April 30, 2019

Daryl E. Raiford
Chief Financial Officer
Ribbon Communications Inc.
4 Technology Drive
Westford, MA 01886

       Re: Ribbon Communications Inc.
           Form 10-K for Fiscal Year Ended December 31, 2018
           Filed March 4, 2019
           Form 8-K furnished February 20, 2019
           File No. 001-38267

Dear Mr. Raiford:

       We have reviewed your filings and have the following comments. In some
of our
comments, we may ask you to provide us with information so we may better
understand your
disclosure.

       Please respond to these comments within ten business days by providing
the requested
information or advise us as soon as possible when you will respond. If you do
not believe our
comments apply to your facts and circumstances, please tell us why in your
response.

       After reviewing your response to these comments, we may have additional
comments.

Form 8-K Furnished on February 20, 2019

General

1.    We note your adjustment for "acquisition-related revenue" included in
your various non-
      GAAP measures. Considering your deferred revenue was adjusted to fair
value at the
      time of acquisition pursuant to GAAP, please tell us how you considered
whether your
      various non-GAAP measures that include this adjustment are substituting
an individually
      tailored recognition and measurement method for a GAAP measure. Refer to
Question
      100.04 of the Non-GAAP Compliance and Disclosure Interpretations and Rule
100(b) of
      Regulation G.
 Daryl E. Raiford
FirstName LastNameDaryl E. Raiford
Ribbon Communications Inc.
Comapany NameRibbon Communications Inc.
April 30, 2019
Page 30,
April 2 2019 Page 2
FirstName LastName
2.       Similarly, please clarify for us what the purchase accounting
adjustment to cost of revenue
         consists of and how you considered whether your various non-GAAP
measures that
         include this adjustment are substituting an individually tailored
recognition and
         measurement method for a GAAP measure. Refer to Question 100.04 of the
Non-GAAP
         Compliance and Disclosure Interpretations and Rule 100(b) of
Regulation G.
3.       You state that GAAP required the elimination of revenue under the new
revenue
         recognition standard in 2018, which you are adding back to arrive at
various non-GAAP
         measures. Please clarify for us what revenue was eliminated with the
adoption of ASC
         606 and how your non-GAAP adjustment for such amounts captures the
economics of
         your activities. Also, please confirm for us that similar adjustments
will not be made to
         fiscal 2019 non-GAAP measures.
4.       We note your non-GAAP net income reconciliation includes income tax
adjustments
         related to benefits arising from purchase accounting and the Tax
Reform. Please explain
         to us, and revise your future filings to disclose, how you calculated
the tax effects of your
         non-GAAP net income adjustments. In this regard, your tax adjustment
should also
         include current and deferred income tax expense commensurate with your
non-GAAP
         measure of profitability. Refer to Question 102.11 of the Non-GAAP
Compliance and
         Disclosure Interpretations.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

       You may contact Rebekah Lindsey, Staff Accountant at (202) 551-3303 or
Kathleen
Collins, Accounting Branch Chief at (202) 551-3499 if you have any questions.



                                                                Sincerely,

                                                                Division of
Corporation Finance
                                                                Office of
Information Technologies
                                                                and Services