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                                                                     EXHIBIT 4.2

                                                                  EXECUTION COPY





                          REGISTRATION RIGHTS AGREEMENT


                             Dated February 16, 2000


                                     between


                           IMPSAT FIBER NETWORKS, INC.


                                       and


                        MORGAN STANLEY & CO. INCORPORATED


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

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                          REGISTRATION RIGHTS AGREEMENT

              THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made and
entered into February 16, 2000, among IMPSAT FIBER NETWORKS, INC., a Delaware
corporation (the "Company"), and MORGAN STANLEY & CO. INCORPORATED (the
"Placement Agent").

              This Agreement is made pursuant to the Placement Agreement dated
February 11, 2000, between the Company and the Placement Agent (the "Placement
Agreement"), which provides for the sale by the Company to the Placement Agent
of an aggregate of $300,000,000 principal amount of the Company's 13 3/4% Senior
Notes due 2005 (the "Securities"). In order to induce the Placement Agent to
enter into the Placement Agreement, the Company has agreed to provide to the
Placement Agent and its direct and indirect transferees the registration rights
set forth in this Agreement. The execution of this Agreement is a condition to
the closing under the Placement Agreement.

              In consideration of the foregoing, the parties hereto agree as
follows:

              1.     Definitions.

              As used in this Agreement, the following capitalized defined terms
shall have the following meanings:

              "1933 Act" shall mean the Securities Act of 1933, as amended from
       time to time.

              "1934 Act" shall mean the Securities Exchange Act of 1934, as
       amended from time to time.

              "Closing Date" shall mean the Closing Date as defined in the
       Placement Agreement.

              "Company" shall have the meaning set forth in the preamble and
       shall also include the Company's successors.

              "Exchange Offer" shall mean the exchange offer by the Company of
       Exchange Securities for Registrable Securities pursuant to Section 2(a)
       hereof.

              "Exchange Offer Registration" shall mean a registration under the
       1933 Act effected pursuant to Section 2(a) hereof.

              "Exchange Offer Registration Statement" shall mean an exchange
       offer registration statement on Form S-4 (or, if applicable, on another
       appropriate form) and all amendments and supplements to such registration
       statement, in each case including the


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       Prospectus contained therein, all exhibits thereto and all material
       incorporated by reference therein.

              "Exchange Securities" shall mean Securities issued by the Company
       under the Indenture containing terms identical to the Securities (except
       that the Exchange Securities will not contain terms with respect to
       transfer restrictions) and to be offered to Holders in exchange for
       Securities pursuant to the Exchange Offer.

              "Holder" shall mean the Placement Agent, for so long as it owns
       any Registrable Securities, and its successors, assigns and direct and
       indirect transferees who become registered owners of Registrable
       Securities under the Indenture; provided that for purposes of Sections 4
       and 5 of this Agreement, the term "Holder" shall include Participating
       Broker-Dealers (as defined in Section 4(a)).

              "Indenture" shall mean the Indenture relating to the Securities
       dated as of February 16, 2000 among the Company, The Bank of New York, as
       trustee, registrar and paying agent and Banque Internationale a
       Luxembourg S.A., as paying agent and transfer agent, and as the same may
       be amended from time to time in accordance with the terms thereof.

              "Majority Holders" shall mean the Holders of a majority of the
       aggregate principal amount of outstanding Registrable Securities;
       provided that whenever the consent or approval of Holders of a specified
       percentage of Registrable Securities is required hereunder, Registrable
       Securities held by the Company or any of its affiliates (other than the
       Placement Agent or any other Holder deemed an affiliate solely by reason
       of its holding one or more Registrable Securities) shall not be counted
       in determining whether such consent or approval was given by the Holders
       of such required percentage or amount.

              "Person" shall mean an individual, partnership, corporation, trust
       or unincorporated organization, or a government or agency or political
       subdivision thereof.

              "Placement Agent" shall have the meaning set forth in the
       preamble.

              "Placement Agreement" shall have the meaning set forth in the
       preamble.

              "Prospectus" shall mean the prospectus included in a Registration
       Statement, including any preliminary prospectus, and any such prospectus
       as amended or supplemented by any prospectus supplement, including a
       prospectus supplement with respect to the terms of the offering of any
       portion of the Registrable Securities covered by a Shelf Registration
       Statement, and by all other amendments and supplements to such
       prospectus, and in each case including all material incorporated by
       reference therein.


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              "Registrable Securities" shall mean the Securities; provided,
       however, that the Securities shall cease to be Registrable Securities (i)
       when a Registration Statement with respect to such Securities shall have
       been declared effective under the 1933 Act and such Securities shall have
       been disposed of pursuant to such Registration Statement, (ii) when such
       Securities have been sold to the public pursuant to Rule 144(k) (or any
       similar provision then in force, but not Rule 144A) under the 1933 Act or
       (iii) when such Securities shall have ceased to be outstanding, provided,
       further, that the Securities with respect to which the Company has caused
       to be filed and declared effective an Exchange Offer Registration
       Statement and has commenced an Exchange Offer, in each case pursuant to
       and in accordance with Section 2 hereof, and which have not been tendered
       by the last Exchange Date (as defined in Section 2(a)(ii) hereof) by the
       Holder thereof shall be deemed not be to Registrable Securities.

