Document:

<PAGE>   1
                                                                    EXHIBIT 10.1

                               SECOND AMENDMENT
                        TO LOAN AND SECURITY AGREEMENT

        SECOND AMENDMENT, dated as of June 21, 2001 (this "Amendment"), to the
Loan and Security Agreement, dated as of April 10, 2001, as amended by the First
Amendment, dated as of May 24, 2001 (as so amended, the "Loan Agreement"), by
and among, on the one hand, the lenders identified on Annex I hereto under the
caption "Continuing Lenders" (each a "Continuing Lender" and collectively, the
"Continuing Lenders") and the lenders identified on Annex I hereto under the
caption "Additional Lenders" (each an "Additional Lender" and collectively, the
"Additional Lenders," and together with the Continuing Lenders and their
respective successors and assigns, each a "Lender" and collectively, the
"Lenders"), FOOTHILL CAPITAL CORPORATION, a California corporation, as the
arranger and administrative agent for the Lenders (the "Agent"), ABLECO FINANCE
LLC, a New York limited liability company, as co-agent for the Lenders (the
"Co-Agent") and, on the other hand, e.spire COMMUNICATIONS, INC., a Delaware
corporation, as a debtor and a debtor in possession (the "Borrower"), and the
subsidiaries of Borrower that are identified on the signature pages of the Loan
Agreement, each as a debtor and a debtor in possession (each individually a
"Guarantor" and collectively the "Guarantors").

        WHEREAS, the Borrower, the Guarantors, the Agent, Co-Agent and the
Lenders are willing to amend the Loan Agreement to, among other things (i) add
the Additional Lenders as Lenders to the Loan Agreement and (ii) amend certain
other terms and conditions in the Loan Agreement.

        NOW THEREFORE, in consideration of the premises and other good and
valuable consideration, the parties hereto hereby agree as follows:

                1.1.    Definitions in this Amendment. Any capitalized term
used herein and not defined herein shall have the meaning assigned to it in the
Loan Agreement.

                1.2.    Existing Definitions. (a) The definition of the term
"Adequate Protection Stipulation" in Section 1.1 of the Loan Agreement is
hereby amended in its entirety to read as follows:

                "`Adequate Protection Stipulation' means the Final Order (I)
        Granting Adequate Protection, (II) Authorizing the Use of Cash
        Collateral, and (III) Granting on a Final Basis Post-Petition Financing
        pursuant to Bankruptcy Code Sections 105, 361, 362, 363 and 364 so
        ordered by the Bankruptcy Court, as in effect on Final Facility
        Effective Date, and as thereafter, amended, modified or extended from
        time to time with, in the case of any material amendments or
        modifications, the consent of the Agent on behalf of the Required
        Lenders."

<PAGE>   2

                (b)     The definition of the term "Maximum Revolver Amount" in
Section 1.1 of the Loan Agreement is hereby amended in its entirety to read as
follows:

                "`Maximum Revolver Amount' means (i) prior to the Final
        Facility Effective Date, $15,000,000 and (ii) on and after the Final
        Facility Effective Date, $60,000,000."

                1.3.    Schedule. Schedule C-1 to the Loan Agreement is hereby
amended in its entirety to read as set forth on Annex II attached hereto.

        2.      Additional Lenders. (a) On and as of the Final Facility
Effective Date, the Continuing Lenders and the Additional Lenders shall provide
additional Revolver Commitments to the Borrower, and each Continuing Lender
shall sell and assign and the Additional Lenders shall purchase and assume, at
the principal amount thereof, such interests in the Revolver Commitments, the
Advances and the Letter of Credit Usage outstanding on such date, in each case
as shall be necessary in order that, after giving effect to all such increases,
assignments and purchases, the Commitments will be as set forth in Annex II to
this Amendment, and the Commitments, Advances and Letter of Credit Usage will be
held by the Lenders ratably in accordance with their Pro Rata Shares in the
Commitments as set forth in Annex II to this Amendment. Such sales, assignments
and purchases shall be without recourse, representation or warranty, except that
(i) each Continuing Lender represents that it is the legal and beneficial owner
of the interests assigned by it free and clear of any adverse claim and (ii)
paragraphs 2, 3 and 5 of Exhibit A-1 to the Loan Agreement are hereby
incorporated by reference as if set forth herein and each Continuing Lender
shall be deemed to have made the representations, warranties and statements of
Assignor in such paragraphs and each Additional Lender shall be deemed to have
made the representations, warranties and statements of Assignee in such
paragraphs.

                (b)     On the Final Facility Effective Date, (i) the
Additional  Lenders shall pay the purchase price for the Advances purchased by
it pursuant to paragraph (a) of this Section 2 by wire transfer of immediately
available funds to the Agent, not later than 12:00 p.m. California time, and
(ii) the Agent shall promptly pay to each Continuing Lender the purchase price
for Advances sold by it pursuant to paragraph (a) of this Section 2, out of the
amounts received by it pursuant to clause (i) of this paragraph (b), by wire
transfer of immediately available funds to an account designated by such
Continuing Lender.

                (c)     Borrower and Guarantors hereby consent to the addition
of the Additional Lenders, to the increase in the Revolver Commitments and to
the sales, assignments and purchases provided for in paragraphs (a) and (b) of
this Section 2 and agree that the Continuing Lenders and the Additional Lenders
shall have all of the rights of a Lender under the Loan Agreement with respect
to the increase in the Commitments provided by it pursuant to such paragraphs
and the Additional Lenders shall have all of the rights of a Lender under the
Loan Documents with respect to the interests purchased by it pursuant to such
paragraphs. Commencing on the Final Facility Effective Date, the Additional
Lenders will be parties to the Loan Agreement, agree to be bound by the terms
and conditions of the Loan Agreement and the Loan Documents and will have all of
the rights and obligations of a Lender under the Loan Agreement and the Loan
Documents.

                                     - 2 -
<PAGE>   3

        3.      Conditions. The effectiveness of this Amendment is subject to
the fulfillment, in a manner satisfactory to the Agent, of each of the following
conditions precedent (the date such conditions are fulfilled or waived by the
Lenders as hereafter referred to as the "Amendment Effective Date"):

                (a)     Representations and Warranties; No Event of Default. The
representations and warranties contained herein, in Section 5 of the Loan
Agreement and in each other Loan Document and certificate or other writing
delivered to the Agent or any Lender pursuant hereto on or prior to the
Amendment Effective Date shall be correct on and as of the Amendment Effective
Date as though made on and as of such date, except to the extent that such
representations and warranties (or any schedules related thereto) expressly
relate solely to an earlier date (in which case such representations and
warranties shall be true and correct on and as of such date); and no Default or
Event of Default shall have occurred and be continuing on the Amendment
Effective Date or would result from this Amendment becoming effective in
accordance with its terms.

                (b)     Delivery of Documents. The Agent shall have received on
or before the Amendment Effective Date the following, each in form and substance
satisfactory to the Agent and, unless indicated otherwise, dated the Amendment
Effective Date:

                        (i)     a letter agreement between the Agent and each
        of the Additional Lenders, duly executed by each Additional Lender; and

                        (ii)    such other agreements, instruments and other
        documents as the Agent may reasonably request.

                (c)     Final Facility Effective Date. Each of the conditions
set forth in Section 3.3 of the Loan Agreement shall have been satisfied prior
to or simultaneously with this Amendment (which satisfaction may be as a result
of the effectiveness of this Amendment).

                (d)     Proceedings. All proceedings in connection with the
transactions contemplated by this Amendment, and all documents incidental
thereto, shall be satisfactory to the Agent and its counsel, and the Agent and
such counsel shall have received all such information and such counterpart
originals or certified copies of documents as the Agent or such counsel may
reasonably request.

        4.      Representations and Warranties. Each Loan Party hereby
represents and warrants to the Agent and the Lenders as follows:

                (a)     The representations and warranties herein, in Section 5
of the Loan Agreement and in each other Loan Document and certificate or other
writing delivered to the Agent or any Lender pursuant hereto on or prior to the
Amendment Effective Date are correct on and as of the Amendment Effective Date
as though made on and as of such date, except to the extent that such
representations and warranties (or any schedules related thereto) expressly
relate solely to an earlier date (in which case such representations and
warranties are true and correct on and as of such date); and no Default or Event
of Default has occurred and is continuing on the Effective Date or would result
from this Amendment becoming effective in accordance with its terms.

                                     - 3 -
<PAGE>   4

                (b)     Such Loan Party (i) is duly organized and existing and
in good standing under the laws of the jurisdiction of its organization, (ii)
has all requisite power and authority to execute, deliver and perform this
Amendment and to perform the Loan Agreement, as amended hereby, and (iii) is
duly qualified to do business in each jurisdiction in which the character of the
properties owned or leased by it or in which the transaction of its business
makes such qualification necessary except where the failure to be so qualified
could not be expected to have a Material Adverse Change.

                (c)     The execution, delivery and performance by such Loan
Party of this Amendment and the performance by such Loan Party of the Loan
Agreement, as amended by this Amendment, (i) have been duly authorized by all
necessary action, (ii) do not and will not contravene such Loan Party's charter
or by-laws or any applicable law.

                (d)     The execution, delivery, and performance by such Loan
Party of this Amendment and the performance of the Loan Agreement, as amended by
this Amendment, do not and will not require any registration with, consent, or
approval of, or notice to, or other action with or by, any Governmental
Authority or other Person, except for the approval of the Bankruptcy Court
pursuant to the Orders and except to the extent any such registration, consent,
approval, notice or other action is not required by reason of the Orders or the
Bankruptcy Code.

                (e)     Subject to the approval of the Bankruptcy Court
pursuant to the Orders, this Amendment and the Loan Agreement, as amended by
this Amendment, when executed and delivered by each Loan Party will be the
legally valid and binding obligations of each Loan Party, enforceable against
each Loan Party in accordance with their respective terms.

        5.      Miscellaneous.

                (a)     Continued Effectiveness of the Loan Agreement. Except
as otherwise expressly provided herein, the Loan Agreement and the other Loan
Documents are, and shall continue to be, in full force and effect and are hereby
ratified and confirmed in all respects, except that on and after the Amendment
Effective Date (i) all references in the Loan Agreement to "this Agreement",
"hereto", "hereof", "hereunder" or words of like import referring to the Loan
Agreement shall mean the Loan Agreement as amended by this Amendment, and (ii)
all references in the other Loan Documents to which any Loan Party is a party to
the "Loan Agreement", "thereto", "thereof", "thereunder" or words of like import
referring to the Loan Agreement shall mean the Loan Agreement as amended by this
Amendment. Except as expressly provided herein, the execution, delivery and
effectiveness of this Amendment shall not operate as an amendment of any right,
power or remedy of the Agent or the Lenders under the Loan Agreement or any
other Loan Document, nor constitute an amendment of any provision of the Loan
Agreement or any other Loan Document.

                (b)     Counterparts. This Amendment may be executed in any
number of counterparts and by different parties hereto in separate counterparts,
each of which shall be deemed to be an original, but all of which taken together
shall constitute one and the same agreement.

                                     - 4 -
<PAGE>   5

                (c)     Headings. Section headings herein are included for
convenience of reference only and shall not constitute a part of this Amendment
for any other purpose.

                (d)     Governing Law. This Amendment shall be governed by, and
construed in accordance with, the law of the State of New York except to the
extent governed by the Bankruptcy Code.

                (e)     Costs and Expenses. The Borrower agrees to pay on
demand  all fees, costs and expenses of each Agent in connection with the
preparation, execution and delivery of this Amendment and the other related
agreements, instruments and documents.

                (f)     Amendment as Loan Document. Each Loan Party hereby
acknowledges and agrees that this Amendment constitutes a "Loan Document" under
the Loan Agreement. Accordingly, it shall be an Event of Default under the Loan
Agreement if (i) any representation or warranty made by Loan Party under or in
connection with this Amendment shall have been untrue, false or misleading in
any material respect when made, or (ii) a Loan Party shall fail to perform or
observe any term, covenant or agreement contained in this Amendment.

                                     - 5 -
<PAGE>   6
                                   ANNEX I

Continuing Lenders:

Foothill Capital Corporation
Ableco Finance LLC
George Schmitt

Additional Lenders:

The CIT Group/Business Credit, Inc.

<PAGE>   7

               IN WITNESS WHEREOF, the parties hereto have caused this Amendment
to be executed and delivered as of the date first above written.

                    Borrower:
                    --------

                    e.spire COMMUNICATIONS, INC.,
                    a Delaware corporation

                    By /s/ CHRISTOPHER J. RESAVY
                       -------------------------------
                        Title:

                    Guarantors:
                    ----------

                    e.spire Finance Corporation,
                       a Delaware corporation
                    ACSI Network Technologies, Inc.,
                       a Maryland corporation
                    e.spireDATA, Inc.,
                       a Maryland corporation
                    ACSI Local Switched Services, Inc.,
                       a Maryland corporation
                    ACSI Long Distance, Inc.,
                       a Maryland corporation
                    e.spire Leasing Corporation,
                       a Maryland corporation
                    American Communication Services of Albuquerque, Inc.,
                       a Delaware corporation
                    American Communication Services of Amarillo, Inc.,
                       a Maryland corporation
                    American Communication Services of Atlanta, Inc.,
                       a Maryland corporation
                    American Communication Services of Austin, Inc.,
                       a Delaware corporation
                    American Communication Services of Baton Rouge, Inc.,
                       a Maryland corporation
                    American Communication Services of Birmingham, Inc.,
                       a Delaware corporation
                    American Communication Services of Charleston, Inc.,
                       a Delaware corporation
                    American Communication Services of Chattanooga, Inc.,
                       a Delaware corporation
                    American Communication Services of Colorado Springs, Inc.,
                       a Maryland corporation
                    American Communication Services of Columbia, Inc.,
                       a Delaware corporation

<PAGE>   8
                    American Communication Services of Columbus, Inc.,
                       a Maryland corporation
                    American Communication Services of Corpus Christi, Inc.,
                       a Maryland corporation Inc.
                    American Communication Services of Dallas, Inc.,
                       a Maryland corporation
                    American Communication Services of D.C., Inc.,
                       a Maryland corporation
                    American Communication Services of El Paso, Inc.,
                       a Delaware corporation
                    American Communication Services of Fort Worth, Inc.,
                       a Delaware corporation
                    American Communication Services of Greenville, Inc.,
                       a Delaware corporation
                    American Communication Services of Irving, Inc.,
                       a Maryland corporation
                    American Communication Services of Jackson, Inc.,
                       a Maryland corporation
                    American Communication Services of Jacksonville, Inc.,
                       a Maryland corporation
                    American Communication Services of Kansas City, Inc.,
                       a Maryland corporation
                    American Communication Services of Las Vegas, Inc.,
                       a Maryland corporation
                    American Communication Services of Lexington, Inc.,
                       a Delaware corporation
                    American Communication Services of Little Rock, Inc.,
                       a Delaware corporation
                    American Communication Services of Louisiana, Inc.,
                       a Delaware corporation
                    American Communication Services of Louisville, Inc.,
                       a Delaware corporation
                    American Communication Services of Maryland, Inc.,
                       a Maryland corporation
                    American Communication Services of Miami, Inc.,
                       a Maryland corporation
                    American Communication Services of Mobile, Inc.,
                       a Delaware corporation
                    American Communication Services of Montgomery, Inc.,
                       a Maryland corporation
                    American Communication Services of Pima County, Inc.,
                       a Delaware corporation
                    American Communication Services of Rio Rancho, Inc.,
                       a Maryland corporation
                    American Communication Services of Roanoke, Inc.,
                       a Maryland corporation

<PAGE>   9
                    American Communication Services of San Antonio, Inc.,
                       a Delaware corporation
                    American Communication Services of Savannah, Inc.,
                       a Maryland corporation
                    American Communication Services of Shreveport, Inc.,
                       a Maryland corporation
                    American Communication Services of Spartanburg, Inc.,
                       a Maryland corporation
                    American Communication Services of Tampa, Inc.,
                       a Maryland corporation
                    American Communication Services of Tulsa, Inc.,
                       a Maryland corporation
                    American Communication Services of Virginia, Inc.,
                       a Virginia corporation
                    American Communication Services International, Inc.,
                       a Delaware corporation
                    ACSI Local Switched Services of Virginia, Inc.,
                       a Virginia corporation
                    Cybergate, Inc.,
                       a Florida corporation
                    FloridaNet, Inc.,
                       a Florida corporation

                    Each by: /s/CHRISTOPHER J. RESAVY
                            ----------------------------------------
                             Title:

<PAGE>   10

                         Agents and Continuing Lenders:
                         -----------------------------

                         FOOTHILL CAPITAL CORPORATION

                         By   /s/
                           ------------------------------------------
                            Title: Vice President

                         ABLECO FINANCE LLC

                         By  /s/ KEVIN GARCIA
                           ------------------------------------------
                            Title: Senior Vice President

                         Continuing Lenders:
                         ------------------

                         /s/ GEORGE SCHMITT
                         --------------------------------------------
                         GEORGE SCHMITT

                         Additional Lenders:
                         ------------------

                         THE CIT GROUP/BUSINESS CREDIT, INC.

                         By  /s/ JAMES A. BRENNAN, JR.
                           ------------------------------------------
                            Title: Vice President<PAGE>   1

                                                                   EXHIBIT 10.10

                                 EXECUTION COPY

                                U.S. $30,000,000

                              MASTER LOAN AGREEMENT

                            Dated as of June 6, 2001

                                      among

                               HARRIS CANADA, INC.

                                  as the Lender

                                     Each of

                                   IMPSAT S.A.
                                   (Argentina)

                            IMPSAT Comunicacoes Ltda.
                                    (Brazil)

                                   IMPSAT S.A.
                                   (Colombia)

                            IMPSATEL Del Ecuador S.A.
                                    (Ecuador)

                         Telecomunicaciones IMPSAT, S.A.
                                   (Venezuela)

                                 as Co-Borrowers

                                       and

                           IMPSAT FIBER NETWORKS, INC.

                                as the Guarantor

 =============================================================================

                              HOLLAND & KNIGHT LLP
                             2099 Pennsylvania, N.W.
                              Washington, DC 20006

                                       and

                               701 Brickell Avenue
                                 Miami, FL 33131

MIA1 #1016002.v8                                           MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   2

                                 EXECUTION COPY

                              MASTER LOAN AGREEMENT

                                TABLE OF CONTENTS
<TABLE>
<CAPTION>

                                                                                                                 Page
                                                                                                                 ----
<S>                                                                                                             <C>
ARTICLE I DEFINITIONS AND PRINCIPLES OF CONSTRUCTION..............................................................2
   Section 1.01         Definitions...............................................................................2
                        -----------
   Section 1.02         Principles of Construction...............................................................24
                        --------------------------
ARTICLE II COMMITMENTS; CREDIT OF ADVANCE........................................................................24
   Section 2.01         Commitment to Lend.......................................................................24
                        ------------------
   Section 2.02         Notice of Intention and Commitment to Borrow.............................................24
                        --------------------------------------------
   Section 2.03         Making of Advances; Credit of Advance Amount.............................................25
                        --------------------------------------------
   Section 2.04         Commitments Not Revolving................................................................26
                        -------------------------
   Section 2.05         Intentionally Left Blank.................................................................26
   Section 2.06         Loan Account.............................................................................26
                        ------------
   Section 2.07         Acknowledgment of Advances...............................................................26
                        --------------------------
   Section 2.08         Brazil Notice of Borrowing...............................................................27
                        --------------------------
ARTICLE III REPAYMENT............................................................................................28
   Section 3.01         Repayment................................................................................28
                        ---------
   Section 3.02         Optional Prepayment......................................................................28
                        -------------------
   Section 3.03         Intentionally Left Blank.................................................................28
                        ------------------------
   Section 3.04         Changes in Market and Exchange Control...................................................28
                        --------------------------------------
   Section 3.05         Application of Payments..................................................................30
                        -----------------------
   Section 3.06         Place and Manner of Payment..............................................................30
                        ---------------------------
ARTICLE IV INTEREST; EXPENSES....................................................................................31
   Section 4.01         Base Rate and Brazil Rate................................................................31
                        -------------------------
   Section 4.02         Interest on Amounts in Default...........................................................31
                        ------------------------------
   Section 4.03         Fees and Initial Expenses................................................................32
                        -------------------------
   Section 4.04         Enforcement Expenses.....................................................................32
                        --------------------
ARTICLE V TAXES..................................................................................................32
   Section 5.01         Taxes....................................................................................32
                        -----
   Section 5.02         Receipt of Payment.......................................................................33
                        ------------------
   Section 5.03         Other Taxes..............................................................................33
                        -----------
   Section 5.04         Indemnification..........................................................................33
                        ---------------
ARTICLE VI THE NOTES.............................................................................................33
   Section 6.01         Grid Notes...............................................................................33
                        ----------
   Section 6.02         Definitive Notes.........................................................................34
                        ----------------
   Section 6.03         Note Exchanges...........................................................................34
                        --------------
   Section 6.04         Replacement Notes........................................................................34
                        -----------------
   Section 6.05         Notes Under Alternative Financing for IMPSAT Comunicacoes Ltda.(Brazil)..................34
                        -----------------------------------------------------------------------
</TABLE>

MIA1 #1016002.v8                      i                    MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   3

                                EXECUTION COPY

<TABLE>
<S>                                                                                                            <C>
ARTICLE VII CONDITIONS PRECEDENT.................................................................................34
   Section 7.01         Conditions Precedent to the Closing Advance..............................................34
                        -------------------------------------------
   Section 7.02         Conditions Precedent to the First Advance................................................36
                        -----------------------------------------
   Section 7.03         Conditions Precedent to the Second Advance...............................................38
                        ------------------------------------------
   Section 7.04         Conditions Precedent to Each Advance.....................................................40
                        ------------------------------------
   Section 7.05         Waiver of Condition Precedent............................................................41
                        -----------------------------
ARTICLE VIII COLLATERAL..........................................................................................41
   Section 8.01         Security Documents.......................................................................41
                        ------------------
   Section 8.02         Further Documents........................................................................41
                        -----------------
ARTICLE IX REPRESENTATIONS AND WARRANTIES........................................................................41
   Section 9.01         Representations and Warranties of each Co-Borrower.......................................41
                        --------------------------------------------------
   Section 9.02         Representations and Warranties of the Guarantor..........................................48
                        -----------------------------------------------
ARTICLE X AFFIRMATIVE COVENANTS..................................................................................51
   Section 10.01        Good and Marketable Title................................................................51
                        -------------------------
   Section 10.02        Financial Statements and Information.....................................................51
                        ------------------------------------
   Section 10.03        Books and Records........................................................................52
                        -----------------
   Section 10.04        Inspection Rights; Access................................................................52
                        -------------------------
   Section 10.05        Governmental Authorizations..............................................................53
                        ---------------------------
   Section 10.06        Conduct of Business and Maintenance of Existence.........................................53
                        ------------------------------------------------
   Section 10.07        Compliance with Laws.....................................................................53
                        --------------------
   Section 10.08        Notices..................................................................................53
                        -------
   Section 10.09        Prompt Payment...........................................................................54
                        --------------
   Section 10.10        Notice of Certain Amendments or Waivers..................................................54
                        ---------------------------------------
   Section 10.11        Insurance................................................................................55
                        ---------
   Section 10.12        Security Documents.......................................................................55
                        ------------------
   Section 10.13        Further Assurances.......................................................................56
                        ------------------
   Section 10.14        Maintenance of Properties, Etc...........................................................57
                        ------------------------------
   Section 10.15        Status of Obligations....................................................................57
                        ---------------------
   Section 10.16        Maintenance of Corporate Separateness....................................................57
                        -------------------------------------
   Section 10.17        License Marks............................................................................58
                        -------------
   Section 10.18        Shareholder Authority....................................................................58
                        ---------------------
   Section 10.19        Supply Contract..........................................................................58
                        ---------------
ARTICLE XI NEGATIVE COVENANTS....................................................................................58
   Section 11.01        Merger; Change of Control; Sale of Assets................................................58
                        -----------------------------------------
   Section 11.02        Liens....................................................................................58
                        -----
   Section 11.03        Amendment and Waiver.....................................................................59
                        --------------------
   Section 11.04        Business Restriction.....................................................................59
                        --------------------
   Section 11.05        Restricted Payments......................................................................59
                        -------------------
   Section 11.06        Investments in Subsidiaries..............................................................59
                        ---------------------------
   Section 11.07        Financial Covenants......................................................................60
                        -------------------
</TABLE>

MIA1 #1016002.v8                     ii                   MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   4

                                EXECUTION COPY

<TABLE>
<S>                                                                                                            <C>
   Section 11.08        Prepayment of Indebtedness...............................................................61
                        --------------------------
   Section 11.09        Accounting Methods.......................................................................61
                        ------------------
   Section 11.10        Additional Indebtedness..................................................................62
                        -----------------------
   Section 11.11        Conduct of Business with Affiliates......................................................62
                        -----------------------------------
   Section 11.12        Capital Expenditures.....................................................................62
                        --------------------
   Section 11.13        Accounts Receivable......................................................................62
                        -------------------
   Section 11.14        Intentionally omitted....................................................................63
                        ----------------------
   Section 11.15        Limitation on Contingent Obligations.....................................................63
                        ------------------------------------
ARTICLE XII THE GUARANTY.........................................................................................63
   Section 12.01        The Guaranty.............................................................................63
                        ------------
   Section 12.02        Examination and Delivery of the Guaranty Agreement.......................................63
                        --------------------------------------------------
ARTICLE XIII EVENTS OF DEFAULT; REMEDIES; SUSPENSION.............................................................63
   Section 13.01        Events of Default........................................................................63
                        -----------------
   Section 13.02        Default Remedies.........................................................................65
                        ----------------
   Section 13.03        Right of Set-off.........................................................................66
                        ----------------
   Section 13.04        Benefit of Agreement; Rights Not Exclusive...............................................66
                        ------------------------------------------
   Section 13.05        Suspension of Available Credit...........................................................66
                        ------------------------------
ARTICLE XIV INCREASED COSTS......................................................................................67
   Section 14.01        Funding Losses...........................................................................67
                        --------------
   Section 14.02        Increased Costs..........................................................................67
                        ---------------
ARTICLE XV MISCELLANEOUS.........................................................................................68
   Section 15.01        Assignments; Participations..............................................................68
                        ---------------------------
   Section 15.02        Successors and Assigns; Remedies Cumulative..............................................68
                        -------------------------------------------
   Section 15.03        Notices..................................................................................68
                        -------
   Section 15.04        Entire Agreement.........................................................................71
                        ----------------
   Section 15.05        Conflicts................................................................................71
                        ---------
   Section 15.06        Modification.............................................................................71
                        ------------
   Section 15.07        Judgment Currency........................................................................71
                        -----------------
   Section 15.08        Severability.............................................................................72
                        ------------
   Section 15.09        Further Assurances.......................................................................72
                        ------------------
   Section 15.10        Governing Law............................................................................72
                        -------------
   Section 15.11        Jurisdiction.............................................................................72
                        ------------
   Section 15.12        Appointment of Agent.....................................................................72
                        --------------------
   Section 15.13        Waiver of Jury Trial.....................................................................73
                        --------------------
   Section 15.14        Waiver of Immunity.......................................................................73
                        ------------------
   Section 15.15        Indemnification..........................................................................73
                        ---------------
   Section 15.16        Counterparts.............................................................................74
                        ------------
   Section 15.17        Limitation on Rights of Others...........................................................74
                        ------------------------------
</TABLE>

