<PAGE>   1
                                                                     EXHIBIT 4.9



                          NEXTLINK COMMUNICATIONS, INC.

                                       TO

                     UNITED STATES TRUST COMPANY OF NEW YORK
                                                                         Trustee



                                    Indenture

                            Dated as of April 1, 1998



                                  $636,974,000



                           9.45% SENIOR DISCOUNT NOTES
                                    DUE 2008



<PAGE>   2


                         NEXTLINK COMMUNICATIONS, INC.

                 Certain Sections of this Indenture relating to
                         Sections 310 through 318 of the
                          Trust Indenture Act of 1939:


<TABLE>
<CAPTION>
Trust Indenture       Indenture
  Act Section          Section
-------------------------------
<S>                                                                         <C>
Section 310(a)(1) .....................................................      609
        (a)(2) ........................................................      609
        (a)(3) ........................................................      Not Applicable
        (a)(4) ........................................................      Not Applicable
        (b) ...........................................................      608
                                                                             610
Section 311(a) ........................................................      613
        (b) ...........................................................      613
Section 312(a) ........................................................      701
        (b) ...........................................................      702
        (c) ...........................................................      702
Section 313(a) ........................................................      703
        (b) ...........................................................      703
        (c) ...........................................................      703
        (d) ...........................................................      703
Section 314(a) ........................................................      704
                                                                            1018
        (b) ...........................................................      Not Applicable
        (c)(1) ........................................................      102
        (c)(2) ........................................................      102
        (c)(3) ........................................................      Not Applicable
        (d) ...........................................................      Not Applicable
        (e) ...........................................................      102
Section 315(a) ........................................................      601
        (b) ...........................................................      602
        (c) ...........................................................      601
        (d) ...........................................................      601
        (e) ...........................................................      514
Section 316(a)(1)(A) ..................................................      502
                                                                             512
</TABLE>

<PAGE>   3


<TABLE>
<S>                                                                         <C>
        (a)(1)(B) .....................................................      513
        (a)(2) ........................................................      Not Applicable
        (b) ...........................................................      508
        (c) ...........................................................      104
Section 317(a)(1) .....................................................      503
        (a)(2) ........................................................      504
        (b) ...........................................................     1003
Section 318(a) ........................................................      107
</TABLE>



<PAGE>   4
                                      TABLE OF CONTENTS



<TABLE>
<CAPTION>
                                                                              Page
                                                                              ----
<S>                                                                           <C>
RECITALS OF THE COMPANY .................................................      1

     ARTICLE ONE Definitions and Other Provisions of General Application

SECTION 101. Definitions ................................................      1
             Act ........................................................      2
             Accreted Value .............................................      2
             Acquired Debt ..............................................      2
             Additional Interest ........................................      2
             Affiliate ..................................................      2
             Agent Member ...............................................      3
             Applicable Procedures ......................................      3
             Asset Disposition ..........................................      3
             Attributable Value .........................................      3
             Bank Credit Agreement ......................................      4
             Board of Directors .........................................      4
             Board Resolution ...........................................      4
             Business Day ...............................................      4
             Capital Lease Obligation ...................................      4
             Capital Stock ..............................................      5
             Cedel ......................................................      5
             Change of Control ..........................................      5
             Commission .................................................      5
             Common Equity ..............................................      5
             Company ....................................................      5
             Company Request ............................................      5
             Company Order ..............................................      5
             Consolidated Capital Ratio .................................      5
             Consolidated Cash Flow Available for Fixed Charges .........      6
             Consolidated Income Tax Expense ............................      6
             Consolidated Interest Expense ..............................      6
             Consolidated Net Income ....................................      7
             Consolidated Net Worth .....................................      7
             Consolidated Tangible Assets ...............................      8
             Corporate Trust Office .....................................      8
             corporation ................................................      8
             Debt .......................................................      8
             Default ....................................................      9
             Defaulted Interest .........................................      9
             Depositary .................................................      9
</TABLE>



<PAGE>   5

<TABLE>
<S>                                                                           <C>
             Disqualified Stock ........................................       9
             DTC .......................................................      10
             Eagle River ...............................................      10
             Eligible Institution ......................................      10
             Event of Default ..........................................      10
             Exchange Act ..............................................      10
             Expiration Date ...........................................      11
             Global Security ...........................................      11
             Government Securities .....................................      11
             Guarantee .................................................      11
             Holder ....................................................      12
             Incur .....................................................      12
             Indenture .................................................      12
             Interest Payment Date .....................................      12
             Interest Rate or Currency Protection Agreement ............      12
             Investment ................................................      13
             Issue Date ................................................      13
             Joint Venture .............................................      13
             Lien ......................................................      13
             Marketable Securities .....................................      13
             Maturity ..................................................      14
             Net Available Proceeds ....................................      14
             Offer to Purchase .........................................      15
             Officers' Certificate .....................................      18
             Opinion of Counsel ........................................      18
             Outstanding ...............................................      18
             Paying Agent ..............................................      19
             Permitted Interest Rate or Currency Protection Agreement ..      19
             Permitted Investment ......................................      19
             Permitted Liens ...........................................      20
             Person ....................................................      21
             Predecessor Security ......................................      21
             Preferred Dividends .......................................      21
             Preferred Stock ...........................................      21
             Purchase Agreement ........................................      21
             Purchase Date .............................................      21
             Purchase Money Debt .......................................      21
             readily marketable cash equivalents .......................      22
             Receivables ...............................................      22
             Receivables Sale ..........................................      22
             Redemption Date ...........................................      22
             Redemption Price ..........................................      23
             Regular Record Date .......................................      23
             Regulation S ..............................................      23
             Regulation S Certificate ..................................      23
</TABLE>



<PAGE>   6

<TABLE>
<S>                                                                           <C>
             Regulation S Global Security ..............................      23
             Regulation S Legend .......................................      23
             Regulation S Securities ...................................      23
             Related Person ............................................      23
             Resale Registration Statement .............................      23
             Responsible Officer .......................................      23
             Restricted Global Security ................................      24
             Restricted Period .........................................      24
             Restricted Securities .....................................      24
             Restricted Securities Certificate .........................      24
             Restricted Securities Legend ..............................      24
             Restricted Subsidiary .....................................      24
             Rule 144A .................................................      24
             Rule 144A Securities ......................................      24
             Sale and Leaseback Transaction ............................      24
             SEC Reports ...............................................      25
             Securities ................................................      25
             Securities Act ............................................      25
             Securities Act Legend .....................................      25
             Security Register .........................................      25
             Security Registrar ........................................      25
             Significant Subsidiary ....................................      25
             Special Record Date .......................................      25
             Stated Maturity ...........................................      25
             Step-Down Date ............................................      25
             Step-Up ...................................................      25
             Subordinated Debt .........................................      25
             Subsidiary ................................................      27
             Successor Security ........................................      27
             Telecommunications Assets .................................      27
             Telecommunications Business ...............................      27
             Trustee ...................................................      27
             Trust Indenture Act .......................................      28
             Unrestricted Securities Certificate .......................      28
             Unrestricted Subsidiary ...................................      28
             Vendor Financing Facility .................................      29
             Vice President ............................................      29
             Voting Stock ..............................................      29
</TABLE>



Note:   This table of contents shall not, for any purpose, be deemed to be a
        part of the Indenture.



                                      -v-

<PAGE>   7

<TABLE>
<S>                                                                           <C>
             Wholly-Owned Restricted Subsidiary ........................      29

SECTION 102. Compliance Certificates and Opinions ......................      29
SECTION 103. Form of Documents Delivered to Trustee ....................      30
SECTION 104. Acts of Holders; Record Dates .............................      31
SECTION 105. Notices, Etc., to Trustee and Company .....................      34
SECTION 106. Notice to Holders; Waiver .................................      34
SECTION 107. Application of Trust Indenture Act ........................      35
SECTION 108. Effect of Headings and Table of Contents ..................      35
SECTION 109. Successors and Assigns ....................................      35
SECTION 110. Separability Clause .......................................      35
SECTION 111. Benefits of Indenture .....................................      35
SECTION 112. Governing Law .............................................      36
SECTION 113. Legal Holidays ............................................      36

                           ARTICLE TWO Security Forms

SECTION 201. Forms Generally ...........................................      36
SECTION 202. Form of Face of Security ..................................      37
SECTION 203. Form of Reverse of Security ...............................      42
SECTION 204. Additional Provisions Required in Global Security .........      47
SECTION 205. Form of Trustee's Certificate of Authentication ...........      47

