Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Greenberg Samantha Joy 2. Issuer Name and Ticker or Trading Symbol CSG SYSTEMS INTERNATIONAL INC [CSGS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 169 INVERNESS DR. W SUITE 300 3. Date of Earliest Transaction (Month/Day/Year) 05/14/2026 (Street) ENGLEWOOD, CO 80112 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 05/14/2026 D 7,808(1)(2) D $80.7(1)(2) 0 D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Greenberg Samantha Joy 169 INVERNESS DR. W SUITE 300 ENGLEWOOD, CO 80112	X

Signatures

/s/ Andrea Matheny, attorney-in-fact		05/18/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	On May 14, 2026, pursuant to that certain Agreement and Plan of Merger, dated as of October 29, 2025 (the "Merger Agreement"), by and among CSG Systems International, Inc. (the "Issuer"), NEC Corporation ("Parent") and Canvas Transaction Company, Inc., a direct or indirect wholly owned subsidiary of Parent ("Merger Sub"), Merger Sub merged with and into the Issuer (the "Merger"), with the Issuer surviving the Merger as a wholly owned subsidiary of Parent. Pursuant to the Merger Agreement, each share of Issuer common stock, par value $0.01 per share, and each unvested share of restricted stock ("RSA") held by the Reporting Person immediately prior to the closing of the Merger was converted into the right to receive $80.70 in cash, without interest, less any applicable withholding taxes.
(2)	Includes 3,085 RSAs. Any payment with respect to unvested RSAs will be subject to vesting conditions on substantially the same terms and conditions as applied to such awards immediately prior to the effective time of the Merger, except for terms rendered inoperative by reason of the Merger.

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