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                                                                     EXHIBIT 4.6

                         SYNCHRONOSS TECHNOLOGIES, INC.
                               AMENDMENT NO. 1 TO
                          REGISTRATION RIGHTS AGREEMENT

          This Amendment No. 1 to the Registration Rights Agreement
("AMENDMENT") is agreed to as of May 21, 2001, by and between Synchronoss
Technologies Inc., a Delaware corporation (the "COMPANY"), the undersigned
holders (the "STOCKHOLDERS") of the Company's Series A Preferred Stock, $0.0001
par value per share, and Silicon Valley Bank (the "BANK"). Capitalized terms
used herein but not otherwise defined herein shall have the meanings set forth
in the Registration Rights Agreement dated as of November 13, 2000 (the
"REGISTRATION RIGHTS AGREEMENT") between the Company and the Investors (as
defined therein) listed on the signature pages thereto.

          Whereas, the Stockholders are "INVESTORS" as such term is defined in
the Registration Rights Agreement;

          Whereas, the Board of Directors and stockholders of the Company have
approved a transaction (the "LOAN AGREEMENT") between the Company and the Bank,
which provides for the borrowing of up to $3,500,000 from the Bank;

          Whereas, in connection with the Loan Agreement, the Company intends to
issue a Warrant to Purchase Stock (the "WARRANT") to the Bank which will entitle
the Bank to purchase up to 60,345 shares of the Company's Series A Preferred
Stock at an exercise price of $2.90 per share;

          Whereas, the Stockholders and the Company now wish to amend certain
Sections of the Registration Rights Agreement to, among other things, include
the Bank as a party to such agreement to the limited extent set forth herein;

          Whereas, the Bank desires to become a party to the Registration Rights
Agreement for the purposes and to the extent provided herein;

          Whereas, pursuant to Section 2.3 of the Registration Rights Agreement,
the Registration Rights Agreement may only be amended upon the written consent
of the Company and the holders of at least a majority of Registrable Securities
presently outstanding; and

          Whereas, pursuant to Section 1.9 of the Registration Rights Agreement,
the Company shall not grant registration rights to any prospective holder of
Registrable Securities without the written consent of the holders of at least a
majority of the Registrable Securities presently outstanding.

          Now, therefore, the Stockholders, representing a sufficient percentage
of the Registrable Securities to approve this Amendment and consent to the grant
of certain registration rights to the Bank; the Company, in accordance with
Section 2.3 of the Registration Rights Agreement; and the Bank hereby agree as
follows:

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          1. Schedule A to the Registration Rights Agreement shall be amended in
     part to include Silicon Valley Bank, Attn: Treasury Department, 3003 Tasman
     Drive, HG 110, Santa Clara, CA 95054.

          2. The Bank will be treated as an "Investor" with respect to rights
     granted to an "Investor" pursuant to the Registration Rights Agreement,
     including, but not limited to, the registration rights under Sections 1.2,
     1.3 and 1.4 of the Registration Rights Agreement; provided, however, that
     the Bank shall not be entitled to initiate a requested registration
     pursuant to Section 1.2 of the Registration Rights Agreement.

          3. The Stockholders, in accordance with Section 1.9 of the
     Registration Rights Agreement, hereby consent to the Company granting
     certain registration rights to the Bank pursuant to the Registration Rights
     Agreement and this Amendment.

          4. The Bank hereby adopts the Registration Rights Agreement and agrees
     to become a party thereto and subject to the terms and conditions thereof
     as if it were an original party thereto; provided, however, that the Bank
     understands and acknowledges that it shall not be entitled to the rights
     granted to Investors pursuant to Section 1.2 of the Registration Rights
     Agreement.

          5. To the extent not addressed by this Amendment, all other provisions
     of the Registration Rights Agreement shall remain unaffected and in full
     force and effect without change.

          6. This Amendment may be executed in two or more counterparts, each of
     which shall be deemed an original, but all of which together shall
     constitute one and the same instrument.

          7. Except as otherwise provided herein, the terms and conditions of
     this Amendment shall inure to the benefit of and be binding upon the
     respective successors and assigns of the parties.

          8. This Amendment shall be governed by and construed under the laws of
     the State of Delaware as applied to agreements among Delaware residents
     entered into and to be performed entirely within Delaware.

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                                        2

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          In Witness Whereof, each of the parties has executed this Amendment as
of the day and year first above written.

                                        SYNCHRONOSS TECHNOLOGIES, INC.


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        SILICON VALLEY BANK


                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------


                                        STOCKHOLDERS:


Date: May __, 2001
                                        ----------------------------------------
                                        Print Exact Name of Stockholder
                                        (as it appears on the stockholder's
                                        certificate(s))


                                        ----------------------------------------
                                        Signature of Stockholder
                                        (or authorized person on behalf of
                                        Stockholder)

                                        ----------------------------------------
                                        Title of Signatory (if applicable)

                                        Principal Residence/Place of Business:

                                        ----------------------------------------

                                        ----------------------------------------