                          ARTICLE THREE The Securities

SECTION 301. Title and Terms ...........................................      48
SECTION 302. Denominations .............................................      49
SECTION 303. Execution, Authentication, Delivery and Dating ............      50
SECTION 304  Temporary Securities ......................................      51
SECTION 305. Registration, Registration of Transfer and Exchange .......      51
SECTION 306. Mutilated, Destroyed, Lost and Stolen Securities ..........      57
SECTION 307. Payment of Interest; Interest Rights Preserved ............      58
SECTION 308. Persons Deemed Owners .....................................      59
SECTION 309. Cancellation ..............................................      60
SECTION 310. Computation of Interest ...................................      60
SECTION 311. CUSIP and ISIN Numbers ....................................      60

                    ARTICLE FOUR Satisfaction and Discharge
</TABLE>



<PAGE>   8

<TABLE>
<S>                                                                           <C>
SECTION 401. Satisfaction and Discharge of Indenture ...................      61
SECTION 402. Application of Trust Money ................................      62

                             ARTICLE FIVE Remedies

SECTION 501. Events of Default .........................................      62
SECTION 502. Acceleration of Maturity; Rescission and Annulment ........      65
SECTION 503. Collection of Indebtedness and Suits for Enforcement
             by Trustee ................................................      66
SECTION 504. Trustee May File Proofs of Claim ..........................      67
SECTION 505. Trustee May Enforce Claims Without Possession of
             Securities ................................................      68
SECTION 506. Application of Money Collected ............................      68
SECTION 507. Limitation on Suits .......................................      69
SECTION 508. Unconditional Right of Holders to Receive
             Principal, Premium and Interest ...........................      69
SECTION 509. Restoration of Rights and Remedies ........................      70
SECTION 510. Rights and Remedies Cumulative ............................      70
SECTION 511. Delay or Omission Not Waiver ..............................      70
SECTION 512. Control by Holders ........................................      71
SECTION 513. Waiver of Past Defaults ...................................      71
SECTION 514. Undertaking for Costs .....................................      72
SECTION 515. Waiver of Stay or Extension Laws ..........................      72

                            ARTICLE SIX The Trustee

SECTION 601. Certain Duties and Responsibilities .......................      72
SECTION 602. Notice of Defaults ........................................      73
SECTION 603. Certain Rights of Trustee .................................      73
SECTION 604. Not Responsible for Recitals or Issuance of
             Securities ................................................      74
SECTION 605. May Hold Securities .......................................      75
SECTION 606. Money Held in Trust .......................................      75
SECTION 607. Compensation and Reimbursement ............................      75
SECTION 608. Disqualification; Conflicting Interests ...................      76
SECTION 609. Corporate Trustee Required; Eligibility ...................      76
</TABLE>



Note:   This table of contents shall not, for any purpose, be deemed to be a
        part of the Indenture.



                                     -vii-

<PAGE>   9

<TABLE>
<S>                                                                              <C>
SECTION 610. Resignation and Removal; Appointment of Successor ...........       77
SECTION 611. Acceptance of Appointment by Successor ......................       78
SECTION 612. Merger, Conversion, Consolidation or Succession to Business..       79
SECTION 613. Preferential Collection of Claims Against the Company .......       79
SECTION 614. Appointment of Authenticating Agent .........................       79

      ARTICLE SEVEN Holders' Lists and Reports by Trustee and the Company

SECTION 701. Company to Furnish Trustee Names and Addresses of Holders ...       81
SECTION 702. Preservation of Information; Communications to Holders ......       82
SECTION 703. Reports by Trustee ..........................................       82
SECTION 704. Reports by Company ..........................................       82
SECTION 705. Officers' Certificate with Respect to Change in
             Interest Rates ..............................................       83

                   ARTICLE EIGHT Merger, Consolidation, Etc.

SECTION 801. Mergers, Consolidations and Certain Sales of Assets .........       83
SECTION 802. Successor Substituted .......................................       85

                      ARTICLE NINE Supplemental Indentures

SECTION 901. Supplemental Indentures Without Consent of Holders ..........       85
SECTION 902. Supplemental Indentures with Consent of Holders .............       86
SECTION 903. Execution of Supplemental Indentures ........................       87
SECTION 904. Effect of Supplemental Indentures ...........................       87
SECTION 905. Conformity with Trust Indenture Act .........................       88
SECTION 906. Reference in Securities to Supplemental Indentures ..........       88

                             ARTICLE TEN Covenants

SECTION 1001. Payment of Principal, Premium and Interest .................       88
SECTION 1002. Maintenance of Office or Agency ............................       88
SECTION 1003. Money for Security Payments to be Held in Trust ............       89
</TABLE>



<PAGE>   10

<TABLE>
<S>                                                                             <C>
SECTION 1004. Existence ..................................................       91
SECTION 1005. Maintenance of Properties and Insurance ....................       91
SECTION 1006. Payment of Taxes and Other Claims ..........................       92
SECTION 1007. Limitation on Consolidated Debt ............................       92
SECTION 1008. Limitation on Debt and Preferred Stock of
              Restricted Subsidiaries ....................................       96
SECTION 1009. Limitation on Restricted Payments ..........................       98
SECTION 1010. Limitation on Dividend and Other Payment
              Restrictions Affecting Restricted Subsidiaries .............      101
SECTION 1011. Limitation on Liens ........................................      102
SECTION 1012. Limitation on Sale and Leaseback Transactions ..............      103
SECTION 1013. Limitation on Asset Dispositions ...........................      104
SECTION 1014. Limitation on Issuances and Sales of Capital
              Stock of Restricted Subsidiaries ...........................      106
SECTION 1015. Transactions with Affiliates and Related Persons ...........      107
SECTION 1016. Change of Control ..........................................      107
SECTION 1017. Provision of Financial Information .........................      109
SECTION 1018. Statement by Officers as to Default ........................      109
SECTION 1019. Waiver of Certain Covenants ................................      109

                    ARTICLE ELEVEN Redemption of Securities

SECTION 1101. Right of Redemption ........................................      110
SECTION 1102. Applicability of Article ...................................      111
SECTION 1103. Election to Redeem; Notice to Trustee ......................      111
SECTION 1104. Securities to Be Redeemed Pro Rata .........................      111
SECTION 1105. Notice of Redemption .......................................      112
SECTION 1106. Deposit of Redemption Price ................................      113
SECTION 1107. Securities Payable on Redemption Date ......................      113
SECTION 1108. Securities Redeemed in Part ................................      113

               ARTICLE TWELVE Defeasance and Covenant Defeasance

SECTION 1201. Company's Option to Effect Defeasance or
              Covenant Defeasance ........................................      114
</TABLE>



Note:   This table of contents shall not, for any purpose, be deemed to be a
        part of the Indenture.



                                      -ix-

<PAGE>   11

<TABLE>
<S>                                                                             <C>
SECTION 1202. Defeasance and Discharge ...................................      114
SECTION 1203. Covenant Defeasance ........................................      115
SECTION 1204. Conditions to Defeasance or Covenant Defeasance ............      115
SECTION 1205. Deposited Money and U.S. Government Obligations
              to Be Held in Trust;Other Miscellaneous Provisions .........      118
SECTION 1206. Reinstatement ..............................................      118
SECTION 1207. Repayment to Company .......................................      119
</TABLE>

ANNEX A -- Form of Regulation S Certificate
ANNEX B -- Form of Restricted Securities Certificate
ANNEX C -- Form of Unrestricted Securities Certificate

<PAGE>   12


               INDENTURE, dated as of April 1, 1998, between NEXTLINK
Communications, Inc., a corporation organized under the laws of the State of
Washington (the "Company"), having its principal office at 155 108th Avenue
N.E., 8th Floor, Bellevue, Washington 98004, and United States Trust Company of
New York, duly organized and existing under the laws of the State of New York,
as Trustee (herein called the "Trustee").

                             RECITALS OF THE COMPANY

               The Company has duly authorized the creation of an issue of
$636,974,000 aggregate principal amount of its 9.45% Senior Discount Notes Due
2008 (the "Securities") of substantially the tenor and amount hereinafter set
forth, and to provide therefor the Company has duly authorized the execution and
delivery of this Indenture. The Securities may consist of Original Securities
and/or Exchange Securities, each as defined herein. The Original Securities and
the Exchange Securities shall rank pari passu in right of payment with all
existing and future senior obligations of the Company.

               All things necessary to make the Securities, when executed by the
Company and authenticated and delivered hereunder and duly issued by the
Company, the valid obligations of the Company, and to make this Indenture a
valid agreement of the Company, in accordance with their and its terms, have
been done.

               NOW, THEREFORE, THIS INDENTURE WITNESSETH:

               For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of the Securities, as follows:


                                   ARTICLE ONE

                        Definitions and Other Provisions
                             of General Application

SECTION 101.   Definitions.

