<PAGE>   1
                                                                    EXHIBIT 10.4


                         SECURED NOTE PURCHASE AGREEMENT

                                  BY AND AMONG


                                  VESPER S.A.,


                          NORTEL NETWORKS CORPORATION,
                              AS INITIAL PURCHASER,


                   THE BANKS AND OTHER ENTITIES LISTED HEREIN,
                                 AS PURCHASERS,


                               ABN AMRO BANK N.V.,
                            AS ADMINISTRATIVE AGENT,


                                       AND


                          NORTEL NETWORKS CORPORATION,
                                  INDIVIDUALLY





                             AS OF DECEMBER 13, 1999

                                  $700,000,000


Confidential Treatment Requested. Confidential portions of this document have
been omitted and filed separately with the Securities and Exchange Commission.
<PAGE>   2


                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                        Page

<S>                                                                                                     <C>
ARTICLE I DEFINITIONS AND RELATED MATTERS...............................................................   2
         Section 1.1   Defined Terms Generally .........................................................   2
         Section 1.2   Definitions .....................................................................   2
         Section 1.3   Related Matters .................................................................  11
         Section 1.4   Determinations ..................................................................  11

ARTICLE II PURCHASE OF NOTES ...........................................................................  11
         Section 2.1   Notes ...........................................................................  11
                 (a)   Notes Generally .................................................................  11
                 (b)   Types of Notes; Minimum Amounts; Frequency of Issuances .........................  11
                 (c)   Notice of Issuance ..............................................................  12
                 (d)   Issuance ........................................................................  13
         Section 2.2   Use of Proceeds .................................................................  13
         Section 2.3   Interest; Interest Periods; Continuation/Conversion  ............................  14
                 (a)   Interest Rate and Payment .......................................................  14
                 (b)   Interest Periods and Minimum Amounts ............................................  15
                 (c)   Continuation/Conversion .........................................................  15
                 (d)   Computations ....................................................................  16
                 (e)   Maximum Lawful Rate of Interest .................................................  17
         Section 2.4   Fees ............................................................................  17
                 (a)   Fees ............................................................................  17
                 (b)   Fees Non-Refundable .............................................................  17
         Section 2.5   Increase, Termination and Reduction of Commitments ..............................  17
         Section 2.6   Repurchase ......................................................................  20
                 (a)   Mandatory Repurchase ............................................................  20
                 (b)   Excess Principal Amount Repurchase ..............................................  20
                 (c)   Mandatory Partial Repurchase ....................................................  20
                 (d)   Voluntary Repurchase ............................................................  21
                 (e)   Repurchase Generally ............................................................  22
                 (f)   Maturity ........................................................................  22
         Section 2.7   Conversion of Nortel Notes in Exchange Debt .....................................  22
         Section 2.8   Manner of Payment ...............................................................  22
                 (a)   Payment Generally ...............................................................  22
                 (b)   Indemnification by the Company ..................................................  23
                 (c)   Payment by the Company or any Designated Repurchaser ............................  23
                 (d)   Date of Payment .................................................................  23
                 (e)   Payments Set Aside ..............................................................  24
         Section 2.9   Pro Rata Treatment ..............................................................  24
         Section 2.10  Mandatory Suspension and Conversion of Euro-Dollar Rate Notes ...................  25
         Section 2.11  Regulatory Changes ..............................................................  26
                 (a)   Increased Costs .................................................................  26
                 (b)   Capital Costs ...................................................................  26
         Section 2.12  Taxes ...........................................................................  27
</TABLE>


                             Note Purchase Agreement
                                        i

<PAGE>   3

<TABLE>
<CAPTION>
                                                                                                        Page

<S>                                                                                                     <C>
         Section 2.13  Compensation for Funding Losses .................................................  28
         Section 2.14  Certificates Regarding Yield Protection, Etc. ...................................  29
         Section 2.15  Applicable Purchasing Office; Discretion of Purchasers as to Manner of
                 Funding ...............................................................................  29
         Section 2.16  No Set Off Regarding Supply Agreement ...........................................  29

ARTICLE III CONDITIONS TO ISSUANCE .....................................................................  30
         Section 3.1   Closing Conditions ..............................................................  30
                 (a)   Common Terms Agreement ..........................................................  30
                 (b)   Fees and Expenses Paid ..........................................................  30
                 (c)   General .........................................................................  30
         Section 3.2   Conditions Precedent to Each Issuance ...........................................  31
                 (a)   Common Terms Agreement ..........................................................  31
                 (b)   Notice of Issuance ..............................................................  31
                 (c)   Delivery of Notes ...............................................................  31
                 (d)   Payment of Front End Fees .......................................................  31
                 (e)   Issuances Prior to Completed Non-Recourse Assignment - [***] ....................  31
                 (f)   Issuances for Interest Payments Prior to Non-Recourse Assignment ................  31
                 (g)   Satisfaction of Conditions ......................................................  32

ARTICLE IV REPRESENTATIONS AND WARRANTIES ..............................................................  32

ARTICLE V COVENANTS OF THE COMPANY .....................................................................  32
         Section 5.1   Common Terms Agreement ..........................................................  32
         Section 5.2   Syndication Efforts .............................................................  32
         Section 5.3   Certain Regulatory Restrictions .................................................  33

ARTICLE VI EVENTS OF DEFAULT ...........................................................................  34
         Section 6.1   Events of Default ...............................................................  34
         Section 6.2   Remedies ........................................................................  34

ARTICLE VII THE ADMINISTRATIVE AGENT, THE PROCEEDS COLLATERAL
    AGENT, THE PURCHASERS AND CO-AGENTS ................................................................  34
         Section 7.1   Authorization and Action ........................................................  34
         Section 7.2   Exculpation; Administrative Agents Reliance; Etc.  ..............................  35
         Section 7.3   Administrative Agent and Affiliates .............................................  36
         Section 7.4   Purchaser Credit Decision; Acknowledgment of Use of Proceeds Benefiting
                 Nortel ................................................................................  36
         Section 7.5   Indemnification .................................................................  37
         Section 7.6   Successor Administrative Agent ..................................................  37
         Section 7.7   Purchaser Parties ...............................................................  37
         Section 7.8   Collateral and Guaranty Matters .................................................  38
         Section 7.9   Payments; Availability of Funds; Certain Notices ................................  40
         Section 7.10  Obligations of Purchaser Parties Several; Enforcement by the
                 Administrative Agent ..................................................................  41
         Section 7.11  Co-Agents .......................................................................  42
         Section 7.12  Global Note .....................................................................  42
</TABLE>

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                             Note Purchase Agreement
                                       ii
<PAGE>   4



<TABLE>
<CAPTION>
                                                                                                        Page

<S>                                                                                                     <C>

         Section 7.13  Paying Agency Agreement .........................................................  43

ARTICLE VIII MISCELLANEOUS .............................................................................  44
         Section 8.1   Expenses ........................................................................  44
         Section 8.2   Indemnity .......................................................................  45
         Section 8.3   Waivers; Amendments in Writing ..................................................  45
         Section 8.4   Cumulative Remedies; Failure or Delay ...........................................  46
         Section 8.5   Notices, Etc. ...................................................................  47
         Section 8.6   Successors and Assigns; Etc. ....................................................  47
         Section 8.7   Confidentiality .................................................................  49
         Section 8.8   Governing Law ...................................................................  50
         Section 8.9   Choice of Forum .................................................................  50
         Section 8.10  Currency Equivalents; Judgment Currency .........................................  51
         Section 8.11  Setoff ..........................................................................  51
         Section 8.12  Nature of Vesper Cayman SPV's Obligations .......................................  52
         Section 8.13  Headings ........................................................................  52
         Section 8.14  Severability ....................................................................  52
         Section 8.15  Survival of Agreements, Representations and Warranties ..........................  52
         Section 8.16  Execution in Counterparts .......................................................  52
         Section 8.17  Complete Agreement; Third-Party Beneficiaries ...................................  53
         Section 8.18  No Fiduciary Duties or Partnership; Limitation of Liability, Etc. ...............  53
         Section 8.19  Securities Law Matters ..........................................................  53
                 (a)   Nature of Notes .................................................................  53
                 (b)   Certain Representations and Covenants ...........................................  54
         Section 8.20  Waiver of Immunity ..............................................................  55
         Section 8.21  English Language ................................................................  55
         Section 8.22  WAIVER OF TRIAL BY JURY .........................................................  55
</TABLE>


                             Note Purchase Agreement
                                      iii

<PAGE>   5



EXHIBITS

Exhibit A           Form of Note
Exhibit B-l         Form of Notice of Issuance
Exhibit B-2         Form of Notice of Responsible Officers
Exhibit C           Form of Proceeds Account Pledge Agreement
Exhibit D           Form of Notice of Continuation/Conversion
Exhibit E           Form of Commitment Increase Agreement
Exhibit F           Form of Cancellation Certificate
Exhibit G-l         Form of Non-Recourse Assignment and Acceptance
Exhibit G-2         Form of Recourse Assignment and Acceptance


SCHEDULES

Schedule 1.1(a)      Commitments
Schedule 1.1(b)      Purchaser Information


                             Note Purchase Agreement
                                        iv


<PAGE>   6


                         SECURED NOTE PURCHASE AGREEMENT


     SECURED NOTE PURCHASE AGREEMENT, dated as of December 13, 1999 (as amended
from time to time, the "Agreement"), by and among VESPER S.A., a sociedade
anonima organized under the laws of Brazil (the "Company"); NORTEL NETWORKS
CORPORATION ("Nortel"), as initial Purchaser (as defined below); the banks and
other entities that either now or in the future are parties hereto as
Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent and
bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor in
such capacity is referred to herein as the "Administrative Agent"); and NORTEL,
individually. The Purchasers (including Nortel, to the extent provided herein),
the Administrative Agent, LASALLE BANK NATIONAL ASSOCIATION, as collateral agent
and common administrative agent under the Common Terms Agreement referred to
below (in such capacity, together with any successor in such capacity, the
"Collateral Agent"), the Proceeds Collateral Agent (defined below) and Nortel,
until the Nortel Release Date, are collectively referred to herein as the
"Purchaser Parties" and each individually as a "Purchaser Party".

                                    RECITALS

     A. The Company desires to issue notes to finance, among other things, the
purchase price of telecommunications equipment and services to be supplied by
Nortel pursuant to the Nortel Supply Agreement in connection with the initial
buildout, ownership and operation of a switched fixed telephony network covering
the 51 cities with populations greater than 200,000 in Region 1 of Brazil, as
designated by the Instrument of Authorization for Operation of a Switched Fixed
Telephone Service for the mode LOCAL and the Instrument of Authorization for
Operation of a Switched Fixed Telephone Service for the mode NATIONAL LONG
DISTANCE OF INTRA-REGIONAL SCOPE, each as entered into by and between the
Agencia Nacional de Telecomunicacoes (National Telecommunications Agency) and
the Company, under its prior name "Canbra Telefonica S.A.," on February 4, 1999
(as such instruments may be amended, and including the Data Licenses
(collectively, the "Project"));

     B. Nortel, as Initial Purchaser, has agreed to purchase such notes on the
terms and conditions set forth in this Agreement;

     C. In order to induce certain institutional note purchasers to assume the
rights and obligations of Nortel under this Agreement and to purchase Notes
outstanding or to be issued under this Agreement, [***]

     D. To induce the Initial Purchaser and the other Purchasers to provide
financing for the Project, the Company is, among other things, entering into (1)
this Agreement, (2) the Common

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                        1


<PAGE>   7



Terms Agreement (as defined below), (3) each of the Collateral Documents and (4)
each of the Supply Agreements.

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
herein contained, the parties hereto hereby agree as follows:


                                    ARTICLE I

                         DEFINITIONS AND RELATED MATTERS

     SECTION 1.1 DEFINED TERMS GENERALLY. All capitalized terms used but not
otherwise defined herein shall have the meanings assigned to such terms in the
Common Terms Agreement (as defined below).

     SECTION 1.2 DEFINITIONS. The following terms with initial capital letters
have the following meanings:

             "ABN AMRO" is defined in the Preamble.

             "ADDITIONAL COMMITMENT" is defined in Section 2.5(a).

             "ADJUSTED EURO-DOLLAR RATE" means, with respect to any day during
any Interest Period, a rate per annum (rounded upwards, if necessary, to the
next higher 1/100 of 1%) equal to (i) the applicable London Interbank Offered
Rate for such Interest Period, divided by (ii) 1.00 minus the Euro-Dollar
Reserve Requirement for such day (expressed as a decimal).

             "ADMINISTRATIVE AGENT" is defined in the Preamble.

             "ADMINISTRATIVE AGENT'S ACCOUNT" means the account of the
Administrative Agent identified as such in Schedule 1.1(b), or such other
account as the Administrative Agent may hereafter designate by notice to the
Company, the Paying Agent and each other Purchaser Party.

             "ADMINISTRATIVE AGENT'S LETTER" means that certain letter dated as
of the date hereof between the Company and the Administrative Agent.

             "ADMINISTRATIVE AGENT'S OFFICE" means the office of the
Administrative Agent identified as such in Schedule 1.1(b), or such other office
as the Administrative Agent may hereafter designate by notice to the Company,
the Paying Agent and each other Purchaser Party.

             "AGENTS" means, collectively, the Administrative Agent, the
Proceeds Collateral Agent, the Collateral Agent and the Co-Agents, if any, but
does not include the Paying Agent.

             "AGREEMENT" is defined in the Preamble and includes all
Schedules and Exhibits.

             "APPLICABLE MARGIN" means, at any time, with respect to Euro-Dollar
Rate Notes, 6% per annum and, with respect to Base Rate Notes, 5% per annum.


                         Nortel Note Purchase Agreement
                                        2


<PAGE>   8


             "APPLICABLE PURCHASING OFFICE" means, with respect to any Purchaser
Party, (i) in the case of any payment with respect to Euro-Dollar Rate Notes,
the Purchaser Party's Euro-Dollar Purchasing Office, and (ii) in the case of any
payment with respect to Base Rate Notes or any other payment under the Note
Documents, the Purchaser Party's Domestic Purchasing Office.

             "ASSIGNMENT" is defined in Section 8.6(b).

             "ASSIGNMENT AND ACCEPTANCE" means any Non-Recourse Assignment and
Acceptance and any Recourse Assignment and Acceptance.

             "BASE RATE" means, for any day, the greater of (i) the average of
interest rates per annum announced by the Reference Banks at their respective
principal offices as their prime rate effective for that day, which rate may not
be the lowest rate then being charged to commercial borrowers by such Reference
Banks, or (ii) the Federal Funds Rate in effect on such day plus 0.5% per annum.
Any change in the Base Rate due to a change in such prime rate or the Federal
Funds Rate shall be effective from and including the effective date of such
change, respectively, in such prime rate or the Federal Funds Rate.

             "BASE RATE NOTE" means a Note, or portion thereof, that bears
interest at a rate determined by reference to the Base Rate.

             "BRIDGE LOAN" means the loan facility agreement between the Company
and Nortel dated as of October 25, 1999.

             "CANCELLATION CERTIFICATE" is defined in Section 2.5(f).

             "CLOSING DATE" means the date on which all conditions set forth in
Section 3.1 hereof have been satisfied or waived, but in no event later than
December 17, 1999.

             "CO-AGENT" means any Purchaser or other Person designated from time
to time by the Administrative Agent to act as the managing agent, documentation
agent, co-arranger, syndication agent or co-agent or in any similar capacity
with respect to this Agreement, to which Purchaser or other Person, in such
capacity, Section 7.11 shall apply immediately upon such designation. The Paying
Agent, in its capacity as such, shall not be a Co-Agent.

             "COMMERCIAL LAUNCH DATE" means the first date upon which the
Company provides any telecommunications services to any Persons for which it
reasonably anticipates the receipt of a fee in payment for such services.

             "COMMITMENT" means, with respect to any Purchaser, the amount set
forth for such Purchaser as its "Commitment" in Schedule 1.1(a), as reduced,
terminated or increased from time to time pursuant to the terms hereof.

             "COMMITMENT INCREASE AGREEMENT" is defined in Section 2.5(a).

             "COMMITMENT USAGE" means, at any time, (i) with respect to any
Purchaser, the aggregate outstanding principal amount of all Notes (including,
in the case of Nortel, any


                         Nortel Note Purchase Agreement
                                        3

<PAGE>   9



Exchange Debt) held by such Purchaser, and (ii) with respect to all Purchasers,
the aggregate outstanding principal amount of all Notes (including, in the case
of Nortel, any Exchange Debt) held by all Purchasers, in each case giving effect
to Issuances of Notes then proposed.

             "COMMON TERMS AGREEMENT" means the Common Terms Agreement dated as
of the date hereof by and among (i) the Company, (ii) Vesper Holding S.A., (iii)
ABN AMRO and Harris Corporation, as Initial Facility Agents, (iv) the Pari Passu
Facility Agents that may hereafter become parties thereto and (v) the Collateral
Agent, as amended from time to time.

             "COMPANY" is defined in the Preamble.


             "COMPANY ACCOUNT" means the account information designated on
Schedule 10.4 of the Common Terms Agreement.

             "CONVERSION PORTION" is defined in Section 2.7.

             "DESIGNATED REPURCHASER" means either (i) a single purpose,
bankruptcy-remote Wholly-Owned Subsidiary of the Company that has capital
sufficient to satisfy the obligation to repurchase Notes pursuant to a Mandatory
Repurchase or a Mandatory Partial Repurchase, or (ii) a financial institution
described in the definition of "Eligible Assignee" in the Common Terms
Agreement.

             "DOMESTIC PURCHASING OFFICE" means the office, branch or Affiliate
of any Purchaser identified in Schedule 1.1(b) as its Domestic Purchasing Office
or such other office, branch or Affiliate as the Purchaser may hereafter
designate as its Domestic Purchasing Office by notice to the Company and the
Administrative Agent.

             "EURO-DOLLAR BUSINESS DAY" means any Business Day on which
commercial banks are open for international business (including dealings in
interbank Dollar deposits) in London, England.

             "EURO-DOLLAR PURCHASING OFFICE" means the office, branch or
Affiliate of any Purchaser identified in Schedule 1.1(b) as its Euro-Dollar
Purchasing Office or such other office, branch or Affiliate as the Purchaser may
hereafter designate as its Euro-Dollar Purchasing Office by notice to the
Company and the Administrative Agent.

             "EURO-DOLLAR RATE NOTE" means any Note, or portion thereof, that
bears interest at a rate determined by reference to an Adjusted Euro-Dollar Rate
(and as to which a single Interest Period is applicable).

             "EURO-DOLLAR RESERVE REQUIREMENT" means, with respect to any
Euro-Dollar Rate Note and for any day, the maximum percentage (expressed as a
decimal) at which reserves (including any marginal, supplemental, special or
emergency reserves), without duplication, are required by the Federal Reserve
Board to be maintained on such day by member banks of the Federal Reserve System
with respect to eurocurrency funding (currently referred to as "Eurocurrency
Liabilities" in Regulation D of the Federal Reserve Board) (or in respect of any
other category of liabilities that includes deposits by reference to which the
interest rate on Euro-


                         Nortel Note Purchase Agreement
                                       4


<PAGE>   10



Dollar Rate Notes is determined or any category of extensions of credit or other
assets that includes loans made or notes held by a non-United States office of
any bank to United States residents). The Euro-Dollar Rate Notes and any other
amounts payable by the Company under this Agreement or any other Note Document
shall be deemed to constitute eurocurrency funding and to be subject to such
reserve requirements without benefit of or credit for proration, exemptions, or
offsets that may be available from time to time to any Purchaser under
Regulation D or any comparable regulation.

             "EVENT OF DEFAULT" is defined in Section 6.1.

             "FEDERAL FUNDS RATE" means, for any day, the rate per annum
(rounded upwards, if necessary, to the nearest 1/100th of 1%) equal to the
weighted average of the rates of overnight federal funds transactions with
members of the Federal Reserve System arranged by federal funds brokers on such
day, as published for such day (or, if such day is not a Business Day, for the
next preceding Business Day) by the Federal Reserve Bank of New York on the
Business Day next succeeding such day, provided that if such rate is not so
published for any day that is a Business Day, the Federal Funds Rate for such
day shall be the average rate charged to the Reference Banks on such day on such
transactions as determined by the Administrative Agent.

             "FEDERAL RESERVE BOARD" means the Board of Governors of the Federal
Reserve System.

             "FEE LETTERS" means, collectively, the Administrative Agent's
Letter, the Proceeds Collateral Agent's Letter and the Purchasers' Fee Letter.

             "FEES" means, collectively, the fees described in the Fee Letters.

             "FRONT END FEES" is defined in the Administrative Agent's Letter.

             "GLOBAL NOTE" is defined in Section 7.12(a).

             "INITIAL ISSUANCE COMMITMENT" means, with respect to any Purchaser,
the amount set forth for such Purchaser as its "Initial Issuance Commitment" in
Schedule 1.1(a).

             "INITIAL ISSUANCE DATE" means the date on which the first Issuance
of Notes occurs.

             "INITIAL REPURCHASE DATE" means July 1, 2004.

             "INTEREST PAYMENT DATE" means the last day of March, June,
September and December in each year, beginning March 31, 2000.

             "INTEREST PERIOD" means, subject to the next sentence, with respect
to each Euro-Dollar Rate Note issued on any Issuance Date, the period commencing
on the date specified in the related Notice of Issuance or Notice of
Continuation/Conversion (or telephonic notice in lieu thereof) and ending one,
two, three or six months thereafter, as the Company may elect pursuant to
Section 2.1(c) or 2.3(c), as applicable. Notwithstanding the foregoing: (a) if a
Euro-Dollar


                         Nortel Note Purchase Agreement
                                        5

<PAGE>   11


Rate Note is continued, the Interest Period applicable to such Euro-Dollar Rate
Note shall commence on the day on which the Interest Period applicable to such
Euro-Dollar Rate Note ends; (b) any Interest Period applicable to a Euro-Dollar
Rate Note (i) that would otherwise end on a day that is not a Euro-Dollar
Business Day shall be extended to the next succeeding Euro-Dollar Business Day,
unless such succeeding Euro-Dollar Business Day falls in another calendar month,
in which case such Interest Period shall end on the next preceding Euro-Dollar
Business Day or (ii) that begins on the last Euro-Dollar Business Day of a
calendar month (or on a day for which there is no numerically corresponding day
in the calendar month at the end of such Interest Period) shall end on the last
Euro-Dollar Business Day of the calendar month; (c) no Interest Period for any
Note shall end after the stated maturity date of such Note and no Interest
Period for any Note shall both commence prior to and end after the Initial
Repurchase Date; and (d) for any Issuance subsequent (for purposes of this
definition, a "Subsequent Issuance") to the first Issuance (for purposes of this
definition, a "Benchmark Issuance") bearing an Interest Period of identical
length, the initial Interest Period of such Subsequent Issuance shall end on the
last day of the Interest Period for the Benchmark Issuance in effect on the date
of such Subsequent Issuance. Notwithstanding the foregoing, the first Interest
Period may end on an "Interest Payment Date," if the Company so elects in the
first Notice of Issuance.

             "ISSUANCE" means a contemporaneous issuance of Notes by the Company
and corresponding purchase by the Purchasers on the same Issuance Date.

             "ISSUANCE DATE" means any date on which a Note is (or is proposed
to be) issued.

             "LONDON INTERBANK OFFERED RATE" means, with respect to any Interest
Period, the rate per annum calculated by the Administrative Agent as the
arithmetic mean (rounded upwards, if necessary, to the next higher 1/100th of
1%) of the offered rates for deposits in Dollars with a term comparable to such
Interest Period that appears on the Telerate Page (as defined below) at
approximately 11:00 A.M., London time, on the second full Euro-Dollar Business
Day preceding the first day of such Interest Period; provided that if there
shall at any time no longer exist a Telerate Page, "London Interbank Offered
Rate" shall mean, with respect to each day during each Interest Period
pertaining to a Euro-Dollar Rate Note, the rate per annum equal to the average
of the rates at which the Reference Banks are offered Dollar deposits at or
about 10:00 A.M., New York City time, two Business Days prior to the beginning
of such Interest Period in the London interbank eurodollar market where the
eurodollar and foreign currency and exchange operations in respect of their
Euro-Dollar Rate Note purchases are then being conducted, for delivery on the
first day of such Interest Period, for the number of days comprised therein and
in an amount comparable to the principal amount of the Euro-Dollar Rate Notes to
be outstanding during such Interest Period. "Telerate Page" means the display
designated as Page 3750 on the Dow Jones & Company Telerate system (or such
other page as may replace such page on such system or any successor system for
the purpose of displaying the rates at which Dollar deposits are offered by
leading banks in the London interbank deposit market).

             "MANDATORY PARTIAL REPURCHASE" is defined in Section 2.6(c)(i).


                         Nortel Note Purchase Agreement
                                        6


<PAGE>   12


             "MANDATORY PARTIAL REPURCHASE AMOUNT" means the portion of any
"Mandatory Prepayment" (as defined in the Common Terms Agreement) required to be
applied to the Obligations under this Agreement pursuant to Article 8 of the
Common Terms Agreement.

             "MANDATORY PARTIAL REPURCHASE EVENT" means any event or
circumstance giving rise to a Mandatory Prepayment under Article 8 of the Common
Terms Agreement.

             "MANDATORY PARTIAL REPURCHASE NOTICE" is defined in Section
2.6(c)(i).

             "MANDATORY REPURCHASE" is defined in Section 2.6(a).

             "MANDATORY REPURCHASE NOTICE" is defined in Section 2.6(a).

             "MEMORANDUM" is defined in Section 5.2(a).

             "NON-RECOURSE ASSIGNMENT" is defined in Section 2.5(a).

             "NON-RECOURSE ASSIGNMENT AND ACCEPTANCE" is defined in Section
8.6(b).

             "NORTEL" is defined in the Preamble, and includes any successor.

              [***]

             "NORTEL PARTY" means Nortel or any of its Affiliates.

             [***]

             "NOTE" means a Note issued or to be issued pursuant to Article II,
which note is in substantially the form of Exhibit A, as amended from time to
time. A Base Rate Note or Euro-Dollar Rate Note each constitutes a "Type" of
Note.

             "NOTE DOCUMENTS" means, collectively, this Agreement, the Common
Terms Agreement, the Notes, the Guaranties, the Collateral Documents, the
Exchange Debt Agreement, the Capital Contribution Agreement, the Administrative
Agent's Letter, the Proceeds Collateral Agent's Letter, the Purchasers' Fee
Letter, the Subordination Agreements (other than any such agreement relating to
Subordinated Debt), all of the Interest Rate Hedge Agreements between the
Company, on the one hand, and one or more Swap Lenders, on the other hand, in
respect of the Obligations, and all amendments, exhibits and schedules to any of
the foregoing.

             "NOTICE OF CONTINUATION/CONVERSION" is defined in Section
2.3(c)(ii).

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                        7


<PAGE>   13


             "NOTICE OF CONVERSION TO EXCHANGE DEBT" is defined in Section 2.7.

             "NOTICE OF ISSUANCE" is defined in Section 2.1(c)(i).

             "NOTICE OF RESPONSIBLE OFFICER" is defined in Section 2.1(c)(iii).

             "OBLIGATED PARTY" is defined in Section 7.9(b).

             "OTHER COMMITMENTS" means Commitments (as defined in the Common
Terms Agreement) under the Other Note Purchase Agreements.

             "OTHER NOTE PURCHASE AGREEMENTS" means the Note Purchase Agreements
(as defined in the Common Terms Agreement), other than this Agreement.

             "OTHER NOTES" means Notes (as defined in the Common Terms
Agreement) issued pursuant to the Other Note Purchase Agreements.

             "OTHER PURCHASERS" means Purchasers (as defined in the Common Terms
Agreement) under the Other Note Purchase Agreements.

             "PARTIAL REPURCHASE DATE" is defined in Section 2.6(c)(i).

             "PARTICIPATION" is defined in Section 8.6(d).

             "PAVING AGENCY AGREEMENT" means that certain paying agency
agreement, dated as of the date hereof, by and among the Paying Agent, the
Company, the Administrative Agent, the other Initial Facility Agents and the
Collateral Agent.

             "PAYING AGENT" means Chase Trust Bank or any successor in such
capacity permitted hereby, as paying agent under the Paying Agency Agreement.

             "PAYING AGENT'S NORTEL ACCOUNT" means the account of the Paying
Agent identified in Schedule 1.1(b), or such other account as the Paying Agent
may hereafter designate by notice to the Company, the Collateral Agent and the
Administrative Agent in accordance with the terms of the Paying Agency
Agreement.

             "PAYING AGENT'S OFFICE" means the office of the Paying Agent
identified as such in Schedule 1.1(b), or such other office as the Paying Agent
may hereafter designate by notice to the Company, the Collateral Agent and the
Administrative Agent in accordance with the terms of the Paying Agency
Agreement.

             "PAYMENT SHARING NOTICE" means a notice from the Company or any
Purchaser informing the Administrative Agent that an Event of Default exists and
directing the Administrative Agent to allocate payments thereafter received from
or on behalf of the Company in accordance with the provisions of Section
2.9(c)(ii). A Payment Sharing Notice remains in effect until the relevant Event
of Default shall have been waived in accordance with Section 8.3.


                         Nortel Note Purchase Agreement
                                        8


<PAGE>   14


             "POST-DEFAULT RATE" means, subject to Section 2.3(e), at any time,
a rate per annum equal to the Adjusted Euro-Dollar Rate or the Base Rate in
effect at such time plus the Applicable Margin plus [***].


             "PROCEEDS ACCOUNT" is defined in the proviso to Section 2.2(a).

             "PROCEEDS ACCOUNT PLEDGE AGREEMENT" means the Proceeds Account
Pledge Agreement among the Company, the Proceeds Collateral Agent, the fund
administrator designated thereunder and the fund manager designated thereunder,
in substantially the form of Exhibit C hereto (or, if there is no such Exhibit
on the date hereof, acceptable in form and substance to Nortel), as amended from
time to time.

             "PROCEEDS COLLATERAL AGENT" means any financial institution or a
branch or agency of a financial institution, organized or licensed to do
business under the laws of the United States of America or any State thereof
appointed by the Administrative Agent pursuant to Article VII hereof to act as
the collateral agent under the Proceeds Account Pledge Agreement.

             "PROCEEDS COLLATERAL AGENT'S LETTER" means that certain letter,
dated as of a date on or prior to the Closing Date, between the Company and the
Proceeds Collateral Agent.

             "PROCESS AGENT" is defined in Section 8.9(b).

             "PROJECT" is defined in the Recitals.

             "PURCHASER" means the financial institutions and other entities
that from time to time are parties hereto as Purchasers, provided that
"Purchaser" shall not include Nortel unless it has a Commitment hereunder,
except for purposes of Sections 7.10 and 8.15, and as otherwise provided herein.
For purposes of the Sections referred to in (and subject to) the last sentence
of Section 8.6(d), "Purchaser" includes a holder of a Participation.

             "PURCHASER PARTY" is defined in the Preamble. For purposes of the
Sections referred to in (and subject to) the last sentence of Section 8.6(d),
"Purchaser Party" includes a holder of a Participation.

             "PURCHASERS' FEE LETTER" means that certain letter, dated as of a
date on or prior to the Closing Date, between Vesper Cayman SPV and the
Administrative Agent on behalf of the Purchasers.

             [***]

             "RECOURSE ASSIGNMENT AND ACCEPTANCE" is defined in Section 8.6(b).

             [***]

             "REFERENCE BANKS" means the Reference Purchaser, Citibank, N.A. and
The CHASE MANHATTAN BANK.

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                        9

<PAGE>   15


             "REFERENCE PURCHASER" means (i) the Administrative Agent, if it is
a bank, or (ii) ABN AMRO, if the Administrative Agent is not a bank.

             "REGISTER" is defined in Section 8.6(c).

             "REGULATORY CHANGE" means (i) the adoption or becoming effective
after the date hereof of any treaty, law, rule or regulation, (ii) any change in
any such treaty, law, rule or regulation (including Regulation D), or any change
in the administration or enforcement thereof, by any Governmental Authority,
central bank or other monetary authority charged with the interpretation or
administration thereof, in each case after the date hereof, or (iii) compliance
by any Purchaser Party (or its Applicable Purchasing Office or, in the case of
capital adequacy requirements, any holding company of any Purchaser Party) with,
any interpretation, directive, request, order or decree (whether or not having
the force of law) of any such Governmental Authority, central bank or other
monetary authority issued or made after the date hereof

             "REPURCHASE PRICE" is defined in Section 2.6(a).

             "REQUIRED PURCHASERS" means Purchasers holding more than 50% of the
sum of (i) the aggregate outstanding principal amount of the Notes plus, (ii)
unless all Commitments have then terminated, the aggregate amount of the Unused
Commitments of all Purchasers, provided that the Notes and Commitments of any
Purchaser that is a Defaulting Pari Passu Creditor shall be disregarded for
purposes of this determination.

             "RESPONSIBLE OFFICER" is defined in Section 2.1(c)(iii).

             "SECURITIES ACT" means the United States Securities Act of 1933, as
amended from time to time.

             "SENIOR OFFICER" means the Chairman of the Board of Directors, the
President, the Chief Executive Officer, the Chief Operating Officer, the Chief
Financial Officer, the Treasurer or any Vice President in charge of a principal
business unit or division of the Company or any of its Subsidiaries.

             "SPECIFIED PARI PASSU CREDITORS" is defined in Section 7.8(b).

             "SUBSEQUENT PURCHASERS" is defined in Section 8.19(b)(iv).

             "SYNDICATE" is defined in Section 5.2(a).

             "SYNDICATION" is defined in Section 5.2(a).

             "TERMINATION DATE" is defined in Section 2.5(e).

             "TYPE" is defined within the definition of Note.

             "UNUSED COMMITMENT" means, at any time, (i) with respect to any
Purchaser, the amount by which the Commitment of such Purchaser exceeds the
aggregate outstanding principal amount of all Notes held by such Purchaser (such
excess being further reduced, solely


                         Nortel Note Purchase Agreement
                                       10

<PAGE>   16

in respect of Nortel's Commitment hereunder, if any, by the aggregate principal
amount of Exchange Debt then held by it) and (ii) with respect to all
Purchasers, the amount by which the aggregate amount of the Commitments of all
Purchasers exceeds the aggregate outstanding principal amount of all Notes (for
this purpose, the Exchange Debt held by Nortel shall constitute Notes in respect
of Nortel's Commitments) held by all Purchasers, in each case before giving
effect to Issuances then proposed.

         SECTION 1.3 RELATED MATTERS. Section 1.2 of the Common Terms Agreement
(other than Section 1.2(b)) shall govern the interpretation of this Agreement
and is hereby incorporated herein by reference, provided that all references
therein to "this Agreement" shall be read as being to this Agreement.

         SECTION 1.4 DETERMINATIONS. Any determination or calculation
contemplated by this Agreement that is made by any Purchaser Party shall be
presumed correct and be binding upon the Company Parties and, in the case of
determinations by the Administrative Agent, also the other Purchaser Parties, in
the absence of manifest error. References in this Agreement to any
"determination" by any Purchaser Party include good faith estimates by such
Purchaser Party (in the case of quantitative determinations), and good faith
beliefs by such Purchaser Party (in the case of qualitative determinations). All
consents and other actions of any Purchaser Party contemplated by this Agreement
may be given, taken, withheld or not taken in good faith in such Purchaser
Party's absolute and sole discretion (whether or not so expressed), except as
otherwise expressly provided herein.


                                   ARTICLE II

                                PURCHASE OF NOTES

         SECTION 2.1 NOTES.


                  (a) Notes Generally. Each Purchaser severally agrees, upon the
terms and subject to the conditions set forth in this Agreement, to purchase for
a purchase price equal to par (i) a single Note of the Company on the Initial
Issuance Date in a principal amount not to exceed such Purchaser's Initial
Issuance Commitment and having a maturity date of July 1, 2012 and (ii)
additional Notes of the Company, at any time from and after the Closing Date
until the Business Day next preceding the Termination Date, each having a
maturity date of July 1, 2012, provided that (A) the Commitment Usage of any
Purchaser shall not exceed, at any time, the Commitment of such Purchaser, and
(B) the Commitment Usage of all Purchasers at any time, in the aggregate, shall
not exceed the lesser of (I) the aggregate amount of the Commitments of all
Purchasers, and (II) $700,000,000. All Notes shall be issued to the Purchasers,
in one or more Issuances, on a pro rata basis in accordance with their
respective Unused Commitments.

                  (b) Types of Notes; Minimum Amounts; Frequency of Issuances.

                           (i) Notes issued under this Section 2.1 shall be
         Euro-Dollar Rate Notes, subject, however, to Sections 2.3(b) and 2.10.


