<PAGE>
                                                                 EXHIBIT 10.7(c)
                           AMENDMENT NO. 3 AND WAIVER



          AMENDMENT NO. 3 AND WAIVER, dated as of December 11, 200l (this
"Amendment"), to the Credit Agreement, dated as of August 17, 1999, as amended
 ---------
by Amendment No. 1, dated as of April 20, 2000, and Amendment No. 2 and Waiver,
dated as of September 29, 2000 (the "Credit Apreement"), among INFONET SERVICES
                                     ----------------
CORPORATION, a Delaware corporation (the "Borrower"), the several banks and
                                          --------
other financial institutions or entities from time to time parties thereto (the
"Lenders"), MERRILL LYNCH & CO., as lead arranger, book manager and syndication
 -------
agent (in such capacity, the "Arranper"), THE BANK OF NOVA SCOTIA, as
                              --------
administrative agent (in such capacity, the "Administrative Agent") and SOCIETE
                                             --------------------
GENERALE, as documentation agent (in such capacity, the "Documumentation
                                                         ---------------
Agent").
-----

                              W I T N E S S E T H:
                              - - - - - - - - - -

          WHEREAS, the Borrower has requested the Lenders to consent to amend
the Credit Agreement as hereinafter set forth; and

          WHEREAS, the Administrative Agent and the Lenders are willing to
consent to the requested amendments on and subject to the terms and conditions
contained herein;

          NOW THEREFORE, in consideration of the premises and mutual covenants
hereinafter set forth, the parties agree as follows:

     I    Definitions. Unless otherwise defined herein, terms defined in the
          -----------
Credit Agreement are used herein as therein defined.

     II   Amendments to Credit Apreement.
          ------------------------------

               2.1    Section 1. The definition of "Cash Equivalents" is hereby
                      ---------
amended to (i) delete the word "and" at the end of clause (f) thereof, (ii)
delete the period at the end of clause (g) thereof and replace such period with
a semicolon followed by the word "and", and (iii) add the following new clause
(h) at the end of clause (g) thereof:

               "and (h) other investments consistent with the Borrower's
               investment policy attached to Amendment No. 3 and Waiver dated as
               of December 11, 200l; provided, that, if the Borrower or any of
                                     --------
               its Subsidiaries shall acquire any of such investments having a
               maturity more than one year after the date of acquisition
               thereof, then, so long as the Borrower or such Subsidiary, as the
               case may be, holds such investments the Borrower and its
               Subsidiaries will hold cash and Cash Equivalents (having a
               maturity of not more than one year after the date of acquisition
               thereof) in an aggregate amount not less than the sum of the
               aggregate amount of Term Loans outstanding plus the Total
               Revolving Credit Commitments then in effect."

<PAGE>


               2.2    Section 2.10. Section 2.10(b) of the Credit Agreement is
                      ------------
hereby amended by inserting the following sentence at the end of such Section:

               "In addition, unless the Required Prepayment Lenders otherwise
               agree, if during any fiscal quarter the Borrower shall make
               Restricted Payments pursuant to exception (i) in Section 7.6, the
               Borrower shall prepay the Term Loans in an amount equal to 50% of
               the amount of such Restricted Payments (each such prepayment to
               be made as promptly after the end of each fiscal quarter in which
               such Restricted Payments were made as will be consistent with
               avoiding making prepayments on Term Loans that are Eurodollar
               Loans on a date other than the last day of an Interest Period
               with respect thereto)."

               2.3    Section 7.3. Section 7.3(g) of the Credit Agreement is
                      -----------
hereby amended by inserting the following clause at the end of such Section:

               "and Hedge Agreements entered into by the Borrower pursuant to
               Section 7.15 relating to the Indebtedness permitted by Section
               7.2(c);"

               2.4    Section 7.6. Section 7.6 of the Credit Agreement is hereby
                      -----------
amended by (a) deleting exception (i) of such Section and substituting in lieu
thereof the following clause:

               "(i) if at the time and after giving effect thereto no Default or
               Event of Default shall have occurred and be continuing, the
               Borrower or any of its Subsidiaries may make any such Restricted
               Payments, provided that the sum of such Restricted Payments shall
               not exceed $100,000,000 in the aggregate while this Agreement is
               in effect and that no proceeds of the Revolving Credit Loans may
               be used for such purposes,"

and (b) adding a new clause (iii) to the end of such Section to read as follows:

               "and (iii) the Borrower may acquire Capital Stock in exchange for
               its Capital Stock."