               For all purposes of this Indenture, except as otherwise expressly
provided or unless the context otherwise requires:

               (1) the terms defined in this Article have the meanings assigned
        to them in this Article and include the plural as well as the singular;



<PAGE>   13

               (2) all other terms used herein which are defined in the Trust
        Indenture Act, either directly or by reference therein, have the
        meanings assigned to them therein;

               (3) all accounting terms not otherwise defined herein have the
        meanings assigned to them in accordance with generally accepted
        accounting principles (whether or not such is indicated herein) and,
        except as otherwise herein expressly provided, the term "generally
        accepted accounting principles" with respect to any computation required
        or permitted hereunder shall mean such accounting principles as are
        generally accepted as consistently applied by the Company at the date of
        such computation; and

               (4) the words "herein", "hereof" and "hereunder" and other words
        of similar import refer to this Indenture as a whole and not to any
        particular Article, Section or other subdivision.

               Certain terms, used principally in Article Six, are defined in
that Article.

               "Act", when used with respect to any Holder, has the meaning
specified in Section 104.

               "Accreted Value" means, as of any date prior to April 15, 2003,
an amount per $1000 principal amount at maturity of Securities that is equal to
the sum of (a) the offering price ($627.97 per $1000 principal amount at
maturity of Securities) of such Securities and (b) the portion of the excess of
the principal amount of such Securities over such offering price which shall
have been amortized on a daily basis and compounded semi-annually on each April
15 and October 15 at the rate of 9.45% per annum from the date of original issue
of the Securities through the date of determination computed on the basis of a
360-day year of twelve 30-day months, and as of any date on or after April 15,
2003,the principal amount of each Security.

               "Acquired Debt" means, with respect to any specified Person, (i)
Debt of any other Person existing at the time such Person merges with or into or
consolidates with or becomes a Restricted Subsidiary of such specified Person
and (ii) Debt secured by a Lien encumbering any asset acquired by such specified
Person, which Debt was not Incurred in anticipation of, and was outstanding
prior to, such merger, consolidation or acquisition.

               "Additional Interest" has the meaning set forth in the form of
Security contained in Section 202. Unless the context otherwise requires,
references herein to "interest" on the Securities shall include Additional
Interest.



<PAGE>   14

               "Affiliate" of any specified Person means any other Person
directly or indirectly controlling or controlled by or under direct or indirect
common control with such specified Person. For the purposes of this definition,
"control" when used with respect to any specified Person means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

               "Agent Member" means any member of, or participant in, the
Depository.

               "Applicable Procedures" means, with respect to any transfer or
transaction involving a Global Security or beneficial interest therein, the
rules and procedures of the Depositary for such Security, Euroclear and Cedel,
in each case to the extent applicable to such transaction and as in effect from
time to time.

               "Asset Disposition" by the Company or any Restricted Subsidiary
means any transfer, conveyance, sale, lease or other disposition (other than a
creation of a Lien) by such Person, (including a consolidation or merger or
other sale of any such Restricted Subsidiary with, into or to another Person in
a transaction in which such Restricted Subsidiary ceases to be a Restricted
Subsidiary of the Company, but excluding a disposition by a Restricted
Subsidiary of the Company to the Company or a Restricted Subsidiary of the
Company or by the Company to a Restricted Subsidiary of the Company) of (i)
shares of Capital Stock or other ownership interests of a Restricted Subsidiary
of the Company, other than as permitted by the provisions of Section 1008 or
pursuant to a transaction in compliance with Section 801, (ii) substantially all
of the assets of the Company or any of its Restricted Subsidiaries representing
a division or line of business (other than as part of a Permitted Investment) or
(iii) other assets or rights of the Company or any of its Restricted
Subsidiaries other than (A) in the ordinary course of business or (B) that
constitutes a Restricted Payment which is permitted by the provisions of Section
1009; provided that a transaction described in clauses (i), (ii) and (iii) shall
constitute an Asset Disposition only if the aggregate consideration for such
transfer, conveyance, sale, lease or other disposition is equal to $5 million or
more in any 12month period.

               "Attributable Value" means, as to any particular lease under
which any Person is at the time liable other than a Capital Lease Obligation,
and at any date as of which the amount thereof is to be determined, the total
net amount of rent required to be paid by such Person under such lease during
the initial term thereof as determined in accordance with generally accepted
accounting principles, discounted from the last date of such initial term to the
date of 



                                      -3-
<PAGE>   15

determination at a rate per annum equal to the discount rate which would be
applicable to a Capital Lease Obligation with like term in accordance with
generally accepted accounting principles. The net amount of rent required to be
paid under any such lease for any such period shall be the aggregate amount of
rent payable by the lessee with respect to such period after excluding amounts
required to be paid on account of insurance, taxes, assessments, utility,
operating and labor costs and similar charges. In the case of any lease which is
terminable by the lessee upon the payment of penalty, such net amount shall also
include the lesser of the amount of such penalty (in which case no rent shall be
considered as required to be paid under such lease subsequent to the first date
upon which it may be so terminated) or the rent which would otherwise be
required to be paid if such lease is not so terminated. "Attributable Value"
means, as to a Capital Lease Obligation, the principal amount thereof.

               "Bank Credit Agreement" means any one or more credit agreements
(which may include or consist of revolving credits) between the Company or any
Restricted Subsidiary of the Company and one or more banks or other financial
institutions providing financing for the business of the Company and its
Restricted Subsidiaries.

               "Board of Directors" means either the board of directors of the
Company or any duly authorized committee of that Board.

               "Board Resolution" means a copy of a resolution certified by the
Secretary or an Assistant Secretary of the Company to have been duly adopted by
the Board of Directors and to be in full force and effect on the date of such
certification, and delivered to the Trustee.

               "Business Day" means each Monday, Tuesday, Wednesday, Thursday
and Friday which is not a day on which banking institutions in The Borough of
Manhattan, The City of New York, New York are authorized or obligated by law or
executive order to close.

               "Capital Lease Obligation" of any Person means the obligation to
pay rent or other payment amounts under a lease of (or other Debt arrangements
conveying the right to use) real or personal property of such Person which is
required to be classified and accounted for as a capital lease or a liability on
the face of a balance sheet of such Person in accordance with generally accepted
accounting principles (a "Capital Lease"). The stated maturity of such
obligation shall be the date of the last payment of rent or any other amount due
under such lease prior to the first date upon which such lease may be terminated
by the lessee without payment of a penalty. The principal amount of such
obligation shall be the capitalized amount thereof that would appear on the face
of a balance sheet of such Person in accordance with generally accepted
accounting principles.



<PAGE>   16

               "Capital Stock" of any Person means any and all shares,
interests, participations or other equivalents (however designated) of corporate
stock or other equity participations, including partnership interests, whether
general or limited, of such Person.

               "Cedel" means Cedel Bank, S.A. (or any successor securities
clearing agency).

               "Change of Control" has the meaning specified in Section  1016.

               "Commission" means the Securities and Exchange Commission, as
from time to time constituted, created under the Exchange Act, or, if at any
time after the execution of this instrument such Commission is not existing and
performing the duties now assigned to it under the Trust Indenture Act, then the
body performing such duties at such time.

               "Common Equity" of any Person means Capital Stock of such Person
that is not Disqualified Stock, and a "sale of Common Equity" includes any sale
of Common Equity effected by private sale or public offering.

               "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor Person shall have become such
pursuant to the applicable provisions of this Indenture and thereafter "Company"
shall mean such successor Person.

               "Company Request" or "Company Order" means a written request or
order signed in the name of the Company by (i) the Chief Executive Officer, the
President, an Executive Vice President or a Vice President of the Company, and
(ii) the Treasurer, Assistant Treasurer or Secretary of the Company, and
delivered to the Trustee.

               "Consolidated Capital Ratio" of any Person as of any date means
the ratio of (i) the aggregate consolidated principal amount of Debt (or in the
case of Debt issued at a discount the accreted amount thereof) of such Person
then outstanding (which amount of Debt shall be reduced by any amount of cash or
cash equivalent collateral securing on a perfected basis and dedicated for
disbursement exclusively to the payment of principal of and interest on such
Debt) to (ii) the aggregate consolidated Capital Stock (other than Disqualified
Stock) and paid in capital (other than in respect of Disqualified Stock) of such
Person as of such date.

               "Consolidated Cash Flow Available for Fixed Charges" for any
period means the Consolidated Net Income of the Company and its Restricted
Subsidiaries for such period increased by the sum of (i) Consolidated Interest



                                      -5-
<PAGE>   17

Expense of the Company and its Restricted Subsidiaries for such period, plus
(ii) Consolidated Income Tax Expense of the Company and its Restricted
Subsidiaries for such period, plus (iii) the consolidated depreciation and
amortization expense included in the income statement of the Company and its
Restricted Subsidiaries for such period, plus (iv) any noncash expense for such
period (excluding any noncash charge to the extent that it requires an accrual
of or a reserve for cash disbursements in any future period), plus (v) any
charge related to any premium or penalty paid in connection with redeeming or
retiring any Debt prior to its stated maturity; provided, however, that there
shall be excluded therefrom the Consolidated Cash Flow Available for Fixed
Charges (if positive) of any Restricted Subsidiary of the Company (calculated
separately for such Restricted Subsidiary in the same manner as provided above
for the Company) that is subject to a restriction which prevents the payment of
dividends or the making of distributions to the Company or another Restricted
Subsidiary of the Company to the extent of such restriction.

