<PAGE>
                                                                     Exhibit 4.3

                        AFFILIATE SUBORDINATION AGREEMENT

          AFFILIATE SUBORDINATION AGREEMENT dated as of December 9, 2003,
between GLOBAL CROSSING NORTH AMERICAN HOLDINGS, INC., a corporation duly
organized and validly existing under the laws of the State of Delaware (the
"Issuer"), GLOBAL CROSSING LIMITED (formerly GC Acquisition Limited), a company
duly organized and validly existing under the laws of Bermuda (the "Company"),
the other entities identified on the signature pages hereto under the caption
"GUARANTORS" (the Company together with such other entities being herein called
the "Guarantors" and, together with the Issuer, the "Credit Parties") and WELLS
FARGO BANK MINNESOTA, N.A., as trustee and agent under the below-referenced
Indenture (in such capacity, together with its successors in such capacity, the
"Trustee").

          Pursuant to an Indenture dated as of December 9, 2003 (as modified
and supplemented and in effect from time to time, the "Indenture") by and
between the Credit Parties and the Trustee for the benefit of the holders of the
Notes (as hereinafter defined), the Issuer has issued $200,000,000 of its 11%
Senior Secured Notes due 2006 (the "Notes") and the Guarantors have
unconditionally guaranteed all of the obligations of the Issuer under and in
respect of the Notes.

          To induce the holders of the Notes to accept the same on the terms and
conditions as provided in the Indenture, and in accordance with Section
4.09(e)(i) of the Indenture, each Credit Party has agreed to subordinate any
Subordinated Indebtedness (as hereinafter defined) held by it to all Senior
Indebtedness (as hereinafter defined), all in the manner and to the extent
hereinafter provided. Accordingly, the parties hereto agree as follows:

          Section 1. Definitions. Terms defined in the Indenture are used herein
as defined therein. In addition, as used herein:

          "Senior Indebtedness" shall mean the following indebtedness and
obligations:

          (a) all indebtedness and other obligations of the Issuer under the
     Notes, of the Guarantors under the Note Guarantees and (without
     duplication) of the Credit Parties under the Indenture (as the same may be
     modified and supplemented from time to time, and including all agreements
     extending, renewing or refinancing the same); and

          (b) all interest accruing after the commencement of any proceedings
     referred to in Section 2.01(ii) below, whether or not such interest is an
     allowed claim in such proceeding.

          "Subordinated Indebtedness" shall mean any intercompany indebtedness
or intercompany accounts payable or other intercompany obligations of a Credit
Party owing to any other Credit Party or (without duplication) to any Restricted
Subsidiary.

          "Subordinated Indebtedness Documents" shall mean any credit agreement,
promissory note, indenture or other agreement or instrument evidencing any
Subordinated Indebtedness.

                        Affiliate Subordination Agreement

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                                       2

          Section 2. Subordination.

          2.01 Subordination of Subordinated Indebtedness. Anything in any
Subordinated Indebtedness Document to the contrary notwithstanding, each Credit
Party, for itself and its successors and assigns, covenants and agrees that, to
the extent and in the manner hereinafter set forth, all Subordinated
Indebtedness held by such Credit Party and its successors and assigns (such
Credit Party and its successors and assigns, the "Affiliate Holder"), and the
payment from whatever source of the principal of, and interest and premium (if
any) on, such Subordinated Indebtedness, are hereby expressly made subordinate
and subject in right of payment to the prior payment in full in cash of all
Senior Indebtedness:

          (i) The holders of Senior Indebtedness shall be entitled to receive
     payment in full in cash of all amounts constituting Senior Indebtedness
     before such Affiliate Holder is entitled to receive any payment on account
     of the Subordinated Indebtedness held by it (and unless and until all
     Senior Indebtedness has been so paid, such Affiliate Holder will not (x)
     ask, demand, sue for, take or receive from any Credit Party obligated in
     respect of such Subordinated Indebtedness (each, a "Credit Party Obligor"),
     by set-off or in any other manner, or (y) seek any other remedy allowed at
     law or in equity against any Credit Party Obligor for breach of such Credit
     Party Obligor's obligations under any Subordinated Indebtedness Document,
     provided that, so long as at the time thereof and after giving effect
     thereto no Event of Default shall have occurred and be continuing,
     unremedied and unwaived, under the Indenture, any Credit Party Obligor may
     make, and such Affiliate Holder shall be entitled to receive and retain,
     payments in respect of the principal of and interest of the Subordinated
     Indebtedness.