MIA1 #1016002.v8                     iii                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   5

                                EXECUTION COPY

<TABLE>
<S>                     <C>                                                                                     <C>
   Section 15.18        No Partnership...........................................................................74
                        --------------
   Section 15.19        Consequential Damages....................................................................74
                        ---------------------
   Section 15.20        Independent Counsel......................................................................74
                        -------------------
   Section 15.21        Alternative Financing for IMPSAT Comunicacoes Ltda.(Brazil)..............................74
                        -----------------------------------------------------------
   Section 15.22        Section Headings; Table of Contents......................................................74
                        -----------------------------------
   Section 15.23        Time is of the Essence...................................................................74
                        ----------------------
   Section 15.24        Confidentiality..........................................................................74
                        ---------------
</TABLE>

MIA1 #1016002.v8                       iv                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   6

                                EXECUTION COPY

<TABLE>
<S>              <C>
EXHIBIT A-1       FORM OF GRID NOTE OF IMPSAT S.A. (ARGENTINA)
EXHIBIT A-2       FORM OF GRID NOTE OF IMPSAT COMUNICACOES LTDA.
                           (BRAZIL)
EXHIBIT A-3       FORM OF GRID NOTE OF IMPSAT S.A. (COLOMBIA)
EXHIBIT A-4       FORM OF GRID NOTE OF IMPSATEL DEL ECUADOR S.A.
                           (ECUADOR)
EXHIBIT A-5       FORM OF GRID NOTE OF TELECOMUNICACIONES IMPSAT, S.A.
                           (VENEZUELA)
EXHIBIT B-1                FORM OF DEFINITIVE NOTE OF IMPSAT S.A. (ARGENTINA)
EXHIBIT B-2       FORM OF DEFINITIVE NOTE OF IMPSAT COMUNICACOES
                           LTDA.    (BRAZIL)
EXHIBIT B-3                FORM OF DEFINITIVE NOTE OF IMPSAT S.A. (COLOMBIA)
EXHIBIT B-4                FORM OF DEFINITIVE NOTE OF IMPSATEL DEL ECUADOR S.A.
                           (ECUADOR)
EXHIBIT B-5                FORM OF DEFINITIVE NOTE OF TELECOMUNICACIONES IMPSAT
                           S.A. (VENEZUELA)
EXHIBIT C                  FORM OF THE GUARANTY AGREEMENT
EXHIBIT D-1       FORM OF CO-BORROWER CERTIFICATE
                           OF IMPSAT S.A. (ARGENTINA)
EXHIBIT D-2       FORM OF CO-BORROWER CERTIFICATE
                           OF IMPSAT COMUNICACOES LTDA. (BRAZIL)
EXHIBIT D-3       FORM OF CO-BORROWER CERTIFICATE
                           OF IMPSAT S.A. (COLOMBIA)
EXHIBIT D-4       FORM OF CO-BORROWER CERTIFICATE
                           OF IMPSATEL DEL ECUADOR S.A. (ECUADOR)
EXHIBIT D-5       FORM OF CO-BORROWER CERTIFICATE
                           OF TELECOMUNICACIONES IMPSAT, S.A. (VENEZUELA)
EXHIBIT E                  FORM OF THE GUARANTOR'S CERTIFICATE
EXHIBIT F-1       FORM OF OPINION OF CO-BORROWER'S COUNSEL
                           OF IMPSAT S.A. (ARGENTINA)
EXHIBIT F-2       FORM OF OPINION OF CO-BORROWER'S COUNSEL
                           OF IMPSAT COMUNICACOES LTDA. (BRAZIL)
EXHIBIT F-3       FORM OF OPINION OF CO-BORROWER'S COUNSEL
                           OF IMPSAT S.A. (COLOMBIA)
EXHIBIT F-4       FORM OF OPINION OF CO-BORROWER'S COUNSEL
                           OF IMPSATEL DEL ECUADOR S.A. (ECUADOR)
EXHIBIT F-5       FORM OF OPINION OF CO-BORROWER'S COUNSEL
                           OF TELECOMUNICACIONES IMPSAT, S.A. (VENEZUELA)
EXHIBIT G                  FORM OF OPINION OF NEW YORK COUNSEL TO THE GUARANTOR
                  AND EACH CO-BORROWER
EXHIBIT H                  BASE CASE BUSINESS PLAN OF EACH CO-BORROWER
                  AND THE GUARANTOR
</TABLE>

MIA1 #1016002.v8                       v                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   7

                                EXECUTION COPY

<TABLE>
<S>               <C>
EXHIBIT I                  BRAZIL NOTICE OF BORROWING
EXHIBIT J                  EXISTING INDEBTEDNESS
EXHIBIT K-1       EXISTING LIENS OF IMPSAT S.A. (ARGENTINA)
EXHIBIT K-2       EXISTING LIENS OF IMPSAT COMUNICACOES LTDA.
                           (BRAZIL)
EXHIBIT K-3       EXISTING LIENS OF IMPSAT S.A. (COLOMBIA)
EXHIBIT K-4       EXISTING LIENS OF IMPSATEL DEL ECUADOR S.A.
                           (ECUADOR)
EXHIBIT K-5       EXISTING LIENS OF TELECOMUNICACIONES IMPSAT, S.A.
                           (VENEZUELA)
EXHIBIT L                  FORM OF INDEMNITY FOR REPLACEMENT NOTE
EXHIBIT M-1                CAPITALIZATION OF IMPSAT S.A. (ARGENTINA) AND IT SUBSIDIARIES
EXHIBIT M-2                CAPITALIZATION OF IMPSAT COMUNICACOES LTDA. (BRAZIL) AND ITS SUBSIDIARIES
EXHIBIT M-3                CAPITALIZATION OF IMPSAT S.A. (COLOMBIA) AND ITS SUBSIDIARIES
EXHIBIT M-4                CAPITALIZATION OF IMPSATEL DEL ECUADOR S.A. (ECUADOR) AND ITS SUBSIDIARIES
EXHIBIT M-5                CAPITALIZATION OF TELECOMUNICACIONES IMPSAT, S.A. (VENEZUELA) AND ITS SUBSIDIARIES
</TABLE>

MIA1 #1016002.v8                       vi                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   8

                                 EXECUTION COPY

                              MASTER LOAN AGREEMENT

         This MASTER LOAN AGREEMENT ("Agreement") is dated as of June 6, 2001,
by and among Harris Canada Inc., a corporation organized under the laws of
Canada (the "Lender"), each of IMPSAT S.A., a sociedad anonima organized under
the laws of Argentina ("IMPSAT S.A. (Argentina)"), IMPSAT Comunicacoes Ltda., a
sociedade por quotas de responsabilidade limitada organized under the laws of
Brazil ("IMPSAT Comunicacoes Ltda.(Brazil)"), IMPSAT S.A., a sociedad anonima
organized under the laws of Colombia ("IMPSAT S.A. (Colombia)"), IMPSATEL Del
Ecuador S.A., a sociedad anonima organized under the laws of Ecuador ("IMPSATEL
Del Ecuador S.A. (Ecuador)"), and Telecomunicaciones IMPSAT, S.A., a sociedad
anonima organized under the laws of Venezuela ("Telecomunicaciones IMPSAT, S.A.
(Venezuela)") (individually, a "Co-Borrower", and collectively, "Co-Borrowers"),
and IMPSAT Fiber Networks, Inc., a corporation organized under the laws of the
State of Delaware ("Guarantor" or "IFN"), for the purchase of Goods and Services
(as defined herein) by each Co-Borrower and relating to certain payment
obligations of each of the Co-Borrowers under the Supply Contract(s) (as defined
herein). The Lender, the Co-Borrowers and the Guarantor, and each of their
successors and assigns, are hereinafter referred to collectively as the
"Parties" or individually as a "Party".

                              W I T N E S S E T H:

         WHEREAS, the Co-Borrowers propose to borrow from the Lender, and the
Lender proposes to lend to the Co-Borrowers, severally and ratably, an aggregate
principal amount of up to $30,000,000 to finance the purchase of certain
microwave transmission equipment and related services, including freight,
insurance and other related services and costs connected with the importation
and clearance through customs of such equipment ("Goods and Services") from
Harris Corporation, and certain of its Affiliates ("Harris") pursuant to the
terms of the Supply Contract(s) to be entered into by and among Harris and the
Co-Borrowers ("Supply Contract(s)") and under additional purchase orders
approved by Harris;

         WHEREAS, in order to induce the Lender to enter into this Agreement and
to extend credit hereunder, the Guarantor has agreed to guarantee payment of the
Obligations (as defined herein) of each Co-Borrower;

         WHEREAS, in order to further secure all amounts due and payable by the
Co-Borrowers, each Co-Borrower agrees to execute and deliver to the Lender such
pledges and other security documents as required by the Lender hereunder
("Security Documents"); and

MIA1 #1016002.v8                       1                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   9

                                EXECUTION COPY

         WHEREAS, in the case of IMPSAT Comunicacoes Ltda. (Brazil), the Lender
is prepared to consider financing the transactions contemplated herein for such
Co-Borrower by, through, or in association with a Brazilian bank or other
Brazilian financial institution;

         NOW, THEREFORE, in consideration of the mutual promises of the Parties,
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, it is mutually agreed by and among the Parties as
follows:

                                    ARTICLE I
                                 DEFINITIONS AND
                           PRINCIPLES OF CONSTRUCTION

         Section 1.01 Definitions.  As used herein:

         "Acknowledgment of Advances" has the meaning specified in Section 2.07.

         "Additions to Deferred Revenues" means, with respect to a Co-Borrower
and as of the date of determination thereof, the additions to Deferred Revenues
during the four (4) consecutive calendar quarters ending on the last day of the
period prior to such date of determination.

         "Adjusted EBITDA" means, with respect to a Co-Borrower and as of the
date of determination thereof, the sum of such Co-Borrower's (a) Annualized
EBITDA, plus (b) Additions to Deferred Revenues, minus (c) Revenue Recognition
from IRUs.

         "Administrative Fee" means three percent (3.00%), flat, of the
Commitment.

         "Advance" has the meaning specified in Section 2.01.

         "Advance Amount" has the meaning specified in Section 2.02.

         "Affiliate" with respect to any Person, means any Person directly or
indirectly controlling, controlled by or under common control with, such Person.
For the purposes of this definition, "control" (including, with correlative
meaning, the terms "controlling" and "controlled") shall mean the possession,
directly or indirectly, of the power to direct or cause the direction of the
management and policies of such Person, whether through the ownership of voting
securities, by contract or otherwise.

         "Agreement" means this Master Loan Agreement.

         "Amendment" has the meaning specified in Section 11.03.

         "Annualized EBITDA" means, with respect to a Co-Borrower and as of the
date of determination thereof, (a) after December 31, 2001, the Co-Borrower's
EBITDA for any

MIA1 #1016002.v8                       2                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   10

                                EXECUTION COPY

period of four (4) consecutive calendar quarters, and (b) to an including
December 31, 2001, the Co-Borrower's EBITDA for any period of two (2)
consecutive calendar quarters multiplied by two (2).

          "Applicable Law" means any statute, law, regulation, ordinance, rule,
judgment, writ, rule of common law, common law duty, code, order, decree,
Governmental Approval, administrative order, directed duty, request, license,
authorization, permit, approval, concession, grant, franchise, directive,
guideline, policy, requirement, or other governmental restriction, or any
similar form of decision of, determination by, agreement with, or requirements
of (or any interpretation or administration of any of the foregoing by) any
Governmental Authority, whether in effect as of the date hereof or thereafter.

         "Argentina" means the Republic of Argentina.

         "Argentina Permitted Indebtedness" means, with respect to IMPSAT S.A.
(Argentina), (a) Indebtedness pursuant to the Credit Documentation; (b)
Indebtedness of IMPSAT S.A. (Argentina) to IFN or to any Subsidiary of IMPSAT
S.A. (Argentina) or of any such Subsidiary to IMPSAT S.A. (Argentina), in each
case for money borrowed; (c) Indebtedness of IMPSAT S.A. (Argentina) for money
borrowed from financial institutions which Indebtedness is either fully
collateralized by cash deposits of IFN or fully funded by IFN through the
acquisition of one hundred percent (100%) participation in such Indebtedness
from such financial institution; (d) guarantees by IMPSAT S.A. (Argentina) of
obligations of any of its Subsidiaries or guarantees by any such Subsidiary of
obligations of IMPSAT S.A. (Argentina); (e) contingent Indebtedness in respect
of bonds or letters of credit provided to guarantee bids or performance under
contracts in the ordinary course of business; (f) Indebtedness of IMPSAT S.A.
(Argentina) which is in existence on the date hereof and set forth on Exhibit J;
(g) Quasi Equity; (h) Indebtedness for money borrowed for working capital
purposes having an original stated final maturity of three (3) years or less up
to a maximum aggregate amount at any time outstanding not to exceed Thirty
Million Dollars (US$30,000,000); (i) Indebtedness incurred in connection with
the financing of Capital Expenditures permitted under Section 11.12, (j)
Indebtedness for money borrowed having a stated final maturity not earlier than
the first anniversary of the Final Maturity Date; and (k) Indebtedness incurred
and applied to refinance Indebtedness permitted by each of clauses (a), (b),
(c), (f), (g), (h) and (i) above; provided, with respect to any such refinancing
Indebtedness, that (i) the principal amount of such refinancing Indebtedness
does not exceed the principal amount of the Indebtedness so refinanced; (ii)
such refinancing Indebtedness has a final maturity date equal to or later than
the final maturity date of, and has an average life to maturity equal to or
greater than the average life to maturity of, the Indebtedness being refinanced;
and (iii) such Indebtedness is incurred and/or guaranteed by IMPSAT S.A.
(Argentina) and any Subsidiary which had incurred or guaranteed, as the case may
be, the Indebtedness to be refinanced.

MIA1 #1016002.v8                       3                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   11

                                EXECUTION COPY

         "Availability Period" means the period beginning on the Initial
Borrowing Date and ending on the earlier of (i) the 365th day after the Initial
Borrowing Date, (ii) March 31, 2002, or (iii) on the earlier termination of this
Agreement.

         "Bank" means Bank of America, N.A.

         "Banking Day" means any day on which commercial banks are open for
international business (including dealing in Dollar deposits) in London, except
(i) with respect to any party, a Saturday, Sunday or other day on which
commercial banks in Montreal, Canada or New York, New York are required or
authorized by law to close and (ii) with respect to IMPSAT S.A. (Argentina), any
day on which commercial banks in Buenos Aires, Argentina are required or
authorized by law to close, and (iii) with respect to IMPSAT Comunicacoes Ltda.
(Brazil), any day on which commercial banks in Sao Paulo, Brazil are required or
authorized by law to close, and (iv) with respect to IMPSAT S.A. (Colombia) any
day on which commercial banks in Bogota D.C., Colombia are required or
authorized by law to close, and (v) with respect to IMPSATEL Del Ecuador S.A.
(Ecuador) any day on which commercial banks in Quito, Ecuador are required or
authorized by law to close, and (vi) with respect to Telecomunicaciones IMPSAT,
S.A. (Venezuela), any day on which commercial banks in Caracas, Venezuela are
required or authorized by law to close.

         "Base Rate" means, for any Interest Period, the applicable LIBOR plus
1.50% and applied to all Advances made under this Agreement to each Co-Borrower
other than IMPSAT Comunicacoes Ltda. (Brazil).

         "Board of Directors" means, with respect to any Person, the Board of
Directors of such Person or any committee of such Board of Directors duly
authorized to act with respect to this Agreement.

         "Borrowing Date" has the meaning specified in Section 2.02.

         "Brazil" means the Federative Republic of Brazil.

         "Brazil Notice of Borrowing" has the meaning specified in Section 2.08.

         "Brazil Permitted Indebtedness" means, with respect to IMPSAT
Comunicacoes Ltda. (Brazil), (a) Indebtedness pursuant to the Credit
Documentation; (b) Indebtedness of IMPSAT Comunicacoes Ltda. (Brazil) to IFN or
to any Subsidiary of IMPSAT Comunicacoes Ltda.(Brazil) or of any such Subsidiary
to IMPSAT Comunicacoes Ltda.(Brazil), in each case for money borrowed; (c)
Indebtedness of IMPSAT Comunicacoes Ltda. (Brazil) for money borrowed from
financial institutions which Indebtedness is either fully collateralized by cash
deposits of IFN or fully funded by IFN through the acquisition of one hundred
percent (100%) participation in such Indebtedness from such financial
institution; (d) guarantees by IMPSAT Comunicacoes Ltda.(Brazil) of obligations
of any of its Subsidiaries or guarantees by any such

MIA1 #1016002.v8                       4                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   12

                                EXECUTION COPY

Subsidiary of obligations of IMPSAT Comunicacoes Ltda. (Brazil); (e) contingent
Indebtedness in respect of bonds or letters of credit provided to guarantee bids
or performance under contracts in the ordinary course of business; (f)
Indebtedness of IMPSAT Comunicacoes Ltda. (Brazil) which is in existence on the
date hereof and set forth on Exhibit J; (g) Quasi Equity; (h) Indebtedness for
money borrowed for working capital purposes having an original stated final
maturity of three (3) years or less up to a maximum aggregate amount at any time
outstanding not to exceed Forty Million Dollars (US$40,000,000); (i)
Indebtedness incurred in connection with the financing of Capital Expenditures
permitted under Section 11.12, (j) Indebtedness for money borrowed having a
stated final maturity not earlier than the first anniversary of the Final
Maturity Date; and (k) Indebtedness incurred and applied to refinance
Indebtedness permitted by each of clauses (a), (b), (c), (f), (g), (h) and (i)
above; provided, with respect to any such refinancing Indebtedness, that (i) the
principal amount of such refinancing Indebtedness does not exceed the principal
amount of the Indebtedness so refinanced; (ii) such refinancing Indebtedness has
a final maturity date equal to or later than the final maturity date of, and has
an average life to maturity equal to or greater than the average life to
maturity of, the Indebtedness being refinanced; and (iii) such Indebtedness is
incurred and/or guaranteed by IMPSAT Comunicacoes Ltda. (Brazil) and any
Subsidiary which had incurred or guaranteed, as the case may be, the
Indebtedness to be refinanced.

         "Brazil Rate" means, for each Interest Period, eleven percent (11%) per
annum and applied to all Advances made under the Agreement to IMPSAT
Comunicacoes Ltda. (Brazil).

         "Business Plan" means a business plan attached hereto as Exhibit H.

         "Capital Expenditures" shall mean, for any period, the additions to
property, plant and equipment and other capital expenditures of a Co-Borrower
and its consolidated Subsidiaries that are (or would be) set forth in a
consolidated statement of cash flows of the Co-Borrower for such period prepared
in accordance with GAAP.

         "Capital Stock" of any Person means any and all shares, interests,
rights to purchase, warrants, options, participations or other equivalents of or
interests in equity (however designated and whether or not convertible into a
class or classes thereof) of such Person.

         "Change of Control" means (a) IFN ceasing to own, directly or
indirectly, shares representing at least 50% of the issued and outstanding
Voting Stock of any of the Co-Borrowers, (b) such time as a "person" or "group"
(within the meaning of Sections 13(d) and 14(d)(2) of the Exchange Act) becomes
the ultimate "beneficial owner" (as defined in Rule 13d-3 under the Exchange
Act) of Voting Stock representing more than 30% of the total voting power of the
Voting Stock of the Guarantor on a fully diluted basis and such ownership
represents a greater percentage of the total voting power of the Voting Stock of
the Guarantor, on a fully diluted basis, than is held by the Existing
Stockholders; or (c) such time as individuals who on the Closing Date constitute
the Board of Directors of the Guarantor,

MIA1 #1016002.v8                       5                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   13

                                EXECUTION COPY

IMPSAT S.A. (Argentina), or IMPSAT Comunicacoes Ltda. (Brazil), respectively,
was approved by a vote of at least two-thirds of the members of such Board of
Directors then in office who either were members of such Board of Directors on
the Closing Date or whose election or nomination for election was previously so
approved) cease for any reason to constitute a majority of the members of such
Board of Directors then in office.

         "Closing Advance" has the meaning specified in Section 7.01.

         "Closing Advance Amount" shall mean US$4,500,000.

         "Closing Date" has the same meaning as Initial Borrowing Date.

         "Co-Borrowers" has the meaning, collectively, specified in the
Preamble, and individually, either IMPSAT S.A. (Argentina), IMPSAT Comunicacoes
Ltda. (Brazil), IMPSAT S.A., (Colombia), IMPSATEL Del Ecuador S.A. (Ecuador), or
Telecomunicaciones IMPSAT, S.A. (Venezuela), as the context may require in this
Agreement.

         "Collateral" means, with respect to a Co-Borrower, the Goods and
Services purchased under the Supply Contract(s) by such Co-Borrower and financed
hereunder and which also constitute equipment listed or described as collateral
in an annex attached to a Security Document relating to each Co-Borrower
securing the Obligations of such Co-Borrower hereunder.

         "Colombia" means the Republic of Colombia.

         "Colombia Permitted Indebtedness" means, with respect to IMPSAT S.A.
(Colombia), (a) Indebtedness pursuant to the Credit Documentation; (b)
Indebtedness of IMPSAT S.A. (Colombia) to IFN or to any Subsidiary of IMPSAT
S.A. (Colombia) or of any such Subsidiary to IMPSAT S.A. (Colombia), in each
case for money borrowed; (c) Indebtedness of IMPSAT S.A. (Colombia) for money
borrowed from financial institutions which Indebtedness is either fully
collateralized by cash deposits of IFN or fully funded by IFN through the
acquisition of one hundred percent (100%) participation in such Indebtedness
from such financial institution; (d) guarantees by IMPSAT S.A. (Colombia) of
obligations of any of its Subsidiaries or guarantees by any such Subsidiary of
obligations of IMPSAT S.A. (Colombia); (e) contingent Indebtedness in respect of
bonds or letters of credit provided to guarantee bids or performance under
contracts in the ordinary course of business; (f) Indebtedness of IMPSAT S.A.
(Colombia) which is in existence on the date hereof and set forth on Exhibit J;
(g) Quasi Equity; (h) Indebtedness for money borrowed for working capital
purposes having an original stated final maturity of three (3) years or less up
to a maximum aggregate amount at any time outstanding not to exceed Fifteen
Million Dollars (US$15,000,000); (i) Indebtedness incurred in connection with
the financing of Capital Expenditures permitted under Section 11.12, (j)
Indebtedness for money borrowed having a stated final maturity not earlier than
the first anniversary of the Final Maturity Date; and

MIA1 #1016002.v8                       6                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   14

                                EXECUTION COPY

(k) Indebtedness incurred and applied to refinance Indebtedness permitted by
each of clauses (a), (b), (c), (f), (g), (h) and (i) above; provided, with
respect to any such refinancing Indebtedness, that (i) the principal amount of
such refinancing Indebtedness does not exceed the principal amount of the
Indebtedness so refinanced; (ii) such refinancing Indebtedness has a final
maturity date equal to or later than the final maturity date of, and has an
average life to maturity equal to or greater than the average life to maturity
of, the Indebtedness being refinanced; and (iii) such Indebtedness is incurred
and/or guaranteed by IMPSAT S.A. (Colombia) and any Subsidiary which had
incurred or guaranteed, as the case may be, the Indebtedness to be refinanced.

         "Commitment" means $30,000,000, subject to the following sublimits:

<TABLE>
<CAPTION>
                  Co-Borrower(s)                              Sublimit
                  --------------                              --------
                 <S>                                        <C>
                  IMPSAT Comunicacoes Ltda.                   $10,000,000
                  (Brazil)

                  The aggregate of all Advances               $20,000,000
                  to IMPSAT S.A. (Argentina),
                  IMPSAT S.A. (Colombia),
                  IMPSATEL Del Ecuador S.A.
                  (Ecuador), and Telecomunicaciones
                  IMPSAT S.A. (Venezuela), but
                  under no circumstances shall
                  the aggregate of all Advances
                  hereunder to IMPSAT S.A. (Colombia),
                  IMPSATEL Del Ecuador S.A.
                  (Ecuador), and Telecomunicaciones
                  IMPSAT S.A. (Venezuela) exceed
                  US$10,000,000.
</TABLE>

         "Commitment Fee" means one percent (1.00%) per annum accruing on the
uncancelled and undisbursed balance of the Facility beginning on the 30th day to
occur after the date hereof and payable in arrears to the Lender on each of July
1, 2001, January 1, 2002, and the date which is the last day of the Availability
Period.

         "Contingent Obligation" means a guarantee, an indemnity obligation in
respect of a guarantee or performance bond (including a fianza), an endorsement,
a contingent agreement to purchase or to furnish funds for the payment or
maintenance of, or otherwise to be or become contingently liable under or with
respect to, any Indebtedness, other obligations, net worth, working capital or
earnings of any Person, or a guarantee of payment of dividends or other
distributions upon the stock or equity interests of any Person, or an agreement
to

MIA1 #1016002.v8                       7                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   15

                                EXECUTION COPY

purchase, sell or lease (as lessee or lessor) property of any Person, products,
materials, supplies or services primarily in each case for the purpose of
enabling a debtor to make payment of its obligations, or an agreement to assure
a creditor against loss, and including causing a bank or other financial
institution to issue a standby letter of credit or other similar instrument for
the benefit of any Person, but excluding endorsement for collection or deposit
in the ordinary course of business.