              "Registration Expenses" shall mean any and all expenses incident
       to performance of or compliance by the Company with this Agreement,
       including without limitation: (i) all SEC, stock exchange or National
       Association of Securities Dealers, Inc. registration and filing fees,
       (ii) all fees and expenses incurred in connection with compliance with
       state securities or blue sky laws (including reasonable fees and
       disbursements of counsel for any underwriters or Holders in connection
       with blue sky qualification of any of the Exchange Securities or
       Registrable Securities), (iii) all expenses of any Persons in preparing
       or assisting in preparing, word processing, printing and distributing any
       Registration Statement, any Prospectus, any amendments or supplements
       thereto, any underwriting agreements, securities sales agreements and
       other documents relating to the performance of and compliance with this
       Agreement, (iv) all rating agency fees, (v) all fees and disbursements
       relating to the qualification of the Indenture under applicable
       securities laws, (vi) the fees and disbursements of the Trustee and its
       counsel, (vii) the fees and disbursements of counsel for the Company and,
       in the case of a Shelf Registration Statement, the fees and disbursements
       of one counsel for the Holders (which counsel shall be selected by the
       Majority Holders and which counsel may also be counsel for the Placement
       Agent) and (viii) the fees and disbursements of the independent public
       accountants of the Company, including the expenses of any special audits
       or "comfort" letters required by or incident to such performance and
       compliance, but excluding fees and expenses of counsel to the
       underwriters (other than fees and expenses set forth in clause (ii)
       above) or the Holders and underwriting discounts and commissions and
       transfer taxes, if any, relating to the sale or disposition of
       Registrable Securities by a Holder.

              "Registration Statement" shall mean any registration statement of
       the Company that covers any of the Exchange Securities or Registrable
       Securities pursuant to the provisions of this Agreement and all
       amendments and supplements to any such Registration Statement, including
       post-effective amendments, in each case including the Prospectus
       contained therein, all exhibits thereto and all material incorporated by
       reference therein.


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              "SEC" shall mean the Securities and Exchange Commission.

              "Shelf Registration" shall mean a registration effected pursuant
       to Section 2(b) hereof.

              "Shelf Registration Statement" shall mean a "shelf" registration
       statement of the Company pursuant to the provisions of Section 2(b) of
       this Agreement which covers all of the Registrable Securities (but no
       other securities unless approved by the Holders whose Registrable
       Securities are covered by such Shelf Registration Statement) on an
       appropriate form under Rule 415 under the 1933 Act, or any similar rule
       that may be adopted by the SEC, and all amendments and supplements to
       such registration statement, including post-effective amendments, in each
       case including the Prospectus contained therein, all exhibits thereto and
       all material incorporated by reference therein.

              "Trustee" shall mean the trustee with respect to the Securities
       under the Indenture.

              "Underwriter" shall have the meaning set forth in Section 3
       hereof.

              "Underwritten Registration" or "Underwritten Offering" shall mean
       a registration in which Registrable Securities are sold to an Underwriter
       for reoffering to the public.

              2.     Registration Under the 1933 Act.

              (a)    To the extent not prohibited by any applicable law or
applicable interpretation of the Staff of the SEC, the Company shall use its
best efforts to cause to be filed an Exchange Offer Registration Statement
covering the offer by the Company to the Holders to exchange all of the
Registrable Securities for Exchange Securities and to have such Registration
Statement remain effective until the closing of the Exchange Offer. The Company
shall commence the Exchange Offer promptly after the Exchange Offer Registration
Statement has been declared effective by the SEC and use its best efforts to
have the Exchange Offer consummated not later than 60 days after such effective
date. The Company shall commence the Exchange Offer by mailing the related
exchange offer Prospectus and accompanying documents to each Holder stating, in
addition to such other disclosures as are required by applicable law:

              (i)    that the Exchange Offer is being made pursuant to this
       Registration Rights Agreement and that all Registrable Securities validly
       tendered will be accepted for exchange;

              (ii)   the dates of acceptance for exchange (which shall be a
       period of at least 20 business days from the date such notice is mailed)
       (the "Exchange Dates");


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              (iii)  that any Registrable Security not tendered will remain
       outstanding and continue to accrue interest but will not retain any
       rights under this Registration Rights Agreement (including any right to
       have the interest rate therein increased pursuant thereto);

              (iv)   that Holders electing to have a Registrable Security
       exchanged pursuant to the Exchange Offer will be required to surrender
       such Registrable Security, together with the enclosed letters of
       transmittal, to the institution and at the address (located in the
       Borough of Manhattan, The City of New York) specified in the notice prior
       to the close of business on the last Exchange Date; and

              (v)    that Holders will be entitled to withdraw their election,
       not later than the close of business on the last Exchange Date, by
       sending to the institution and at the address (located in the Borough of
       Manhattan, The City of New York) specified in the notice a telegram,
       telex, facsimile transmission or letter setting forth the name of such
       Holder, the principal amount of Registrable Securities delivered for
       exchange and a statement that such Holder is withdrawing his election to
       have such Securities exchanged.

              As soon as practicable after the last Exchange Date, the Company
       shall:

              (i)    accept for exchange Registrable Securities or portions
       thereof tendered and not validly withdrawn pursuant to the Exchange
       Offer;

              (ii)   deliver, or cause to be delivered, to the Trustee for
       cancellation all Registrable Securities or portions thereof so accepted
       for exchange by the Company and issue, and cause the Trustee to promptly
       authenticate and mail to each Holder, an Exchange Security equal in
       principal amount of the Registrable Securities surrendered by such
       Holder; and

              (iii)  use its best efforts to list the Exchange Securities on the
       Luxembourg Stock Exchange.

The Company shall use its best efforts to complete the Exchange Offer as
provided above and shall comply with the applicable requirements of the 1933
Act, the 1934 Act and other applicable laws and regulations in connection with
the Exchange Offer. The Exchange Offer shall not be subject to any conditions,
other than that the Exchange Offer does not violate applicable law or any
applicable interpretation of the Staff of the SEC. The Company shall inform the
Placement Agent of the names and addresses of the Holders to whom the Exchange
Offer is made, and the Placement Agent shall have the right, subject to
applicable law, to contact such Holders and otherwise facilitate the tender of
Registrable Securities in the Exchange Offer.