          (ii) In the event of any insolvency or bankruptcy proceedings, and any
     receivership, liquidation, reorganization or other similar proceedings in
     connection therewith, relative to any Credit Party Obligor or to its
     creditors, as such, or to its property, and in the event of any proceedings
     for voluntary liquidation, dissolution or other winding up of any Credit
     Party Obligor, whether or not involving insolvency or bankruptcy, then the
     holders of Senior Indebtedness shall be entitled to receive payment in full
     of all amounts constituting Senior Indebtedness before such Affiliate
     Holder is entitled to receive, or make any demand for, any payment on
     account of the Subordinated Indebtedness, and to that end the holders of
     Senior Indebtedness shall be entitled to receive for application in payment
     thereof any payment or distribution of any kind or character, whether in
     cash or property or securities.

          (iii) If any payment or distribution of any character, whether in
     cash, securities or other property, in respect of any Subordinated
     Indebtedness shall (despite these subordination provisions) be received by
     such Affiliate Holder before all Senior Indebtedness shall have been paid
     in full in cash, such payment or distribution shall be held in trust for
     the benefit of, and shall be paid over or delivered to, the holders of
     Senior Indebtedness (or their representatives), and to holders of any other
     Indebtedness to which the Subordinated Indebtedness is similarly
     subordinated, ratably according to the respective aggregate amounts
     remaining unpaid thereon, to the extent necessary to pay all Senior
     Indebtedness, and all such other Indebtedness, in full.

                        Affiliate Subordination Agreement

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                                       3

          No present or future holder of Senior Indebtedness shall be prejudiced
in its right to enforce subordination of any Subordinated Indebtedness or any
Subordinated Indebtedness Document by any act or failure to act on the part of
any Credit Party Obligor or by any act or failure to act, in good faith on the
part of such holder or any trustee or agent for such holder. The foregoing
provisions are solely for the purpose of defining the relative rights of the
holders of Senior Indebtedness on the one hand, and each Affiliate Holder on the
other hand, and nothing herein shall impair, as between any Credit Party Obligor
and any Affiliate Holder, the obligation of such Credit Party Obligor, which is
unconditional and absolute, to pay to such Affiliate Holder any principal of
Subordinated Indebtedness and interest thereon in accordance with the terms of
any Subordinated Indebtedness Document.

          2.02 Subrogation. Subject to the payment in full in cash of all Senior
Indebtedness, each Affiliate Holder shall be subrogated to the rights of the
holders of such Senior Indebtedness to receive payments and distributions of
cash, property and securities applicable to the Senior Indebtedness until the
principal of, and interest on, the Subordinated Indebtedness held by such
Affiliate Holder shall be paid in full in cash. For purposes of such
subrogation, no payments or distributions to the holders of Senior Indebtedness
of any cash, property or securities to which any Affiliate Holder would be
entitled except for the provisions of Section 2.01, and no payments over
pursuant to the provisions of Section 2.01 to the holders of Senior Indebtedness
by any Affiliate Holder, shall, as between the applicable Credit Party Obligor,
its creditors other than holders of Senior Indebtedness, and such Affiliate
Holder, be deemed to be a payment or distribution by such Credit Party Obligor
to or on account of the Senior Indebtedness.

          2.03 Defaults. If after payment in full in cash of the Senior
Indebtedness, any payment of Subordinated Indebtedness is not made when due or
any other event of default shall occur in respect of such Subordinated
Indebtedness, the applicable Affiliate Holder may declare all amounts owing in
respect of such Subordinated Indebtedness due and payable, provided that if
after repayment in full of the Senior Indebtedness, any payments of Senior
Indebtedness shall at any time be rescinded or otherwise must be returned by the
holder of any Senior Indebtedness, such demand, if made, shall be automatically
rescinded.

          Section 3. Miscellaneous.

          3.01 Notices. All notices, waivers, requests, consents, demands,
directions and other instruments delivered pursuant to the terms of this
Agreement shall be in writing in the English language or accompanied by a
certified English translation (which English translation shall be considered the
original instrument and shall control in case of any conflict between the
English and foreign language versions) and telecopied or delivered to the
respective parties hereto as provided in Section 12.02 of the Indenture. All
such communications shall be deemed to have been given at the times specified in
said Section 12.02. The Trustee shall receive a copy of any notice under this
Agreement from any Credit Party to any other Credit Party.