         "Contract" has the meaning specified in Section 9.01(q).

         "Conversion Rate" shall mean, for purposes of calculating the Dollar
equivalent of any amount in Brazilian Reais, the average of the sale and
purchase rates published by Banco Central do Brasil in the SISBACEN (Sistema de
Informacoes do Banco Central) electronic system, transaction PTAX800, option 5,
offered rate, on the day on which the relevant calculation is to be made.

         "Credit Documentation" means this Agreement, the Security Documents,
the Notes, and the Guaranty Agreement and any exhibits or annexes thereto.

         "Cross Default Amount" means, with respect to any Person, an aggregate
amount of US$5,000,000.

         "Debt Service" means, with respect to any Person for any period, the
sum of (i) the total Interest Expense of such Person and its Subsidiaries during
such period, plus (ii) all amounts of principal and interest, if any, paid or
required to be paid during such period in respect of Total Debt (excluding
Indebtedness in respect of guarantees except to the extent paid by such Person
during such period) of such Person and its Subsidiaries (except principal paid
in respect of Indebtedness contemplated by clause (b) of the definition of
"Permitted Indebtedness" where the funds to pay such principal are provided by a
contribution to Paid in Capital and the payment of principal is made within ten
(10) days after receipt of such contribution); provided, however, that amounts
of principal which are paid under revolving credit or similar facilities and
then reborrowed during the same calendar quarter shall be counted without
duplication.

         "Default" means any condition or event which constitutes an Event of
Default or which, with the giving of notice or the lapse of time or both would,
unless cured or waived, become an Event of Default.

         "Default Rate" means, for any Interest Period, (a) the applicable LIBOR
plus 3.50% per annum in the case of each Co-Borrower other than IMPSAT
Comunicacoes Ltda. (Brazil), and (b) thirteen percent (13%) per annum in the
case of IMPSAT Comunicacoes Ltda. (Brazil).

MIA1 #1016002.v8                       8                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   16

                                EXECUTION COPY

         "Deferred Revenues" means, with respect to a Co-Borrower and as of the
date of determination thereof, the aggregate revenue from IRUs that such
Co-Borrower recognizes in its financial statements over the term of such IRUs as
of the date of such determination.

         "Definitive Note" means a promissory note substantially in the form of
(i) Exhibit B-1 and issued by IMPSAT S.A. (Argentina), (ii) Exhibit B-2 and
issued by IMPSAT Comunicacoes Ltda. (Brazil), (iii) Exhibit B-3 and issued by
IMPSAT S.A. (Colombia), (iv) Exhibit B-4 and issued by IMPSATEL Del Ecuador S.A.
(Ecuador), and (v) Exhibit B-5 and issued by Telecomunicaciones IMPSAT, S.A.
(Venezuela).

         "Dollars" or "$" or "US$" means lawful money of the United States of
America.

         "EBITDA" means, with respect to any Person for any period, the Net
Income of such Person and its Subsidiaries for such period after (a) restoring
thereto amounts deducted for, without duplication, (1) Interest Expense for such
period, (2) taxes based upon net income, (3) depreciation and amortization, and
(4) other non-cash charges and (b) deducting therefrom non-cash income or losses
(including in the case of Impsat S.A. (Argentina) losses arising from Management
Unit Costs) to the extent included in determining Net Income.

         "Ecuador" means the Republic of Ecuador.

         "Ecuador Permitted Indebtedness" means, with respect to IMPSATEL Del
Ecuador S.A. (Ecuador), (a) Indebtedness pursuant to the Credit Documentation;
(b) Indebtedness of IMPSATEL Del Ecuador S.A. (Ecuador) to IFN or to any
Subsidiary of IMPSATEL Del Ecuador S.A. (Ecuador) or of any such Subsidiary to
IMPSATEL Del Ecuador S.A. (Ecuador), in each case for money borrowed; (c)
Indebtedness of IMPSATEL Del Ecuador S.A. (Ecuador) for money borrowed from
financial institutions which Indebtedness is either fully collateralized by cash
deposits of IFN or fully funded by IFN through the acquisition of one hundred
percent (100%) participation in such Indebtedness from such financial
institution; (d) guarantees by IMPSATEL Del Ecuador S.A. (Ecuador) of
obligations of any of its Subsidiaries or guarantees by any such Subsidiary of
obligations of IMPSATEL Del Ecuador S.A. (Ecuador); (e) contingent Indebtedness
in respect of bonds or letters of credit provided to guarantee bids or
performance under contracts in the ordinary course of business; (f) Indebtedness
of IMPSATEL Del Ecuador S.A. (Ecuador) which is in existence on the date hereof
and set forth on Exhibit J; (g) Quasi Equity; (h) Indebtedness for money
borrowed for working capital purposes having an original stated final maturity
of three (3) years or less up to a maximum aggregate amount at any time
outstanding not to exceed Fifteen Million Dollars (US$15,000,000); (i)
Indebtedness incurred in connection with the financing of Capital Expenditures
permitted under Section 11.12, (j) Indebtedness for money borrowed having a
stated final maturity not earlier than the first anniversary of the Final
Maturity Date; and (k) Indebtedness incurred and applied to refinance
Indebtedness permitted by each of clauses (a), (b), (c), (f), (g), (h) and (i)
above; provided, with respect to any such refinancing

MIA1 #1016002.v8                       9                  MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   17

                                EXECUTION COPY

Indebtedness, that (i) the principal amount of such refinancing Indebtedness
does not exceed the principal amount of the Indebtedness so refinanced; (ii)
such refinancing Indebtedness has a final maturity date equal to or later than
the final maturity date of, and has an average life to maturity equal to or
greater than the average life to maturity of, the Indebtedness being refinanced;
and (iii) such Indebtedness is incurred and/or guaranteed by IMPSATEL Del
Ecuador S.A. (Ecuador) and any Subsidiary which had incurred or guaranteed, as
the case may be, the Indebtedness to be refinanced.

         "Eligible Assignee" means, (a) the Lender; (b) a commercial bank or
savings and loan association or savings bank organized under the laws of the
United States of America (or any state thereof) or Canada (or any province
thereof), and having total assets in excess of one hundred million Dollars
(US$100,000,000); (c) a commercial bank organized under the laws of any other
country that is a member of the Basel Accord and the Organization of Economic
Cooperation and Development or has concluded special lending arrangements with
the International Monetary Fund associated with its general arrangements to
borrow, or a political subdivision of any such country, and having total assets
in excess of one hundred million Dollars (US$100,000,000), so long as such bank
is acting through a branch or agency located in the country in which it is
organized or another country that is described in this clause (c); (d) a finance
company, insurance company or other financial institution or fund (whether a
corporation, partnership, trust or other entity) that is principally engaged in
making, purchasing or otherwise investing in commercial loans in the ordinary
course of its business and having total assets in excess of one hundred million
Dollars (US$100,000,000); and (e) any other Person designated by the Lender and
approved by the Guarantor (such approval not to be unreasonably withheld).

         "Equity" means, with respect to any Person at any date, the
consolidated stockholders' equity of such Person and its Subsidiaries as of such
date, determined in accordance with GAAP.

         "Event of Default" has the meaning specified in Section 13.01.

         "Exchange Act" means the U.S. Securities Exchange Act of 1934, as
amended from time to time.

         "Existing Stockholders" means (a) each Individual Stockholder, (b) the
estate or any guardian, custodian or other legal representative of any
Individual Stockholder, (c) any foundation or similar organization organized
under Applicable Law which affords voting control to an Individual Stockholder,
(d) any trust for the benefit of any Individual Stockholder or its family
members which affords voting control to such Individual Stockholder, (e) any
Person in which all of the equity interests are owned directly, or indirectly,
by any of the Persons named in clauses (a) through (d).

MIA1 #1016002.v8                       10                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   18

                                EXECUTION COPY

         "Facility" means the financing transaction or transactions contemplated
by this Agreement, including the Advances outstanding from time to time and the
obligations of the Lender to make Advances pursuant to the terms of this
Agreement.

         "Final Maturity Date" means July 1, 2005.

         "First Advance" has the meaning specified in Section 7.02.

         "First Interest Payment Date" with respect to any Advance means July 1,
2001, unless the Initial Borrowing Date occurs less than 30 days prior thereto,
in which case the First Interest Payment Date shall be the next January 1 or
July 1 to occur at least 30 days after the Initial Borrowing Date.

         "First Repayment Date" shall mean July 1, 2002.

         "GAAP" means generally accepted accounting principles, consistently
applied in (i) a Co-Borrower's country as applied to a Co-Borrower, and (ii) the
United States as applied to the Guarantor.

         "Goods and Services" has the meaning specified in the first WHEREAS
clause.

         "Governmental Authority" means any nation or government, any state or
other political subdivision thereof, and any entity exercising executive,
legislative, judicial, regulatory or administrative functions of, or pertaining
to, government.

         "Governmental Approval" has the meaning specified in Section 9.01(c)
(iii).

         "Grid Note" means a promissory note as approved by the Lender
substantially in the form of (i) Exhibit A-1 and issued by IMPSAT S.A.
(Argentina), (ii) Exhibit A-2 and issued by IMPSAT Comunicacoes Ltda. (Brazil),
(iii) Exhibit A-3 and issued by IMPSAT S.A. (Colombia), (iv) Exhibit A-4 and
issued by IMPSATEL Del Ecuador S.A. (Ecuador), and (v) Exhibit A-5 and issued by
Telecomunicaciones IMPSAT, S.A. (Venezuela).

         "Guaranty" means the guaranty set forth in Article XII.

         "Guaranty Agreement" means the guaranty agreement executed by the
Guarantor and in substantially the form of Exhibit C.

         "Guarantor" has the meaning specified in the Preamble.

         "Guarantor Subsidiaries" means Subsidiaries that are not also
Co-Borrowers hereunder.

         "Harris" has the meaning specified in the first WHEREAS clause.

MIA1 #1016002.v8                       11                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   19

                                EXECUTION COPY

         "IFN" means Impsat Fiber Networks, Inc., a Delaware corporation.

         "Import Duties" means payments made by either IMPSAT S.A. (Argentina),
IMPSAT S.A. (Colombia), IMPSATEL Del Ecuador S.A. (Ecuador), or
Telecomunicaciones IMPSAT, S.A. (Venezuela), as the case may be, to a
Governmental Authority in respect of import duties assessed by such Governmental
Authority for the importation of Goods and Services financed hereunder into such
Governmental Authority's country.

         "Import Duties Conversion Rate" means, as the date of payment of Import
Duties by a Co-Borrower to the appropriate Government Authority in such
Co-Borrower's country, the official spot-market exchange rate for Dollars as
published in a reputable financial daily newspaper for such date of payment, or,
if such spot-market exchange rate is unavailable for such date of payment, an
equivalent substitute exchange rate selected or determined by the Lender after
consultation with a Co-Borrower.

         "IMPSAT Indentures" means collectively the 2003 Indenture, the 2005
Indenture and the 2008 Indenture.

         "Indebtedness" with respect to any Person means any amount payable by
such Person as debtor, borrower or guarantor pursuant to an agreement or
instrument involving or evidencing money borrowed or received, the advance of
credit, a conditional sale or a transfer with recourse or with an obligation to
repurchase, or pursuant to a lease with substantially the same economic effect
as any such agreement or instrument or any obligation secured by a Lien.

         "Indemnified Liabilities" has the meaning specified in Section 15.15.

         "Indemnity" means an indemnity agreement between the Lender and a
Co-Borrower substantially in the form of Exhibit L.

         "Individual Stockholder" means each of the following Persons: Ricardo
Verdaguer, Roberto Vivo Chaneton, Enrique Pescarmona, Monica Pescarmona de
Baldini, Liliana Pescarmona de Mayol, and Alexander Rivelis.

         "Initial Borrowing Date" means the first Borrowing Date under this
Agreement.

         "Initial Purchase Order" means the initial purchase order issued to
Harris by a Co-Borrower and in accordance with the terms of the Supply
Contract(s).

         "Intelsat" means the International Telecommunications Satellite
Organization.

         "Interest Expense" means, with respect to any Person for any period,
interest expense, both expensed and capitalized, of such Person and its
Subsidiaries for such period, including

MIA1 #1016002.v8                       12                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   20

                                EXECUTION COPY

accrued interest and the interest component of capital lease obligations, all
commissions, discounts, fees and charges.

         "Interest Payment Date" with respect to any Advance means each of the
First Interest Payment Date and semiannually thereafter upon January 1 or July 1
as the case may be.

         "Interest Period" with respect to any Advance means the period (i)
beginning on the Borrowing Date (in the case of the initial Interest Period) for
such Advance or on the last day of the next preceding Interest Period (in the
case of any subsequent Interest Period) for such Advance, provided that in case
of IMPSAT Comunicacoes Ltda. (Brazil), the initial Interest Period shall begin
in accordance with Section 2.08(b), and (ii) ending on the next occurring
Interest Payment Date; provided, that any Interest Period which would otherwise
end after the Final Maturity Date shall end on the Final Maturity Date.

         "Investment" means the acquisition of any Capital Stock, evidence of
Indebtedness, securities (including any option, warrant or other right to
acquire any of the foregoing) of, the making of any loans or advances to, the
guaranteeing of any obligations of any Person, or the purchase or other
acquisition (in one transaction or a series of transactions) of any assets
constituting a business unit.

         "Invoice" means any invoice issued by Harris to a Co-Borrower pursuant
to the Supply Contract(s) or in respect of a Purchase Order, as the case may be.

         "IRU" means, with respect to any Co-Borrower, the creation of an
usufructo under Applicable Law on any portion of such Co-Borrower's
telecommunications network (other than the Collateral) or any lease, similar
agreement or arrangement pursuant to which such Co-Borrower grants the right to
use a portion of its telecommunications network to any Person for a period of
time of five (5) or more years in exchange for consideration payable in a form
other than periodic payments at quarterly or more frequent intervals.

         "Issuance" means a making of an Advance to a Co-Borrower by the Lender
on a specific date.

         "Issuance Date" means any date on which an Issuance is made.

         "Lender" means Harris Canada, Inc. or any Affiliate of Harris Canada,
Inc. designated by Harris Canada, Inc. as the Lender, and any assignees under
Section 15.01(b).

         "Lender's Local Counsel" means (i) in Argentina, Alvarez, Prado,
Cabanellas y Kelly, (ii) in Brazil, Holland & Knight-Evaldo Ramos Advogados
Associados, (iii) in Colombia, Gomez, Pinzon y Associados, (iv) in Ecuador,
Bustamante y Bustamante, and (v) in Venezuela, Tinoco, Travieso, Planchart and
Nunez.

MIA1 #1016002.v8                       13                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   21

                                EXECUTION COPY

         "LIBOR," for each Interest Period means the rate per annum determined
as of two Banking Days before the first day of such Interest Period as the
average (rounded upwards to the nearest 1/16th of the percent) of the rates
quoted on the Reuters Screen LIBO Page by the banks used as reference banks for
such service as the rates offered by such banks for three-month or six-month
deposits in Dollars; where the relevant Interest Period would be ninety (90)
days or less the three-month deposit rate shall be used, and where the relevant
Interest Period is more than ninety (90) days the six-month deposit rate shall
be used. If it is not possible to determine LIBOR in this way for any Interest
Period, LIBOR shall mean the rate per annum which the Bank, on the date of
calculation, is prepared to accept as a rate of return on deposits of Dollars,
with first class banks in the London interbank market, or if the Bank cannot
make Dollar deposits in London, then in the New York interbank market, in
amounts equal or comparable to the relevant amount advanced or principal
outstanding, for periods equal or comparable to the relevant Interest Period.

         "License" means any license, concession, authorization, certificate of
compliance, franchise, approval or permit, granted or issued by any Governmental
Authority and held by a Co-Borrower or any of its Subsidiaries in connection
with the Telecommunications Business.

         "Lien" means any mortgage, pledge, lien, charge, attachment, set-off,
encumbrance or other security interest in the nature thereof (including, without
limitation, any conditional sale agreement, equipment trust agreement or other
title retention agreement, or a lease with substantially the same economic
effect as any such agreement) or other encumbrance of any nature whatsoever.

         "Loan" at any time means the aggregate principal amount of all Advances
to a Co-Borrower hereunder then outstanding.

         "Management Unit Costs" means salaries, benefits, and other personnel
costs incurred by IMPSAT S.A. (Argentina) on behalf of management-level
employees of the Guarantor.

         "Material Adverse Change" means an event, circumstance or development
of whatever nature that has had or could reasonably be expected to have a
Material Adverse Effect.

         "Material Adverse Effect" means a material adverse effect on (a) the
business, assets, results of operations, condition (financial or otherwise) or
prospects of any of the Guarantor and its Subsidiaries taken as a whole, IMPSAT
S.A. (Argentina), or IMPSAT Comunicacoes Ltda. (Brazil), (b) the ability of any
Co-Borrower or the Guarantor to perform their respective obligations under any
of the documentation comprising the Facility; (c) the rights and remedies of the
Lender under this Agreement, the Security Documents, the Notes or the Guaranty
Agreement; (d) the validity or enforceability of this Agreement, the Security
Documents, the Notes or the Guaranty Agreement; (e) the Licenses or the rights
of the Co-Borrower thereunder; or (f) the Collateral.

MIA1 #1016002.v8                       14                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   22

                                EXECUTION COPY

         "Net Income" means, for any period, the net income (loss) of a Person
and its Subsidiaries, determined on a consolidated basis, for such period in
accordance with GAAP.

         "New Skies" means New Skies Satellites N.V.

         "Note" means a Grid Note or a Definitive Note.

         "Notice" has the meaning specified in Section 15.03.

         "Obligations" means, without duplication, all present and future
Advances, Loans, Indebtedness, Taxes, liabilities, obligations, covenants,
duties, and debts, owing by each Co-Borrower to the Lender, arising under or
pursuant to this Agreement, including, without limitation, all principal,
interest, charges, expenses, fees and any other sums chargeable to such
Co-Borrower hereunder.

         "Organization Documents" means, with respect to any Person (other than
an individual), its founding act, charter, certificate of incorporation,
by-laws, memorandum or articles of association, contrato social, estatuto
social, and other similar documents regarding it's organization or constitution.

         "Paid in Capital" means, with respect to any Person, at any time, the
aggregate amount of capital contributed to such Person in the form of cash or
capitalized Indebtedness.

         "Party" or "Parties" has the meaning specified in the opening paragraph
of this Agreement.

         "Payment Date" means a date upon which a payment of principal or
interest is due and payable hereunder, or if such date is not a Banking Day, the
next Banking Day.

         "Permitted Fianzas" means, with respect to a Co-Borrower, any and all
fianzas issued on behalf of a Co-Borrower in the ordinary course of business in
favor of (a) telecommunications providers in such Co-Borrower's country pursuant
to interconnection agreements, (b) any other Person to secure the payment by
such Co-Borrower of operating expenses to such Person, or (c) a Governmental
Authority which is a customer of such Co-Borrower pursuant to the Co-Borrower's
contract with such customer.

         "Permitted Indebtedness" means, as the context requires, Argentina
Permitted Indebtedness, Brazil Permitted Indebtedness, Colombia Permitted
Indebtedness, Ecuador Permitted Indebtedness, or Venezuela Permitted
Indebtedness including, in each such instance, amounts that have been committed
but not disbursed.

         "Permitted Investments" means: (a) Temporary Cash Investments; (b)
Investments in the form of inter-company Indebtedness which constitutes
Permitted Indebtedness; (c) accounts

MIA1 #1016002.v8                       15                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   23

                                EXECUTION COPY

receivable owing to such Co-Borrower or any Subsidiary thereof if created or
acquired in the ordinary course of business and payable or dischargeable in
accordance with customary trade terms; (d) payroll, travel and similar advances
and advances to suppliers to cover matters that are expected at the time of such
advances ultimately to be treated as expenses for accounting purposes and that
are made in the ordinary course of business; (e) stock, obligations or
securities received in satisfaction of judgments, work-outs, assignments for the
benefit of creditors or other similar judicial proceedings; (f) investments in
Capital Stock of Intelsat or New Skies to the extent permitted by the IMPSAT
Indentures, and (g) the existing Investments of IMPSATEL Del Ecuador S.A.
(Ecuador) in TransTeledatos SA, a sociedad anonima organized under the laws of
Ecuador.

         "Permitted Liens" means:

         (a)      Liens established pursuant to the terms hereof;

         (b)      Liens securing taxes not yet due or being contested in good
faith by appropriate proceedings for which adequate reserves determined in
accordance with GAAP have been established (and as to which the property subject
to any such Lien is not yet subject to foreclosure, seizure, arrest, sale,
collection, levy or loss on account thereof);

         (c)      nonconsensual statutory Liens which are imposed by Applicable
Law arising in the ordinary course of business and securing obligations which
are not yet due and payable or which are being contested in good faith by
appropriate proceedings for which adequate reserves determined in accordance
with GAAP have been established (and as to which the property subject to any
such Lien is not yet subject to foreclosure, sale or loss on account thereof);

         (d)      pledges or deposits made in the ordinary course of business to
secure payment of worker's compensation insurance, unemployment insurance,
pensions or social security programs;

         (e)      easements, rights-of-way, restrictions and other similar
encumbrances on real property which, in the aggregate, are not substantial in
amount and which do not in any case materially detract from the value of the
property to the Co-Borrower or materially interfere with the ordinary conduct of
the business of the Co-Borrower or a Subsidiary;

         (f)      Liens arising by virtue of any Applicable Law in favor of
banks or other financial institutions on cash or rights of setoff or similar
rights as to deposit accounts or other funds maintained with a creditor
depository institution;

         (g)      Liens on goods (and the documents of title relating thereto)
the purchase price, shipment or storage of which is financed by a documentary
letter credit issued for the account of a Co-Borrower or a Subsidiary thereof in
the ordinary course of business, provided that

MIA1 #1016002.v8                       16                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   24

                                EXECUTION COPY

such Lien secures only the obligations of such Co-Borrower or such Subsidiary in
respect of such letter of credit;

         (h)      any interest or title of a lessor or vendor in the property
subject to any lease or installment sale;

         (i)      Liens in favor of customs and revenue authorities arising as a
matter of law to secure payment of customs duties in connection with the
importation of goods in the ordinary course of business (and as to which the
property subject to any such Lien is not yet subject to foreclosure, seizure,
arrest, sale, collection, levy or loss on account thereof);

         (j)      Liens on interests of IMPSAT S.A. (Argentina) in Intelsat and
New Skies in favor of Credit Lyonnais;

         (k)      Liens arising under any IRU;

         (l)      Liens on or sales of existing or future receivables; and

         (m)      Liens (including extensions and renewals thereof) upon real or
personal property, provided that (i) such Lien is created solely for the purpose
of securing Indebtedness incurred (1) to finance the cost (including the cost of
design, development, acquisition, construction, installation, improvement,
transportation or integration) of the item of property or assets subject thereto
and such Lien is created prior to, at the time of or within six (6) months after
the later of the acquisition, the completion of construction or the commencement
of full operation of such property or (2) to refinance any Indebtedness
previously so secured, (ii) the principal amount of the Indebtedness secured by
such Lien does not exceed one hundred percent (100%) of such cost and (iii) any
such Lien shall not extend to or cover any property or assets other than such
item of property or assets and any improvements on such item.

         "Person" means an individual, corporation, association, limited
liability company, limited liability partnership, partnership, estate, trust,
unincorporated organization or a government or any agency or political
subdivision thereof.

         "Pledge Agreement" means a pledge agreement, executed and delivered by
each Co-Borrower to the Lender securing such Co-Borrower's Obligations hereunder
by granting a security interest to the Lender in the equipment financed
hereunder and registered with the appropriate Governmental Authority in such
Co-Borrower's country.

         "Pledged Shareholder Note" means any of (a) a promissory note of IMPSAT
S.A. (Argentina) endorsed and delivered in pledge to Nortel Networks Corporation
evidencing Indebtedness of IMPSAT S.A. (Argentina) for money borrowed from the
Guarantor (i) the principal amount of which is payable in a single payment not
earlier than the first anniversary

MIA1 #1016002.v8                       17                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   25

                                EXECUTION COPY

of the maturity date of the loans evidenced by the Loan Agreement among Nortel
Networks Corporation, IMPSAT S.A. (Argentina), and lenders thereunder dated as
of October 25, 1999, and (ii) the interest on which is payable at a per annum
rate no greater than the rate payable on the securities issued under the 2008
Indenture, or (b) a promissory note of IMPSAT Comunicacoes Ltda. (Brazil)
endorsed and delivered in pledge to Nortel Networks Corporation evidencing
Indebtedness of IMPSAT Comunicacoes Ltda. (Brazil) for money borrowed from the
Guarantor (i) the principal amount of which is payable in a single payment not
earlier than the first anniversary of the maturity date of the loans evidenced
by the Loan Agreement among Nortel Networks Corporation, IMPSAT Comunicacoes
Ltda. (Brazil), and lenders thereunder dated as of October 25, 1999, and (ii)
the interest on which is payable at a per annum rate no greater than the rate
payable on the securities issued under the 2008 Indenture

         "Proceeding" has the meaning specified in Section 15.11.

         "Process Agent" means CT Corporation System, with offices at 111-Eighth
Avenue, New York, NY 10011 USA, as agent for purposes of receiving service of
process or other legal summons from a Person in any action or proceeding in the
courts of the State of New York or the Federal courts sitting in the City of New
York.

         "Purchase Order" means the provision of a purchase order, issued by a
Co-Borrower pursuant to the terms of the Supply Contract(s) and accepted by
Harris for the shipment of Goods and Services on a date that is no earlier than
November 28, 2000 and no later than the last day of the Availability Period.

         "Quasi Equity" means the aggregate principal amount of all Pledged
Shareholder Notes.

         "Reais" means the lawful currency of Brazil.

         "Repayment Date" with respect to any Advance means each of the First
Repayment Date and semiannually thereafter upon January 1 or July 1 as the case
may be.

