EXHIBIT 99.3

                            CERTIFICATE OF AMENDMENT
                                       OF
            FOURTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                              SONUS NETWORKS, INC.

    Sonus Networks, Inc., a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware (the
"CORPORATION"), DOES HEREBY CERTIFY:

    FIRST: That at a meeting of the Board of Directors of the Corporation,
resolutions were duly adopted setting forth a proposed amendment to the Fourth
Amended and Restated Certificate of Incorporation of said corporation, declaring
said amendment to be advisable and directing the holders of Common Stock of said
corporation to consider said amendment and to indicate their approval and
adoption thereof. The resolution setting forth the proposed amendment is as
follows:

    RESOLVED:  That the first sentence of Article IV of the Fourth Amended and
               Restated Certificate of Incorporation of the Corporation be, and
               it hereby is, amended to read as follows:

           The total number of shares of capital stock which the
           corporation shall have authority to issue is 605,000,000,
           consisting solely of:

               600,000,000 shares of common stock, par value
               $0.001 per share ("Common Stock"); and

               5,000,000 shares of preferred stock, par value
               $0.01 per share ("Preferred Stock").

    RESOLVED:  That except as expressly amended hereby no other aspect of such
               Article IV shall be modified hereby.

    SECOND: That thereafter, pursuant to said resolutions of its Board of
Directors, the holders of record of not less than a majority of the issued and
outstanding shares of Common Stock of said Corporation, representing not less
than the minimum number of votes necessary to authorize and take such action,
duly adopted such an amendment at the Annual Meeting of the Shareholders in
accordance with Sections 211 and 222 of the General Corporation Law of the State
of Delaware.

    THIRD: That said amendment was duly adopted in accordance with the
provisions of Section 242 of the General Corporation Law of the State of
Delaware.

    IN WITNESS WHEREOF, the Corporation has caused this certificate to be signed
by Stephen J. Nill, its Vice President Finance and Administration and Chief
Financial Officer, this 29th day of May, 2001.


                                                      
                                                       SONUS NETWORKS, INC.

                                                       By:  /s/ STEPHEN J. NILL
                                                            -----------------------------------------
                                                            Stephen J. Nill
                                                            VICE PRESIDENT FINANCE AND ADMINISTRATION
                                                            AND CHIEF FINANCIAL OFFICER