You are cordially invited to attend a special meeting of the stockholders of CSG Systems International, Inc. (“CSG”). The special meeting will be held online on [•], 2026 at [•], Eastern Time (the “special meeting”). You may attend the meeting virtually via the internet at www.virtualshareholdermeeting.com/CSGS2026SM, where you will be able to vote electronically and submit questions. You will need the 16-digit control number, which is included in your notice of internet availability of proxy materials (“notice of internet availability”), on your proxy card or in the instructions accompanying your proxy materials, to attend the special meeting. You will not be able to attend the meeting in person.

At the special meeting, CSG stockholders will be asked to consider and vote on a proposal to adopt the Agreement and Plan of Merger, dated as of October 29, 2025 (as amended or modified from time to time, the “merger agreement”), among CSG, NEC Corporation (“Parent”), and Canvas Transaction Company, Inc., a direct or indirect wholly owned subsidiary of Parent (“Merger Sub”). Subject to the terms and conditions of the merger agreement, Merger Sub will be merged with and into CSG, the separate existence of Merger Sub will cease, and CSG will survive the merger as a wholly owned subsidiary of Parent (the “merger”).

If the merger is completed, CSG stockholders will have the right to receive $80.70 in cash, without interest and subject to any applicable withholding taxes, for each share of common stock, par value $0.01 per share, of CSG (“CSG common stock”), other than excluded shares and dissenting shares (each as defined in the accompanying proxy statement), that they own immediately prior to the effective time of the merger, which represents a premium of approximately 17.4% over CSG’s closing stock price on October 28, 2025, the last trading day prior to the announcement of the merger agreement, and a premium of approximately 23.1% over the volume-weighted average price of $65.57 for the 30-trading day period ending on October 28, 2025. Approval of the proposal to adopt the merger agreement requires the affirmative vote (in person or by proxy) of the holders of a majority of the outstanding shares of CSG common stock entitled to vote as of the close of business on the record date (as defined in the accompanying proxy statement).

CSG common stock is listed on the Nasdaq Global Select Market (“Nasdaq”) under the symbol “CSGS”. The closing price of CSG common stock on Nasdaq on [•], 2025, the latest practicable date before the printing of the accompanying proxy statement, was $[•] per share.

The CSG board of directors (the “CSG Board”) has reviewed and considered the terms and conditions of the merger and has unanimously (a) determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable, fair to and in the best interests of CSG and its stockholders, and declared it advisable, fair to and in the best interests of CSG to enter into the merger agreement with Parent and Merger Sub providing for the merger in accordance with the DGCL (as defined in the accompanying proxy statement), (b) approved the merger, merger agreement and the transactions contemplated thereby in accordance with the DGCL and (c) recommended that the merger and merger agreement be adopted by CSG stockholders. The CSG Board made its determination after consultation with its outside legal counsel and its financial advisor and consideration of various factors, as more fully described in the accompanying proxy statement.

The CSG Board unanimously recommends that you vote “FOR” the proposal to adopt the merger agreement.

At the special meeting, stockholders will also be asked to vote on (a) a proposal to approve, on a non-binding, advisory basis, the compensation that may be paid or become payable to the named executive officers of CSG in connection with the consummation of the merger (the “advisory compensation proposal”), and (b) a proposal to adjourn the special meeting from time to time, as determined by the CSG Board, including for the purpose of

soliciting additional votes for the approval of the merger proposal if there are insufficient votes at the time of the special meeting to approve the proposal to adopt the merger agreement by CSG stockholders (the “adjournment proposal”). The CSG Board unanimously recommends that you vote “FOR” each of these proposals.

The CSG Board is soliciting your proxy to ensure that a quorum is present and that your shares are represented and voted at the special meeting and any postponement or adjournment thereof.

If your shares are held in “street name,” you should instruct your broker, bank or other nominee how to vote your shares on each proposal in accordance with your voting instruction form.

The merger cannot be completed unless CSG stockholders adopt the merger agreement. Your vote is very important, regardless of the number of shares you own. Whether or not you expect to attend the special meeting online, please submit a proxy to vote your shares as promptly as possible to ensure that your shares may be represented and voted at the special meeting. If you receive more than one proxy card because you own shares registered in different names or addresses, each proxy should be submitted. If you attend the special meeting and vote online, your online vote will revoke any proxy previously submitted. If you neither return your proxy nor attend the special meeting online, your shares will not be counted for purposes of determining whether a quorum is present at the special meeting and will have the same effect as a vote “AGAINST” the adoption of the merger agreement. Similarly, if you hold your shares in “street name” and fail to instruct your broker, bank or other nominee how to vote your shares, your shares will not be counted for purposes of determining whether a quorum is present and will have the same effect as a vote “AGAINST” the adoption of the merger agreement.

The obligations of CSG, Parent and Merger Sub to complete the merger are subject to the satisfaction or waiver of certain conditions. The accompanying proxy statement contains detailed information about CSG, the special meeting, the merger agreement, the merger, the advisory compensation proposal and the adjournment proposal. A copy of the merger agreement is attached as Annex A to the accompanying proxy statement and incorporated therein by reference. CSG urges you to, and you should, read the entire proxy statement carefully, including the merger agreement and the other annexes and the documents referred to or incorporated by reference in the accompanying proxy statement. You may obtain additional information about CSG from documents it has filed with the U.S. Securities and Exchange Commission.

If you have any questions or need assistance voting your shares of CSG common stock, please contact Innisfree M&A Incorporated, CSG’s proxy solicitor, by calling toll-free, 888-750-5830. Banks and brokers call 212-750-5833.

Neither the U.S. Securities and Exchange Commission nor any state securities regulatory agency has approved or disapproved of the merger, passed upon the merits of the merger agreement or the merger or determined if the accompanying proxy statement is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying proxy statement is dated [•], 2025 and, together with the enclosed form of proxy card, is first being mailed to CSG stockholders on or about [•], 2025.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES YOU OWN. WHETHER OR NOT YOU EXPECT TO ATTEND THE SPECIAL MEETING ONLINE, PLEASE SUBMIT A PROXY TO VOTE YOUR SHARES OVER THE INTERNET OR BY TELEPHONE PURSUANT TO THE INSTRUCTIONS CONTAINED IN THESE MATERIALS OR COMPLETE, DATE, SIGN AND RETURN A PROXY CARD AS PROMPTLY AS POSSIBLE TO ENSURE THAT YOUR SHARES MAY BE REPRESENTED AND VOTED AT THE SPECIAL MEETING. IF YOU RECEIVE MORE THAN ONE PROXY CARD BECAUSE YOU OWN SHARES REGISTERED IN DIFFERENT NAMES OR ADDRESSES, EACH PROXY SHOULD BE SUBMITTED. IF YOU ATTEND THE SPECIAL MEETING AND VOTE ONLINE, YOUR ONLINE VOTE WILL REVOKE ANY PROXY PREVIOUSLY SUBMITTED. IF YOU NEITHER RETURN YOUR PROXY NOR ATTEND THE SPECIAL MEETING ONLINE, YOUR SHARES WILL NOT BE COUNTED FOR PURPOSES OF DETERMINING WHETHER A QUORUM IS PRESENT AT THE SPECIAL MEETING AND WILL HAVE THE SAME EFFECT AS A VOTE “AGAINST” THE ADOPTION OF THE MERGER AGREEMENT. SIMILARLY, IF YOU HOLD YOUR SHARES IN “STREET NAME” AND FAIL TO INSTRUCT YOUR BROKER, BANK OR OTHER NOMINEE HOW TO VOTE YOUR SHARES, YOUR SHARES WILL NOT BE COUNTED FOR PURPOSES OF DETERMINING WHETHER A QUORUM IS PRESENT AND WILL HAVE THE SAME EFFECT AS A VOTE “AGAINST” THE ADOPTION OF THE MERGER AGREEMENT.

Your proxy may be revoked at any time before the vote at the special meeting by following the procedures outlined in the accompanying proxy statement.

In order to vote online and examine the list of stockholders entitled to vote at the special meeting, you will need to log onto www.virtualshareholdermeeting.com/CSGS2026SM and enter the 16-digit control number, which is included in your notice of internet availability, on your proxy card or in the instructions accompanying your proxy materials. If your shares of CSG common stock entitled to vote are registered directly in your name, you are considered the holder of record with respect to such shares of CSG common stock and you have the right to attend the special meeting and vote online.

If your shares of CSG common stock entitled to vote are held in a brokerage account or by a bank or other nominee, you are the beneficial owner of such CSG common stock. As such, in order to vote online at the special meeting, you must follow the instructions provided by your bank, brokerage firm or nominee.

The proxy statement of which this notice forms a part provides a detailed description of the merger, the merger agreement, the advisory compensation proposal and the adjournment proposal, and provides specific information concerning the special meeting. CSG urges you to read the proxy statement, including any documents incorporated

therein by reference, and its annexes carefully and in their entirety. If you have any questions concerning the merger or the proxy statement, would like additional copies of the proxy statement or need help voting your shares of CSG common stock, please contact CSG’s proxy solicitor, Innisfree M&A Incorporated by calling, toll-free, 888-750-5830. Banks and brokers call 212-750-5833.

The following are brief answers to certain questions that you may have regarding the merger, the special meeting and the proposals being considered at the special meeting. CSG urges you to carefully read the remainder of this proxy statement because the information in this section does not provide all of the information that might be important to you with respect to the merger and the special meeting. Additional important information is also contained in the annexes attached to this proxy statement and the documents referred to or incorporated by reference into this proxy statement.

This proxy statement contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Forward-looking statements include, but are not limited to, statements concerning CSG’s expectations, plans, intentions, strategies or prospects with respect to the merger. These statements are often identified by the use of words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “hope,” “hopeful,” “likely,” “may,” “optimistic,” “possible,” “potential,” “preliminary,” “project,” “should,” “will,” “would” or the negative or plural of these words or similar expressions or variations. Forward-looking statements are made based upon management’s current expectations and beliefs and are not guarantees of future performance. Such forward-looking statements are subject to a number of risks, uncertainties, assumptions and other factors that could cause actual results and the timing of certain events to differ materially from future results expressed or implied by the forward-looking statements. These factors include, among others: (i) the ability of the parties to complete the merger on the anticipated terms and timing, or at all, (ii) the satisfaction or waiver of other conditions to the completion of the merger, including obtaining required shareholder and regulatory approvals; (iii) the risk that CSG’s stock price may fluctuate during the pendency of the merger and may decline if the merger is not completed; (iv) potential litigation relating to the merger that could be instituted against CSG or its directors, managers or officers, including the delay, expense or other effects of any outcomes related thereto; (v) the risk that disruptions from the merger will harm CSG’s business, including current plans and operations, including during the pendency of the merger; (vi) the ability of CSG to retain, motivate, and hire key personnel; (vii) the diversion of management’s time and attention from ordinary course business operations to completion of the merger and integration matters; (viii) potential adverse reactions or changes to business relationships resulting from the announcement, pendency or completion of the merger; (ix) legislative, regulatory and economic developments; (x) potential business uncertainty, including changes to existing business relationships, during the pendency of the merger that could affect CSG’s financial performance; (xi) certain restrictions during the pendency of the merger that may impact CSG’s ability to pursue certain business opportunities or strategic transactions; (xii) unpredictability and severity of catastrophic events, including but not limited to acts of terrorism, outbreaks of war or hostilities or global pandemics, as well as management’s response to any of the aforementioned factors; (xiii) the possibility that the merger may be more expensive to complete than anticipated, including as a result of unexpected factors or events; (xiv) unexpected costs, liabilities or delays associated with the transaction; (xv) the response of competitors to the transaction; (xvi) the occurrence of any event, change or other circumstance that could give rise to the termination of the merger, including in circumstances requiring CSG to pay a termination fee; (xvii) the ability to realize the anticipated benefits of the merger, including the expected synergies and cost saving; (xviii) the possibility that competing or superior acquisition proposals for CSG will be made; and (xix) other risks set forth under the heading “Risk Factors,” of CSG’s Annual Report on Form 10-K for the year ended December 31, 2024, CSG’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, and in CSG’s subsequent filings with the Securities and Exchange Commission (“SEC”). You should not rely upon forward-looking statements as predictions of future events. Actual results and outcomes could differ materially from the results described in or implied by such forward looking statements. Forward-looking statements speak only as of the date hereof, and, except as required by law, CSG undertakes no obligation to update or revise these forward-looking statements.

CSG is a leader in innovative customer engagement, revenue management, and payments solutions that make ordinary customer experiences extraordinary. Our cloud-first architecture and customer-obsessed mindset help companies around the world launch new digital services, expand into new markets, and create dynamic experiences that capture new customers and build brand loyalty. For over 40 years, CSG’s technologies and people have helped some of the world’s most recognizable brands solve their toughest business challenges and evolve to meet the demands of today’s digital economy with future-ready solutions that drive exceptional customer experiences. Industry leaders in telecom, broadband cable, media, retail, healthcare, financial services, insurance, government, and other industries leverage the power of our technology to compete and win in the digital age. Our approximately 5,700-plus employees around the globe have made CSG a trusted technology leader and SaaS platform provider to some of the biggest and most innovative brands around the world.

CSG common stock is traded on Nasdaq under the ticker symbol “CSGS”.

CSG’s principal executive offices are located at 169 Inverness Dr W, Suite 300, Englewood, CO 80112, and CSG’s telephone number is (303) 200-2000. CSG’s corporate web address is https://www.csgi.com. The information provided on CSG’s website is not part of this proxy statement and is not incorporated in this proxy statement by reference or by any other reference to CSG’s website provided in this proxy statement.

Additional information about CSG is contained in its public filings with the SEC, which filings are incorporated by reference herein. See the section of this proxy statement entitled “Where You Can Find Additional Information” beginning on page 94.

NEC is a Japanese information technology company and was established on July 17, 1899. NEC and its group entities leverage technology to create social value and promote a more sustainable world where everyone has the chance to reach their full potential. The NEC group’s approximately 110,000 employees utilize world-leading AI, security, and communications technologies to solve the most pressing needs of customers and society.

Merger Sub is a direct or indirect wholly owned subsidiary of Parent and was formed on October 23, 2025, solely for the purpose of engaging in transactions of the nature contemplated by the merger agreement and has not engaged in any business activities other than as incidental to its formation and the maintenance of its existence and in connection with the transactions contemplated by the merger agreement. Upon the consummation of the merger, the separate corporate existence of Merger Sub will cease and CSG will continue as the surviving corporation and as a wholly owned subsidiary of Parent.

This proxy statement is being provided to CSG stockholders as part of a solicitation by the CSG Board for proxies for use at the special meeting, to be held at the time and place specified below, and at any properly convened meeting following an adjournment or postponement of the special meeting.

The special meeting is scheduled to be held online via live audio webcast at [•] on [•], 2026 at www.virtualshareholdermeeting.com/CSGS2026SM, Eastern Time. The special meeting will be held in a virtual meeting format only, with no physical in-person meeting.

At the special meeting, CSG stockholders will be asked to consider and vote on the following proposals:

The adoption of the merger agreement by the affirmative vote of holders of a majority of the outstanding shares of CSG common stock entitled to vote as of the close of business on the record date is a condition to the completion of the merger. If CSG stockholders fail to approve the merger proposal, the merger will not occur.

The vote on the advisory compensation proposal is a vote separate and apart from the vote to approve the merger proposal. Accordingly, a stockholder may vote to approve the merger proposal and vote not to approve the advisory compensation proposal, and vice versa. Because the vote on the advisory compensation proposal is only advisory in nature, it will not be binding on CSG, Parent or the surviving corporation. Accordingly, because CSG is contractually obligated to pay such merger-related compensation, the compensation will be payable, subject only to the conditions applicable thereto, if the merger proposal is approved, regardless of the outcome of the advisory vote.

Other than the matters described above, CSG does not expect a vote to be taken on any other matters at the special meeting or any adjournment or postponement thereof.

The CSG Board has reviewed and considered the terms of the merger and has unanimously (a) determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable, fair to and in the best interests of CSG and its stockholders, and declared it advisable, fair to and in the best interests of CSG to enter into the merger agreement with Parent and Merger Sub providing for the merger in accordance with the DGCL (as defined in the accompanying proxy statement), (b) approved the merger, merger agreement and the transactions contemplated thereby in accordance with the DGCL and (c) recommended that the merger and merger agreement be adopted by CSG stockholders. Certain factors considered by the CSG Board in reaching its decision to adopt the merger agreement can be found in the section of this proxy statement entitled “The Merger Proposal (Proposal 1)—Recommendation of the CSG Board and Reasons for the Merger” beginning on page 40.

The CSG Board unanimously recommends that CSG stockholders vote “FOR” the merger proposal, “FOR” the advisory compensation proposal and “FOR” the adjournment proposal.

Only holders of record of CSG common stock at the close of business on [•], [•], the record date for the special meeting, will be entitled to notice of, and to vote at, the special meeting or any adjournments or postponements of the special meeting.

Holders of record of CSG common stock are entitled to one vote for each share of CSG common stock they own of record at the close of business on the record date. At the close of business on the record date, there were [•] shares of CSG common stock issued and outstanding, held by approximately [•] holders of record.

Under CSG’s bylaws, the presence, in person or represented by proxy, at the special meeting of a majority of the issued and outstanding shares of CSG common stock entitled to vote thereat at the close of business on the record date will constitute a quorum. Virtual attendance at the special meeting constitutes presence in person for purposes of a quorum at the special meeting. There must be a quorum for business (other than the adjournment proposal) to be conducted at the special meeting. If a quorum is not present or represented by proxy, then the chair of the special meeting may adjourn the special meeting from time to time until a quorum is present or represented by proxy. Failure of a quorum to be represented at the special meeting will necessitate an adjournment of the special meeting and may subject CSG to additional expense.