               2.5 Section 7.8. Section 7.8(m) of the Credit Agreement is hereby
                   -----------
amended by deleting "on or prior to October 6; 2001" in line 1 and by deleting
"$l0,000,000" in line 2 and substituting in lieu thereof "$20,000,000".

               2.6 Section 7.17. Section 7.17 of the Credit Agreement is hereby
                   ------------
amended by deleting "$10,000,000" in the final line of such Section and
substituting in lieu thereof "$20,000,000".

     III  Waiver. The Lenders hereby waive any violation of Section 7.8 of the
          ------
Credit Agreement which may have occurred prior to the date of this Amendment as
a result of Investments which complied with the Borrower's investment policy
attached hereto but which were not Cash Equivalents under the Credit Agreement
as in effect prior to the date of this Amendment.

                                        2

<PAGE>

     IV   Conditions Precedent. This Amendment shall become effective as of the
          --------------------
date hereof when each of the conditions precedent set forth below shall have
been fulfilled (the date such conditions are fulfilled, the "Amendment Effective
                                                             -------------------
Date"):
----

               4.1  Amendment. The Administrative Agent shall have received this
                    ---------
Amendment, executed and delivered by a duly authorized officer of each of the
Loan Parties and the Required Lenders.

               4.2  No Default or Event of Default. On and as of this Amendment
                    ------------------------------
Effective Date and after giving effect to this Amendment and the transactions
contemplated hereby, no Default or Event of Default shall have occurred and be
continuing.

               4.3  Representation and Warranties. The representations and
                    -----------------------------
warranties made by each Loan Party in each Loan Document to which it is a party
and herein after giving effect to this Amendment and the transactions
contemplated hereby shall be true and correct in all material respects on and as
of the Amendment Effective Date, after giving effect to this Amendment, as if
made on such date, except where such representations and warranties relate to an
earlier date in which case such representations and warranties shall be true and
correct as of such earlier date.

     V    General.
          -------

               5.1  Representation and Warranties. The Borrower represents and
                    -----------------------------
warrants to each Lender and the Administrative Agent as follows:

                    (a) Corporate Power: Authorization; Enforceable Obligations.
                        -------------------------------------------------------

                        (i)    Each Loan Party has the corporate power and
          authority, and the legal right, to make and deliver this Amendment and
          to perform the Loan Documents to which it is a party, as amended by
          this Amendment, and has taken all necessary corporate action to
          authorize the execution, delivery and performance of this Amendment
          and the performance of such Loan Documents, as so amended.

                        (ii)   No consent or authorization of, approval by,
          notice to, filing with or other act by or in respect of, any
          governmental authority or any other Person is required in connection
          with the execution and delivery of this Amendment to which any Loan
          Party is a party or with the performance, validity or enforceability
          of the Loan Documents to which it is a party, as amended by this
          Amendment.

                        (iii)  This Amendment has been duly executed and
          delivered on behalf of each of the Loan Parties party hereto.

                        (iv)   This Amendment and each Loan Document to which a
          Loan Party is a party, as amended by this Amendment, constitutes a
          legal, valid and binding obligation of such Loan Party enforceable
          against such Loan Party in accordance with its terms, except as
          affected by bankruptcy, insolvency,

                                        3

<PAGE>

          fraudulent conveyance, reorganization, moratorium and other similar
          laws relating to or affecting the enforcement of creditors' rights
          generally, general equitable principles (whether considered a
          proceeding in equity or at law) and an implied covenant of good faith
          and fair dealing.

                    (b)   No Legal Bar. The execution, delivery and performance
                          ------------
     of this Amendment and the performance of the Loan Documents to which each
     Loan Party is a party, as amended by this Amendment, will not violate any
     Requirement of Law or contractual obligation of any Loan Party or of any of
     their Subsidiaries and will not result in, or require, the creation or
     imposition of any Lien on any of its or their respective properties or
     revenues pursuant to any such Requirement of Law or contractual obligation.

                    (c)   Representations and Warranties in Loan Documents. The
                          ------------------------------------------------
     representations and warranties set forth in each Loan Document are, after
     giving effect to this Amendment, true and correct in all material respects
     as if made on and as of this Amendment Effective Date, except as they may
     specifically relate to an earlier date.