          3.02 No Waiver. No failure on the part of the Trustee or any Holder to
exercise, and no course of dealing with respect to, and no delay in exercising,
any right, power or remedy hereunder shall operate as a waiver thereof; nor
shall any single or partial exercise by the Trustee or any Holder of any right,
power or remedy hereunder preclude any other or further exercise

                        Affiliate Subordination Agreement

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                                       4

thereof or the exercise of any other right, power or remedy. The remedies herein
are cumulative and are not exclusive of any remedies provided by law.

          3.03 Amendments, Etc. The terms of this Agreement may be waived,
altered or amended only by an instrument in writing duly executed by each Credit
Party and the Trustee. Any such amendment or waiver shall be binding upon the
Trustee, each Holder and each Credit Party. The Trustee shall not be obligated
to enter into any amendment, waiver or alteration that affects the Trustee's own
rights, duties, immunities or indemnities hereunder or under the Indenture, the
Global Security Agreement or otherwise except in accordance with the terms
hereof.

          3.04 Successors and Assigns. This Agreement shall be binding upon and
inure to the benefit of the respective successors and assigns of each Credit
Party, the Trustee and each Holder.

          3.05 Counterparts. This Agreement may be executed in any number of
counterparts, all of which taken together shall constitute one and the same
instrument and any of the parties hereto may execute this Agreement by signing
any such counterpart.

          3.06 Governing Law. This Agreement shall be governed by, and construed
in accordance with, the law of the State of New York.

          3.07 Captions. The captions and section headings appearing herein are
included solely for convenience of reference and are not intended to affect the
interpretation of any provision of this Agreement.

          3.08 Agents and Attorneys-in-Fact. The Trustee may employ agents and
attorneys-in-fact in connection herewith and shall not be responsible for the
gross negligence or willful misconduct of any such agents or attorneys-in-fact
selected by it in good faith.

          3.09 Severability. If any provision hereof is invalid and
unenforceable in any jurisdiction, then, to the fullest extent permitted by law,
(a) the other provisions hereof shall remain in full force and effect in such
jurisdiction and (b) the invalidity or unenforceability of any provision hereof
in any jurisdiction shall not affect the validity or enforceability of such
provision in any other jurisdiction.

          3.10 Rights, Privileges; Etc. The rights, privileges, immunities,
indemnities and standard of care provided to the Trustee under Article VIII of
the Indenture and the Global Security Agreement shall, to the extent applicable,
apply in this Agreement and to the Trustee's acts and omissions related to this
Agreement as if fully set forth herein.

          3.11 Enforcement. By the Trustee's signature below and its acceptance
of the benefits of this Agreement, except to the extent otherwise provided in
Section 7.06 of the Indenture, each Holder agrees that this Agreement may only
be enforced by the Trustee, and that no Holder shall have any right individually
to enforce or seek to enforce this Agreement or to realize upon the Collateral
or other security given to secure the payment and performance of the Secured
Obligations.

                        Affiliate Subordination Agreement

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                                       5

          IN WITNESS WHEREOF, the parties hereto have caused this Affiliate
Subordination Agreement to be duly executed in their respective capacities as
set forth below as of the date first written above.

                                   ISSUER

                                   GLOBAL CROSSING NORTH
                                      AMERICAN HOLDINGS, INC.


                                   By: /s/ John B. McShane
                                       -----------------------------------------
                                       Name: John B. McShane
                                       Title: Authorized Signatory


                                   GUARANTORS

                                   GLOBAL CROSSING LIMITED


                                   By: /s/ John B. McShane
                                       -----------------------------------------
                                       Name: John B. McShane
                                       Title: Exec. VP & General Counsel

                        Affiliate Subordination Agreement

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                                       6

US Guarantors:

                                   ALC COMMUNICATIONS CORPORATION
                                   BUDGET CALL LONG DISTANCE, INC.
                                   BUSINESS TELEMANAGEMENT, INC.
                                   GC DEV. CO., INC.
                                   GC PACIFIC LANDING CORP.
                                   GLOBAL CROSSING ADVANCED CARD SERVICES, INC.
                                   GLOBAL CROSSING BANDWIDTH, INC.
                                   GLOBAL CROSSING BILLING, INC.
                                   GLOBAL CROSSING DEVELOPMENT CO.
                                   GLOBAL CROSSING EMPLOYEE SERVICES INC.
                                   GLOBAL CROSSING GLOBALCENTER HOLDINGS, INC.
                                   GLOBAL CROSSING HOLDINGS USA, LLC
                                   GLOBAL CROSSING INTERNET DIAL-UP, INC.
                                   GLOBAL CROSSING LATIN AMERICA & CARIBBEAN CO.
                                   GLOBAL CROSSING LOCAL SERVICES, INC.
                                   GLOBAL CROSSING NORTH AMERICA, INC.
                                   GLOBAL CROSSING NORTH AMERICAN NETWORKS, INC.
                                   GLOBAL CROSSING TELECOMMUNICATIONS, INC.
                                   GLOBAL CROSSING TELEMANAGEMENT, INC.
                                   GLOBAL CROSSING USA INC.
                                   GT LANDING CORP.
                                   GT LANDING II CORP.
                                   INTERNATIONAL OPTICAL NETWORK, L.L.C.
                                   IXNET, INC.
                                   MAC LANDING CORP.
                                   PAC LANDING CORP.
                                   RACAL TELECOMMUNICATIONS INC.
                                   SUBSIDIARY TELCO, LLC
                                   US CROSSING, INC.


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Assistant Secretary

                        Affiliate Subordination Agreement

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                                       7

Bermudan Guarantors:

                                   ATLANTIC CROSSING HOLDINGS LTD.
                                   ATLANTIC CROSSING LTD.
                                   ATLANTIC CROSSING II LTD.
                                   GLOBAL CROSSING HOLDINGS
                                   GLOBAL CROSSING INTERNATIONAL, LTD.
                                   GLOBAL CROSSING NETWORK CENTER LTD.
                                   GLOBAL CROSSING PORTFOLIO HOLDINGS LTD.
                                   MID-ATLANTIC CROSSING HOLDINGS LTD.
                                   MID-ATLANTIC CROSSING LTD.
                                   PAC PANAMA LTD.
                                   PAN AMERICAN CROSSING HOLDINGS LTD.
                                   PAN AMERICAN CROSSING LTD.
                                   SOUTH AMERICAN CROSSING HOLDINGS LTD.
                                   SOUTH AMERICAN CROSSING LTD.


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Attorney-in-fact


Canadian Guarantors:

                                   AMERITEL MANAGEMENT, INC.
                                   GLOBAL CROSSING CONFERENCING-CANADA, LTD.
                                   GLOBAL CROSSING TELECOMMUNICATIONS-CANADA,
                                   LTD.
                                   GLOBAL CROSSING WORLDWIDE CUSTOMER HELP DESK
                                   CANADA LTD.


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Assistant Secretary

                        Affiliate Subordination Agreement

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                                       8

UK Guarantors:

                                   Executed as a deed by
                                   ATLANTIC CROSSING HOLDINGS U.K. LIMITED
                                   GC PAN EUROPEAN CROSSINGUK LTD.
                                   GEOCONFERENCE LIMITED
                                   GLOBAL CROSSING (BIDCO) LIMITED
                                   GLOBAL CROSSING CONFERENCING LIMITED
                                   GLOBAL CROSSING EUROPE LIMITED
                                   GLOBAL CROSSING IXNET EMEA HOLDINGS LIMITED
                                   GLOBAL CROSSING NETWORK CENTER (UK) LTD.
                                   GLOBAL CROSSING (UK) TELECOMMUNICATIONS
                                      LIMITED
                                   GT U.K. LTD.
                                   IXNET UK LIMITED
                                   MID-ATLANTIC CROSSING  HOLDINGS UK LTD.
                                   PAN AMERICAN CROSSING UK LTD.


                                   By /s/ Terrence L. Dugan
                                      ------------------------------------------
                                      Name: Terrence L. Dugan
                                      Title: Attorney-in-fact


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Attorney-in-fact


Irish Guarantors:

                                   SIGNED, SEALED and DELIVERED by


                                   GC HOLDING SPV
                                   GLOBAL CROSSING IRELAND LIMITED
                                   GLOBAL CROSSING SERVICES EUROPE LIMITED
                                   GLOBAL CROSSING SERVICES IRELAND LIMITED

                                   by its duly appointed attorney:


                                   By /s/ Terrence L. Dugan
                                      ------------------------------------------
                                      Name: Terrence L. Dugan


                                   Witnesseth: /s/ Lindsay Stieber
                                               ---------------------------------
                                               Name: Lindsay Stieber

                        Affiliate Subordination Agreement

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                                       10

European Guarantors:

                                   GC HUNGARY HOLDINGS VAGYONKEZELO
                                      KORLATOLT FELELOSSEGU TARSASAG
                                   GC LANDING CO. GMBH
                                   GC PAN EUROPEAN CROSSING BELGIE B.V.B.A.
                                   GC PAN EUROPEAN CROSSING DANMARK A.P.S.
                                   GC PAN EUROPEAN CROSSING DEUTSCHLAND GMBH
                                   GC PAN EUROPEAN CROSSING FRANCE S.A.R.L.
                                   GC PAN EUROPEAN CROSSING HOLDINGS B.V.
                                   GC PAN EUROPEAN CROSSING LUXEMBOURG I
                                   S.A.R.L.
                                   GC PAN EUROPEAN CROSSING LUXEMBOURG II
                                   S.A.R.L.
                                   GC PAN EUROPEAN CROSSING NEDERLAND B.V.
                                   GC PAN EUROPEAN CROSSING NETWORKS B.V.
                                   GC PAN EUROPEAN CROSSING NORGE AS
                                   GC PAN EUROPEAN CROSSING SVERIGE AB
                                   GC PAN EUROPEAN CROSSING SWITZERLAND GMBH
                                   GLOBAL CROSSING BELGIE B.V.B.A.
                                   GLOBAL CROSSING CYPRUS HOLDINGS LIMITED
                                   GLOBAL CROSSING DANMARK APS
                                   GLOBAL CROSSING DEUTSCHLAND GMBH
                                   GLOBAL CROSSING FRANCE SAS
                                   GLOBAL CROSSING NEDERLAND B.V.
                                   GLOBAL CROSSING NORGE AS
                                   GLOBAL CROSSING SVERIGE AB
                                   GLOBAL CROSSING SWITZERLAND GMBH
                                   GLOBAL CROSSING VENEZUELA B.V.
                                   GT NETHERLANDS B.V.
                                   INTERNATIONAL EXCHANGE NETWORKS SAS


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Attorney-in-fact


                                   GC PAN EUROPEAN CROSSING ITALIA S.R.L.
                                   GLOBAL CROSSING ITALIA S.R.L.


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: ATTORNEY-IN-FACT BY VIRTUE OF THE
                                             POWER OF ATTORNEY EXECUTED ON
                                             NOVEMBER 6 2003 BEFORE NOTARY

                        Affiliate Subordination Agreement

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                                       11

                                    MARIA CELESTE PAMPURI NOTARY PUBLIC IN MILAN

                        Affiliate Subordination Agreement

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                                       12

Global Marine Guarantors:

                                   GLOBAL MARINE CABLE SYSTEMS PTE LIMITED
                                   GLOBAL MARINE SYSTEMS (JAPAN) LIMITED
                                   VIBRO EINSPULTECHNIK DUKER-UND WASSERBAU GMBH


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Attorney-in-fact


                                   GLOBAL MARINE SYSTEMS (DEPOTS) LIMITED


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Authorized Signatory


                                   Executed as a deed by
                                   GLOBAL MARINE SYSTEMS LIMITED


                                   By /s/ Terrence L. Dugan
                                      ------------------------------------------
                                      Name: Terrence L. Dugan
                                      Title: Attorney-in-fact


                                   By /s/ David Sheffey
                                      ------------------------------------------
                                      Name: David Sheffey
                                      Title: Attorney-in-fact


Caribbean and Latin American Guarantors:

                                   GC ST. CROIX COMPANY, INC.
                                   GLOBAL CROSSING MEXICANA S. DE R.L. DE C.V.
                                   GLOBAL CROSSING PANAMA INC.
                                   GC SAC ARGENTINA S.R.L.
                                   SAC BRASIL HOLDING LTDA.
                                   SAC BRASIL LTDA.
                                   SAC CHILE S.A.
                                   SAC COLOMBIA LIMITADA
                                   SAC PANAMA S.A.
                                   SAC PERU S.R.L.


                                   By /s/ David Sheffey
                                      ------------------------------------------

                        Affiliate Subordination Agreement

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                                       13

                                      Name: David Sheffey
                                      Title: Attorney-in-fact

                        Affiliate Subordination Agreement

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                                       14

                                   TRUSTEE


                                   Acknowledged:
                                   WELLS FARGO BANK MINNESOTA, N.A.,
                                   not in its individual capacity but solely as
                                   Trustee under the Indenture on behalf of the
                                   Holders


                                   By: /s/ Jane Y. Schweiger
                                       -----------------------------------------
                                       Name: Jane Y. Schweiger
                                       Title: Vice President

                        Affiliate Subordination Agreement