If you attend the special meeting or if you submit (and do not thereafter revoke) a proxy by duly executing and returning a proxy card or by telephone or through the internet, even if you abstain from voting, your shares of CSG common stock will be counted for purposes of determining whether a quorum is present at the special meeting. In the event that a quorum is not present at the special meeting or additional votes must be solicited to adopt the merger agreement, the special meeting may be adjourned or postponed to solicit additional proxies.

The approval of the merger proposal requires the affirmative vote of the holders of a majority of the outstanding shares of CSG common stock entitled to vote as of the close of business on the record date.

Assuming a quorum is present, approval of the advisory compensation proposal (on a non-binding basis) requires the affirmative vote of the holders of a majority of the shares of CSG common stock present in person or represented by proxy at the special meeting and entitled to vote thereon.

Approval of the adjournment proposal requires the affirmative vote of the holders of a majority of the shares of CSG common stock present in person or represented by proxy at the online special meeting and entitled to vote thereon.

An abstention occurs when a stockholder attends a meeting, either in person or by proxy, but abstains from voting. At the special meeting, abstentions will be counted as present for purposes of determining whether a quorum is present. Abstaining from voting will have the same effect as a vote “AGAINST” the merger proposal, the advisory compensation proposal and the adjournment proposal.

If no instruction as to how to vote is given (including no instruction to abstain from voting) in an executed, duly returned and not revoked proxy, the proxy will have the same effect as a vote “FOR” the merger proposal, the advisory compensation proposal and the adjournment proposal.

Broker non-votes are shares held in “street name” by brokers, banks and other nominees that are present in person or represented by proxy at the special meeting, but with respect to which the broker, bank or other nominee is not instructed by the beneficial owner of such shares how to vote on a particular proposal and such broker, bank or other nominee does not have discretionary voting power on such proposal. Pursuant to the NYSE rules, which also govern brokers’ use of discretionary authority for Nasdaq-listed companies, brokers, banks and other nominees holding shares in “street name” do not have discretionary voting authority with respect to any of the three proposals described in this proxy statement, if a beneficial owner of shares of CSG common stock held in “street name” does not give voting instructions to the broker, bank or other nominee, then those shares will not be counted as present in person or represented by proxy at the online special meeting. As the vote to approve the merger proposal is based on the total number of shares of CSG common stock outstanding at the close of business on the record date, not just the shares that are counted as present in person or represented by proxy at the online special meeting, if you fail to issue voting instructions to your broker, bank or other nominee, it will have the same effect as a vote “AGAINST” the merger proposal. If you fail to issue voting instructions to your broker, bank or other nominee, it will have no effect on the outcome of the advisory compensation proposal or the adjournment proposal.

If you are a stockholder of record and you do not attend the special meeting, sign and return your proxy card by mail or submit your proxy by telephone or over the internet, your shares will not be voted at the special meeting, will not be counted as present in person or represented by proxy at the online special meeting and will not be counted as present for purposes of determining whether a quorum is present.

As discussed above, under the NYSE rules, which also govern brokers’ use of discretionary authority for Nasdaq-listed companies, brokers and other record holders do not have discretionary voting authority with respect to any of the three proposals described in this proxy statement. Accordingly, if you are the beneficial owner of shares held in “street name” and you do not issue voting instructions to your broker, bank or other nominee, your shares will not be voted at the special meeting and will not be counted as present in person or represented by proxy at the online special meeting or counted as present for purposes of determining whether a quorum is present.

A failure to submit a proxy or otherwise attend and vote your shares at the online special meeting will have no effect on the outcome of the advisory compensation proposal (assuming a quorum is present) or the adjournment proposal. The vote to approve the merger proposal, however, is based on the total number of shares of CSG common stock outstanding at the close of business on the record date, not just the shares that are counted as present in person or represented by proxy at the online special meeting. As a result, if you fail to vote your shares, it will have the same effect as a vote “AGAINST” the merger proposal.

If your shares are registered directly in your name with CSG’s transfer agent, you are considered a “stockholder of record.” Stockholders of record can vote their shares of CSG common stock in the following four ways:

Even if you plan to attend the special meeting, you are encouraged to submit a proxy in advance by internet, telephone or mail to ensure that your shares will be represented and voted at the special meeting if you later decide not to attend the special meeting. Telephone and internet facilities for the submission of a proxy to vote shares will be available 24 hours a day and will close at 11:59 p.m., Eastern Time on [•], 2026. Proxy cards must be received no later than [•], 2026 in order to ensure that your shares are voted.

If your shares are held by your broker, bank or other nominee, you are considered the beneficial owner of shares held in “street name” and you will receive a form from your broker, bank or other nominee seeking instruction from you as to how your shares should be voted. You should instruct your broker, bank or other nominee how to vote your shares on each proposal in accordance with your voting instruction form. If you beneficially own your shares and receive a voting instruction form, you can vote by following the instructions on your voting instruction form. Please refer to information from your bank, broker or other nominee on how to submit voting instructions.

Stockholders who are entitled to vote at the special meeting (and their duly appointed proxies) may attend the special meeting. You will need the 16-digit control number, which is included in your notice of internet availability,

on your proxy card or voting instruction form, to be able to vote or ask questions during the special meeting. If you are an CSG stockholder as of the record date (or a proxy thereof), you should enter your control number and follow the prompt to log in.

We encourage you to access the virtual special meeting website 15 minutes prior to the start of the special meeting to check-in online. We will have technicians ready to assist you with any technical difficulties you may have accessing the live webcast of the special meeting. A technical support phone number will be posted on www.virtualshareholdermeeting.com/CSGS2026SM if you experience technical difficulties during the check-in process or during the webcast.

You can change or revoke your proxy at any time before the final vote at the special meeting. If you are the stockholder of record, you may change or revoke your proxy by:

If you hold shares in “street name,” you may submit new voting instructions by contacting your bank, broker or other nominee. You may also change your vote at the online special meeting.

If you submit a proxy or provide instructions to vote your shares and do not thereafter revoke such proxy or change such instructions in accordance with one of the methods set forth above, your shares will be represented and voted at the special meeting in accordance with your instructions. Attendance at the online special meeting will not, in and of itself, result in the revocation of a proxy or cause your shares of CSG common stock to be voted.

The CSG Board is soliciting your proxy, and CSG will bear the cost of soliciting proxies. Innisfree has been retained to assist with the solicitation of proxies. Innisfree will be paid a fee of up to $[•], plus certain additional per-service fees, and will be reimbursed for certain fees and expenses for these and other advisory services in connection with the special meeting. Solicitation initially will be made by mail. Forms of proxies and proxy materials may also be distributed through brokers, banks and other nominees to the beneficial owners of shares of CSG common stock, in which case these parties will be reimbursed for their reasonable out-of-pocket expenses. Proxies may also be solicited in person or by telephone, facsimile, electronic mail, or other electronic medium by Innisfree or, without additional compensation, by certain of CSG’s directors, officers and employees.

In addition to the merger proposal and the advisory compensation proposal, CSG stockholders are also being asked to approve the adjournment proposal, which will enable the adjournment of the special meeting from time to time, as determined in accordance with the merger agreement by the CSG Board, including for the purpose of soliciting additional votes in favor of the merger proposal if there are not sufficient votes at the time of the special meeting to approve the merger proposal. If a quorum is not present, the presiding officer at the special meeting may adjourn the special meeting from time to time until a quorum is present. If the adjournment is for more than 30 days, or if, after the adjournment, a new record date is fixed for the adjourned special meeting, a notice of the adjourned special meeting will be given to each stockholder of record entitled to vote at the special meeting. In addition, the special meeting could be postponed before it commences, subject to the terms of the merger agreement. If the special meeting is adjourned or postponed, stockholders who have already submitted their proxies will be able to revoke them at any time prior to the final vote on the proposals. If you return a proxy and do not indicate how you wish to vote on the adjournment proposal, your shares will be voted in favor of the adjournment proposal.

The CSG Board unanimously recommends a vote “FOR” the adjournment proposal, if necessary, to solicit additional proxies.

You should not send documents representing CSG common stock with the proxy card. If the merger is completed, the paying agent for the merger will send you transmittal materials and instructions for exchanging any of your certified shares of CSG common stock for the consideration to be paid to former CSG stockholders in connection with the merger.

If you have more questions about the merger or how to submit your proxy, or if you need additional copies of this proxy statement or the enclosed proxy card or voting instructions, please contact Innisfree, CSG’s proxy solicitor, by calling, toll free, 888-750-5830. Banks and brokers call 212-750-5833.

CSG stockholders are being asked to approve a proposal to adopt the merger agreement, pursuant to which, subject to the terms and conditions set forth therein, and in accordance with the DGCL, Merger Sub will be merged with and into CSG, the separate corporate existence of Merger Sub will thereupon cease, and CSG will survive the merger as a wholly owned subsidiary of Parent.

The affirmative vote of the holders of a majority of the outstanding shares of CSG common stock entitled to vote as of the close of business on the record date to adopt the merger agreement at the special meeting is a condition to the completion of the merger. If CSG stockholders fail to approve the merger proposal, the merger will not occur.

The CSG Board unanimously recommends that CSG stockholders vote “FOR” the merger proposal.

The discussion of the merger in this proxy statement is qualified in its entirety by reference to the merger agreement, a copy of which is attached to this proxy statement as Annex A and is hereby incorporated by reference into this proxy statement.

Subject to the terms and conditions of the merger agreement and in accordance with the DGCL, if the merger is completed, then at the effective time, Merger Sub will merge with and into CSG, the separate corporate existence of Merger Sub will cease, and CSG will survive the merger as a wholly owned subsidiary of Parent.

Upon the terms and subject to the conditions of the merger agreement, at the effective time, CSG stockholders will have the right to receive $80.70 in cash, without interest and subject to any applicable withholding taxes, for each share of CSG common stock that they own that is issued and outstanding immediately prior to the effective time of the merger (other than excluded shares and dissenting shares, each as described in the merger agreement). After the merger is completed, CSG stockholders will have only the right to receive a cash payment in respect of their shares of CSG common stock, and will no longer have any rights as CSG stockholders, including voting or other rights.

Any excluded shares outstanding as of immediately prior to the effective time will be cancelled and retired without any conversion thereof or consideration paid therefor at the effective time by virtue of the merger.

Pursuant to the merger agreement, effective as of the effective time, outstanding CSG equity awards will be treated as follows:

In addition, pursuant to the merger agreement, CSG equity awards granted in 2023 that would have completed their full vesting period and been settled in accordance with their terms in 2026 will vest and settle on or prior to December 31, 2025, with any applicable performance-based vesting conditions deemed achieved based on actual performance as of the latest practicable date.

Beginning on the date of the merger agreement, no purchase period under the CSG ESPP has commenced or will commence, no new participants have joined or may join the CSG ESPP, and no participant has increased or may increase the amount of his or her payroll deductions with respect to the CSG ESPP. The CSG ESPP will terminate in its entirety on the closing and no further rights will be granted or exercised under the CSG ESPP thereafter.

If the merger proposal is not approved by CSG stockholders, or if the merger is not completed for any other reason, CSG stockholders will not receive any payment for their shares of CSG common stock in connection with the merger. Instead, CSG will remain an independent public company and shares of CSG common stock will continue to be listed and traded on Nasdaq. In addition, if the merger is not completed, CSG expects that management will operate CSG’s business in a manner similar to that in which it is being operated today and that CSG stockholders will continue to be subject to the same risks and opportunities to which they are currently subject, including, without limitation, risks related to the competitive industries in which CSG operates and adverse economic conditions. Furthermore, if the merger is not completed, and depending on the circumstances that would have caused the merger not to be completed, it is likely that the price of CSG common stock will decline significantly. If that were to occur, it is uncertain when, if ever, the price of CSG common stock would return to the price at which it trades as of the date of this proxy statement.

Accordingly, if the merger is not completed, there can be no assurance as to the effect of these risks and opportunities on the future value of your shares of CSG common stock. If the merger proposal is not approved by CSG stockholders or if the merger is not completed for any other reasons, there can be no assurance that any other transaction acceptable to CSG will be offered or that CSG’s business, prospects or results of operation will not be adversely impacted.

CSG may be required to pay Parent a termination fee of $82,000,000 if the merger agreement is terminated under certain specified circumstances pursuant to the terms and conditions of the merger agreement, and Parent may be required to pay CSG a fee of $135,000,000 if the merger agreement is terminated under other specified circumstances pursuant to the terms and conditions of the merger agreement. See the section of this proxy statement entitled “The Merger Agreement—Termination Fee” beginning on page 82 for a discussion of the circumstances under which CSG or Parent will be required to pay a termination fee.

The CSG Board and management team regularly review CSG’s financial performance, industry conditions, future growth prospects and overall strategic direction. As part of this assessment, the CSG Board and CSG’s management regularly consider potential opportunities to strengthen the business and enhance stockholder value, including by evaluating and weighing the continued execution of CSG’s strategy as a standalone public company against possible strategic opportunities, including acquisitions, dispositions, commercial partnerships or combinations with third parties.

Over the past several years, the CSG Board and management team from time to time have had preliminary discussions concerning potential transactions with strategic acquirors, private equity sponsors and other third parties. Other than one unsolicited proposal received in 2022 from a third party, who did not pursue further discussions or submit a revised proposal after the CSG Board concluded and communicated that such proposal was not in the best interests of CSG and its stockholders, no such discussions have resulted in any specific proposal on price, structure or other material terms.

In furtherance of its consideration of potential strategic alternatives, the CSG Board and management have retained and held discussions with representatives of Jefferies from time to time based on Jefferies’ experience and expertise as a financial advisor in a wide variety of transactions, as well as Jefferies’ qualifications and experience advising, and familiarity with, companies operating in the industries in which CSG operates. In addition, CSG has also from time to time been advised by Simpson Thacher & Bartlett LLP (“Simpson Thacher”) as its outside legal counsel in connection with the evaluation of various strategic alternatives and other matters. CSG worked with representatives of Jefferies and Simpson Thacher throughout the course of the events described below.

On January 29, 2025, it was reported by a news source that NEC was considering the possibility of making an offer to acquire CSG. At the close of business on January 28, 2025, the previous trading day, the closing price of CSG common stock was $56.44 per share. At such time, CSG had not received any offer or other communications from NEC or any other party with respect to an acquisition proposal.

Several months later, the Chief Executive Officer of Netcracker requested a dinner meeting with Brian Shepherd, the Chief Executive Officer of CSG, on May 14, 2025. At the meeting, Mr. Shepherd was introduced to certain senior management members of NEC, namely Masakazu Yamashina, Corporate Senior Executive Vice President and Co-Chief Operating Officer of NEC, and Hidetoshi Uriu, Chief Investment Officer of NEC, who expressed an interest in a potential acquisition of CSG, and noted the potential benefits of the acquisition to both parties. No formal indication of interest was made with respect to such potential acquisition and no valuation was discussed.

On May 22, 2025, CSG received a non-binding written indication of interest from NEC (the “May Proposal”) regarding a potential acquisition of 100% of the common stock of CSG for $74.00 per share in cash, subject to a number of conditions, including completion of NEC’s due diligence review of CSG and finalization of definitive agreements for the proposed transaction. The May Proposal represented a premium of 15.7% to the closing price of CSG common stock on the previous trading day, May 21, 2025, and a premium of 31.1% to the closing price of CSG common stock on January 28, 2025, the trading day immediately prior to the news story that NEC was considering the possibility of making an offer to acquire CSG. The May Proposal was shared with the CSG Board and representatives of Jefferies and Simpson Thacher later that day.

On May 22, 2025, the CSG Board held a special meeting to discuss the May Proposal. At the meeting, representatives of Simpson Thacher provided an overview of the directors’ fiduciary duties under applicable law in connection with their evaluation of strategic alternatives for CSG, including a potential sale. The CSG Board discussed the May Proposal and discussed and determined to engage Jefferies to conduct financial analyses of any proposal or proposed transaction (and the terms and conditions thereof), to assist CSG in negotiations and to help the CSG Board evaluate strategic alternatives based on the factors described above, among others. The CSG Board instructed the management team to negotiate the terms of these engagements. Following the meeting, at the direction of the CSG Board, Mr. Shepherd sent a response to representatives of NEC confirming receipt of the May Proposal.

On May 22, 2025, the CSG Board directed the senior management team to update certain five-year financial projections for the 2025 through 2029 fiscal years that the CSG Board had approved in November 2024, to incorporate actual results through April 2025 as well as the May 2025 forecast (the “Preliminary Management

Projections – Base Case”) and to provide the Preliminary Management Projections – Base Case to representatives of Jefferies in connection with Jefferies’ preliminary financial analysis. On May 26, 2025, CSG’s senior management team provided to representatives of Jefferies the Preliminary Management Projections – Base Case.

On May 28, 2025, at the direction of the CSG Board, representatives of Jefferies notified representatives of The Goldman Sachs Group, Inc. (“Goldman Sachs”), financial advisor to NEC, that the CSG Board was reviewing the May Proposal and that formal feedback would be provided following the CSG Board’s review of the May Proposal in conjunction with its advisors.

On May 29, 2025, Mr. Shepherd spoke with Mr. Yamashina to reiterate that the CSG Board was continuing to evaluate the May Proposal and that formal feedback would be provided following such process.

