Sec Form 4 Filing - Marmurek Eric S @ Ribbon Communications Inc. - 2024-03-15

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Marmurek Eric S 2. Issuer Name and Ticker or Trading Symbol Ribbon Communications Inc. [ RBBN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) SVP, Finance & CAO (Last) (First) (Middle) 6500 CHASE OAKS BLVD., STE. 100 3. Date of Earliest Transaction (MM/DD/YY) 03/15/2024 (Street) PLANO, TX75023 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 03/15/2024 M 4,116 A 251,812 D Common Stock 03/15/2024 M 1,581 A 253,393 D Common Stock 03/15/2024 F 1,554 D $ 2.83 ( 3 ) 251,839 D

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Restricted Stock Units (RSUs) ( 1 ) 03/15/2024 M 4,116 ( 4 ) ( 4 ) Common Stock 4,116 $ 0 0 D Performance-Based Restricted Stock Units ( 1 ) 03/15/2024 M 1,581 ( 2 ) ( 2 ) Common Stock 1,581 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Marmurek Eric S 6500 CHASE OAKS BLVD. STE. 100 PLANO, TX75023 SVP, Finance & CAO Signatures Patrick Macken, By POA from Rick Marmurek, SVP, CAO 03/18/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each Restricted Stock Unit (RSU) and Performance Share Unit (PSU) converts into common stock on a one-for-one basis. ( 2 )The number of PSUs earned and issued upon vesting was determined based on goals (set by the Compensation Committee of the Issuer's Board of Directors (the "Compensation Committee") on an annual basis) for each of the three fiscal years ended December 31, 2023. Based on the Compensation Committee's determination of achievement of these pre-established financial goals, 32% of the shares subject to the 2023 financial period were earned and vested on March 15, 2024, and no shares were earned for the 2021 and 2022 performance periods and were forfeited. ( 3 )Reflects shares of Common Stock withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting of the RSUs and PSUs. ( 4 )The RSUs were granted on March 15, 2021 and vested as to one-third on March 15, 2022; the remaining two-thirds of the RSUs vested in four equal semi-annual installments thereafter through March 15, 2024.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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