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                                                                    EXHIBIT 10.9



                               IRU FIBER AGREEMENT
                                   (ARGENTINA)


                                     BETWEEN


                                   IMPSAT S.A.


                                       AND


                         360NETWORKS DE ARGENTINA S.R.L.


                                FEBRUARY __, 2001



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                                TABLE OF CONTENTS


<TABLE>
<S>                                                                                         <C>
ARTICLE 1 DEFINITIONS........................................................................1

        1.01   Defined Terms.................................................................1
        1.02   Construction..................................................................5

ARTICLE 2 PROVISION OF THE SYSTEM............................................................5

        2.01   Transfer of Rights............................................................5
        2.02   No Ownership Interest.........................................................5
        2.03   Description of Segments.......................................................6
        2.04   Power and Authority...........................................................6
        2.05   Long-Haul Connectivity-Chile.......................ERROR! BOOKMARK NOT DEFINED.

ARTICLE 3 CONSIDERATION......................................................................6

        3.01   Amount of Total Fee...........................................................6
        3.02   Payment of Total Fee..........................................................6
        3.03   Route Kilometer Adjustment....................................................6
        3.04   Method of Payment.............................................................7
        3.05   Late Payment..................................................................7
        3.06   Disputed Amounts..............................................................7
        3.07   No Set-Off....................................................................8
        3.08   Indirect Taxes................................................................8
        3.09   Income Taxes..................................................................8

ARTICLE 4 CONSTRUCTION OF THE IMPSAT ARGENTINA SYSTEM........................................8

        4.01   Construction Standards........................................................8
        4.02   Shelters......................................................................8
        4.03   Completion of Construction....................................................9
        4.04   Liquidated Damages............................................................9
        4.05   Inspection; Access to Information............................................10
        4.06   Documentation................................................................10
        4.07   Construction Progress Reports................................................10
        4.08   Routing of IRU Fibers........................................................11
        4.09   Fiber Orders.................................................................11
        4.10   Impsat System................................................................11

ARTICLE 5 ACCEPTANCE AND TESTING............................................................11
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<TABLE>
<S>                                                                                        <C>
        5.01   Overview.....................................................................11
        5.02   Acceptance Testing by Impsat.................................................11
        5.03   Acceptance Testing by 360americas............................................11
        5.04   Failure Notice...............................................................12
        5.05   Correction...................................................................12
        5.06   Testing by Third Party.......................................................13
        5.07   Acceptance Testing and Acceptance Date.......................................13
        5.08   Spans........................................................................13
        5.09   Coordination With Other Agreements...........................................14

ARTICLE 6 TERM .............................................................................14

        6.01   Length of Term...............................................................14
        6.02   Ownership of IRU Fibers and Associated Properties............................14
        6.03   Extension of Term............................................................14

ARTICLE 7 NETWORK ACCESS....................................................................14

        7.01   Grant of Access..............................................................14
        7.02   Reimbursement; Scheduling....................................................14

ARTICLE 8 OPERATIONS........................................................................15

        8.01   Network Configuration........................................................15
        8.02   Acknowledgments by 360americas...............................................15
        8.03   Electronic and Photo-Optical Equipment.......................................15
        8.04   Additional Equipment.........................................................15

ARTICLE 9 MAINTENANCE AND REPAIR............................................................16

        9.01   Maintenance Services.........................................................16
        9.02   Recurring Service Charge.....................................................16
        9.03   Planned System Work Period...................................................16
        9.04   Service Affecting Condition..................................................16
        9.05   Event of a Fault.............................................................16
        9.06   No Physical Access...........................................................16
        9.07   Optronic Equipment...........................................................16
        9.08   Subcontracting...............................................................16

ARTICLE 10 PERMITS; UNDERLYING RIGHTS; RELOCATIONS..........................................17

        10.01  Required Authorizations......................................................17
        10.02  Relocation of Segment........................................................17
        10.03  As-Builts Upon Relocation....................................................18

ARTICLE 11 USE OF THE SEGMENTS..............................................................18
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<TABLE>
<S>                                                                                        <C>
        11.01  Underlying Rights Requirements...............................................18
        11.02  Compliance of 360americas....................................................18
        11.03  Limitations on Use...........................................................18
        11.04  Impsat Argentina System......................................................18
        11.05  Cooperation..................................................................19

ARTICLE 12 INDEMNIFICATION..................................................................19

        12.01  Indemnification by 360americas...............................................19
        12.02  Indemnification by Impsat....................................................19
        12.03  Notice.......................................................................19
        12.04  Use Agreements...............................................................20

ARTICLE 13 LIABILITY........................................................................20

        13.01  Limitation on Types of Damages...............................................20
        13.02  Disclaimer of Warranty.......................................................20
        13.03  Limitation on Amount of Damages..............................................21
        13.04  Limitation on Time for Claim.................................................21
        13.05  Survival.....................................................................21

ARTICLE 14 INSURANCE........................................................................21

        14.01  Required Insurance Policies..................................................21
        14.02  No Limitation of Liability...................................................21
        14.03  Additional Insured...........................................................22
        14.04  Failure to Obtain Insurance..................................................22
        14.05  Denial of Claim..............................................................22
        14.06  Waiver of Subrogation........................................................22

ARTICLE 15 TAXES, FEES AND OTHER GOVERNMENTAL IMPOSITIONS...................................22

        15.01  Minimization of Impositions..................................................22
        15.02  Indirect Taxes and Income Taxes..............................................22
        15.03  Right to Contest.............................................................23
        15.04  Future Cooperation...........................................................23

ARTICLE 16 CONFIDENTIALITY..................................................................24

        16.01  Proprietary Information......................................................24
        16.02  Permitted Disclosure.........................................................24
        16.03  No Intellectual Property Transfer............................................25
        16.04  Internal Disclosures.........................................................25
        16.05  Public Announcements.........................................................25
        16.06  Survival.....................................................................25

ARTICLE 17 DEFAULT..........................................................................25
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<TABLE>
<S>                                                                                        <C>
        17.01  Events of Default by 360americas.............................................25
        17.02  Remedies of Impsat Upon 360americas Event of Default.........................26
        17.03  Events of Default by Impsat..................................................26
        17.04  Remedies of 360americas Upon Impsat Event of Default.........................26

ARTICLE 18 TERMINATION......................................................................27


ARTICLE 19 FORCE MAJEURE....................................................................27


ARTICLE 20 ASSIGNMENT.......................................................................28

        20.01  Assignment by Impsat.........................................................28
        20.02  Grant of Security Interest by Impsat.........................................28
        20.03  Assignment by 360americas....................................................29
        20.04  Binding Effect...............................................................30
        20.05  No Third Party Beneficiary...................................................30

ARTICLE 21 REPRESENTATIONS, WARRANTIES AND ACKNOWLEDGMENTS..................................30

        21.01  Representations and Warranties of 360americas................................30
        21.02  Representations and Warranties of Impsat.....................................31
        21.03  Survival.....................................................................31

ARTICLE 22 NOTICES..........................................................................31


ARTICLE 23 GENERAL..........................................................................33

        23.01  Waiver.......................................................................33
        23.02  Governing Law................................................................33
        23.03  Dispute Resolution...........................................................33
        23.04  Jurisdiction.................................................................33
        23.05  Expenses.....................................................................33
        23.06  Rules of Construction........................................................33
        23.07  Entire Agreement.............................................................34
        23.08  Relationship of the Parties..................................................34
        23.09  Severability.................................................................34
        23.10  Further Assurances...........................................................34
        23.11  Counterparts.................................................................34
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                         IRU FIBER AGREEMENT (ARGENTINA)


                This IRU FIBER AGREEMENT (ARGENTINA) (this "Agreement"), made
and entered into as of February ___, 2001 (the "Effective Date") in the City of
Buenos Aires, Argentina, is by and between Impsat S.A., an Argentina corporation
("Impsat"), and 360networks de Argentina S.R.L., an Argentina limited liability
company ("360americas").

                                    RECITALS


                WHEREAS, Impsat and its Affiliates have constructed a
terrestrial fiber optic telecommunications network in South America and are in
the process of expanding such network; and

                WHEREAS, 360americas desires to acquire from Impsat, and Impsat
desires to provide to 360americas, an Indefeasible Right of Use (as defined in
this Agreement) to twelve (12) specifically identifiable Non-Zero Dispersion
dark fibers (the "IRU Fibers"), the Shelters and certain Associated Property
with respect thereto, on the Impsat System from Paso de Los Libres, Argentina to
Las Toninas, Argentina through the following major cities: Buenos Aires, Parana,
and Rosario, all as more specifically set forth on Exhibit A (such route, the
"Argentina Route");

                NOW, THEREFORE, in consideration of the mutual covenants
contained in this Agreement, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto do
hereby agree as follows:

                                    ARTICLE 1
                                   DEFINITIONS

        1.01    Defined Terms. Unless otherwise defined in this Agreement, when
used in this Agreement, the following terms shall have the following meanings:

                "Acceptance Date" has the meaning set forth in Section 5.07.

                "Acceptance Testing" has the meaning set forth in Section 5.01.

                "Affiliate" means, with respect to any entity, any other entity
controlled by or under common control with such entity; provided, however, that
this definition shall not include any entity under common control with Impsat
Fiber Networks, Inc., a Delaware corporation ("IFN"), but shall include any
entities controlled by IFN. For purposes of this definition, "control"
(including the terms "controlling," "controlled by" and "under common control
with") means the possession, direct or indirect, of the power (i) to vote 50.1%
or more of the securities (on a fully diluted basis) having ordinary voting
power for the election of directors, managing general partners or managing
members or (ii) to direct or cause the direction of the management and policies
of a party, whether by contract or otherwise.


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                "Agreement" has the meaning set forth in the preamble.

                "Argentina Route" has the meaning set forth in the Recitals.

                "As-Builts" has the meaning set forth in Section 4.06(A).

                "Associated Properties" means the tangible and intangible
property needed for the use of the IRU Fibers and the Shelters to provide
communications services, including but not limited to Impsat's rights in all
Underlying Rights and the right for the IRU Fibers to occupy the conduit housing
the IRU Fibers, but specifically excludes any electronic or opto-electronic
equipment.

                "BA-Valparaiso Route" means the route set forth on Exhibit L.

                "Business Day" means a day other than a Saturday, Sunday or
other day on which commercial banks in New York, New York or Buenos Aires,
Argentina are authorized or required to close.

                "Cable" when used in this Agreement as a capitalized term means
the fiber optic cable, the individual fibers contained therein, and the
associated splicing connections, splice boxes, and vaults installed or to be
installed by Impsat as part of the Impsat Argentina System. When not a
capitalized term, cable means only the fiber optic cable together with the
individual fibers contained therein.

                "Connecting Point" has the meaning set forth in Section 7.01.

                "Construction Specifications" has the meaning set forth in
Section 4.01.

                "Costs" shall mean the actual direct costs paid or payable in
accordance with the established accounting procedures generally used by Impsat
and which Impsat utilizes in billing third parties for reimbursable projects,
including the following: (1) internal labor costs, including wages, salaries,
benefits and overhead (provided that overhead shall equal fifteen percent (15%)
of wages, salaries and benefits), and (2) other direct costs and out of pocket
expenses on a direct pass-through basis.

                "Dark Fiber" means optical fiber provided without electronics or
optronics, and which is not "lit" or activated.

                "Dispute Account" has the meaning set forth in Section 3.06(A).

                "Dollars" or "US$" means United States dollars.

                "Effective Date" has the meaning set forth in the preamble.

                "Estimated Delivery Date" means, with respect to each Segment,
the date set forth in Exhibit B with respect to such Segment, as any such date
may be extended for and during (1) the period of any delay described in Article
19 and/or (2) a period equal to the duration of any 360americas Event of
Default.


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                "Estimated Long-Haul Kilometers" has the meaning set forth in
Section 3.01(A).

                "Fiber Fee" has the meaning set forth in Section 3.01(A).

                "Fiber Specifications" has the meaning set forth in Section
4.01.

                "Impositions" means any and all taxes, fees, levies, imposts,
duties or charges of any nature together with any penalties, fines or interest
thereon arising out of the ownership of or imposed upon the Impsat Argentina
System by any national, state, provincial or other local governmental or public
taxing authority, but shall not include Indirect Taxes or Income Taxes.

                "Impsat" has the meaning set forth in the preamble.

                "Impsat Argentina System" means the fiber optic
telecommunications system along the Argentina Route, and, if applicable, the
BA-Valparaiso Route, constructed or to be constructed or acquired by Impsat and
comprised of fiber optic cables, cable stations, node sites, Telehouses,
amplification/regeneration facilities and similar sites and facilities and other
rights associated with the property and equipment utilized therein.

                "Impsat Event of Default" has the meaning set forth in Section
17.03.

                "Income Taxes" means taxes imposed by any national, state,
provincial or other governmental authority on the income of a party to a
transaction contemplated by this Agreement, whether determined by reference to
net income, gross income or otherwise, and shall include taxes imposed in lieu
thereof. Such term shall not include Impositions or Indirect Taxes.

                "Indefeasible Right of Use" or "IRU" means (1) with respect to
the IRU Fibers and the Shelters, the exclusive, indefeasible right in rem to use
and possess, for the Term, the IRU Fibers and the Shelters for the purposes
described in this Agreement, [  ]* and (2) with respect to the Associated
Properties, an associated non-exclusive, indefeasible right in rem to use, for
the Term, the Associated Properties for the purposes described in this
Agreement, [  ]*.

                "Indirect Taxes" means transactional taxes imposed on any
transaction contemplated by this Agreement and shall include, without limitation
any sales, use, excise, Value Added Taxes ("VAT"), Goods and Services Tax
("GST"), gross receipts tax or similar type tax imposed by any national, state,
provincial or other governmental or quasi-governmental authority but, unless
stated specifically otherwise, shall not include any Income Taxes, Impositions
or Ingresso Brutos.

                "Interest Rate" means [  ]* percent ([  ]*%) per annum, or if
lower, the highest rate allowed by applicable law.

                "IRU Fibers" has the meaning set forth in the Recitals, but
specifically excludes any and all other portions of the Impsat Argentina System
including, without limitation, any other fibers, the other portions of the Cable
containing the IRU Fibers, the conduit in which the IRU Fibers are contained,
the Shelters, the cable stations, the node sites, Telehouses, the


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amplification/regeneration facilities, similar sites and facilities or any other
equipment or any other rights whatsoever associated with the Impsat Argentina
System.

                "Liquidated Damages" has the meaning set forth in Section 4.04.

                "Maintenance Services" has the meaning set forth in Section
9.01.

                "Network Completion Date" has the meaning set forth in Section
4.04.

                "Network Segments" has the meaning set forth in Section 4.04.

                "Non-Disturbance Agreement" has the meaning set forth in Section
20.02(A).

                "Payment Escrow Agreement" has the meaning set forth in Section
3.06(A).

                "Planned System Work Period" means a prearranged period of time
reserved for performing certain work on any part of the Impsat Argentina System.

                "Proprietary Information" has the meaning set forth in Section
16.01.

                "Pro Rata Share" means the relative number of the IRU Fibers in
the affected portion of the Impsat Argentina System compared to the total number
of fibers in the affected portion of the Impsat Argentina System.

                "Recurring Service Charge" has the meaning set forth in Section
9.02.

                "Required Relocation" has the meaning set forth in Section
10.02.

                "Segment" means the connections identified as separate segments
as set forth on Exhibit B.

                "Service Affecting Condition" has the meaning set forth in
Section 9.04.

                "Shelters" has the meaning set forth in Section 4.02(A).

                "Shelter Fee" has the meaning set forth in Section 3.01(B).

                "Spans" has the meaning set forth in Section 5.08.

                "360americas" has the meaning set forth in the preamble.

                "360americas Event of Default" has the meaning set forth in
Section 17.01.

                "Telecommunication Authorizations" has the meaning set forth in
Section 10.01.

                "Telecommunications Services Agreement" means the Amended and
Restated Telecommunications Services Agreement dated as of August 30, 2000
between Impsat Fiber Networks, Inc. and Atlantica Network (Bermuda) Ltd.


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                "Telehouse Services Agreement" means the telehouse services
agreements to be entered into between Impsat and 360americas (or the respective
Affiliates thereof) pursuant to which Impsat or its Affiliates will provide
certain services in connection with its telehouses (each, a "Telehouse") located
in each of the following cities: Buenos Aires, Sao Paulo, Rio de Janeiro and
Caracas.

                "Testing Notice" has the meaning set forth in Section 5.02.

                "Term" has the meaning set forth in Section 6.01.

                "Total Fee" has the meaning set forth in Section 3.01(B).

                "Underlying Rights" has the meaning set forth in Section 10.01.

                "Underlying Rights Requirements" has the meaning set forth in
Section 11.01.

                "Use Agreements" has the meaning set forth in Section 12.04.

        1.02    Construction. Unless otherwise defined in this Agreement, all
terms used in this Agreement which are commonly used in the terrestrial
telecommunications industry shall have the meanings commonly given such terms in
the industry.

                                    ARTICLE 2
                             PROVISION OF THE SYSTEM

        2.01    Transfer of Rights. Impsat hereby grants to 360americas and
360americas hereby acquires from Impsat, effective on the Acceptance Date for
each particular Segment delivered by Impsat to 360americas hereunder on the
terms and subject to the covenants and conditions set forth in this Agreement:

                A.      an Indefeasible Right of Use for the Term and for the
                        purposes described in this Agreement, in the IRU Fibers
                        and the Shelters along such Segment of the Argentina
                        Route; and

                B.      an Indefeasible Right of Use for the Term and for the
                        purposes described in this Agreement, in the Associated
                        Properties along such Segment of the Argentina Route.

On each Acceptance Date with respect to a Segment, each party shall execute such
documentation as the other reasonably may require to evidence such grant and
acceptance, including any necessary consents of any third party. [  ]*

        2.02    No Ownership Interest. The IRUs to be granted hereunder do not
and shall not provide 360americas with any ownership interest in or other rights
to physical access to, control of, modification of, encumbrance in any manner
of, or other use of the Impsat Argentina System or the Underlying Rights except
as expressly set forth in this Agreement.


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        2.03    Description of Segments. The Segments included in this Agreement
and the Estimated Delivery Date for each Segment are set forth in Exhibit B.

        2.04    Power and Authority. Each party represents and warrants that it
has the power and authority to perform its obligations under this Agreement.

                [  ]*

                                    ARTICLE 3
                                  CONSIDERATION

        3.01    Amount of Total Fee. Subject to Section 3.03 below, the Total
Fee shall be an amount equal to the sum of, and shall be allocated among the
following:

                A.      The total price for the IRU of the IRU Fibers (the
                        "Fiber Fee") is set forth in Exhibit C. This price is
                        based on the number of kilometers on the Argentina Route
                        (which number is estimated to be [  ]* (the "Estimated
                        Long-Haul Kilometers")) multiplied by the number of IRU
                        Fibers being purchased multiplied by the applicable IRU
                        price per strand as set forth in Exhibit C; and

                B.      The total price for use of the twenty (20) Shelters is
                        set forth in Exhibit C (the "Shelter Fee" and together
                        with the Fiber Fee, the "Total Fee"). Any additional
                        regeneration and/or optical amplification facilities
                        will be priced as set forth in Exhibit C.

        3.02    Payment of Total Fee. In consideration for the grant of the IRUs
hereunder by Impsat to 360americas, 360americas shall pay to Impsat a fee in the
amount determined pursuant to Section 3.01 above payable in accordance with the
following payment schedule:

                A.      [  ]* percent ([  ]*%) of the Total Fee, less the
                        US$[  ]* deposit already paid by 360americas pursuant to
                        Section 1.3 of the Telecommunications Services
                        Agreement, within five (5) Business Days after the
                        Effective Date; and

                B.      [  ]* percent ([  ]*%) of the Fiber Fee allocable to
                        each Segment, as set forth on Exhibit C, within five (5)
                        Business Days of the Acceptance Date for such Segment.

                C.      [  ]* percent ([  ]*%) of the Shelter Fee shall be
                        payable based on Impsat's inspection, acceptance and
                        payment for materials for the Shelters, and the
                        remaining [  ]* percent ([  ]*%) of the Shelter Fee
                        allocable to a Segment shall be payable within five (5)
                        Business Days of the Acceptance Date of the applicable
                        Segment containing such Shelters.

        3.03    Route Kilometer Adjustment. Subject to the foregoing, the Fiber
Fee in Section 3.02 shall be equitably adjusted to account for any difference
between actual and Estimated


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Long-Haul Kilometers. If the actual number of route kilometers exceeds by more
than [  ]* of the Estimated Long-Haul Kilometers in the aggregate, Impsat shall
bear the cost of any such excess over [  ]* and shall not be entitled to recover
from 360americas the cost of additional route kilometers as it relates to the
Total Fee and Recurring Service Charge.

        3.04    Method of Payment. All payments to be made to Impsat under this
Agreement shall be made in Dollars by wire transfer of immediately available
funds to the account or accounts designated by Impsat.

        3.05    Late Payment. Except as set forth in Section 3.06, if either
party fails to make any payment under this Agreement when due, such amount shall
accrue interest from the date such payment is due until it is paid, such
interest to be payable along with the amount due on the date the underlying
payment is due, compounded monthly at a rate per annum equal to the Interest
Rate.

        3.06    Disputed Amounts.

                A.      In the event that 360americas has an objection to any
                        payment obligation hereunder including Indirect Taxes
                        pursuant to Section 3.08, 360americas shall promptly
                        notify Impsat of such objection and such amount, and
                        Impsat and 360americas shall make every reasonable
                        effort to settle promptly the dispute concerning the
                        payment(s) in question. In the event such dispute cannot
                        be settled, Impsat and 360americas shall promptly
                        execute and deliver a Payment Escrow Agreement
                        substantially in the form of Exhibit D attached hereto
                        (the "Payment Escrow Agreement"), with such changes as
                        the Payment Escrow Agent may reasonably request, and
                        360americas will have the right to withhold payment of
                        the disputed amount(s) so long as it deposits, in full,
                        such disputed amount into the Dispute Account created
                        pursuant to the Payment Escrow Agreement (the "Dispute
                        Account").

                B.      Provided such disputed amount is placed into the Dispute
                        Account in a timely manner and 360americas has acted in
                        good faith, 360americas shall not be deemed to be in
                        breach of or in default for failing to pay Impsat.

                C.      The Payment Escrow Agent will distribute the disputed
                        amount in accordance with the terms of the Payment
                        Escrow Agreement.

                D.      In addition, the prevailing party shall be entitled to
                        receive from the Dispute Account an amount equal to the
                        interest earned by the Payment Escrow Agent on the
                        distributed, disputed amount, which shall be distributed
                        by the Payment Escrow Agent under clause (C) above.
                        Impsat and 360americas will equally share the costs and
                        expenses of the Payment Escrow Agent.


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                E.      360americas shall make timely payments for that portion
                        of any payments owed hereunder or such amount will
                        accrue interest as set forth in Section 3.05 above.

        3.07    No Set-Off. All payments under this Agreement shall not be
subject to any rights of set-off, counterclaim, deduction, defense or other
right that either party may have against each other or any other party.

        3.08    Indirect Taxes. The Fiber Fee, the Shelter Fee, the Recurring
Service Charge and any other amounts due from and payable by 360americas under
this Agreement are exclusive of any Indirect Taxes. Impsat shall be entitled to
include on any invoice, and 360americas shall pay, any Indirect Tax lawfully
imposed on any transaction contemplated by this Agreement. Notwithstanding the
foregoing, Impsat and 360americas each shall pay one-half of any stamp taxes
payable as a result of the execution and delivery of this Agreement. An
allocation of the fees based on the distances per province for stamp tax
purposes is set forth in Exhibit M.

        3.09    Income Taxes. Each party shall be responsible for its own Income
Taxes. Except as set forth in this Section 3.09, all payments made by
360americas hereunder shall be made without any deduction or withholding for or
on account of any Income Taxes, except where required by law. If 360americas is
required by law to make any deduction or withholding from any payment due
hereunder to Impsat, then, notwithstanding anything to the contrary contained in
this Agreement, the gross amount payable by 360americas shall be increased so
that, after any such deduction or withholding for Income Taxes, the net amount
received by Impsat will not be less than Impsat would have received had no such
deduction or withholding been required. This 'grossing-up' provision shall not
apply (i) to the extent the deduction or withholding merely constitutes a
prepayment of Impsat's or its Affiliates income tax liability or (ii) to the
extent such withholding results from an assignment by Impsat to a foreign
Affiliate of Impsat.

                                    ARTICLE 4
                   CONSTRUCTION OF THE IMPSAT ARGENTINA SYSTEM

        4.01    Construction Standards. Impsat shall design and construct the
Impsat Argentina System in accordance with the construction specifications set
forth in Exhibit E and industry standards and practices (the "Construction
Specifications"). All IRU Fiber shall be compliant with ITU G.655 and shall meet
or exceed the fiber specifications set forth in Exhibit F(1) and F(2) (the
"Fiber Specifications").

        4.02    Shelters.

                A.      Exhibit G sets forth the sites along the Argentina Route
                        at which regeneration facilities and optical
                        amplification facilities currently are located or are to
                        be installed in accordance with the specifications set
                        forth on Exhibit G and industry standards and practices
                        in the country of Argentina (collectively, the
                        "Shelters") and the approximate distance between such
                        Shelters and the status of the Shelter sites as of the
                        date of this Agreement. If Impsat's design of the Impsat
                        Argentina System results in a distance between any two
                        Shelters that is greater than 95 kilometers,


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                        Impsat shall install additional Shelters at 360americas'
                        request. For each additional Shelter, 360americas shall
                        pay to Impsat the amount of US$[  ]* plus the Costs of
                        acquiring and preparing the Shelter site.

                B.      The IRU with respect to the Associated Properties shall
                        include for 360americas the right to occupy and use,
                        subject to the terms of this Agreement, 20 square meters
                        of space and facilities in each Shelter. Such space
                        shall be exclusively for 360americas. 360americas
                        acknowledges that the sites for the Shelters may be
                        shared with Impsat and other entities, but that
                        360americas shall have exclusive access to its Shelters
                        for its sole use.

                C.      Upon reasonable prior notification to Impsat,
                        360americas (and its supplier and agents) shall be given
                        a right to unescorted access to the Shelter sites to
                        maintain its equipment and to add or upgrade equipment
                        as it may consider necessary.

                D.      Impsat shall provide the services set forth in Exhibit G
                        for the Shelters including, without limitation, power,
                        air conditioning, security and fire suppression.

        4.03    Completion of Construction. Impsat shall complete the
construction and satisfactorily perform the Acceptance Testing of each of the
Segments, including the provision of such Shelters on such Segment as are
required to be provided pursuant to Section 4.02, by the applicable Estimated
Delivery Date respecting such Segment.

        4.04    Liquidated Damages. The parties agree that damages for delay are
difficult to calculate and therefore agree that, if the Acceptance Date for any
Segment does not occur on or before the Estimated Delivery Date with respect to
such Segment, Impsat shall diligently continue work to complete the Segment, but
for each Segment that is not complete, commencing [  ]* calendar days following
the applicable Estimated Delivery Date, Impsat shall pay to 360americas by way
of liquidated damages (the "Liquidated Damages"), and not as a penalty, the
amount of [  ]*% of the applicable Fiber Fee and the applicable Shelter Fee for
such Segment per day until the Acceptance Date for such Segment, subject to a
cap on the amount of Liquidated Damages equal to [  ]*% of the Total Fee for
such Segment. In the event that all Segments under this Agreement (the "Network
Segments") have not been accepted by 360americas on or before [  ]* (the
"Network Completion Date"), Impsat shall continue to work to complete such
Segments as soon as practicable. In the event Impsat fails to deliver to
360americas or its Affiliates the Network Segments such that they are ready for
acceptance within [  ]* days following the Network Completion Date, 360americas
shall be entitled during a further [  ]* day period to reject any or all Network
Segments (except for those Segments if any which have prior to such date been
accepted by 360americas), and to terminate this Agreement as it relates to the
rejected Network Segments and demand the immediate return of all amounts
previously paid by 360americas to Impsat under this Agreement (with interest
thereon at the Interest Rate) and all accrued Liquidated Damages, with respect
to all non-accepted Segments. In the event that 360americas rejects all the
Network Segments, then with


                                       9

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   15

effect from the date all such Segments are rejected, Impsat's obligation to pay
any further Liquidated Damages shall cease and Impsat shall pay 360americas all
amounts previously paid by 360americas under this Agreement, together with
interest thereon at the Interest Rate and all accrued Liquidated Damages to
date. 360americas' sole remedies for any delay in the performance of Impsat
hereunder shall be the payment of Liquidated Damages hereunder and the right of
termination pursuant to Section 17.03(A) and any remedies set forth in Section
17.04. In the event 360americas terminates under this Section 4.04, Liquidated
Damages are due [  ]* days after such termination date. Otherwise, the amount of
Liquidated Damages will be applied to reduce the Fiber Fee.

        4.05    Inspection; Access to Information. Impsat shall provide
360americas or its designated Affiliates with reasonable access to inspect the
construction, splicing and testing of the IRU Fibers during the course and at
the time of the relevant construction, installation and testing period for the
purpose of verifying conformity with the Construction Specifications, provided
such access does not unreasonably interfere with Impsat's performance hereunder
and such access is coordinated in advance with Impsat. From time to time during
the Term, upon 360americas' written request, Impsat shall make available for
inspection by 360americas and its designees, at Impsat's offices, copies of all
information, documents, reports, permits, drawings and specifications generated,
obtained or acquired by Impsat in performing its duties pursuant to this Article
4 that are material to the grant of the IRUs to 360americas, including, without
limitation, the Underlying Rights. If the terms of such document or the legal
restrictions applicable to such information or document do not permit
disclosure, Impsat shall use commercially reasonable efforts to receive any
necessary consents to such disclosure and shall redact any necessary information
to protect disclosure of confidential business and proprietary terms.

        4.06    Documentation.


                A.      Within ninety (90) days after the Acceptance Date for
                        each Segment, Impsat shall provide 360americas with the
                        following documentation: (1) as-built drawings for such
                        Segment in accordance with the requirements described in
                        Exhibit E ("As-Builts"); and (2) technical
                        specifications of the optical fiber cable, associated
                        splices and other associated equipment placed in that
                        Segment.

                B.      Within thirty (30) days after the Effective Date, Impsat
                        shall provide 360americas with a plan of work. Such plan
                        of work will only be provided for informational purposes
                        and failure by Impsat to achieve any of the dates set
                        forth therein shall not be a breach of this Agreement.

        4.07    Construction Progress Reports. Impsat shall provide to
360americas, on the first day of each month, a construction progress report with
respect to status as of the first day of the previous month in accordance with
Exhibit H containing the following information: (a) scheduled and forecasted
completion dates for all Segments, (b) kilometers of fibers installed between
each Shelter, (c) a brief narrative describing the work performed and a list of
any


                                       10

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   16

potential risks that may prevent or delay project completion by the agreed
upon dates and the proposed actions to minimize or diminish such risks and (d)
other information of a similar nature reasonably requested by 360americas.

        4.08    Routing of IRU Fibers. Impsat may route the IRU Fibers through
Impsat's separate terminal, endlink, Telehouse or Shelters for operational
reasons, provided that Impsat shall be solely responsible for all costs and
expenses associated with the operation and maintenance of such facilities.

        4.09    Fiber Orders. Exhibit I sets forth Impsat's good faith estimate
of the status, as of the date of this Agreement, based on information currently
available to Impsat of orders for fiber optic cable for the IRU Fibers.

        4.10    Impsat System. Notwithstanding anything to the contrary
contained in this Agreement, Impsat may elect, at its option, to acquire any
portion of the Impsat System from third parties (whether under an indefeasible
right of use or otherwise) in lieu of constructing and installing the Impsat
System respecting such portion; provided, any such acquired portion shall be or
have been constructed substantially in accordance with the specifications and
procedures required by this Agreement and provided further that any of
360americas' rights under this Agreement should not be materially and adversely
affected, including without limitation, the Underlying Rights Requirements.

                                    ARTICLE 5
                             ACCEPTANCE AND TESTING

        5.01    Overview. Acceptance testing shall be conducted for each Segment
pursuant to the provisions of this Article 5 ("Acceptance Testing").

        5.02    Acceptance Testing by Impsat. Acceptance Testing of the IRU
Fibers and the Shelters as applicable, shall be conducted in accordance with
Exhibit J. To the extent Impsat has not previously performed testing prior to
the Effective Date, 360americas shall have the right, but not the obligation, to
have an individual present to observe Impsat's Acceptance Testing or to conduct
its own Acceptance Testing in accordance with Section 5.03 below. To the extent
Impsat has not previously performed testing prior to the Effective Date, Impsat
shall provide 360americas at least ten (10) days prior notice of Impsat's
testing schedule or any change in the date thereof (a "Testing Notice").

        5.03    Acceptance Testing by 360americas. 360americas shall have the
right, but not the obligation, at its sole expense, to conduct its own
Acceptance Testing to verify that the IRU Fibers meet the Fiber Specifications
and to inspect the IRU Fibers and the Shelters pursuant to Section 4.05 to
verify that a Segment conforms to the Construction Specifications. If
360americas elects to conduct its own Acceptance Testing, it shall notify Impsat
of its intent to do so (including dates and locations) at least three (3) days
prior to the date of Impsat's scheduled commencement of the Acceptance Testing
of a particular Segment as specified in Impsat's corresponding Testing Notice.
360americas may elect to perform such testing (i) itself subsequent to the
Impsat testing or (ii) concurrently with Impsat's testing, in which case both
parties shall reasonably cooperate with the other to facilitate such concurrent
testing. If


                                       11

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   17

360americas elects to perform the testing itself subsequent to Impsat's testing,
360americas will complete such testing within ten (10) days after Impsat
completes its Acceptance Testing of the relevant Segment. Impsat shall have the
right, but not the obligation, to have an individual present to observe
360americas' Acceptance Testing. Within fourteen (14) days after the conclusion
of 360americas' Acceptance Testing, 360americas shall provide Impsat with a copy
of the test results. 360americas' exercise or non-exercise of its right to
conduct Acceptance Testing shall not extend or shorten the time periods for
360americas to determine, pursuant to Section 5.04, if the Segment meets the
Fiber Specifications and the Construction Specifications. Impsat shall cooperate
in all reasonable respects with 360americas to facilitate any Acceptance Testing
that 360americas may choose to conduct pursuant to this Section 5.03; provided,
however, that Impsat shall retain authority to ensure that such testing does not
disrupt or interfere with any continued construction of such Segment that is
ongoing at such time.

        5.04    Failure Notice. If, within fourteen (14) days after the later of
(i) receipt by 360americas from Impsat of the test results referred to in
Section 5.02 or of the results of re-testing as set forth below and (ii)
360americas' conclusion of its own testing as provided in Section 5.03,
360americas reasonably determines that (i) Impsat's or 360americas' test results
show that the IRU Fibers with respect to a particular Segment do not meet the
Fiber Specifications set forth in Exhibit F(2) in all respects and the Fiber
Specifications set forth in F(1) in all material respects, or (ii) the Segment
does not comply with the Construction Specifications in all material respects,
360americas shall, within such fourteen (14) day period, notify Impsat of such
determination and shall identify in writing the specific data that indicate such
failure to meet the Fiber Specifications or the specific item that does not
comply with the Construction Specifications and the manner in which it does not
comply.

        5.05    Correction.

                A.      Upon receiving notice pursuant to Section 5.04 that a
                        Segment does not meet the Fiber Specifications or the
                        Construction Specifications, Impsat shall either:

                        (1)     Expeditiously take such action as is reasonably
                        necessary to cause such Segment to meet the Fiber
                        Specifications set forth in Exhibit F(2) in all respects
                        and the Fiber Specifications set forth in F(1) in all
                        material respects or the Construction Specifications and
                        then re-test (if applicable) the Segment in accordance
                        with the provisions of this Article 5; or

                        (2)     Notify 360americas within five (5) days of
                        receipt of a Failure Notice that Impsat disputes
                        360americas' determination that the Segment does not
                        meet the Fiber Specifications or the Construction
                        Specifications and invoke the provisions of Section
                        5.06.

                B.      After taking corrective actions and re-testing (if
                        appropriate), Impsat shall provide 360americas with a
                        copy of the new test results and 360americas shall again
                        have all rights provided in this Article 5 with respect
                        to such new test results.


                                       12

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   18

                C.      With respect to immaterial failures of a Segment to meet
                        the Fiber Specifications in F(1) or Construction
                        Specifications, notwithstanding, 360americas' acceptance
                        of such Segment, Impsat will promptly take action
                        necessary to cause the Segment to comply with such
                        Specifications.

        5.06    Testing by Third Party. If Impsat provides notice to 360americas
pursuant to Subsection 5.05(A)(2), the parties shall appoint a mutually
acceptable fiber optic testing company and such company shall re-test the
applicable Segment of the IRU Fibers. If that test demonstrates that the tested
Segment of the IRU Fibers meets the Fiber Specifications (without regard to any
changes to such portion by Impsat after the testing that gave rise to such
notice) as tested by 360americas, then 360americas shall pay the testing
company's charges and shall be deemed to have accepted the relevant Segment of
the IRU Fibers. If that test demonstrates that the relevant Segment of the IRU
Fibers does not meet the Fiber Specifications or that it does meet the Fiber
Specifications as the result of changes made by Impsat after the testing that
gave rise to such notice, then Impsat shall pay the testing company's charges
for performing the testing and shall perform the corrective action and
re-testing set forth in Subsection 5.05(A)(1).

        5.07    Acceptance Testing and Acceptance Date. If the Acceptance
Testing for a Segment shows that the Segment meets the Fiber Specifications and
Construction Specifications and 360americas either does not object to the
results of any Acceptance Testing or fails to notify Impsat of any failure of
such Segment to satisfy the Construction Specifications by written notice within
the time periods specified in Section 5.04, 360americas shall be deemed to have
accepted the Segment. The date of 360americas' notice accepting the Segment or
the date of 360americas' deemed acceptance (which shall be deemed to be the date
of the Acceptance Testing) under this Article 5 for the Segment shall be the
"Acceptance Date" of the Segment; provided, however, that for purposes of
Sections 4.04 and 17.03(A), such date shall be the date that 360americas
receives test results demonstrating, or deemed pursuant to this Section 5.07 to
demonstrate, that the Segment meets the Fiber Specifications. Notwithstanding
the foregoing, 360americas shall have no obligation to accept (but shall have
the right to accept) a Segment, and shall not be deemed by inaction to have
accepted a Segment, until the Estimated Delivery Date with respect to such
Segment. In addition, nothing contained in this Agreement to the contrary,
360americas shall have no obligation to accept a Segment unless the Shelter
associated with such Segment and the Telehouse, if any, at the endpoint of such
Segment are available for occupancy by 360americas, provided, however, that if
the Acceptance Date for a Segment has not occurred because of delay in Telehouse
availability, Liquidated Damages shall cease to accrue upon the date such
Segment has otherwise satisfied the Fiber Specifications.

        5.08    Spans. 360americas may, upon reasonable notice to Impsat,
request Impsat to perform Acceptance Testing with respect to portions of a
Segment identified by 360americas (such portions, a "Span"). In such event, the
parties shall cooperate to minimize any resulting interference with the
construction and Acceptance Testing of the remainder of such Segment, and Impsat
shall, subject to the aforesaid obligation of cooperation, not be responsible,
in Liquidated Damages or otherwise, for any resulting delay in the Acceptance
Date of the remainder of such Segment. The provisions of Sections 5.01 through
5.07 of this Agreement shall apply to such Spans mutatis mutandis.


                                       13

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   19

        5.09    Coordination With Other Agreements. [  ]*

                                    ARTICLE 6
                                      TERM

        6.01    Length of Term. The grant of the IRUs with respect to each
Segment hereunder shall become effective on the first day when both (a) the
Acceptance Date with respect to such Segment has occurred and (b) Impsat has
received payment in full of the Total Fee with respect to such Segment in
accordance with Article 3. Such grant shall extend with respect to such Segment,
or portion thereof, for the periods set forth in Exhibit B, as it may be
extended pursuant to Section 6.03 (the "Term").

        6.02    Ownership of IRU Fibers and Associated Properties. It is
understood and agreed that Impsat must and does maintain legal title to the IRU
Fibers, the Shelters and the Associated Property, subject to the grant of the
IRU hereunder.

        6.03    Extension of Term. 360americas shall have the option,
exercisable in writing no later than [  ]* days prior to the expiration of the
periods set forth in Exhibit B to renew the IRU for a period equal to the lesser
of (i) [  ]* and (ii) [  ]*, upon payment of US$[  ]* if Impsat shall thereafter
to continue to own and operate the Impsat Argentina System. If the IRUs
hereunder shall be renewed as aforesaid, 360americas shall pay its Pro Rata
Share of any Impositions and the costs of extending any Underlying Rights
assessed or incurred in connection with the renewal or during the renewal
period. 360americas shall execute (and, to the extent necessary, record, at its
own expense) instruments reasonably required by Impsat at the expiration or
termination of the Term of the IRU with respect to such Segment to clear from
Impsat's title or Impsat's property any leasehold interest, license, or other
possessory or nonpossessory estate, right or interest that 360americas (or
persons claiming through 360americas) might claim under this Agreement.

                                    ARTICLE 7
                                 NETWORK ACCESS

        7.01    Grant of Access. Impsat shall provide 360americas with access
to, and 360americas shall have the right to connect 360americas' communications
system with, the IRU Fibers at fiber distribution panels at the Shelters and
Telehouses and all splice points along the Argentina Route (each such access
point being referred to as a "Connecting Point"), provided such access does not
physically or operationally interfere with, or present a risk of damage to, any
portion of the Impsat Argentina System, including the equipment of Impsat or any
of its customers thereon, or any of the Shelters. The specific locations of each
such Connecting Point shall be in 360americas' space on 360americas' optical
distribution frame (ODF), as determined by 360americas, subject to the
Underlying Rights Requirements and 360americas having obtained any other
required permits, authorizations and approvals necessary to permit such
connection.

        7.02    Reimbursement; Scheduling. In order to schedule a connection of
this type, 360americas shall request and coordinate such work not less than
ninety (90) days in advance of the date the connection is requested to be
completed unless otherwise agreed to in writing by the


                                       14

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   20

parties. In addition, Impsat shall prepare a proposal regarding the costs of the
provision of such access which is reasonable compared to prevailing market
prices and the parties shall agree on the price to be paid to Impsat for the
provision of such services, which charges shall be reasonable in accordance with
industry standards. Such work will be restricted to a Planned System Work
Period, unless otherwise agreed to in writing by Impsat for specific projects.
Subject to all applicable Underlying Rights Requirements, 360americas shall also
be provided reasonable access by Impsat to any Connecting Point at all times.

                                    ARTICLE 8
                                   OPERATIONS

        8.01    Network Configuration. Subject to the provisions of this
Agreement, 360americas shall have full responsibility for determining any
network and service configuration or designs, routing configurations,
rearrangement or consolidation of channels or circuits and all related functions
with regard to its use of the IRU Fibers.

        8.02    Acknowledgments by 360americas. 360americas acknowledges and
agrees that:

                A.      Under this Agreement, Impsat is not obligated to supply
                        to 360americas any opto-electronics or electronics or
                        optical or electrical equipment, all of which are the
                        sole responsibility of 360americas; and

                B.      Except as set forth in this Agreement, Impsat is not
                        responsible for performing any work or providing any
                        facilities, including without limitation, monitoring and
                        testing equipment.

        8.03    Electronic and Photo-Optical Equipment. 360americas shall be
permitted to attach to the IRU Fibers such electronic, photo-optical, and other
equipment of its own choosing in order to allow the IRU Fibers to be used for
lawful communications purposes, and shall be permitted to locate such equipment
at the specified locations within the Shelters, as long as, in Impsat's
reasonable determination:

                A.      such installation and use comply with such health and
                        safety requirements as Impsat shall reasonably adopt
                        from time to time in its own discretion that generally
                        apply to its own use of the Impsat Argentina System,
                        provided such requirements are timely communicated to
                        360americas.

                B.      such equipment does not physically or operationally
                        interfere with, or present a risk of damage to, any
                        portion of the Impsat Argentina System, including the
                        equipment of Impsat or any of its customers thereon, or
                        any of the Shelters.

        8.04    Additional Equipment. The IRUs granted hereunder shall include
the right at 360americas' sole cost to install additional equipment, or replace
existing equipment, in the Shelters provided to 360americas pursuant to Section
4.02.


                                       15

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.
<PAGE>   21

                                    ARTICLE 9
                             MAINTENANCE AND REPAIR

        9.01    Maintenance Services. Beginning on the Acceptance Date with
respect to any Segment, Impsat shall provide the maintenance services set forth
in Exhibit K (the "Maintenance Services") in accordance with the Operations &
Maintenance Procedure set forth in Exhibit K. The IRU Fibers shall be maintained
throughout the Term in accordance with the procedures set forth in Exhibit K
and, to the extent not inconsistent with Exhibit K, industry standard procedures
for the applicable country.

        9.02    Recurring Service Charge. 360americas agrees to pay to Impsat
annually for the Maintenance Services the fees allocable to each Segment as set
forth in Exhibit C (the "Recurring Service Charge"). Such amount shall be
payable in advance in quarterly installments within thirty (30) days following
the commencement of each calendar quarter after the Acceptance Date of the
respective Segment. If the respective Acceptance Date does not occur at the
beginning of a calendar quarter, such payment shall be prorated based on the
number of calendar days remaining in the then current calendar quarter and paid
within thirty (30) calendar days following such Acceptance Date. [  ]*. For
purposes of this Section 9.02, "CPI-U" means the Consumer Price Index, All Urban
Consumers (CPI-U), U.S. City Average, published by the United States Department
of Labor, Bureau of Labor Statistics (1982-84), or, in the event such index
ceases to be computed or published, any successor index designated by Impsat in
its reasonable discretion. [  ]*

        9.03    Planned System Work Period. Impsat shall, as set forth in
Exhibit K, (a) notify 360americas of any Planned System Work Period and (b)
notify 360americas of any condition that in Impsat's judgment could reasonably
be expected to interrupt service on the IRU Fibers promptly after becoming aware
of the potential of such condition to adversely impact service on the IRU
Fibers. The parties shall establish detailed communication principles between
them, including details of personnel, contact details and periodic progress
meetings.

        9.04    Service Affecting Condition. [  ]*.

        9.05    Event of a Fault. In the event of a fault, each party shall
immediately notify the other party of the occurrence thereof. Impsat shall cause
such fault to be repaired and service to be restored within the respective
periods therefor set forth in Exhibit K. Impsat shall have access to the trouble
ticket system of 360americas.

        9.06    No Physical Access. Except as expressly set forth in this
Agreement, 360americas shall have no right to physically access the Impsat
Argentina System or maintain, adjust, align or attempt to repair the IRU Fiber
and Associated Properties.

        9.07    Optronic Equipment. Nothing in this Agreement shall obligate
Impsat to maintain 360americas' optronic, electrical, optical or other
equipment, all of which are the obligation and responsibility of 360americas.

        9.08    Subcontracting. In its sole discretion, Impsat may subcontract
provisioning, testing, maintenance, repair, restoration, relocation, or other
operational and technical services it


                                       16

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   22

is obligated to provide hereunder or may have the underlying facility owner or
its contractor perform such obligations; provided, however, such contracting
shall not relieve Impsat of any obligations under this Agreement.

                                   ARTICLE 10
                     PERMITS; UNDERLYING RIGHTS; RELOCATIONS

        10.01   Required Authorizations. Impsat will, at its cost and expense,
obtain and maintain during the applicable Term with respect to each Segment, all
permits, authorizations, licenses and approvals for the IRU Fibers, the Shelters
and the Associated Properties necessary to ensure 360americas' uninterrupted use
and operation of the IRU Fibers, the Shelters and the Associated Properties for
the period of the Term with respect to such Segments (the "Underlying Rights").
As of the Acceptance Date for each Segment, Impsat shall have obtained all
necessary Underlying Rights for the construction, installation and maintenance
of such Segment and the grant of the IRU hereunder in such Segment, and to
permit 360americas or its Affiliates to (A) use, operate and access the IRU
Fibers and related facilities in the manner contemplated by this Agreement,
including without limitation the right to access the IRU Fibers at the ODF at
the Shelters and Telehouses; and (B) subject to the last sentence of this
Section 10.01, operate a communications system using the Segments. Impsat
represents that the stated term of any Underlying Right will not expire in
accordance with its ordinary terms prior to the last day of the Term as set
forth on Exhibit B with respect to any Segment. If the stated term of any such
Underlying Right expires on a date earlier than the last day of the Term as set
forth on Exhibit B with respect to any Segment, Impsat shall, at its sole cost
and expense, exercise any renewal rights thereunder, or otherwise use all
reasonable endeavors to acquire such extensions, additions or replacements, or
secure alternative rights, or otherwise enable 360americas or its Affiliates to
use the Impsat Argentina System or the applicable Segment for the remainder of
the Term with respect to such Segment. 360americas shall have the right to
participate with Impsat in any negotiations or arrangements with respect to
extensions or additions to or replacements or alternatives for any such
Underlying Rights that terminate prior to the end of the Term. Except as
expressly set forth in this Agreement, nothing contained in this Agreement shall
be construed to be a representation, warranty or covenant of Impsat's right,
title or interest with respect to the right of way or the Underlying Right.
Notwithstanding any provision of this Agreement, 360americas shall be solely
responsible for procuring, obtaining and maintaining any telecommunications
licenses, consents, permissions, authorizations, franchises or other approvals
or permissions necessary for 360americas to provide service or communications
over the IRU Fibers, to connect to the Connection Points or to otherwise use the
Impsat Argentina System to provide or sell telecommunications services,
including, without limitation, a certification as a Public Telecommunications
Services Provider granted by the Argentina government (the "Telecommunication
Authorizations"), and shall be solely responsible for any additional costs
assessed against 360americas or Impsat as a result of any failure of 360americas
to procure, obtain or maintain such Telecommunication Authorizations.

        10.02   Relocation of Segment. If, after the Acceptance Date with
respect to a Segment, (i) Impsat is required, directly or indirectly, by a
governmental authority to (A) relocate any portion of such Segment, including
any of the Associated Properties used or required in providing the IRU in the
Segment, or (B) pay additional amounts in respect of such Segment


                                       17

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.
<PAGE>   23

(any such relocation or payments, a "Required Relocation") or (ii) Impsat
determines to effect such relocation for operational reasons, Impsat shall
proceed with such relocation, and shall have the right, in good faith, to
reasonably determine the extent of, the timing of, and methods to be used for
such relocation, provided that (a) any such relocation shall be constructed and
tested in accordance with the Construction Specifications and Fiber
Specifications, and (b) any such relocation shall not adversely affect in any
material respect the operations, performance, or endpoints of the Segment.
Impsat will (i) notify 360americas promptly after it determines to effect any
relocation, (ii) conduct such relocation in a manner that minimizes, to the
extent practicable, any disruption to the IRU Fibers and (iii) keep 360americas
informed of the progress and timing of any such relocation. [  ]*

        10.03   As-Builts Upon Relocation. Upon 360americas' written request,
Impsat shall deliver to 360americas updated As-Builts with respect to any
Segment relocated under Section 10.02 within ninety (90) days following the
completion of such relocation.

                                   ARTICLE 11
                               USE OF THE SEGMENTS

        11.01   Underlying Rights Requirements. The requirements, restrictions,
and/or limitations upon 360americas' right to use the IRU Fibers, the Shelters
and the Associated Properties as provided under this Agreement and as imposed
under, and associated with safety, operational and other rules and regulations
imposed in connection with the Underlying Rights, provided the same are
communicated to 360americas in writing, are referred to collectively as the
"Underlying Rights Requirements."

        11.02   Compliance of 360americas. 360americas shall use the IRU Fibers,
the Shelters and the Associated Properties in compliance with and subject to the
Underlying Rights Requirements and all applicable government codes, ordinances,
laws, rules and regulations.

        11.03   Limitations on Use. 360americas may use the IRU Fibers, the
Shelters and the Associated Properties for lawful communications purposes only,
including without limitation, leasing the IRU Fibers and granting IRUs and
providing other communications services derived from the IRU Fibers to third
parties and as permitted by the Underlying Rights Requirements and providing use
of the Shelters to third parties. 360americas agrees and acknowledges that it
has no right to use any of the fibers, other than the IRU Fibers, included in
the Cable or otherwise incorporated in the Impsat Argentina System. 360americas
shall keep any and all parts of the Impsat Argentina System free from any liens,
rights or claims of any third party attributable to 360americas. Impsat agrees
and acknowledges that it has no right to use the IRU Fibers during the Term.

        11.04   Impsat Argentina System. 360americas shall not use the Impsat
Argentina System in a way that physically or operationally interferes in any way
with or adversely affects the use of the Impsat Argentina System by any other
person including, without limitation, Impsat, it being expressly acknowledged
that the Impsat Argentina System includes or will include other participants,
including Impsat and other owners and holders of dark fiber, or other interests
and telecommunication system operations. Impsat shall not use the Impsat
Argentina System in a way that physically interferes with or adversely affects
360americas' use of the


                                       18

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   24

Impsat Argentina System, the Shelters, or the IRU Fibers, provided that
360americas uses the IRU Fibers, the Shelters and the Associated Properties in
compliance with the terms hereof. Impsat may comply with the obligations in the
foregoing sentence by obtaining a similar agreement from any person that
acquires the right to use fibers in the Impsat Argentina System after the date
hereof, which agreement provides that other users of the Impsat Argentina System
(including 360americas) are intended third party beneficiaries thereof.

        11.05   Cooperation. 360americas and Impsat each agree to cooperate with
and support the other in all reasonable respects in complying with any
requirements applicable to their respective rights and obligations hereunder by
any governmental or regulatory agency or authority.

                                   ARTICLE 12
                                 INDEMNIFICATION

        12.01   Indemnification by 360americas. Subject to the provisions of
Article 13, 360americas agrees to indemnify, defend, protect and hold harmless
Impsat and its Affiliates, their respective employees, agents, officers and
directors (the "Impsat Indemnitees"), from and against, and assumes all
liability for, all costs, loss, damage, expense, liability, suits, actions,
damages or claims of any character arising out of, related to, or in connection
with (a) any physical damage to the Impsat Argentina System or injury to persons
to the extent proximately caused by the acts or omissions of 360americas or its
agents, (b) 360americas' use of the IRU Fibers and/or the Impsat Argentina
System, (c) any breach or violation by 360americas of applicable law or
governmental regulation or other statute, rule or regulation issued by an
applicable regulatory authority, or (d) arising out of or in connection with a
contractual or other relationship between such claiming party and 360americas as
it relates to the IRU Fibers, the Impsat Argentina System or this Agreement.

        12.02   Indemnification by Impsat. Subject to the provisions of Article
13, Impsat agrees to indemnify, defend, protect and hold harmless 360americas
and its Affiliates, their respective employees, agents, officers and directors
(the "360americas Indemnitees"), from and against, and assumes all liability
for, all costs, loss, damage, expense, liability, suits, actions, damages or
claims of any character arising out of, related to, or in connection with (a)
any physical damage to the IRU Fibers, the Shelters or the Associated Properties
or injury to persons to the extent proximately caused by the acts or omissions
of Impsat or its agents, (b) Impsat's use of the Impsat Argentina System, (c)
arising out of or in connection with any negligent acts or omissions of Impsat
in the performance or non-performance of its obligations under this Agreement,
or (d) any breach or violation by Impsat of applicable law or governmental
regulation or other statute, rule or regulation issued by an applicable
regulatory authority.

        12.03   Notice. Each party agrees to promptly notify the other party
with notice of any claim that may result in an indemnification obligation
hereunder. The indemnifying party may defend such claim with counsel of its own
choosing, provided that no settlement or compromise of any such claim shall
occur without the consent of the indemnified party, which consent shall not be
unreasonably withheld or delayed.


                                       19

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   25

        12.04   Use Agreements. Notwithstanding the foregoing provisions of this
Article 12, to the extent Impsat is required under the terms and provisions of
any easement, supply contract, agreement, right-of-way, lease or indefeasible
right of use agreement relating to the provision of the IRU hereunder
(collectively, the "Use Agreements"), to indemnify the grantor or provider
thereof from and against any and all claims, demands, suits, judgments,
liabilities, losses or expenses arising out of or related to such Use
Agreements, regardless of the cause, 360americas hereby releases, and waives any
claims against such grantor or provider from the same, regardless of whether
such claims, suits, judgments, liabilities, losses or expenses arise from the
sole or partial negligence or willful misconduct or other action or inaction of
such grantor or provider or its employees, servants, agents, contractors,
subcontractors or other persons using the property or asset covered by such Use
Agreements.

                                   ARTICLE 13
                                    LIABILITY

        13.01   Limitation on Types of Damages. NOTWITHSTANDING ANY PROVISION OF
THIS AGREEMENT TO THE CONTRARY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY
FOR ANY SPECIAL, INCIDENTAL, INDIRECT, PUNITIVE OR CONSEQUENTIAL DAMAGES,
WHETHER FORESEEABLE OR NOT, ARISING OUT OF, OR IN CONNECTION WITH SUCH PARTY'S
PERFORMANCE OR FAILURE TO PERFORM ITS RESPECTIVE OBLIGATIONS OR BREACH OF ITS
RESPECTIVE REPRESENTATIONS HEREUNDER, INCLUDING, BUT NOT LIMITED TO, LOSS OF
USE, PROFITS OR REVENUE, COST OF CAPITAL, COST OF RESTORATION (WHETHER ARISING
OUT OF TRANSMISSION INTERRUPTIONS OR PROBLEMS, ANY INTERRUPTION OR DEGRADATION
OF SERVICE OR OTHERWISE), OR CLAIMS OF CUSTOMERS, IN EACH CASE WHETHER
OCCASIONED BY ANY CONSTRUCTION, RECONSTRUCTION, RELOCATION, REPAIR OR
MAINTENANCE PERFORMED BY, OR FAILED TO BE PERFORMED BY, THE OTHER PARTY OR ANY
OTHER CAUSE WHATSOEVER, WHETHER ARISING UNDER CONTRACT OR TORT, INCLUDING BREACH
OF CONTRACT, BREACH OF WARRANTY, ACTIVE, PASSIVE OR IMPUTED NEGLIGENCE, OR
STRICT LIABILITY, ALL CLAIMS WITH RESPECT SUCH SPECIAL, INCIDENTAL, INDIRECT,
PUNITIVE OR CONSEQUENTIAL DAMAGES ARE HEREBY SPECIFICALLY AND EXPRESSLY
DISCLAIMED, EXCLUDED AND WAIVED.

        13.02   Disclaimer of Warranty. EXCEPT AS SET FORTH IN THIS AGREEMENT,
IMPSAT MAKES NO WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE IRU FIBERS OR
THE SEGMENTS DELIVERABLE HEREUNDER, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR
FITNESS FOR PARTICULAR PURPOSE, AND ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY
DISCLAIMED. IT IS EXPRESSLY AGREED THAT IMPSAT'S SOLE OBLIGATION AND LIABILITY
FROM A BREACH OF THIS AGREEMENT AND 360AMERICAS' EXCLUSIVE REMEDIES FOR ANY
CAUSE WHATSOEVER (INCLUDING WITHOUT LIMITATION LIABILITY ARISING FROM
NEGLIGENCE) ARISING OUT OF OR RELATING TO THIS AGREEMENT UNDER ANY THEORY OF LAW
OR EQUITY ARE LIMITED TO THOSE SET FORTH IN ARTICLES 12, 17 AND 18 AND SECTION
4.04, AND ALL OTHER RIGHTS AND REMEDIES OF 360AMERICAS, INCLUDING (WITHOUT
LIMITATION)


                                       20

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   26

ANY THAT MIGHT OTHERWISE APPLY UNDER ANY UNIFORM COMMERCIAL CODE OR SIMILAR LAW
OF ANY KIND, ARE EXPRESSLY EXCLUDED, DISCLAIMED AND WAIVED. IMPSAT MAKES NO
WARRANTY, EXPRESS OR IMPLIED, TO ANY PERSON OR ENTITY OTHER THAN 360AMERICAS OR
ITS AFFILIATES CONCERNING THE IMPSAT ARGENTINA SYSTEM.

        13.03   Limitation on Amount of Damages. IN NO EVENT SHALL EITHER PARTY
BE LIABLE TO THE OTHER PARTY UNDER THIS AGREEMENT IN AN AGGREGATE AMOUNT THAT
EXCEEDS THE TOTAL FEE; PROVIDED, HOWEVER, THAT THE LIMITATION OF THIS SECTION
13.03 SHALL NOT APPLY TO ANY LOSS OR DAMAGE CAUSED BY THE WILLFUL MISCONDUCT OF
EITHER PARTY.

        13.04   Limitation on Time for Claim. The parties expressly agree that
no claim for losses or damages whatsoever in connection with this Agreement or a
claim for indemnity under the provisions of Article 12 shall be made more than
two (2) years after the date that the event giving rise to such claim is known
or reasonably should have been known to the party making such claim.

        13.05   Survival. The provisions of this Article 13 shall survive
expiration or termination of this Agreement.

                                   ARTICLE 14
                                    INSURANCE

        14.01   Required Insurance Policies. Following the date hereof, and
throughout the Term, each party shall procure and maintain in force, at its own
expense:

                A.      Not less than US$10,000,000 combined single limit, per
                        event and in the annual aggregate, liability insurance,
                        on an occurrence basis, for personal injury and property
                        damage, including liability for completed operations and
                        employers liability.

                B.      Workmen's Compensation insurance in a form and with
                        limits as required by local law, in no case less than
                        that stipulated by Workmen's Compensation Law No. 24557.

                C.      Automobile Liability Insurance covering death or injury
                        to any person or persons, or damage to property arising
                        from the operation of vehicles or equipment, with limits
                        of not less than US$3,000,000 per occurrence.

                D.      Any other insurance coverages specifically required of
                        such party pursuant to Impsat's agreements with third
                        parties with respect to the Underlying Rights.

        14.02   No Limitation of Liability. The limits specified in this Article
14 are minimum requirements and shall not be construed in any way as limits of
liability.


                                       21

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   27

        14.03   Additional Insured. Each party shall be named as additional
insured under the policies required to be maintained by the other under this
Article 14, with the exception of the insurance indicated under Section
14.01(B). 360americas' and Impsat's insurances shall be obtained and issued in
Argentina by financially sound and reputable insurance companies authorized to
operate in Argentina, and each party shall provide the other with an insurance
certificate confirming compliance with this requirement for each policy
providing such required coverage. Such insurance certificates shall provide for
at least (30) days prior written notice of cancellation or material change to
the other party. Each party shall pay the premiums on all insurances required
under this section when due and provide the other with evidence thereof.

        14.04   Failure to Obtain Insurance. In the event either party fails to
obtain the required insurance and a claim is made or suffered, such party shall
indemnify and hold harmless the other party from any and all claims for which
the required insurance would have provided coverage. Further, in the event of
any such failure which continues after seven (7) days' written notice thereof by
the other party, such other party may, but shall not be obligated to, obtain
such insurance and will have the right to be reimbursed for the cost of such
insurance by the party failing to obtain such insurance.

        14.05   Denial of Claim. In the event coverage is denied or
reimbursement of a properly presented claim is disputed by the carrier for
insurance provided above, the party carrying such coverage shall make good-faith
efforts to pursue such claim with its carrier for the benefit of the other
party.

        14.06   Waiver of Subrogation. Impsat and 360americas shall each obtain
from the insurance companies providing the coverages required by this Agreement,
the permission of such insurers to allow such party to waive all rights of
subrogation. Impsat and 360americas each waive any and all rights to recover
against the other, or against the officers, directors, Affiliates, shareholders,
partners, joint venturers, employees, agents and customers, invitees or business
visitors of such other party, for any loss or damage sustained by either party
for which reimbursement is available from any of the insurances carried by such
party pursuant to this Article, or any other insurance actually carried by such
party, but only to the extent of the recovery afforded by such insurance.

                                   ARTICLE 15
                 TAXES, FEES AND OTHER GOVERNMENTAL IMPOSITIONS

        15.01   Minimization of Impositions. The parties acknowledge and agree
that it is their mutual objective and intent to minimize, to the extent lawful
and feasible, the aggregate Impositions, Indirect Taxes and Income Taxes payable
with respect to the Impsat Argentina System and (b) share such Impositions
according to their respective interests in the Impsat Argentina System, and that
they will cooperate with each other in all reasonable respects and coordinate
their mutual efforts to achieve such objectives in accordance with the
provisions of this Article 15.

        15.02   Indirect Taxes and Income Taxes. Indirect Taxes and Income Taxes
shall be payable in accordance with the provisions of Sections 3.08 and 3.09.


                                       22

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.
<PAGE>   28

                A.      Impsat Impositions. Impsat shall be responsible for and
shall timely pay any and all Impositions with respect to the construction or
operation of the Impsat Argentina System which Impositions are (a) imposed or
assessed with respect to Impsat's ownership of the Impsat Argentina System for
periods prior to the Acceptance Date for a Segment or (b) imposed or assessed
(regardless of the time) with respect to the Impsat Argentina System in exchange
for the granting of an interest in public real property relating to the Impsat
Argentina System (except the Stamp Tax which will be shared equally by the
parties). Notwithstanding the foregoing obligations, Impsat shall have the right
to challenge any such Impositions.

                B.      360americas Impositions. Except as to Impositions
described in 15.02(A), following the Acceptance Date for any Segment,
360americas shall be responsible for and shall pay all Impositions which have
been separately assessed, allocated to, or imposed on the IRU Fibers by the
governmental authority imposing such Impositions. Notwithstanding the foregoing,
360americas shall have the right to challenge any such Impositions.

                C.      Mutual Impositions. Except as to Impositions described
in 15.02(A) or (B), following the Acceptance Date, Impsat shall timely pay any
and all Impositions imposed upon or with respect to the Impsat Argentina System
containing IRU Fibers to the extent such Impositions may not feasibly be
separately assessed or imposed upon or against the respective ownership
interests of Impsat and 360americas in the affected portion of the Impsat
Argentina System; provided that, except where Section 15.04 applies in the case
of a contested Imposition, upon receipt of a notice of any such Imposition,
Impsat shall promptly notify 360americas of such Imposition and following
payment of such Imposition by Impsat, 360americas shall promptly reimburse
Impsat for its proportionate share of such Imposition, which share shall be
determined (1) to the extent possible, based upon the manner and methodology
used by the particular authority imposing such Impositions (e.g., on the cost of
the relative property interests, historic or projected revenue derived
therefrom, or any combination thereof) or (2) if the same cannot be so
determined then based on 360americas' Pro Rata Share of the Impositions during
the relevant tax period. The amount of any reimbursement required to be made
under this Section 15.02(C) shall be increased by the amount of any Indirect
Taxes required to be paid by Impsat in respect of the receipt or accrual of such
reimbursement.

        15.03   Right to Contest. Notwithstanding any provision in this
Agreement to the contrary, Impsat shall have the right to contest any Imposition
(including by non-payment of such Imposition). The out-of-pocket costs and
expenses (including reasonable attorneys' fees) incurred by Impsat in any such
contest shall be shared by Impsat and 360americas to the extent 360americas
benefits from such contest, in the same proportion as to which the parties would
have shared in such Impositions, as they were originally assessed. Any refunds
or credits resulting from a contest brought pursuant to this Section 15.03 shall
be divided between Impsat and 360americas in the same proportion as to which
such refunded or credited Impositions were borne by Impsat and 360americas. In
any such event, Impsat shall provide timely notice of such challenge or refund
to 360americas.

        15.04   Future Cooperation. Impsat and 360americas agree to cooperate
fully in the preparation of any returns or reports relating to the Impositions.
Impsat and 360americas further acknowledge and agree that the provisions of this
Article 15 are intended to allocate the


                                       23

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.
<PAGE>   29

Impositions on procedures and methods of computation that are in effect on the
date of this Agreement. Material changes in such procedures and methods could
significantly alter the fundamental economic assumptions of the parties
underlying this Agreement. Accordingly, the parties agree that, if such
procedures or methods of computation change materially, the parties will
negotiate in good faith an amendment to this Article 15 to preserve, to the
extent reasonably practicable, the economic intent and effect of this Article
15.

                                   ARTICLE 16
                                 CONFIDENTIALITY

        16.01   Proprietary Information.

                A.      Impsat and 360americas hereby agree that if either party
                        provides (or, prior to the execution hereof, has
                        provided) confidential or proprietary information to the
                        other party that is identified as proprietary or
                        confidential or is clearly of such a nature
                        ("Proprietary Information"), such Proprietary
                        Information shall be held in confidence, and the
                        receiving party shall afford such Proprietary
                        Information the same care and protection as it affords
                        generally to its own confidential and proprietary
                        information (which in any case shall be not less than
                        reasonable care) in order to avoid disclosure to or
                        unauthorized use by any third party.

                B.      As used in this Agreement, Proprietary Information shall
                        mean any and all technical or business information
                        furnished, in whatever form or medium, or disclosed by
                        either party including, but not limited to, product or
                        service specifications, prototypes, computer programs,
                        models, drawings, marketing plans, financial data, and
                        personnel statistics.

                C.      All Proprietary Information, unless otherwise specified
                        in writing, shall remain the property of the disclosing
                        party, shall be used by the receiving party only for the
                        intended purpose, and such written Proprietary
                        Information, including all copies thereof, shall be
                        returned to the disclosing party or destroyed after the
                        receiving party's need for it has expired or upon the
                        request of the disclosing party. Proprietary Information
                        shall not be reproduced except to the extent necessary
                        to accomplish the purpose and intent of this Agreement,
                        or as otherwise may be permitted in writing by the
                        disclosing party.

        16.02   Permitted Disclosure. The foregoing provisions of Section 16.01
shall not apply to any Proprietary Information which (a) becomes publicly
available other than through the recipient hereunder; (b) is required to be
disclosed by a governmental or judicial law, order, rule or regulation or the
rules of any securities exchange or NASDAQ, provided that the party availing
itself of this exception has used commercially reasonable efforts to avoid or
limit such disclosure; (c) becomes available to the disclosing party without
restriction from a third party without an obligation to keep confidential such
Proprietary Information; or (d) becomes relevant to the settlement of any
dispute or enforcement of either party's rights under this Agreement in
accordance with the provisions of this Agreement, in which case appropriate
protective measures


                                       24

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   30

shall be taken to preserve the confidentiality of such Proprietary Information
as fully as possible within the confines of such settlement or enforcement
process. If any Proprietary Information is required to be disclosed pursuant to
the foregoing clause (b), the party required to make such disclosure shall
promptly inform the other party of the requirements of such disclosure.

        16.03   No Intellectual Property Transfer. Nothing in this Agreement
shall be construed as granting any right or license under any trademarks,
copyrights, inventions, patents or other intellectual property now or hereafter
owned or controlled by either party.

        16.04   Internal Disclosures. Notwithstanding Sections 16.01 and 16.02,
either party may disclose Proprietary Information to its employees, agents, and
legal, financial, and accounting advisors and providers (including its lenders
and other financing sources) to the extent necessary or appropriate in
connection with the negotiation and/or performance of this Agreement or its
obtaining of financing, provided that each such party is notified of the
confidential and proprietary nature of such Proprietary Information and is
subject to or agrees to be bound by similar restrictions on its use and
disclosure.

        16.05   Public Announcements. All media releases, public announcements,
and public disclosures relating to this Agreement or the subject matter of this
Agreement, including promotional or marketing material, but not including
announcements intended solely for internal distribution or disclosures to the
extent required to meet legal or regulatory requirements, shall be coordinated
with and shall be subject to approval by both parties prior to release.

        16.06   Survival. The provisions of this Article 16 shall survive
expiration or termination of this Agreement.

                                   ARTICLE 17
                                     DEFAULT

        17.01   Events of Default by 360americas. The happening of any one or
more of the following listed events (a "360americas Event of Default") shall
constitute a breach of this Agreement by 360americas:

                A.      If 360americas fails to pay Impsat any amounts owed
                        hereunder (except as set forth in Section 3.06),
                        including, without limitation, payment of any portion of
                        the Total Fee and the Recurring Service Charge, and does
                        not cure such non-payment within [  ]* days after
                        written notice of the same.

                B.      If 360americas breaches any of its material nonpayment
                        obligations and fails to cure such breach within [  ]*
                        days of written notice thereof by Impsat; provided,
                        however, that where such failure cannot reasonably be
                        cured within such [  ]*-day period and is susceptible to
                        cure, if 360americas shall proceed promptly to cure the
                        same and prosecute such cure with due diligence, the
                        time for curing such failure shall be extended for such
                        period of time as may be necessary to complete such
                        cure, up to a maximum of [  ]*.


                                       25

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.
<PAGE>   31

                C.      If 360americas files a petition in bankruptcy, makes an
                        assignment for the benefit of creditors, is adjudicated
                        insolvent or bankrupt, petitions or applies for a
                        receiver or trustee for a substantial part of its
                        property, commences any proceeding under any
                        reorganization arrangement, dissolution or liquidation
                        law or statute of any jurisdiction, or if there is
                        commenced against the other party any such proceeding
                        which has not been dismissed 120 days after
                        commencement.

        17.02   Remedies of Impsat Upon 360americas Event of Default. Subject to
the limitations of Article 13, upon any 360americas Event of Default, Impsat may
(a) take such action as it determines, in its sole discretion, to be necessary
to correct the default, (b) pursue any remedies it may have under this Agreement
or applicable law, (c) upon 10 days written notice specifying the intention to
terminate this Agreement, terminate this Agreement in its entirety, unless
360americas has paid all amounts due in respect of the Total Fee, in which case
Impsat shall not be entitled to terminate this Agreement in its entirety and
shall only be entitled to terminate the portions of this Agreement relating to
the provision of the Maintenance Services and/or to the remedies set forth in
clauses (a) and (b) above.

        17.03   Events of Default by Impsat. The happening of any one or more of
the following listed events (an "Impsat Event of Default") shall constitute a
breach of this Agreement by Impsat:

                A.      If 360americas terminates this Agreement pursuant to
                        Section 4.04.

                B.      If Impsat breaches any of its other material obligations
                        and fails to cure such breach within [  ]* days of
                        written notice thereof by 360americas; provided,
                        however, that where such failure cannot reasonably be
                        cured within such [  ]*-day period and is susceptible to
                        cure, if Impsat shall proceed promptly to cure the same
                        and prosecute such cure with due diligence, the time for
                        curing such failure shall be extended for such period of
                        time as may be necessary to complete such cure, up to a
                        maximum of [  ]* days.

                C.      If Impsat files a petition in bankruptcy, makes an
                        assignment for the benefit of creditors, is adjudicated
                        insolvent or bankrupt, petitions or applies for a
                        receiver or trustee for a substantial part of its
                        property, commences any proceeding under any
                        reorganization arrangement, dissolution or liquidation
                        law or statute of any jurisdiction, or if there is
                        commenced against the other party any such proceeding
                        which has not been dismissed 120 days after
                        commencement.

        17.04   Remedies of 360americas Upon Impsat Event of Default. Subject to
the limitations of Article 13, upon an Impsat Event of Default, 360americas may
(a) upon 10 days written notice specifying the intention to terminate this
Agreement, terminate this Agreement in its entirety and/or (b) pursue the
specific remedies it may have under this Agreement or applicable law; provided,
however, that in the event any Segment is not completed and not available to be
accepted by 360americas on or before the Estimated Delivery Date with respect


                                       26

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   32

to such Segment, the sole remedy of 360americas (in addition to its right to
terminate this Agreement pursuant to clause (a) above and the right to seek
specific performance) shall be Impsat's payment of Liquidated Damages pursuant
to Section 4.04 above.

                                   ARTICLE 18
                                   TERMINATION

                This Agreement shall become effective on the date hereof and,
unless earlier terminated pursuant to Article 17 above, shall terminate on the
date when all the Terms of the Segments shall have expired or terminated. Upon
the expiration of the Term with respect to any Segment or other termination of
this Agreement, the IRU with respect to such Segment shall immediately terminate
and all rights of 360americas to use the Impsat Argentina System, the IRU
Fibers, the Associated Properties or any part thereof relating to such Segment,
shall cease and Impsat shall have no further obligations to 360americas with
respect to such Segment. Promptly thereupon, 360americas shall remove all of
360americas' electronics, equipment, and other 360americas property from such
Segment and any related Impsat facilities at 360americas' sole cost, under
Impsat's supervision. 360americas shall repair such Segment to its original
condition before the installation of such equipment and property.
Notwithstanding the foregoing, no termination or expiration of this Agreement
shall affect the rights or obligations of any party hereto (a) with respect to
any then existing defaults or the obligation to make any payment hereunder for
services rendered prior to the date of termination or expiration, and (b) with
respect to those provisions of this Agreement that are expressly provided in
this Agreement to survive such termination.

                                   ARTICLE 19
                                  FORCE MAJEURE

                Neither party shall be in default under this Agreement if and to
the extent that any failure or delay in such party's performance of one or more
of its obligations hereunder is caused by any of the following conditions, and
such party's performance of one or more of its obligations shall be excused and
extended for and during the period of any such delay: act of God; weather; fire;
material failures, shortages or unavailability or other delay in delivery
(except for fiber or fiber cable) not resulting from the responsible party's
failure to timely place orders therefor; lack of or delay in transportation;
government or quasi-governmental codes, ordinances, laws, rules, regulations or
restrictions; war or civil disorder; strikes or other labor disputes; permitting
delays beyond the reasonable control of such party; or any other cause beyond
the reasonable control of such party. The party claiming relief under this
Article 19 shall notify the other in writing as soon as reasonably practicable
after the force majeure event, but in any event, no later than thirty (30) days,
of the existence of the event relied on and promptly of the cessation or
termination of said event, and the party claiming relief shall exercise
reasonable commercial efforts to minimize the time of any such delay. The
unavailability or shortages of, or delays in delivery of, fiber, cable or other
materials, standing alone, shall not constitute a force majeure event. As of the
Effective Date of this Agreement, neither party is aware of any force majeure
event.


                                       27

* CONFIDENTIAL TREATMENT REQUEST - Confidential portion has been omitted and
filed separately with the Commission.

<PAGE>   33

                                   ARTICLE 20
                                   ASSIGNMENT

        20.01   Assignment by Impsat. Except as provided in this Section 20.01
and 20.02, Impsat shall not assign, encumber or otherwise transfer this
Agreement or all or any portion of its rights or obligations hereunder to any
other party without the prior written consent of 360americas (which consent may
be withheld in 360americas' sole discretion). Notwithstanding the foregoing, and
subject to the provisions of this Article 20, Impsat shall have the right,
without 360americas' consent, to (a) subcontract any of its construction,
maintenance or testing obligations hereunder, or (b) assign or otherwise
transfer this Agreement in whole or in part (1) to any Affiliate of Impsat or
(2) to any corporation or other entity into which Impsat and its Affiliates may
be merged or consolidated or which purchases all or substantially all of the
stock or assets of Impsat and its Affiliates; provided that the assignee or
transferee in any such circumstance shall continue to be subject to all of the
provisions of this Agreement, including without limitation, this Section 20.01.
Promptly following any such permitted assignment or transfer, Impsat shall give
360americas written notice identifying the assignee or transferee. In the event
of any permitted partial assignment of any rights hereunder, Impsat shall remain
the sole point of contact with 360americas. No permitted partial or complete
assignment shall release or discharge Impsat from its duties and obligations
hereunder.

        20.02   Grant of Security Interest by Impsat.

                A.      360americas acknowledges and agrees that Impsat may
                        grant security interests of any kind in and/or
                        collaterally assign its rights with respect to, the
                        Impsat Argentina System, the IRU Fibers, the Associated
                        Properties, the Underlying Rights, the Shelters, and/or
                        this Agreement, including the proceeds thereof, to other
                        parties, and that this Agreement and all the rights
                        granted to 360americas hereunder are subject to and
                        subordinated to any such security interests, provided
                        that any secured party agrees, pursuant to a written
                        agreement reasonably satisfactory to 360americas (the
                        "Non-Disturbance Agreement"), to recognize and be bound
                        by the terms of this Agreement as long as (1) a
                        360americas Event of Default is not continuing, (2) this
                        Agreement is not supplemented, amended or extended or
                        otherwise modified in any manner that adversely affects
                        the interests of any secured party, and (3) after
                        receipt of notice from any secured party of a default by
                        Impsat under any relevant security document, 360americas
                        agrees to make, and makes, all payments under this
                        Agreement thereafter as instructed by a secured party
                        provided that 360americas is not required to pay any
                        amounts in excess of what it would have otherwise been
                        required to pay to Impsat. 360americas acknowledges and
                        consents to the foreclosure, should it occur, upon this
                        Agreement by any secured party or its designee,
                        successor or assignee, and the consequent replacement by
                        Impsat under this Agreement by the secured party, its
                        designee, successor or assignee, or another purchaser or
                        assignee. Impsat will use all commercially reasonable
                        efforts to cause any such secured party, upon request by
                        360americas, to provide a similar


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                        undertaking for the benefit of 360americas' lenders.
                        Impsat shall provide to 360americas a Non-Disturbance
                        Agreement executed by the secured parties (i) within
                        sixty (60) days of the Effective Date of this Agreement,
                        (ii) before the Acceptance Date of the applicable
                        Segment, and/or (iii) within thirty (30) days of the
                        addition of any new secured parties.

                B.      Any secured party shall be entitled to exercise all
                        rights and to cure any defaults of Impsat under this
                        Agreement, within such cure period as may be available
                        to Impsat under this Agreement. Upon receipt of notice
                        from a secured party, 360americas agrees to accept such
                        exercise and cure by a secured party and to render all
                        or any part of the performance due by 360americas under
                        this Agreement to such secured party.

                C.      Any secured party shall be deemed an intended third
                        party beneficiary of this Section 20.02. This Section
                        20.02 shall be self-operative and no further instrument
                        of subordination shall be required by any security
                        agreement, mortgage or other document reflecting the
                        security interest to make this subordination effective.
                        In confirmation of such acknowledged subordination,
                        360americas shall execute promptly any instrument or
                        certificate which Impsat or any secured party may
                        reasonably request.

        20.03   Assignment by 360americas. Except as provided below, 360americas
shall not assign, encumber or otherwise transfer this Agreement or all or any
portion of its rights or obligations hereunder to any other party without the
prior written consent of Impsat (which consent, prior to payment of the Total
Fee hereunder, may be withheld in Impsat's sole discretion, and after such
payment, may not be unreasonably withheld). 360americas shall have the right,
without Impsat's consent, to assign or otherwise transfer this Agreement (1) in
whole or in part, as collateral to any institutional lender to 360americas (or
institutional lender to any permitted transferee or assignee of 360americas
subject to the prior rights and obligations of the parties hereunder), (2) in
whole or in part, to any Affiliate of 360americas, (3) in whole but not in part,
to any other corporation or other entity into which 360americas and its
Affiliates may be merged or consolidated or which purchases all or substantially
all of the stock or assets of 360americas and its Affiliates; provided, however,
that the assignee or transferee in any such circumstance shall continue to be
subject to all of the provisions of this Agreement (except that any lender
referred to in clause (1) above shall not incur any obligations under this
Agreement, nor shall it be restricted from exercising any right of enforcement
or foreclosure with respect to any related security interest or lien, so long as
the purchaser in foreclosure is subject to the provisions of this Agreement,
including, without limitation, this Section 20.03). Promptly following any such
assignment or transfer, 360americas shall give Impsat written notice identifying
the assignee or transferee. In the event of any permitted partial assignment of
any rights hereunder, 360americas shall remain the sole party and point of
contact with Impsat hereunder. No permitted partial or complete assignment shall
release or discharge 360americas from its duties and obligations hereunder.
Impsat acknowledges and agrees that 360americas intends to collaterally assign
its interest in this Agreement to its institutional lenders.


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        20.04   Binding Effect. This Agreement and each of the parties'
respective rights and obligations under this Agreement, shall be binding upon
and shall inure to the benefit of the parties hereto and each of their
respective permitted successors and assigns.

        20.05   No Third Party Beneficiary. Except as otherwise provided in this
Article 20 and Section 11.04, nothing in this Agreement will be construed to
give any person other than the parties to this Agreement any legal or equitable
right under or with respect to this Agreement or any provision of this
Agreement.

                                   ARTICLE 21
                 REPRESENTATIONS, WARRANTIES AND ACKNOWLEDGMENTS

        21.01   Representations and Warranties of 360americas. 360americas
represents and warrants as follows:

                A.      360americas is a limited liability company duly
                        incorporated, validly existing and in good corporate
                        standing under the laws of its jurisdiction of
                        incorporation.

                B.      360americas has the corporate power and authority to
                        execute and deliver this Agreement and to perform its
                        obligations hereunder. Such execution, delivery and
                        performance have been duly authorized by all necessary
                        corporate action on the part of 360americas. This
                        Agreement has been duly executed and delivered by
                        360americas and constitutes the valid and legally
                        binding obligation of 360americas enforceable against
                        360americas in accordance with its terms.

                C.      Neither the execution and delivery of this Agreement nor
                        the performance or consummation of the transactions
                        contemplated hereunder will cause 360americas to be in
                        violation of (i) its governing documents or any
                        agreement by which it is bound or to which it is
                        subject, or, (ii) to the knowledge of 360americas, any
                        law or regulation to which it is subject.

                D.      To the knowledge of 360americas, no material consent,
                        order, approval or authorization or other action by, and
                        no notice to or filing with, any governmental authority
                        or regulatory body is required for the due execution,
                        delivery and performance by 360americas of the Agreement
                        and the consummation of the transactions contemplated
                        hereby.

                E.      There is no action, suit, proceeding or investigation
                        pending or, to the best knowledge of 360americas,
                        threatened, against or affecting 360americas or its
                        properties, assets or business, in any court or before
                        or by any governmental department, board, agency or
                        instrumentality, or any arbitrator, that materially
                        affects or impairs 360americas' ability to enter into
                        this Agreement, or to consummate the transactions
                        contemplated hereby.


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        21.02   Representations and Warranties of Impsat. Impsat represents and
warrants as follows:

                A.      Impsat is a corporation duly incorporated, validly
                        existing and in good corporate standing under the laws
                        of its jurisdiction of incorporation.

                B.      Impsat has the corporate power and authority to execute
                        and deliver this Agreement and to perform its
                        obligations hereunder. Such execution, delivery and
                        performance have been duly authorized by all necessary
                        corporate action on the part of Impsat. This Agreement
                        has been duly executed and delivered by Impsat and
                        constitutes the valid and legally binding obligation of
                        Impsat enforceable against Impsat in accordance with its
                        terms.

                C.      Neither the execution and delivery of this Agreement nor
                        the performance or consummation of the transactions
                        contemplated hereunder will cause Impsat to be in
                        violation of (i) its governing documents or any
                        agreement by which it is bound or to which it is
                        subject, or, (ii) to the knowledge of Impsat, any law or
                        regulation to which it is subject.

                D.      To the knowledge of Impsat, no material consent, order,
                        approval or authorization or other action by, and no
                        notice to or filing with, any governmental authority or
                        regulatory body is required for the due execution,
                        delivery and performance by Impsat of any of the
                        Agreement and the consummation of the transactions
                        contemplated hereby.

                E.      There is no action, suit, proceeding or investigation
                        pending or, to the best knowledge of Impsat, threatened,
                        against or affecting Impsat or its properties, assets or
                        business, in any court or before or by any governmental
                        department, board, agency or instrumentality, or any
                        arbitrator, that materially affects or impairs Impsat's
                        ability to enter into this Agreement, or to consummate
                        the transactions contemplated hereby.

        21.03   Survival. The foregoing representations and warranties shall
survive the execution and delivery of this Agreement.

                                   ARTICLE 22
                                     NOTICES

                All notices and communications concerning this Agreement shall
be addressed to the other party as follows:

                        If to Impsat:

                        Impsat S.A.
                        Alferez Pareja 256 (1107)
                        Buenos Aires, Argentina


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                     Fax: 54 (114) 4363-3758
                     Attention:  Alexander F. Rivelis

                     with a copy to:

                     Latham & Watkins
                     1001 Pennsylvania Avenue
                     Washington, DC 20004
                     Fax:  (202) 637-2201
                     Attention:  James R. Hanna

                     If to 360americas:

                     360networks de Argentina S.R.L.
                     c/o M&M Bomchil Abogados
                     Suipacha 268 pisa 12
                     C1008Aaf Buenos Aires
                     Argentina
                     Fax: 54 (114) 321-7555
                     Attention:  Francisco M. Gutierrez, Abogado

                     with a copy to:

                     360networks de Argentina S.R.L.
                     c/o 360networks inc.
                     1066 West Hastings Street, Suite 1500
                     Vancouver, British Columbia V6E 3XI
                     Canada
                     Fax: (604) 648-7747
                     Attention: Vice President and General Counsel

                     with a copy to:

                     360networks de Argentina S.R.L.
                     c/o 360networks (USA) inc.
                     13900 Lincoln Park Drive
                     Suite 230
                     Herndon, VA  20171
                     Fax: +(571) 203-6566
                     Attn:  General Manager

or at such other address as either party may designate from time to time in
writing to the other party.


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                Notices shall be hand delivered or sent by commercial overnight
delivery service, and shall be deemed served or delivered to the addressee or
its office when actually received or refused.

                                   ARTICLE 23
                                     GENERAL

        23.01   Waiver. No failure to exercise, and no delay in exercising, on
the part of either party, any privilege, any power or any right hereunder will
operate as a waiver thereof, nor will any single or partial exercise of any
privilege, right or power hereunder preclude further exercise of any privilege,
right or power hereunder.

        23.02   Governing Law. This Agreement shall be governed by and construed
in accordance with the domestic laws of the Republic of Argentina.

        23.03   Dispute Resolution. Any dispute arising under this Agreement
shall be subject to the Master Dispute Resolution Agreement dated as of the date
hereof, by and among Impsat Fiber Networks, Inc., Impsat S.A., Impsat
Comunicacoes Ltda., 360americas network (Bermuda) ltd., 360networks de Argentina
S.R.L. and 360networks do Brasil Ltda.

        23.04   Jurisdiction. Jurisdiction shall be subject to the Master
Dispute Resolution Agreement dated as of the date hereof, by and among Impsat
Fiber Networks, Inc., Impsat S.A., Impsat Comunicacoes Ltda., 360americas
network (Bermuda) ltd., 360networks de Argentina S.R.L. and 360networks do
Brasil Ltda.

        23.05   Expenses. Except as otherwise expressly provided in this
Agreement, each party to this Agreement shall bear its respective expenses
incurred in connection with the preparation, execution and performance of this
Agreement and the transactions contemplated hereby, including all fees and
expenses of its representatives.

        23.06   Rules of Construction.

                A.      The captions or headings in this Agreement are strictly
                        for convenience and shall not be considered in
                        interpreting this Agreement or as amplifying or limiting
                        any of its content. All words used in this Agreement
                        will be construed to be of such gender or number as the
                        context requires.

                B.      Unless expressly defined in this Agreement, words having
                        well known technical or trade meanings shall be so
                        construed. All listing of items shall not be taken to be
                        exclusive, but shall include other items, whether
                        similar or dissimilar to those listed, as the context
                        reasonably requires.

                C.      This Agreement has been fully negotiated between and
                        jointly drafted by the parties.


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                D.      All actions, activities, consents, approvals and other
                        undertakings of the parties in this Agreement shall be
                        performed in a reasonable and timely manner. Except as
                        specifically set forth in this Agreement, for the
                        purpose of this Agreement, the standards and practices
                        of performance within the telecommunications industry in
                        the relevant market shall be the measure of a party's
                        performance.

        23.07   Entire Agreement. This Agreement and the Master Agreement dated
as of the date hereof, by and among Impsat Fiber Networks, Inc., Impsat S.A.,
Impsat Comunicacoes Ltda., 360americas network (Bermuda) ltd., 360networks de
Argentina S.R.L. and 360networks do Brasil Ltda., constitute the entire and
final agreement and understanding between the parties with respect to the
subject matter hereof and supersede all prior agreements relating to the subject
matter hereof (including without limitation the Telecommunications Services
Agreement). The Exhibits referred to in this Agreement are integral parts hereof
and are hereby made a part of this Agreement; provided, however, that to the
extent that any of the provisions of any Exhibit hereto are inconsistent with
the express terms of this Agreement, the terms of this Agreement shall prevail.
This Agreement may only be modified or supplemented by an instrument in writing
executed by a duly authorized representative of each party and delivered to the
party relying on the writing.

        23.08   Relationship of the Parties. The relationship between
360americas and Impsat shall not be that of partners, agents, or joint venturers
for one another, and nothing contained in this Agreement shall be deemed to
constitute a partnership or agency agreement between them for any purposes,
including, but not limited to federal income tax purposes.

        23.09   Severability. If any term, covenant or condition contained in
this Agreement is, to any extent, held invalid or unenforceable in any respect
under the laws governing this Agreement, the remainder of this Agreement shall
not be affected thereby, and each term, covenant or condition of this Agreement
shall be valid and enforceable to the fullest extent permitted by law. The
parties further agree that if any provision contained in this Agreement is, to
any extent, held invalid or unenforceable in any respect under the laws
governing this Agreement, they shall take any actions necessary to render the
remaining provisions of this Agreement valid and enforceable to the fullest
extent permitted by law and, to the extent necessary, shall amend or otherwise
modify this Agreement to replace any provision contained in this Agreement which
is held invalid or unenforceable with a valid and enforceable provision giving
effect to the intent of the parties.

        23.10   Further Assurances. In connection with this Agreement and the
transactions contemplated hereby, each party shall execute and deliver any
additional documents and instruments and perform any additional acts that may be
necessary or appropriate to effectuate and perform the provisions of this
Agreement and such transactions.

        23.11   Counterparts. This Agreement may be executed in one or more
counterparts, each of which will be deemed to be an original copy of this
Agreement, and all of which, when taken together, will be deemed to constitute
one and the same agreement. The exchange of copies of this Agreement and of
signature pages by facsimile transmission shall constitute effective


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<PAGE>   40

execution and delivery of this Agreement as to the parties and may be used in
lieu of the original Agreement for all purposes. Signatures of the parties
transmitted by facsimile shall be deemed to be their original signatures for any
purposes whatsoever.


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                IN WITNESS WHEREOF, Impsat and 360americas have executed this
Agreement as of the date first above written.

                                    IMPSAT S.A.
                                    an Argentina corporation


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



                                    360NETWORKS DE ARGENTINA S.R.L.
                                    an Argentina limited liability company


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



                                       36

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filed separately with the Commission.