On June 12, 2025, as authorized by the CSG Board, CSG entered into an engagement letter with Jefferies, which provided for Jefferies to act as lead financial advisor to CSG in connection with CSG’s consideration of the proposed transaction and potential strategic alternatives.

On June 13, 2025, the CSG Board held a special meeting to further discuss the May Proposal with members of CSG senior management and representatives of Jefferies and Simpson Thacher in attendance. At the meeting, the CSG Board discussed with members of CSG senior management and CSG’s advisors the May Proposal, as well as certain regulatory matters, including deal protections related to a potential transaction with NEC. Representatives of Jefferies reviewed with the CSG Board Jefferies’ preliminary financial analysis of the May Proposal and a list of third parties that might have strategic interest in a transaction with CSG based on their respective business profiles. The CSG Board discussed with its advisors the merits and drawbacks of conducting a “market check” to determine if any such third parties might have an interest in a strategic transaction with CSG at such time. Members of the CSG Board and its advisors discussed each of the identified potential acquirors and concluded, based on their business insights and the CSG Board’s discussions with its advisors, that none of such parties were likely to have an interest in pursuing a strategic transaction with CSG at such time or in the near future, given the size of transaction and strategic priorities, or be able to offer the same combination of value and transaction certainty that NEC could offer. After further discussion regarding the May Proposal, the CSG Board concluded that, while it was conceivable that NEC could ultimately propose a transaction that would be compelling, the May Proposal was less attractive than CSG’s standalone business plans and long-term value prospects. The CSG Board then instructed representatives of Jefferies to convey to NEC, on behalf of CSG, that NEC would need to increase its proposed price and provide assurances regarding regulatory protections to move forward and that, for purposes of facilitating such a revised proposal, the CSG Board was willing to permit meetings among each party’s legal counsel. On June 16, 2025, representatives of Jefferies spoke with representatives of Goldman Sachs to convey such message and, following such discussion between representatives of Jefferies and representatives of Goldman Sachs, Mr. Shepherd sent an email to representatives of NEC also conveying such message.

On June 19, 2025, representatives of Simpson Thacher and representatives of Freshfields LLP (“Freshfields”), legal advisor to NEC, attended an introductory meeting by videoconference to discuss the CSG Board’s feedback on the May Proposal. During the meeting, representatives of Simpson Thacher and Freshfields discussed and agreed that their respective regulatory teams would discuss the regulatory analysis related to a proposed transaction between NEC and CSG. On June 20, 2025, representatives of Simpson Thacher and Freshfields held a meeting by videoconference to discuss the regulatory analysis and related legal terms to be included in the transaction documentation.

Over the course of the remainder of June and early July 2025, Simpson Thacher’s and Freshfields’ respective regulatory teams continued to gather facts pertaining to the regulatory analysis and held additional meetings to discuss such regulatory analysis.

On July 11, 2025, representatives of Simpson Thacher, on behalf of CSG, sent to representatives of Freshfields, on behalf of NEC, a draft term sheet setting forth a proposal regarding certain key terms of the proposed transaction, including the efforts that the parties would be required to take in order to obtain required regulatory approvals with respect to any potential transaction, as well as proposed constructs for the termination date and regulatory termination fee.

On July 14, 2025, representatives of Freshfields sent to representatives of Simpson Thacher a revised draft of the term sheet, proposing, among other things, a regulatory termination fee of $100 million. Such revised draft was shared with the CSG Board later that day. Substantially concurrently, certain representatives of NEC communicated to Mr. Shepherd via email that NEC wished to reiterate its proposed purchase price of $74.00 per share in cash.

On July 15, 2025, Mr. Shepherd spoke with Mr. Yamashina and other members of NEC management. During such discussion, NEC management expressed the view that significant progress had been made on the draft term sheet and that NEC was interested in further discussions around CSG’s business, operations and financial outlook to determine if NEC could present CSG with a more compelling proposal. On July 16, 2025, at the direction of the CSG Board, Mr. Shepherd notified members of NEC management that CSG would be willing to enter into a mutual confidentiality agreement with NEC to facilitate such discussions and the sharing of certain non-public information related thereto on a limited basis to support the submission of a revised proposal.

Between July 17 and July 24, 2025, representatives of Simpson Thacher and representatives of Freshfields negotiated and finalized the terms of an initial mutual confidentiality agreement, and CSG and NEC entered into such agreement on July 24, 2025. Following execution of the confidentiality agreement, CSG made available certain limited non-public information about CSG’s business and operations to NEC to facilitate its due diligence of CSG.

On July 28, 2025, members of CSG’s and NEC’s respective management teams and representatives of Jefferies and Goldman Sachs met at Simpson Thacher’s offices in Palo Alto to discuss CSG’s business, operations and financial outlook as well as preliminary views on potential synergies that could be achieved in connection with a potential transaction. At such meeting, CSG’s management team discussed CSG’s upcoming second quarter 2025 financial results and provided additional information about the CSG business, including certain financial forecasts based on the Preliminary Management Projections – Base Case and reflecting certain adjustments and upside scenarios (the “Preliminary Additional Projections – Upside Case”). CSG’s management team provided a summary of such meeting to the CSG Board on July 30, 2025.

On July 30, 2025, at the direction of the CSG Board, representatives of Jefferies spoke with representatives of Goldman Sachs to discuss next steps coming out of the July 28 meeting and reemphasize the CSG Board’s feedback regarding the deal price in the May Proposal and the need for a more compelling proposal in order to move forward with additional diligence or discussions.

On August 4, 2025, the CSG Board held a special meeting with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance. At the meeting, the CSG Board discussed with members of CSG senior management and its advisors the status of discussions with NEC, including Jefferies’ preliminary financial analysis and Simpson Thacher’s regulatory analysis. An executive session was held to discuss next steps, during which the CSG Board instructed Mr. Shepherd to respond to NEC and representatives of Jefferies to respond to Goldman Sachs reasserting the need to see a meaningful improvement in the value proposed as well as certain improvements to the regulatory terms reflected in the term sheet. Following the meeting, Mr. Shepherd delivered such message to representatives of NEC. On August 5, 2025, representatives of Jefferies also communicated the CSG Board’s feedback to Goldman Sachs.

On August 11, 2025, NEC representatives orally indicated to Mr. Shepherd that, based on the discussions and diligence conducted to such date, NEC was prepared to explore a transaction at a proposed share price range of $77.00 to $81.00 per share in cash, again subject to a number of conditions including completion of NEC’s due diligence review of CSG and finalization of definitive agreements for the proposed transaction (“August 11 Proposal”). The NEC representatives also provided additional feedback on the term sheet.

On August 12, 2025, the CSG Board held a special meeting to discuss the August 11 Proposal. Mr. Shepherd updated the CSG Board regarding his recent conversations with NEC representatives, and the CSG Board discussed the August 11 Proposal with CSG senior management. Following such discussions, the CSG Board authorized and instructed Mr. Shepherd to have CSG’s advisors deliver a counterproposal to NEC’s advisors of $82.00 per share in cash, which was contingent on the regulatory terms to be proposed in a revised term sheet to be delivered by Simpson Thacher.

On August 13, 2025, representatives of Simpson Thacher sent the revised draft of the term sheet to representatives of Freshfields reflecting the counterproposal of $82.00 per share in cash, as well as certain changes to the regulatory terms, including a regulatory termination fee of 5.25% of CSG’s equity value based on the transaction price.

On August 21, 2025, NEC sent to CSG a further revised proposal reflecting an updated proposed price range of $80.00 to $81.00 per share in cash and certain revisions to the regulatory terms, including a proposed regulatory termination fee of $135,000,000, again subject to a number of conditions including completion of NEC’s due diligence review of CSG and finalization of definitive agreements for the proposed transaction (the “August 21 Proposal”).

Later that day, the CSG Board held a special meeting, with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance, to discuss the August 21 Proposal. Representatives of Simpson Thacher summarized the revised regulatory terms proposed by NEC and indicated that the remaining open items were of the type that could be negotiated between legal advisors in connection with negotiating and finalizing the definitive transaction agreements. Representatives of Jefferies reviewed with the CSG Board the terms of the August 21 Proposal, including NEC’s revised price range. Following such discussion, the CSG Board determined to allow NEC to conduct further diligence with the understanding that the deal price and certain regulatory terms were still under negotiation.

On August 22, 2025, representatives of Jefferies and representatives of Goldman Sachs attended a virtual meeting to discuss the key terms of the August 21 Proposal, coordination on due diligence and draft merger agreement, and other administrative matters. Separately, on the same day, representatives of Simpson Thacher and representatives of Freshfields discussed the key terms of the term sheet, next steps for legal documentation, including an amended and restated non-disclosure agreement (the “A&R NDA”), a clean team agreement and merger agreement, and coordination on due diligence.

On August 22, 2025, representatives of Simpson Thacher sent an initial draft of the A&R NDA to representatives of Freshfields. Representatives of Simpson Thacher and Freshfields exchanged comments on the A&R NDA over the subsequent five days, and the A&R NDA was executed on August 27, 2025 including standstill (which included “don’t ask, don’t waive” language), non-solicit and certain other additional provisions, with the standstill provisions set to automatically terminate upon the signing of a definitive agreement providing for an acquisition of CSG.

On August 24, 2025, representatives of Simpson Thacher sent an initial draft of the mutual clean team agreement to representatives of Freshfields. Over the subsequent two weeks, representatives of Simpson Thacher and Freshfields exchanged comments on the clean team agreement, and the clean team agreement was executed on September 11, 2025.

On August 29, 2025, CSG granted access to NEC and its representatives and advisors to a virtual data room containing certain non-public information for purposes of NEC’s diligence review.

Over the course of late August and September, CSG and NEC and their respective representatives and advisors conducted multiple in-person and virtual due diligence meetings and exchanged various non-public information.

On September 4, 2025, representatives of CSG, NEC, Jefferies and Goldman Sachs attended a virtual meeting, at which CSG senior management presented forecasts of CSG and certain updates to the Preliminary Additional Projections – Upside Case, which updates were not material (the “Additional Projections – Upside Case”).

On September 15, 2025, Freshfields sent Simpson Thacher an initial draft of the merger agreement for the proposed transaction. Over the course of the ensuing period of time until the parties entered into the merger agreement on October 29, 2025, NEC and its advisors continued their due diligence review of CSG and representatives of CSG, NEC, Simpson Thacher and Freshfields negotiated the terms of the merger agreement and other definitive documentation for the proposed transaction.

On October 21, 2025, the CSG Board held a special meeting with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance. At the meeting, Mr. Shepherd as well as representatives of Jefferies and Simpson Thacher updated the CSG Board with respect to the developments regarding the status and negotiations with NEC over the past several weeks and the CSG Board provided guidance and instruction on various transaction related issues under negotiation with NEC. The CSG Board then held an executive session with Mr. Shepherd and the independent board members in attendance to further discuss the potential transaction. The CSG Board concluded that NEC should be permitted to conduct further requested commercial due diligence on CSG to permit NEC to provide an updated proposal.

On October 26, 2025, representatives of NEC orally proposed to Mr. Shepherd that NEC was prepared to move forward with the proposed transaction at a purchase price of $80.00 per share in cash (the “October 26 Proposal”).

On October 27, 2025, the CSG Board held a special meeting with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance, where the October 26 Proposal was discussed. During the meeting, representatives of Simpson Thacher reminded the directors of their fiduciary duties under applicable law in connection with their evaluation of a potential sale of CSG and presented a summary of the latest merger agreement and other transaction documentation for the proposed transaction. CSG’s senior management team then reviewed certain updates to the Preliminary Management Projections – Base Case from May made to reflect and take into account CSG’s preliminary actual results through the end of September 2025, which updates were not material (the “Management Projections – Base Case”) with the CSG Board, and approved the Management Projections – Base Case for Jefferies’ use and reliance in connection with its financial analysis and opinion. Representatives of Jefferies reviewed with the CSG Board Jefferies’ preliminary financial analysis of the October 26 Proposal and the proposed transaction based on the Management Projections – Base Case. The CSG Board considered the terms of the proposed transaction, including the purchase price offered as part of the October 26 Proposal, and the risks and potential benefits of a potential transaction as compared to CSG’s prospects as an independent public company and the risks associated with executing such plan. Following such discussion, the CSG Board instructed Mr. Shepherd to reject the $80.00 per share price proposed as part of the October 26 Proposal and request a best and final proposal from NEC.

Following the meeting, Mr. Shepherd communicated to certain executive members of NEC that the proposed price of $80.00 per share would not be acceptable to the CSG Board and requested a best and final proposal from NEC.

In the morning of October 28, 2025, certain executive members of NEC presented an oral offer of $80.70 per share (the “October 28 Proposal”) to Mr. Shepherd. Shortly thereafter, the CSG Board held a special meeting with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance, where the $80.70 price per share proposal was discussed based on the preliminary financial analyses that had been presented by representatives of Jefferies at the meeting held on the prior day. Following such discussion, the CSG Board reached consensus that CSG’s advisors should proceed with finalizing the merger agreement and other transaction documentation with NEC and its advisors.

In the evening of October 28, 2025, the CSG Board held a special meeting with members of CSG senior management, representatives of Jefferies and Simpson Thacher in attendance. In advance of the meeting, representatives of Jefferies had provided to the CSG Board a customary relationships disclosure letter describing Jefferies’ relationships with CSG and NEC, and representatives of Simpson Thacher had provided to the CSG Board a final, fully negotiated version of the merger agreement. At the meeting, representatives of Simpson Thacher summarized the updates to the terms of the final merger agreement since the prior meeting. Representatives of Jefferies reviewed with the CSG Board Jefferies’ financial analysis with respect to CSG and delivered its opinion (which Jefferies subsequently confirmed in writing) that, as of October 28, 2025, and based on and subject to the various assumptions made, procedures followed, matters considered and limitations and qualifications on the scope of review undertaken as described in its opinion, the merger consideration to be received by the holders of shares of CSG common stock pursuant to the proposed merger agreement was fair, from a financial point of view, to such holders (other than Parent, Merger Sub and their respective affiliates). Jefferies’ opinion is more fully described in the section of this proxy statement entitled “The Merger Proposal (Proposal 1)—Opinion of Jefferies LLC.” The written opinion is attached to this proxy statement as Annex B. After further discussion and deliberation, the CSG Board unanimously (i) approved and declared advisable the execution, delivery and performance of the merger agreement and the transactions contemplated thereby, including the merger, (ii) determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable, fair to and in the best interests of CSG and the CSG stockholders, (iii) directed that the merger agreement be submitted to the CSG stockholders for adoption, and (iv) recommended that the merger agreement and the transactions contemplated thereby, including the merger, be adopted by the CSG stockholders in accordance with applicable law.

Promptly thereafter early in the morning on October 29, 2025, CSG, Parent and Merger Sub executed and delivered the merger agreement and issued a joint press release announcing the proposed transaction.

At a meeting of the CSG Board held on October 28, 2025, the CSG Board, acting in consultation with its outside legal counsel and financial advisor, unanimously (a) determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable, fair to and in the best interests of CSG and its stockholders, (b) declared it advisable, fair to and in the best interests of CSG to enter into the merger agreement with Parent and Merger Sub providing for the merger in accordance with the DGCL, (c) approved the execution, delivery and performance of the merger agreement and the consummation of the transactions contemplated thereby, including the merger and (d) recommended that the merger agreement and the merger and the other transactions contemplated thereby in accordance with the terms thereof be adopted by CSG stockholders.

When you consider the CSG Board’s recommendation, you should be aware that CSG’s directors may have interests in the merger that may be different from, or in addition to, the interests of CSG stockholders generally. These interests are described in the section entitled “The Merger Proposal (Proposal 1)—Interests of CSG’s Executive Officers and Directors in the Merger”.

In the course of reaching its decision, the CSG Board consulted with CSG’s management and financial and legal advisors, reviewed a significant amount of information and considered a number of potentially positive factors that it believed supported its decision, including, among others, the following (not necessarily in order of relative importance):

In the course of reaching its decision, the CSG Board also considered and balanced against the potential benefits of the merger a number of potentially adverse factors with respect to the merger and the other transactions contemplated by the merger agreement including, among others, the following (not necessarily in the order of relative importance):

While the CSG Board considered potentially positive and potentially negative factors, the CSG Board concluded that, overall, the potentially positive factors outweigh the potentially negative factors. Accordingly, the CSG Board unanimously determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable and in the best interests of CSG and its stockholders.

The foregoing discussion is not intended to be an exhaustive list of the information and factors considered by the CSG Board in its consideration of the merger, but includes the material positive factors and material negative factors considered by the CSG Board in that regard. In view of the number and variety of factors, the CSG Board did not find it practicable to, nor did it attempt to, make specific assessments of, quantify, or otherwise assign relative weights to, the specific factors considered in reaching its determination. In addition, individual members of the CSG Board may have given different weights to different factors. Based on the totality of the information presented, the CSG Board collectively reached the unanimous decision to authorize and approve the execution, delivery and performance of the merger agreement and the transactions contemplated thereby, including the merger, in light of the factors described above and other factors that the members of the CSG Board felt were appropriate.

Portions of this explanation of CSG’s reasons for the merger and other information presented in this section are forward-looking in nature and, therefore, should be read in light of the section entitled “Cautionary Statement Regarding Forward-Looking Statements”, beginning on page 26 of this proxy statement.