               5.2  Continuing Effect of Credit Agreement. This Amendment shall
                    -------------------------------------
not constitute an amendment or waiver of any provision of the Credit Agreement
not expressly referred to herein and shall not be construed as an amendment,
waiver or consent to any action on the part of any party hereto that would
require an amendment, waiver or consent of the Administrative Agent or the
Lenders except as expressly stated herein. Except as expressly waived or amended
hereby, the provisions of the Credit Agreement are and shall remain in full
force and effect.

               5.3  Affirmation of Security Documents. Each of the Parties
                    ---------------------------------
hereto agrees that the execution and delivery of this Amendment and the
performance of the Credit Agreement shall not in any way affect such Person's
obligations under any Security Document to which such Person is a party, which
obligations on the date hereof remain absolute and unconditional and are not
subject to any defense, set-off or counterclaim.

               5.4  Expenses. The Borrower agrees to pay or reimburse the
                    --------
Administrative Agent for all of its reasonable out-of-pocket costs and expenses
incurred in connection with (a) the negotiation, preparation, execution and
delivery of this Amendment and any other documents prepared in connection
herewith, and consummation of the transactions contemplated hereby and thereby,
including the fees and expenses of Simpson Thacher & Bartlett, counsel to the
Administrative Agent, and (b) the enforcement or preservation of any rights
under this Amendment and any other such documents.

               5.5  GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED BY, AND
                    -------------
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

               5.6  Counterparts. This Amendment may be executed in any number
                    ------------
of counterparts by the parties hereto, each of which counterparts when so
executed shall be an original, but all counterparts taken together shall
constitute one and the same instrument.

                                        4
/

<PAGE>


           IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and delivered by their respective duly authorized officers as
of the day and year first above written.

                                       INFONET SERVICES CORPORATION

                                       By:  /s/ Akbar H. Firdosy
                                           -------------------------------------
                                       Name:  Akbar H. Firdosy
                                       Title: Vice President, Chief Financial
                                              Officer, Treasurer

                                       IINS, INC.

                                       By:    /s/ Akbar H. Firdosy
                                           -------------------------------------
                                       Name:  Akbar H. Firdosy
                                       Title: Vice President, Chief Financial
                                              Officer, Treasurer

                                       ESG COMMUNICATIONS INCORPORATED

                                       By:    /s/ Akbar H. Firdosy
                                           -------------------------------------
                                       Name:  Akbar H. Firdosy
                                       Title: Vice President, Chief Financial
                                              Officer, Treasurer

                                       INFONET BROADBAND SERVICES CORPORATION

                                       By:    /s/ Akbar H. Firdosy
                                           -------------------------------------
                                       Name:  Akbar H. Firdosy
                                       Title: Vice President, Chief Financial
                                              Officer, Treasurer

                                       MERRILL LYNCH & CO., as Lead Arranger,
                                       Book Manager and Syndication Agent

                                       By:______________________________________
                                       Name:
                                       Title:


                                       MERRILL LYNCH CAPITAL CORPORATION,
                                       as lender

                                       By:______________________________________
                                       Name:
                                       Title:

                                       S-1

<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be duly executed and delivered by their respective duly authorized
officers as of the day and year first above written.

                                        INFONET SERVICES CORPORATION

                                        By: ____________________________________
                                        Name:
                                        Title:


                                        IINS, INC.


                                        By: ____________________________________
                                        Name:
                                        Title:


                                        ESG COMMUNICATIONS INCORPORATED


                                        By: ____________________________________
                                        Name:
                                        Title:


                                        INFONET BROADBAND SERVICES CORPORATION


                                        By: ____________________________________
                                        Name:
                                        Title:


                                        MERRILL LYNCH & CO., as Lead Arranger,
                                        Book Manager and Syndication Agent

                                        By:   /s/ Sheila McGillicuddy
                                            ------------------------------------
                                        Name:  Sheila McGillicuddy
                                        Title: Director

                                      S-1

<PAGE>

           IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and delivered by their respective duly authorized oficers as of
the day and year first above written.

                                              INFONET SERVICES CORPORATION


                                              By: ______________________________
                                              Name:
                                              Title:

KFW
KREDITANSTALT FUR WIEDERAUFBAU
Date: 18.12.2001                              IINS, INC.


