Sec Form 4/A Filing - Marmurek Eric S @ Ribbon Communications Inc. - 2019-05-15

FORM 4/A 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) Principal Accounting Officer (Last) (First) (Middle) C/O RIBBON COMMUNICATIONS INC., 4 TECHNOLOGY PARK DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 05/15/2019 (Street) WESTFORD, MA01886 4. If Amendment, Date Original Filed (MM/DD/YY) 05/17/2019 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 05/15/2019 S 1,109 ( 1 ) D $ 4.85 31,850 ( 2 ) 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Marmurek Eric S C/O RIBBON COMMUNICATIONS INC. 4 TECHNOLOGY PARK DRIVE WESTFORD, MA01886 Principal Accounting Officer Signatures Eric S. Marmurek 11/19/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 instruction letter previously adopted by the Reporting Person and represent shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of Restricted Stock Awards (RSAs). This amendment to the Form 4 filed on May 17, 2019 by the Reporting Person corrects the fact that these shares were sold pursuant to a Rule 10b5-1 instruction letter instead of by delivering of securities to the Company incident to the vesting of a security. ( 2 )Excludes 36,338 shares of common stock (the "Excluded Shares") underlying an award of Restricted Stock Units granted on April 15, 2019 (the "RSU Award"). The RSU Award was inadvertently reported on Table I instead of Table II on the Form 4 filed by the Reporting Person on April 16, 2019. As a result of this administrative error, the Excluded Shares were erroneously included in the Table I, Column 5 total of the Form 4 filed by the Reporting Person on April 16, 2019.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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