               "Consolidated Income Tax Expense" for any period means the
consolidated provision for income taxes of the Company and its Restricted
Subsidiaries for such period calculated on a consolidated basis in accordance
with generally accepted accounting principles.

               "Consolidated Interest Expense" means for any period the
consolidated interest expense included in a consolidated income statement
(excluding interest income) of the Company and its Restricted Subsidiaries for
such period calculated on a consolidated basis in accordance with generally
accepted accounting principles, including without limitation or duplication (or,
to the extent not so included, with the addition of), (i) the amortization of
Debt discounts; (ii) any payments or fees with respect to letters of credit,
bankers' acceptances or similar facilities; (iii) fees with respect to interest
rate swap or similar agreements or foreign currency hedge, exchange or similar
agreements; (iv) Preferred Dividends of the Company and its Restricted
Subsidiaries (other than dividends paid in shares of Preferred Stock that is not
Disqualified Stock) declared and paid or payable; (v) accrued Disqualified Stock
dividends of the Company and its Restricted Subsidiaries, whether or not
declared or paid; (vi) interest on Debt guaranteed by the Company and its
Restricted Subsidiaries; and (vii) the portion of any Capital Lease Obligation
paid or accrued during such period that is allocable to interest expense.

               "Consolidated Net Income" for any period means the consolidated
net income (or loss) of the Company and its Restricted Subsidiaries for such
period determined on a consolidated basis in accordance with generally accepted
accounting principles; provided that there shall be excluded therefrom (a) the
net income (or loss) of any Person acquired by the Company or a Restricted
Subsidiary of the Company in a pooling-of-interests transaction for any period
prior to the date of such transaction, (b) the net income (or loss) of



<PAGE>   18

any Person that is not a Restricted Subsidiary of the Company except to the
extent of the amount of dividends or other distributions actually paid to the
Company or a Restricted Subsidiary of the Company by such Person during such
period, (c) gains or losses on Asset Dispositions by the Company or its
Restricted Subsidiaries, (d) all extraordinary gains and extraordinary losses,
(e) the cumulative effect of changes in accounting principles, (f) non-cash
gains or losses resulting from fluctuations in currency exchange rates, (g) any
non-cash gain or loss realized on the termination of any employee pension
benefit plan and (h) the tax effect of any of the items described in clauses (a)
through (g) above; provided, further, that for purposes of any determination
pursuant to the provisions of Section 1009 there shall further be excluded
therefrom the net income (but not net loss) of any Restricted Subsidiary of the
Company that is subject to a restriction which prevents the payment of dividends
or the making of distributions to the Company or another Restricted Subsidiary
of the Company to the extent of such restriction.

               "Consolidated Net Worth" of any Person means the consolidated
stockholders' equity of such Person, determined on a consolidated basis in
accordance with generally accepted accounting principles, less amounts
attributable to Disqualified Stock of such Person; provided that, with respect
to the Company, adjustments following the date of this Indenture to the
accounting books and records of the Company in accordance with Accounting
Principles Board Opinions Nos. 16 and 17 (or successor opinions thereto) or
otherwise resulting from the acquisition of control of the Company by another
Person shall not be given effect to.

               "Consolidated Tangible Assets" of any Person means the total
amount of assets (less applicable reserves and other properly deductible items)
which under generally accepted accounting principles would be included on a
consolidated balance sheet of such Person and its Restricted Subsidiaries after
deducting therefrom all goodwill, trade names, trademarks, patents, unamortized
debt discount and expense and other like intangibles, which in each case under
generally accepted accounting principles would be included on such consolidated
balance sheet; provided that, with respect to the Company, adjustments following
the date of this Indenture to the accounting books and records of the Company in
accordance with Accounting Principles Board Opinions Nos. 16 and 17 (or
successor opinions thereto) or otherwise resulting from the acquisition of
control of the Company by another Person shall not be given effect to.

               "Corporate Trust Office" means the principal office of the
Trustee in the Borough of Manhattan, The City of New York, New York, at which at
any particular time its corporate trust business shall be administered, which at
the date hereof is located at 114 West 47th Street, New York, New York 10036.



                                      -7-

<PAGE>   19

               "corporation" means a corporation, association, company, limited
liability company, joint-stock company or business trust.

               "Debt" means (without duplication), with respect to any Person,
whether recourse is to all or a portion of the assets of such Person and whether
or not contingent, (i) every obligation of such Person for money borrowed, (ii)
every obligation of such Person evidenced by bonds, debentures, notes or other
similar instruments, including any such obligations Incurred in connection with
the acquisition of property, assets or businesses, (iii) every reimbursement
obligation of such Person with respect to letters of credit, bankers'
acceptances or similar facilities issued for the account of such Person, (iv)
every obligation of such Person issued or assumed as the deferred purchase price
of property or services (including securities repurchase agreements but
excluding trade accounts payable or accrued liabilities arising in the ordinary
course of business which are not overdue or which are being contested in good
faith), (v) every Capital Lease Obligation of such Person, (vi) all Receivables
Sales of such Person, together with any obligation of such Person to pay any
discount, interest, fees, indemnities, penalties, recourse, expenses or other
amounts in connection therewith, (vii) all obligations to redeem Disqualified
Stock issued by such Person, (viii) every obligation under Interest Rate or
Currency Protection Agreements of such Person and (ix) every obligation of the
type referred to in clauses (i) through (viii) of another Person and all
dividends of another Person the payment of which, in either case, such Person
has Guaranteed. The "amount" or "principal amount" of Debt at any time of
determination as used herein represented by (a) any Debt issued at a price that
is less than the principal amount at maturity thereof, shall be the amount of
the liability in respect thereof determined in accordance with generally
accepted accounting principles, (b) any Receivables Sale, shall be the amount of
the unrecovered capital or principal investment of the purchaser (other than the
Company or a Wholly-Owned Restricted Subsidiary of the Company) thereof,
excluding amounts representative of yield or interest earned on such investment,
(c) any Disqualified Stock, shall be the maximum fixed redemption or repurchase
price in respect thereof, (d) any Capital Lease Obligation, shall be determined
in accordance with the definition thereof, or (e) any Permitted Interest Rate or
Currency Protection Agreement, shall be zero. In no event shall Debt include any
liability for taxes.

               "Default" means an event that with the passing of time or the
giving of notice or both shall constitute an Event of Default.

               "Defaulted Interest" has the meaning specified in Section 307.

               "Depositary" means, with respect to the Securities issuable or
issued in whole or in part in the form of one or more Global Securities, DTC for
so long as it shall be a clearing agency registered under the Exchange Act, or



<PAGE>   20

such successor (which shall be a clearing agency registered under the Exchange
Act) as the Company shall designate from time to time in an Officers'
Certificate delivered to the Trustee.

               "Disqualified Stock" of any Person means any Capital Stock of
such Person (other than Capital Stock outstanding on the Issue Date) which, by
its terms (or by the terms of any security into which it is convertible or for
which it is exchangeable), or upon the happening of any event, matures or is
mandatorily redeemable, pursuant to a sinking fund obligation or otherwise, or
is redeemable at the option of the holder thereof, in whole or in part, on or
prior to the final Stated Maturity of the Securities; provided, however, that
any Preferred Stock which would not constitute Disqualified Stock but for
provisions thereof giving holders thereof the right to require the Company to
repurchase or redeem such Preferred Stock upon the occurrence of an asset sale
or a Change of Control occurring prior to the final Stated Maturity of the
Securities shall not constitute Disqualified Stock if the asset sale or change
of control provisions applicable to such Preferred Stock are no more favorable
to the holders of such Preferred Stock than the provisions applicable to the
Securities contained in Section 1013 or Section 1016 and such Preferred Stock
specifically provides that the Company will not repurchase or redeem any such
stock pursuant to such provisions prior to the Company's repurchase of such
Securities as are required to be repurchased pursuant to Section 1013 or Section
1016.

               "DTC" means The Depository Trust Company.

               "Eagle River" means Eagle River Investments, L.L.C., a limited
liability company formed under the laws of the State of Washington.