CSG retained Jefferies as its financial advisor in connection with a possible sale, disposition or other business transaction involving CSG. In connection with this engagement, CSG requested that Jefferies evaluate the fairness, from a financial point of view, to the holders of shares of CSG common stock of the merger consideration to be received by such holders (other than Parent, Merger Sub and their respective affiliates) pursuant to the merger agreement. At a meeting of the CSG Board held on October 28, 2025, Jefferies rendered its opinion to the CSG Board to the effect that, as of that date and based on and subject to the various assumptions made, procedures

followed, matters considered and limitations and qualifications on the review undertaken as described in its opinion, the merger consideration to be received by the holders of shares of CSG common stock pursuant to the merger agreement was fair, from a financial point of view, to such holders (other than Parent, Merger Sub and their respective affiliates).

The full text of Jefferies’ opinion, which describes the various assumptions made, procedures followed, matters considered and limitations and qualifications on the review undertaken by Jefferies, is attached as Annex B to this proxy statement and is incorporated herein by reference. CSG encourages you to read the opinion carefully and in its entirety.

Jefferies’ opinion was provided for the use and benefit of the CSG Board (in its capacity as such) in its evaluation of the merger consideration from a financial point of view and did not address any other aspect of the merger or any other matter. Jefferies’ opinion did not address the relative merits of the merger as compared to any alternative transaction or opportunity that might be available to CSG, nor did it address the underlying business decision by CSG to engage in the merger or any term, aspect or implication of any other agreement (or amendment thereto or related arrangements) entered into in connection with, or contemplated by or resulting from, the merger or otherwise. Jefferies’ opinion did not constitute a recommendation as to how the CSG Board or any holder of shares of CSG common stock should vote on or otherwise act with respect to the merger or any other matter. The following summary is qualified in its entirety by reference to the full text of Jefferies’ opinion.

In arriving at its opinion, Jefferies, among other things:

In Jefferies’ review and analysis and in rendering its opinion, Jefferies assumed and relied upon, but did not assume any responsibility to independently investigate or verify, the accuracy and completeness of all financial and other information that was supplied or otherwise made available to Jefferies by CSG or that was publicly available to Jefferies (including, without limitation, the information described above), or that was otherwise reviewed by Jefferies. Jefferies relied on assurances of the management of CSG that it was not aware of any facts or circumstances that would make any of the foregoing information incomplete, inaccurate or misleading. In its review, Jefferies did not obtain any independent evaluation or appraisal of any of the assets or liabilities (contingent, accrued, derivative, off-balance sheet or otherwise), nor did Jefferies conduct a physical inspection of any of the properties or facilities of, CSG, and Jefferies was not furnished with and assumed no responsibility to obtain, any such evaluations, appraisals or physical inspections. Jefferies did not evaluate the solvency or fair value of CSG, Parent or any other entity under any laws relating to bankruptcy, insolvency or similar matters.

With respect to the financial forecasts provided to and reviewed by Jefferies, Jefferies noted that projecting future results of any company is inherently subject to uncertainty. However, Jefferies was advised, and Jefferies assumed, that such financial forecasts were reasonably prepared on bases reflecting the best currently available estimates and good faith judgments of the management of CSG as to the future financial performance of CSG and the other matters covered thereby. Jefferies expressed no opinion as to CSG’s financial forecasts or the assumptions on which they were based.

Jefferies’ opinion was based on economic, monetary, regulatory, market and other conditions existing and which could be evaluated as of the date thereof. Jefferies expressly disclaimed any undertaking or obligation to advise any person of any change in any fact or matter affecting Jefferies’ opinion of which Jefferies becomes aware after the date thereof.

Jefferies made no independent investigation of, and Jefferies expressed no view or opinion as to, any legal, regulatory, accounting or tax matters affecting or relating to CSG, and Jefferies assumed the correctness in all respects material to its analyses and opinion of all legal, regulatory, accounting and tax advice given to CSG and the CSG Board, including, without limitation, with respect to changes in, or the impact of, accounting standards or tax and other laws, regulations and governmental and legislative policies affecting CSG or the merger and legal, regulatory, accounting and tax consequences of the terms of, and transactions contemplated by, the merger agreement and related documents to CSG and its stockholders. In addition, in preparing its opinion, Jefferies did not take into account any tax consequences of the transaction to any holder of CSG common stock. Jefferies assumed that the merger would be consummated in accordance with the terms of the merger agreement without waiver, modification or amendment of any term, condition or agreement and in compliance with all applicable laws, documents and other requirements and that the final form of the merger agreement would be substantially similar to the last draft reviewed by Jefferies. Jefferies also assumed that in the course of obtaining the necessary governmental, regulatory or third-party approvals, consents, waivers and releases for the merger or otherwise, including with respect to any divestitures or other requirements, no delay, limitation, restriction or condition would be imposed or occur that would have an adverse effect on CSG, Parent or the contemplated benefits of the merger or that otherwise would be material in any respect to Jefferies’ analyses or opinion.

Jefferies’ opinion did not address the relative merits of the transactions contemplated by the merger agreement as compared to any alternative transaction or opportunity that might be available to CSG, nor did it address the underlying business decision by CSG to engage in the merger or the terms of the merger agreement or the documents referred to therein, including the form or structure of the merger or any term, aspect or implication of any other agreements, arrangements or understandings entered into in connection with, or contemplated by or resulting from the merger or otherwise. Jefferies’ opinion did not constitute a recommendation as to how any holder of shares of CSG common stock should vote on the merger or any matter related thereto. Jefferies was not asked to address, and its opinion did not address, the fairness to, or any other consideration of, the holders of any class of securities, creditors or other constituencies of CSG or any other party, other than the holders of shares of CSG common stock. Jefferies expressed no view or opinion as to the price at which shares of CSG common stock would trade or otherwise be transferrable at any time. Furthermore, Jefferies did not express any view or opinion as to the fairness, financial or otherwise, of the amount or nature of any compensation or other consideration payable to or to be received by any of CSG’s officers, directors or employees, or any class of such persons, in connection with the merger relative to the merger consideration to be received by holders of shares of CSG common stock or otherwise. Jefferies’ opinion was authorized by the Fairness Committee of Jefferies LLC.

In connection with rendering its opinion to the CSG Board, Jefferies performed certain financial and comparative analyses, including those described below. The following summary is not a complete description of all analyses performed and factors considered by Jefferies in connection with its opinion. The preparation of a financial opinion is a complex process involving subjective judgments and is not necessarily susceptible to partial analysis or summary description. With respect to the selected public companies and selected transactions analyses summarized below, no company used as a comparison was identical or directly comparable to CSG. These analyses necessarily involved complex considerations and judgments concerning financing characteristics and other factors that could affect the public trading or other values of the companies concerned.

Jefferies believes that its analyses and the summary below must be considered as a whole and in context and that selecting portions of its analyses and factors or focusing on information presented in tabular format, without considering all analyses and factors or the narrative description of the analyses, could create a misleading or incomplete view of the processes underlying Jefferies’ analyses and opinion. Jefferies did not draw, in isolation, conclusions from or with regard to any one factor or method of analysis for purposes of its opinion, but rather arrived at its ultimate opinion based on the results of all analyses undertaken by it and assessed as a whole.

The estimates of the future performance of CSG in or underlying Jefferies’ analyses are not necessarily indicative of future results or values, which may be significantly more or less favorable than those estimates. In performing its analyses, Jefferies considered industry performance, general business and economic conditions and other matters, many of which are beyond the control of CSG. Estimates of the financial value of companies or

businesses do not purport to be appraisals or necessarily reflect the prices at which companies, businesses or securities actually may be sold or acquired. Accordingly, the estimates used in, and the implied reference ranges resulting from, any particular analysis described below are inherently subject to substantial uncertainty and should not be taken as Jefferies’ view of the actual value of CSG or its businesses or securities.

The terms of the merger were determined through negotiations between CSG, on one hand, and Parent and Merger Sub, on the other hand, and the decision by CSG to enter into the merger agreement was solely that of the CSG Board. Jefferies’ opinion and financial analyses were only one of many factors considered by the CSG Board in its evaluation of the merger consideration and should not be viewed as determinative of the views of the CSG Board or CSG management with respect to the merger or the merger consideration payable in the merger.

The summary of the financial analyses described in this section is a summary of the material financial analyses reviewed with the CSG Board and performed by Jefferies in connection with its analyses and opinion. The financial analyses summarized below include information presented in tabular format. In order to fully understand Jefferies’ financial analyses, the tables must be read together with the text of each summary. The tables alone do not constitute a complete description of the financial analyses. Considering the data below without considering the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of Jefferies’ financial analyses. The order in which the financial analyses summarized below appear does not necessarily reflect the relative importance or weight given to such analyses. The following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before October 28, 2025, and is not necessarily indicative of current or future market conditions.

Jefferies reviewed publicly available financial, stock market and operating information of CSG and the following five selected publicly traded companies in the application software industry that have financial and operating characteristics that Jefferies, in its professional judgment, considered generally relevant for purposes of its analysis, which are collectively referred to as the “selected companies”:

Jefferies reviewed, among other information and to the extent publicly available, enterprise values (“EVs”) of the selected companies, calculated as fully diluted equity values based on closing stock prices on October 28, 2025, plus total debt, capital leases, preferred equity and non-controlling interests, minus cash and cash equivalents, as a multiple of each company’s estimated earnings before interest, taxes, depreciation and amortization, as applicable (“Adjusted EBITDA”) and unlevered free cash flow (“UFCF”), and reviewed the stock price to earnings per share (“P/E”) multiples for the selected companies for the calendar year 2026, which Jefferies refers to as CY 2026E. Financial data of the selected companies were based on publicly available research analysts’ estimates, public filings and other publicly available information.

The financial data reviewed included the following:

Jefferies applied a selected range of enterprise value to estimated Adjusted EBITDA multiples of 8.0x to 9.5x and a selected range of enterprise value to estimated UFCF multiples of 12.0x to 15.0x to corresponding data of

CSG based on the CSG Forecasts for estimated Adjusted EBITDA unburdened by stock-based compensation expense and capital expenditure, and estimated UFCF for CY 2026E unburdened by stock-based compensation expense and burdened by capital expenditure, to determine ranges of implied enterprise values for CSG. Jefferies then subtracted CSG’s estimated net debt as of September 30, 2025 to calculate a range of implied equity values, and divided the result by the number of fully diluted shares of CSG common stock outstanding, each as provided by CSG management, to calculate a range of implied per share equity values for CSG. Jefferies also applied a selected range of P/E multiples of 11.0x to 16.0x to CSG’s estimated earnings per share for CY 2026E to calculate a range of implied per share equity values for CSG. This analysis indicated the reference ranges of implied per share equity values set forth in the table below (rounded to the nearest $0.25), in each case as compared to the merger consideration of $80.70 per share.

No company utilized in the selected public companies analysis is identical to CSG. In evaluating the selected public companies, Jefferies made judgments and assumptions with regard to industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond CSG’s and Jefferies’ control.

Jefferies reviewed publicly available financial, stock market and operating information of CSG and company filings, definitive proxy statements, press releases and Wall Street research relating to the following eight historical M&A transactions, announced since May 2016, involving companies in the application software industry that have financial and operating characteristics that Jefferies, in its professional judgment, considered generally relevant for purposes of its analysis, which are collectively referred to as the “selected transactions”:

The financial data reviewed included the following:

Jefferies applied a selected range of enterprise value to the next twelve months (“NTM”) Adjusted EBITDA multiples derived from the selected transactions analysis of 8.0x to 11.0x to the estimated NTM Adjusted EBITDA of CSG for the twelve months ended September 30, 2026 to determine a range of implied enterprise values for CSG. Jefferies then subtracted CSG’s estimated net debt as of September 30, 2025 to calculate a range of implied equity values, and divided the result by the number of fully diluted shares of CSG common stock outstanding, each as

provided by CSG management, to calculate a range of implied per share equity values. This analysis indicated the reference ranges of implied per share equity values set forth in the table below (rounded to the nearest $0.25), in each case as compared to the merger consideration of $80.70 per share.

No transaction utilized as a comparison in the selected transactions analysis is identical to the merger. In evaluating the merger, Jefferies made numerous judgments and assumptions with regard to industry performance, general business, economic, market, and financial conditions and other matters, many of which are beyond the control of CSG and Jefferies.

Jefferies performed a discounted cash flow analysis of CSG by calculating the estimated present value of the stand-alone unlevered free cashflows that CSG was forecasted to generate during the calendar years ending December 31, 2025, through December 31, 2029, based on the CSG Forecasts (and burdened by stock-based compensation expense). The terminal values of CSG were calculated by applying a selected range of perpetuity growth rates of 2.5% to 3.5% to CSG’s estimated terminal year unlevered free cashflows, based on the CSG Forecasts and per management guidance. The present values of the unlevered free cash flows and terminal values of CSG were then calculated using a selected discount rate range of 8.5% to 9.5%, based on an estimate of CSG’s weighted average cost of capital, to determine a range of implied enterprise values for CSG. Jefferies then subtracted CSG’s estimated net debt as of September 30, 2025, to calculate a range of implied equity values, and divided the result by the number of fully diluted shares of CSG common stock outstanding, each as provided by CSG management, to calculate a range of implied per share equity values for CSG. This analysis indicated a reference range of implied per share equity values of $61.75 to $88.50 per share (rounded to the nearest $0.25), as compared to the merger consideration of $80.70 per share.

CSG has agreed to pay Jefferies for its financial advisory services in connection with the merger an aggregate fee of approximately $37 million, $1.5 million of which became payable upon the delivery of Jefferies’ opinion and the balance of which is payable contingent upon the closing of the merger. In addition, CSG agreed to reimburse Jefferies for expenses, including fees and expenses of counsel, incurred in connection with Jefferies’ engagement and to indemnify Jefferies and related parties against liabilities, including liabilities under federal securities laws, arising out of or in connection with the services rendered and to be rendered by Jefferies under its engagement.

As the CSG Board was aware, during the two-year period prior to the date of Jefferies’ opinion, Jefferies and its affiliates have not provided investment banking services to NEC for which Jefferies and its affiliates have received compensation. As the CSG Board was also aware during the two-year period prior to the date of Jefferies’ opinion, Jefferies and its affiliates have provided financial advisory and financing services to CSG, for which Jefferies and its affiliates have received aggregate compensation of approximately $4.2 million. Jefferies and its affiliates may provide financial advisory and/or financing services to CSG, NEC and their respective affiliates in the future, for which services Jefferies and its affiliates would expect to receive compensation. In the ordinary course of Jefferies’ business, Jefferies and its affiliates may trade or hold securities or financial instruments (including loans and other obligations) of CSG, NEC and their affiliates for Jefferies’ own account and for the accounts of Jefferies’ customers and, accordingly, may at any time hold long or short positions in those securities.

Jefferies was selected as CSG’s financial advisor in connection with the merger because, among other things, Jefferies is an internationally recognized investment banking firm with substantial experience in mergers and acquisition transactions and based on its familiarity with CSG’s business and industry. Jefferies is regularly engaged in the valuation of businesses and their securities in connection with mergers, acquisitions, negotiated underwritings, competitive bids, secondary distributions of listed and unlisted securities and private placements.

CSG does not, as a matter of course, publicly disclose projections as to its future financial results. CSG senior management prepared and provided to the CSG Board at its meeting on October 27, 2025, certain non-public financial forecasts based on management’s reasonable best estimates, judgments and assumptions with respect to CSG’s future financial performance at the time such forecasts were prepared, as further described in the section of this proxy statement entitled “The Merger Proposal (Proposal 1)—Background of the Merger,” beginning on page 35 of this proxy statement, and which we refer to, together with the Additional Projections – Upside Case, as the “Financial Projections”. With the consent of the CSG Board, these financial projections were provided to representatives of Jefferies for its use in connection with its financial analyses summarized above under “The Merger Proposal (Proposal 1)—Opinion of Jefferies LLC”, beginning on page 44 of this proxy statement. Jefferies expressed no view or opinion as to these financial projections or the assumptions on which they were based. A summary of the Financial Projections is set forth below:

The Additional Projections – Upside Case, which are further described in the section of this proxy statement entitled “The Merger Proposal (Proposal 1)—Background of the Merger,” beginning on page 35 of this proxy statement, were provided to representatives of NEC on September 4, 2025 to reflect certain upside scenarios for diligence purposes only in connection with NEC’s evaluation of the transactions contemplated by the merger agreement, and were not used by Jefferies in connection with its financial analyses.

The Financial Projections were not prepared with a view to public disclosure or with a view toward compliance with SEC rules and are included in this proxy statement only because, with the consent of the CSG Board, the Financial Projections were provided to representatives of Jefferies for its use in connection with its financial analyses summarized above under “The Merger Proposal (Proposal 1)—Opinion of Jefferies LLC” and the Additional Projections – Upside Case were provided to representatives of NEC for diligence purposes only. The Financial Projections were not prepared with a view to compliance with generally accepted accounting principles as applied in the United States (“GAAP”), the published guidelines of the SEC regarding projections and forward-looking statements or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. The Financial Projections were prepared by, and are the responsibility of, CSG’s management. KPMG LLP (“KPMG”) has not audited, reviewed, examined,

compiled nor applied agreed-upon procedures with respect to the Financial Projections and, accordingly, KPMG does not express an opinion or any other form of assurance with respect thereto. The KPMG report incorporated by reference in this proxy statement relates to CSG’s previously issued financial statements. It does not extend to the Financial Projections and should not be read to do so. The Financial Projections were prepared solely for internal use of CSG and are subjective in many respects. CSG has made no representations to Parent or Merger Sub, in the merger agreement or otherwise, concerning any projected financial information, including the Financial Projections.