         "Restricted Obligations" means (a) any Capital Stock of a Co-Borrower;
(b) any Capital Stock of any Subsidiary of such Co-Borrower that is not owned by
such Co-Borrower; (c) any warrants or options to purchase any Capital Stock of
such Co-Borrower or any Subsidiary of such Co-Borrower; (d) any Indebtedness or
other payment obligation of any kind from such Co-Borrower or any Subsidiary of
such Co-Borrower to any shareholder of such Co-Borrower or of any Subsidiary of
such Co-Borrower; and (e) any obligation to any Person that is guaranteed in
whole or in part by any Subsidiary of a Co-Borrower whether now existing or
hereafter created.

         "Restricted Payment" means the declaration or payment of any dividend
or distribution in respect of, or any payment of principal, interest, premium or
any other amount in respect

MIA1 #1016002.v8                       18                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   26

                                EXECUTION COPY

of, or the purchase, redemption, defeasance, retirement or other acquisition of,
any Restricted Obligation, or the setting aside of any assets (in any sinking
fund or analogous fund or otherwise) for any such purpose.

         "Revenue Recognition from IRUs" means, with respect to a Co-Borrower
and as of a date of determination thereof, the portion of Deferred Revenues that
such Co-Borrower recognizes as revenue under its financial statements for the
four (4) consecutive calendar quarters occurring prior to such date of
determination.

         "Second Advance" has the meaning specified in Section 7.03.

         "Security Documents" means a Pledge Agreement or such documentation as
the Lender may require pursuant to the terms hereof for purposes of obtaining a
perfected security interest in the Collateral with respect to a Co-Borrower.

         "Subsidiary" means, with respect to a Co-Borrower or the Guarantor, at
any time, any entity of which more than fifty percent (50%) of the outstanding
voting stock or other equity interest entitled ordinarily to vote in the
election of the directors or other governing body (however designated) is at the
time beneficially owned or controlled directly or indirectly by such Co-Borrower
or the Guarantor (as the case may be), by one or more such entities or by such
Co-Borrower or the Guarantor (as the case may be) and one or more such entities.

         "Supplemental Documentation" means agreements, instruments, documents,
certificates, financing statements, warehouse receipts, bills of lading, notices
of assignment of accounts, schedules of accounts assigned, mortgages and other
written materials necessary or requested by the Lender to perfect and maintain
perfected the Lender's security interest in the Collateral and/or to consummate
the transactions contemplated in or by this Agreement and the Security
Documents.

         "Supply Contract(s)" has the meaning specified in the first WHEREAS
clause.

         "Taxes" has the meaning specified in Section 5.01.

         "Telecommunications Business" means telecommunications services, value
added telecommunications services, radio paging, mobile telecommunications,
personal telecommunications services, trunking, transport of broadcasting
signals, information technology, Internet services and related and ancillary
services in Co-Borrower's country in which such Co-Borrower or any of its
Subsidiaries is from time to time engaged.

         "Temporary Cash Investment" means, as to any Co-Borrower, any of the
following: (a) direct obligations of the United States of America or any agency
thereof or obligations fully and unconditionally guaranteed by the United States
of America or any agency thereof, (b) time deposit accounts, certificates of
deposit and money market deposits maturing within one

MIA1 #1016002.v8                       19                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   27

                                EXECUTION COPY

year of the date of acquisition thereof issued by a bank or trust company which
is organized under the laws of the United States of America, any state thereof
or any foreign country recognized by the United States of America, and which
bank or trust company has capital, surplus and undivided profits aggregating in
excess of fifty million Dollars (US$50,000,000) (or the foreign currency
equivalent thereof) and has outstanding debt which is rated "A" (or such similar
equivalent rating) or higher by at least one nationally recognized statistical
rating organization (as defined in Rule 436 under the Securities Act) or any
money market fund sponsored by a registered broker dealer or mutual fund
distributor, (c) repurchase obligations with a term of not more than thirty (30)
days for underlying securities of the types described in clause (a) above
entered into with a bank meeting the qualifications described in clause (b)
above, (d) commercial paper, maturing not more than one year after the date of
acquisition, issued by a corporation (other than an Affiliate of any Co-Borrower
or the Guarantor) organized and in existence under the laws of the United States
of America, any state thereof or any foreign country recognized by the United
States of America with a rating the time as of which any investment therein is
made of "P-1" (or higher) according to Moody's Investor Service, Inc.
("Moody's") or "A-1" (or higher) according to Standard & Poor's Ratings Services
("S&P"), (e) securities with maturities of six (6) months or less from the date
of acquisition issued or fully and unconditionally guaranteed by any state,
commonwealth or territory of the United States of America, or by any political
subdivision or taxing authority thereof, and rated at least "A" by S&P or
Moody's, and (f) certificates of deposit maturing not more than one (1) year
after the acquisition thereof by a Co-Borrower or a Subsidiary thereof and
issued by any of the ten (10) largest banks (based on assets as of December 31,
2000) organized under the laws of such Co-Borrower's country provided that any
such bank is not under intervention, receivership or any similar arrangement at
the time of the acquisition of such certificates of deposit.

         "Total Debt" means, at any date, all indebtedness of a Co-Borrower and
its Subsidiaries at such date other than the subordinated indebtedness.

         "Total Equity" means, with respect to any Person at any date, the sum
of (a) the Equity of such Person as of such date, plus (b) the Quasi Equity of
such Person as of such date.

         "2003 Indenture" means the Indenture dated as of July 30, 1996 and as
amended on May 13, 1997 among IFN, as Issuer, IMPSAT S.A. (Argentina) as
Guarantor, and The Bank of New York as Trustee, relating to the 12 1/8% Senior
Guaranteed Notes due 2003 of IMPSAT Corporation.

         "2005 Indenture" means the Indenture dated February 16, 2000 between
IFN, as Issuer, the Bank of New York, as Trustee, Registrar and Paying Agent,
and The Banque Internationale a Luxembourg S.A., as Paying Agent and Transfer
Agent, relating to the 13 3/4% Senior Notes due 2005 of IFN.

MIA1 #1016002.v8                       20                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   28

                                EXECUTION COPY

         "2008 Indenture" means the Indenture dated as of June 17, 1998 between
IFN, as Issuer, and The Bank of New York, as Trustee, relating to the 12 3/8%
Senior Notes due 2008 of IFN.

         "United States" means the United States of America.

         "Venezuela" means the Bolivarian Republic of Venezuela.

         "Venezuela Permitted Indebtedness" means, with respect to
Telecomunicaciones IMPSAT, S.A. (Venezuela), (a) Indebtedness pursuant to the
Credit Documentation; (b) Indebtedness of Telecomunicaciones IMPSAT, S.A.
(Venezuela) to IFN or to any Subsidiary of Telecomunicaciones IMPSAT, S.A.
(Venezuela) or of any such Subsidiary to Telecomunicaciones IMPSAT, S.A.
(Venezuela), in each case for money borrowed; (c) Indebtedness of
Telecomunicaciones IMPSAT, S.A. (Venezuela) for money borrowed from financial
institutions which Indebtedness is either fully collateralized by cash deposits
of IFN or fully funded by IFN through the acquisition of one hundred percent
(100%) participation in such Indebtedness from such financial institution; (d)
guarantees by Telecomunicaciones IMPSAT, S.A. (Venezuela) of obligations of any
of its Subsidiaries or guarantees by any such Subsidiary of obligations of
Telecomunicaciones IMPSAT, S.A. (Venezuela); (e) contingent Indebtedness in
respect of bonds or letters of credit provided to guarantee bids or performance
under contracts in the ordinary course of business; (f) Indebtedness of
Telecomunicaciones IMPSAT, S.A. (Venezuela) which is in existence on the date
hereof and set forth on Exhibit J; (g) Quasi Equity; (h) Indebtedness for money
borrowed for working capital purposes having an original stated final maturity
of three (3) years or less up to a maximum aggregate amount at any time
outstanding not to exceed Fifteen Million Dollars (US$15,000,000); (i)
Indebtedness incurred in connection with the financing of Capital Expenditures
permitted under Section 11.12, (j) Indebtedness for money borrowed having a
stated final maturity not earlier than the first anniversary of the Final
Maturity Date; and (k) Indebtedness incurred and applied to refinance
Indebtedness permitted by each of clauses (a), (b), (c), (f), (g), (h) and (i)
above; provided, with respect to any such refinancing Indebtedness, that (i) the
principal amount of such refinancing Indebtedness does not exceed the principal
amount of the Indebtedness so refinanced; (ii) such refinancing Indebtedness has
a final maturity date equal to or later than the final maturity date of, and has
an average life to maturity equal to or greater than the average life to
maturity of, the Indebtedness being refinanced; and (iii) such Indebtedness is
incurred and/or guaranteed by Telecomunicaciones IMPSAT, S.A. (Venezuela) and
any Subsidiary which had incurred or guaranteed, as the case may be, the
Indebtedness to be refinanced.

         "Voting Stock" means with respect to any Person, Capital Stock of any
class or kind ordinarily having the power to vote for the election of directors,
managers or other voting members of the governing body of such Person.

MIA1 #1016002.v8                       21                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   29

                                EXECUTION COPY

         "Wholly Owned Subsidiary" means, with respect to any Person, a
subsidiary of which securities (except for directors' qualifying shares) of
other ownership interests representing 99.9% of the equity or 99.9% of the
ordinary voting power or 99.9% of the general partnership interest are, at the
time any determination is being made, owned, controlled or held by such Person
or one or more Wholly Owned Subsidiaries.

         Section 1.02.  Principles of Construction

         (a)      The meanings set forth for defined terms in Section 1.01 or
elsewhere in this Agreement shall be equally applicable to both the singular and
plural forms of the terms defined.

         (b)      Unless otherwise specified, all reference in this Agreement to
Articles, Sections and Exhibits are to Articles, Sections and Exhibits in or to
this Agreement.

         (c)      The headings of the Articles and Sections in this Agreement
are included for convenience only and shall not in any way affect the meaning or
construction of any provision of this Agreement.

         (d)      Any reference herein to any Person shall be construed to
include such Person's successors and permitted assigns.

                                   ARTICLE II
                          COMMITMENT; CREDIT OF ADVANCE

         Section 2.01. Commitment to Lend. On the terms and subject to the
conditions set forth herein, the Lender shall, upon a Co-Borrower's request made
in accordance with Section 2.02, make advances hereunder to such Co-Borrower
during the Availability Period in amounts corresponding to the payment
obligations of such Co-Borrower specified in an Invoice issued pursuant to the
terms of either the Supply Contract(s) or as Harris otherwise issues in respect
of a Purchase Order (each such advance, an "Advance"); provided, however, that
the principal amount of the Advances made by the Lender hereunder shall not, in
the aggregate, exceed the Commitment, and the aggregate principal amount of
Advances made to any Co-Borrower shall not exceed the applicable sublimit set
forth in the definition of "Commitment". In no event shall the Lender be
obligated to advance cash to or on behalf of any Co-Borrower hereunder except in
respect of Import Duties or pursuant to a Brazil Notice of Borrowing.

         Section 2.02. Notice of Intention and Commitment to Borrow.

         (a)      Subject to Section 2.01, the Parties hereby agree that the
issuance of a Purchase Order by a Co-Borrower (except IMPSAT Comunicacoes Ltda.
(Brazil)) shall constitute such Co-Borrower's irrevocable commitment to borrow
an amount equal to the amount specified in Harris' Invoice issued in respect
thereof ("Advance Amount") on the Issuance Date of such

MIA1 #1016002.v8                       22                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   30

                                EXECUTION COPY

Invoice, or if such date is not a Banking Day, the date of the next-occurring
Banking Day ("Borrowing Date"), and

         (b)      Borrowings for IMPSAT Comunicacoes Ltda. (Brazil) shall be
made subject to the terms of Section 2.08.

         (c)      Except to the extent provided in Section 2.02(d) with respect
to IMPSAT S.A. (Colombia), borrowings in respect of Import Duties shall be made
upon the Lender's receipt of a request for reimbursement therefor, made by a
Co-Borrower, in each case detailing the amounts paid by such Co-Borrower, or on
its behalf, to the appropriate Governmental Authority, the dates of such
payments and the amounts of such payments in Dollars, determined at the Import
Duties Conversion Rate. Such request for reimbursement of Import Duties shall
constitute an irrevocable commitment by such Co-Borrower to borrow such amounts
hereunder. Each request for reimbursement of Import Duties hereunder shall be
accompanied by a statement executed by the chief financial officer of such
Co-Borrower either (a) specifying the Import Duties Conversion Rate for the
payment date of such Import Duties, or (b) certifying that an official
spot-market exchange rate in Dollars was unavailable on the payment date. In the
event that an official spot-market exchange rate is unavailable on a payment
date for Import Duties, the Lender and the respective Co-Borrower shall consult
with each other to determine an appropriate substitute exchange rate. In the
event that the Lender and such Co-Borrower fail to agree on such substitute
exchange rate after ten (10) days, the Lender shall determine such substitute
exchange rate, taking into account for such purposes the most recently published
spot-market exchange rate for Dollars in such Co-Borrower's country. Such
determination by the Lender shall then be deemed to constitute the Import Duties
Conversion Rate for purposes of financing such Import Duties hereunder.

         (d)      For purposes of Section 2.02(c), Telecomunicaciones IMPSAT,
S.A. (Venezuela) shall submit all requests for reimbursement of Import Duties on
behalf of IMPSAT S.A. (Colombia), and the Lender shall disburse all amounts
approved for financing pursuant to Section 2.03(c) to Telecomunicaciones IMPSAT,
S.A. (Venezuela) as Advances to Telecomunicaciones IMPSAT, S.A. (Venezuela).

         Section 2.03. Making of Advances; Credit of Advance Amount.

         (a)      Subject to the conditions for the making of Advances by the
Lender set forth herein, the Lender shall, on each Borrowing Date, (i) credit
the related Advance Amount against the amounts due to it by such Co-Borrower
under each Purchase Order or (ii) disburse, in accordance with Section 2.08, the
Advance Amount to IMPSAT Comunicacoes Ltda. (Brazil) (via wire instructions to
be provided to Harris do Brasil Ltda. by IMPSAT Comunicacoes Ltda. (Brazil)
pursuant to a side letter to be entered into among Harris do Brasil Ltda.,
IMPSAT Comunicacoes Ltda. (Brazil), and a commercial bank acceptable to Harris
do

MIA1 #1016002.v8                       23                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   31

                                EXECUTION COPY

Brasil Ltda.) in Dollars at the Conversion Rate determined as of the date of
the Brazil Notice of Borrowing (as defined in Section 2.08);

         (b)      Pursuant to Section 2.06, the Lender shall make the amount of
each Advance available by ledger entry of a credit against the Purchase Order or
Brazil Notice of Borrowing (as the case may be) on the related Borrowing Date to
such account as may be specified by the Lender or by Harris to the Lender.

         (c)      Pursuant to Section 2.02(c) and not later than 1:00 p.m. (New
York time), the Lender shall arrange for a wire transfer of immediately
available funds in Dollars in the amount specified in the request for
reimbursement issued in respect of such Import Duties to an account of such
Co-Borrower at a commercial bank pursuant to wire instructions to be provided to
the Lender by such Co-Borrower in such request for reimbursement.

         Section 2.04. Commitments Not Revolving. The Lender's commitment to
lend hereunder is not revolving in nature, and any amounts of Advances repaid or
prepaid may not be reborrowed.

         Section 2.05. Intentionally Left Blank.

         Section 2.06. Loan Account. The Lender shall maintain five separate
loan accounts on its books, one in the name of each Co-Borrower in which will be
recorded each Advance made to such Co-Borrower and all payments of principal of
and interest on each Advance. The entries in said account (in the absence of
manifest error in the making thereof) shall constitute prima facie evidence of
the outstanding principal of and interest on each Advance from time to time.

         Section 2.07. Acknowledgment of Advances. On a quarterly basis as the
Lender shall determine and until all amounts under this Agreement have been
fully advanced, each Co-Borrower will receive from the Lender an acknowledgment
of all Advances made hereunder to such Co-Borrower ("Acknowledgment of
Advances"). Upon receipt by a Co-Borrower of each Acknowledgment of Advances
from the Lender, such Co-Borrower shall examine and confirm that the information
contained in such Acknowledgment of Advances is true and accurate by returning a
copy of such Acknowledgment of Advances signed by an authorized officer of such
Co-Borrower to the Lender within three (3) Banking Days. Should such Co-Borrower
believe that the information contained in such Acknowledgment of Advances to not
be accurate with respect to the Advances previously received by such
Co-Borrower, such Co-Borrower shall immediately give Notice to the Lender
thereof. Should such Co-Borrower give Notice to the Lender that such Co-Borrower
believes that the Acknowledgment of Advances received is inaccurate, the Parties
agree, upon Notice having been received by the Lender within three (3) Banking
Days of such Acknowledgment of Advances, to consult with each other regarding
such Co-Borrower's concerns and shall, if necessary, cause reissuance of such

MIA1 #1016002.v8                       24                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   32

                                EXECUTION COPY

Acknowledgment of Advances to which such Co-Borrower shall confirm that the
information contained therein is true and correct and return such Acknowledgment
of Advances signed by an authorized officer of such Co-Borrower to the Lender
with three (3) Banking days of such reissuance. In the event that the Parties
are unable to agree upon the content of the Acknowledgment of Advances, the
Lender shall have the right, but not the obligation, to suspend further Advances
pursuant to Section 13.05.

         Section 2.08.  Brazil Notice of Borrowing.

         (a)      For Advances made to IMPSAT Comunicacoes Ltda. (Brazil), the
Lender shall have received prior to the date of such Advance a notice of
borrowing from such Co-Borrower in substantially the form of Exhibit I ("Brazil
Notice of Borrowing"). No Advance shall be made hereunder by the Lender to
IMPSAT Comunicacoes Ltda. (Brazil) until the Brazil Notice of Borrowing, the
conditions for disbursement of Advances, and the requirements of Section 2.03
are fulfilled to the satisfaction of the Lender.

         (b)      Not later than 1:00 p.m. (New York time) on the proposed
Issuance Date, the Lender shall arrange for a wire transfer of immediately
available funds in the amount of the principal amount of the Advances to be made
pursuant to such Issuance to an account of IMPSAT Comunicacoes Ltda.(Brazil) at
a commercial bank designated by the Lender pursuant to wire instructions set
forth in the Brazil Notice of Borrowing. Notwithstanding anything herein to the
contrary, no interest shall accrue on any such Advance until the funds
constituting such Advance are deposited in such account.

         (c)      The Dollar amount for any Advance made under this Section 2.08
shall be established by converting the corresponding amount of Reais at the
Conversion Rate determined as of the date of the relevant Brazil Notice of
Borrowing.

                                   ARTICLE III
                                    REPAYMENT

         Section 3.01. Repayment.

         (a)      Except as otherwise expressly provided herein, each
Co-Borrower shall repay each Advance made to such Co-Borrower as specified
herein.

         (b)      Each Co-Borrower shall pay to the Lender or its order, an
aggregate of outstanding principal amounts of the Advances made to such
Co-Borrower payable hereunder in seven (7) substantially equal, consecutive
installments on successive Repayment Dates commencing on the First Repayment
Date, or, if Advances are made after the First Repayment Date, each installment
shall be in an amount equal to the result obtained by dividing the amount of the
Advances outstanding made to such Co-Borrower 30 days prior to the
next-occurring Repayment Date on which such installment is due by the number of
installments then

MIA1 #1016002.v8                       25                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   33

                                EXECUTION COPY

remaining to be paid, provided always that the last such installment shall be in
the amount necessary to repay in full the principal balance then outstanding.

         Section 3.02. Optional Prepayment. A Co-Borrower may prepay any Advance
made hereunder without premium or penalty in whole or in part on the last day of
any Interest Period for the Advance to be prepaid; provided, that (i) no Default
shall have occurred, and (ii) any prepayment in part be made in a minimum amount
of US$500,000; and provided, further, that outstanding Advances may be prepaid
under this Section 3.02 only in the inverse order of maturity. If a Co-Borrower
wishes to make such a prepayment, it shall give the Lender Notice to that effect
not later than thirty (30) days before the date of the prepayment, specifying
the date on which the prepayment is to be made and the amount to be prepaid.
Such Notice shall constitute such Co-Borrower's irrevocable commitment to prepay
that amount on that date, together with interest accrued on the amount prepaid
to but excluding the prepayment date.

         Section 3.03  Intentionally Left Blank.

         Section 3.04. Changes in Market and Exchange Control. Except with
respect to Advances made to IMPSAT Comunicacoes Ltda., in the event that prior
to the commencement of any Interest Period, the Lender shall have determined
(which determination, in the absence of manifest error, shall be final,
conclusive and binding upon the Co-Borrowers and the Guarantor) that the ability
of the Lender to make or maintain Advances pursuant to Section 2.01 in Dollars
during the ensuing Interest Period has become impractical or has been materially
adversely affected because:

         (a)      of any material adverse change in or the termination of the
London Interbank Eurodollar Market for Dollars;

         (b)      of reasons generally affecting the London Interbank Eurodollar
Market, there exist no adequate and fair means for ascertaining the rate of
interest applicable to the principal indebtedness of the Co-Borrowers to the
Lender constituted by Advances made pursuant to Section 2.01 for such Interest
Period; or

         (c)      of reasons generally affecting the London Interbank Eurodollar
Market, deposits in Dollars are not available to the Lender in the London
Interbank Eurodollar Market in sufficient amounts in the ordinary course of
business for such Interest Period;

then, and in any such case, the Lender shall promptly notify the Co-Borrowers
and the Guarantor of such determination and shall, within the next succeeding 60
days after such notice thereof, deliver to the Co-Borrowers and the Guarantor in
writing the terms of a substitute basis for the continuation of the indebtedness
of the Co-Borrowers and the Guarantor pursuant to Section 2.01 which is,
financially, the substantial equivalent to the Lender of the basis provided
herein, including the funding of such indebtedness in a financial market other
than the London Interbank Eurodollar Market. The terms of the substitute basis
for such indebtedness

MIA1 #1016002.v8                       26                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   34

                                EXECUTION COPY

shall be retroactive to and effective from the beginning of the then current
Interest Period and the provisions of this Agreement respecting such
indebtedness of the Co-Borrowers and the Guarantor, shall be, ipso facto,
amended to accord with the terms of the substitute basis. Notwithstanding
anything to the contrary contained in this Agreement respecting prepayment, in
the event the Lender gives the notice provided for in this Section 3.04, the
Co-Borrowers, collectively but not individually shall have the right, upon
notice to that effect (which notice shall be irrevocable) delivered to the
Lender at least 30 days prior to the next Interest Payment Date, to prepay in
full on such Interest Payment Date the principal indebtedness of the
Co-Borrowers to the Lender pursuant to Section 2.01 together with interest
accrued thereon at the substitute basis and all other sums due hereunder with
respect to such indebtedness to the date of such prepayment. In the event of
such prepayment, the obligation of the Lender to make any further credit
available under Section 2.01 shall, at the Lender's option, thereupon terminate.
If any Co-Borrower does not give such notice and prepay in accordance with the
foregoing, then such Co-Borrower shall execute and deliver to the Lender any and
all further instruments as the Lender deems necessary or advisable to reflect
the substitute basis for the indebtedness of such Co-Borrower to the Lender
pursuant to Section 2.01.

         Section 3.05. Application of Payments. All payments by or for the
account of a Co-Borrower under this Agreement shall be applied first to all
amounts then due and payable other than principal and interest in such order as
the Lender may elect, then to interest due and payable, then to principal due
and payable, and lastly to prepayment of installments of principal in inverse
order of maturity.

         Section 3.06. Place and Manner of Payment. Amounts payable by each
Co-Borrower and the Guarantor hereunder shall be made without set-off or
counterclaim in Dollars to the credit of the Lender not later than 11:00 a.m.
(New York City time) on the day such payment is due and in funds for same day
settlement, at the Lender or at such other account or financial institution as
the Lender may from time to time notify the Co-Borrowers and the Guarantor. Each
Co-Borrower and the Guarantor, as the case may be, shall provide a copy of its
payment instructions (including its transfer reference number), showing how
funds are being transferred, by telefax to the Lender.

         All amounts due under this Agreement shall be payable solely in
Dollars. Each Co-Borrower agrees that, notwithstanding any foreign exchange
restriction or prohibition in the jurisdiction of such Co-Borrower, any and all
payments under this Agreement will be made in Dollars, payable at the location
in Co-Borrower's country as the Lender so requires, and each Co-Borrower shall
take any action necessary to obtain due authorization to meet its obligations
hereunder. If, under such exchange control system, there exists an official
controlled exchange rate and a free market exchange rate, including, in the case
of a free market exchange rate, the possibility or requirement of obtaining
foreign currency through the purchase of bonds, titles of credit, indentures or
any similar document or instrument, such Co-Borrower shall be obliged to
purchase foreign currency in the most expeditious legal manner to meet its

MIA1 #1016002.v8                       27                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   35

                                EXECUTION COPY

obligations hereunder, even if the free market is at a higher exchange rate than
the official controlled exchange rate, and even if the acquisition of such
foreign currency must be, or may be, effected through the purchase of such
bonds, titles of credit, indentures or similar documents or instruments, even at
a higher exchange rate. In the event a Co-Borrower is not able to obtain Dollars
by any other means following the occurrence of any such prohibition or
restriction, such Co-Borrower shall, at its own expense, provide an equal amount
of Dollar-denominated securities of the country of such Co-Borrower that are
liquid and available in the said country's market or any liquid public or
private debt or equity security quoted in Dollars and traded in the United
States markets and the amount shall be such that, when sold in the United States
market, the net proceeds of the sale in the same as the amounts due hereunder.

                                   ARTICLE IV
                               INTEREST; EXPENSES

         Section 4.01. Base Rate and Brazil Rate.

         (a)      Each Co-Borrower other than IMPSAT Comunicacoes Ltda. (Brazil)
shall pay to the Lender or its order interest on the aggregate amount of
Advances to such Co-Borrower and outstanding from time to time at the Base Rate.
IMPSAT Comunicacoes Ltda. (Brazil) shall pay to the Lender or its order interest
on the aggregate amount of Advances to such Co-Borrower and outstanding from
time to time at the Brazil Rate. All interest accrued hereunder shall be
calculated and payable in arrears on each Interest Payment Date. If an Advance
is made within the 30 days before an Interest Payment Date, interest shall be
calculated from the date of the Advance but be paid on such Advance starting
only on the next occurring Interest Payment Date after the Advance is made.
Interest at the Base Rate shall be calculated on the basis of the actual number
of days elapsed divided by 360; the actual yearly rate of interest equivalent to
each of the rates determined as above and calculated in such manners is such
rate multiplied by the actual number of days in the year divided by 360.
Interest at the Brazil Rate shall be calculated on the actual number of days
elapsed (including the first day but not including the last day of each Interest
Period).