               "Eligible Institution" means a commercial banking institution
that has combined capital and surplus of not less than $500 million or its
equivalent in foreign currency, whose debt is rated "A3" or higher, "A" or
higher or "A" or higher according to Moody's Investors Service, Inc., Standard &
Poor's Ratings Group or Duff & Phelps Credit Rating Co. (or such similar
equivalent rating by at least one "nationally recognized statistical rating
organization" (as defined in Rule 436 under the Securities Act)) respectively,
at the time as of which any investment or rollover therein is made.

               "Eligible Receivables" means, at any time, Receivables of the
Company and its Restricted Subsidiaries, as evidenced on the most recent
quarterly consolidated balance sheet of the Company as at a date at least 45
days prior to such time arising in the ordinary course of business of the
Company or any Restricted Subsidiary of the Company.



                                      -9-

<PAGE>   21

               "Euroclear" means the Euroclear Clearance System (or any
successor securities clearing agency).

               "Event of Default" has the meaning specified in Section  501.

               "Exchange Act" means the Securities Exchange Act of 1934, as
amended (or any successor act) and the rules and regulations thereunder.

               "Exchange Offer" has the meaning set forth in the form of the
Securities contained in Section  202.

               "Exchange Registration Statement" has the meaning set forth in
the form of the Securities contained in Section 202.

               "Exchange Security" means any Security issued in exchange for an
Original Security or Original Securities pursuant to the Exchange Offer or
otherwise registered under the Securities Act and any Security with respect to
which the next preceding Predecessor Security of such Security was an Exchange
Security.

               "Expiration Date" has the meaning set forth in the definition of
"Offer to Purchase" in this Section 101.

               "Global Security" means a Security in the form prescribed in
Section 204 evidencing all or part of the Securities, issued to the Depositary
or its nominee, and registered in the name of such Depositary or its nominee.

               "Government Securities" means direct obligations of, or
obligations guaranteed by, the United States of America for the payment of which
obligations or guarantee the full faith and credit of the United States is
pledged and which have a remaining weighted average life to maturity of not more
than 18 months from the date of Investment therein.

               "Guarantee" by any Person means any obligation, contingent or
otherwise, of such Person guaranteeing, or having the economic effect of
guaranteeing, any Debt of any other Person (the "primary obligor") in any
manner, whether directly or indirectly, and including, without limitation, any
obligation of such Person, (i) to purchase or pay (or advance or supply funds
for the purchase or payment of) such Debt or to purchase (or to advance or
supply funds for the purchase of) any security for the payment of such Debt,
(ii) to purchase property, securities or services for the purpose of assuring
the holder of such Debt of the payment of such Debt, or (iii) to maintain
working capital, equity capital or other financial statement condition or
liquidity of the primary obligor so as to enable the primary obligor to pay such
Debt (and "Guaranteed", "Guaranteeing" and "Guarantor" shall have meanings
correlative to the fore-



<PAGE>   22

going); provided, however, that the Guarantee by any Person shall not include
endorsements by such Person for collection or deposit, in either case, in the
ordinary course of business; and provided, further, that the incurrence by a
Restricted Subsidiary of the Company of a lien permitted under clause (iv) of
the second paragraph of Section 1011 shall not be deemed to constitute a
Guarantee by such Restricted Subsidiary of any Purchase Money Debt of the
Company secured thereby.

               "Holder" means a Person in whose name a Security is registered in
the Security Register.

               "Incur" means, with respect to any Debt or other obligation of
any Person, to create, issue, incur (by conversion, exchange or otherwise),
assume, Guarantee or otherwise become liable in respect of such Debt or other
obligation including by acquisition of Subsidiaries or the recording, as
required pursuant to generally accepted accounting principles or otherwise, of
any such Debt or other obligation on the balance sheet of such Person (and
"Incurrence", "Incurred", "Incurrable" and "Incurring" shall have meanings
correlative to the foregoing); provided, however, that a change in generally
accepted accounting principles that results in an obligation of such Person that
exists at such time becoming Debt shall not be deemed an Incurrence of such Debt
and that neither the accrual of interest nor the accretion of original issue
discount shall be deemed an Incurrence of Debt; provided, further, however, that
the Company may elect to treat all or any portion of revolving credit debt of
the Company or a Subsidiary as being incurred from and after any date beginning
the date the revolving credit commitment is extended to the Company or a
Subsidiary, by furnishing notice thereof to the Trustee, and any borrowings or
reborrowings by the Company or a Subsidiary under such commitment up to the
amount of such commitment designated by the Company as Incurred shall not be
deemed to be new Incurrences of Debt by the Company or such Subsidiary.

               "Indenture" means this instrument as originally executed or as it
may from time to time be supplemented or amended by one or more indentures
supplemental hereto entered into pursuant to the applicable provisions hereof.

               "Interest Payment Date" means the Stated Maturity of an
installment of interest on the Securities.

               "Interest Rate or Currency Protection Agreement" of any Person
means any forward contract, futures contract, swap, option or other financial
agreement or arrangement (including, without limitation, caps, floors, collars
and similar agreements) relating to, or the value of which is dependent upon,
interest rates or currency exchange rates or indices.



                                      -11-

<PAGE>   23

               "Investment" by any Person means any direct or indirect loan,
advance or other extension of credit or capital contribution (by means of
transfers of cash or other property to others or payments for property or
services for the account or use of others, or otherwise) to, or purchase or
acquisition of Capital Stock, bonds, notes, debentures or other securities or
evidence of Debt issued by, any other Person, including any payment on a
Guarantee of any obligation of such other Person, but excluding any loan,
advance or extension of credit to an employee of the Company or any of its
Restricted Subsidiaries in the ordinary course of business, accounts receivable
and other commercially reasonable extensions of trade credit.

               "Issue Date" means the date on which the Securities are first
authenticated and delivered under this Indenture.

               "Joint Venture" means a corporation, partnership or other entity
engaged in one or more Telecommunications Businesses as to which the Company
(directly or through one or more Restricted Subsidiaries) exercises managerial
control and in which the Company owns (i) a 50% or greater interest, or (ii) a
30% or greater interest, together with options or other contractual rights,
exercisable not more than seven years after the Company's initial Investment in
such Joint Venture, to increase its interest to not less than 50%.

               "Lien" means, with respect to any property or assets, any
mortgage or deed of trust, pledge, hypothecation, assignment, Receivables Sale,
deposit arrangement, security interest, lien, charge, easement (other than any
easement not materially impairing usefulness or marketability), encumbrance,
preference, priority or other security agreement or preferential arrangement of
any kind or nature whatsoever on or with respect to such property or assets
(including, without limitation, any conditional sale or other title retention
agreement having substantially the same economic effect as any of the
foregoing).

               "Marketable Securities" means: (i) Government Securities; (ii)
any time deposit account, money market deposit and certificate of deposit
maturing not more than 365 days after the date of acquisition issued by, or time
deposit of, an Eligible Institution; (iii) commercial paper maturing not more
than 365 days after the date of acquisition issued by a corporation (other than
an Affiliate of the Company) with a rating, at the time as of which any
investment therein is made, of "P1" or higher according to Moody's Investors
Service, Inc., "A1" or higher according to Standard & Poor's Ratings Group or
"A1" or higher according to Duff & Phelps Credit Rating Co. (or such similar
equivalent rating by at least one "nationally recognized statistical rating
organization" (as defined in Rule 436 under the Securities Act)); (iv) any
banker's acceptances or money market deposit accounts issued or offered by an
Eligible Institution; (v) repurchase obligations with a term of not more than 7
days for Government Securities 



<PAGE>   24

entered into with an Eligible Institution; (vi) auction-rate preferred stocks of
any corporation maturing within 90 days after the date of acquisition by the
Company thereof, having a rating of at least AA by Standard & Poor's; and (vii)
any fund investing exclusively in investments of the types described in clauses
(i) through (vi) above.

               "Maturity", when used with respect to any Security, means the
date on which the principal of such Security becomes due and payable as therein
or herein provided, whether at the Stated Maturity or by declaration of
acceleration, call for redemption or otherwise.