The Financial Projections are forward-looking statements. Although this summary of the Financial Projections is presented with numerical specificity, the Financial Projections reflect numerous variables, assumptions and estimates as to future events made by CSG’s management that it believed were reasonable at the time the Financial Projections were prepared, taking into account the relevant information available to management at the time and presented as of the time of the preparation, to the best of management’s knowledge and belief, the expected course of action and the expected future financial performance of CSG on a stand-alone basis as described above and subject to certain assumptions and limitations. Such variables, assumptions and estimates are inherently uncertain, and many are beyond the control of CSG’s management. Although CSG’s management believes there is a reasonable basis for the Financial Projections, CSG cautions stockholders that future results could be materially different from the Financial Projections. Because the Financial Projections cover multiple years, by their nature, they become less predictive with each successive year. This information is not fact and should not be relied upon as being necessarily indicative of actual future results. The Financial Projections are subject to estimates and assumptions in many respects and, as a result, subject to interpretation. These estimates and assumptions may prove inaccurate for any number of reasons, including general economic conditions, competition and other risks. For information on factors that may cause CSG’s future results to vary materially, see the section of this proxy statement entitled “Cautionary Statement Regarding Forward-Looking Statements”, beginning on page 26 of this proxy statement.

In addition, the Financial Projections do not take into account any circumstances or events occurring after the date that they were prepared and do not give effect to the merger. Because the Financial Projections were developed on a stand-alone basis without giving effect to the merger, they do not reflect any divestitures or other restrictions that may be imposed in connection with the receipt of any necessary governmental or regulatory approvals, any synergies realized as a result of the merger or any changes to CSG’s operations or strategy that may be implemented after completion of the merger. As a result, there can be no assurance that the Financial Projections will be realized, and actual results may be materially better or worse than those contained in the Financial Projections. The inclusion of this information should not be regarded as an indication that the CSG Board, CSG, Jefferies, Parent, Merger Sub, or their respective representatives or affiliates or any other recipient of this information considered, or now considers, the Financial Projections to be necessarily predictive of actual future results. The summary of the Financial Projections is not included in this proxy statement in order to induce any stockholder to vote in favor of the merger proposal or any of the other proposals to be voted on at the special meeting.

Except to the extent required by applicable federal securities laws, CSG does not intend, and expressly disclaims any responsibility, to update or otherwise revise the Financial Projections to reflect circumstances existing after the date when CSG prepared the Financial Projections or to reflect the occurrence of future events or changes in general economic or industry conditions, even in the event that any of the assumptions underlying the Financial Projections are shown to be in error. By including in this document a summary of certain financial projections, neither CSG nor any of its representatives or advisors (including Jefferies) nor Parent or its representatives or affiliates makes any representation to any person regarding the ultimate performance of CSG or the surviving corporation compared to the information contained in such financial forecasts and should not be read to do so.

Certain of the measures included in the Financial Projections may be considered non-GAAP financial measures. Non-GAAP financial measures should not be considered in isolation from, or as a substitute for, financial information presented in compliance with GAAP, and non-GAAP financial measures as used by CSG may not be comparable to similarly titled amounts used by other companies. With the consent of the CSG Board, certain of the Financial Projections, including such non-GAAP financial measures were relied upon by representatives of Jefferies in connection with its financial analyses summarized above under “The Merger Proposal (Proposal 1)—Opinion of Jefferies LLC”, beginning on page 44 of this proxy statement, and by the CSG Board in connection with its consideration of the merger. Financial measures provided to a financial advisor in connection with a business combination transaction are excluded from the definition of non-GAAP financial measures and therefore are not subject to SEC rules regarding disclosures of non-GAAP financial measures, which would otherwise require a reconciliation of a non-GAAP financial measure to a GAAP financial measure. Reconciliations of non-GAAP

financial measures were not relied upon by representatives of Jefferies for purposes of its financial analyses and opinion or by the CSG Board in connection with its consideration of the merger. CSG has not provided reconciliations of the non-GAAP financial measures included in these projections to the comparable GAAP measure due to the lack of reasonably accessible or reliable comparable GAAP measures for these measures and the inherent difficulty in forecasting and quantifying the measures that are necessary for such reconciliation. Accordingly, a reconciliation of the financial measures is not included herein.

CSG’s executive officers and directors have interests in the merger that may be different from, or in addition to, the interests of CSG stockholders generally. These interests are described in more detail below. The CSG Board was aware and considered these interests in reaching the determination to approve the merger agreement and the merger and to recommend that CSG stockholders approve the merger agreement proposal.

CSG’s named executive officers are: Brian A. Shepherd (President and Chief Executive Officer), Hai Tran (Executive Vice President and Chief Financial Officer), Elizabeth A. Bauer (Executive Vice President and Chief Experience Officer), Rasmani Bhattacharya (Executive Vice President, Chief Legal Officer and Chief Compliance Officer), and Michael J. Woods (Executive Vice President and President of Communications, Media and Technology). CSG’s executive officers who are not named executive officers are Chad C. Dunavant (Executive Vice President and Chief Product and Strategy Officer) and Lori J. Szwanek (Senior Vice President and Chief Accounting Officer).

CSG’s non-employee directors are: Rachel Barger, David Barnes, Greg Conley, Marwan Fawaz, Samatha Greenberg, Rajan Naik, Haiyan Song, Silvio Tavares and Lily Yang.

With respect to executive officers and directors of CSG, these interests are described in more detail below:

As is the case for any stockholder of CSG, CSG’s directors and executive officers will receive $80.70 per share in cash, without interest, and less any applicable withholding taxes, for each share of CSG common stock that they own at the effective time. For information regarding beneficial ownership of CSG common stock by each of CSG’s current directors, CSG’s named executive officers and all directors and executive officers as a group, see the section of this proxy statement entitled “Security Ownership of Certain Beneficial Owners and Management” beginning on page 88.

As described in the section of this proxy statement entitled “The Merger Agreement—Treatment of CSG Equity Awards” beginning on page 63, pursuant to the merger agreement, effective as of the effective time, outstanding CSG equity awards will be treated as follows:

In addition, pursuant to the merger agreement, CSG equity awards granted in 2023 that would have completed their full vesting period and been settled in accordance with their terms in 2026 will vest and settle on or prior to December 31, 2025, with any applicable performance-based vesting conditions deemed achieved based on actual performance as of the latest practicable date.

Assuming that the closing occurs on July 1, 2026, which is the assumed closing date only for purposes of this compensation-related disclosure, as of November 20, 2025 (the latest practicable date to determine such amounts before the filing of this proxy statement) and (i) excluding any awards expected to vest in the ordinary course or that will vest solely pursuant to the terms of the merger agreement, in each case, prior to July 1, 2026 and (ii) assuming no additional grants or forfeitures of CSG equity awards will be made prior to July 1, 2026, CSG’s executive officers who are not named executive officers would hold unvested CSG equity awards (with any performance-based or market-based restricted stock awards reflected at target level of achievement, though such awards may vest up to 200% of target on maximum achievement) with an aggregate value (including the value of accrued cash dividends as of November 20, 2025) of $1,756,765 and CSG’s non-employee directors would hold no unvested CSG equity awards. As of November 20, 2025 (the latest practicable date to determine such amounts

before the filing of this proxy statement), CSG’s non-employee directors hold unvested CSG equity awards with an aggregate value (including the value of accrued cash dividends) of $2,258,405. In each case, the amount of accrued cash dividends does not include dividends that may accrue in respect of such awards after November 20, 2025; however, cash dividends will continue to be paid in the ordinary course and consistent with past practice. See “—Quantification of Payments and Benefits” for the value of the CSG equity awards held by each of CSG’s named executive officers.

Beginning on the date of the merger agreement, no purchase period under the CSG ESPP has commenced or will commence, no new participants have joined or may join the CSG ESPP, and no participant has increased or may increase the amount of his or her payroll deductions with respect to the CSG ESPP. The CSG ESPP will terminate in its entirety on the closing and no further rights will be granted or exercised under the CSG ESPP thereafter.

Each executive officer is eligible for severance benefits in the event of a Qualifying Termination (as defined below) within the first 18 months following a change in control of CSG under either the CSG Systems International, Inc. Executive Severance Plan (the “Executive Severance Plan”) or, in the case of CSG’s executive officer who is a Senior Vice President, the CSG Systems International, Inc. Severance Plan for Senior Vice Presidents (the “SVP Severance Plan” and, together with the Executive Severance Plan, the “Severance Plans”). For purposes of this disclosure, “Qualifying Termination” means a termination of the executive’s employment by CSG other than for cause or by the executive for good reason (in each case, as defined in the applicable severance plan).

If any executive officer participating in the Severance Plans has a Qualifying Termination within the first 18 months following a change in control of CSG, the executive officer would be entitled to the following separation benefits: (i) a lump sum severance payment consisting of an amount equal to 200% of the executive officer’s annual base salary and target bonus, with the exception of Mr. Shepherd and Ms. Bauer, who would receive an amount equal to 300% of their respective annual base salary and target bonus as reflected in their participation agreements and any executive officer who is a Senior Vice President who would receive 100% of their annual base salary and target bonus; (ii) a cash amount equal to the COBRA continuation coverage premiums that would be payable by the executive officer for the first 18 months of the COBRA continuation period (or 12 months, in the case of an executive officer who is a Senior Vice President); (iii) an additional lump sum payment consisting of the executive officer’s target bonus, pro-rated for the number of days the executive officer was employed during the calendar year; and (iv) vesting of all unvested time-based and performance-based restricted stock awards, with the vesting determined based on target level of performance; provided, however, in the event that a performance-based stock award includes a stock price performance metric, the measurement period for such stock price performance metric will be deemed to have ended on the date of the change in control. Payment to executive officers under the Severance Plans are contingent on, among other things, the executive officer entering into and complying with a broad-based release of claims in respect of CSG.

In addition, to the extent that any payment or benefit received in connection with a change in control of CSG would be subject to an excise tax under Section 4999 of the Code, such payments and/or benefits will be subject to a “best net” cutback if such reduction would result in a greater net after-tax benefit to the executive officer than receiving the full amount of such payments.

As of November 20, 2025 (the latest practicable date to determine such amounts before the filing of this proxy statement), and for the avoidance of doubt, excluding any value attributable to any equity-based awards any such person may hold, CSG’s executive officers who are not named executive officers would be entitled to cash severance in an aggregate amount of $2,352,048 (assuming that (i) each executive officer’s base salary rate, target annual bonus and benefits levels remain unchanged from those in effect as of the date of this proxy statement and (ii) that the closing occurs on July 1, 2026, which is the assumed closing date only for purposes of this compensation-related disclosure). See “—Quantification of Payments and Benefits” for the value of cash severance that would be owed to each of CSG’s named executive officers.

Pursuant to the terms of the merger agreement, CSG’s directors and executive officers will be entitled to certain ongoing indemnification, expense advancement and insurance arrangements. See the section entitled “The Merger Agreement–Indemnification of Directors and Officers; Insurance” beginning on page 78 for a description of such ongoing arrangements.

In the event that the effective time occurs prior to the completion of the performance period under CSG’s annual bonus plan, the surviving corporation will pay annual bonuses at the greater of target and actual performance for the applicable plan year and otherwise pursuant to the terms of the underlying bonus plan (“Closing Year Bonuses”). In the event that an employee eligible for the Closing Year Bonus incurs a termination of employment for any reason prior to the payment date of the Closing Year Bonus under circumstances for which such employee would be entitled to receive all or a portion of his or her annual bonus in accordance with the terms of any compensation and benefit plan applicable to him or her, such entitlement will continue to apply.

As of the date of this proxy statement, none of CSG’s executive officers or directors have entered into any agreement, arrangement or understanding with Parent or any of its affiliates regarding employment, or providing for any compensation and benefits, following the effective time, and the merger is not conditioned upon any such agreement, arrangement or understanding being entered into.

CSG may, in consultation with Parent, consider certain actions before the effective time, including accelerating certain compensation payments otherwise payable in future years, to mitigate the amount of potential “excess parachute payments” for “disqualified individuals” (each, within the meaning of Section 280G of the Code).

No CSG plan, policy, agreement or arrangement provides any employee, officer or director with the right to a tax “gross-up” payment in connection with any “golden parachute” or other tax liability triggered in connection with the merger. The Severance Plans contain a “best net” cutback provision such that in the event that payments and benefits to an executive officer in connection with a change in control will be subject to excise taxes imposed under Section 4999 of the Code, then the executive officer would either receive all such payments and benefits in full or such payments and benefits would be reduced to the greatest amount that does not trigger the excise tax pursuant to Section 4999 of the Code, whichever results in the greater after-tax amount for the executive officer.

CSG may establish a cash-based retention, integration and business continuity bonus program in an aggregate amount not to exceed $10 million to incentivize employees in the successful consummation of the merger, integration of CSG’s business and operations and business continuity in connection with the merger. Retention awards will generally be payable subject to continued employment through immediately prior to the consummation of the merger. CSG’s executive officers who are not Senior Vice Presidents will not be eligible to participate in such program.

Certain of CSG’s executive officers have balances in the Wealth Accumulation Plan, which is a nonqualified deferred compensation plan that was frozen in 2022. All accounts under the Wealth Accumulation Plan are fully vested. In connection with the merger, CSG may terminate the Wealth Accumulation Plan, effective as of the effective time, and pay out account balances thereunder in accordance with the plan terms. As of November 20, 2025 (the latest practicable date to determine such amounts before the filing of this proxy statement), CSG’s executive officers who are not named executive officers have an aggregate balance under the Wealth Accumulative Plan equal to $927,944.

The following table sets forth the information required by Item 402(t) of Regulation S-K regarding the compensation for CSG’s named executive officers based on the merger, assuming that (a) the merger is completed on July 1, 2026, which is the assumed closing date only for purposes of this compensation-related disclosure, (b) each named executive

officer experiences a Qualifying Termination immediately following the completion of the merger, (c) each named executive officer’s base salary rate, target annual bonus and benefits levels remain unchanged from those in effect as of the date of this proxy statement, (d) the number of CSG equity awards is those held as of November 20, 2025 (the latest practicable date to determine such amounts before the filing of this proxy statement), less any awards expected to vest in the ordinary course or that will vest solely pursuant to the terms of the merger agreement, in each case, prior to July 1, 2026, and assuming no additional grants or forfeitures of CSG equity awards will be made prior to July 1, 2026, (e) the performance-based or market-based restricted stock awards are reflected at target level of achievement (other than the CEO Award, which is reflected based on the merger consideration (i.e., 157% achievement)), though such awards may vest up to 200% of target on maximum achievement, (f) all accrued cash dividends in respect of equity awards are shown as of November 20, 2025 (the latest practicable date to determine such amounts before the filing of this proxy statement) and no value is attributed to cash dividends that may accrue in respect of such awards after such date; however, cash dividends will continue to be paid in the ordinary course and consistent with past practice, and (g) the merger consideration is $80.70 per share. The actual amounts payable would depend on the date of termination, the manner of the termination and the terms of the agreements in effect at such time. The calculations in the table below neither include amounts that CSG’s named executive officers were already entitled to receive or were vested in as of the date of this proxy statement (except as otherwise noted in the footnotes to the table), nor do they include amounts under contracts, agreements, plans or arrangements to the extent they do not discriminate in scope, terms or operation in favor of the named executive officers and are available generally to all the salaried employees of CSG. The calculations do not reflect any possible reductions under the Section 280G “best net” cutback provisions as described above in the section entitled “—Interests of CSG’s Executive Officers and Directors in the Merger—Severance Benefits” beginning on page 54. As a result of the foregoing assumptions, which may or may not actually occur or be accurate on the relevant date, including the assumptions described in the footnotes to the table, the actual amounts, if any, to be received by a named executive officer may materially differ from the amounts set forth below.

The merger is not conditioned on any financing arrangements or contingencies. Parent and Merger Sub have represented in the merger agreement that Parent and Merger Sub has and will have sufficient funds at the effective time for the satisfaction of all of Parent’s and Merger Sub’s obligations under the merger agreement. Parent and Merger Sub intend to finance the merger through a combination of existing cash resources and the proceeds from bank facilities of Parent. If such financing has not been obtained, Parent and Merger Sub will each continue to be obligated to consummate the merger, subject to satisfaction or waiver of the closing conditions set forth in the merger agreement.

Completion of the merger is conditioned upon (a) the expiration or early termination of the waiting period (and any extension thereof) applicable to the consummation of the merger under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the “HSR Act”) and the expiration or termination of any voluntary agreement between Parent, on the one hand, and the FTC and the DOJ, on the other hand, pursuant to which Parent has agreed not to consummate the merger, (b) the CFIUS clearance having been obtained, and (c) all consents pursuant to the antitrust laws of Australia, Japan, Kenya, Saudi Arabia, South Africa and the United Kingdom and foreign investment laws of the United Kingdom having been obtained (or waiting periods having expired or terminated). Under the merger agreement and subject to certain limitations, each of CSG, Parent and Merger Sub has agreed to use its respective reasonable best efforts to, among other things, consummate the merger as promptly as practicable. Parent and Merger Sub have agreed to use reasonable best efforts to take any steps necessary, proper or advisable to avoid or eliminate each and every impediment under any antitrust or foreign investment law, including agreeing to or committing to or effecting certain specified regulatory actions to the extent necessary to obtain the waiting period expirations, clearances, and consents discussed above.