By: /s/ Mr. Bellman   /s/ Mr. Wagner          By: ______________________________
   ----------------------------------
Name: Mr. Bellmann     Mr. Wagner             Name:
                                              Title:
Title: Vice President  Sen. Project Manager

                                              ESG COMMUNICATIONS INCORPORATED


                                              By: ______________________________
                                              Name:
                                              Title:


                                              INFONET BROADBAND SERVICES
                                              CORPORATION


                                              By: ______________________________
                                              Name:
                                              Title:


                                              MERRILL LYNCH & CO., as Lead
                                              Arranger, Book Manager and
                                              Syndication Agent

                                              By: ______________________________
                                              Name:
                                              Title:

                                       S-l

<PAGE>

                                        MERRILL LYNCH CAPITAL CORPORATION,
                                        as Lender


                                        By:________________________________
                                        Name:
                                        Title:


                                        THE BANK OF NOVA SCOTIA, as a Lender and
                                        as Administrative Agent


                                        By: /s/ Vincent Fitzgerald
                                           ---------------------------------
                                        Name:   VINCENT I. FITZGERALD, JR.
                                        Title:  AUTHORIZED SIGNATORY

                                      S-2

<PAGE>

                                        ABN AMRO BANK N.V.


                                        By:    /s/ David C. Carrington
                                               ---------------------------
                                        Name:  David C. Carrington
                                        Title: Group Vice President

                                        By:    /s/ Shilpa Parandekar
                                               ---------------------------
                                        Name:  Shilpa Parandekar
                                        Title: Assistant Vice President

                                       S-1

<PAGE>





                                        THE FUJI BANK, Ltd.



                                        By:    /s/ Masahito Fukuda
                                               ---------------------------
                                        Name:  Masahito Fukuda
                                        Title: Senior Vice President



                                      S-13

<PAGE>


                                        UBS AG, Stamford Branch


                                        By:    /s/ Wilfred V. Saint
                                               ---------------------------
                                        Name:  Wilfred V. Saint
                                        Title: Associate Director
                                               Banking Products
                                               Services, US



                                        By:    /s/ Thomas R. Salzano
                                               ---------------------------
                                        Name:  Thomas R. Salzano
                                        Title: Director
                                               Banking Products Services, US

                                       S-1

<PAGE>

                                                LEHMAN COMMERCIAL PAPER, INC.


                                                By: /s/ G. Andrew Keith
                                                    ----------------------------
                                                Name:   G. Andrew Keith
                                                Title:  Authorized Signatory

                                      S-1

<PAGE>

                                                IBM Credit Corporation

                                                By: /s/ Thomas S Curcio
                                                    ----------------------------
                                                Name:  Thomas S Curcio
                                                Title: Manager of Credit

                                      S-2

<PAGE>

                                        Societe Generale,
                                        As Documentation Agent and as Lender

                                        By:    /s/ Mark Vigil
                                              ---------------------------
                                        Name:  Mark Vigil
                                        Title: Director

                                      S-3

<PAGE>

                                        MERRILL LYNCH CAPITAL CORPORATION,
                                        as Lender


                                        By: /s/ Howard B Sysler
                                           ----------------------------------
                                        Name:   Howard B Sysler
                                        Title:  Vice President


                                        THE BANK OF NOVA SCOTIA, as a Lender and
                                        as Administrative Agent


                                        By: _________________________________
                                        Name:
                                        Title:

                                       S-2

<PAGE>

                                IKB Deutsche Industriebank AG
                                Luxembourg Branch

                                By:   /s/ Ana Bohorquez       /s/ Keuchel
                                      ------------------------------------
                                Name: Ana Bohorquez
                                Title: Assistant Director      Anja Keuchel
                                                                 Manager



Infonet Amendment No. 3 and Waiver

<PAGE>

                                                PILGRIM PRIME RATE TRUST
                                                By: ING Pilgrim Investments, LLC
                                                    as its investment manager

                                                By: /s/ Mark F. Haak
                                                   -----------------------------
                                                Name:   Mark F. Haak, CFA
                                                Title:  Vice President

<PAGE>

                                        NIB CAPITAL BANK NV

                                        By: /s/ E. Jager     /s/ B. J. Volkeda
                                            ------------------------------------
                                        Name:   E. Jager         B. J. Volkeda
                                        Title:

                                      S-1