               "Net Available Proceeds" from any Asset Disposition by any Person
means cash or readily marketable cash equivalents received (including by way of
sale or discounting of a note, installment receivable or other receivable, but
excluding any other consideration received in the form of assumption by the
acquiror of Debt or other obligations relating to such properties or assets)
therefrom by such Person, net of (i) all legal, title and recording tax
expenses, commissions and other fees and expenses Incurred and all federal,
state, provincial, foreign and local taxes (including taxes payable upon payment
or other distribution of funds from a foreign subsidiary to the Company or
another subsidiary of the Company) required to be accrued as a liability as a
consequence of such Asset Disposition, (ii) all payments made by such Person or
its Restricted Subsidiaries on any Debt which is secured by such assets in
accordance with the terms of any Lien upon or with respect to such assets or
which must by the terms of such Lien, or in order to obtain a necessary consent
to such Asset Disposition or by applicable law, be repaid out of the proceeds
from such Asset Disposition, (iii) all distributions and other payments made to
minority interest holders in Restricted Subsidiaries of such Person or joint
ventures as a result of such Asset Disposition, (iv) appropriate amounts to be
provided by such Person or any Restricted Subsidiary thereof, as the case may
be, as a reserve in accordance with generally accepted accounting principles
against any liabilities associated with such assets and retained by such Person
or any Restricted Subsidiary thereof, as the case may be, after such Asset
Disposition, including, without limitation, liabilities under any
indemnification obligations and severance and other employee termination costs
associated with such Asset Disposition, in each case as determined by the Board
of Directors, in its reasonable good faith judgment evidenced by a Board
Resolution filed with the Trustee; provided, however, that any reduction in such
reserve within twelve months following the consummation of such Asset
Disposition will be treated for all purposes of this Indenture and the
Securities as a new Asset Disposition at the time of such reduction with Net
Available Proceeds equal to the amount of such reduction, and (v) any
consideration for an Asset Disposition (which would otherwise constitute Net
Available Proceeds) that is required to be held in escrow pending determination
of whether a purchase price adjustment will be 



                                      -13-

<PAGE>   25

made, but amounts under this clause (v) shall become Net Available Proceeds at
such time and to the extent such amounts are released to such Person.

               "Offer to Purchase" means a written offer (the "Offer") sent by
the Company by first class mail, postage prepaid, to each Holder at his address
appearing in the Security Register on the date of the Offer offering to purchase
up to the principal amount of Securities specified in such Offer at the purchase
price specified in such Offer (as determined pursuant to this Indenture). Unless
otherwise required by applicable law, the Offer shall specify an expiration date
(the "Expiration Date") of the Offer to Purchase which shall be, subject to any
contrary requirements of applicable law, not less than 30 days or more than 60
days after the date of such Offer and a settlement date (the "Purchase Date")
for purchase of Securities within five Business Days after the Expiration Date.
The Company shall notify the Trustee at least 15 Business Days (or such shorter
period as is acceptable to the Trustee) prior to the mailing of the Offer of the
Company's obligation to make an Offer to Purchase, and the Offer shall be mailed
by the Company or, at the Company's request, by the Trustee in the name and at
the expense of the Company. The Offer shall contain information concerning the
business of the Company and its Subsidiaries which the Company in good faith
believes will enable such Holders to make an informed decision with respect to
the Offer to Purchase (which at a minimum will include (i) the most recent
annual and quarterly financial statements and "Management's Discussion and
Analysis of Financial Condition and Results of Operations" contained in the
documents required to be filed with the Trustee pursuant to this Indenture
(which requirements may be satisfied by delivery of such documents together with
the Offer), (ii) a description of material developments in the Company's
business subsequent to the date of the latest of such financial statements
referred to in clause (i) (including a description of the events requiring the
Company to make the Offer to Purchase), (iii) if applicable, appropriate pro
forma financial information concerning the Offer to Purchase and the events
requiring the Company to make the Offer to Purchase and (iv) any other
information required by applicable law to be included therein). The Offer shall
contain all instructions and materials necessary to enable such Holders to
tender Securities pursuant to the Offer to Purchase. The Offer shall also state:

               (a) the Section of this Indenture pursuant to which the Offer to
        Purchase is being made;

               (b) the Expiration Date and the Purchase Date;

               (c) the aggregate principal amount of the Outstanding Securities
        offered to be purchased by the Company pursuant to the Offer to Purchase
        (including, if less than 100%, the manner by which such has been
        determined pursuant to Section 1013 or 1016) (the "Purchase Amount");



<PAGE>   26

               (d) the purchase price to be paid by the Company for each $1,000
        aggregate principal amount of Securities accepted for payment (as
        specified pursuant to this Indenture) (the "Purchase Price");

               (e) that the Holder may tender all or any portion of the
        Securities registered in the name of such Holder and that any portion of
        a Security tendered must be tendered in an integral multiple of $1,000
        principal amount;

               (f) the place or places where Securities are to be surrendered
        for tender pursuant to the Offer to Purchase;
               (g) that interest on any Security not tendered or tendered but
        not purchased by the Company pursuant to the Offer to Purchase will
        continue to accrue;

               (h) that on the Purchase Date the Purchase Price will become due
        and payable upon each Security being accepted for payment pursuant to
        the Offer to Purchase and that interest thereon shall cease to accrue on
        and after the Purchase Date;

               (i) that each Holder electing to tender a Security pursuant to
        the Offer to Purchase will be required to surrender such Security at the
        place or places specified in the Offer prior to the close of business on
        the Expiration Date (such Security being, if the Company or the Trustee
        so requires, duly endorsed by, or accompanied by a written instrument of
        transfer in form satisfactory to the Company and the Trustee duly
        executed by, the Holder thereof or his attorney duly authorized in
        writing);

               (j) that Holders will be entitled to withdraw all or any portion
        of Securities tendered if the Company (or its Paying Agent) receives,
        not later than the close of business on the Expiration Date, a telegram,
        telex, facsimile transmission or letter setting forth the name of the
        Holder, the principal amount of the Security the Holder tendered, the
        certificate number of the Security the Holder tendered and a statement
        that such Holder is withdrawing all or a portion of his tender;

               (k) that (a) if Securities in an aggregate principal amount less
        than or equal to the Purchase Amount are duly tendered and not withdrawn
        pursuant to the Offer to Purchase, the Company shall purchase all such
        Securities and (b) if Securities in an aggregate principal amount in
        excess of the Purchase Amount are tendered and not withdrawn pursuant to
        the Offer to Purchase, the Company shall purchase Securities having an
        aggregate principal amount equal to the Purchase Amount on a pro



                                      -15-

<PAGE>   27

        rata basis (with such adjustments as may be deemed appropriate so that
        only Securities in denominations of $1,000 or integral multiples thereof
        shall be purchased);

               (l) that in the case of any Holder whose Security is purchased
        only in part, the Company shall execute, and the Trustee shall
        authenticate and deliver to the Holder of such Security without service
        charge, a new Security or Securities, of any authorized denomination as
        requested by such Holder, in an aggregate principal amount equal to and
        in exchange for the unpurchased portion of the Security so tendered; and

               (m) the CUSIP number or numbers of the Securities offered to be
        purchased by the Company pursuant to the Offer to Purchase.

Any Offer to Purchase shall be governed by and effected in accordance with the
Offer for such Offer to Purchase.

               "Officers' Certificate" means a certificate signed by (i) the
Chief Executive Officer, President, an Executive Vice President or a Vice
President, and (ii) the Treasurer, Assistant Treasurer, Secretary or an
Assistant Secretary, of the Company, and delivered to the Trustee and containing
the statements provided for in Section 102. One of the officers signing an
Officers' Certificate given pursuant to Section 1018 shall be the principal
executive, financial or accounting officer of the Company.

               "Opinion of Counsel" means a written opinion of legal counsel,
who may be counsel for the Company, and who shall be acceptable to the Trustee,
and containing the statements provided for in Section 102.

               "Original Securities" means all Securities other than Exchange
Securities.

               "Outstanding", when used with respect to Securities, means, as of
the date of determination, all Securities theretofore authenticated and
delivered under this Indenture, except:

               (i)  Securities theretofore cancelled by the Trustee or
        delivered to the Trustee for cancellation;

               (ii) Securities for whose payment or redemption money in the
        necessary amount has been theretofore deposited with the Trustee or any
        Paying Agent (other than the Company) in trust or set aside and
        segregated in trust by the Company (if the Company shall act as its own
        Paying Agent) for the Holders of such Securities; provided that, if such
        Securities are to be redeemed, 



<PAGE>   28

        notice of such redemption has been duly given pursuant to this
        Indenture; and

               (iii) Securities which have been paid pursuant to Section 306 or
        in exchange for or in lieu of which other Securities have been
        authenticated and delivered pursuant to this Indenture, other than any
        such Securities in respect of which there shall have been presented to
        the Trustee proof satisfactory to it that such Securities are held by a
        bona fide purchaser in whose hands such Securities are valid obligations
        of the Company;

provided, however, that in determining whether the Holders of the requisite
principal amount of the Outstanding Securities have given any request, demand,
authorization, direction, notice, consent or waiver hereunder, Securities owned
by the Company or any other obligor upon the Securities or any Affiliate of the
Company or of such other obligor shall be disregarded and deemed not to be
Outstanding, except that, in determining whether the Trustee shall be protected
in relying upon any such request, demand, authorization, direction, notice,
consent or waiver, only Securities which the Trustee knows to be so owned shall
be so disregarded. Securities so owned which have been pledged in good faith may
be regarded as Outstanding if the pledgee establishes to the satisfaction of the
Trustee the pledgee's right so to act with respect to such Securities and that
the pledgee is not the Company or any other obligor upon the Securities or any
Affiliate of the Company or of such other obligor.