Under the HSR Act, the merger may not be completed until notifications have been filed with and certain information has been furnished to the Antitrust Division of the DOJ and the FTC, and all statutory waiting period requirements have been satisfied. Further, the merger may not be completed until certain information has been

furnished to the Committee on Foreign Investment in the United States (“CFIUS”). CSG and Parent must file, as applicable, a (i) HSR notification with the Antitrust Division of the DOJ and the FTC, and (ii) draft joint voluntary notice to CFIUS no later than December 4, 2025.

At any time before or after the completion of the merger, the Antitrust Division or the FTC could take action under the U.S. antitrust laws, including seeking to prevent the merger, to rescind the merger or to clear the merger subject to the divestiture of assets of CSG or Parent or subject to other remedies. In addition, U.S. state attorneys general could take action under the antitrust laws as they deem necessary or desirable in the public interest, including without limitation seeking to enjoin the completion of the transactions or permitting completion subject to the divestiture of assets of CSG or Parent or other remedies. Private parties may also seek to take legal action under the antitrust laws under some circumstances. There can be no assurance that a challenge to the transactions on antitrust grounds will not be made or, if such challenge is made, that it would not be successful.

The exchange of CSG common stock for cash pursuant to the merger generally will be a taxable transaction for U.S. federal income tax purposes. In general, a U.S. holder (as defined in the section of this proxy statement entitled “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 89) whose shares of CSG common stock are converted into the right to receive cash in the merger will recognize capital gain or loss for U.S. federal income tax purposes in an amount equal to the difference, if any, between the amount of cash received with respect to such shares and the U.S. holder’s adjusted tax basis in such shares at the time of the exchange. Gain or loss will be determined separately for each block of shares of CSG common stock (i.e., shares of CSG common stock acquired at the same cost in a single transaction).

The determination of the actual tax consequences of the merger to a holder of CSG common stock will depend on the holder’s specific situation. You should read the section of this proxy statement entitled “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 89 and consult your tax advisors regarding the U.S. federal income tax consequences of the merger to you in your particular circumstances, as well as tax consequences arising under the laws of any state, local or non-U.S. taxing jurisdiction.

As promptly as reasonably practicable following the completion of the merger, the parties will cooperate to cause the CSG common stock to be delisted from Nasdaq and deregistered under the Exchange Act, and accordingly, the CSG common stock will no longer be publicly traded.

Under the DGCL, CSG stockholders have the right to demand appraisal and to receive payment in cash for the fair value of their shares of CSG common stock as determined by the Delaware Court of Chancery, together with interest, if any, as determined by the Delaware Court of Chancery, in lieu of the merger consideration, subject to the requirements and limitations set forth in Section 262 of the DGCL described herein. These rights are known as appraisal rights. CSG stockholders of record and beneficial owners electing to exercise appraisal rights must comply with the provisions of Section 262 of the DGCL in order to perfect their rights. Strict compliance with the statutory procedures is required to perfect appraisal rights under Delaware law. This section is intended as a brief summary of the material provisions of Delaware law pertaining to appraisal rights. The following discussion, however, is not a complete summary of the law pertaining to appraisal rights under the DGCL and is qualified in its entirety by the full text of Section 262 of the DGCL, which is attached to this proxy statement as Annex C and incorporated into this proxy statement by reference. A copy of Section 262 may also be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. Failure to comply strictly with the procedures set forth in Section 262 of the DGCL will result in the loss of appraisal rights. The following discussion does not constitute any legal or other advice, nor does it constitute a recommendation as to whether or not an CSG stockholder of record or beneficial owner should exercise his, her or its right to seek appraisal under Section 262 of the DGCL.

Subject to certain exceptions specified in Section 262 of the DGCL and summarized below, holders of record, and beneficial owners, of shares of CSG common stock who: (a) submit a written demand for appraisal of such

person’s shares to CSG prior to the vote on the merger agreement; (b) have not consented to or otherwise voted in favor of the merger agreement or otherwise withdrawn, lost or waived appraisal rights; (c) continuously are the record holders or beneficial holders, as applicable, of such shares through the effective time; and (d) otherwise comply with the applicable procedures and requirements set forth in Section 262 of the DGCL will be entitled to have their shares appraised by the Delaware Court of Chancery and receive payment in cash of the “fair value” of such shares (as determined by the Delaware Court of Chancery, exclusive of any element of value arising from the accomplishment or expectation of the merger) as of the completion of the merger instead of the merger consideration. Any such CSG stockholder of record or beneficial holder awarded “fair value” for the holder’s shares by the court would receive payment of that fair value in cash, together with interest, if any, in lieu of the right to receive the merger consideration. It is possible that any such “fair value” as determined by the Delaware Court of Chancery may be more or less than, or the same as the merger consideration.

Section 262 of the DGCL requires that CSG stockholders for whom appraisal rights are available be notified not less than 20 days before the special meeting. Either a copy of Section 262 of the DGCL or information directing CSG stockholders to a publicly available electronic resource at which Section 262 of the DGCL may be accessed without subscription or cost must be included with such notice.

This proxy statement constitutes our notice to CSG stockholders of the availability of appraisal rights in connection with the merger in compliance with the requirements of Section 262 of the DGCL, which is attached to this proxy statement as Annex C and incorporated into this proxy statement by reference. A copy of Section 262 may also be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. CSG stockholders of record and beneficial owners who wish to exercise appraisal rights or who wish to preserve the right to do so should review the following summary and the applicable statutory provisions carefully. Failure to comply with the procedures of Section 262 of the DGCL in a timely and proper manner will result in the loss of appraisal rights. In addition, the Delaware Court of Chancery will dismiss appraisal proceedings in respect of CSG unless certain stock ownership conditions are satisfied by CSG stockholders of record and beneficial owners seeking appraisal. Because of the complexity of the procedures for exercising the right to seek appraisal, CSG stockholders of record and beneficial owners who wish to exercise appraisal rights are urged to consult with their own legal and financial advisors in connection with compliance under Section 262 of the DGCL. An CSG stockholder of record or beneficial owner who loses, waives or otherwise fails to properly exercise his, her or its appraisal rights will be entitled to receive the merger consideration.

If you are an CSG stockholder of record or a beneficial holder and wish to exercise the right to seek an appraisal of your shares of CSG common stock, you must satisfy each of the following conditions:

If you fail to comply with any of these conditions and the merger is completed, you will be entitled to receive the merger consideration, but you will have no appraisal rights with respect to your shares of CSG common stock.

In addition, because shares of CSG common stock are listed on a national securities exchange and are expected to continue to be listed on such exchange immediately prior to the consummation of the merger, the Delaware Court of Chancery will dismiss appraisal proceedings as to all shares of CSG common stock, unless (a) the total number of shares entitled to appraisal exceeds 1% of the outstanding shares of CSG common stock or (b) the value of the merger consideration for such total number of shares entitled to appraisal exceeds $1 million (collectively, the “ownership thresholds”). At least one of the ownership thresholds must be met in order for CSG stockholders to be entitled to seek appraisal with respect to such shares of CSG common stock.

In the case of a record holder of shares of CSG common stock, voting, via the internet during the special meeting or by proxy, against, abstaining from voting on or failing to vote on the merger agreement will not constitute a written demand for appraisal as required by Section 262 of the DGCL. The written demand for appraisal is in addition to and separate from any proxy or vote. If you want to exercise your appraisal rights, you must not vote your shares of CSG common stock via the internet during the special meeting or by proxy in favor of the merger agreement.

In the case of a beneficial owner of shares of CSG common stock, brokers, banks and other nominees that hold shares in “street name” for their customers do not have discretionary authority to vote those shares on the merger agreement without specific voting instructions from the beneficial owner on such proposal, but such brokers, banks or other nominees will vote such shares as instructed if the beneficial owner provides such instructions. If a beneficial owner of shares of CSG common stock held in “street name” instructs such person’s broker, bank or other nominee to vote such person’s shares in favor of the merger agreement, and does not revoke such instruction prior to the vote on the merger agreement, then such shares will be voted in favor of the merger agreement, and it will constitute a waiver of such beneficial owner’s right of appraisal and will nullify any previously delivered written demand for appraisal. Therefore, if you are a beneficial owner of shares of CSG common stock who wishes to exercise appraisal rights, you must either not provide any instructions to your broker, bank or other nominee how to vote on the merger agreement or instruct such broker, bank or other nominee to vote against the merger agreement or abstain from voting on such proposal.

A holder of record or beneficial owner of shares of CSG common stock issued and outstanding immediately prior to the effective time may assert appraisal rights for the shares of CSG common stock held of record or beneficially in that holder’s name. A demand for appraisal must be executed by or on behalf of the CSG stockholder of record or beneficial owner, as applicable, and must reasonably inform CSG of the identity of the CSG stockholder of record or beneficial owner and that the CSG stockholder intends to demand appraisal of his, her or its shares of CSG common stock. In addition, in the case of a demand for appraisal made by a beneficial owner, the demand must (a) reasonably identify the holder of record of the shares for which the demand is made, (b) provide documentary evidence of such beneficial owner’s beneficial ownership and a statement that such documentary evidence is a true and correct copy of what it purports to be and (c) provide an address at which such beneficial owner consents to receive notices given by CSG and to be set forth on the verified list of persons who have demanded appraisal for their shares pursuant to Section 262(f) of the DGCL. A holder of record, such as a bank, broker or other nominee, who holds shares of CSG common stock as a nominee or intermediary for others, may exercise his, her or its right of appraisal with respect to the shares held for one or more beneficial owners, while not exercising this right for other beneficial owners. In that case, the written demand should state the number of shares as to which appraisal is sought. Where no number of shares is expressly mentioned, the demand will be presumed to cover all shares held in the name of the holder of record.

If you elect to exercise appraisal rights under Section 262 of the DGCL, you should mail or deliver a written demand to:

The following discussion sets forth the principal terms of the merger agreement, a copy of which is attached as Annex A to this proxy statement and is incorporated by reference herein. The rights and obligations of the parties are governed by the express terms and conditions of the merger agreement and not by this discussion, which is summary by nature. This discussion is not complete and is qualified in its entirety by reference to the complete text of the merger agreement. You are encouraged to read the merger agreement carefully in its entirety, as well as this proxy statement and any documents incorporated by reference herein, before making any decisions regarding the merger.

The merger agreement and this summary of its terms have been included to provide you with information regarding the terms of the merger agreement. Factual disclosures about CSG contained in this proxy statement or in CSG’s public reports filed with the SEC may supplement, update or modify the factual disclosures about CSG contained in the merger agreement and described in this summary. The representations, warranties and covenants made in the merger agreement by CSG, Parent and Merger Sub were qualified and subject to important limitations agreed to by CSG, Parent and Merger Sub in connection with negotiating the terms of the merger agreement. In particular, in your review of the representations and warranties contained in the merger agreement and described in this summary, it is important to bear in mind that the representations and warranties were negotiated with the purposes of, among other things, establishing the circumstances in which a party to the merger agreement may have the right not to close the merger if the representations and warranties of the other party prove to be untrue, due to a change in circumstance or otherwise, and allocating risk between the parties to the merger agreement, and were not intended by the parties to the merger agreement to be a characterization of the actual state of facts or condition of CSG, Parent or Merger Sub, except as expressly stated in the merger agreement. The representations and warranties may also be subject to a contractual standard of materiality different from those generally applicable to stockholders and reports and documents filed with the SEC, and in some cases were qualified by disclosures that were made by CSG to Parent and Merger Sub, which disclosures are not reflected in the merger agreement. Moreover, information concerning the subject matter of the representations and warranties, which do not purport to be accurate as of the date of this proxy statement, may have changed since October 29, 2025 and subsequent developments or new information qualifying a representation or warranty may have been included in this proxy statement or in the public filings made by CSG with the SEC.

Additional information about CSG may be found elsewhere in this proxy statement and CSG’s other public filings. See “Where You Can Find Additional Information” beginning on page 94 of this proxy statement.

The closing of the merger will take place by electronic exchange of signatures and documents at 8:00 a.m. (New York City time) no later than the fifth business day after the satisfaction or (to the extent permitted by applicable law) waiver of the conditions set forth in the merger agreement (other than those conditions that by their nature are to be satisfied at the closing, but subject to the satisfaction or (to the extent permitted by applicable law) waiver of such conditions), unless another time or place is mutually agreed to in writing by CSG, Parent and Merger Sub.

At the closing, CSG, Parent and Merger Sub will cause the merger to be consummated by filing a certificate of merger with respect to the merger (the “certificate of merger”) with the Secretary of State of the State of Delaware in accordance with Section 251 of the DGCL and shall take such further actions as may be required to make the merger effective. The merger shall become effective at the time and day of such filing with and acceptance by the Secretary of State of the State of Delaware or at such later time as may be agreed by CSG, Parent and Merger Sub in writing and specified in the certificate of merger in accordance with the DGCL (such time, the “effective time”).

Upon the terms and subject to the conditions of the merger agreement, and in accordance with the DGCL, at the effective time, Merger Sub will be merged with and into CSG and the separate corporate existence of Merger Sub will cease, with CSG continuing as the surviving corporation and a wholly owned subsidiary of Parent. At the effective time, (a) the certificate of incorporation of CSG, as in effect immediately prior to the effective time, shall be amended and restated in its entirety, and, as so amended and restated, shall be the certificate of incorporation of the surviving corporation, until thereafter amended or restated as provided therein and in accordance with applicable

law and (b) without any further action on the part of CSG or Merger Sub, the bylaws of Merger Sub as in effect immediately prior to the effective time shall be the bylaws of the surviving corporation (except that references therein to the name of Merger Sub shall be replaced by references to the name of CSG) until thereafter amended or restated as provided therein or by the certificate of incorporation of the surviving corporation and in accordance with applicable law.

The board of directors of the surviving corporation from and after the effective time shall consist of the members of the board of directors of Merger Sub immediately prior to the effective time, until their successors have been duly elected or appointed and qualified or until their earlier death, resignation or removal in accordance with the certificate of incorporation and the bylaws of the surviving corporation and applicable law. The officers of CSG immediately prior to the effective time will be the officers of the surviving corporation from and after the effective time until their respective successors are duly elected or appointed and qualified, or until their earlier death, resignation or removal, in accordance with the surviving corporation’s certificate of incorporation and bylaws and applicable law.

At the effective time, each share of CSG common stock issued and outstanding immediately prior to the effective time (other than company restricted shares, excluded shares and dissenting shares, each as further described in the merger agreement) will be converted into the right to receive the merger consideration. From and after the effective time, such shares of CSG common stock will no longer be outstanding and will automatically be cancelled and extinguished, and will cease to exist, and each former holder of such shares will cease to have any rights with respect thereto, except for the right to receive the merger consideration.

Each excluded share will cease to be outstanding, will be automatically cancelled and extinguished without any conversion thereof or consideration paid therefor at the effective time by virtue of the merger.

Pursuant to the merger agreement, effective as of the effective time, outstanding CSG equity awards will be treated as follows:

In addition, pursuant to the merger agreement, CSG equity awards granted in 2023 that would have completed their full vesting period and been settled in accordance with their terms in 2026 will vest and settle on or prior to December 31, 2025, with any applicable performance-based vesting conditions deemed achieved based on actual performance as of the latest practicable date.

Beginning on the date of the merger agreement, no purchase period under the CSG ESPP has commenced or will commence, no new participants have joined or may join the CSG ESPP, and no participant has increased or may increase the amount of his or her payroll deductions with respect to the CSG ESPP. The CSG ESPP will terminate in its entirety on the closing and no further rights will be granted or exercised under the CSG ESPP thereafter.

At or immediately after the effective time, Parent will deposit, or cause to be deposited, with a paying agent selected by Parent with CSG’s reasonable prior approval, an amount of cash equal to the aggregate cash consideration to which CSG’s stockholders are entitled under the merger agreement (which, for the avoidance of doubt, shall not include any amounts payable pursuant to equity awards under the merger agreement). Promptly after the effective time (and in any event within five business days after the effective time), the surviving corporation will cause the paying agent to mail or otherwise provide to each former holder of record of certificates that immediately prior to the effective time represented outstanding shares of CSG common stock and each former holder of record of shares of CSG common stock represented by a certificate (in each case, other than holders of only company restricted shares, excluded shares or dissenting shares, as described in the merger agreement) (a) a letter of transmittal in customary form reasonably satisfactory to CSG and Parent, and (b) instructions for use in effecting the surrender of the certificates, or affidavits of loss in lieu thereof, in exchange for the merger consideration.

Promptly following the effective time (but in no event later than the fifth business day thereafter), Parent and the surviving corporation shall cause the paying agent to mail, to each holder of record (as of immediately prior to the effective time) of any non-certificated shares held in book-entry form not held, directly or indirectly, through The Depository Trust Company (“DTC”) (other than any company restricted shares, excluded shares or dissenting shares) (a) a customary notice of the effectiveness of the merger in such form and containing such provisions as are reasonably acceptable to CSG and (b) instructions for use in effecting the surrender of such shares in exchange for the merger consideration. With respect to such non-certificated shares held, directly or indirectly, through DTC, Parent and CSG shall cooperate to establish procedures with the paying agent, DTC, DTC’s nominees and such other necessary or desirable third-party intermediaries to ensure that the paying agent shall transmit to DTC or its nominees, as promptly as practicable after the effective time, on surrender of company shares (other than any company restricted Shares, excluded shares or dissenting shares) held of record by DTC or its nominees in accordance with DTC’s customary surrender procedures and such other procedures as agreed by Parent, CSG, the paying agent, DTC, DTC’s nominees and such other necessary or desirable third-party intermediaries, the merger consideration payable in respect thereof.