                         Nortel Note Purchase Agreement
                                       11

<PAGE>   17



                           (ii) No more than two Issuances shall be made
         hereunder during any calendar month.

                  (c) Notice of Issuance.

                           (i) When the Company desires or is required to issue
         Notes pursuant to this Section 2.1, it shall deliver to the
         Administrative Agent, with a copy to the Collateral Agent, a Notice of
         Issuance substantially in the form of Exhibit B-1, duly completed,
         executed by a Responsible Officer and with all exhibits required
         thereby (a "Notice of Issuance"), no later than 12:00 noon (New York
         time) at least three EuroDollar Business Days before the proposed
         Issuance Date.

                           (ii) In lieu of delivering a Notice of Issuance, the
         Company, through a Responsible Officer, may give the Administrative
         Agent telephonic notice of any proposed Issuance by the time a Notice
         of Issuance would be required to be delivered and containing all
         information required for a Notice of Issuance; provided, however, that
         such notice shall be promptly confirmed in writing by delivery of a
         Notice of Issuance to the Administrative Agent on or before the
         proposed Issuance Date. The Administrative Agent shall incur no
         liability to the Company or the other Purchaser Parties in acting upon
         any telephonic notice that the Administrative Agent believes in good
         faith to have been given by a Responsible Officer or for otherwise
         acting in good faith under this Section 2.1 and in causing any Notes to
         be Issued in accordance with this Agreement pursuant to any telephonic
         notice.

                           (iii) The Company shall notify the Administrative
         Agent of the names of its officers and employees authorized to request
         that the Purchasers purchase and to take other actions with respect to
         Notes on behalf of the Company (each, a "Responsible Officer") by
         providing the Administrative Agent with a Notice of Responsible Officer
         substantially in the form of Exhibit B-2, duly completed and executed
         by a Senior Officer of the Company (a "Notice of Responsible Officer").
         The Administrative Agent shall be entitled to rely conclusively on a
         Responsible Officer's authority to request that the Purchasers purchase
         and to take other actions with respect to Notes on behalf of the
         Company until the Administrative Agent receives a new Notice of
         Responsible Officer that no longer designates such Person as a
         Responsible Officer. The Administrative Agent shall have no duty to
         verify the authenticity of the signature appearing on any Notice of
         Issuance, Notice of Responsible Officer or any other notice given under
         the Note Documents.

                           (iv) Any Notice of Issuance (or telephone notice in
         lieu thereof) delivered pursuant to this Section shall be irrevocable
         and the Company shall be bound to issue Notes to the Purchasers in
         accordance therewith.

                           (v) The Administrative Agent shall promptly notify
         each Purchaser and Nortel of the contents of any Notice of Issuance (or
         telephonic notice in lieu thereof) received by it and, in the case of
         any such notice to a Purchaser, such Purchaser's pro rata portion of
         the purchase price of the Notes proposed to be issued pursuant thereto.
         Not later than 11:00 a.m. (New York time) on the date specified in such
         notice as the Issuance

                         Nortel Note Purchase Agreement
                                       12


<PAGE>   18


         Date, each Purchaser, subject to the terms and conditions hereof, shall
         make its pro rata portion of the purchase price of the Notes issued
         pursuant to such Notice of Issuance available, in immediately available
         funds, to the Administrative Agent at the Administrative Agent's Office
         for deposit in the Administrative Agent's Account.

                           (vi) Notwithstanding the foregoing, at any time that
         any amounts due to Nortel under the Nortel Supply Agreement shall
         remain unpaid for a period of thirty days after such amounts become due
         and payable (and, if there is any dispute with respect thereto, after
         exhaustion of all dispute resolution provisions set forth in the Nortel
         Supply Agreement), the Company shall be required to deliver to the
         Administrative Agent a Notice of Issuance with respect to an Issuance
         of Notes in a principal amount equal to such past due amount.

                  (d) Issuance. Not later than 12:00 noon (New York time) on the
proposed Issuance Date, subject to satisfaction of the applicable conditions set
forth in Article III, as determined by the Administrative Agent, the
Administrative Agent shall arrange for a wire transfer of immediately available
funds in the amount of the principal amount of the Notes to be issued pursuant
to such Issuance to the Company Account or such other account, if any, as may be
designated by the Company pursuant to wire instructions set forth in the Notice
of Issuance. Notwithstanding anything herein to the contrary, no Note shall be
released by the Administrative Agent to any Purchaser hereunder and no interest
shall accrue on any Note the purchase price of which is made available by any
Purchaser to the Administrative Agent pursuant to Section 2.1 (c)(v) until such
funds are made available to the Company pursuant to the terms of this Section
2.1(d).

         SECTION 2.2 USE OF PROCEEDS.

                  (a) The proceeds of the Notes shall be used by the Company
only to make payments:

                           (i) due under the Nortel Supply Agreement with
         respect to equipment and services provided thereunder and associated
         duties and taxes (other than the payment of civil works and duties and
         taxes related thereto), provided that the aggregate principal amount of
         Notes the proceeds of which may be used for the uses designated under
         this clause (i) may not exceed [***];

                           (ii) for interest on the Notes, Investments in Vesper
         Cayman SPV permitted by Section 5.4(e) of the Common Terms Agreement,
         Fees payable by the Company and other amounts (other than principal)
         payable to the Paying Agent or the Purchaser Parties under this
         Agreement, the Fee Letters, the Common Terms Agreement, the Exchange
         Debt Agreement, the Guaranties, or the Collateral Documents, any and
         all other fees and expenses incurred by any Company Party in connection
         with this Agreement, provided that the aggregate principal amount of
         the Notes the proceeds of which may be used for the purposes indicated
         in this clause (ii) may not exceed [***];

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.



                         Nortel Note Purchase Agreement
                                       13


<PAGE>   19




                           (iii) for civil works and associated duties and taxes
         required in connection with the Nortel Supply Agreement, provided that
         the aggregate principal amount of the Notes the proceeds of which may
         be used for the purposes indicated in this clause (iii) may not exceed
         [***]; and

                           (iv) to refinance the Bridge Loan;

provided, however, that the proceeds of the Issuance of Notes on the Initial
Issuance Date shall be used (A) first, to refinance the Bridge Loan; (B) second,
to the full extent of amounts then due under the Nortel Supply Agreement and the
Note Documents, for any of the uses set forth above and (C) to the extent not
immediately used by the Company for the purposes set forth in clauses (A) and
(B) of this proviso, to make Investments in (a) certificates of deposit or
export notes, (I) not less than $125,000,000 in principal amount of which shall
mature within ninety days from the date of acquisition thereof and the balance
of which shall mature within 180 days from the date of acquisition thereof, in
each case (II) are subject to a swap agreement that has the effect of indexing
the principal amount thereof to Dollars and is with a counterparty that is
reasonably acceptable to Nortel and (III) is issued by a financial institution
with a short-term debt rating of Al and/or P1 reasonably acceptable to Nortel;
or (b) Investments approved by Nortel in its discretion, that, in the case of
either (a) or (b), are at all times held in a brokerage account (the "Proceeds
Account") with a broker that shall be acceptable to Nortel and with respect to
which the Company has (x) delivered a power of attorney in form and substance
reasonably acceptable to the Administrative Agent and Nortel and (y) executed
and delivered a Proceeds Account Pledge Agreement pursuant to which the credit
rights of the Company in such Proceeds Account and all Investments from time to
time contained therein are subject to a first priority pledge in favor of the
Proceeds Collateral Agent for the ratable benefit of the Purchaser Parties,
which Proceeds Account Pledge Agreement has been filed, recorded or registered
with each relevant Governmental Authority.

                  (b) Without limitation of the foregoing, no equipment or
services provided by any Person other than Nortel (including Qualcomm or
Ericsson) except such equipment or services provided under the Nortel Supply
Agreement, and no interest accrued on Notes held or financing provided by any
such Person, will be eligible for financing under this Agreement.

         SECTION 2.3 INTEREST; INTEREST PERIODS; CONTINUATION/CONVERSION.

                  (a) Interest Rate and Payment.

                           (i) Each Note shall bear interest on the outstanding
         principal amount thereof, from and including the Issuance Date of such
         Note to and excluding the due date or the date of any repayment
         thereof, at the following rates per annum: (A) for so long as and to
         the extent that such Note is a Euro-Dollar Rate Note, at the Adjusted
         Euro-Dollar Rate for each day during each Interest Period applicable
         thereto plus the Applicable Margin in respect of EuroDollar Rate Notes;
         and (B) for so long as and to the extent that such Note is a Base Rate
         Note, at the Base Rate (as in effect from time to time) plus the
         Applicable Margin in respect of Base Rate Notes.

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                         Nortel Note Purchase Agreement
                                       14


<PAGE>   20



                           (ii) Interest shall accrue on all amounts other than
         principal payable by any Company Party under the Note Documents
         (including indemnities, overdue interest and Fees, but not including
         amounts payable pursuant to the last sentence of Section 8.1, or to the
         last sentence of Section 10.1 of the Common Terms Agreement, in either
         case during the 90-day period after the Closing Date) from the date
         such amount is due to and excluding the date of any payment thereof at
         the rate otherwise applicable to the Notes, subject to clause (iii)
         below.

                           (iii) Notwithstanding the foregoing provisions of
         this Section 2.3, at any time while an Event of Default exists under
         Section 6.1(a) or (q) of the Common Terms Agreement in respect of any
         principal, interest, Fees or other amount payable under the Note
         Documents or in respect of any indemnification obligation related
         thereto, all Notes and all other amounts payable under the Note
         Documents shall bear interest to the maximum extent permitted by
         Applicable Law at a fluctuating rate per annum equal to the
         Post-Default Rate as in effect from time to time, without notice or
         demand of any kind, until such Event of Default shall have been waived
         or otherwise shall have ceased to exist.

                           (iv) Accrued interest shall be payable in arrears (A)
         in the case of a Base Rate Note, on each Interest Payment Date; (B) in
         the case of a Euro-Dollar Rate Note, on the last day of each Interest
         Period applicable thereto; provided that if the Interest Period
         applicable to a Euro-Dollar Rate Note is longer than three months,
         interest also shall be payable on the day that is three months after
         the first day of such Interest Period; (C) in the case of any interest
         accrued at the Post-Default Rate or pursuant to Section 2.3(a)(ii), on
         demand; and (D) in the case of any Note, when the Note shall become due
         (whether at maturity, by reason of prepayment, acceleration, Mandatory
         Repurchase, Mandatory Partial Repurchase or otherwise).

                  (b) Interest Periods and Minimum Amounts. Notwithstanding
anything herein to the contrary, (i) all Interest Periods applicable to
Euro-Dollar Rate Notes shall comply with the definition of "Interest Period,"
(ii) there may be no more than 15 different Interest Periods for all Euro-Dollar
Rate Notes outstanding at the same time, (iii) Euro-Dollar Rate Notes with the
same Interest Period outstanding at any time shall be in an aggregate amount at
least equal to (x) in the case of Notes issued by the Company to pay interest,
Fees and other amounts payable pursuant to Section 2.2(a)(ii), in such aggregate
amount of such interest, Fees or other amount payable; (y) in the case of Notes
issued by the Company to make payments due under the Nortel Supply Agreement
pursuant to Section 2.2(a)(i), in such aggregate amount greater than [***]
as is equal to the amount of the related invoice under the Nortel Supply
Agreement; or (z) in all other cases, $2,000,000 and in an integral multiple of
$1,000,000 and (iv) Base Rate Notes outstanding at any time shall be in an
aggregate amount at least equal to $1,000,000.

                  (c) Continuation/Conversion.

                           (i) Subject to this Section 2.3(c), Sections 2.3(b)
         and 2.10 and the Company obtaining all necessary approvals, the Company
         shall have the option (A) at any time, to convert all or any part of
         its outstanding Base Rate Notes to Euro-Dollar Rate Notes, (B) on the
         last day of the Interest Period applicable thereto, to (I) convert all
         or any part of its outstanding Euro-Dollar Rate Notes to Base Rate
         Notes, (II) continue all

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       15


<PAGE>   21




         or any part of its Euro-Dollar Rate Notes as Notes of the same Type,
         provided that, in the case of clauses (A) and (B)(ii), there does not
         exist an Event of Default at such time. If an Event of Default shall
         exist upon the expiration of the Interest Period applicable to any
         Euro-Dollar Rate Note, such Note automatically shall be converted into
         a Base Rate Note.

                           (ii) If the Company elects to continue or convert a
         Note under this Section 2.3(c), it shall deliver to the Administrative
         Agent a Notice of Continuation/Conversion substantially in the form of
         Exhibit D, duly completed and executed by a Responsible Officer (a
         "Notice of Continuation/Conversion"), (A) not later than 10:00 a.m.
         (New York time) at least three Euro-Dollar Business Days before the
         proposed continuation or conversion date, if the Company proposes to
         continue, or to convert into, a Euro-Dollar Rate Note, and (B)
         otherwise not later than 10:00 a.m. (New York time) at least three
         Business Days before the proposed continuation or conversion date.

                           (iii) In lieu of delivering a Notice of
         Continuation/Conversion, the Company, through a Responsible Officer,
         may give the Administrative Agent telephonic notice of any proposed
         continuation or conversion by the time a Notice of
         Continuation/Conversion would be required to be delivered and
         containing all information required therefor; provided, however, that
         such notice shall be confirmed in writing by delivery of a Notice of
         Continuation/Conversion to the Administrative Agent on or before the
         proposed continuation or conversion date. The Purchaser Parties shall
         incur no liability to the Company in acting upon any telephonic notice
         that the Administrative Agent believes to have been given by a
         Responsible Officer or for otherwise acting in good faith under this
         Section 2.3(c) and in converting or continuing any Note (or a part
         thereof) pursuant to any telephonic notice.

                           (iv) Any Notice of Continuation/Conversion (or
         telephonic notice in lieu thereof) shall be irrevocable and the Company
         shall be bound to continue or convert in accordance therewith. If any
         request for the continuation or conversion of a Note is not made in
         accordance with this Section 2.3(c), or if no notice is so given with
         respect to a Euro-Dollar Rate Note as to which the Interest Period
         expires, then such Note automatically shall be continued as a
         Euro-Dollar Rate Note having an Interest Period of one month.

                           (v) The Administrative Agent shall promptly notify
         each Purchaser and Nortel of the contents of any Notice of
         Continuation/Conversion (or telephonic notice in lieu thereof) received
         by it, or of the automatic continuation of any Euro-Dollar Rate Note
         pursuant to clause (iv).

                  (d) Computations. Interest accruing at the Euro-Dollar Rate
shall be computed on the basis of a 360-day year and the actual number of days
elapsed (including the first and excluding the last day of the period). All
other amounts payable hereunder or under the other Note Documents shall be
computed on the basis of a 365/366-day year and the actual number of days
elapsed (including the first and excluding the last day of the period). Any
change in the interest rate on any Note or other amount resulting from a change
in the rate

                         Nortel Note Purchase Agreement
                                       16


<PAGE>   22




applicable thereto pursuant to the terms hereof shall become effective as of
9:00 a.m. (New York time) on the day on which such change in the applicable rate
shall become effective.

                  (e) Maximum Lawful Rate of Interest. The rate of interest
payable on any Note or other amount shall in no event exceed the maximum rate
permissible under Applicable Law. If the rate of interest payable on any Note or
other amount is ever reduced as a result of this Section and at any time
thereafter the maximum rate permitted by Applicable Law shall exceed the rate of
interest provided for in this Agreement, then the rate provided for in this
Agreement shall be increased up to the maximum rate provided by Applicable Law
for such period as is required so that the total amount of interest received by
the Purchasers during such period is that which would have been received by the
Purchasers but for the operation of the first sentence of this Section.

         SECTION 2.4 FEES.

                  (a) Fees. On the Closing Date and from time to time thereafter
as specified in the Administrative Agent's Letter or the Proceeds Collateral
Agent's Letter, as the case may be, the Company shall (i) pay to the Paying
Agent or to the Administrative Agent the Fees specified in the Administrative
Agent's Letter and (ii) pay to the Paying Agent or to the Proceeds Collateral
Agent the Fees specified in the Proceeds Collateral Agent's Letter.

                  (b) Fees Non-Refundable. All Fees shall be fully earned when
payable hereunder and shall be non-refundable except under the circumstances
described in the last sentence of Section 2.8(b).

         SECTION 2.5 INCREASE, TERMINATION AND REDUCTION OF COMMITMENTS.

                  (a) Upon (i) the unconditional written release or
effectiveness of any conditional release, in each case by the Administrative
Agent and one or more of the Purchasers (other than an Affiliate of Nortel) of
Nortel from the [***] in respect of all or a portion of the Notes then held by
such Purchaser, (ii) the assumption by one or more Purchasers (other than an
Affiliate of Nortel) of all or a portion of the Unused Commitment of Nortel,
(iii) the Assignment by Nortel of all or a portion of the Notes then held by
Nortel (other than to an Affiliate of Nortel), provided in the case of clause
(i), (ii) and (iii), such Unused Commitment and Notes cease to be covered under
[***], (any of the foregoing being a "Non-Recourse Assignment"), (iv) the
assignment or transfer of a beneficial ownership (including by way of a sale of
a participation) without recourse by Nortel of Exchange Debt (other than to an
Affiliate of Nortel), or (v) the receipt by Nortel in repurchase of all or any
portion of any Notes held by Nortel of its pro rata portion of any Mandatory
Partial Repurchase Amount paid by the Company pursuant to Section 8.1(b) of the
Common Terms Agreement, Nortel shall concurrently execute and deliver to the
Administrative Agent and the Company a Commitment Increase Agreement
substantially in the form of Exhibit E hereto (a "Commitment Increase
Agreement"), in which Nortel shall agree that, from and after the date of
effectiveness of such release, assumption, assignment or repurchase, Nortel
shall have a Commitment under this Agreement, or Nortel's Commitment hereunder
shall be increased (as the case may be) by an amount equal to the principal
amount of the Notes so released from [***] (including in connection with any
such Non-Recourse Assignment) or the amount of Nortel's

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                         Nortel Note Purchase Agreement
                                       17


<PAGE>   23



Unused Commitment so assumed, the principal amount of Exchange Debt so assigned
or the principal amount of Notes held by Nortel so repurchased (an "Additional
Commitment"), provided that (x) the aggregate amount of Additional Commitments
hereunder shall not exceed [***] minus the sum of:

                           (i) the amount by which the Commitments of the other
         Purchasers have increased since the Closing Date pursuant to amendments
         of this Agreement or by additional financial institutions becoming
         Purchasers hereunder, all pursuant to Section 2.5(d) below, plus

                           (ii) the product of "A" multiplied by "B;" where

                           [***]

         (y) the Company shall pay to the Paying Agent or to the Administrative
Agent all Front End Fees payable to it as a result of such Non-Recourse
Assignment pursuant to the Administrative Agent's Letter; and provided further
that, after giving effect to any such Additional Commitment, the sum of (1) the
aggregate principal amount of Notes and Unused Commitments that are subject to
the [***] , (2) the aggregate principal amount of Nortel's Notes and Commitment
hereunder, and (3) the principal amount of Exchange Debt then held by Nortel, in
the aggregate, may not exceed [***] (in case this proviso is not satisfied, the
amount of the Additional Commitment shall be reduced accordingly).

                  (b) Following effectiveness of any Additional Commitment, the
Administrative Agent shall promptly notify the Company and all other Purchaser
Parties of the amount of such Additional Commitment and Nortel's Commitment or
increased Commitment, as the case may be, giving effect thereto, and promptly
distribute to the parties hereto a revised Schedule 1.1(a) reflecting Nortel's
new or increased Commitment, and such revised Schedule 1.1(a) shall, as of the
date of effectiveness of Nortel's new or increased Commitment and thereafter,
constitute Schedule 1.1(a) for all purposes.

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                         Nortel Note Purchase Agreement
                                       18




<PAGE>   24



                  (c) If another Purchaser agrees that the Commitment of such
other Purchaser may be increased by the amount of, or an Eligible Assignee
agrees to become a Purchaser with a Commitment equal to, the amount of the
Additional Commitment otherwise required hereunder, all as specified in Section
2.5(d) below, Nortel's obligation to provide an Additional Commitment pursuant
to Section 2.5(a) shall be released.

                  (d) Effective upon the delivery by any Purchaser in its
discretion, or by any Eligible Assignee, to the Company and the Administrative
Agent of a duly executed Commitment Increase Agreement, such Purchaser shall
have an increased Commitment under this Agreement, or such Eligible Assignee
shall become a Purchaser hereunder and have a Commitment hereunder, as set forth
in such Commitment Increase Agreement. Except as otherwise set forth in this
Section 2.5, no Purchaser shall have any obligation whatsoever to deliver a
Commitment Increase Agreement. Upon effectiveness of any new or additional
Commitment, the Administrative Agent shall notify the Company and all other
Purchaser Parties and Nortel of the amount of such additional or new Commitment
and the identity of the new Purchaser (if applicable), promptly distribute to
the parties hereto a revised Schedule 1.1(a) reflecting such Purchaser's new or
increased Commitment, and such revised Schedule 1.1(a) shall, as of the date of
effectiveness of such Purchaser's new or increased Commitment and thereafter,
constitute Schedule 1.1(a) for all purposes. In no event whatsoever shall the
Commitment of any Purchaser increase without the written consent of such
Purchaser.

                  (e) Each Purchaser's Commitment shall terminate without
further action on the part of such Purchaser on the earliest to occur of (i)
July 1, 2004, (ii) the date of termination of such Commitment of such Purchaser
pursuant to Section 2.5(f), or (iii) the date of termination of the Commitments
of all Purchasers pursuant to Section 6.2 (such earliest date being referred to
herein as the "Termination Date" with respect to such Commitment).

                  (f) The Company shall have the right, at any time or from time
to time after the Closing Date, to terminate in whole or permanently reduce in
part, without premium or penalty, the Commitments of the Purchasers on a pro
rata basis to an amount not less than the Commitment Usage of all Purchasers at
such time, by giving the Administrative Agent not less than three Business Days'
prior written notice of such termination or reduction and the amount of any
partial reduction, subject to demonstrating either (i) the availability of
alternative funds at least equal to the amount of Commitments requested to be
terminated or reduced, or (ii) that such terminated portions are no longer
required by the Company to complete the Project. In connection with any such
notice, the Company shall, on the date of such notice, deliver to Nortel and the
Administrative Agent (A) a certificate substantially in the form of Exhibit F,
duly completed and executed by the Chief Financial Officer of the Company (a
"Cancellation Certificate") setting forth in reasonable detail the reasons for
such termination or reduction and (B) financial projections for the Company,
reasonably acceptable to Nortel and the Administrative Agent, supporting the
statements contained in the Cancellation Certificate. Nortel shall promptly
inform the Administrative Agent as to whether the Cancellation Certificate is
acceptable. Such notice, the Cancellation Certificate and Nortel's acceptance or
rejection thereof shall be promptly sent by the Administrative Agent to the
Purchasers upon its receipt of each. Any such termination or partial reduction
shall be effective on the date specified in the


                         Nortel Note Purchase Agreement
                                       19


<PAGE>   25




Company's notice and shall be in a minimum amount of $5,000,000 and in integral
multiples of $100,000.

                  (g) The Commitments of any [***] are subject to reduction, and
Nortel may acquire a Commitment or its Commitment may be increased, in each
case, as specified in Section 8.6(f).

                  (h) Except as otherwise provided in Section 2.5(a) and subject
to each Purchaser's right to reject the offer of any Mandatory Partial
Repurchase Amount pursuant to Section 2.6(c)(ii), upon receipt by the Purchasers
of any Mandatory Partial Repurchase Amount, or any voluntary repurchase of the
Note pursuant to Section 2.6(d), the Commitment of each Purchaser shall be
reduced by the principal amount of the Notes so repurchased. In addition, the
Commitments of the Purchasers shall be reduced on a pro rata basis under the
circumstances and in the amount specified in Section 9.6(a)(iii) of the Common
Terms Agreement.

         SECTION 2.6 REPURCHASE; MATURITY.

                  (a) Mandatory Repurchase. The Administrative Agent, by notice
given not less than five Business Days prior to Initial Repurchase Date (the
"Mandatory Repurchase Notice") to the Company and to each other Purchaser Party,
may (and upon instructions of any Purchaser shall) require the Company to
repurchase (a "Mandatory Repurchase") and, if such notice is given, the Company
shall repurchase or cause to be repurchased by a Designated Repurchaser, and
each of the Purchasers that so instructed the Administrative Agent shall sell on
the Initial Repurchase Date, all (but not less than all) of the Notes held by
such Purchaser for a repurchase price, in Dollars and in immediately available
funds, equal to the aggregate outstanding principal amount of all such Notes
held by such Purchaser so repurchased, plus accrued and unpaid interest on such
principal amount to the date of repurchase (the "Repurchase Price").

                  (b) Excess Principal Amount Repurchase. If at any time the
aggregate Commitment Usage of any Purchaser exceeds the amount of such
Purchaser's Commitment, the Company or a Designated Repurchaser shall, within
three Business Days after the Business Day on which the Company learns of or is
notified of the excess, make mandatory repurchases of the Notes as may be
necessary so that, after such repurchase, such excess is eliminated.

                  (c) Mandatory Partial Repurchase.

                           (i) Upon the occurrence of any Mandatory Partial
         Repurchase Event, the Company shall give the Administrative Agent and
         each of the Purchasers prompt written notice of the occurrence of such
         Mandatory Partial Repurchase Event (the "Mandatory Partial Repurchase
         Notice") and the Company shall offer or cause a Designated Repurchaser
         to offer to repurchase (a "Mandatory Partial Repurchase") and, subject
         to clause (ii), the Purchasers shall sell, on the Euro-Dollar Business
         Day specified in the Mandatory Partial Repurchase Notice (which date
         shall not be less than five Euro-Dollar Business Days after the date of
         the Mandatory Partial Repurchase Notice and shall not be after the date
         any Mandatory Prepayment in respect of such Mandatory Partial
         Repurchase Event is required to be made under the terms of the Common
         Terms

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       20




<PAGE>   26


         Agreement) (the "Partial Repurchase Date"), the maximum principal
         amount of Notes that may be repurchased with the Mandatory Partial
         Repurchase Amount, which amount shall be in Dollars and in immediately
         available funds, and shall be allocated among the Purchaser Parties in
         accordance with Section 2.9; provided that the Mandatory Partial
         Repurchase Amount shall, with respect to each Mandatory Partial
         Repurchase, be applied first to purchase the Base Rate Notes and then
         to purchase the Euro-Dollar Rate Notes held by each such Purchaser (or
         each such Purchaser's designee).

                           (ii) Each Purchaser shall be entitled to reject any
         Mandatory Partial Repurchase offer by the Company or by a Designated
         Repurchaser pursuant to this Section 2.6(c) and shall notify the
         Administrative Agent of such rejection no more than three days after
         receipt by such Purchaser of a copy of the Mandatory Partial Repurchase
         Notice. The amount of principal and accrued interest on the Notes of
         any Purchaser that rejects the offer of Mandatory Partial Repurchase
         that would otherwise have been repurchased shall be applied to
         repurchase Notes on a pro rata basis in accordance with the Commitment
         Usage of all other Purchasers that did not reject the offer of
         Mandatory Partial Repurchase until the outstanding principal amount of
         the Notes and Commitments of all such Purchasers have been reduced to
         zero and thereafter shall be reapplied as provided in Section
         9.6(a)(iii) of the Common Terms Agreement.

                  (d) Voluntary Repurchase.

                           (i) Subject to this Section 2.6(d), the Company, at
         its option (to the extent permissible under Applicable Law), at any
         time or from time to time, may or may cause a Designated Repurchaser
         to, repurchase the Notes in whole or in part, without premium or
         penalty, provided that (A) any repurchase shall be of an aggregate
         principal amount of Notes of $2,000,000 and integral multiples of
         $l,000,000, in the case of Euro-Dollar Rate Notes, or a minimum
         aggregate amount of $1,000,000 and integral multiples of $1,000,000, in
         the case of Base Rate Notes (or, alternatively for either Type of Note,
         the whole principal amount of Notes then outstanding), and (B) any
         repurchase of a Euro-Dollar Rate Note, if made on a day other than the
         last day of the Interest Period applicable thereto, shall be made with
         amounts payable pursuant to Section 2.13.

                           (ii) If the Company elects to, or elects to cause a
         Designated Repurchaser to, repurchase Notes under this Section 2.6(d),
         it shall deliver to the Administrative Agent a notice of voluntary
         repurchase (A) not later than 12:00 noon (New York time) at least three
         Euro-Dollar Business Days before the proposed repurchase, if the
         Company proposes to repurchase or cause to be repurchased Euro-Dollar
         Rate Notes and (B) otherwise not later than 12:00 noon (New York time)
         three Business Days before the proposed voluntary repurchase date. Any
         notice of voluntary repurchase shall be irrevocable, and the principal
         amount of Notes to be repurchased specified in such notice shall be due
         and payable on the date specified in such notice, together with
         interest accrued thereon to such date and any amounts payable pursuant
         to Section 2.13 with respect thereto.

                           (iii) Each voluntary repurchase shall be applied to
         the unpaid principal amount of the Notes held by the respective
         Purchasers as provided in Section 2.9;


                         Nortel Note Purchase Agreement
                                       21
<PAGE>   27



         provided that each voluntary repurchase shall be applied first to
         repurchase the Base Rate Notes and then to repurchase the Euro-Dollar
         Rate Notes held by each such Purchaser.

                  (e) Repurchase Generally. If any Notes are repurchased by the
Company or by any Designated Repurchaser pursuant to this Section 2.6, each
Purchaser shall deliver to the Administrative Agent the Notes held by it that
are to be repurchased endorsed for transfer or accompanied by bond powers
executed by such Purchaser, against receipt of payment of the Repurchase Price,
the Mandatory Partial Repurchase Amount or the amount of the voluntary
repurchase, as the case may be. Such repurchase shall be made without recourse
to, or representation or warranty of any kind by, such Purchaser, except that
the Notes shall be sold free and clear of any Lien created by the Administrative
Agent or the Purchaser.

                  (f) Maturity. All Notes outstanding on July 1, 2012 shall be
due and payable on such date.

         SECTION 2.7 CONVERSION OF NORTEL NOTES INTO EXCHANGE DEBT. If all or
any portion of the Notes held at any time by Nortel are to be converted into
Exchange Debt pursuant to the terms and conditions of the Exchange Debt
Agreement (such portion being the "Conversion Portion"), Nortel and the Company
shall deliver to the Administrative Agent a Notice of Conversion to Exchange
Debt in the form provided in the Exchange Debt Agreement (the "Notice of
Conversion to Exchange Debt") not later than 12:00 noon (New York time) at least
three Business Days before the conversion date. On such conversion date, the
Conversion Portion shall cease to be outstanding hereunder and the Company shall
pay to the Administrative Agent, for the sole account of Nortel, any accrued and
unpaid interest on the Conversion Portion of the Notes.

         SECTION 2.8 MANNER OF PAYMENT.

                  (a) Payment Generally. Except as otherwise expressly provided,
the Company and any Designated Repurchaser shall make each payment under the
Note Documents to the Paying Agent in Dollars and in immediately available
funds, without any deduction whatsoever, including any deduction for any setoff,
recoupment, counterclaim or Taxes (other than Excluded Taxes), at the Paying
Agent's Office for deposit in the Paying Agent's Nortel Account (which amount
will be held in trust for the Administrative Agent) at such time as shall
provide the Paying Agent with sufficient time to, in turn, pay such amount to
the Administrative Agent in Dollars and in immediately available funds, without
any deduction whatsoever, including any deduction for any setoff, recoupment,
counterclaim or Taxes at the Administrative Agent's Office for the account of
the Applicable Purchasing Offices of the Purchaser Party entitled to such
payment for deposit in the Administrative Agent's Account not later than 12:00
noon (New York time) on the due date thereof. Any payments received by the
Administrative Agent after 12:00 noon (New York time) on any Business Day shall
be deemed received on the next succeeding Business Day. Not later than 2:00 p.m.
(New York time) on the day such payment is made, the Administrative Agent shall
initiate a wire transfer to each Purchaser Party, for the account of the
Purchaser Party's Applicable Purchasing Office, in Dollars and in immediately
available funds, of such Purchaser's share of the payment so made, determined
pursuant to Section 2.9. Delivery to the Administrative Agent shall be made by
the Paying Agent in accordance with the written instructions satisfactory to the
Paying Agent from

                         Nortel Note Purchase Agreement
                                       22


<PAGE>   28





time to time given to the Paying Agent by the Administrative Agent; and delivery
to each Purchaser Party shall be made by the Administrative Agent in accordance
with the written instructions satisfactory to the Administrative Agent from time
to time given to the Administrative Agent by each Purchaser. Any payment made by
the Company or any Designated Repurchaser to the Paying Agent in accordance with
this Section 2.8(a) shall satisfy pro tanto and shall be conclusive and shall
discharge the Company or such Designated Repurchaser of its corresponding
payment obligations to the Purchaser Parties under the Notes.

                  (b) Indemnification by the Company. To the extent that the
Company or any Designated Repurchaser makes any payment due under this Agreement
or any other Note Document to the Paying Agent, the Company hereby indemnifies
the Purchaser Parties against any failure on the part of the Paying Agent to pay
to the Administrative Agent in accordance with the instructions provided to the
Paying Agent by the Administrative Agent pursuant to Section 2.8(a) any sum due
in respect of the Notes or any other Note Document by the due date or due time
thereof in an amount, at a minimum, equal to the portion of such payment made to
the Paying Agent not paid to the Administrative Agent as aforesaid and agrees to
pay such amount, plus interest at the Post-Default Rate, not later than (i) one
Business Day after the due date thereof, in the case of payments of principal,
(ii) three Business Days after the due date thereof, in the case of payments of
interest and (iii) five Business Days after the due date thereof, in the case of
expenses, Fees or other amounts payable under the Note Documents. This indemnity
constitutes a separate and independent obligation from the obligations of the
Company under the Notes and shall give rise to a separate and independent cause
of action. To the extent that the Paying Agent makes any payment to the
Administrative Agent with respect to which the Purchaser Parties have received a
payment from the Company in satisfaction of its indemnification obligations set
forth in this Section 2.8(b), each Purchaser Party shall promptly return to the
Company any such indemnification payment so made by the Company, together with
interest at the Federal Funds Rate from one Business Day after the later of(x)
the date on which the payment from the Paying Agent was received by such
Purchaser Party and (y) the date on which such indemnification payment from the
Company was received by such Purchaser Party, to but excluding the date on which
such payment is returned to the Company.

                  (c) Payment by the Company or any Designated Repurchaser.
Notwithstanding anything in this Section 2.8 to the contrary, the Company or any
Designated Repurchaser may, subject to the receipt of any necessary Governmental
Approvals and in lieu of making any payment to the Paying Agent, make any such
payment to the Administrative Agent in Dollars and in immediately available
funds, without any deduction whatsoever, including any deduction for any setoff,
recoupment, counterclaim or Taxes (other than Excluded Taxes), at the
Administrative Agent's Office, for deposit in the Administrative Agent's Account
for the account of the Purchaser Parties not later than 12:00 noon (New York
time) on the due date thereof. Any payments received by the Administrative Agent
after 12:00 noon (New York time) on any Business Day shall be deemed received on
the next succeeding Business Day.

                  (d) Date of Payment. Whenever any payment or repurchase to be
made hereunder shall be due on a day that is not a Business Day (or, in the case
of any payment with respect to any Euro-Dollar Rate Note, not a Euro-Dollar
Business Day), such payment shall instead be made on the next succeeding
Business Day (or, in the case of any such payment with

                         Nortel Note Purchase Agreement
                                       23


<PAGE>   29


respect to any Euro-Dollar Rate Note, the next succeeding Euro-Dollar Business
Day), together with interest accrued during the period of such extension,
unless, in the case of any such payment in respect of Euro-Dollar Notes, such
succeeding Euro-Dollar Business Day fails in the next calendar month, in which
case such payment or repurchase shall be made on the immediately preceding
Euro-Dollar Business Day.

                  (e) Payments Set Aside. To the extent any Agent or any
Purchaser receives payment of any amount under the Note Documents, whether by
way of payment by the Company, setoff, as proceeds of Collateral or otherwise,
which payment is subsequently invalidated, declared to be fraudulent or
preferential, set aside or required to be repaid to a trustee, receiver or any
other party under any bankruptcy law, other law or equitable cause, in whole or
in part, then, to the extent of such payment received and to the fullest extent
permitted by Applicable Law, the Obligations or Fees or part thereof intended to
be satisfied thereby shall be revived and continue in full force and effect,
together with all Collateral security therefor, as if such payment had not been
received by such Agent or Purchaser. If prior to any such invalidation,
declaration, setting aside or requirement, this Agreement shall have been
canceled or surrendered, this Agreement shall (to the extent permitted by
Applicable Law) be reinstated in full force and effect, and such prior
cancellation or surrender shall (to the extent permitted by Applicable Law) not
diminish, discharge or otherwise affect the obligations of the Company in
respect of the amount of the affected payment.

         SECTION 2.9 PRO RATA TREATMENT.

                  (a) Except to the extent otherwise expressly provided herein
or in the Fee Letters,

                           (i) Notes shall be issued to the Purchasers, pro
         rata according to their respective Unused Commitments, and

                           (ii) Each reduction of the Commitments shall be
         applied to the respective Commitments of the Purchasers pro rata
         according to their respective Unused Commitments before such reduction;
         provided, however, that in the case of Nortel but not any other
         Purchaser, Nortel's Commitment may subsequently be increased pursuant
         to Section 2.5(a).

                  (b) Except to the extent otherwise expressly provided herein,
(i) each payment or prepayment by the Company, the Paying Agent or a Designated
Repurchaser of principal or payment in respect of a repurchase by the Company or
a Designated Repurchaser of the Notes shall be made for the account of the
Purchasers pro rata according to the respective outstanding principal amount of
the Notes held by the Purchasers, provided that (A) Mandatory Partial
Repurchases shall be made pro rata in accordance with the respective Commitment
Usage of the Purchasers (or, after the Notes of Nortel, if any, have been
repurchased in full, in accordance with the respective principal amounts of
Notes held by the other Purchasers), and (B) repurchases required by Section
2.6(b) shall be applied to eliminate any excess for any Purchaser of the
aggregate principal amount of such Purchaser's Notes over its Commitment and
(ii) each payment by the Company or the Paying Agent of interest on the Notes
shall be made for the


                         Nortel Note Purchase Agreement
                                       24



<PAGE>   30



account of the Purchasers pro rata according to the respective accrued but
unpaid interest on the Notes owed to such Purchasers on such day.

                  (c) Whenever any payment received by the Administrative Agent
under this Agreement or any other Note Document is insufficient to pay in full
all amounts then due and payable to the Purchaser Parties under the Note
Documents, including in respect of any repurchase:

                           (i) if the Administrative Agent has not received a
         Payment Sharing Notice (or if all Payment Sharing Notices previously
         given shall have ceased to be in effect), such payment shall be applied
         in the following order: first, to the ratable payment of Fees, costs
         and expenses due and payable to the Agents under the Note Documents;
         second, to the ratable payment of all costs and expenses due and
         payable to the Purchaser Parties (other than the Agents) under Section
         8.1; third, to the ratable payment of Fees then due and payable to the
         Purchaser Parties pursuant to Section 2.4 or the Purchasers' Fee
         Letter; fourth, to the ratable payment of accrued and unpaid interest
         then due and payable on the Notes and other Obligations to the
         Purchaser Parties; and fifth, to the ratable payment of the principal
         amount of all Notes then due and payable or subject to repurchase (in
         each case in accordance with the respective amounts owed therefor); or

                           (ii) if the Administrative Agent has received a
         Payment Sharing Notice that remains in effect, such payment shall be
         applied in the following order: first, to the ratable payment of the
         costs and expenses due and payable to the Agents under the Note
         Documents; second, to the ratable payment of all costs and expenses due
         and payable to the Purchaser Parties (other than the Agents) under
         Section 8.1; third, to the ratable payment of Fees then due and payable
         to the Purchaser Parties pursuant to Section 2.4 or the Purchasers' Fee
         Letter; fourth, to the payment of the accrued and unpaid interest on
         all Notes and other Obligations, regardless of whether any such amount
         is then due and payable, ratably among the Purchaser Parties in
         accordance with the aggregate accrued interest plus the aggregate
         principal amount of all Notes and other Obligations to the Purchaser
         Parties then due and payable to each such Purchaser Party; and fifth,
         to the ratable payment of the principal amount of all Notes and other
         Obligations to the Purchaser Parties, regardless of whether any such
         Note is due and payable or subject to repurchase.

         SECTION 2.10 MANDATORY SUSPENSION AND CONVERSION OF EURO-DOLLAR RATE
NOTES. All outstanding Euro-Dollar Rate Notes shall be converted into Base Rate
Notes, on the last day of the respective Interest Periods applicable thereto
(or, if earlier, in the case of clause 2.10(b) below, on the last day that such
Purchaser can lawfully continue to hold Euro-Dollar Rate Notes) and all pending
requests for the purchase of Euro-Dollar Rate Notes shall be disregarded, if:

                  (a) On or prior to the determination of the interest rate for
a Euro-Dollar Rate Note for any Interest Period, the Administrative Agent
determines in good faith that, by reason of circumstances affecting the
interbank Euro-Dollar market, adequate and fair means do not exist for
determining the Adjusted Euro-Dollar Rate or the Required Purchasers advise the
Administrative Agent (which shall thereupon notify the Company and the other
Purchaser


                         Nortel Note Purchase Agreement
                                       25

<PAGE>   31


Parties) that such rate would not accurately reflect the cost to the Purchasers
of holding a Euro-Dollar Rate Note for such Interest Period; or

                  (b) After the date hereof a Purchaser notifies the
Administrative Agent (which shall thereupon notify the Company and the other
Purchaser Parties) of its determination that any Regulatory Change makes it
unlawful or impossible for such Purchaser or its Euro-Dollar Purchasing Office
to purchase or hold any Euro-Dollar Rate Note, to obtain in the interbank
eurodollar market through its Euro-Dollar Purchasing Office the funds with which
to purchase any Euro-Dollar Rate Note or to comply with its obligations
hereunder in respect thereof.

         SECTION 2.11 REGULATORY CHANGES.

                  (a) Increased Costs. If, on or after the date hereof, any
Regulatory Change shall impose, modify or deem applicable any reserve, special
deposit, compulsory loan, insurance or similar requirement (other than any such
requirement with respect to any Euro-Dollar Rate Note to the extent included in
the Euro-Dollar Reserve Requirement), against, or any fees or charges in respect
of, assets held by, deposits with or other liabilities for the account of,
commitments of, advances or purchase price of Notes or principal amount of other
credit extended by, any Purchaser Party (or its Applicable Purchasing Office),
or shall impose on any Purchaser Party (or its Applicable Purchasing Office) or
on the relevant interbank market any other condition affecting any Euro-Dollar
Rate Note or any obligation to purchase Euro-Dollar Rate Notes, and the effect
of the foregoing is (i) to increase the cost to such Purchaser Party (or its
Applicable Purchasing Office) of purchasing or maintaining any Euro-Dollar Rate
Note or its Commitment in respect thereof by an amount which such Purchaser
Party deems material or (ii) to reduce the amount of any sum received or
receivable by such Purchaser Party (or its Applicable Purchasing Office)
hereunder or under any other Note Document with respect thereto by an amount
which such Purchaser Party deems material then, subject to Section 2.14(a), such
Purchaser Party shall promptly notify the Company thereof and the Company shall
from time to time pay to such Purchaser Party, within 15 days after request by
such Purchaser Party, such additional amounts as may be specified by such
Purchaser Party as sufficient to compensate such Purchaser Party for such
increased cost or reduction.

                  (b) Capital Costs. If a Regulatory Change regarding capital
adequacy has the effect of reducing the rate of return on the capital of or
maintained by any Purchaser Party or any company controlling such Purchaser
Party as a consequence of such Purchaser Party's Notes, Commitment or
obligations hereunder and other commitments of this type to a level below that
which such Purchaser Party or company could have achieved but for such
Regulatory Change (taking into account such Purchaser Party's or company's
policies with respect to capital adequacy) by an amount which such Purchaser
Party deems material, then, subject Section 2.14(a), such Purchaser Party shall
promptly notify the Company thereof and the Company shall from time to time pay
to such Purchaser Party, within 15 days after request by such Purchaser Party,
such additional amounts as may be specified by such Purchaser Party as
sufficient to compensate such Purchaser Party or company for such reduction in
return, to the extent such Purchaser Party or such company determines such
reduction to be attributable to the existence or maintenance of such Notes or
obligations for the account of the Company.


                         Nortel Note Purchase Agreement
                                       26

<PAGE>   32


         SECTION 2.12 TAXES.

                  (a) If the Company is required by Applicable Law to make any
deduction or withholding in respect of any Taxes (other than Excluded Taxes)
from any amount payable under any Note Document to the Paying Agent or to, or
for the account of, any Purchaser Party, the Company shall pay to the Paying
Agent or to, or for the account of, such Purchaser Party, on the date such
amount is payable, such additional amounts as may be necessary to ensure that
the net amounts received by it or for its account, in the aggregate, after all
applicable deductions or withholdings, shall equal the amount that the Paying
Agent or such Purchaser Party would have been entitled to receive under the Note
Documents if no deductions or withholdings were made. If the Company shall
deduct or withhold any Taxes from any payments under the Note Documents, it
shall provide to the relevant Purchaser Party for whose account such payment was
made, to the extent available to the Company, (i) a statement setting forth the
amount and type of Taxes so deducted or withheld, the applicable rate and any
other information or documentation that the Paying Agent or such Purchaser Party
may reasonably request and (ii) as promptly as possible after payment is made to
the relevant Governmental Authority, a certified copy of any original official
receipt received by the Company showing payment.

                  (b) If any Purchaser Party is required to make any payment on
account of Taxes (other than Excluded Taxes) on or in relation to any sum
received or receivable by it under any Note Document, or any liability for Taxes
(other than Excluded Taxes) in respect of any such payment is imposed, levied or
assessed against such Purchaser Party, whether or not correctly or legally
imposed, then (i) such Purchaser Party shall promptly notify the Administrative
Agent and the Company and shall provide such evidence thereof, in such form as
is reasonably specified by the Company, and such cooperation as the Company may
reasonably request, and (ii) the Company or the Paying Agent, as the case may
be, shall pay when due such additional amounts as may be necessary to ensure
that the amount received by such Purchaser Party, less any such Taxes paid,
imposed, levied or assessed, including any Taxes (other than Excluded Taxes)
imposed on such additional amounts, shall equal the amount that such Purchaser
Party would have been entitled to retain under the Note Documents in the absence
of the payment, imposition, levy or assessment of such Taxes.

                  (c) Upon the written request of the Company, each Purchaser
Party shall promptly provide to the Company, the Paying Agent, the
Administrative Agent and the Collateral Agent such form, certification
or similar documentation (each duly completed, accurate and signed) as is
required by Brazil or any other jurisdiction otherwise imposing Taxes and
specified by the Company in such request, but only if required or permitted
under Applicable Law, in order to obtain an exemption from, or reduced rate of,
deduction, payment or withholding of Taxes to which such Purchaser Party is
entitled pursuant to an applicable tax treaty or the laws of Brazil or such
other jurisdiction; provided that no Purchaser Party shall have any obligation
to provide such form, certification or similar document if, in the sole judgment
of such Purchaser Party, the provision of such form, certification or similar
document will be unduly burdensome, will require such Purchaser Party to
disclose any confidential or proprietary information or will otherwise be
disadvantageous to such Purchaser Party. Subject to the proviso in the
immediately preceding sentence, the Company shall not be required to indemnify
any Purchaser Party under Section 2.12(a) or 2.12(b) for any Taxes to the extent
that such Taxes

                         Nortel Note Purchase Agreement
                                       27



<PAGE>   33

would not be imposed but for the failure by such Purchaser Party to provide any
form, certification or similar document as required by this subsection; provided
that if a Purchaser Party that is otherwise exempt from or subject to a reduced
rate of withholding tax, becomes subject to Taxes because of its failure to
deliver a form required hereunder, the Company shall take such steps as such
Purchaser Party shall reasonably request to assist such Purchaser Party to
recover such Taxes.

                  (d) The Company hereby acknowledges and agrees that, to the
extent the rate of interest and Fees paid by or on behalf of any Company Party
in respect of any Notes subject to the [***] exceeds the rate of interest and
Fees payable to or for the account of the Purchaser of such Notes pursuant to
the terms of the related Recourse Assignment and Acceptance, such excess is a
fee payable by the Company for the account of Nortel in consideration for Nortel
providing [***] with respect to Recourse Assignments of the Notes [***]. The
Company hereby acknowledges that the portion of the interest and Fees paid by
the Company in respect of Notes subject to the [***] constituting the [***]
will be paid to the Paying Agent or to the Administrative Agent, as the case may
be, by the Company solely for the benefit of Nortel. The Administrative Agent
and each of the Purchasers hereby acknowledges and agrees that, in receiving
from the Company and paying to the Administrative Agent the [***], the Paying
Agent will be acting solely as the agent for Nortel and that, in receiving from
the Company or the Paying Agent, as the case may be, and paying to Nortel
[***], the Administrative Agent will be acting solely as the agent for Nortel.
All parties shall deduct and withhold Taxes, prepare any certificates required
hereunder and file all Tax returns, reports and statements in a manner
consistent with this Section 2.12(d).

         SECTION 2.13 COMPENSATION FOR FUNDING LOSSES. The Company shall pay to
the Administrative Agent on behalf of any Purchaser, upon demand by such
Purchaser, such amount or amounts as such Purchaser determines is or are
necessary to compensate it for any loss, cost, expense or liabilities incurred
(including any loss, cost, expense or liability incurred by reason of the
liquidation or redeployment of deposits but not for any lost profits) by it as a
result of (a) any payment, prepayment, repurchase or conversion of any
Euro-Dollar Rate Note for any reason (including by reason of a Mandatory
Repurchase, a Mandatory Partial Repurchase, an acceleration pursuant to Section
6.2 or by operation of Section 2.10) on a date other than the last day of an
Interest Period applicable to such Euro-Dollar Rate Note, or (b) any
Euro-Dollar Rate Note for any reason not being issued (other than a wrongful
failure to purchase by such Purchaser) on the date therefor determined in
accordance with the applicable provisions of this Agreement. The loss to any
Purchaser attributable to any such event shall be deemed to be an amount
determined by such Purchaser to be equal to the excess, if any, of (i) the
amount of interest that such Purchaser would pay for a deposit equal to the
principal amount of the applicable Euro-Dollar Rate Note so paid, prepaid,
repurchased, converted or not issued, as applicable, for the period from the
date of such payment, prepayment, repurchase, conversion or failure to the last
day of the then current Interest Period for such Euro-Dollar Rate Note (or, in
the case of a failure to issue, the duration of the initial Interest Period that
would have been in effect with respect to such Note) if the interest rate
payable on such deposit were equal to the Adjusted Euro-Dollar Rate for such
Interest Period, over (ii) the amount of interest that such Purchaser would earn
on such principal amount for such period if such Purchaser were to invest

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       28



<PAGE>   34

such principal amount for such period at the interest rate that would be offered
by such Purchaser (or an Affiliate of such Purchaser) for dollar deposits from
other banks in the eurodollar market at the commencement of such period.

         SECTION 2.14 CERTIFICATES REGARDING YIELD PROTECTION, ETC.

                  (a) Any request by any Purchaser Party for payment of
additional amounts pursuant to Sections 2.11, 2.12 and 2.13 shall be submitted
through the Administrative Agent and shall be accompanied by a certificate of
such Purchaser Party setting forth in reasonable detail the basis and
calculation of the amount of such request. In determining the amount of such
payment, such Purchaser Party may use such reasonable attribution or averaging
methods as it deems reasonably appropriate and practical.

                  (b) Before any Purchaser Party requests compensation under
Section 2.11 or 2.12, such Purchaser Party shall designate a different
Applicable Purchasing Office if such designation (i) will avoid the need for
such request or reduce the amount payable under such Section and (ii) will not
cause the imposition on such Purchaser Party of any additional costs or legal,
regulatory or administrative burdens deemed by such Purchaser Party to be
material or otherwise deemed by such Purchaser Party in its absolute and sole
discretion to be disadvantageous to it.

                  (c) Failure or delay on the part of any Purchaser Party to
demand compensation pursuant to Section 2.11 by submitting a certificate
requesting same in accordance with this Section 2.14 shall not constitute a
waiver of such Purchaser Party's right to demand such compensation; provided
that the Company shall not be required to compensate a Purchaser Party pursuant
to Section 2.11 for any increased costs or reductions incurred more than 270
days prior to the date that such Purchaser Party submits a certificate notifying
the Company of the Regulatory Change giving rise to such increased costs or
reductions and of such Purchaser Party's intention to claim compensation
therefor; provided further that, if the Regulatory Change giving rise to such
increased costs or reductions is retroactive, then the 270-day period referred
to above shall be extended to include the period of retroactive effect thereof.

         SECTION 2.15 APPLICABLE PURCHASING OFFICE; DISCRETION OF PURCHASERS AS
TO MANNER OF FUNDING. Each Purchaser may purchase, carry or transfer Euro-Dollar
Rate Notes at, to, or for the account of an Affiliate of the Purchaser,
provided that such Purchaser shall not be entitled to receive any greater amount
under Section 2.11 or 2.12 as a result of the transfer of any such Note than
such Purchaser would be entitled to immediately prior thereto unless (a) such
transfer occurred at a time when circumstances giving rise to the claim for such
greater amount did not exist or (b) such claim would have arisen even if such
transfer had not occurred. Notwithstanding any other provision of this
Agreement, each Purchaser shall be entitled to purchase all or any part of its
Euro-Dollar Rate Notes in any lawful manner it sees fit.

         SECTION 2.16 NO SET-OFF REGARDING SUPPLY AGREEMENT. The obligations of
the Company Parties to pay all their respective Obligations shall not be
affected by (a) any set-off, counterclaim, recoupment, deduction, abatement,
suspension, diminution, reduction, defense or other right that the Company or
any of its Subsidiaries may have against any Nortel Party for any reason
whatsoever arising under or pursuant to the Nortel Supply Agreement or otherwise

                         Nortel Note Purchase Agreement
                                       29



<PAGE>   35

relating to the purchase of goods or services from any Nortel Party, (b) any
defect in the condition, design, operation or fitness for use of, or any damage
to or loss or destruction of, any equipment, material or service provided by any
Nortel Party under the Nortel Supply Agreement, (c) any insolvency, bankruptcy,
reorganization or similar proceedings by or against the Company or any Guarantor
or affecting any of its properties, (d) any action of any Governmental Authority
or any damage to or destruction of or any taking of the Company's or any
Guarantor's property or any part thereof, (e) any change, waiver, extension,
indulgence or failure to perform or comply with, or other action or omission
herein or in the other Note Documents (except for express written amendments to
this Agreement and other Note Documents as and in the manner permitted under
this Agreement or the other Note Documents), (f) any dissolution of the Company
or any Guarantor, whether or not permitted under the Note Documents, (g) any
inability or illegality with respect to the use or ownership of the Company's or
any Guarantor's property, (h) any failure to obtain, or expiration, suspension
or other termination of, or interruption, to any required Governmental
Approvals, (i) any lack of power or authority of the Administrative Agent or any
other Purchaser Party or the Company or (j) any other event or circumstance
whatsoever, whether or not similar to any of the foregoing and whether or not
the Company or any Guarantor shall have notice or knowledge of any of the
foregoing, it being the intention of the Administrative Agent and the other
Purchaser Parties, the Company and the Guarantors that the Obligations of the
Company and the Guarantors hereunder and under the other Note Documents shall be
absolute and unconditional and shall be separate and independent covenants and
agreements and shall continue unaffected unless the requirements to pay or
perform the same shall have been amended or terminated pursuant to an express
provision hereof or of any of the other Note Documents.


                                   ARTICLE III

                             CONDITIONS TO ISSUANCE

         SECTION 3.1 CLOSING CONDITIONS. The occurrence of the Closing Date
shall be subject to satisfaction of the following conditions:

                  (a) Common Terms Agreement. The conditions to closing set
forth in Section 2.1 of the Common Terms Agreement shall have been fulfilled in
a manner satisfactory to, or waived in writing as required by Section 2.1 of the
Common Terms Agreement.

                  (b) Fees and Expenses Paid. The Company shall have paid to
the Paying Agent, to the Purchaser Parties or, in the case of expenses, to any
other Person entitled thereto (i) all Fees due on or before the Closing Date and
(ii) all expenses for which the Company shall have been billed on or before the
Closing Date to the extent such expenses are reimbursable pursuant to Section
8.1 and denominated in Reais.

                  (c) General. All other documents and legal matters in
connection with the transactions contemplated by this Agreement shall have been
delivered, executed, recorded or otherwise resolved in form and substance
satisfactory to the Administrative Agent and Nortel, and the Administrative
Agent and Nortel each shall have received all such counterpart originals or
certified copies thereof as it may request.

                         Nortel Note Purchase Agreement

                                       30



<PAGE>   36


         SECTION 3.2 CONDITIONS PRECEDENT TO EACH ISSUANCE. The obligation of
the Purchasers to purchase any Notes on any Issuance Date shall be subject to
the following conditions precedent:

                  (a) Common Terms Agreement. The conditions precedent set forth
in (i) Section 3.1 hereof shall have been satisfied; and (ii) Section 2.2 of the
Common Terms Agreement shall have been satisfied or waived in writing as
required by Section 2.2 of the Common Terms Agreement.

                  (b) Notice of Issuance. The Company shall have delivered to
the Administrative Agent, after the time the conditions set forth in Section 3.1
hereof and Section 2.2 of the Common Terms Agreement shall have been satisfied
or waived and otherwise in accordance with the applicable provisions of this
Agreement, a Notice of Issuance (or telephonic notice in lieu thereof).

                  (c) Delivery of Notes. The Company shall have delivered to the
Administrative Agent Notes payable to the respective Purchasers in the principal
amount to be purchased by them, duly executed by the Company and dated the
Issuance Date.

                  (d) Payment of Front End Fees. The use of proceeds of the
Issuance, as set forth in the Notice of Issuance, shall include, or the Company
shall otherwise have paid, all Front End Fees payable in respect of such
Issuance under the Administrative Agent's Letter.

                  (e) Issuances Prior to Completed Non-Recourse Assignment -
[***]. At all times prior to the date on which the Administrative Agent shall
have been notified of the occurrence of the [***], the obligation of any
Purchaser (other than Nortel) whose Notes are covered by [***] (a [***]) to
purchase Notes hereunder on any Issuance Date, is subject to the additional
condition that no [***] shall then exist, provided that nothing in this Section
3.2(e) shall affect the obligation of Nortel or any Purchaser, other than a
[***], to purchase Notes hereunder during the period that a [***] exists, as
specified in Section 8.6(f).

                  (f) Issuances for Interest Payments Prior to Non-Recourse
Assignment. Notwithstanding the foregoing, at any time prior to the date on
which Nortel enters into a Non-Recourse Assignment of all or any portion of its
Notes or Commitment hereunder, Issuances for the sole purpose of paying interest
due on Notes shall not be subject to any of the conditions to Issuance, other
than (i) compliance with the Total Debt to Total Capitalization and Senior Debt
to Total Capitalization ratios as required by Sections 5.6(a) and (b) of the
Common Terms Agreement after giving effect to such Issuance and any issuance of
Exchange Debt pursuant to the Exchange Debt Agreement, (ii) the absence of a
Default or Event of Default under Section 6.1(a), (b), (f), (g), (h), (i), (j),
(l), (m), (n), (p) or (q) of the Common Terms Agreement, (iii) the absence of a
Default or Event of Default under Section 6.1(c) or (d) of the Common Terms
Agreement in respect of any failure of a Company Party to comply with Section
4.3, 4.8(b), 4.9, 5.1, 5.2, 5.3, 5.6(f), 5.7, 5.8, 5.9, 5.10, 5.12 or 5.13 of
the Common Terms Agreement, (iv) the absence of (A) an acceleration of the
maturity of the Notes due to the occurrence of an Event of Default or (B) a
Mandatory Repurchase Notice having been given by the Required Purchasers as
provided in Section 2.6(a), (v) compliance with the conditions to Issuance set
forth in Sections

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       31



<PAGE>   37


2.2(a) and 2.2(e) of the Common Terms Agreement and (vi) compliance with the
conditions to Issuance set forth in Section 2.2(b) of the Common Terms Agreement
with respect to Sections 3.1, 3.2, 3.3, 3.4, 3.11, 3.21, 3.22 and 3.27. At any
time subsequent to any Non-Recourse Assignment, such Issuances shall be subject
to those conditions to Issuance generally applicable to all other Issuances
hereunder.

                  (g) Satisfaction of Conditions. Each Issuance of Notes shall
constitute a representation and warranty by the Company as of the Issuance Date
that the conditions contained in Sections 3.2(a) through (e), as modified by
Section 3.2(f), have been satisfied.


                                   ARTICLE IV

                         REPRESENTATIONS AND WARRANTIES

         The Company hereby repeats herein as of the date hereof and as of each
Issuance Date hereunder all of the representations and warranties set forth in
Article 3 of the Common Terms Agreement, which representations and warranties
are hereby incorporated herein by reference.


                                    ARTICLE V

                            COVENANTS OF THE COMPANY

         SECTION 5.1 COMMON TERMS AGREEMENT. The affirmative and negative
covenants set forth in Articles 4 and 5 of the Common Terms Agreement are hereby
incorporated by reference.

         SECTION 5.2 SYNDICATION EFFORTS.

                  (a) The Company hereby agrees to cooperate with the
Administrative Agent and Nortel in connection with two completed syndication
efforts, one aimed at achieving [***] of the Commitments and Notes and one aimed
at achieving a Non-Recourse Assignment of the Commitments and Notes (each a
"Syndication"), at such times as the Administrative Agent (upon the request of,
consultation with, and the consent of, Nortel) may elect. In connection
therewith, the Company shall provide the Administrative Agent and its legal
counsel and consultants with such information and access to their respective
officers, directors, employees, accountants, and legal counsel as may be
reasonably requested for the purpose of performing due diligence and preparing
an information memorandum or like presentation package (the "Memorandum") for
distribution to financial institutions and other Persons who may be interested
in participating in the Commitments and Notes (together with the Purchaser, the
"Syndicate"). The information requested may include, but may not be limited to,
general industry information and information concerning the Company generally,
along with historic and projected financial information of each.

                  (b) The Company agrees to make reasonable changes in this
Agreement and the other Note Documents as needed to complete the Syndications,
which changes would not be


[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       32



<PAGE>   38


adverse in any material respect to the Company and would not modify the rate or
payment terms, stated maturity or Initial Repurchase Date of the Notes.

                  (c) Prior to delivery of the Memorandum to any potential
Syndicate member, one or more knowledgeable Senior Officers of the Company shall
review the Memorandum and will provide a certificate to the Administrative Agent
and Nortel stating that, to the best of each such Senior Officer's knowledge,
the information included in the Memorandum is correct in all material respects
and does not contain any untrue statement of a material fact or omit to state
any fact necessary to make such information not materially misleading. The
Company shall be required to update the Memorandum while any Syndication is
ongoing and provide a new certificate with respect to such Memorandum as
reasonably requested by the Administrative Agent but no more frequently than
quarterly.

                  (d) The Company hereby agrees that no other major financing
for the Company or HoldCo will be syndicated by or with the cooperation of the
Company or HoldCo in the global bank markets which would jeopardize the success
of any Syndication by using up a substantial portion of the Company's credit
capacity (other than (x) a syndication of the Other Commitments and Other Notes
under the Qualcomm/Ericsson Note Purchase Agreement or the Harris Note Purchase
Agreement if Qualcomm or Harris, respectively, provides an [***] thereof in
connection with such syndication or (y) in accordance with any syndication
involving the issuance of Exchange Debt or a Qualifying Debt Offering (as
defined in the Exchange Debt Agreement) in which a portion of the proceeds are
used to prepay a principal amount of Notes in accordance with Section 2.1(f) of
the Exchange Debt Agreement, a syndication of the Other Commitments and Other
Notes under the Qualcomm/Ericsson Note Purchase Agreement in coordination with
and on a pro rata basis with the Syndication of the Notes and Commitments
hereunder) during the period beginning on the date on which the Administrative
Agent notifies the Company that it will begin Syndication and ending on the
earlier of (i) with respect to a Syndication to achieve a [***], 90 days from
the date on which such notice, in writing, was provided to the Company and with
respect to a Syndication to achieve a Non-Recourse Assignment, 120 days after
such date and (ii) full Syndication of the Commitments and Notes hereunder to
Purchasers other than Nortel or termination of such Syndication effort, provided
that if a Syndication is terminated for any reason, the Administrative Agent and
Nortel shall be permitted to reutilize the above-described time periods one
additional time each as if such terminated Syndication effort had never
occurred. Thereafter, the Company agrees to coordinate any syndicated financing
activity for its benefit or for the benefit of HoldCo in good faith with any
Syndication then being prepared by the Administrative Agent and Nortel.

         SECTION 5.3 CERTAIN REGULATORY RESTRICTIONS. The Purchaser Parties and
the Company acknowledge and agree that the Company or any Designated Repurchaser
may require certain Central Bank foreign exchange approvals in the future in
order to utilize the commercial foreign exchange markets to make remittances in
Dollars out of Brazil with respect to payments to the Administrative Agent or to
the Paying Agent not specifically identified in the related Prior Approvals
existing on the Closing Date or issued thereafter; provided that the failure to
have or receive any such approvals does not (and shall not be deemed to) limit
in any respect the Company's or such Designated Repurchaser's obligations under
the Note Documents, including

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       33



<PAGE>   39


their respective obligations to pay all amounts due hereunder and thereunder in
Dollars in the amounts and at the times provided for herein and therein.


                                   ARTICLE VI

                                EVENTS OF DEFAULT

         SECTION 6.1 EVENTS OF DEFAULT. The occurrence of(a) any one or more of
the "Events of Default" described in Article 6 of the Common Terms Agreement or
(b) any failure by the Company to comply with or observe any agreement, covenant
or obligation under Section 2.2 hereof shall constitute an event of default
(each an "Event of Default") hereunder.

         SECTION 6.2 REMEDIES.

                  (a) If an Event of Default occurs under Section 6.1(f) or
Section 6.l(g) of the Common Terms Agreement, then the Commitments shall
automatically and immediately terminate, and the obligation of the Purchaser
Parties to purchase any Note hereunder shall cease, the unpaid principal amount
of the Notes and all other Obligations shall automatically become immediately
due and payable, all without presentment, demand, protest, any additional notice
or other requirements of any kind (including notice of dishonor and notice of
intent to accelerate), all of which are hereby expressly waived by the Company.

                  (b) If an Event of Default occurs, other than under Section
6.1(f) or 6.1(g) of the Common Terms Agreement, the Administrative Agent may, or
upon written request of the Required Purchasers shall, by written notice to the
Company, declare that the Commitments are terminated, whereupon the obligation
of the Purchaser Parties to purchase any Note hereunder shall cease, and/or
declare the outstanding principal amount of the Notes and all other Obligations
to be, and the same shall thereupon become, due and payable, all without
presentment, demand, protest, any additional notice or other requirements of any
kind (including notice of dishonor and notice of intent to accelerate), all of
which are hereby expressly waived by the Company.

                  (c) Subject to the terms of Article 9 of the Common Terms
Agreements, the Agents and the other Purchaser Parties have the additional
rights and remedies set forth in the Collateral Documents and the other Note
Documents and Applicable Law upon the occurrence of an Event of Default.


                                   ARTICLE VII
                THE ADMINISTRATIVE AGENT, THE PROCEEDS COLLATERAL
                       AGENT, THE PURCHASERS AND CO-AGENTS

         SECTION 7.1 AUTHORIZATION AND ACTION.

                  (a) Each Purchaser hereby irrevocably appoints and authorizes
ABN AMRO to act as its Administrative Agent (which term for all purposes
hereunder shall include the


                         Nortel Note Purchase Agreement

                                       34


<PAGE>   40


"Nortel Facility Agent" referred to in the Common Terms Agreement) hereunder and
under the other Note Documents, to execute and deliver or accept, on its behalf,
the other Note Documents and any other documents, instruments and agreements
related thereto or hereto to take such action on its behalf under the provisions
hereof and thereof and to exercise such rights, remedies, powers and privileges
hereunder and thereunder as are delegated to the Administrative Agent by the
terms hereof and thereof, together with such rights, remedies, powers and
privileges as are reasonably incidental thereto.

                  (b) The Administrative Agent shall not have any duties or
responsibilities except those expressly set forth in the Note Documents. No duty
to act, or refrain from acting, and no other obligation, covenant,
responsibility or liability whatsoever, shall be implied on the basis of any
right, power or authority granted to the Administrative Agent or shall become
effective in the event of any temporary or partial exercise of such rights,
power or authority. The Administrative Agent shall not be required to exercise
any right, power, remedy or privilege granted to it in any Note Document, to
ascertain or inquire whether any Default or Event of Default has occurred and is
continuing, or to inspect the property (including the books and records) of the
Company or to take any other affirmative action, except as expressly provided in
Section 6.2 or elsewhere in the Note Documents, or unless requested or directed
to do so in accordance with the provisions of Section 8.3 or Article 9 of the
Common Terms Agreement.

                  (c) Without limiting the generality of the foregoing, the use
of the term "agent" in this Agreement with respect to the Administrative Agent
is not intended to connote any fiduciary or other express or implied obligation
arising under agency doctrine or any other Applicable Law; instead, such term is
used merely as a matter of market custom and is intended to create or reflect
only an administrative relationship among independent contracting parties.

                  (d) The duties of the Administrative Agent shall be mechanical
and administrative in nature. The Administrative Agent shall not have by reason
of this Agreement a fiduciary relationship in respect of any other Purchaser
Party. Except for notices, reports and other documents and information expressly
required to be furnished to the Purchaser Parties by the Administrative Agent
hereunder, the Administrative Agent shall not have any duty or responsibility to
provide any Purchaser Party with any credit or other information concerning
affairs, financial condition or business of the Company that may come into the
possession of the Administrative Agent or any of its Affiliates.

         SECTION 7.2 EXCULPATION; ADMINISTRATIVE AGENT'S RELIANCE; ETC. Neither
the Administrative Agent in its capacity as such nor any of its directors,
officers, agents, attorneys or employees shall be liable to the Company or any
other Purchaser Party for any action lawfully taken or omitted to be taken by it
or them (whether negligently or otherwise) under or in connection with any Note
Document (a) with the consent or at the request of the Required Purchasers (or,
as provided in Section 8.3, or in Article 9 of the Common Terms Agreement, all
of the Purchasers or the Specified Pari Passu Creditors (as defined below)), or
(b) in any other circumstances, except for its or their own gross negligence or
willful misconduct. The Administrative Agent makes no warranty or representation
to any other Purchaser Party and shall not be responsible to any other Purchaser
Party for any recitals, statements, warranties or representations made in, or in
connection with, any Note Document or for the execution, effectiveness,
genuineness, validity, enforceability, collectibility, or sufficiency of any
Note

                         Nortel Note Purchase Agreement

                                       35



<PAGE>   41
Document or any financial information, opinions of counsel or other documents
executed and delivered pursuant thereto, or for the financial condition of the
Company. The Administrative Agent shall not be responsible to any Purchaser for
the satisfaction of any condition specified in Article III hereof or Article 2
of the Common Terms Agreement, except receipt of items required to be delivered
to the Administrative Agent, or for the value, effectiveness, priority,
genuineness, validity, of any Collateral or any Lien thereon. The Administrative
Agent may treat the Purchaser identified in the Register as the holder of any
Note as the holder thereof until the Administrative Agent receives the related
Assignment and Acceptance signed by such Purchaser and the assignee and in form
satisfactory to the Administrative Agent. The Administrative Agent shall be
entitled to rely upon any notice, certificate or other writing believed by the
Administrative Agent to be genuine and correct and to have been signed or sent
by the proper Person or Persons. The Administrative Agent shall be entitled to
consult with legal counsel, independent public accountants and other experts
selected by the Administrative Agent and to act in reliance upon the advice of
such counsel and other experts concerning its actions and duties hereunder.

         SECTION 7.3 ADMINISTRATIVE AGENT AND AFFILIATES. The Administrative
Agent shall, in its capacity as a Purchaser, have the same rights, powers and
obligations under this Agreement and the other Note Documents as any other
Purchaser and may exercise or refrain from exercising the same as though it were
not the Administrative Agent, including the right to give or deny consent to any
action requiring consent or direction of the Required Purchasers (or, as
provided in Section 8.3, or in Article 9 of the Common Terms Agreement, all of
the Purchasers or of the Specified Pari Passu Creditors). The Administrative
Agent in its individual capacity and its Affiliates may accept deposits from,
lend money to, act as trustee under indentures of, and generally engage in any
kind of business with, the Company, any of its Subsidiaries and any Affiliate of
the Company, all as if the Administrative Agent were not the Administrative
Agent and without any duty to account therefore; to the Purchasers. The
Administrative Agent shall be entitled to receive from the Company or from the
Paying Agent its fees or portions thereof in connection with this transaction
without any liability to account therefor to any other Purchaser, except as the
Administrative Agent may have expressly agreed.

         SECTION 7.4 PURCHASER CREDIT DECISION; ACKNOWLEDGMENT OF USE OF
PROCEEDS BENEFITING NORTEL. Each Purchaser Party acknowledges that it has,
independently and without reliance upon the Administrative Agent or any other
Purchaser Party and based on such documents and information as it has deemed
appropriate, made its own credit analysis and decision to enter into this
Agreement. Each Purchaser Party also acknowledges that it will, independently
and without reliance upon the Administrative Agent or any other Purchaser Party
and based on such documents and information as it shall deem appropriate at the
time, continue to make its own credit decisions in taking or not taking action
under the Note Documents. Each Purchaser Party expressly recognizes that the
proceeds of a significant portion of the Notes are required to be used to make
payments to Nortel Parties under the Nortel Supply Agreement and expressly
agrees that Nortel, whether or not it is a Purchaser under this Agreement, shall
have the rights and obligations specified under this Agreement, all without
regard to the fact that such proceeds are or may be used for such purpose and
that the Nortel Supply Agreement exists.

                         Nortel Note Purchase Agreement

                                       36



<PAGE>   42


         SECTION 7.5 INDEMNIFICATION. The Administrative Agent shall in no event
be required to take any action under the Note Documents or in relation thereto
not expressly specified therein, unless it shall first be indemnified to its
satisfaction by the other Purchaser Parties against any and all liability and
expense that it may incur by reason of taking any such action. Each Purchaser
agrees to indemnify and hold the Administrative Agent harmless (to the extent
not promptly paid or reimbursed by the Company or, to the extent required by
Section 8.1, Nortel), ratably according to their respective Commitments (net, in
the case of Nortel, of the principal amount then outstanding of any Exchange
Debt)), from and against any and all (a) costs, expenses and other amounts
incurred by the Administrative Agent otherwise payable by the Company pursuant
to Section 8.1 and (b) Indemnified Liabilities that may be imposed on, incurred
by, or asserted against the Administrative Agent, except to the extent they
resulted from the gross negligence or willful misconduct of the Administrative
Agent. Without limitation of the foregoing, each Purchaser agrees to reimburse
the Administrative Agent promptly upon demand for its ratable share of any
out-of-pocket expenses (including reasonable counsel fees) incurred by the
Administrative Agent in connection with the administration, modification,
amendment or enforcement (whether through negotiations, legal proceedings or
otherwise) of, or legal advice in respect of rights or responsibilities under,
the Note Documents, to the extent that the Administrative Agent is not promptly
reimbursed for such expenses by the Company.

         SECTION 7.6 SUCCESSOR ADMINISTRATIVE AGENT. Subject to the penultimate
sentence of this Section 7.6, the Administrative Agent may resign at any time as
Administrative Agent under the Note Documents by giving 30 days' written notice
thereof to the Purchasers, Nortel and the Company. Upon any such resignation,
the Required Purchasers shall have the right to appoint a successor
Administrative Agent, which shall be reasonably satisfactory to Nortel, unless
the [***] shall have occurred, and the Company, unless a Default or Event of
Default shall then exist. If no successor Administrative Agent shall have been
so appointed by the Required Purchasers, and shall have accepted such
appointment, within 60 days after the retiring Administrative Agent's notice of
resignation, then the retiring Administrative Agent may, on behalf of the other
Purchaser Parties, appoint a successor Administrative Agent, which shall (i) be
a financial institution or a branch or agency of a financial institution,
organized or licensed to do business under the laws of the United States of
America or any State thereof and (ii) be entitled to charge customary
administrative agency fees. Upon the acceptance of any appointment as the
Administrative Agent by a successor Administrative Agent, such successor
Administrative Agent shall thereupon succeed to and become vested with all the
rights, powers, privileges and duties of the retiring Administrative Agent, and
the retiring Administrative Agent shall be discharged of its duties and
obligations under the Note Documents. Upon any retiring Administrative Agent's
resignation, the provisions of this Article VII (as well as other expense
reimbursement, indemnification and exculpatory provisions in the other Note
Documents) shall continue in effect for its benefit as to any actions taken or
omitted by it while it was Administrative Agent.

         SECTION 7.7 PURCHASER PARTIES. The provisions of this Article VII are
solely for the benefit of the Administrative Agent and the other Purchaser
Parties and the Company shall not have any rights to rely on or enforce any of
the provisions hereof (except that (a) the provisions of Section 7.6, unless a
Default or an Event of Default shall then exist, and of Sections 7.8(f) and
7.9(a) are also for the benefit of the Company and (b) the Company is entitled
to rely on any

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement

                                       37



<PAGE>   43


release executed by the Administrative Agent as authorized by Section 7.8). In
performing its functions and duties under the Note Documents, except as
expressly otherwise provided in Section 8.6(c), the Administrative Agent shall
act solely as Administrative Agent of the Purchasers and does not assume and
shall not be deemed to have assumed any obligation toward or relationship of
agency or trust with or for the Company.

         SECTION 7.8 COLLATERAL AND GUARANTY MATTERS.

                  (a) The Administrative Agent is hereby authorized to act as,
or to appoint and authorize any Person or Person specified herein to act as,
and, pursuant to Article 1288 of the Brazilian Civil Code, does hereby appoint
and authorize LaSalle Bank National Association to act as, attorney-in-fact for
purposes of Article 1317 of the Brazilian Civil Code and Proceeds Collateral
Agent in respect of the Proceeds Account Pledge Agreement on behalf of the
Purchaser Parties under this Agreement and the Proceeds Account Pledge
Agreement, subject to the terms and conditions set forth herein and therein.
Unless the context otherwise requires, all references in this Article VII to the
Administrative Agent shall be deemed to include the Proceeds Collateral Agent.
LaSalle Bank National Association, by execution of the Proceeds Account Pledge
Agreement, shall accept such appointment and upon such acceptance shall be
entitled to exercise such rights, remedies, powers and privileges hereunder,
thereunder and under the other Note Documents as are delegated to the Proceeds
Collateral Agent by the terms hereof and thereof, together with such rights,
remedies, powers and privileges as are reasonably incidental thereto. The
Administrative Agent is further hereby authorized to act as, or to appoint and
authorize the Person or Persons specified in the Common Terms Agreement to act
as, Collateral Agent on behalf of the Purchaser Parties under the Common Terms
Agreement, the Pari Passu Collateral Documents and the other Note Documents, as
applicable, subject to the terms and conditions set forth in such documents.

                  (b) Except for any matters expressly subject to the consent or
approval of the Administrative Agent under the Note Documents, the
Administrative Agent shall not, without the prior approval of the Required
Purchasers (or, as provided in Section 8.3, or Article 9 of the Common Terms
Agreement, all of the Purchasers or a specified percentage of the Other
Purchasers under any or each of the Other Note Purchase Agreements or the Pari
Passu Purchasers under any or each tranche of Pari Passu Debt (the "Specified
Pari Passu Creditors")) consent to any departure by the Company from the terms
of, waive any default or otherwise amend this Agreement or any other Note
Documents. The Administrative Agent will not take any action contrary to the
written direction of the Required Purchasers (or, as provided in Section 8.3, or
Article 9 of the Common Terms Agreement, all of the Purchasers or the Specified
Pari Passu Creditors), will take any lawful action not contrary to the
provisions of the Note Documents prescribed in written instructions of the
Required Purchasers (or, as provided in Section 8.3, or Article 9 of the Common
Terms Agreement, all of the Purchasers or the Specified Pari Passu Creditors)
and, as to any matters not expressly provided for by the Note Documents
(including enforcement or collection), may decline to take any action, except
upon the written instructions of the Required Purchasers (or, as provided in
Section 8.3, or Article 9 of the Common Terms Agreement, all of the Purchasers
or the Specified Pan Passu Creditors); provided, however, that neither the
Administrative Agent nor the Proceeds Collateral Agent may fail to take any
action with respect to any amendment to the Proceeds Account Pledge

                         Nortel Note Purchase Agreement

                                       38



<PAGE>   44



Agreement pursuant to Section 4.10 of the Common Terms Agreement, whether or not
specifically requested or directed to do so, that is required to be taken by the
terms of this Agreement or any other Note Document. If such instructions are
requested by the Administrative Agent reasonably promptly, the Administrative
Agent shall be absolutely entitled to refrain from taking any action and shall
not have any liability to the Company or any of its Subsidiaries or any other
Purchaser Party for refraining from taking any action until it shall have
received such instructions; provided, however, that the Administrative Agent
shall in no event be required to take or refrain from taking any action that
would, in the Administrative Agent's opinion, (i) be contrary to the provisions
of any Note Document or Applicable Law or (ii) be reasonably likely to result in
material liability to the Administrative Agent.

                  (c) The Purchasers hereby irrevocably authorize the
Administrative Agent to, or to join with the Collateral Agent, in its
discretion, in any release of any Lien held by the Collateral Agent upon any
Common Collateral (i) from and after the day of termination of any Pari Passu
Collateral Document pursuant to the terms thereof; (ii) constituting property
being sold or disposed of if the Company certifies to the Administrative Agent
and the Collateral Agent that the sale or disposition is permitted under the
relevant Pari Passu Collateral Document and Section 5.8 of the Common Terms
Agreement is being complied with in connection therewith (and the Administrative
Agent and the Collateral Agent may rely conclusively on any such certificate,
without further inquiry, unless notified to the contrary by the Required
Purchasers); or (iii) approved, authorized or ratified in writing by all
Purchaser Parties (or the Specified Pari Passu Creditors) in accordance with
Section 8.3, or Article 9 of the Common Terms Agreement; provided, however, that
(A) the Administrative Agent shall not be required to execute any such documents
on terms that create any obligation or entail any consequence other than the
release of such Liens without recourse or warranty, and (B) such release shall
not in any manner discharge, affect or impair the Obligations, the Guaranties or
any other Liens upon (or obligations of the Company in respect of) the assets
retained by the Company, including the proceeds of any Asset Disposition, each
of which shall continue to constitute part of the Common Collateral to the
extent provided in the Pari Passu Collateral Documents. Upon request by the
Administrative Agent at any time, the other Purchaser Parties will confirm in
writing the Administrative Agent's and Collateral Agent's authority to release
particular types or items of Common Collateral pursuant to this Section 7.8(c).


                  (d) The Purchasers hereby irrevocably authorize the
Administrative Agent to, or to join with the Proceeds Collateral Agent, in its
discretion, in any release of any Lien held by the Proceeds Collateral Agent
upon any collateral under the Proceeds Account Pledge Agreement (i) from and
after the day of termination of the Proceeds Account Pledge Agreement pursuant
to the terms thereof; (ii) constituting Cash Equivalents held in the Proceeds
Account being sold or disposed of if the Company certifies to Nortel, the
Administrative Agent and the Proceeds Collateral Agent that the proceeds of such
sale or disposition are being used for purposes permitted by Section 2.2,
including, to the extent not used for any purpose set forth in Section
2.2(a)(i), (ii) or (iii), any purpose set forth in clause (C) of the proviso to
Section 2.2(a) (and the Administrative Agent and the Proceeds Collateral Agent
may rely conclusively on any such certificate, without further inquiry, unless
notified to the contrary by Nortel); or (iii) approved, authorized or ratified
in writing by all Purchaser Parties in accordance with Section 8.3; provided,
however, that (A) neither the Administrative Agent nor the Proceeds Collateral

                         Nortel Note Purchase Agreement

                                       39




<PAGE>   45




Agent shall be required to execute any such documents on terms that create any
obligation or entail any consequence other than the release of such Liens
without recourse or warranty, and (B) such release shall not in any manner
discharge, affect or impair the Obligations, the Guaranties or any other Liens
upon (or obligations of the Company in respect of) the cash and Cash Equivalents
retained by the Company, including the proceeds of any sale of Cash Equivalents
held in the Proceeds Account, each of which shall continue to constitute part of
the collateral under the Proceeds Account Agreement to the extent provided
therein. Upon request by the Administrative Agent or the Proceeds Collateral
Agent at any time, the other Purchaser Parties will confirm in writing the
Administrative Agent's and Proceeds Account Agent's authority to release
particular types or items of collateral under the Proceeds Account Pledge
Agreement pursuant to this Section 7.8(d).

                  (e) Except as specifically otherwise provided in the Proceeds
Account Pledge Agreement, the Proceeds Collateral Agent is hereby authorized on
behalf of all of the Purchasers, without assumption of any duty or obligation in
respect of and without the necessity of any notice to or further consent from
any other Purchaser Party, to take any action with respect to the Proceeds
Account Pledge Agreement or any collateral thereunder that may be necessary to
perfect and maintain perfected the Proceeds Collateral Agent's Liens upon such
collateral. Without limiting or limitation of the foregoing, the Proceeds
Collateral Agent shall promptly take any actions as are reasonably required to
enable the Company to effectuate the provisions of Section 4.10 of the Common
Terms Agreement, including reviewing as to form and substance any proposed
amendment to the Proceeds Account Pledge Agreement prepared pursuant thereto and
consenting to and executing any such amendment in such manner as may be
necessary to permit such amendment to be filed, recorded or registered with any
Governmental Authority.

                  (f) Neither the Administrative Agent, the Proceeds Collateral
Agent nor the Collateral Agent shall have any obligation whatsoever to any other
Purchaser Party or other Person to assure that the Collateral exists or is owned
by the Company or (except as otherwise expressly required by the Collateral
Documents) is cared for, protected or insured, or that the Liens of the Proceeds
Collateral Agent or Collateral Agent, as the case may be, thereunder have been
properly created, perfected, protected or enforced or are entitled to any
particular priority.

                  (g) Except as otherwise provided in the Pari Passu Financing
Documents, the Collateral Agent, in its discretion, may act in any manner it may
deem appropriate in respect of the Collateral, and except as otherwise provided
in the Note Documents, the Proceeds Collateral Agent, in its discretion, may act
in any manner it may deem appropriate in respect of the collateral under the
Proceeds Account Pledge Agreement. Neither the Administrative Agent, the
Proceeds Collateral Agent nor the Collateral Agent shall have any duty or
liability whatsoever with respect thereto to any other Purchaser Party.

         SECTION 7.9 PAYMENTS; AVAILABILITY OF FUNDS; CERTAIN NOTICES.

                  (a) If the Administrative Agent shall fail to deliver to any
other Purchaser Party its share of any payment received from the Paying Agent or
the Company, as the case may be, as and when required by Section 2.8, neither
the Paying Agent nor the Company shall have any liability therefor and the
Administrative Agent shall pay to such Purchaser Party its share of such payment
together with interest on such amount at the Federal Funds Rate, for each day
from

                         Nortel Note Purchase Agreement

                                       40


<PAGE>   46



the date such amount was required to be paid to such Purchaser Party until the
date the Administrative Agent pays such amount to such Purchaser Party,
calculated as set forth in Section 2.3(d).

                  (b) Unless (i) the Administrative Agent shall have been
notified by a Purchaser Party prior to the Issuance Date of any Note or (ii) the
Administrative Agent shall have been notified by the Company prior to the date
on which the Company is required to make any payment hereunder (including, in
the case of the Company, any payment in satisfaction of its indemnification
obligations hereunder or under the Common Terms Agreement) that such Purchaser
Party or the Company, as the case may be (the "Obligated Party"), does not
intend to make available to the Administrative Agent the Obligated Party's
purchase price for such Note or such payment, the Administrative Agent may
assume that the Obligated Party will make such amount available to the
Administrative Agent on such date and the Administrative Agent may, in reliance
upon such assumption (but shall not be required to), make available to the
Company (in the case of an Issuance) or the Purchaser Parties (in the case of a
payment or repurchase by the Company or a Designated Repurchaser) a
corresponding amount. If such corresponding amount is not in fact made available
to the Administrative Agent by the Obligated Party, the Administrative Agent
shall be entitled to recover such amount on demand from the Obligated Party (or,
in the case of an Issuance, if the Purchaser Party that is the Obligated Party
fails to pay such amount forthwith upon such demand, from the Company). Such
amount shall be payable together with interest thereon from the day on which
such corresponding amount was made available by the Administrative Agent to the
Purchaser Party or the Company, as applicable, to the date of payment by the
Obligated Party (or the Company pursuant to the parenthetical clause of the
preceding sentence), at a rate of interest equal to (A) in the case of any
payment by any other Purchaser Party, the Federal Funds Rate, and (B) in the
case of any payment by the Company, the interest rate applicable to the Note.

                  (c) The Administrative Agent shall promptly notify the
Purchaser Parties telephonically or by facsimile of each Interest Period chosen
by the Company (or any automatic continuation of any Euro-Dollar Rate Note
pursuant to Section 2.3(c)(iv)), the Euro-Dollar Rate for each Interest Period
(and the relevant interest rate), the date of any expected payment and all other
material notices transmitted by the Company.

         SECTION 7.10 OBLIGATIONS OF PURCHASER PARTIES SEVERAL; RIGHT TO
INITIATE JUDICIAL PROCEEDINGS.

                  (a) Each Purchaser Party's obligations hereunder are several,
and not joint or joint and several. The failure of any Purchaser Party to
purchase any Note or otherwise to perform its obligations hereunder will not
increase the obligations of any other Purchaser Party. Notwithstanding the
foregoing, any Purchaser may assume, but shall have no obligation to any Person
to assume, any non-performing Purchaser's obligation to purchase a Note. Nothing
contained in this Agreement and no action taken by the Administrative Agent or
any other Purchaser Party pursuant to this Agreement shall be deemed to
constitute the Administrative Agent and any other Purchaser Party to be a
partnership, an association, a joint venture or any other kind of entity.


                         Nortel Note Purchase Agreement

                                       41


<PAGE>   47



                  (b) Subject to the provisions of Section 9.3 of the Common
Terms Agreement, the Collateral Agent has the right and power to institute and
maintain such suits and proceedings as it may deem appropriate to protect and
enforce the rights vested in it by the Common Terms Agreement and the Pari Passu
Collateral Documents and may, either after entry or without entry, proceed by
suit or suits at law or in equity to enforce such rights and to foreclose upon
Common Collateral and to sell all or, from time to time, any of the Common
Collateral as permitted by the Pari Passu Collateral Documents; provided,
however, that the Collateral Agent shall not be required to exercise any
discretionary power granted to the Collateral Agent in the Common Terms
Agreement or the Pari Passu Collateral Documents.

                  (c) Subject to the provisions of Section 7.8(b), the Proceeds
Collateral Agent has the right and power to institute and maintain such suits
and proceedings as it may deem appropriate to protect and enforce the rights
vested in it by this Agreement and the Proceeds Account Pledge Agreements and
may, either after entry or without entry, proceed by suit or suits at law or in
equity to enforce such rights and to foreclose upon the collateral under the
Proceeds Account Pledge Agreement and to sell all or, from time to time, any of
the collateral under the Proceeds Account Pledge Agreement as permitted thereby;
provided, however, that the Proceeds Collateral Agent shall not be required to
exercise any discretionary power granted to the Administrative Agent herein or
in the Proceeds Account Pledge Agreements.

                  (d) Subject to the provisions of Section 8.3, the
Administrative Agent has the right and power to institute and maintain such
suits and proceedings as it may deem appropriate to protect and enforce the
rights vested in it by this Agreement and the other Note Documents and may,
either after entry or without entry, proceed by suit or suits at law or in
equity to enforce such rights.

         SECTION 7.11 CO-AGENTS. No Co-Agent, in such capacity, shall have any
right, power, obligation, liability, duty or responsibility whatsoever under the
Note Documents to, and no Co-Agent shall be deemed to have any fiduciary
relationship with, any Purchaser. Each Purchaser acknowledges that it has not
relied, and will not rely, on any of the Co-Agents in deciding to enter into
this Agreement or in taking or not taking any action hereunder. Each of the
Co-Agents shall be entitled to all immunities and indemnities of the
Administrative Agent provided in this Article VII, mutatis mutandis.

         SECTION 7.12 GLOBAL NOTE.

                  (a) Subject to Section 7.12(b), at the option of the Required
Purchasers, each Issuance of the Notes shall initially be represented by one or
more Notes in registered, global form without interest coupons (a "Global
Note"). Each Global Note shall be deposited upon issuance with the
Administrative Agent as custodian for the Purchasers and registered in the name
of the Administrative Agent, in each case for credit to an account of and as the
designee of a Purchaser.

                  (b) Notwithstanding Section 7.12(a), upon the occurrence and
during the continuance of any Event of Default, each Global Note shall be
exchanged by the Company upon the request of any Purchaser for Notes to be held
by such Purchasers in the respective principal amount of such Purchaser's pro
rata portion of such Global Note.

                         Nortel Note Purchase Agreement
                                       42
<PAGE>   48



            (c) If any Global Note is to be exchanged for other Notes or
canceled in whole, it shall be surrendered by or on behalf of the Administrative
Agent for exchange or cancellation as provided in this Section 7.12. If any
Global Note is to be exchanged for other Notes or canceled in part, or if
another Note is to be exchanged in whole or in part for a beneficial interest in
any Global Note, then either (i) such Global Note shall be so surrendered for
exchange or cancellation as provided in this Section 7.12 or (ii) the principal
amount thereof shall be reduced or increased by an amount equal to the portion
thereof to be so exchanged or canceled, or equal to the principal amount of such
other Note to be exchanged for a beneficial interest therein, as the case may
be, by means of an appropriate adjustment made in the Register (as defined
below). Upon any such surrender or adjustment of a Global Note, the Company
shall deliver any Notes issuable in exchange for such Global Note (or any
portion thereof) to or upon the order of, and registered in such names as may be
directed by, the Administrative Agent.

            (d) Every Note delivered upon registration of transfer of, or in
exchange for or in lieu of, a Global Note or any portion thereof, whether
pursuant to this Section 7.12 or otherwise, shall be delivered in the form of,
and shall be, a Global Note, unless such Note is registered in the name of a
Person other than the Administrative Agent.

            (e) Nothing in this Section 7.12, or in the form of any Global Note,
shall vitiate the several nature of the agreements to purchase and obligations
of the Purchasers set forth in Article II.

     SECTION 7.13 COMMON TERMS AGREEMENT; PAYING AGENCY AGREEMENT.

           (a) Each Purchaser Party hereby approves the form of the Common Terms
Agreement and the other Note Documents attached as exhibits to the Common Terms
Agreement and hereby authorizes each of the Administrative Agent and the
Collateral Agent on its behalf to accept from the Company and execute and
deliver as Administrative Agent or Collateral Agent, as applicable, and on
behalf of the Purchasers, the Common Terms Agreement and other Note Documents in
substantially the form of such exhibits, with such changes, additions or
deletions as the Administrative Agent and Collateral Agent, in their reasonable
discretion, may approve as reasonably necessary or appropriate, such approval to
be conclusively evidenced by the Administrative Agent's and Collateral Agent's
acceptance or execution thereof. Without limitation, each Purchaser agrees to be
bound by the Common Terms Agreement, any amendment thereto adopted in accordance
with the terms thereof and by any notices that the Administrative Agent may
deliver thereunder on the Purchasers' behalf. Each Purchaser Party also
authorizes the Administrative Agent, the Proceeds Collateral Agent and the
Collateral Agent to accept, or execute and deliver, such additional documents
(including financing statements, opinions, certificates and other documents in
form and substance satisfactory to the Administrative Agent, the Proceeds
Collateral Agent and the Collateral Agent, in their discretion) in connection
with the closing pursuant to Section 3.1 hereof or Section 2.1 of the Common
Terms Agreement, upon any Issuance Date pursuant to Section 3.2 hereof or
Section 2.2 of the Common Terms Agreement, or any subsequent closing for the
pledge of any additional Collateral or any additional Guaranties as the
Administrative Agent, the Proceeds Collateral Agent or the Collateral Agent, in
its respective reasonable discretion, may approve, such approval to be
conclusively evidenced by the Administrative Agent's, the Proceeds Collateral
Agent's or Collateral Agent's acceptance or execution thereof.

                         Nortel Note Purchase Agreement
                                       43
<PAGE>   49




            (b) Each Purchaser Party hereby approves the form of the Paying
Agency Agreement and hereby authorizes the Administrative Agent on its behalf to
accept from the Company and execute and deliver as Administrative Agent on
behalf of the Purchasers the Paying Agency Agreement in substantially the form
presented to such Purchaser Party, with such changes, additions or deletions as
the Administrative Agent, in its reasonable discretion, may approve as
reasonably necessary or appropriate, such approval to be conclusively evidenced
by the Administrative Agent's acceptance or execution thereof. Without
limitation, each Purchaser agrees to be bound by the Paying Agency Agreement,
any amendment thereto adopted in accordance with the terms hereof and by any
notices that the Administrative Agent may deliver thereunder on the Purchasers'
behalf.


                                  ARTICLE VIII

                                  MISCELLANEOUS

     SECTION 8.1 EXPENSES. The Company shall pay promptly after demand:

            (a) any and all reasonable out-of-pocket expenses incurred by any
Nortel Party through the Closing Date associated with the performance of any due
diligence review and the preparation, negotiation, execution and delivery of the
Note Documents, including the reasonable fees, disbursements and other charges
of one firm of Nortel's outside counsel in each of the United States of America
and Brazil, in each case whether or not the Closing Date occurs; provided that
(i) the aggregate amount payable under this clause (a) through the Closing Date,
excluding legal fees and disbursements, will not exceed $400,000, and (ii) this
clause (a) shall not be applicable in respect of any expenses incurred by Nortel
at any time after the [***];

            (b) any and all out of pocket expenses of the Administrative Agent
and Nortel with respect to Syndication of this Agreement and the facilities
hereunder, including printing, legal and travel expenses (but not including any
fees or other charges of legal counsel to the Administrative Agent incurred at
any time prior to the Closing Date);

            (c) any and all reasonable out-of-pocket expenses incurred by any
Nortel Party (or, after the [***], by the Administrative Agent or the Proceeds
Collateral Agent) after the Closing Date associated with the administration of
the Note Documents and any waiver or amendment of the Note Documents (including
the execution and delivery of additional Collateral Documents as required by the
Common Terms Agreement), including reasonable fees, disbursements and other
charges of one firm of Nortel's (or the Administrative Agent's, as the case may
be) outside counsel in each the United States of America and Brazil; and

            (d) any and all costs and expenses (including fees and disbursements
of in-house and other attorneys, appraisers, consultants and other experts)
incurred by the Purchaser Parties (including, at any time prior to the [***],
Nortel), after an actual or alleged Default or an Event of Default, in any
workout, restructuring or similar arrangements, or in connection with the
protection, preservation, exercise or enforcement of any of the terms of the
Note Documents, or in connection with any foreclosure, collection or bankruptcy
proceedings.

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       44
<PAGE>   50


Notwithstanding the foregoing, to the extent the Company shall have been billed
on or before the Closing Date for any amounts under paragraph (a) and (b) above,
and such expenses are denominated in a currency other than in Reais, the Company
shall pay such expenses within 90 days after the Closing Date.

     SECTION 8.2 INDEMNITY. The Purchaser Parties under this Agreement shall be
indemnified to the extent of and subject to the terms and conditions set forth
in Section 10.2 of the Common Terms Agreement. Section 10.2 of the Common Terms
Agreement is hereby incorporated herein by reference, provided that all
references therein to "this Agreement" shall be read as being to this Agreement
and all references therein to the "Pari Passu Creditor Parties" shall be read as
being to the Purchaser Parties under this Agreement.

     SECTION 8.3 WAIVERS: Amendments in Writing.

            (a) No amendment of any provision of this Agreement, of the Notes or
any other Note Document or of the Paying Agency Agreement (including, in each
case, a waiver thereof or consent relating thereto) shall be effective unless
the same shall be in writing and signed or consented to by the Administrative
Agent, Nortel (unless the [***] shall have occurred), the Required Purchasers,
the Company, each Guarantor and, to the extent required by Article 9 of the
Common Terms Agreement, the Specified Pari Passu Creditors. Notwithstanding the
foregoing:

               (i) No amendment that has the effect of (A) reducing the rate or
            amount, or extending the stated maturity or due date, of any amount
            payable by any Company Party or any Designated Repurchaser to any
            Purchaser Party under the Note Documents (including the amount
            payable pursuant to any Mandatory Repurchase or Mandatory Partial
            Repurchase or in satisfaction of any indemnification obligation
            arising under Section 2.8(b)), (B) increasing the amount, or
            extending the stated termination or reduction date, of any
            Commitment of any Purchaser, or subjecting any Purchaser Party to
            any additional obligation to extend credit, (C) permitting the
            creation of any Lien ranking prior to or on a parity with the Lien
            of any Collateral Document (other than a "Pari Passu Lien" securing
            "Other Pari Passu Debt," each as defined on the date hereof in the
            Common Terms Agreement), subordinating the Lien of any Collateral
            Document or releasing any part of the Collateral (except as
            permitted under the Note Documents on the date hereof) or depriving
            any Purchaser Party of the security afforded by the Lien of any
            Collateral Document, (D) [***] (except as permitted under the Note
            Documents), (E) amending or waiving Section 4.8(b), 4.9 or 5.12 of
            the Common Terms Agreement in a manner adverse to the interests of
            the Purchaser Parties, (F) changing Section 2.9 hereof, this Section
            8.3 or the definition of the term "Initial Repurchase Date,"
            "Required Purchasers" or "Specified Pari Passu Creditors," (G)
            amending or waiving any material provision of the Paying Agency
            Agreement in any respect, including any modification to any
            provisions regarding the time or method of payment thereunder, the
            availability of remedies to the Purchaser Parties thereunder or the
            ability of the Paying Agent to assign (including by operation of
            law) its obligations thereunder, or (H) consenting to the assignment
            by the Paying Agent (including by operation of law) of its
            obligations under the Paying Agency Agreement or to the selection by
            the Company of a successor Paying

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       45

<PAGE>   51

          Agent in accordance with the terms of the Paying Agency Agreement
          shall be effective unless the same shall be signed by or on behalf of
          all of the Purchasers or, in the case of any amendment referred to in
          clause (A) or (B) all of the Purchasers directly affected thereby;

               (ii) No amendment that has the effect of (A) increasing the
          duties or obligations of the Administrative Agent, (B) increasing the
          standard of care or performance required on the part of the
          Administrative Agent, or (C) reducing or eliminating the indemnities
          or immunities to which the Administrative Agent is entitled (including
          any amendment of this Section 8.3), shall be effective unless the same
          shall be signed and consented to by the Administrative Agent;

               (iii) No amendment that has the effect of (A) increasing the
          duties or obligations of the Proceeds Collateral Agent, (B) increasing
          the standard of care or performance required on the part of the
          Proceeds Collateral Agent, or (C) reducing or eliminating the
          indemnities or immunities to which the Proceeds Collateral Agent is
          entitled (including any amendment of this Section 8.3), shall be
          effective unless the same shall be signed and consented to by the
          Proceeds Collateral Agent; and

               (iv) No amendment of Section 2.2, Section 2.5, Section 8.6 or
          this Section 8.3(a) shall be effective unless the same shall be signed
          and consented to by Nortel.

               (v) All amendments to the Proceeds Account Pledge Agreement as
          are required by Section 4.10 of the Common Terms Agreement and all
          amendments to the Proceeds Account Pledge Agreement for the purpose of
          removing and naming a successor to any Person designated as the
          depositary thereunder shall be in form and substance satisfactory to
          the Proceeds Collateral Agent, shall be consistent with the provisions
          of such Section 4.10 of the Common Terms Agreement and shall not
          require the consent of any Person other than (I) the Proceeds
          Collateral Agent, (II) the Company and (III) the Person designated as
          the depositary and, if applicable, the successor to such Person.

            (b) Any waiver or consent shall be effective only in the specific
instance and for the specific purpose for which given. No notice to or demand on
the Company in any case shall entitle the Company to any other or further notice
or demand in similar or other circumstances. Any amendment effected in
accordance with this Section 8.3 shall be binding upon each present and future
Purchaser Party and the Company.

            SECTION 8.4 CUMULATIVE REMEDIES; FAILURE OR DELAY. The rights and
remedies provided for under this Agreement are cumulative and are not exclusive
of any rights and remedies that may be available to the Purchaser Parties under
Applicable Law or otherwise. No failure or delay on the part of any Purchaser
Party in the exercise of any power, right or remedy under the Note Documents
shall impair such power, right or remedy or operate as a waiver thereof, nor
shall any single or partial exercise of any such power, right or remedy preclude
other or further exercise thereof or of any other power, right or remedy.


                         Nortel Note Purchase Agreement
                                       46
<PAGE>   52


            SECTION 8.5 NOTICES, ETC. All notices and other communications under
this Agreement shall be in writing and (except for financial statements, other
related informational documents and routine communications, which may be sent by
first-class mail, postage prepaid) shall be personally delivered or sent by
prepaid courier, by overnight, registered or certified mail (postage prepaid),
or by facsimile, and shall be deemed given when received by the intended
recipient thereof. Unless otherwise specified in a notice sent or delivered in
accordance with this Section 8.5, all notices and other communications shall be
given to the parties hereto at their respective addresses (or to their
respective facsimile numbers) indicated in Schedule 1.1(b) (in the case of the
Purchaser Parties) or Schedule 10.4 of the Common Terms Agreement (in the case
of the Company).

            SECTION 8.6 SUCCESSORS AND ASSIGNS; ETC.

            (a) This Agreement shall be binding upon and inure to the benefit of
the parties hereto and their respective successors and permitted assigns. The
Company may not assign or transfer any interest hereunder without the prior
written consent of each Purchaser Party.

            (b) Upon the earlier of January 1, 2000 or the Commercial Launch
Date (or, in the case of any [***], at any time), each Purchaser shall have the
right at any time to assign (an "Assignment") all or any portion of such
Purchaser's Commitments or Notes (or both) to one or more Eligible Assignees;
provided, however, that (i) unless otherwise agreed by the Administrative Agent,
each Assignment shall be of a constant, and not a varying, percentage of all of
the assigning Purchaser's rights and obligations with respect to each of the
assigned Commitments of such Purchaser and related rights and obligations under
this Agreement and the other Note Documents (it being understood that a
Purchaser may separately assign all or any portion of each of its Commitments or
its Notes, or both); (ii) unless a Default or Event of Default then exists, no
Assignment shall be to a Person that is a provider of telecommunications
services in Brazil or an Affiliate of such provider; (iii) the parties to the
Assignment shall execute and deliver to the Administrative Agent either (x) an
assignment and acceptance substantially in the form of Exhibit G-1 (a
"Non-Recourse Assignment and Acceptance") pursuant to which such Assignment will
not carry with it any rights [***] that applied to Notes or Commitment assigned
or (y) an assignment and acceptance substantially in the form of Exhibit G-2 (a
"Recourse Assignment and Acceptance") (iv) the assignee shall pay to the
Administrative Agent a processing and recordation fee of $3,500; (v) no
Assignment shall be effective for any purpose unless and until the
Administrative Agent accepts such Assignment and makes an appropriate entry
thereof in the Register; and (vi) each Assignment prior to the [***] shall (A)
require the consent of Nortel (which shall not be unreasonably withheld) and (B)
if the Assignment is pursuant to a Recourse Assignment and Acceptance, carry
with it the rights [***] that applied to the Notes or Commitment assigned,
provided the assignee agrees in the Recourse Assignment and Acceptance to be
bound by the terms and conditions of the [***]. Upon satisfaction of the
conditions in clauses (i) through (iv) and (vi) of the proviso to the
immediately preceding sentence with respect to any proposed Assignment, the
Administrative Agent shall accept the Assignment, make appropriate entries
thereof in the Register and send notice thereof to the Company and all other
Purchaser Parties. Prior to the [***], such notice shall also

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       47
<PAGE>   53


be given to Nortel and the Administrative Agent shall note in the Register, and
notify Nortel, whether such Assignment is intended to be a [***] and, if so,
whether the conditions in clause (vi) were satisfied in respect of such
Assignment. From and after the date on which the conditions in the foregoing
clauses (i) through (vi) and in the Assignment and Acceptance have been
satisfied, the assignee shall be a "Purchaser" hereunder and, to the extent that
rights and obligations hereunder have been assigned to it, shall have the rights
and obligations of the assigning Purchaser hereunder, and the assigning
Purchaser shall, to the extent that rights and obligations hereunder have been
assigned by it, relinquish its rights and be released from its obligations under
this Agreement (and, in the case of an Assignment covering all or the remaining
portion of the assigning Purchaser's rights and obligations under this
Agreement, cease to be a party hereto); provided that all rights of the
assigning Purchaser under Section 8.2 (and any indemnification provisions
contained in the other Note Documents) shall survive any Assignment of all other
rights and obligations of such Purchaser.

            (c) The Administrative Agent, which for purposes of this Section
8.6(c) only shall be deemed to act as agent of the Company, shall maintain at
the Administrative Agent's Office a copy of each Assignment and Acceptance
delivered to it and a register (the "Register") for the recordation of the names
of the Purchaser Parties and their respective Commitments and the principal
amounts of their respective Notes. The entries in the Register shall be
conclusive as against the Company and each Purchaser Party, in the absence of
manifest error, notwithstanding notice to the contrary. The Register shall be
available for inspection by the Company or any Purchaser Party at any reasonable
time and from time to time upon reasonable prior notice. Prior to the due
presentment for registration of transfer of any Note, the Company and the
Administrative Agent shall treat the Person in whose name such Note is
registered (or, if any Note is a Global Note, by whom a beneficial interest in
any such Note is held) as the owner of such Note and all Notes evidenced thereby
for the purpose of receiving all payments thereon and for all other purposes,
notwithstanding any notice to the contrary.

            (d) Each Purchaser shall have the right at any time to grant or sell
participations (each, a "Participation") in all or any portion of such
Purchaser's Commitments and Notes to one or more banks or other institutions,
subject to the terms and conditions set forth in this Section 8.6(d) and the
terms of any [***]. If any Purchaser sells or grants a Participation, (i) such
Purchaser shall make and receive all payments for the account of its
participant, including payments to Nortel [***], (ii) such Purchaser's
obligations under this Agreement [***] shall remain unchanged, (iii) such
Purchaser shall continue to be the sole holder of its Notes and other Note
Documents [***], if any, subject to the Participation and shall have the sole
right to enforce its rights and remedies under the Note Documents [***] (subject
to Section 7.10), (iv) the Company and the other Purchaser Parties (including
Nortel) shall continue to deal solely and directly with such Purchaser in
connection with such Purchaser's rights and obligations under the Note Documents
[***], if any, and (v) the Participation agreement shall not restrict such
Purchaser's ability to agree to any amendment of the terms of the Note Documents
[***], or to exercise or refrain from exercising, or grant to or create in favor
of such participant, any powers or rights that such Purchaser may have under or
in respect of the Note Documents, [***] or any Collateral, including the right
to vote on any matter or to give any consent or approval, except that the
participant may be granted

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       48
<PAGE>   54



the right to consent to any (A) reduction of the rate or amount, or any
extension of the stated maturity, Initial Repurchase Date or due date of any
interest, principal or Fees payable by any Company Party and subject to the
Participation, (B) increase of the rate or amount, or any shortening of the
stated maturity, Initial Repurchase Date or due date, of any interest or fees
payable by the Purchaser to Nortel [***] and to which the Participation is
subject, (C) increase in the amount or extension of the stated termination or
any reduction date of the affected Commitments, or (D) release of all or
substantially all of the Collateral, Nortel [***], except to the extent
otherwise provided in the Note Documents [***]. A participant shall have the
rights of the Purchasers under Sections 2.11, 2.12 and 2.13 and 8.11, subject to
the obligations imposed by such Sections; provided that amounts payable to any
participant shall not exceed the amounts that would have been payable under such
Sections to the Purchaser granting the Participation had such Participation not
been granted, unless the Participation is made with the prior written consent of
the Company.

            (e) Each Purchaser may at any time assign or pledge any portion of
its rights under the Note Documents to a Federal Reserve Bank. No such
assignment or pledge shall be subject to the provisions of Sections 8.6(b) or
8.6(d).

            (f) Following the occurrence of [***], all Notes held by and
Commitments of any [***] shall, at the election of such [***], be re-assigned to
Nortel on the terms and conditions set forth in [***] and this Section 8.6 (in
which case such [***] shall cease to be a Purchaser hereunder). Whether or not
such Assignment has occurred, however, unless the [***] has occurred, upon the
occurrence of [***], (i) the Commitment of each [***] shall be automatically
reduced to an amount equal to such Purchaser's Commitment Usage (and each such
[***] shall be automatically released from that portion of such [***] Commitment
in excess of its then Commitment Usage), and (ii) Nortel shall assume, without
any further condition or action on the part of Nortel or any other Person, that
portion of the Commitments from which such [***] were released pursuant to
clause (i) of this paragraph (f). Following such reduction, release and
assumption, the [***] shall continue to be "Purchasers" under this Agreement,
until the Assignment contemplated by the first sentence of this Section 8.6(f)
has become effective, and Nortel shall be a Purchaser hereunder. It is expressly
agreed that the foregoing reduction, release and assumption shall occur
simultaneously so that, if the [***] are not obligated to purchase Notes on any
Issuance Date, Nortel shall instead be obligated to purchase such Notes, to the
extent of the Commitments assumed by it pursuant to this provision, and subject
to the other terms and conditions set forth herein and the other Note Documents.

            SECTION 8.7 CONFIDENTIALITY.

            (a) Each Purchaser Party will maintain any confidential information
that it may receive from the Company or any of its Subsidiaries pursuant to this
Agreement confidential and shall not disclose such information to third parties
without the prior consent of the Company, except for disclosure: (i) to legal
counsel, accountants and other professional advisors to the Purchaser Party on a
"need-to-know basis" who have agreed to be subject to this Section 8.7; (ii) to
regulatory officials having jurisdiction over the Purchaser Party; (iii)
required by

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                         Nortel Note Purchase Agreement
                                       49
<PAGE>   55



Applicable Law or in connection with any legal proceeding; (iv) to any other
Purchaser Party or to any Affiliate of any Purchaser Party; (v) to another
Person in connection with a potential Assignment, Participation (or an
assignment by Nortel of Exchange Debt) or a Purchaser Party's off-balance sheet
or securitization transaction in the ordinary course of its business, provided
that such Person shall have agreed in writing to be subject to this Section 8.7;
(vi) to prospective purchasers of Collateral after an Event of Default; and
(vii) of information that has been previously disclosed publicly without breach
of this provision.

            (b) The Company shall maintain this Agreement and the other Note
Documents confidential and shall not disclose them to third parties, except for
disclosure: (i) to legal counsel, accountants and other professional advisors to
the Company who have agreed to be subject to this Section 8.7; (ii) to
regulatory officials having jurisdiction over the Company; (iii) required by
Applicable Law or in connection with any legal proceeding; (iv) to the Purchaser
Parties; (v) at the request of any Purchaser Party, to another Person in
connection with a potential Assignment or Participation (or an assignment of
Exchange Debt); and (vi) of information that has been previously disclosed
publicly without breach of this provision.

            SECTION 8.8 GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK (OTHER THAN
CHOICE OF LAW RULES THAT WOULD REQUIRE THE APPLICATION OF THE LAWS OF ANY OTHER
JURISDICTION).

            SECTION 8.9 CHOICE OF FORUM.

            (a) Pursuant to Section 5-1402 of the New York General Obligations
Law, all actions or proceedings arising in connection with this Agreement may be
tried and litigated in, and the Company hereby submits to the nonexclusive
jurisdiction of, the state or Federal courts located in the Borough of
Manhattan, New York City, State of New York, unless such actions or proceedings
are required to be brought in another court to obtain subject matter
jurisdiction over the matter in controversy. EACH OF THE COMPANY AND THE
PURCHASER PARTIES WAIVES ANY RIGHT IT MAY HAVE TO ASSERT THE DOCTRINE OF FORUM
NON CONVENIENS, TO ASSERT THAT IT IS NOT SUBJECT TO THE JURISDICTION OF SUCH
COURTS OR TO OBJECT TO VENUE TO THE EXTENT ANY PROCEEDING IS BROUGHT IN
ACCORDANCE WITH THIS SECTION.

            (b) The Company hereby irrevocably appoints CT Corporation Systems
(which has consented thereto) with offices on the date hereof at 111 Eighth
Avenue, New York, New York 10011, as Process Agent (the "Process Agent") to
receive for and on behalf of the Company service of process in the County of
New York relating to this Agreement and any other Note Document not governed
by the laws of Brazil. SERVICE OF PROCESS IN ANY ACTION OR PROCEEDING AGAINST
THE COMPANY MAY BE MADE ON THE PROCESS AGENT BY REGISTERED OR CERTIFIED MAIL,
RETURN RECEIPT REQUESTED, OR BY ANY OTHER METHOD OF SERVICE PROVIDED FOR UNDER
APPLICABLE LAWS IN EFFECT IN THE STATE OF NEW YORK, AND THE PROCESS AGENT IS
HEREBY AUTHORIZED AND DIRECTED TO ACCEPT SUCH SERVICE FOR AND ON BEHALF OF THE
COMPANY AND TO ADMIT SERVICE WITH RESPECT THERETO. SUCH SERVICE UPON THE PROCESS
AGENT SHALL


                         Nortel Note Purchase Agreement
                                       50
<PAGE>   56



BE DEEMED EFFECTIVE PERSONAL SERVICE ON THE COMPANY, SUFFICIENT FOR PERSONAL
JURISDICTION, AND SHALL BE LEGAL AND BINDING UPON THE COMPANY FOR ALL PURPOSES,
NOTWITHSTANDING ANY FAILURE OF THE PROCESS AGENT TO MAIL COPIES OF SUCH LEGAL
PROCESS TO THE COMPANY, OR ANY FAILURE ON THE PART OF THE COMPANY TO RECEIVE THE
SAME. The Company confirms that it has instructed the Process Agent to mail to
the Company, upon service of process being made on the Process Agent pursuant to
this Section, a copy of the summons and complaint or other legal process served
upon it, by registered mail, return receipt requested, at the Company's address
set forth in Schedule 10.4 of the Common Terms Agreement, or to such other
address as the Company may notify the Process Agent in writing. The Company
agrees that it will at all times maintain a Process Agent to receive service of
process in the County of New York on its behalf with respect to this Agreement.
If for any reason the Process Agent or any successor thereto shall no longer
serve as such Process Agent or shall have changed its address without
notification thereof to the Purchaser Parties, the Company, immediately after
gaining knowledge thereof, irrevocably shall appoint a substitute Process Agent
acceptable to the Administrative Agent in the County of New York and advise the
Administrative Agent thereof.

            (c) NOTHING CONTAINED IN THIS SECTION SHALL PRECLUDE THE PURCHASER
PARTIES FROM BRINGING ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO
THIS AGREEMENT IN THE COURTS OF ANY PLACE WHERE THE COMPANY OR ANY OF ITS ASSETS
MAY BE FOUND OR LOCATED.

            SECTION 8.10 CURRENCY EQUIVALENTS; JUDGMENT CURRENCY.

            (a) If for the purposes of obtaining judgment in any court it is
necessary to convert a sum due hereunder or under any other Note Document in
Dollars into another currency, the parties hereto agree, to the fullest extent
that they may effectively do so, that the rate of exchange used shall be that at
which, in accordance with normal banking procedures, the Administrative Agent
could purchase Dollars with such other currency at the close of business in New
York City on the Business Day preceding that on which final judgment is given.

            (b) The obligation of the Company in respect of any sum due from it
to any Purchaser Party hereunder or under any other Note Document shall,
notwithstanding any judgment in a currency other than Dollars, be discharged
only to the extent that on the Business Day following receipt by such Purchaser
Party in such other currency of any sum adjudged to be so due such Purchaser
Party may, in accordance with normal banking procedures, purchase Dollars with
such other currency; if the Dollars so purchased are less than the sum
originally due to such Purchaser Party in Dollars, the Company agrees, as a
separate obligation and notwithstanding any such judgment, to indemnify such
Purchaser Party against such loss, and if the Dollars so purchased exceed the
sum originally due to any such Purchaser Party, such Purchaser Party agrees to
remit to the Company such excess.

            SECTION 8.11 SET-OFF. In addition to any rights now or hereafter
granted under Applicable Law, during the existence and continuation of any Event
of Default, each Purchaser Party is hereby irrevocably authorized by the
Company, at any time or from time to time, without notice to the Company or to
any other Person, any such notice being hereby expressly waived, to set-off and
to appropriate and to apply any and all deposits (general or special, including


                         Nortel Note Purchase Agreement
                                       51
<PAGE>   57


certificates of deposit, whether matured or unmatured, but not including trust
accounts) and any other Debt, in each case whether direct or indirect or
contingent or matured or unmatured at any time held or owing by such Purchaser
Party to or for the credit or the account of the Company, against and on account
of the obligations of the Company to such Purchaser Party under the Note
Documents to which the Company is a party, irrespective of whether or not such
Purchaser Party shall have made any demand for payment and although such
obligations may be contingent and unmatured. Each Purchaser Party agrees to
promptly notify the Company, the Collateral Agent, the Proceeds Collateral Agent
and the Administrative Agent after any such set-off or application made by such
Purchaser.

            SECTION 8.12 NATURE OF VESPER CAYMAN SPV'S OBLIGATIONS.
Notwithstanding anything herein or in any of the Note Documents to the contrary,
(a) the Company shall have no direct or contingent obligations (including by
reason of Section 2.12(b) or 8.2 hereof) in respect of Vesper Cayman SPV's
obligations under the Purchasers' Fee Letter and (b) Vesper Cayman SPV shall not
be deemed to be a Company Party for purposes of, and the obligations of Vesper
Cayman SPV under the Purchasers' Fee Letter shall not constitute Obligations to
the Purchaser Parties that are secured by the collateral under, the Proceeds
Account Pledge Agreement.

            SECTION 8.13 HEADINGS. The Article and Section headings used in this
Agreement are for convenience of reference only and shall not affect the
construction hereof.

            SECTION 8.14 SEVERABILITY. If any provision of this Agreement shall
be held to be invalid, illegal or unenforceable under Applicable Law in any
jurisdiction, such provision shall be ineffective only to the extent of such
invalidity, illegality or unenforceability, which shall not affect any other
provisions hereof or the validity, legality or enforceability of such provision
in any other jurisdiction.

            SECTION 8.15 SURVIVAL OF AGREEMENTS, REPRESENTATIONS AND WARRANTIES.
All agreements, representations and warranties made herein shall survive the
execution and delivery of this Agreement, the closing and the Issuances of Notes
hereunder and shall continue as valid and enforceable agreements, and
representations and warranties (when made hereunder) until payment and
performance of any and all Obligations. Any investigation at any time made by or
on behalf of the Purchaser Parties shall not diminish the right of the Purchaser
Parties to rely thereon. Without limitation, the agreements and obligations of
the Company contained in Sections 2.11, 2.12, 2.13, 2.14, 8.1 and 8.2, and the
obligations of the Purchasers under Section 7.5 shall survive the payment in
full of all other Obligations.

            SECTION 8.16 EXECUTION IN COUNTERPARTS.

            (a) This Agreement may be executed in any number of counterparts,
each of which counterparts, when so executed and delivered, shall be deemed to
be an original and all of which counterparts, taken together, shall constitute
but one and the same Agreement. This Agreement shall become effective upon the
execution of a counterpart hereof by each of the parties hereto. Faxed
signatures to this Agreement shall be binding for all purposes to the extent
provided in clause (b).



                         Nortel Note Purchase Agreement
                                       52
<PAGE>   58

            (b) This Agreement shall be effective immediately upon its execution
by all parties hereto, provided that, on the Closing Date, each party hereto
shall deliver originally executed signature pages that, if executed in Brazil,
have been witnessed by two witnesses or, if executed outside of Brazil, have
been notarized by a notary public licensed as such under the laws of the place
of signing.

            SECTION 8.17 COMPLETE AGREEMENT; THIRD-PARTY BENEFICIARIES. This
Agreement, together with the other Note Documents, is intended by the parties as
the final expression of their agreement regarding the subject matter hereof and
as a complete and exclusive statement of the terms and conditions of such
agreement. There are no third-party beneficiaries of this Agreement, except that
the Collateral Agent and the Proceeds Collateral Agent are expressly intended to
be a third-party beneficiary of this Agreement.

            SECTION 8.18 NO FIDUCIARY DUTIES OR PARTNERSHIP; LIMITATION OF
LIABILITY, ETC.

            (a) The relationship between the Company and each Purchaser Party is
solely that of debtor and creditor, and neither the Administrative Agent, the
Proceeds Collateral Agent, the Collateral Agent nor any other Purchaser Party
has any fiduciary or other special relationship with the Company, and no term or
condition of any of the Note Documents shall be construed so as to deem the
relationship between the Company and any Purchaser Party to be other than that
of debtor and creditor. No joint venture or partnership is created by this
Agreement or any other Note Document among any Purchaser Parties or among the
Company and any Purchaser Party.

            (b) No claim shall be made by any party hereto against any other
party hereto or its Affiliates, directors, officers, employees or agents for any
special, indirect, consequential or punitive damages in respect of any claim for
breach of contract or under any other theory of liability arising out of or
related to the transactions contemplated by this Agreement, or any act, omission
or event occurring in connection therewith; and the Company, on behalf of itself
and its Subsidiaries, and each of the other parties hereto waives, releases and
agrees not to sue upon any claim for any such damages, whether or not accrued
and whether or not known or suspected to exist in its favor.

            (c) All attorneys, accountants, appraisers and other professional
Persons and consultants retained by the Purchaser Parties shall have the right
to act exclusively in the interest of the Purchaser Parties and shall have no
duty of disclosure, duty of loyalty, duty of care or other duty or obligation of
any type or nature whatsoever to the Company or any of its Subsidiaries or any
of their shareholders, Affiliates or any other Person except as required by or
arising under Applicable Law.

            SECTION 8.19 SECURITIES LAW MATTERS.

            (a) Nature of Notes. The parties hereto acknowledge that the Notes
and any Participations therein are not and are not intended to be "securities"
as defined in the Securities Act, and that the issuance, sale and assignment of
and granting of Participations in the Notes are not intended to be subject to
the provisions governing the issuance, sale and transfer of "securities"
thereunder.


                         Nortel Note Purchase Agreement
                                       53
<PAGE>   59



            (b) Certain Representations and Covenants. Each Purchaser, by
execution and delivery hereof or of an Assignment and Acceptance, shall be
deemed to make to the Company, as of the Closing Date or upon the effectiveness
of such Assignment and Acceptance, as the case may be, and as of each Issuance
Date thereon or thereafter (without regard to whether the Notes are "securities"
for purposes of the Securities Act), the following representations, warranties
and covenants:

               (i) Such Purchaser is acquiring the Notes (or Participations
          therein) solely for financing or investment purposes and not with a
          view toward, or for sale in connection with any distribution thereof
          (except for distributions of Notes held by Nortel pursuant to the
          Syndications), has received and reviewed such information as it deems
          necessary to evaluate the merits and risks of its investment in the
          Notes, is an "accredited investor" within the meaning of Regulation D
          promulgated under the Securities Act and has such knowledge and
          experience in financial and business matters as to be capable of
          evaluating the merits and risks of its investment in the Notes,
          including a complete loss of its investment.

               (ii) Such Purchaser acknowledges that the Notes issued hereunder
          have not been and will not be registered under the Securities Act and
          may not be offered, sold or otherwise transferred without registration
          under the Securities Act other than to the Company or unless an
          exemption from registration is available. In addition, the Purchaser
          represents that it is acquiring the Notes for investment and not with
          a view to any sale or distribution thereof, subject to its ability to
          resell this Note pursuant to Rule 144A or Regulation S of the
          Securities Act, or as otherwise provided by law and subject in any
          case to any requirement of law that the disposition of the property of
          such Purchaser shall at all times be and remain within its control.

               (iii) The Notes and the other Note Documents may be amended or
          supplemented from time to time to modify the restrictions on and
          procedures for resales and other transfers of the Notes to reflect any
          change in Applicable Law (or the interpretation thereof) or in
          practices related to the resale or transfer of restricted securities
          generally. By the acceptance of any Note, such Purchaser is deemed to
          have agreed to any such amendment or supplement.


               (iv) Any offer of Assignment or Assignment by such Purchaser not
          made pursuant to an effective registration statement shall only be
          made (A) to Persons whom the Purchaser reasonably believes to be
          "qualified institutional buyers" as such term is defined in Rule 144A
          promulgated under the Securities Act, (B) to non-U.S. Persons outside
          of the United States (which shall include dealers or other
          professional fiduciaries in the United States acting on a
          discretionary basis for beneficial owners (other than an estate or
          trust) that are non-U.S. Persons) to whom the Purchaser reasonably
          believes offers of Assignment or Assignment of the Notes may be made
          in reliance upon Regulation S promulgated under the Securities Act and
          applicable securities legislation of the relevant jurisdiction or (C)
          to other "accredited investors" within the meaning of Regulation D
          promulgated under the Securities Act. Such Purchaser will take
          reasonable steps to inform, and cause each of its Affiliates to take
          reasonable steps to inform, Persons acquiring Notes from such
          Purchaser or one of its

                         Nortel Note Purchase Agreement
                                       54


<PAGE>   60

          Affiliates, as the case may be, in the United States (the "Subsequent
          Purchasers") that the Notes (x) have not been and will not be
          registered under the Securities Act, (y) are being sold to such
          Subsequent Purchasers without registration under the Securities Act in
          reliance on Rule 144A or Regulation S promulgated thereunder or in
          accordance with another exemption from registration under the
          Securities Act, as the case may be, and (z) may not be offered, sold
          or otherwise transferred except in compliance with the Securities Act.

         SECTION 8.20 WAIVER OF IMMUNITY. To the extent that the Company has or
hereafter may be entitled to claim or may acquire, for itself or any of its
assets, any immunity from suit, jurisdiction of any court or from any legal
process (whether through service of notice, attachment prior to judgment,
attachment in aid of execution, or otherwise) with respect to itself or its
property, it hereby irrevocably waives such immunity in respect of its
obligations hereunder and under the other Note Documents to the extent permitted
by Applicable Law and without limiting the generality of the foregoing, agrees
that the waivers Set forth in this Section shall be effective to the fullest
extent now or hereafter permitted under the Foreign Sovereign Immunities Act of
1976 of the United States of America and are intended to be irrevocable for
purposes of such Act.

         SECTION 8.21 ENGLISH LANGUAGE. Any translation of this Agreement or any
Note or other Note Document into another language shall have no interpretive
effect. All documents or notices to be delivered pursuant to or in connection
with this Agreement and the Note Documents shall be in the English language, or,
if any such document or notice is not in the English language, accompanied by an
English translation thereof, and the English language version of any such
document or notice shall control for purposes hereof.

         SECTION 8.22 WAIVER OF TRIAL BY JURY. THE COMPANY AND THE PURCHASER
PARTIES WAIVE THE RIGHT TO A TRIAL BY JURY IN ANY ACTION UNDER THIS AGREEMENT OR
ANY ACTION ARISING OUT OF THE TRANSACTIONS CONTEMPLATED HEREBY, REGARDLESS OF
WHICH PARTY INITIATES SUCH ACTION OR ACTIONS.



                         Nortel Note Purchase Agreement
                                       55
<PAGE>   61


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

                              Company:

                              VESPER S.A., a sociedade anonima


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


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

                              -------------------------------------------------
                              Witness


                              -------------------------------------------------
                              Witness




                         Nortel Note Purchase Agreement
                                       56
<PAGE>   62


                              Administrative Agent:

                              ABN AMRO BANK N.V., as Administrative
                              Agent

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


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

                              Purchasers:

                              NORTEL NETWORKS CORPORATION,
                              a Canadian corporation, as initial Purchaser

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

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

                              Nortel:

                              NORTEL NETWORKS CORPORATION
                              a Canadian corporation, individually

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

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



                         Nortel Note Purchase Agreement
                                       57
<PAGE>   63


                                                                 SCHEDULE 1.1(a)

                                   COMMITMENTS

<TABLE>
<CAPTION>
================================================================================
      PURCHASER                    COMMITMENT        INITIAL ISSUANCE COMMITMENT
      ---------                    ----------        ---------------------------
<S>                                <C>               <C>
Nortel Networks Corporation        $400,000,000.00        $200,000,000.00
                                   ---------------        ---------------
      TOTAL                        $400,000,000.00        $200,000,000.00
</TABLE>



                         Nortel Note Purchase Agreement
                                 Schedule 1.1(a)

<PAGE>   64


                                                                 SCHEDULE 1.1(b)

                              PURCHASER INFORMATION

ADMINISTRATIVE AGENT'S OFFICE

ABN AMRO Bank N.Y.
Agency Services
1325 Avenue of the Americas, 9th Floor
New York, New York 10128
Fax: 212-314-1712
Phone:   212-314-1724
Attention:   Linda Boardman

ADMINISTRATIVE AGENT'S ACCOUNT (for funding of purchase price of Notes by the
Purchasers and for payments by the Paying Agent or any Company Party):

     Account Name: [***]
     Account No.: [***]
     ABN AMRO Bank, NY
     ABA No.: [***]
     Ref:  For Nortel NPA: Nortel-Vesper (Brazil)

PAYING AGENT'S OFFICE

Chase Trust Bank
Akasaka Park Building, 13th Floor
2-20 Akasaka 5-chome
Minato-ku, Tokyo 107 Japan
Fax:   001-212-946-8177/8178
Phone:   001-212 946-3172
Attention:   William Potes
Ref:  Vesper S.A.

PAYING AGENT'S NORTEL ACCOUNT (for funding of payments by the Company):

     Account No.: [***]
     The Chase Manhattan Bank
     ABA No.: [***]


[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                          Nortel Note Purchase Agreement
                                 Schedule 1.1(b)
<PAGE>   65



PURCHASERS AND NORTEL:

<TABLE>
<CAPTION>
=============================================================================================
PURCHASERS AND NORTEL              DOMESTIC PURCHASING OFFICE         EURO-DOLLAR PURCHASING
                                                                              OFFICE
---------------------              --------------------------         -----------------------
<S>                                <C>                                <C>
Nortel Networks Corporation        8200 Dixie Road, Suite 100         8200 Dixie Road, Suite 100
                                   Brampton, Ontario L6T5P6           Brampton, Ontario L6T5P6
                                   Fax:   905-863-8258                Fax:   905-863-8258
                                   Phone: 905-863-6613                Phone: 905-863-6613
                                   Attention: Treasurer               Attention:  Treasurer
</TABLE>

                         Nortel Note Purchase Agreement
                                 Schedule 1.1(b)
<PAGE>   66
                                                                       EXHIBIT A

                                  FORM OF NOTE

THIS NOTE (THIS "NOTE") HAS NOT BEEN REGISTERED UNDER THE UNITED STATES OF
AMERICA SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE OFFERED, SOLD OR
OTHERWISE TRANSFERRED WITHOUT REGISTRATION UNDER SUCH ACT UNLESS AN EXEMPTION
FROM REGISTRATION IS AVAILABLE. IN ADDITION, THE PURCHASER REPRESENTS THAT IT IS
ACQUIRING THIS NOTE FOR INVESTMENT AND NOT WITH A VIEW TO ANY SALE OR
DISTRIBUTION HEREOF, SUBJECT TO ITS ABILITY TO RESELL THIS NOTE PURSUANT TO RULE
144A OR REGULATION S OF THE UNITED STATES OF AMERICA SECURITIES ACT OF 1933, AS
AMENDED, OR AS OTHERWISE PROVIDED BY LAW AND SUBJECT IN ANY CASE TO ANY
REQUIREMENT OF LAW THAT THE DISPOSITION OF THE PROPERTY OF ANY HOLDER SHALL AT
ALL TIMES BE AND REMAIN WITHIN ITS CONTROL.

THIS NOTE AND RELATED DOCUMENTATION MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO
TIME TO MODIFY THE RESTRICTIONS ON AND PROCEDURES FOR RESALES AND OTHER
TRANSFERS OF THIS NOTE TO REFLECT ANY CHANGE IN APPLICABLE LAW OR REGULATION (OR
THE INTERPRETATION THEREOF) OR IN PRACTICES RELATED TO THE RESALE OR TRANSFER OF
RESTRICTED SECURITIES GENERALLY. BY THE ACCEPTANCE OF THIS NOTE, THE PURCHASER
HEREOF SHALL BE DEEMED TO HAVE AGREED TO ANY SUCH AMENDMENT OR SUPPLEMENT.



$                                                               [PLACE AND DATE]
 --------------


FOR VALUE RECEIVED, the undersigned, Vesper S.A., a sociedade anonima organized
under the laws of Brazil (the "Company"), hereby unconditionally promises to pay
to the holder hereof from time to time or its registered assigns (the "Holder"),
as registered in the Register, pursuant to the Paying Agency Agreement dated
December 13, 1999 (the "Paying Agency Agreement") among the Company, the Initial
Facility Agents (as defined in the Common Terms Agreement), the Collateral
Agent, and the Paying Agent (as defined below), on July 1, 2012, the principal
amount of $____________. The Company further agrees to pay interest on the
unpaid principal amount hereof from time to time outstanding as provided in
Article 2 hereof.



                               Note (Nortel NPA)
                                       1
<PAGE>   67

                            ARTICLE 1. DEFINED TERMS.

         SECTION 1.1 DEFINED TERMS GENERALLY. Capitalized terms used but not
otherwise defined in this Note shall have the meanings assigned to them in the
Note Purchase Agreement (as defined below) (including terms defined therein by
reference to the Common Terms Agreement (as defined below)).

         SECTION 1.2 DEFINITIONS. The following terms with initial capital
letters have the following meanings:

                  "ADJUSTED EURO-DOLLAR RATE" means, with respect to any day
during any Interest Period, a rate per annum (rounded upwards, if necessary, to
the next higher 1/100 of 1%) equal to (i) the applicable London Interbank
Offered Rate for such Interest Period, divided by (ii) 1.00 minus the
Euro-Dollar Reserve Requirement for such day (expressed as a decimal).

                  "ADMINISTRATIVE AGENT" means ABN AMRO Bank N.V. ("ABN AMRO"),
as Administrative Agent and bookrunner for the Purchasers or any successor in
such capacity.

                  "APPLICABLE MARGIN" means, at any time, with respect to
Euro-Dollar Rate Notes, 6% per annum and with respect to Base Rate Notes, 5% per
annum.

                  "APPLICABLE PURCHASING OFFICE" means, with respect to any
Purchaser Party, (i) in the case of any payment with respect to Euro-Dollar Rate
Notes, the Purchaser Party's Euro-Dollar Purchasing Office, and (ii) in the case
of any payment with respect to Base Rate Notes or any other payment under the
Note Documents, the Purchaser Party's Domestic Purchasing Office.

                  "BASE RATE" means, for any day, the greater of (i) the average
of interest rates per annum announced by the Reference Banks at their respective
principal offices as their prime rate effective for that day, which rate may not
be the lowest rate then being charged to commercial borrowers by such Reference
Banks, or (ii) the Federal Funds Rate in effect on such day plus 0.5% per annum.
Any change in the Base Rate due to a change in such prime rate or the Federal
Funds Rate shall be effective from and including the effective date of such
change respectively in such prime rate or the Federal Funds Rate.

                  "BASE RATE NOTE" means a Note, or portion thereof, that bears
interest at a rate determined by reference to the Base Rate.

                  "COMMON TERMS AGREEMENT" means the Common Terms Agreement
dated as of December 13, 1999 (as amended from time to time), by and among (i)
the Company, (ii) Vesper Holding S.A., (iii) ABN AMRO and Harris Corporation, as
Initial Facility Agents, (iv) the Other Pari Passu Facility Agents that may
hereafter become parties thereto and (v) the Collateral Agent.



                               Note (Nortel NPA)
                                       2
<PAGE>   68

                  "COMPANY" is defined in the Preamble.

                  "EURO-DOLLAR BUSINESS DAY" means any Business Day on which
commercial banks are open for international business (including dealings in
interbank Dollar deposits) in London, England.

                  "EURO-DOLLAR RATE NOTE" means any Note, or portion thereof,
that bears interest at a rate determined by reference to an Adjusted Euro-Dollar
Rate (and as to which a single Interest Period is applicable).

                  "EVENT OF DEFAULT" means the occurrence of (i) any one or more
of the "Events of Default" described in Article 6 of the Common Terms Agreement
or (ii) any failure by the Company to comply with or observe any agreement,
covenant or obligation under Section 2.2 of the Note Purchase Agreement.

                  "FEDERAL FUNDS RATE" means, for any day, the rate per annum
(rounded upwards, if necessary to the nearest 1/100th of 1%) equal to the
weighted average of the rates of overnight federal funds transactions with
members of the Federal Reserve System arranged by federal funds brokers on such
day, as published for such day (or, if such day is not a Business Day, for the
next preceding Business Day) by the Federal Reserve Bank of New York on the
Business Day next succeeding such day, provided that if such rate is not so
published for any day that is a Business Day, the Federal Funds Rate for such
day shall be the average rate charged to the Reference Banks on such day on such
transactions as determined by the Administrative Agent.

                  "HOLDER" is defined in the Preamble.

                  "INTEREST PAYMENT DATE" means the last day of March, June,
September and December in each year, beginning March 31, 2000.

                  "INTEREST PERIOD" means, subject to the next sentence, with
respect to each Euro-Dollar Rate Note issued on any Issuance Date, the period
commencing on the date specified in the related Notice of Issuance or Notice of
Continuation/Conversion (or telephonic notice in lieu thereof) and ending one,
two, three or six months thereafter, as the Company may elect pursuant to
Section 2.1(c) or 2.3(c) of the Note Purchase Agreement as applicable.
Notwithstanding the foregoing: (a) if a Euro-Dollar Rate Note is continued, the
Interest Period applicable to such Euro-Dollar Rate Note shall commence on the
day on which the Interest Period applicable to such Euro-Dollar Rate Note ends;
(b) any Interest Period applicable to a Euro-Dollar Rate Note (i) that would
otherwise end on a day that is not a Euro-Dollar Business Day shall be extended
to the next succeeding Euro-Dollar Business Day, unless such succeeding
Euro-Dollar Business Day falls in another calendar month, in which case such
Interest Period shall end on the next preceding Euro-Dollar Business Day or (ii)
that begins on the last Euro-Dollar Business Day of a calendar month (or on a
day for which there is no numerically corresponding day in the calendar month at
the end of such Interest Period) shall end on the last Euro-Dollar Business Day
of the



                               Note (Nortel NPA)
                                       3
<PAGE>   69

calendar month; (c) no Interest Period for any Note shall end after the stated
maturity date of such Note and no Interest Period for any Note shall both
commence prior to and end after the Initial Repurchase Date; and (d) for any
Issuance subsequent (for purposes of this definition, a "Subsequent Issuance")
to the first Issuance (for purposes of this definition, a "Benchmark Issuance")
bearing an Interest Period of identical length, the initial Interest Period of
such Subsequent Issuance shall end on the last day of the Interest Period for
the Benchmark Issuance in effect on the date of such Subsequent Issuance.
Notwithstanding the foregoing, the first Interest Period may end on an "Interest
Payment Date," if the Company so elects in the first Notice of Issuance.

                  "LONDON INTERBANK OFFERED RATE" means, with respect to any
Interest Period, the rate per annum calculated by the Administrative Agent as
the arithmetic mean (rounded upwards, if necessary, to the next higher 1/100th
of 1%) of the offered rates for deposits in Dollars with a term comparable to
such Interest Period that appears on the Telerate Page (as defined below) at
approximately 11:00 A.M., London time, on the second full Euro-Dollar Business
Day preceding the first day of such Interest Period; provided that if there
shall at any time no longer exist a Telerate Page, "London Interbank Offered
Rate" shall mean, with respect to each day during each Interest Period
pertaining to a Euro-Dollar Rate Note, the rate per annum equal to the average
of the rates at which the Reference Banks are offered Dollar deposits at or
about 10:00 A.M., New York City time, two Business Days prior to the beginning
of such Interest Period in the London interbank eurodollar market where the
eurodollar and foreign currency and exchange operations in respect of their
Euro-Dollar Rate Note purchases are then being conducted, for delivery on the
first day of such Interest Period, for the number of days comprised therein and
in an amount comparable to the principal amount of the Euro-Dollar Rate Notes to
be outstanding during such Interest Period. "Telerate Page" means the display
designated as Page 3750 on the Dow Jones & Company Telerate system (or such
other page as may replace such page on such system or any successor system for
the purpose of displaying the rates at which Dollar deposits are offered by
leading banks in the London interbank deposit market).

                  "MANDATORY PARTIAL REPURCHASE" is defined in Section 2.6(c)(i)
of the Note Purchase Agreement.

                  "NOTICE OF CONTINUATION/CONVERSION" is defined in Section
2.3(b).

                  "NOTE DOCUMENTS" means, collectively, the Note Purchase
Agreement, the Common Terms Agreement, this and any other Note, the Guaranties,
the Collateral Documents, the Exchange Debt Agreement, the Capital Contribution
Agreement, the Fee Letters, the Subordination Agreements (other than any such
agreement relating to Subordinated Debt), all of the Interest Rate Hedge
Agreements between the Company, on the one hand, and one or more Swap Lenders,
on the other hand, in respect of the Obligations, and all amendments, exhibits
and schedules to any of the foregoing.



                               Note (Nortel NPA)
                                       4
<PAGE>   70

                  "NOTE PURCHASE AGREEMENT" means the Secured Note Purchase
Agreement, dated as of December 13, 1999 (as amended from time to time), by and
among (i) the Company, (ii) Nortel Networks Corporation, individually and as
initial purchaser, and (iii) the Administrative Agent.

                  "PAYING AGENT" means Chase Trust Bank or any successor in such
capacity, as paying agent under the Paying Agency Agreement.

                  "PAYING AGENT'S OFFICE" means the office of the Paying Agent
identified as such in Schedule 1.1(b) to the Note Purchase Agreement, or such
other office as the Paying Agent may hereafter designate by notice to the
Company and the Administrative Agent.

                  "POST-DEFAULT RATE" means, subject to Section 2.3(e) of the
Note Purchase Agreement, at any time, a rate per annum equal to the Adjusted
Euro-Dollar Rate or the Base Rate in effect at such time plus the Applicable
Margin plus 1%.

                  "REFERENCE BANKS" means the Reference Purchaser, Citibank,
N.A. and The Chase Manhattan Bank.

                  "REFERENCE PURCHASER" means (i) the Administrative Agent, if
it is a bank, or (ii) ABN AMRO, if the Administrative Agent is not a bank.

                  "REGISTER" means the register for the recordation of the names
of the Purchaser Parties and their respective Commitments and the principal
amounts of their respective Notes maintained by the Administrative Agent in
accordance with Section 8.6(c) of the Note Purchase Agreement.

                  "SUBSEQUENT PURCHASERS" is defined in Section 6.13(b)(ii).

     ARTICLE 2. INTEREST; INTEREST PERIODS; CONTINUATION/CONVERSION.

         SECTION 2.1 INTEREST RATE AND PAYMENT.

                  (a) This Note shall bear interest on the outstanding principal
amount hereof, from and including the Issuance Date to and excluding the due
date or the date of any repayment hereof, at the following rates per annum: (i)
for so long as and to the extent that this Note is a Euro-Dollar Rate Note, at
the Adjusted Euro-Dollar Rate for each day during each Interest Period
applicable hereto plus the Applicable Margin in respect of Euro-Dollar Rate
Notes; and (ii) for so long as and to the extent that this Note is a Base Rate
Note, at the Base Rate (as in effect from time to time) plus the Applicable
Margin in respect of Base Rate Notes.

                  (b) Notwithstanding Section 2.1(a) hereof or Sections
2.3(a)(i) and 2.3(a)(ii) of the Note Purchase Agreement, at any time while an
Event of Default exists under Section 6.1(a) or (q) of the Common Terms
Agreement in respect of any principal, interest, Fees or other



                               Note (Nortel NPA)
                                       5
<PAGE>   71

amount payable under the Note Documents or in respect of any indemnification
obligation related thereto, this Note shall bear interest to the maximum extent
permitted by Applicable Law at a fluctuating rate per annum equal to the
Post-Default Rate as in effect from time to time, without notice or demand of
any kind, until such Event of Default shall have been waived or otherwise shall
have ceased to exist.

                  (c) Accrued interest shall be payable in arrears (i) for so
long as and to the extent that this Note is a Base Rate Note, on each Interest
Payment Date; (ii) for so long as and to the extent that this Note is a
Euro-Dollar Rate Note, on the last day of each Interest Period applicable
thereto; provided that if the Interest Period applicable to a Euro-Dollar Rate
Note is longer than three months, interest also shall be payable on the day that
is three months after the first day of such Interest Period; (iii) in the case
of any interest accrued at the Post-Default Rate pursuant to Section 2.1(b)
hereof, on demand; and (iv) when this Note shall become due (whether at
maturity, by reason of prepayment, acceleration, Mandatory Purchase, Mandatory
Partial Repurchase or otherwise).

         SECTION 2.2 INTEREST PERIODS. Notwithstanding anything herein to the
contrary, all Interest Periods applicable to this Note for so long as and to the
extent that this Note is a Euro-Dollar Rate Note shall comply with the
definition of "Interest Period" and the provisions of the Note Purchase
Agreement.

         SECTION 2.3 CONTINUATION/CONVERSION.

                  (a) Subject to Sections 2.3(c), 2.3(b) and 2.10 of the Note
Purchase Agreement and the Company obtaining all necessary approvals, the
Company shall have the option (i) at any time, to convert all or any part of
this Note from a Base Rate Note to a Euro-Dollar Rate Note, (ii) on the last day
of the Interest Period applicable hereto, to (A) convert all or any part of this
Note from a Euro-Dollar Rate Note to a Base Rate Note, (B) to the extent that
this Note is a Euro-Dollar Rate Note, continue all or any part of this Note as a
Note of the same Type, provided that, in the case of clause (i) and (ii)(B) of
this Section 2.3(a), there does not exist an Event of Default at such time. To
the extent that this Note is a Euro-Dollar Rate Note, if an Event of Default
shall exist upon the expiration of the Interest Period applicable to this Note,
this Note automatically shall be converted into a Base Rate Note.

                  (b) If the Company elects to continue or convert this Note or
a part hereof under this Section 2.3, it shall deliver to the Administrative
Agent a Notice of Continuation/Conversion together with all attachments required
thereby, duly completed and executed by a Responsible Officer (a "Notice of
Continuation/Conversion"), (i) not later than 10:00 a.m. (New York time) at
least three Euro-Dollar Business Days before the proposed continuation or
conversion date, if the Company proposes to continue or to convert all or part
of this Note into, a Euro-Dollar Rate Note, and (ii) otherwise not later than
10:00 a.m. (New York time) at least three Business Days before the proposed
continuation or conversion date.



                               Note (Nortel NPA)
                                       6
<PAGE>   72

                  (c) In lieu of delivering a Notice of Continuation/Conversion,
the Company, through a Responsible Officer, may give the Administrative Agent
telephonic notice of any proposed continuation or conversion by the time a
Notice of Continuation/Conversion would be required to be delivered and
containing all information required therefor; provided, however, that such
notice shall be confirmed in writing by delivery of a Notice of
Continuation/Conversion to the Administrative Agent on or before the proposed
continuation or conversion date. The Holder shall incur no liability to the
Company in acting upon any telephonic notice that the Administrative Agent
believes to have been given by a Responsible Officer or for otherwise acting in
good faith under this Section 2.3 and in converting or continuing this Note (or
a part hereof) pursuant to any telephonic notice.

                  (d) Any Notice of Continuation/Conversion (or telephonic
notice in lieu thereof) shall be irrevocable and the Company shall be bound to
continue or convert in accordance therewith. If any request for the continuation
or conversion of this Note is not made in accordance with this Section 2.3, or,
to the extent that this Note is a Euro-Dollar Rate Note, if no notice is so
given with respect to this Note and the Interest Period applicable hereto
expires, then this Note automatically shall be continued as a Euro-Dollar Rate
Note having an Interest Period of one month.

         SECTION 2.4 COMPUTATIONS. For so long as and to the extent that this
Note is a Euro-Dollar Rate Note, interest on this Note shall be computed on the
basis of a 360-day year and the actual number of days elapsed (including the
first and excluding the last day of the period). For so long as and to the
extent that this Note is a Base Rate Note, interest on this Note shall be
computed on the basis of a 365/366-day year and the actual number of days
elapsed (including the first and excluding the last day of the period). Any
change in the interest rate on this Note resulting from a change in the rate
applicable hereto pursuant to the terms hereof shall become effective as of 9:00
a.m. (New York time) on the day on which such change in the applicable rate
shall become effective.

         SECTION 2.5 MAXIMUM LAWFUL RATE OF INTEREST. The rate of interest
payable on this Note shall in no event exceed the maximum rate permissible under
Applicable Law. If the rate of interest payable on this Note or other amount is
ever reduced as a result of this Section 2.5 and at any time thereafter the
maximum rate permitted by Applicable Law shall exceed the rate of interest
provided for in this Note, then the rate provided for in this Note shall be
increased up to the maximum rate provided by Applicable Law for such period as
is required so that the total amount of interest received by the Holder during
such period is that which would have been received by the Holder but for the
operation of the first sentence of this Section 2.5.

                    ARTICLE 3. REPURCHASE; ACCELERATION; ETC.

         SECTION 3.1 MANDATORY REPURCHASE AND OPTIONAL OR VOLUNTARY REPURCHASE;
ACCELERATION. This Note is subject to mandatory repurchase at the option of the
Holder, is subject to optional or voluntary repurchase at the option of the
Company and is subject to acceleration, all on the terms and conditions set
forth in the Note Purchase Agreement, all of



                               Note (Nortel NPA)
                                       7
<PAGE>   73

which are incorporated herein by reference. Reference is made to the Note
Purchase Agreement for the foregoing terms and conditions as well as certain
other provisions applicable to this Note.

                          ARTICLE 4. MANNER OF PAYMENT.

         SECTION 4.1 PAYMENT GENERALLY. Except as otherwise expressly provided
in the Note Purchase Agreement, the Company or any Designated Repurchaser shall
make each payment under this Note to the Paying Agent in Dollars and in
immediately available funds, without any deduction whatsoever, including any
deduction for any setoff, recoupment, counterclaim or Taxes (other than Excluded
Taxes), at the Paying Agent's Office, for deposit in the Paying Agent's Account
(which amount will be held in trust for the Administrative Agent) at such time
as shall provide the Paying Agent with sufficient time to, in turn, pay such
amount to the Administrative Agent in Dollars and in immediately available
funds, without any deduction whatsoever, including any deduction for any setoff,
recoupment, counterclaim or Taxes at the Administrative Agent's Office for the
account of the Applicable Purchasing Offices of the Holder, for deposit in the
Administrative Agent's Account not later than 12:00 noon (New York time) on the
due date thereof. Any payments received after 12:00 noon (New York time) on any
Business Day shall be deemed received on the next succeeding Business Day. Not
later than 2:00 p.m. (New York time) on the day such payment is made, the
Administrative Agent shall initiate a wire transfer to the Holder or its
registered assigns, for the account of the Holder's Applicable Purchasing
Office, in Dollars and in immediately available funds, of the Holder's share of
the payment so made, determined pursuant to Section 2.9 of the Note Purchase
Agreement. Delivery to the Administrative Agent shall be made by the Paying
Agent in accordance with the written instructions satisfactory to the Paying
Agent from time to time given to the Paying Agent by the Administrative Agent;
and delivery to the Holder shall be made by the Administrative Agent in
accordance with the written instructions satisfactory to the Administrative
Agent from time to time given to the Administrative Agent by the Holder.

         SECTION 4.2 DISCHARGE; INDEMNIFICATION. The Holder agrees that any
payment received by the Paying Agent made in respect of this Note under and in
accordance with Section 2.8(a) of the Note Purchase Agreement from or on behalf
of the Company shall be deemed to satisfy pro tanto the corresponding
obligations of the Company under this Note to pay the Holder and shall be
conclusive and shall discharge the Company of its corresponding payment
obligations to the Holder under this Note. To the extent that the Company or any
other Person on behalf of the Company makes any payment due under this Note to
the Paying Agent, the Company hereby indemnifies the Holder against any failure
on the part of the Paying Agent to pay to the Administrative Agent in accordance
with the instructions provided to the Paying Agent by the Administrative Agent
pursuant to Section 2.8(a) of the Note Purchase Agreement any sum due in respect
of this Note by the due date or due time thereof and agrees to pay the amount of
such payment due, plus interest at the Post-Default Rate, not later than (i) one
Business Day after the due date thereof, in the case of payments of principal
and (ii) three Business Days after the due date thereof, in the case of payments
of interest and (iii) five Business Days after the date thereof, in the case of
expenses or other amounts payable under this Note. This indemnity constitutes a
separate and independent obligation from the obligations of



                               Note (Nortel NPA)
                                       8
<PAGE>   74

the Company under this Note and shall give rise to a separate and independent
cause of action. To the extent that the Paying Agent makes any payment to the
Administrative Agent with respect to which the Holder has received a payment
from the Company in satisfaction of its indemnification obligations set forth in
Section 4.2, the Holder shall promptly return to the Company any such
indemnification payment so made by the Company, together with interest at the
Federal Funds Rate from, one Business Day after the later of (x) the date on
which the payment from the Paying Agent was received by the Holder and (y) the
date on which the payment from the Company was received by the Holder, to but
excluding the date on which such payment is returned to the Company.

         SECTION 4.3 DATE OF PAYMENT. Whenever any payment or repurchase to be
made hereunder shall be due on a day that is not a Business Day (or, in the case
of any payment with respect to a Euro-Dollar Rate Note, not a Euro-Dollar
Business Day), such payment shall instead be made on the next succeeding
Business Day (or, in the case of any such payment with respect to a Euro-Dollar
Rate Note, the next succeeding Euro-Dollar Business Day), together with interest
accrued during the period of such extension, unless, in the case of any such
payment in respect of a Euro-Dollar Note, such succeeding Euro-Dollar Business
Day falls in the next calendar month, in which case such payment or repurchase
shall be made on the immediately preceding Euro-Dollar Business Day.

         SECTION 4.4 PAYMENTS SET ASIDE. To the extent any Agent or the Holder
receives payment of any amount under this Note, whether by way of payment by the
Company, setoff, as proceeds of Collateral or otherwise, which payment is
subsequently invalidated, declared to be fraudulent or preferential, set aside
or required to be repaid to a trustee, receiver or any other party under any
bankruptcy law, other law or equitable cause, in whole or in part, then, to the
extent of such payment received and to the extent permitted by Applicable Law,
the Obligations or Fees or part thereof intended to be satisfied thereby shall
be revived and continue in full force and effect, together with all Collateral
security therefor, as if such payment had not been received by the Agent or the
Holder. If prior to any such invalidation, declaration, setting aside or
requirement, this Note shall have been canceled or surrendered, this Note shall
be reinstated in full force and effect, and such prior cancellation or surrender
shall not diminish, discharge or otherwise affect the obligations of the Company
in respect of the amount of the affected payment.

         SECTION 4.5 MANDATORY SUSPENSION AND CONVERSION OF EURO-DOLLAR RATE
NOTES; REGULATORY CHANGES; COMPENSATION FOR FUNDING LOSSES. Under certain
circumstances, this Note, to the extent it is a Euro-Dollar Rate Note, will be
converted into a Base Rate Note. In addition, under certain circumstances,
certain additional costs and other amounts are payable by the Company in respect
of this Note. Reference is made to the Note Purchase Agreement for a complete
description of the foregoing, all of which are hereby incorporated herein by
reference.



                               Note (Nortel NPA)
                                       9
<PAGE>   75

                                ARTICLE 5. TAXES.

         SECTION 5.1 TAXES.

                  (a) If the Company is required by Applicable Law to make any
deduction or withholding in respect of any Taxes (other than Excluded Taxes)
from any amount payable under this Note to the Paying Agent or to, or for the
account of the Holder, the Company shall pay to the Paying Agent or to, or for
the account of such Holder, on the date such amount is payable, such additional
amounts as may be necessary to ensure that the net amounts received by it or for
its account, in the aggregate, after all applicable deductions or withholdings,
shall equal the amount that the Paying Agent or the Holder would have been
entitled to receive under this Note if no deductions or withholdings were made.
If the Company shall deduct or withhold any Taxes from any payments under this
Note, it shall provide to the Holder to the extent available to the Company, (i)
a statement setting forth the amount and type of Taxes so deducted or withheld,
the applicable rate and any other information or documentation that the Paying
Agent or the Holder may reasonably request and (ii) as promptly as possible
after payment is made to the relevant Governmental Authority, a certified copy
of any original official receipt received by the Company showing payment.

                  (b) If the Holder is required to make any payment on account
of Taxes (other than Excluded Taxes) on or in relation to any sum received or
receivable by it under this Note, or any liability for Taxes (other than
Excluded Taxes) in respect of any such payment is imposed, levied or assessed
against the Holder, whether or not correctly or legally imposed, then (i) the
Holder shall promptly notify the Administrative Agent and the Company and shall
provide such evidence thereof, in the form reasonably specified by the Company,
and such cooperation as the Company may reasonably request, and (ii) the Company
shall pay when due such additional amounts as may be necessary to ensure that
the amount received by the Holder, less any such Taxes paid, imposed, levied or
assessed, including any Taxes (other than Excluded Taxes) imposed on such
additional amounts, shall equal the amount that the Holder would have been
entitled to retain under this Note in the absence of the payment, imposition,
levy or assessment of such Taxes.

                  (c) Upon the written request of the Company, the Holder shall
promptly provide to the Company, the Paying Agent, the Administrative Agent and
the Collateral Agent such form, certification or similar documentation (each
duly completed, accurate and signed) as is required by Brazil or any other
jurisdiction otherwise imposing Taxes and specified by the Company in such
request, but only if required or permitted under Applicable Law, in order to
obtain an exemption from, or reduced rate of, deduction, payment or withholding
of Taxes to which the Holder is entitled pursuant to an applicable tax treaty or
the laws of Brazil or such other jurisdiction; provided that the Holder shall
not have any obligation to provide such form, certification or similar document
if, in the sole judgment of the Holder, the provision of such form,
certification or similar document will be unduly burdensome, will require the
Holder to disclose any confidential or proprietary information or will otherwise
be disadvantageous to the Holder. Subject to the proviso in the immediately
preceding sentence, the Company shall not be



                               Note (Nortel NPA)
                                       10
<PAGE>   76

required to indemnify the Holder under Section 5.1(a) or 5.1(b) hereof or
Section 2.12(a) or 2.12(b) of the Note Purchase Agreement for any Taxes to the
extent that such Taxes would not be imposed but for the failure by the Holder to
provide any form, certification or similar document as required by this
subsection; provided that if the Holder is otherwise exempt from or subject to a
reduced rate of withholding tax and becomes subject to Taxes because of its
failure to deliver a form required hereunder, the Company shall take such steps
as the Holder shall reasonably request to assist the Holder to recover such
Taxes.

                            ARTICLE 6. MISCELLANEOUS.

         SECTION 6.1 EXPENSES. To the extent provided in the Note Purchase
Agreement, the Company shall pay promptly after demand, any and all costs and
expenses (including fees and disbursements of in-house and other attorneys,
appraisers, consultants and other experts) incurred by the Holder after an
actual or alleged Default or an Event of Default, in any workout, restructuring
or similar arrangements, or in connection with the protection, preservation,
exercise or enforcement of any of the terms of this Note, or in connection with
any foreclosure, collection or bankruptcy proceedings.

         SECTION 6.2 WAIVERS; AMENDMENTS IN WRITING.

                  (a) No amendment of any provision of this Note (including a
waiver thereof or consent relating thereto) shall be effective unless the same
shall be in writing and signed or consented to in accordance with Section 8.3(a)
of the Note Purchase Agreement.

                  (b) Any waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given. No notice to or
demand on the Company in any case shall entitle the Company to any other or
further notice or demand in similar or other circumstances.

         SECTION 6.3 CUMULATIVE REMEDIES; FAILURE OR DELAY. The rights and
remedies provided for under this Note and the Note Purchase Agreement are
cumulative and are not exclusive of any rights and remedies that may be
available to the Holder under Applicable Law or otherwise. No failure or delay
on the part of the Holder in the exercise of any power, right or remedy under
this Note shall impair such power, right or remedy or operate as a waiver
thereof, nor shall any single or partial exercise of any such power, right or
remedy preclude other or further exercise thereof or of any other power, right
or remedy.

         SECTION 6.4 SUCCESSORS AND ASSIGNS; ETC.

                  (a) This Note shall be binding upon and inure to the benefit
of the Holder and its successors and permitted assigns. The Company may not
assign or transfer any interest hereunder without the prior written consent of
the Holder.

                  (b) This Note may be assigned, and participations in this Note
may be sold, only as provided in the Note Purchase Agreement.



                               Note (Nortel NPA)
                                       11
<PAGE>   77

         SECTION 6.5 GOVERNING LAW. THIS NOTE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK (OTHER THAN
CHOICE OF LAW RULES THAT WOULD REQUIRE THE APPLICATION OF THE LAWS OF ANY OTHER
JURISDICTION).

         SECTION 6.6 CHOICE OF FORUM.

                  (a) Pursuant to Section 5-1402 of the New York General
Obligations Law, all actions or proceedings arising in connection with this Note
may be tried and litigated in, and the Company hereby submits to the
nonexclusive jurisdiction of, the state or Federal courts located in the Borough
of Manhattan, New York City, State of New York, unless such actions or
proceedings are required to be brought in another court to obtain subject matter
jurisdiction over the matter in controversy. EACH OF THE COMPANY AND THE HOLDER
WAIVES ANY RIGHT IT MAY HAVE TO ASSERT THE DOCTRINE OF FORUM NON CONVENIENS, TO
ASSERT THAT IT IS NOT SUBJECT TO THE JURISDICTION OF SUCH COURTS OR TO OBJECT TO
VENUE TO THE EXTENT ANY PROCEEDING IS BROUGHT IN ACCORDANCE WITH THIS SECTION.

                  (b) NOTHING CONTAINED IN THIS SECTION 6.6 SHALL PRECLUDE THE
HOLDER FROM BRINGING ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS
NOTE IN THE COURTS OF ANY PLACE WHERE THE COMPANY OR ANY OF ITS ASSETS MAY BE
FOUND OR LOCATED.

         SECTION 6.7 CURRENCY EQUIVALENTS; JUDGMENT CURRENCY.

                  (a) If for the purposes of obtaining judgment in any court it
is necessary to convert a sum due under this Note in Dollars into another
currency, the parties hereto agree, to the fullest extent that they may
effectively do so, that the rate of exchange used shall be that rate at which,
in accordance with normal banking procedures, the Administrative Agent could
purchase Dollars with such other currency at the close of business in New York
City on the Business Day preceding that on which final judgment is given.

                  (b) The obligation of the Company in respect of any sum due
from it to the Holder under this Note shall, notwithstanding any judgment in a
currency other than Dollars, be discharged only to the extent that on the
Business Day following receipt by the Holder in such other currency of any sum
adjudged to be so due the Holder may, in accordance with normal banking
procedures, purchase Dollars with such other currency. If the Dollars so
purchased are less than the sum originally due to the Holder in Dollars, the
Company agrees, as a separate obligation and notwithstanding any such judgment,
to indemnify the Holder against such loss, and if the Dollars so purchased
exceed the sum originally due to the Holder, the Holder agrees to remit to the
Company such excess.

         SECTION 6.8 HEADINGS. The Article and Section headings used in this
Note are for convenience of reference only and shall not affect the construction
hereof.



                               Note (Nortel NPA)
                                       12
<PAGE>   78

         SECTION 6.9 SEVERABILITY. If any provision of this Note shall be held
to be invalid, illegal or unenforceable under Applicable Law in any
jurisdiction, such provision shall be ineffective only to the extent of such
invalidity, illegality or unenforceability, which shall not affect any other
provisions hereof or the validity, legality or enforceability of such provision
in any other jurisdiction.

         SECTION 6.10 WAIVER OF IMMUNITY. To the extent that the Company has or
hereafter may be entitled to claim or may acquire, for itself or any of its
assets, any immunity from suit, jurisdiction of any court or from any legal
process (whether through service of notice, attachment prior to judgment,
attachment in aid of execution, or otherwise) with respect to itself or its
property, it hereby irrevocably waives such immunity in respect of its
obligations under this Note to the extent permitted by Applicable Law and
without limiting the generality of the foregoing, agrees that the waivers set
forth in this Section shall be effective to the fullest extent now or hereafter
permitted under the Foreign Sovereign Immunities Act of 1976 of the United
States of America and are intended to be irrevocable for purposes of such Act.

         SECTION 6.11 ENGLISH LANGUAGE. Any translation of this Note into
another language shall have no interpretive effect. All documents or notices to
be delivered pursuant to or in connection with this Note shall be in the English
language, or, if any such document or notice is not in the English language,
accompanied by an English translation thereof, and the English language version
of any such document or notice shall control for purposes hereof.

         SECTION 6.12 WAIVER OF TRIAL BY JURY. THE COMPANY AND THE HOLDER WAIVE
THE RIGHT TO A TRIAL BY JURY IN ANY ACTION UNDER THIS NOTE OR ANY ACTION ARISING
OUT OF THE TRANSACTIONS CONTEMPLATED HEREBY, REGARDLESS OF WHICH PARTY INITIATES
SUCH ACTION OR ACTIONS.

         SECTION 6.13 SECURITIES LAW MATTERS.

                  (a) The parties hereto acknowledge that this Note is not and
is not intended to be a "security" as defined in the Securities Act, and that
the issuance, sale and assignment of this Note is not intended to be subject to
the provisions governing the issuance, sale and transfer of "securities"
thereunder.

                  (b) The Holder, shall be deemed to make to the Company
(without regard to whether this Note is a "security" for purposes of the
Securities Act)) the following representations, warranties and covenants:

                           (i) The Holder is acquiring the Note solely for
financing or investment purposes and not with a view toward, or for sale in
connection with any distribution thereof (except for a distribution of this Note
if held by Nortel pursuant to the Syndications), has received and reviewed such
information as it deems necessary to evaluate the merits and risks of its
investment in this Note, is an "accredited investor" within the meaning of
Regulation D



                               Note (Nortel NPA)
                                       13
<PAGE>   79

promulgated under the Securities Act and has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment in this Note, including a complete loss of its
investment.

                           (ii) Any offer of Assignment or Assignment by the
Holder not made pursuant to an effective registration statement shall only be
made (A) to Persons whom the Holder reasonably believes to be "qualified
institutional buyers" as such term is defined in Rule 144A promulgated under the
Securities Act, (B) to non-U.S. Persons outside of the United States (which
shall include dealers or other professional fiduciaries in the United States
acting on a discretionary basis for beneficial owners (other than an estate or
trust) that are non-U.S. Persons) to whom the Holder reasonably believes offers
of Assignment or Assignment of the Notes may be made in reliance upon Regulation
S promulgated under the Securities Act and applicable securities legislation of
the relevant jurisdiction or (C) to other "accredited investors" within the
meaning of Regulation D promulgated under the Securities Act. The Holder will
take reasonable steps to inform, and cause each of its Affiliates to take
reasonable steps to inform, a Person acquiring this Note from the Holder or one
of its Affiliates, as the case may be, in the United States (the "Subsequent
Purchasers") that this Note (x) has not been and will not be registered under
the Securities Act, (y) is being sold to such Subsequent Purchaser without
registration under the Securities Act in reliance on Rule 144A or Regulation S
promulgated thereunder or in accordance with another exemption from registration
under the Securities Act, as the case may be, and (z) may not be offered, sold
or otherwise transferred except in compliance with the Securities Act.

         SECTION 6.14 CONSTRUCTION. This Note is in all respects subject to the
Note Purchase Agreement pursuant to which it was issued, all of which is hereby
incorporated herein by reference. In case of any inconsistency between the terms
and conditions of this Note and the Note Purchase Agreement, the terms and
conditions of the Note Purchase Agreement shall govern.


                                       VESPER S.A., a sociedade anonima
                                       organized under the laws of Brazil


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

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


                                       -----------------------------------------
                                       Witness


                                       -----------------------------------------
                                       Witness



                               Note (Nortel NPA)
                                       14
<PAGE>   80

                                                                     EXHIBIT B-1

                                     FORM OF
                               NOTICE OF ISSUANCE


         TO:      ABN AMRO BANK N.V., AS
                  ADMINISTRATIVE AGENT
                  ABN AMRO Bank N.V.
                  Agency Services
                  1325 Avenue of the Americas, 9th Floor
                  New York, New York  10128
                  Attention: Linda Boardman


    COPY TO:      LASALLE BANK NATIONAL
                  ASSOCIATION, AS COLLATERAL
                  AGENT
                  135 S. LaSalle Street, Suite 1625
                  Chicago, Illinois 60603
                  Attention: Brian D. Ames

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         Pursuant to Article II of the Note Purchase Agreement:



                        Notice of Issuance (Nortel NPA)
                                       1
<PAGE>   81

         1. The Company hereby requests that the Purchasers purchase Notes in
the (aggregate) principal amount of $_______________ on _______________, ____(1)
in the form of a Euro-Dollar Rate Note with an Interest Period of
___________.(2)

         2. The Company hereby represents and warrants as follows:

                  (a) All of the representations and warranties contained in
Article IV of the Note Purchase Agreement and in the other Note Documents are
true and correct in all material respects on and as of the date hereof as though
made on and as of this date (except to the extent that such representations and
warranties expressly were made only as of a specific date and except to the
extent such representations and warranties are not required to be made pursuant
to Section 3.2(f) of the Note Purchase Agreement);

                  (b) No Default or Event of Default exists or would result from
the issuance of the Notes;

                  (c) Attached hereto is a copy of the Prior Approval obtained
in connection with the Notes referred to above;

                  (d) In the case of any Issuance the proceeds of which are to
be used for purposes of Section 2.2(a)(i), the reference number(s) of the
relevant invoice(s) or similar documentation evidencing the amounts being
financed with the proceeds of such Issuance are:
         __________________________________________________________________
         __________________________________________________________________; and

                  (e) The aggregate amount of the proceeds of the Issuance
requested pursuant to this Notice of Issuance will be used for the purposes set
forth below:



--------

  (1)  Must be a Euro-Dollar Business Day.

  (2)  Must comply with definition of "Interest Period."



                        Notice of Issuance (Nortel NPA)
                                       2
<PAGE>   82

Amount to be used to make payments due under the
Nortel Supply Agreement with respect to equipment
and services provided thereunder and associated
duties and taxes (other than the payment of civil
works and duties and taxes related thereto):                 $
                                                              ------------------

Amount to be used to make payments for interest on
the Notes, Investments in Vesper Cayman SPV
permitted by Section 5.4(e) of the Common Terms
Agreement, Fees payable by the Company and other
amounts (other than principal) payable to the
Paying Agent or the Purchaser Parties under the
Notes, the Note Purchase Agreement, the Fee
Letters, the Common Terms Agreement, the Exchange
Debt Agreement, the Guaranties, or the Collateral
Documents, any and all other fees and expenses
incurred by any Company Party in connection with
the Notes and the Note Purchase Agreement:                   $
                                                              ------------------

Amount to be used to make payments for civil works
and associated duties and taxes required in
connection with the Nortel Supply Agreement:                 $
                                                              ------------------

Amount to be used to refinance the Bridge Loan:              $
                                                              ------------------

Amount to make Investments permitted by the
proviso to Section 2.2(a) of the Note Purchase
Agreement that will be deposited in the Proceeds
Account:                                                     $
                                                              ------------------

                  (f) All other conditions to the Issuance of Notes set forth in
Article III of the Note Purchase Agreement are satisfied.

         3. The Company acknowledges that this Notice of Issuance is irrevocable
and that it is bound to issue Notes to the Purchasers in accordance herewith.

         Date:                  ,     .
               -----------------  ----

                                       VESPER S.A., a sociedade anonima
                                       organized under the laws of Brazil


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



                        Notice of Issuance (Nortel NPA)
                                       3
<PAGE>   83

                                                                     EXHIBIT B-2

                                     FORM OF
                         NOTICE OF RESPONSIBLE OFFICERS


TO:      ABN AMRO BANK N.V., AS ADMINISTRATIVE
         AGENT
         ABN AMRO Bank N.V.
         Agency Services
         1325 Avenue of the Americas, 9th Floor
         New York, New York  10128
         Attention:  Linda Boardman

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         The Company hereby (i) designates the following individuals as
Responsible Officers, authorized to request that the Purchasers purchase and to
take other actions on behalf of the Company with respect to the Notes and (ii)
certifies that the offices, signatures and telephone numbers of such individuals
are as follows:

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------

               NAME                         OFFICE                        SIGNATURE                     PHONE NO.
----------------------------------------------------------------------------------------------------------------------
<S>                                 <C>                     <C>                                     <C>

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

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

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

     Each Purchaser Party is hereby authorized to rely conclusively on this
   Notice of Responsible Officers with respect to the authority of any Person
                          designated as a Responsible



                  Notice of Responsible Officers (Nortel NPA)
                                        1
<PAGE>   84

Officer herein unless and until a new Notice of Responsible Officers is received
by the Administrative Agent that no longer designates such Person as a
Responsible Officer. Additional persons may be designated as Responsible
Officers, or the designation of any person may be revoked, at any time, by
subsequent Notices of Responsible Officers signed by any person who purports to
be a Senior Officer of the Company.

         The foregoing supersedes any Notice of Responsible Officers presently
in effect under the Note Purchase Agreement.

         Date:                  ,     .
               -----------------  ----

                                       VESPER S.A. a sociedade anonima organized
                                       under the laws of Brazil


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



                   Notice of Responsible Officers (Nortel NPA)
                                        2
<PAGE>   85

                                                                       EXHIBIT C


                                     FORM OF

                        PROCEEDS ACCOUNT PLEDGE AGREEMENT

         This Proceeds Account Pledge Agreement (this "Account Pledge
Agreement"), is made on December 17, 1999, by and among:

                  (a) Vesper S.A., a company (sociedade anonima) duly organized
and existing in accordance with the laws of the Federative Republic of Brazil
("Brazil"), with its head office in the City of Rio de Janeiro, State of Rio de
Janeiro, at Avenida Republica do Chile, 500, 25(0)andar, enrolled in the Legal
Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under nr.
02.730.101/0001-43, herein represented in accordance with its Bylaws (the
"Company");

                  (b) LaSalle Bank National Association, a financial institution
duly organized and existing under the laws of the United States of America, with
its offices at 135 S. LaSalle Street, Suite 1625, Chicago, Illinois ("LaSalle"),
represented herein by its duly authorized representative, as identified and
qualified in the signature pages hereof, acting as collateral agent for Nortel
(as defined below) and the other Purchasers under the Nortel Note Purchase
Agreement (as defined below) (in such capacity, together with its successors in
such capacity, the "Proceeds Collateral Agent");

                  (c) BBA-Capital DTVM S.A., a financial institution duly
organized and existing under the laws of Brazil, with its registered office in
the City of Sao Paulo, Avenida Paulista, 37, 10(0) andar, enrolled in the Legal
Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under nr.
33.311.713/0001-25, represented herein by its duly authorized representative, as
identified and qualified in the signature pages hereof (in such capacity,
together with its successors in such capacity, the "Fund Administrator"); and

                  (d) Fibra DTVM Ltda., a financial institution duly organized
and existing under the laws of Brazil, with its registered office in the City of
Sao Paulo, Avenida Brigadeiro Faria Lima, 3064, 7(0) andar, enrolled in the
Legal Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under
nr. 30.711.501/0001-47, represented herein by its duly authorized
representative, as identified and qualified in the signature pages hereof (in
such capacity, together with its successors in such capacity, the "Fund
Manager").

                               W I T N E S S E T H

         WHEREAS, the Company has entered into (i) that certain Secured Note
Purchase Agreement dated as of December 13, 1999 (as amended from time to time,
the "Nortel Note Purchase Agreement") with ABN AMRO Bank N.V. ("ABN AMRO"), as
administrative agent (in such capacity, the "Nortel Facility Agent"), Nortel
Networks Corporation ("Nortel"), as initial Purchaser, and the other Purchasers
from time to time party thereto (all such parties, together with the Proceeds
Collateral Agent and the Collateral Agent (as defined below), the "Nortel
Purchaser Parties"); (ii) that certain Secured Note Purchase Agreement dated as
of December 13,

                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 1 of 24


<PAGE>   86

1999 (as amended from time to time, the "Qualcomm/Ericsson Note Purchase
Agreement") with ABN AMRO, as administrative agent (in such capacity, the
"Qualcomm/Ericsson Facility Agent"), ABN AMRO and Qualcomm Incorporated, as
initial Purchasers, and the other Purchasers from time to time party thereto,
and Telefonaktiebolaget LM Ericsson (publ.) ("Ericsson"), individually; and
(iii) that certain Secured Note Purchase Agreement dated as of December 13, 1999
(as amended from time to time, the "Harris Note Purchase Agreement" and,
together with the Nortel Note Purchase Agreement and the Qualcomm/Ericsson Note
Purchase Agreement, the "Note Purchase Agreements") with Harris Corporation
("Harris"), as administrative agent (in such capacity, the "Harris Facility
Agent" and, together with the Nortel Facility Agent and the Qualcomm/Ericsson
Facility Agent, the "Initial Facility Agents"), Harris, as initial Purchaser,
and the other Purchasers from time to time party thereto;

         WHEREAS, in connection with the Nortel Note Purchase Agreement, HoldCo,
the Company, the Initial Facility Agents and LaSalle in its capacity as the
collateral agent thereunder (the "Collateral Agent") have entered into that
certain Common Terms Agreement dated as of December 13, 1999 (as amended from
time to time, the "Common Terms Agreement") which sets forth certain common
terms, conditions and covenants relating to, among other things, the Nortel Note
Purchase Agreement;

         WHEREAS, the Company may, pursuant to the terms and conditions set
forth in the Common Terms Agreement, after the date hereof, enter into Interest
Hedge Agreements with a Pari Passu Creditor (as defined in the Common Terms
Agreement), any Affiliate of a Pari Passu Creditor or any other financial
institution reasonably acceptable to the Proceeds Collateral Agent, that acts as
the counterparty in any Interest Hedge Agreement in respect of the Secured
Obligations (as defined below) (a "Swap Lender" and, together with the Nortel
Purchasers, the "Secured Parties");

         WHEREAS, it is a covenant entered into in connection with the
purchasing of the Notes under the Nortel Note Purchase Agreement that the
Company constitute a first priority security interest in favor of the Proceeds
Collateral Agent, for the benefit of the Secured Parties in, on and to all
right, title and interest, whether now existing or hereafter acquired, in (i)
the Proceeds Account, including the credit balance from time to time of the
Proceeds Account, all funds and investments at any time held in or for the
Proceeds Account, all interest, dividends and other income derived from any such
balances, funds and Investments and all moneys and Investments required to be
held in or for the Proceeds Account, (ii) all statements, certificates and
instruments representing or evidencing the Proceeds Account (including the
reports referred to in Section 9(c) hereof) and all Investments and other
property listed on Exhibit 1 hereto as well as those from time to time received,
receivable or otherwise distributed in respect of such Investments and held in
or credited to the Proceeds Account, (iii) all of the quotas of any investment
fund listed from time to time on Exhibit 1 hereto in which any proceeds of the
Initial Issuance of the Notes pursuant to the Nortel Note Purchase Agreement are
from time to time invested in accordance with the provisions of the Nortel Note
Purchase Agreement, and (iv) to the extent not included in the foregoing, all
proceeds, products and accessions of and to any and all of the foregoing,
including whatever is received upon any collection, exchange, sale or other
disposition of any of the foregoing and any property into which any of the
foregoing is converted, whether cash or non-cash proceeds, and any and all other
amounts paid or payable


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 2 of 24
<PAGE>   87

under or in connection with any of the foregoing (items (i), (ii) and (iii)
together with all proceeds and products therefrom are collectively referred to
herein as the "Pledged Assets"); and

         WHEREAS, it is a covenant entered into in connection with the
purchasing of the Notes under the Nortel Note Purchase Agreement that the
Company shall have executed and delivered this Account Pledge Agreement to the
Proceeds Collateral Agent for the ratable benefit of the Secured Parties.

         NOW, THEREFORE, in consideration of the foregoing premises and mutual
covenants contained herein, the parties hereto agree as follows:

         1.       Defined Terms.

                  (a) Capitalized terms used and not otherwise defined in this
Account Pledge Agreement are used herein with the same meanings ascribed to them
in the Nortel Note Purchase Agreement (including terms defined therein by
reference to the Common Terms Agreement). All terms defined in this Account
Pledge Agreement in the singular shall have the same meanings when used in the
plural and vice versa. The words "hereof," "herein," and "hereunder" and words
of similar import when used in this Account Pledge Agreement shall, unless the
context otherwise requires, refer to this Account Pledge Agreement as a whole
and not to any particular provision of this Account Pledge Agreement, and
section, subsection, schedule and exhibit references are to this Account Pledge
Agreement unless otherwise specified. All terms defined in this Account Pledge
Agreement shall have the defined meanings contained herein when used in any
certificate or other document made or delivered pursuant hereto.

                  (b) Except as otherwise stated herein, all terms and
conditions of the Nortel Note Purchase Agreement, the Common Terms Agreement
(including Article 1 and, except for Sections 10.8, 10.9, 10.19 and 10.20 and
Article 10 thereof), the other Note Documents and, when executed and delivered,
the Interest Hedge Agreements, shall fully and automatically apply to this
Account Pledge Agreement, mutatis mutandis, and shall be deemed as an integral
part hereof, as if they were transcribed herein.

         2.       Pledge; Grant of Security Interest.

                  (a) In order to secure the full and prompt payment and
performance when due (whether at the stated maturity, by acceleration or
otherwise) of all obligations and liabilities of the Company under the Nortel
Note Purchase Agreement and any Note issued thereunder and of all obligations
and liabilities of the Company to the Secured Parties, which may arise under,
out of, or in connection with, the Nortel Note Purchase Agreement, the Common
Terms Agreement, or any other Note Document, whether on account of principal,
interest, reimbursement obligations, fees, indemnities, costs, expenses or
otherwise (including, without limitation, all fees and disbursements of counsel
to the Secured Parties that are required to be paid by the Company pursuant to
the terms of the Nortel Note Purchase Agreement, the Common Terms Agreement and
any other Note Document) (the "Obligations"), and all obligations of the Company
to the Proceeds Collateral Agent or Secured Parties created under this Account
Pledge Agreement (such obligations together with the Obligations being
collectively referred to as the "Secured Obligations"), which for the purposes
of Article 761 of the Brazilian Civil Code, are estimated to


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 3 of 24
<PAGE>   88

be in (but expressly not limited to) the principal amount of up to
US$1,019,000,000, equivalent on the date hereof to R$1,875,673,300, with
original final maturity on July 1, 2012 (subject to mandatory and optional
repurchase and acceleration thereunder) or as otherwise provided for in the
Nortel Note Purchase Agreement, the Common Terms Agreement or the Notes the
Company hereby pledges the Pledged Assets to the Proceeds Collateral Agent for
the benefit of the Secured Parties, pursuant to the provisions of Articles 271
to 279 of the Brazilian Commercial Code and Article 768 et seq. of the Brazilian
Civil Code.

                  (b) The Company shall establish a special, segregated,
restricted and irrevocable investment account which shall be maintained, at all
times until the termination of this Account Pledge Agreement (the "Proceeds
Account"), in the exclusive possession and control of the Fund Administrator,
and which shall at all times be subject to this Account Pledge Agreement, the
Nortel Note Purchase Agreement and the Common Terms Agreement.

                  (c) All funds from the Initial Issuance of Notes and any funds
otherwise to be deposited in the Proceeds Account in accordance with the terms
of this Account Pledge Agreement, the Nortel Note Purchase Agreement and the
Common Terms Agreement shall immediately be applied to the investment by the
Company in quotas of the funds listed in Exhibit 1 hereto, each of which shall
be an exclusive investment mutual fund (fundo de investimento financeiro
exclusivo) having the Fund Administrator as non-discretionary exclusive
administrator and having the Fund Manager as exclusive manager of the Fund's
portfolio (each, a "Fund").

         3. Restriction on Transfer and Encumbrance. The Pledged Assets may not
be sold or transferred by the Company (except as permitted under the Nortel Note
Purchase Agreement) or by any other means whatsoever become subject to any Liens
(except for those created hereby and those permitted under the Common Terms
Agreement) until this Account Pledge Agreement is terminated pursuant to Section
15 hereof.

         4. Registration of the Pledge of the Pledged Assets. The Company shall,
within 15 days after the execution of this Account Pledge Agreement or any
Amendment (as defined below) entered into in accordance with Section 6, register
this Account Pledge Agreement or such Amendment, together with its sworn
translation into the Portuguese language, with the competent Registry of Titles
and Deeds (Cartorio de Registro de Titulos e Documentos) in Brazil and deliver
to the Proceeds Collateral Agent evidence of such registration in form and
substance reasonably satisfactory to the Proceeds Collateral Agent. All expenses
incurred in connection with such sworn translation and with such registrations
shall be paid by the Company.

         5. Representations and Warranties. The Company hereby repeats herein as
of the date hereof all of the representations and warranties set forth in
Article 3 of the Common Terms Agreement, except for the representation and
warranty set forth in the third sentence of Section 3.2 of the Common Terms
Agreement. In addition, the Company hereby represents and warrants to the
Proceeds Collateral Agent, for the benefit of the Secured Parties, as follows:

                  (a) This Account Pledge Agreement constitutes a legal, valid
and binding obligation of the Company, enforceable against the Company in
accordance with its terms, and the security interest created hereby shall, upon
completion of the registration required by Section


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 4 of 24
<PAGE>   89

4 hereof, constitute a legal, valid and perfected first priority security
interest in the Pledged Assets, enforceable in accordance with its terms against
all creditors of the Company, in each case as enforcement may be limited by
bankruptcy, insolvency, reorganization, moratorium and other similar laws
relating to creditors' rights generally; provided, however, that any security
interest to be created hereby in any Pledged Asset which has not been issued to,
or received or acquired by, the Company on or before the date hereof shall be
deemed to have been created, perfected and to be in full force only (i) after
such Pledged Asset is issued to, or received or acquired by, the Company and
(ii) on the date when the Lien of the Proceeds Collateral Agent, for the ratable
benefit of the Secured Parties thereon, shall have been registered as provided
in Section 4 hereof or as may be in the future required by Brazilian law; and
provided further that, the pledge created hereby will secure the obligations of
the Company to such Swap Lender only upon the effectiveness of the relevant
Interest Hedge Agreement and the registrations required by Section 4 hereof.

         6. Covenants. The Company shall promptly enter into amendments to this
Pledge Agreement with the Proceeds Collateral Agent, substantially in the form
of Exhibit 3 hereto (each an "Amendment") (a) upon investment of any funds
contained in the Proceeds Account (including any investment in or acquisition of
quotas of a Fund), and as required under the Nortel Note Purchase Agreement, in
order to extend the Lien created hereunder to the relevant Investment as well as
any statements, certificates, instruments or receipts, either physical or
electronic, evidencing such Investment (which shall then be subject to all terms
and conditions provided herein) promptly after title to such Investment is
acquired by the Company, all pursuant to the provisions of the Nortel Note
Purchase Agreement, and (b) upon the entering by the Company into any Interest
Hedge Agreement, in order to extend the Lien created hereby to each Swap Lender
thereunder to secure the obligations assumed by the Company thereunder; and the
Company shall make all filings and registrations and obtain all authorizations
necessary to create a first priority, perfected security interest in the
relevant Pledged Assets to which the security interest created hereby was
extended in favor of the Proceeds Collateral Agent for the benefit of the
Secured Parties, including the Swap Lenders under such Interest Hedge Agreement,
and take such further actions as the Proceeds Collateral Agent may reasonably
request for the purposes of obtaining or preserving the full benefits of this
Account Pledge Agreement and of the rights and powers herein granted with
respect to all such after-acquired Pledged Assets and in favor of all such
subsequent Secured Parties. The Fund Administrator shall, to the extent
necessary under Brazilian law, include a legend in any such statements,
certificates, instruments or receipts, as appropriate, evidencing that such
invested funds are subject to a Lien in favor of the Proceeds Collateral Agent
hereunder. The Company shall provide the Proceeds Collateral Agent with evidence
of the registration of each such Amendment in the appropriate Registry of Titles
and Deeds in Brazil (Cartorio de Registro de Titulos e Documentos) within
fifteen (15) days after the execution of such Amendment.

         7. Appointment, Duties and Limits to the Responsibilities of the Fund
Administrator and the Fund Manager.

                  (a) The Company and the Proceeds Collateral Agent hereby
appoint and constitute the Fund Administrator as administrator and the Fund
Manager as the manager of the Fund's portfolio of the Pledged Assets upon their
creation. The Fund Administrator assumes


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 5 of 24
<PAGE>   90

total and sole responsibility for administration of the custody, registrar
services, payment of all applicable taxes and net asset value calculation with
respect to the Fund. The Fund Manager assumes total and sole responsibility for
the Fund's portfolio management, its compliance with all Applicable Laws and
regulations and the investment by the Fund only in investments described in
clause (e) of this Section 7 of this Account Pledge Agreement. The Fund
Administrator shall be subject to the provisions set forth in this Account
Pledge Agreement and in Applicable Laws related to the administration of
investment funds in Brazil and the Fund Manager shall be subject to the
provisions set forth in this Account Pledge Agreement and in Applicable Laws
related to the management of investment funds and management of investment funds
portfolios in Brazil.

                  (b) Prior to the occurrence of an Event of Default (as
evidenced by a written notice from the Proceeds Collateral Agent to the Fund
Administrator and to the Fund Manager irrespective of any notice to the contrary
from the Company), the Fund Manager shall make investments with funds deposited
in the Fund ("Investments") in or otherwise administer the Proceeds Account
pursuant to the provisions set forth in clause (e) of this Section 7 of this
Account Pledge Agreement. Upon the occurrence and during the continuation of an
Event of Default (as evidenced by a written notice from the Proceeds Collateral
Agent to the Fund Administrator and to the Fund Administrator irrespective of
any notice to the contrary from the Company), the Fund Manager shall only act
pursuant to the instructions it receives from the Proceeds Collateral Agent with
respect to the Proceeds Account, the Fund and the funds on deposit therein or
the Investments made with such funds, the Pledged Assets or any other provision
of this Account Pledge Agreement.

                  (c) The Company and the Proceeds Collateral Agent hereby vest
the Fund Administrator with full powers administer the Fund and the Fund Manager
to manage the Fund's portfolio invest the funds deposited in the Proceeds
Account as directed by the Company (except as expressly otherwise provided in
Section 7(b) above). Nothing contained herein shall, however, prevent the
Proceeds Collateral Agent upon the occurrence and during the continuation of an
Event of Default (as evidenced by a written notice from the Proceeds Collateral
Agent to the Fund Administrator and to the Fund Manager irrespective of any
notice to the contrary from the Company) from instructing the Fund Manager, from
time to time, as to the investment of such funds.

                  (d) The Company and the Proceeds Collateral Agent hereby agree
that any such Investment may be liquidated (without regard to maturity date) by
the Proceeds Collateral Agent whenever necessary to make any distribution or
transfer required by this Account Pledge Agreement. Neither the Fund
Administrator, the Fund Manager nor, except to the extent provided in Section
7.2 of the Nortel Note Purchase Agreement, the Proceeds Collateral Agent, shall
have any liability for any investment loss resulting from any such liquidation
of Investments. Additionally, the Fund Manager shall have no liability for any
loss resulting from decline in value of the Fund or any other Pledged Assets in
response to market fluctuations and/or defaults (credit risks), including losses
of the entire amount invested, so long as it is acting in accordance with the
terms and conditions of this Account Pledge Agreement and Applicable Law. It is
hereby acknowledged and agreed by the Company and the Proceeds Collateral Agent
that the Fund Administrator has no responsibility whatsoever with regard to


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 6 of 24
<PAGE>   91
management of the Fund's portfolio, the Fund's performance, results, risks and
losses, the Fund's compliance with all Applicable Laws and regulations, and the
investment by the Fund only in investments described in clause (e) of this
Section 7 of this Account Pledge Agreement, as provided in clauses (a) and (f)
of this Section 7 and in Section 8 of this Account Pledge Agreement.

                  (e) The Fund shall only make Investments in (i) certificates
of deposit or export notes, (A) not less than US$125,000,000 in principal amount
of which shall mature within ninety days from the date of acquisition thereof
and the balance of which shall mature within 180 days from the date of
acquisition thereof, in each case (B) are subject to a swap agreement that has
the effect of indexing the principal amount of thereof to Dollars and is with a
counterparty that is reasonably acceptable to the Proceeds Collateral Agent
(acting pursuant to the instructions of Nortel in accordance with the Nortel
Note Purchase Agreement) and (C) is issued by a financial institution with a
short-term debt rating of A1 and/or P1 reasonably acceptable to the Proceeds
Collateral Agent (acting pursuant to the instructions of Nortel in accordance
with the Nortel Note Purchase Agreement); or (ii) Investments approved by the
Proceeds Collateral Agent (acting pursuant to the instructions of Nortel in
accordance with the Nortel Note Purchase Agreement) in its discretion; provided,
however, that the Fund Administrator shall have no duty to make any inquiry into
the authority of the Proceeds Collateral Agent to approve any swap counterparty,
financial institution or Investment hereunder.

                  (f) It is hereby acknowledged and agreed by the Company and
the Proceeds Collateral Agent (i) that neither the Fund Administrator nor the
Fund Manager is a party to the Nortel Note Purchase Agreement, the Common Terms
Agreement, or any of the other Note Documents, other than this Account Pledge
Agreement and neither the Fund Administrator nor the Fund Manager shall be bound
by the terms and provisions of any document to which they are not a party, other
than any notice given under this Account Pledge Agreement, (ii) that the duties
and responsibilities of the Fund Administrator and those of the Fund Manager are
separate and distinct and that each shall be responsible for and liable only for
their respective duties and obligations as set forth in this Account Pledge
Agreement, (iii) that neither the Fund Administrator nor the Fund Manager shall
have any duty to inquire as to the authority of the Proceeds Collateral Agent or
the Company to give the Fund Administrator or the Fund Manager any notice or
instruction or as to the terms or provisions of such notices or instructions,
and that each shall be conclusively entitled to and is hereby directed to act
strictly in accordance with the instructions given by the Company provided,
however, that if the Proceeds Collateral Agent gives the Fund Administrator and
the Fund Manager notice of the occurrence and continuation of an Event of
Default, each of the Fund Administrator and the Fund Manager shall be
conclusively entitled to and is hereby directed to act strictly in accordance
with the instructions given by the Proceeds Collateral Agent unless and until
the Proceeds Collateral Agent gives notices of the cessation of such Event of
Default. The Company hereby agrees to indemnify against and hold the Fund
Administrator, the Fund Manager and each of their respective officers,
representatives and employees harmless from any loss, liability, cost, claim,
action, demand or expense (including, but not limited to all reasonable costs,
charges and expenses paid or incurred in disputing or defending any of the
foregoing) which any of them may incur or which may be made against any of them
arising out of or in connection with its appointment hereunder or the exercise
of the functions of the Fund Administrator or the Fund Manager, except, in the
case of


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 7 of 24
<PAGE>   92
the Fund Administrator and its officers, representatives and employees, such as
may result from a breach by the Fund Administrator of any provision of this
Account Pledge Agreement or Applicable Law, or the gross negligence or willful
misconduct of the Fund Administrator, or in the case of the Fund Manager and its
officers, directors, employees, such as may result from a breach by the Fund
Manager of any provision of this Account Pledge Agreement, or the gross
negligence or willful misconduct of the Fund Manager.

         8. Undertakings of the Fund Administrator and of the Fund Manager.

                  (a) During the term of this Account Pledge Agreement, the Fund
Administrator expressly undertakes:

                      (i) To receive any and all amounts that shall be deposited
         by or on behalf of the Company in the Fund, effect the transfers set
         forth herein and carry on its duties for the proper administration of
         the Fund.

                      (ii) To operate and administer, or permit the operation
         and administration of, the Fund only as authorized by this Account
         Pledge Agreement.

                      (iii) To insert in its computer systems, mailing documents
         and any other system or documents, where required by Applicable Law, a
         legend stating that the operation and administration of the Proceeds
         Account and any Fund shall be in accordance with the terms and
         conditions of this Account Pledge Agreement.

                  (b) During the term of this Account Pledge Agreement, the Fund
Manager expressly undertakes:

                      (i) To operate and manage, or permit the operation and
         management of the portfolio of any Fund only as authorized by this
         Account Pledge Agreement.

                      (ii) To insert in its computer systems, mailing documents
         and any other system or documents, where required by Applicable Law, a
         legend stating that the operation and management of the Proceeds
         Account and any Fund shall be in accordance with the terms and
         conditions of this Account Pledge Agreement.

                      (iii) To invest the funds deposited in the Proceeds
         Account and any Fund only in accordance with the terms and conditions
         of this Account Pledge Agreement.

         9.       Withdrawals and Transfers.

                  (a) The Company shall have no right to withdraw any cash from
the Proceeds Account or otherwise dispose of or transfer any Pledged Assets
except as expressly provided herein and in the Nortel Note Purchase Agreement.
The Company shall instruct the Fund Administrator to redeem any quotas of the
Fund only if no Event of Default exists and to the extent necessary to make
payments for the purposes set forth in Section 2.2(a) of the Nortel Note
Purchase Agreement, provided that such instruction shall be duly approved in
writing by the Proceeds Collateral Agent.


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 8 of 24
<PAGE>   93

                  (b) The amounts to be transferred from the Proceeds Account or
as a result of a redemption or disposition of the quotas of the Fund shall be
calculated by the Company and communicated to the Fund Administrator, the Fund
Manager and the Proceeds Collateral Agent by the Company in writing at least
three (3) Business Days prior to each date on which a transfer is to be made,
which writing shall state that (i) such transfer is being made for the purposes
set forth in Section 2.2(a) (i) through (iii) of the Nortel Note Purchase
Agreement and (ii) no Event of Default then exists.

                  (c) Not later than ten (10) days after the end of each
calendar month, the Fund Administrator shall provide the Proceeds Collateral
Agent and the Company with reports in form and substance reasonably acceptable
to the Company and the Proceeds Collateral Agent on (i) the amounts deposited in
the Proceeds Account and invested in the Fund by the Company during the
preceding month, so long as any amounts have been deposited in, withdrawn from
or transferred to or from the Fund, as required by Applicable Law, so that the
Proceeds Collateral Agent and the Company is fully informed and updated in
respect of the Proceeds Account and the Fund, as well as of the total amounts
and Investments subject to the Lien created hereunder. The Fund Administrator
shall properly maintain such reports which shall at all times be deemed an
integral part hereof as if they were transcribed herein.

         10. Rights and Powers of the Proceeds Collateral Agent Upon an Event of
Default.

                  (a) If an Event of Default has occurred and is continuing, the
Proceeds Collateral Agent may give any notice (except written notice of such
Event of Default as may be required hereby or by mandatory requirements of law),
without limitation and in addition to any and all rights with respect to the
Pledged Assets granted to the Proceeds Collateral Agent or the Secured Parties
under the Nortel Note Purchase Agreement, the Common Terms Agreement and the
other Note Documents:

                      (i) personally, or by agents or attorneys, immediately
         take possession of the Pledged Assets or any part thereof, from the
         Fund Administrator, the Fund Manager, the Company or any other Person
         who then has possession of any part thereof with or without notice or
         process of law;

                      (ii) instruct the obligor or obligors on or any
         counterparties to any agreement, instrument or other obligation in
         respect of or relating to the Company or the Pledged Assets to make any
         payment required by the terms of such instrument, agreement or
         obligation directly to the Proceeds Collateral Agent or the Fund
         Administrator to be applied to the Secured Obligations in accordance
         with the terms of the Nortel Note Purchase Agreement;

                      (iii) take possession of the Pledged Assets or any part
         thereof by directing the Fund Administrator in writing to deliver the
         same to the Proceeds Collateral Agent at any place or places designated
         by the Proceeds Collateral Agent, it being understood that the Fund
         Administrator's obligation so to deliver the Pledged Assets is of the
         essence of this Account Pledge Agreement and that, accordingly, upon
         application to a court having jurisdiction, the Proceeds Collateral
         Agent shall be entitled to a judicial


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 9 of 24
<PAGE>   94
         order requiring specific performance by the Fund Administrator of such
         obligation pursuant to Articles 461, 621 and 632 of the Brazilian Civil
         Procedure Code;

                      (iv) withdraw any and all cash and liquidate any and all
         Investments in the Proceeds Account or otherwise held hereunder and
         apply such cash, the liquidation proceeds of Investments and other
         cash, if any, then held in the Proceeds Account or otherwise held
         hereunder to the Secured Obligations in accordance with the terms of
         the Nortel Note Purchase Agreement; and

                      (v) sell, assign or otherwise liquidate the Pledged Assets
         or any part thereof at public or private sale, for cash, upon credit or
         for future delivery, and at such prices as the Proceeds Collateral
         Agent may deem satisfactory and take possession of the proceeds of any
         such sale or liquidation and apply the same to the Obligations in
         accordance with the terms of the Nortel Note Purchase Agreement.

                  (b) Promptly after the cessation of an Event of Default, the
Proceeds Collateral Agent shall send written notice of such cessation to the
Fund Administrator and to the Fund Manager and the Fund Administrator and the
Fund Manager shall immediately and conclusively rely on such notice to act
pursuant to the instructions it receives from the Company with respect to the
Proceeds Account, as provided in this Agreement.

         11. Remedies. Without prejudice to any of the foregoing provisions,
upon the occurrence and during the continuation of an Event of Default, the
Proceeds Collateral Agent is hereby irrevocably authorized and entitled to
dispose of, collect, receive, appropriate and/or realize upon the Pledged Assets
(or any part thereof) and may forthwith sell, assign, give option or options to
purchase or otherwise dispose of and deliver the Pledged Assets or any part
thereof at such price and upon such terms and conditions as it may deem
appropriate, irrespective of any prior or subsequent notice to the Company, in
accordance with the provisions set forth in Article 774, Item III, of the
Brazilian Civil Code, and Article 277 of the Brazilian Commercial Code, and
apply the proceeds thus received for payment of the Secured Obligations as then
due and payable. Any notice by the Proceeds Collateral Agent that an Event of
Default has occurred and is continuing or has ceased shall be conclusive as
against the Company and all other third parties. Without limitation, upon the
occurrence and during the continuation of an Event of Default, the Proceeds
Collateral Agent shall be entitled to instruct the obligors under the
Investments constituting Pledged Assets hereunder to make payments required by
such Pledged Assets directly to the Proceeds Collateral Agent, to be applied to
the Secured Obligations as provided in the Nortel Note Purchase Agreement. The
Company hereby irrevocably appoints the Proceeds Collateral Agent as
attorney-in-fact, and for such purpose has executed and delivered to the
Proceeds Collateral Agent on the date hereof a power-of-attorney substantially
in the form of Exhibit 2 hereto. The Company agrees to deliver an equivalent
power-of-attorney to each successor Proceeds Collateral Agent. For the purposes
hereof, it is hereby agreed and understood that (a) the proceeds of any such
sale shall be applied in accordance with the terms of the Note Purchase
Agreement and (b) in the event of any deficiency of the proceeds of any such
sale or other realization, the Company shall remain liable for the payment of
the corresponding balance of the Secured Obligations.


                 Proceeds Account Pledge Agreement (Nortel NPA)

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<PAGE>   95

         12. Amendments, Etc., with Respect to the Secured Obligations. The
Company shall remain obligated hereunder, and the Pledged Assets shall remain
subject to the security interests granted hereby at all times until termination
of this Account Pledge Agreement pursuant to Section 15, notwithstanding that,
without limitation and without any reservation of rights against the Company,
and without notice to or further assent by the Company:

             (a) any demand for payment of any of the Secured Obligations made
by any Secured Party may be rescinded by such Secured Party in accordance with
the terms of the Nortel Note Purchase Agreement or Article 9 of the Common Terms
Agreement;

             (b) the Common Terms Agreement, the Nortel Note Purchase Agreement,
the Notes and any Other Pari Passu Financing Document may be amended, modified
or supplemented, in whole or part, in accordance with the terms of such
agreement; and

             (c) any guaranty, right to setoff or other collateral security at
any time held by the Proceeds Collateral Agent for the benefit of the Secured
Parties for the payment of the Secured Obligations may be sold, exchanged,
waived, surrendered or released.

         13. Certain Waivers by the Company. Neither the Proceeds Collateral
Agent nor any Secured Party shall have any obligation to protect, secure,
perfect or insure any other Lien at any time held by it as security for the
Secured Obligations or any property subject thereto. The Company waives any and
all notice of the creation, renewal, extension or accrual of any of the Secured
Obligations and notice of, or proof of reliance by, the Proceeds Collateral
Agent or any Secured Party upon this Account Pledge Agreement; each of the
Secured Obligations shall conclusively be deemed to have been created,
contracted or incurred in reliance upon this Account Pledge Agreement; and all
dealings between the Company, on the one hand, and the Proceeds Collateral Agent
and the Secured Parties, on the other, shall likewise be conclusively presumed
to have been had or consummated in reliance upon this Account Pledge Agreement.
The Company waives diligence, presentment, protest, demand for payment and
notice of default or nonpayment to or upon the Company with respect to the
Secured Obligations.

         14. Pursuit of Rights and Remedies Against the Company. When pursuing
its rights and remedies hereunder against the Company, the Proceeds Collateral
Agent may, but shall be under no obligation to, pursue such rights and remedies
as it may have against any third party or against any collateral security for or
Guaranty of the Secured Obligations or any right of offset with respect thereto,
and any failure by the Proceeds Collateral Agent to pursue such other rights or
remedies or to collect any payments from such third party or to realize upon any
such collateral security or Guaranty or to exercise any such right of offset, or
any release of such third party or of any such collateral security, Guaranty or
right of offset, shall not relieve the Company of any liability hereunder, and
shall not impair or affect the rights and remedies, whether express, implied or
available as a matter of law, of the Proceeds Collateral Agent or the Secured
Parties.

         15. Termination and Release. When the Secured Obligations have been
indefeasibly satisfied in full, the Notes are no longer outstanding, no other
amount is then outstanding or owing to any Secured Party under any Interest
Hedge Agreement, any Note or the Nortel Note Purchase Agreement and all
Commitments under the Nortel Note Purchase Agreement have terminated, then, and
only then, shall this Account Pledge Agreement and the security interests


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 11 of 24
<PAGE>   96
created hereby be released and this Account Pledge Agreement shall terminate, at
the Company's expense; otherwise, this Account Pledge Agreement and the security
interests created hereby shall remain in full force and effect. No release of
this Account Pledge Agreement, or of the Lien created and evidenced hereby,
shall be valid unless executed by the Proceeds Collateral Agent and acknowledged
by Nortel. The Proceeds Collateral Agent, upon the Company's request, at the
Company's expense and to the extent authorized to do so by Article 7 of the
Nortel Note Purchase Agreement and in accordance with this Section 15, shall
execute and deliver to the Company all documents reasonably necessary to
evidence such release. To the fullest extent permitted by Applicable Law, this
Account Pledge Agreement shall continue to be effective or be reinstated, as the
case may be, if at any time any amount received by the Proceeds Collateral Agent
or any other Secured Party in respect of the Secured Obligations is rescinded or
must otherwise be restored or returned by the Proceeds Collateral Agent or such
Secured Party upon the insolvency, bankruptcy, dissolution, liquidation or
reorganization of the Company or upon the appointment of any intervenor or
conservator of, or agent or similar official for, the Company or any part of its
assets, or otherwise, all as though such payments had not been made.

         16. Resignation or Removal of the Fund Administrator and the Fund
Manager. The Fund Administrator and Fund Manager may resign at any time by
giving at least thirty (30) days' prior written notice thereof to the Proceeds
Collateral Agent and the Company and may be removed at any time with or without
cause by the Company, or upon the occurrence and during the continuation of an
Event of Default (as evidenced by a written notice from the Proceeds Collateral
Agent to the Fund Administrator and to the Fund Manager) by the Proceeds
Collateral Agent. Upon any such resignation or removal, the Company shall have
the right to appoint a successor administrator or manager, as the case may be,
subject to prior approval of any such successor administrator or manager, as the
case may be, by the Proceeds Collateral Agent (which approval shall not be
unreasonably withheld). If no successor administrator or manager, as the case
may be, shall have been so appointed by the Company and shall have accepted its
appointment within thirty (30) days after the resignation or removal of the
retiring Fund Administrator or Fund Manager, as the case may be, the Proceeds
Collateral Agent shall have the right to appoint a successor administrator or
manager, as the case may be. Upon the acceptance of its appointment as Fund
Administrator or Fund Manager, as the case may be, the successor administrator
or manager, as the case may be, shall thereupon succeed to and be vested with
all the rights, powers, privileges and duties of the retiring Fund Administrator
or Fund Manager, as the case may be, and the retiring Fund Administrator or Fund
Manager, as the case may be, shall be discharged from its duties and obligations
under this Account Pledge Agreement.

         17. Waivers and Amendments. Notwithstanding any provisions of this
Account Pledge Agreement, no amendment of any provision of this Account Pledge
Agreement (including any waiver or consent relating thereto) shall be effective
unless the same shall have been consented to and signed in accordance with
Section 8.3 of the Nortel Note Purchase Agreement.

         18. Severability. If any provision of this Account Pledge Agreement
shall be held to be invalid, illegal or unenforceable under Applicable Law in
any jurisdiction, such provision shall be ineffective only to the extent of such
invalidity, illegality or unenforceability, and shall not affect any other
provisions hereof or the validity, legality or enforceability of such provision
in any other jurisdiction. Where provisions of any Applicable Law resulting in
such prohibition or


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 12 of 24
<PAGE>   97
unenforceability may be waived, they are hereby waived by the Company and the
Proceeds Collateral Agent to the full extent permitted by Applicable Law so that
this Account Pledge Agreement shall be deemed a valid and binding agreement, and
the security interest created hereby shall constitute a continuing first
priority Lien on and perfected, first priority security interest in the Pledged
Assets, in each case enforceable against the Company in accordance with its
terms.

         19. Authority of the Proceeds Collateral Agent. The Company
acknowledges that the rights and responsibilities of the Proceeds Collateral
Agent under this Account Pledge Agreement with respect to any action taken by
the Proceeds Collateral Agent or the exercise or non-exercise by the Proceeds
Collateral Agent of any option, request, judgment or other right or remedy
provided for herein or resulting or arising out of this Account Pledge Agreement
shall, as between the Proceeds Collateral Agent and the other Secured Parties,
be governed by the Nortel Note Purchase Agreement and by such other agreements
with respect thereto as may exist from time to time among them, but, as between
the Proceeds Collateral Agent and the Company, the Proceeds Collateral Agent
shall be conclusively presumed to be acting as agent for the Secured Parties
with full and valid authority so to act or refrain from acting, and the Company
shall be under no obligation or entitlement to make any inquiry respecting such
authority.

         20. Complete Agreement; Successors and Assigns; Third-Party
Beneficiaries. This Account Pledge Agreement is intended by the parties as the
final expression of their agreement regarding the subject matter hereof and as a
complete and exclusive statement of the terms and conditions of such agreement.
This Account Pledge Agreement shall be binding upon and inure to the benefit of
the parties hereto and their respective successors and assigns. All Secured
Parties that are not signatories to this Account Pledge Agreement are intended
to be third-party beneficiaries of this Account Pledge Agreement. Otherwise,
there are no third-party beneficiaries of this Account Pledge Agreement.

         21. Waiver of Immunity. To the extent that the Company has or hereafter
may be entitled to claim or may acquire, for itself or any of the Pledged
Assets, any immunity from suit, jurisdiction of any court or from any legal
process (whether through service of notice, attachment prior to judgment,
attachment in aid of execution, or otherwise) with respect to itself or its
property, it hereby irrevocably waives such immunity in respect of its
obligations hereunder to the extent permitted by Applicable Law.

         22. GOVERNING LAW; JURISDICTION. THIS ACCOUNT PLEDGE AGREEMENT SHALL BE
GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF BRAZIL.
THE PARTIES HERETO IRREVOCABLY SUBMIT TO THE EXCLUSIVE JURISDICTION OF THE
COURTS SITTING IN THE CITY OF RIO DE JANEIRO, BRAZIL, IN ANY ACTION OR
PROCEEDING TO RESOLVE ANY DISPUTE OR CONTROVERSY RELATED TO OR ARISING FROM THIS
ACCOUNT PLEDGE AGREEMENT AND THE PARTIES HERETO IRREVOCABLY AGREE THAT ALL
CLAIMS IN RESPECT OF SUCH ACTION OR PROCEEDING MAY BE HEARD AND DETERMINED IN
SUCH COURTS.

         23. No Duty on Agent's Part. The powers conferred on the Proceeds
Collateral Agent hereunder are solely to protect the Proceeds Collateral Agent's
and the Secured Parties' interests in the Pledged Assets and shall not impose
any duty upon the Proceeds Collateral Agent or on the


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 13 of 24
<PAGE>   98
Secured Parties to cause the Proceeds Collateral Agent to exercise any such
powers. The Proceeds Collateral Agent shall be accountable only for amounts that
it actually receives as a result of the exercise of such powers, and neither the
Proceeds Collateral Agent nor any Secured Party nor any of its respective
officers, directors, employees or agents shall be responsible to the Company for
any act or failure to act hereunder except to the extent otherwise provided in
Section 7.2 of the Nortel Note Purchase Agreement.

         24. Notices. All notices and other communications under this Account
Pledge Agreement shall be in writing and shall be personally delivered or sent
by prepaid courier, by overnight, registered or certified mail (postage
prepaid), or by facsimile, and shall be deemed given when received by the
intended recipient thereof. Unless otherwise specified in a notice sent or
delivered in accordance with Section 10.4 of the Common Terms Agreement, all
notices and other communications shall be given to the parties hereto (a) to the
attention of Brian D. Ames at the address indicated in clause (b) of the
Preamble to this Account Pledge Agreement or by facsimile to (312) 904-2084 (in
the case of the Proceeds Collateral Agent), (b) at the address (or to the
facsimile number) indicated in Schedule 10.4 of the Common Terms Agreement (in
the case of the Company), (c) to the attention of Diniz Bernardo Nunes Filho at
the address indicated in clause (c) of the Preamble to this Account Pledge
Agreement or by facsimile to (011) 3178-8599 (in the case of the Fund
Administrator or (d) to the attention of ____________________ at the address
indicated in clause (d) of the Preamble to this Account Pledge Agreement or by
facsimile to ____________________ (in the case of the Fund Manager).

         25. Survival of Agreements, Representations and Warranties. All
agreements, representations and warranties made herein shall survive the
execution and delivery of this Account Pledge Agreement and the closing and
shall continue as valid and enforceable agreements, representations and
warranties (when made hereunder) until payment and performance of any and all
Secured Obligations. Any investigation at any time made by or on behalf of the
Proceeds Collateral Agent or the Secured Parties shall not diminish the right of
the Proceeds Collateral Agent or the Secured Parties to rely thereon.


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 14 of 24
<PAGE>   99
         26. Specific Performance. For the purposes hereof, the Proceeds
Collateral Agent may, seek the specific performance of the obligations
undertaken herein by the Company, as provided in Articles 461, 621 and 632 of
the Brazilian Civil Procedure Code.

         IN WITNESS WHEREOF, the parties have caused this Proceeds Account
Pledge Agreement to be duly executed in the presence of the undersigned
witnesses.


Company:
VESPER S.A.


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


Proceeds Collateral Agent:
LASALLE BANK NATIONAL ASSOCIATION


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


Fund Administrator:
BBA-CAPITAL DTVM S.A.


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



                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 15 of 24
<PAGE>   100


Fund Manager:
FIBRA DTVM LTDA.


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


Witnesses:

------------------------------              -------------------------------
Name:                                       Name:
ID:                                         ID:


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 16 of 24
<PAGE>   101
                                                                       EXHIBIT 1


                          LIST OF INVESTMENTS AND FUNDS

Fundo de Investimento Financeiro BBA-Capital Columbus - C.N.P.J. nr.
[***]



                 Proceeds Account Pledge Agreement (Nortel NPA)

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.

                                   Page 17 of 24

<PAGE>   102
                                                                       EXHIBIT 2

                            FORM OF POWER OF ATTORNEY

         By this Power of Attorney, Vesper S.A., a company (sociedade anonima)
duly organized and existing in accordance with the laws of the Federative
Republic of Brazil, with its head office in the City of Rio de Janeiro, State of
Rio de Janeiro at Avenida Republica do Chile, 500, 25(0) andar, enrolled in the
Legal Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under
nr. 02.730.101/0001-43, herein represented in accordance with its Bylaws (the
"Appointer"), irrevocably constitutes and appoints LaSalle Bank National
Association, a financial institution duly organized and existing under the laws
of the United States of America (the "Proceeds Collateral Agent") as its
attorney-in-fact to act in its name and place, to the fullest extent permitted
by law and in accordance with the terms of the Account Pledge Agreement (as
defined below), to do and perform all and every act and thing whatsoever
necessary or desirable, in connection with the Proceeds Account Pledge Agreement
dated as of December 17, 1999, entered into by and among the Appointer, the
Proceeds Collateral Agent (for the benefit of the Secured Parties referred to
therein), the Fund Administrator and the Fund Manager (as amended, supplemented
or otherwise modified from time to time, the "Agreement") including, without
limitation:

                      (a) upon the occurrence and during the continuation of an
         Event of Default, to dispose of, collect, receive, appropriate,
         withdraw, transfer and/or realize upon the Pledged Assets (or any part
         thereof) and may forthwith sell, assign, give option or options to
         purchase or otherwise dispose of and deliver the Pledged Assets or any
         part thereof at such prices and upon such terms and conditions as it
         may deem appropriate, irrespective of any prior or subsequent notice to
         the Appointer, in accordance with the provisions set forth in Article
         774, Item III, of the Brazilian Civil Code, apply the proceeds thus
         received for the payment of the Secured Obligations, being vested with
         all necessary powers incidental thereto, including, without limitation,
         the power and authority to purchase foreign currency and make all
         remittances abroad, to sign any necessary foreign exchange contract
         with financial institutions in Brazil that may be required to make such
         remittances and to represent the Appointer before the Central Bank and
         any other Brazilian Governmental Authority when necessary to accomplish
         the purposes of the Account Pledge Agreement;

                      (b) upon the occurrence and during the continuation of an
         Event of Default, to endorse checks, to purchase foreign currency with
         any Pledged Asset and remit such currency abroad and, for this purpose,
         to take all action in connection thereto, including, without
         limitation, to execute exchange contracts and any other instruments or
         agreements and to represent the Appointer before the Central Bank of
         Brazil and any bank or financial institution in Brazil;

                      (c) upon the occurrence and during the continuation of an
         Event of Default, to take all necessary actions and to execute any
         instrument before any Governmental Authority, including, without
         limitation, the Brazilian Securities and Exchange Commission ("CVM")
         and before any stock exchange, in the case of a public sale


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 18 of 24
<PAGE>   103

         of the Pledged Assets following the occurrence and during the
         continuation of an Event of Default; and

                      (d) upon the occurrence and during the continuation of an
         Event of Default, to take any action and to execute any instrument
         consistent with the terms of the Account Pledge Agreement as the
         Proceeds Collateral Agent may deem necessary or advisable to accomplish
         the purposes of the Account Pledge Agreement.

         Any notice by the Proceeds Collateral Agent that an Event of Default
has occurred and is continuing or has ceased shall be conclusive as against the
Fund Administrator, the Fund Manager and all third parties.

         Capitalized terms used, but not defined herein, shall have the meaning
ascribed to them in the Account Pledge Agreement.

         The powers granted herein are in addition to the powers granted by the
Appointer to the Proceeds Collateral Agent in the Account Pledge Agreement and
do not cancel or revoke any of such powers.

         This power of attorney shall be irrevocable, valid and effective until
the Account Pledge Agreement has terminated in accordance with its terms.

         Any successor Proceeds Collateral Agent shall automatically succeed to
the rights of the Proceeds Collateral Agent hereunder.

         IN WITNESS WHEREOF, the Appointer has caused its duly authorized
representatives to execute this power of attorney on December 17, 1999.


Appointer:
VESPER S.A.


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



                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 19 of 24

<PAGE>   104
                                                                       EXHIBIT 3

                                     FORM OF

                 AMENDMENT TO PROCEEDS ACCOUNT PLEDGE AGREEMENT


         This [o] Amendment to the Proceeds Account Pledge Agreement
(hereinafter referred to as this "Amendment") is made as of [o] by and among:

                  (a) Vesper S.A., a company (sociedade anonima) duly organized
and existing in accordance with the laws of the Federative Republic of Brazil,
with its head office in the City of Rio de Janeiro, State of Rio de Janeiro, at
Avenida Republica do Chile, 500, 25(0) andar, enrolled in the Legal Entities
National List of the Ministry of Finance (C.N.P.J./M.F.) under nr.
02.730.101/0001-43, herein represented in accordance with its Bylaws (the
"Company");

                  (b) LaSalle Bank National Association, a financial institution
duly organized and existing under the laws of the United States of America, with
its offices at 135 S. LaSalle Street, Suite 1625, Chicago, Illinois, represented
herein by its duly authorized representative, as identified and qualified in the
signature pages hereof, acting as collateral agent for Nortel and the other
Purchasers under the Nortel Note Purchase Agreement (as defined below) (in such
capacity, together with its successors in such capacity, the "Proceeds
Collateral Agent");

                  (c) BBA-Capital DTVM S.A., a financial institution duly
organized and existing under the laws of Brazil, with its registered office in
the City of Sao Paulo, Avenida Paulista, 37, 10(0) andar, enrolled in the Legal
Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under nr.
33.311.713/0001-25, represented herein by its duly authorized representative, as
identified and qualified in the signature pages hereof (in such capacity,
together with its successors in such capacity, the "Fund Administrator"); and

                  (d) Fibra DTVM Ltda., a financial institution duly organized
and existing under the laws of Brazil, with its registered office in the City of
Sao Paulo, Avenida Brigadeiro Faria Lima, 3064, 7(0) andar, enrolled in the
Legal Entities National List of the Ministry of Finance (C.N.P.J./M.F.) under
nr. 30.711.501/0001-47, represented herein by its duly authorized
representative, as identified and qualified in the signature pages hereof (in
such capacity, together with its successors in such capacity, the "Fund
Manager").WHEREAS, on December 17, 1999, the parties hereto entered into a
Proceeds Account Pledge Agreement (the "Account Pledge Agreement"), registered
with the Registry of Titles and Deeds of the City of [o] under number [o];

         WHEREAS, the parties hereto have agreed to amend the Account Pledge
Agreement in order to [grant to the Proceeds Collateral Agent, for the ratable
benefit of the Secured Parties, a perfected first priority security interest in
the Pledged Assets]/[extend the pledge created thereunder to secure its
Obligations assumed under the Interest Hedge Agreement dated [o] entered into
between the Company and [o] (the "Secured Interest Hedge Agreement")];


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 20 of 24
<PAGE>   105
         WHEREAS, pursuant to the terms hereof, the parties hereto desire to
amend the Account Pledge Agreement;

         NOW, THEREFORE, the parties hereto enter into this Amendment No. __ to
the Account Pledge Agreement under the following terms and conditions:

                  1. Capitalized terms used and not otherwise defined herein
shall have the meaning ascribed to them in the Account Pledge Agreement.

                  2. The Company hereby [pledges, and transfers any additional
Pledged Assets contained in the new Exhibit 1 attached hereto (and which were
not contained in the original Exhibit 1 of the Account Pledge Agreement) to the
Proceeds Collateral Agent, for the benefit of the Secured Parties]/[extends the
pledge created under the Account Pledge Agreement to secure its Obligations
under the Secured Interest Hedge Agreement and for purposes hereof and of the
Account Pledge Agreement, each of the Swap Lenders party to the Secured Interest
Hedge Agreement shall be a Secured Party under the Account Pledge Agreement].

                  3. The Company hereby represents and warrants to and in favor
of the Proceeds Collateral Agent, for the benefit of the Secured Parties that:

                      (a) The execution, delivery, performance and [grant of the
         security interest/extension of the pledge created under the Account
         Pledge Agreement] pursuant to this Amendment have been duly authorized
         by all necessary corporate action on the part of the Company. This
         Amendment has been duly executed and delivered by the Company. The
         execution, delivery, performance and [grant of the security
         interest/extension of the pledge created under the Account Pledge
         Agreement] do not and will not (i) violate any provision of any charter
         or other organizational documents of the Company, (ii) conflict with,
         result in a breach of, or constitute (or, with the giving of notice or
         lapse of time or both, would constitute) a default under, or, except
         for consents and approvals that have been obtained and are in full
         force and effect, require the approval or consent of any Person
         pursuant to, any material Contractual Obligation of the Company
         (including any provisions of any Material Contract or any contracts
         relating to Debt to which the Company is a party), or violate any
         Applicable Law binding on the Company, or (iii) result in the creation
         or imposition of any Lien upon any asset of the Company or any income
         or profits therefrom, except for the Lien [created/extended] hereby in
         favor of the Proceeds Collateral Agent, for the ratable benefit of the
         Secured Parties, under the Account Pledge Agreement.

                      (b) This Amendment and the Account Pledge Agreement, as
         amended hereby, each constitutes a legal, valid and binding obligation
         of the Company, enforceable against the Company in accordance with its
         terms, and the security interest [created/extended] hereby shall, upon
         completion of the registrations required by Section 5 hereof,
         constitute the legal, valid and perfected first priority security
         interest in the Pledged Assets, enforceable in accordance with its
         terms against all creditors of the Company, in each case, except as
         enforcement may be limited by bankruptcy, insolvency, reorganization,
         moratorium or other similar laws relating to creditors' rights
         generally.


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 21 of 24
<PAGE>   106

         4. All provisions of the Account Pledge Agreement not amended or
modified herein shall remain in full force and effect in accordance with the
terms of the Account Pledge Agreement.

         5. The Company, at its own cost and expense, shall, within fifteen (15)
days after the execution of this Amendment, register this Amendment, together
with a sworn translation into the Portuguese language, with the competent
Registry of Titles and Deeds (Cartorio de Registro de Titulos e Documentos) in
Brazil and deliver to the Proceeds Collateral Agent evidence of such
registration in form and substance reasonably satisfactory to the Proceeds
Collateral Agent.


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 22 of 24
<PAGE>   107
         IN WITNESS WHEREOF, the undersigned have caused this Amendment No. ___
to Proceeds Account Pledge Agreement to be executed in the presence of the
undersigned witnesses.

Company:
VESPER S.A.



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


Proceeds Collateral Agent:
LASALLE BANK NATIONAL ASSOCIATION



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


Fund Administrator:
BBA-CAPITAL DTVM S.A.


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


                 Proceeds Account Pledge Agreement (Nortel NPA)

                                   Page 23 of 24
<PAGE>   108
Fund Manager:
FIBRA DTVM LTDA.


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


Witnesses:



-----------------------------               -------------------------------
Name:                                       Name:
ID:

                 Proceeds Account Pledge Agreement (Nortel NPA)

                                 Page 24 of 24
<PAGE>   109

                                                                       EXHIBIT D

                                     FORM OF
                        NOTICE OF CONVERSION/CONTINUATION


TO:      ABN AMRO BANK N.V., AS
         ADMINISTRATIVE AGENT
         ABN AMRO Bank N.V.
         Agency Services
         1325 Avenue of the Americas, 9th Floor
         New York, New York  10128
         Attention: Linda Boardman

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         Pursuant to Section 2.3(c) of the Note Purchase Agreement:

         (FOR CONVERSION OF BASE RATE INTO EURO-DOLLAR RATE)

         The Company hereby requests to convert $_______________ of presently
outstanding Base Rate Notes on ______________, ____ into Euro-Dollar Rate Notes
with an Interest Period of ___________ month(s) expiring on ______________,
_________. Evidence of the Prior Approval for the requested conversion is
attached as an appendix hereto.

         (FOR CONVERSION OF EURO-DOLLAR RATE INTO BASE RATE)

         The Company hereby requests to convert $_______________ of presently
outstanding Euro-Dollar Rate Notes, with an Interest Period of ___________
expiring on ______________, ____ into Base Rate Notes. Evidence of the Prior
Approval for the requested conversion is attached as an appendix hereto.



                 Notice of Conversion/Contiguation (Nortel NPA)
                                       1
<PAGE>   110

         (FOR CONTINUATION OF EURO-DOLLAR RATE)

         The Company hereby requests to continue $_______________ of presently
outstanding Euro-Dollar Rate Notes with an Interest Period of ___________
month(s) expiring on ______________, ____ as Euro-Dollar Rate Notes with an
Interest Period of ___________ month(s) expiring on ______________, _________.

         Date:                  ,     .
               -----------------  ----

                                       VESPER S.A., a sociedade anonima
                                       organized under the laws of Brazil


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



                 Notice of Conversion/Contiguation (Nortel NPA)
                                       2
<PAGE>   111

                                                                       EXHIBIT E

                                     FORM OF
                          COMMITMENT INCREASE AGREEMENT

                           Dated               ,      .
                                 --------------  -----

TO:      ABN AMRO BANK N.V., AS
         ADMINISTRATIVE AGENT
         ABN AMRO Bank N.V.
         Agency Services
         1325 Avenue of the Americas, 9th Floor
         New York, New York  10128
         Attention: Linda Boardman

         VESPER S.A.
         Avenida Republica do Chile, 500,
         25(Degree) andar
         Centro Rio de Janiero - RJ
         Brazil
         Attention: Robert Birch

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         Pursuant to Section 2.5 of the Note Purchase Agreement:

         1. The undersigned Purchaser or Eligible Assignee agrees to an increase
in its Commitment of $_______________ or to a Commitment of $_______________.

         2. The undersigned Purchaser or Eligible Assignee agrees that it shall
be a Purchaser with reference to the increase in its Commitment or to the
Commitment stated in paragraph 1 hereof.



                   Commitment Increase Agreement (Nortel NPA)
                                        1
<PAGE>   112

         3. Except as is otherwise provided in Section 2.5(a) of the Note
Purchase Agreement, effective upon the due execution and delivery to the Company
and the Administrative Agent of this Commitment Increase Agreement, the
undersigned Purchaser or Eligible Assignee shall have an aggregate Commitment of
$_______________.

         4. THIS COMMITMENT INCREASE AGREEMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF NEW YORK.

                                       [NAME OF PURCHASER/ELIGIBLE ASSIGNEE]

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


Accepted this _____ day of
_________________, ____

ABN AMRO BANK N.V., AS ADMINISTRATIVE AGENT

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

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


Accepted this _____ day of
_________________, ____

VESPER S.A.

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

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



                   Commitment Increase Agreement (Nortel NPA)
                                       2
<PAGE>   113

                                                                       EXHIBIT F

                                     FORM OF
                            CANCELLATION CERTIFICATE


TO:      ABN AMRO BANK N.V., AS
         ADMINISTRATIVE AGENT
         ABN AMRO Bank N.V.
         Agency Services
         1325 Avenue of the Americas, 9th Floor
         New York, New York  10128
         Attention: Linda Boardman


         NORTEL NETWORKS CORPORATION
         8200 Dixie Road, Suite 100
         Brampton, Ontario L6T5P6
         Attention: Treasurer

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         This Cancellation Certificate is being delivered pursuant to Section
2.5(f) of the Note Purchase Agreement. As of the date hereof, the undersigned,
in his or her capacity as chief financial officer of the Company, certifies as
follows:

         1. I have reviewed the terms of the Note Documents and have made, or
have caused to be made under my supervision, a review in reasonable detail of
the transactions and condition of the Company as of the date hereof.



                     Cancellation Certificate (Nortel NPA)
                                        1
<PAGE>   114

         2. Such review has revealed that, for the reason(s) indicated below,
the Company may exercise its right, pursuant to Section 2.5(f) of the Note
Purchase Agreement, to terminate in whole or permanently reduce in part the
Commitments of the Purchasers:(3)

                  [ ] Availability of alternative funds at least equal to the
amount of the Commitments requested to be terminated or reduced.

                  [ ] The Commitments requested to be terminated or reduced are
no longer required by the Company to complete the Project.

         3. The Company has set forth, in Appendix A hereto, the reasons, in
reasonable detail, for such termination or reduction and financial projections
for the Company supporting the statements made in paragraph 2 hereof.

         4. The Company desires to terminate or reduce the Commitments of the
Purchasers as of ______________, _____, in the amount of $_______________.(4)



----------

  (3)  Check the box indicating applicable basis for the exercise of the right
       to terminate in whole or permanently reduce in part.

  (4)  Such termination or reduction to be made on a pro rata basis in an amount
       not less than the Commitment Usage of all Lenders as of the date hereof
       and in minimum amount of $5,000,000 and integral multiples of $1,000,000.



                     Cancellation Certificate (Nortel NPA)
                                        2
<PAGE>   115

         The undersigned has executed this Cancellation Certificate as of the
___th day of _______________, _____.


                                       VESPER S.A., a sociedade anonima
                                       organized under the laws of Brazil


                                       By:
                                          --------------------------------------
                                       Name:
                                            ------------------------------------
                                       Title: Chief Financial Officer


Acknowledged this _____ day of
_________________, ____

ABN AMRO BANK N.V., AS ADMINISTRATIVE AGENT

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

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


Accepted this _____ day of
_________________, ____

NORTEL NETWORKS CORPORATION

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

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



                     Cancellation Certificate (Nortel NPA)
                                        3
<PAGE>   116

                                   APPENDIX A

            REASONS FOR TERMINATION/REDUCTION; FINANCIAL PROJECTIONS



                     Cancellation Certificate (Nortel NPA)
                                       4
<PAGE>   117

                                                                     EXHIBIT G-1

                        FORM OF ASSIGNMENT AND ACCEPTANCE
                                 (NON-RECOURSE)

                           Dated               ,
                                 --------------  ----

TO:      ABN AMRO BANK N.V., AS
         ADMINISTRATIVE AGENT
         ABN AMRO Bank N.V.
         Agency Services
         1325 Avenue of the Americas, 9th Floor
         New York, New York  10128
         Attention: Linda Boardman

         Reference is hereby made to the Secured Note Purchase Agreement, dated
as of December 13, 1999 (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"); NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser;
the banks and other entities that either now or in the future are parties
thereto as Purchasers; ABN AMRO BANK N.V. ("ABN AMRO"), as administrative agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"); and
NORTEL, individually.

         Capitalized terms used but not defined herein have the meanings
assigned to them in the Note Purchase Agreement (including terms defined therein
by reference to the Common Terms Agreement (as defined therein)).

         ____________________ (the "Assignor") and __________________ (the
"Assignee") agree as follows:

         1. Subject to Section 3 below, the Assignor hereby sells and assigns to
the Assignee, and the Assignee hereby purchases and assumes from the Assignor,
WITHOUT RECOURSE, a __________% interest in and to all of the Assignor's rights
and obligations under the Note Purchase Agreement and the other Note Documents
as of the Effective Date (as defined below), including, without limitation, such
percentage interest in the Assignor's Commitment as is in effect on the
Effective Date (as defined below) and the Notes held by the Assignor on the
Effective Date, but specifically excluding all of the Assignor's rights and
obligations [***] (if any).

         2. The Assignor (a) represents and warrants that, as of the date
hereof, its Commitment (without giving effect to assignments thereof which have
not yet become effective) is $_____________; (b) represents and warrants that it
is the legal and beneficial owner of the


[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.


                     Assignment and Acceptance (Nortel NPA)
                                        1
<PAGE>   118

interest being assigned by it hereunder and that such interest is free and clear
of any adverse claim; (c) makes no representation or warranty and assumes no
responsibility with respect to the existence, priority or value of any Lien on
any Collateral, any statements, warranties or representations made in or in
connection with the Note Purchase Agreement or any of the other Note Documents
or the execution, legality, validity, enforceability, genuineness, sufficiency
or value of the Note Purchase Agreement, any of the other Note Documents or any
other instrument or document furnished pursuant thereto; (d) makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of the Company Parties or any of their respective
obligations under the Note Documents or any other instrument or document
furnished pursuant thereto; and (e) attaches the Notes referred to in paragraph
1 above and requests that the Administrative Agent exchange such Notes for new
Notes as follows: Notes, dated ____________, ________ in the respective
principal amounts of $___________________, $___________________ and
_______________ payable to the Assignor or its registered assigns, and Notes,
dated ________________________, ________ in the respective principal amount of
$_________________, $___________________ and $___________________ payable to the
Assignee or its registered assigns.

         3. The Assignee (a) confirms that it has received a copy of the Note
Purchase Agreement and the other Note Documents, together with copies of the
financial statements referred to in Section 2.1 and 4.1 of the Common Terms
Agreement prior to the date hereof and such other documents and information as
it has deemed appropriate to make its own credit analysis and decision to enter
into this Assignment and Acceptance; (b) agrees that it will, independently and
without reliance upon the Administrative Agent or any other Purchaser Party, and
based on such documents and information as it shall deem appropriate at the
time, continue to make its own credit decisions in taking or not taking action
under the Note Purchase Agreement or the other Note Documents; (c) appoints and
authorizes the Administrative Agent and the Collateral Agent to take such
actions on its behalf and to exercise such powers under the Note Documents as
are delegated to such agent by the terms thereof, together with such powers as
are reasonably incidental thereto; (d) agrees that it will perform in accordance
with their terms all of the obligations which by the terms of the Note Purchase
Agreement or the other Note Documents are required to be performed by it as a
Purchaser; (e) specifies as its address for notices the office set forth beneath
its name on the signature pages hereof; and (f) attaches (i) in the case of an
Assignee as to which, in the reasonable judgment of such Assignee, payments
under the Note Purchase Agreement or the other Note Documents are exempt from
withholding tax of the United States of America or other applicable
jurisdiction, or are subject to such tax at a reduced rate under an applicable
tax treaty, a properly completed and executed Internal Revenue Service Form 4224
or 1001 or other applicable form, certificate or document prescribed by the
Internal Revenue Service of the United States or the appropriate taxing
authority of any relevant jurisdiction certifying as to the Assignee's
entitlement to such exemption or reduced rate with respect to all such payments,
or (ii) in the case of an Assignee as to which, in the reasonable judgment of
such Assignee, such an exemption or reduced rate of tax is not allowable with
respect to payments under the Note Purchase Agreement and the other Note
Documents, a statement of the Assignee indicating that no such exemption or
reduced rate is allowable with respect to such payments.



                     Assignment and Acceptance (Nortel NPA)
                                       2
<PAGE>   119

         4. Following the execution of this Assignment and Acceptance it will be
delivered to the Administrative Agent for acceptance and recording by the
Administrative Agent, if the Administrative Agent accepts such Assignment and
Acceptance in its discretion. The effective date of this Assignment and
Acceptance shall be ____________________ or the date on which the Administrative
Agent accepts this Assignment and Acceptance, whichever is later (the "Effective
Date"). If the Administrative Agent shall fail to accept and record this
Assignment and Acceptance prior to the expiration of ____ days after the date
hereof, this Assignment and Acceptance shall be without force and effect for any
purpose, and the Assignor shall remain the owner of the interest in the
Assignor's rights and obligations under the Note Documents purported to be sold
hereby.

         5. Upon acceptance and recording by the Administrative Agent, if any,
as of the Effective Date, (a) the Assignee shall be a party to the Note Purchase
Agreement and, to the extent provided in this Assignment and Acceptance, have
the rights and obligations of a Purchaser thereunder and under the other Note
Documents and (b) the Assignor shall, to the extent provided in this Assignment
and Acceptance, relinquish its rights and be released from its obligations under
the Note Purchase Agreement and the other Note Documents.

         6. Upon such acceptance and recording, from and after the Effective
Date, the Administrative Agent shall make all payments under the Note Purchase
Agreement and the other Note Documents in respect of the interest assigned
hereby (including all payments of principal, interest and Fees) to the Assignee.
The Assignor and Assignee shall make all appropriate adjustments in payments
under the Note Purchase Agreement and the other Note Documents for periods prior
to the Effective Date directly between themselves.



                     Assignment and Acceptance (Nortel NPA)
                                       3
<PAGE>   120

         7. THIS ASSIGNMENT AND ACCEPTANCE SHALL BE GOVERNED BY, AND CONSTRUED
IN ACCORDANCE WITH, THE LAWS OF NEW YORK.

                                       [NAME OF ASSIGNOR]


                                       By:
                                          --------------------------------------
                                       Name:
                                            ------------------------------------
                                       Title:
                                             -----------------------------------
                                       After the Effective Date:
                                                                ----------------
                                         Commitment:  $
                                                       -------------------------
                                         Aggregate Principal Amount of
                                          Notes Outstanding:  $
                                                               -----------------

                                       [NAME OF ASSIGNEE]


                                       By:
                                          --------------------------------------
                                       Name:
                                            ------------------------------------
                                       Title:
                                             -----------------------------------
                                       Notice Address:
                                                     ---------------------------
                                       After the Effective Date:
                                                                ----------------
                                         Commitment:  $
                                                       -------------------------
                                         Aggregate Principal Amount of
                                          Notes Outstanding:  $
                                                               -----------------

Accepted this _______ day of
_________________, ____

ABN AMRO BANK N.V., AS ADMINISTRATIVE AGENT

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

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



                     Assignment and Acceptance (Nortel NPA)
                                       4
<PAGE>   121
                                                                     EXHIBIT G-2
                                                                      [RECOURSE]


                                     FORM OF
                            ASSIGNMENT AND ACCEPTANCE

                    Dated as of __________________, 1999/200_


     Reference is hereby made to the Secured Note Purchase Agreement, dated as
of December ___, 1999, (as the same may be amended, supplemented, replaced,
renewed or otherwise modified from time to time, the "Note Purchase Agreement")
by and among VESPER S.A., a sociedade anonima organized under the laws of Brazil
(the "Company"), NORTEL NETWORKS CORPORATION ("Nortel"), as initial Purchaser,
the banks and other entities that either now or in the future are parties
thereto as Purchasers, ABN AMRO BANK N.V. ("ABN AMRO"), as Administrative Agent
and bookrunner for the Purchasers (in such capacity, ABN AMRO or any successor
in such capacity is referred to herein as the "Administrative Agent"), and
NORTEL, individually. The Purchasers (including Nortel, to the extent provided
in the Note Purchase Agreement), the Administrative Agent, LASALLE BANK NATIONAL
ASSOCIATION, as Collateral Agent under the Common Terms Agreement referred to
below (in such capacity, together with any successor in such capacity, the
"Collateral Agent") are collectively referred to herein as the "Purchaser
Parties" and each individually as a "Purchaser Party". [***]

     Terms with initial capital letters used but not defined herein have the
meanings assigned to them by the Note Purchase Agreement.


     ___________________ (the "Assignor") and ___________________ (the
"Assignee") agree as follows:

     1. Subject to Section 3 below, the Assignor hereby sells and assigns to the
Assignee, and the Assignee hereby purchases and assumes from the Assignor,
WITHOUT RECOURSE to Assignor [***] a __________% interest in and to all of the
Assignor's rights and obligations under the [***], the Note Purchase Agreement
and the other Note Documents as of the Effective Date (as defined below),
including, without limitation, such percentage interest in the Assignor's
Commitment as is in effect on the Effective Date, the amounts outstanding under
the Notes owing to the Assignor on the Effective Date, and the Notes held by or
for the Assignor on the Effective Date.

     2. The Assignor (a) represents and warrants that, as of the date hereof,
its Commitment (without giving effect to assignments thereof which have not yet
become effective) is $_____________ and Assignor agrees that its Commitment
shall not change during the period from the date hereof to and including the
Effective Date other than as a result hereof;

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.



                       Recourse Assignment and Acceptance
                                        1
<PAGE>   122


(b) represents and warrants that it is the legal and beneficial owner of the
interest being assigned by it hereunder and that such interest is free and clear
of any adverse claim; (c) makes no representation or warranty and assumes no
responsibility with respect to the existence, priority or value of any Lien on
any Collateral, any statements, warranties or representations made in or in
connection with the Note Purchase Agreement or any of the other Note Documents
or the execution, legality, validity, enforceability, genuineness, sufficiency
or value of the [***] Note Purchase Agreement or any of the other Note Documents
or any other instrument or document furnished pursuant thereto; (d) makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of any of the Company Parties or [***] the performance or
observance of any of their respective obligations under the Note Documents [***]
or any other instrument or document furnished pursuant thereto, and (e) requests
that the Administrative Agent exchange the Notes referred to in paragraph 1
above on the Effective Date for new Notes as follows: a Note, in the principal
face amount of $________________, payable to the Assignor or its registered
assigns, and a Note, in the principal face amount of $__________________ payable
to the Assignee or its registered assigns [and a Note, in the principal face
amount of $________________, payable to the Assignor or its registered assigns,
and a Note, in the principal face amount of $_________________ payable to the
Assignee or its registered assigns] [if possible under the circumstances: and
(f) represents and warrants that the Interest Period applicable to each
Euro-Dollar Rate Note outstanding as of the Effective Date, if any, ends on the
Effective Date].

     3. The Assignee (a) confirms that it has received a copy of the [***] Note
Purchase Agreement and the other Note Documents (other than the Administrative
Agent's Letter), the Paying Agency Agreement, and the Addendum to Assignment and
Acceptance (described below), together with copies of the financial statements
referred to in [***] Section 4.1 of the Common Terms Agreement or delivered
pursuant to Section 2.1 thereof, prior to the date hereof and such other
documents and information as it has deemed appropriate to make its own credit
analysis and decision to enter into this Assignment and Acceptance; (b) agrees
that it will, independently and without reliance upon the Administrative Agent
or the Collateral Agent or any other Purchaser Party, and based on such
documents and information as it shall deem appropriate at the time, continue to
make its own credit decisions in taking or not taking action under the [***]
Note Purchase Agreement or the other Note Documents; (c) appoints and authorizes
the Administrative Agent and Collateral Agent to take such actions on its behalf
and to exercise such powers under the [***] Note Documents as are respectively
delegated to the Administrative Agent and Collateral Agent by the terms thereof,
together with such powers as are reasonably incidental thereto; (d) agrees that
it will perform in accordance with their terms all of the obligations which by
the terms hereof and of the Note Purchase Agreement or the other Note Documents
are required to be performed by it as a Purchaser; (e) specifies as its address
for notices the office set forth beneath its name on the signature pages hereof;
and (f) attaches and otherwise agrees to provide hereafter to Company, Paying
Agent, Administrative Agent, and Collateral Agent a properly completed and
executed Internal Revenue Service Form 4224 or 1001 or other applicable form,
certificate or document prescribed by the Internal Revenue Service of the United
States (to the extent applicable as determined in the reasonable judgment of
Assignee) or by the appropriate taxing authority of any

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.



                       Recourse Assignment and Acceptance
                                       2
<PAGE>   123


other relevant jurisdiction (as any such form, certificate or document of such
other relevant jurisdiction has been specified to Assignee by the Company under
Section 2.12(c) of the Note Purchase Agreement) certifying as to the Assignee's
entitlement to an exemption from withholding tax or reduced rate of withholding
tax with respect to all payments under the [***], Note Purchase Agreement, and
the other Note Documents.

     4. Following the execution of this Assignment and Acceptance it will be
delivered to the Administrative Agent for acceptance and recording by the
Administrative Agent, if the Administrative Agent accepts such Assignment and
Acceptance in its discretion. The effective date of this Assignment and
Acceptance shall be ____________________ or the date on which the Administrative
Agent accepts this Assignment and Acceptance in its discretion, whichever is
later (the "Effective Date"). If the Administrative Agent shall fail to accept
and record this Assignment and Acceptance prior to the expiration of 10 days
after the date hereof, this Assignment and Acceptance shall be without force and
effect for any purpose, and the Assignor shall remain the owner of the interest
in the Assignor's rights and obligations under the Note Documents otherwise
purported to be sold hereby.

     5. [***]

     6. Upon acceptance and recording by the Administrative Agent, if any, as of
the Effective Date, (a) the Assignee shall be a party to the Note Purchase
Agreement and, to the extent provided in this Assignment and Acceptance, have
the rights and obligations of a Purchaser thereunder and under the other Note
Documents [***] and the Addendum, and (b) the Assignor shall, to the extent
provided in this Assignment and Acceptance, relinquish its rights and be
released from its obligations under the Note Purchase Agreement and the other
Note Documents [***] and the Addendum.

     7. Upon such acceptance and recording, from and after the Effective Date,
the Administrative Agent shall make all payments under the Note Purchase
Agreement and the other Note Documents in respect of the interest assigned
hereby (including all payments of principal, interest and Fees, but excluding
[***] to the Assignee. The Assignor and Assignee shall make all appropriate
adjustments in payments under the Note Purchase Agreement and the other Note
Documents for periods prior to the Effective Date directly between themselves.

     8. Delivery of an executed signature page hereof by telecopy transmission
from one party hereto to another shall constitute effective and binding
execution and delivery hereof by such party. This Assignment and Acceptance may
be executed by the parties hereto on any

[*] Certain material (indicated by an asterisk) has been omitted from this
document pursuant to a request for confidential treatment. The omitted material
has been filed separately with the Securities and Exchange Commission.



                       Recourse Assignment and Acceptance
                                       3
<PAGE>   124


number of separate counterparts, each of which, when so executed and delivered,
shall be an original, and all such counterparts shall together constitute one
and the same instrument.


           [THIS ASSIGNMENT AND ACCEPTANCE CONTINUES ON THE NEXT PAGE]



                       Recourse Assignment and Acceptance
                                       4
<PAGE>   125


              [SIGNATURE PAGE 1 OF 4 OF ASSIGNMENT AND ACCEPTANCE]


     THIS ASSIGNMENT AND ACCEPTANCE SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK (OTHER THAN CHOICE OF LAW
RULES THAT WOULD REQUIRE THE APPLICATION OF THE LAWS OF ANY OTHER JURISDICTION).




NORTEL NETWORKS CORPORATION,
AS ASSIGNOR AND, INDIVIDUALLY, CONSENTING AND
AGREEING TO THE FOREGOING


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

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

Notice Address:
8200 Dixie Road, Suite 100
Brampton, Ontario L6T 5P6
Canada

After the Effective Date:
Commitment: $0.00



                       Recourse Assignment and Acceptance
                                       5
<PAGE>   126


              [SIGNATURE PAGE 2 OF 4 OF ASSIGNMENT AND ACCEPTANCE]



[NAME OF ASSIGNEE]



By:
   -----------------------------
Name:
Title:
Notice Address
After the Effective Date:

Commitment: $



                       Recourse Assignment and Acceptance
                                        6
<PAGE>   127


              [SIGNATURE PAGE 3 OF 4 OF ASSIGNMENT AND ACCEPTANCE]


Accepted as of this ______ day of
_______________, 1999:

ABN AMRO BANK N.V.,
AS ADMINISTRATIVE AGENT


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

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



                       Recourse Assignment and Acceptance
                                        7
<PAGE>   128


              [SIGNATURE PAGE 4 OF 4 OF ASSIGNMENT AND ACCEPTANCE]

Consented to, as of this _______ day of _________________, 1999/200__:

VESPER S.A.

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



                       Recourse Assignment and Acceptance
                                        8