Document:

<PAGE>   1
                                                                     EXHIBIT 4.1

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                                 METRICOM, INC.
                             METRICOM FINANCE, INC.

                                     ISSUERS

                                 METRICOM, INC.

                                    GUARANTOR

                          FIRST SUPPLEMENTAL INDENTURE

                                   RELATING TO

                            13% SENIOR NOTES DUE 2010

                          DATED AS OF FEBRUARY 7, 2000

                          BANK ONE TRUST COMPANY, N.A.

                                     TRUSTEE

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<PAGE>   2
                               TABLE OF CONTENTS

<TABLE>
                                                                                                     PAGE
                                                                                                     ----
<S>                                                                                                  <C>
ARTICLE 1  DEFINITIONS AND INCORPORATION BY REFERENCE...............................................    2

         Section 1.01.     Relation to Indenture....................................................    2

         Section 1.02.     Definitions..............................................................    2

         Section 1.03.     Other Definitions........................................................   20

ARTICLE 2  THE SERIES OF NOTES......................................................................   21

         Section 2.01.     Title of the Securities..................................................   21

         Section 2.02.     Limitation on Aggregate Principal Amount and Additional Notes............   21

         Section 2.03.     Interest and Interest Rate; Maturity Date of Notes.......................   21

         Section 2.04.     Form.....................................................................   22

         Section 2.05.     Other Debt Securities....................................................   23

         Section 2.06.     Warrants.................................................................   23

ARTICLE 3  REDEMPTION AND PREPAYMENT................................................................   24

         Section 3.01.     Optional Redemption......................................................   24

         Section 3.02.     Repurchase at the Option of Holders......................................   25

ARTICLE 4  COVENANTS ...............................................................................   27

         Section 4.01.     Reports..................................................................   27

         Section 4.02.     Release of Obligations Following Holding Company Reorganization..........   28

         Section 4.03.     Limitation on Restricted Payments........................................   28

         Section 4.04.     Limitation on Incurrence of Indebtedness and Issuance of Preferred
                           Stock....................................................................   31

         Section 4.05.     Limitation on Liens......................................................   31

         Section 4.06.     Limitation on Dividend and Other Payment Restrictions Affecting
                           Restricted Subsidiaries..................................................   32

         Section 4.07.     Limitation on Sale of Assets.............................................   33

         Section 4.08.     Limitation on Transactions with Affiliates...............................   34

         Section 4.09.     Limitation on Sale and Leaseback Transactions............................   36
</TABLE>

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<TABLE>
<S>                                                                                                   <C>
         Section 4.10.     Limitation on Issuance of Guarantees of Indebtedness by
                              Restricted Subsidiaries .............................................    36

         Section 4.11.     Limitation on Business Activities........................................   37

         Section 4.12.     Limitation on Issuance and Sale of Equity Interests of Restricted
                              Subsidiaries .........................................................   37

         Section 4.13.     Designation of Restricted and Unrestricted Subsidiaries..................   38

         Section 4.14.     Change of Control........................................................   39

ARTICLE 5  SUCCESSORS ..............................................................................   40

         Section 5.01.     Merger, Consolidation, or Sale of Assets.................................   40

         Section 5.02.     Successor Corporation Substituted........................................   41

         Section 5.03.     Additional Amounts.......................................................   41

ARTICLE 6  DEFAULTS AND REMEDIES....................................................................   43

         Section 6.01.     Events of Default........................................................   43

         Section 6.02.     Acceleration.............................................................   45

ARTICLE 7  INTEREST RESERVE.........................................................................   46

         Section 7.01.     Interest Reserve; Security...............................................   46

         Section 7.02.     Recording and Opinions...................................................   47

         Section 7.03.     Release of the Pledged Securities........................................   48

         Section 7.04.     Certificates of the Issuers..............................................   49

         Section 7.05.     Certificates of the Trustee..............................................   49

         Section 7.06.     Authorization of Actions to Be Taken by the Trustee Under the
                             Pledge Agreement ......................................................   49

         Section 7.07.     Trustee's Duties.........................................................   50

         Section 7.08.     Authorization of Receipt of Funds by the Trustee Under the
                             Pledge Agreement ......................................................   50

         Section 7.09.     Termination of Security Interest.........................................   51

         Section 7.10.     Cooperation of Trustee...................................................   51

         Section 7.11.     Collateral Agent.........................................................   51

ARTICLE 8  NOTE GUARANTEES..........................................................................   52

         Section 8.01.     Subsidiary Guarantees....................................................   52

         Section 8.02.     Additional Guarantees....................................................   54

         Section 8.03.     Limitation on Guarantor Liability........................................   54
</TABLE>

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<TABLE>
<S>                                                                                                   <C>
         Section 8.04.     Legal Defeasance or Covenant Defeasance..................................   54

         Section 8.05.     Merger and Consolidation of Guarantors...................................   56

         Section 8.06.     Release..................................................................   56

ARTICLE 9  LEGAL DEFEASANCE AND COVENANT DEFEASANCE

ARTICLE 10  MISCELLANEOUS...........................................................................   57

         Section 10.01.    Ratification of Indenture................................................   57

         Section 10.02.    Governing Law............................................................   57

         Section 10.03.    Counterpart Originals....................................................   57
</TABLE>

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<PAGE>   5
                             CROSS-REFERENCE TABLE*

                               TRUST INDENTURE ACT

<TABLE>
<CAPTION>
SECTION                                                                                    INDENTURE
-------                                                                                    ---------
<S>                                                                                        <C>
310(a)(1)...................................................................................   7.10

(a)(2) .....................................................................................   7.10

(a)(3)......................................................................................   N.A.

(a)(4)......................................................................................   N.A.

(a)(5)......................................................................................   7.10

(i)(b)......................................................................................   7.10

(ii)(c).....................................................................................   N.A.

311(a)......................................................................................   7.11

(b).........................................................................................   7.11

(iii)(c)....................................................................................   N.A.

312(a)......................................................................................   2.06

(b).........................................................................................  10.03

(iv)(c).....................................................................................  10.03

313(a)......................................................................................   7.06

(b)(2)......................................................................................   7.07

(v)(c)......................................................................................   7.06;
                                                                                              10.02

(vi)(d).....................................................................................   7.06

314(a)......................................................................................   4.03;

                                                                                               4.04(a);
</TABLE>

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<TABLE>
<S>                                                                                        <C>
                                                                                               10.02

(c)(1)......................................................................................   10.04

(c)(2)......................................................................................   10.04

(c)(3)......................................................................................    N.A.

(vii)(e)....................................................................................   10.05

(f)NA315(a).................................................................................    7.01

(b).........................................................................................    7.05,
                                                                                               10.02

(A)(c)......................................................................................    7.01

(d).........................................................................................    7.01

(e).........................................................................................    6.11

316(a)(last sentence).......................................................................    2.10

(a)(1)(A)...................................................................................    6.05

(a)(1)(B)...................................................................................    6.04

(a)(2)......................................................................................    N.A.

(b).........................................................................................    6.07

(B)(c)......................................................................................    2.12

317(a)(1)...................................................................................    6.08

(a)(2)......................................................................................    6.09

(b).........................................................................................    2.05

318(a)......................................................................................   10.01

(b).........................................................................................    N.A.

(c).........................................................................................   10.01
</TABLE>

                                       v
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N.A. means not applicable.

* This cross-reference Table is not part of the Indenture.

                                       vi
<PAGE>   8

            FIRST SUPPLEMENTAL INDENTURE, dated as of February 7, 2000 (this
"First Supplemental Indenture"), to that certain Senior Indenture dated as of
December 29, 1999 (the "Indenture"), between Metricom, Inc., a Delaware
corporation (the "Company"), Metricom Finance, Inc., a Delaware corporation
("Finance Sub," and together with the Company, the "Issuers" and each an
"Issuer," provided, however, that subsequent to a Holding Company
Reorganization, as defined below, such terms shall refer only to the holding
company resulting from the consummation of such Holding Company Reorganization)
and Bank One Trust Company, N.A., a national banking association, as trustee
(the "Trustee").

            The Issuers and the Trustee have heretofore executed the Indenture,
which has been filed with the Securities and Exchange Commission under the
Securities Act of 1933, as amended, as Exhibit 4.4 to the Company's Registration
Statement on Form S-3 (Registration No. 333-91359), providing for the issuance
from time to time of unsecured and unsubordinated debt securities of the
Issuers.

            The Company, Bank One Trust Company, N.A., as the initial warrant
agent (the "Initial Warrant Agent"), and EquiServe LP, as warrant agent (the
"Warrant Agent") have heretofore executed that certain Warrant Agreement dated
as of February 7, 2000 (the "Warrant Agreement"), providing for the issuance
from time to time of warrants (the "Warrants") to acquire an aggregate of
1,425,000 shares of the Company's Common Stock (as defined herein) and for the
issuance of such shares of the Company's Common Stock underlying such Warrants.

            The Issuers and the Trustee are hereby supplementing the Indenture
pursuant to the provisions of Section 9.01 of the Indenture to establish the
form and terms of the debt securities issued pursuant to this First Supplemental
Indenture.

            The Board of Directors of each Issuer has duly adopted resolutions
authorizing such Issuer to execute and deliver this First Supplemental Indenture
providing for the issuance and sale of the Notes and the Warrant Agreement
providing for the concurrent issuance of the Warrants.

            All the conditions and requirements necessary to make this First
Supplemental Indenture, when duly executed and delivered, a valid and binding
agreement in accordance with its terms and for the purposes herein expressed,
have been performed and fulfilled.

            The Issuers and the Trustee agree as follows for the benefit of each
other and for the equal and ratable benefit of the holders of the Notes (the
"Holders"), as follows:

<PAGE>   9
                                    ARTICLE 1
                   DEFINITIONS AND INCORPORATION BY REFERENCE

            SECTION 1.01. RELATION TO INDENTURE. This First Supplemental
Indenture constitutes an integral part of the Indenture. To the extent there are
inconsistent provisions between this First Supplemental Indenture and the
Indenture, the provisions of this First Supplemental Indenture shall govern.

            SECTION 1.02. DEFINITIONS. For all purposes of this First
Supplemental Indenture, except as otherwise expressly provided for or unless the
context otherwise requires:

            (a) Capitalized terms used but not defined herein shall have the
      respective meanings assigned to them in the Indenture; and

            (b) All references herein to Articles and Sections, unless otherwise
      specified, refer to the corresponding Articles and Sections of this First
      Supplemental Indenture.

            (c) The following terms have the indicated meaning for purposes of
      this First Supplemental Indenture:

            "Acquired Debt" means, with respect to any specified Person, (1)
Indebtedness of any other Person existing at the time the other Person is merged
with or into or became a Restricted Subsidiary of the specified Person,
including, without limitation, Indebtedness Incurred in connection with, or in
contemplation of, the other Person merging with or into or becoming a Restricted
Subsidiary of the specified Person, and (2) Indebtedness secured by a Lien
encumbering any asset acquired by the specified Person.

            "Affiliate" means, as applied to any Person, any other Person
directly or indirectly controlling, controlled by, or under direct or indirect
common control with, such Person. For purposes of this definition, "control" and
correlative meanings, the terms "controlling," "controlled by" and "under common
control with," as applied to any Person, means the possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of such Person, whether through the ownership of voting securities, by
contract or otherwise.

            "Annualized Consolidated Cash Flow" means, with respect to any
Person, that Person's Consolidated Cash Flow for the Reference Period multiplied
by two.

            "Asset Acquisition" means (1) an Investment by an Issuer or any
Restricted Subsidiary of an Issuer in any other Person pursuant to which that
Person becomes a Restricted Subsidiary of the Issuers or merges into or
consolidates with an Issuer or any of the Issuers' Restricted Subsidiaries,
provided that that Person's primary

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business is a Communications and Data Access Business, or (2) an acquisition by
an Issuer or any Restricted Subsidiary of an Issuer of the property and assets
of any Person other than an Issuer or any of their Restricted Subsidiaries that
constitute all or substantially all of the assets of that Person or a division
or line of business of that Person, provided that the property and assets
acquired are assets used in a Communications and Data Access Business.

            "Asset Disposition" means the sale or other disposition by an Issuer
or any Restricted Subsidiary of an Issuer, other than to an Issuer or any of
their Restricted Subsidiaries, of (1) all or a significant amount of the Capital
Stock of any Restricted Subsidiary of an Issuer, or (2) all or substantially all
of the assets that constitute a division or line of business of an Issuer or a
division or line of business of any Restricted Subsidiary of an Issuer.

            "Asset Sale" means (1) the sale, lease, conveyance or other
disposition of any assets or properties, including, without limitation, by way
of a consolidation, merger or sale and leaseback, other than in the ordinary
course of business; provided, however, that the sale, lease, conveyance or other
disposition of all or substantially all of the assets of the Issuers and the
assets of their Restricted Subsidiaries taken as a whole shall be governed by
Section 4.14 and Section 5.01 hereof and not by the provisions of Section 4.07
hereof, and (2) the issue or sale by the Issuers or any of their Restricted
Subsidiaries of Equity Interests of any Restricted Subsidiary of an Issuer, in
the case of either clause (1) or (2), whether in a single transaction or a
series of related transactions (a) that have a fair market value in excess of
$2.0 million or (b) for Net Proceeds in excess of $2.0 million.

            Notwithstanding the foregoing, none of the following shall be deemed
to be an Asset Sale: (I) a transfer of assets by an Issuer to a Restricted
Subsidiary of an Issuer or by such a Restricted Subsidiary to an Issuer or to
another Restricted Subsidiary of an Issuer; (II) an issuance or sale of Equity
Interests by a Restricted Subsidiary of an Issuer to an Issuer or to another
Restricted Subsidiary of an Issuer; (III) a Permitted Investment or a Restricted
Payment that is permitted by Section 4.03 hereof; (IV) issuances of Equity
Interests, other than in respect of Disqualified Stock, of a Restricted
Subsidiary pursuant to an employee stock option plan providing for customary and
reasonable stock-based compensation; (V) a transfer constituting the granting of
a Permitted Lien; and (VI) sales or other dispositions of property or equipment
determined by the management of that Issuer in good faith to be worn out,
obsolete or damaged.

            "Attributable Debt" in respect of a Sale and Leaseback Transaction
means, at the time of determination, the present value, discounted at the rate
of interest implicit in the transaction, determined in accordance with GAAP, of
the obligation of the lessee for net rental payments during the remaining term
of the lease included in such Sale and Leaseback Transaction, including any
period for which the lease has been extended or may, at the option of the
lessor, be extended.

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            "Bankruptcy Law" means Title 11, U.S. Code or any similar federal or
state law for the relief of debtors.

            "Capital Lease Obligation" means, at the time any determination
thereof is to be made, the amount of the obligation to pay rent or other payment
amount in respect of a lease that would at such time be required to be
classified and accounted for as a capital lease on a balance sheet prepared in
accordance with GAAP.

            "Capital Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents, however designated,
whether voting or non-voting, in equity of such Person, whether now outstanding
or issued after the date hereof, including, without limitation, all Common Stock
and Preferred Stock.

            "Cash Equivalents" means (1) United States dollars; (2) securities
issued or directly and fully guaranteed or insured by the United States
government or any agency or instrumentality thereof having maturities of not
more than one year from the date of acquisition; (3) certificates of deposit and
eurodollar time deposits with maturities of not more than one year from the date
of acquisition, bankers' acceptances with maturities of not more than one year
from the date of acquisition and overnight bank deposits, in each case with any
domestic commercial bank having capital and surplus in excess of $500 million
and a Thompson Bank Watch Rating of "B" or better; (4) repurchase obligations
with a term of not more than seven days for underlying securities of the types
described in clauses (2) and (3) above entered into with any financial
institution meeting the qualifications specified in clause (3) above; (5)
commercial paper rated at least P-1 by Moody's Investors Service, Inc. or at
least A-1 by Standard & Poor's with maturities of not more than one year from
the date of acquisition; or (6) money market or mutual funds at least 95% of the
assets of which are invested in investments of the types specified in clauses
(1) through (5) above.

            "Change of Control" means such time as (1) a "person" or "group,"
within the meaning of Sections 13(d) and 14(d)(2) of the Exchange Act, other
than a Permitted Holder, becomes the ultimate "beneficial owner," as defined in
Rule 13d-3 under the Exchange Act, of more than 50% of the total voting power of
the then outstanding Voting Stock of either Issuer on a fully diluted basis; (2)
individuals who at the beginning of any period of two consecutive calendar years
constituted the Board of Directors of either Issuer, together with any directors
who are members of such Board of Directors on the date hereof and any new
directors whose election by the Board of Directors or whose nomination for
election by the stockholders of such Issuer was approved by a vote of at least
two-thirds of the members of the Board of Directors then still in office who
either were members of the Board of Directors at the beginning of such period or
whose election or nomination for election was previously so approved, cease for
any reason to constitute a majority of the members of such Board of Directors
then in office; (3) the sale, lease, transfer, conveyance or other disposition,
other than by way of merger or consolidation, in one or a series of related
transactions, of all or substantially all of the assets of the Issuers and their
Subsidiaries taken as a whole to any such "person" or

                                       4
<PAGE>   12
"group," other than to a Permitted Holder or a Restricted Subsidiary of an
Issuer; (4) the merger or consolidation of an Issuer with or into another
corporation or the merger of another corporation with or into an Issuer with the
effect that immediately after such transaction any such "person" or "group" of
persons or entities, other than a Permitted Holder, shall have become the
ultimate beneficial owner of securities of the surviving corporation of such
merger or consolidation representing more than 50% of the total voting power of
the then outstanding Voting Stock of the surviving corporation; or (5) the
approval by the holders of the Capital Stock of an Issuer of a plan relating to
the liquidation or dissolution of such Issuer.

            In no event shall the consummation of a Holding Company
Reorganization constitute a Change of Control and, prior to a Holding Company
Reorganization, this definition shall not apply to Finance Sub.

            "Common Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents, however designated,
whether voting or non-voting, of that Person's equity, other than Preferred
Stock of that Person, whether now outstanding or issued after the date the Notes
are issued, including without limitation, all series and classes of that equity.

            "Communications and Data Access Business" means a business primarily
involved in the ownership, design, development, construction, acquisition,
installation, integration, management and/or provision of telecommunications
equipment, inventory, systems, content and/or services, including, without
limitation, mobile or landline Internet, mobile telephone, PCS, microwave or
paging or data transmission, or businesses reasonably related thereto as
determined in good faith by the Board of Directors of each Issuer.

            "Consolidated Cash Flow" means, with respect to any Person for any
period, the Consolidated Net Income of that Person for that period plus: (1) an
amount equal to any extraordinary loss plus any net loss realized in connection
with an Asset Sale, to the extent such losses were deducted in computing such
Consolidated Net Income, plus (2) provision for taxes based on income or profits
of that Person and its Restricted Subsidiaries for that period, to the extent
that the provision for taxes was deducted in computing Consolidated Net Income,
plus (3) the Consolidated Interest Expense of that Person and its Restricted
Subsidiaries for that Period, to the extent such interest expense was deducted
in computing Consolidated Net Income, plus (4) depreciation and amortization,
including amortization of goodwill and other intangibles but excluding
amortization of prepaid cash expenses that were paid in a prior period, of that
Person and its Restricted Subsidiaries for that period to the extent that such
depreciation and amortization were deducted in computing such Consolidated Net
Income, plus (5) all other non-cash items reducing Consolidated Net Income,
other than items that will require cash payments and for which an accrual or
reserve is, or is required by GAAP to be, made, minus (6) non-cash items
increasing Consolidated Net

                                       5
<PAGE>   13
Income for that period, other than items that were accrued in the ordinary
course of business, in each case, on a consolidated basis and determined in
accordance with GAAP.

            Notwithstanding the foregoing, the provision for taxes on the income
or profits of, and the depreciation and amortization and other non-cash charges
of, any Restricted Subsidiary of an Issuer shall be added to Consolidated Net
Income to compute the Consolidated Cash Flow only to the extent, and in same
proportion, that the Net Income of such Restricted Subsidiary was included in
calculating the Consolidated Net Income of that Issuer.

            "Consolidated Fixed Charges" means, with respect to any Person for
any period, the sum, without duplication, of (1) the Consolidated Interest
Expense of that Person and its Restricted Subsidiaries for that period, plus (2)
any interest expense on Indebtedness of another Person that is Guaranteed by
that Person or one of its Restricted Subsidiaries or secured by a Lien on assets
of such Person or one of its Restricted Subsidiaries, whether or not such
Guarantee or Lien is called upon, plus (3) the product of (a) all dividend
payments, whether or not in cash, on any series of Preferred Stock of such
Person or any of its Restricted Subsidiaries, other than dividend payments on
Equity Interests payable solely in Equity Interests of an Issuer, other than
Disqualified Stock, times (b) a fraction, the numerator of which is one and the
denominator of which is one minus the then effective combined federal, state and
local statutory tax rate of such Person, expressed as a decimal, in each case,
on a consolidated basis and in accordance with GAAP.

            "Consolidated Interest Expense" means, with respect to any Person,
that Person's consolidated interest expense, whether paid or accrued and whether
or not capitalized, including, without limitation, amortization of debt issuance
costs and original issue discount, non-cash interest payments, the interest
component of any deferred payment obligations, the interest component of all
payments associated with Capital Lease Obligations, commissions, discounts and
other fees and charges Incurred in respect of letter of credit or bankers'
acceptance financing, and net payments, if any, pursuant to Hedging Obligations,
to the extent that any such expense was deducted in computing the Consolidated
Net Income of that Person.

            "Consolidated Leverage Ratio" means, on any date of determination,
the ratio of: (1) the aggregate amount of the Indebtedness of the Issuers and
their Restricted Subsidiaries on a consolidated basis as of the end of the most
recent fiscal quarter for which financial statements for the Issuers have become
publicly available prior to that date, to (2) the aggregate amount of Annualized
Consolidated Cash Flow.

            In making the foregoing calculation, (a) Indebtedness shall be
calculated after giving pro forma effect to: (I) any Indebtedness, including, if
applicable, the Notes, Incurred subsequent to the end of the Reference Period
and on or prior to the date of determination, in each case as if such
Indebtedness had been Incurred and the proceeds had been applied on the last day
of that Reference Period for purposes of clause (1)

                                       6
<PAGE>   14
above, and on the first day of the Reference Period for purposes of clause (2)
above, and (II) any Indebtedness that was outstanding during or after the
Reference Period but that is not outstanding or is to be repaid on the date of
determination, in each case as if such Indebtedness was repaid on the last day
of such Reference Period for purposes of clause (1) above, and on the first day
of the Reference Period for purposes of clause (2) above; (b) pro forma effect
shall be given to Asset Dispositions and Asset Acquisitions, including giving
pro forma effect to the application of proceeds of any Asset Disposition, that
occurred during or after the Reference Period and on or prior to the
determination date as if they had occurred and such proceeds had been applied on
the first day of the Reference Period; and (c) pro forma effect shall be given
to asset dispositions and asset acquisitions, including giving pro forma effect
to the application of proceeds of any asset disposition, that have been made by
any Person that has become a Restricted Subsidiary or has been merged with or
into an Issuer or any Restricted Subsidiary during or after the Reference Period
and on or prior to the determination date and that would have constituted Asset
Dispositions or Asset Acquisitions had such transactions occurred when that
Person was a Restricted Subsidiary as if those asset dispositions or asset
acquisitions were Asset Dispositions or Asset Acquisitions that occurred on the
first day of the Reference Period.

            "Consolidated Net Income" means, with respect to any Person for any
period, the aggregate of the Net Income of such Person and its Restricted
Subsidiaries, for such period, on a consolidated basis determined in accordance
with GAAP; provided, however, that (1) the Net Income, but not loss, of any
Person that is not a Restricted Subsidiary or that is accounted for by the
equity method of accounting shall be included only to the extent of the amount
of dividends or distributions paid in cash to the referent Person or a
Restricted Subsidiary; (2) the Net Income of any Restricted Subsidiary shall be
excluded to the extent that the declaration or payment of dividends or similar
distributions by that Restricted Subsidiary of that Net Income is not at the
date of determination permitted without any prior governmental approval, that
has not been obtained, or, directly or indirectly, by operation of the terms of
its charter or any agreement, instrument, judgment, decree, order, statute, rule
or governmental regulation applicable to that Restricted Subsidiary or its
stockholders, except in the case of any restriction or encumbrance permitted
under clause (a) of Section 4.06 hereof; (3) the Net Income of any Person
acquired in a pooling of interests transaction for any period prior to the date
of such acquisition shall be excluded for purposes of computing the amount of
Restricted Payments that the Issuers or their Restricted Subsidiaries may make;
and (4) the cumulative effect of a change in accounting principles shall be
excluded.

            "Consolidated Net Worth" means, with respect to any Person, the
consolidated stockholders' or partners' equity of that Person reflected on the
most recent financial statements of that Person, determined in accordance with
GAAP, less any amounts attributable to redeemable Capital Stock of that Person
otherwise included in the consolidated stockholders' or partners' equity of that
Person.

                                       7
<PAGE>   15
            "Credit Facilities" means one or more debt facilities or commercial
paper facilities with banks or other lenders providing for revolving credit
loans, letters of credit, term loans, equipment financing or receivables
financing, including through the sale of receivables to such lenders or to
special purpose entities formed to borrow from such lenders against such
receivables, in each case, as amended, restated, modified, renewed, refunded,
replaced, supplemented, extended or refinanced in whole or in part from time to
time, and whether involving the same or different agents, banks or lenders.

            "Default" means any event that is, or after notice or passage of
time or both would be, an Event of Default.

            "Disqualified Stock" means any Capital Stock that, by its terms or
by the terms of any security into which it is convertible or for which it is
exchangeable at the option of the holder of that security, or upon the happening
of any event (other than an optional call for redemption by the issuer of that
Capital Stock), matures or is mandatorily redeemable, pursuant to a sinking fund
obligation or otherwise, or redeemable at the option of the holder of that
security, in whole or in part, on or prior to the date on which the Notes
mature, except to the extent that the Capital Stock is solely redeemable with,
or solely exchangeable for, any Capital Stock of that Person that is not
Disqualified Stock; provided, however, that any Capital Stock that would not
constitute Disqualified Stock but for provisions of that Capital Stock giving
holders of that Capital Stock a right to require that Person to repurchase or
redeem that Capital Stock upon the occurrence of an "asset sale" or a "change of
control" occurring prior to the final maturity date of the applicable Notes
shall not constitute Disqualified Stock if the "asset sale" or "change of
control" provisions applicable to that Capital Stock are no more favorable to
the holders of that Capital Stock than the provisions contained in Section 4.07
and Section 4.14 hereof and the Capital Stock specifically provides that the
Person will not repurchase or redeem any such Capital Stock pursuant to those
"asset sales" or "change of control" provisions prior to the repurchase of any
Notes that are required to be repurchased pursuant to Section 4.07 and Section
4.14 hereof and at all times subject to Section 4.03 hereof; provided, further,
that if an Issuer issues any Capital Stock pursuant to any plan for the benefit
of its employees or of employees of its Restricted Subsidiaries, such Capital
Stock shall not constitute Disqualified Stock solely because it may be required
to be repurchased by such Issuer in order to satisfy applicable statutory or
regulatory obligations. Notwithstanding anything herein to the contrary, neither
the Series A1 Preferred Stock nor Series A2 Preferred Stock shall constitute
Disqualified Stock for any purpose of the Indenture or this First Supplemental
Indenture.

            "Equity Interests" means Capital Stock and all warrants, options or
other rights to acquire Capital Stock, but excluding any debt security that is
convertible into, or exchangeable for, Capital Stock.

            "ERISA" means the Employee Retirement Income Security Act of 1974
and regulations promulgated thereunder.

                                       8
<PAGE>   16
            "Escrow Agent" means Bank One Trust Company, N.A., as escrow agent
under the Pledge Agreement.

            "Exchange Act" means the Securities and Exchange Act of 1934, as
amended.

            "FCC" means the Federal Communications Commission and any successor
governmental entity thereto.

            "GAAP" means generally accepted accounting principles set forth in
the opinions and pronouncements of the Accounting Principles Board of the
American Institute of Certified Public Accountants, the statements and
pronouncements of the Financial Accounting Standards Board and such other
statements by such other entities as have been approved by a significant segment
of the accounting profession, which are applicable at the date of any
determination made under the Indenture or this First Supplemental Indenture.

            "Hedging Obligations" means, with respect to any Person, the net
payment obligations of that Person under (1) interest rate swap agreements,
interest rate cap agreements and interest rate collar agreements, and (2) other
agreements or arrangements in the ordinary course of business designed to
protect that Person against fluctuations in commodity prices, interest rates or
currency exchange rates, in any case, not entered into for speculative purposes.

            "Holding Company Reorganization" means a transaction or a series of
transactions resulting in the assets and operations of the Company being held
and operated by Finance Sub or its Restricted Subsidiaries; provided, however,
that a transaction or a series of transactions shall qualify as a "Holding
Company Reorganization" only if it does not result in adverse tax consequences
to the Holders or material adverse tax consequence to the Issuers, as determined
in good faith by each Issuer's Board of Directors by a resolution set forth in
an officers' certificate delivered to the Trustee, which resolution shall be
based on an opinion of independent tax counsel of national standing that there
will be no adverse tax consequences to the Holders or material adverse
consequences to the Issuers. A Holding Company Reorganization may be effected,
without limitation, through: (1) a transaction or series of transactions in
which the Company contributes all or substantially of its assets and liabilities
to Finance Sub which may at any time and from time to time transfer these assets
to its Restricted Subsidiaries, but retains its obligations under the Notes, or
(2) a transaction in which (A) a wholly owned subsidiary of Finance Sub formed
solely for the purpose of effecting the Holding Company Reorganization merges
with and into the Company, with the Company being the surviving entity and in
which Finance Sub becomes the sole holder of all of the issued and outstanding
Capital Stock of the surviving entity and all of the holders of the Capital
Stock of the Company become the holders of all of the issued and outstanding
shares of the Capital Stock of Finance Sub; or (B) the Company merges into a
newly-formed limited liability company the sole member of which is Finance Sub
as a result of

                                       9
<PAGE>   17
which Finance Sub becomes the sole owner of the limited liability company
successor of the Company, and all of the holders of the Capital Stock of the
Company, become the holders of all of the issued and outstanding shares of the
Capital Stock of Finance Sub.

            Following the completion of a Holding Company Reorganization, the
term "Issuers" will refer only to the holding company resulting from the
consummation of the Holding Company Reorganization.

            "Incur" means create, incur, issue, assume, guarantee or otherwise
become liable, directly or indirectly, contingently or otherwise, for any
Indebtedness. The term "Incurrence" when used as a noun shall have a correlative
meaning. The accretion of principal of a non-interest bearing or other discount
security shall not be deemed the Incurrence of Indebtedness.

            "Indebtedness" means, with respect to any Person, any indebtedness
of that Person, whether or not contingent, in respect of borrowed money or
evidenced by bonds, notes, debentures or similar instruments or letters of
credit, or reimbursement agreements in respect of letters of credit, or banker's
acceptances or representing Capital Lease Obligations, the balance deferred and
unpaid of the purchase price of any property or representing any Hedging
Obligations, except any such balance that constitutes an accrued expense or
trade payable, or all Disqualified Stock valued at the greater of its voluntary
or involuntary maximum fixed repurchase price plus accrued and unpaid dividends,
if and to the extent any of the foregoing indebtedness, other than letters of
credit and Hedging Obligations, would appear as a liability upon a balance sheet
of such Person prepared in accordance with GAAP, as well as all Indebtedness or
other liabilities of others secured by a Lien on any asset of that Person,
whether or not such Indebtedness is assumed by that Person, and, to the extent
not otherwise included, the guarantee by such Person of any Indebtedness or
other liabilities of others, whether or not contingent, and whether or not such
guarantee appears on the balance sheet of that Person. The amount of any
Indebtedness outstanding as of any date shall be: (1) the accreted value
thereof, in the case of any Indebtedness that does not require current payments
of interest, (2) the principal amount of Indebtedness, together with any
interest thereon that is more than 30 days past due, in the case of any other
Indebtedness, and (3) the face amount of any bankers acceptances, letters of
credit or similar instruments (but in the case of a letter of credit only to the
extent not secured by cash collateral for such obligation) and the maximum
amount of any guarantee provided in respect of other liabilities by such Person;
provided, however, that in each case, with respect to any Indebtedness of any
Person secured by a Lien on any asset of such Person and non-recourse to such
Person other than to the extent of the asset subject to such Lien, the amount of
such Indebtedness shall be the lesser of (A) the principal amount thereof and
(B) the fair market value of the asset subject to such Lien; provided that such
non-recourse Indebtedness does not have final stated maturity (and is not
otherwise required to be repaid, redeemed or repurchased) prior to the final
stated maturity of the Notes and such non-recourse Indebtedness is Subordinated
Debt.

                                       10
<PAGE>   18
            "Investment" means, with respect to any Person, all investments by
that Person in other Persons, including Affiliates, in the form of direct or
indirect loans, guarantees of Indebtedness or other obligations, advances of
assets or capital contributions, excluding commission, travel and entertainment,
moving, and similar advances to officers and employees made in the ordinary
course of business, purchases or other acquisitions for consideration of
Indebtedness, Equity Interests or other securities, together with all items that
are or would be classified as investments on a balance sheet prepared in
accordance with GAAP.

            "Issue Date" means the date that any Notes are issued under this
First Supplemental Indenture.

            "Lien" means, with respect to any asset, any mortgage, lien, pledge,
charge, security interest or encumbrance of any kind in respect of such asset,
whether or not filed, recorded or otherwise perfected under applicable law,
including any conditional sale or other title retention agreement, any lease in
the nature thereof, any option or other agreement to sell or give a security
interest in any asset and any filing of or agreement to give any financing
statement under the Uniform Commercial Code or equivalent statutes of any
jurisdiction.

            "Market Capitalization" of any Person means, as of any day of
determination, the average Closing Price of that Person's common stock over the
20 consecutive trading days immediately preceding that day. "Closing Price" on
any trading day with respect to the per share price of any shares of common
stock means the last reported sale price regular way or, in case no such
reported sale takes place on such day, the average of the reported closing bid
and asked prices regular way, in either case on the New York Stock Exchange or,
if the shares of common stock are not listed or admitted to trading on that
exchange, on the principal national securities exchange on which the shares are
listed or admitted to trading or, if not listed or admitted to trading on any
national securities exchange, on the National Association of Securities Dealers
Automated Quotations National Market System or, if the shares are not listed or
admitted to trading on any national securities exchange or quoted on such
automated quotation system but the issuer if a Foreign Issuer, as defined in
Rule 3b-4(b) under the Exchange Act, and the principal securities exchange on
which the shares are listed or admitted to trading is a Designated Offshore
Securities Market, as defined in Rule 902(a) under the Securities Act, the
average of the reported closing bid and asked prices regular way on that
principal exchange, or, if the shares are not listed or admitted to trading on
any national securities exchange or quoted on that automated quotation system
and the issuer and principal securities exchange do not meet such requirements,
the average of the closing bid and asked prices in the over-the-counter marked
as furnished by any New York Stock Exchange member firm that is selected from
time to time by the Issuers for that purpose and is reasonably acceptable to the
Trustee.

                                       11
<PAGE>   19
            "MCI WorldCom Reseller Agreement" means that certain Ricochet(2)
Reseller Agreement, dated as of June 20, 1999, between Metricom, Inc and MCI
Worldcom, Inc., as amended through the date the Notes are issued.

            "Net Income" means, with respect to any Person, the net income or
loss of that Person, determined in accordance with GAAP and before any reduction
in respect of preferred stock dividends, excluding, however, (1) any gain, but
not loss, together with any related provision for taxes on such gain, but not
loss, realized in connection with (a) any Asset Disposition, including, without
limitation, dispositions pursuant to Sale and Leaseback Transactions, or (b) the
disposition of any securities by that Person or any of its Restricted
Subsidiaries or the extinguishment of any Indebtedness of that Person or any of
its Restricted Subsidiaries, and (2) any extraordinary gain, but not loss,
together with any related provision for taxes on such extraordinary gain, but
not loss.

            "Net Proceeds" means the aggregate cash proceeds or Cash Equivalents
received by the Issuers or any of their Restricted Subsidiaries in respect of
any Asset Sale, including, without limitation, any cash received upon the sale
or other disposition of any non-cash consideration received in any Asset Sale,
net of all costs relating to such Asset Sale, including, without limitation,
legal, accounting, investment banking and brokers fees, and sales and
underwriting commissions, taxes paid or payable as a result of the Asset Sale,
after taking into account any available tax credits or deductions and any tax
sharing arrangements, and any reserve for adjustment in respect of the sale
price of such asset or assets established in accordance with GAAP.

            "Non-Recourse Debt" means Indebtedness: (1) as to which neither an
Issuer nor any of their Restricted Subsidiaries: (a) provides credit support of
any kind, including any undertaking, agreement or instrument that would
constitute Indebtedness; (b) is directly or indirectly liable, as a guarantor or
otherwise; or (c) constitutes the lender; (2) no default with respect to which,
including any rights that the holders of that Indebtedness may have to take
enforcement action against an Unrestricted Subsidiary, would permit upon notice,
lapse of time or both any holder of any other of Indebtedness of the Issuers,
other than the Notes, or of the Indebtedness of any Restricted Subsidiary of the
Issuers to declare a default on that other Indebtedness or cause the payment of
that other Indebtedness to be accelerated or payable prior to its Stated
Maturity; and (3) as to which the lenders have been notified in writing that
they will not have any recourse to the stock or assets of the Issuers or any of
their Restricted Subsidiaries.

            "Notes" shall have the meaning set forth in Section 2.01 hereof.

            "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.

            "Permitted Debt" means each and all of the following: (1)
Indebtedness under one or more Credit Facilities and related guarantees under
the Credit Facilities in

                                       12
<PAGE>   20
any aggregate principal amount not to exceed $275.0 million at any time
outstanding (exclusive of any amount incurred under any such Credit Facilities
pursuant to Section 4.04 hereof, including this definition of Permitted Debt),
less any permanent reductions as a result of the application of proceeds from an
Asset Sale to permanently reduce Indebtedness represented by the Credit
Facilities as provided under Section 4.07 hereof; (2) Indebtedness outstanding
on the date hereof; (3) Indebtedness represented by the Notes; provided that any
Additional Notes issued after the initial issuance of the Notes represent
Indebtedness that, but for this clause (3), could otherwise have been incurred
under Section 4.04 hereof; provided, further, that if any Additional Notes are
to be issued prior to February 15, 2002, we shall deposit in the Pledge Account
funds sufficient to pay, or to permit the purchase of additional Pledged
Securities sufficient to pay, when due, all cash interest payments accruing on
the Additional Notes on or prior to February 15, 2002; (4) Permitted Refinancing
Indebtedness, which will not include the refinancing, renewal, replacement,
defeasance or refunding of Indebtedness under clauses (1), (5) or (11) of this
definition; (5) Indebtedness: (a) in respect of performance, surety or appeal
bonds or letters of credit, in each case provided in the ordinary course of
business; (b) in respect of Hedging Obligations; provided that such agreements
do not increase the Indebtedness of the obligor outstanding at any time other
than as a result of fluctuations in foreign currency exchange rates or interest
rates or by reason of fees, indemnities and compensation payable thereunder; and
(c) arising from agreements providing for indemnification, adjustment of
purchase price or similar obligations incurred in connection with the
disposition of any business, assets or Restricted Subsidiary; (6) intercompany
Indebtedness between or among an Issuer and any of the Issuers' Restricted
Subsidiaries; provided, however, that (a) if the Company is the obligor on the
Indebtedness, that Indebtedness is expressly subordinated to the prior payment
in full in cash of all obligations with respect to the Notes, the Indenture and
the First Supplemental Indenture, and (b) if an Issuer's Restricted Subsidiary
is the obligor on the Indebtedness, that Indebtedness is expressly subordinated
to the prior payment in full in cash of all obligations with respect to any
guarantee of the Notes, Indenture and First Supplemental Indenture issued under
Section 4.10 covenant hereof, and (c) (I) any subsequent event or issuance or
transfer of Equity Interests that results in any such Indebtedness being held by
a Person other than an Issuer or a Restricted Subsidiary of an Issuer and (II)
any sale or other transfer of any of that Indebtedness to a Person other than an
Issuer or one of the Issuers' Restricted Subsidiaries shall be deemed, in each
case, to constitute an Incurrence of that Indebtedness by such Issuer or
Restricted Subsidiary, as the case may be, that was not permitted by this clause
(6); (7) Indebtedness due and owing to governmental entities in connection with
telecommunications license, permit or similar fees or Indebtedness incurred to
finance the payment of deposits with and license, permit or similar fees to the
FCC and other governmental authorities, including, without limitation,
international telecommunications agencies and governmental authorities; (8)
Indebtedness the proceeds of which are, or the credit support provided by that
Indebtedness is, used to finance the development, construction, expansion,
operation or acquisition of assets used or to be used in, or at least a majority
of the Voting Stock of, a Communications and Data Access Business (including, in
the case of the acquisition of at least a majority of the Voting Stock of a
Communications and Data Access Business, Acquired Debt not to

                                       13
<PAGE>   21
exceed, individually or in the aggregate, $200.0 million principal amount;
provided, however, that such Acquired Debt was not incurred in connection with
or in contemplation of such acquisition); (9) the guarantee by an Issuer or any
Restricted Subsidiary of an Issuer of Indebtedness of an Issuer or a Restricted
Subsidiary of an Issuer that was permitted to be incurred by Section 4.04
hereof; (10) Indebtedness under this clause (10) the aggregate principal amount
or accreted amount of which, taken together with the aggregate principal amount
or accreted amount of all other Indebtedness issued under this clause (10), does
not exceed 2.0 times the aggregate net proceeds received by us after the date
hereof from the issuance and sale (other than to one or more of an Issuers'
Subsidiaries) of Equity Interests (other than in respect of Disqualified Stock),
other than (A) proceeds to the extent relied upon to permit the making of one or
more Restricted Payments in compliance with Section 4.03 hereof, and (B)
proceeds to the extent relied upon by the Issuers to permit the making of one or
more Permitted Investments pursuant to clause (8) of the definition of Permitted
Investments; and (11) Indebtedness not otherwise permitted hereunder in an
aggregate principal amount or accreted amount which, when aggregated with the
principal amount or accreted amount of all other Indebtedness then outstanding
and incurred pursuant to this clause (11), does not exceed $50.0 million at any
one time outstanding.

            For purposes of the foregoing clause (10), the amount of net
proceeds the Issuers receive from the issuance and sale of Equity Interests, if
other than cash, will be determined by each Issuer's Board of Directors in good
faith, whose resolution will be delivered to the Trustee, and the Board of
Director's determination shall be based upon the opinion or appraisal issued by
an investment banking firm, appraisal firm or accounting firm, in each case of
national standing, if the fair market value of such Equity Interests exceeds
$15.0 million.

            "Permitted Holder" means either MCI Worldcom or Vulcan Ventures, or
any majority owned Affiliate thereof.

            "Permitted Investment" means (1) any Investment in an Issuer or in
any Restricted Subsidiary of an Issuer by an Issuer or any of their Restricted
Subsidiaries; (2) any Investment in Cash Equivalents; (3) any Investment by an
Issuer or any Restricted Subsidiary of an Issuer in a Person engaged in a
Communications and Data Access Business, if as a result of that Investment (a)
that Person becomes a Restricted Subsidiary of an Issuer or (b) that Person is
merged, consolidated or amalgamated with or into, or transfers or conveys
substantially all of its assets to, or is liquidated into, an Issuer or
Restricted Subsidiary of an Issuer; (4) any Restricted Investment made as a
result of the receipt of non-cash consideration from an Asset Sale that was made
pursuant to and in compliance with the provisions described under Section 4.07
hereof; (5) any acquisition of assets solely in exchange for the issuance of
Equity Interests of an Issuer, other than Disqualified Stock; (6) other
Investments by an Issuer or any Restricted Subsidiary of an Issuer in any Person
having an aggregate fair market value, measured as of the date made and without
giving effect to subsequent changes in value, when taken together with all other
Investments made pursuant to this clause (6) that are at the time outstanding,
not to

                                       14
<PAGE>   22
exceed $50.0 million; (7) Investments arising in connection with Hedging
Obligations; (8) any Investment in a Person engaged or proposed to be engaged in
a Communications and Data Access Business made in exchange for, or out of the
proceeds of, an offering for cash of shares of the Capital Stock of an Issuer,
other than Disqualified Stock, excluding any proceeds from an offering of shares
of the Capital Stock of such Issuer that are relied upon by the Issuers to Incur
any Indebtedness pursuant to clause (10) of the definition of the term Permitted
Debt; (9) payroll, travel and similar advances to cover matters that are
expected at the time of such advance ultimately to be treated as expenses in
accordance with GAAP; and (10) investments in negotiable instruments held for
collection, lease, utility and workers' compensation, performance and other
similar pledges or deposits, and other pledges or deposits permitted under
Section 4.05 hereof.

            "Permitted Liens" means (1) Liens on the assets of an Issuer or of
any Restricted Subsidiary of an Issuer to secure Indebtedness, other than
Subordinated Debt, permitted by the Indenture and this First Supplemental
Indenture to be Incurred; (2) Liens on property of a Person existing at the time
such Person is merged into or consolidated with an Issuer or any Restricted
Subsidiary of an Issuer; provided, however, that such Liens were in existence
prior to the contemplation of such merger or consolidation and do not extend to
any assets other than those of the Person merged into or consolidated with such
Issuer or Restricted Subsidiary; (3) Liens on property existing at the time of
acquisition of that property by an Issuer or any Restricted Subsidiary of an
Issuer; provided, however, that such Liens were in existence prior to the
contemplation of such merger or consolidation and do not extend to any assets
other than those of the Person merged into or consolidated with such Issuer or
Restricted Subsidiary; (4) Liens existing on the date hereof; (5) Liens in favor
of an Issuer or any Restricted Subsidiary of an Issuer; (6) Liens incurred in
the ordinary course of the business of the Issuers or of any of their Restricted
Subsidiaries with respect to obligations that do not exceed, in the aggregate at
any one time outstanding, more than 5% of the total consolidated assets of the
Issuers and their Restricted Subsidiaries, determined in accordance with GAAP
and based on the most recent publicly available consolidated balance sheet, and
that (a) are not incurred in connection with the borrowing of money or the
obtaining of advances or credit, other than trade credit in the ordinary course
of business, and (b) do not in the aggregate materially detract from the value
of the property or materially impair the use thereof in the ordinary course of
business by the Issuers or their Restricted Subsidiaries; (7) Liens to secure
the performance of statutory obligations, surety or appeal bonds, performance
bonds, deposits to secure the performance of bids, trade contracts, government
contracts, leases or licenses or other obligations of a like nature Incurred in
the ordinary course of business, including, without limitation, landlord Liens
on leased properties; (8) Liens for taxes, assessments or governmental charges
or claims that are not yet delinquent or that are being contested in good faith
by appropriate proceedings promptly instituted and diligently prosecutes,
provided that any reserve or other appropriate provision as shall be required to
conform with GAAP shall have been made for that reserve or provision; (9)
carriers', warehousemen's, mechanics', landlords' materialmen's, repairmen's or
other like Liens arising in the ordinary course of business in respect of
obligations not overdue for a period in excess of 60 days or which are being

                                       15
<PAGE>   23
contested in good faith by appropriate proceedings promptly instituted and
diligently prosecuted; provided, however, that any reserve or other appropriate
provision as shall be required to conform with GAAP shall have been made for
that reserve or provision; (10) easements, rights-of-way, zoning and similar
restrictions and other similar encumbrances or title defects incurred, or leases
or subleases granted to third parties, in the ordinary course of business, which
do not in any case materially detract from the value of the property subject to
the Lien or do not interfere with or adversely affect in any material respect
the ordinary conduct of the business of the Issuers and their Restricted
Subsidiaries taken as a whole; (11) Liens in favor of customs and revenue
authorities to secure payment of customs duties in connection with the
importation of goods in the ordinary course of business and other similar Liens
arising in the ordinary course of business; (12) leases or subleases granted to
third Persons not interfering with the ordinary course of business of the
Issuers and their Restricted Subsidiaries; (13) Liens, other than any Lien
imposed by ERISA or any rule or regulation promulgated under ERISA, incurred or
deposits made in the ordinary course of business in connection with workers'
compensation, unemployment insurance, and other types of social security; (14)
deposits made in the ordinary course of business to secure liability to
insurance carriers; (15) any attachment or judgment Lien in respect of a
judgment not constituting an Event of Default under clause (8) of Section 6.01
hereof; (16) any interest or title of a lessor or sublessor under any operating
lease, conditional sale, title retention, consignment or similar arrangements
entered into in the ordinary course of business; (17) Liens under licensing
agreements for use of intellectual property entered into in the ordinary course
of business; (18) Liens under the Pledge Agreement; (19) bankers' liens in
respect of deposit accounts; (20) Liens imposed by law incurred by the Issuers
or their Restricted Subsidiaries in the ordinary course of business; and (21)
Liens to secure Attributable Debt in connection with Sale and Leaseback
Transactions.

            "Permitted Refinancing Indebtedness" means any Indebtedness of an
Issuer or any Restricted Subsidiary of an Issuer issued in exchange for, or the
net proceeds of which are or are to be used to extend, refinance, renew,
replace, defease or refund other Indebtedness of an Issuer or any Restricted
Subsidiary of an Issuer, other than intercompany Indebtedness; provided,
however, that: (1) the principal amount, or accreted value, if applicable, of
such Permitted Refinancing Indebtedness does not exceed the principal amount of,
or accreted value, if applicable, plus accrued and unpaid interest on, any
Indebtedness so extended, refinanced, renewed, replaced, defeased or refunded,
plus the amount of customary or prescribed premiums and reasonable expenses
incurred in connection with that extension, refinancing, renewal, replacement,
defeasance or refunding; (2) the Permitted Refinancing Indebtedness has a final
maturity date later than the final maturity date of, and has a Weighted Average
Life to Maturity equal to or greater than the Weighted Average Life to Maturity
of, the Indebtedness being extended, refinanced, renewed, replaced, defeased or
refunded; (3) if the Indebtedness being extended, refinanced, renewed, replaced,
defeased or refunded is subordinated in right of payment to the Notes, such
Permitted Refinancing Indebtedness has a final maturity date later than the
final maturity date of, and is subordinated in right of payment to, the Notes on
terms at least as favorable to the Holders as those contained in the
documentation

                                       16
<PAGE>   24
governing the Indebtedness being extended, refinanced, renewed, replaced,
defeased or refunded; and (4) the Indebtedness is Incurred by an Issuer if such
Issuer is the obligor on the Indebtedness or by an Issuer or a Restricted
Subsidiary of an Issuer if a Restricted Subsidiary of an Issuer is the obligor
on the Indebtedness being extended, refinanced, renewed, replaced, defeased or
refunded.

            "Person" means any individual, corporation, limited liability
company, partnership, joint venture, association, joint-stock company, trust,
unincorporated organization or government or any agency or political subdivision
of that government or agency.

            "Pledge Account" means that certain segregated account provided for
under the Pledge Agreement.

            "Pledge Agreement" means that certain Pledge Agreement entered into
by the Issuers and the Trustee concurrently with this First Supplemental
Indenture and providing for an amount of cash or U.S. Government Securities
sufficient to pay the first four scheduled interest payments on the Notes to be
deposited with and held by the Escrow Agent for such purpose.

            "Pledged Securities" means the cash and U.S. Government Securities
deposited in the Pledge Account, together with any interest or other
distributions received on that cash or those securities.

            "Preferred Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents, however designated,
whether voting or non-voting, of that Person's equity that have a preference as
to the payment of dividends or as to payments upon a liquidation of that Person,
whether now outstanding or issued after the date hereof, including without
limitation, all series and classes of such equity.

            "Reference Period" means the latest two fiscal quarters for which
financial statements are publicly available.

            "Restricted Investment" means an Investment other than a Permitted
Investment.

            "Restricted Payment" means any payment or action to: (1) declare or
pay any dividend or make any other payment or distribution on account of Equity
Interests of an Issuer or any Restricted Subsidiary of an Issuer, including,
without limitation, any payment in connection with any merger or consolidation
involving an Issuer, or to the direct or indirect holders of Equity Interests of
an Issuer or any Restricted Subsidiary of an Issuer in their capacity as such,
other than dividends or distributions payable in Equity Interests, except
Disqualified Stock, of an Issuer or Restricted Subsidiary of an Issuer; (2)
purchase, redeem or otherwise acquire or retire for value, including without
limitation, in connection with any merger or consolidation involving an Issue,
any Equity Interests of an Issuer or of a direct or indirect parent or other
Affiliate of an Issuer, other than in

                                       17
<PAGE>   25
exchange for Equity Interests, except Disqualified Stock, of an Issuer or any
Restricted Subsidiary of an Issuer; (3) make any payment on or with respect to,
or purchase, redeem, defease or otherwise acquire or retire for value any
Indebtedness that is subordinated to the Notes, except a payment of interest or
principal at Stated Maturity; or (4) make any Restricted Investment.

            "Restricted Subsidiary" means any of Subsidiary other than an
Unrestricted Subsidiary.

            "Sale and Leaseback Transaction" of any Person means an arrangement
with any lender or investor or to which such lender or investor is a party
providing for the leasing by such Person of any property or asset of such Person
which has been or is being sold or transferred by such Person more than 365 days
after the acquisition thereof or the completion of construction or commencement
of operation thereof to such lender or investor or to any Person to whom funds
have been or are to be advanced by such lender or investor on the security of
such property or asset. The stated maturity of such arrangement is the date of
the last payment of rent or any other amount due under such arrangement prior to
the first date on which such arrangement may be terminated by the lessee without
payment of a penalty.

            "Securities Act" means the Securities Act of 1933, as amended.

            "Separability Legend" has the meaning specified in Section 2.06(f)
hereof.

            "Separation Date" means the earliest to occur of (i) August 15,
2000, (ii) the occurrence of an Event of Default, (iii) the occurrence of an
Exercise Event, as defined in the Warrant Agreement, and (iv) such other date as
Lehman Brothers Inc. shall determine in its sole discretion.

            "Series A1 Preferred Stock" means the Series A1 Preferred Stock of
the Company.

            "Series A2 Preferred Stock" means the Series A2 Preferred Stock of
the Company.

            "Significant Subsidiary" means any Restricted Subsidiary that meets
any of the following conditions: (1) the Issuers' and their Restricted
Subsidiaries' investments in and advances to such Restricted Subsidiary exceed
10% of the total assets of the Issuers and their Restricted Subsidiaries
consolidated as of the end of the most recently completed fiscal year (or, for a
proposed business combination to be accounted for as a pooling of interests,
when the number of common shares exchanged or to be exchanged by an Issuer
exceeds 10% of its total common shares outstanding at the date the combination
is initiated); (2) the Issuers' and their Restricted Subsidiaries' proportionate
share of the total assets (after intercompany eliminations) of such Restricted
Subsidiary exceeds 10% of the total assets of the Issuers and their Restricted
Subsidiaries

                                       18
<PAGE>   26
consolidated as of the end of the most recently completed fiscal year; or (3)
the Issuers and their Restricted Subsidiaries' equity in the income from
continuing operations before income taxes, extraordinary items and cumulative
effect of a change in accounting principle of such Restricted Subsidiary exceeds
10% of such income of the Issuers and their Restricted Subsidiaries consolidated
for the most recently completed fiscal year, in each case as computed in
accordance with Rule 1-02(w) of Regulation S-X under the Securities Act.

            "Stated Maturity" means (1) with respect to any debt security, the
date specified in such debt security as the fixed date on which the final
installment of principal of such debt security is due and payable and (2) with
respect to any scheduled installment of principal of or interest on any debt
security, the date specified in such debt security as the fixed date on which
such installment is due and payable.

            "Subordinated Debt" means any of Indebtedness subordinated in right
of payment to the Notes.

            "Subsidiary" means, with respect to any Person, (1) any corporation,
association or other business entity of which more than 50% of the total voting
power of shares of Capital Stock entitled, without regard to the occurrence of
any contingency, to vote in the election of directors, managers or trustees
thereof is at the time owned or controlled, directly or indirectly, by that
Person and (2) any partnership (a) the sole general partner or the managing
general partner of which is such Person or an entity described in clause (1) and
related to such Person or (b) the only general partners of which are such Person
or of one or more entities described in clause (1) and related to such Person or
(c) any combination entities described in clauses (1) and (2).

            "Unrestricted Subsidiary" means any Subsidiary that is designated by
the Board of Directors as an Unrestricted Subsidiary pursuant to a resolution of
the Board of Directors, but only to the extent that such Subsidiary: (1) has no
Indebtedness other than Non-Recourse Debt; and (2) is a Person with respect to
which neither the Issuers nor any of their Restricted Subsidiaries has any
direct or indirect obligation (a) to subscribe for additional Equity Interests,
or (b) to maintain or preserve such Person's financial condition or to cause
such Person to achieve any specified levels of operating results.

            "U.S. Government Securities" means securities that are direct
obligations of, or obligations guaranteed by, the United States of America for
the payment of which its full faith and credit is pledged.

            "Voting Stock" of any Person as of any date means the Capital Stock
of that Person that is at the time entitled to vote in the election of directors
or similar individuals of that Person.

            "Weighted Average Life to Maturity" means, when applied to any
Indebtedness at any date, the number of years obtained by dividing (1) the sum
of the products obtained by multiplying (a) the amount of each then remaining
installment,

                                       19
<PAGE>   27
sinking fund, serial maturity or other required payments of principal, including
payment at final maturity, in respect thereof, by (b) the number of years,
calculated to the nearest one-twelfth, that will elapse between such date and
the making of such payment, by (2) the then outstanding principal amount of such
Indebtedness.

                                       20
<PAGE>   28
            SECTION 1.03. OTHER DEFINITIONS.

<TABLE>
<CAPTION>
                                                               Defined in
         Term                                                    Section
         ----                                                 ------------
<S>                                                           <C>
"Additional Amounts"                                          Section 5.03
"Additional Notes"                                            Section 2.02
"Affiliate Transaction"                                       Section 4.11
"Asset Sale Offer"                                            Section 4.10
"Change of Control Offer"                                     Section 4.14
"Change of Control Payment"                                   Section 4.14
"Change of Control Payment Date"                              Section 4.14
"Company"                                                         Preamble
"Event of Default"                                            Section 6.01
"Finance Sub"                                                     Preamble
"First Supplemental Indenture"                                    Preamble
"Holders"                                                         Preamble
"Indenture"                                                       Preamble
"Initial Warrant Agent"                                           Preamble
"Interest Payment Date"                                       Section 2.03
"Issuers" ("Issuer")                                              Preamble
"Notes"                                                       Section 2.01
"Offer Amount"                                                Section 3.02
"Offer Period"                                                Section 3.02
"Payment Default"                                             Section 6.01
</TABLE>

                                       21
<PAGE>   29

<TABLE>
<S>                                                           <C>
"Purchase Date"                                               Section 3.02
"Regular Record Date"                                         Section 2.03
"Repurchase Offer"                                            Section 3.02
"Separability Legend"                                         Section 2.06
"Trustee"                                                         Preamble
"Warrants"                                                        Preamble
"Warrant Agent"                                                   Preamble
"Warrant Agreement"                                               Preamble
</TABLE>

                                    ARTICLE 2

                               THE SERIES OF NOTES

            SECTION 2.01. TITLE OF THE SECURITIES. The series of Notes issued in
accordance with the terms and conditions of this First Supplemental Indenture
shall be designated the "13% Senior Notes due 2010" (together with any
Additional Notes issued in accordance with Section 2.02 hereof, the "Notes").

            SECTION 2.02. LIMITATION ON AGGREGATE PRINCIPAL AMOUNT AND
ADDITIONAL NOTES. The Notes are initially limited to an aggregate principal
amount of $300,000,000, all of which will be issued on the date hereof, and an
additional amount of Notes that, together with all other Notes issued under this
Indenture (the "Additional Notes") is no more than $600,000,000 in aggregate
principal amount or principal amount at maturity, that may be issued from time
to time after the date hereof, subject to compliance with Section 4.04 hereof.

            Nothing contained in this Section 2.02 or elsewhere in this First
Supplemental Indenture, or in the Notes, is intended to or shall limit execution
by the Issuers or authentication or delivery by the Trustee of Notes under the
circumstances contemplated in the Indenture or this First Supplemental
Indenture.

            The Issuers may, pursuant to the provisions of the Indenture, and
without the consent of Holders of the Notes, create and issue further Notes
ranking equally and ratably with the Notes initially issued hereunder in all
respects (or in all respects other than the payment of interest accruing prior
to the Issue Date of such Additional Notes or except for the first payment of
interest following the Issue Date of such Additional Notes) and so that such
Additional Notes shall be consolidated with and form a single series with

                                       22
<PAGE>   30
the previously issued Notes and shall have the same terms as to status,
redemption or otherwise as the Notes. Any Additional Notes shall be issued in
accordance with Section 2.01 of the Indenture.

            SECTION 2.03. INTEREST AND INTEREST RATE; MATURITY DATE OF NOTES.
The Notes shall bear interest at a rate of 13%, from their original Issue Date
or from the immediately preceding Interest Payment Date to which interest has
been paid on such Notes or duly provided for, payable semi-annually in arrears
on February 15 and August 15 of each year, commencing August 15, 2000 with
respect to the Notes issued on the date hereof (each an "Interest Payment
Date"), to the Persons in whose name the Notes are registered in the security
register at the close of business on the February 1 or August 1 (whether or not
a Business Day), as the case may be, next preceding such Interest Payment Date
(each, a "Regular Record Date"). Interest shall be computed on the basis of a
360-day year comprised of twelve 30-day months.

            The Issuers shall pay principal, premium, if any, and interest, to
the extent required, on the Notes by wire transfer of immediately available
funds to the registered Holder of the Global Note representing such Notes at the
corporate trust operations office of the Trustee; provided, however, that with
respect to Notes issued in certificated form, the Issuers may pay interest at
their option by check mailed to the address of the Person entitled to payment as
it appears in the Security Register or by wire transfer of immediately available
funds in accordance with instructions provided by the registered Holders of such
certificated Notes.

            The Stated Maturity of the Notes shall be February 15, 2010.

            If any Interest Payment Date or the Stated Maturity falls on a day
that is not a Business Day, the required payment shall be made on the next
Business Day as if it were made on the date such payment was due and no interest
shall accrue on the amount so payable for the period from and after such
Interest Payment Date or the Stated Maturity, as the case may be.

            SECTION 2.04. FORM. The Notes and the Trustee's certificate of
authentication shall be substantially in the form of Exhibit A hereto. The Notes
may have notations, legends or endorsements required by law, stock exchange rule
or usage. Each Note shall be dated the date of its authentication. The Notes
shall be in denominations of $1,000 and integral multiples thereof.

            The terms and provisions contained in the Notes shall constitute,
and are hereby expressly made, a part of this First Supplemental Indenture and
the Issuers, the Guarantor and the Trustee, by their execution and delivery of
this First Supplemental Indenture, expressly agree to such terms and provisions
and to be bound thereby. To the extent any provision of any Note conflicts with
the express provisions of the Indenture or this First Supplemental Indenture,
the provisions of the Indenture or this First

                                       23
<PAGE>   31
Supplemental Indenture shall govern and be controlling, subject to the
resolution of inconsistent provisions in accordance with Section 1.01 hereof.

            Notes issued in global form shall be substantially in the form of
Exhibit A hereto (including the Global Note Legend thereon and the "Schedule of
Exchanges of Interests in the Global Note" attached thereto). Notes issued in
certificated form shall be substantially in the form of Exhibit A attached
hereto (but without the Global Note Legend thereon and without the "Schedule of
Exchanges of Interests in the Global Note" attached thereto). Each Global Note
shall represent such of the outstanding Notes as shall be specified therein and
each shall provide that it shall represent the aggregate principal amount of
outstanding Notes from time to time endorsed thereon and that the aggregate
principal amount of outstanding Notes represented thereby may from time to time
be reduced or increased, as appropriate, to reflect exchanges and redemptions.
Any endorsement of a Global Note to reflect the amount of any increase or
decrease in the aggregate principal amount of outstanding Notes represented
thereby shall be made by the Trustee or the Custodian, at the direction of the
Trustee, in accordance with instructions given by the Holder thereof as required
by Section 2.07 of the Indenture.

            SECTION 2.05. OTHER DEBT SECURITIES. The Notes and any debt
securities subsequently issued under the Indenture but not under this First
Supplemental Indenture, shall be treated as distinct classes of debt securities
for all purposes under the Indenture, including waivers, amendments, redemptions
and offers to purchase.

            SECTION 2.06. ASSOCIATED WARRANTS OFFERING. The Notes issued on the
date hereof are being issued together with Warrants.

            (a) LEGENDS. In addition to other legends provided for in the
Indenture, the following legends shall appear on the face of all Global Notes
and Note issued in certificated form under this First Supplemental Indenture and
relating to the Notes originally issued on the date hereof:

            (i) SEPARABILITY LEGEND. Until the Separation Date, each Global Note
and Notes issued in certificated form under this First Supplemental Indenture
shall bear a legend in substantially the following form (the "Separability
Legend"):

            "UNTIL THE SEPARATION DATE (AS DEFINED), THIS NOTE HAS BEEN ISSUED
            WITH, AND MUST BE TRANSFERRED WITH, THE ASSOCIATED WARRANTS TO
            PURCHASE COMMON STOCK OF THE COMPANY. EACH $1,000 PRINCIPAL AMOUNT
            OF NOTES IS ASSOCIATED WITH A WARRANT TO PURCHASE 4.75 SHARES OF
            COMMON STOCK, SUBJECT TO ADJUSTMENT UNDER CERTAIN CIRCUMSTANCES. A
            COPY OF THE WARRANT AGREEMENT PURSUANT TO WHICH THE WARRANTS HAVE
            BEEN ISSUED IS AVAILABLE FROM THE COMPANY UPON REQUEST."

                                       24
<PAGE>   32
            (ii) ORIGINAL ISSUE DISCOUNT LEGEND. Each Global Note and Notes
issued in certificated form under this First Supplemental Indenture shall bear a
legend in substantially the following form:

            "FOR PURPOSES OF SECTION 1273 OF THE INTERNAL REVENUE CODE OF 1986,
            AS AMENDED (THE "CODE"), THIS SECURITY HAS ORIGINAL ISSUE DISCOUNT.
            FOR PURPOSES OF SECTION 1273 OF THE CODE, THE ISSUE PRICE IS $787.94
            AND THE AMOUNT OF ORIGINAL ISSUE DISCOUNT IS $212.06, IN EACH CASE
            PER $1,000 PRINCIPAL AMOUNT OF THIS SECURITY. FOR PURPOSES OF
            SECTION 1275 OF THE CODE, THE YIELD TO MATURITY COMPOUNDED
            SEMIANNUALLY IS 17.57%."

            (b) SEPARATION OF NOTES AND WARRANTS.

            (i) Prior to the Separation Date, no Notes may be sold, assigned or
otherwise transferred to any Person unless, simultaneously with such transfer,
the Trustee receives confirmation from the Warrant Agent that the Holder of the
Notes has requested a transfer of the related Warrants to the same transferee.

            (ii) On or after the Separation Date, the Holder of a Note
containing a Separability Legend may surrender such Note accompanied by a
written application to the Trustee, duly executed by the Holder, for a new Note
or Notes not containing a Separability Legend. Whether or not the Holder obtains
a new Note, from and after the Separation Date, the Separability Legend shall
have no further force and effect.

                                    ARTICLE 3

                            REDEMPTION AND PREPAYMENT

            SECTION 3.01. OPTIONAL REDEMPTION. Commencing February 15, 2005, the
Issuers may redeem the Notes, at their option, in whole or in part, at any time
or from time to time, upon not less than 30 nor more than 60 days' prior notice
mailed by first class mail to each registered Holder's address as it appears in
the applicable note register, at the following redemption prices expressed in
percentages of principal amount, plus accrued and unpaid interest to the
redemption date, if redeemed during the 12-month period commencing on February
15 of the years set forth below:

<TABLE>
<CAPTION>
                                       REDEMPTION
YEAR                                     PRICE
----                                   --------
<S>                                    <C>
2005..............................     108.000%
</TABLE>

                                       25
<PAGE>   33

<TABLE>
<S>                                    <C>
2006..............................     106.000%
2007..............................     104.000%
2008..............................     102.000%
2009 and thereafter...............     100.000%
</TABLE>

            SECTION 3.02. REPURCHASE AT THE OPTION OF HOLDERS. In the event
that, pursuant to Section 4.07 hereof, the Issuers shall be required to commence
an offer to all Holders to purchase Notes (a "Repurchase Offer"), and they shall
follow the procedures specified below.

            The Repurchase Offer shall remain open for a period of 20 Business
Days following its commencement and no longer, except to the extent that a
longer period is required by applicable law (the "Offer Period"). No later than
five Business Days after the termination of the Offer Period (the "Purchase
Date"), the Issuers shall purchase at the purchase price (as determined in
accordance with Section 4.07 hereof, the principal amount of Notes required to
be purchased pursuant to Section 4.07 hereof, in the aggregate (the "Offer
Amount") or, if less than the Offer Amount has been tendered, all Notes tendered
in response to such Repurchase Offer. Payment for any Notes so purchased shall
be made in the same manner as interest payments are made.

            If the Purchase Date is on or after an interest record date and on
or before the related interest payment date, any accrued and unpaid interest
shall be paid to the Person in whose name a Note is registered at the close of
business on such record date, and no additional interest shall be payable to
Holders who tender Notes pursuant to such Repurchase Offer.

            Upon the commencement of a Repurchase Offer, the Issuers shall send,
by first class mail, a notice to the Trustee and each of the Holders, with a
copy to the Trustee. The notice shall contain all instructions and materials
necessary to enable such Holders to tender Notes pursuant to such Repurchase
Offer. The Repurchase Offer shall be made to all Holders. The notice, which
shall govern the terms of such Repurchase Offer, shall state:

            (a) that the Repurchase Offer is being made pursuant to this Section
3.02 and Section 4.07 hereof, and the length of time the Repurchase Offer shall
remain open;

            (b) the Offer Amount, the purchase price and the Purchase Date;

            (c) that any Note not tendered or accepted for payment shall
continue to accrue interest;

                                       26
<PAGE>   34
            (d) that, unless the Issuers default in making such payment, any
Note accepted for payment pursuant to the Repurchase Offer shall cease to accrue
interest after the Purchase Date;

            (e) that Holders electing to have a Note purchased pursuant to any
Repurchase Offer may elect to have Notes purchased in integral multiples of
$1,000 only;

            (f) that Holders electing to have a Note purchased pursuant to any
Repurchase Offer shall be required to surrender the Note, with the form entitled
"Option of Holder to Elect Purchase" on the reverse of the Note completed, or
transfer by book-entry transfer, to the Issuers, a Depositary, if appointed by
the Issuers, or a Paying Agent at the address specified in the notice before the
Purchase Date;

            (g) that Holders shall be entitled to withdraw their election if the
Issuers, the Depositary or the Paying Agent, as the case may be, receives, not
later than the expiration of the Offer Period, a telegram, telex, facsimile
transmission or letter setting forth the name of the Holder, the principal
amount of the Notes the Holder delivered for purchase and a statement that such
Holder is withdrawing his election to have such Notes purchased; and

            (h) that, if the aggregate principal amount of Notes surrendered by
Holders exceeds the Offer Amount, the Notes shall be selected for purchase
pursuant to the terms of this Section 3.02, and that Holders whose Notes were
purchased only in part shall be issued new Notes equal in principal amount to
the unpurchased portion of the Notes surrendered (or transferred by book-entry
transfer).

            On or before the Purchase Date, the Issuers shall, to the extent
lawful, accept for payment, pursuant to the terms of this Section 3.02, the
Offer Amount of Notes or portions thereof tendered pursuant to the Repurchase
Offer, or if less than the Offer Amount has been tendered, all Notes tendered,
and shall deliver to the Trustee an Officers' Certificate stating that such
Notes or portions thereof were accepted for payment by the Issuers in accordance
with the terms of this Section 3.02. The Issuers, the Depositary or the Paying
Agent, as the case may be, shall promptly (but in any case not later than five
Business days after the Purchase Date) mail or deliver to each tendering Holder
an amount equal to the purchase price of the Notes tendered by such Holder and
accepted by the Issuers for purchase, and the Issuers shall promptly issue a new
Note, and the Trustee, upon written request from the Issuers shall authenticate
and mail or deliver such new Note to such Holder, in a principal amount equal to
any unpurchased portion of the Note surrendered. Any Note not so accepted shall
be promptly mailed or delivered by the Issuers to the Holder thereof. The
Issuers shall publicly announce through PR Newswire, Dow Businesswire or any
comparable wire service that distributes releases to the broad financial and
investor media, the results of the Repurchase Offer on the Purchase Date.

                                       27
<PAGE>   35
            The Issuers shall comply with the requirements of Rule 14e-1 under
the Exchange Act, and any other securities laws and regulations thereunder to
the extent that such laws or regulations are applicable in connection with the
repurchase of the Notes pursuant to the Repurchase Offer. To the extent that the
provisions of Rule 14e-1 under the Exchange Act or any securities laws or
regulations conflict with the provisions of this Section 3.02 or with Section
4.07 hereof, the Issuers will comply with the applicable securities laws and
regulations and will not be deemed to have breached its obligations under those
sections of this First Supplemental Indenture.

            SECTION 3.03. Any redemption pursuant to Section 3.01 or 3.02 hereof
shall also be made in accordance with the provisions of Section 3.01 through
3.06 of the Indenture. Notes called for redemption become due and payable on the
date fixed for redemption. Interest will cease to accrue on the Notes or
portions thereof being redeemed on and after the redemption date, unless the
Issuers default in the payment of the redemption or repurchase price.

                                    ARTICLE 4

                                    COVENANTS

            SECTION 4.01. REPORTS. (a) The Issuers shall file on a timely basis
with the SEC, to the extent such filings are accepted by the SEC and whether or
not the Issuers have a class of securities registered under the Exchange Act,
the annual reports, quarterly reports, current reports and other documents that
the Issuers would be required to file if they were subject to Section 13 or
15(d) of the Exchange Act, including a "Management's Discussion and Analysis of
Financial Condition and Results of Operations" that describes the financial
condition and results of operations of the Issuers and their consolidated
Subsidiaries, as well as disclosure showing in reasonable detail, either on the
face of the financial statements or in the footnotes to those statements, the
financial condition and results of operations of the Issuers and their
Restricted Subsidiaries separate from the financial information and results of
operations of their Unrestricted Subsidiaries and, with respect to the annual
information only, a report on those financial statements by the Issuers'
certified independent accountants. The Issuers shall also (1) file with the
Trustee, and provide to each Holder, without cost to that Holder, copies of all
of the above reports and documents within 15 days after the date on which the
Issuers file such reports and documents with the SEC or the date on which the
Issuers would be required to file such reports and documents if they were so
required, and (2) if filing such reports and documents with the SEC is not
accepted by the SEC or is prohibited under the Exchange Act, to supply at the
Issuers' cost copies of such reports and documents to any prospective Holder
promptly upon request. Notwithstanding the foregoing, prior to a Holding Company
Reorganization Metricom Finance will not have any of the foregoing obligations
unless and to the extent otherwise required by law.

            (b) The Issuers shall, so long as any of the Notes are outstanding,
deliver to the Trustee, forthwith upon any Officer becoming aware of any Default
or

                                       28
<PAGE>   36
Event of Default, an Officers' Certificate specifying such Default or Event of
Default and what action the Issuers are taking or propose to take with respect
thereto.

            SECTION 4.02. RELEASE OF OBLIGATIONS FOLLOWING HOLDING COMPANY
REORGANIZATION. Upon consummation of the Holding Company Reorganization, the
obligation of (a) Finance Sub with respect to the Notes shall automatically be
extinguished and only the Company shall continue as the sole obligor on the
Notes, if the Holding Company Reorganization is one in which the assets and
operations of the Company are transferred to Finance Sub or any of its
Restricted Subsidiaries, as contemplated by clause (1) of the definition of
Holding Company Reorganization, or (b) the Company with respect to the Notes
shall automatically be extinguished and only Finance Sub shall continue as the
sole obligor on the Notes, if the Holding Company Reorganization is one in which
the assets and operations of the Company remain with the Company or its
successor corporation or organization, as contemplated by clause (2) of the
definition of Holding Company Reorganization; provided, however, that upon
consummation of the Holding Company Reorganization, the Company's guarantee of
Finance Sub's obligations with respect to the Notes shall automatically, and
without further notice to or action by the Holders, be extinguished and shall
cease to be of any further force or effect. In that event, the Trustee shall, at
the request of either obligor, enter into a Supplemental Indenture to evidence
the release of the Company or Finance Sub, as the case may be, from its
obligations on the Notes, and the release of the Company from its guarantee of
Finance Sub's obligations with respect to the Notes.

            SECTION 4.03. LIMITATION ON RESTRICTED PAYMENTS. The Issuers shall
not make, and shall not permit any Restricted Subsidiary to make, directly or
indirectly a Restricted Payment, unless, at the time of and after giving effect
to that Restricted Payment: (1) no Default or Event of Default will have
occurred and be continuing or would occur as a consequence of the Restricted
Payment; (2) the Issuers would, at the time of the Restricted Payment and after
giving pro forma effect to the Restricted Payment as if it had been made at the
beginning of the applicable Reference Period, have been permitted to incur at
least $1.00 of additional Indebtedness under the Consolidated Leverage Ratio
test set forth in the first paragraph of Section 4.04 hereof; and (3) the
Restricted Payment, together with the aggregate amount of all other Restricted
Payments made by the Issuers or any of their Restricted Subsidiaries after the
date hereof are issued, excluding Restricted Payments permitted by clauses (ii),
(iii), (iv) or (v) of the immediately following paragraph below, is less than
the sum of: (a) the amount by which Consolidated Cash Flow exceeds 1.5 times
Consolidated Fixed Charges for the period from the first day of the calendar
quarter in which the Notes are issued through the end of the last completed
fiscal quarter for which consolidated financial statements for the Issuers are
publicly available; plus (b) 100% of the aggregate net cash proceeds received by
the Issuers from the issue or sale since the date hereof of (I) Equity
Interests, other than Disqualified Stock, of the Issuers, except to the extent
any such net cash proceeds are relied upon to incur Indebtedness pursuant to
clause (10) of the definition of the term Permitted Debt or used to make
Permitted Investments pursuant to clause (8) of the definition of the term
Permitted Investment, and (II) Disqualified Stock or convertible

                                       29
<PAGE>   37
debt securities of the Issuers to the extent converted into Equity Interests,
other than Disqualified Stock, and in any case other than Equity Interests,
Disqualified Stock or convertible debt securities sold to a Restricted
Subsidiary; plus (c) to the extent not already included in Consolidated Cash
Flow for the Issuers for the relevant period, without duplication, if any
Restricted Investment that was made by the Issuers or any of their Restricted
Subsidiaries after the date hereof is sold for cash or otherwise liquidated or
repaid for cash, the lesser of: (I) the cash return of capital with respect to
the Restricted Investment, less the cost of disposition, if any; and (II) the
initial amount of the Restricted Investment; plus (d) to the extent not already
included in Consolidated Cash Flow for the Issuers the relevant period, without
duplication, an amount equal to the net reduction in Restricted Investments made
by the Issuers or any of their Restricted Subsidiaries from the redesignation of
an Unrestricted Subsidiary as a Restricted Subsidiary not to exceed the lesser
of: (I) the amount of the Restricted Investment, valued in each case as provided
under Section 4.13 hereof, previously made by the Issuers or any of their
Restricted Subsidiaries in that Unrestricted Subsidiary, which amount was
included in the calculation of the amount of Restricted Payments associated with
that Restricted Investment, and (II) the fair market value of the Investment by
the Issuers or their Restricted Subsidiaries in the Unrestricted Subsidiary at
the time of the redesignation.

            The foregoing provision will not be violated by reason of: (i) the
payment of any dividend with respect to any Equity Interests of the Issuers or
their Restricted Subsidiaries within 60 days after the date of its declaration
if the payment would comply with the foregoing paragraph at the date of its
declaration; (ii) the payment of dividends with respect to the Series A1
Preferred Stock and Series A2 Preferred Stock through November 15, 2002 in
accordance with the terms of those securities as of the date hereof; (iii) the
redemption, repurchase, defeasance or other acquisition or retirement for value
of Equity Interests of the Issuers or any Indebtedness that is subordinated to
the Notes, in each case in exchange for, or out of the net cash proceeds of the
substantially concurrent sale, other than to a Restricted Subsidiary of an
Issuer of, Equity Interests of an Issuer, other than Disqualified Stock;
provided, however, that the amount of any net cash proceeds that are utilized
for any such redemption, repurchase, retirement, defeasance or other acquisition
will be excluded from clause (b) of the preceding paragraph; (iv) the
defeasance, redemption, repurchase or other acquisition or retirement of
Indebtedness which is subordinated to the Notes with the net cash proceeds from
an incurrence of Permitted Refinancing Indebtedness; (v) the payment of any
dividend or distribution by any Restricted Subsidiary of an Issuer, including
Finance Sub, to the holders of such Restricted Subsidiary's Common Stock so long
as that dividend or distribution is paid to all holders of the Common Stock of
that Restricted Subsidiary pro rata in accordance with their interests; (vi)
payments or distributions to dissenting stockholders pursuant to applicable law,
pursuant to or in connection with a consolidation, merger or transfer of assets
that complies with the provisions of Section 5.01 of the Indenture and Section
5.01 of this First Supplemental Indenture; (vii) cash payments in lieu of the
issuance of fractional shares in connection with the exercise of any warrants,
options or other securities convertible into or exchangeable for Common Stock of
an Issuer or of a

                                       30
<PAGE>   38
Restricted Subsidiary of an Issuer; (viii) the purchase, redemption,
acquisition, cancellation or other retirement for value of shares of Capital
Stock of an Issuer or any Restricted Subsidiary of an Issuer to the extent
required by FCC rules, other comparable foreign telecommunications authorities
or any other governmental agencies in order to prevent the loss or secure the
renewal or reinstatement of any license or franchise held by the Issuers or any
Restricted Subsidiary; (ix) the purchase by the Issuers or a Restricted
Subsidiary of Equity Interests, other than with respect to Disqualified Stock,
in a Restricted Subsidiary from employees, officers or directors of that
Restricted Subsidiary in connection with the termination of their employment
with such Restricted Subsidiary; provided that the Equity Interests so
repurchased are not Capital Stock of, or Equity Interests to acquire Capital
Stock of, a class that is listed on a national securities exchange or admitted
for trading in the National Market of the Nasdaq Stock Market; provided further
that the amount of all Restricted Payments made pursuant to this clause (ix) do
not exceed $2.5 million in any calendar year or $10.0 million in the aggregate;
(x) other Restricted Payments in an aggregate amount not to exceed $5.0 million;
and (xi) the repurchase of Subordinated Debt at a purchase price not greater
than 101% of the principal or accreted amount thereof, plus accrued and unpaid
interest, if any, pursuant to a mandatory offer to repurchase made after a
Change of Control; provided, however, that the Issuers shall have first made any
Change of Control Offer and repurchased all tendered Notes pursuant to Section
4.14 hereof; provided, further, that except for clauses (i), (v), (vii) and
(viii), no Default or Event of Default shall have occurred and be continuing or
occur as a consequence of the Restricted Payment.

            The amount of all Restricted Payments, other than cash, will be the
fair market value on the date the Restricted Payment is made of the assets or
securities proposed to be transferred or issued by the Issuers or any Restricted
Subsidiary pursuant to the Restricted Payment. The fair market value of any
non-cash Restricted Payment will be determined by each Issuer's Board of
Directors in good faith, whose resolution will be delivered to the Trustee, and
its determination will be based upon an opinion or appraisal issued by an
investment banking firm, appraisal firm or accounting firm, in each case of
national standing, if the fair market value exceeds $15.0 million. Not later
than the date of making any Restricted Payment, the Issuers will deliver to the
Trustee an Officers' Certificate stating that the Restricted Payment is
permitted and setting forth the basis thereof.

            SECTION 4.04. LIMITATION ON INCURRENCE OF INDEBTEDNESS AND ISSUANCE
OF PREFERRED STOCK. The Issuers shall not, and shall not permit any of their
Restricted Subsidiaries to, directly or indirectly, Incur any Indebtedness
(including Acquired Debt) and the Issuers will not issue any Disqualified Stock
and will not permit any of their Restricted Subsidiaries to issue any shares of
Preferred Stock; provided, however, that the Issuers may Incur Indebtedness
(including Acquired Debt) or issue shares of Disqualified Stock and any of their
Restricted Subsidiaries may Incur Indebtedness if the incurrence results in a
Consolidated Leverage Ratio that is no greater than 7.0 to 1.0 if the
Indebtedness is Incurred or the Disqualified Stock is issued prior to February
1, 2005, or 6.0 to 1.0 thereafter. Notwithstanding the foregoing, as long as no

                                       31
<PAGE>   39
Default or Event of Default shall have occurred and be continuing, the Issuers
and, except as specified in the definition of Permitted Debt, any of their
Restricted Subsidiaries may Incur Permitted Debt.

            Notwithstanding any other provision of this Section 4.04, including
the definition of Permitted Debt, the Issuers and their Restricted Subsidiaries
may Incur the U.S. dollar equivalent of any Indebtedness in a foreign currency
and the maximum amount of Indebtedness that the Issuers or a Restricted
Subsidiary may incur pursuant to this covenant will not be deemed to be exceeded
with respect to any outstanding Indebtedness due solely to the result of
subsequent fluctuations in the exchange rates of currencies.

            For purposes of determining compliance with this Section 4.04, in
the event that an item of proposed Indebtedness meets the criteria of more than
one of the categories of Permitted Debt described in clauses (1) through (11) of
the definition of Permitted Debt or would be entitled to be Incurred pursuant to
the first paragraph of this Section 4.04, at the date of Incurrence, the
Issuers, in their sole discretion, shall classify and from time thereafter may
reclassify, in whole or in part, that item of Indebtedness in any manner that
complies with this Section 4.04. Accrual of interest, accretion of accreted
value and the payment of interest in the form of additional Indebtedness shall
not be deemed an Incurrence of Indebtedness for purposes of this Section 4.04.

            In addition, for purposes of determining any particular amount of
Indebtedness under this Section 4.04, neither (A) Guarantees, Liens or
obligations with respect to letters of credit supporting Indebtedness otherwise
included in the determination of such particular amount, or (B) any Liens
granted pursuant to the equal and ratable provisions referred to in Section 4.05
hereof, will be included.

            SECTION 4.05. LIMITATION ON LIENS. The Issuers shall not, and shall
not permit any of their Restricted Subsidiaries to, create, incur, assume or
otherwise cause or suffer to exist or become effective any Lien of any kind
securing Indebtedness, Attributable Debt or trade payables, other than Permitted
Liens, upon any of the Issuers' or their Restricted Subsidiaries' property or
assets, now owned or acquired after the date hereof, unless all payments due
under the Indenture or this First Supplemental Indenture with respect to the
Notes, and the applicable Notes, are secured on an equal and ratable basis with
(or if the obligations being secured rank junior in right of payment to the
Notes, on a senior basis to) the obligations so secured until such time as such
obligations are no longer secured by a Lien; provided, however, in no event will
the Issuers or their Restricted Subsidiaries be permitted at any time to have
Liens securing more than $700 million principal amount of Indebtedness.

            SECTION 4.06. LIMITATION ON DIVIDEND AND OTHER PAYMENT RESTRICTIONS
AFFECTING RESTRICTED SUBSIDIARIES. For so long as any of the Notes are
outstanding, the Issuers shall not, and shall not permit any of their Restricted
Subsidiaries to, create or otherwise cause or suffer to exist or become
effective any consensual

                                       32
<PAGE>   40
encumbrance or restriction of any kind on the ability of any Restricted
Subsidiary to: (1) pay dividends or make any other distributions to the Issuers
or any of their Restricted Subsidiaries on any Capital Stock or with respect to
any other interest or participation in, or measured by, profits; (2) pay any
Indebtedness owed to the Issuers or any of their Restricted Subsidiaries; (3)
make loans or advances to the Issuers or any Restricted Subsidiary; or (4)
transfer any property or assets of a Restricted Subsidiary to the Issuers or any
Restricted Subsidiary.

            The foregoing provisions shall not restrict any encumbrances or
restrictions: (a) contained in the terms of any Indebtedness or any agreement
pursuant to which such Indebtedness was issued if the encumbrance or restriction
applies only in the event of a payment default or default with respect to a
financial covenant contained in that Indebtedness or agreement and such
encumbrance or restriction is not materially more disadvantageous to the Holders
than is customary in comparable financings, as determined by each Board of
Directors of the Issuers, in good faith, and such Boards of Directors determine
in good faith that any such encumbrance or restriction is not reasonably likely
to materially affect the Issuers' ability to make principal or interest payments
on the Notes; (b) existing under or by reason of applicable law; (c) existing
with respect to any Person, or the property or assets of that Person, acquired
by the Issuers or any Restricted Subsidiary existing at the time of the
acquisition and not incurred in contemplation of the acquisition, which
encumbrances or restrictions are not applicable to any Person or the property or
assets of any Person other than the acquired Person or the property or assets of
the Person so acquired, provided that, in the case of encumbrances and
restrictions with respect to Acquired Indebtedness, that Indebtedness was
permitted to be incurred under the Indenture and this First Supplemental
Indenture; (d) in the case of clause (4) (and, in case of subparagraph (II)
below to the extent relating to the sale of all of an Issuer's Capital Stock in,
or all or substantially all the assets of, a Restricted Subsidiary, clause (1))
of the first paragraph of this Section 4.06, (I) that restrict in a customary
manner the subletting, assignment or transfer of any property or asset that is,
or is subject to, a lease, purchase mortgage obligation, license, conveyance or
similar agreement or instrument; (II) existing by virtue of any transfer of,
agreement to transfer, option or right with respect to, or Lien on, any of the
property or assets of the Issuers of any Restricted Subsidiary not otherwise
prohibited by the Indenture or this First Supplemental Indenture, or (III)
arising or agreed to in the ordinary course of business, not relating to any
Indebtedness, and that do not, individually or in the aggregate, detract from
the value of the property or assets of the Issuers or of any Restricted
Subsidiary in any manner material to the Issuers or any Restricted Subsidiary;
(e) existing under purchase money obligations that impose restrictions of the
nature described in clause (4) above on the property so acquired; (f) existing
under Permitted Refinancing Indebtedness, provided that the restrictions
contained in the agreements governing the Permitted Refinancing Indebtedness are
no more restrictive than those contained in the agreements governing the
Indebtedness being refinanced; or (g) provisions in joint venture and other
similar agreements entered into in the ordinary course of business that prohibit
actions of the type described in clauses (1), (3) or (4) above unless the joint
venture or similar entity satisfies net worth or other operating or

                                       33
<PAGE>   41
financial performance standards customary in these types of agreements, as
determined by each Board of Directors of the Issuers in good faith.

            Nothing contained in this Section 4.06 will prevent the Issuers or
any Restricted Subsidiary from: (A) creating, incurring, assuming or suffering
to exist any Liens otherwise permitted by Section 4.05 hereof; or (B)
restricting the sale or other disposition of property or assets of the Issuers
or any of their Restricted Subsidiaries that secure Indebtedness of the Issuers
or any of their Restricted Subsidiaries.

            SECTION 4.07. LIMITATION ON SALE OF ASSETS. The Issuers shall not,
and shall not permit any of their Restricted Subsidiaries to, consummate an
Asset Sale, unless (1) the Issuers or such Restricted Subsidiary receive
consideration at the time of the Asset Sale at least equal to the fair market
value of the assets or Equity Interests issued or sold or otherwise disposed of,
as determined in good faith by the Board of Directors of each Issuer, whose
determination will be conclusive, and in each case where the fair market value
is greater than $10.0 million, evidenced by a Board Resolution and set forth in
an Officers' Certificate delivered to the Trustee; and (2) at least 75% of the
consideration received by the Issuers or such Restricted Subsidiary for the
Asset Sale consists of cash or Cash Equivalents; provided, however, that the
amount of:

            (a) any liabilities of (I) the Issuers, as shown on the most recent
      balance sheet, other than contingent liabilities and liabilities that are
      by their terms subordinated to the Notes or (II) any Restricted
      Subsidiaries, as shown on the most recent consolidated balance sheet,
      other than contingent liabilities or liabilities that are by their terms
      subordinated to any guarantees of the Notes, in each case that are assumed
      by the transferee in the Asset Sale pursuant to a customary novation
      agreement that releases the Issuers or such Restricted Subsidiary, as
      applicable, from further liability, and

            (b) any securities, notes or other obligations received by the
      Issuers or such Restricted Subsidiary from the transferee in the Asset
      Sale that are converted into cash or Cash Equivalents within 30 days, to
      the extent of the cash or Cash Equivalents received in that conversion,

shall be treated as cash for purposes of this clause (2).

            The Issuers shall, or shall cause the relevant Restricted Subsidiary
to, within 360 days after the date of receipt of the Net Proceeds from an Asset
Sale, at the option of the Issuers either apply these Net Proceeds (a) to
permanently repay, and reduce the amount permitted to be borrowed under, any of
the Issuers' Indebtedness secured by a Lien or any Indebtedness of one or more
of the Issuers' Restricted Subsidiaries, or (b) acquire a controlling interest
in, or all or substantially all the assets of, another Communications and Data
Access Business, make a capital expenditure in assets used or to be used in a
Communications and Data Access Business or acquire other long-term assets that
are used or are to be used in a Communications and Data Access Business.

                                       34
<PAGE>   42
            Pending the final application of any Net Proceeds from an Asset
Sale, the Issuers may temporarily reduce Indebtedness under any revolving Credit
Facility or otherwise invest those Net Proceeds in any manner that is not
prohibited by the Indenture or this First Supplemental Indenture. Any Net
Proceeds from Asset Sales that are not applied or invested as provided above
will be deemed to constitute "Excess Proceeds." When the aggregate amount of
Excess Proceeds exceeds $10.0 million, the Issuers shall make an offer to all
Holders and holders of any other Indebtedness that ranks equally in right of
payment with the Notes and that requires the Issuers to make such an offer (an
"Asset Sale Offer") to purchase the maximum principal amount or principal amount
at maturity, as applicable, of Notes and other Indebtedness that ranks equally
in right of payment with the Notes that may be purchased out of the Excess
Proceeds, at an offer price in cash in an amount equal to 100% of the principal
amount of the Notes, plus accrued and unpaid interest, if any, to the purchase
date.

            If the aggregate amount of Notes and other Indebtedness ranking
equally with the Notes tendered in an Asset Sale Offer exceeds the amount of
Excess Proceeds, the Holders validly accepting the Asset Sale Offer will be
entitled to receive their pro rata portion of the Excess Proceeds (calculated
for each Holder based on the ratio of the principal amount of the Notes tendered
by such Holder to the total principal amount of Notes, or principal amount at
maturity of all other Indebtedness tendered in respect of such Asset Sale
Offer). Following the completion of an Asset Sale Offer, the amount of Excess
Proceeds remaining, if any, will be deemed to be zero. To the extent that the
aggregate amount of Notes and other Indebtedness tendered in response to an
Asset Sale Offer is less than the Excess Proceeds, the Issuers may use any
remaining Excess Proceeds for any purpose not prohibited by the Indenture and
this First Supplemental Indenture.

            SECTION 4.08. LIMITATION ON TRANSACTIONS WITH AFFILIATES. The
Issuers shall not, and shall not permit any of their Restricted Subsidiaries to,
make any payment to, or sell, lease, transfer or otherwise dispose of any
properties or assets to, or purchase any property or assets from, or enter into
or make or amend any transaction, contract, agreement, understanding, loan,
advance or guarantee with, or for the benefit of, any Affiliate of the Issuers
or any of their Restricted Subsidiaries (each of the foregoing, an "Affiliate
Transaction"), unless

            (1) the Affiliate Transaction is on terms that are no less favorable
      to the Issuers or such Restricted Subsidiary than terms that would have
      been obtained in a comparable transaction by the Issuers or such
      Restricted Subsidiary with an unrelated Person and

            (2) the Issuers deliver to the Trustee (a) with respect to any
      Affiliate Transaction or series of related Affiliate Transactions
      involving aggregate consideration in excess of $5.0 million, a resolution
      of the Board of Directors of each Issuer set forth in an Officers'
      Certificate certifying that the Affiliate Transaction complies with clause
      (1) above and that the Affiliate Transaction has been approved by a
      majority of the disinterested members of each Board of Directors and (b)
      with respect to any Affiliate

                                       35
<PAGE>   43

      Transaction or series of related Affiliate Transactions involving
      aggregate consideration in excess of $15.0 million, an opinion or
      appraisal as to the fairness to the Issuers or such Restricted Subsidiary
      of the Affiliate Transaction from a financial point of view, issued by an
      investment banking firm, appraisal firm or accounting firm, in each case
      of national standing.

            The foregoing limitation does not limit, and will not apply to:

            (I) any employment agreement entered into by the Issuers or any of
      their Restricted Subsidiaries in the ordinary course of business;

            (II) transactions between or among the Issuers and/or their
      Restricted Subsidiaries;

            (III) Restricted Payments that are permitted by Section 4.03 hereof;

            (IV) fees and compensation paid to members of the Boards of
      Directors of the Issuers and their Restricted Subsidiaries in their
      capacity as such, to the extent such fees and compensation are reasonable
      and customary;

            (V) reasonable advances to employees for moving, entertainment and
      travel expenses, and similar expenditures in the ordinary course of
      business;

            (VI) fees and compensation paid to, and indemnity provided on behalf
      of, officers, directors or employees of the Issuers or any of their
      Restricted Subsidiaries, as determined by the Board of Directors of each
      Issuer or of any such Restricted Subsidiary, to the extent those fees and
      compensation are reasonable and customary;

            (VII) the MCI WorldCom Reseller Agreement as in effect on the date
      hereof;

            (VIII) any agreement similar to the MCI WorldCom Reseller Agreement
      entered into with any Affiliate of the Issuers or of their Restricted
      Subsidiaries on terms not more favorable to such party than the terms of
      the MCI WorldCom Reseller Agreement, as in effect immediately before the
      effective time of any such similar agreement;

            (IX) compliance by the Company with its obligations under the
      outstanding Series A1 Preferred Stock and Series A2 Preferred Stock, as
      the same exist on the date hereof;

            (X) the consummation of the Holding Company Reorganization;

            (XI) any sale or other issuance of Equity Interests, other than in
      respect of Disqualified Stock; or

            (XII) commercial, technical and similar agreements or transactions
      related to the provision of services by the Issuers or their Restricted
      Subsidiaries or related to the

                                       36
<PAGE>   44
      acquisition of goods and services by the Issuers or their Restricted
      Subsidiaries, in any case entered into in the ordinary course of business;
      provided, however, that the terms of such agreements or transactions are
      no less favorable to the Issuers than terms that would have been obtained
      in a comparable transaction by the Issuers or their Restricted
      Subsidiaries with an unrelated Person.

            SECTION 4.09. LIMITATION ON SALE AND LEASEBACK TRANSACTIONS. The
Issuers shall not, and shall not permit any of their Restricted Subsidiaries to,
enter into any Sale and Leaseback Transaction; provided, however, that the
Issuers and their Restricted Subsidiaries may enter into a Sale and Leaseback
Transaction if (1) the Issuers or such Restricted Subsidiary could have Incurred
Indebtedness in an amount equal to the Attributable Debt relating to the Sale
and Leaseback Transaction pursuant to Section 4.04 hereof; (2) the gross cash
proceeds of the Sale and Leaseback Transaction are at least equal to the fair
market value, as determined in good faith by the Board of Directors of each
Issuer and set forth in an Officers' Certificate delivered to the Trustee, of
the property that is the subject of the Sale and Leaseback Transaction; and (3)
the transfer of assets in the Sale and Leaseback Transaction is permitted by,
and the Issuers apply the proceeds of the transaction in compliance with,
Section 4.07 hereof.

            SECTION 4.10. LIMITATION ON ISSUANCE OF GUARANTEES OF INDEBTEDNESS
BY RESTRICTED SUBSIDIARIES. The Issuers shall not permit any Restricted
Subsidiary, directly or indirectly, to guarantee, assume or in any other manner
become liable with respect to any of Indebtedness of the Issuers that ranks
equally in right of payment with, or junior in right of payment to the Notes
unless:

            (1) that Restricted Subsidiary simultaneously executes and delivers
      a Supplemental Indenture to the Indenture providing for a guarantee of the
      Notes on terms substantially similar to the guarantee of such
      Indebtedness, along with a notation relating to such guarantee in
      substantially the form of Exhibit E hereto, except that if such
      Indebtedness is by its express terms subordinated in right of payment to
      the Notes, any such assumption, guarantee or other liability of such
      Restricted Subsidiary with respect to such Indebtedness will be
      subordinated in right of payment to such Restricted Subsidiary's
      assumption, guarantee of other liability with respect to the Notes
      substantially to the same extent as such Indebtedness is subordinated to
      the Notes, and

            (2) that Restricted Subsidiary waives, and will not in any manner
      whatsoever claim or take the benefit or advantage of, any rights of
      reimbursement, indemnity or subrogation or any other rights against the
      Issuers or any of their Restricted Subsidiaries as a result of any payment
      by such Restricted Subsidiary under its guarantee.

                                       37
<PAGE>   45
            Notwithstanding the foregoing, any guarantee by a Restricted
Subsidiary may provide by its terms that it will be automatically and
unconditionally released and discharged upon (a) any sale, exchange or transfer,
to any Person not an Affiliate of the Issuers, of all of the Capital Stock of
the Issuers and their Restricted Subsidiaries in, or all or substantially all of
the assets of, such Restricted Subsidiary, which sale, exchange or transfer is
not prohibited by the Indenture or this First Supplemental Indenture; provided,
however, that the Person to which that Capital Stock is sold does not, directly
or indirectly, guarantee, assume or in any other manner become liable with
respect to any Indebtedness of the Issuers as a result of or in connection with
the sale, exchange or transfer, or (b) the release or discharge of the
Indebtedness which resulted in the creation of that guarantee, except a
discharge or release by or as a result of payment under such guarantee.

            SECTION 4.11. LIMITATION ON BUSINESS ACTIVITIES. The Issuers shall
not, and shall not permit any of their Restricted Subsidiaries to, directly or
indirectly, engage in any line of business other than a Communications and Data
Access Business, except to such extent as would not be material to the Issuers
and their Restricted Subsidiaries taken as a whole.

            SECTION 4.12. LIMITATION ON ISSUANCE AND SALE OF EQUITY INTERESTS OF
RESTRICTED SUBSIDIARIES. Other than in connection with the Holding Company
Reorganization, the Issuers shall not sell, transfer, convey or otherwise
dispose of and shall not permit any Restricted Subsidiary, directly or
indirectly, to issue, sell, transfer, convey or otherwise dispose of any Equity
Interests of such Restricted Subsidiary or any other Restricted Subsidiary to
any Person, except:

            (1) to the Issuers or any of their Restricted Subsidiaries;

            (2) issuances of director's qualifying shares or sales to foreign
      nationals of shares of Capital Stock of non-U.S. Restricted Subsidiaries
      to the extent required by law; and

            (3) issuances and sales of Equity Interests in respect of Common
      Stock of Restricted Subsidiaries effected in compliance with Section 4.07
      hereof or in a transaction excluded from the definition of the term "Asset
      Sale"; provided, however, that, if, after giving effect to such issuance
      or sale, that Restricted Subsidiary would cease to be a Subsidiary of the
      Issuers, then the Issuers shall not effect, or permit their Restricted
      Subsidiary, to effect such issuance or sale unless any remaining
      Investment in such Person would have been permitted to be made (and shall
      be treated as a Restricted Investment) under Section 4.03 hereof, with the
      value of such remaining Investment to be determined in the manner
      prescribed by the last sentence of the first paragraph of Section 4.13
      hereof.

            SECTION 4.13. DESIGNATION OF RESTRICTED AND UNRESTRICTED
SUBSIDIARIES. For so long as no Default or Event of Default has occurred and is
continuing, prior to a Holding Company Reorganization and subsequent to a
Holding

                                       38
<PAGE>   46
Company Reorganization described in clause (1) of the definition thereof, the
Board of Directors of the Company, and subsequent to a Holding Company
Reorganization described in clause (2) of the definition thereof, the Board of
Directors of Finance Sub, will be permitted to designate any Restricted
Subsidiary to be an Unrestricted Subsidiary; provided, however, that the Issuers
could incur, immediately after that designation, $1.00 of Indebtedness under the
Consolidated Leverage Ratio test set forth in the first paragraph of Section
4.04 hereof as though such designation had occurred at the beginning of the
Reference Period. In the event that the Issuers designate a Restricted
Subsidiary as an Unrestricted Subsidiary, all outstanding Investments by the
Issuers and their Restricted Subsidiaries, except to the extent repaid in cash,
in the Restricted Subsidiary so designated will be deemed to be an Investment at
the time of the designation and will reduce the amount available for Restricted
Payments under the first paragraph of Section 4.03 hereof or otherwise available
as a Permitted Investment, as applicable. All of these outstanding Investments
will be valued at an amount equal to the greater of:

            (1) the fair market value of those Investments at the time of the
      designation; and

            (2) the original fair market value of those Investments at the time
      they were made.

            The Issuers shall only be permitted to designate a Restricted
Subsidiary as an Unrestricted Subsidiary if the Restricted Payment or an
equivalent Permitted Investment would be permitted at that time and if the
Restricted Subsidiary otherwise would meet the definition of an Unrestricted
Subsidiary.

            Any designation by the Board of Directors of the Company prior to a
Holding Company Reorganization and subsequent to a Holding Company
Reorganization described in clause (1) of the definition thereof, and any
designation by the Board of Directors of Finance Sub subsequent to a Holding
Company Reorganization described in clause (2) of the definition thereof, of a
Restricted Subsidiary as an Unrestricted Subsidiary will be required to be
evidenced by the filing with the Trustee of a certified copy of the Board
Resolution giving effect to the designation and an Officers' Certificate
certifying that the designation complied with the foregoing conditions. If, at
any time, any Unrestricted Subsidiary would fail to meet the definition of an
Unrestricted Subsidiary, it will thereafter cease to be an Unrestricted
Subsidiary for purposes of the Indenture and this First Supplemental Indenture
and any Indebtedness of that Subsidiary will be deemed to be incurred by a
Restricted Subsidiary as of that date and, if the Indebtedness is not permitted
to be Incurred as of that date under Section 4.04 hereof, the Issuers will be in
default of such Section 4.04 hereof.

            Prior to a Holding Company Reorganization and subsequent to a
Holding Company Reorganization described in clause (1) of the definition
thereof, the Board of Directors of the Company, and subsequent to a Holding
Company Reorganization described in clause (2) of the definition thereof, the
Board of Directors of Finance Sub, will be permitted to at any time designate
any Unrestricted Subsidiary to be a Restricted

                                       39
<PAGE>   47
Subsidiary; provided, however, that the designation will be deemed to be an
Incurrence of Indebtedness by a Restricted Subsidiary of any outstanding
Indebtedness of the Unrestricted Subsidiary and the designation will only be
permitted if (a) the Indebtedness is permitted under the first paragraph of
Section 4.04 hereof, and (b) no Default or Event of Default would be in
existence immediately following such designation.

            SECTION 4.14. CHANGE OF CONTROL. Upon the occurrence of a Change of
Control, each Holder will have the right to require the Issuers to repurchase
all or any part of such Holder's Notes pursuant to the Change of Control Offer
described below at a purchase price in cash (the "Change of Control Payment")
equal to 101% of the principal amount of such Notes, plus accrued and unpaid
interest to the Change of Control Payment Date.

            Within 10 days following any Change of Control, the Issuers shall
mail a notice to the Trustee and each Holder describing the transaction or
transactions that constitute the Change of Control and offering to repurchase
the Notes (the "Change of Control Offer") on the date specified in the notice,
which will not be earlier than 30 days or later than 60 days from the date the
notice is mailed (the "Change of Control Payment Date").

            On the Change of Control Payment Date, the Issuers shall, to the
extent lawful: (a) accept for payment Notes or portions thereof properly
tendered and not withdrawn pursuant to the Change of Control Offer; (b) deposit
with the Paying Agent an amount equal to the Change of Control Payment for all
Notes or portions thereof so accepted; and (c) deliver, or cause to be
delivered, to the Trustee, all Notes or portions thereof so accepted together
with an Officers' Certificate specifying the Notes or portions thereof that
accepted for payment.

            The Paying Agent promptly shall mail the Change of Control Payment
due to the Holders accepted for purchase. The Trustee shall promptly
authenticate and mail or cause to be transferred by book entry to the Holders a
new Note equal in principal amount of any unpurchased portion of the Notes
surrendered. In any event, each Note that is purchased and each new Note that
issued will be in a principal amount of $1,000 or integral multiples thereof.
The Issuers shall announce publicly the results of the Change of Control Offer
on or as soon as practicable after the Change of Control Payment Date.

            The Change of Control provisions described in this Section 4.14 will
be applicable whether or not any other provisions of the Indenture and this
First Supplemental Indenture are applicable. Except as described in this Section
4.14, the Indenture and First Supplemental Indenture do not contain provisions
that permit the Holders to require the Issuers to repurchase or redeem the Notes
in the event of a takeover, recapitalization or similar transaction.

                                       40
<PAGE>   48
            The Issuers shall not be required to make a Change of Control Offer
upon a Change of Control if a third party makes the Change of Control Offer in
the manner, at the times and otherwise in compliance with the requirements set
forth in the Indenture and this Supplemental Indenture applicable to a Change of
Control Offer made by the Issuers and purchases all Notes validly tendered and
not withdrawn under that Change of Control Offer.

            The Issuers shall comply with Rule 14e-1 under the Exchange Act and
any other securities laws and regulations to the extent those laws and
regulations are applicable in the event that a Change of Control occurs and the
Issuers are required to offer to repurchase the Notes under this Section 4.14.
In the event of a conflict between complying with applicable laws and the
provisions of the Indenture and this First Supplemental Indenture, the Issuers
shall comply with applicable laws and shall not be deemed to have committed a
Default or Event of Default as a result of so complying.

                                    ARTICLE 5

                                   SUCCESSORS

            SECTION 5.01. MERGER, CONSOLIDATION, OR SALE OF ASSETS. The Issuers
shall not, directly or indirectly, consolidate or merge with or into, whether or
not an Issuer is the surviving corporation, or sell, assign, transfer, convey or
otherwise dispose of all or substantially all of the Issuers' properties or
assets in one or more related transactions, to another Person unless

            (1) an Issuer is the surviving corporation or the Person formed by
      or surviving the consolidation or merger, if other than an Issuer, or to
      which the sale, assignment, transfer, conveyance or other disposition is
      made is organized under the laws of the United States or any state of the
      United States or the District of Columbia, the British Virgin Islands,
      Cayman Islands, The Netherlands, Ireland, Jersey or Luxembourg;

            (2) the Person formed by or surviving the consolidation or merger,
      if other than an Issuer, or the Person to which the sale, assignment,
      transfer, conveyance or other disposition is made assumes all of the
      Issuers' obligations under the Notes and the Indenture and this First
      Supplemental Indenture pursuant to a Supplemental Indenture in a form
      reasonably satisfactory to the Trustee;

            (3) immediately before and after the transaction no Default or Event
      of Default will have occurred;

            (4) in the event that the continuing Person is incorporated in a
      jurisdiction other than under the laws of the United States or any state
      of the United States or the District of Columbia: (a) the Issuers deliver
      to the Trustee an opinion of counsel stating that the obligations of the
      continuing person under the Indenture and this First Supplemental
      Indenture are enforceable under the laws of the new jurisdiction of its
      incorporation to the same extent as the Issuers' obligations under the
      Indenture and

                                       41
<PAGE>   49
      this First Supplemental Indenture immediately prior to the transaction;
      (b) the continuing Person agrees in writing to submit to jurisdiction and
      appoints an agent for the service of process, each under terms
      substantially similar to the terms contained in the Indenture and this
      First Supplemental Indenture with respect to the Issuers; (c) the
      continuing Person agrees in writing to pay Additional Amounts with respect
      to any withholding tax imposed by the country of the continuing Person's
      organization or any political subdivision thereof, and such Additional
      Amounts will relate to any withholding tax whatsoever regardless of any
      change of law, subject to exceptions set forth below under Section 5.03
      hereof; and (d) prior to a Holding Company Reorganization and subsequent
      to a Holding Company Reorganization described in clause (1) of the
      definition thereof, subsequent to a Holding Company Reorganization
      described in clause (2) of the definition thereof, the Board of Directors
      of the Company, determines in good faith that the transaction is not
      reasonably likely to have a material adverse effect on the Holders and a
      Board Resolution to that effect is delivered to the Trustee; and

            (5) except in the case of the Holding Company Reorganization, an
      Issuer or the Person formed by or surviving the consolidation or merger,
      if other than an Issuer, or to which the Issuers sell, assign, transfer,
      convey or otherwise dispose of all or substantially all their properties
      or assets, will, immediately after the transaction after giving pro forma
      effect to the transaction and any related financing transactions as if the
      same had occurred at the beginning of the applicable Reference Period, be
      permitted to incur at least $1.00 of additional Indebtedness pursuant to
      the Consolidated Leverage Ratio test set forth in the first paragraph of
      Section 4.04 hereof.

            In addition, the Issuers shall not, directly or indirectly, lease
all or substantially all of their properties or assets, in one or more related
transactions, to any other Person.

            Notwithstanding the foregoing provisions, nothing in this Section
5.01 shall prohibit the Issuers from completing the Holding Company
Reorganization, provided that the completion of that transaction is solely for
the purpose of effecting the Holding Company Reorganization and not for the
purpose of circumventing any other provision of the Indenture or this First
Supplemental Indenture.

            SECTION 5.02. SUCCESSOR CORPORATION SUBSTITUTED. Upon any
consolidation or merger, or any sale, assignment, transfer, conveyance or other
disposition of all or substantially all of the Issuers' assets in accordance
with the foregoing provisions in which an Issuer is not the continuing obligor
under the Notes and the Indenture and First Supplemental Indenture, the
surviving entity will succeed to, and be substituted for, and may exercise every
right and power of, the Issuers under the Notes, Indenture and the First
Supplemental Indenture with the same effect as if that successor had been named
as an Issuer in the Notes, Indenture and First Supplemental Indenture. When a
successor assumes all the obligations of its predecessor under the

                                       42
<PAGE>   50
Notes, Indenture and First Supplemental Indenture, the predecessor will be
released from those obligations.

            SECTION 5.03. ADDITIONAL AMOUNTS. The Issuers shall pay to each
Holder such additional amounts ("Additional Amounts") as may be necessary in
order that every net payment of the principal of and interest on such Holder's
Notes, after deduction or withholding for or on account of any present or future
tax, assessment or governmental charge imposed upon or as a result of such
payment by the country in which the continuing Person is organized or any
political subdivision or taxing authority in that political subdivision or
taxing authority, will not be less than the amount provided for in such Notes,
then due and payable before any such tax, assessment or other governmental
charge; provided, however, that the foregoing obligation to pay Additional
Amounts shall not apply to:

      (a)   any tax, assessment or other governmental charge which would not
            have been so imposed but for:

            (i)   the existence of any present or former connection between such
                  Holder (or between a fiduciary, settler, beneficiary, member,
                  partner or shareholder of, or possessor of a power over, such
                  Holder, if such Holder is an estate, trust, partnership or
                  corporation) and the country in which the Issuers are
                  organized, including, without limitation, such Holder (or such
                  fiduciary, settler, beneficiary, member, partner, shareholder
                  or possessor) being or having been a citizen or resident of
                  the country in which the Issuers are organized or treated as a
                  resident thereof, or being or having been engaged in trade or
                  business or present therein, or having or having had a
                  permanent establishment therein or making or having made an
                  election the effect of which is to subject such Holder or
                  beneficial owner (or such fiduciary, settler, beneficiary,
                  member, partner, shareholder or possessor) to such tax
                  assessment or other governmental charge;

            (ii)  the failure of such Holder or beneficial owner of a Note to
                  comply with any requirement under income tax treaties,
                  statutes and regulations or administrative practice of the
                  country in which the Issuers are organized, to establish
                  entitlement to exemption from or reduction of such tax,
                  assessment or other governmental charge; or

            (iii) such Holder's present or former status as a personal holding
                  company or foreign personal holding company with respect to
                  the United States, a controlled foreign corporation or a
                  passive foreign investment company for United States tax
                  purposes or a corporation that accumulates earnings to avoid
                  United States federal income tax;

      (b)   any tax, assessment or other governmental charge which would not
            been so imposed but for the presentation by the Holder of such Note
            for payment on a date

                                       43
<PAGE>   51

            more than 10 days after the date on which such payment becomes due
            and payable or a date on which payment thereof is duly provided for
            and notice is given to Holders, whichever occurs later;

      (c)   any estate, inheritance, gift, sales, transfer, personal property or
            similar tax, assessment or governmental charge;

      (d)   any tax, assessment or other governmental charge which is payable
            otherwise than by deduction or withholding from payments of
            principal of or interest on such Note;

      (e)   any tax, assessment or other governmental charge which is payable by
            a Holder that is not the beneficial owner of the Note, or a portion
            of the Note, or that is a foreign or fiduciary partnership, but only
            to the extent that a beneficial owner, settler with respect to such
            fiduciary or member of the partnership would not have been entitled
            to the payment of an Additional Amount had the beneficial owner or
            member received directly its beneficial or distributive share of the
            payment;

      (f)   any tax, assessment or other governmental charge required to be
            withheld by any Paying Agent from any payment of the principal of or
            interest on any Note, if such payment can be made without such
            withholding by any other paying agent; or

      (g)   any combination of items (a) through (f) above.

            For the purposes of the foregoing, the holding of or the receipt of
any payment with respect to a Note will not constitute a connection between the
Holder (or between a fiduciary, settler, beneficiary, member, partner or
shareholder of, or a person having a power over, such Holder if such Holder is
an estate, a trust, a partnership or a corporation) and the country in which the
Issuers are organized.

            Except as specifically provided herein, the Issuers shall not be
required to make any payment with respect to any tax, assessment or other
governmental charge imposed by any government or any political subdivision or
taxing authority thereof or therein.

            References in the Indenture and this First Supplemental Indenture to
principal and/or interest shall be deemed also to refer to any Additional
Amounts which may be payable under this provision.

                                    ARTICLE 6

                              DEFAULTS AND REMEDIES

                                       44
<PAGE>   52
            SECTION 6.01. EVENTS OF DEFAULT. Each of the following shall
constitute an "Event of Default" for purposes of the Indenture and this First
Supplemental Indenture:

            (1) default in the payment of interest on the Notes when due and
      payable and, other than with respect to the first four scheduled interest
      payments on the Notes, continuance of such default for a period of 30
      days;

            (2) default in the performance of any covenant set forth in the
      Pledge Agreement, or repudiation by the Issuers of any of their
      obligations under the Pledge Agreement or the unenforceability of the
      Pledge Agreement against the Issuers for any reason which in any one case
      or in the aggregate results in a material impairment of the rights
      intended to be afforded thereby;

            (3) default when due in the payment of principal of, or premium, if
      any, on any Note;

            (4) failure by the Issuers or any of their Restricted Subsidiaries
      for 30 days after written notice to them by the Trustee or by the Holders
      of at least 25% in aggregate principal amount of the outstanding Notes to
      comply with the provisions of Section 4.03, 4.04, 4.07 or 4.14 hereof;

            (5) failure by the Issuers or any of their Restricted Subsidiaries
      to perform or comply with the provisions of Section 5.01 hereof or of the
      Indenture;

            (6) failure by the Issuers or any of their Restricted Subsidiaries
      for 60 days after written notice to them by the Trustee or by the Holders
      of at least 25% in aggregate principal amount of the outstanding Notes to
      comply with any other covenant set forth in the Notes, Indenture or this
      First Supplemental Indenture;

            (7) default under any mortgage, indenture or instrument under which
      there may be issued or by which there may be secured or evidenced any
      Indebtedness for money borrowed by the Issuers or any of their Significant
      Subsidiaries (or group of Restricted Subsidiaries that if treated as a
      single subsidiary would constitute a Significant Subsidiary), or the
      payment of which is guaranteed by the Issuers or any of their Significant
      Subsidiaries (or group of Restricted Subsidiaries that if treated as a
      single subsidiary would constitute a Significant Subsidiary), whether that
      Indebtedness or guarantee now exists or is created after the date hereof,
      which default (a) is caused by a failure to pay principal of or premium,
      if any, or interest on that Indebtedness prior to the expiration of the
      grace period provided in that Indebtedness on the date of such default (a
      "Payment Default") or (b) results in the acceleration of that Indebtedness
      prior to its express maturity, and, in each case, if the principal amount
      of any such Indebtedness, together with the principal amount of any other
      such Indebtedness under which there has been a Payment Default or the
      maturity of which has been so accelerated, aggregates $10.0 million or
      more;

                                       45
<PAGE>   53
            (8) failure by the Issuers or any of their Significant Subsidiaries
      (or group of Restricted Subsidiaries that if treated as a single
      subsidiary would constitute a Significant Subsidiary) to pay final
      judgments aggregating in excess of $10.0 million, excluding amounts
      covered by insurance, which judgments are not paid, discharged or stayed
      for a period of 60 days after the date on which the right to appeal has
      expired.

            (9) an Issuer or any Significant Subsidiaries of an Issuer (or group
      of Restricted Subsidiaries that if treated as a single subsidiary would
      constitute a Significant Subsidiary):

            (a) commences a voluntary case under any Bankruptcy Law;

            (b) consents to the entry of an order for relief against it in an
            involuntary case under any Bankruptcy Law now or hereafter in
            effect;

            (c) consents to the appointment of or taking possession by a
            receiver, liquidator, assignee, custodian, trustee, sequestrator or
            similar official of an Issuer or any Significant Subsidiary of an
            Issuer (or group of Restricted Subsidiaries that if treated as a
            single Subsidiary would constitute a Significant Subsidiary) or for
            all or substantially all of the property and assets of an Issuer or
            any of its Significant Subsidiaries (or group of Restricted
            Subsidiaries that if treated as a single Subsidiary would constitute
            a Significant Subsidiary); or

            (d) effects a general assignment for the benefit of its creditors;
            or

            (10) a court of competent jurisdiction enters an order or decree
      under any Bankruptcy Law for:

            (a) relief in respect of an Issuer or any Significant Subsidiary of
            an Issuer (or group of Restricted Subsidiaries that, taken as a
            whole, would constitute a Significant Subsidiary) in an involuntary
            case under any Bankruptcy Law now or hereafter in effect;

            (b) appointment of a receiver, liquidator, assignee, custodian,
            trustee, sequestrator or similar official of an Issuer or any
            Significant Subsidiary of an Issuer (or group of Subsidiaries that
            if treated as a single subsidiary would constitute a Significant
            Subsidiary) or for all or substantially all of the property and
            assets of an Issuer or any Significant Subsidiary (or group of
            Restricted Subsidiaries that if treated as a single subsidiary would
            constitute a Significant Subsidiary); or

            (c) the winding up or liquidation of the affairs of an Issuer or any
            Significant Subsidiary (or group of Restricted Subsidiaries that,
            taken as a whole, would constitute a Significant Subsidiary);

                                       46
<PAGE>   54
and, in each case, the order or decree remains unstayed and in effect for a
period of 60 consecutive days.

            SECTION 6.02. ACCELERATION. If an Event of Default, other than an
Event of Default specified in clause (9) or (10) above, occurs and is
continuing, the Trustee or the Holders of at least 25% in aggregate principal
amount of the Notes then outstanding, by written notice to the Issuers, and to
the Trustee if such notice is given by the Holders, may, and the Trustee at the
request of such Holders shall, declare, the principal of, premium, if any, and
accrued but unpaid interest on the Notes to be immediately due and payable. Upon
a declaration of acceleration, such principal, premium, if any, and accrued and
unpaid interest will be immediately due and payable. In the event of a
declaration of acceleration because an Event of Default set forth in clause (7)
above has occurred and is continuing, such declaration of acceleration will be
automatically rescinded and annulled if the Indebtedness that is the subject of
such Event of Default has been discharged or the holders thereof have rescinded
their declaration of acceleration in respect of such Indebtedness, and written
notice of such discharge or rescission, as the case may be, shall have been
given to the Trustee by the Issuers and countersigned by the holders of such
Indebtedness or a trustee, fiduciary or agent for such holders, within 60 days
after such declaration of acceleration in respect of the Notes, and no other
Event of Default has occurred during such 60-day period which has not been cured
or waived during such period. If an Event of Default specified in clause (9) or
(10) above occurs, the principal of, premium, if any, and accrued and unpaid
interest on the Notes then outstanding will ipso facto become and be immediately
due and payable without any declaration or other act on the part of the Trustee
or any Holder. The Holders of at least a majority in principal amount of the
outstanding Notes as to which the acceleration has occurred, by written notice
to the Issuers and to the Trustee, may waive all past defaults and rescind and
annul a declaration of acceleration and its consequences if, among other things,
(1) all existing Events of Default, other than the nonpayment of the principal
of, premium, if any, and accrued and unpaid interest on the Notes that have
become due solely by such declaration of acceleration, have been cured or waived
and (2) the rescission, in the opinion of counsel, would not conflict with any
judgment or decree of a court of competent jurisdiction.

            Notwithstanding the foregoing, the Trustee shall have no obligation
to accelerate the Notes if in the best judgment of the Trustee acceleration is
not in the best interest of the Holders.

                                    ARTICLE 7

                                INTEREST RESERVE

            SECTION 7.01. INTEREST RESERVE; SECURITY. The due and punctual
payment of the principal of, premium, if any, and interest on the Notes when and
as the

                                       47
<PAGE>   55
same shall be due and payable, whether on an interest payment date, at maturity,
by acceleration, repurchase, redemption or otherwise, and interest on the
overdue principal of, premium, if any, and interest on the Notes and performance
of all other obligations of the Issuers and any Guarantors to the Holders of
Notes or the Trustee under the Indenture, this First Supplemental Indenture, the
Notes and the Note Guarantees, according to the terms hereunder or thereunder,
shall be secured by the Pledged Securities, as provided in the Pledge Agreement
which the Issuers and the Guarantor have entered into simultaneously with the
execution of this First Supplemental Indenture for the benefit of the Holders of
Notes. Each Holder of Notes, by its acceptance thereof, consents and agrees to
the terms of the Pledge Agreement as the same may be in effect or may be amended
from time to time in accordance with its terms and authorizes and directs the
Trustee to enter into the Pledge Agreement and to perform its obligations and
exercise its rights thereunder in accordance therewith. The Issuers and the
Guarantor shall deliver to the Trustee copies of all documents executed pursuant
to the Indenture, this First Supplemental Indenture and the Pledge Agreement and
shall do or cause to be done all such acts and things as may be necessary or
proper, or as may be required by the provisions of the Pledge Agreement to
assure and confirm to the Trustee the security interest in the Pledged
Securities contemplated hereby, by the Pledge Agreement, or any part thereof, as
from time to time constituted, so as to render the same available for the
security and benefit of this First Supplemental Indenture and of the Notes and
the Note Guarantees secured hereby, according to the intent and purposes herein
and therein expressed. The Issuers shall take, or shall cause their Restricted
Subsidiaries to take, upon request of the Trustee, any and all actions
reasonably required to cause the Pledge Agreement to create and maintain, as
security for the obligations of the Issuers hereunder, a valid and enforceable
perfected Lien on the Pledged Securities, subject to Liens permitted by the
Pledge Agreement.

            SECTION 7.02. RECORDING AND OPINIONS. The Issuers and the Guarantor
will cause the Pledge Agreement and any financing statements, and all amendments
or supplements to each of the foregoing and any other similar security documents
as necessary, to be registered, recorded and filed and/or re-recorded, re-filed
and renewed in such manner and in such place or places, if any, as may be
required by law in order fully to preserve and protect the Lien securing the
obligations under the Notes and the Note Guarantees pursuant to the Pledge
Agreement.

            The Issuers and any other obligor shall furnish to the Trustee:

            (a) promptly after the execution and delivery of this First
Supplemental Indenture, and promptly after the execution and delivery of any
other instrument of further assurance or amendment, an Opinion of Counsel in the
United States either (i) stating that, subject to customary assumptions and
exclusions, in the opinion of such counsel, the Indenture, this First
Supplemental Indenture, the Pledge Agreement and all other instruments of
further assurance or amendment have been properly recorded, registered and filed
to the extent necessary to make effective the Liens intended to be created by
the Pledge Agreement and reciting the details of such action or

                                       48
<PAGE>   56
referring to prior Opinions of Counsel in which such details are given or (ii)
stating that, subject to customary assumptions and exclusions, in the opinion of
such counsel, no such action is necessary to make any other Lien created under
any of the Pledge Agreement effective as intended by such Pledge Agreement; and

            (b) within 30 days after February 15, in each year beginning with
the year 2001 and ending on the date on which the fourth scheduled interest
payment is made, an Opinion of Counsel, dated as of such date, either (i)
stating that, subject to customary assumptions and exclusions, in the opinion of
such counsel, such action has been taken with respect to the recording,
registering, filing, re-recording, re-registering and re-filing of the
Indenture, this First Supplemental Indenture and all supplemental indentures,
financing statements, continuation statements or other instruments of further
assurance as is necessary to maintain the Lien of this First Supplemental
Indenture and the Pledge Agreement until the next Opinion of Counsel is required
to be rendered pursuant to this paragraph and reciting the details of such
action or referring to prior Opinions of Counsel in which such details are given
or (ii) stating that, subject to customary assumptions and exclusions, in the
opinion of such counsel, no such action is necessary to maintain such Lien,
until the next Opinion of Counsel, if any, is required to be rendered pursuant
to this paragraph.

            (c) The Issuers shall furnish to the Trustee the certificates or
opinions, as the case may be, required by TIA Section 314(d). Such certificates
or opinions will be subject to the terms of TIA Section 314(e).

            SECTION 7.03. RELEASE OF THE PLEDGED SECURITIES.

            (a) Subject to subsections (b), (c) and (d) of this Section 7.03,
Pledged Securities may be released from the Lien and security interest created
by the Indenture, this First Supplemental Indenture and the Pledge Agreement at
any time or from time to time upon the request of the Issuers pursuant to an
Officers' Certificate certifying that all terms for release and conditions
precedent hereunder and under the Pledge Agreement have been met and specifying
(i) the identity of the Pledged Securities to be released and (ii) the provision
of this First Supplemental Indenture which authorizes such release. The Trustee
shall release (at the sole cost and expense of the Issuers) (i) all Pledged
Securities (except as provided in Article 8 of the Indenture and, in particular,
the funds in the trust fund described in Section 8.04 thereof) upon discharge or
defeasance of this First Supplemental Indenture in accordance with Article 8
thereof; (ii) all Pledged Securities upon the payment in full of all obligations
of the Issuers with respect to the Notes; and (iii) Pledged Securities that are
expressly required to be released by the Pledge agreement. Upon receipt of such
Officers' Certificate the Trustee shall execute, deliver or acknowledge any
necessary or proper instruments of termination, satisfaction or release to
evidence the release of any Pledged Securities permitted to be released pursuant
to this First Supplemental Indenture or the Pledge Agreement. The Trustee is
hereby authorized and shall, from time to time upon request of the Issuers,
execute and deliver UCC-3 partial release or termination statements and such
other documents

                                       49
<PAGE>   57
evidencing release of Pledged Securities available for release pursuant to
clauses (i) through (iii) above.

            (b) Except pursuant to Section 7.03(a), no Pledged Securities shall
be released from the Lien and security interest created by the Pledge Agreement
pursuant to the provisions of the Pledge Agreement unless there shall have been
delivered to the Trustee the certificate required by this Section 7.03.

            (c) The Trustee may release Pledged Securities from the Lien and
security interest created by the Indenture, this First Supplemental Indenture
and the Pledge Agreement upon the sale or disposition of Pledged Securities
pursuant to the Trustee's powers, rights and duties with respect to remedies
provided under the Pledge Agreement.

            (d) The release of any Pledged Securities from the terms of the
Indenture, this First Supplemental Indenture and the Pledge Agreement shall not
be deemed to impair the security under this First Supplemental Indenture in
contravention of the provisions hereof if and to the extent the Pledged
Securities are released pursuant to the terms hereof. To the extent applicable,
the Issuers shall cause TIA Section 313(b), relating to reports, and TIA Section
314(d), relating to the release of property or securities from the Lien and
security interest of the Pledge Agreement and relating to the substitution
therefor of any property or securities to be subjected to the Lien and security
interest of the Pledge Agreement to be satisfied. Any certificate or opinion
required by TIA Section 314(d) may be made by an Officer of each Issuer except
in cases where TIA Section 314(d) requires that such certificate or opinion be
made by an independent Person, which Person shall be an independent engineer,
appraiser or other expert selected or approved by the Trustee in the exercise of
reasonable care.

            SECTION 7.04. CERTIFICATES OF THE ISSUERS. The Issuers shall furnish
to the Trustee, prior to each proposed release of Pledged Securities pursuant to
the Pledge Agreement (i) all documents required by TIA Section 314(d) and (ii)
an Opinion of Counsel in the United States, which may be rendered by internal
counsel to the Company, to the effect that, subject to customary assumptions and
exclusions, such accompanying documents constitute all documents required by TIA
Section 314(d). The Trustee may, to the extent permitted by Sections 7.01 and
7.02 of the Indenture, accept as conclusive evidence of compliance with the
foregoing provisions the appropriate statements contained in such documents and
such Opinion of Counsel.

            SECTION 7.05. AUTHORIZATION OF ACTIONS TO BE TAKEN BY THE TRUSTEE
UNDER THE PLEDGE AGREEMENT. Subject to the provisions of Section 7.01 and 7.02
of the Indenture, the Trustee may, in its sole discretion and without the
consent of the Holders of Notes, on behalf of the Holders of Notes, take all
actions it deems necessary or appropriate in order to (a) enforce any of the
terms of the Pledge Agreement and (b) collect and receive any and all amounts
payable in respect of the Obligations of the Issuers hereunder, including but
not limited to the appointment and approval of collateral

                                       50
<PAGE>   58
agents and the appointment and approval of an insurance trustee. The Trustee
shall have power to institute and maintain such suits and proceedings as it may
deem expedient to prevent any impairment of the Pledged Securities by any acts
that may be unlawful or in violation of the Pledge Agreement or this Indenture,
and such suits and proceedings as the Trustee may deem expedient to preserve or
protect its interests and the interests of the Holders of Notes in the Pledged
Securities (including power to institute and maintain suits or proceedings to
restrain the enforcement of or compliance with any legislative or other
governmental enactment, rule or order that may be unconstitutional or otherwise
invalid if the enforcement of, or compliance with, such enactment, rule or order
would impair the security interest hereunder or be prejudicial to the interests
of the Holders of Notes or of the Trustee).

            SECTION 7.06. TRUSTEE'S DUTIES. The powers and duties conferred upon
the Trustee by this Article 7 are solely to protect the Pledged Securities and
shall not impose any duty upon the Trustee to exercise any such powers and
duties, except as expressly provided in this First Supplemental Indenture. The
Trustee shall be under no duty to either Issuer or any Guarantor whatsoever to
make or give any presentment, demand for performance, notice or nonperformance,
protest, notice of protest, notice of dishonor, or other notice or demand in
connection with any Pledged Securities, or to take any steps necessary to
preserve this First Supplemental Indenture. The Trustee shall not be liable to
either Issuer or any Guarantor for failure to collect or realize upon any or all
of the Pledged Securities, or for any delay in doing so, nor shall the Trustee
be under any duty to either Issuer or any Guarantor to take any action
whatsoever with regard thereto. The Trustee shall have no duty to either Issuer,
the Guarantor or any Holder to comply with any recording, filing or other legal
requirements necessary to establish or maintain the validity, priority or
enforceability of the Liens in, or the Trustee's rights in or to, any of the
Pledged Securities.

            SECTION 7.07. AUTHORIZATION OF RECEIPT OF FUNDS BY THE TRUSTEE UNDER
THE PLEDGE AGREEMENT. Upon an Event of Default and so long as such Event of
Default continues, the Trustee may exercise in respect of the Pledged
Securities, in addition to the other rights and remedies provided for herein, in
the Pledge Agreement or otherwise available to it, all of the rights and
remedies of a secured party under the Uniform Commercial Code or other
applicable law, and the Trustee may also upon obtaining possession of the
Pledged Securities as set forth herein, without notice to the Issuers, except as
specified below, sell the Pledged Securities or any part thereof in one or more
parcels at public or private sale, at any exchange, broker's board or at any of
the Trustee's offices or elsewhere, for cash, on credit or for future delivery,
and upon such other terms as the Trustee may deem commercially reasonable. The
Issuers acknowledge and agree that any such private sale may result in prices
and other terms less favorable to the seller than if such a sale were a public
sale. The Issuers agree that, to the extent notice of sale shall be required by
law, at least 10 days' notice to the Issuers of the time and place of any public
sale or the time after which any private sale is to be made shall constitute
reasonable notification. The Trustee shall not be obligated to make any sale
regardless of notice of sale having been given. The Trustee may adjourn any
public or

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<PAGE>   59
private sale from time to time by announcement at the time and place fixed
therefor, and such sale may, without further notice, be made at the time and
place to which it was so adjourned.

        Any cash that is Pledged Securities held by the Trustee and all cash
proceeds received by the Trustee in respect of any sale of, collection from, or
other realization upon all or any part of the Pledged Securities shall be
applied (unless otherwise provided for in the Pledge Agreement and after payment
of any and all amounts payable to the Trustee pursuant to this Indenture), as
the Trustee shall determine or as the Holders of the Notes shall direct pursuant
to Section 6.05 of the Indenture, (i) against the obligations for the ratable
benefit of the Holders of the Notes, (ii) to maintain, repair or otherwise
protect the Pledged Securities or (iii) to take such other action to protect the
other rights of the Holders of the Notes or to take any other appropriate action
or remedy for the benefit of the Holders of the Notes. Any surplus of such cash
or cash proceeds held by the Trustee and remaining after payment in full of all
the obligations shall be paid over to the Issuers or to whomsoever may be
lawfully entitled to receive such surplus or as a court of competent
jurisdiction may direct.

            SECTION 7.08. TERMINATION OF SECURITY INTEREST. Upon the payment in
full of all interest payable on the first four scheduled interest payment dates,
the Trustee shall (at the request of the Issuers accompanied by (i) an Officers'
Certificate of each of the Issuers to the Trustee stating that such interest
payments have been paid in full, and (ii) instructions from the Issuers to the
Trustee to release the Liens pursuant to this First Supplemental Indenture and
the Pledge Agreement) release the Liens securing the Pledged Securities.

            SECTION 7.09. COOPERATION OF TRUSTEE. In the event the Issuers or
any Guarantor pledge or grant a security interest in additional Pledged
Securities, the Trustee shall cooperate with the Issuers or such Guarantor in
reasonably and promptly agreeing to the form of, and executing as required, any
instruments or documents necessary to make effective the security interest in
the Pledged Securities to be so substituted or pledged. To the extent
practicable, the terms of any security agreement or other instrument or document
necessitated by any such substitution or pledge shall be comparable to the
provisions of the existing Pledge Agreement. Subject to, and in accordance with
the requirements of this Article 7 and the terms of the Pledge Agreement, in the
event that the Issuers or any Guarantor engages in any transaction pursuant to
Section 7.03 hereof, the Trustee shall cooperate with the Issuers or such
Guarantor in order to facilitate such transaction in accordance with any
reasonable time schedule proposed by the Issuers, including by delivering and
releasing the Pledged Securities in a prompt and reasonable manner.

            SECTION 7.10. COLLATERAL AGENT. The Trustee may, from time to time,
appoint one or more Collateral Agents hereunder. Each of such Collateral Agents
may be delegated any one or more of the duties or rights of the Trustee
hereunder or under the Pledge Agreement or one or more Credit Facilities or
which are specified in the Pledge

                                       52
<PAGE>   60
Agreement or such Credit Facilities, including without limitation, the right to
hold any Pledged Securities in the name of, registered to, or in the physical
possession of, such Collateral Agent, for the rateable benefit of the Holders of
the Notes. Each such Collateral Agent shall have such rights and duties as may
be specified in an agreement between the Trustee and such Collateral Agent. The
Trustee and any Collateral Agent shall be authorized hereunder to give any
acknowledgment reasonably requested by any party under one or more Credit
Facilities to confirm the rights and obligations of the parties under such
Credit Facilities.

                                    ARTICLE 8

                                 NOTE GUARANTEES

            SECTION 8.01. GUARANTEES. Subject to this Article 8, each of the
Guarantors hereby, jointly and severally, unconditionally guarantees to each
Holder of a Note authenticated and delivered by the Trustee and to the Trustee
and its successors and assigns, irrespective of the validity and enforceability
of the Indenture, this First Supplemental Indenture, the Notes or the
obligations of the Issuers hereunder or thereunder, that: (a) the principal of
premium, if any, and interest on the Notes will be promptly paid in full when
due, whether at maturity, by acceleration, redemption or otherwise, and interest
on the overdue principal of and interest on the Notes, if any, if lawful, and
all other obligations of the Issuers to the Holders or the Trustee hereunder or
thereunder will be promptly paid in full or performed, all in accordance with
the terms hereof and thereof; and (b) in case of any extension of time of
payment or renewal of any Notes or any of such other obligations, that same will
be promptly paid in full when due or performed in accordance with the terms of
the extension or renewal, whether at stated maturity, by acceleration pursuant
to Section 6.02 hereof or otherwise. Failing payment when due of any amount so
guaranteed or any performance so guaranteed for whatever reason, the Guarantors
shall be jointly and severally obligated to pay the same immediately. Each
Guarantor agrees that this is a guarantee of payment and not a guarantee of
collection.

            Each Guarantor hereby agrees that its obligations with regard to
this Note Guarantee shall be joint and several, unconditional, irrespective of
the validity or enforceability of the Notes or the obligations of the Issuers
under the Indenture, this First Supplemental Indenture, the absence of any
action to enforce the same, the recovery of any judgment against the Issuers or
any other obligor with respect to the Indenture, this First Supplemental
Indenture, the Notes or the obligations of the Issuers under the Indenture, this
First Supplemental Indenture or the Notes, any action to enforce the same or any
other circumstances (other than complete performance) which might otherwise
constitute a legal or equitable discharge or defense of a Guarantor. Each
Guarantor further, to the extent permitted by law, waives and relinquishes all
claims, rights and remedies accorded by applicable law to guarantors and agrees
not to assert or take advantage of any such claims, rights or remedies,
including but not limited to: (a) any right to require any of the Trustee, the
Holders or the Issuers (each a "Benefited Party"),

                                       53
<PAGE>   61
as a condition of payment or performance by such Guarantor, to (1) proceed
against the Issuers, any other guarantor (including any other Guarantor) of the
obligations under the Note Guarantees or any other Person, (2) proceed against
or exhaust any security held from the Issuers, any such other guarantor or any
other Person, (3) proceed against or have resort to any balance of any deposit
account or credit on the books of any Benefited Party in favor of the Issuers or
any other Person, or (4) pursue any other remedy in the power of any Benefited
Party whatsoever; (b) any defense arising by reason of the incapacity, lack of
authority or any disability or other defense of the Issuers including any
defense based on or arising out of the lack of validity or the unenforceability
of the obligations under the Note Guarantees or any agreement or instrument
relating thereto or by reason of the cessation of the liability of the Issuers
from any cause other than payment in full of the obligations under the Note
Guarantees; (c) any defense based upon any statute or rule of law which provides
that the obligation of a surety must be neither larger in amount nor in other
respects more burdensome than that of the principal; (d) any defense based upon
any Benefited Party's errors or omissions in the administration of the
obligations under the Note Guarantees, except behavior which amounts to bad
faith; (e)(1) any principles or provisions of law, statutory or otherwise, which
are or might be in conflict with the terms of the Note Guarantees and any legal
or equitable discharge of such Guarantor's obligations hereunder, (2) the
benefit of any statute of limitations affecting such Guarantor's liability
hereunder or the enforcement hereof, (3) any rights to set-offs, recoupments and
counterclaims and (4) promptness, diligence and any requirement that any
Benefited Party protect, secure, perfect or insure any security interest or lien
or any property subject thereto; (f) notices, demands, presentations, protests,
notices of protest, notices of dishonor and notices of any action or inaction,
including acceptance of the Note Guarantees, notices of default under the Notes
or any agreement or instrument related thereto, notices of any renewal,
extension or modification of the obligations under the Note Guarantees or any
agreement related thereto, and notices of any extension of credit to the Issuers
and any right to consent to any thereof; (g) to the extent permitted under
applicable law, the benefits of any "One Action" rule and (h) any defenses or
benefits that may be derived from or afforded by law which limit the liability
of or exonerate guarantors or sureties, or which may conflict with the terms of
the Note Guarantees. Except as set forth in Section 8.06 hereof, each Guarantor
hereby covenants that its Note Guarantee will not be discharged except by
complete performance of the obligations contained in its Note Guarantee, the
Indenture and this First Supplemental Indenture.

            If any Holder or the Trustee is required by any court or otherwise
to return to the Issuers, the Guarantors or any custodian, trustee, liquidator
or other similar official acting in relation to either the Issuers or the
Guarantors, any amount paid by either to the Trustee or such Holder, this Note
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

            Each Guarantor agrees that it shall not be entitled to any right of
subrogation in relation to the Holders in respect of any obligations guaranteed
hereby until payment in full of all obligations guaranteed hereby. Each
Guarantor further agrees

                                       54
<PAGE>   62
that, as between the Guarantors, on the one hand, and the Holders and the
Trustee, on the other hand, (x) the maturity of the obligations guaranteed
hereby may be accelerated as provided in Section 6.02 hereof for the purposes of
this Note Guarantee, notwithstanding any stay, injunction or other prohibition
preventing such acceleration in respect of the obligations guaranteed hereby and
(y) in the event of any declaration of acceleration of such obligations as
provided in Section 6.02 hereof, such obligations (whether or not due and
payable) shall forthwith become due and payable by the Guarantors for the
purpose of this Note Guarantee. The Guarantors shall have the right to seek
contribution from any non-paying Guarantor so long as the exercise of such right
does not impair the rights of the Holders under the Note Guarantee.

            SECTION 8.02. ADDITIONAL GUARANTEES. If any Restricted Subsidiary
becomes obligated pursuant to Section 4.10 hereof, then the Issuers shall cause
any such Restricted Subsidiary to, within five Business Days of the date on
which any such Restricted Subsidiary became so obligated, (a) execute and
deliver to the Trustee a Supplemental Indenture in form reasonably satisfactory
to the Trustee pursuant to which such Restricted Subsidiary shall
unconditionally guarantee, on a senior unsecured basis, all of the Issuers'
obligations under the Notes, the Indenture and this First Supplemental Indenture
on the terms set forth herein and therein and (b) deliver to the Trustee an
Opinion of Counsel that, subject to customary assumptions and exclusions, such
supplemental indenture has been duly executed and delivered by such Restricted
Subsidiary. Any Restricted Subsidiary that becomes a Guarantor shall remain a
Guarantor unless (i) designated an Unrestricted Subsidiary by the Issuers in
accordance with this First Supplemental Indenture; (ii) is otherwise released
from its obligations as a Guarantor pursuant to Section 8.06 hereof; or (iii)
the circumstances giving rise to the obligation to provide a guarantee under
Section 4.10 hereof no longer exist.

            SECTION 8.03. LIMITATION ON GUARANTOR LIABILITY. Each Guarantor, and
by its acceptance of Notes, each Holder, hereby confirms that it is the
intention of all such parties that the Note Guarantee of such Guarantor not
constitute a fraudulent transfer or conveyance for purposes of Bankruptcy Law,
the Uniform Fraudulent Conveyance Act, the Uniform Fraudulent Transfer Act or
any similar federal or state law to the extent applicable to any Note Guarantee.
To effectuate the foregoing intention, the Trustee, the Holders and the
Guarantors hereby irrevocably agree that the obligations of such Guarantor under
this Article 8 shall be limited to the maximum amount as will, after giving
effect to such maximum amount and all other contingent and fixed liabilities of
such Guarantor that are relevant under such laws, and after giving effect to any
collections from, rights to receive contribution from or payments made by or on
behalf of any other Guarantor in respect of the obligations of such other
Guarantor under this Article 8, result in the obligations of such Guarantor
under its Note Guarantee not constituting a fraudulent transfer or conveyance.

            SECTION 8.04. EXECUTION AND DELIVERY OF NOTE GUARANTEE.

                                       55
<PAGE>   63
            To evidence its Note Guarantee set forth in Section 11.01 hereof,
each Guarantor hereby agrees that a notation of such Note Guarantee
substantially in the form included in Exhibit D shall be endorsed by an Officer
of such Guarantor on each Note authenticated and delivered by the Trustee and
that this Indenture shall be executed on behalf of such Guarantor by its
President or one of its Vice Presidents.

            Each Guarantor hereby agrees that its Note Guarantee set forth in
Section 11.01 hereof shall remain in full force and effect notwithstanding any
failure to endorse on each Note a notation of such Note Guarantee.

            If an Officer whose signature is on this Indenture or on the Note
Guarantee no longer holds that office at the time the Trustee authenticates the
Note on which a Note Guarantee is endorsed, the Note Guarantee shall be valid
nevertheless.

            The delivery of any Note by the Trustee, after the authentication
thereof hereunder, shall constitute due delivery of the Note Guarantee set forth
in this Indenture on behalf of the Guarantors.

            SECTION 8.05. MERGER AND CONSOLIDATION OF GUARANTORS. Except as
otherwise provided in Section 8.06 hereof, no Guarantor may consolidate with or
merge with or into (whether or not such Guarantor is the surviving Person)
another Person whether or not affiliated with such Guarantor unless:

            (a) subject to Section 8.06 hereof, the Person formed by or
surviving any such consolidation or merger (if other than a Guarantor or an
Issuer) unconditionally assumes all the obligations of such Guarantor, pursuant
to a supplemental indenture in form and substance reasonably satisfactory to the
Trustee, under the Notes, the Indenture, this First Supplemental Indenture, and
the Note Guarantee on the terms set forth herein or therein; and

            (b) the Guarantor complies with the requirements of Article 5
hereof.

            In case of any such consolidation, merger, sale or conveyance and
upon the assumption by the successor Person, by supplemental indenture, executed
and delivered to the Trustee and satisfactory in form to the Trustee, of the
Note Guarantee endorsed upon the Notes and the due and punctual performance of
all of the covenants and conditions of this Indenture to be performed by the
Guarantor, such successor Person shall succeed to and be substituted for the
Guarantor with the same effect as if it had been named herein as a Guarantor.
Such successor Person thereupon may cause to be signed any or all of the Note
Guarantees to be endorsed upon all of the Notes issuable hereunder which
theretofore shall not have been signed by the Issuers and delivered to the
Trustee. All the Note Guarantees so issued shall in all respects have the same
legal rank and benefit under the Indenture, this First Supplemental Indenture as
the Note Guarantees theretofore and thereafter issued in accordance with the
terms of the Indenture and this First Supplemental Indenture as though all of
such Note Guarantees had been issued at the date of the execution hereof.

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<PAGE>   64
            Except as set forth in Articles 4 and 5 hereof, and notwithstanding
clauses (a) and (b) above, nothing contained in this Indenture or in any of the
Notes shall prevent any consolidation or merger of a Guarantor with or into an
Issuer or another Guarantor, or shall prevent any sale or conveyance of the
property of a Guarantor as an entirety or substantially as an entirety to an
Issuer or another Guarantor.

            SECTION 8.06. RELEASE. In the event of a sale or other disposition
of all of the assets of any Guarantor, by way of merger, consolidation or
otherwise, or a sale or other disposition of all to the capital stock of any
Guarantor, in each case to a Person that is not (either before or after giving
effect to such transactions) a Restricted Subsidiary of the Issuers, then such
Guarantor (in the event of a sale or other disposition, by way of merger,
consolidation or otherwise, of all of the capital stock of such Guarantor) or
the corporation acquiring the property (in the event of a sale or other
disposition of all or substantially all of the assets of such Guarantor) will be
released and relieved of any obligations under its Note Guarantee; provided,
however, that the Net Proceeds of such sale or other disposition are applied in
accordance with the applicable provisions of this Indenture, including without
limitation Section 4.07 hereof. Upon delivery by the Issuers to the Trustee of
an Officers' Certificate and an Opinion of Counsel to the effect that such sale
or other disposition was made by the Issuers in accordance with the provisions
of the Indenture and this First Supplemental Indenture, including without
limitation Section 4.07 hereof, the Trustee shall execute any documents
reasonably required in order to evidence the release of any Guarantor from its
obligations under its Note Guarantee.

            Any Guarantor not released from its obligations under its Note
Guarantee shall remain liable for the full amount of principal of and interest
on the Notes and for the other obligations of any Guarantor under the Indenture
and this First Supplemental Indenture as provided in this Article 8.

                                  ARTICLE 9

                   LEGAL DEFEASANCE AND COVENANT DEFEASANCE

            SECTION 9.01. OPTION TO EFFECT LEGAL DEFEASANCE OR COVENANT
DEFEASANCE. The Issuers may, at the option of their respective Boards of
Directors evidenced by a resolution set forth in an Officers' Certificate, at
any time, elect to have either Section 9.02 or 9.03 hereof be applied to all
outstanding Notes upon compliance with the conditions set forth below in this
Article Nine. The provisions of this Article 9 shall modify and replace in their
entirety the corresponding provisions of Article 8 of the Indenture.

            SECTION 9.02. LEGAL DEFEASANCE AND DISCHARGE. Upon the Issuers'
exercise under Section 9.01 hereof of the option applicable to this Section 9.02
hereof, the Company shall, subject to the satisfaction of the conditions set
forth in Section 9.04 hereof, be deemed to have been discharged from their
obligations with respect to all

                                       57
<PAGE>   65
outstanding Notes on the date the conditions set forth below are satisfied
(hereinafter, "Legal Defeasance"). For this purpose, Legal Defeasance means that
the Issuers shall be deemed to have paid and discharged the entire Indebtedness
represented by the outstanding Notes, which shall thereafter be deemed to be
"outstanding" only for the purposes of Section 9.05 hereof and the other
Sections of this First Supplemental Indenture referred to in (a) and (b) below,
and to have satisfied all its other obligations under such Notes and this First
Supplemental Indenture (and the Trustee, on demand of and at the expense of the
Issuers, shall execute proper instruments acknowledging the same), except for
the following provisions which shall survive until otherwise terminated or
discharged hereunder: (a) the rights of Holders of outstanding Notes to receive
solely from the trust fund described in Section 9.04 hereof, and as more fully
set forth in such Section, payments in respect of the principal of, premium, if
any, and interest on such Notes when such payments are due, (b) the Issuers'
obligations with respect to such Notes under Article 2 of the Indenture, Article
2 of this First Supplemental Indenture and Section 4.02 of the Indenture, (c)
the rights, powers, trusts, duties and immunities of the Trustee hereunder and
the Issuers' obligations in connection therewith and (d) this Article Nine.
Subject to compliance with this Article Nine, the Issuers may exercise their
option under this Section 9.02 notwithstanding the prior exercise of its option
under Section 9.03 hereof.

            SECTION 9.03. COVENANT DEFEASANCE. Upon the Issuers' exercise under
Section 9.01 hereof of the option applicable to this Section 9.03, the Issuers
shall, subject to the satisfaction of the conditions set forth in Section 9.04
hereof, be released from its obligations under the covenants contained in
Sections 4.01, 4.03, 4.04, 4.05, 4.06, 4.07, 4.08, 4.09, 4.10, 4.11, 4.12, 4.13
and 4.14, hereof, and the operation of Section 5.01(5) hereof, with respect to
the outstanding Notes on and after the date the conditions set forth in Section
9.04 hereof are satisfied (hereinafter, "Covenant Defeasance"), and the Notes
shall thereafter be deemed not "outstanding" for the purposes of any direction,
waiver, consent or declaration or act of Holders (and the consequences of any
thereof) in connection with such covenants, but shall continue to be deemed
"outstanding" for all other purposes hereunder (it being understood that such
Notes shall not be deemed outstanding for accounting purposes). For this
purpose, Covenant Defeasance means that, with respect to the outstanding Notes,
the Issuers may omit to comply with and shall have no liability in respect of
any term, condition or limitation set forth in any such covenant, whether
directly or indirectly, by reason of any reference elsewhere herein to any such
covenant or by reason of any reference in any such covenant to any other
provision herein or in any other document and such omission to comply shall not
constitute a Default or an Event of Default under Section 6.01 hereof, but,
except as specified above, the remainder of this First Supplemental Indenture
and such Notes shall be unaffected thereby. In addition, upon the Issuer's
exercise under Section 9.01 hereof of the option applicable to this Section 9.03
hereof, subject to the satisfaction of the conditions set forth in Section 9.04
hereof, Sections 6.01(4) through 6.01(8) hereof shall not constitute Events of
Default.

                                       58
<PAGE>   66

            SECTION 9.04. CONDITIONS TO LEGAL OR COVENANT DEFEASANCE. The
following shall be the conditions to the application of either Section 9.02 or
9.03 hereof to the outstanding Notes. In order to exercise either Legal
Defeasance or Covenant Defeasance:

      (a) the Issuers must irrevocably deposit with the Trustee, in trust, for
the benefit of the Holders, cash in United States dollars, non-callable
Government Securities, or a combination thereof, in such amounts as shall be
sufficient, in the opinion of a nationally recognized firm of independent public
accountants, to pay the principal of, premium, if any, and interest on the
outstanding Notes on the stated date for payment thereof or on the applicable
redemption date, as the case may be, and the Issuers must specify whether the
Notes are being defeased to maturity or to a particular redemption date;

      (b) in the case of an election under Section 9.02 hereof, the Issuers
shall have delivered to the Trustee an Opinion of Counsel in the United States
reasonably acceptable to the Trustee confirming that (A) the Issuers have
received from, or there has been published by, the Internal Revenue Service a
ruling or (B) since the date of this First Supplemental Indenture, there has
been a change in the applicable federal income tax law, in either case to the
effect that, and based thereon such Opinion of Counsel shall confirm that, the
Holders of the outstanding Notes shall not recognize income, gain or loss for
federal income tax purposes as a result of such Legal Defeasance and shall be
subject to federal income tax on the same amounts, in the same manner and at the
same times as would have been the case if such Legal Defeasance had not
occurred;

      (c) in the case of an election under Section 9.03 hereof, the Issuers
shall have delivered to the Trustee an Opinion of Counsel in the United States
reasonably acceptable to the Trustee confirming that the Holders of the
outstanding Notes shall not recognize income, gain or loss for federal income
tax purposes as a result of such Covenant Defeasance and shall be subject to
federal income tax on the same amounts, in the same manner and at the same times
as would have been the case if such Covenant Defeasance had not occurred;

      (d) no Default or Event of Default shall occur and be continuing on the
date of such deposit, other than a Default or Event of Default resulting from
the borrowing of such funds to be applied to the deposit, or insofar as an Event
of Default shall occur under Sections 6.01(9) or 6.01(10) hereof at any time in
the period ending on the 123rd day after the date of deposit;

      (e) such Legal Defeasance or Covenant Defeasance shall not result in a
breach or violation of, or constitute a default under, any material agreement or
instrument (other than the Indenture and this First Supplemental Indenture) to
which the Issuers or any of their Restricted Subsidiaries is a party or by which
the Issuers or any of their Restricted Subsidiaries are bound;

                                       59
<PAGE>   67
      (f) the Issuers shall have delivered to the Trustee an Opinion of Counsel
(which may be subject to customary exceptions) to the effect that on the 123rd
day following the deposit, the trust funds shall not be subject to the effect of
any applicable bankruptcy, insolvency, reorganization or similar laws affecting
creditors' rights generally;

      (g) the Issuers shall have delivered to the Trustee an Officers'
Certificate stating that the deposit was not made by the Issuers with the intent
of preferring the Holders over any other creditors of the Issuers or with the
intent of defeating, hindering, delaying or defrauding any other creditors of
the Issuers; and

      (h) the Issuers shall have delivered to the Trustee an Officers'
Certificate and an Opinion of Counsel, each stating that all conditions
precedent provided for or relating to the Legal Defeasance or the Covenant
Defeasance have been satisfied.

            SECTION 9.05. DEPOSITED MONEY AND GOVERNMENT SECURITIES TO BE HELD
IN TRUST, OTHER MISCELLANEOUS PROVISIONS.: Subject to Section 9.06 hereof, all
money and non-callable Government Securities (including the proceeds thereof)
deposited with the Trustee (or other qualifying trustee, collectively for
purposes of this Section 9.05, the "Trustee") pursuant to Section 9.04 hereof in
respect of the outstanding Notes shall be held in trust and applied by the
Trustee, in accordance with the provisions of such Notes and this First
Supplemental Indenture, to the payment, either directly or through any Paying
Agent (including the Company acting as Paying Agent) as the Trustee may
determine, to the Holders of such Notes of all sums due and to become due
thereon in respect of principal, premium, if any, and interest, but such money
need not be segregated from other funds except to the extent required by law.

            The Issuers shall pay and indemnify the Trustee against any tax, fee
or other charge imposed on or assessed against the cash or non-callable U.S.
Government Securities deposited pursuant to Section 9.04 hereof or the principal
and interest received in respect thereof other than any such tax, fee or other
charge which by law is for the account of the Holders of the outstanding Notes.

            Anything in this Article Nine to the contrary notwithstanding, the
Trustee shall deliver or pay to the Company from time to time upon the request
of the Company any money or non-callable Government Securities held by it as
provided in Section 9.04 hereof which, in the opinion of a nationally recognized
firm of independent public accountants expressed in a written certification
thereof delivered to the Trustee (which may be the opinion delivered under
Section 9.04(a) hereof), are in excess of the amount thereof that would then be
required to be deposited to effect an equivalent Legal Defeasance or Covenant
Defeasance.

            SECTION 9.06. REPAYMENT TO ISSUERS. Any money deposited with the
Trustee or any Paying Agent, or then held by Issuers, in trust for the payment
of the principal of, premium, if any, or interest on any Note and remaining
unclaimed for

                                       60
<PAGE>   68
two years after such principal, and premium, if any, or interest has become due
and payable shall be paid to the Issuers on its request or (if then held by the
Issuers) shall be discharged from such trust; and the Holder of such Note shall
thereafter, as an unsecured creditor, look only to the Issuers for payment
thereof, and all liability of the Trustee or such Paying Agent with respect to
such trust money, and all liability of the Issuers as trustee thereof, shall
thereupon cease; provided, however, that the Trustee or such Paying Agent,
before being required to make any such repayment, may at the expense of the
Issuers cause to be published once, in The New York Times and The Wall Street
Journal (national edition), notice that such money remains unclaimed and that,
after a date specified therein, which shall not be less than 30 days from the
date of such notification or publication, any unclaimed balance of such money
then remaining shall be repaid to the Issuers.

            SECTION 9.07. REINSTATEMENT. If the Trustee or Paying Agent is
unable to apply any United States dollars or non-callable Government Securities
in accordance with Section 9.02 or 9.03 hereof, as the case may be, by reason of
any order or judgment of any court or governmental authority enjoining,
restraining or otherwise prohibiting such application, then the Issuers'
obligations under this First Supplemental Indenture and the Notes shall be
revived and reinstated as though no deposit had occurred pursuant to Section
9.02 or 9.03 hereof until such time as the Trustee or Paying Agent is permitted
to apply all such money in accordance with Section 9.02 or 9.03 hereof, as the
case may be; provided, however, that, if the Issuers make any payment of
principal of, premium, if any, or interest on any Note following the
reinstatement of its obligations, the Issuers shall be subrogated to the rights
of the Holders of such Notes to receive such payment from the money held by the
Trustee or Paying Agent.

                                   ARTICLE 10

                                  MISCELLANEOUS

            SECTION 10.08. RATIFICATION OF INDENTURE. Except as expressly
supplemented, modified or amended hereby, the Indenture continues in full force
and effect and is in all respects confirmed and preserved.

            SECTION 10.09. GOVERNING LAW. THE INTERNAL LAW OF THE STATE OF NEW
YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS INDENTURE AND THE NOTES WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

            SECTION 10.10. COUNTERPART ORIGINALS. The parties may sign any
number of copies of this First Supplemental Indenture. Each signed copy shall be
an original, but all of them together represent the same agreement.

                         [Signatures on following page]

                                       61
<PAGE>   69
                                   SIGNATURES

Dated as of February 7, 2000

                                        METRICOM, INC.

                                        By:   /s/ Timothy A. Dreisbach
                                              ----------------------------------
                                              Name: Timothy A. Dreisbach
                                              Title: President and CEO

                                        METRICOM FINANCE, INC.

                                        By:   /s/ Timothy A. Dreisbach
                                              ----------------------------------
                                              Name: Timothy A. Dreisbach
                                              Title: President and CEO

                                        BANK ONE TRUST COMPANY, N.A., AS TRUSTEE

                                        By:   /s/ Donna Fanning
                                              ----------------------------------
                                              Name: Donna Fanning

                                       E-1<PAGE>   1
                                                                     EXHIBIT 4.2

                                WARRANT AGREEMENT

                                   Dated as of

                                February 7, 2000

                                     between

                                 METRICOM, INC.

                                       and

                                 BANKBOSTON N.A.

                                as Warrant Agent

                                       and

                          BANK ONE TRUST COMPANY, N.A.

                            as Initial Warrant Agent

                                  Warrants for
                                 Common Stock of
                                 METRICOM, INC.

<PAGE>   2

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                        Page
                                    ARTICLE 1
                                   Definitions
<S>                                                                      <C>
SECTION 1.1. Definitions                                                 1
SECTION 1.2. Other Definitions                                           5

                                    ARTICLE 2
                              Warrant Certificates

SECTION 2.1. Form and Dating                                             6
SECTION 2.2. Legends                                                     8
SECTION 2.3. Execution and Countersignature                             15
SECTION 2.4. Certificate Register                                       16
SECTION 2.5. Separation of Warrants and Notes                           16
SECTION 2.6. Transfer and Exchange                                      16
SECTION 2.7. Replacement Certificates                                   18
SECTION 2.8. Temporary Certificates                                     18
SECTION 2.9. Cancellation                                               18

                                    ARTICLE 3
                                 Exercise Terms

SECTION 3.1. Exercise Price                                             19
SECTION 3.2. Exercise Periods; Restrictions on Exercise                 19
SECTION 3.3. Expiration                                                 19
SECTION 3.4. Manner of Exercise                                         20
SECTION 3.5. Issuance of Warrant Shares                                 20
SECTION 3.6. Fractional Warrant Shares                                  21
SECTION 3.7. Reservation of Warrant Shares                              21
SECTION 3.8. Compliance with Law                                        22

                                    ARTICLE 4
                             Antidilution Provisions

SECTION 4.1. Changes in Common Stock                                    22
SECTION 4.2. Cash Dividends and Other Distributions                     23
SECTION 4.3. Rights Issue to All Holders of Common Stock                23
SECTION 4.4. Other Issuances of Common Stock or Rights                  24
SECTION 4.5. Combination; Liquidation                                   25
SECTION 4.6. Other Events                                               26
</TABLE>

<PAGE>   3

<TABLE>

<S>                                                                      <C>
SECTION 4.7. Superseding Adjustment                                     26
SECTION 4.8. Minimum Adjustment                                         27
SECTION 4.9. Notice of Adjustment                                       27
SECTION 4.10. Notice of Certain Transactions                            28
SECTION 4.11. Adjustment to Warrant Certificate                         28
SECTION 4.12. Exceptions to Antidilution Provisions                     29

                                    ARTICLE 5
                                  Warrant Agent

SECTION 5.1. Appointment of Warrant Agent                               39
SECTION 5.2. Right and Duties of Warrant Agent                          40
SECTION 5.3. Individual Rights of Warrant Agent                         41
SECTION 5.4. Warrant Agent's Disclaimer                                 41
SECTION 5.5. Compensation and Indemnity                                 41
SECTION 5.6. Successor Warrant Agent                                    41

                                    ARTICLE 6
                                  Miscellaneous

SECTION 6.1. Financial Statements and Reports of the Company            44
SECTION 6.2. Third Party Beneficiaries                                  44
SECTION 6.3. Rights of Holders                                          44
SECTION 6.4. Amendment                                                  44
SECTION 6.5. Notices                                                    45
SECTION 6.6. Governing Law                                              46
SECTION 6.7. Successors                                                 46
SECTION 6.8. Multiple Originals                                         46
SECTION 6.9. Table of Contents                                          46
SECTION 6.10. Severability                                              46
</TABLE>

EXHIBIT A    Form of Face of Warrant Certificate

APPENDIX A   List of Financial Experts

<PAGE>   4

            WARRANT AGREEMENT dated as of February 7, 2000 (this "Agreement"),
between METRICOM, INC., a Delaware corporation (the "Company"), BankBoston N.A.,
as Warrant Agent (the "Warrant Agent") and Bank One Trust Company, N.A., as
Initial Warrant Agent (the "Initial Warrant Agent").

            The Company desires to issue the warrants (the "Warrants" and each a
"Warrant") described herein which will initially entitle the holders thereof
(the "Holders") to purchase an aggregate of 1,425,000 shares of its common
stock, par value $0.001 per share (the "Common Stock"), of the Company at a
purchase price of $87.00 per share subject to the adjustments described herein,
in connection with an offering of (i) $300,000,000 aggregate principal amount of
13% Senior Notes due 2010 (collectively, the "Notes" and each $1,000 principal
amount thereof a "Note") issued by the Company and Metricom Finance, Inc., a
Delaware corporation and wholly owned subsidiary of the Company ("Finance Sub"
and together with the Company, the "Issuers"), pursuant to the provisions of the
Indenture (as defined below), and (ii) 300,000 Warrants initially entitling the
Holder to purchase 4.75 shares of Common Stock, subject to adjustment as
provided herein. In connection with the sale of the Notes, each purchaser of a
Note is required to purchase a Warrant, resulting in an aggregate of 300,000
Warrants to be issued to the purchasers of the Notes.

            Each Note will be transferable only along with the corresponding
Warrant forming a unit and will not become separately transferable until the
earliest to occur of (i) August 15, 2000, (ii) an Event of Default, as defined
in the Indenture, (iii) an Exercise Event, as defined herein, or (iv) such other
date, as Lehman Brothers Inc. shall determine in its sole discretion (the
"Separation Date").

            The Company further desires the Warrant Agent to act on behalf of
the Company in connection with the issuance of the Warrants as provided herein
and the Warrant Agent is willing to so act.

            Each party agrees as follows for the benefit of the other party and
for the equal and ratable benefit of the Holders of Warrants:

                                    ARTICLE 1
                                   Definitions

            Any capitalized terms not otherwise defined herein shall have the
meaning attributed such term in the Indenture.

            SECTION 1.1. Definitions.

            "Affiliate" means, as applied to any Person, any other Person
directly or indirectly controlling, controlled by, or under direct or indirect
common control with, such Person. For purposes of this definition, "control" and
correlative meanings, the terms "controlling," "controlled by" and "under common
control with," as applied to any Person, mean the possession,

<PAGE>   5

directly or indirectly, of the power to direct or cause the direction of the
management and policies of such Person, whether through the ownership of voting
securities, by contract or otherwise.

            "Board of Directors" means (1) in respect of a limited liability
company, the board of advisors of that company; (2) in respect of a corporation,
the board of directors of the corporation, or any authorized committee thereof;
and (3) in respect of any other Person, the board or committee of that Person
serving a similar function.

            "Business Day" means any day other than a Legal Holiday.

            "Capital Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents, however designated,
whether voting or non-voting, in equity of such Person, whether now outstanding
or issued after the date hereof, including, without limitation, all Common Stock
and Preferred Stock.

            "Change of Control" means such time as (1) a "person" or "group,"
within the meaning of Sections 13(d) and 14(d)(2) of the Exchange Act, other
than a Permitted Holder, becomes the ultimate "beneficial owner," as defined in
Rule 13d-3 under the Exchange Act, of more than 50% of the total voting power of
the then outstanding Voting Stock of the Company on a fully diluted basis; (2)
individuals who at the beginning of any period of two consecutive calendar years
constituted the Board of Directors of the Company, together with any directors
who are members of such Board of Directors on the date hereof and any new
directors whose election by the Board of Directors or whose nomination for
election by the stockholders of the Company was approved by a vote of at least
two-thirds of the members of the Board of Directors then still in office who
either were members of the Board of Directors at the beginning of such period or
whose election or nomination for election was previously so approved, cease for
any reason to constitute a majority of the members of such Board of Directors
then in office; (3) the sale, lease, transfer, conveyance or other disposition,
other than by way of merger or consolidation, in one or a series of related
transactions, of all or substantially all of the assets of the Company and its
Subsidiaries taken as a whole to any such "person" or "group," other than to a
Permitted Holder or a Restricted Subsidiary of the Company; (4) the merger or
consolidation of the Company with or into another corporation or the merger of
another corporation with or into the Company with the effect that immediately
after such transaction any such "person" or "group" of persons or entities,
other than a Permitted Holder, shall have become the ultimate beneficial owner
of securities of the surviving corporation of such merger or consolidation
representing more than 50% of the total voting power of the then outstanding
Voting Stock of the surviving corporation; or (5) the approval by the holders of
the Capital Stock of the Company of a plan relating to the liquidation or
dissolution of such Issuer. In no event shall the consummation of a Holding
Company Reorganization constitute a Change of Control.

            "Combination" means an event (other than the Holding Company
Reorganization) in which the Company consolidates with, merges with or into, or
sells all or substantially all of its assets to another Person.

<PAGE>   6

            "Current Market Value" per share of Common Stock or any other
security of the Company at any date means: (i) if the security is not of a class
registered under the Exchange Act, (a) the value of the security, determined in
good faith by the Board of Directors and certified in a resolution of the Board
of Directors, based on the most recently completed arm's-length transaction
between the Company and a Person other than an Affiliate of the Company, the
closing of which occurred on such date or within the six-month period preceding
such date, or (b) if no such transaction shall have occurred on such date or
within such six-month period, the value of the security as determined by an
independent Financial Expert; or (ii) if the security is of a class registered
under the Exchange Act, the average of the last reported sale price of the
Common Stock (or the equivalent in an over-the-counter market) for each Business
Day during the period commencing 15 Business Days before such date and ending on
the date one day prior to such date, or if the security of a class registered
under the Exchange Act for less than 15 consecutive Business Days before such
date, the average of the daily closing bid prices (or such equivalent) for all
of the Business Days before such date for which daily closing bid prices are
available (provided, however, that if the closing bid price is not determinable
for at least 10 Business Days in such period, then clause (i) above and not this
clause (ii) shall be used to determine Current Market Value).

            "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

            "Exercise Date" means, for a given Warrant, the day on which such
Warrant is exercised pursuant to Section 3.4.

            "Exercise Event" means, with respect to each Warrant as to which
such event is applicable, the earlier of: (i) a Change of Control and (ii) any
date when the Company (A) consolidates or merges into or with another Person
(but only where holders of Common Stock receive consideration in exchange for
all or part of such Common Stock other than common stock in the surviving
Person) if the Common Stock (or other securities) thereafter issuable upon
exercise of the Warrants will not be registered under the Exchange Act or (B)
sells all or substantially all of its assets to another Person if the Common
Stock (or other securities) thereafter issuable upon exercise of the Warrants
will not be registered under the Exchange Act; provided, that the events in (A)
and (B) will not be deemed to have occurred if the consideration for the Common
Stock in either such transaction consists solely of cash. Notwithstanding
anything herein to the contrary, the consummation of the Holding Company
Reorganization shall not constitute an Exercise Event.

            "Financial Expert" means one of the Persons listed in Appendix A
hereto.

            "Holding Company Reorganization" has the meaning set forth in the
Indenture.

            "Indenture" means the Senior Notes Indenture dated as of December
29, 1999, between the Company and the Trustee, with respect to the Notes, as
supplemented by the First Supplemental Indenture dated as of February 7, 2000,
and as it may be amended or supplemented from time to time.

<PAGE>   7

            "Independent Financial Expert" means a Financial Expert that does
not, and whose directors, executive officers and 5% stockholders do not, have a
direct or indirect financial interest in the Company or any of its subsidiaries
or Affiliates, which has not been for at least five years and, at the time it is
called upon to give independent financial advice to the Company, is not (and
none of its directors, executive officers or 5% stockholders is) a promoter,
director, or officer of the Company or any of its subsidiaries or Affiliates.
The Independent Financial Expert may be compensated and indemnified by the
Company for opinions or services it provides as an Independent Financial Expert.

            "Indirect Participant" means a Person who holds a beneficial
interest in a Global Note through a Participant.

            "Issue Date" means February 7, 2000 or such date on which additional
Notes are originally issued.

            "Legal Holiday" means a Saturday, a Sunday or a day on which banking
institutions in the City of New York or at a place of payment are authorized by
law, regulation or executive order to remain closed. If a payment date is a
Legal Holiday at a place of payment, payment may be made at that place on the
next succeeding day that is not a Legal Holiday, and no interest shall accrue on
such payment for the intervening period.

            "Officer" means the Chairman of the Board of Directors, the
President, any Vice President, the Treasurer, or an Assistant Treasurer, or the
Secretary or an Assistant Secretary of the Company.

            "Participant" means, with respect to DTC or its nominee, an
institution that has an account therewith.

            "Permitted Holder" means either MCI Worldcom, Inc. or Vulcan
Ventures Incorporated, or any majority owned Affiliate thereof.

            "Preferred Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents, however designated,
whether voting or non-voting, of that Person's equity that have a preference as
to the payment of dividends or as to payments upon a liquidation of that Person,
whether now outstanding or issued after the date hereof, including without
limitation, all series and classes of such equity.

            "Person" means any natural person, limited liability company,
corporation, partnership, government, agency or instrumentality of a government,
or any other entity.

            "Restricted Subsidiary" has the meaning set forth in the Indenture.

            "Securities Act" means the Securities Act of 1933, as amended.

<PAGE>   8

            "Trustee" means Bank One Trust Company, N.A., or any successor
trustee under the Indenture.

            "Voting Stock" of any Person as of any date means the Capital Stock
of that Person that is at the time entitled to vote in the election of directors
or similar individuals of that Person.

            "Warrant Certificates" mean the registered certificates (including
without limitation, the global certificates) issued by the Company under this
Agreement representing the Warrants.

            "Warrant Shares" mean the shares of Common Stock (and any other
securities) for which the Warrants are exercisable.

            SECTION 1.2. Other Definitions.
<TABLE>
<CAPTION>

                                                                     Defined in
Term                                                                    Section
-------                                                              ----------
<S>                                                                   <C>
"Agreement"............................................................Recitals
"Cashless Exercise".........................................................3.4
"Certificate Register"......................................................2.4
"Common Stock".........................................................Recitals
"Company"..............................................................Recitals
"Delivering Seller"......................................................5.7(a)
"DTC" or "Depository"....................................................2.2(b)
"Exercise Price"............................................................3.1
"Expiration Date"........................................................3.2(c)
"Finance Sub"..........................................................Recitals
"Global Warrants"...........................................................2.1
"Holders"..............................................................Recitals
"Initial Period"............................................................5.1
"Issuers"..............................................................Recitals
"Notes"................................................................Recitals
"Participants"...........................................................2.6(b)
"Reference Security"...................................................4.12(vi)
"Separability Legend"....................................................2.2(a)
"Separation Date"......................................................Recitals
"Successor Company"......................................................4.5(a)
"Transfer Agent"............................................................3.5
"Warrant Agent"........................................................Recitals
"Warrant" and "Warrants"...............................................Recitals
</TABLE>

            All terms used herein with their initial letters capitalized and not
otherwise defined herein are used herein with the meaning given those terms in
the Indenture.

<PAGE>   9

        SECTION 1.3. Rules of Construction. Unless the text otherwise requires:

                (i) a defined term has the meaning assigned to it;

                (ii) an accounting term not otherwise defined has the meaning
        assigned to it in accordance with generally accepted accounting
        principles as in effect from time to time;

                (iii) "or" is not exclusive;

                (iv) "including" means including without limitation; and

                (v) words in the singular include the plural and words in the
        plural include the singular.

                                    ARTICLE 2

                              Warrant Certificates

            SECTION 2.1. Form and Dating. Each Warrant Certificate shall be
issued in registered form only, substantially in the form of Exhibit A. The
Warrant Certificates may have notations, legends or endorsements required by
law, stock exchange rule, agreements to which the Company is subject, if any, or
usage (including CUSIP numbers) (provided that any such notation, legend or
endorsement is in a form acceptable to the Company) and shall bear the legends
required by Section 2.2. Each Warrant Certificate shall be dated the date of its
countersignature.

            The terms and provisions contained in the form of Warrant annexed
hereto as Exhibit A shall constitute, and are hereby expressly made, a part of
this Warrant Agreement. To the extent applicable, the Company, the Warrant Agent
and the Initial Warrant Agent, by their execution and delivery of this Warrant
Agreement, agree to such terms and provisions and to be bound thereby.

            Warrants offered and sold shall be issued initially in the form of
one or more permanent global Warrant Certificates in registered form,
substantially in the form set forth in Exhibit A (the "Global Warrants"),
registered in the name of the Depositary or the nominee of the Depositary,
deposited with the Initial Warrant Agent, as custodian for the Depositary, duly
executed by the Company and countersigned by the Warrant Agent and the Initial
Warrant Agent as hereinafter provided. The aggregate number of Warrants
represented by the Global Warrant may from time to time be increased or
decreased by adjustments made on the records of the Warrant Agent or the Initial
Warrant Agent, as applicable, as custodian for the Depositary or its nominee, in
accordance with the instructions given by the Holder thereof, as hereinafter
provided.

<PAGE>   10

            Warrants in definitive form may be issued in exchange for interests
in the Global Warrant pursuant to such procedures as the Company and the Warrant
Agent or the Initial Warrant Agent, as applicable, shall reasonably agree upon
and shall be issued in the form of permanent certificated Warrants in registered
form in substantially the form set forth in Exhibit A.

            Ownership of beneficial interests in Global Warrants will be limited
to Participants or Indirect Participants.

            The definitive Warrant Certificates shall be typed, printed,
lithographed or engraved or produced by any combination of these methods or may
be produced in any other manner permitted by the rules of any securities
exchange on which the Warrants may be listed, all as determined by the officers
executing such Warrant Certificates, as evidenced by their execution of such
Warrant Certificates.

            SECTION 2.2. Legends. (a) Each Warrant Certificate issued prior to
the Separation Date shall bear the following legend (the "Separability Legend"):

        UNTIL THE SEPARATION DATE (AS DEFINED), THIS WARRANT HAS BEEN ISSUED AS,
        AND MUST BE TRANSFERRED AS, A UNIT TOGETHER WITH THE ASSOCIATED 13%
        SENIOR NOTES DUE 2010 (THE "NOTES") OF METRICOM, INC. (THE "COMPANY")
        AND METRICOM FINANCE, INC. EACH UNIT CONSISTS OF $1,000 PRINCIPAL AMOUNT
        OF NOTES AND A WARRANT TO PURCHASE 4.75 SHARES OF COMMON STOCK OF THE
        COMPANY, SUBJECT TO ADJUSTMENT UNDER CERTAIN CIRCUMSTANCES. A COPY OF
        THE WARRANT AGREEMENT PURSUANT TO WHICH THE WARRANTS HAVE BEEN ISSUED IS
        AVAILABLE FROM THE COMPANY UPON REQUEST.

        The Company shall give written notice to the Warrant Agent of the
occurrence of the Separation Date.

            (b) Each Global Warrant issued in global form and deposited with DTC
shall bear the following legend:

        UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
        THE DEPOSITORY TRUST COMPANY ("DTC"), TO THE COMPANY OR ITS AGENT FOR
        REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE
        ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS IS
        REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS
        MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
        AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE
        HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH
        AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

<PAGE>   11

        TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN
        WHOLE, BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR
        SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL
        SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE
        RESTRICTIONS SET FORTH IN THE WARRANT AGREEMENT REFERRED TO HEREIN.

            SECTION 2.3. Execution and Countersignature. One Officer shall sign
the Warrant Certificates for the Company by manual or facsimile signature. If an
Officer whose signature is on a Warrant Certificate no longer holds that office
at the time the Warrant Agent or the Initial Warrant Agent, as applicable,
countersigns the Warrant Certificate, the Warrant Certificate shall nevertheless
be valid. A Warrant Certificate shall not be valid until an authorized signatory
of the Warrant Agent or the Initial Warrant Agent, as applicable, manually
countersigns the Warrant Certificate. Such authorized signature shall be
conclusive evidence that the Warrant Certificate has been countersigned under
this Agreement.

            The Warrant Agent or the Initial Warrant Agent, as applicable, shall
initially countersign and deliver Warrant Certificates entitling the Holders
thereof to purchase in the aggregate not more than 4.75 Warrant Shares upon a
written order of the Company signed by one Officer.

            The Warrant Agent or the Initial Warrant Agent, as applicable, may
appoint an agent reasonably acceptable to the Company to countersign the Warrant
Certificates. Unless limited by the terms of such appointment, such agent may
countersign Warrant Certificates whenever the Warrant Agent or the Initial
Warrant Agent, as applicable, may do so. Each reference in this Agreement to
countersignature by the Warrant Agent or the Initial Warrant Agent, includes
countersignature by such agent. Such agent will have the same rights as the
Warrant Agent or the Initial Warrant Agent, as applicable, for service of
notices and demands.

            SECTION 2.4. Certificate Register. The Warrant Agent or the Initial
Warrant Agent, as applicable, shall keep a register ("Certificate Register") of
the Warrant Certificates and of their transfer and exchange. The Certificate
Register shall show the names and addresses of the respective Holders and the
date and number of Warrants represented on the face of each Warrant Certificate.
The Company and the Warrant Agent or the Initial Warrant Agent, as applicable,
may deem and treat the Person in whose name a Warrant Certificate is registered
as the absolute owner of such Warrant Certificate for all purposes whatsoever
and neither the Company nor the Warrant Agent or the Initial Warrant Agent, as
applicable, shall be affected by notice to the contrary.

            SECTION 2.5. Separation of Warrants and Notes. (a) Prior to the
Separation Date no Warrant may be sold, assigned or otherwise transferred to any
Person unless, simultaneously with such transfer, the Initial Warrant Agent
receives confirmation from the Trustee for the Notes that the Holder thereof has
requested a transfer of the related Notes to the same transferee.

<PAGE>   12

            (b) On or after the Separation Date, the holder of a Warrant
Certificate containing a Separability Legend may surrender such Warrant
Certificate accompanied by a written application to the Warrant Agent, duly
executed by the Holder thereof, for a new Warrant Certificate or certificates
not containing the Separability Legend.

            SECTION 2.6. Transfer and Exchange. (a) The Warrant Certificates
shall be issued in registered form only and shall be transferable only upon the
surrender of such Warrant Certificate for registration of transfer. When a
Warrant Certificate is presented to the Warrant Agent or the Initial Warrant
Agent, as applicable, with a request to register a transfer, the Warrant Agent
or the Initial Warrant Agent, as applicable, shall register the transfer as
requested if the reasonable requirements of the Warrant Agent, or the Initial
Warrant Agent, as applicable, and of Section 8-401(1) of the Uniform Commercial
Code as in effect in the State of New York are met; provided, however, that
prior to the Separation Date the Initial Warrant Agent shall not register a
transfer of a Warrant Certificate and such transfer will be void and of no
effect unless the Notes that are a part of the same Unit as the Warrants
represented by the Warrant Certificate to be transferred are simultaneously
transferred to the same transferee. To permit the registration of transfers and
exchanges, the Company shall, at the request of the Warrant Agent or the Initial
Warrant Agent, as applicable, execute and the Warrant Agent or the Initial
Warrant Agent, as applicable, shall countersign Warrant Certificates. All
Warrant Certificates issued upon any registration of transfer or exchange of
Warrant Certificates shall be valid obligations of the Company, entitled to the
same benefits under this Agreement as the Warrant Certificates surrendered upon
such registration of transfer or exchange. No service charge will be made to a
Holder for any registration of transfer or exchange upon surrender of any
Warrant Certificate at the office of the Warrant Agent or the Initial Warrant
Agent, as applicable, maintained for that purpose. However, the Company may
require payment of a sum sufficient to cover any tax, assessment or other
governmental charge that may be imposed in connection with any registration of
transfer or exchange of Warrant Certificates but not for any exchange or
original issuance (not involving a transfer) pursuant to Section 2.8, 3.4 or
3.5.

            (b) Notwithstanding any other provisions of this Section 2.6, unless
and until it is exchanged in whole or in part for Warrants in definitive
registered form, the Global Warrant may not be transferred except as a whole by
DTC to a nominee of DTC or by a nominee of DTC to DTC or another nominee of DTC
or by DTC or any such nominee to a successor depositary or a nominee of such
successor depositary. Interests of beneficial owners in the Global Warrant may
be transferred in accordance with the rules and procedures of DTC. Members of,
or participants in, DTC ("Participants") shall have no rights under this
Agreement with respect to the Global Warrant held on their behalf by DTC or the
Warrant Agent or the Initial Warrant Agent, as applicable, as its custodian, and
DTC may be treated by the Company, the Warrant Agent or the Initial Warrant
Agent, as applicable, and any agent of the Company or the Warrant Agent or the
Initial Warrant Agent, as applicable, as the absolute owner of such Global
Warrant for all purposes whatsoever. Notwithstanding the foregoing, nothing
herein shall prevent the Company, the Warrant Agent or the Initial Warrant
Agent, as applicable, or any agent of the Company or the Warrant Agent or the
Initial Warrant Agent, as applicable, from giving effect to any written
certification, proxy or other authorization furnished by DTC, and nothing herein
shall impair, as between DTC and its Participants, the operation of customary
practices governing the exercise of

<PAGE>   13

the rights of a Holder of any Warrants. The registered holder of the Global
Warrant may grant proxies and otherwise authorize any person, including
Participants and persons that may hold interests through Participants, to take
any action which a Holder is entitled to take under this Agreement or the
Warrants.

            If DTC notifies the Company that it is unwilling or unable to
continue as depositary for the Global Warrant or Warrants or if at any time DTC
shall no longer be eligible under the next sentence of this paragraph, the
Company shall appoint a successor depositary with respect to the Warrants. Each
depositary appointed pursuant to this Section 2.6 must, at the time of its
appointment and at all times while it serves as depositary, be a clearing agency
registered under the Exchange Act and any other applicable statute or
regulation. The Company will execute, and the Warrant Agent or the Initial
Warrant Agent, as applicable, upon receipt of written instructions from the
Company, will countersign and deliver, Warrants in definitive registered form in
any authorized denominations, in an aggregate amount equal to the amount of the
Global Warrant or Warrants representing such Warrants in exchange for such
Global Warrant or Warrants if DTC notifies the Company that it is unwilling or
unable to continue as depositary for the Global Warrant or Warrants or if at any
time DTC shall no longer be eligible to serve as depositary and a successor
depositary for the Warrants is not appointed by the Company within 60 days after
the Company receives such notice or becomes aware of such ineligibility.

            SECTION 2.7. Replacement Certificates. If a mutilated Warrant
Certificate is surrendered to the Warrant Agent or the Initial Warrant Agent, as
applicable, or if the Holder of a Warrant Certificate claims that the Warrant
Certificate has been lost, destroyed or wrongfully taken, the Company shall
issue and the Warrant Agent or the Initial Warrant Agent, as applicable, shall
countersign a replacement Warrant Certificate if the reasonable requirements of
the Warrant Agent, or the Initial Warrant Agent, as applicable, and of Section
8-405 of the Uniform Commercial Code as in effect in the State of New York are
met. Such Holder shall furnish an indemnity bond sufficient in the judgment of
the Company and the Warrant Agent or the Initial Warrant Agent, as applicable,
to protect the Company and the Warrant Agent or the Initial Warrant Agent, as
applicable, from any loss which either of them may suffer if a Warrant
Certificate is replaced. The Company and the Warrant Agent or the Initial
Warrant Agent, as applicable, may charge the Holder for their expenses in
replacing a Warrant Certificate. Every replacement Warrant Certificate is an
additional obligation of the Company.

            SECTION 2.8. Temporary Certificates. Until definitive Warrant
Certificates are ready for delivery, the Company may prepare and the Warrant
Agent or the Initial Warrant Agent, as applicable, shall countersign temporary
Warrant Certificates. Temporary Warrant Certificates shall be substantially in
the form of definitive Warrant Certificates but may have variations that the
Company considers appropriate for temporary Warrant Certificates. Without
unreasonable delay, the Company shall prepare and the Warrant Agent or the
Initial Warrant Agent, as applicable, shall countersign definitive Warrant
Certificates and deliver them in exchange for temporary Warrant Certificates.

<PAGE>   14

            SECTION 2.9. Cancellation. (a) In the event the Company shall
purchase or otherwise acquire Warrant Certificates, the same shall thereupon be
delivered to the Warrant Agent or the Initial Warrant Agent, as applicable, for
cancellation.

            (b) The Warrant Agent or the Initial Warrant Agent, as applicable,
and no one else shall cancel and may, but shall not be required to, destroy all
Warrant Certificates surrendered for transfer, exchange, replacement, exercise
or cancellation unless the Company directs the Warrant Agent or the Initial
Warrant Agent, as applicable, to deliver canceled Warrant Certificates to the
Company. The Company may not issue new Warrant Certificates to replace Warrant
Certificates to the extent they represent Warrants which have been exercised or
Warrants which the Company has purchased or otherwise acquired.

                                    ARTICLE 3
                                 Exercise Terms

            SECTION 3.1. Exercise Price. Each Warrant shall initially entitle
the Holder thereof, subject to adjustment pursuant to the terms of this
Agreement, to purchase 4.75 shares of Common Stock for a per share exercise
price (the "Exercise Price") of $87.00.

            SECTION 3.2. Exercise Periods; Restrictions on Exercise. Subject to
the terms and conditions set forth herein, the Warrants shall be exercisable at
any time or from time to time after the earlier of August 15, 2000 and the
occurrence of an Exercise Event and prior February 15, 2010 (the "Expiration
Date").

            SECTION 3.3. Expiration. Each Warrant shall terminate and become
void as of the earlier of (i) the close of business on the Expiration Date or
(ii) the date such Warrant is exercised. The Issuer shall give notice not less
than 90 and not more than 120 days prior to the Expiration Date to the Holders
of all then outstanding Warrants to the effect that the Warrants will terminate
and become void as of the close of business on the Expiration Date; provided,
however, that if the Company fails to give notice as provided in this Section
3.3, the Warrants will nevertheless expire and become void on the Expiration
Date.

            SECTION 3.4. Manner of Exercise. Warrants may be exercised upon (i)
surrender to the Warrant Agent or the Initial Warrant Agent, as applicable, at
the principal corporate trust office of the Warrant Agent or the Initial Warrant
Agent, as applicable, of the related Warrant Certificate, together with the form
of election to purchase Common Stock on the reverse thereof duly filled in and
signed by the Holder thereof, and (ii) payment to the Warrant Agent, for the
account of the Company, of the Exercise Price for each Warrant Share issuable
upon the exercise of such Warrants then exercised. Such payment shall be made in
cash or by certified or official bank check payable to the order of the Company
or by wire transfer of funds to an account designated by the Company for such
purpose. Subject to Section 3.2, the rights represented by the Warrants shall be
exercisable at the election of the Holders thereof either in full at any time or
from time to time in part and in the event that a Warrant Certificate is
surrendered for exercise of less than all the Warrants represented by such
Warrant Certificate at any time prior to the

<PAGE>   15

Expiration Date, a new Warrant Certificate representing the remaining Warrants
shall be issued. The Warrant Agent or the Initial Warrant Agent, as applicable,
shall countersign and deliver the required new Warrant Certificates, and the
Company, at the request of the Warrant Agent or the Initial Warrant Agent, as
applicable, shall supply the Warrant Agent or the Initial Warrant Agent, as
applicable, with Warrant Certificates duly signed on behalf of the Company for
such purpose.

            SECTION 3.5. Issuance of Warrant Shares. Subject to Section 2.6,
upon the surrender of Warrant Certificates and form of election properly
completed and executed and payment of the per share Exercise Price, as set forth
in Section 3.4, the Company shall issue and cause the Warrant Agent or the
Initial Warrant Agent, as applicable, or, if appointed, a transfer agent for the
Common Stock ("Transfer Agent") to countersign and deliver to or upon the
written order of the Holder and in such name or names as the Holder may
designate a certificate or certificates for the number of full Warrant Shares so
purchased upon the exercise of such Warrants or other securities or property to
which it is entitled, registered or otherwise, to the Person or Persons entitled
to receive the same, together with cash as provided in Section 3.6 in respect of
any fractional Warrant Shares otherwise issuable upon such exercise. Such
certificate or certificates shall be deemed to have been issued and any Person
so designated to be named therein shall be deemed to have become a holder of
record of such Warrant Shares as of the date of the surrender of such Warrant
Certificates, form of election and payment of the per share Exercise Price, as
aforesaid; provided, however, that if, at such date, the transfer books for the
Warrant Shares shall be closed, the certificates for the Warrant Shares in
respect of which such Warrants are then exercised shall be issuable as of the
date on which such books shall next be opened and until such date the Company
shall be under no duty to deliver any certificates for such Warrant Shares;
provided further, however, that such transfer books, unless otherwise required
by law, shall not be closed at any one time for a period longer than 20 calendar
days.

            SECTION 3.6. Fractional Warrant Shares. The Company shall not be
required to issue fractional Warrant Shares on the exercise of Warrants. If more
than one Warrant shall be exercised in full at the same time by the same Holder,
the number of full Warrant Shares which shall be issuable upon such exercise
shall be computed on the basis of the aggregate number of Warrant Shares
purchasable pursuant thereto. If any fraction of a Warrant Share would, except
for the provisions of this Section 3.6, be issuable on the exercise of any
Warrant (or specified portion thereof), the Company shall pay at the time of
exercise an amount in cash equal to the Current Market Value per Warrant Share,
as determined on the day immediately preceding the date the Warrant is
exercised, multiplied by such fraction, computed to the nearest whole cent.

            SECTION 3.7. Reservation of Warrant Shares. The Company shall at all
times keep reserved out of its authorized shares of Common Stock a number of
shares of Common Stock sufficient to provide for the exercise of all outstanding
Warrants. The registrar for the Common Stock shall at all times until the
Expiration Date reserve such number of authorized shares as shall be required
for such purpose. The Company will keep a copy of this Agreement on file with
the Transfer Agent. All Warrant Shares which may be issued upon exercise of
Warrants shall, upon issue, be fully paid, nonassessable, free of preemptive
rights and free from all taxes, liens, charges and security interests with
respect to the issue thereof. The Company will supply such Transfer Agent with
duly executed stock certificates for such purpose and will itself

<PAGE>   16

provide or otherwise make available any cash which may be payable as provided in
Section 3.6. The Company will furnish to such Transfer Agent a copy of all
notices of adjustments (and certificates related thereto) transmitted to each
Holder.

            Before taking any action which would cause an adjustment pursuant to
Article 4 to reduce the Exercise Price below the then par value (if any) of the
Common Stock, the Company shall take any and all corporate action which may, in
the opinion of its counsel, be necessary in order that the Company may validly
and legally issue fully paid and nonassessable shares of Common Stock at the
Exercise Price as so adjusted.

            The Company covenants that all shares of Common Stock which may be
issued upon exercise of Warrants will, upon issue, be fully paid, nonassessable,
free of preemptive rights, free from all taxes and free from all liens, charges
and security interests, created by or through the Company, with respect to the
issue thereof.

            SECTION 3.8. Compliance with Law. Notwithstanding anything in this
Agreement to the contrary, in no event shall a Holder be entitled to exercise a
Warrant unless (i) a registration statement filed under the Securities Act in
respect of the issuance of the Warrant Shares is then effective or (ii) in the
opinion of counsel to the Company addressed to the Warrant Agent the exercise of
such Warrants is exempt from the registration requirements of the Securities Act
and such securities are qualified for sale or exempt from qualification under
the applicable securities laws of the States or other jurisdictions in which
such holders reside.

            SECTION 3.9 Listing of Warrant Shares. The Company shall take all
action reasonably necessary to have the Warrant Shares approved for listing on a
national securities exchange or market.

                                    ARTICLE 4
                             Antidilution Provisions

            SECTION 4.1. Changes in Common Stock. In the event that at any time
or from time to time the Company shall (i) pay a dividend or make a distribution
on its Common Stock payable in shares of its Common Stock or other equity
interests of the Company, (ii) subdivide its outstanding shares of Common Stock
into a larger number of shares of Common Stock, (iii) combine its outstanding
shares of Common Stock into a smaller number of shares of Common Stock or (iv)
increase or decrease the number of shares of Common Stock outstanding by
reclassification of its Common Stock, then the number of shares of Common Stock
issuable upon exercise of each Warrant immediately after the happening of such
event shall be adjusted to a number determined by multiplying the number of
shares of Common Stock that such holder would have owned or have been entitled
to receive upon exercise had such Warrants been exercised immediately prior to
the happening of the events described above (or, in the case of a dividend or
distribution of Common Stock or other shares of capital stock, immediately prior
to the record date therefor) by a fraction, the numerator of which shall be the
total number of shares of Common Stock outstanding immediately after the
happening of the events described above and the denominator of which shall be
the total number of shares of Common Stock outstanding

<PAGE>   17

immediately prior to the happening of the events described above; and subject to
Section 4.8, the Exercise Price for each Warrant shall be adjusted to a number
determined by dividing the Exercise Price immediately prior to such event by the
aforementioned fraction. An adjustment made pursuant to this Section 4.1 shall
become effective immediately after the effective date of such event, retroactive
to the record date therefor in the case of a dividend or distribution in shares
of Common Stock or other shares of the Company's Capital Stock.

            SECTION 4.2. Cash Dividends and Other Distributions. In the event
that at any time or from time to time the Company shall distribute to all
holders of Common Stock (i) any dividend or other distribution of cash,
evidences of its indebtedness, shares of its capital stock or any other assets,
properties or debt securities or (ii) any options, warrants or other rights to
subscribe for or purchase any of the foregoing (provided, however, that no
adjustment shall be made upon the exercise of such rights, options or warrants,
and other than, in each case, (w) the issuance of any rights under a shareholder
rights plan, (x) any dividend or distribution described in Section 4.1, (y) any
rights, options, warrants or securities described in Section 4.3 and (z) any
cash dividends or other cash distributions from current or retained earnings),
then the number of shares of Common Stock issuable upon the exercise of each
Warrant shall be increased to a number determined by multiplying the number of
shares of Common Stock issuable upon the exercise of such Warrant immediately
prior to the record date for any such dividend or distribution by a fraction,
the numerator of which shall be the Current Market Value per share of Common
Stock on the record date for such dividend or distribution and the denominator
of which shall be such Current Market Value per share of Common Stock on the
record date for such dividend or distribution less the sum of (x) the amount of
cash, if any, distributed per share of Common Stock and (y) the fair value (as
determined in good faith by the Board of Directors, whose determination shall be
evidenced by a board resolution filed with the Warrant Agent, a copy of which
will be sent to Holders upon request) of the portion, if any, of the
distribution applicable to one share of Common Stock consisting of evidences of
indebtedness, shares of stock, securities, other assets or property, warrants,
options or subscription or purchase rights; and, subject to Section 4.8, the
Exercise Price shall be adjusted to a number determined by dividing the Exercise
Price immediately prior to such record date by the aforementioned fraction. Such
adjustments shall be made whenever any distribution is made and shall become
effective as of the date of distribution, retroactive to the record date for any
such distribution; provided, however, that the Company is not required to make
an adjustment pursuant to this Section 4.2 if at the time of such distribution
the Company makes the same distribution to Holders of Warrants as it makes to
holders of Common Stock pro rata based on the number of shares of Common Stock
for which such Warrants are exercisable (whether or not currently exercisable).
No adjustment shall be made pursuant to this Section 4.2 which shall have the
effect of decreasing the number of shares of Common Stock issuable upon exercise
of each Warrant or increasing the Exercise Price.

            SECTION 4.3. Rights Issue to All Holders of Common Stock. In the
event that at any time or from time to time the Company shall issue to all
holders of Common Stock without any charge, rights, options or warrants
entitling the holders thereof to subscribe for shares of Common Stock (provided,
however, that no adjustment shall be made upon the exercise of such rights,
options or warrants), or securities convertible into or exchangeable or
exercisable for Common Stock, entitling such holders to subscribe for or
purchase shares of Common Stock

<PAGE>   18

(provided, however, that no adjustment shall be made upon the conversion,
exchange or exercise of such securities (other than issuances specified in this
and the foregoing clause which are made as the result of anti-dilution
adjustments in such securities)) at a price per share that is lower at the
record date for such issuance than the then Current Market Value per share of
Common Stock (other than in connection with the adoption of a shareholder rights
plan by the Company), then the number of shares of Common Stock issuable upon
the exercise of each Warrant shall be increased to a number determined by
multiplying the number of shares of Common Stock theretofore issuable upon
exercise of each Warrant by a fraction, the numerator of which shall be the
number of shares of Common Stock outstanding on the date of issuance of such
rights, options, warrants or securities plus the number of additional shares of
Common Stock offered for subscription or purchase or into or for which such
securities that are issued are convertible, exchangeable or exercisable, and the
denominator of which shall be the number of shares of Common Stock outstanding
on the date of issuance of such rights, options, warrants or securities plus the
total number of shares of Common Stock which the aggregate consideration
expected to be received by the Company (assuming the exercise or conversion of
all such rights, options, warrants or securities) would purchase at the then
Current Market Value per share of Common Stock. Subject to Section 4.8, in the
event of any such adjustment, the Exercise Price shall be adjusted to a number
determined by dividing the Exercise Price immediately prior to such date of
issuance by the aforementioned fraction. Such adjustment shall be made
immediately after such rights, options or warrants are issued and shall become
effective, retroactive to the record date for the determination of stockholders
entitled to receive such rights, options, warrants or securities.
Notwithstanding anything to the contrary in this Article 4, no adjustment to the
number of Warrant Shares issuable upon exercise of the Warrants or to the
Exercise Price shall be made as a result of the offering by the Company to all
holders of its Common Stock of rights, options or warrants entitling the holders
thereof to subscribe for Common Stock or securities convertible into or
exchangeable or exercisable for shares of Common Stock, resulting from the
operation of any anti-dilution provision in any warrant or other security of the
Company convertible into, exercisable or exchangeable for Common Stock of the
Company, which such warrant or security is outstanding on the date of this
Agreement. No adjustment shall be made pursuant to this Section 4.3 which shall
have the effect of decreasing the number of shares of Common Stock purchasable
upon exercise of each Warrant or of increasing the Exercise Price.

            SECTION 4.4. Other Issuances of Common Stock or Rights. In the event
that at any time or from time to time the Company shall issue (i) shares of
Common Stock (subject to the provisions below), (ii) rights, options or warrants
entitling the holder thereof to subscribe for shares of Common Stock (provided,
however, that no adjustment shall be made upon the exercise of such rights,
options or warrants), or (iii) securities convertible into or exchangeable or
exercisable for Common Stock (provided, however, that no adjustment shall be
made upon the conversion, exchange or exercise of such securities (other than
issuances specified in (i), (ii) or (iii) which are made as the result of
anti-dilution adjustments in such securities)), at a price per share at the
record date of such issuance that is less than the then Current Market Value per
share of Common Stock, then the number of shares of Common Stock issuable upon
the exercise of each Warrant shall be increased to a number determined by
multiplying the number of shares of Common Stock theretofore issuable upon
exercise of each Warrant by a fraction, the numerator of which shall be the
number of shares of Common Stock outstanding immediately after such sale or

<PAGE>   19

issuance plus the number of additional shares of Common Stock offered for
subscription or purchase or into or for which such securities that are issued
are convertible, exchangeable or exercisable, and the denominator of which shall
be the number of shares of Common Stock outstanding immediately prior to such
sale or issuance plus the total number of shares of Common Stock which the
aggregate consideration expected to be received by the Company (assuming the
exercise or conversion of all such rights, options, warrants or securities, if
any) would purchase at the then Current Market Value per share of Common Stock,
and subject to Section 4.8 the Exercise Price shall be adjusted to a number
determined by dividing the Exercise Price immediately prior to such date of
issuance by the aforementioned fraction; provided, however, that no adjustment
to the number of Warrant Shares issuable upon the exercise of the Warrants or to
the Exercise Price shall be made as a result of (i) the issuance of shares of
Common Stock under any warrants, options or other rights existing on the date
hereof, (ii) the issuance of shares of Common Stock in bona fide public or
private offerings that are underwritten or in which a placement agent is
retained by the Company or (iii) the issuance of options, rights or shares of
Common Stock pursuant to any option, under any employee benefit plans approved
by the Board of Directors. Such adjustments shall be made whenever such rights,
options or warrants or convertible securities are issued. No adjustment shall be
made pursuant to this Section 4.4 which shall have the effect of decreasing the
number of shares of Common Stock issuable upon exercise of each warrant or of
increasing the Exercise Price. For purposes of Section 4.4 only, any issuance of
Common Stock, or rights, options or warrants to subscribe for, or other
securities convertible into or exercisable or exchangeable for, Common Stock,
which issuance (or agreement to issue) (A) is in exchange for or otherwise in
connection with the bona fide acquisition of property (excluding any such
exchange exclusively for cash but including any such exchange incident to an
acquisition by merger or the establishment or modification of any commercial
relationship by contract) of any Person and (B) is at a price per share
determined by the Board of Directors to be equal to the fair market value
thereof at the time an agreement in principle is reached or at the time a
definitive agreement is entered into, except that in the event the fair market
value exceeds $30,000,000, the Issuers shall be required to obtain an opinion
from financial advisors with respect to the fairness to the Issuers (or Company,
as appropriate) of the transaction from a financial point of view, shall be
deemed to have been made at a price per share equal to the Current Market Value
per share at the record date with respect to such issuance (the time of closing
or consummation of such exchange or acquisition) if such definitive agreement is
entered into within 90 days of the date of such agreement in principle.

            SECTION 4.5. Combination; Liquidation. (a) Except as provided in
Section 4.5(b), in the event of a Combination, each Holder shall have the right
to receive upon exercise of the Warrants the kind and amount of shares of
capital stock or other securities or property which such Holder would have been
entitled to receive upon or as a result of such Combination had such Warrant
been exercised immediately prior to such event. Unless paragraph (b) is
applicable to a Combination, the Company shall provide that the surviving or
acquiring Person (the "Successor Company") in such Combination will enter into
an agreement with the Warrant Agent or the Initial Warrant Agent, as applicable,
confirming the Holders' rights pursuant to this Section 4.5(a) and providing for
adjustments, which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 4. The provisions of this Section
4.5(a) shall similarly apply to successive Combinations involving any Successor
Company.

<PAGE>   20

            (b) In the event of (i) a Combination where consideration to the
holders of Common Stock in exchange for their shares is payable solely in cash
or (ii) the dissolution, liquidation or winding-up of the Company, the holders
of the Warrants shall be entitled to receive, upon surrender of their Warrant
Certificates, distributions on an equal basis with the holders of Common Stock
or other securities, issuable upon exercise of the Warrants, as if the Warrants
had been exercised immediately prior to such event, less the Exercise Price.

            In case of any Combination described in this Section 4.5(b), the
surviving or acquiring Person and, in the event of any dissolution, liquidation
or winding-up of the Company, the Company shall deposit promptly with the
Warrant Agent or the Initial Warrant Agent, as applicable, the funds, if any,
necessary to pay to the holders of the Warrants the amounts to which they are
entitled as described above. After such funds and the surrendered Warrant
Certificates are received, the Warrant Agent is required to deliver a check in
such amount as is appropriate (or, in the case of consideration other than cash,
such other consideration as is appropriate) to such Person or Persons as it may
be directed in writing by the Holders surrendering such Warrants.

            SECTION 4.6. Other Events. If any event occurs as to which the
foregoing provisions of this Article 4 are not strictly applicable or, if
strictly applicable, would not, in the good faith judgment of the Board of
Directors, fairly and adequately protect the purchase rights of the Warrants in
accordance with the essential intent and principles of such provisions, then
such Board of Directors shall make such adjustments in the application of such
provisions, in accordance with such essential intent and principles, as shall be
reasonably necessary, in the good faith opinion of such Board of Directors, to
protect such purchase rights as aforesaid, but in no event shall any such
adjustment have the effect of increasing the Exercise Price or decreasing the
number of shares of Common Stock issuable upon exercise of any Warrant.

            SECTION 4.7. Superseding Adjustment. Upon the expiration of any
rights, options, warrants or conversion or exchange privileges which resulted in
adjustments pursuant to this Article 4, if any thereof shall not have been
exercised, the number of Warrant Shares issuable upon the exercise of each
Warrant shall be readjusted pursuant to the applicable section of Article 4 as
if (A) the only shares of Common Stock issuable upon exercise of such rights,
options, warrants, conversion or exchange privileges were the shares of Common
Stock, if any, actually issued upon the exercise of such rights, options,
warrants or conversion or exchange privileges and (B) shares of Common Stock
actually issued, if any, were issuable for the consideration actually received
by the Company upon such exercise plus the aggregate consideration, if any,
actually received by the Company for the issuance, sale or grant of all such
rights, options, warrants or conversion or exchange privileges whether or not
exercised and the Exercise Price shall be readjusted inversely; provided,
however, that no such readjustment shall (except by reason of an intervening
adjustment under Section 4.1) have the effect of decreasing the number of
Warrant Shares purchasable upon the exercise of each Warrant or increase the
Exercise Price by an amount in excess of the amount of the adjustment initially
made in respect of the issuance, sale or grant of such rights, options, warrants
or conversion or exchange privileges.

<PAGE>   21

            SECTION 4.8. Minimum Adjustment. The adjustments required by the
preceding Sections of this Article 4 shall be made whenever and as often as any
specified event requiring an adjustment shall occur, except that no adjustment
of the Exercise Price or the number of shares of Common Stock issuable upon
exercise of Warrants that would otherwise be required shall be made unless and
until such adjustment either by itself or with other adjustments not previously
made increases or decreases by at least 1% the Exercise Price or the number of
shares of Common Stock issuable upon exercise of Warrants immediately prior to
the making of such adjustment. Any adjustment representing a change of less than
such minimum amount shall be carried forward and made as soon as such
adjustment, together with other adjustments required by this Article 4 and not
previously made, would result in a minimum adjustment. For the purpose of any
adjustment, any specified event shall be deemed to have occurred at the close of
business on the date of its occurrence. In computing adjustments under this
Article 4, fractional interests in Common Stock shall be taken into account to
the nearest one-hundredth of a share.

            SECTION 4.9. Notice of Adjustment. Whenever the Exercise Price or
the number of shares of Common Stock and other property, if any, issuable upon
exercise of the Warrants is adjusted, as herein provided, the Company shall
deliver to the Warrant Agent a certificate of a firm of independent accountants
selected by the Board of Directors (who may be the regular accountants employed
by the Company) setting forth, in reasonable detail, the event requiring the
adjustment and the method by which such adjustment was calculated (including a
description of the basis on which (i) the Board of Directors determined the fair
value of any evidences of indebtedness, other securities or property or
warrants, options or other subscription or purchase rights and (ii) the Current
Market Value of the Common Stock was determined, if either of such
determinations were required), and specifying the Exercise Price and the number
of shares of Common Stock issuable upon exercise of Warrants after giving effect
to such adjustment. The Company shall promptly cause the Warrant Agent to mail a
copy of such certificate to each Holder in accordance with Section 7.6. The
Warrant Agent shall be entitled to rely on such certificate and shall be under
no duty or responsibility with respect to any such certificate, except to
exhibit the same from time to time, to any Holder desiring an inspection thereof
during reasonable business hours. The Warrant Agent shall not at any time be
under any duty or responsibility to any Holder to determine whether any facts
exist which may require any adjustment of the Exercise Price or the number of
shares of Common Stock or other stock or property issuable on exercise of the
Warrants, or with respect to the nature or extent of any such adjustment when
made, or with respect to the method employed in making such adjustment or the
validity or value of any shares of Common Stock, evidences of indebtedness,
warrants, options, or other securities or property.

            SECTION 4.10. Notice of Certain Transactions. In the event that the
Company shall propose to (a) pay any dividend payable in securities of any class
to the holders of its Common Stock or to make any other non-cash dividend or
distribution to the holders of its Common Stock, (b) offer the holders of its
Common Stock rights to subscribe for or to purchase any securities convertible
into shares of Common Stock or shares of stock of any class or any other
securities, rights or options, (c) issue any (i) shares of Common Stock, (ii)
rights, options or warrants entitling the holders thereof to subscribe for
shares of Common Stock, or (iii) securities convertible into or exchangeable or
exercisable for Common Stock (in the case of (i), (ii) and (iii),

<PAGE>   22

if such issuance or adjustment would result in an adjustment hereunder), (d)
effect any capital reorganization, reclassification, consolidation or merger,
(e) effect the voluntary or involuntary dissolution, liquidation or winding-up
of the Company or (f) make a tender offer or exchange offer with respect to the
Common Stock, the Company shall within 10 days send to the Warrant Agent and the
Warrant Agent or the Initial Warrant Agent, as applicable, shall within 10 days
of its receipt thereof send the Holder a notice (in such form as shall be
furnished to the Warrant Agent or the Initial Warrant Agent, as applicable, by
the Company) of such proposed action or offer. Such notice shall be mailed by
the Warrant Agent or the Initial Warrant Agent, as applicable, to the Holders at
their addresses as they appear in the Certificate Register, which shall specify
the record date for the purposes of such dividend, distribution or rights, or
the date such issuance or event is to take place and the date of participation
therein by the holders of Common Stock, if any such date is to be fixed, and
shall briefly indicate the effect of such action on the Common Stock and on the
number and kind of any other shares of stock and on other property, if any, and
the number of shares of Common Stock and other property, if any, issuable upon
exercise of each Warrant and the Exercise Price after giving effect to any
adjustment pursuant to Article 4 which will be required as a result of such
action. Such notice shall be given as promptly as possible and (x) in the case
of any action covered by clause (a) or (b) above, at least 10 days prior to the
record date for determining holders of the Common Stock for purposes of such
action or (y) in the case of any other such action, at least 20 days prior to
the date of the taking of such proposed action or the date of participation
therein by the holders of Common Stock, whichever shall be the earlier.

            SECTION 4.11. Adjustment to Warrant Certificate. The form of Warrant
Certificate need not be changed because of any adjustment made pursuant to this
Article 4, and Warrant Certificates issued after such adjustment may state the
same Exercise Price and the same number of shares of Common Stock issuable upon
exercise of the Warrants as are stated in the Warrant Certificates initially
issued pursuant to this Agreement. The Company, however, may at any time in its
sole discretion make any change in the form of Warrant Certificate that it may
deem appropriate to give effect to such adjustments and that does not affect the
substance of the Warrant Certificate, and any Warrant Certificate thereafter
issued or countersigned, whether in exchange or substitution for an outstanding
Warrant Certificate or otherwise, may be in the form as so changed.

            SECTION 4.12. Exceptions to Antidilution Provisions. Without
limiting any other exception contained in this Article 4, and in addition
thereto, no adjustment need be made for:

                (i) grants or exercises of rights granted to employees,
        directors or consultants of the Company or any of its subsidiaries or
        shares of Common Stock issued or granted to such persons under
        equity-based incentive or corporation plans or otherwise, whether or not
        upon the exercise, exchange or conversion of any such rights;

<PAGE>   23

                (ii) options, warrants or other agreements or rights to purchase
        capital stock of the Company entered into prior to the date of the
        issuance of the Warrants and any issuance of shares of Common Stock in
        connection therewith;

                (iii) rights to purchase shares of Common Stock pursuant to a
        Company plan for reinvestment of dividends or interest;

                (iv) a change in the par value of shares of Common Stock
        (including a change from par value to no par value or vice versa);

                (v) the consummation of the Holding Company Reorganization; and

                (vi) bona fide public offerings or private placements pursuant
        to Section 4(2) of the Securities Act, Regulation D thereunder or
        Regulation S of any security trading on any national securities
        exchange, the Nasdaq system or in the over the counter market, or of a
        security directly or indirectly convertible or exchangeable for any such
        security (the latter security being a "Reference Security"), involving
        at least one investment bank of national reputation, if such security is
        sold to investors at a price equal to the closing sale, bid or ask price
        (whichever is customary)(less such discount, if any, as such investment
        bank shall reasonably determine is necessary to permit the consummation
        of such public offering or private placement) of such security or the
        Reference Security on the date of the public offering or private
        placement.

                                    ARTICLE 5
                                  Warrant Agent

            SECTION 5.1. Appointment of Warrant Agent. The Company hereby
appoints (a) the Initial Warrant Agent to act as agent for the Company from the
date hereof until the Separation Date, (the "Initial Period"), and (b) the
Warrant Agent to act as agent for the Company from the Separation Date until the
Expiration Date, both in accordance with the express provisions of this
Agreement and the Initial Warrant Agent and Warrant Agent hereby accept such
appointments. For purposes of this Article 5, the term "Warrant Agent" shall
refer to both the Initial Warrant Agent with respect to the Initial Period and
the Warrant Agent with respect to subsequent to the Initial Period. Upon the
Separation Date, the Initial Warrant Agent shall transfer to the Warrant Agent
the Certificate Register and such other documents as the Warrant Agent shall
reasonably request.

            SECTION 5.2. Right and Duties of Warrant Agent. (a) In acting under
this Warrant Agreement and in connection with the Warrant Certificates, the
Warrant Agent is acting solely as agent for the Company and does not assume any
obligation or relationship of agency or trust for or with any of the holders of
Warrant Certificates or beneficial owners of Warrants.

<PAGE>   24

            (b) The Warrant Agent may consult with counsel satisfactory to it
(who may be counsel to the Company), and the advice of such counsel shall be
full and complete authorization and protection in respect of any action taken,
suffered or omitted by it hereunder in good faith and in accordance with the
advice of such counsel.

            (c) The Warrant Agent shall be protected and shall incur no
liability for or in respect of any action taken or thing suffered by it in
reliance upon any Warrant Certificate, notice, direction, consent, certificate,
affidavit, statement, opinion or other paper or document reasonably believed by
it to be genuine and to have been presented or signed by the proper parties.

            (d) The Warrant Agent shall be obligated to perform only such duties
as are specifically set forth herein and in the Warrant Certificates, and no
implied duties or obligations of the Warrant Agent shall be read into this
Agreement or the Warrant Certificates. The Warrant Agent shall not be
accountable or under any duty or responsibility for the use by the Company of
any of the Warrant Certificates countersigned by the Warrant Agent and delivered
by it to the Holders or on behalf of the Holders pursuant to this Agreement or
for the application by the Company of the proceeds of the Warrants. The Warrant
Agent shall have no duty or responsibility in case of any default by the Company
in the performance of its covenants or agreements contained herein or in the
Warrant Certificates or in the case of the receipt of any written demand from a
Holder with respect to such default, including any duty or responsibility to
initiate or attempt to initiate any proceedings at law or otherwise.

            (e) The Warrant Agent shall not at any time be under any duty or
responsibility to any Holder to determine whether any facts exist that may
require an adjustment of the number of shares of Common Stock issuable upon
exercise of each Warrant or the Exercise Price, or with respect to the nature or
extent of any adjustment when made or with respect to the method employed or
provided to be employed herein or in any supplemental agreement in making the
same. The Warrant Agent shall not be accountable with respect to the validity or
value of any shares of Common Stock or of any securities or property which may
at any time be issued or delivered upon the exercise of any Warrant or upon any
adjustment pursuant to Article 4, and it makes no representation with respect
thereto. The Warrant Agent shall not be responsible for any failure of the
Company to make any cash payment or to issue, transfer or deliver any shares of
Common Stock or stock certificates upon the surrender of any Warrant Certificate
for the purpose of exercise or upon any adjustment pursuant to Article 4, or to
comply with any of the covenants of the Company contained in Article 4.

            (f) The Warrant Agent may perform any of its duties through agents
and shall have no liability for the acts or omissions of such agents appointed
with due care.

            SECTION 5.3. Individual Rights of Warrant Agent. Except as may be
prohibited by law, the Warrant Agent and any stockholder, director, officer or
employee of the Warrant Agent may buy, sell or deal in any of the Warrants or
other securities of the Company or its affiliates or become pecuniarily
interested in transactions in which the Company or its affiliates may be
interested, or contract with or lend money to the Company or its affiliates or
otherwise act as fully and freely as though it were not the Warrant Agent under
this Agreement. Nothing herein

<PAGE>   25

shall preclude the Warrant Agent from acting in any other capacity for the
Company or for any other legal entity.

            SECTION 5.4. Warrant Agent's Disclaimer. The Warrant Agent shall not
be responsible for and makes no representation as to the validity or adequacy of
this Agreement or the Warrant Certificates and it shall not be responsible for
any statement in this Agreement or the Warrant Certificates other than its
countersignature thereon.

            SECTION 5.5. Compensation and Indemnity. The Company and the Warrant
Agent have entered into an agreement pursuant to which the Company agrees to pay
the Warrant Agent from time to time compensation for its services and to
reimburse the Warrant Agent upon request for all reasonable out-of-pocket
expenses incurred by it, including the reasonable compensation and expenses of
the Warrant Agent and its directors, officers, agents and counsel. The Company
shall indemnify the Warrant Agent and its directors, officers, agents and
counsel against any and all loss, liability, damage, claim or expense (including
agents' and attorneys' fees and expenses) incurred by the Warrant Agent without
negligence, bad faith or willful misconduct on its part arising out of or in
connection with the acceptance or performance of its duties under this
Agreement. The Warrant Agent shall notify the Company promptly of any claim for
which it may seek indemnity. The Company need not reimburse any expense or
indemnify against any loss or liability incurred by the Warrant Agent through
wilful misconduct, negligence or bad faith. The Company's payment obligations
pursuant to this Section 6.5 shall survive the termination of this Agreement and
the resignation or removal of the Warrant Agent.

            To secure the Company's payment obligations under this Agreement,
the Warrant Agent shall have a lien prior to the Holders on all money or
property held or collected by the Warrant Agent.

            SECTION 5.6. Successor Warrant Agent. The Company agrees for the
benefit of the Holders that there shall at all times be a Warrant Agent
hereunder until all the Warrants have been exercised or are no longer
exercisable.

            (a) The Warrant Agent may at any time resign by giving written
notice to the Company of such intention on its part, specifying the date on
which its desired resignation shall become effective; provided, however, that
such date shall not be less than 60 days after the date on which such notice is
given unless the Company otherwise agrees. The Warrant Agent hereunder may be
removed at any time by the filing with it of an instrument in writing signed by
or on behalf of the Company and specifying such removal and the date when it
shall become effective, which date shall not be less than 60 days after such
notice is given unless the Warrant Agent otherwise agrees. Any removal under
this Section 6.6 shall take effect upon the appointment by the Company as
hereinafter provided of a successor Warrant Agent (which shall be a bank or
trust company authorized under the laws of the jurisdiction of its organization
to exercise corporate trust powers) and the acceptance of such appointment by
such successor Warrant Agent. If a successor Warrant Agent does not take office
within 60 days after the retiring Warrant Agent resigns or is removed, the
retiring Warrant Agent or the Holders of 10% of the

<PAGE>   26

Warrants may petition, at the expense of the Company, any court of competent
jurisdiction for the appointment of a successor.

            (b) In the event that at any time the Warrant Agent shall resign, or
shall be removed, or shall become incapable of acting, or shall be adjudged a
bankrupt or insolvent, or shall commence a voluntary case under Federal
bankruptcy laws, as now or hereafter constituted, or under any other applicable
Federal or state bankruptcy, insolvency or similar law, or shall consent to the
appointment of or taking possession by a receiver, custodian, liquidator,
assignee, trustee, sequestrator (or other similar official) of the Warrant Agent
or its property or affairs, or shall make an assignment for the benefit of
creditors, or shall admit in writing its inability to pay its debts generally as
they become due, or shall take corporate action in furtherance of any such
action, or a decree or order for relief by a court having jurisdiction in the
premises shall have been entered in respect of the Warrant Agent in an
involuntary case under the Federal bankruptcy laws, as now or hereafter
constituted, or any other applicable Federal or State bankruptcy, insolvency or
similar law, or a decree or order by a court having jurisdiction in the premises
shall have been entered for the appointment of a receiver, custodian,
liquidator, assignee, trustee, sequestrator (or similar official) of the Warrant
Agent or of its property or affairs, or any public officer shall take charge or
control of the Warrant Agent or of its property or affairs for the purpose of
rehabilitation, conservation, winding up or liquidation, a successor Warrant
Agent, qualified as aforesaid, shall be appointed by the Company by an
instrument in writing filed with the successor Warrant Agent. Upon the
appointment as aforesaid of a successor Warrant Agent and acceptance by the
successor Warrant Agent of such appointment, the Warrant Agent shall cease to be
the Warrant Agent hereunder; provided, however, that in the event of the
resignation of the Warrant Agent hereunder, such resignation shall be effective
on the earlier of (i) the date specified in the Warrant Agent's notice of
resignation and (ii) the appointment and acceptance of a successor Warrant Agent
hereunder.

            (c) Any successor Warrant Agent appointed hereunder shall execute,
acknowledge and deliver to its predecessor and to the Company an instrument
accepting such appointment hereunder, and thereupon such successor Warrant
Agent, without any further act, deed or conveyance, shall become vested with all
the rights and obligations of such predecessor with like effect as if originally
named as Warrant Agent hereunder, and such predecessor, upon payment of its
charges and disbursements then unpaid, shall thereupon become obligated to
transfer, deliver and pay over, and such successor Warrant Agent shall be
entitled to receive, all monies, securities and other property on deposit with
or held by such predecessor, as Warrant Agent hereunder.

            (d) Any corporation into which the Warrant Agent hereunder may be
merged or consolidated, or any corporation resulting from any merger or
consolidation to which the Warrant Agent shall be a party, or any corporation to
which the Warrant Agent shall sell or otherwise transfer all or substantially
all the corporate trust or stock transfer assets and business of the Warrant
Agent, provided that it shall be qualified as aforesaid, shall be the successor
Warrant Agent under this Agreement without the execution or filing of any paper
or any further act on the part of any of the parties hereto.

<PAGE>   27

                                    ARTICLE 6
                                  Miscellaneous

            SECTION 6.1. Financial Statements and Reports of the Company. The
Company agrees (a) to file with the Warrant Agent or Initial Warrant Agent, as
applicable, and to provide to each Holder, upon written request of such Holder
to the Company, without cost to such Holder, copies of the annual and quarterly
reports and documents that the Company files with the Securities and Exchange
Commission (to the extent such filings are accepted by the Commission and
whether or not the Company has a class of securities registered under the
Exchange Act or that the Company would be required to file were it subject to
Section 13 or 15 of the Exchange Act, within 15 days after the date of such
filing or the date on which the Company would be required to file such reports
or documents, and all such annual or quarterly reports shall include the
geographic segment financial information as has heretofore been disclosed by the
Company in its public filings with the Securities and Exchange Commission, and
(b) if filing such reports and documents is not accepted by the Securities and
Exchange Commission or is prohibited under the Exchange Act, to supply at the
Company's expense copies of such reports and documents to any prospective Holder
promptly upon request.

            SECTION 6.2. Third-Party Beneficiaries. The Holders shall be
third-party beneficiaries to the agreements made hereunder between the Company,
on the one hand, and the Warrant Agent or the Initial Warrant Agent, as
applicable, on the other hand, and each Holder shall have the right to enforce
such agreements directly to the extent it deems such enforcement necessary or
advisable to protect its rights or the rights of Holders hereunder.

            SECTION 6.3. Rights of Holders. Holders of unexercised Warrants are
not entitled to (i) receive dividends or other distributions, (ii) receive
notice of or vote at any meeting of the stockholders, (iii) consent to any
action of the stockholders, (iv) receive notice as stockholders of any other
proceedings of the Company, (v) exercise any preemptive rights or (vi) exercise
any other rights whatsoever as stockholders of the Company.

            SECTION 6.4. Amendment. This Agreement may be amended by the parties
hereto without the consent of any Holder for the purpose of curing any
ambiguity, or of curing, correcting or supplementing any defective provision
contained herein or adding or changing any other provisions with respect to
matters or questions arising under this Agreement as the Company and the Warrant
Agent or the Initial Warrant Agent, as applicable, may deem necessary or
desirable (including without limitation any addition or modification to provide
for compliance with the transfer restrictions set forth herein); provided,
however, that such action shall not adversely affect the rights of any of the
Holders in any material respect. Any amendment or supplement to this Agreement
that has a material adverse effect on the interests of the Holders shall require
the written consent of the Holders of a majority of the then outstanding
Warrants. The consent of each Holder affected shall be required for any
amendment pursuant to which the Exercise Price would be increased or the number
of Warrant Shares issuable upon exercise of Warrants would be decreased (other
than pursuant to adjustments provided herein) or the exercise period with
respect to the Warrants would be shortened. In determining whether the Holders
of

<PAGE>   28

the required number of Warrants have concurred in any direction, waiver or
consent, Warrants owned by the Company or by any Person directly or indirectly
controlling or controlled by or under direct or indirect common control with the
Company shall be disregarded and deemed not to be outstanding, except that, for
the purpose of determining whether the Warrant Agent or the Initial Warrant
Agent, as applicable, shall be protected in relying on any such direction,
waiver or consent, only Warrants which the Warrant Agent or the Initial Warrant
Agent, as applicable, actually knows are so owned shall be so disregarded. Also,
subject to the foregoing, only Warrants outstanding at the time shall be
considered in any such determination.

            SECTION 6.5. Notices. Any notice or communication shall be in
writing and delivered in Person or mailed by first-class mail addressed as
follows:

               if to the Company:

               Metricom, Inc.
               980 University Avenue
               Los Gatos, California
               Attention:  Chief Financial Officer
               Telecopy No.:  408-354-1024

               With copies to:
               Cooley Godward LLP
               1 Maritime Plaza
               San Francisco, California  94111
               Attention:  Kenneth L. Guernsey, Esq.
               Telecopy No.:  415-951-3699

               If to the Initial Warrant Agent:

               Bank One Trust Company, N.A.
               One North State Street
               9th Floor
               Chicago, Illinois 60602
               Telecopy No.:  312-407-1708
               Attention:  Corporate Trust Administration

               If to the Warrant Agent:

               EquiServe LP

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

               ------------------------------------------
               Telecopy No.
                            ------------------------------
               Attention:
                            ------------------------------

<PAGE>   29

            The Company or the Warrant Agent by notice to the other may
designate additional or different addresses for subsequent notices or
communications.

            Any notice or communication mailed to a Holder shall be mailed to
the Holder at the Holder's address as it appears on the Certificate Register and
shall be sufficiently given if so mailed within the time prescribed.

            Failure to mail a notice or communication to a Holder or any defect
in it shall not affect its sufficiency with respect to other Holders. If a
notice or communication is mailed in the manner provided above, it is duly
given, whether or not the addressee receives it; provided, however, that notice
to the Warrant Agent or the Initial Warrant Agent shall be effective only upon
receipt.

            SECTION 6.6. Governing Law. The laws of the State of New York shall
govern this Agreement and the Warrants.

            SECTION 6.7. Successors. All agreements of the Company in this
Agreement and the Warrant Certificates shall bind its successors. All agreements
of the Warrant Agent or the Initial Warrant Agent, in this Agreement shall bind
their respective successors.

            SECTION 6.8. Multiple Originals. The parties may sign any number of
copies of this Agreement. Each signed copy shall be an original, but all of them
together represent the same agreement. One signed copy is enough to prove this
Agreement.

            SECTION 6.9. Table of Contents. The table of contents and headings
of the Articles and Sections of this Agreement have been inserted for
convenience of reference only, are not intended to be considered a part hereof
and shall not modify or restrict any of the terms or provisions hereof.

            SECTION 6.10. Severability. The provisions of this Agreement are
severable, and if any clause or provision shall be held invalid, illegal or
unenforceable in whole or in part in any jurisdiction, then such invalidity or
unenforceability shall affect in that jurisdiction only such clause or
provision, or part thereof, and shall not in any manner affect such clause or
provision in any other jurisdiction or any other clause or provision of this
Agreement in any jurisdiction.

                  [Remainder of page intentionally left blank]

<PAGE>   30

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

                                               METRICOM, INC.

                                               by   /s/ Timothy A. Dreisbach
                                                   -----------------------------
                                                   Name: Timothy A. Dreisbach
                                                   Title: President and CEO

                                               BANKBOSTON N.A.
                                                   as Warrant Agent

                                               by   /s/ Tyler Hanes
                                                   -----------------------------
                                                   Name: Tyler Hanes
                                                   Title: Managing Director

                                               BANK ONE TRUST COMPANY, N.A.
                                                   as Initial Warrant Agent

                                               by   /s/ Sandra L. Caruba
                                                   -----------------------------
                                                   Name: Sandra L. Caruba
                                                   Title: Vice President

                                       A-1

<PAGE>   31

EXHIBIT A

                       FORM OF FACE OF WARRANT CERTIFICATE

            [UNTIL THE SEPARATION DATE (AS DEFINED), THIS WARRANT HAS BEEN
ISSUED AS, AND MUST BE TRANSFERRED AS, A UNIT TOGETHER WITH THE ASSOCIATED 13%
SENIOR NOTES DUE 2010 (THE "NOTES") OF METRICOM, INC. ("THE COMPANY"), AND
METRICOM FINANCE, INC. EACH UNIT CONSISTS OF $1,000 PRINCIPAL AMOUNT OF NOTES
AND A WARRANT TO PURCHASE 4.75 SHARES OF COMMON STOCK OF THE COMPANY, SUBJECT TO
ADJUSTMENT UNDER CERTAIN CIRCUMSTANCES. A COPY OF THE WARRANT AGREEMENT PURSUANT
TO WHICH THE WARRANTS HAVE BEEN ISSUED IS AVAILABLE FROM THE COMPANY UPON
REQUEST.](1)

            [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY ("DTC"), TO THE COMPANY OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE
ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO
CEDE & CO., OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

            TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN
WHOLE, BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH
SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL SECURITY SHALL BE
LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE
WARRANT AGREEMENT REFERRED TO HEREIN.]

--------
(1) To be included on Warrants issued before the Separation Date.

                                                                             A-1

<PAGE>   32

No. Certificate for _____ Warrants

        WARRANTS TO PURCHASE COMMON STOCK OF METRICOM, INC.

            THIS CERTIFIES THAT __________, or its registered assigns, is the
registered holder of the number of Warrants set forth above (the "Warrants").
Each Warrant entitles the holder thereof (the "Holder"), at its option and
subject to the provisions contained herein and in the Warrant Agreement referred
to below, to purchase from Metricom, Inc., a Delaware corporation (the
"Company"), 4.75 shares of Common Stock, par value of $0.001 per share, of the
Company (the "Common Stock") at the per share exercise price of $87.00 (the
"Exercise Price"). This Warrant Certificate shall terminate and become void as
of the close of business on August 15, 2000 (the "Expiration Date") or upon the
exercise hereof as to all the shares of Common Stock subject hereto. The number
of shares issuable upon exercise of the Warrants and the Exercise Price per
share shall be subject to adjustment from time to time as set forth in the
Warrant Agreement.

            Each Note will be transferable only along with the corresponding
Warrant forming a unit and will not become separately transferable until the
earliest to occur of (i) August 15, 2000, (ii) an Event of Default, as defined
in the Indenture, (iii) an Exercise Event, as defined herein, or (iv) such other
date, as Lehman Brothers Inc. shall determine in its sole discretion (the
"Separation Date").

                This Warrant Certificate is issued under and in accordance with
a Warrant Agreement dated as of February 7, 2000 (the "Warrant Agreement"),
between the Company, Bank One Trust Company, N.A. (the "Initial Warrant Agent")
and BankBoston N.A. (the "Warrant Agent," which term shall refer to the Initial
Warrant Agent from the date hereof up to and excluding the Separation Date, and
therefore, to the Warrant Agent, and includes any successor Warrant Agent under
the Warrant Agreement), and is subject to the terms and provisions contained in
the Warrant Agreement, to all of which terms and provisions the Holder of this
Warrant Certificate consents by acceptance hereof. The Warrant Agreement is
hereby incorporated herein by reference and made a part hereof. Reference is
hereby made to the Warrant Agreement for a full statement of the respective
rights, limitations of rights, duties and obligations of the Company, the
Warrant Agent and the Holders of the Warrants. Capitalized terms used but not
defined herein shall have the meanings ascribed thereto in the Warrant
Agreement. A copy of the Warrant Agreement may be obtained for inspection by the
Holder hereof upon written request prior to the Separation Date to the Initial
Warrant Agent at Bank One Trust Company, N.A., One North State Street, 9th
Floor, Chicago, Illinois 60602, Telecopy No: 312-407-1708, Attention: Corporate
Trust Administration, and from the Separation Date, to the Warrant Agent at 150
Royall Street, Canton, Massachusetts 02021.

            Subject to the terms of the Warrant Agreement, the Warrants may be
exercised in whole or in part by presentation of this Warrant Certificate with
the Election to Purchase attached hereto duly executed and with the simultaneous
payment of the Exercise Price in cash (subject to adjustment) to the Warrant
Agent for the account of the Company at the office of the Warrant

<PAGE>   33

Agent. Payment of the Exercise Price in cash shall be made by certified or
official bank check payable to the order of the Company or by wire transfer of
funds to an account designated by the Company for such purpose.

        This Warrant requires the Holder to comply with certain certification
and opinion delivery requirements under certain circumstances in order to
validly exercise the Warrant.

            As provided in the Warrant Agreement and subject to the terms and
conditions therein set forth, the Warrants shall be exercisable at any time on
or after August 15, 2000, provided, however, that no Warrant shall be
exercisable after February 15, 2010.

            In the event the Company enters into a Combination, the Holder
hereof will be entitled to receive upon exercise of the Warrants the kind and
amount of shares of capital stock or other securities or other property of such
surviving entity as the Holder would have been entitled to receive upon or as a
result of the Combination had the Holder exercised its Warrants immediately
prior to such Combination; provided, however, that in the event that, in
connection with such Combination, consideration to holders of Common Stock in
exchange for their shares is payable solely in cash or in the event of the
dissolution, liquidation or winding-up of the Company, the Holder hereof will be
entitled to receive such cash distributions as the Holder would have received
had the Holder exercised its Warrants immediately prior to such Combination,
less the Exercise Price.

            As provided in the Warrant Agreement, the number of shares of Common
Stock issuable upon the exercise of the Warrants and the Exercise Price are
subject to adjustment upon the happening of certain events.

            The Company may require payment of a sum sufficient to pay all
taxes, assessments or other governmental charges in connection with the transfer
or exchange of the Warrant Certificates pursuant to Section 2.6 of the Warrant
Agreement, but not for any exchange or original issuance (not involving a
transfer) with respect to temporary Warrant Certificates, the exercise of the
Warrants or the issuance of the Warrant Shares.

            Upon any partial exercise of the Warrants, there shall be
countersigned and issued to the Holder hereof a new Warrant Certificate
representing those Warrants which were not exercised. This Warrant Certificate
may be exchanged at the office of the Warrant Agent by presenting this Warrant
Certificate properly endorsed with a request to exchange this Warrant
Certificate for other Warrant Certificates evidencing an equal number of
Warrants. No fractional Warrant Shares will be issued upon the exercise of the
Warrants, but the Company shall pay an amount in cash equal to the Current
Market Value per Warrant Share on the day immediately preceding the date the
Warrant is exercised, multiplied by the fraction of a Warrant Share that would
be issuable on the exercise of any Warrant.

            All shares of Common Stock issuable by the Company upon the exercise
of the Warrants shall, upon such issue, be duly and validly issued and fully
paid and non-assessable.

<PAGE>   34

            The holder in whose name the Warrant Certificate is registered may
be deemed and treated by the Company and the Warrant Agent as the absolute owner
of the Warrant Certificate for all purposes whatsoever and neither the Company
nor the Warrant Agent shall be affected by notice to the contrary.

            The Warrants do not entitle any holder hereof to any of the rights
of a shareholder of the Company.

            This Warrant shall be governed by the laws of the State of New York.

            This Warrant Certificate shall not be valid or obligatory for any
purpose until it shall have been countersigned by the Warrant Agent.

                                               METRICOM, INC.

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

DATED:

Countersigned:

---------------------------
as Warrant Agent,

By:
    Authorized Signatory

<PAGE>   35

                   FORM OF ELECTION TO PURCHASE WARRANT SHARES
                 (to be executed only upon exercise of Warrants)
                                 METRICOM, INC.

            The undersigned hereby irrevocably elects to exercise Warrants at an
exercise price per Warrant (subject to adjustment) of $______ to acquire _____
shares of Common Stock, par value $0.001 per share, of Metricom, Inc. on the
terms and conditions specified within the Warrant Certificate and the Warrant
Agreement therein referred to, surrenders this Warrant Certificate and all
right, title and interest therein to Metricom, Inc. and directs that the shares
of Common Stock deliverable upon the exercise of such Warrants be registered or
placed in the name and at the address specified below and delivered thereto.

Date:____________, _____

                                      ------------------------------------------
                                      (Signature of Owner)

                                      ------------------------------------------
                                      (Street Address)

                                      ------------------------------------------
                                      (City)           (State)        (Zip Code)

                                      Signature Guaranteed by:

                                      ------------------------------------------
                                      Signature must be guaranteed by an
                                      eligible Guarantor Institution (generally,
                                      banks, stock brokers, savings and
                                      loan associations and credit
                                      unions) with membership in an
                                      approved guarantee medallion
                                      program pursuant to Securities
                                      and Exchange Commission
                                      Rule 17Ad-5
--------------

     The signature must correspond with the name as written upon the face of the
     within Warrant Certificate in every particular, without alteration or
     enlargement or any change whatsoever, and must be guaranteed.

<PAGE>   36

Securities and/or check to be issued to:

Please insert social security or identifying number:

         Name:____________________________________________

         Street Address:__________________________________

         City, State and Zip Code:________________________

Any unexercised Warrants represented by the Warrant Certificate to be issued to:

         Please insert social security or identifying number:

         Name:____________________________________________

         Street Address:__________________________________

                             City, State and Zip Code:________________________

<PAGE>   37

                                   APPENDIX A

                            LIST OF FINANCIAL EXPERTS
                                ----------------

BT Alex. Brown
Bear, Stearns & Co., Inc.
Chase Securities Inc.
Credit Suisse First Boston Corporation
Donaldson, Lufkin & Jenrette Securities Corporation
ING Baring (U.S.) Securities Corporation
Goldman, Sachs & Co.
J.P. Morgan Securities Inc.
Lazard Freres & Co.
Lehman Brothers Inc.
Merrill Lynch, Pierce, Fenner & Smith Incorporated
Morgan Stanley, Dean Witter & Co. Incorporated
Oppenheimer & Co., Inc.
Prudential Securities Inc.
Salomon Smith Barney Inc.
SBC Warburg Dillon Read Inc.

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