On surrender of company shares (other than any company restricted shares, excluded shares or dissenting shares) that (A) are represented by certificates, by physical surrender of such certificates (or affidavits of loss in lieu thereof certificates) together with the letter of transmittal, duly completed and validly executed in accordance with such letter’s instructions (and such other customary documents as may reasonably be required by the paying agent), (B) are uncertificated shares not held, directly or indirectly, through DTC, by book-receipt of an “agent’s message” by the paying agent in connection with the surrender of such uncertificated shares (or such other reasonable evidence, if any, of surrender with respect to such uncertificated shares as the paying agent may reasonably request

pursuant to the terms and conditions of the paying agent agreement) or (C) are uncertificated shares held, directly or indirectly, through DTC, in accordance with DTC’s customary surrender procedures and such other procedures as agreed by CSG, Parent, the paying agent, DTC, DTC’s nominees and such other necessary or desirable third-party intermediaries, the holder of such certificated or uncertificated shares shall be entitled to receive in exchange therefor the merger consideration for each company share formerly represented by such certificate (or affidavits of loss in lieu thereof) or uncertificated share (less any applicable withholding tax) and the certificate or uncertificated share so surrendered will be canceled.

The merger agreement contains representations and warranties made by CSG to Parent and Merger Sub and by Parent and Merger Sub to CSG. Certain of the representations and warranties in the merger agreement are subject to materiality or material adverse effect qualifications (that is, they will not be deemed to be inaccurate or incorrect unless their failure to be true or correct (a) is material, (b) would result in a material adverse effect on the party making such representation or warranty or (c) would prevent, materially delay or materially impair the ability of CSG to consummate the transactions). In addition, certain of the representations and warranties in the merger agreement are subject to knowledge qualifications, which means that those representations and warranties would not be deemed untrue, inaccurate or incorrect as a result of matters of which certain individuals from the party making the representation (who are specified in qualifying the “knowledge” of such party for purposes of the merger agreement) did not have actual knowledge after reasonable inquiry. Furthermore, each of the representations and warranties is subject to the qualifications set forth on the disclosure letter, in the case of certain representations and warranties made by CSG, as well as the reports of CSG filed with or furnished to the SEC during the period from January 1, 2023 through October 29, 2025 (excluding any disclosures set forth under the captions “Risk Factors” or “Forward-Looking Statements” and in any other section to the extent they are cautionary, predictive or forward-looking in nature).

In the merger agreement, CSG has made representations and warranties to Parent and Merger Sub regarding, among other topics, the following:

In the merger agreement, Parent and Merger Sub have made representations and warranties to CSG regarding:

For purposes of the merger agreement, a “material adverse effect” on CSG means any change, occurrence, effect, event, circumstance or development (each, an “effect”) that, individually or in the aggregate, (x) has had or would reasonably be expected to have a material adverse effect on the business, assets, liabilities, financial condition or results of operations of CSG and its subsidiaries, taken as a whole, or (y) would or would reasonably be expected to prevent, materially delay or materially impair the ability of CSG to consummate the transactions in accordance with the merger agreement; provided, that, solely in the case of the foregoing clause (x), none of the following shall be deemed in and of themselves, either alone or in combination, to constitute, and no effect resulting from, attributable to or arising out of any of the following shall be taken into account in determining whether a material adverse effect has occurred:

The merger agreement provides that, subject to certain exceptions in the disclosure letter, during the period from October 29, 2025 to the effective time (or, if earlier, the date, if any, on which the merger agreement is validly terminated in accordance with its terms) and except as otherwise required or expressly provided for by the merger agreement, as required by applicable laws, or consented to in writing by Parent (which consent shall not be unreasonably withheld, conditioned or delayed), (a) CSG will use commercially reasonable efforts to conduct and cause each of its subsidiaries to conduct its business in all material respects according to its ordinary course of business consistent with past practice (as may be updated from time to time as is reasonable in light of then-current circumstances to the extent such circumstances are beyond the control of CSG and its subsidiaries), and CSG shall use and shall cause each of its subsidiaries to use its commercially reasonable efforts to, (i) preserve intact its business organization, (ii) preserve the present relationships with those persons having significant business relationships with CSG or any of its subsidiaries (including present relationships with any governmental authority) and (iii) preserve the services of the officers and key employees of CSG and its subsidiaries, and (b) CSG will not, and will not permit any of its subsidiaries to:

Notwithstanding the foregoing, nothing in the merger agreement gives Parent or Merger Sub, directly or indirectly, the right to control or direct the business or operations of CSG or its subsidiaries at any time prior to the effective time. Prior to the effective time, CSG and its subsidiaries will exercise, consistent with the terms and conditions of the merger agreement, complete control and supervision over its own business and operations.

During the period commencing on October 29, 2025 and continuing until the earlier to occur of the termination of the merger agreement and the effective time, CSG shall (and shall cause its wholly owned subsidiaries to and shall use its reasonable best efforts to cause its other subsidiaries to) afford Parent and its representatives reasonable access during normal business hours, on reasonable notice, to the properties, books and records and personnel of CSG and its subsidiaries and, during such period, CSG shall (and shall cause its wholly owned subsidiaries to and shall use its reasonable best efforts to cause its other subsidiaries to) furnish reasonably promptly to Parent all information (financial or otherwise) concerning its business, properties and personnel as Parent may reasonably request, in each case solely for the purpose of consummating the transactions or for reasonable integration planning purposes.

From October 29, 2025 until the effective time or, if earlier, the valid termination of the merger agreement in accordance with its terms, CSG will not, and will cause its subsidiaries not to, and will direct its and their respective representatives, directly or indirectly, not to:

Notwithstanding the foregoing or the below, subject to compliance with the other covenants in the merger agreement, nothing in the merger agreement shall prevent CSG or the CSG Board from:

From October 29, 2025 until the effective time or, if earlier, the valid termination of the merger agreement in accordance with its terms, except to the extent otherwise permitted under the terms of the merger agreement, the CSG Board shall not make a company board recommendation change.

Notwithstanding anything in the merger agreement to the contrary, prior to the time, but not after, the company stockholder approval is obtained, CSG has received an unsolicited written, bona fide acquisition proposal from any person after October 29, 2025 that is not withdrawn and did not result from a breach of the non-solicitation provisions of the merger agreement, the CSG Board determines in good faith (after consultation with its financial advisor(s) and outside legal counsel) that such acquisition proposal constitutes a superior proposal, the CSG Board may, if and only if the CSG Board has determined, in good faith after consultation with its outside legal counsel, that failure to take action would be inconsistent with its fiduciary duties under applicable law, (a) effect a company board recommendation change or (b) terminate the merger agreement pursuant to the applicable termination right therein in order to enter into a definitive written agreement providing for such superior proposal; provided, however, that CSG pays to Parent the termination fee required to be paid pursuant to the merger agreement (as described below); provided, further, that prior to taking any action described in clauses (a) or (b) above:

Any material amendment, revision or supplement to any acquisition proposal will be deemed to be a new acquisition proposal and require a new notice by CSG with a notice period of three business days.

Notwithstanding anything to the contrary set forth in the merger agreement, at any time prior to obtaining the company stockholder approval, the CSG Board may in response to the occurrence of an intervening event, effect a company board recommendation change; provided, that CSG and the CSG Board may only effect such a company board recommendation change if (a) the CSG Board determines in good faith (after consultation with its outside legal counsel) that the failure to take such action in response to an intervening event would be inconsistent with its fiduciary duties under applicable law, (b) CSG provides written notice to Parent at least five business days prior to effecting a company board recommendation change of its intent to take such action, specifying the reasons therefor, including written information describing such intervening event in reasonable detail (and CSG shall keep Parent reasonably informed of material developments with respect to such intervening event), (c) prior to effecting such company board recommendation change, CSG negotiates, and causes its representatives to negotiate, with Parent in good faith (to the extent Parent desires to negotiate) during such five business day period to enable Parent to propose in writing in a binding and irrevocable offer to amend the terms and conditions of the merger agreement that would obviate the basis for the company board recommendation change and (d) no earlier than the end of such five business day period, the CSG Board determines in good faith (after consultation with its financial advisor(s) and outside legal counsel), after considering any amendments to the terms and conditions of the merger agreement proposed in writing by Parent in such binding and irrevocable offer, that the failure to take such action would be inconsistent with its fiduciary duties under applicable law.

Following October 29, 2025, as promptly as practicable, and in any event within 24 hours, following receipt of an acquisition proposal or any inquiries, proposals or offers that would reasonably be expected to lead to an acquisition proposal, CSG will provide Parent with written notice thereof, which notice shall indicate (to the extent known) the identity of the person making such acquisition proposal, inquiry, proposal or offer and include the material terms and conditions thereof. Thereafter, CSG will keep Parent reasonably informed on a prompt and timely basis with respect to the status of or material terms and conditions of any such acquisition proposal, inquiry, proposal or offer (including any amendments or proposed amendments to such material terms). CSG will promptly (and in any event within 24 hours following receipt or delivery thereof) provide Parent with copies of all written acquisition proposals, and all written inquiries, proposals, offers or other materials (including draft and proposed agreements and draft and proposed financing documents) relating to any acquisition proposal or that would reasonably be expected to lead to an acquisition proposal that, in each case, are either received by CSG or any of its representatives from the person(s) making any such acquisition proposal, inquiry, proposal or offer or any of its representatives, or are delivered by CSG or any of its representatives to such person(s) or any of its or their representatives.

Following October 29, 2025, CSG and its subsidiaries will, and shall direct its and their representatives to, immediately cease all existing discussions or negotiations with any person (other than Parent, Merger Sub and their representatives) conducted prior to October 29, 2025 with respect to any inquiry, proposal or offer that constitutes, or could be reasonably be expected to lead to, an acquisition proposal. Promptly after October 29, 2025, CSG shall terminate access by any person (other than Parent, Merger Sub and their representatives) to any physical or electronic dataroom relating to a potential acquisition proposal (or prior discussions in respect of a potential acquisition proposal) and request that each person (other than Parent, Merger Sub and their representatives) that has executed a confidentiality agreement (other than the confidentiality agreement) relating to a potential acquisition proposal (or prior discussions in respect of a potential acquisition proposal) promptly return to CSG or destroy all non-public documents and materials containing non-public information of CSG that has been furnished by CSG or any of its representatives to such person pursuant to the terms of such confidentiality agreement.

For purposes of this merger agreement summary, “acquisition proposal” means: any offer or proposal (other than an offer or proposal by Parent or Merger Sub) to engage in any transaction or series of related transactions resulting in: (a) any acquisition by any person or “group” (as defined under Section 13(d) of the Exchange Act) of beneficial ownership of more than 20% of the outstanding voting securities of CSG or any tender offer or exchange offer that if consummated would result in any person or “group” (as defined under Section 13(d) of the Exchange Act) beneficially owning more than 20% of the outstanding voting securities of CSG; (b) any merger, consolidation, business combination, share exchange, recapitalization, reorganization or other similar transaction involving CSG or its subsidiaries (i) pursuant to which any person or “group” (as defined in or under Section 13(d) of the Exchange Act), other than CSG’s stockholders (as a group) immediately prior to the consummation of such transaction, would

hold, directly or indirectly, equity interests in the surviving or resulting entity of such transaction representing more than 20% of the voting power of the surviving or resulting entity or (ii) as a result of which CSG’s stockholders (as a group) immediately prior to the consummation of such transaction would hold, directly or indirectly, equity interests in the surviving or resulting entity of such transaction representing less than 80% of the voting power of the surviving or resulting entity; or (c) any spin-off, split-off, joint venture or partnership involving, or sale, lease, exchange, transfer, license or other disposition of, more than 20% of the assets of CSG and its subsidiaries on a consolidated basis (determined on a fair market value basis).

For purposes of this merger agreement summary, “intervening event” means: any effect that (a) is material to the business, assets, liabilities, condition (financial or otherwise) or results of operations of CSG and its subsidiaries, taken as a whole, (b) occurs after October 29, 2025, that was neither known to or reasonably foreseeable by the CSG Board as of or prior to October 29, 2025 (or if known, the consequences of which were not known or reasonably foreseeable by the CSG Board as of or prior to October 29, 2025) and (c) does not relate to an acquisition proposal; provided, that, no effect to the extent resulting from, attributable to or arising out of any of the following shall be taken into account in determining whether an “intervening event” has occurred: (i) any change in CSG’s stock price or the trading volume of CSG’s stock or (ii) the fact that CSG exceeds any estimates or expectations of CSG’s revenue, earnings or other financial performance or results of operations for any period or any internal budgets, plans or forecasts of its revenues, earnings or other financial performance or results of operations in each case, in and of itself.

For purposes of this merger agreement summary, “superior proposal” means: a written, bona fide acquisition proposal received by or on behalf of CSG after October 29, 2025 that the CSG Board determines in good faith, after consultation with its financial advisor(s) and outside legal counsel, would be (a) more favorable to CSG’s stockholders, from a financial point of view, than the terms of the merger (including any changes to the terms and conditions of the merger agreement proposed by Parent in response to such acquisition proposal) and (b) reasonably likely to be consummated in accordance with its terms, in the case of each of clauses (a) and (b), taking into account all factors and matters deemed relevant by the CSG Board, including (i) all financial aspects and terms of such acquisition proposal, including the amount, form and timing of payment of consideration, and any termination or break-up fees or expense reimbursement provisions, (ii) all regulatory, legal and stockholder approval aspects and terms of such acquisition proposal, including any conditions to, the likelihood of, and the time likely to be required for consummation of such acquisition proposal on the terms set forth therein, (iii) all financing aspects and terms of such acquisition proposal, including the sources, availability and terms of any financing, financing market conditions and the existence of a financing contingency and (iv) the identity of the person making such acquisition proposal; provided, that for purposes of the reference to an “acquisition proposal” in this definition of a “superior proposal,” all references to “20%” and “80%” in the definition of “acquisition transaction” shall be deemed to be references to “50%”.

For purposes of this merger agreement summary, “company board recommendation change” means any of the following actions by the CSG Board: (i) withdrawing, amending, modifying or qualifying in a manner adverse to Parent or Merger Sub, or publicly proposing to withhold, withdraw, amend, modify or qualify in a manner adverse to Parent or Merger Sub, the company board recommendation, (ii) fail to include the company board recommendation in the proxy statement, (iii) approve or recommend, or propose publicly to approve or recommend, an acquisition proposal, (iv) solely with respect to an acquisition proposal that has been publicly disclosed and does not involve a tender or exchange offer, fail to publicly reaffirm the company board recommendation within ten business days after the public disclosure of such acquisition proposal (or, if the CSG stockholders’ meeting is scheduled to be held within ten business days, then within one business day after Parent so requests in writing); provided, that CSG shall have no obligation to make such reaffirmation more than once with respect to such acquisition proposal unless such acquisition proposal is subsequently modified, in which case CSG shall only be obligated to make such reaffirmation once each time such a modification is made or (v) fail to recommend against any tender or exchange offer that constitutes an acquisition proposal (it being understood that this clause (v) shall not be triggered while the CSG Board refrains from taking a position with respect to such an acquisition proposal until immediately before 5:30 p.m., Eastern time, on the tenth business day after the commencement of a tender or exchange offer in connection with such acquisition proposal); provided, that a “stop, look and listen” communication by the CSG Board or any committee thereof to Company Stockholders pursuant to Rule 14d-9(f) of the Exchange Act shall not

be deemed to be a company board recommendation change, it being understood that neither (1) the determination in itself by the CSG Board that an acquisition proposal constitutes or is reasonably likely to lead to a superior proposal nor (2) the delivery in itself by CSG to Parent of any notice contemplated by this provision will constitute a company board recommendation change.

For purposes of this merger agreement summary, “company stockholder approval” means: the affirmative vote (in person or by proxy) of the holders of a majority of all of the outstanding shares of common stock entitled to vote thereon at the company stockholders’ meeting, or any adjournment, recess or postponement thereof, to adopt the merger agreement.

CSG, acting through the CSG Board (or a committee thereof) shall, as promptly as reasonably practicable following the earlier of the date on which CSG is made aware that the SEC (x) will not review this proxy statement or (y) has no further comments on this proxy statement (the “proxy statement clearance date”), take all necessary actions in accordance with applicable law, the certificate of incorporation or bylaws of CSG and the rules of Nasdaq to establish a record date for, duly call, give notice of, convene and hold a meeting of its stockholders (including any adjournment, recess or postponement thereof, the “company stockholders’ meeting”) for the purpose of obtaining the company stockholder approval, with a record date and meeting date to be selected after reasonable consultation with Parent, which meeting date shall be no later than 30 business days after the proxy statement clearance date. CSG shall solicit from the CSG stockholders proxies in favor of the adoption of the merger agreement in accordance with the DGCL. CSG shall not adjourn or postpone the company stockholders’ meeting without prior written consent of Parent (not to be unreasonably withheld, conditioned or delayed); provided, that CSG shall be permitted to postpone or adjourn the company stockholders’ meeting (a) if the CSG Board has determined in good faith (after consultation with its outside legal counsel) that it is required by applicable law to postpone or adjourn the company stockholders’ meeting in order to allow the CSG stockholders sufficient time to evaluate any information or disclosure that CSG has sent to the CSG stockholders or otherwise made available to the CSG stockholders, (b) to the extent required by a court of competent jurisdiction in connection with any legal proceedings in connection with the merger agreement, (c) if as of the time for which the company stockholders’ meeting is originally scheduled there are insufficient CSG shares represented to constitute a quorum necessary to conduct the business of the company stockholders’ meeting or (d) to solicit additional proxies for the purpose of obtaining the company stockholder approval if either CSG or Parent reasonably believes necessary in order to obtain the company stockholder approval. CSG shall provide Parent reasonably detailed periodic updates concerning proxy solicitation results on a timely basis.