              (b)    In the event that (i) the Company determines that the
Exchange Offer Registration provided for in Section 2(a) above is not available
or may not be consummated as

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soon as practicable after the last Exchange Date because it would violate
applicable law or the applicable interpretations of the Staff of the SEC, (ii)
the Exchange Offer is not for any other reason consummated by August 16, 2000 or
(iii) the Exchange Offer has been completed and in the opinion of counsel for
the Placement Agent a Registration Statement must be filed and a Prospectus must
be delivered by the Placement Agent in connection with any offering or sale of
Registrable Securities, the Company shall use its best efforts to cause to be
filed as soon as practicable after such determination, date or notice of such
opinion of counsel is given to the Company, as the case may be, a Shelf
Registration Statement providing for the sale by the Holders of all of the
Registrable Securities and to have such Shelf Registration Statement declared
effective by the SEC (such obligation, arising solely under clause (ii) above,
to have filed a Shelf Registration Statement shall be deemed satisfied with
respect to any Holder upon consummation of the Exchange Offer with respect to
such Holder). In the event the Company is required to file a Shelf Registration
Statement solely as a result of the matters referred to in clause (iii) of the
preceding sentence, the Company shall use its best efforts to file and have
declared effective by the SEC both an Exchange Offer Registration Statement
pursuant to Section 2(a) with respect to all Registrable Securities and a Shelf
Registration Statement (which may be a combined Registration Statement with the
Exchange Offer Registration Statement) with respect to offers and sales of
Registrable Securities held by the Placement Agent after completion of the
Exchange Offer. The Company agrees to use its best efforts to keep the Shelf
Registration Statement continuously effective until the expiration of the period
referred to in Rule 144(k) with respect to the Registrable Securities or such
shorter period that will terminate when all of the Registrable Securities
covered by the Shelf Registration Statement have been sold pursuant to the Shelf
Registration Statement. The Company further agrees to supplement or amend the
Shelf Registration Statement if required by the rules, regulations or
instructions applicable to the registration form used by the Company for such
Shelf Registration Statement or by the 1933 Act or by any other rules and
regulations thereunder for shelf registration or if reasonably requested by a
Holder with respect to information relating to such Holder, and to use its best
efforts to cause any such amendment to become effective and such Shelf
Registration Statement to become usable as soon as thereafter practicable. The
Company agrees to furnish to the Holders of Registrable Securities copies of any
such supplement or amendment promptly after its being used or filed with the
SEC.

              (c)    The Company shall pay all Registration Expenses in
connection with the registration pursuant to Section 2(a) or Section 2(b). Each
Holder shall pay all underwriting discounts and commissions and transfer taxes,
if any, relating to the sale or disposition of such Holder's Registrable
Securities pursuant to the Shelf Registration Statement.

              (d)    An Exchange Offer Registration Statement pursuant to
Section 2(a) hereof or a Shelf Registration Statement pursuant to Section 2(b)
hereof will not be deemed to have become effective unless it has been declared
effective by the SEC; provided, however, that, if, after it has been declared
effective, the offering of Registrable Securities pursuant to a Shelf
Registration Statement is interfered with by any stop order, injunction or other
order or requirement of the SEC or any other governmental agency or court, such
Registration Statement


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will be deemed not to have become effective during the period of such
interference until the offering of Registrable Securities pursuant to such
Registration Statement may legally resume. As provided for in the Indenture, in
the event the Exchange Offer is not consummated and the Shelf Registration
Statement is not declared effective on or prior to August 16, 2000, the interest
rate on the Securities will increase by .5% per annum to 14 1/4% per annum. Upon
consummation of the Exchange Offer or the effectiveness of the Shelf
Registration Statement as declared by the SEC, as the case may be, the rate of
interest on the Securities will decrease to the original rate of interest of 13
3/4% per annum for the Securities. If a Shelf Registration Statement is required
solely by the matters referred to in clause (iii) of the first sentence of
Section 2(b), such increase in interest rate shall be payable only to the
Placement Agent, with respect to the Securities held by them, and only with
respect to any period (after August 16, 2000) during which such Shelf
Registration Statement is not effective.

              (e)    Without limiting the remedies available to the Placement
Agent and the Holders, the Company acknowledges that any failure by the Company
to comply with its obligations under Section 2(a) and Section 2(b) hereof may
result in material irreparable injury to the Placement Agent or the Holders for
which there is no adequate remedy at law, that it will not be possible to
measure damages for such injuries precisely and that, in the event of any such
failure, the Placement Agent or any Holder may obtain such relief as may be
required to specifically enforce the Company's obligations under Section 2(a)
and Section 2(b) hereof.

              3.     Registration Procedures.

              In connection with the obligations of the Company with respect to
the Registration Statements pursuant to Section 2(a) and Section 2(b) hereof,
the Company shall as expeditiously as possible:

              (a)    prepare and file with the SEC a Registration Statement on
       the appropriate form under the 1933 Act, which form (x) shall be selected
       by the Company and (y) shall, in the case of a Shelf Registration, be
       available for the sale of the Registrable Securities by the selling
       Holders thereof and (z) shall comply as to form in all material respects
       with the requirements of the applicable form and include all financial
       statements required by the SEC to be filed therewith, and use its best
       efforts to cause such Registration Statement to become effective and
       remain effective in accordance with Section 2 hereof;

              (b)    prepare and file with the SEC such amendments and
       post-effective amendments to each Registration Statement as may be
       necessary to keep such Registration Statement effective for the
       applicable period and cause each Prospectus to be supplemented by any
       required prospectus supplement and, as so supplemented, to be filed
       pursuant to Rule 424 under the 1933 Act; to keep each Prospectus current
       during the period described under Section 4(3) and Rule 174 under the
       1933 Act that is applicable to transactions by brokers or dealers with
       respect to the Registrable Securities or Exchange Securities;


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              (c)    in the case of a Shelf Registration, furnish to each Holder
       of Registrable Securities, to counsel for the Placement Agent, to counsel
       for the Holders and to each Underwriter of an Underwritten Offering of
       Registrable Securities, if any, without charge, as many copies of each
       Prospectus, including each preliminary Prospectus, and any amendment or
       supplement thereto and such other documents as such Holder or Underwriter
       may reasonably request, in order to facilitate the public sale or other
       disposition of the Registrable Securities; and the Company consents to
       the use of such Prospectus and any amendment or supplement thereto in
       accordance with applicable law by each of the selling Holders of
       Registrable Securities and any such Underwriters in connection with the
       offering and sale of the Registrable Securities covered by and in the
       manner described in such Prospectus or any amendment or supplement
       thereto in accordance with applicable law;

              (d)    use its best efforts to register or qualify the Exchange
       and Registrable Securities under all applicable state securities or "blue
       sky" laws of such jurisdictions as any Holder of Registrable Securities
       covered by a Registration Statement shall reasonably request in writing
       by the time the applicable Registration Statement is declared effective
       by the SEC, to cooperate with such Holders in connection with any filings
       required to be made with the National Association of Securities Dealers,
       Inc. and do any and all other acts and things which may be reasonably
       necessary or advisable to enable such Holder to consummate the
       disposition in each such jurisdiction of such Exchange and Registrable
       Securities owned by such Holder; provided, however, that the Company
       shall not be required to (i) qualify as a foreign corporation or as a
       dealer in securities in any jurisdiction where it would not otherwise be
       required to qualify but for this Section 3(d), (ii) file any general
       consent to service of process or (iii) subject itself to taxation in any
       such jurisdiction if it is not so subject;

              (e)    in the case of a Shelf Registration, notify each Holder of
       Registrable Securities, counsel for the Holders and counsel for the
       Placement Agent promptly and, if requested by any such Holder or counsel,
       confirm such advice in writing (i) when a Registration Statement has
       become effective and when any post-effective amendment thereto has been
       filed and becomes effective, (ii) of any request by the SEC or any state
       securities authority for amendments and supplements to a Registration
       Statement and Prospectus or for additional information after the
       Registration Statement has become effective, (iii) of the issuance by the
       SEC or any state securities authority of any stop order suspending the
       effectiveness of a Registration Statement or the initiation of any
       proceedings for that purpose, (iv) if, between the effective date of a
       Registration Statement and the closing of any sale of Registrable
       Securities covered thereby, the representations and warranties of the
       Company contained in any underwriting agreement, securities sales
       agreement or other similar agreement, if any, relating to the offering
       cease to be true and correct in all material respects or if the Company
       receives any notification with respect to the suspension of the
       qualification of the Registrable Securities for sale in


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       any jurisdiction or the initiation of any proceeding for such purpose,
       (v) of the happening of any event during the period a Shelf Registration
       Statement is effective which makes any statement made in such
       Registration Statement or the related Prospectus untrue in any material
       respect or which requires the making of any changes in such Registration
       Statement or Prospectus in order to make the statements therein not
       misleading and (vi) of any determination by the Company that a
       post-effective amendment to a Registration Statement would be
       appropriate;

              (f)    make every reasonable effort to obtain the withdrawal of
       any order suspending the effectiveness of a Registration Statement at the
       earliest possible moment and provide immediate notice to each Holder of
       the withdrawal of any such order;

              (g)    in the case of a Shelf Registration, furnish to each Holder
       of Registrable Securities, without charge, at least one conformed copy of
       each Registration Statement and any post-effective amendment thereto
       (without documents incorporated therein by reference or exhibits thereto,
       unless requested);

              (h)    in the case of a Shelf Registration, cooperate with the
       selling Holders of Registrable Securities to facilitate the timely
       preparation and delivery of certificates representing Registrable
       Securities to be sold and not bearing any restrictive legends and enable
       such Registrable Securities to be in such denominations (consistent with
       the provisions of the Indenture) and registered in such names as the
       selling Holders may reasonably request at least one business day prior to
       the closing of any sale of Registrable Securities;

              (i)    in the case of a Shelf Registration, upon the occurrence of
       any event contemplated by Section 3(e)(v) hereof, use their best efforts
       to prepare and file with the SEC a supplement or post-effective amendment
       to a Registration Statement or the related Prospectus or any document
       incorporated therein by reference or file any other required document so
       that, as thereafter delivered to the purchasers of the Registrable
       Securities, such Prospectus will not contain any untrue statement of a
       material fact or omit to state a material fact necessary to make the
       statements therein, in light of the circumstances under which they were
       made, not misleading. The Company agrees to notify the Holders to suspend
       use of the Prospectus as promptly as practicable after the occurrence of
       such an event, and the Holders hereby agree to suspend use of the
       Prospectus until the Company has amended or supplemented the Prospectus
       to correct such misstatement or omission;

              (j)    a reasonable time prior to the filing of any Registration
       Statement, any Prospectus, any amendment to a Registration Statement or
       amendment or supplement to a Prospectus or any document which is to be
       incorporated by reference into a Registration Statement or a Prospectus
       after the initial filing of a Registration Statement, provide copies of
       such document to the Placement Agent and its counsel (and, in the case of
       a Shelf Registration Statement, to the Holders and their counsel) and
       make such of the representatives of the Company as shall be reasonably
       requested by the Placement Agent


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       or its counsel (and, in the case of a Shelf Registration Statement, to
       the Holders or their counsel) available for discussion of such document,
       and shall not at any time file or make any amendment to the Registration
       Statement, any Prospectus or any amendment of or supplement to a
       Registration Statement or a Prospectus or any document which is to be
       incorporated by reference into a Registration Statement or a Prospectus,
       of which the Placement Agent and its counsel (and, in the case of a Shelf
       Registration Statement, the Holders and their counsel) shall not have
       previously been advised and furnished a copy or to which the Placement
       Agent or its counsel (and, in the case of a Shelf Registration Statement,
       the Holders or their counsel) shall reasonably object;

              (k)    obtain a CUSIP number for all Exchange Securities, as the
       case may be, not later than the effective date of a Registration
       Statement;

              (l)    cause the Indenture to be qualified under the Trust
       Indenture Act of 1939, as amended (the "TIA"), in connection with the
       registration of the Exchange Securities or Registrable Securities, as the
       case may be, cooperate with the Trustee and the Holders to effect such
       changes to the Indenture as may be required for the Indenture to be so
       qualified in accordance with the terms of the TIA and execute, and use
       their best efforts to cause the Trustee to execute, all documents as may
       be required to effect such changes and all other forms and documents
       required to be filed with the SEC to enable the Indenture to be so
       qualified in a timely manner;

              (m)    in the case of a Shelf Registration, make available for
       inspection by a representative of the Holders of the Registrable
       Securities, any Underwriter participating in any disposition pursuant to
       such Shelf Registration Statement, and attorneys and accountants
       designated by the Holders, at reasonable times and in a reasonable
       manner, all financial and other records, pertinent documents and
       properties of the Company, and cause the officers, directors and
       employees of the Company to supply all information reasonably requested
       by any such representative, Underwriter, attorney or accountant in
       connection with a Shelf Registration Statement;

              (n)    in the case of a Shelf Registration, use its best efforts
       to cause all Registrable Securities to be listed on any securities
       exchange or any automated quotation system on which the Securities are
       then listed if requested by the Majority Holders, to the extent such
       Registrable Securities satisfy applicable listing requirements;

              (o)    use its best efforts to cause the Exchange Securities to be
       rated or continue to be rated by two nationally recognized statistical
       rating organizations (as such term is defined in Rule 436(g)(2) under the
       1933 Act), if the Registrable Securities have been so rated;

              (p)    if reasonably requested by any Holder of Registrable
       Securities covered by a Registration Statement, (i) promptly incorporate
       in a Prospectus supplement or post-effective amendment such information
       with respect to such Holder as such Holder


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       reasonably requests to be included therein and (ii) make all required
       filings of such Prospectus supplement or such post-effective amendment as
       soon as the Company has received notification of the matters to be
       incorporated in such filing; and

              (q)    in the case of a Shelf Registration, enter into such
       customary agreements and take all such other actions in connection
       therewith (including those requested by the Holders of a majority of the
       Registrable Securities being sold) in order to expedite or facilitate the
       disposition of such Registrable Securities including, but not limited to,
       an Underwritten Offering and in such connection, (i) to the extent
       possible, make such representations and warranties to the Holders and any
       Underwriters of such Registrable Securities with respect to the business
       of the Company and its subsidiaries, the Registration Statement,
       Prospectus and documents incorporated by reference or deemed incorporated
       by reference, if any, in each case, in form, substance and scope as are
       customarily made by issuers to underwriters in underwritten offerings and
       confirm the same if and when requested, (ii) obtain opinions of counsel
       to the Company (which counsel and opinions, in form, scope and substance,
       shall be reasonably satisfactory to the Holders and such Underwriters and
       their respective counsel) addressed to each selling Holder and
       Underwriter of Registrable Securities, covering the matters customarily
       covered in opinions requested in underwritten offerings, (iii) obtain
       "comfort" letters from the independent certified public accountants of
       the Company (and, if necessary, any other certified public accountant of
       any subsidiary of the Company, or of any business acquired by the Company
       for which financial statements and financial data are or are required to
       be included in the Registration Statement) addressed to each selling
       Holder and Underwriter of Registrable Securities, such letters to be in
       customary form and covering matters of the type customarily covered in
       "comfort" letters in connection with underwritten offerings, and (iv)
       deliver such documents and certificates as may be reasonably requested by
       the Holders of a majority in principal amount of the Registrable
       Securities being sold or the Underwriters, and which are customarily
       delivered in underwritten offerings, to evidence the continued validity
       of the representations and warranties of the Company made pursuant to
       clause (i) above and to evidence compliance with any customary conditions
       contained in an underwriting agreement.

              In the case of a Shelf Registration Statement, the Company may
require each Holder of Registrable Securities to furnish to the Company such
information regarding the Holder and the proposed distribution by such Holder of
such Registrable Securities as the Company may from time to time reasonably
request in writing.

              In the case of a Shelf Registration Statement, each Holder agrees
that, upon receipt of any notice from the Company of the happening of any event
of the kind described in Section 3(e)(v) hereof, such Holder will forthwith
discontinue disposition of Registrable Securities pursuant to a Registration
Statement until such Holder's receipt of the copies of the supplemented or
amended Prospectus contemplated by Section 3(i) hereof, and, if so directed by
the Company, such Holder will deliver to the Company (at its expense) all copies
in its


<PAGE>   13

                                       12


possession, other than permanent file copies then in such Holder's possession,
of the Prospectus covering such Registrable Securities current at the time of
receipt of such notice. The Company may give any such notice only twice during
any 365 day period and any such suspensions may not exceed 30 days for each
suspension and there may not be more than two suspensions in effect during any
365-day period.

              The Holders of Registrable Securities covered by a Shelf
Registration Statement who desire to do so may sell such Registrable Securities
in an Underwritten Offering. In any such Underwritten Offering, the investment
banker or investment bankers and manager or managers (the "Underwriters") that
will administer the offering will be selected by the Majority Holders of the
Registrable Securities included in such offering.

              4.     Participation of Broker-Dealers in Exchange Offer.

              (a)    The Staff of the SEC has taken the position that any
broker-dealer that receives Exchange Securities for its own account in the
Exchange Offer in exchange for Securities that were acquired by such
broker-dealer as a result of market-making or other trading activities (a
"Participating Broker-Dealer"), may be deemed to be an "underwriter" within the
meaning of the 1933 Act and must deliver a prospectus meeting the requirements
of the 1933 Act in connection with any resale of such Exchange Securities.

              The Company understands that it is the Staff's position that if
the Prospectus contained in the Exchange Offer Registration Statement includes a
plan of distribution containing a statement to the above effect and the means by
which Participating Broker-Dealers may resell the Exchange Securities, without
naming the Participating Broker-Dealers or specifying the amount of Exchange
Securities owned by them, such Prospectus may be delivered by Participating
Broker-Dealers to satisfy their prospectus delivery obligation under the 1933
Act in connection with resales of Exchange Securities for their own accounts, so
long as the Prospectus otherwise meets the requirements of the 1933 Act.

              (b)    In light of the above, notwithstanding the other provisions
of this Agreement, the Company agrees that the provisions of this Agreement as
they relate to a Shelf Registration shall also apply to an Exchange Offer
Registration to the extent, and with such reasonable modifications thereto as
may be, reasonably requested by the Placement Agent or by one or more
Participating Broker-Dealers, in each case as provided in clause (ii) below, in
order to expedite or facilitate the disposition of any Exchange Securities by
Participating Broker-Dealers consistent with the positions of the Staff recited
in Section 4(a) above; provided that:

              (i)    the Company shall not be required to amend or supplement
       the Prospectus contained in the Exchange Offer Registration Statement, as
       would otherwise be contemplated by Section 3(i), for a period exceeding
       180 days after the last Exchange Date (as such period may be extended
       pursuant to the penultimate paragraph of Section 3 of this Agreement) and
       Participating Broker-Dealers shall not be authorized by the


<PAGE>   14

                                       13


       Company to deliver and shall not deliver such Prospectus after such
       period in connection with the resales contemplated by this Section 4; and

              (ii)   the application of the Shelf Registration procedures set
       forth in Section 3 of this Agreement to an Exchange Offer Registration,
       to the extent not required by the positions of the Staff of the SEC or
       the 1933 Act and the rules and regulations thereunder, will be in
       conformity with the reasonable request to the Company by the Placement
       Agent or with the reasonable request in writing to the Company by one or
       more broker-dealers who certify to the Placement Agent and the Company in
       writing that they anticipate that they will be Participating
       Broker-Dealers; and provided further that, in connection with such
       application of the Shelf Registration procedures set forth in Section 3
       to an Exchange Offer Registration, the Company shall be obligated (x) to
       deal only with one entity representing the Participating Broker-Dealers,
       which shall be Morgan Stanley & Co. Incorporated unless it elects not to
       act as such representative, (y) to pay the fees and expenses of only one
       counsel representing the Participating Broker-Dealers, which shall be
       counsel to the Placement Agent unless such counsel elects not to so act
       and (z) to cause to be delivered only one, if any, "comfort" letter with
       respect to the Prospectus in the form existing on the last Exchange Date
       and with respect to each subsequent amendment or supplement, if any,
       effected during the period specified in clause (i) above.

              (c)    The Placement Agent shall have no liability to the Company
or any Holder with respect to any request that it may make pursuant to Section
4(b) above.

              5.     Indemnification and Contribution.

              (a)    The Company agrees to indemnify and hold harmless the
Placement Agent, each Holder and each person, if any, who controls the Placement
Agent or any Holder within the meaning of either Section 15 of the 1933 Act or
Section 20 of the 1934 Act, or is under common control with, or is controlled
by, the Placement Agent or any Holder, from and against all losses, claims,
damages and liabilities (including, without limitation, any legal or other
expenses reasonably incurred by the Placement Agent, any Holder or any such
controlling or affiliated person in connection with defending or investigating
any such action or claim) caused by any untrue statement or alleged untrue
statement of a material fact contained in any Registration Statement (or any
amendment thereto) pursuant to which Exchange Securities or Registrable
Securities were registered under the 1933 Act, including all documents
incorporated therein by reference, or caused by any omission or alleged omission
to state therein a material fact required to be stated therein or necessary to
make the statements therein not misleading, or caused by any untrue statement or
alleged untrue statement of a material fact contained in any Prospectus (as
amended or supplemented if the Company shall have furnished any amendments or
supplements thereto), or caused by any omission or alleged omission to state
therein a material fact necessary to make the statements therein in light of the
circumstances under which they were made not misleading, except insofar as such
losses, claims, damages or liabilities are


<PAGE>   15

                                       14


caused by any such untrue statement or omission or alleged untrue statement or
omission based upon information relating to the Placement Agent or any Holder
furnished to the Company in writing by the Placement Agent or any Holder
expressly for use therein; provided, however, that the foregoing indemnity shall
not inure to the benefit of any of the foregoing parties from whom the person
asserting any such losses, claims, damages or liabilities purchased the
Securities or Exchange Securities, or any person controlling any of the
foregoing parties, if such party failed to send or give a copy of the Prospectus
(as amended or supplemented if the Company shall have furnished such amendments
or supplements thereto) to such person within the time required by the
Securities Act (and if so required), and if the Prospectus (as so amended or
supplemented) would have cured the defect giving rise to such losses, claims,
damages or liabilities. In connection with any Underwritten Offering permitted
by Section 3, the Company will also indemnify the Underwriters, if any, selling
brokers, dealers and similar securities industry professionals participating in
the distribution, their officers and directors and each Person who controls such
Persons (within the meaning of the Securities Act and the Exchange Act) to the
same extent as provided above with respect to the indemnification of the
Holders, if requested in connection with any Registration Statement.

              (b)    Each Holder agrees, severally and not jointly, to indemnify
and hold harmless the Company, the Placement Agent and the other selling
Holders, and each of their respective directors, officers who sign the
Registration Statement and each Person, if any, who controls the Company, the
Placement Agent and any other selling Holder within the meaning of either
Section 15 of the 1933 Act or Section 20 of the 1934 Act to the same extent as
the foregoing indemnity from the Company to the Placement Agent and the Holders,
but only with reference to information relating to such Holder furnished to the
Company in writing by such Holder expressly for use in any Registration
Statement (or any amendment thereto) or any Prospectus (or any amendment or
supplement thereto).

              (c)    In case any proceeding (including any governmental
investigation) shall be instituted involving any person in respect of which
indemnity may be sought pursuant to either paragraph (a) or paragraph (b) above,
such person (the "indemnified party") shall promptly notify the person against
whom such indemnity may be sought (the "indemnifying party") in writing and the
indemnifying party, upon request of the indemnified party, shall retain counsel
reasonably satisfactory to the indemnified party to represent the indemnified
party and any others the indemnifying party may designate in such proceeding and
shall pay the fees and disbursements of such counsel related to such proceeding.
In any such proceeding, any indemnified party shall have the right to retain its
own counsel, but the fees and expenses of such counsel shall be at the expense
of such indemnified party unless (i) the indemnifying party and the indemnified
party shall have mutually agreed to the retention of such counsel or (ii) the
named parties to any such proceeding (including any impleaded parties) include
both the indemnifying party and the indemnified party and representation of both
parties by the same counsel would be inappropriate due to actual or potential
differing interests between them. It is understood that the indemnifying party
shall not, in connection with any proceeding or related proceedings in the same
jurisdiction, be liable for (a) the fees and expenses of more than one


<PAGE>   16

                                       15


separate firm (in addition to any local counsel) for the Placement Agent and for
all Holders and all persons, if any, who control the Placement Agent and any
Holders within the meaning of either Section 15 of the 1933 Act or Section 20 of
the 1934 Act, unless the Placement Agent determines in its sole discretion that
such a joint representation of the Placement Agent and the Holders would involve
differences or potential differences that render such joint representation
inadvisable, in which case the indemnifying party shall not be responsible for
(i) the fees and expenses of more than one separate firm (in addition to any
local counsel) for all Holders and all persons, if any, who control any Holders
within the meaning of either Section 15 of the 1933 Act or Section 20 of the
1934 Act and (ii) the fees and expenses of more than one separate firm (in
addition to any local counsel) for the Placement Agent and all persons, if any,
who control the Placement Agent within the meaning of either Section 15 of the
1933 Act or Section 20 of the 1934 Act, and (b) the fees and expenses of more
than one separate firm (in addition to any local counsel) for the Company, its
directors, its officers who sign the Registration Statement and each person, if
any, who controls the Company within the meaning of either such Section, and
that all such fees and expenses shall be reimbursed as they are incurred. In
such case involving the Placement Agent and persons who control the Placement
Agent, such firm shall be designated in writing by the Placement Agent. In such
case involving the Holders and such persons who control Holders, such firm shall
be designated in writing by the Majority Holders. In all other cases, such firm
shall be designated by the Company. The indemnifying party shall not be liable
for any settlement of any proceeding effected without its written consent but,
if settled with such consent or if there be a final judgment for the plaintiff,
the indemnifying party agrees to indemnify the indemnified party from and
against any loss or liability by reason of such settlement or judgment.
Notwithstanding the foregoing sentence, if at any time an indemnified party
shall have requested an indemnifying party to reimburse the indemnified party
for fees and expenses of counsel as contemplated by the second and third
sentences of this paragraph, the indemnifying party agrees that it shall be
liable for any settlement of any proceeding effected without its written consent
if (i) such settlement is entered into more than 30 days after receipt by such
indemnifying party of the aforesaid request and (ii) such indemnifying party
shall not have reimbursed the indemnified party for such fees and expenses of
counsel in accordance with such request prior to the date of such settlement. No
indemnifying party shall, without the prior written consent of the indemnified
party, effect any settlement of any pending or threatened proceeding in respect
of which such indemnified party is or could have been a party and indemnity
could have been sought hereunder by such indemnified party, unless such
settlement includes an unconditional release of such indemnified party from all
liability on claims that are the subject matter of such proceeding.

              (d)    If the indemnification provided for in paragraph (a) or
paragraph (b) of this Section 5 is unavailable to an indemnified party or
insufficient in respect of any losses, claims, damages or liabilities, then each
indemnifying party under such paragraph, in lieu of indemnifying such
indemnified party thereunder, shall contribute to the amount paid or payable by
such indemnified party as a result of such losses, claims, damages or
liabilities in such proportion as is appropriate to reflect the relative fault
of the indemnifying party or parties on the one hand and of the indemnified
party or parties on the other hand in connection with the


<PAGE>   17

                                       16


statements or omissions that resulted in such losses, claims, damages or
liabilities, as well as any other relevant equitable considerations. The
relative fault of the Company and the Holders shall be determined by reference
to, among other things, whether the untrue or alleged untrue statement of a
material fact or the omission or alleged omission to state a material fact
relates to information supplied by the Company or by the Holders and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission. The Holders' respective
obligations to contribute pursuant to this Section 5(d) are several in
proportion to the respective number of Registrable Securities of such Holder
that were registered pursuant to a Registration Statement.

              (e)    The Company and each Holder agree that it would not be just
or equitable if contribution pursuant to this Section 5 were determined by pro
rata allocation or by any other method of allocation that does not take account
of the equitable considerations referred to in paragraph (d) above. The amount
paid or payable by an indemnified party as a result of the losses, claims,
damages and liabilities referred to in paragraph (d) above shall be deemed to
include, subject to the limitations set forth above, any legal or other expenses
reasonably incurred by such indemnified party in connection with investigating
or defending any such action or claim. Notwithstanding the provisions of this
Section 5, no Holder shall be required to indemnify or contribute any amount in
excess of the amount by which the total price at which Registrable Securities
were sold by such Holder exceeds the amount of any damages that such Holder has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the 1933 Act) shall be
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation. The remedies provided for in this Section 5 are not exclusive
and shall not limit any rights or remedies which may otherwise be available to
any indemnified party at law or in equity.

              The indemnity and contribution provisions contained in this
Section 5 shall remain operative and in full force and effect regardless of (i)
any termination of this Agreement, (ii) any investigation made by or on behalf
of the Placement Agent, any Holder or any person controlling the Placement Agent
or any Holder, or by or on behalf of the Company, its officers or directors or
any person controlling the Company, (iii) acceptance of any of the Exchange
Securities and (iv) any sale of Registrable Securities pursuant to a Shelf
Registration Statement.

              6.     Miscellaneous.

              (a)    No Inconsistent Agreements. The Company has not entered
into, and on or after the date of this Agreement will not enter into, any
agreement which is inconsistent with the rights granted to the Holders of
Registrable Securities in this Agreement or otherwise conflicts with the
provisions hereof. The rights granted to the Holders hereunder do not in any way
conflict with and are not inconsistent with the rights granted to the holders of
the Company's other issued and outstanding securities under any such agreements.


<PAGE>   18

                                       17


              (b)    Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given unless the Company has obtained the written consent of Holders
of at least a majority in aggregate principal amount of the outstanding
Registrable Securities affected by such amendment, modification, supplement,
waiver or consent; provided, however, that no amendment, modification,
supplement, waiver or consents to any departure from the provisions of Section 5
hereof shall be effective as against any Holder of Registrable Securities unless
consented to in writing by such Holder.

              (c)    Notices. All notices and other communications provided for
or permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, telex, telecopier, or any courier guaranteeing overnight
delivery (i) if to a Holder, at the most current address given by such Holder to
the Company by means of a notice given in accordance with the provisions of this
Section 6(c), which address initially is, with respect to the Placement Agent,
the address set forth in the Placement Agreement; and (ii) if to the Company,
initially at the Company's address set forth in the Placement Agreement and
thereafter at such other address, notice of which is given in accordance with
the provisions of this Section 6(c).

              All such notices and communications shall be deemed to have been
duly given: at the time delivered by hand, if personally delivered; five
business days after being deposited in the mail, postage prepaid, if mailed;
when answered back, if telexed; when receipt is acknowledged, if telecopied; and
on the second succeeding business day if timely delivered to an air courier
guaranteeing overnight delivery.

              Copies of all such notices, demands, or other communications shall
be concurrently delivered by the person giving the same to the Trustee, at the
address specified in the Indenture.

              (d)    Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors, assigns and transferees of each
of the parties, including, without limitation and without the need for an
express assignment, subsequent Holders; provided that nothing herein shall be
deemed to permit any assignment, transfer or other disposition of Registrable
Securities in violation of the terms of the Placement Agreement. If any
transferee of any Holder shall acquire Registrable Securities, in any manner,
whether by operation of law or otherwise, such Registrable Securities shall be
held subject to all of the terms of this Agreement, and by taking and holding
such Registrable Securities such person shall be conclusively deemed to have
agreed to be bound by and to perform all of the terms and provisions of this
Agreement and such person shall be entitled to receive the benefits hereof. The
Placement Agent (in its capacity as Placement Agent) shall have no liability or
obligation to the Company with respect to any failure by a Holder to comply
with, or any breach by any Holder of, any of the obligations of such Holder
under this Agreement.


<PAGE>   19


                                       18


              (e)    Third Party Beneficiary. The Holders shall be third party
beneficiaries to the agreements made hereunder between the Company, on the one
hand, and the Placement Agent, on the other hand, and shall have the right to
enforce such agreements directly to the extent they deems such enforcement
necessary or advisable to protect their rights or the rights of Holders
hereunder.

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

              (g)    Headings. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

              (h)    Governing Law. This Agreement shall be governed by the laws
of the State of New York.

              (i)    Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.


<PAGE>   20


              IN WITNESS WHEREOF, the parties have executed this Agreement as of
the date first written above.

                                     IMPSAT FIBER NETWORKS, INC.

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


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


Confirmed and accepted as of
 the date first above written:

MORGAN STANLEY & CO. INCORPORATED

By: Morgan Stanley & Co. Incorporated

By:
   --------------------------------------
   Name:  John D. Tyree
   Title: Vice President