         (b)      The Lender shall give Notice to each Co-Borrower subject to
the Base Rate of LIBOR for each Interest Period after each determination
thereof.

         (c)      Except as otherwise expressly provided herein, accrued
interest on each Advance made hereunder shall be payable on each Interest
Payment Date with respect to such Advance.

         Section 4.02. Interest on Amounts in Default. If a Co-Borrower fails to
pay any amount when due and payable hereunder, such Co-Borrower shall pay
interest on such amount at an interest rate equal to the Default Rate. Such
interest shall accrue from the date of Default for so long as such Default shall
continue, and shall be payable on demand and compounded on

MIA1 #1016002.v8                       28                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   36

                                EXECUTION COPY

each Interest Payment Date, before and after demand and judgment until paid. For
Loans in which interest has been accruing at the Base Rate, interest at the
Default Rate shall be calculated on the basis of the actual number of days
elapsed divided by 360; the actual yearly rate of interest to which the said
rate so calculated is equivalent is the said rate multiplied by the actual
number of days in the year divided by 360. For Loans in which interest has been
accruing at the Brazil Rate, interest at the Default Rate shall be calculated on
the basis of the actual number of days elapsed (including the first day but not
including the last day of the relevant Interest Period).

         Section 4.03. Fees and Initial Expenses. The Co-Borrowers shall pay to
the Lender the Administrative Fee, which shall be non-refundable, on the date
hereof. The Co-Borrowers shall pay to the Lender the Commitment Fee on the due
dates therefor. The Co-Borrowers shall reimburse the Lender on a date not later
than the earlier of (i) the Initial Borrowing Date, or (ii) the thirtieth (30th)
day following the date of execution of this Agreement, for all reasonable and
documented expenses incurred by the Lender in connection with the negotiation,
preparation, execution, delivery and administration of the Credit Documentation
and any amendment or waiver with respect thereto. All documents or information
to be furnished to the Lender by the Co-Borrowers and the Guarantor shall be
supplied at the expense of the Co-Borrowers and the Guarantor. The Co-Borrowers
and the Guarantor shall pay, within 30 days of the Lender's billing therefor,
the reasonable and documented fees and expenses of independent legal counsel for
the Lender and all other costs and expenses incurred by the Lender in connection
with this Agreement, including without limitation, (x) the negotiation,
preparation, execution, and delivery of this Agreement in an amount not to
exceed US$225,000 and (y) any amendments or waivers with respect to this
Agreement.

         Section 4.04. Enforcement Expenses. Each Co-Borrower shall promptly
reimburse the Lender for all reasonable out-of-pocket expenses incurred by the
Lender (including, without limitation, the reasonable fees, disbursements and
other charges of counsel to the Lender) in connection with the preservation or
enforcement of any right of the Lender under the Credit Documentation.

                                    ARTICLE V
                                      TAXES

         Section 5.01. Taxes.

         (a)      Any and all payments by the Co-Borrowers or the Guarantor
under this Agreement, the Guaranty Agreement or the Notes (including, without
limitation, payments with respect to the Advances) shall be made free and clear
of and without deduction for any and all present and future taxes, levies,
duties, imposts, deductions, charges, fees or withholdings, and all interest,
penalties and other liabilities with respect thereto, imposed by any
Governmental Authority of Argentina, Brazil, Colombia, Ecuador, Venezuela, or
any

MIA1 #1016002.v8                       29                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   37

                                EXECUTION COPY

other Governmental Authority pertaining to any jurisdiction from or through
which any payment is made hereunder or under the Notes, the Guaranty or the
Security Documents, other than income or franchise taxes imposed on the Lender
by the laws of the jurisdiction in which it is resident or organized
(collectively, "Taxes").

         (b)      If any Taxes shall be required by law to be deducted from or
in respect of any sum payable under this Agreement, the Guaranty Agreement or
any Note to the Lender, then (i) the sum payable by such Co-Borrower or the
Guarantor shall be increased as may be necessary so that after making all
required deductions, the Lender shall receive an amount equal to the sum it
would have received had no such deductions been made, (ii) such Co-Borrower or
the Guarantor, as the case may be, shall make such deductions and (iii) such
Co-Borrower or the Guarantor, as the case may be, shall pay the full amount
deducted to the relevant taxing authority in accordance with Applicable Law.

         Section 5.02. Receipt of Payment. Within thirty (30) days after the
date of any payment of Taxes withheld by a Co-Borrower in respect of any payment
to the Lender, such Co-Borrower shall furnish to the Lender the original or a
certified copy of a receipt evidencing payment thereof.

         Section 5.03. Other Taxes. Each Co-Borrower and the Guarantor shall pay
any Taxes that may be imposed by any Governmental Authority (other than Canada)
in connection with the execution, delivery or registration of this Agreement,
the Guaranty Agreement or the Notes issued hereunder or the filing,
registration, recording or perfecting of any security interest contemplated by
this Agreement or the Security Documents.

         Section 5.04. Indemnification. If the Lender pays any Taxes that a
Co-Borrower or the Guarantor is required to pay pursuant to this Article V, such
Co-Borrower or the Guarantor shall indemnify the Lender on demand in full in the
currency in which such Taxes are paid, whether or not such Taxes were correctly
or legally asserted, together with interest thereon from and including the date
of payment to, but excluding, the date of reimbursement at the Default Rate.

                                   ARTICLE VI
                                    THE NOTES

         Section 6.01. Grid Notes. Each Co-Borrower agrees that to evidence
further its obligation to repay all Advances with interest accrued thereon, it
shall not later than the Initial Borrowing Date hereunder issue and deliver to
the Lender, in accordance with the written instructions of the Lender, one Grid
Note. Each Grid Note shall be valid and enforceable as to its principal amount
at any time only to the extent of the aggregate amounts then disbursed and
outstanding under the Loans, and, as to interest, only to the extent of the
interest accrued

MIA1 #1016002.v8                       30                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   38

                                EXECUTION COPY

thereon. Any notations by the Lender on any Grid Note regarding payments made on
account of the principal thereof, in absence of manifest error, shall be
conclusive and binding.

         Section 6.02. Definitive Notes. No later than ten (10) days after the
expiration of the Availability Period, each Co-Borrower shall issue and deliver
to the Lender the following: (a) a series of seven (7) Definitive Notes in
exchange for the Grid Note previously issued and delivered in accordance with
Section 6.01, whereupon the Lender shall surrender such previously issued Grid
Note for cancellation to such Co-Borrower, and (b) a legal opinion of counsel in
such Co-Borrower's country confirming the statements under the opinion
originally delivered to the Lender pursuant to Section 7.01(d)(i) or 7.02(g), as
the case may be. The principal aggregate amount of such Definitive Notes shall
equal the principal amount of the Loans then advanced to such Co-Borrower under
this Facility.

         Section 6.03. Note Exchanges. If requested by the Lender pursuant to
the sale of the Loans to any Person, a Co-Borrower shall issue and deliver to
the Lender a new series of Definitive Notes or series of promissory notes, for
which each such promissory note in such series shall be issued in a principal
amount equal to an installment of principal remaining under the relevant Loan
and otherwise be substantially in the form of the Definitive Notes previously
issued and delivered in accordance with this Agreement, whereupon the Lender
shall surrender such previously issued Definitive Notes for cancellation to such
Co-Borrower.

         Section 6.04. Replacement Notes. To the fullest extent permitted by
Applicable Law, if any Note is mutilated, lost, stolen or destroyed, the
respective Co-Borrower shall issue and deliver a new Note of the same date,
maturity and denomination as the Note so mutilated, lost, stolen or destroyed;
provided that, in the case of any mutilated Note, such mutilated Note shall be
returned to the respective Co-Borrower after examination by the Lender, and, in
the case of any lost, stolen or destroyed Note, the respective Co-Borrower shall
have first received evidence of such loss, theft or destruction and an
Indemnity.

         Section 6.05. Notes Under Alternative Financing for IMPSAT Comunicacoes
Ltda. (Brazil). The Lender may request an exchange of Notes previously issued by
IMPSAT Comunicacoes Ltda. (Brazil) for promissory notes issued in accordance
with the financing established pursuant to the terms of Section 15.21. IMPSAT
Comunicacoes Ltda. (Brazil) hereby agrees to effect such exchange of Notes upon
the receipt of the Lender's request therefor.

                                   ARTICLE VII
                              CONDITIONS PRECEDENT

         Section 7.01. Conditions Precedent to the Closing Advance. Upon the
fulfillment of each of the conditions in Sections 7.01 and 7.04 prior to the
Initial Borrowing Date to the reasonable satisfaction of the Lender, the Lender
shall make an initial Advance to those Co-

MIA1 #1016002.v8                       31                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   39

                                EXECUTION COPY

Borrowers for which Purchase Order(s) or Brazil Notice(s) of Borrowing, as the
case may be, are made available to the Lender on the Initial Borrowing Date (the
"Closing Advance") in an aggregate amount not to exceed the Closing Advance
Amount on the Initial Borrowing Date:

         (a)      Each Co-Borrower and the Guarantor shall have executed and
delivered to the Lender this Master Loan Agreement;

         (b)      Each Co-Borrower requesting a Closing Advance shall provide
the Lender with Purchase Order(s), or a Brazil Notice of Borrowing, as the case
may be, in an aggregate amount not to exceed the Closing Advance Amount;

         (c)      Each Co-Borrower shall have executed and delivered to the
Lender a Grid Note dated as of the Initial Borrowing Date, and the Guarantor
shall have executed and delivered to the Lender the Guaranty Agreement;

         (d)      The Lender shall have received on or before the second Banking
Day preceding the Initial Borrowing Date an executed copy, in each case
acceptable to the Lender, of (i) opinions of counsel to each Co-Borrower
requesting a Closing Advance in such Co-Borrower's country, dated as of the date
of its delivery, substantially in the form set forth in Exhibit F hereto; (ii)
an opinion of New York counsel to the Guarantor and the Co-Borrowers, dated as
of the date of its delivery, substantially in the form set forth in Exhibit G
hereto; and (iii) evidence of the irrevocable appointment by each Co-Borrower
and the Guarantor of the Process Agent;

         (e)      Each Co-Borrower requesting a Closing Advance and the
Guarantor shall have delivered to the Lender copies of all Licenses to which
such Co-Borrower is a party or under which such Co-Borrower is bound, and copies
of all Governmental Approvals, together with a certificate that is approved by
the Lender and substantially in the form set forth in Exhibit D (as to such
Co-Borrower) and Exhibit E (as to the Guarantor) signed by a duly authorized
officer of such Co-Borrower or the Guarantor, as the case may be, certifying
that such Licenses and Governmental Approvals are in full force and effect and
further certifying that (i) no event shall have occurred and be continuing that
constitutes a Default or an Event of Default, or a default by any Co-Borrower
under the Supply Contract(s) (if said Supply Contract(s) is in full force and
effect) and no such event will occur or will have occurred by reason of such
Advance, (ii) the representations and warranties provided in Article IX hereof
shall be true and correct in all material respects, (iii) no Material Adverse
Change shall have occurred since the date of the latest financial statements
provided to the Lender by such Co-Borrower and the Guarantor under Section 10.02
hereof, and (iv) upon its execution, the Supply Contract(s) shall be and
continue to remain in full force and effect;

         (f)      Each Co-Borrower requesting a Closing Advance and the
Guarantor shall have delivered to the Lender evidence that such Co-Borrower is
covered by the insurance policies

MIA1 #1016002.v8                       32                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   40

                                EXECUTION COPY

described in Section 9.01(n) and the Guarantor is covered by the insurance
policies described in Section 9.02(j), all in form and substance reasonably
satisfactory to the Lender, and that all such insurance policies are in full
force and effect;

         (g)      Each Co-Borrower requesting a Closing Advance and the
Guarantor shall have delivered to the Lender (i) copies of any agreements among
such Co-Borrower's or the Guarantor's shareholders; (ii) copies of the
Organization Documents of such Co-Borrower and the Guarantor; and (iii) evidence
of authority (with specimen signatures) of each Person authorized by such
Co-Borrower and the Guarantor to execute and deliver this Agreement, the Notes,
and such other documentation as may be required hereunder or by the Lender;

         (h)      The Guarantor shall have delivered to the Lender a copy of its
Annual Report on Form 10-K under the Exchange Act for the year ended December
31, 2000; and

         (i)      All fees, expenses and other amounts due and payable to the
Lender on or before the Initial Borrowing Date shall have been paid, including
all amounts due under Section 4.03.

         Section 7.02. Conditions Precedent to the First Advance. If, as applied
to each Co-Borrower individually, such Co-Borrower did not receive a Closing
Advance pursuant to Section 7.01, the Lender shall make an Advance to such
Co-Borrower (as applied to such Co-Borrower individually, a "First Advance")
upon the fulfillment of each of the conditions in Sections 7.02 and 7.04 by such
Co-Borrower, to the reasonable satisfaction of the Lender:

         (a)      Prior to making any First Advance, each Co-Borrower requesting
a First Advance and the Guarantor shall have executed and delivered to the
Lender this Master Loan Agreement, each Co-Borrower shall have executed and
delivered to the Lender a Grid Note dated as of the Initial Borrowing Date, the
Guarantor shall have executed and delivered to the Lender the Guaranty
Agreement, and each Co-Borrower and the Guarantor shall have provided Lender
with evidence of the irrevocable appointment by each Co-Borrower and the
Guarantor of the Process Agent;

         (b)      Each Co-Borrower requesting a First Advance shall provide the
Lender with a Purchase Order(s), a request for reimbursement for Import Duties
or, with respect to Advances to IMPSAT Comunicacoes Ltda. (Brazil), a Brazil
Notice of Borrowing;

         (c)      Each Co-Borrower requesting a First Advance shall have
delivered to the Lender copies of all Licenses to which such Co-Borrower is a
party or under which such Co-Borrower is bound, and copies of all Governmental
Approvals, together with a certificate that is approved by the Lender and
substantially in the form set forth in Exhibit D (as to such Co-Borrower) signed
by a duly authorized officer of such Co-Borrower, certifying that such Licenses
and Governmental Approvals are in full force and effect and further certifying
that (i) no event shall have occurred and be continuing that constitutes a
Default or an Event of

MIA1 #1016002.v8                       33                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   41

                                EXECUTION COPY

Default, or a default by any Co-Borrower under the Supply Contract(s) (if said
Supply Contract(s) is in full force and effect) and no such event will occur or
will have occurred by reason of such Advance, (ii) the representations and
warranties provided in Article IX hereof shall be true and correct in all
material respects, (iii) no Material Adverse Change shall have occurred since
the date of the latest financial statements provided to the Lender by such
Co-Borrower and the Guarantor under Section 10.02 hereof, and (iv) upon its
execution, the Supply Contract(s) shall be and continue to remain in full force
and effect;

         (d)      Each Co-Borrower requesting a First Advance shall have
delivered to the Lender evidence that such Co-Borrower is covered by the
insurance policies described in Section 9.01(n), all in form and substance
reasonably satisfactory to the Lender, and that all such insurance policies are
in full force and effect;

         (e)      Each Co-Borrower requesting a First Advance shall have
delivered to the Lender (i) copies of any agreements among such Co-Borrower's or
the Guarantor's shareholders; (ii) copies of the Organization Documents of such
Co-Borrower; and (iii) evidence of authority (with specimen signatures) of each
Person authorized by such Co-Borrower to execute and deliver this Agreement, the
Notes, and such other documentation as may be required hereunder or by the
Lender;

         (f)      Each Co-Borrower shall have acknowledged to the Lender in a
writing signed by an authorized officer of such Co-Borrower that, upon receipt
of Goods and Services, such Co-Borrower shall execute and deliver Security
Documents to the Lender in accordance with Section 10.12 for the purpose of
filing, recording and the performance of such other actions, including due
registration, that are necessary in order to establish, protect, preserve and
perfect the Lender's security interest in the Collateral of such Co-Borrower to
be provided in such Security Documents therefor as valid and perfected first
priority security interests with respect to such Collateral to be financed
through all Advances made hereunder;

         (g)      Opinions of counsel to each Co-Borrower in such Co-Borrower's
country, in each case dated as of the date of its delivery and in substantially
the form set forth in Exhibit F hereto, and approved by the Lender;

         (h)      With respect to Security Documents which shall have been
delivered to the Lender pursuant to Section 10.12 corresponding to a Closing
Advance, opinions from the Lender's Local Counsel, in form and substance
satisfactory to the Lender, relating to the Security Documents for each
Co-Borrower and the security interests created thereunder;

         (i)      The Guarantor shall have delivered to the Lender a certificate
confirming that (i) the Guaranty Agreement is and continues to remain in full
force and effect with respect to Advances made prior to such First Advance, and
with respect to all Advances made pursuant to this Agreement, (ii) the
transactions contemplated in Section 7.02 do not and shall not

MIA1 #1016002.v8                       34                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   42

                                EXECUTION COPY

constitute a novation, release of, or waiver of any obligation of the Guarantor
under this Agreement or the Guaranty Agreement, (iii) the Supply Contract(s) is
in full force and effect, and (iv) the certifications provided pursuant to
Section 7.01(e) are and continue to remain true and correct in all material
respects as if such certifications were made on the date of such First Advance;

         (j)      All fees, expenses and other amounts due and payable to the
Lender on or before the date of the requested First Advance, as the case may be,
shall have been paid, including all amounts due under Section 4.03; and

         (k)      The Lender shall have received such Supplemental Documentation
as the Lender may reasonably request.

         Section 7.03. Conditions Precedent to the Second Advance. If, as
applied to each Co-Borrower individually, such Co-Borrower previously received a
Closing Advance, the Lender shall make an Advance to such Co-Borrower (as
applied to such Co-Borrower individually, a "Second Advance") upon the
fulfillment of each of the conditions in Sections 7.03 and 7.04 by such
Co-Borrower, to the reasonable satisfaction of the Lender:

         (a)      Each Co-Borrower requesting a Second Advance shall provide the
Lender with a Purchase Order(s), a request for reimbursement for Import Duties
or, with respect to Advances to IMPSAT Comunicacoes Ltda. (Brazil), a Brazil
Notice of Borrowing;

         (b)      With respect to Co-Borrower's receiving a Closing Advance
under Section 7.01, all filings, recordings and other actions that are necessary
in order to establish, protect, preserve and perfect the Lender's security
interest in the Collateral of each Co-Borrower as provided in the Security
Documents therefor as valid and perfected first priority security interests with
respect to such Collateral, financed through such Advances shall have been duly
registered;

         (c)      (i) In respect of Collateral under Section 7.03(b), an opinion
of counsel to the Co-Borrower in such Co-Borrower's country, dated as of the
date of its delivery, confirming that the Security Documents applicable to such
Co-Borrower are in full force and effect and that the Security Documents create
a first priority security interest for the Lender with respect to the
Collateral, and (ii) opinions of counsel to the Co-Borrower in such
Co-Borrower's country, in each case dated as of the date of its delivery,
confirming that all statements set forth in each opinion originally submitted
pursuant to Section 7.01(d) continues to remain in full force and effect as if
such statements were made on the date of such Second Advance;

         (d)      With respect to Security Documents which shall have been
delivered to the Lender pursuant to Section 10.12 corresponding to a First
Advance, opinions from the Lender's Local Counsel, in form and substance
satisfactory to the Lender, relating to the Security Documents for each
Co-Borrower and the security interests created thereunder;

MIA1 #1016002.v8                       35                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   43

                                EXECUTION COPY

         (e)      Each Co-Borrower requesting a Second Advance shall have
delivered to the Lender a certificate confirming that the certifications
provided pursuant to Section 7.01(e) are and continue to remain true and correct
in all material respects as if such certifications were made on the date of such
Second Advance;

         (f)      The Guarantor shall have delivered to the Lender a certificate
confirming that (i) the Guaranty Agreement is and continues to remain in full
force and effect with respect to Advances made prior to such Second Advance, and
with respect to all Advances made pursuant to this Agreement, (ii) the
transactions contemplated in Section 7.03 do not and shall not constitute a
novation, release of, or waiver of any obligation of the Guarantor under this
Agreement or the Guaranty Agreement, (iii) the Supply Contract(s) is in full
force and effect, and (iv) the certifications provided pursuant to Section
7.01(e) are and continue to remain true and correct in all material respects as
if such certifications were made on the date of such Second Advance;

         (g)      All fees, expenses and other amounts due and payable to the
Lender on or before the date of the requested Second Advance, as the case may
be, shall have been paid, including all amounts due under Section 4.03; and

         (h)      The Lender shall have received such Supplemental Documentation
as the Lender may reasonably request.

         Section 7.04. Conditions Precedent to Each Advance. The obligation of
the Lender to make each Advance to a Co-Borrower hereunder (including Advances
to such Co-Borrower made in accordance with the conditions set forth in Sections
7.01, 7.02 and 7.03) is subject to the fulfillment, to the reasonable
satisfaction of the Lender, of the following conditions precedent that, at the
time of the making of such Advance:

         (a)      No event shall have occurred and be continuing that
constitutes a Default or an Event of Default, or a default by any Co-Borrower
under the Supply Contract(s) or any Purchase Order, and no such event will occur
or will have occurred by reason of such Advance;

         (b)      The representations and warranties provided in Article IX
hereof shall be true and correct in all material respects;

         (c)      No Material Adverse Change shall have occurred since the date
of the latest financial statements provided to the Lender by each Co-Borrower
and the Guarantor under Section 10.02 hereof;

         (d)      The Lender shall have received such Supplemental Documentation
as the Lender may reasonably request;

MIA1 #1016002.v8                       36                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   44

                                EXECUTION COPY

         (e)      The Supply Contract(s) and the Security Documents shall be in
full force and effect as of the date of their respective execution and
thereafter;

         (f)      All filings, recordings and other actions taken in order to
establish, protect, preserve and perfect the Lender's security interest in the
Collateral delivered to each Co-Borrower to date as provided in the Security
Documents therefor as valid and perfected first priority security interests with
respect to such Collateral shall have been duly registered and such registration
is and continues to remain in full force and effect;

         (g)      Each Co-Borrower shall have provided the Lender with
Acknowledgments of Advances for all prior Advances in accordance with Section
2.07.

         (h)      With respect to Advances to IMPSAT Comunicacoes Ltda.
(Brazil), such Co-Borrower shall have provided the Lender with a Brazil Notice
of Borrowing in accordance with Section 2.08;

         (i)      All fees, expenses and other amounts due and payable to the
Lender on or before the date of the requested Advance shall have been paid,
including all amounts due under Section 4.03; and

         (j)      With respect to Advances to IMPSAT Comunicacoes Ltda.
(Brazil), IMPSAT Comunicacoes Ltda. (Brazil) shall have delivered to the Lender
evidence of the Registry of Financial Operations (Registro de Operacoes
Financeiras- ROF) of the Central Bank of Brazil allowing the entry of the
Advance into Brazil.

         Section 7.05 Waiver of Condition Precedent. The conditions in Sections
7.01, 7.02, 7.03, and 7.04 are for the benefit of the Lender only and may be
waived by the Lender, in whole or in part, and with or without conditions, for
any Advance, without affecting the Lender's right to require that such
conditions be satisfied for any other Advance or Advances.

                                  ARTICLE VIII
                                   COLLATERAL

         Section 8.01. Security Documents. As security for its Obligations, each
Co-Borrower hereby grants to the Lender a continuing first priority security
interest in, lien on and right of set-off against, and hereby assigns to the
Lender as security, the Collateral, whether now owned or hereafter acquired (to
the extent permitted by the law of the jurisdiction where the Collateral will be
located) or existing and wherever located, described in the respective Security
Documents on the terms and conditions set forth therein.

         Section 8.02. Further Documents. Each Co-Borrower agrees to execute and
deliver, or cause to be executed and delivered, to the Lender such confirmatory
or supplementary agreements, and such notices or other documents, instruments or
agreements as the Lender

MIA1 #1016002.v8                       37                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   45

                                EXECUTION COPY

may request which are in the Lender's judgment necessary under the law of the
respective Co-Borrower's country or under any other Applicable Law in order to
obtain for the Lender the benefit of the relevant Security Documents.

                                   ARTICLE IX
                         REPRESENTATIONS AND WARRANTIES

         Section 9.01. Representations and Warranties of each Co-Borrower. Each
Co-Borrower, as to itself, makes the representations and warranties set forth
below to the Lender as of the Initial Borrowing Date and the date of each
Advance, except to the extent any of such representations and warranties
specifically relate to an earlier date. All of the representations and
warranties under this Article IX shall survive the Initial Borrowing Date and
the making of Advances and remain in effect until all amounts hereunder have
been fully paid:

         (a)      Organization. The Co-Borrower is a sociedad anonima (or in the
case of IMPSAT Comunicacoes Ltda. (Brazil), a sociedade por quotas de
responsabilidade limitada) duly organized and validly existing under the laws of
the jurisdiction of its organization and has the power and authority (including
any required license, permit or other approval from any Governmental Authority)
to own its property, to conduct its business as currently conducted and to
consummate the transactions contemplated in, and to perform its obligations
under, this Agreement, the Notes and the Security Documents. The Co-Borrower has
paid all fees and taxes required to be paid by it under the law of its
Co-Borrower's country in order to maintain its valid existence and organization,
and is adequately capitalized under the requirements of the law of its
Co-Borrower's country.

         (b)      Due Authorization. The Co-Borrower has taken all necessary
action to authorize the execution and delivery of this Agreement, the Notes and
the Security Documents and all other documents to be executed and delivered by
it in connection with this Agreement or the Security Documents, and the
performance of its obligations under this Agreement, the Security Documents and
the Notes, and the consummation of the transactions contemplated in this
Agreement and the Security Documents.

         (c)      Authority and Consents.

                  (i)      The execution, delivery and performance by the
Co-Borrower of the Agreement, the Notes and the Security Documents to which it
is or will be a party, and the transactions contemplated by the Agreement, the
Notes and the Security Documents: (A) have been duly authorized by all necessary
corporate action (including any necessary shareholder or quotaholder action);
(B) will not breach, contravene, violate, conflict with or constitute a default
under (I) any of its Organization Documents, (II) any applicable legal
requirement to which it is subject or (III) any Contract, loan, agreement,
indenture, mortgage, lease or other instrument or requirement to which it is a
party or by which it or any of its properties may be

MIA1 #1016002.v8                       38                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   46

                                EXECUTION COPY

bound or affected, including all Licenses; and (C) except for the Liens created
by the Security Documents, will not result in or require the creation or
imposition of any Lien upon or with respect to any of the Co-Borrower's
properties.

                  (ii)     Each of (A) the Agreement has been duly executed and
delivered by the Co-Borrower, and (B) the Security Documents and the Notes, when
executed and delivered by each of the respective parties thereto, will be the
legal, valid and binding obligation of the Co-Borrower, enforceable against such
Co-Borrower in accordance with its terms.

                  (iii)    No authorization, consent or approval of, or notice
to or filing with any Governmental Authority or any other Person has been, is or
will be required to be obtained or made (A) for the due execution, delivery,
recordation, filing or performance by the Co-Borrower of this Agreement, the
Notes and the Security Documents to which it is a party or any transaction
contemplated by the Agreement, the Notes and the Security Documents, (B) for the
grant by the Co-Borrower, or the perfection and maintenance, of the Liens
contemplated by the Security Documents (including the first priority nature
thereof) or (C) for the exercise by the Lender of any of its rights under any of
the Agreement, the Notes or the Security Documents or any remedies in respect of
the Collateral pursuant to the Security Documents, except for the Licenses,
authorizations, consents, approvals, notices and filings as have been disclosed
to the Lender by each Co-Borrower or to be disclosed to the Lender pursuant to
Section 7.01 or 7.02, as the case may be ("Governmental Approvals"); all of
which have been duly obtained, taken, given or made and are in full force and
effect.

         (d)      Enforceability. This Agreement has been duly executed and
delivered by each Co-Borrower and constitutes, and the Note, when duly executed
and delivered by such Co-Borrower, will constitute, a valid and binding
obligation of such Co-Borrower, enforceable against such Co-Borrower in
accordance with its terms, subject to applicable bankruptcy, insolvency,
moratorium and similar laws affecting creditors' rights generally, and subject,
as to enforceability, to general principles of equity (regardless of whether
enforcement is sought in a proceeding in equity or at law).

         (e)      Litigation. There are no actions, proceedings or claims
pending or, to the knowledge of the Co-Borrower, threatened, the adverse
determination of which might have a Material Adverse Effect or affect the
validity or enforceability of, this Agreement, the Security Documents or the
Notes.

         (f)      No Default. No Default, Event of Default or default under any
agreement or instrument evidencing any Indebtedness of the Co-Borrower or any of
its Subsidiaries which would permit the acceleration of such Indebtedness is
occurring and continuing, and no such event will occur upon the making of the
Loan.

MIA1 #1016002.v8                       39                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   47

                                EXECUTION COPY

         (g)      Security Interests. The Security Documents, upon their
registration with appropriate Governmental Authorities, will provide the Lender
with effective, valid, legally binding and enforceable first priority Liens on
all Collateral. The security interests described above will be, as of the
respective dates of registration of such Security Documents with the appropriate
Governmental Authorities, superior and prior to the rights of all third Persons
in the Collateral described under each Security Documents so delivered and
registered then existing or thereafter arising by way of mortgage, Lien,
security interest, encumbrance, assignment or otherwise.

         (h)      Financial Condition.

                  (i)      Each Co-Borrower has delivered to the Lender the
following financial statements for such Co-Borrower and its Subsidiaries, each
of which has been certified by the principal financial officer of such
Co-Borrower: the audited financial statements of such Co-Borrower and its
Subsidiaries, as at and for the fiscal year ended on December 31, 2000, prepared
in accordance with GAAP, together with the opinion of such Co-Borrower's
accountants with respect thereto. Such financial statements are complete and
correct in all material respects and fairly present the financial condition of
such Co-Borrower and its Subsidiaries as at such dates and the results of their
operations for the periods ended on such dates.

                  (ii)     Except for Indebtedness hereunder and Indebtedness
listed under Exhibit J and as reflected in the financial statements delivered
pursuant to Section 9.01(h)(i), as of the date hereof, neither the Co-Borrower
nor any of its Subsidiaries has any material contingent obligation, liability
for Taxes, long-term commitment or outstanding Indebtedness of any kind that are
required by GAAP to be included in the financial statements required to be
delivered pursuant to Section 10.02 of such Co-Borrower or Subsidiary, as the
case may be.

                  (iii)    Since December 31, 2000, (x) no event or condition
has occurred which could reasonably be expected to constitute a Material Adverse
Change, and (y) except as disclosed to the Lender by each Co-Borrower on the
date hereof or to be disclosed to the Lender pursuant to Section 7.01 or 7.02,
as the case may be, no Restricted Payment has been declared or paid by any
Co-Borrower or any of their respective Subsidiaries.

         (i)      Impsat Indentures. None of the Impsat Indentures has been
amended or modified as to its amount, terms or maturity date.

         (j)      Business of the Co-Borrower and its Subsidiaries. As of the
Initial Borrowing Date, neither the Co-Borrower nor any of its Subsidiaries has
conducted any business other than the Telecommunications Business.

         (k)      Capitalization. Exhibit M contains a true and complete list of
all of the authorized and outstanding Capital Stock of the Co-Borrower and each
of its Subsidiaries by

MIA1 #1016002.v8                       40                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   48

                                EXECUTION COPY

class, all commitments by the shareholders thereof to make capital contributions
to the Co-Borrower and all capital contributions made by the shareholders to the
Co-Borrower. All of the Capital Stock of the Co-Borrower and each of its
Subsidiaries has been duly authorized and validly issued and is fully paid and
nonassessable. None of such Capital Stock has been issued in violation of any
law to which the Co-Borrower is subject. Except as disclosed to the Lender by
the Co-Borrower in accordance with this Section 9.01(k), neither the Co-Borrower
nor any of its Subsidiaries is a party or subject to, has issued or outstanding
or is bound by, any subscriptions, options, warrants, calls, agreements,
preemptive rights, acquisition rights, redemption rights or any other rights or
claims of any character that restrict the transfer of, require the issuance of,
or otherwise relate to any shares of its Capital Stock. The Capital Stock of the
Co-Borrower and each of its Subsidiaries is owned beneficially and of record by
the Persons disclosed, or to be disclosed, to the Lender by such Co-Borrower in
accordance with this Section 9.01(k). The ownership of such Capital Stock by
such Persons complies with all legal requirements of the Co-Borrower's country.
As of the Initial Borrowing Date, there is no Lien on any of the Capital Stock
of the Co-Borrower or any of its Subsidiaries owned by the Guarantor.

         (l)      Indebtedness. Except for Permitted Indebtedness and as set
forth on Exhibit J, as of March 31, 2001, neither the Co-Borrower nor any of its
Subsidiaries has any Indebtedness of any nature, whether due or to become due,
absolute, contingent or otherwise.

         (m)      Taxes and Reports. All Tax returns, reports and statements of
the Co-Borrower and each of its Subsidiaries required by Applicable Law to be
filed with any Governmental Authority have been duly and properly filed, which
returns, reports and statements are complete and accurate in all material
respects. All Taxes due or anticipated to become due in respect of the
Co-Borrower and each of its Subsidiaries, or any of their respective properties,
incomes or franchises, have been duly paid by, or have been adequately provided
for or reserved against on the books of the Co-Borrower or such Subsidiary. In
addition, no Liens have been filed, and no claims are being asserted, or, to the
best knowledge of the Co-Borrower, threatened, with respect to any such Taxes.

         (n)      Insurance. Such Co-Borrower has acquired adequate insurance
policies with financially sound and reputable insurers in such amounts and
against such risks as is customary for those Persons engaged in the same type or
types of business as such Co-Borrower, such policies being in full force and
effect as of the date of this Agreement, and there being no delinquencies in the
payment of any premium for such policies.

         (o)      Taxes. The execution and delivery of this Agreement, the Note
and the Security Documents (and the recording and perfecting of the security
interest created thereunder) are not subject to any Taxes.

MIA1 #1016002.v8                       41                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   49

                                EXECUTION COPY

         (p)      Status of Obligations. Each of the Co-Borrower and its
Subsidiaries (x) has good title to its property free and clear of all Liens, and
(y) represents and warrants that its respective obligations under this Agreement
rank, and its obligations under the Note will rank, at least pari passu with all
its other Indebtedness; except with respect to Permitted Liens and the Liens set
forth in Exhibit K, for each of clauses (x) and (y) of this paragraph 9.01(p).

         (q)      Compliance with Contracts. With respect to each agreement,
contract, lease, purchase and sale order, commitment, license and other
arrangement (each a "Contract") that is material to the business of the
Co-Borrower or any of its Subsidiaries, (i) each such Contract is a valid and
binding agreement of the Co-Borrower and, to the best of the Co-Borrower's
knowledge, of the other party or parties thereto, and each such Contract is in
full force and effect in all material respects, and (ii) the Co-Borrower or its
Subsidiary (as the case may be) is in compliance with each such Contract and has
no knowledge of any default under any such Contract which default has not been
cured or waived and which default would reasonably be expected to have a
Material Adverse Effect or affect the validity or enforceability of, this
Agreement, the Notes or the Security Documents.

         (r)      Disclosure. All historical information supplied to the Lender
by or on behalf of the Co-Borrower pursuant to this Agreement has been, and is,
true, accurate and complete in all material respects. All future projections and
forward-looking statements provided to the Lender including (but not limited to)
the future projections and forward-looking statements contained in the base-case
Business Plan for such Co-Borrower, attached as Exhibit H hereto, are based upon
good faith judgment and reasonable assumptions of such Co-Borrower. All
representations and warranties made by such Co-Borrower in all of the Credit
Documentation to which it is a party are true and complete in all material
respects on and as of the date hereof (or such later date as this representation
is deemed made pursuant to the terms hereof).

         (s)      Material Adverse Change. There has been no Material Adverse
Change since December 31, 2000.

         (t)      Subsidiaries. Each Co-Borrower has disclosed to the Lender a
complete list of each Subsidiary of the Co-Borrower. Each such Subsidiary is a
Wholly Owned Subsidiary of such Co-Borrower, is an entity duly organized and
validly existing under the laws of its jurisdiction of organization, and has all
corporate powers and all governmental licenses, authorizations, consents and
approvals required to carry on its business as presently conducted.

         (u)      Immunity. The borrowing by the Co-Borrower under this
Agreement and the execution, delivery and performance of this Agreement, the
Notes and the Security Documents by the Co-Borrower constitute private and
commercial acts rather than public or governmental acts. Under the laws of the
Co-Borrower's country, the Co-Borrower is not entitled to any immunity,
sovereign or otherwise, from any action or proceeding in connection with this
Agreement, the Note or the Security Documents.

MIA1 #1016002.v8                       42                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   50

                                EXECUTION COPY

         (v)      Withholding Taxes. Payments (other than in respect of
principal on the Advances) made by a Co-Borrower under this Agreement and the
Note to a resident of a country other than such Co-Borrower's country will be
subject to withholding tax at an effective rate not exceeding the rates
disclosed to the Lender or to be disclosed to the Lender pursuant to Section
7.01 or 7.02, as the case may be, unless a treaty applies that will exempt the
imposition of such tax.

         (w)      Investments. Any investment held by the Co-Borrower and each
of its Subsidiaries are disclosed in the financial statements provided to the
Lender pursuant to Section 10.02 to the extent required by GAAP to be disclosed.

         (x)      Licenses; Governmental Approvals. Each Co-Borrower has
disclosed, or shall disclose, to the Lender pursuant to Section 7.01 or 7.02, as
the case may be, a complete and accurate list of all Licenses and Governmental
Approvals necessary for the implementation of the Facility (including, but not
limited to, all such approvals necessary for the payment of amounts due
hereunder in Dollars) and the conduct of the business of the Co-Borrower and
each of its Subsidiaries.

         (y)      Compliance with Laws. The Co-Borrower and each of its
Subsidiaries is conducting its business in compliance in all material respects
with all Applicable Laws of the Co-Borrower's country, all Governmental
Approvals, Licenses and its Organization Documents.

         (z)      Intellectual Property. The Co-Borrower and each of its
Subsidiaries owns or has the right to use all patents, trademarks, permits,
service marks, trade names, copyrights, franchises, formulas, licenses and other
rights with respect thereto, and has obtained assignment of all licenses and
other rights of whatsoever nature necessary for the operation of its business as
currently contemplated without any conflict with the rights of others. To the
best knowledge of such Co-Borrower, no product, process, method, substance, part
or other material sold or employed or presently contemplated to be sold by or
employed by the Co-Borrower or any Subsidiary of such Co-Borrower in connection
with its business infringes or will infringe any patent, trademark, permit,
service mark, trade name, copyright, franchise, formula, license or other
intellectual property right.

                  (aa)     Insolvency and Insolvency Proceedings. Neither the
Co-Borrower nor any of its Subsidiaries is insolvent as defined under any
Applicable Law, nor, after giving effect to the consummation of the transactions
contemplated in the Agreement, will the Co-Borrower or any such Subsidiary be
rendered insolvent by the execution and delivery of the Agreement (including,
without limitation, the Notes) or the consummation of the transactions
contemplated thereby. The Co-Borrower is not engaged, nor is it about to engage,
in any business or transaction for which the assets retained by it shall be an
unreasonably small amount of capital, taking into consideration the Obligations
incurred hereunder.

MIA1 #1016002.v8                       43                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   51

                                EXECUTION COPY

                  (bb)     Acknowledgment of Advances. The information set forth
under each Acknowledgment of Advances confirmed and signed by the Co-Borrower is
true and complete as set forth therein.

                  (cc)     Notice of Borrowing. With respect to IMPSAT
Comunicacoes Ltda. (Brazil), the information set forth and each Brazil Notice of
Borrowing is accurate and complete as of the date set forth therein.

         Section 9.02. Representations and Warranties of the Guarantor. The
Guarantor makes the representations and warranties set forth below to the Lender
as of the Initial Borrowing Date and the date of each Advance, except to the
extent any such representations and warranties specifically relate to an earlier
date. All of the representations and warranties under this Article IX shall
survive the Initial Borrowing Date and the making of Advances and remain in
effect until all amounts due hereunder have been fully paid:

         (a)      Organization, Good Standing. The Guarantor is a corporation
duly incorporated and validly existing and in good standing under the laws of
State of Delaware and has the power and authority (including any required
license, permit or other approval from any Governmental Authority) to own its
property, to conduct its business as currently conducted and to consummate the
transactions contemplated in, and to perform its obligations under, this
Agreement.

         (b)      Foreign Corporation. The Guarantor is duly qualified and in
good standing as a foreign corporation in each jurisdiction (other than the
State of Delaware) in which the nature of its activities makes the qualification
or licensing necessary.

         (c)      Due Authorization. The Guarantor has taken all necessary
action to authorize the Guaranty, the execution and delivery of this Agreement,
the execution and delivery of the Guaranty Agreement, the execution and delivery
of all other documents to be executed and delivered by it in connection with
this Agreement and the performance of its obligations under this Agreement, the
Guaranty Agreement and the Notes.

         (d)      Enforceability. This Agreement and the Guaranty Agreement have
been duly executed and delivered by the Guarantor and constitute valid and
binding obligations of the Guarantor, enforceable against the Guarantor in
accordance with their respective terms, subject to applicable bankruptcy,
insolvency, moratorium and similar laws affecting creditors' rights generally,
and subject, as to enforceability, to general principles of equity (regardless
of whether enforcement is sought in a proceeding in equity or at law).

         (e)      Subsidiary Shares. The Guarantor owns of record and has full
power to direct the voting of all of the issued and outstanding shares of
Capital Stock (or quotas as the case may be) of each Co-Borrower as disclosed to
the Lender. The Guarantor has good and marketable title to the shares (or quotas
as the case may be) of each Co-Borrower owned by it.

MIA1 #1016002.v8                       44                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   52

                                EXECUTION COPY

         (f)      Governmental Authorizations. No authorizations or actions of
any kind from any Governmental Authority are necessary to authorize the Guaranty
by the Guarantor or required for the validity or enforceability against the
Guarantor of this Agreement or the Notes.

         (g)      Consents, Non-Contravention. No consent or approval of, or
notice to, any counterparty of the Guarantor is required by the terms of any
Contract (including, without limitation, any agreement or instrument evidencing
any Indebtedness of the Guarantor) for the execution or endorsement (as the case
may be) or the delivery by the Guarantor of, or the performance of its or any
Co-Borrower's obligations under, this Agreement or the Notes, and such
execution, endorsement, delivery and performance will not result in any breach
or violation of, or constitute a default under, the charter or by-laws of the
Guarantor or any material agreement, instrument, judgment, order, statute, rule
or regulation applicable to the Guarantor or to any of its property.

         (h)      Litigation. There are no actions, proceedings or claims
pending or, to the knowledge of the Guarantor, threatened the adverse
determination of which might result in a Material Adverse Effect, or affect the
validity or enforceability of, this Agreement or the Notes.

         (i)      No Default. No Default, Event of Default or default under any
agreement or instrument evidencing any Indebtedness of the Guarantor which would
permit the acceleration of any Indebtedness is occurring and continuing, and no
such event will occur upon the making of any Advances.

         (j)      Insurance. The Guarantor has taken all action necessary to
acquire adequate insurance policies with financially sound and reputable
insurers in such amounts and against such risks as is customary for those
Persons engaged in the same type or types of business as the Guarantor, such
policies being in full force and effect as of the date of this Agreement, and
there being no delinquencies in the payment of any premium for such policies.

         (k)      Taxes. The execution and delivery of this Agreement and of the
Guaranty Agreement are not subject to any Taxes.

         (l)      Status of Obligations. The Guarantor's obligations under this
Agreement rank, and its obligations under the Guaranty Agreement will rank, at
least pari passu with all its other unsecured Indebtedness.

         (m)      Compliance with Contracts. With respect to each Contract that
is material to the Guarantor's business, (i) each such Contract is a valid and
binding agreement of the Guarantor and is in full force and effect in all
material respects, and (ii) the Guarantor is in compliance with each such
Contract and has no knowledge of any default under any such Contract which
default has not been cured or waived and which default would reasonably be

MIA1 #1016002.v8                       45                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   53

                                EXECUTION COPY

expected to have a Material Adverse Effect on the financial condition of the
Guarantor or impair the ability of the Guarantor to perform its obligations
under, or affect the validity or enforceability of, this Agreement or the
Guaranty Agreement.

         (n)      Disclosure. All information heretofore supplied to the Lender
pursuant to this Agreement by or on behalf of the Guarantor is true, accurate
and complete in all material respects. All representations and warranties made
by the Guarantor in all of the Credit Documentation to which it is a party are
true and complete in all material respects on and as of the date hereof (or such
later date as this representation is deemed made pursuant to the terms hereof).

         (o)      Financial Statements. The Guarantor's consolidated financial
statements as at December 31, 2000, and for the fiscal year ended on such date
are complete and correct, have been prepared in accordance with GAAP, and have
been certified by a firm of independent accountants as fairly presenting the
financial condition of the Guarantor as at such date and the results of its
operations for such fiscal year.

         (p)      No Untrue Statements; No Material Adverse Effect. None of the
Guaranty Agreement or any document, certificate or instrument of the Guarantor
or any of its officers delivered to the Lender in conjunction with the Guaranty
contains any untrue statement of a material fact or omits to state a material
fact necessary to make the statements contained therein, in light of the
circumstances under which they were made, not misleading. There is no fact known
to the Guarantor which adversely affects, or in the future may (so far as the
Guarantor can now reasonably foresee) adversely affect, the business or
condition of either the Guarantor or any Co-Borrower or impair the ability of
the Guarantor to perform its obligations under this Guaranty. No Material
Adverse Change in the financial condition of the Guarantor has occurred since
the dates of the audited financial statements of December 31, 2000, submitted to
the Lender.

         (q)      Insolvency and Insolvency Proceedings. The Guarantor is not
presently Insolvent, as defined under the Applicable Law, and entering into and
performing its obligations under the Guaranty Agreement will not render the
Guarantor Insolvent, as defined under the Applicable Law. Neither the Guarantor
nor any controlling stockholder of the Guarantor, is currently a debtor in any
bankruptcy, reorganization, insolvency or similar proceeding.

         (r)      Immunity. The Guaranty of the Guarantor under this Agreement
and the execution, delivery and performance of this Agreement and the Guaranty
Agreement constitute private and commercial acts rather than public or
governmental acts. Under the laws of Delaware and the United States of America,
the Guarantor is not entitled to any immunity, sovereign or otherwise, from any
action or proceeding in connection with this Agreement or the Guaranty
Agreement.

MIA1 #1016002.v8                       46                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   54

                                EXECUTION COPY

                                    ARTICLE X
                              AFFIRMATIVE COVENANTS

         Section 10.01. Good and Marketable Title. Each Co-Borrower shall
preserve and maintain good and marketable title to the Collateral free of
encumbrance and shall at all times warrant and defend the title to such
Collateral against the claims and demands of all Persons, except with respect to
Liens created under the Security Documents.

         Section 10.02. Financial Statements and Information.

         (a)      Each Co-Borrower shall furnish to the Lender, on or before the
forty-fifth (45th) day after the close of each of the first three quarters of
each of its fiscal years, its balance sheet as at the close of such quarter and
its income statement and statement of changes in financial position for such
quarter, prepared in accordance with GAAP, certified by its chief financial
officer as fairly presenting its financial condition as at the close of such
quarter and the results of its operations for such quarter, which certification
shall include or be accompanied by a statement that there has occurred during
such quarter no event that constituted, or that, with the giving of notice or
the lapse of time or both, would have constituted, an Event of Default (or a
detailed description of any such event that has occurred).

         (b)      With respect to each of the Co-Borrower's respective fiscal
years, each Co-Borrower shall furnish to the Lender, on or before the ninetieth
(90th) day after the close of such fiscal year, its balance sheet as at the
close of such fiscal year and its income statement and statement of changes in
financial position for such fiscal year, prepared in accordance with GAAP,
certified by a firm of independent accountants selected by it and acceptable to
the Lender as fairly presenting the financial condition of such Co-Borrower as
at the close of such fiscal year and the results of its operations for such
fiscal year, which certification shall include or be accompanied by a statement
that, during the examination by such firm of such financial statements, such
firm observed or discovered no event that constituted, or that, with the giving
of notice or the lapse of time or both, would have constituted, an Event of
Default (or a detailed description of any such event so observed or discovered).

         (c)      Each Co-Borrower shall furnish to the Lender from time to time
the Acknowledgements of Advances in accordance with Section 2.07 and such other
statements and information as the Lender may reasonably request.

         (d)      (i) The Guarantor shall furnish to the Lender the latest
publicly available financial information of the Guarantor from time to time as
the Lender may reasonably request and (ii) the Guarantor, IMPSAT S.A.
(Argentina), and IMPSAT Comunicacoes Ltda. (Brazil) shall furnish to the Lender
its respective annual business plan within 120 days of the beginning of each
calendar year.

MIA1 #1016002.v8                       47                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   55

                                EXECUTION COPY

         Section 10.03. Books and Records. Each Co-Borrower, its Subsidiaries,
and the Guarantor shall keep proper books and records and account in which
entries in conformity with GAAP and all requirements of law applicable to it
shall be made of all dealings and transactions in relation to its business and
activities.

         Section 10.04. Inspection Rights; Access. Each Co-Borrower and its
Subsidiaries shall permit representatives of the Lender to examine its property
(including, without limitation, the Collateral), books and records at any
reasonable times and upon reasonable notice. Each Co-Borrower, its respective
Subsidiaries and the Guarantor shall allow the Lender reasonable access to their
senior management.

         Section 10.05. Governmental Approvals and Authorizations. Each
Co-Borrower and the Guarantor shall obtain, make and keep in full force and
effect the Governmental Approvals and all other authorizations from and
registrations with Governmental Authorities that may be required for the
validity or enforceability against such Co-Borrower and the Guarantor of this
Agreement, the Notes, the Guaranty Agreement, and the Security Documents.

         Section 10.06. Conduct of Business and Maintenance of Existence. Each
Co-Borrower and their respective Subsidiaries, if any, shall continue to engage
in the Telecommunications Business in the respective Co-Borrowers' countries,
and shall preserve, renew and keep in full force and effect, their respective
corporate existence and its rights, privileges and franchises necessary to the
normal conduct of its business. Without limiting the foregoing, each Co-Borrower
shall continue to pay all fees and taxes required to be paid by it under the law
of the respective Co-Borrowers' countries and shall maintain adequate
capitalization under the requirements of the law of the respective Co-Borrowers'
countries.

         Section 10.07. Compliance with Laws. Each Co-Borrower shall comply with
all Applicable Laws, ordinances, rules and regulations (including without
limitation those relating to the environment, health and safety), concessions
(including without limitation any License), permits and material contractual
obligations relative to the conduct of its business and to the Collateral,
except where the necessity of compliance therewith is contested in good faith by
appropriate proceedings or where the failure to so comply would not result in a
Material Adverse Effect.

         Section 10.08. Notices. Each Co-Borrower shall promptly, but in no
event later than three (3) Banking Days after (unless otherwise indicated below)
such Co-Borrower obtains knowledge of the occurrence of the following events,
give notice to the Lender of the occurrence of any of the following:

         (a)      a Default or an Event of Default;

         (b)      a default by such Co-Borrower under any material Contract;

MIA1 #1016002.v8                       48                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   56

                                EXECUTION COPY

         (c)      any (i) (A) commencement or Material Adverse Change in respect
of any litigation, investigation or proceeding of or before any arbitrator or
Governmental Authority in which the amount in controversy exceeds five million
Dollars (US$5,000,000); or (B) any material litigation, investigation or
proceeding of or before any arbitrator or Governmental Authority which, to the
knowledge of such Co-Borrower is threatened by or against such Co-Borrower, any
of its Subsidiaries, or against any of their properties or revenues which: (x)
purport to affect or pertain to this Agreement or the Supply Contract(s) or any
of the transactions contemplated hereby or thereby, or (y) if determined
adversely, could reasonably be expected to have a Material Adverse Effect; (ii)
issuance by any Governmental Authority of an injunction, writ, temporary
restraining order or any order of any nature purporting to enjoin or restrain
the execution, delivery or performance of this Agreement or the Supply
Contract(s), or directing that the transactions contemplated hereunder or
thereunder not be consummated as herein or therein provided; or (iii) issuance
by any Governmental Authority of any injunction, order, decision or other
restraint purporting to enjoin, restrain, prohibit (or which would have the
effect of prohibiting) the making of the Loans, or invalidate (or which would
have the effect of invalidating) any provision of this Agreement or the Supply
Contract(s), including provisions regarding the granting of Liens on the
Collateral or the priority of such Liens;

         (d)      during the Availability Period, any Material Adverse Change as
determined by the Co-Borrower in its reasonable judgment;

         (e)      thirty (30) days prior to the movement of any Goods and
Services or any other Collateral outside of such Co-Borrower's jurisdiction as
sent forth in the Security Documents, having, in the aggregate, at any time, a
replacement value in excess of five million Dollars (US$5,000,000);

         (f)      thirty (30) days prior thereto in writing, the movement of the
principal place of business of such Co-Borrower to any location other than as
set forth in the Security Documents; and

         (g)      Each Co-Borrower and the Guarantor shall, promptly upon
obtaining knowledge thereof, give written notice to the Lender of any litigation
or proceedings affecting the Collateral.

         The Lender shall have the right to request, with respect to any such
notice, a statement of an authorized officer of such Co-Borrower setting forth
reasonable details of the occurrence referred to therein and stating what action
such Co-Borrower proposes to take with respect thereto.

         Section 10.09. Prompt Payment. Each Co-Borrower and the Guarantor shall
punctually pay to the Lender all principal, interest, and any other amounts
owing by it under this

MIA1 #1016002.v8                       49                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   57

                                EXECUTION COPY

Agreement on the dates, at the place or places, in the currency or currencies,
and in the manner specified herein.

         Section 10.10. Notice of Certain Amendments or Waivers. The Guarantor
shall promptly give written notice to the Lender of any proposal to amend or
waive the terms of any Impsat Indenture.

         Section 10.11. Insurance. Each Co-Borrower and the Guarantor shall
deliver to the Lender certificates evidencing all the insurance as further
described in Section 9.01(n) and Section 9.02(j) hereof. Each Co-Borrower shall
preserve and maintain, and cause each of its respective Subsidiaries to preserve
and maintain, with financially sound and reputable insurance companies,
insurance in such amounts and against such risks as are customarily maintained
by companies engaged in the same or similar business operating in the same or
similar locations; and pay, and cause each of its Subsidiaries to pay, all
premiums thereon before the same shall become delinquent.

         Section 10.12. Security Documents.

         (a)      Each Co-Borrower shall, at its sole cost and expense, deliver
to Lender a duly executed, but not registered, Security Document, in form and
substance satisfactory to the Lender, which will constitute a valid and binding
obligation of such Co-Borrower, enforceable against such Co-Borrower in
accordance with its terms; each new Security Document shall include as of the
date of delivery to the Lender of the Security Documents and in accordance with
Section 10.12(b): (x) a detailed and complete list of all equipment delivered by
Harris to such Co-Borrower for which title has passed to such Co-Borrower
pursuant to the Supply Contract(s) and (y) the total amount of the Obligations
outstanding at the time of the making of the then most-recent Advance to such
Co-Borrower.

         (b)      Each Co-Borrower shall deliver its respective Security
Documents to the Lender in accordance with Section 10.12(a), unless otherwise
provided:

                  (i)      initially, (A) with respect to each of Impsat S.A.
(Argentina) and Impsat Comunicacoes Ltda. (Brazil), on a date that is no later
than 90 days after the initial Advance made to such Co-Borrower, and (B) with
respect to each of Impsat S.A. (Colombia), Impsatel Del Ecuador S.A. (Ecuador),
and Telecomunicaciones Impsat S.A. (Venezuela), taken as a whole, on June 30,
2001; and

                  (ii)     subsequently, upon the earliest of the following
dates to occur with respect to Goods and Services delivered to such Co-Borrower
but for which Security Documents have not been delivered to the Lender, (A) the
date upon which the aggregate of all Advances made to such Co-Borrower in
respect of such Goods and Services equals or exceeds (x) US$2,500,000 in the
case of each of Impsat S.A. (Argentina) and Impsat Comunicacoes Ltda. (Brazil),
respectively, and (y) the aggregate of US$1,500,000 with

MIA1 #1016002.v8                       50                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   58

                                EXECUTION COPY

respect to each of Impsat S.A. (Colombia), Impsatel Del Ecuador S.A. (Ecuador),
and Telecomunicaciones Impsat S.A. (Venezuela), taken as a whole, or (B) (x)
with respect to each of Impsat S.A. (Argentina) and Impsat Comunicacoes Ltda.
(Brazil), the date that is no later than 90 days after the date of the most
recent Security Document delivered to the Lender and (y) with respect to each of
Impsat S.A. (Colombia), Impsatel Del Ecuador S.A. (Ecuador), and
Telecomunicaciones Impsat S.A. (Venezuela), taken as a whole, each September 30,
December 31, March 31 and June 30 to occur after June 30, 2001.

         (c)      With respect to the obligations of each of Impsat S.A.
(Colombia), Impsatel Del Ecuador S.A. (Ecuador) and Telecomunicaciones Impsat
S.A. (Venezuela) to deliver Security Documents to the Lender in accordance with
Section 10.12(b), the parties agree, without prejudicing the right of the Lender
to otherwise receive the Security Documents from the Co-Borrowers in strict
accordance with Section 10.12(b), to consult from time to time in the interest
of timing the delivery of the Security Documents more or less frequently, taking
into account the aggregate of Advances made to a particular Co-Borrower as
compared with the aggregate of Advances made to other Co-Borrowers within the
same time period.

         Section 10.13. Further Assurances; Supply Contract(s).

         (a)      Each Co-Borrower and the Guarantor shall promptly, at its sole
cost and expense, execute and deliver to the Lender such further instruments and
documents, and take such further action, as the Lender may, at any time and from
time to time, reasonably request in order to carry out the intent and purpose of
this Agreement, the Notes and the Security Documents and to establish and
protect the rights, interests and remedies created, or intended to be created,
in favor of the Lender hereby and thereby, including, without limitation, the
execution, delivery, recordation and filing of security agreements, financing
statements and continuation statements with respect to the Collateral. Each
Co-Borrower and the Guarantor shall pay, or reimburse the Lender for, any and
all fees, costs and expenses of whatever kind or nature incurred in connection
with the creation, preservation and protection of the Lender's Liens on, and
security interests in, the Collateral, including, without limitation, reasonable
and documented legal fees, other fees and taxes in connection with the recording
or filing of instruments and documents in public offices, payment or discharge
of any taxes or Liens upon or in respect of the Collateral, other fees, costs
and expenses in connection with protecting, maintaining or preserving the
Collateral and the Lender's interests therein, whether through judicial
proceedings or otherwise, or in defending or prosecuting any actions, suits or
proceedings arising out of or related to the Collateral; and all such amounts
that are paid by the Lender shall, until reimbursed by such Co-Borrower,
constitute Obligations of such Co-Borrower secured by the Collateral.

         (b)      Each Co-Borrower shall, at its own cost and expense, promptly
take any action necessary to preserve the Collateral and to keep the Collateral
in good working order and condition.

MIA1 #1016002.v8                       51                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   59

                                EXECUTION COPY

         (c)      Each Co-Borrower shall, at its own cost and expense, promptly
take such action as may be necessary to discharge duly all Liens on any part of
the Collateral (other than the Liens created under this Agreement and the
Security Documents), and agrees to make restitution to the Lender for any
diminution in the value of its security interest resulting from such Liens. Each
Co-Borrower shall assume responsibility in respect of, and shall protect, save
and keep harmless the Lender from and against any and all liabilities,
obligations, losses, damages, penalties, claims, actions, suits, costs, expenses
and disbursements (including legal fees and disbursements) of any kind and
nature whatsoever that may be imposed on, incurred by or asserted against the
Lender in any way relating to or arising out of any such Lien.

         (d)      The Lender shall have received a copy of the Supply
Contract(s), duly executed by all parties thereto, immediately upon the
execution thereof.

         Section 10.14. Maintenance of Properties, Etc.. Each Co-Borrower shall,
and shall cause each of its Subsidiaries to, maintain and preserve all of its
material properties, ordinary wear and tear excepted, and, from time to time,
make or cause to be made all appropriate and proper repairs, renewals,
replacements, enhancements, additions and improvements thereto in accordance
with sound business practices, and keep all systems and equipment in compliance
with any and all standards or rules (including compliance with technical
standards and construction requirements and deadlines) imposed pursuant to any
Applicable Law or by any Governmental Authority or pursuant to the terms of any
material Contract (including the Licenses). At a minimum, such Co-Borrower
shall, and shall cause each of its Subsidiaries to, use the standard of care
typical in the international telecommunications industry in the operation and
maintenance of its telecommunications properties.

         Section 10.15. Status of Obligations. Each Co-Borrower shall ensure
that its payment obligations under this Agreement and the Note will at all times
constitute the direct, general and unconditional obligations of such Co-Borrower
and rank in all respects as provided in Section 9.01(p).

         Section 10.16. Maintenance of Corporate Separateness. Each Co-Borrower
will, and will cause each of its Subsidiaries to, satisfy customary corporate
formalities required under the respective Organization Documents of each
Co-Borrower or Subsidiary, including the holding of regular board of directors'
and shareholders' meetings and the maintenance of corporate offices and records.

         Section 10.17. License Marks. Each Co-Borrower shall, and shall cause
each of its Subsidiaries to, preserve or renew all of its registered patents,
trademarks, trade names and service marks, and all of its licenses or other
rights to use the foregoing, the non-preservation or non-renewal of which could
reasonably be expected to have a Material Adverse Effect.

MIA1 #1016002.v8                       52                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   60

                                EXECUTION COPY

         Section 10.18 Shareholder Authority. To the extent that a Co-Borrower
or any Subsidiary is required by Applicable Law to obtain authority from its
shareholders to perform or refrain from performing, as the case may be, any of
the covenants contained in Article X or Article XI of this Agreement, then such
Co-Borrower or Subsidiary (as the case may be) shall take all necessary action
before its shareholders so that its shareholders can maintain or adopt all
necessary decisions for the full performance of the obligations of such
Co-Borrower or Subsidiary.

         Section 10.19 Supply Contract(s) As soon as reasonably practicable,
Harris and each Co-Borrower shall enter into the Supply Contract(s) as
contemplated by this Agreement.

                                   ARTICLE XI
                               NEGATIVE COVENANTS

         Section 11.01. Merger; Change of Control; Sale of Assets. Neither any
Co-Borrower nor the Guarantor shall (i) merge or consolidate with any other
corporation; (ii) undergo a Change of Control, or (iii) directly or indirectly
sell, lease or transfer or otherwise dispose of all or any substantial part of
its assets other than in such Co-Borrower's or the Guarantor's ordinary course
of business in each case without the prior written consent of the Lender.

         Section 11.02. Liens. No Co-Borrower shall, nor shall any Co-Borrower
permit any of its Subsidiaries to, create, incur, assume or otherwise permit to
exist any Lien on any of its properties of any character (including accounts
receivable and bank accounts), whether now owned or hereafter acquired, or on
any proceeds or income therefrom, or sign any security agreement authorizing any
secured party thereunder to file any financing statement, record any Lien or
take any similar action, or assign any accounts or any other right to receive
income, except for the Liens created under the Security Documents, the Liens set
forth in Exhibit K and Permitted Liens.

         Section 11.03. Amendment and Waiver. Neither any Co-Borrower nor the
Guarantor shall enter into any amendment of, or agree to or accept or consent to
any waiver (each, an "Amendment") of any of the material provisions of (i)
Organization Documents; (ii) any agreements among its respective shareholders;
and (iii) any material Contracts to which it is a party or any License, except
to the extent that such Amendment could not reasonably be expected to have a
Material Adverse Effect; provided, however, that in the case of a License, such
Co-Borrower shall give the Lender no less than five (5) Banking Days prior
written notice of such Person's proposed Amendment.

         Section 11.04. Business Restriction. Neither any Co-Borrower nor any of
its Subsidiaries shall, directly or indirectly, enter into any business except
the operation of a Telecommunications Business in the respective Co-Borrower's
country without the prior written consent of the Lender.

MIA1 #1016002.v8                       53                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   61

                                EXECUTION COPY

         Section 11.05. Restricted Payments. Each Co-Borrower agrees not to, and
to cause its Subsidiaries not to, effective as of the date that such agreement
will not cause the Guarantor to violate its obligations under the IMPSAT
Indentures:

         (a)      reduce or increase such Person's capital, except to the extent
that any such action is required for each Co-Borrower to comply with the
covenants contained in Section 11.07, if applicable; or

         (b)      declare or pay any dividends or make any distributions or
other payments or delivery of property or cash in respect of:

                  (i)      the interest of such Person's shareholders or other
equity owners; or

                  (ii)     any Indebtedness which is by its terms subordinate or
junior in right of payment to the Loans.

         Notwithstanding any provision herein to the contrary, each Co-Borrower
shall not, and shall not permit its Subsidiaries to, make any distributions or
other payments or delivery of property or cash in respect of any Pledged
Shareholder Note other than as expressly permitted therein.

         Section 11.06. Investments in Subsidiaries. Each Co-Borrower shall not,
and shall not permit any of its Subsidiaries to make any Investment other than
(i) Permitted Investments or (ii) Investments in one or more Persons which will,
upon the making of such Investment, become a Subsidiary, joint venture,
partnership, or a consortium, or be merged or consolidated with or into or
transfer or convey all or substantially all its assets to, such Co-Borrower or a
Subsidiary thereof; provided that (1) such Person's primary business is related,
ancillary or complementary to the Telecommunications Business, and (2)
immediately before and immediately after the date of such Investment, such
Co-Borrower is in compliance with the covenants contained in Section 11.15 (as
applicable) as determined on a pro forma basis; and provided further that an
Investment will not be permitted under clause (ii) if the sum of the
consideration to be paid in respect of such Investment plus the consideration
paid in respect of all previous Investments made under this clause (ii) exceeds
forty percent (40%) of the such Co-Borrower's net worth immediately preceding
such Investment.

         Section 11.07. Financial Covenants.

         (a)      Neither IMPSAT S.A. (Argentina) nor IMPSAT Comunicacoes Ltda.
(Brazil), as the case may be, for so long as any amounts under the Facility
remain unpaid, shall permit:

                  (i)      Total Debt to Adjusted EBITDA to exceed: (A) in the
case of IMPSAT S.A. (Argentina), (u) 10.0:1.0 for the third quarter of 2001, (v)
8.0:1.0 for fourth quarter of 2001, (w) 5.5:1.0 for the year 2002, (x) 3.5:1.0
for the year 2003, (y) 2.0:1.0 for the year

MIA1 #1016002.v8                       54                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   62

                                EXECUTION COPY

2004, and (z) 2.0:1.0 for the year 2005; and (B) in the case of IMPSAT
Comunicacoes Ltda. (Brazil), (w) 6.0:1.0 for the year 2002, (x) 5.0:1.0 for the
year 2003, (y) 3.0:1.0 for the year 2004, and (z) 3.0:1.0 for the year 2005;

                  (ii)     Adjusted EBITDA to Interest Expense to decrease to a
level below: (A) in the case of IMPSAT S.A. (Argentina), (u) 1.0:1.0 for the
third quarter of 2001, (v) 1.5:1.0 for the fourth quarter of 2001, (w) 1.8:1.0
for the year 2002, (x) 3.0:1.0 for the year 2003, (y) 4.0:1.0 for the year 2004,
and (z) 5.0:1.0 for the year 2005; and (B) in the case of IMPSAT Comunicacoes
Ltda. (Brazil), (w) 0.3:1.0 for the year 2002, (x) 1.3:1.0 for the year 2003,
(y) 1.5:1.0 for the year 2004, and (z) 3.0:1.0 for the year 2005;

                  (iii)    Total Debt to Paid in Capital to exceed: (A) in the
case of IMPSAT S.A. (Argentina), (w) 2.5:1.0 for the third quarter of 2001, (x)
2.5:1.0 for the fourth quarter of 2001, (y) 2.5:1.0 for the year 2002, and (z)
2.0:1.0 for the year 2003; and (B) in the case of IMPSAT Comunicacoes Ltda.
(Brazil), (u) 3.0:1.0 for the third quarter of 2001, (v) 3.0:1.0 for the fourth
quarter of 2001, (w) 3.0:1.0 for the year 2002, (x) 3.0:1.0 for the year 2003,
(y) 2.5:1.0 for the year 2004, and (z) 2.5:1.0 for the year 2005;

                  (iv)     Total Debt to Total Equity to exceed: (A) in the case
of IMPSAT S.A. (Argentina), (x) 2.5:1.0 for the year 2003, (y) 2.0:1.0 for the
year 2004, and (z) 2.0:1.0 for the year 2005; and (B) in the case of IMPSAT
Comunicacoes Ltda. (Brazil), (y) 3.0:1.0 for the year 2004, and (z) 2.5:1.0 for
the year 2005; and

                  (v)      Adjusted EBITDA to Debt Service to exceed: (A) in the
case of IMPSAT S.A. (Argentina), (u) 0.5:1.0 for the third quarter of 2001, (v)
0.5:1.0 for the fourth quarter of 2001, (w) 0.5:1.0 for the year 2002, (x)
0.8:1.0 for the year 2003, (y) 1.3:1.0 for the year 2004, and (z) 1.7:1.0 for
the year 2005; and (B) in the case of IMPSAT Comunicacoes Ltda. (Brazil), (w)
0.25:1.0 for the year 2002, (x) 0.45:1.0 for the year 2003, (y) 1.0:1.0 for the
year 2004, and (z) 1.5:1.0 for the year 2005.

         (b)      Neither IMPSAT S.A. (Colombia), IMPSATEL Del Ecuador S.A.
(Ecuador) nor Telecomunicaciones IMPSAT, S.A. (Venezuela), or any combination
thereof (either among such Co-Borrowers, or with any Co-Borrower, or the
Guarantor or any Guarantor Subsidiary), shall enter into any financing
arrangement or agree to, amend, modify or restructure the terms of any
then-existing financing agreement with any creditor to include any financial
covenants or similar agreements, unless the Lender shall benefit from or is
granted the same terms as such covenants or agreements on the same basis as
provided to such other creditor of such Co-Borrower. In the event that such
Co-Borrower enters into such arrangements, such Co-Borrower shall (i) notify the
Lender no later than the date such arrangements are executed, (ii) provide the
Lender with a copy of the arrangement or agreement containing the terms of such
financial covenants or similar agreements, and (iii) certify to the Lender
(pursuant to a certification executed by an authorized signatory of such

MIA1 #1016002.v8                       55                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   63

                                EXECUTION COPY

Co-Borrower) that the copy of such arrangement or agreement is complete, true
and correct copy of the original documents containing such arrangement or
agreement.

         Section 11.08. Prepayment of Indebtedness. None of the Co-Borrowers
shall, and shall not permit any of their respective Subsidiaries to, nor shall
the Guarantor, make any optional payment or optional prepayment on or
redemption, defeasance or purchase of any Indebtedness (other than the Loans,
the 2003 Indenture, and all funds obtained for the stated purpose of satisfying
in full any existing Indebtedness) at any time (including, but not limited to,
the Impsat Indentures, excluding the 2003 Indenture), without prepaying, at the
same time, the outstanding Obligations and the Notes on a pro rata basis.

         Section 11.09. Accounting Methods. Neither the Co-Borrowers nor the
Guarantor shall change, modify or alter, nor permit their respective
Subsidiaries to change, modify or alter, the maintenance of their respective
books and records of account other than in accordance with GAAP.

         Section 11.10. Additional Indebtedness. No Co-Borrowers shall, nor
shall any Co-Borrower permit any of its Subsidiaries to, incur, assume,
guarantee, permit to exist or otherwise become liable for any Indebtedness
except:

         (a)      Indebtedness under or pursuant to the Agreement and the Notes;
and

         (b)      Permitted Indebtedness.

         Section 11.11. Conduct of Business with Affiliates. No Co-Borrower
shall, nor shall any Co-Borrower permit any of its Subsidiaries to, conduct any
business with, or enter into any business transaction involving, any shareholder
or any other Affiliate of such Co-Borrower, unless such business or transaction
involving any shareholder or any other Affiliate of such Co-Borrower, and such
business or transaction is (i) in the ordinary course of such Co-Borrower's or
such Subsidiary's (and such shareholder's or other Affiliate's) business, and
(ii) upon fair and reasonable terms no less favorable to such Co-Borrower or
such Subsidiary, as the case may be, than it would obtain in a comparable arm's
length transaction with a Person which is not an Affiliate.

         Section 11.12. Capital Expenditures. No Co-Borrower shall, nor shall
any Co-Borrower permit any of its Subsidiaries to, make or commit to make any
Capital Expenditure in excess of the amounts shown in the table below or as
contemplated by the Business Plan attached hereto as Exhibit H. Any amount of
Capital Expenditures that is not spent by such Co-Borrower in the particular
year for which such Capital Expenditures were originally allocated pursuant to
the Business Plan may be carried over solely for one year after which, such
amount, if not spent during such year, shall no longer be available.

MIA1 #1016002.v8                       56                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   64

                                EXECUTION COPY

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------------
                                        IMPSAT                                 IMPSATEL Del        Telecomunicaciones
               IMPSAT S.A.        Comunicacoes Ltda.        IMPSAT S.A.        Ecuador S.A.            IMPSAT S.A.
   Year        (Argentina)             (Brazil)              (Colombia)          (Ecuador)             (Venezuela)
-------------------------------------------------------------------------------------------------------------------------
<S>           <C>                  <C>                     <C>                <C>                     <C>
   2001        $150,000,000          $130,000,000           $25,000,000         $10,000,000            $25,000,000
-------------------------------------------------------------------------------------------------------------------------
   2002        $50,000,000            $65,000,000           $15,000,000         $4,000,000             $12,000,000
-------------------------------------------------------------------------------------------------------------------------
   2003        $50,000,000            $85,000,000           $15,000,000         $4,000,000             $12,000,000
-------------------------------------------------------------------------------------------------------------------------
   2004        $50,000,000           $100,000,000           $15,000,000         $5,000,000             $10,000,000
-------------------------------------------------------------------------------------------------------------------------
   2005        $50,000,000           $120,000,000           $15,000,000         $5,000,000             $12,000,000
-------------------------------------------------------------------------------------------------------------------------
</TABLE>

         Section 11.13. Accounts Receivable. The Co-Borrowers shall not, and
shall not permit any of their respective Subsidiaries to, directly or indirectly
(except as a Permitted Lien), sell or factor any account receivable. Each
Co-Borrower shall keep accurate and complete records of the accounts receivable
of such Co-Borrower and each of its Subsidiaries and deliver to the Lender such
information about such accounts receivable as the Lender may request from time
to time.

         Section 11.14.  Intentionally omitted.

         Section 11.15. Limitation on Contingent Obligations. No Co-Borrower
shall, nor shall any Co-Borrower permit any of its Subsidiaries to, create,
incur, assume or suffer to exist any Contingent Obligation, except (i)
guarantees made in the ordinary course of business by a Co-Borrower of
obligations of any of its Subsidiaries, provided that such obligations are
otherwise permitted under this Agreement, (ii) Permitted Fianzas, (iii)
guarantees made by a Co-Borrower to the extent such guarantees currently exist
on the date hereof, and (iv) guarantees made in the ordinary course of business
by a Co-Borrower of the Obligations of any other Co-Borrower or of the
Guarantor.

                                   ARTICLE XII
                                  THE GUARANTY

         Section 12.01. The Guaranty.

         (a)      The Guarantor irrevocably guarantees (as primary obligor and
not merely as surety), by virtue of the Guaranty Agreement, payment in full as
provided herein, of all amounts payable by the Co-Borrowers under this Agreement
and the Notes, as and when such amounts become payable (whether at stated
maturity, by acceleration or otherwise).

         (b)      The Guarantor's obligations under this Guaranty shall be
unconditional, irrespective of the validity or enforceability of any other
provision of this Agreement or of the Notes. In the event this Agreement, the
Notes or any part hereof or thereof is deemed unenforceable, this Guaranty and
the Guaranty Agreement shall stand alone and be enforced separately and such
obligations under the Guaranty Agreement shall be independent of the obligations
of any Co-Borrower.

MIA1 #1016002.v8                       57                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   65

                                EXECUTION COPY

         Section 12.02. Examination and Delivery of the Guaranty Agreement. As
evidence of this Guaranty, the Guarantor shall execute and deliver the Guaranty
Agreement to the Lender.

                                  ARTICLE XIII
                     EVENTS OF DEFAULT; REMEDIES; SUSPENSION

         Section 13.01. Events of Default. If one or more of the following
events of default (each, an "Event of Default") occurs and is continuing, the
Lender shall be entitled to the remedies set forth in Section 13.02:

         (a)      Any Co-Borrower fails to pay any amount payable hereunder as
and when such amount becomes payable.

         (b)      Any Co-Borrower or the Guarantor fails to perform or observe
any covenant or agreement contained herein to be performed or observed by it
other than those referred to in Section 13.01(a), if such failure is not
remedied on or before the thirtieth (30th) day after it occurs.

         (c)      Any representation or warranty of a Co-Borrower or the
Guarantor in this Agreement or any other document delivered in connection with
this Agreement proves to have been incorrect, incomplete or misleading in any
material respect at the time it was made or repeated or deemed to have been made
or repeated.

         (d)      A Co-Borrower or the Guarantor (i) (A) fails to pay its
Indebtedness as and when such Indebtedness becomes payable in an amount equal to
or exceeding the Cross Default Amount or (B) fails to pay any Indebtedness owed
to the Lender or any Affiliate thereof as and when such Indebtedness becomes
payable, or (ii) fails to perform or observe any covenant or agreement to be
performed or observed by it contained in any other agreement or in any
instrument evidencing any Indebtedness if, as a result of such failure, any
other party to such agreement or instrument is entitled to exercise, and has not
irrevocably waived, the right to accelerate the maturity of any amount owing
thereunder.

         (e)      A Co-Borrower or the Guarantor (i) is dissolved, (ii) fails or
is unable to pay its debts generally as they become due, (iii) commences,
pursuant to Applicable Law, a voluntary case in bankruptcy or any other action
or proceeding for any other relief under any law affecting creditors' rights
that is similar to a bankruptcy law or (iv) consents, pursuant to Applicable
Law, by answer or otherwise to the commencement against it of an involuntary
case in bankruptcy or any other such action or proceeding; or a court enters an
order for relief or a decree in an involuntary case in bankruptcy or any other
such action or proceeding in respect of Co-Borrower or the Guarantor or any of
the property of a Co-Borrower or the Guarantor if such order or decree is not
dismissed or stayed on or before the thirtieth (30th) day after the entry
thereof or if any such dismissal or stay ceases to remain in effect.

MIA1 #1016002.v8                       58                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   66

                                EXECUTION COPY

         (f)      Any governmental authorization necessary for the performance
of any obligation of a Co-Borrower or the Guarantor under this Agreement, the
Guaranty Agreement or the Notes fails to become or remain valid and subsisting
in full force and effect.

         (g)      Any Governmental Authority takes any action that, in the
reasonable opinion of the Lender, materially adversely affects the business,
operations, property, condition (financial or otherwise) or prospects of any
Co-Borrower or the Guarantor or impairs the ability of any Co-Borrower or the
Guarantor to perform its obligations under this Agreement, the Guaranty
Agreement or the Notes, if such action is not rescinded on or before the
thirtieth (30th) day after it occurs.

         (h)      The aggregate amount of unsatisfied judgments, decrees or
orders for the payment of money against a Co-Borrower or the Guarantor exceeds
US$5,000,000 or the equivalent thereof in any other currency or currencies.

         (i)      A Co-Borrower or the Guarantor sells or otherwise disposes of
all or a substantial part of its assets or ceases to conduct all or a
substantial part of its business as now conducted, or merges or consolidates
with any other company without the prior written consent of the Lender.

         (j)      (i) The Guaranty or the Guaranty Agreement is disaffirmed or
questioned as to its validity or enforceability by the Guarantor or ceases for
any reason to be valid or in full force and effect; or (ii) any Security
Document ceases for any reason to be valid or in full force and effect.

         (k)      Any Material Adverse Change has occurred since the date of the
most recent financial statements provided to the Lender under Section 10.02.

         Section 13.02. Default Remedies. If any Event of Default shall occur
and be continuing, the Lender may, by notice to the Co-Borrowers and the
Guarantor, (a) declare any or all of the obligations of the Lender hereunder to
be terminated, whereupon such obligations shall terminate, and (b) declare any
or all amounts payable hereunder and under the Notes by the Co-Borrowers or the
Guarantor that would otherwise be due after the date of such termination to be
immediately due and payable, whereupon all such amounts shall become immediately
due and payable, all without diligence, presentment, demand of payment, protest
or notice of any kind, which are expressly waived by the Co-Borrowers and the
Guarantor; provided, however, that if any event of any kind referred to in
Section 13.01(e) occurs, the obligations of the Lender hereunder shall
immediately terminate, and all amounts payable hereunder by the Co-Borrowers or
the Guarantor that would otherwise be due after the occurrence of such event
shall become immediately due and payable without any such notice or other
preliminary waived by the Co-Borrowers and the Guarantor in this Section 13.02.
Further, and without modification or limitation of the rights otherwise
specified in this Section

MIA1 #1016002.v8                       59                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   67

                                EXECUTION COPY

13.02 or under Sections 13.03 through 13.05 (inclusive), the Lender may, in
accordance with Applicable Law: (i) foreclose the Liens created under the
Security Documents relating to the Collateral by any available judicial
procedure or without judicial process, and sell, assign or otherwise dispose of
the Collateral or any part thereof, either at public or private sale, in lots or
in bulk, for cash, for credit or for future delivery, or otherwise, with or
without representations or warranties, and upon such terms as shall be
acceptable to the Lender, all at the sole option and discretion of the Lender;
(ii) enforce payment and prosecute any action or proceeding with respect to any
and all of the Collateral and take or bring, in the Lender's name or in the name
of the respective Co-Borrower, all steps, actions, suits or proceedings deemed
by the Lender to be necessary or desirable to effect collection of or to realize
upon the Collateral; (iii) take possession of the Collateral with or without
judicial process pursuant to Applicable Law; (iv) execute, in the name of the
respective Co-Borrower, any and all documents of title relating to the
Collateral; (v) transfer any or all of the Collateral into the name of the
Lender or its nominee or nominees; and (vi) exercise any and all other rights
and privileges affecting the possession, control, transfer and disposition of
the Collateral pursuant to Applicable Law.

         Section 13.03. Right of Set-off. If any amount payable to the Lender
hereunder is not paid as and when due, such Co-Borrower and the Guarantor hereby
authorizes the Lender and each Affiliate of the Lender to proceed, to the
fullest extent permitted by Applicable Law, without prior notice, by right of
set-off, counterclaim or otherwise, against any assets of any of the Co-Borrower
or the Guarantor (as the case may be) in any currency that may at any time be in
the possession of the Lender or such Affiliate, to the full extent of all
amounts payable to the Lender hereunder.

         Section 13.04. Benefit of Agreement; Rights Not Exclusive. This
Agreement shall be binding upon and inure to the benefit of the respective
successors and assigns of the parties hereto except that neither IFN nor any
Co-Borrower may assign or otherwise transfer all or any part of its rights or
obligations under this Agreement without obtaining the prior written consent of
the Lender. The rights provided for herein are cumulative and are not exclusive
of any other rights, powers, privileges or remedies provided by law.

         Section 13.05. Suspension of Available Credit. If at any time, (a) an
Event of Default or a Default occurs and is continuing; or (b) in the reasonable
judgment of the Lender, an event or circumstance occurs which makes it unlikely
that any Co-Borrower will be able to perform its obligations under this
Agreement on a timely basis, the Lender may, without prejudice to the
Co-Borrowers' and the Guarantor's obligations hereunder, including without
limitation, the obligation to pay interest and to repay principal, by notice to
the Co-Borrowers and the Guarantor, suspend the Lender's obligation to make
Advances, which suspension will continue until the Lender Notifies the
Co-Borrowers and the Guarantor that the suspension is removed.

MIA1 #1016002.v8                       60                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   68

                                EXECUTION COPY

                                 ARTICLE XIV
                               INCREASED COSTS

         Section 14.01. Funding Losses. If a Co-Borrower makes any payment of
principal with respect to any Advance on any day other than the last day of an
Interest Period applicable thereto, such Co-Borrower shall reimburse the Lender
within fifteen (15) days after demand for any resulting loss or expense incurred
by the Lender (or by any Person to whom the Lender may have sold a participation
in such Advance), including, without limitation, any loss incurred in obtaining,
liquidating or redeploying deposits from third parties; provided that the Lender
shall have delivered to such Co-Borrower a certificate as to the amount of such
loss or expense, which certificate shall be conclusive absent manifest error.

         Section 14.02. Increased Costs. The Co-Borrowers shall reimburse the
Lender on demand for all costs incurred and reductions in amounts received or
receivable, as reasonably determined by the Lender, that are attributable to the
Advances or the performance by the Lender of its obligations under this
Agreement and that occur by reason of the promulgation after the date hereof of
any law, regulation or treaty or any change therein or in the interpretation
thereof or by reason of compliance by the Lender with any direction, requirement
or request (whether or not having the force of law) of any Governmental
Authority, including, without limitation, any such cost or reduction resulting
from the imposition or amendment of any reserve, special deposit or similar
requirement against assets of, liabilities of, deposits with or for the account
of, or loans by, the Lender. The Lender shall have a duty to mitigate all such
costs, including, but not limited to, a duty to provide an alternative structure
for the Advances if such alternative structure would reasonably mitigate such
costs. Upon request of the Lender for any reimbursement pursuant to this Section
14.02, the Co-Borrowers may upon thirty (30) days prior written notice to the
Lender prepay in full the Advances of the Lender then outstanding, together with
any accrued and unpaid interest thereon and any fees required to be paid under
Section 4.03 on the next Interest Payment Date following the date the notice is
given.

                                   ARTICLE XV
                                  MISCELLANEOUS

         Section 15.01.  Assignments; Participations.

         (a)      No Co-Borrower shall be permitted to assign this Agreement
without the prior written consent of the Lender and any purported assignment in
violation of this Section 15.01(a) shall be null and void.

         (b)      The Lender shall be permitted to assign, or sell participation
interests in, the Facility (or any portion thereof) or any Notes issued
hereunder to any Eligible Assignee without the prior approval of any Co-Borrower
or the Guarantor.

MIA1 #1016002.v8                       61                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   69

                                EXECUTION COPY

         (c)      Following any assignment made in accordance with Section
15.01(b), the Eligible Assignee shall be deemed the "Lender" for all purposes
hereunder or, if there is more than one Lender following such assignment, the
Lender and each Eligible Assignee shall be deemed a Lender in such proportions
as shall be specified in the related assignments.

         Section 15.02. Successors and Assigns; Remedies Cumulative. This
Agreement shall be binding upon and inure to the benefit of the Parties and
their respective successors and permitted assigns. The rights and remedies of
the Lender under this Agreement are cumulative, and are in addition to and not
in substitution for any rights or remedies provided by law. Any single or
partial exercise by the Lender of any right under this Agreement, or any failure
to exercise or delay in exercising any such rights, shall not be or be deemed to
be a waiver of, or to prejudice any other rights or remedies to which the Lender
may be entitled for any Event of Default or Default. Any waiver by the Lender of
the strict compliance with any term of this Agreement or any related document
shall not be deemed to be a waiver of any subsequent default.

         Section 15.03. Notices. Every notice, demand, request, consent, waiver
or agreement (collectively, "Notices" and individually a "Notice") under this
Agreement shall be in writing, and in English, English being the governing
language of this Agreement. All documents shall be hand-delivered or sent by
prepaid international courier or by telefax to the following address:

for the Co-Borrowers,

IMPSAT S.A.
Alferez Pareja 256
1107 Buenos Aires
Argentina
Tel: (54-11) 5170-0000
Fax: (54-11) 5170-6900

* * *
IMPSAT Comunicacoes Ltda.
Rua Eid Mansur 666
Parque Sao Jorge - COTIA (SP)
CEP 06700-000
Brazil
Tel: (55-11) 3444-6000
Fax: (55-11) 3444-6000

* * *
IMPSAT S.A.
Diagonal 126 N(o)67-19
Bogota. D.C.

MIA1 #1016002.v8                       62                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   70

                                EXECUTION COPY

Colombia
Tel: (57-1) 433-6066
Fax: (57-1) 433-5968

* * *
IMPSATEL Del Ecuador S.A.
Urbanizacion Inaquito Alto
Calle (Oe-9) Juan Diaz N37-111
Quito - Ecuador
Tel: (593 2) 264 101
Fax: (593 2) 465 066

* * *
Telecomunicaciones IMPSAT, S.A.
Edificio IMPSAT
Calle 9, entre 4ta.y 5ta. Transversal
Sector Sur, Manzana B-8, La Urbina
Caracas 1070
Venezuela
Tel: (58-2) 243-5044
Fax: (58-2) 241-6948

for the Guarantor,

IMPSAT FIBER NETWORKS, INC.
Dellepiane 150, piso 9
C1107 BCA Buenos Aires, Argentina
Tel: (54-11) 5170-3545
Fax:(54-11) 5170-3520

For the Lender,

         For Notices relating to Guarantor, IMPSAT, S.A. (Argentina), IMPSAT
         S.A. (Colombia), IMPSATEL Del Ecuador, SA (Ecuador), or
         Telecomunicaciones IMPSAT, S.A. (Venezuela) to:

Paul Hare
Credit Manager
Harris Corporation
Microwave Communications Division
3 Hotel de Ville
Dollard-des- Ormeaux,
Quebec, Canada

MIA1 #1016002.v8                       63                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   71

                                EXECUTION COPY

H9B 3G4
Phone: (514) 421-8427
Fax: (514) 421-2952

         For Notices relating to IMPSAT Comunicacoes  Ltda. (Brazil) to:

Isabela Teixeira Mendes
Sales Finance Manager
Harris do Brasil Ltda
Estrada da Aldeinha, 400
06465-100 - Barueri/SP - Brazil
Phone: (55 11) 41973278
Fax: (55 11) 41973001
For all Notices, a copy to:

Marie Wilson, Esq.
Division Counsel
Harris Corporation, Microwave Communications Division
350 Twin Dolphin Drive
Redwood Shores, CA 94065
Phone: (605) 594-3218
Fax: (650) 594-3345

or such other mailing address or telefax number as to which the Co-Borrowers and
the Guarantor, or the Lender may, for itself, from time to time notify the other
Parties. Documents sent by telefax will be deemed received by the recipient the
second business day after transmission (except with respect to telefaxes sent
pursuant to Section 13.02, which shall be deemed to have been received on the
date sent). For the purposes of this Agreement "in writing", includes printing,
typewriting, or any electronic transmission that can be reproduced as written
text, on paper, at the point of reception.

         Section 15.04. Entire Agreement. This Agreement, the Notes, the
Guaranty Agreement and the Security Documents contain the entire agreement
between the Parties relating to the subject matter hereof and supersede all oral
statements and prior writings with respect thereto.

         Section 15.05. Conflicts. In the event that the terms of this Agreement
conflict with the terms of any of the other Credit Documentation, the terms of
this Agreement shall control.

MIA1 #1016002.v8                       64                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   72

                                EXECUTION COPY

         Section 15.06. Modification. No change or modification of this
Agreement shall be of any force unless such change or modification is in writing
and has been signed by all the Parties.

         Section 15.07. Judgment Currency. The obligation under this Agreement
to make payments in Dollars shall not be discharged or satisfied by any payment
or recovery pursuant to any judgment expressed in or converted into any other
currency except to the extent of the amount of Dollars that is actually received
by the Lender as a result of such payment or recovery. Accordingly, the
Obligations and their payment in Dollars shall be enforceable as an alternative
or additional cause of action for the purpose of recovery in such other currency
of the amount by which such actual receipt by the Lender falls short of the full
amount of Dollars payable under this Agreement, and such obligation shall not be
affected by judgment being obtained for any other sums due under this Agreement.

         Section 15.08. Severability. If any provision of this Agreement shall
be held to be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

         Section 15.09. Further Assurances. Each of the Co-Borrowers and the
Guarantor shall execute such deeds, assignments, endorsements and other
instruments and documents and shall give such further assurances as shall be
necessary to perform its obligations hereunder.

         Section 15.10. Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK, UNITED
STATES OF AMERICA, WITHOUT REFERENCE TO PRINCIPLES OR CONFLICTS OF LAW OTHER
THAN SECTION 5-1401 AND SECTION 5-1402 OF THE NEW YORK GENERAL OBLIGATIONS LAW.

         Section 15.11. Jurisdiction. Each Co-Borrower and the Guarantor
irrevocably submit to the jurisdiction of the courts of the State of New York
sitting in the Borough of Manhattan and of the United States sitting in the
Southern District of New York, and of the courts of their own respective
corporate domiciles with respect to actions or proceedings brought against any
Co-Borrower or the Guarantor, as the case may be, as a defendant, for purposes
of all legal proceedings arising out of or relating to this Agreement or the
transactions contemplated hereby (a "Proceeding"). Each Co-Borrower and the
Guarantor irrevocably waive, to the fullest extent permitted by law, any
objection which they may now or hereafter have to the laying of venue of any
Proceeding and any claim that any Proceeding has been brought in an inconvenient
forum. Any process or summons for purposes of any Proceeding may be served on
any Co-Borrower or the Guarantor, as the case may be, by mailing a copy thereof
by registered mail, or a form of mail substantially equivalent thereto,
addressed to such Party at its address as provided for Notices hereunder (or at
the address of such Party's Process Agent).

MIA1 #1016002.v8                       65                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   73

                                EXECUTION COPY

         Section 15.12. Appointment of Agent. The Co-Borrower hereby irrevocably
appoints the Process Agent as its authorized agent to accept and acknowledge on
its behalf service of any and all process which may be served in any Proceeding.
Such designation and appointment shall be irrevocable until all principal of and
interest on the Advance and other sums payable hereunder shall have been paid in
full in accordance with the provisions thereof. Each of the Co-Borrowers
covenants and agrees that it shall take any and all reasonable action, including
the execution and filing of any and all documents, that may be necessary to
continue the foregoing designations and appointments in full force and effect
and to cause the Process Agent to continue to act in such capacity.

         Section 15.13. Waiver of Jury Trial. EACH CO-BORROWER AND THE GUARANTOR
HEREBY IRREVOCABLY WAIVE ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL
PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY.

         Section 15.14. Waiver of Immunity. To the extent that any Co-Borrower
or the Guarantor has or hereafter may be entitled to claim or may acquire, for
itself or any of its assets, any immunity from suit, jurisdiction of any court
or from any legal process (whether through service or notice, attachment prior
to judgment, attachment in aid of execution, or otherwise) with respect to
itself or its property, it hereby irrevocably waives such immunity in respect of
its obligations hereunder, under the Notes, the Guaranty Agreement and (in the
case of each Co-Borrower) under the Security Documents to the extent permitted
by Applicable Law and, without limiting the generality of the foregoing, agrees
that the waivers set forth in this Section 15.14 shall be effective to the
fullest extent now or hereafter permitted under the Foreign Sovereign Immunities
Act of 1976 of the United States and are intended to be irrevocable for the
purposes of such Act.

         Section 15.15 Indemnification. The Co-Borrowers, and the Guarantor
shall indemnify, defend and hold the Lender harmless from and against any and
all liabilities, obligations, losses, damages, penalties, actions, judgments,
suits, costs, charges, expenses and disbursements (including attorneys' fees and
all goods, services, value added consumption sales, use or similar tax
applicable to costs, charges, expenses and disbursements) of any kind or nature
whatsoever which may at any time (including at any time following repayment of
the Facility) be imposed on, incurred by or asserted against the Lender arising
out of this Agreement or any other Credit Documentation, or the transactions
contemplated hereby or any action taken or admitted by the Lender under or in
connection with the foregoing, including with respect to any investigation,
litigation or proceeding (including any insolvency proceeding or appellate
proceeding) related to or arising out of this Agreement or the Facility, whether
or not the Lender is a party thereto (all of the foregoing, collectively the
"Indemnified Liabilities"); provided, that the Co-Borrowers shall have no
obligation hereunder to the Lender with respect to Indemnified Liabilities
resulting from the gross negligence or willful

MIA1 #1016002.v8                       66                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   74

                                EXECUTION COPY

misconduct of the Lender. The agreements in this section shall survive payment
of all other indebtedness.

         Section 15.16 Counterparts. This Agreement may be executed in any
number of counterparts, each of which shall be deemed an original, but all of
which shall constitute one and the same instrument. At least one copy of this
Agreement shall include the signatures of all of the Parties.

         Section 15.17. Limitation on Rights of Others. No Person other than a
Party shall have any legal or equitable right, remedy or claim under or in
respect of this Agreement.

         Section 15.18. No Partnership. Nothing in this Agreement, the Guaranty
Agreement, the Security Documents, the Supply Contract(s) or the Notes shall be
read to create any agency, partnership or joint venture of the Lender (or any of
its Affiliates) and the Co-Borrowers (or any of their respective Affiliates).

         Section 15.19. Consequential Damages. THE LENDER SHALL NOT BE LIABLE
FOR ANY INDIRECT, CONSEQUENTIAL OR PUNITIVE DAMAGES IN CONNECTION WITH ITS
ACTIVITIES PURSUANT TO THE FACILITY, THE NOTES OR THE SECURITY DOCUMENTS.

         Section 15.20. Independent Counsel. Each Party confirms that it has
used its own independent counsel in the negotiation, preparation, execution and
delivery of the Credit Documentation.

         Section 15.21. Alternative Financing for IMPSAT Comunicacoes Ltda.
(Brazil). The Lender is prepared to consider financing Advances to IMPSAT
Comunicacoes Ltda. (Brazil) by, through or in association with a Brazilian bank
or other financial institution; provided that the Guarantor has agreed to
provide its Guaranty under such financing on the same terms as set forth under
Article XII hereof and the Lender is satisfied that the required governmental
authorizations in respect of such financing may be expeditiously obtained for
payment by such Co-Borrower of all amounts due and payable under such financing
in Dollars.

         Section 15.22. Section Headings; Table of Contents. Section and article
headings used herein and the table of contents are for convenience of reference
only and are not to affect the construction of, or to be taken into
consideration in interpreting, this Agreement.

         Section 15.23. Time is of the Essence. Time is of the essence of this
Agreement and no extension or variation of this Agreement shall operate as a
waiver of this provision.

         Section 15.24 Confidentiality. Each of the Parties hereby agrees to
maintain the confidentiality of Information (as defined below), except that
Information may be disclosed (a) to its Affiliates, directors, officers,
employees and professional advisors, including accountants, legal counsel and
other advisors (it being understood that the Persons to whom

MIA1 #1016002.v8                       67                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   75

                                EXECUTION COPY

such disclosure is made will be informed of and will agree to be bound by this
confidentiality provision), (b) to the extent requested by any regulatory
authority, (c) to the extent required by Applicable Law including in connection
with a public offering of equity or debt securities of any of the Co-Borrowers
or the Guarantor or by any subpoena or similar legal process, (d) to any other
party to this Agreement; (e) in connection with the exercise of any remedies
hereunder or any suit, action or proceeding relating to this Agreement or the
enforcement of rights hereunder, (f) subject to the execution and delivery of an
agreement containing provisions substantially the same as those of this Section
15.24, to any assignee of or participant in, or any prospective assignee of or
participant in, any of its rights or obligations under this Agreement, (g) with
the consent of the Lender and the Guarantor, or (h) to the extent such
Information (1) becomes publicly available other than as a result of a breach of
this Section 15.24 or (2) becomes available to such party on a non-confidential
basis from a source other than the other Parties.

         For the purpose of this Section 15.24, "Information" means all
information received from any of the Parties relating to any of the Lender, the
Co-Borrowers, the Guarantor of their respective businesses or Affiliates, other
than any such information that is available to the Parties on a non-confidential
basis prior to disclosure by any Party. Any Person required to maintain the
confidentiality of Information as provided in this Section 15.24 shall be
considered to have complied with its obligation to do so if such Person has
exercised the same degree of care to maintain the confidentiality of such
Information as such Person would accord to its own confidential information.

         IN WITNESS WHEREOF, this Agreement shall be effective as of the opening
of business on the day and year first above written.

                       [SIGNATURES BEGIN ON THE NEXT PAGE]

MIA1 #1016002.v8                       68                 MASTER LOAN AGREEMENT

<TABLE>
<CAPTION>
 HARRIS          IMPSAT           IMPSAT          IMPSAT         IMPSATEL       Telecomunicaciones       IMPSAT
 CANADA,          S.A.         Comunicacoes        S.A.            Del               IMPSAT              FIBER
  INC.         (Argentina)        Ltda.         (Colombia)     Ecuador S.A.           S.A.              NETWORKS
                                                                                                          INC.
<S>            <C>             <C>              <C>            <C>              <C>                    <C>

----------     ----------       ----------      ----------      ----------         ----------          ----------
</TABLE>

<PAGE>   76

                                 EXECUTION COPY

                                      IMPSAT S.A. (Argentina)

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location:  Buenos Aires, Argentina                        Date:
                                                                --------------

I _______________________ acting as authorizing notary public _______________
   Name of Notary Public                                       Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

-------------------------------.
Title and Authorizing Documents

MIA1 #1016002.v8                   S-1                    MASTER LOAN AGREEMENT

<PAGE>   77

                                EXECUTION COPY

                                      IMPSAT COMUNICACOES LTDA.
                                      (Brazil)

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location:  Buenos Aires, Argentina                            Date:
                                                                    -----------

I _______________________ acting as authorizing notary public _________________
   Name of Notary Public                                       Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

--------------------------------.
Title and Authorizing Documents

MIA1 #1016002.v8                   S-2                    MASTER LOAN AGREEMENT

<PAGE>   78

                                EXECUTION COPY

                                      IMPSAT S.A. (Colombia)

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location: Buenos Aires, Argentina                             Date:
                                                                    ------------

I _______________________ acting as authorizing notary public __________________
   Name of Notary Public                                         Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

-------------------------------.
Title and Authorizing Documents

MIA1 #1016002.v8                   S-3                    MASTER LOAN AGREEMENT

<PAGE>   79

                                EXECUTION COPY

                                      IMPSATEL DEL ECUADOR SA (Ecuador)

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location: Buenos Aires, Argentina                             Date:
                                                                    -----------

I _______________________ acting as authorizing notary public _________________
   Name of Notary Public                                         Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

-------------------------------.
Title and Authorizing Documents

MIA1 #1016002.v8                   S-4                    MASTER LOAN AGREEMENT

<PAGE>   80

                                EXECUTION COPY

                              TELECOMUNICACIONES IMPSAT S.A. (Venezuela)

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location: Buenos Aires, Argentina                    Date:
                                                           --------------

I _______________________ acting as authorizing notary public _________________
   Name of Notary Public                                        Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

--------------------------------.
Title and Authorizing Documents

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<PAGE>   81

                                EXECUTION COPY

                                       IMPSAT FIBER NETWORKS, INC.

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

Location: Buenos Aires, Argentina                             Date:
                                                                    ------------

I _______________________ acting as authorizing notary public __________________
   Name of Notary Public                                         Register No.
hereby certify that the attached documents have been signed before me by
_______________________ to me know and that the person referred to above act as
    Name and ID No.

-------------------------------.
Title and Authorizing Documents

MIA1 #1016002.v8                   S-6                    MASTER LOAN AGREEMENT

<PAGE>   82

                                EXECUTION COPY

                                         HARRIS CANADA, INC.

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

WITNESSES:

---------------------------------------------
Name:
      ---------------------------------------

---------------------------------------------
Name:
     ----------------------------------------

State of California          )
                             ) ss.
County of San Mateo)

On _______________________ before me, ___________________________________
                                            (Name & Title of Officer)
personally appeared _____________________________________________________,
                                    (Name of Signer)
personally known to me to be the person whose name is subscribed to the within
instrument and acknowledged to me that he executed the same in his authorized
capacity, and that by his signature on the instrument the person, or the entity
upon behalf of which the person acted, executed the instrument.

                                       WITNESS my hand and official seal.

                                       -------------------------------------
                                            Signature Notary Public

MIA1 #1016002.v8

MIA1 #1016002.v8                   S-7                    MASTER LOAN AGREEMENT

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