CSG, acting through the CSG Board (or a committee thereof), is required to (a) including in the proxy statement the recommendation (subject to certain exceptions), and, subject to the consent of Jefferies, the written opinion of Jefferies, and (b) use its reasonable best efforts to obtain the company stockholder approval at the company stockholders’ meeting (it being understood that the CSG Board will not be required to recommend in favor of the adoption of the merger agreement if a company board recommendation change has been effected in accordance with the applicable terms of the merger agreement). CSG shall provide Parent reasonably detailed periodic updates concerning proxy solicitation results on a timely basis.

For a period of 12 months following the effective time, the surviving corporation will provide, or Parent will cause the surviving corporation to provide, to each employee of CSG or its subsidiaries who, as of the effective time, continues his or her employment with Parent, the surviving corporation or any of their subsidiaries (each, a “continuing employee”), (i) an annual base salary and target annual cash incentive opportunity that are each no less favorable than the base salary and target annual cash incentive opportunity provided to each continuing employee immediately prior to closing, (ii) other employee benefits that are, at Parent’s sole election, either (a) substantially comparable in the aggregate to the employee benefits (excluding any severance and termination benefits, defined benefit pensions or post-employment health or welfare benefits, retention, change in control or other one-off payments or benefits and any equity-based or long-term incentive compensation) provided to continuing employees immediately prior to the effective time or (b) no less favorable than the employee benefits provided to similarly-situated employees of Parent and its affiliates and (iii) severance and termination benefits that are no less favorable than the severance and termination benefits provided to continuing employees immediately prior to the effective time.

In addition, with respect to Parent’s, the surviving corporation’s or any of their subsidiaries’ plans or programs providing employee benefits to continuing employees on or following the effective time (collectively, the “new plans”), Parent will cause credit for all service with CSG and its subsidiaries prior to the effective time to be granted to continuing employees for all purposes; provided, that such service need not be credited (i) to the extent that it is not taken into account under the analogous plans before the effective time (as reflected in the records of the applicable plan), (ii) for purposes of eligibility to participate in or benefit accrual under any defined benefit plan or post-employment health or welfare plan, (iii) for purposes of vesting of new awards granted under Parent’s long term incentive arrangements, if any, or (iv) to the extent it would result in duplication of coverage or benefits. In addition, Parent will or cause the surviving corporation to use commercially reasonable best efforts to ensure that (a) each continuing employee will be immediately eligible to participate, without any waiting time, in any and all new plans to the extent coverage under each new plan replaces coverage under a comparable plan in which each continuing employee participates immediately before the effective time (such plans, collectively, the “old plans”) and for purposes of each new plan providing medical, dental, pharmaceutical, vision and/or disability benefits to any continuing employee, all waiting periods, pre-existing condition exclusions, evidence of insurability requirements and actively-at-work or similar requirements of each new plan will be waived for each continuing employee and his or her covered dependents to the extent they did not apply to the continuing employee under the corresponding old plan and (b) any eligible expenses incurred by each continuing employee and his or her covered dependents during any unfinished portion of the plan year of the old plan ending on the date each continuing employee’s participation in the corresponding new plan begins will be given full credit under each new plan for purposes of satisfying all deductible, coinsurance and maximum out-of-pocket requirements applicable to each continuing employee and his or her covered dependents for the applicable plan year as if such amounts had been paid in accordance with each new plan.

In addition, in the event that the effective time occurs prior to the completion of the performance period under CSG’s annual bonus plan, the surviving corporation will pay the Closing Year Bonuses. In the event that an employee eligible for the Closing Year Bonus incurs a termination of employment for any reason prior to the payment date of the Closing Year Bonus under circumstances for which each continuing employee would be entitled to receive all or a portion of his or her annual bonus in accordance with the terms of any compensation and benefit plan applicable to him or her, this entitlement will continue to apply.

Each of CSG, Parent and Merger Sub shall use its reasonable best efforts to take, or cause to be taken, all actions that are necessary, proper or advisable to consummate and make effective, as promptly as practicable, the transactions, including using reasonable best efforts to (a) cause each of the conditions to the merger set forth in the merger agreement to be satisfied as promptly as practicable after October 29, 2025, (b) obtain, as promptly as practicable after October 29, 2025, and maintain all necessary actions or non-actions and consents from governmental authorities and make all necessary registrations, declarations and filings with governmental authorities, that are necessary to consummate the transactions (including, for the avoidance of doubt, the money transmitter consents), (c) obtain all necessary consents under any contracts to which CSG or any of its subsidiaries is a party in connection with the merger agreement and the consummation of the transactions and (d) reasonably cooperate with the other party or parties with respect to any of the foregoing. In furtherance of the foregoing, each of Parent and Merger Sub, on the one hand, and CSG, on the other hand, will file or make, as applicable, (i) with the FTC and the antitrust division of the DOJ a Notification and Report Form relating to the merger agreement and the transactions contemplated thereby as required by the HSR Act as promptly as reasonably practicable and in any event within 20 business days after October 29, 2025, (ii) with CFIUS a draft joint voluntary notice as promptly as practicable and in any event within 20 business days after the date hereof and then a final joint voluntary notice as promptly as practicable after receipt of confirmation from CFIUS that it has no further comments on the draft joint voluntary notice and (iii) as promptly as practicable any other submission required under the antitrust laws of Australia, Japan, Kenya, Saudi Arabia, South Africa and the United Kingdom and foreign investment laws of the United Kingdom to effectuate the transactions pursuant to antitrust and foreign investment laws as soon as practicable after October 29, 2025. Each of Parent and CSG shall cooperate and coordinate with the other in the making of such filings, supply the other with any information and documentary material that may be required in order to make such filings, supply any additional information that reasonably may be required or requested by the FTC, DOJ, CFIUS or any foreign governmental authority responsible for the enforcement of any antitrust or foreign direct investment law, cooperate with each other and use their respective reasonable best efforts to contest, resist and settle any legal proceeding that seeks to prohibit, prevent or restricted consummation of any of the transactions and

to have vacated, lifted, reversed or overturned any order that may result from such legal proceedings and use reasonable best efforts to cause the expiration or termination of the applicable waiting periods under the HSR Act and obtain the consents under such other applicable antitrust and foreign direct investment laws.

For purposes of this section, “reasonable best efforts” shall require Parent and Merger Sub, to the extent necessary to obtain clearances, consents, approvals, waivers, actions, waiting period expirations or terminations, non-actions or other authorizations pursuant to the HSR Act or any antitrust or foreign investment laws applicable to the transactions, to use their respective reasonable best efforts to take any steps necessary, proper or advisable to avoid or eliminate each and every impediment under any antitrust or foreign investment law applicable to the transactions by the termination date, including by agreeing to or committing to or effecting by consent decree, hold separate order, contract or otherwise, (i) the sale, divestiture, license, other disposition of, or imposition of any lien or impediment on, any or all of the capital stock or other equity or voting interests, assets (whether tangible or intangible), rights, products or businesses of CSG or any of its subsidiaries or (ii) any other restrictions on the activities of CSG or any of its subsidiaries, including any limitation on the ability of CSG or its subsidiaries to conduct their respective businesses or own any capital stock or assets or to acquire, hold or exercise full rights of ownership of their respective businesses or assets (any action in clauses (i) or (ii), a “regulatory action”); provided, that notwithstanding anything in the merger agreement to the contrary, nothing in this or any other provision of the merger agreement shall require or obligate Parent, Merger Sub, or any of Parent’s affiliates or subsidiaries to, and CSG shall not, without the prior written consent of Parent, agree or commit to effect (A) any regulatory action that would reasonably be expected to, individually or in the aggregate with all other regulatory actions, be a burdensome action or the effectiveness of which is not conditioned upon the closing or (B) the sale, divestiture, license, other disposition of, or imposition of any lien or impediment on, any or all of the capital stock or other equity or voting interests, assets (whether tangible or intangible), rights, products or businesses of Parent or any of its subsidiaries (other than CSG (or the surviving corporation) or any of its subsidiaries) or any other restrictions on the activities of Parent or any of its subsidiaries (other than CSG (or the surviving corporation) or any of its subsidiaries), including any limitation on the ability of Parent or its subsidiaries (other than CSG (or the surviving corporation) or any of its subsidiaries) to conduct their respective businesses or own any capital stock or assets or to acquire, hold or exercise full rights of ownership of their respective businesses or assets (other than CSG (or the surviving corporation) or any of its subsidiaries). “burdensome action” means a regulatory action that (1) would have a material adverse impact on CSG (or the surviving corporation) and its subsidiaries taken as a whole or (2) except with respect to any sales, divestitures, licenses or other dispositions necessary to obtain clearances, consents, approvals, waivers, actions, waiting period expirations or terminations, non-actions or other authorizations pursuant to the HSR Act and all other applicable federal, state, local, foreign or supranational antitrust, competition or premerger notification laws (but not laws that are designed or intended to prohibit or restrict or regulate foreign investment or protect national or regional security or other interests, including laws relating to CFIUS), would have a material adverse impact on the reasonably expected benefits of the transactions to Parent and its affiliates. If so requested by Parent, CSG shall agree to take any and all actions (including, but, for the avoidance of doubt, not limited to, burdensome actions) that are conditioned on the closing.

Each of Parent and Merger Sub (and their respective affiliates, if applicable), on the one hand, and CSG, on the other hand, shall promptly inform the other of any substantive communication from any governmental authority regarding any of the transactions in connection with any filings or investigations with, by or before any governmental authority relating to the merger agreement or the transactions (including, for the avoidance of doubt, the money transmitter consents), including any proceedings initiated by a private party. If any party hereto or an affiliate thereof shall receive a request for additional information or documentary material from any governmental authority with respect to the transactions pursuant to the HSR Act or any other antitrust and foreign investment law or any money transmitter law with respect to which any such filings have been made, then such party shall use its reasonable best efforts to make, or cause to be made, as soon as reasonably practicable and advisable and after consultation with the other party, an appropriate response in substantial compliance with such request. In connection with and without limiting the foregoing, to the extent reasonably practicable and unless prohibited by applicable law or by the applicable governmental authority, the parties hereto agree to (i) give each other reasonable advance notice of all pre-arranged substantive meetings and conference calls with any governmental authority relating to the transactions, (ii) give each other an opportunity to participate in each of such meetings and conference calls, (iii) keep the other party reasonably apprised with respect to any substantive oral communications with any governmental authority regarding the transactions, (iv) cooperate in the submission or filing of any analyses, presentations, memoranda, briefs, arguments, opinions or other substantive written communications explaining or

defending the transactions, articulating any regulatory or competitive argument and/or responding to requests or objections made by any governmental authority, (v) provide each other with a reasonable advance opportunity to review and comment on, and consider in good faith the views of the other with respect to, all substantive written communications (including any analyses, presentations, memoranda, briefs, arguments and opinions) with a governmental authority regarding the transactions (subject to withholding or redactions to address reasonable privilege or confidentiality concerns), (vi) provide each other (or outside counsel of each party, as appropriate) with copies of all substantive written communications to or from any governmental authority relating to the transactions and (vii) cooperate and provide each other with a reasonable opportunity to participate in, and consider in good faith the views of the other regarding, all material deliberations with respect to all efforts to satisfy the conditions set forth in certain provisions of the merger agreement. Any such disclosures, rights to participate or provisions of information by one party to the other may be made on an outside counsel-only (or outside antitrust counsel-only) basis to the extent required under applicable law and may be subject to redactions to remove references concerning the valuation of CSG or confidential competitively sensitive business information of CSG or Parent or any of their subsidiaries.

During the period commencing on October 29, 2025 and continuing until the earlier to occur of the valid termination of the merger agreement and the effective time, Parent shall not, and shall cause its affiliates and subsidiaries not to, acquire or agree to acquire, by merger, consolidation, equity or asset purchase or otherwise, any rights, business, person or division thereof in each case that would reasonably be expected, at the time of such acquisition, to prevent, materially delay or materially impede the obtaining of, or adversely affect in any material respect the ability of Parent to procure, any clearances, approvals, waivers, actions, non-actions, authorizations, consents, orders or declarations of any governmental authority or the expiration or termination of any applicable waiting period to the extent necessary to (x) consummate the transactions, including the merger, and (y) satisfy the conditions set forth in certain section of the merger agreement, including by causing Parent, Merger Sub or CSG to be required to obtain any additional clearances, consents, approvals, waivers, actions, waiting period expirations or terminations, non-actions, or other authorizations that would reasonably be expected to prevent, materially delay or materially impede the obtaining of, or adversely affect in any material respect the ability of Parent to procure, any clearances, approvals, waivers, actions, non-actions, authorizations, consents, orders or declarations of any governmental authority or the expiration or termination of any applicable waiting period to the extent necessary to (x) consummate the transactions and (y) satisfy the conditions set forth in certain sections of the merger agreement.

Notwithstanding anything in the merger agreement to the contrary (i) following good faith consultation with CSG, Parent shall have the exclusive right to make all strategic and tactical decisions as to the matters addressed in the forgoing sections to the extent permissible under the laws or orders of the relevant jurisdiction, including as to the timing, form and content of any communications, analyses, appearances, presentations, memoranda, briefs, arguments, opinions and proposals made or submitted by or on behalf of any party hereto in connection with any legal proceeding under or relating to any antitrust and foreign investment laws; (ii) CSG shall not, nor shall it permit any of its controlled affiliates or representatives to, make any substantive communications with, or proposals relating to, or enter into, any understanding, undertaking or agreement with, any governmental authority relating to the transactions without Parent’s prior review and approval, to the extent permissible under the laws or orders of the relevant jurisdiction; (iii) the obligation of Parent or Merger Sub to take any action described in certain provisions of the merger agreement shall be subject to the right of Parent, in Parent’s good faith reasonable discretion, to take reasonable periods of time in order to advocate and negotiate with any applicable governmental authority with respect to such actions; and (iv) subject to CSG’s consultation and participation rights described in this section, if there are multiple alternative actions or remedies which may result in obtaining consents, registrations, approvals, permits, expirations of waiting periods and authorizations necessary or advisable to be obtained from any third party or any governmental authority in order to consummate the transactions, then Parent shall have sole discretion over which alternative actions or remedies to propose (to the extent that no such remedies take effect prior to the closing without CSG’s consent).

The surviving corporation and its subsidiaries as of the effective time shall (and, Parent shall cause the surviving corporation and its subsidiaries as of the effective time to) honor and fulfill in all respects the obligations of CSG and its subsidiaries under (i) its indemnification agreements with CSG’s current or former directors and officers or any person serving or who served as a director, officer, member, trustee or fiduciary of any corporation, partnership, joint venture, trust, pension or other employee benefit plan or enterprise at the request of CSG or any of

its subsidiaries, in each case, prior to the effective time (collectively, the “indemnified persons”) and (ii) indemnification, expense advancement and exculpation provisions in the certificate of incorporation or bylaws (or similar governing documents) of CSG or its applicable subsidiaries in effect on October 29, 2025. In addition, during the period commencing at the effective time and ending on the sixth anniversary of the effective time, the surviving corporation and its subsidiaries shall (and Parent shall cause the surviving corporation and its subsidiaries to) cause the certificates of incorporation and/or bylaws (and/or similar governing documents) of the surviving corporation and its subsidiaries to contain provisions with respect to indemnification, exculpation and the advancement of expenses with respect to any acts or omissions occurring or alleged to have occurred at or prior to the effective time that are no less favorable than the indemnification, exculpation and advancement of expenses provisions contained in the certificates of incorporation and bylaws (or similar governing documents) of CSG and its subsidiaries as of October 29, 2025, and during such six year period, such provisions shall not be repealed, amended or otherwise modified in any manner adverse to the indemnified persons except as required by applicable law or as provided below.

Prior to the effective time, notwithstanding anything to the contrary set forth in the merger agreement, CSG shall purchase a six year “tail” prepaid policy (the “D&O tail policy”) in respect of acts or omissions occurring at or prior to the effective time, covering each indemnified person on terms with respect to such coverage and amounts no less favorable than CSG’s existing directors’ and officers’ liability insurance policy or, if insurance coverage that is no less favorable is unavailable, the best available coverage; provided, that if the D&O tail policy is not available at an aggregate cost not greater than 300% of the last annual premium paid prior to October 29, 2025 under CSG’s existing directors’ and officers’ liability insurance policy then, prior to the closing, CSG shall obtain as much comparable insurance as can be obtained at a cost up to but not exceeding 300% of the last annual premium paid prior to October 29, 2025. The surviving corporation shall (and Parent shall cause the surviving corporation to) maintain such “tail” policy in full force and effect and continue to honor their respective obligations during the period commencing at the effective time and ending on the sixth anniversary of the effective time.

The merger agreement contains additional agreements among CSG, Parent and Merger Sub relating to, among other matters:

The respective obligations of each of CSG, Parent and Merger Sub to consummate the merger are subject to the satisfaction (or written waiver by CSG and Parent (to the extent permitted by applicable law)) at or prior to the effective time of the following conditions:

The respective obligations of Parent and Merger Sub to effect the merger are also subject to the satisfaction (or written waiver by Parent (to the extent permitted by applicable law)) at or prior to the effective time of the following conditions:

The obligations of CSG to effect the merger is also subject to the satisfaction (or written waiver by CSG (to the extent permitted by applicable law)) at or prior to the effective time of the following conditions: