<PAGE>
                              AMENDED AND RESTATED
                               SECURITY AGREEMENT


                  THIS AMENDED AND RESTATED SECURITY AGREEMENT (this "Security
Agreement") dated as of November 27, 2001, is made and entered into by and
between Patricio E. Northland, an individual (the "Pledgor"), and AT&T Latin
America Corp., a Delaware corporation (the "Company").

                                    RECITALS

                  WHEREAS, the Pledgor and the Company previously entered into a
Security Agreement dated as of January 26, 2001 (the Original Security
Agreement") in connection with a Promissory Note executed by the Pledgor in
favor of the Company dated as of January 26, 2001 (the "Original Note"); and

                  WHEREAS, the Pledgor has executed an Amended and Restated
Promissory Note (the "Amended Note") which cancels and replaces the Original
Note; and

                  WHEREAS, the Pledgor wishes to grant security and assurance to
the Company in order to secure the payment of the Amended Note, and to that
effect the Pledgor wishes to pledge to the Company certain collateral.

                                    AGREEMENT

                  NOW, THEREFORE, in consideration of the foregoing and for
other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the parties hereto agree as follows:

                  1. CANCELLATION OF ORIGINAL SECURITY AGREEMENT. The Original
Security Agreement is hereby canceled and superseded in its entirety and
replaced by this Security Agreement.

                  2. DEFINITIONS. All capitalized terms used in this Security
Agreement and not otherwise defined shall have the meanings given to them in the
Employment Agreement, dated as of November 1, 1999, among Pledgor, the Company
and Frantis, Inc. (formerly known as FirstCom Corporation).

                  3. PLEDGE OF SECURITY. Pledgor hereby pledges and assigns to
the Company, and hereby grants to the Company a security interest in, all of the
Pledgor's right, title and interest in and to the 800,000 shares of Class A
common stock of the Company (the "Pledged Stock") that were received by
Executive in connection with the merger of FirstCom Corporation into a
wholly-owned subsidiary of the Company in exchange for shares of FirstCom common
stock purchased by Executive pursuant to the Restricted Stock Purchase



<PAGE>

Agreement, dated as of October 31, 1999, between the Pledgor and FirstCom
Corporation, and the certificates representing such shares, and all dividends,
cash, instruments, chattel paper and other rights, property, products or
proceeds from time to time received, receivable or otherwise distributed in
respect of or in exchange for any or all of such shares (the "Pledged
Collateral").

                  4. SECURITY FOR OBLIGATIONS. This Security Agreement secures,
and all of the Pledged Collateral is collateral security for, the prompt payment
or performance in full when due, of all obligations of every nature of the
Pledgor under the Amended Note (including, without limitation, interest that but
for the filing of a petition in bankruptcy with respect to the Pledgor, would
accrue on such obligations), and all obligations of every nature of the Pledgor
now or hereafter existing under this Security Agreement.

                  5. DELIVERY OF PLEDGED COLLATERAL. The Company acknowledges
that Pledgor previously delivered all certificates or instruments representing
or evidencing the Pledged Collateral to the Company and such certificates or
instruments are held by the Company.

                  6. REPRESENTATIONS, WARRANTIES AND COVENANTS. The Pledgor
hereby represents, warrants and/or covenants as follows:

                  (a) This Security Agreement is the legally valid and binding
         obligation of the Pledgor, enforceable against him in accordance with
         its terms, except as enforcement may be limited by bankruptcy,
         insolvency, reorganization, moratorium or similar laws or equitable
         principles relating to or limiting creditors' rights generally.

                  (b) The Pledgor's place of residence is currently Miami,
         Florida.

                  7. ADMINISTRATION OF SECURITY. The following provisions shall
govern the administration of the Pledged Collateral:

                  (a) Until the Pledgor has fully paid all outstanding principal
         and other amounts accruing under the Amended Note, (i) the Company
         shall apply all dividends payable to the Pledgor with respect to all
         Pledged Collateral held by the Pledgor first to accrued interest, then
         to other amounts owing and then to principal under the Amended Note,
         and (ii) the Pledgor shall apply all proceeds of the sale of any or all
         of the Pledged Collateral as prescribed in Section 6 of the Amended
         Note.

                  (b) The Company will work in good faith with the Pledgor to
         the Pledged Collateral if and to the extent that the Pledgor proposes
         to sell or otherwise dispose of such Pledged Collateral in a manner
         that will facilitate such proposed sale or other disposition while
         protecting the legitimate interests of the Company.

                  (c) The Pledgor shall immediately upon request by the Company
         and in confirmation of the security interests hereby created, execute
         and deliver to the Company such further instruments, deeds, transfers,
         assurances and agreements, in form and substance as the Company



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<PAGE>

         requests, including any financing statement and amendments thereto, or
         any other documents, as required under New York law and any other
         applicable law to protect the security interests created hereunder.

                  8. EVENTS OF DEFAULT. The occurrence of any of the following
events will constitute an "Event of Default":

                  (a) Failure of the Pledgor to pay any principal, interest or
         other amount due under the Amended Note when due, whether at stated
         maturity, by acceleration, demand or otherwise; or

                  (b) Failure of the Pledgor to perform or observe any term,
         covenant or agreement as required pursuant to this Security Agreement
         or the Amended Note; or

                  (c) Death of the Pledgor; or

                  (d) A court having jurisdiction enters a decree or order for
         relief in respect of the Pledgor in an involuntary case under the
         United States Code entitled "Bankruptcy" (as now and hereinafter in
         effect, or any successor thereto, the "Bankruptcy Code") or any
         applicable bankruptcy, insolvency or other similar law now or hereafter
         in effect, which decree or order is not stayed; or any other similar
         relief is granted under any applicable federal or state law; or an
         involuntary case is commenced against the Pledgor under any applicable
         bankruptcy, insolvency or other similar law now or hereafter in effect;
         or a decree or order of a court having jurisdiction for the appointment
         of a receiver, liquidator, sequestrator, trustee, custodian or other
         officer having similar powers over the Pledgor or over all or a
         substantial part of his property is entered; or the involuntary
         appointment of an interim receiver, trustee or other custodian of the
         Pledgor for all or a substantial part of his property occurs; or a
         warrant of attachment, execution or similar process is issued against
         any substantial part of the property of the Pledgor, and, in the case
         of any event described in this clause (d), such event continues for 60
         days unless dismissed, bonded or discharged; or

                  (e) An order for relief is entered with respect to the
         Pledgor, or the Pledgor commences a voluntary case under the Bankruptcy
         Code or any applicable bankruptcy, insolvency or other similar law now
         or hereafter in effect, or consents to the entry of an order for relief
         in an involuntary case, or to the conversion of an involuntary case to
         a voluntary case, under any such law, or consents to the appointment of
         or taking possession by a receiver, trustee or other custodian for all
         or a substantial part of his property; or the Pledgor makes an
         assignment for the benefit of creditors; or the Pledgor is unable or
         fails, or admits in writing his inability, to pay his debts as such
         debts become due.

                  9. REMEDIES IN CASE OF AN EVENT OF DEFAULT.

                  (a) If an Event of Default occurs and is continuing, the
         Company shall have all of the remedies of a secured party under New
         York law, and, without limiting the foregoing, shall have the right,
         subject to any necessary regulatory approvals, to sell, assign and



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<PAGE>

         deliver the whole or, from time to time, any part of the Pledged
         Collateral, or any interest in any part thereof. Notwithstanding the
         foregoing, the Company may elect to retain such shares rather than
         selling them to a third party, in which case the Company shall be
         deemed to have purchased such shares for a per share price equal to the
         closing price of a share of such Common Stock, as reported on the
         national exchange market on which such Common Stock is traded, on the
         date the related Event of Default occurs (the "Default Date Value"), or
         if the Company sells such shares to a third party, the per share
         proceeds of any such sale shall be deemed, for purposes of this
         Security Agreement, to be equal to the greater of the net sale proceeds
         per share and the Default Date Value.

                  (b) Neither failure nor delay on the part of the Company to
         exercise any right, remedy, power or privilege provided for herein or
         by statute or at law or in equity shall operate as a waiver thereof,
         nor shall any single or partial exercise of any such right, remedy,
         power or privilege preclude any other or further exercise thereof or
         the exercise of any other right, remedy, power or privilege.

                  10. TERMINATION OF SECURITY INTEREST. The Company agrees that
the security interests and all other rights granted to the Company hereunder
with respect to the Pledged Collateral shall terminate promptly upon the earlier
of (i) the full and complete satisfaction of all of the Pledgor's obligations
under the Amended Note, (ii) the sale of the Pledged Collateral, provided that
the Pledgor makes arrangements reasonably satisfactory to the Company to apply
the net after tax proceeds of any such sale to repay the Loan to the extent
prescribed in the Amended Note, or (iii) forgiveness of the Amended Note
pursuant to Section 8 of the Amended Note.

                  11. ASSIGNMENTS AND TRANSFERS. Except as explicitly permitted
pursuant to the terms of this Security Agreement, the Pledgor will not sell,
assign, transfer or otherwise dispose of, or grant any option with respect to,
or mortgage, pledge or otherwise encumber the Pledged Collateral or any interest
therein.

                  12. COMPLIANCE WITH REGULATIONS G, T, U AND X. The Pledgor and
the Company hereby agree that no part of the proceeds of the Loan will be used
by the Pledgor to purchase or carry any margin stock within the meaning of
Regulations G, T, U and X of the Board of Governors of the Federal Reserve
System. The Pledgor has not taken and will not knowingly take any action that
would cause this Security Agreement or the Amended Note to violate any
regulation of the Board of Governors of the Federal Reserve System or to violate
the Securities Exchange Act of 1934, in each case as in effect now or as the
same may hereinafter be in effect.

                  13. ATTORNEY-IN-FACT. The Company or its successors are hereby
appointed the attorney-in-fact of the Pledgor for the purpose of carrying out
the provisions of this Security Agreement and taking any action and executing
any instrument that the Company reasonably may deem necessary or advisable to
accomplish the purposes hereof at any time after the occurrence of an Event of
Default. This appointment as attorney-in-fact is irrevocable and coupled with an
interest.

                  14. EXPENSES. The Pledgor shall pay to the Company upon demand
the amount of any and all costs and expenses, including the reasonable fees and



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<PAGE>

expenses of its counsel and of any experts and agents, that the Company may
incur in connection with (i) the exercise or enforcement of any of the rights of
the Company hereunder, or (ii) the failure by the Pledgor to perform or observe
any of the provisions hereof.

                  15. NOTICES. All notices or other communications required or
permitted to be given hereunder shall be delivered in the same manner as set
forth in the Employment Agreement.

                  16. REASONABLE CARE. The Company shall be deemed to have
exercised reasonable care in the custody and preservation of the Pledged
Collateral in its possession if the Pledged Collateral is accorded treatment
substantially equal to that which the Company accords its own property. Except
to the extent required by law, the Company shall have no responsibility for (i)
asserting or taking action with respect to calls, conversion, exchanges,
maturities, tenders or other matters relative to any Pledged Collateral, whether
or not the Company has or is deemed to have knowledge of such matters, or (ii)
taking any necessary steps to preserve rights against any parties with respect
to the Pledged Collateral.

                  17. MISCELLANEOUS.

                  (a) The provisions of this Security Agreement shall inure to
         the benefit of the successors and assigns of the Company. The Pledgor
         shall not assign or transfer any of his benefits or obligations arising
         under this Security Agreement.

                  (b) If any provision of this Security Agreement is held to be
         invalid, illegal or unenforceable, the validity, legality and
         enforceability of the remaining provisions shall not in any way be
         affected or impaired thereby, and the parties shall negotiate in good
         faith to replace that provision with a new, valid and enforceable
         provision reflecting the same allocation of burdens and benefits as the
         stricken provision.

                  (c) This Security Agreement embodies the complete agreement
         and understanding between the parties hereto with respect to the
         subject matter hereof and supersedes and preempts any prior
         understandings, agreements or representations by or between the
         parties, written or oral, that may have related to the subject matter
         hereof in any way.

                  (d) The headings in this Security Agreement are for
         convenience only and shall not affect the construction hereof.

                  (e) The Pledgor and the Company agree that there shall be no
         interpretation of the terms of this Security Agreement against the
         Company because the Company drafted this Security Agreement.

                  (f) THIS SECURITY AGREEMENT SHALL BE GOVERNED BY, AND
         INTERPRETED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF NEW
         YORK.




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                  (g) This Security Agreement may be amended only in a writing
         designated as an amendment and signed by the Pledgor and the Company.

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

                                      /s/ PATRICIO E. NORTHLAND
                                      ------------------------------------
                                      PATRICIO E. NORTHLAND





                                      AT&T LATIN AMERICA CORP.



                                      By: /s/ Marie Santana
                                         --------------------------------

                                      Title: Vice President, Human Resources
                                            --------------------------------



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