Document:

<PAGE>   1
                                                                     EXHIBIT 4.3

NUMBER                                                              SHARES
  C -                                                           COMMON STOCK

                                             SEE REVERSE FOR CERTAIN DEFINITIONS

                          [LOGO OF IMPSAT FIBER NETWORKS, INC.]
                   INCORPORATED UNDER THE LAWS OF THE STATE OF
                                  DELAWARE                     CUSIP 45321T103

THIS CERTIFIES that

is the record holder of

FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK, $0.01 PAR VALUE PER SHARE,
OF

                          IMPSAT FIBER NETWORKS, INC.

transferable on the share register of the Corporation in person or by a duly
authorized attorney upon surrender of this Certificate properly endorsed. This
Certificate is not valid unless countersigned by the Transfer Agent and
registered by the Registrar.

WITNESS the facsimile seal of the Corporation and the facsimile signatures of
its duly authorized officers.

Dated:

COUNTERSIGNED AND REGISTERED:
                                              [Signature of Authorized Officer]

                                [CORPORATE SEAL]
[BANK NAME]

    TRANSFER AGENT AND
    REGISTRAR

                                              [Signature of Authorized Officer]
<PAGE>   2

This certificate also evidences and entitles the holder hereof to certain Rights
as set forth in the Rights Agreement between IMPSAT Fiber Networks, Inc. (the
"Company") and The Bank of New York (the "Rights Agent") dated as of _______,
2000 (the "Rights Agreement"), the terms of which are hereby incorporated herein
by reference and a copy of which is on file at the principal offices of the
Company. Under certain circumstances, as set forth in the Rights Agreement, such
Rights will be evidenced by separate certificates and will no longer be
evidenced by this certificate. The Company will mail to the holder of this
certificate a copy of the Rights Agreement, as in effect on the date of mailing,
without charge promptly after receipt of a written request therefor. Under
certain circumstances set forth in the Rights Agreement, Rights issued to, or
held by, any Person who is, was or becomes an Acquiring Person, an Adverse
Person or any Affiliate or Associate thereof (as such terms are defined in the
Rights Agreement), whether currently held by or on behalf of such Person or by
any subsequent holder, may become null and void.

                            [Reverse of Certificate]

                          IMPSAT FIBER NETWORKS, INC.

         A statement of the powers, designations, preferences and relative,
participating, optional or other special rights of each class of stock or series
thereof and the qualifications, limitations or restrictions of such preferences
and/or rights as established, from time to time, by the Certificate of
Incorporation of the Corporation and by any certificate of designation, the
number of shares constituting each class and series, and the designations
thereof, may be obtained by the holder hereof upon request and without charge at
the principal office of the Corporation.

         The following abbreviations, when used in the inscription on the face
of this Certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

     TEN COM  - as tenants in common
     TEN ENT  - as tenants by the entireties
     JT TEN   - as joint tenants with right
                of survivorship and not as
                tenants in common

UNIF GIFT MIN ACT -                Custodian
                     ---------                    --------------
                       (Cust)                        (Minor)
                          under Uniform Gifts to Minors
                                  Act
                                        ---------------------
                                              (State)

         Additional abbreviations may also be used though not in the above list.

         For value received,           hereby sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
      IDENTIFYING NUMBER OF ASSIGNEE
------------------------------------------------------------

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

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

-------------------------------------------------------------------------------
   PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE

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

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

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shares of the capital stock represented by the within Certificate, and does
hereby irrevocably constitute and appoint

--------------------------------------------------------------------- as
Attorney to transfer the said stock on the books of the within named Corporation
with full power of substitution in the premises.

Dated:
       --------------------------------

                                        ---------------------------------------
                                        Signature

                                        NOTICE: The signature to this assignment
                                        must correspond with the name as written
                                        upon the face of this Certificate in
                                        every particular, without alteration or
                                        enlargement or any change whatever.

                                        Signature(s) Guaranteed:

                                        By

                                        THE SIGNATURE MUST BE GUARANTEED BY AN
                                        ELIGIBLE GUARANTOR INSTITUTION (BANKS,
                                        STOCKBROKERS, SAVINGS AND LOAN
                                        ASSOCIATIONS AND CREDIT UNIONS WITH
                                        MEMBERSHIP IN AN APPROVED SIGNATURE
                                        GUARANTEE MEDALLION PROGRAM), PURSUANT
                                        TO S.E.C. RULE 17Ad-15.<PAGE>   1
                                                                    EXHIBIT 10.4

                                 US$149,100,000

                               FINANCING AGREEMENT

                          DATED AS OF OCTOBER 25, 1999

                                  BY AND AMONG

                                   IMPSAT S.A.

                                  AS BORROWER,

                          NORTEL NETWORKS CORPORATION,

                            AS ADMINISTRATIVE AGENT,

                          NORTEL NETWORKS CORPORATION,

                               AS COLLATERAL AGENT

                                       AND

                   THE LENDERS PARTY HERETO FROM TIME TO TIME

                                   AS LENDERS

<PAGE>   2

                               FINANCING AGREEMENT

THIS FINANCING AGREEMENT, dated as of this October 25, 1999 (this "AGREEMENT"),
by and among IMPSAT S.A., a corporation (sociedad anonima) organized pursuant to
the laws of the Republic of Argentina (the "BORROWER"); NORTEL NETWORKS
CORPORATION ("NORTEL"), a corporation organized pursuant to the laws of the
Province of Ontario, Canada, as administrative agent (the "ADMINISTRATIVE
AGENT"); Nortel as collateral agent (the "COLLATERAL AGENT"); and the several
lenders party hereto from time to time, as lenders (together with Nortel, the
"LENDERS").

                              W I T N E S S E T H:

       WHEREAS, (i) the Borrower, Nortel Networks de Argentina S.A. ("NORTEL
ARGENTINA") and Nortel have entered into a Turnkey Project Agreement dated as of
September 6, 1999 (the "TURNKEY CONTRACT") and (ii) Nortel and IMPSAT (as
defined hereinbelow) are currently negotiating the terms of a supply agreement
(the "SUPPLY AGREEMENT") (the Turnkey Contract and the Supply Agreement,
collectively, the "NORTEL CONTRACTS") pursuant to which the Borrower will
purchase telecommunications equipment and/or services manufactured or supplied
by Nortel or its Affiliates related to the design, procurement, installation,
commissioning, and operation of a broadband telecommunications network in
Argentina (the "PROJECT");

       WHEREAS, the Borrower has requested that the Lenders make available to
the Borrower under the terms and conditions hereof a credit facility in a
principal amount not to exceed one hundred forty nine million one hundred
thousand Dollars (US$149,100,000) to finance the purchase of products and
services under the Turnkey Contract and the Supply Agreement;

       WHEREAS, the Borrower is a Subsidiary of IMPSAT Corporation, a
corporation organized pursuant to the laws of the State of Delaware, U.S.A.
("IMPSAT");

       WHEREAS, as a material inducement to the Lenders to extend the credit
under this Agreement, IMPSAT has agreed to guarantee the obligations of the
Borrower to the Lenders under this Agreement and to make certain agreed equity
contributions to the Borrower;

       WHEREAS, concurrently herewith, the Parties other than the Borrower have
entered into a financing agreement (the "BRAZIL FINANCING AGREEMENT") with the
Borrower's Affiliate, IMPSAT Comunicacoes Ltda., a company organized pursuant to
the laws of Brazil ("IMPSAT BRAZIL"), to finance the purchase of products and
services under the Turnkey Project Agreement dated September 6, 1999 among
IMPSAT Brazil, Nortel and Northern Telecom do Brasil Comercio e Servicos Ltda.
("NORTEL BRAZIL") (the "BRAZIL TURNKEY CONTRACT") and together with the Supply
Agreement, the "BRAZIL NORTEL CONTRACTS");

       WHEREAS, the Lenders are willing to provide the credit facility requested
by the Borrower upon the terms and subject to the conditions hereinafter set
forth;

                                      -1-
<PAGE>   3

       NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, receipt of which is hereby acknowledged, the Parties
agree as follows:

                             SECTION 1. DEFINITIONS.

SECTION 1.1 DEFINED TERMS.

       The following capitalized terms shall have the meanings set forth in this
Section 1.1 when used in this Agreement, including its preamble and recitals:

       "AFFILIATE" means, as to any Person, any other Person Controlled by,
Controlling, or under common Control with, such Person.

       "AGENTS" means the Administrative Agent and the Collateral Agent.

       "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
(including any Environmental Laws).

       "APPLICABLE PERMITS" means the Applicable Permits as defined in the
Turnkey Contract.

       "ARGENTINA" means the Republic of Argentina.

       "ARGENTINE GAAP" means generally accepted accounting principles in
Argentina as established from time to time by the Consejo Profesional de
Ciencias Economicas.

       "ASSIGNMENT AND ASSUMPTION AGREEMENT" means an assignment and assumption
agreement between a Lender and an Eligible Assignee, and accepted by the
Administrative Agent, substantially in the form of Exhibit A.

       "AUTHORIZED OFFICER" means, with respect to any Person, each of the
following officers of such Person: (a) the Chief Executive Officer; (b) the
Chief Operating Officer; or (c) the Chief Financial Officer.

       "BORROWER BUSINESS PLAN" means the 10-year consolidated Business Plan of
the Borrower dated August 31, 1999 and not including any amendments, supplements
or replacements thereof (except as contemplated by Section 6.2(l)).

       "BORROWER'S NET DEBT" means, on any date, (a) the Borrower's Total Debt
outstanding on such date; minus (b) the amount of the Borrower's Quasi
Equity outstanding on such date; minus (c) the aggregate amount of cash and
Temporary Cash Investments of the Borrower and its Subsidiaries that are subject
to a Lien in favor of the Lenders pursuant to the Security Documents.

                                      -2-
<PAGE>   4

       "BRAZIL" means the Federative Republic of Brazil.

       "BRAZIL AGREEMENTS" means, collectively, the Financing Documents as
defined in the Brazil Financing Agreement and the Brazil Nortel Contracts.

       "BRAZIL EQUIPMENT PLEDGE AGREEMENT" means the Equipment Pledge Agreement
as defined in the Brazil Financing Agreement.

       "BRAZIL ESCROW ACCOUNT AGREEMENT" means the Escrow Account Agreement as
defined in the Brazil Financing Agreement.

       "BRAZIL GUARANTEE" means the IMPSAT Guarantee as defined in the Brazil
Financing Agreement.

       "BRAZIL MORTGAGE DEEDS" means the Mortgage Deeds as defined in the Brazil
Financing Agreement.

       "BRAZIL PLEDGED SHAREHOLDER NOTE" means a Pledged Shareholder Note as
defined in the Brazil Financing Agreement.

       "BRITISH TELECOM" means British Telecommunications plc, a corporation
organized pursuant to the laws of the United Kingdom.

       "BUSINESS DAY" means a day other than a Saturday, Sunday, or any other
day on which commercial banks in New York City, United States of America, and
the City of Buenos Aires, Argentina are authorized or required by Applicable Law
to close.

       "BUSINESS PLANS" means, collectively, the Borrower Business Plan and the
IMPSAT Business Plan.

       "CAPITAL ADEQUACY REGULATION" means any guideline, request or directive
of any central bank or other Governmental Authority, or any other Applicable
Law, whether or not having the force of law, in each case of general
applicability regarding capital adequacy of banks and branches thereof or
corporations controlling banks.

       "CAPITAL EXPENDITURES" means, with respect to any Person for any period,
the additions to property, plant and equipment and other capital expenditures of
such Person and its Subsidiaries for such period, as the same are or would be
set forth in a consolidated statement of cash flows of such Person and its
Subsidiaries for such period.

       "CAPITAL STOCK" means, with respect to any Person, all shares, interests,
rights to purchase, warrants, options, or other equivalents of or interests in
the common or preferred equity of such Person.

       "CENTRAL BANK" means the Banco Central de la Republica Argentina.

       "CHANGE OF CONTROL" means an event or circumstance as a result of which:
(i) (a) prior to the occurrence of a Public Market, a "person" or "group"
(within the meaning of Sections 13(d)

                                      -3-
<PAGE>   5

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 a
greater percentage of the total voting power of the Voting Stock of IMPSAT, on a
fully diluted basis, than is beneficially owned by the Existing Stockholders on
such date and (b) after the occurrence of a Public Market, 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 thirty percent (30%) of the total
voting power of the Voting Stock of IMPSAT on a fully diluted basis and such
ownership represents a greater percentage of the total voting power of the
Voting Stock of IMPSAT, on a fully diluted basis, than is held by the Existing
Stockholders on such date; (ii) individuals who on the date hereof constitute
the board of directors of IMPSAT (together with any new directors whose election
by the board of directors or whose nomination for election by IMPSAT's
stockholders was approved by a vote of at least two-thirds of the members of the
board of directors of IMPSAT then in office who either were members of the board
of directors of IMPSAT on the date hereof or whose election or nomination for
election was previously so approved) cease for any reason to constitute a
majority of the members of the board of directors of IMPSAT then in office;
(iii) IMPSAT is the "beneficial owner" of less than fifty percent (50%) of the
Voting Stock of the Borrower; or (iv) any of the Indebtedness outstanding under
either of the IMPSAT Indentures is redeemed by IMPSAT prior to its stated
maturity date as a result of a "Change of Control" (as such term is defined in
the respective IMPSAT Indenture) in accordance with the terms of the respective
IMPSAT Indenture.

       "CHARTER DOCUMENTS" means, with respect to any Person (other than an
individual), its founding act, charter, certificate of incorporation, by-laws,
memorandum and articles of association, estatutos sociales and other similar
documents regarding its organization or constitution.

       "CLOSING DATE" means November 5, 1999 or such other date as the Parties
may agree.

       "COMMITMENT" means, with respect to each Lender, such Lender's obligation
to lend its proportional share of the Commitment Amount, subject to the terms
and conditions hereof.

       "COMMITMENT AMOUNT" means an amount equal to one hundred forty nine
million one hundred thousand Dollars (US$149,100,000) to be used as provided in
Section 2.2. as such amount is reduced by Disbursements and may be reduced from
time to time pursuant to Section 2.5 or otherwise in accordance with this
Agreement; provided, however, that during the last six (6) months of the
Commitment Period, the Commitment Amount shall be limited to the amount, if any,
that has not theretofore been disbursed for payments of Invoices under the
Supply Agreement pursuant to Section 2.2(ii).

       "COMMITMENT PERIOD" means the period commencing on the date hereof and
ending on the Commitment Termination Date.

       "COMMITMENT TERMINATION DATE" means the earliest of (a) the date six (6)
months following the second (2nd) anniversary of the date hereof; (b) the first
date on which the sum of

                                      -4-
<PAGE>   6

all Disbursements equals the Commitment Amount; and (c) the date of termination
of the Commitment pursuant to Section 10.2(a).

       "CONSOLIDATION DATE" means the date six (6) months after the date of this
Agreement (being the same day of the calendar month) and each successive date
that is six (6) calendar months thereafter (being the same day of the calendar
month), provided, that if such date is not a Business Day, the next succeeding
Business Day unless it falls in the next calendar month, in which case the
Consolidation Date shall be the Business Day immediately preceding such date.

       "CONTROL" means: (a) the beneficial ownership of more than fifty percent
(50%) of the total Voting Stock then outstanding of a Person; or (b) even if
less than such percentage of outstanding Voting Stock is owned, the power to
direct the management and policies of such Person, directly or through one or
more intermediaries, whether through the ownership of voting securities, by
contract, or otherwise.

       "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 premium, 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 clauses (b) and (c) 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 event, occurrence, factual or legal condition which,
if continued uncured or unchanged would, with the passage of time or the giving
of notice or both, become or constitute an Event of Default.

       "DEFAULT INTEREST RATE" means an interest rate per annum equal to (i) the
interest rate then in effect under Section 3.3(a), plus (ii) two hundred fifty
(250) basis points.

       "DISBURSEMENT" means any disbursement of Loan proceeds by the Lenders
hereunder.

       "DISBURSEMENT DATE" means the date on which a Disbursement is made in
accordance with Section 2.3.

       "DISBURSEMENT REQUEST" means a requisition for a Disbursement
substantially in the form of Exhibit B, duly completed and signed by an
Authorized Officer of the Borrower.

       "DISPOSAL" means, with respect to any property of the Borrower or any
Subsidiary thereof, any direct or indirect sale, conveyance, transfer,
alienation, lease, IRU, loan, sale-and-repurchase, sale-leaseback or other
transaction or arrangement as a result of which the Borrower or Subsidiary party
to such transaction or arrangement relinquishes all or substantially all
marketable rights in and to such property; and the verb "DISPOSE OF" has a
corresponding meaning.

                                      -5-
<PAGE>   7

       "DOLLARS AND US$" means the lawful currency 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 to
the extent included in determining Net Income.

       "ELIGIBLE ASSIGNEES" means, (a) a 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
Administrative Agent and approved by the Borrower (such approval not to be
unreasonably withheld).

       "ENVIRONMENTAL LAWS" means any and all applicable statutes, laws,
judicial decisions, regulations, ordinances, rules, judgments, orders, decrees,
codes, injunctions, permits, concessions, grants, franchises, licenses,
agreements, and other governmental restrictions relating to the environment or
the effect of the environment on human health or to emissions, discharges or
release of pollutants, contaminants, Hazardous Substances, or wastes into the
environment, including (without limitation) ambient air, surface water, ground
water, or land, or otherwise relating to the manufacture, processing,
distribution, use, treatment, storage, disposal, transport, or handling of
pollutants, contaminants, Hazardous Substances, or wastes or the clean-up or
other remediation thereof.

       "ENVIRONMENTAL LIABILITIES" means all liabilities in connection with, or
relating to, the business, assets, presently or previously owned or leased
property, activities (including, without limitation, off-site disposal) or
operations of the Borrower or any of its Subsidiaries, whether vested or
unvested, contingent or fixed, actual or potential, known or unknown, which
arise under or relate to matters covered by the Environmental Laws.

       "EQUIPMENT" has the meaning ascribed to such term in the Nortel
Contracts.

       "EQUIPMENT PLEDGE AGREEMENT" means a contract of registered pledge
(contrato de prenda con registro) substantially in the form of Exhibit C to be
entered into between the

                                      -6-
<PAGE>   8

Borrower and the Collateral Agent, pursuant to which the Borrower shall pledge
Equipment to the Collateral Agent for the benefit of the Lenders, as security
for the Loans.

       "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 U.S. GAAP.

       "ESCROW ACCOUNT AGREEMENT" means an agreement substantially in the form
of Exhibit D to be entered into by and among the Borrower, the Administrative
Agent, the bank party thereto and the Escrow Agent.

       "ESCROW AGENT" means the escrow agent as defined under the Escrow Account
Agreement.

       "EVENT OF SOVEREIGN RISK" means (a) failure by the Central Bank to
exchange or to approve or permit the exchange of Pesos for Dollars, the
unavailability of Dollars in any legal exchange market in Argentina in
accordance with normal commercial practice, or any other action of any Argentine
Governmental Authority that has the effect of restricting such exchange or the
transfer of Pesos for Dollars outside Argentina and (b) a declaration of a
banking moratorium or any suspension of payments by banks in Argentina, or the
imposition by any Argentine Governmental Authority of any moratorium on the
required rescheduling of or required approval of the payment of any indebtedness
in Argentina.

       "EXCESS CASH FLOW" means, with respect to any Person, for any period: (a)
such Person's EBITDA for such period; plus (b) the Net Proceeds of any Long Term
Lease received by such Person during such period (excluding the portion, if any,
of such Net Proceeds included in EBITDA for such period); minus (c) the sum of
the following items, determined for such Person and its Subsidiaries on a
consolidated basis: (i) Debt Service for such period, (ii) Capital Expenditures
for such period (but only to the extent permitted by Section 8.3(f) or
contemplated in the IMPSAT Business Plan, as the case may be), (iii) the net
increase (or minus any net decrease) in working capital, excluding cash, from
the opening of business on the first day, to the close of business on the last
day, of such period, and (iv) taxes based upon net income payable with respect
to such period; and minus (d) the portion, if any, included in EBITDA for such
period of the Net Proceeds of any Long Term Lease received by such Person during
any prior period.

       "EXCHANGE ACT" means the U.S. Securities Exchange Act of 1934, as
amended.

       "EXISTING STOCKHOLDERS" means (i) the Individual Stockholders, (ii) the
estate or any guardian, custodian or other legal representative of any
Individual Stockholder, (iii) any foundation or similar organization organized
under Applicable Law which affords voting Control to such Individual
Stockholder, (iv) any trust for the benefit of any Individual Stockholder or his
family members which affords voting Control to such Individual Stockholder, (v)
British Telecom, and (vi) any Person in which all of the equity interests are
owned directly, or indirectly, by any of the Persons named in clauses (i)
through (v).

                                      -7-
<PAGE>   9

       "EXPROPRIATION EVENT" means: (i) any taking by condemnation,
nationalization, seizure, expropriation or other appropriation by any
Governmental Authority of all or any material portion of the Collateral, (ii)
any assumption by any Governmental Authority of control of all or any material
portion of the Collateral or the business operations of the Borrower or any of
its Subsidiaries or any of any such Person's share capital, (iii) any taking of
any action by a Governmental Authority which results in the involuntary
dissolution or disestablishment of the Borrower or any of its Subsidiaries, or
(iv) any taking of any action by any Governmental Authority that prevents the
Borrower and its Subsidiaries, taken as a whole, from carrying on their business
or operations or a material part thereof.

       "FACILITY" means the multi-drawdown, non-revolving credit facility in an
aggregate principal amount of up to the Commitment Amount provided by the
Lenders to the Borrower under this Agreement.

       "FIBER OPTIC LOAN AGREEMENT" means the loan agreement entered into
between the Borrower and the Fiber Optic Supplier.

       "FIBER OPTIC SUPPLIER" means Lucent Technologies Inc. or a wholly-owned
Subsidiary thereof.

       "FINANCING DOCUMENTS" means this Agreement, the Notes, all Assignment and
Assumption Agreements, the Security Documents, the IMPSAT Guarantee, the Pledged
Shareholder Notes, the Intercreditor Agreement, the Fiber Optic Loan Agreement
and any other instruments, documents and agreements executed by or on behalf of
the Borrower or for the benefit of the Lenders in connection with the Facility.

       "FORCE MAJEURE" means, with respect to any Person, any cause which is
beyond the reasonable control of such Person, including, without limitation, the
elements, riots, civil disturbances, wars, states of belligerency or acts of the
public enemy, labor disputes, or the laws, regulations, acts or failure to act
of any Governmental Authority.

       "GLOBAL CROSSING IRU" means the IRU granted by the Borrower to South
American Crossing Ltd. in respect of one duct on the Network between Buenos
Aires and Mendoza in accordance with Article 2 of the TAC Turnkey Construction
and IRU Agreement among the Borrower, IMPSAT S.A. (Chile) and South American
Crossing Ltd. dated September 22, 1999.

       "GOVERNMENTAL APPROVALS" means any authorization, consent, license,
approval, grant, franchise, concession, identification number, lease, ruling,
certification, exemption, action, filing, registration, permit, sanction, or
other authorization of any nature to be granted by any Governmental Authority,
as now or hereafter necessary under any Applicable Law.

       "GOVERNMENTAL AUTHORITY" means any nation or government, any state or
other political subdivision thereof (including, but not limited to, federal,
national, state, provincial, regional and municipal) and any entity exercising
executive, legislative, judicial, regulatory, or administrative authority.

                                      -8-
<PAGE>   10

       "HAZARDOUS SUBSTANCE" means any substance subject to regulation under
Environmental Laws because of its toxic, radioactive, caustic or otherwise
dangerous or hazardous qualities.

       "IMPSAT BUSINESS PLAN" means the 10-year consolidated business plan of
IMPSAT and its Subsidiaries dated August 31, 1999 and not including any
amendments, supplements or replacements thereof (except as contemplated by
Section 6.2(l)).

       "IMPSAT GUARANTEE" means a guarantee agreement to be executed by IMPSAT
in favor of the Lenders, in form and substance satisfactory to the Lenders.

       "IMPSAT INDENTURES" means the 2003 Indenture and the 2008 Indenture.

       "INDEBTEDNESS" means, with respect to any Person at any time and from
time to time, the sum, without duplication, of the following: (a) all
obligations of such Person for money borrowed (whether by loan, the issuance of
debt securities or otherwise); (b) the available amount at such time of all
letters of credit issued for the account of such Person and all outstanding
reimbursement obligations with respect thereto; (c) all liabilities or
obligations secured by any Lien on any property owned by such Person; (d) all
capitalized lease obligations; (e) all Indebtedness of others guaranteed by such
Person; (f) all obligations of such Person to pay the deferred purchase price or
acquisition price of property or services, other than Trade Payables and accrued
expenses incurred, that are not past due by more than sixty (60) days; (g) all
obligations of such Person under trade or bankers' acceptances or under
agreements providing for swaps, ceiling rates, ceiling and floor rates, or
contingent participation or other hedging mechanisms with respect to the payment
of interest; and (h) all indebtedness, liabilities and obligations of such
Person to redeem or retire shares of Capital Stock of such Person.

       "INDEPENDENT AUDITOR" means with respect to IMPSAT, Deloitte & Touche
LLP, and with respect to the Borrower, Deloitte & Touche Argentina or such other
internationally recognized firm of certified public accountants as may be
approved by the Administrative Agent.

       "INDIVIDUAL STOCKHOLDERS" means, collectively, Pescarmona, Verdaguer and
Vivo, and each an "INDIVIDUAL STOCKHOLDER".

       "INITIAL DISBURSEMENT DATE" means the date on which the first
Disbursement is made.

       "INTERCREDITOR AGREEMENT" means an agreement substantially in the form of
Exhibit E to be entered into by and among the Borrower, the Lenders, the
Administrative Agent, the Collateral Agent and the Fiber Optic Supplier.

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

       "INTEREST PAYMENT DATE" means, (a) with respect to any LIBOR Loan, the
last day of each Interest Period; and (b) with respect to any Prime Loan, the
last day of each March, June, September and December.

                                      -9-
<PAGE>   11

       "INTEREST PERIOD" means, with respect to each LIBOR Loan, each period
commencing, initially, on the Disbursement Date of such LIBOR Loan, and ending
on the next following Consolidation Date, and thereafter, commencing on the last
day of the preceding Interest Period with respect to such LIBOR Loan, and
ending, except as otherwise provided in Section 3.3 hereof, on the same day in
the sixth (6th) calendar month thereafter; provided, that,

              (a)    if any Interest Period otherwise would end on a day that is
not a Business Day, such Interest Period shall end on the next succeeding
Business Day; provided, further, that should such next succeeding Business Day
fall in the next calendar month, such Interest Period shall end on the
immediately preceding Business Day,

              (b)    any Interest Period that begins on a day for which there is
no numerically corresponding day in the calendar month at the end of such
Interest Period shall end on the last Business Day of the calendar month at the
end of such Interest Period (e.g., March 31 to September 30 for a six (6) month
Loan), and

              (c)    no Interest Period shall extend beyond the next Principal
Repayment 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.

       "IRU" means the creation of an usufructo under Argentine law of any
portion of the Network by the Borrower or any Subsidiary thereof.

       "LENDING OFFICE" means, with respect to any Lender, the office of that
Lender designated as its Lending Office by notice to the Administrative Agent
and the Borrower.

       "LIBOR" means, with respect to any Interest Period for any LIBOR Loan,
the per annum interest rate (rounded upward, if necessary, to the nearest 1/16
of one percent) equal to the arithmetic mean of the rates per annum at which
Dollar deposits are offered in an amount substantially equal to the outstanding
principal amount of the Loan and for a period approximately equal to the
duration of such Interest Period appearing on the display page designated as
page "LIBOR" on the Reuters Monitor Money Rates Service, or such other page as
may replace the LIBOR page on that service for the purpose of displaying London
Interbank Offered Rates for Dollar deposits of leading banks at or about 11:00
a.m. (London time) two (2) London business days prior to the commencement of
such Interest Period. For purposes hereof, a "LONDON BUSINESS DAY" shall mean
any day on which dealings in deposits in Dollars are conducted in the London
Euro-currency market.

       "LIBOR LOAN" means a Loan that bears interest at LIBOR.

       "LICENSES" means the Spectrum Authorization and the other licenses listed
in Schedule 7.15 and such other licenses, concessions, authorizations, permits,
or the like (including any

                                      -10-
<PAGE>   12

additions or amendments thereto) issued or granted by the SC or any other
Governmental Authority from time to time in favor of the Borrower or any of its
Subsidiaries and required for the completion of the Project, the operation of
the Network and the conduct of the Telecommunications Business.

       "LIEN" means, with respect to any Person, any security interest, lien,
pledge, mortgage, charge, or encumbrance (including any agreement to give any of
the foregoing), title retention agreement, finance lease or trust receipt, or a
consignment or bailment for security purposes, or other security arrangement or
any other arrangement on or with respect to any asset or revenue of such Person.

       "LONG TERM LEASE" means any lease or similar agreement or arrangement
pursuant to which the Borrower or a Subsidiary thereof grants the right to use
any portion of the 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.

       "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; provided, however, that clause (f) of the definition of Material
Adverse Effect shall not apply to the determination of either an Event of
Default under Section 10.1 or a condition to any Disbursement under Section
6.3(h), other than the initial Disbursement.

       "MATERIAL ADVERSE EFFECT" means a material adverse effect on (a) the
business, assets, results of operations, condition (financial or otherwise) or
prospects of the Borrower and its Subsidiaries, taken as a whole, or IMPSAT; (b)
the ability of the Borrower or IMPSAT to perform their respective obligations
under any of the Project Agreements; (c) the rights and remedies of the Lenders
or the Agents under the Financing Documents; (d) the validity or enforceability
of this Agreement or any of the other Project Agreements; (e) the Licenses or
the rights of the Borrower and its Subsidiaries thereunder; (f) Argentine, U.S.
or international loan syndication, financial or capital markets or in the
economic, political or regulatory conditions in Argentina which in the
Administrative Agent's opinion in its sole discretion could impair the
assignment or syndication of the Facility; or (g) the ability of the Lenders to
make funds available to the Borrower in Dollars.

       "MATURITY DATE" means the seventh (7th) anniversary of the date hereof.

       "MORTGAGE DEEDS" means one or more deeds pursuant to which the Borrower
or its Subsidiaries shall grant mortgages from time to time in favor of the
Collateral Agent for the benefit of the Lenders to secure the repayment of the
Loans, substantially in the form of Exhibit F.

       "NEGATIVE CASH FLOW" means, if the amount resulting from the calculation
described in the definition of Excess Cash Flow is a negative amount, such
negative amount.

       "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 U.S. GAAP.

                                      -11-
<PAGE>   13

       "NET PROCEEDS" means, with respect to any event (a) the proceeds received
in respect of such event in the form of cash and Temporary Cash Investments,
including (i) any cash received in respect of any non-cash proceeds, but only as
and when received, (ii) in the case of an insured casualty event, insurance
proceeds, and (iii) in the case of an Expropriation Event or similar event,
expropriation awards and similar payments, net of (b) the sum of (i) all
reasonable fees and out-of-pocket expenses paid by the Borrower and its
Subsidiaries to third parties other than Affiliates of Borrower (except Morgan
Stanley Dean Witter in the case of a public offering or private placement) in
connection with such event, (ii) in the case of a Disposal, the amount of all
payments required to be made by the Borrower and its Subsidiaries as a result of
such event to repay Indebtedness (other than Indebtedness secured under the
Security Documents) secured by the asset or property Disposed of or otherwise
subject to mandatory prepayment as a result of such event, (iii) the amount of
all taxes paid (or reasonably estimated to be payable) by the Borrower and its
Subsidiaries in connection with such event, and (iv) the amount of any reserves
established by the Borrower and its Subsidiaries to fund contingent liabilities
reasonably estimated to be payable, in each case during the year that such event
occurred or the next succeeding year and that are directly attributable to such
event (as determined reasonably and in good faith by the chief financial officer
of the Borrower).

       "NET PROCEEDS ACCOUNT" means the net proceeds account to be established
in accordance with the Escrow Account Agreement.

       "NETWORK" has the meaning ascribed to such term in the Turnkey Contract.

       "NOTE" means a promissory note of the Borrower, substantially in the form
of Exhibit G, provided, however, that at the request of any Lender, all Loans to
be made by such Lender may be evidenced by promissory notes of the Borrower in a
form different from Exhibit G if the purpose of such request is that such Notes
be capable of characterization as executive instruments ("titulos ejecutivos")
under Argentine law and if the alternate form of Note is approved by the Agents,
which approval shall not be unreasonably withheld.

       "OBLIGATIONS" means all present and future obligations, liabilities and
other amounts, whether or not contingent, owing to any Lender pursuant to this
Agreement or any other Financing Document, including principal, accrued interest
and fees.

       "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" means the Borrower, each Lender, the Administrative Agent and the
Collateral Agent, individually, and "PARTIES" means two (2) or more of them.

       "PERMITTED INDEBTEDNESS" means (a) Indebtedness pursuant to the Financing
Documents; (b) Indebtedness of the Borrower to IMPSAT or to any Subsidiary of
the Borrower or of any such Subsidiary to the Borrower, in each case for money
borrowed; (c) Indebtedness of the Borrower for money borrowed from financial
institutions which Indebtedness is either fully collateralized by cash deposits
of IMPSAT or fully funded by IMPSAT through the acquisition of one hundred
percent (100%) participation in such Indebtedness from such financial
institution;

                                      -12-
<PAGE>   14

(d) guarantees by the Borrower of obligations of any Subsidiary thereof or
guarantees by any such Subsidiary of obligations of the Borrower; (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 the Borrower which is in existence on the date hereof and set
forth on Schedule 7.11; (g) Quasi Equity; (h) Indebtedness for money borrowed
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 fifty million
Dollars (US$50,000,000); (i) Indebtedness for money borrowed having a stated
final maturity not earlier than the first anniversary of the Maturity Date; (j)
Indebtedness of the Borrower (A) in an amount not to exceed twelve million
Dollars (US$12,000,000) to Citibank N.A. in respect of equipment financing to be
guaranteed by Eximbank and otherwise substantially on the terms and conditions
contemplated in the letter dated August 26, 1999 from Citibank N.A., (B) in an
amount not to exceed fifteen million Dollars (US$15,000,000) under an equipment
lease facility between the Borrower and El Camino Resources de America Latina,
Inc. substantially on the terms and conditions contemplated in the letter dated
May 20, 1999 from El Camino Resources de America Latina, Inc. and (C) in respect
of guarantees by the Borrower of the Indebtedness of IMPSAT Brazil to ABN AMRO
Bank, N.V. and El Camino Resources de Latin America, Inc., permitted under the
Brazil Financing Agreement; and (k) Indebtedness incurred and applied to
refinance Indebtedness permitted by each of clauses (a), (b), (c), (f), (g),
(h), and (j) 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 the Borrower and any Subsidiary
which had incurred or guaranteed, as the case may be, the Indebtedness to be
refinanced.

       "PERMITTED INVESTMENTS" means: (a) Temporary Cash Investments; (b)
Investments in the form of inter-company Indebtedness which constitutes
Permitted Indebtedness; (c) accounts receivable owing to the 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; and (f) investments in Capital Stock of the International
Telecommunications Satellite Organization ("INTELSAT") or New Skies Satellites
N.V. ("NEW SKIES") to the extent permitted by the IMPSAT Indentures.

       "PERMITTED LIENS" means:

              (a)    Liens under the Financing Documents;

              (b)    Liens securing taxes not yet due or being contested in good
faith by appropriate proceedings for which adequate reserves determined in
accordance with Argentine

                                      -13-
<PAGE>   15

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 Argentine 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 Borrower or materially interfere with the ordinary conduct of
the business of the 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)    the shared Liens pursuant to the Intercreditor Agreement;

              (h)    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 the Borrower or a Subsidiary
thereof in the ordinary course of business, provided that such Lien secures only
the obligations of the Borrower or such Subsidiary in respect of such letter of
credit;

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

              (j)    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);

              (k)    Liens on the Borrower's interests in Intelsat and New Skies
in favor of Credit Lyonnais in an amount not to exceed nine million six hundred
thousand Dollars (US$9,600,000);

              (l)    Liens incurred or deposits made to secure the performance
of tenders, bids, leases, statutory or regulatory obligations, bankers'
acceptances, surety and appeal bonds, contracts (other than for Indebtedness),
performance and return-of-money bonds and other

                                      -14-
<PAGE>   16

obligations of a similar nature incurred in the ordinary course of business
(exclusive of obligations for the payment of borrowed money);

              (m)    Liens (including extensions and renewals thereof) upon real
or personal property, in each case other than in respect of the Network;
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;

              (n)    Liens arising from the rendering of a final judgment or
order against the Borrower or any of its Subsidiaries that does not give rise to
an Event of Default;

              (o)    Liens existing on the date hereof and listed on Schedule
7.12; and

              (p)    Liens arising (i) in respect of the Global Crossing IRU and
(ii) under any other IRU approved by the Administrative Agent under Section
8.2(j).

       "PERSON" means an individual, a partnership, a joint venture, a
corporation, a trust, a limited liability company, an unincorporated
organization or a Governmental Authority.

       "PESCARMONA" means Mr. Enrique Pescarmona.

       "PESOS" means the lawful currency of Argentina.

       "PLEDGED SHAREHOLDER NOTE" means a promissory note of the Borrower
endorsed and delivered in pledge to the Administrative Agent, in form and
substance satisfactory to the Lenders, evidencing Indebtedness of the Borrower
for money borrowed from IMPSAT, (i) the principal amount of which is payable in
a single payment not earlier than the first anniversary of the Maturity Date 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.

       "PREPAYMENT EVENT" means (a) any Disposal (other than an IRU or a Long
Term Lease) of all or part of the Network or the Collateral; (b) any
Expropriation Event; and (c) any casualty or other insured damage to any
material asset of the Borrower or any Subsidiary thereof.

       "PRIME LOAN" means a Loan that bears interest at the Prime Rate.

       "PRIME RATE" means the per annum rate of interest announced publicly from
time to time by the Toronto Dominion Bank (or such other bank as the Borrower
and the Administrative Agent may agree) as the prime rate in effect on such date
at its principal office in New York City, which rate may not be the lowest rate
of interest charged by the Toronto Dominion Bank (or such other agreed bank) to
its customers. Each change in any interest rate provided for herein

                                      -15-
<PAGE>   17

resulting from a change in the Prime Rate shall take effect on the beginning of
the day of such change in the Prime Rate.

       "PRINCIPAL REPAYMENT DATE" means, initially, the second (2nd) anniversary
of the date hereof (being the same day of the calendar month) and each
successive date that is six (6) calendar months thereafter (being the same day
of the calendar month) until the Maturity Date.

       "PROJECT AGREEMENTS" means the Financing Documents, the Nortel Contracts
and the other agreements entered into by the Borrower and its Subsidiaries in
connection with the Project, as listed in Exhibit H.

       "PROJECT PARTY" means any party to a Project Agreement.

       "PUBLIC EQUITY OFFERING" means an underwritten primary public offering of
common stock of IMPSAT pursuant to an effective registration statement under the
Securities Act.

       "PUBLIC MARKET" shall be deemed to exist if (i) a Public Equity Offering
has been consummated and (ii) at least fifteen percent (15%) of the total issued
and outstanding common stock of IMPSAT immediately prior to the consummation of
such Public Equity Offering has been distributed by means of an effective
registration statement under the Securities Act or sales pursuant to Rule 144
under Securities Act.

       "QUASI EQUITY" means the aggregate principal amount of all Pledged
Shareholder Notes or, in the case of IMPSAT Brazil, of all Brazil Pledged
Shareholder Notes.

       "REQUIRED LENDERS" means, at any time, Lenders holding more than fifty
percent (50%) in aggregate principal amount of the Loans then outstanding or, if
no Loan is outstanding, of the total Commitment Amount.

       "REVENUES" means, with respect to any Person for any period, the
consolidated revenues of such Person and its Subsidiaries.

       "SC" means the Argentine Secretariat of Communications ("Secretaria de
Comunicaciones").

       "SECURED PARTIES" means, collectively, the Agents and the Lenders, and
each a "SECURED PARTY".

       "SECURITIES ACT" means the U.S. Securities Act of 1933, as amended.

       "SECURITY DOCUMENTS" means the Mortgage Deeds, the Equipment Pledge
Agreements, the Escrow Account Agreement, and any other agreements entered into
pursuant to Section 9.

       "SPECTRUM AUTHORIZATION" means the authorization granted by the SC,
revocable in nature, to use the radioelectric spectrum in accordance with the
Argentine Telecommunications Law 19,798, as it may be amended from time to time.

       "SUBSIDIARY" means, with respect to any Person, any other Person that is
directly or indirectly Controlled by the first Person.

                                      -16-
<PAGE>   18

       "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 Argentina in which the Borrower or any of its Subsidiaries is from
time to time engaged.

       "TEMPORARY CASH INVESTMENT" means 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 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 the Borrower) 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 the Borrower or a
Subsidiary thereof and issued by any of the ten (10) largest banks (based on
assets as of the last December 31) organized under the laws of Argentina,
provided that 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, with respect to any Person at any time and from time
to time, the aggregate amount of any and all Indebtedness of such Person and its
Subsidiaries then outstanding.

       "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.

       "TRADE PAYABLES" means, with respect to any Person, any accounts payable
or any other indebtedness or monetary obligation to trade creditors created,
assumed or guaranteed by such Person or any of its Subsidiaries arising in the
ordinary course of business in connection with the acquisition of goods or
services and required to be paid within one year.

                                      -17-
<PAGE>   19

       "U.S. GAAP" means generally accepted accounting principles as adopted by
the American Institute of Certified Public Accountants, consistently applied.

       "VERDAGUER" means Mr. Ricardo Verdaguer.

       "VIVO" means Mr. Robert Vivo.

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

       "2003 INDENTURE" means the Indenture dated as of July 30, 1996 among
IMPSAT, as Issuer, the Borrower, as Guarantor, and The Bank of New York, as
Trustee, relating to the 12 1/8% Senior Guaranteed Notes due 2003 of IMPSAT.

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

SECTION 1.2 OTHER DEFINITIONS.

       The following terms shall have the meaning given to them in the Section
indicated below:

<TABLE>
<CAPTION>
TERM                                                        SECTION
<S>                                                         <C>
Administrative Agent                                        Preamble
Agreement                                                   Preamble
Bankruptcy Code                                             10.1(g)
Bonex                                                       4.2(a)
Borrower                                                    Preamble
Borrower Capital Increase                                   6.2(d)
Brazil Financing Agreement                                  Fifth Recital
Brazil Nortel Contracts                                     Fifth Recital
Brazil Turnkey Contract                                     Fifth Recital
Collateral                                                  9.1
Collateral Agent                                            Preamble
Commitment Fee                                              3.4(a)
Deferred Payment Date                                       4.2(c)
Deposit Account                                             3.6(a)
Event of Default                                            10.1
Excluded Taxes                                              5.1(a)
FRBs                                                        4.2(b)
</TABLE>

                                      -18-
<PAGE>   20

<TABLE>
<S>                                                         <C>
Funding Breakage Costs                                      5.2
IMPSAT                                                      Third Recital
IMPSAT Brazil                                               Fifth Recital
IMPSAT Capital Contribution                                 6.2(d)
Indemnitees                                                 11.2
Information                                                 16.11
Intelsat                                                    "Permitted Investments" definition
Invoices                                                    2.2
Lenders                                                     Preamble
Loan(s)                                                     2.1(a)
New Skies                                                   "Permitted Investments" definition
Nortel                                                      Preamble
Nortel Argentina                                            First Recital
Nortel Brazil                                               Fifth Recital
Nortel Contracts                                            First Recital
Note(s)                                                     2.4(a)
Par Bonds                                                   4.2(b)
Placement Agent                                             16.12
Prepayment                                                  3.2(a)
Project                                                     First Recital
Reference Dealers                                           4.2(b)
Register                                                    2.3(d)
Release                                                     9.3(b)
Released Collateral                                         9.3(b)
Release Instruments                                         9.3(b)
Release Notice                                              9.3(b)
Replacement Notes                                           13.1
Second Currency                                             4.1
Sovereign Event Deferral Period                             4.2(c)
Specified Place of Payment                                  4.1
Supply Agreement                                            First Recital
Syndication Agents                                          16.12
Taxes                                                       5.1(a)
Turnkey Contract                                            First Recital
</TABLE>

                                      -19-
<PAGE>   21

SECTION 1.3 INTERPRETATION.

       In this Agreement: (a) the singular includes the plural and the plural
the singular; (b) words importing any gender include the other gender; (c)
references to statutes or regulations are to be construed as including all
statutory or regulatory provisions consolidating, amending or replacing the
statute or regulation referred thereto; (d) references to "writing" include
printing, typing, lithography and other means of reproducing words in a tangible
visible form; (e) references to articles, sections (or subdivisions of
sections), exhibits, annexes or schedules are to this Agreement unless otherwise
indicated; (f) references to agreements and other contractual instruments shall
be deemed to include all schedules and exhibits to such agreements and all
subsequent amendments and other modifications to such agreements and contractual
instruments, but only to the extent such amendments and other modifications are
not prohibited by the terms hereof; and (g) references to Persons include their
respective permitted successors and assigns and, in the case of Governmental
Authorities, Persons succeeding to their respective functions and capacities.

SECTION 1.4 ACCOUNTING PRINCIPLES AND TERMS.

       Except as otherwise provided in this Agreement: (a) all computations and
determinations as to financial matters, and all financial statements to be
delivered under this Agreement, shall be made or prepared in accordance with
U.S. GAAP (including principles of consolidation where appropriate) applied on a
consistent basis; (b) all accounting terms used in this Agreement shall have the
meanings respectively ascribed to such terms by U.S. GAAP.

                         SECTION 2. THE CREDIT FACILITY

SECTION 2.1 LOANS.

       (a)    LENDERS' AGREEMENT TO LEND. Each Lender severally agrees, upon the
terms and conditions set forth herein, to make loans to the Borrower from time
to time during the Commitment Period, in an aggregate principal amount not to
exceed the amount of such Lender's Commitment (each such loan a "LOAN" and
collectively the "LOANS").

       (b)    FACILITY NOT REVOLVING. Each Lender's Commitment and the Facility
are not revolving in nature. Any amounts that are repaid or prepaid may not be
reborrowed, and the amount of the Facility shall be reduced by the amount of any
repayment or prepayment. The aggregate principal amount of all Loans shall not
at any time exceed the Commitment Amount.

SECTION 2.2 USE OF PROCEEDS.

       The proceeds of the Loans shall be used as follows:

              (i)    up to one hundred twenty-four million one hundred thousand
       Dollars (US$124,100,000) to pay invoices issued from time to time to the
       Borrower or its Affiliates in respect of products or services purchased
       under the Turnkey Contract;

                                      -20-
<PAGE>   22

              (ii)   up to twenty million Dollars (US $20,000,000) to pay
       invoices issued from time to time to the Borrower or its Affiliates in
       respect of products or services purchased under the Supply Agreement; and

              (iii)  up to five million Dollars (US $5,000,000) to pay invoices
       in respect of real property to be purchased for use in the Network.

       The invoices to be issued under items (i) through (iii) above are
collectively referred to as the "INVOICES".

SECTION 2.3 PROCEDURE FOR BORROWING; DISBURSEMENTS.

       (a)    DISBURSEMENTS. During the Commitment Period, the Borrower may
request a Disbursement of a Loan by delivering to the Administrative Agent a
Disbursement Request, duly completed with all required information and executed
by an Authorized Officer of the Borrower, together with copies of or proper
references or identification to the Invoices to be paid with the proceeds of
such Loan, not later than 10:00 a.m., New York time, at least three (3) Business
Days prior to the Disbursement Date requested in such Disbursement Request. Each
Disbursement Request shall specify the Disbursement Date for such Disbursement
and the principal amount to be disbursed. During any one calendar month of the
Commitment Period, the Borrower shall not request, and the Lenders shall not
make, more than one (1) Disbursement. Each Disbursement shall be in an amount of
not less than One Million Dollars (US$1,000,000).

              (1)    Upon receipt of the corresponding documentation and subject
to the limitations set forth herein, the Administrative Agent shall promptly
give each Lender notice of such proposed Disbursement, of such Lender's
proportionate share thereof and of the other matters required by Section 2.3(a)
to be specified in the Disbursement Request.

              (2)    Not later than 10:00 a.m. (New York time) on the date
specified in each Disbursement Request, each Lender shall make available in
Dollars and in immediately available funds at the office of the Administrative
Agent its pro rata share of each Disbursement requested.

              (3)    Not later than 3:00 p.m. (New York time) (to the extent of
funds actually received by the Administrative Agent at or prior to 12:00 noon),
the Administrative Agent shall disburse the funds in accordance with Section
2.3(b).

              (4)    In the event that any Lender shall fail to make available
to the Administrative Agent such Lender's portion of any Disbursement as
provided in Section 2.3(a)(2), the Administrative Agent shall disburse the funds
it has received from other Lenders pursuant to the procedures set forth in
Section 2.3(b); provided, that nothing in this Section 2.3(a)(4) shall relieve
or be deemed to relieve such defaulting Lender or any other Lender from their
respective obligations to make Loans hereunder or to prejudice any rights which
the Borrower may have against any Lender as a result of any failure by such
Lender to make Loans hereunder.

                                      -21-
<PAGE>   23

       (b)    PAYMENT. Except as otherwise provided in Section 6.2(h) and in the
Escrow Account Agreement, the proceeds of each Disbursement shall be paid for
the account of the Borrower by wire transfer of such amounts to the account
designated by Nortel or Nortel Argentina which shall be set forth in the
Disbursement Request relating to such Disbursement. The Borrower hereby
acknowledges that the Borrower shall be deemed to have received the funds upon
the disbursement by the Administrative Agent of such funds pursuant to the
procedures set forth in this Section 2.3.

       (c)    CONSOLIDATION. On each Consolidation Date, all Loans disbursed
since the immediately preceding Consolidation Date (or, in the case of the first
Consolidation Date, all Loans disbursed prior thereto) shall be consolidated
into a single Loan. To this end, the Borrower shall deliver to the
Administrative Agent, before 10:00 a.m., New York time, at least six (6)
Business Days prior to each Consolidation Date a notice of consolidation
substantially in the form of Exhibit I, which notice shall indicate the amount
of the Loans to be consolidated.

       (d)    REGISTER. The Administrative Agent shall maintain at its address a
register (the "REGISTER") on which it shall record, from time to time, the names
and addresses of the Lenders, the Commitment of each Lender, the amount of the
Loans made by each Lender and each repayment and prepayment in respect of the
Loans of each Lender. The entries made on the Register shall, to the extent
permitted by Applicable Law, be prima facie evidence of the existence and
amounts of the Obligations therein recorded, and the Borrower, the Agents and
the Lenders shall treat each Person whose name is recorded in the Register as
the owner of a Loan or Note hereunder as the owner thereof for all purposes of
this Agreement, notwithstanding any notice to the contrary; provided, however,
that the failure of the Administrative Agent to maintain the Register or any
error therein shall not in any manner affect the obligation of the Borrower to
repay (with applicable interest) the Loans of such Lender in accordance with the
terms of this Agreement. The Register shall be available for inspection by the
Borrower and any Lender at any reasonable time and from time to time upon
reasonable prior notice.

SECTION 2.4 NOTES.

       (a)    EXECUTION AND DELIVERY. The Borrower's obligation to pay the
principal of, and interest on, each Loan made by each Lender shall be evidenced
by a Note duly executed and delivered by the Borrower to the Administrative
Agent and payable to the order of the relevant Lender. Each Note shall be
entitled to the benefits of this Agreement and the other Financing Documents and
(subject to variations in form approved by the Agents as provided in the
definition of "NOTE" contained herein) shall (1) be dated the respective
Disbursement Date; (2) be in a stated principal amount equal to such Lender's
pro rata share of the requested Disbursement; (3) be payable in installments as
provided in Section 3.1; and (4) bear interest as provided in Section 3.3. The
Administrative Agent shall deliver to each Lender each Note payable to such
Lender.

       (b)    DELIVERY OF EXECUTION COPIES. By 10:00 a.m. New York time on the
day three (3) Business Days prior to each Disbursement Date and each
Consolidation Date, the Administrative Agent shall provide the Borrower with
execution copies of all Notes required to

                                      -22-
<PAGE>   24

be issued by the Borrower on such Disbursement Date or Consolidation Date which
Notes shall contain the dates, denominations and payees of the Notes evidencing
the corresponding Loans.

       (c)    FAILURE TO DELIVER EXECUTION COPIES. If the Administrative Agent
shall fail to timely deliver to the Borrower the execution copies of any Notes
required to be issued by the Borrower in accordance with Section 2.4(b), then,
notwithstanding the provisions of Section 6.3(b), the Borrower shall be required
to promptly sign and return copies of such Notes by facsimile to the
Administrative Agent and to deliver the executed originals of such Notes for the
Administrative Agent's receipt by 10:00 a.m. New York time on the day two (2)
Business Days following the receipt by the Borrower of execution copies of such
Notes.

       (d)    EXCHANGE. Notes evidencing Loans consolidated under Section 2.3(c)
shall be executed and delivered to the Administrative Agent, but shall only be
released to any Lender upon the exchange of the existing Notes held by such
Lender.

       (e)    RELEASE. Subject to Section 2.4(d), each Note shall be surrendered
to the Borrower against final payment thereof on the Maturity Date or such
earlier date as the Loans are paid in full.

       (f)    INTERPRETATION. In the event of any inconsistencies between this
Agreement and any Note, the terms of this Agreement shall control; provided,
however, that nothing in this clause (f) shall limit the rights of any Lender to
bring any action or enforce its rights or remedies under any Note.

SECTION 2.5 VOLUNTARY TERMINATION OR REDUCTION OF THE COMMITMENT.

       The Borrower may, upon not less than three (3) Business Days' (but not
more than thirty (30) days') prior notice to the Administrative Agent, terminate
or permanently reduce the Commitment Amount by an aggregate amount of ten
million Dollars (US$10,000,000) or a higher integral multiple of one million
Dollars (US$1,000,000); provided, that any such reduction or termination shall
be subject to the Administrative Agent's receipt of a certificate of the
Borrower evidencing that the Borrower has sufficient funds available to complete
the Project. Once reduced in accordance with this Section 2.5, the Commitment
Amount may not be reinstated. Any reduction of the Commitment Amount shall be
applied pro rata to each Lender's Commitment. All accrued and unpaid Commitment
Fees corresponding to the amount of the Commitment Amount reduced or terminated
to the effective date of any such reduction or termination shall be paid by the
Borrower on the effective date of such reduction or termination.

               SECTION 3. PAYMENT OF PRINCIPAL , INTEREST AND FEES

SECTION 3.1 REPAYMENT OF PRINCIPAL.

       The principal amount of each Loan shall be repaid by the Borrower in
eleven (11) consecutive equal semi-annual installments on the Principal
Repayment Dates, provided that the final installment shall be payable on the
Maturity Date.

                                      -23-
<PAGE>   25

SECTION 3.2 PREPAYMENTS.

       (a)    MANDATORY PREPAYMENTS.

       The Borrower shall prepay the principal amount of the Loans, in whole or
in part, together with interest accrued thereon to the date of prepayment (each
such prepayment, a "PREPAYMENT") upon the occurrence of any of the following
events, as follows:

              (1)    ILLEGALITY. The Borrower shall make Prepayments on the
dates and in the amounts specified in Section 5.3(b) if so required pursuant to
such Section.

              (2)    PREPAYMENT EVENTS. The Borrower shall make Prepayments upon
the receipt of Net Proceeds in respect of any Prepayment Event in an amount
equal to such Net Proceeds; provided, however, that in the case of a Prepayment
Event consisting of a casualty or other insured damage, the Borrower shall not
be subject to such prepayment obligation if within the period of thirty (30)
days following the receipt of such Net Proceeds the Borrower (i) notifies the
Administrative Agent that it intends to reinvest such Net Proceeds within the
six (6) months thereafter in the payment of the costs of repairing, restoring,
rebuilding or replacing the portion of the property that was the subject of such
casualty or damage; and (ii) certifies that such repair, restoration, rebuilding
or replacement will be completed within a period of six (6) months from the
occurrence of the relevant casualty event; and provided further, that if the Net
Proceeds from such a casualty event or damage exceed ten million Dollars
(US$10,000,000), the full amount thereof shall be paid to the Escrow Agent to be
held by the Escrow Agent in the Net Proceeds Account and shall be released by
the Escrow Agent to or at the direction of the Borrower as and when required for
payment of such costs of repair, restoration, rebuilding or replacement.

              (3)    PREPAYMENT UNDER IMPSAT INDENTURES. Concurrently with the
making of any voluntary or mandatory prepayment in respect of the securities
issued pursuant to the 2003 Indenture or the 2008 Indenture (not including any
voluntary or mandatory prepayment made in connection with the refinancing of the
aggregate principal and interest due under such securities), the Borrower shall
make a Prepayment in an amount which bears to the aggregate principal amount of
the Loans then outstanding the same ratio as the amount of the prepayment of the
relevant securities bears to the aggregate principal amount of such securities
then outstanding.

              (4)    EXCESS CASH FLOW OF THE BORROWER. Within fifteen (15)
Business Days after the Borrower shall have submitted to the Administrative
Agent its annual financial statements pursuant to Section 8.1(a) in respect of
any fiscal year of the Borrower ending after the Commitment Termination Date,
the Borrower shall make a Prepayment in an aggregate amount equal to fifty
percent (50%) of the Borrower's Excess Cash Flow, if any, for such fiscal year,
minus the aggregate principal amount of the Loans prepaid during such fiscal
year pursuant to Sections 3.2(a)(5), 3.2(a)(6) or 3.2(b).

              (5)    BORROWER CAPITAL MARKETS TRANSACTIONS. The Borrower shall
make a Prepayment upon its receipt of the Net Proceeds of any public offering or
private placement or other capital markets transaction by the Borrower of debt
securities in an amount equal to fifty

                                      -24-
<PAGE>   26

percent (50%) of (i) such Net Proceeds plus the Borrower's projected Excess Cash
Flow or (ii) such Net Proceeds minus the Borrower's projected Negative Cash
Flow, calculated, in each case, on a pro forma basis, for the four (4) fiscal
quarters following the fiscal quarter during which such Net Proceeds are
received; provided, however, that such percentage shall be twenty-five percent
(25%) until January 1, 2003. The Prepayment contemplated in this paragraph shall
not apply to an offering or placement of debt securities which are purchased and
held exclusively by IMPSAT, but shall apply to any secondary offering or
placement of such securities.

              (6)    IMPSAT CAPITAL MARKETS TRANSACTION. The Borrower shall make
a Prepayment upon IMPSAT's receipt of the Net Proceeds of any public offering or
private placement or other capital markets transaction by IMPSAT of debt
securities (i) in the amount of such Net Proceeds specified in Section 13.4 in
the case of the offering or placement of the Replacement Notes and (ii) in all
other cases, in an amount equal to fifty percent (50%) of (1) such Net Proceeds
plus IMPSAT's projected Excess Cash Flow or (2) such Net Proceeds minus IMPSAT's
projected Negative Cash Flow, calculated, in each case, on a pro forma basis,
for the four (4) fiscal quarters following the fiscal quarter during which such
Net Proceeds are received; provided, however, that such percentage shall be
twenty-five percent (25%) until January 1, 2003.

              (7)    IRUs. Except in respect of the Global Crossing IRU,
promptly after the Administrative Agent's approval of the creation of an IRU
pursuant to Section 8.2(j), the Borrower shall make a Prepayment upon its
receipt of the Net Proceeds of such IRU in an amount equal to the sum of (i) the
cost (including the cost of design, development, construction, improvement,
installation and integration) of the item of property or assets in respect of
which the IRU is granted plus (ii) an amount of up to fifty percent (50%) of
such cost, such amounts to be agreed by the Administrative Agent and the
Borrower as a condition to the Administrative Agent's approval.

       All amounts required to be prepaid under this Section 3.2(a) shall be
paid to the Administrative Agent promptly (but in any case within ten (10)
Business Days) after the Borrower's receipt of such amount.

       (b)    OPTIONAL PREPAYMENTS. Upon not less than seven (7) Business Days
prior written notice to the Administrative Agent, the Borrower may make a
Prepayment without premium or penalty, on any Interest Payment Date, subject to
the limitations imposed by Applicable Law, if any, provided that such Prepayment
shall only be allowed if the amount thereof is equal to one million Dollars
(US$1,000,000) or an integral multiple thereof, except that if the aggregate
principal amount of the Loans then outstanding is less than one million Dollars
(US$1,000,000), the Borrower may prepay such aggregate principal amount. Upon
receipt of such notice by the Administrative Agent, the Borrower's obligation to
make such Prepayment shall be irrevocable and binding.

       (c)    ORDER OF APPLICATION. All Prepayments under this Section 3.2 shall
be applied in inverse order of scheduled future installment repayments of the
Loans.

                                      -25-
<PAGE>   27

SECTION 3.3 INTEREST.

       (a)    INTEREST RATE. The Borrower shall pay to the Lenders interest on
the outstanding principal amount of each Loan on each Interest Payment Date, for
the period commencing on the Disbursement Date of such Loan until such Loan is
paid in full, at a rate per annum equal to LIBOR determined for each Interest
Period of such Loan, plus the number of basis points indicated below or, if such
Loan shall have been converted to a Prime Loan pursuant to Section 3.3(b), at a
rate per annum equal to the Prime Rate plus the number of basis points indicated
below.

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------
                INTEREST PERIOD                 LIBOR LOAN BASIS                   PRIME LOAN BASIS POINTS
                                                     POINTS
-------------------------------------------------------------------------------------------------------------------
<S>                                                       <C>                               <C>
First through sixth                                       525                               311
-------------------------------------------------------------------------------------------------------------------

Seventh and eighth                                        600                               386
-------------------------------------------------------------------------------------------------------------------

Ninth and tenth                                           625                               411
-------------------------------------------------------------------------------------------------------------------

Eleventh and thereafter                                   650                               436
-------------------------------------------------------------------------------------------------------------------
</TABLE>

       (b)    CONVERSION FROM LIBOR TO PRIME RATE. Notwithstanding, anything
herein to the contrary, if, on or prior to the determination of LIBOR for any
Interest Period, (1) the Administrative Agent reasonably determines (which
determination shall be conclusive absent manifest error) that by reason of any
event affecting the relevant market, quotations of interest rates for the
relevant deposits are not being provided for purposes of determining LIBOR for
such Interest Period; or (2) the Administrative Agent receives notice from the
Required Lenders that by reason of any event generally affecting the London
interbank market the LIBOR determined or to be determined for such Interest
Period does not adequately and fairly reflect the cost to such Lenders of making
or maintaining their affected Loans during such Interest Period (as conclusively
certified by such Required Lenders), then the Administrative Agent shall give
the Borrower and the Lenders prompt written notice thereof. If such notice is
given, any LIBOR Loans requested to be made on the first day of such Interest
Period shall be made as Prime Loans. The Administrative Agent shall use
reasonable efforts to determine whether the circumstances which have caused such
notice to be given continue to exist, and, if the Administrative Agent shall at
any time determine that such circumstances no longer exist, it shall, as soon as
practicable thereafter, notify the Borrower and the Lenders that the
Administrative Agent is withdrawing such notice whereupon any then outstanding
Prime Loan shall be converted to a LIBOR Loan.

       (c)    DEFAULT INTEREST. Notwithstanding the provisions of Section
3.3(a), the Borrower shall pay to the Lenders interest at the Default Interest
Rate on the unpaid principal amount, and

                                      -26-
<PAGE>   28

on any other amount payable by the Borrower hereunder or under the Notes, which
has not been paid in full when due (whether at stated maturity, by acceleration,
prepayment or otherwise), for the period from and including the due date thereof
to and including the date the same is paid in full (both before and after
judgment), whether or not any notice of default in the payment thereof has been
delivered. Interest payable under this Section 3.3(c) shall be compounded on any
overdue amount at three (3) month intervals commencing on the date on which the
default occurred.

       (d)    COMPUTATION. Interest on all LIBOR Loans shall be computed on the
basis of three hundred sixty (360) days and actual days elapsed (including the
first day but excluding the last) in the period for which payable. Interest on
all Prime Loans shall be computed on the basis of a year of three hundred
sixty-five/sixty-six (365/366) days and actual days elapsed (including the first
day but excluding the last).

SECTION 3.4 FEES.

       (a)    COMMITMENT FEE. The Borrower shall pay to the Administrative Agent
for the account of the Lenders a non-refundable per annum fee ("COMMITMENT FEE")
equal to three quarters of one percent (0.75%) of the daily average of the
undisbursed portion of the Commitment Amount during the Commitment Period,
computed on the basis of a year of three hundred sixty (360) days and actual
days elapsed (including the first day but excluding the last day other than the
Commitment Termination Date) and payable in arrears on the last Business Day of
each calendar quarter.

       (b)    FRONT-END FEE. The Borrower shall pay to the Administrative Agent
for the account of the Lenders on the Initial Disbursement Date a non-refundable
one-time fee in an amount equal to one and one half percent (1.50%) of the
Commitment Amount.

       (c)    MANAGEMENT FEES. The Borrower shall pay to (i) the Administrative
Agent an annual fee in an amount equal to sixty thousand Dollars (US$60,000),
(ii) the Collateral Agent an annual fee in an amount equal to thirty five
thousand Dollars (US$35,000), and (iii) the Escrow Agent an annual fee in an
amount equal to five thousand Dollars (US$5,000), all such fees payable in
advance to the respective parties.

SECTION 3.5 NATURE OF PAYMENTS.

       All payments under this Agreement and under the Notes shall be paid on
the dates when due without presentment, demand, protest, or notice of any kind,
all of which are hereby expressly waived. Such payments shall be made in Dollars
and in immediately available funds, without setoff, recoupment, counterclaim, or
any other deduction of any nature.

SECTION 3.6 PAYMENT PROCEDURES.

       (a)    DEPOSIT ACCOUNT. All payments hereunder and under the Notes shall
be made to the Administrative Agent for the ratable account of each Lender
entitled thereto, in Dollars by

                                      -27-
<PAGE>   29

wire transfer of immediately available funds to the Administrative Agent's
account indicated below, or such other account as the Administrative Agent may
designate to the Borrower in writing (the "DEPOSIT ACCOUNT"), not later than
1:00 P.M. New York time on the date when due.

                        Administrative Agent's Deposit Account:
                        Citibank N.A. New York
                        Swift Number CITIUS33
                        ABA # 021000089
                        For Credit to the account of Nortel Networks Corporation
                        Account #38545364

       Any payments under this Agreement that are made later than 1:00 p.m. (New
York time) shall be deemed to have been made on the next succeeding Business
Day.

       (b)    BUSINESS DAYS. Whenever any payment to be made hereunder or under
any Note shall be due on a day which is not a Business Day, the due date thereof
shall be extended to the next succeeding Business Day, provided, that should
such next succeeding Business Day fall in the next calendar month, such due date
shall be the immediately preceding Business Day.

SECTION 3.7 ADMINISTRATIVE AGENT'S DETERMINATION.

       Any determination made by the Administrative Agent as to the interest
rate, the Default Interest Rate, and the amounts of interest, principal and
other amounts due hereunder shall be conclusive in the absence of manifest
error.

SECTION 3.8 PAYMENTS PRO RATA.

       (a)    PRO RATA. The Administrative Agent agrees that promptly after its
receipt of each payment from or on behalf of the Borrower in respect of any
amount due and payable by the Borrower hereunder, except as otherwise expressly
provided herein, it shall distribute such payment to the Lenders pro rata based
upon their respective shares, if any, of the Obligations with respect to which
such payment was received.

       (b)    EXCESS PAYMENTS. Each of the Lenders agrees that, if it should
receive any payment hereunder (either by voluntary payment, by realization upon
security, by the exercise of the right of setoff or banker's lien, by
counterclaim or cross action, or otherwise), which is applicable to the payment
of the principal of or interest on the Loans or the fees, with the result that
such Lender receives a greater proportion of the amount then due to it hereunder
than any other Lender receives in respect of the amount due to such other Lender
hereunder, then such Lender receiving such excess payment shall purchase for
cash without recourse or warranty from the other Lenders an interest in the
Obligations of the Borrower to such other Lenders in such amount as shall result
in a proportional participation by all the Lenders in such payment; provided,
however, that if all or any portion of such excess amount is thereafter
recovered from such Lender, such purchase shall be rescinded and the purchase
price restored to the extent of such recovery, without interest.

                                      -28-
<PAGE>   30

             SECTION 4. PAYMENT IN DOLLARS; EVENT OF SOVEREIGN RISK

SECTION 4.1 OBLIGATION TO PAY IN DOLLARS; JUDGMENT CURRENCY.

       This is an international transaction in which the specification of
Dollars and payment in the place specified pursuant to this Agreement (the
"SPECIFIED PLACE OF PAYMENT"), is of the essence, and Dollars shall be the
currency of account in all events. The Obligations of the Borrower shall not be
discharged by an amount paid in another currency or in another place, whether
pursuant to a judgment or otherwise, to the extent that the amount so paid on
conversion to Dollars and transferred to the Specified Place of Payment under
normal banking procedures does not yield the amount of Dollars in the Specified
Place of Payment due hereunder. If for the purpose of obtaining judgment in any
court it is necessary to convert a sum due hereunder in Dollars into another
currency (the "SECOND CURRENCY"), the rate of exchange which shall be applied
shall be that at which in accordance with normal banking procedures the Lenders
could purchase Dollars with the Second Currency on the Business Day next
preceding that on which judgment is rendered. The obligation of the Borrower in
respect of any such sum due to the Lenders hereunder or under the Notes shall,
notwithstanding the rate of exchange actually applied in rendering such
judgment, be discharged only to the extent that on the Business Day following
receipt by the Lenders of any sum adjudged to be due hereunder or under the
Notes in the Second Currency, the Lenders may in accordance with normal banking
procedures purchase and transfer to the Specified Place of Payment Dollars with
the amount of the Second Currency so adjudged to be due; and the Borrower
hereby, as a separate obligation and notwithstanding any such judgment, agrees
to indemnify the Lenders against, and to pay the Lenders on demand in Dollars,
any difference between the sum originally due to the Lenders in Dollars and the
amount of Dollars so purchased and transferred.

SECTION 4.2 EVENT OF SOVEREIGN RISK.

       Without prejudice to Section 4.1, in the event that not less than three
(3) Business Days before any payment is due hereunder any Lender notifies the
Administrative Agent that an Event of Sovereign Risk has occurred and is
continuing, the Administrative Agent shall notify the Borrower and each Lender
of the occurrence of such event and the Borrower shall at its own expense and at
each Lender's sole option (which option shall be deemed to be that set forth in
Section 4.2(b) below unless notice shall have been received from such Lender as
described in Section 4.2(b) or (c) below):

       (a)    DOLLARS. Obtain the required amount of Dollars through (1) the
sale of Bonos Externos de la Republica Argentina, Series 1989 ("BONEX") or of
any other public or private bond or tradable security, (2) the purchase of
Dollars in New York, with whatever legal tender, or (3) failing both (1) and
(2), any other legal mechanism for the acquisition of Dollars in any exchange
market; or

       (b)    BEST FIRM BID PRICE. If a Lender shall have notified the
Administrative Agent and the Borrower prior to a date of payment that its option
shall be that set forth in this Section

                                      -29-
<PAGE>   31

4.2(b), make the required payment in the city of Buenos Aires, Argentina, by the
delivery of, at such Lender's sole option, (1) Bonex, (2) Argentine Floating
Rate Bonds ("FRBs"), (3) Argentine Par Bonds ("PAR BONDS") or (4) any other
securities exchangeable for Bonex, FRBs or Par Bonds in accordance with
Argentine regulations, which, in any of cases (1) through (4) if sold at the
best firm bid price quoted, for the relevant amount, on the date of payment in
New York by the Reference Dealers would cause such Lender to receive, after
taxes, fees, commissions and any other costs, an amount of Dollars equal to the
amount required to be paid by the Borrower for the account of such Lender on
such payment date (for purposes of this Section 4.2(b), the "best firm bid
price" shall be determined on the basis of quotes obtained from the Reference
Dealers and, if only one quote is obtained, on the basis of such quote; and
"REFERENCE DEALERS" shall mean The Chase Manhattan Bank, Banque Nationale de
Paris, JP Morgan and Merrill Lynch & Co. or, if none of the foregoing is quoting
a firm bid price for such payment date, then the "Reference Dealers" shall be
those dealers (which may be as few as one dealer) selected by such Lender to be
Reference Dealers for the purposes of this Section 4.2(b)); or

       (c)    DEFERRAL. If a Lender shall have notified the Administrative Agent
and the Borrower prior to a date of payment that its option shall be that set
forth in this Section 4.2(c), defer payment of the amount due as specified in
such notice until the earlier of (1) the date which is one Business Day
following the date on which such Lender shall, in its sole discretion, notify
the Administrative Agent and the Borrower that such Event of Sovereign Risk is
no longer in effect, or (2) the date (which date shall be not more than ninety
(90) calendar days following the date on which the payment was originally due)
on which such Lender shall notify the Administrative Agent and the Borrower that
payment is to be made in accordance with the procedure outlined in either
Section 4.2(a) or (b) above, as such Lender shall elect. If a payment obligation
of the Borrower is so deferred pursuant to this Section 4.2(c), then the period
between the original payment date and the deferred date for payment determined
in accordance with the first sentence of this Section 4.2(c) (the "DEFERRED
PAYMENT DATE") shall be the "SOVEREIGN EVENT DEFERRAL PERIOD", which shall also
constitute an "Interest Period" for purposes of such Lender's Loan(s) and
Note(s). If such Lender shall subsequently provide notice that the Borrower is
to make payment as specified in (x) Section 4.2(c)(1) above or (y) Section
4.2(c)(2) above pursuant to an election to apply the mechanism set forth in
Section 4.2(a) above (which subsequent notice shall specify the Dollar amount
due on the Deferred Payment Date concerned), then the Borrower shall make
payment in Dollars of all outstanding amounts due hereunder (including, without
limitation, interest accrued during the Sovereign Event Deferral Period) on such
Deferred Payment Date in accordance with the terms of this Agreement.
Alternatively, if such Lender shall subsequently provide notice that the
Borrower is to make payments pursuant to the mechanism set forth in Section
4.2(b) above (which subsequent notice shall specify the Dollar amount due on the
Deferred Payment Date concerned, as well as the securities to be used for
payment and the account in Argentina to which such securities are to be
delivered), then the Borrower shall make payment of all outstanding amounts due
hereunder (including, without limitation, interest accrued during the Sovereign
Event Deferral Period) on such Deferred Payment Date in accordance with such
Lender's notice.

                                      -30-
<PAGE>   32

       (d)    ACCRUAL OF INTEREST UNAFFECTED. Payments made in accordance with
this Section 4.2 shall include any amounts required to be paid under Section
5.2. Any undertaking of operations to obtain Dollars according to this Section
4.2 shall not affect the accrual of interest (including default interest) in
accordance herewith. Nothing in this Section 4.2 shall impair any of the rights
of the Agents or the Lenders under this Agreement or be construed to entitle the
Borrower to refuse to make payments hereunder in Dollars for any reason
whatsoever, including, without limitation, any of the following:

                     (1)    the purchase of Dollars in Argentina by any means
becomes more onerous or burdensome for the Borrower than as of the date hereof;
and

                     (2)    the exchange rate in force in Argentina for the
conversion of Pesos to Dollars changes significantly from that in effect as of
the date hereof.

                     SECTION 5. FUNDING AND YIELD PROTECTION

SECTION 5.1 TAXES.

       (a)    PAYMENT NET OF TAXES. Any and all payments by the Borrower in
respect of amounts due under this Agreement, the Notes and any other Financing
Document shall be made free and clear of, and without withholding or deduction
for or on account of, any present or future taxes (including, without
limitation, income taxes, value added taxes, sales taxes, use taxes, stamp or
documenting taxes, excise taxes, property taxes and asset taxes), duties,
levies, fees, imposts, deductions, charges or withholdings, and all liabilities
with respect thereto, of whatever nature now or hereafter imposed, assessed or
levied by any Argentine Governmental Authority or by any other Governmental
Authority from or through which any payment is made hereunder or under the other
Financing Documents ("TAXES"), except income or franchise taxes imposed on any
Lender by the laws of the jurisdiction, whether federal, state or local, in
which it is resident or organized ("EXCLUDED TAXES"). If any Taxes, other than
any Excluded Taxes, are required by Applicable Law to be withheld or deducted
from or in respect of any sum payable under this Agreement, the Notes or any
other Financing Document:

              (1)    the Borrower shall pay such additional amount as may be
necessary to ensure that after reduction for all required withholdings or
deductions for Taxes, other than Excluded Taxes (including withholdings or
deductions applicable to additional sums payable under this Section 5.1), the
net amount actually received by the Lenders free and clear of such withholding
or deduction is equal to the amount the Lenders would have received had no such
withholdings or deductions been made;

              (2)    the Borrower shall make such withholdings or deductions;
and

              (3)    the Borrower shall pay the full amount withheld or deducted
to the relevant Governmental Authorities in accordance with the Applicable Laws
and prior to the date on which penalties attach thereto.

                                      -31-
<PAGE>   33

       (b)    INDEMNITY. The Borrower shall indemnify and hold the Agents and
the Lenders harmless from and against, and shall reimburse the Lenders on demand
for, the full amount of Taxes (including, without limitation, any Taxes imposed
on amounts payable under this Section 5.1) paid by the Lenders other than
Excluded Taxes, and for any loss, liability, claim or expense (including
penalties, interest, and legal fees) arising therefrom or with respect thereto,
whether or not such Taxes were correctly or legally asserted, and which the
Agents or the Lenders may incur at any time arising out of, or in connection
with, any failure of the Borrower to make any payment of such Taxes when due.

       (c)    OTHER TAXES. The Borrower shall pay all Taxes (including notary
public and filing fees), other than Excluded Taxes, associated with the
execution, delivery, filing, recording, or registration of, or foreclosure with
respect to, this Agreement, the Notes and the other Financing Documents, and
shall indemnify and hold the Agents and the Lenders harmless from and against
any and all liabilities with respect to, or resulting from, any failure or delay
in paying such Taxes.

       (d)    SURVIVAL. Without prejudice to the survival of any other agreement
of the Borrower hereunder, the Obligations of the Borrower under this Section
5.1 shall survive the payment in full of all principal and interest hereunder
and under the Notes.

       (e)    TAX RECEIPTS. Within thirty (30) days after the date of any
payment of Taxes required to be made under this Section 5.1, the Borrower shall
furnish to the Administrative Agent a copy of any official tax receipts
evidencing such payment.

SECTION 5.2 FUNDING BREAKAGE COSTS.

       If the Lenders incur any costs, expenses or losses as a result of (a) any
failure by the Borrower to borrow after giving the Administrative Agent a
Disbursement Request; (b) any payment, including any payment due on
acceleration, by the Borrower on a date other than an Interest Payment Date; or
(c) any failure by the Borrower to make any Prepayment after the Borrower has
given the notice required hereunder regarding such Prepayment, then, in any such
event, the Borrower shall pay or cause to be paid, in Dollars, to the
Administrative Agent for the account of the Lenders the amount which the
Administrative Agent shall notify the Borrower as being the aggregate of such
costs, expenses and losses (collectively, the "FUNDING BREAKAGE COSTS"). The
certificate of the Administrative Agent setting forth in reasonable detail the
amount of Funding Breakage Costs for which demand is made shall, in the absence
of manifest error, be conclusive and binding as to the amount of such Funding
Breakage Costs for all purposes.

SECTION 5.3 ILLEGALITY.

       (a)    NOTICE AND SUSPENSION. If the introduction of any Applicable Law,
or any change in any Applicable Law, or any change in the interpretation or
administration of any Applicable Law, makes or has made it unlawful for a Lender
or its applicable Lending Office to make or fund its Loans, then the Lender
shall give notice thereof to the Borrower through the Administrative Agent, and
the obligation of that Lender to make or fund its Loans shall be

                                      -32-
<PAGE>   34

suspended until such Lender shall notify the Administrative Agent and the
Borrower that the circumstances giving rise to such determination no longer
exists.

       (b)    PREPAYMENT. If, as a result of any circumstances set forth in
Section 5.3(a) it is unlawful for a Lender to maintain any Loan, the Borrower
shall, upon receipt of notice of such determination and demand from such Lender
(with a copy to the Administrative Agent), prepay in full the Loan of such
Lender then outstanding, together with any accrued and unpaid interest thereon
and any fees required to be paid under Section 3.4, on the next Interest Payment
Date for such Loan following the date the notice is given; provided, however,
that if such Lender notifies the Borrower that earlier Prepayment is necessary
in order to enable such Lender to comply with such Applicable Law or change and
specifies an earlier date for the Prepayment, the Borrower shall make the
Prepayment on the date so specified together with any amounts required to be
paid under Section 5.2.

       (c)    LENDER'S DUTY TO MITIGATE. Before giving notice to the
Administrative Agent under this Section 5.3, the affected Lender shall endeavor
to designate a different Lending Office with respect to its Loan or endeavor in
good faith to provide another structure for its Loan if such designation or
alternative structure will avoid the need for giving such notice or making such
demand and will not, in the Lender's sole determination, be illegal or cause
such Lender to suffer any economic, legal, regulatory or other disadvantage.

SECTION 5.4 INCREASED COSTS AND YIELD PROTECTION.

       (a)    NOTICE; ADDITIONAL PAYMENTS. If due to either (1) the introduction
of, any change in, or any change in the interpretation or administration by any
competent authority of, any Applicable Law, or (2) the compliance by a Lender
with any guideline or request from any central bank or any other Governmental
Authority (whether or not having the force of law), in each case, made
subsequent to the date of this Agreement, there shall be any increase in the
cost to such Lender of agreeing to make or making, funding or maintaining its
Loan, then such Lender shall notify the Administrative Agent and the Borrower
accordingly, and the Borrower shall pay to the Administrative Agent for the
account of such Lender, such additional amounts as are sufficient to compensate
such Lender for such increased costs; provided, that any such additional amounts
shall not duplicate any amounts payable by the Borrower under Section 5.3.

       (b)    CAPITAL ADEQUACY REGULATIONS. If (1) the effectiveness of any
Capital Adequacy Regulation, (2) any change in any Capital Adequacy Regulation,
(3) any change in the interpretation or administration of any Capital Adequacy
Regulation by any competent authority, including with respect to compliance by a
Lender (or its Lending Office) or any corporation controlling the Lender with
any Capital Adequacy Regulation, in each case, made subsequent to the date of
this Agreement, affects the amount of capital required or expected to be
maintained by such Lender (or its Lending Office) or any corporation controlling
such Lender and, after taking into consideration such Lender's or such
corporation's policies with respect to capital adequacy and otherwise
anticipated return on capital, such Lender determines that the amount of such
capital is increased as a consequence of its Commitment, Loans and other
obligations under this Agreement, then the Borrower, upon receipt from such
Lender (through the Administrative

                                      -33-
<PAGE>   35

Agent) of a demand for payment of additional amounts, shall pay to such Lender
additional amounts sufficient to compensate such Lender, the Lending Office or
the corporation for the increased cost to such Lender, Lending Office or other
corporation or the reduction in the rate of return to such Lender, Lending
Office or other corporation on its capital caused by its compliance with such
Capital Adequacy Regulation, provided, however, that any such additional amounts
shall not duplicate any amounts payable by the Borrower under Section 5.4(a).

       (c)    LENDER'S DUTY TO MITIGATE. Before giving notice to the
Administrative Agent under this Section 5.4, the affected Lender shall endeavor
to designate a different Lending Office with respect to its Loan if such
designation will avoid the need for giving such notice or making such demand and
will not, in the Lender's sole determination, be illegal or cause such Lender to
suffer any economic, legal, regulatory or other disadvantage.

                   SECTION 6. DELIVERIES; CONDITIONS PRECEDENT

SECTION 6.1 CONCURRENT DELIVERIES.

       Concurrently with the execution of this Agreement, the Borrower has
delivered, or caused to be delivered to the Administrative Agent an original or
certified copy of each of (a) the executed Turnkey Contract, (b) the Business
Plans, (c) the executed Brazil Financing Agreement and (d) the executed Brazil
Turnkey Contract.

SECTION 6.2 CONDITIONS PRECEDENT TO INITIAL DISBURSEMENT; CLOSING.

       The obligations of the Lenders to make the initial Disbursement is
subject to (i) the conditions precedent contained in Section 6.3 and (ii) the
delivery to the Administrative Agent on the Closing Date of the following
documents, each in form and substance satisfactory to the Administrative Agent:

       (a)    PROJECT DOCUMENTS. An original executed counterpart of each of (1)
the IMPSAT Guarantee, (2) the Escrow Account Agreement, (3) the Intercreditor
Agreement and (4) the Supply Agreement.

       (b)    BRAZIL FINANCING DOCUMENTS. An original or certified copy of each
of (1) the executed Brazil Guarantee and (2) the executed Brazil Escrow Account
Agreement.

       (c)    OFFICER'S CERTIFICATES. Certificates, dated the Closing Date,
signed by an Authorized Officer of IMPSAT and the Borrower, respectively, and
certifying the authenticity of IMPSAT's and the Borrower's respective Charter
Documents and corporate resolutions attached thereto and indicating IMPSAT's and
the Borrower's current officers, their respective signatures and their corporate
authority.

       (d)    CAPITALIZATION. A certificate dated the Closing Date signed by an
Authorized Officer of the Borrower certifying that, as of the Closing Date, the
Borrower's Paid in Capital is

                                      -34-
<PAGE>   36

equal to or greater than the equivalent in Pesos of twenty six million four
hundred forty five thousand Dollars (US$26,445,000) (determined according to
U.S. GAAP), such certificate to be accompanied by original or certified copies
of the following documents: (i) evidence of the Borrrower's receipt of an
irrevocable contribution on account of a future capital increase made by IMPSAT
in the amount of US$50,000,000 (fifty million Dollars) (the "IMPSAT CAPITAL
CONTRIBUTION"); (ii) the minutes of the Borrower's Board of Directors accepting
the IMPSAT Capital Contribution and calling for a shareholders meeting to
consider the Borrower's capital increase in the amount of the IMPSAT Capital
Contribution (the "BORROWER CAPITAL INCREASE") and (iii) the written undertaking
of IMPSAT containing its irrevocable commitment not to withdraw, in whole or in
part, or transfer or encumber any rights in respect of the IMPSAT Capital
Contribution prior to the effective date of the Borrower Capital Increase.

       (e)    IMPSAT BRAZIL CAPITALIZATION. The certificate of an Authorized
Officer of IMPSAT Brazil required by Section 6.2(e) of the Brazil Financing
Agreement.

       (f)    LICENSES. Documents which evidence, to the satisfaction of the
Administrative Agent, the Borrower's ownership of the Licenses and that the
Licenses are in full force and effect.

       (g)    OPINIONS OF COUNSEL. An opinion addressed to the Administrative
Agent, the Collateral Agent and each of the Lenders and dated the Closing Date
from each of:

              (1)    Arnold & Porter, special U.S. Counsel to the Borrower, and

              (2)    Nicholson & Cano, Argentine Counsel to the Borrower.

Such opinions to be in form and substance satisfactory to the Lenders and to
address the matters identified in Exhibit J and Exhibit K, respectively.

       (h)    PAYMENT OF FEES. A letter of instruction dated the Closing Date
addressed to the Administrative Agent and signed by an Authorized Officer of the
Borrower (1) setting forth a statement of all costs, fees, out-of-pocket
expenses and other compensations and payments (including under any fee letters)
due by the Borrower to Nortel or any other Lender on or before the initial
Disbursement Date under or with respect to the Financing Documents and the
Collateral, including all reasonable legal fees and expenses incurred by Nortel
or its Affiliates under Section 11.1 (2) acknowledging and consenting to the
payment of all such amounts, and (3) directing the payment of all such amounts
by the Administrative Agent from the proceeds of the first Disbursement.

       (i)    GOVERNMENTAL APPROVALS. Evidence that the following Governmental
Approvals have been obtained and are in full force and effect, and all
registrations, applications, tariffs, reports and other documents in connection
therewith required to be filed and/or registered with any Person have been filed
and registered:

              (1)    All Governmental Approvals, if any, then necessary in
connection with the execution, delivery or performance by the Borrower of this
Agreement and any other Financing Documents to which the Borrower is a party;

                                      -35-
<PAGE>   37

              (2)    All Governmental Approvals, if any, then necessary in
connection with the exercise by the Administrative Agent, the Collateral Agent
or any Lender of its rights or remedies under this Agreement or any other
Financing Documents; and

              (3)    All material Governmental Approvals (other than the
Applicable Permits), if any, then necessary in connection with the continuing
operation of the Telecommunications Business by the Borrower and its
Subsidiaries and the implementation of the Project.

       (j)    PROCESS AGENT. A letter from CT Corporation System, currently
located at 111 Eighth Avenue, New York, New York 10011, in a form satisfactory
to the Administrative Agent in its sole discretion, indicating its consent to
its appointment as agent for service of process by the Borrower; and evidence
that the fees of such agent have been paid in full for the period commencing on
the date hereof until six (6) months after the Maturity Date.

       (k)    INSURANCE. Certificates of all insurance required by Section
8.1(d), which certificates (1) state the names of the insurance companies, the
amounts of the insurance, the dates of the expiration thereof and the properties
and risks covered thereby, (2) have been executed by an Authorized Officer of
the respective insurer, and (3) certify that all premiums and other payments
have been timely paid and that such insurance is otherwise not subject to
cancellation by the insurer during its term, except for nonpayment of premiums,
in which case at least fifteen (15) days prior written notice of termination
must be given to the Administrative Agent.

       (l)    BUSINESS PLANS. Copies of the Business Plans as revised through
the Closing Date to reflect the debt and capital structure contemplated by this
Agreement, but not otherwise materially revised.

SECTION 6.3 CONDITIONS PRECEDENT TO ALL DISBURSEMENTS.

       The obligation of the Lenders to make any and all Disbursements
(including the initial Disbursement) is subject to the satisfaction of the
following conditions precedent on the relevant Disbursement Date to the
satisfaction of the Administrative Agent:

       (a)    DISBURSEMENT REQUEST. The Borrower shall have delivered to the
Administrative Agent a duly completed and executed Disbursement Request.

       (b)    NOTES. The Borrower shall have duly completed, executed, and
delivered to the Administrative Agent a Note or Notes dated the applicable
Disbursement Date and payable to the order of each Lender participating in such
Disbursement, in the principal amount of the Loan to be made by such Lender on
such date.

       (c)    SECURITY DOCUMENTS. All Security Documents theretofore executed
and delivered shall be in full force and effect and the Borrower shall have
executed and delivered one or more Equipment Pledge Agreements and Mortgage
Deeds over the Equipment and real property, if any, that has been acquired by
the Borrower since the last Disbursement Date and is required to become part of
the Collateral in accordance with this Agreement and all of such

                                      -36-
<PAGE>   38

agreements and deeds which require registration with a Governmental Authority in
order to perfect the Liens provided therein shall have been duly registered or
filed for registration and a certified copy of the registered agreement or deed
or of the official receipt or other document evidencing such filing, as the case
may be, shall have been delivered to the Administrative Agent.

       (d)    REPRESENTATIONS AND WARRANTIES. All representations and warranties
made by the Borrower, any Subsidiary thereof or IMPSAT in the Financing
Documents shall be true and correct in all material respects on and as of such
Disbursement Date with the same force and effect as if made on and as of such
Disbursement Date (except to the extent that such representations and warranties
expressly refer to an earlier date, in which case they shall have been true and
correct as of such earlier date).

       (e)    COVENANTS. The Borrower shall be in compliance with all covenants
contained in Section 8 as of such Disbursement Date.

       (f)    LITIGATION. No litigation, investigation or proceeding of or
before any arbitrator or Governmental Authority shall be pending, or to the
knowledge of the Borrower, threatened by or against the Borrower or any of its
Subsidiaries or against any of its or their respective properties or revenues
which challenges the validity or legality of this Agreement or any other Project
Agreement or any of the transactions contemplated hereby or thereby.

       (g)    NO DEFAULTS. No Default or Event of Default shall exist hereunder
and no default or event of default shall exist under any of the Brazil
Agreements (regardless of whether or not there has been a notice of default or
acceleration thereunder) on or as of such Disbursement Date.

       (h)    MATERIAL ADVERSE CHANGE. Since the last Disbursement Date (or, in
the case of the initial Disbursement, since the date hereof), no Material
Adverse Change shall have occurred and be continuing.

       (i)    INSURANCE. All insurance required to be maintained by the Borrower
or its Subsidiaries pursuant to Section 8.1(d) shall be in full force and effect
and all premiums due and payable as of such Disbursement Date shall have been
paid in full.

       (j)    LICENSES AND GOVERNMENTAL APPROVALS. All Licenses and all
Governmental Approvals referred to in Section 6.2(i) shall be in full force and
effect as of such Disbursement Date.

       (k)    OTHER DOCUMENTS; OPINIONS. The Administrative Agent shall have
received: (1) such other documents and evidence as the Administrative Agent may
reasonably request in connection with the transactions contemplated hereby; and
(2) if requested by the Required Lenders, a legal opinion or opinions, in form
and substance satisfactory to the Administrative Agent, of counsel acceptable to
the Administrative Agent, with respect to any matters incident to such
Disbursement, including without limitation as to the due registration of the
Security Documents then in effect.

                                      -37-
<PAGE>   39

SECTION 6.4 ENGLISH TRANSLATIONS.

       All Charter Documents and other documents and resolutions required to be
delivered pursuant to this Agreement, the other Project Agreements, and the
Licenses shall, if not in English, and if the Administrative Agent so requests,
be accompanied by an English translation (which, if the Administrative Agent so
requests, shall be a certified translation prepared by an Argentine certified
translator) which the Administrative Agent shall have the right to rely upon for
all purposes hereof and the other Project Agreements. All costs of translation
shall be payable by the Borrower.

SECTION 6.5 TERMINATION BY THE LENDERS.

       In the event the conditions precedent to the initial Disbursement shall
not have occurred on or before November 6, 1999, the Required Lenders shall have
the right, by notice to the Borrower through the Administrative Agent, to
terminate this Agreement, without prejudice to the rights of the Lenders under
Section 11 hereof. Any fees and expenses payable hereunder by the Borrower to
the Lenders shall thereupon become immediately due and payable.

                   SECTION 7. REPRESENTATIONS AND WARRANTIES.

       The Borrower hereby represents and warrants to each Agent and each Lender
that the statements contained in this Section 7 are true, correct and complete
as of the date hereof and shall be true, correct and complete as of each
Disbursement Date.

SECTION 7.1 CORPORATE STATUS.

       Each of the Borrower and its Subsidiaries and IMPSAT (a) is a sociedad
anonima or corporation, as the case may be, duly organized, validly existing and
in good standing under the laws of the jurisdiction of its incorporation, and
(b) has the power and authority to own its property and assets, to carry on its
business in each jurisdiction in which it operates, and to incur Indebtedness
and to create or suffer to exist Liens on its properties created under the
Security Documents. IMPSAT is the holder, directly or indirectly, of at least
ninety-five (95%) of the Capital Stock of the Borrower. Set forth on Schedule
7.1 hereto is a complete list of the Subsidiaries of IMPSAT and the Borrower,
the jurisdiction of organization of each such Subsidiary and the amount and
percentage of Capital Stock of each such Subsidiary owned by IMPSAT and the
Borrower.

SECTION 7.2 CORPORATE POWER.

       (a)    AUTHORITY. Each of the Borrower and IMPSAT and their respective
Subsidiaries has full power and authority to enter into the Project Agreements
to which it is a party or, when executed and delivered, it will become a party,
all of which have been duly authorized by all proper and necessary corporate
action, and has duly executed and delivered each such Project

                                      -38-
<PAGE>   40

Agreement which has been entered into as of the date hereof or the applicable
Disbursement Date, as the case may be.

       (b)    VALIDITY AND ENFORCEABILITY. Assuming due execution and delivery
thereof by the other parties thereto, each such Project Agreement constitutes,
or when executed and delivered will constitute, a legal, valid and binding
obligation of the Borrower, IMPSAT and their respective Subsidiaries, as the
case may be, enforceable against them in accordance with its terms, except, in
each case, to the extent such enforceability may be restricted by bankruptcy,
insolvency or similar Applicable Laws affecting the enforcement of creditors'
rights generally or by general principles of equity.

SECTION 7.3 GOVERNMENTAL APPROVALS.

              (a)    FINANCING DOCUMENTS. All Governmental Approvals that are
required by the Borrower or any other party in connection with the execution,
delivery or performance by, or enforcement against, the Borrower and any other
party of this Agreement and all other Financing Documents to which the Borrower
or such other party is a party have been obtained, are in full force and effect,
and the Borrower and each such party is in compliance in all material respects
with such Governmental Approvals.

              (b)    OPERATIONS. All Governmental Approvals (other than the
Applicable Permits) that are required by the Borrower or any other party to the
Financing Documents in connection with the business, operations and activities
of the Borrower and its Subsidiaries as now conducted or as contemplated by the
Borrower Business Plan have been obtained.

              (c)    NO PROCEEDINGS. There is no proceeding pending or, to the
knowledge of the Borrower or any of its Subsidiaries, threatened against the
Borrower or any other party to the Financing Documents that seeks to rescind,
terminate, suspend, modify or otherwise affect any Governmental Approvals, in
each case that would have a Material Adverse Effect.

SECTION 7.4 NO VIOLATION.

       Neither the execution, delivery or performance by the Borrower, IMPSAT or
any of their respective Subsidiaries of any Project Agreement to which it is a
party, nor the use by the Borrower of the proceeds of the Loans as contemplated
by this Agreement:

              (a)    will violate or conflict with any term or condition of any
License;

              (b)    will contravene any material provision of any Applicable
Law binding on the Borrower, IMPSAT or any of their respective Subsidiaries or
any of their assets;

              (c)    will conflict with, or be inconsistent with, or result in
any breach of, or constitute a default under, or result in the creation or
imposition of (or the obligation to create or impose) any Lien (other than
Permitted Liens) upon any of the properties or assets of the Borrower, IMPSAT or
any of their respective Subsidiaries pursuant to the terms of any indenture,
mortgage, credit agreement, loan agreement or any other agreement, contract or

                                      -39-
<PAGE>   41

instrument to which the Borrower, IMPSAT or any such Subsidiary is a party or by
which each such Person or any of its respective properties or assets are bound
or to which they may be subject; or

              (d)    will violate any provision of the Charter Documents of the
Borrower, IMPSAT or any of their respective Subsidiaries;

except to the extent that any of the violations contained in clauses (c) and (d)
above could not reasonably be expected to have a Material Adverse Effect.

SECTION 7.5 PROCEEDINGS.

       (a)    NO PROCEEDINGS. Except as disclosed in Schedule 7.5, there is no
litigation, investigation or proceeding pending or, to the knowledge of the
Borrower or IMPSAT after reasonable inquiry, threatened before any arbitrator or
Governmental Authority, nor, to the knowledge of the Borrower after reasonable
inquiry, any circumstances or conditions that might give rise to any such
proceedings, which could reasonably be expected to have a Material Adverse
Effect.

       (b)    NO ORDERS. No injunction, writ, temporary restraining order or any
order of any nature has been issued by any court or Governmental Authority (1)
purporting to enjoin or restrain the execution, delivery or performance of this
Agreement or any other Financing Documents, or (2) which could reasonably be
expected to have a Material Adverse Effect.

SECTION 7.6 TAXES.

       The Borrower, IMPSAT and their respective Subsidiaries have timely filed
all required returns and have paid all applicable taxes shown thereon to be due
and payable except for such taxes, if any, as are being contested in good faith
by appropriate proceedings and as to which (a) adequate reserves have been
established in accordance with U.S. or Argentine GAAP, as applicable, on the
books of the Borrower, IMPSAT and such Subsidiaries, as the case may be, or (b)
the aggregate amount of such unpaid taxes, assessments and charges is less than
five hundred thousand Dollars (US$500,000).

SECTION 7.7 FINANCIAL STATEMENTS.

       (a)    BALANCE SHEETS, ETC. Except as indicated in Schedule 7.16, the
consolidated balance sheet of the Borrower and its Subsidiaries and the
consolidated balance sheet of IMPSAT and its Subsidiaries as of December 31,
1998 and June 30, 1999 and the related consolidated statements of income or
operations, retained earnings and changes in financial position (or of cash
flow, as the case may be) of each of the Borrower and IMPSAT for the fiscal year
or period then ended, with the opinion thereon of the Independent Auditor (in
the case of the balance sheets for December 31, 1998) are correct and fairly
present the financial condition of the Borrower or IMPSAT and their respective
Subsidiaries, as the case may be; and results of operations for the period
covered thereby. The financial statements to be delivered pursuant to

                                      -40-
<PAGE>   42

Section 8.1 hereof shall be correct and shall fairly present in all such cases
the financial condition of the Borrower or IMPSAT, as the case may be, as of the
dates thereof and the results of its operations for the periods ended on said
dates, and all are or shall be prepared in accordance with U.S. GAAP.

       (b)    NO LIABILITIES. Neither the Borrower nor IMPSAT had or will have
on the dates of the financial statements referred to in Section 7.7(a) any
material contingent liabilities, liabilities for taxes, or material losses from
any commitments, except as specifically referred to, or reflected, or provided
for, in said financial statements as at said dates.

SECTION 7.8 THE PROJECT.

       (a)    BUSINESS PLANS. The Business Plans accurately state in all
material respects all costs and expenses incurred and to be incurred in order to
construct and finance the construction of the Network and the carrying out of
the Project in the manner contemplated by the Project Agreements. All
projections and budgets furnished or to be furnished to the Lenders by or on
behalf of the Borrower and IMPSAT and the summaries of significant assumptions
related thereto, including (without limitation) all information in the Business
Plans: (1) have been and will be prepared with due care; (2) fairly present, and
will fairly present, in all material respects, the expectations of the Borrower
and IMPSAT as to the matters covered thereby, (3) are based on, and will be
based on, reasonable assumptions as to all factual and legal matters relative to
the estimates therein; and (4) are and will be in all material respects
consistent with the provisions of the Project Agreements and the Business Plans.

       (b)    MATERIAL INFORMATION. There are no statements or conclusions in
any of the projections or budgets which are based upon or include information
known to the Borrower or IMPSAT to be misleading or which fail to take into
account material information regarding the matters reported therein. Attached to
this Agreement as Exhibit H is a true and complete list of the Project
Agreements executed on or before the date hereof and, to the best knowledge of
each of the Borrower and IMPSAT, no default has occurred thereunder.

SECTION 7.9 ENVIRONMENTAL MATTERS.

       Each of the Borrower, its Subsidiaries and IMPSAT has duly complied with,
and its business, operations, assets, equipment, property, leaseholds, and other
facilities are in compliance with, all applicable Environmental Laws. None of
the Borrower, its Subsidiaries or IMPSAT has, nor to the knowledge of the
Borrower or IMPSAT after reasonable inquiry, has any other Person, released,
discharged, generated, manufactured, produced, stored, or disposed of in, on,
under, or about any sites of the Borrower, or transported thereto or therefrom,
any hazardous material or Hazardous Substance that could reasonably be expected
to subject the Lenders to any liability or the Borrower, its Subsidiaries or
IMPSAT to any liability that could have a Material Adverse Effect. There is no
proceeding pending against the Borrower, its Subsidiaries or IMPSAT, and to the
best knowledge of the Borrower or IMPSAT after reasonable inquiry, no
investigation or inquiry by any Governmental Authority is threatened or

                                      -41-
<PAGE>   43

contemplated, with respect to the presence or release of hazardous materials or
Hazardous Substances in, on, from, or to the sites of the Borrower.

SECTION 7.10 TRANSACTIONS WITH AFFILIATES.

       Except as disclosed in Schedule 7.10, none of the Borrower, IMPSAT or any
of their respective Subsidiaries are parties to any contract, agreement or
arrangement (whether or not in the ordinary course of business) with the
Borrower, IMPSAT or another Subsidiary of the Borrower or IMPSAT that is not on
an arms-length basis.

SECTION 7.11 INDEBTEDNESS.

       As of September 30, 1999, none of the Borrower, IMPSAT or their
respective Subsidiaries is a party to or bound by any note or agreement with
respect to Indebtedness other than the Indebtedness arising under this Agreement
and the Indebtedness set forth in Schedule 7.11, which is a complete and
accurate list of all Indebtedness of the Borrower, IMPSAT and their respective
Subsidiaries, showing as of such date the outstanding (or potential) principal
amount thereof, and there has been no material change in the amount or status of
such Indebtedness as of such date.

SECTION 7.12 PROPERTIES.

       (a)    TITLE. The Borrower or a Subsidiary of the Borrower (1) has good
record and marketable title in fee simple (or the Argentine equivalent thereof)
or valid leasehold interests in or rights of use with respect to, all real
property used in the ordinary conduct of the Telecommunications Business, except
for such defects in title as could not, individually or in the aggregate,
reasonably be expected to interfere with the Borrower's ability to conduct such
business as currently conducted or to utilize such properties for their intended
purposes; and (2) is, or will be upon its acquisition thereof in accordance with
the Nortel Contracts, the owner of the Collateral. The property of the Borrower,
its Subsidiaries and IMPSAT is not subject to any Liens other than Permitted
Liens (including those described on Schedule 7.12). The Borrower and the
Subsidiaries have not created and are not contractually obligated to create any
Lien, other than Permitted Liens or Liens to be created or permitted to be
created under the Financing Documents to which they are a party, on or with
respect to any of their assets, rights or revenues.

       (b)    CONDITION. All assets material to the Telecommunications Business
are in good repair, working order and condition (ordinary wear and tear
excepted).

       (c)    BANK ACCOUNTS. Each of IMPSAT, the Borrower and its Subsidiaries
has full right and title to each of its bank accounts, and each such bank
account is not subject to any Lien other than (1) banker's liens, rights of
setoff or similar rights as to such deposit accounts or other funds maintained
with such creditor depository institution or (2) Permitted Liens.

                                      -42-
<PAGE>   44

SECTION 7.13 INTELLECTUAL PROPERTY.

       The Borrower or IMPSAT owns all of the patents, trademarks, permits,
service marks, trade names, copyrights, franchises and formulas, or rights with
respect to the foregoing, used in the marketing of any of the Borrower's and its
Subsidiaries' services (a list of which is attached as Schedule 7.13, as updated
from time to time by notice to the Administrative Agent) and the Borrower owns
or has obtained assignments of all such and other rights of whatever nature
necessary for the present conduct of the Telecommunications Business, without
any known conflict with the rights of others other than as set forth in Schedule
7.13 and except as could not reasonably be expected to have a Material Adverse
Effect.

SECTION 7.14 BOOKS AND RECORDS.

       Each of IMPSAT, the Borrower and its Subsidiaries maintains its books and
records (including appropriate copies, backups and archives of such books and
records) in accordance with standard industry practice, Applicable Law and U.S.
GAAP or Argentine GAAP, as applicable.

SECTION 7.15 THE LICENSES.

       Schedule 7.15 contains a true and complete list of all Licenses owned by
or granted to the Borrower or its Subsidiaries. Each License is legally valid,
in full force and effect, duly registered, not subject to any administrative
review or appeal, or subject to any proceeding the outcome of which could result
in the revocation, in whole or in part, for any reason not within the control of
the Borrower or IMPSAT. The Borrower has paid when due all amounts required to
be paid and otherwise has complied with all conditions the compliance with which
is required in order to preserve its rights under the Licenses. No Licenses
other than those listed in Schedule 7.15 are required in order for the Borrower
and its Subsidiaries to install, exploit and operate the Network and to engage
in the Telecommunications Business as it is currently conducted by them, and as
contemplated by the Borrower Business Plan.

SECTION 7.16 NO MATERIAL ADVERSE CHANGE.

       Except as indicated in Schedule 7.16, there has been no Material Adverse
Change since December 31, 1998.

SECTION 7.17 INSURANCE.

       The insurance policies and coverage required by Section 8.1(d) are in
full force and effect, all premiums and other payments required thereunder have
been timely paid and such policies and coverage are otherwise not subject to
cancellation by the insurer during the respective terms thereof, except for
nonpayment of premiums, in which case at least fifteen (15) days prior written
notice of termination must be given to the Administrative Agent.

                                      -43-
<PAGE>   45

SECTION 7.18 COLLATERAL.

       As of each Disbursement Date, all actions necessary for the establishment
and perfection of the Collateral Agent's Lien on the Collateral to be acquired
by the Borrower as of such date, including any required consents,
acknowledgments, filings, registration, notarization or recordation thereof, and
the payment of all related fees, taxes and expenses shall have been completed,
and the Collateral Agent (on behalf of the Secured Parties) shall have an
effective, valid, legally binding and enforceable Lien on the Collateral, which
Lien is superior and prior to the Liens of all third parties (other than the
Permitted Liens).

SECTION 7.19 INVESTMENT COMPANY ACT.

       None of the Borrower, IMPSAT or any of their respective Subsidiaries is
an investment company within the meaning of the Investment Company Act of 1940,
as amended, or, directly or indirectly, controlled by or acting on behalf of any
Person that is an investment company, within the meaning of said Act.

SECTION 7.20 IMMUNITY.

       The execution, delivery, and performance of the Financing Documents and
the other Project Agreements constitute private and commercial acts rather than
governmental or public acts. Under Applicable Law, neither the Borrower, IMPSAT,
nor any of their respective Subsidiaries nor any of their respective revenues or
properties has any right of immunity from suit, court jurisdiction, attachment
prior to judgment, attachment in aid of execution of a judgment, execution of a
judgment or from set-off, Liens, counterclaim or any other legal process or
remedy with respect to its obligations under the Financing Documents or the
other Project Agreements.

SECTION 7.21 TRUE AND COMPLETE DISCLOSURE.

       All information heretofore or hereafter furnished by or on behalf of the
Borrower or IMPSAT or any of their respective Subsidiaries to the Agents or the
Lenders, and all representations and warranties made herein, are true and
correct in all material respects, and do not contain any material misstatement
of fact or omit to state a material fact necessary to make the statements
contained therein not misleading at such time.

                              SECTION 8. COVENANTS.

SECTION 8.1 AFFIRMATIVE COVENANTS.

       Until payment in full of the Obligations and so long as this Agreement
remains in effect, the Borrower shall, and shall cause its Subsidiaries to,
comply with each of the following covenants and agreements:

                                      -44-
<PAGE>   46

       (a)    ANNUAL AND QUARTERLY REPORTING REQUIREMENTS. The Borrower shall
deliver to the Administrative Agent:

              (1)    as to the Borrower:

                     (i)    within ninety (90) days of the close of each fiscal
year of the Borrower, a copy of the consolidated annual financial statements of
the Borrower and its Subsidiaries (including its consolidated balance sheet as
at the close of such calendar year, consolidated statements of income, retained
earnings and changes in financial position or of cash flow, as the case may be,
for such fiscal year with related notes specifying significant accounting
practices and their impact on such financial statements and with related
schedules), and accompanied by an opinion thereon of the Independent Auditor
that is satisfactory to the Administrative Agent, which opinion shall state,
subject to no qualifications, that said financial statements fairly present the
financial condition and results of operations of the Borrower and its
Subsidiaries, as at the end of, and for, such fiscal year and that said
financial statements have been prepared in accordance with Argentine GAAP or
U.S. GAAP. Such annual financial statements shall be in the English language
and, in the case that such financial statements have been prepared in accordance
with Argentine GAAP, shall be accompanied by a reconciliation to U.S. GAAP of
the Borrower's net income and shareholders' equity and convenience translations
to Dollars. From time to time, at the request of the Administrative Agent, the
Borrower shall deliver to the Administrative Agent such additional financial
information as the Administrative Agent may request; and

                     (ii)   as soon as practicable, and in any event within
forty-five (45) days after the end of each of the first three (3) quarters of
each fiscal year of the Borrower, the unaudited consolidated financial
statements of the Borrower and its Subsidiaries for such period and for the
period from the beginning of the respective fiscal year to the end of such
quarterly period and the related balance sheets at the end of such period,
setting forth in each case in comparative form the corresponding figures for the
corresponding period in the preceding fiscal year accompanied by a certificate
of the Chief Financial Officer of the Borrower, which certificate shall state
that such financial statements fairly present the financial condition and
results of operations, as the case may be, of the Borrower in accordance with
Argentine GAAP or U.S. GAAP, as at the end of, and for, such period (subject to
normal year end audit adjustments), and, in the case that such financial
statements have been prepared in accordance with Argentine GAAP, by a
reconciliation to U.S. GAAP of the Borrower's net income and shareholders'
equity and convenience translations to Dollars.

              (2)    as to IMPSAT:

                     (i)    within ninety (90) days of the close of each fiscal
year of IMPSAT, a copy of the annual consolidated financial statements of IMPSAT
and its Subsidiaries (including its balance consolidated sheet as at the close
of such calendar year, consolidated statements of income, retained earnings and
changes in financial position or of cash flow, as the case may be, for such
fiscal year with related notes specifying significant accounting practices and
their impact on such financial statements and with related schedules), and
accompanied by an opinion thereon

                                      -45-
<PAGE>   47

of the Independent Auditor that is satisfactory to the Administrative Agent,
which opinion shall state, subject to no qualifications, that said financial
statements fairly present the financial condition and results of operations of
IMPSAT and its Subsidiaries, as at the end of, and for, such fiscal year and
that said financial statements have been prepared in accordance with U.S. GAAP.
Such annual financial statements shall be in the English language. From time to
time, at the request of the Administrative Agent, IMPSAT shall deliver to the
Administrative Agent such additional financial information as the Administrative
Agent may request; and

                     (ii)   as soon as practicable, and in any event within
forty-five (45) days after the end of each of the first three (3) quarters of
each fiscal year of IMPSAT, the consolidated unaudited financial statements of
IMPSAT and its Subsidiaries for such period and for the period from the
beginning of the respective fiscal year to the end of such quarterly period and
the related balance sheets at the end of such period, setting forth in each case
in comparative form the corresponding figures for the corresponding period in
the preceding fiscal year accompanied by a certificate of the Chief Financial
Officer of IMPSAT which certificate shall state that such financial statements
fairly present the financial condition and results of operations, as the case
may be, of IMPSAT and its Subsidiaries in accordance with U.S. GAAP, as at the
end of, and for, such period (subject to normal year end audit adjustments).

       (b)    ADDITIONAL REPORTING REQUIREMENTS.

              (1)    Without prejudice to the requirement to have such documents
approved by the Administrative Agent, promptly upon the execution and delivery
thereof, the Borrower shall provide the Administrative Agent with copies of all
Project Agreements (including any amendments, additions or replacements).

              (2)    Promptly upon the completion thereof and in no event later
than thirty (30) days thereafter, the Borrower shall provide the Administrative
Agent with a copy of any material amendment, addition or revised version of each
of the Business Plans.

              (3)    Promptly upon the execution and delivery thereof, the
Borrower shall provide the Administrative Agent with copies of all agreements
regarding leases and similar transactions contemplated by Section 8.2(n);
provided that the Administrative Agent shall maintain the confidentiality of the
parties, terms and conditions of such agreements subject to the exceptions
contained in the first paragraph of Section 16.11.

              (4)    From time to time, the Borrower shall deliver to the
Administrative Agent such other information regarding the business of the
Borrower, its Subsidiaries, IMPSAT, the Project, the Network and the
Telecommunications Business as the Administrative Agent may reasonably request.

       (c)    NOTICES. The Borrower shall promptly, but in no event later than
three (3) Business Days after (unless otherwise indicated below) the Borrower
obtains knowledge of the occurrence of the following events, give notice to the
Administrative Agent of the occurrence of any of the following:

                                      -46-
<PAGE>   48

              (1)    a Default or an Event of Default;

              (2)    a default by the Borrower, IMPSAT or any of their
Affiliates under any Project Agreement;

              (3)    except as disclosed in Schedule 7.5 or which could not
reasonably be expected to have a Material Adverse Effect, any (i) (A)
commencement or Material Adverse Change in respect of any litigation,
investigation or proceeding of or before any arbitrator or Governmental
Authority; or (B) any material litigation, investigation or proceeding of or
before any arbitrator or Governmental Authority which, to the knowledge of the
Borrower is threatened by or against the Borrower, IMPSAT, any of their
respective Subsidiaries, or against any of their properties or revenues which:
(x) purport to affect or pertain to this Agreement or any of the other Project
Agreements 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 any other
Project Agreements, 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 any of the
other Project Agreements, including provisions regarding the granting of Liens
on the Collateral or the priority of such Liens;

              (4)    during the Commitment Period, any Material Adverse Change
as determined by the Borrower in its reasonable judgment;

              (5)    thirty (30) days prior to the movement of any Equipment or
any other Collateral outside of Argentina having, in the aggregate, at any time,
a replacement value in excess of five million Dollars (US$5,000,000); and

              (6)    thirty (30) days prior thereto in writing, the movement of
the principal place of business of the Borrower or IMPSAT to any location other
than as set forth in the Security Documents;

              (7)    ten (10) days prior thereto in writing, of any intention on
the part of the Borrower or its Subsidiaries to incur additional Indebtedness
for money borrowed (other than Indebtedness to IMPSAT) in one or more
transactions in an aggregate principal amount exceeding thirty million Dollars
(US$30,000,000) in any given fiscal year.

       The Administrative Agent and the Collateral Agent shall have the right to
request, with respect to any such notice, a statement of an Authorized Officer
of the Borrower setting forth reasonable details of the occurrence referred to
therein and stating what action the Borrower proposes to take with respect
thereto.

                                      -47-
<PAGE>   49

       (d)    INSURANCE. The Borrower shall:

              (1)    maintain or cause to be maintained in full force and effect
to the satisfaction of the Administrative Agent in its sole discretion, at all
times on and after the date hereof and continuing until the Maturity Date, with
responsible insurance companies having a Best Insurance Reports rating of A or
better and a financial size category of "10" or higher (or other companies
reasonably acceptable to the Administrative Agent and in an amount not less than
the amount of all the Loans, and in any event, not less than the full
replacement cost of all Collateral):

                     (i)    all first risk property insurance, including
earthquake, windstorm and flood, with a limit of loss per occurrence acceptable
to the Administrative Agent in its sole discretion from time to time;

                     (ii)   equipment and machinery breakdown insurance covering
breakdown and resulting damage including rotating equipment such as generators
and electrical equipment (including transformers, switch gear and electrical
apparatus) for their full replacement value;

                     (iii)  business interruption insurance covering risk of
loss as a result of the cessation or material interruption of the
Telecommunications Business resulting from an insured loss under the Borrower's
property policy for an indemnity period of six (6) months or any part thereof,
the initial amount of such insurance to provide for the payment during the six
(6) months commencing from the date hereof of not less than the gross revenues
to be earned by the Borrower for such six (6) month period, calculated based on
the Business Plans and to be adjusted by the Borrower semiannually from the date
hereof thereafter, less any non-continuing costs and expenses during the
relevant indemnity period; and

                     (iv)   third party liability insurance, including bodily
injury and property damage, with a limit of no less than two million Dollars
(US$2,000,000) per occurrence.

              (2)    within sixty (60) days after receipt by the Borrower of a
written request from the Administrative Agent, accompanied by a pro forma
political risk insurance policy which contains terms and conditions commercially
reasonable under then current market conditions, and the obtention of which will
not increase the "all-in" financing cost of the Facility to the Borrower, obtain
such a policy and maintain such political risk insurance in full force and
effect until the Maturity Date.

              (3)    file with the Administrative Agent not more than seven (7)
days after each policy anniversary, certificates of all insurance then in
effect, stating the names of the insurance companies, the amounts of the
insurance, the dates of the expiration thereof and the properties and risks
covered thereby and specifically listing the special provisions enumerated for
such insurance required by this Section 8.1(d).

       The certificates of insurance referred to in clause (3) hereof shall be
executed by an authorized representative of each insurer, and certify that all
premiums and other payments

                                      -48-
<PAGE>   50

required in respect of such insurance have been timely paid and that such
insurance is otherwise not subject to cancellation by the insurer during its
term, except for nonpayment of premiums, in which case at least fifteen (15)
days prior written notice of termination must be given to the Administrative
Agent. Upon request, the Borrower will promptly furnish the Agents with evidence
of such insurance relating to the Collateral and all information relating to the
replacement cost and location of the same.

       In each case, the insurance policies shall designate the Administrative
Agent as additional insured in respect of the liability insurance related to the
Equipment and the sole loss payee in respect of the property insurance related
to the Equipment. All amounts payable to the Administrative Agent according to
the foregoing under property insurance policies shall be paid to an account of
the Administrative Agent (i) upon the occurrence of an Event of Default; or (ii)
if the insured loss materially impairs the Borrower's ongoing operations. In
such event, funds received by the Administrative Agent under such property
insurance policies shall be made available to the Borrower for application to
the costs of repairing, restoring, rebuilding or replacing the portion of the
Collateral with respect to which such proceeds were obtained; provided that,
subject to the provisions of Sections 3.2 and 9.1 hereof, such repaired,
restored, rebuilt or replaced asset shall be or become a part of the Collateral.
The Administrative Agent shall at the request of the Required Lenders pay any
insurance premiums directly, on Borrower's behalf, and Borrower shall reimburse
Lenders through the Administrative Agent promptly for any such payment made by
Lenders.

       (e)    COMPLIANCE WITH APPLICABLE LAW. The Borrower shall, and shall
cause its Subsidiaries to comply in all material respects with the requirements
of all Applicable Law, including obtaining and maintaining all Governmental
Approvals.

       (f)    CONSTRUCTION OF THE NETWORK. The Borrower shall (1) cause the
construction and development of the Network to be completed in accordance with
the Business Plans and otherwise with due diligence and continuity (except for
interruptions due to Force Majeure), in a good and workmanlike manner and in
accordance with the Licenses, the Applicable Permits, Applicable Law, and the
Project Agreements, and (2) operate and maintain the Network, and retain and
maintain the staff sufficient to operate and maintain the Network, in accordance
with the Project Agreements and the Business Plans, and otherwise comply in all
material respects with, and satisfy the requirements of, all Licenses, the
Project Agreements and Applicable Laws. Not later than ten (10) days after the
first day of each calendar quarter, the Borrower shall submit to the
Administrative Agent, upon the Administrative Agent's request, a progress report
on the Project. Such report shall identify, and provide the details of, any
delays or variances from the Business Plans and shall contain such other
information in connection therewith as the Administrative Agent may reasonably
request.

       (g)    TAXES, ETC. The Borrower shall pay, or arrange for payment, prior
to the date when due of all (1) taxes imposed on the Borrower and its
Subsidiaries, and (2) present and future claims, levies, or liabilities
(including, without limitation, claims for labor, service, materials and
supplies) for sums which have become due and payable and which, if unpaid, might
by law become a Lien or otherwise have a Material Adverse Effect, except for any
such tax, claim, levy or liability the payment of which is being contested in
good faith by proper

                                      -49-
<PAGE>   51

proceedings for which adequate reserves determined in accordance with Argentine
GAAP have been established and are being maintained, (and as to which it or its
property is not yet subject to foreclosure, seizure, arrest, sale, collection,
levy or loss on account thereof). The Borrower shall make timely filings of all
tax returns and material governmental reports required to be filed or submitted
under any Applicable Laws.

       (h)    MAINTENANCE OF BOOKS AND RECORDS; ACCESS. The Borrower shall, and
shall cause each of its Subsidiaries to, keep adequate books and records of
account, in which complete entries will be made in accordance with Argentine
GAAP, reflecting the financial condition of the Borrower and its Subsidiaries
and shall permit the Administrative Agent and the Lenders, at all reasonable
times and with prior notice to the Borrower, at the expense of the Lenders prior
to an Event of Default but at the Borrower's expense thereafter, to inspect and
have access to the books and records of such Person and make copies thereof, and
to discuss such books and records with the representatives, employees and
accountants of such Person and with the Independent Auditor.

       The Borrower shall promptly supply to the Administrative Agent copies of
any reports on its or its Subsidiaries' business and activities which are
publicly distributed as well as any other reports thereon and reports made to
any Governmental Authority as the Administrative Agent may from time to time
reasonably request.

       The Borrower shall maintain an adequate billing, software and accounting
system, including books, accounts and records, and shall prepare all financial
statements required hereunder in accordance with Argentine GAAP, consistently
applied, and in compliance with all Applicable Laws.

       (i)    RANK OF DEBT. The Borrower shall take any and all action necessary
to ensure that the Loans at all times continue to be the direct and
unconditional obligation of the Borrower and rank at least pari passu (in
respect of priority of payment, security or otherwise) to all other secured or
unsecured Indebtedness of the Borrower, except that such ranking shall not apply
to the rights of secured Indebtedness over collateral subject to Permitted
Liens.

       (j)    PAYMENT OF OBLIGATIONS. The Borrower shall pay, and shall cause
each of its Subsidiaries to pay its obligations that, if not paid, could result
in a Material Adverse Effect, before the same shall become delinquent or in
default, except where: (1) the validity or amount thereof is being contested in
good faith by appropriate proceedings, (2) adequate reserves have been
established with respect thereto in accordance with Argentine GAAP, and (3) the
failure to make payment pending such contest could not reasonably be expected to
result in a Material Adverse Effect.

       (k)    ENVIRONMENTAL MATTERS. The Borrower shall promptly give to the
Administrative Agent notice in writing if the Borrower or any Subsidiary thereof
(1) receives any complaint, order, citation or other written communication from
any Person with respect to, or (2) otherwise acquires actual knowledge of (i)
the existence or alleged existence of any Environmental Liability or any actual
or alleged violation of any applicable Environmental Law arising at, upon,
under, within or in connection with any property now or previously owned,

                                      -50-
<PAGE>   52
leased, operated or used by the Borrower, IMPSAT or any of their respective past
or present Subsidiaries, or any part thereof, or due to the operations or
activities of any such Person, on or in connection with such property or any
part thereof (including receipt by the Borrower or its Affiliates of any notice
of the happening of any event involving the release of a reportable quantity of
any Hazardous Substance under any applicable Environmental Law or cleanup of any
Hazardous Substance), (ii) any release of any Hazardous Substance on such
property or any part thereof in a quantity that is reportable under any
applicable Environmental Law, (iii) the commencement of any cleanup pursuant to
or in accordance with any applicable Environmental Law of any Hazardous
Substances on or about such property or any part thereof, and (iv) any pending
or threatened proceeding for the termination, suspension or non-renewal of any
permit required under any applicable Environmental Law.

       (l)    LICENSES. The Borrower shall, and shall cause its Subsidiaries (1)
to maintain the Licenses in full force and effect, at all times on and after the
date hereof; and (2) upon receipt of any notification from any Governmental
Authority that the Borrower is in breach of any License: (i) promptly notify the
Administrative Agent thereof, providing copies of all relevant documents and
other information; and (ii) take prompt and adequate remedial action to remedy
such breach, which action shall be taken within the cure period, if any, set out
in such notification.

       (m)    REGULATORY FILINGS. The Borrower shall, and shall cause its
Subsidiaries to, deliver to the Administrative Agent, promptly after the sending
or filing thereof, copies of all non-confidential reports filed by the Borrower,
any of its Subsidiaries or IMPSAT with the SC, the United States Securities and
Exchange Commission, the Central Bank, the Argentine National Securities
Commission (Comision Nacional de Valores) or the Buenos Aires Stock Exchange and
all non-confidential reports filed with any other Governmental Authority,
except, in all such cases, reports the failure of which to be filed could not
reasonably be expected to have a Material Adverse Effect.

       (n)    CONTINUANCE OF BUSINESS. The Borrower shall, and shall cause its
Subsidiaries to, do or cause to be done all things necessary to maintain, renew
and keep in full force and effect (i) the Licenses, (ii) their respective
corporate existence and (iii) all other rights and privileges and franchises
related to Telecommunications Business, except in the case of clauses (ii) and
(iii) to the extent that the failure to do so would not have a Material Adverse
Effect.

SECTION 8.2 NEGATIVE COVENANTS.

       Until the Maturity Date, and so long as this Agreement remains in effect,
the Borrower shall comply in all respects with each of the following covenants
and agreements:

       (a)    FUNDAMENTAL CHANGES. The Borrower shall not, and shall not permit
its Subsidiaries to, dissolve, liquidate, merge with another Person or, except
as permitted by Section 8.2(k), create any new Subsidiary without the prior
written consent of the Administrative Agent on behalf of the Required Lenders.

       (b)    LIENS. The Borrower shall not, and shall not permit its
Subsidiaries to, create, incur, assume or suffer to exist, any Lien upon or with
respect to such Person's accounts

                                      -51-
<PAGE>   53

receivable, the Collateral, any rights under the Licenses or in and to the
Network or the Project Agreements other than any Permitted Lien.

       (c)    RESTRICTED PAYMENTS. The Borrower agrees, effective as of the date
that such agreement will not cause IMPSAT to violate its obligations under the
IMPSAT Indentures, not to, and to cause its Subsidiaries not to:

              (1)    reduce or increase such Person's capital, except to the
extent that any such action is required for the Borrower to comply with the
covenants contained in Section 8.3; or

              (2)    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, the 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.

       (d)    GUARANTEES. The Borrower shall not, and shall not permit its
Subsidiaries to, enter into or become bound by any agreements guaranteeing the
Indebtedness of another Person, except as permitted by clauses (d), (e), (f) and
(j)of the definition of "Permitted Indebtedness."

       (e)    DOCUMENT AMENDMENTS. The Borrower shall not, and shall not permit
its Subsidiaries to, agree to any modification, amendment, waiver, supplement,
rescission or termination (collectively, "AMENDMENT") of any (i) License, (ii)
Governmental Approval (other than Licenses) or (iii) Project Agreement, without,
in each case, the prior written approval of the Administrative Agent on behalf
of the Required Lenders, 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 clause (i), the Borrower shall give the Administrative Agent
no less than five (5) Business Days' prior written notice of such Person's
proposed Amendment during which period the Administrative Agent shall have the
exclusive right (which it shall not exercise unreasonably) to reject such
Amendment.

       (f)    TRANSACTIONS WITH AFFILIATES. Except as expressly permitted by
this Agreement, the Borrower shall not, and shall not permit its Subsidiaries
to, directly or indirectly, enter into any transaction with an Affiliate, except
in the ordinary course of and pursuant to the reasonable requirements of the
business of the Borrower and upon commercially reasonable terms no less
favorable to the Borrower than those that could be obtained on an arm's length
basis from a Person which is not an Affiliate.

       (g)    INDEBTEDNESS. The Borrower shall not, and shall not permit its
Subsidiaries to, incur, create, assume or suffer to exist, or permit to incur,
create, assume or suffer to exist, or

                                      -52-
<PAGE>   54

become or remain liable, for or on account of any Indebtedness except (1)
Indebtedness hereunder, and (2) Permitted Indebtedness in an amount such that
the Borrower remains in compliance with the covenants set forth in Section
8.3(a) and Section 8.3(b).

       (h)    NON-RELATED ACTIVITIES. The Borrower shall not, and shall not
permit its Subsidiaries to, engage, directly or indirectly, in any activity,
unless such activity is, directly or indirectly, related to the
Telecommunications Business without the prior written consent of the
Administrative Agent on behalf of the Required Lenders.

       (i)    CORPORATE ACTIONS. The Borrower shall not, and shall not permit
its Subsidiaries to, (i) change or otherwise alter the end of such Person's
fiscal year or such Person's corporate purpose, or (ii) otherwise amend such
Person's Charter Documents in any manner without the prior written consent of
the Administrative Agent on behalf of the Required Lenders; except in the case
of clause (ii) as could not reasonably be expected to have a Material Adverse
Effect.

       (j)    DISPOSALS. Except in respect of the Global Crossing IRU, the
Borrower shall not, and shall not permit its Subsidiaries to (whether by a
single transaction or a number of related or unrelated transactions and whether
at one time or over a period of time) (A) grant an IRU in respect of any of such
Person's property or assets or (B) Dispose of (1) the Collateral, (2) any rights
under the Licenses or in and to the Network, (3) such Person's accounts
receivable, (4) any of the Equipment (whether or not it is part of the
Collateral) or (5) all or a substantial part of such Person's assets without, in
the case of each of (A) and (B), the prior written consent of the Administrative
Agent on behalf of the Required Lenders. Clause (5) of this Section 8.2(j) shall
not apply to (i) any Disposal on normal commercial terms in the ordinary course
of business of property or of obsolete property or (ii) the return of Equipment
in accordance with the Nortel Contracts.

       (k)    INVESTMENTS. The 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 or be merged or consolidated with or into or
transfer or convey all or substantially all its assets to, the Borrower or a
Subsidiary thereof; provided that (1) such Person's primary business is related,
ancillary or complementary to the Telecommunications Business, (2) immediately
before and immediately after the date of such Investment, the Borrower is in
compliance with the covenants contained in Section 8.3 as determined on a pro
forma basis, and (3) such Person (except where such Person is merged into the
Borrower or a Subsidiary thereof) agrees in writing to be bound by the terms of
the Financing Documents; and provided further that an Investment will not be
permitted under this 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 Borrower's net worth immediately preceding such Investment.

       (l)    CHANGE IN ACCOUNTING POLICIES. The Borrower shall not, and shall
not permit any of its Subsidiaries to, make any change in accounting policies or
reporting practices (including changing its fiscal year) which, individually or
in the aggregate, materially affects any determination as to the Borrower's
compliance with its Obligations, including any financial covenants, without the
prior written consent of the Administrative Agent on behalf of the

                                      -53-
<PAGE>   55
Required Lenders; provided, that if such change is required by Argentine GAAP,
the Borrower shall, prior to making such change, only be required to notify the
Administrative Agent of such change and the effect thereof.

       (m)    CAPITAL MARKETS TRANSACTIONS. The Borrower shall not, and shall
not permit any of its Subsidiaries to issue, or offer to issue any debt or
equity securities of Borrower or any Subsidiary thereof in a public offering,
private placement or other capital markets transaction prior to January 1, 2000.

       (n)    LEASES. The Borrower shall not, and shall not permit any of its
Subsidiaries to, without the prior written consent of the Administrative Agent
on behalf of the Required Lenders, enter into any lease (including a Long Term
Lease) or similar transaction with any Person for the use of any part of the
Network except leases or similar transactions in respect of which the lessee
acknowledges in writing, after the Lien on the property to be leased has been
perfected under the applicable Security Document, the existence of such Lien and
the right of the Collateral Agent, upon the occurrence of certain events, to
assume the rights of the Borrower under the lease, including the right to
receive payment thereunder.

SECTION 8.3 FINANCIAL COVENANTS.

       (a)    BORROWER'S NET DEBT TO PAID IN CAPITAL. The Borrower shall not at
any time permit the ratio of (i) the Borrower's Net Debt outstanding on the last
day of any calendar quarter set forth below to (ii) the Borrower's Paid in
Capital on such date, to exceed the ratio set forth opposite such date:

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------- ---------------------
                                     CALENDAR QUARTER                                              RATIO
------------------------------------------------------------------------------------------- ---------------------
<S>                                                                                            <C>
The first calendar quarter of 2000 and each calendar quarter thereafter through the
second calendar quarter of 2003.                                                                   2.0:1
------------------------------------------------------------------------------------------- ---------------------
</TABLE>

       (b)    BORROWER'S NET DEBT TO TOTAL EQUITY. The Borrower shall not at any
time permit the ratio of (i) the Borrower's Net Debt outstanding on the last day
of any calendar quarter set forth below to (ii) the Borrower's Total Equity on
such date, to exceed the ratio set forth opposite such date:

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------- ---------------------
                                     CALENDAR QUARTER                                              RATIO
------------------------------------------------------------------------------------------- ---------------------
<S>                                                                                            <C>
The third calendar quarter of 2003 and each calendar quarter thereafter through the
fourth quarter of 2004.                                                                            2.0:1
------------------------------------------------------------------------------------------- ---------------------

The first calendar quarter of 2005 and each calendar quarter thereafter.                           1.5:1
------------------------------------------------------------------------------------------- ---------------------
</TABLE>

                                      -54-
<PAGE>   56

       (c)    DEBT SERVICE COVERAGE RATIO. The Borrower shall not at any time
permit the ratio of (i) the Borrower's EBITDA for the four (4) consecutive
calendar quarters ending on the date set forth below to (ii) the Borrower's Debt
Service for such four (4) consecutive calendar quarter period, to be less than
the ratio set forth opposite such date:

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------- ---------------------
                                           DATE                                                    RATIO
------------------------------------------------------------------------------------------- ---------------------

<S>                                                                                                <C>
December 31, 1999 and the last day of each calendar quarter of 2000.                               0.50:1
------------------------------------------------------------------------------------------- ---------------------

The last day of each calendar quarter of 2001.                                                     1.00:1
------------------------------------------------------------------------------------------- ---------------------

The last day of each calendar quarter of 2002 through 2006.                                        1.30:1
------------------------------------------------------------------------------------------- ---------------------
</TABLE>

       (d)    INTEREST SERVICE COVERAGE RATIO. The Borrower shall not at any
time permit the ratio of (i) the Borrower's EBITDA for the four (4) consecutive
calendar quarters ending on the date set forth below to (ii) the Borrower's
Interest Expense for such four (4) consecutive calendar quarter period, to be
less than the ratio set forth opposite such date:

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------- ---------------------
                                           DATE                                                    RATIO
------------------------------------------------------------------------------------------- ---------------------

<S>                                                                                            <C>
December 31, 1999 and the last day of the first, second and third calendar quarters of
2000.                                                                                              0.75:1
------------------------------------------------------------------------------------------- ---------------------

The last day of the fourth calendar quarter of 2000 and the last day of each calendar
quarter of 2001.                                                                                   1.00:1
------------------------------------------------------------------------------------------- ---------------------

The last day of each calendar quarter of 2002.                                                     1.55:1
------------------------------------------------------------------------------------------- ---------------------

The last day of each calendar quarter of 2003.                                                     2.50:1
------------------------------------------------------------------------------------------- ---------------------

The last day of each calendar quarter of 2004, 2005 and 2006.                                      3.50:1
------------------------------------------------------------------------------------------- ---------------------
</TABLE>

       (e)    NET DEBT COVERAGE RATIO. The Borrower shall not at any time permit
the ratio of (i) the Borrower's Net Debt outstanding on the last day of any
calendar quarter set forth below to (ii) the Borrower's EBITDA for the four (4)
consecutive calendar quarters ending on such date, to exceed the ratio set forth
opposite such date:

                                      -55-
<PAGE>   57

<TABLE>
<CAPTION>

------------------------------------------------------------------------------------------- ---------------------
                                     CALENDAR QUARTER                                              RATIO
------------------------------------------------------------------------------------------- ---------------------

<S>                                                                                                <C>
Each calendar quarter of 2000.                                                                     9.00:1
------------------------------------------------------------------------------------------- ---------------------

The first and second calendar quarters of 2001.                                                    8.00:1
------------------------------------------------------------------------------------------- ---------------------

The third and fourth calendar quarters of 2001.                                                    6.00:1
------------------------------------------------------------------------------------------- ---------------------

The first and second calendar quarters of 2002.                                                    6.00:1
------------------------------------------------------------------------------------------- ---------------------

The third and fourth calendar quarters of 2002.                                                    5.00:1
------------------------------------------------------------------------------------------- ---------------------

The first and second calendar quarters of 2003.                                                    5.00:1
------------------------------------------------------------------------------------------- ---------------------

The third and fourth calendar quarters of 2003.                                                    3.00:1
------------------------------------------------------------------------------------------- ---------------------

Each calendar quarter of 2004, 2005 and 2006.                                                      2.50:1
------------------------------------------------------------------------------------------- ---------------------
</TABLE>

       (f)    MAXIMUM ANNUAL CAPITAL EXPENDITURES. The Borrower shall not at any
time permit the Borrower's Capital Expenditures (excluding Capital Expenditures
funded by contributions to Paid in Capital other than contributions required to
maintain the Borrower's compliance with the covenants contained in Sections
8.3(a) and 8.3(b)) for the calendar years set forth below, to exceed the amount
set forth opposite such year:

<TABLE>
<CAPTION>
------------------------------- --------------------------------------------------------------
        CALENDAR YEAR                           MAXIMUM CAPITAL EXPENDITURES
------------------------------- --------------------------------------------------------------
<S>          <C>                                            <C>
             1999                                         US$115,000,000
------------------------------- --------------------------------------------------------------

             2000                                         US$147,000,000
------------------------------- --------------------------------------------------------------

             2001                                          US$24,000,000
------------------------------- --------------------------------------------------------------

             2002                                          US$33,000,000
------------------------------- --------------------------------------------------------------

             2003                                          US$45,000,000
------------------------------- --------------------------------------------------------------

             2004                                          US$46,000,000
------------------------------- --------------------------------------------------------------

             2005                                          US$47,000,000
------------------------------- --------------------------------------------------------------

             2006                                          US$47,000,000
------------------------------- --------------------------------------------------------------
</TABLE>

                                      -56-
<PAGE>   58

provided, however, that Capital Expenditures permitted in any period which are
not used in such period may be carried forward to, and expended in, the next
period.

SECTION 8.4 OPERATIONAL COVENANT.

       The Borrower shall not at any time permit Revenues for any calendar year
set forth below to be less than the amount set forth opposite such date below:

<TABLE>
<CAPTION>
------------------------------- --------------------------------------------------------------
        CALENDAR YEAR                                 MINIMUM REVENUES
------------------------------- --------------------------------------------------------------
<S>          <C>                                           <C>
             1999                                          US$90,000,000
------------------------------- --------------------------------------------------------------

             2000                                         US$120,000,000
------------------------------- --------------------------------------------------------------

             2001                                         US$143,000,000
------------------------------- --------------------------------------------------------------

             2002                                         US$200,000,000
------------------------------- --------------------------------------------------------------

             2003                                         US$295,000,000
------------------------------- --------------------------------------------------------------

             2004                                         US$400,000,000
------------------------------- --------------------------------------------------------------

             2005                                         US$530,000,000
------------------------------- --------------------------------------------------------------

             2006                                         US$623,000,000
------------------------------- --------------------------------------------------------------
</TABLE>

                               SECTION 9. SECURITY

SECTION 9.1 GRANT OF SECURITY INTEREST.

       To secure the prompt payment of the Obligations, and to secure the
performance of and compliance with all the agreements, covenants and provisions
of the Financing Documents, the Borrower shall and shall cause its Subsidiaries,
pursuant to the Security Documents, to grant, assign, pledge and convey to the
Collateral Agent for the benefit of each Secured Party a first-priority security
interest, subject only to Permitted Liens, in all Equipment, real property and
other tangible and intangible property and rights to be acquired by the Borrower
and its Subsidiaries pursuant to the Nortel Contracts (all such property and
rights, together with the cash and cash equivalents held from time to time in
the Net Proceeds Account, collectively, the "COLLATERAL"). Each of the Equipment
Pledge Agreements and Mortgage Deeds shall state as the maximum secured
obligation such amount as shall be designated by the Administrative Agent in its
sole discretion; provided, however, that the aggregate maximum secured amount
stated in all such Security Documents shall not exceed one hundred fifteen
percent (115%) of the amount of

                                      -57-
<PAGE>   59

the Commitment Amount as of the date hereof (as reduced, if applicable, in
accordance with Section 2.5). The Borrower hereby confirms to the Secured
Parties that it shall, and shall cause each of its Subsidiaries to, take all
actions required by the Security Documents or otherwise deemed reasonably
necessary or reasonably desirable by the Collateral Agent in order to create,
perfect and maintain the perfection of the Secured Parties' first-priority Lien
in the Collateral, subject only to Permitted Liens.

SECTION 9.2 ESCROW ACCOUNTS.

       To secure the prompt payment of principal of and interest on the Loans,
the Borrower, pursuant to the Escrow Account Agreement, shall establish and
maintain the Net Proceeds Account and grant to the Administrative Agent for the
benefit of the Secured Parties a first-priority security interest in the Net
Proceeds Account and each other escrow account, if any, and in all funds
deposited therein.

SECTION 9.3 RELEASE OF COLLATERAL.

       (a)    SECURITY INTEREST. The Borrower hereby further agrees and confirms
that, except for any Collateral released pursuant to Section 9.3(b), the Secured
Parties' security interest in the Collateral shall not be released by the
Collateral Agent until and unless (1) the Borrower shall have paid in full all
amounts due and payable under this Agreement and under any Security Document and
shall have performed all of its Obligations or (2) the Required Lenders shall
have consented to such release, in their sole discretion.

       (b)    RELEASE INSTRUMENTS. In connection with any Disposal of Collateral
permitted by the terms hereof, the Borrower may request a release of such
Collateral (the "RELEASED COLLATERAL") by delivering to the Collateral Agent a
notice (each, a "RELEASE NOTICE"), which shall refer to this Section, describe
in reasonable detail the proposed Released Collateral and be accompanied by (1)
an officer's certificate of the Borrower certifying that no Event of Default has
occurred and is continuing and that the officers of the Borrower executing any
and all documents in connection with the release were duly authorized to do so
and (2) the proposed instrument of release (the "RELEASE") executed by all
necessary parties thereto other than the Collateral Agent (collectively, the
"RELEASE INSTRUMENTS").

       (c)    COUNTERPARTS. The Collateral Agent shall execute, acknowledge, if
applicable, and deliver to the Borrower counterparts of the documents described
in Sections 9.3(b)(1) and 9.3(b)(2) within five (5) Business Days of receipt by
the Collateral Agent of a Release provided that the conditions set forth in the
Release Instruments and herein with respect to dispositions of Collateral have
been satisfied. The Borrower at its own expense shall execute, deliver, obtain
and record such instruments as the Collateral Agent may reasonably require,
including, without limitation, amendments to the Security Documents or this
Agreement necessary to reflect such release. The Borrower shall reimburse the
Collateral Agent upon demand for all reasonable costs and expenses (including
reasonable attorneys' fees and expenses) incurred by the Collateral Agent in
connection with any actions taken by it pursuant to this Section.

                                      -58-
<PAGE>   60

                          SECTION 10. EVENTS OF DEFAULT

SECTION 10.1            EVENTS OF DEFAULT.

Each of the following events shall constitute an "EVENT OF DEFAULT" hereunder:

       (a)    NON-PAYMENT. The Borrower shall fail to pay:

              (1)    any installment of the principal amount of any Loan as and
when the same becomes due and payable hereunder (whether at stated maturity, by
acceleration, mandatory prepayment or otherwise) ; or

              (2)    any interest on any Loan or any other amount payable
hereunder or under any Note, when and as the same shall become due and payable
(whether at stated maturity, by acceleration, mandatory prepayment or otherwise)
and such failure shall continue unremedied for three (3) Business Days.

       (b)    REPRESENTATIONS AND WARRANTIES. Any representation, warranty,
certification or statement made by or on behalf of the Borrower, any Subsidiary
thereof or IMPSAT in any Financing Document or any amendment thereof or in any
certificate, report, or opinion delivered pursuant to or otherwise in connection
with any Financing Document shall prove to have been false, incorrect, or
misleading in any material respect as of the time made, delivered or deemed made
or delivered.

       (c)    COVENANTS. The Borrower, any Subsidiary thereof or IMPSAT shall
fail to perform or observe in any material respect any term, covenant, condition
or agreement:

              (1)    contained in this Agreement (other than the covenants
contained in Section 8.1 or paragraphs (f), (g) and (h) of Section 8.2) or any
other Financing Document and such default shall continue beyond any cure or
grace period specifically applicable thereto pursuant to the terms of such
Financing Document; or

              (2)    contained in Section 8.1 or paragraphs (f), (g) and (h) of
Section 8.2) hereof and such default shall continue unremedied for a period of
ten (10) Business Days after the earlier of (i) the date on which the Borrower
obtains knowledge of such default or (ii) the date on which notice thereof shall
have been received by the Borrower from the Administrative Agent (which notice
will be given at the request of any Lender).

       (d)    IMPSAT INDENTURES. IMPSAT or any of its Subsidiaries shall default
in:

              (1)    any payment of any Indebtedness under the IMPSAT
Indentures; or

              (2)    the observance or performance of any agreement, covenant or
condition under the IMPSAT Indentures or any instrument or agreement evidencing,
securing or relating thereto, or any other event shall occur or condition exist,
the effect of which default or other event or condition is to cause, or to
permit the Trustee (under either IMPSAT Indenture), to

                                      -59-
<PAGE>   61

cause any such Indebtedness to become due or subject to mandatory repurchase or
repayment prior to its stated maturity.

       (e)    BRAZIL AGREEMENTS. Declaration of default or notice of
acceleration shall have occurred under the Brazil Financing Agreement or any
other of the Brazil Agreements.

       (f)    DEFAULT UNDER OTHER INDEBTEDNESS. The Borrower, any Subsidiary
thereof or IMPSAT shall default in:

              (1)    any payment of any Indebtedness (other than the Loans under
this Agreement or the loans under the Brazil Financing Agreement) aggregating in
excess of five million Dollars (US$5,000,000); or

              (2)    the observance or performance of any agreement or condition
relating to any Indebtedness (other than the Financing Documents or the IMPSAT
Indentures) aggregating in excess of five million Dollars (US$5,000,000), or
contained in any instrument or agreement evidencing, securing, or relating
thereto, or any other event shall occur or condition exist, the effect of which
default or other event or condition is to cause, or to permit the holder of such
Indebtedness (or a trustee or agent on behalf of such holder) to cause any such
Indebtedness to become due or subject to mandatory repurchase or repayment prior
to its stated maturity.

       (g)    BANKRUPTCY. The Borrower, any Subsidiary thereof or IMPSAT shall
commence a voluntary case concerning itself under any bankruptcy law of
Argentina (including, without limitation, Argentine Law No. 24.522) or any other
jurisdiction or Title 11 of the United States Code entitled "Bankruptcy," as now
or hereafter in effect, or any successor thereto (the "BANKRUPTCY CODE"); or an
involuntary case is commenced against the Borrower, any Subsidiary thereof or
IMPSAT under any such laws, and the petition is not contested within 10 days, or
is not dismissed within 30 days, after commencement of the case; or a custodian
(as defined in the Bankruptcy Code) is appointed for, or takes charge of, all or
substantially all of the property of the Borrower, any Subsidiary thereof or
IMPSAT or the Borrower, any Subsidiary thereof or IMPSAT commences any other
proceeding under any reorganization, arrangement, adjustment of debt, relief of
debtors, dissolution, insolvency or liquidation or similar law of any
jurisdiction whether now or hereafter in effect relating to the Borrower, any
Subsidiary thereof or IMPSAT, or there is commenced against the Borrower, any
Subsidiary thereof or IMPSAT any such proceeding which remains undismissed for a
period of thirty (30) days; or the Borrower, any Subsidiary thereof or IMPSAT is
adjudicated insolvent or bankrupt; or any order of relief or other order
approving any such case or proceeding is entered; or the Borrower, any
Subsidiary thereof or IMPSAT suffers any appointment of any custodian or the
like for it or any substantial part of its property to continue undischarged or
unstayed for a period of thirty (30) days; or the Borrower, any Subsidiary
thereof or IMPSAT makes a general assignment for the benefit of creditors; or
the Borrower, any Subsidiary thereof or IMPSAT shall generally not pay its debts
as they become due or there shall otherwise occur a cesacion de pagos (within
the meaning of Argentine law); or any corporate action is taken by the Borrower,
any Subsidiary thereof or IMPSAT for the purpose of effecting any of the
foregoing.

                                      -60-
<PAGE>   62

       (h)    FINANCING DOCUMENTS. Any Financing Document shall cease to be in
full force and effect, or shall cease to give the Lenders the Liens and the
material rights, powers and privileges purported to be created thereby
(including, without limitation, a perfected security interest in, and Lien on,
all of the Collateral described therein in favor of the Lenders, superior to and
prior to the rights of all third Persons, and subject to Permitted Liens only).

       (i)    NORTEL CONTRACTS. The Borrower shall breach or otherwise fail to
perform any material obligation under any of the Nortel Contracts or any of the
Nortel Contracts shall cease to be in full force and effect for any reason
imputable to the Borrower or an Affiliate thereof except at the stated
termination date thereof or shall be assigned or otherwise transferred,
terminated, or rescinded without the approval of Nortel.

       (j)    OTHER PROJECT AGREEMENTS. The Borrower or any Project Party (other
than Nortel) shall breach or otherwise fail to perform any material obligation
under the Project Agreements (other than the Turnkey Contract) or such other
Project Agreements shall cease for any reason (other than for a reason
attributable to Nortel) to be in full force and effect except at the stated
termination date thereof, or shall be assigned or otherwise transferred,
terminated, or rescinded by any Project Party thereto; provided that it shall
not be an Event of Default if, not later than one hundred twenty (120) days of
any breach or failure by such other Project Party, or the effective date of any
termination or rescission in respect of such other Project Agreement (other than
a termination or rescission based on a breach or failure by the Borrower), such
breach or failure is cured or a substitute vendor enters into a new written
agreement with the Borrower to continue to provide the equipment, systems and
services contemplated under such other Project Agreement on terms that conform
to and will not result in a deviation from the then current Business Plans.

       (k)    LICENSES. Any License necessary for the Project shall cease to be
in full force and effect. A License shall be deemed to cease to be in full force
and effect (1) when an order revoking or terminating said License shall be
issued and such order is no longer subject to further administrative and
judicial review, or (2) when any Governmental Authority having jurisdiction over
any such License shall, prior to the termination thereof, decide not to renew
such License and such decision shall not be subject to further administrative or
judicial review.

       (l)    GOVERNMENTAL ACTIONS. Any Governmental Authority shall have (1)
condemned, nationalized, seized, compulsorily acquired, or otherwise
expropriated all or any material part of the property or other assets of the
Borrower or any of its Subsidiaries or of any capital stock of the Borrower or
any of its Subsidiaries, or (2) assumed custody or control either of such
property or other assets or of the business or operations of the Borrower or any
of its Subsidiaries or of their capital stock, or shall have taken any action
for the dissolution of the Borrower or any of its Subsidiaries or any other
action that would prevent the Borrower or any of its Subsidiaries or their
respective officers from carrying on the business or operations of the Borrower
or any such Subsidiary in all material respects; provided, however, that this
paragraph shall not apply to any Subsidiary of the Borrower (i) the property or
assets of which do not comprise part of the Network or the Collateral, (ii)
which is not a party to any of the Project Documents and (iii) the

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total Equity of which is less than one hundred thousand Dollars (US$100,000),
unless the Governmental Action in question is reasonably likely to have a
Material Adverse Effect.

       (m)    JUDGMENTS. A final judgment, award, decree, fine or penalty for
the payment of money in excess of five million Dollars (US$5,000,000)
individually or in the aggregate shall be rendered by one or more courts,
administrative tribunals or other bodies having jurisdiction against the
Borrower or IMPSAT or any of their respective Subsidiaries and the same shall
not be discharged (or provision satisfactory to the Administrative Agent shall
not be made for such discharge), or a stay of execution thereof shall not be
procured, within thirty (30) days from the date of entry thereof, and the
Borrower, within such thirty (30) day period or such longer period during which
the execution of such judgment or judgments shall have been stayed, shall not
have appealed therefrom and caused the execution thereof to be stayed during
such appeal.

       (n)    CURRENCY RESTRICTIONS. Argentina or any Governmental Authority
thereof shall impose restrictions on the free transferability of Dollars to or
from Argentina or Dollars shall, in the reasonable judgment of the Required
Lenders, be unavailable within Argentina at a commercially reasonable rate of
exchange, and the Borrower shall not, within ten (10) Business Days after notice
from the Administrative Agent, have demonstrated to the satisfaction of the
Administrative Agent that such restrictions will not have a Material Adverse
Effect on the ability of the Borrower to perform its Obligations or on the
availability of Dollars for purposes of paying any amounts required to be paid
pursuant to this Agreement or the other Financing Documents.

       (o)    IMPSAT GUARANTEE. IMPSAT shall breach any covenant or agreement in
the IMPSAT Guarantee.

       (p)    CHANGE IN CONTROL. A Change in Control shall have occurred.

       (q)    LEGAL EXISTENCE; TAXES. The Borrower or IMPSAT shall have failed
to maintain its legal existence or the Borrower, any Subsidiary thereof or
IMPSAT shall have failed to pay taxes as they come due.

       (r)    IMPAIRMENT OF COLLATERAL. The Collateral Agent shall fail at any
time to have a valid and perfected Lien on, subject to no prior or equal Liens
other than Permitted Liens, any material portion of the Collateral.

       (s)    MATERIAL ADVERSE CHANGE. A Material Adverse Change shall have
occurred.

       (t)    CAPITALIZATION. (1) The Borrower shall make any distribution or
payment or transfer any property to IMPSAT or any other Person, directly or
indirectly, in respect of the IMPSAT Capital Contribution or (2) the resolution
of a duly-convened shareholders meeting of the Borrower, in form and content
satisfactory to the Administrative Agent, authorizing the Borrower Capital
Increase shall not have been duly adopted on or before December 31, 1999.

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ECTION 10.2. REMEDIES UPON EVENT OF DEFAULT.

       (a)    RIGHTS AND REMEDIES. If any Event of Default (other than the Event
of Default referred to in Section 10.1(g)) has occurred and is continuing, the
Administrative Agent shall, at the request of, or may, with the consent of the
Required Lenders (1) terminate the Commitment, whereupon the obligation of the
Lenders to make Loans hereunder shall immediately be terminated and/or (2)
declare all of the Loans to be due and payable, whereupon the Loans, together
with interest accrued thereon and all other amounts due under this Agreement and
the Notes, shall immediately mature and become due and payable, without
presentment, demand, diligence, protest, notice of acceleration, or other notice
of any kind, all of which the Borrower hereby expressly waives; or (3) exercise
on behalf of itself and the Lenders all other rights and remedies available to
it and the Lenders under this Agreement and the other Financing Documents. Upon
the occurrence of any Event of Default, the Lenders and the Agents shall have,
in addition to any other rights and remedies contained in this Agreement and the
other Financing Documents, all of the rights and remedies of a secured party
under the laws of Argentina or other Applicable Laws, all of which rights and
remedies shall be cumulative and non-exclusive, to the extent permitted by
Applicable Law.

       (b)    BANKRUPTCY. Upon the occurrence of an Event of Default referred to
in Section 10.1(g) of this Agreement:

              (1)    the Commitment shall automatically be terminated and the
obligation of the Lenders shall immediately terminate;

              (2)    the Loans, together with all interest accrued thereon and
all other amounts due under this Agreement and the Notes, shall immediately
mature and become due and payable, without any other presentment, demand,
diligence, protest, notice of acceleration, or other notice of any kind, all of
which each of the Borrower hereby expressly waives; and

              (3)    the Administrative Agent may, or at the request of the
Required Lenders shall, exercise (or shall direct the Collateral Agent to
exercise) on behalf of itself and the Lenders all other rights and remedies
available to it and the Lenders under this Agreement and the other Financing
Documents.

       (c)    OTHER REMEDIES. In addition to such remedies as are provided for
in this Agreement and the other Financing Documents, the Lenders' remedies upon
the occurrence and during the continuance of an Event of Default shall include,
to the extent permitted by Applicable Law, (1) a right to apply or require the
Borrower to apply for any necessary orders, permits or licenses in connection
with the operation or abandonment of the Network, the Telecommunications
Business or any part thereof; and (2) a right to have a receiver appointed by a
court of competent jurisdiction in order to manage, protect and preserve the
Network, the Telecommunications Business and the Collateral and to continue the
operation of the Telecommunications Business, and to collect the revenues and
profits thereof and apply the same to the payment of all expenses and other
charges of such receivership until the sale or other final disposition of the
Collateral.

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<PAGE>   65

       (d)    ACTIONS. In connection with the foregoing remedies, the Borrower
shall take such further actions and execute all such instruments as the
Administrative Agent or the Collateral Agent deems necessary. The Borrower
agrees that the Administrative Agent or the Collateral Agent may enforce any
obligation of the Borrower as set forth in this Agreement by an action for
specific performance.

       (e)    ADVANCES. The Lenders may (but shall not be obligated to) make
advances from their own funds to preserve, protect or obtain any of the
Collateral, including amounts to pay Taxes, insurance and the like, and all such
advances shall become part of the Obligations and shall be repayable to the
Lenders with interest thereon from the date of such advances until paid at the
Default Interest Rate.

SECTION 10.3 CUMULATIVE RIGHTS.

       No failure or delay on the part of the Lenders, the Administrative Agent
or the Collateral Agent in exercising any right, power, or remedy accruing to
them hereunder shall impair any such right, power, or remedy, nor shall such
failure or delay in exercising any right, power, or remedy with respect to any
particular occurrence of an Event of Default be construed as a waiver of any
such right, power, or remedy for any other or future occurrence of an Event of
Default, nor shall any single or partial exercise of any such right or power
preclude any other or further exercise thereof or the exercise of any other
right or power hereunder. To the fullest extent permitted by Applicable Law, all
remedies, either under this Agreement or by Applicable Law otherwise afforded
the Lenders, shall be cumulative and not alternative.

                    SECTION 11. EXPENSES AND INDEMNIFICATION

SECTION 11.1 EXPENSES.

       The Borrower agrees to pay on demand (a) all reasonable costs and
expenses of the Administrative Agent in connection with the preparation,
execution, delivery, administration, modification, amendment, protocolization
and registration of the Financing Documents, including the reasonable fees and
expenses of counsel for the Agents with respect thereto, with respect to
advising the Agents as to their rights and responsibilities or the perfection,
protection or preservation of their and the Lenders' rights or interests under
the Financing Documents, with respect to negotiations with the Borrower, IMPSAT
or with other creditors of the Borrower or IMPSAT arising out of any Default or
any events or circumstances that may give rise to an Event of Default, and with
respect to presenting claims in or otherwise participating in or monitoring any
bankruptcy, insolvency or other similar proceeding involving creditors' rights
generally and any proceeding ancillary thereto, and (b) all reasonable costs and
expenses of the Agents and the Lenders in connection with the enforcement of the
Financing Documents, including in any action, suit or litigation, any
bankruptcy, insolvency or other similar proceeding affecting creditors' rights
(including, without limitation, the reasonable fees and expenses of counsel for
each Agent and the Lenders with respect thereto).

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SECTION 11.2 INDEMNIFICATION.

       Without regard to whether the Borrower or any other Person has disclosed
any fact to Nortel, the Administrative Agent, the Collateral Agent or any
Lender, the Borrower hereby agrees to indemnify and hold harmless each of the
Agents and Lenders and each of their respective officers, directors, employees,
consultants and advisors (collectively, the "INDEMNITEES") from and against any
and all actions, suits, claims, damages, demands, judgments, losses,
liabilities, costs or expenses whatsoever, including reasonable attorneys' fees,
which any Indemnitee may sustain or incur (or which may be claimed against any
Indemnitee by any Person whatsoever) to the extent arising by reason of or in
connection with:

       (a)    the Loans or the proposed use of the proceeds thereof;

       (b)    the payment or failure to pay the Obligations;

       (c)    the occurrence of an Event of Default;

       (d)    the pursuit by either Agent or any Lender of any legal remedy in
connection with an Event of Default;

       (e)    the entering into any Financing Document by either Agent or any
Lender, or enforcing their remedies hereunder or thereunder; or

       (f)    any Environmental Law as a result of the past, present or future
operations of the Borrower any of its Subsidiaries or IMPSAT (or any predecessor
in interest to any such Persons);

provided, however, that, the Borrower shall not be required to indemnify any
Indemnitee for any actions, suits, claims, damages, demands, judgments, losses,
liabilities, costs or expenses to the extent caused by such Indemnitee's willful
misconduct or gross negligence.

                    SECTION 12. ASSIGNMENT AND PARTICIPATION

SECTION 12.1 ASSIGNMENT.

       (a)    REQUIREMENTS. Each Lender may assign to one or more Eligible
Assignees all or any portion of its rights and obligations under this Agreement
(including, without limitation, all or a portion of its Commitment, the Loans
owing to it and the Note or Notes held by it); provided, however, that (1) each
such assignment shall be of a uniform, and not a varying, percentage of all
rights and obligations under and in respect of all rights and obligations under
this Agreement, (2) except in the case of an assignment to a Person that,
immediately prior to such assignment, was a Lender or an assignment of all of a
Lender's rights and obligations under this Agreement, the amount of any
Commitment proposed to be assigned (determined as of the date of the Assignment
and Assumption Agreement with respect to such assignment) shall in no

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<PAGE>   67

event be less than one million Dollars (US$1,000,000), and (3) the parties to
each such assignment shall execute and deliver an Assignment and Assumption
Agreement.

       (b)    NOTICE. Promptly following an assignment described in (a) above,
the parties to such assignment shall deliver the executed Assignment and
Assumption Agreement entered into between the assignor Lender and the assignee
to the Administrative Agent for its acknowledgment and recording in the Register
together with a non-refundable processing and recordation fee of three thousand
five hundred Dollars (US$3,500). The assigning Lender shall also deliver a
notice to the Borrower in respect of such assignment (unless such notice has
already been given) and the assignee shall furnish the Administrative Agent with
a completed administrative details questionnaire.

       (c)    RECORDING. Upon its receipt of an Assignment and Assumption
Agreement executed by the assignor Lender and the assignee, the Administrative
Agent shall promptly acknowledge such Assignment and Assumption Agreement and
record the information contained therein in the Register in accordance with the
provisions of Section 2.3(d) and give notice of such acknowledgment and
recordation to the Lenders and the Borrower. Any assignment of any Loan or Note
hereunder shall become effective on the day when the relevant Assignment and
Assumption Agreement is recorded by the Administrative Agent in the Register.

       (d)    EXCHANGE OF NOTES. Concurrently with the delivery of an Assignment
and Assumption Agreement to the Administrative Agent pursuant to (c) above, or
as soon thereafter as practicable, the assignor Lender shall surrender the Note
evidencing the Loan being assigned thereunder for cancellation against delivery
to the assignor Lender and/or the assignee of one or more new Notes executed by
the Borrower in the same aggregate principal amount.

       (e)    RELEASE. From and after the date on which an Assignment and
Assumption Agreement is effective and solely to the extent of such assignment,
the assignor Lender shall be released of its commitments and obligations under
this Agreement and the assignee shall thereupon become a Party and shall have
the same rights and interest and assume the same obligations and liabilities as
having been assigned to it by the assignor Lender.

SECTION 12.2 PARTICIPATION.

       Any Lender may sell participations to any Person in or to all or a
portion of its rights and obligations under this Agreement (including, without
limitation, all or a portion of its Commitment, the Loans owing to it and the
Note or Notes held by it), provided, however, that (a) such Lender's obligations
under this Agreement (including, without limitation, its Commitment) shall
remain unchanged, (b) such Lender shall remain solely responsible to the other
Parties for the performance of such obligations, (c) such Lender shall remain
the holder of any such Note for all purposes of this Agreement, and (d) the
Borrower, the Agents and the other Lenders shall continue to deal solely and
directly with such Lender in connection with such Lender's rights and
obligations under this Agreement.

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<PAGE>   68

                     SECTION 13. OPTION TO REVISE STRUCTURE.

SECTION 13.1 OPTION TO REVISE.

       Subject to Applicable Law, at any time after January 1, 2000 (but
excluding the six (6) month period ending on July 31, 2003) the Administrative
Agent on behalf of the Required Lenders shall have the right, upon giving not
less than sixty (60) days' prior written notice to the Borrower, to cause the
structure of the Commitments and the Loans to be revised to facilitate access to
all financial markets, including banks, insurance companies, investment
companies, other financial institutions or governmental agencies, to sell or
refinance the Commitment and/or Loans, including by requiring a portion of the
Loans and Commitment to be replaced by an issuance of debt securities in the
capital markets ("REPLACEMENT NOTES") in an aggregate principal amount of not
less than one hundred twenty five million Dollars (US$125,000,000) (or in the
case of a second or third issuance of Replacement Notes, the lesser of one
hundred twenty five million Dollars (US$125,000,000) and the sum of the Facility
then outstanding hereunder and the Facility then outstanding under the Brazil
Financing Agreement) for the purpose of the prepayment of outstanding Loans of
the Lenders; provided, that any such revisions and/or replacement shall neither
decrease the economic benefit or the term of the Loans or the Commitment to
IMPSAT and the Borrower nor have an "all-in" financing cost in excess of
thirteen percent (13%) per annum. The Lenders and the Borrower shall cooperate
with respect to the determination of the optimal timing for such revisions or
replacement, including for issuance of the Replacement Notes and any other
issuance of debt securities by the Borrower or IMPSAT. Upon receipt of such
notice from the Administrative Agent, the Borrower shall cooperate with the
Placement Agent and Nortel as set forth in Section 16.12 and otherwise provide,
on a best efforts basis, such assistance as is customarily and reasonably
required or desirable to be provided by an issuer to enable the successful
placement of Replacement Notes, under the terms and subject to the conditions
set forth in Sections 13.2 and 13.3 and such other terms and conditions as may
be agreed upon between the Borrower and the Lenders from time to time.

SECTION 13.2 COSTS BORNE BY LENDERS.

       Replacement Notes shall be issued by IMPSAT; provided, that all costs and
expenses incurred in connection with the issuance of Replacement Notes,
including underwriting fees, commissions and the Borrower's and IMPSAT's
out-of-pocket costs associated with the issuance of the Replacement Notes
(including, without limitation, the reasonable fees and expenses of its auditors
and counsel), shall be borne solely by the Lenders; provided further, that the
Parties shall seek to structure the transaction to minimize tax costs.

SECTION 13.3 TERMS OF REPLACEMENT NOTES.

       The Replacement Notes shall be on terms approved by Nortel and consistent
with market practice in the relevant debt securities market. To the extent
political risk insurance is required by and consistent with relevant market
practice, all costs of such insurance shall be borne by the Borrower. To the
extent the rate of withholding tax applicable to Replacement Notes is

                                      -67-
<PAGE>   69

consistent with relevant market practice, the full rate of withholding tax shall
be borne by the Borrower.

SECTION 13.4 APPLICATION OF PROCEEDS.

       A portion of the Net Proceeds of the Replacement Notes shall be applied
to the Prepayment of the Loans in accordance with Section 3.2(a)(6), such
portion to be an amount determined by multiplying such Net Proceeds by a
fraction the numerator of which is the amount of the Facility outstanding
hereunder as of the date of IMPSAT's receipt of such Net Proceeds and the
denominator of which is the sum of the amounts of the Facility outstanding
hereunder and the Facility outstanding under the Brazil Financing Agreement, as
of such date; provided, however, that if the Replacement Notes are issued prior
to the making of any Disbursements under this Agreement or the Brazil Financing
Agreement, the numerator and denominator of the fraction used to determine the
application of the Net Proceeds shall refer to the Commitment Amounts then
available under the respective Financing Agreements, and the Commitment Amount
hereunder shall be reduced by the amount resulting from such calculation; and,
provided, further, that if Disbursements have been made under only one of the
Financing Agreement when the Replacement Notes are issued, the Net Proceeds of
the Replacement Notes shall be applied first in Prepayment of the entire amount
of the Loans under such Financing Agreement, and the Commitment Amount under the
other Financing Agreement shall be reduced by the remaining amount, if any, of
such Net Proceeds.

SECTION 13.5 RELEASE OF OBLIGATIONS.

       After the initial Prepayment pursuant to Section 13.4, and provided that
there shall not then exist a Default or an Event of Default, the Net Proceeds of
Long Term Leases shall not be included in the calculation of Excess Cash Flow
for purposes of Prepayments under Section 3.2(a)(4).

SECTION 13.6 TERMINATION OF OPTION.

       The right of the Administrative Agent provided in Section 13.1 shall
terminate upon Nortel's ceasing to be the beneficial owner of at least fifty
percent (50%) of all Loans outstanding hereunder and under the Brazil Financing
Agreement, taken as a whole or, if no Loans have yet been disbursed, upon
Nortel's ceasing to be obligated in respect of at least fifty percent (50%) of
the Commitment Amount.

                   SECTION 14. GOVERNING LAW AND JURISDICTION

SECTION 14.1 GOVERNING LAW.

       This Agreement and the Notes shall be governed by, and construed in
accordance with, the laws of the State of New York (not including such state's
conflict of laws provisions).

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<PAGE>   70

SECTION 14.2 WAIVER OF JURY TRIAL.

       Each of the Lenders, the Agents and the Borrower hereby knowingly,
voluntarily, and intentionally waives any right it may have to a trial by jury
of any claim, demand, or cause of action under, or in connection with, this
Agreement, the Notes or any other financing document. This provision is a
material inducement for the Lenders to enter into this Agreement and the other
financing documents.

SECTION 14.3 JURISDICTION; VENUE FOR SUIT.

       Each of the Borrower, the Lenders and the Agents hereby expressly and
irrevocably (a) waives all right to object to jurisdiction or execution in any
legal action or proceeding relating to this Agreement, the Notes, or any other
Financing Document which such Person may now or hereafter have by reason of such
Person's domicile or by reason of any subsequent or other domicile and hereby
irrevocably consents that any legal action, suit, or proceeding arising out of,
or relating to, any of the Financing Documents and any other document or
instrument required to be executed in relation thereto may be instituted in or
removed to the United States District Court of the Southern District of New York
and the courts of the State of New York sitting in New York, Borough of
Manhattan; (b) submits to and accepts and consents with regard to any such
action or proceeding for itself and in respect of its properties and assets,
generally and unconditionally, the non-exclusive jurisdiction of any such court;
and (c) waives any objection it may now or hereafter have to the laying of the
venue of any such action, suit, or proceeding, and further waives any claim that
any such action, suit, or proceeding brought in any of the aforesaid courts has
been brought in any inconvenient forum.

SECTION 14.4 WAIVER OF IMMUNITY.

       To the extent that the Borrower or any of its Subsidiaries or any of
their respective assets has, or hereafter may acquire, any right to immunity
from suit, set-off, legal proceedings generally, attachment prior to judgment,
attachment in aid of execution, or other attachment or execution of judgment on
the grounds of sovereignty or otherwise, the Borrower for itself, and its
Subsidiaries hereby irrevocably waives such rights to immunity in respect of
Obligations. In addition, the Borrower hereby irrevocably waives, to the fullest
extent it may effectively do so, the right to demand that either Agent or any
Lender post a performance bond or guarantee (excepcion de arraigo) in any action
or proceeding against the Borrower or its property in Argentina.

SECTION 14.5 PROCESS AGENT.

       The Borrower has appointed CT Corporation System with offices at 111
Eighth Avenue, New York, New York 10011 and its successors as the Borrower's
designee, appointee, and agent to receive, accept and acknowledge, for and on
behalf of the Borrower, service of any and all legal process, summons, notices
and documents which may be served in such action, suit or proceeding relating to
this Agreement or the Notes or any other Financing Document in the case of the
courts of the United States District Court of the Southern District of New York
or of the

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<PAGE>   71

courts of the State of New York sitting in New York, Borough of Manhattan, which
service may be made on any such designee, appointee, and agent in accordance
with legal procedures prescribed for such courts. So long as the Borrower has
any Obligations, the Borrower agrees to take any and all action necessary to
continue such designation in full force and effect and should such designee,
appointee, and agent become unavailable for this purpose for any reason not
attributable to the Borrower, the Borrower shall forthwith grant a similar
special irrevocable power of attorney to a new designee, appointee, and agent
with offices in New York, New York, which shall irrevocably agree to act as
such, with the powers and for purposes specified in this Section 14.5. The
Borrower further irrevocably consents and agrees to service of any and all legal
process, summons, notices, and documents out of any of the aforesaid courts in
any such action, suit or proceeding relating to this Agreement, the Notes, or
any other Financing Document delivered to the Borrower in accordance with this
Section 14.5 or to its then designee, appointee, or agent for service. If
service is made upon such designee, appointee, and agent, a copy of such
process, summons, notice or document shall also be provided to the Borrower, by
registered or certified mail, or overnight express air courier, provided that
failure to provide such copy to the Borrower shall not impair or affect in any
way the validity of such service or any judgment rendered in such action or
proceedings. The Borrower agrees that service upon the Borrower or any such
designee, appointee, and agent as provided for in this Section 14.5 shall
constitute valid and effective personal service upon the Borrower with respect
to matters contemplated in this Section 14.5 and that the failure of any such
designee, appointee, and agent to give any notice of such service to the
Borrower shall not impair or affect in any way the validity of such service or
any judgment rendered in any action or proceeding based thereon. Nothing herein
shall limit or be construed to limit the rights of the Lenders to commence
proceedings against the Borrower in any other venue where assets of the Borrower
may be found.

SECTION 14.6 LEGAL PROCESS IN OTHER JURISDICTIONS.

       Nothing in Section 14.3 or in Section 14.5 shall affect the right of any
Lender or Agent to serve legal process in any other manner permitted by law or
affect the right of any Lender or the Administrative Agent to bring any action
or proceeding against the Borrower or its property in the courts of other
competent jurisdictions, including, without limitation, the courts sitting in
the City of Buenos Aires, Argentina.

                             SECTION 15. THE AGENTS

SECTION 15.1.  AUTHORIZATION AND ACTION.

       The Lenders hereby appoint and authorize the Administrative Agent and the
Collateral Agent to exercise such powers and discretion under this Agreement and
the other Financing Documents, as are delegated to them, respectively, by the
terms hereof and thereof, together with such powers and discretion as are
reasonably incidental thereto. As to any matters not expressly provided for in
the Financing Documents (including, without limitation, enforcement or
collection of the Notes), neither Agent shall be required to exercise any
discretion or take any

                                      -70-
<PAGE>   72

action, but shall be required to act or to refrain from acting (and shall be
fully protected in so acting or refraining from acting) upon the instructions of
the Required Lenders; provided, however, that neither Agent shall be required to
take any action that exposes it to personal liability or that is contrary to
this Agreement or Applicable Law. Each Agent hereunder agrees to give to the
Lenders prompt notice of each notice given to it by the Borrower pursuant to the
terms of this Agreement.

SECTION 15.2 AGENT'S RELIANCE.

       Neither Agent nor any of its directors, officers, agents or employees
shall be liable for any action taken or omitted to be taken by it or them under
or in connection with the Financing Documents, except for its or their own gross
negligence or willful misconduct. Without limitation of the generality of the
foregoing, the Agents: (a) may treat the payee of any Note as the holder thereof
until the Administrative Agent receives and accepts an Assignment and Assumption
Agreement entered into by the payee of such Note, as assignor, and an assignee;
(b) may consult with legal counsel (including counsel for the Borrower),
independent public accountants and other experts selected by it and shall not be
liable for any action taken or omitted to be taken in good faith by it in
accordance with the advice of such counsel, accountants or experts; (c) make no
warranty or representation to the Lenders and shall not be responsible to any
Lender for any statements, warranties or representations (whether written or
oral) made in or in connection with this Agreement; (d) shall not have any duty
to ascertain or to inquire as to the performance or observance of any of the
terms, covenants or conditions of this Agreement on the part of the Borrower or
to inspect the property (including the books and records) of the Borrower; (e)
shall not be responsible to any Lender for the due execution, legality,
validity, enforceability, genuineness, sufficiency or value of, or the
perfection or priority of any Lien created or purported to be created under or
in connection with, this Agreement or any other instrument or document furnished
pursuant thereto; and (f) shall incur no liability under or in respect of this
Agreement by acting upon any notice, consent, certificate or other instrument or
writing (which may be by facsimile, electronic mail or telex) believed by it to
be genuine and signed or sent by the proper party or parties.

SECTION 15.3 LENDER CREDIT DECISION.

       Each Lender acknowledges that it has, independently and without reliance
upon either Agent and based on the financial statements referred to in Section
7.7 of this Agreement and such other documents and information as it has deemed
appropriate, made its own credit analysis and decision to enter into this
Agreement. Each Lender also acknowledges that it will, independently and without
reliance upon any Agent and based on such documents and information as it shall
deem appropriate at the time, continue to make its own credit decisions in
taking or not taking action under this Agreement.

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SECTION 15.4 LENDER INDEMNIFICATION.

       The Lenders agree to indemnify each Agent ratably according to the
respective principal amount of the Notes then held by the Lenders (or if no
Notes are at the time outstanding or if any Notes are held by Persons that are
not the Lenders, ratably according to the respective amounts of the Commitment)
from and against any and all liabilities, obligations, losses, damages,
penalties, actions, judgments, suits, costs, expenses or disbursements of any
kind or nature whatsoever that may be imposed on, incurred by, or asserted
against such Agent in any way relating to or arising out of this Agreement or
any action taken or omitted by such Agent under this Agreement (to the extent
not promptly reimbursed by the Borrower); provided, however, that the Lenders
shall not be liable for any portion of such liabilities, obligations, losses,
damages, penalties, actions, judgments, suits, costs, expenses or disbursements
resulting from such Agent's gross negligence or willful misconduct. Without
limitation of the foregoing, the Lenders agree to reimburse each Agent promptly
upon demand for its ratable share of any costs and expenses (including, without
limitation, fees and expenses of counsel) payable by the Borrower under Sections
11.1 and 11.2, to the extent that such Agent is not promptly reimbursed for such
costs and expenses by the Borrower.

SECTION 15.5 SUCCESSOR AGENTS.

       Either Agent may resign at any time by giving written notice thereof to
the Lenders and the Borrower and may be removed at any time with or without
cause by the Required Lenders. Upon any such resignation or removal, the
Required Lenders shall have the right to appoint a successor Agent. If no
successor Agent shall have been so appointed, and shall have accepted such
appointment, within thirty (30) days after the retiring Agent's giving of notice
of resignation or the Required Lenders' removal of the retiring Agent, then the
retiring Agent may, on behalf of the Lenders, appoint a successor Agent, which
shall be a commercial bank organized under the laws of the United States or of
any State thereof and having a combined capital and surplus of at least one
hundred million Dollars (US$100,000,000). Upon the acceptance of any appointment
as an Agent hereunder by a successor Agent and, in the case of a successor
Collateral Agent, upon the execution and filing or recording of such instruments
or notices, as may be necessary or desirable, or as the Required Lenders may
request, in order to continue the perfection of the security interests granted
or purported to be granted under the Security Documents, such successor Agent
shall succeed to and become vested with all the rights, powers, discretion,
privileges and duties of the retiring Agent, and the retiring Agent shall be
discharged from its duties and obligations under this Agreement. After any
retiring Agent's resignation or removal hereunder as an Agent, the provisions of
this Section 15 shall inure to its benefit as to any actions taken or omitted to
be taken by it while it was an Agent under this Agreement.

                                      -72-
<PAGE>   74

                         SECTION 16. GENERAL PROVISIONS

SECTION 16.1 NOTICES.

       All communications and notices provided for hereunder shall be in writing
and shall be personally delivered, mailed by postage prepaid registered mail
(airmail if international), return receipt requested, or telefaxed (with a
confirmation copy by postage prepaid registered mail, return receipt requested):

      If to the Borrower:      IMPSAT S.A.
                               Alferez Pareja 256
                               (1107) Buenos Aires, Argentina
                               Attention:  President
                               Fax No.:    54 11 4307 1525

      If to IMPSAT:            IMPSAT Corporation
                               c/o IMPSAT USA, Inc.
                               2040 North Dixie Highway
                               Wilton Manors, Florida  33305
                               Attention:  President
                               Fax No.:    (954) 779-3766

      If to the Lenders:       Nortel  Networks Corporation
                               c/o Nortel (CALA) Inc.
                               1500 Concord Terrace
                               Sunrise, FL 33323-2815
                               Attention:  Vice President and General Counsel
                               Fax No.     (954) 851-8900

                               With a copy to:        Baker & McKenzie
                               805 Third Avenue
                               New York, NY 10022
                               Attention:  Thomas W. Studwell, Esq.
                               Fax No.:    (212) 891-3521

                                      -73-
<PAGE>   75

       If to the Administrative Agent:Nortel  Networks Corporation
                               c/o Nortel (CALA) Inc.
                               1500 Concord Terrace
                               Sunrise, FL 33323-2815
                               Attention:  Vice President and General Counsel
                               Fax No.     (954) 851-8900

       If to the Collateral Agent: Nortel  Networks Corporation
                               c/o Nortel (CALA) Inc.
                               1500 Concord Terrace
                               Sunrise, FL 33323-2815
                               Attention:  Vice President and General Counsel
                               Fax No.     (954) 851-8900

Except as otherwise specified herein, all notices shall be deemed duly given on
the date of actual receipt.

SECTION 16.2 SEVERABILITY OF PROVISIONS.

       If any one or more of the provisions contained in this Agreement or any
documents executed in connection herewith shall be invalid, illegal, or
unenforceable in any respect, the validity, legality, and enforceability of the
remaining provisions contained herein shall not in any way be affected or
impaired.

SECTION 16.3 BINDING EFFECT; SUCCESSORS AND ASSIGNS.

       This Agreement shall be binding upon and shall inure to the benefit of
each Party and its respective successors and assigns, provided that the Borrower
shall not assign or transfer any of its rights or Obligations hereunder except
with the prior written consent of the Administrative Agent and each Lender.

SECTION 16.4 AMENDMENT; WAIVER.

       (a)    GENERAL. Neither this Agreement nor any Financing Document may be
amended, waived, discharged, or terminated unless such change, waiver,
discharge, or termination is in writing signed by the Required Lenders, the
Administrative Agent or the Collateral Agent, as applicable, and the Borrower,
provided, however, that no such change, waiver, discharge or termination shall,
without the consent of each Lender affected thereby, (a) extend the final
maturity of any Loan or Note, or reduce the rate or extend the time of payment
of interest or fees thereon, or reduce the principal amount hereof, or increase
the Commitment of any Lender over the amount thereof then in effect (it being
understood that a waiver of any Default or Event of Default other than a payment
default shall not constitute a change in the terms of any Commitment of any
Lender), (b) release any of the Collateral except as shall otherwise be provided
in any of the Financing Documents, (c) amend, modify or waive any provision of
this

                                      -74-
<PAGE>   76

Section 16.4 or Sections 3, 4, 5, 11, 12, 15.4 and 16.6, (d) reduce the
percentages specified in the definition of Required Lenders, or (e) consent to
the assignment of any of the rights and Obligations of the Borrower under this
Agreement or any Collateral Agreements. The failure of any party to enforce at
any time any provision hereof or under any of the Notes or Security Documents
shall not be construed to be a waiver of such provisions or of the right of such
party thereafter to enforce any such provision or any other provision hereof or
thereof.

       (b)    DIRECTED CHANGES. In the event that, under the Turnkey Contract,
the Aggregate Price is increased as a result of Directed Changes (as those terms
are defined in the Turnkey Contract), the Parties shall negotiate in good faith
an amendment to this Agreement to increase the Commitment Amount accordingly.

SECTION 16.5 ENTIRE AGREEMENT.

       This Agreement and the other Financing Documents constitute the entire
agreement and understanding of the Parties with respect to the subject matter
hereof, and supersede all prior agreements, discussions, and understandings
between the Lenders and the Borrower with respect to the subject matter hereof.

SECTION 16.6 RIGHT OF SET-OFF.

       The Borrower's Obligations shall be paid in full in accordance with their
respective terms, and may not be offset against any obligations that Nortel, any
Lender, or any of their respective Affiliates may owe to the Borrower under any
other agreement, including (without limitation) any of the Nortel Contracts.
Each of the Lenders shall, to the fullest extent permitted by Applicable Law,
have the right to apply any and all amounts on deposit or on account (general or
special, time or demand, matured or unmatured, in whatever currency) with it or
with any of its branches, Subsidiaries, or Affiliates in reduction of past due
Obligations (whether such Obligations became due at scheduled maturity, by
acceleration or otherwise) of the Borrower hereunder.

SECTION 16.7 FURTHER ASSURANCES.

       The Borrower agrees upon the reasonable request of any Agent or Lender
promptly to take such actions as are necessary to carry out the intent of this
Agreement and the other Financing Documents.

SECTION 16.8 TERM OF AGREEMENT; SURVIVAL.

       Each agreement, representation, warranty, and covenant contained in this
Agreement shall survive any investigation made at any time by or on behalf of
the Lenders, and shall survive the Commitment Termination Date. This Agreement
shall continue to be in full force and effect and binding upon the Parties until
all of the Borrower's Obligations have been fully and indefeasibly paid and
performed, whereupon this Agreement shall terminate. Notwithstanding

                                      -75-
<PAGE>   77

the foregoing, all the indemnification provisions in this Agreement shall
survive and all other provisions which by their terms survive termination shall
so survive.

SECTION 16.9 HEADINGS.

       The various headings in this Agreement are intended for convenience only,
and shall not affect the meaning or interpretation of this Agreement.

SECTION 16.10 COUNTERPARTS.

       This Agreement may be executed in any number of counterparts (including
facsimile transmissions thereof), each of which when so executed shall be an
original but all of which together shall constitute one instrument.

SECTION 16.11 CONFIDENTIALITY.

       Each of the Parties hereby agrees to maintain the confidentiality of the
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 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 the Borrower or IMPSAT 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 16.11, 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 other Parties, or (h) to the extent such
Information (1) becomes publicly available other than as a result of a breach of
this Section 16.11 or (2) becomes available to such party on a non-confidential
basis from a source other than the other Parties.

       For the purposes of this Section 16.11, "INFORMATION" means all
information received from any of the Parties relating to any of the Lenders, the
Fiber Optic Supplier or their respective businesses, 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 16.11 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.

                                      -76-
<PAGE>   78

SECTION 16.12 COOPERATION.

       The Borrower will cooperate (i) with Nortel, the Administrative Agent, if
applicable, and the lead agents for syndication (such lead agents and the
Administrative Agent being referred to collectively as the "SYNDICATION AGENTS")
in the syndication of the Loans and Commitments undertaken by the Syndication
Agents, and (ii) with Nortel and any underwriter or placement agent for the
placement or distribution of the Replacement Notes ("PLACEMENT AGENT") by: (a)
upon reasonable notice making senior officers of the Borrower available for a
meeting with prospective assignees and the Syndication Agents, the Placement
Agent and their respective consultants; and (b) providing such other assistance
as may be reasonably requested by the Syndication Agents and the Placement
Agent, such as responding to questions from prospective assignees with respect
to the operations, business plans, results and other matters relating to the
Borrower, its Affiliates and IMPSAT.

IN WITNESS WHEREOF, the Parties have caused this Agreement to be duly executed
as of the date first written above.

BORROWER:

IMPSAT S.A.

By:
            ---------------------------

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

Its:
            ---------------------------

LENDERS:

NORTEL NETWORKS CORPORATION

By:
            ---------------------------

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

Its:
            ---------------------------

                                      -77-
<PAGE>   79

ADMINISTRATIVE AGENT:

NORTEL NETWORKS CORPORATION

By:
            ---------------------------

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

Its:
            ---------------------------

COLLATERAL AGENT:

NORTEL NETWORKS CORPORATION

By:
            ---------------------------

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

Its:
            ---------------------------

                                      -78-
<PAGE>   80

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                            PAGE
                                                                                                                            ----

<S>                                                                                                                           <C>
SECTION 1. DEFINITIONS..........................................................................................................2

      SECTION 1.1       DEFINED TERMS...........................................................................................2
      SECTION 1.2       OTHER DEFINITIONS......................................................................................18
      SECTION 1.3       INTERPRETATION.........................................................................................20
      SECTION 1.4       ACCOUNTING PRINCIPLES AND TERMS........................................................................20

SECTION 2.  THE CREDIT FACILITY................................................................................................20

      SECTION 2.1       LOANS. ................................................................................................20
      SECTION 2.2       USE OF PROCEEDS........................................................................................20
      SECTION 2.3       PROCEDURE FOR BORROWING; DISBURSEMENTS.................................................................21
      SECTION 2.4       NOTES. ................................................................................................22
      SECTION 2.5       VOLUNTARY TERMINATION OR REDUCTION OF THE COMMITMENT...................................................23

SECTION 3.  PAYMENT OF PRINCIPAL, INTEREST AND FEES............................................................................24

      SECTION 3.1       REPAYMENT OF PRINCIPAL.................................................................................24
      SECTION 3.2       PREPAYMENTS............................................................................................24
      SECTION 3.3       INTEREST...............................................................................................26
      SECTION 3.4       FEES. .................................................................................................27
      SECTION 3.5       NATURE OF PAYMENTS.....................................................................................28
      SECTION 3.6       PAYMENT PROCEDURES.....................................................................................28
      SECTION 3.7       ADMINISTRATIVE AGENT'S DETERMINATION...................................................................28
      SECTION 3.8       PAYMENTS PRO RATA......................................................................................28

SECTION 4.  PAYMENT IN DOLLARS; EVENT OF SOVEREIGN RISK........................................................................29

      SECTION 4.1       OBLIGATION TO PAY IN DOLLARS; JUDGMENT CURRENCY........................................................29
      SECTION 4.2       EVENT OF SOVEREIGN RISK................................................................................30

SECTION 5.  FUNDING AND YIELD PROTECTION.......................................................................................31

      SECTION 5.1       TAXES. ................................................................................................31
      SECTION 5.2       FUNDING BREAKAGE COSTS.................................................................................33
      SECTION 5.3       ILLEGALITY.............................................................................................33
      SECTION 5.4       INCREASED COSTS AND YIELD PROTECTION...................................................................34

SECTION 6.  DELIVERIES; CONDITIONS PRECEDENT...................................................................................35

      SECTION 6.1       CONCURRENT DELIVERIES..................................................................................35
      SECTION 6.2       CONDITIONS PRECEDENT TO INITIAL DISBURSEMENT; CLOSING..................................................35
      SECTION 6.3       CONDITIONS PRECEDENT TO ALL DISBURSEMENTS..............................................................37
      SECTION 6.4       ENGLISH TRANSLATIONS...................................................................................38
      SECTION 6.5       TERMINATION BY THE LENDERS.............................................................................39
</TABLE>

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                                TABLE OF CONTENTS

                                    (CONT'D)

<TABLE>
<CAPTION>
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<S>                                                                                                                         <C>
SECTION 7.  REPRESENTATIONS AND WARRANTIES.....................................................................................39

      SECTION 7.1       CORPORATE STATUS.......................................................................................39
      SECTION 7.2       CORPORATE POWER........................................................................................39
      SECTION 7.3       GOVERNMENTAL APPROVALS.................................................................................40
      SECTION 7.4       NO VIOLATION...........................................................................................40
      SECTION 7.5       PROCEEDINGS............................................................................................41
      SECTION 7.6       TAXES .................................................................................................41
      SECTION 7.7       FINANCIAL STATEMENTS...................................................................................41
      SECTION 7.8       THE PROJECT............................................................................................42
      SECTION 7.9       ENVIRONMENTAL MATTERS..................................................................................42
      SECTION 7.10      TRANSACTIONS WITH AFFILIATES...........................................................................43
      SECTION 7.11      INDEBTEDNESS...........................................................................................43
      SECTION 7.12      PROPERTIES.............................................................................................43
      SECTION 7.13      INTELLECTUAL PROPERTY..................................................................................44
      SECTION 7.14      BOOKS AND RECORDS......................................................................................44
      SECTION 7.15      THE LICENSES...........................................................................................44
      SECTION 7.16      NO MATERIAL ADVERSE CHANGE.............................................................................44
      SECTION 7.17      INSURANCE..............................................................................................44
      SECTION 7.18      COLLATERAL.............................................................................................45
      SECTION 7.19      INVESTMENT COMPANY ACT.................................................................................45
      SECTION 7.20      IMMUNITY...............................................................................................45
      SECTION 7.21      TRUE AND COMPLETE DISCLOSURE...........................................................................45

SECTION 8.  COVENANTS..........................................................................................................46

      SECTION 8.1       AFFIRMATIVE COVENANTS..................................................................................46
      SECTION 8.2       NEGATIVE COVENANTS.....................................................................................53
      SECTION 8.3       FINANCIAL COVENANTS....................................................................................55
      SECTION 8.4       OPERATIONAL COVENANT...................................................................................58

SECTION 9.  SECURITY...........................................................................................................59

      SECTION 9.1       GRANT OF SECURITY INTEREST.............................................................................59
      SECTION 9.2       ESCROW ACCOUNTS........................................................................................59
      SECTION 9.3       RELEASE OF COLLATERAL..................................................................................59

SECTION 10.  EVENTS OF DEFAULT.................................................................................................60

      SECTION 10.1      EVENTS OF DEFAULT......................................................................................60
      SECTION 10.2      REMEDIES UPON EVENT OF DEFAULT.........................................................................64
      SECTION 10.3      CUMULATIVE RIGHTS......................................................................................65
</TABLE>

                                      -ii-
<PAGE>   82
                                TABLE OF CONTENTS

                                    (CONT'D)

<TABLE>
<CAPTION>
                                                                                                                            PAGE
                                                                                                                            ----

<S>                                                                                                                         <C>
SECTION 11.  EXPENSES AND INDEMNIFICATION......................................................................................66

      SECTION 11.1      EXPENSES...............................................................................................66
      SECTION 11.2      INDEMNIFICATION........................................................................................66

SECTION 12.  ASSIGNMENT AND PARTICIPATION......................................................................................67

      SECTION 12.1      ASSIGNMENT.............................................................................................67
      SECTION 12.2      PARTICIPATION..........................................................................................68

SECTION 13.  OPTION TO REVISE STRUCTURE........................................................................................68

      SECTION 13.1      OPTION TO REVISE.......................................................................................68
      SECTION 13.2      COSTS BORNE BY LENDERS.................................................................................69
      SECTION 13.3      TERMS OF REPLACEMENT NOTES.............................................................................69
      SECTION 13.4      APPLICATION OF PROCEEDS................................................................................69
      SECTION 13.5      RELEASE OF OBLIGATIONS.................................................................................70
      SECTION 13.6      TERMINATION OF OPTION..................................................................................70

SECTION 14.  GOVERNING LAW AND JURISDICTION....................................................................................70

      SECTION 14.1      GOVERNING LAW..........................................................................................70
      SECTION 14.2      WAIVER OF JURY TRIAL...................................................................................70
      SECTION 14.3      JURISDICTION; VENUE FOR SUIT...........................................................................70
      SECTION 14.4      WAIVER OF IMMUNITY.....................................................................................71
      SECTION 14.5      PROCESS AGENT..........................................................................................71
      SECTION 14.6      LEGAL PROCESS IN OTHER JURISDICTIONS...................................................................72

SECTION 15.  THE AGENTS........................................................................................................72

      SECTION 15.1      AUTHORIZATION AND ACTION...............................................................................72
      SECTION 15.2      AGENT'S RELIANCE.......................................................................................73
      SECTION 15.3      LENDER CREDIT DECISION.................................................................................73
      SECTION 15.4      LENDER INDEMNIFICATION.................................................................................73
      SECTION 15.5      SUCCESSOR AGENTS.......................................................................................74

SECTION 16.  GENERAL PROVISIONS................................................................................................74

      SECTION 16.1      NOTICES................................................................................................74
      SECTION 16.2      SEVERABILITY OF PROVISIONS.............................................................................76
      SECTION 16.3      BINDING EFFECT; SUCCESSORS AND ASSIGNS.................................................................76
      SECTION 16.4      AMENDMENT; WAIVER......................................................................................76
      SECTION 16.5      ENTIRE AGREEMENT.......................................................................................77
      SECTION 16.6      RIGHT OF SET-OFF.......................................................................................77
</TABLE>

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<PAGE>   83
                                TABLE OF CONTENTS

                                    (CONT'D)

<TABLE>
<CAPTION>
                                                                                                                            PAGE
                                                                                                                            ----

<S>                                                                                                                         <C>
      SECTION 16.7      FURTHER ASSURANCES.....................................................................................77

      SECTION 16.8      TERM OF AGREEMENT; SURVIVAL............................................................................77
      SECTION 16.9      HEADINGS...............................................................................................78
      SECTION 16.10     COUNTERPARTS...........................................................................................78
      SECTION 16.11     CONFIDENTIALITY........................................................................................78
      SECTION 16.12     COOPERATION............................................................................................79
</TABLE>

                                     -iv-
<PAGE>   84

                                TABLE OF CONTENTS

                                    (CONT'D)

SCHEDULES

7.1                          SUBSIDIARIES
7.5                          PROCEEDINGS
7.10                         TRANSACTIONS WITH AFFILIATES
7.11                         INDEBTEDNESS
7.12                         EXISTING LIENS
7.13                         INTELLECTUAL PROPERTY
7.15                         LICENSES
7.16                         MATERIAL ADVERSE CHANGE

EXHIBITS

A                            FORM OF ASSIGNMENT AND ASSUMPTION AGREEMENT
B                            FORM OF DISBURSEMENT REQUEST
C                            FORM OF EQUIPMENT PLEDGE AGREEMENT
D                            FORM OF ESCROW ACCOUNT AGREEMENT
E                            FORM OF INTERCREDITOR AGREEMENT
F                            FORM OF MORTGAGE DEED
G                            FORM OF NOTE
H                            LIST OF PROJECT AGREEMENTS
I                            FORM OF NOTICE OF CONSOLIDATION
J                            SUBJECT MATTER OF OPINION OF U.S. COUNSEL
K                            SUBJECT MATTER OF OPINION OF ARGENTINE COUNSEL

                                      -v-

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