               "Paying Agent" means any Person authorized by the Company to pay
the principal of (and premium, if any) or interest on any Securities on behalf
of the Company. The Trustee is hereby authorized by the Company to act as a
"Paying Agent" for the purposes of this Indenture, until such time as the
Company notifies the Trustee in writing that such authorization is revoked.

               "Permitted Interest Rate or Currency Protection Agreement" of any
Person means any Interest Rate or Currency Protection Agreement entered into
with one or more financial institutions in the ordinary course of business that
is designed to protect such Person against fluctuations in interest rates or
currency exchange rates with respect to Debt Incurred and which shall have a
notional amount no greater than the payments due with respect to the Debt being
hedged thereby and not for purposes of speculation.

               "Permitted Investment" means (i) any Investment in a Joint
Venture (including the purchase or acquisition of any Capital Stock of a Joint
Venture), provided the aggregate amount of all outstanding Investments pursuant
to this clause (i) in Joint Ventures in which the Company owns, directly or
indirectly, a less than 50% interest shall not exceed $25 million, (ii) any
Investment in any 



                                      -17-

<PAGE>   29

Person as a result of which such Person becomes a Restricted Subsidiary, or,
subject to the proviso to clause (i) of this definition, becomes a Joint Venture
of the Company, (iii) any Investment in Marketable Securities, (iv) Investments
in Permitted Interest Rate or Currency Protection Agreements, (v) Investments
made as a result of the receipt of noncash consideration from an Asset
Disposition that was made pursuant to and in compliance with Section 1013 of
this Indenture and (vi) other Investments in an aggregate amount not to exceed
the aggregate net proceeds received by the Company or any Restricted Subsidiary
after the date of this Indenture from the sale or liquidation of any
Unrestricted Subsidiary or any interest therein (except to the extent that any
such amount is included in the calculation of Consolidated Net Income).

               "Permitted Liens" means (a) Liens for taxes, assessments,
governmental charges or claims which are not yet delinquent or which are being
contested in good faith by appropriate proceedings, if a reserve or other
appropriate provision, if any, as shall be required in conformity with generally
accepted accounting principles shall have been made therefor; (b) other Liens
incidental to the conduct of the Company's and its Restricted Subsidiaries'
business or the ownership of its property and assets not securing any Debt, and
which do not in the aggregate materially detract from the value of the Company's
and its Restricted Subsidiaries' property or assets when taken as a whole, or
materially impair the use thereof in the operation of its business; (c) Liens
with respect to assets of a Restricted Subsidiary granted by such Restricted
Subsidiary to the Company to secure Debt owing to the Company; (d) pledges and
deposits made in the ordinary course of business in connection with workers'
compensation, unemployment insurance and other types of statutory obligations
(including to secure government contracts); (e) deposits made to secure the
performance of tenders, bids, leases, and other obligations of like nature
incurred in the ordinary course of business (exclusive of obligations for the
payment of borrowed money); (f) zoning restrictions, servitudes, easements,
rights-of-way, restrictions and other similar charges or encumbrances incurred
in the ordinary course of business which, in the aggregate, do not materially
detract from the value of the property subject thereto or interfere with the
ordinary conduct of the business of the Company or its Restricted Subsidiaries;
(g) Liens arising out of judgments or awards against the Company or any
Restricted Subsidiary with respect to which the Company or such Restricted
Subsidiary is prosecuting an appeal or proceeding for review and the Company or
such Restricted Subsidiary is maintaining adequate reserves in accordance with
generally accepted accounting principles; (h) any interest or title of a lessor
in the property subject to any lease other than a Capital Lease; and (i) any
statutory warehousemen's, materialmen's or other similar Liens for sums not then
due and payable (or which, if due and payable, are being contested in good faith
and with respect to which adequate reserves are being maintained to the extent
required by generally accepted accounting principles).



<PAGE>   30

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

               "Predecessor Security" of any particular Security means every
previous Security issued before, and evidencing all or a portion of the same
debt as that evidenced by, such particular Security; and, for the purposes of
this definition, any Security authenticated and delivered under Section 306 in
exchange for or in lieu of a mutilated, destroyed, lost or stolen Security shall
be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen
Security.

               "Preferred Dividends" for any Person means for any period the
quotient determined by dividing the amount of dividends and distributions paid
or accrued (whether or not declared) on Preferred Stock of such Person during
such period calculated in accordance with generally accepted accounting
principles, by 1 minus the maximum statutory income tax rate then applicable to
the Company (expressed as a decimal).

               "Preferred Stock" of any Person means Capital Stock of such
Person of any class or classes (however designated) that ranks prior, as to the
payment of dividends or as to the distribution of assets upon any voluntary or
involuntary liquidation, dissolution or winding up of such Person, to shares of
Capital Stock of any other class of such Person.

               "Purchase Agreement" means the Purchase Agreement, dated as of
March 27, 1998, between the Company and the Purchasers, as such agreement may be
amended from time to time.

               "Purchase Date" has the meaning set forth in the definition of
"Offer to Purchase" in this Section 101.

               "Purchase Money Debt" means (i) Acquired Debt Incurred in
connection with the acquisition of Telecommunications Assets and (ii) Debt of
the Company or of any Restricted Subsidiary of the Company (including, without
limitation, Debt represented by Bank Credit Agreements, Capital Lease
Obligations, Vendor Financing Facilities, mortgage financings and purchase money
obligations) Incurred for the purpose of financing all or any part of the cost
of construction, acquisition or improvement by the Company or any Restricted
Subsidiary of the Company or any Joint Venture of any Telecommunications Assets
of the Company, any Restricted Subsidiary of the Company or any Joint Venture,
and including any related notes, Guarantees, collateral documents, instruments
and agreements executed in connection 



                                      -19-

<PAGE>   31

therewith, as the same may be amended, supplemented, modified or restated from
time to time.

               "Purchasers" means Salomon Brothers Inc and Goldman, Sachs & Co.

               "readily marketable cash equivalents" means (i) marketable
securities issued or directly and unconditionally guaranteed by the United
States Government or issued by any agency thereof and backed by the full faith
and credit of the United States; (ii) marketable direct obligations issued by
any state of the United States of America or any political subdivision of any
such state or any public instrumentality thereof and, at the time of
acquisition, having the highest rating obtainable from either Standard & Poor's
Rating Group or Moody's Investors Service, Inc.; (iii) commercial paper maturing
no more than 180 days from the date of acquisition thereof and, at the time of
acquisition, having a rating of P-1 according to Moody's Investors Service,
Inc., "A1" or higher according to Standard & Poor's Ratings Group or "A1" or
higher according to Duff & Phelps Credit Rating Co. (or such similar equivalent
rating by at least one "nationally recognized statistical rating organization"
(as defined in Rule 436 under the Securities Act)); and (iv) certificates of
deposit or bankers' acceptance maturing within one year from the date of
acquisition thereof issued by any commercial bank organized under the laws of
the United States of America or any state thereof or the District of Columbia
having unimpaired capital and surplus of not less than $100,000,000.

               "Receivables" means receivables, chattel paper, instruments,
documents or intangibles evidencing or relating to the right to payment of money
in respect of the sale of goods or services.

               "Receivables Sale" of any Person means any sale of Receivables of
such Person (pursuant to a purchase facility or otherwise), other than in
connection with a disposition of the business operations of such Person relating
thereto or a disposition of defaulted Receivables for purpose of collection and
not as a financing arrangement.

               "Redemption Date", when used with respect to any Security to be
redeemed, means the date fixed for such redemption by or pursuant to this
Indenture.

               "Redemption Price", when used with respect to any Security to be
redeemed, means the price at which it is to be redeemed pursuant to this
Indenture.

               "Registered Securities" means the Exchange Securities and all
other Securities sold or otherwise disposed of pursuant to an effective



<PAGE>   32

registration statement under the Securities Act, together with their respective
Successor Securities.

               "Regular Record Date" for the interest payable on any Interest
Payment Date means the April 1 or October 1 (whether or not a Business Day), as
the case may be, next preceding such Interest Payment Date.

               "Regulation S" means Regulation S under the Securities Act (or
any successor provision), as it may be amended from time to time.

               "Regulation S Certificate" means a certificate substantially in
the form set forth in Annex A.

               "Regulation S Global Security" has the meaning specified in
Section 201.

               "Regulation S Legend" means a legend substantially in the form of
the legend required in the form of Security set forth in Section 202 to be
placed upon each Regulation S Security.

               "Regulation S Securities" means all Securities required pursuant
to Section 305(c) to bear a Regulation S Legend. Such term includes the
Regulation S Global Security.

               "Related Person" of any Person means any other Person directly or
indirectly owning (a) 10% or more of the Outstanding Common Equity of such
Person (or, in the case of a Person that is not a corporation, 10% or more of
the equity interest in such Person) or (b) 10% or more of the combined voting
power of the Voting Stock of such Person.

               "Resale Registration Statement" has the meaning set forth in the
Form of the Securities contained in Section 202.

               "Responsible Officer", when used with respect to the Trustee,
means the chairman or any vice-chairman of the board of directors, the chairman
or any vice-chairman of the executive committee of the board of directors, the
chairman of the trust committee, the president, any vice president, the
secretary, any assistant secretary, the treasurer, any assistant treasurer, the
cashier, any assistant cashier, any trust officer or assistant trust officer,
the controller or any assistant controller or any other officer of the Trustee
customarily performing functions similar to those performed by any of the above
designated officers and also means, with respect to a particular corporate trust
matter, any other officer to whom such matter is referred because of his
knowledge of and familiarity with the particular subject.



                                      -21-

<PAGE>   33

               "Restricted Global Security" has the meaning specified in Section
201.

               "Restricted Period" means the period of 41 consecutive days
beginning on and including the later of (i) the day on which Securities are
first offered to persons other than distributors (as defined in Regulation S) in
reliance on Regulation S and (ii) the original issuance date of the Securities.

               "Restricted Securities" means all Securities required pursuant to
Section 305(c) to bear any Restricted Securities Legend.  Such term includes the
Restricted Global Security.

               "Restricted Securities Certificate" means a certificate
substantially in the form set forth in Annex B.

               "Restricted Securities Legend" means, collectively, the legends
substantially in the forms of the legends required in the form of Security set
forth in Section 202 to be placed upon each Restricted Security.

               "Restricted Subsidiary" of the Company means any Subsidiary,
whether existing on or after the date of this Indenture, unless such Subsidiary
is an Unrestricted Subsidiary.

               "Rule 144A" means Rule 144A under the Securities Act (or any
successor provision), as it may be amended from time to time.

               "Rule 144A Securities" means the Securities purchased by the
Purchasers from the Company pursuant to the Purchase Agreement, other than the
Regulation S Securities.

               "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
shall be 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.

               "SEC Reports" has the meaning specified in Section  704.



<PAGE>   34

               "Securities" means the Exchange Securities and the Original
Securities.

               "Securities Act" means the Securities Act of 1933 and any statute
successor thereto, in each case as amended from time to time.

               "Securities Act Legend" means a Restricted Securities Legend or a
Regulation S Legend.

               "Security Register" and "Security Registrar" have the respective
meanings specified in Section  305(b).

               "Significant Subsidiary" means a Restricted Subsidiary that is a
"significant subsidiary" as defined in Rule 102(w) of Regulation SX under the
Securities Act and the Exchange Act.

               "Special Record Date" for the payment of any Defaulted Interest
means a date fixed by the Trustee pursuant to Section 307.

               "Stated Maturity", when used with respect to any Security or any
installment of interest thereon, means the date specified in such Security as
the fixed date on which the principal of such Security or such installment of
interest, as the case may be, is due and payable.

               "Step-Down Date" has the meaning set forth in the form of the
Security contained in Section 202.

               "Step-Up" has the meaning set forth in the form of the Security
contained in Section 202.

               "Subordinated Debt" means Debt of the Company as to which the
payment of principal of (and premium, if any) and interest and other payment
obligations in respect of such Debt shall be subordinate to the prior payment in
full of the Securities to at least the following extent: (i) no payments of
principal of (or premium, if any) or interest on or otherwise due in respect of
such Debt may be permitted for so long as any default in the payment of
principal (or premium, if any) or interest on the Securities exists; (ii) in the
event that any other default that with the passing of time or the giving of
notice, or both, would constitute an Event of Default exists with respect to the
Securities, upon notice by 25% or more in principal amount of the Securities to
the Trustee, the Trustee shall have the right to give notice to the Company and
the holders of such Debt (or trustees or agents therefor) of a payment blockage,
and thereafter no payments of principal of (or premium, if any) or interest on
or otherwise due in respect of such Debt may be made for a period of 179 days
from the date of 



                                      -23-

<PAGE>   35

such notice or for the period until such default has been cured or waived or
ceased to exist and any acceleration of the Securities has been rescinded or
annulled, whichever period is shorter (which Debt may provide that (A) no new
period of payment blockage may be commenced by a payment blockage notice unless
and until 360 days have elapsed since the effectiveness of the immediately prior
notice, (B) no nonpayment default that existed or was continuing on the date of
delivery of any payment blockage notice to such holders (or such agents or
trustees) shall be, or be made, the basis for a subsequent payment blockage
notice and (C) failure of the Company to make payment on such Debt when due or
within any applicable grace period, whether or not on account of such payment
blockage provisions, shall constitute an event of default thereunder); and (iii)
such Debt may not (x) provide for payments of principal of such Debt at the
stated maturity thereof or by way of a sinking fund applicable thereto or by way
of any mandatory redemption, defeasance, retirement or repurchase thereof by the
Company (including any redemption, retirement or repurchase which is contingent
upon events or circumstances, but excluding any retirement required by virtue of
acceleration of such Debt upon an event of default thereunder), in each case
prior to the final Stated Maturity of the Securities or (y) permit redemption or
other retirement (including pursuant to an offer to purchase made by the
Company) of such other Debt at the option of the holder thereof prior to the
final Stated Maturity of the Securities, other than a redemption or other
retirement at the option of the holder of such Debt (including pursuant to an
offer to purchase made by the Company) which is conditioned upon a change of
control of the Company pursuant to provisions substantially similar to those of
Section 1016 (and which shall provide that such Debt will not be repurchased
pursuant to such provisions prior to the Company's repurchase of the Securities
required to be repurchased by the Company pursuant to the provisions of Section
1016.

               "Subsidiary" of any Person means (i) a corporation more than 50%
of the combined voting power of the outstanding Voting Stock of which is owned,
directly or indirectly, by such Person or by one or more other Subsidiaries of
such Person or by such Person and one or more Subsidiaries thereof or (ii) any
other Person (other than a corporation) in which such Person, or one or more
other Subsidiaries of such Person or such Person and one or more other
Subsidiaries thereof, directly or indirectly, has at least a majority ownership
and power to direct the policies, management and affairs thereof.

               "Successor Security" of any particular Security means every
Security issued after, and evidencing all or a portion of the same debt as that
evidenced by, such particular Security; and, for the purposes of this
definition, any Security authenticated and delivered under Section 306 in
exchange for or in lieu of a mutilated, destroyed, lost or stolen Security shall
be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen
Security.



<PAGE>   36

               "Telecommunications Assets" means all assets, rights (contractual
or otherwise) and properties, whether tangible or intangible, used or intended
for use in connection with a Telecommunications Business.

               "Telecommunications Business" means the business of (i)
transmitting, or providing services relating to the transmission of, voice,
video or data through owned or leased transmission facilities, (ii) creating,
developing or marketing communications related network equipment, software and
other devices for use in a Telecommunication Business or (iii) evaluating,
participating or pursuing any other activity or opportunity that is primarily
related to those identified in (i) or (ii) above and shall, in any event,
include all businesses in which the Company or any of its Subsidiaries are
engaged on the Issue Date; provided that the determination of what constitutes a
Telecommunications Business shall be made in good faith by the Board of
Directors, which determination shall be conclusive.

               "Trustee" means the Person named as the "Trustee" in the first
paragraph of this instrument until a successor Trustee shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Trustee" shall mean such successor Trustee.

               "Trust Indenture Act" means the Trust Indenture Act of 1939 as in
force at the date as of which this instrument was executed; provided, however,
that in the event the Trust Indenture Act of 1939 is amended after such date,
"Trust Indenture Act" means, to the extent required by any such amendment, the
Trust Indenture Act of 1939 as so amended.

               "Unrestricted Securities Certificate" means a certificate
substantially in the form set forth in Annex C.

               "Unrestricted Subsidiary" means (1) any Subsidiary of the Company
designated as such by the Board of Directors as set forth below where (a)
neither the Company nor any of its other Subsidiaries (other than another
Unrestricted Subsidiary) (i) provides credit support for, or Guarantee of, any
Debt of such Subsidiary or any Subsidiary of such Subsidiary (including any
undertaking, agreement or instrument evidencing such Debt) or (ii) is directly
or indirectly liable for any Debt of such Subsidiary or any Subsidiary of such
Subsidiary, and (b) no default with respect to any Debt of such Subsidiary or
any Subsidiary of such Subsidiary (including any right which the holders thereof
may have to take enforcement action against such Subsidiary) would permit (upon
notice, lapse of time or both) any holder of any other Debt of the Company and
its Restricted Subsidiaries to declare a default on such other Debt or cause the
payment thereof to be accelerated or payable prior to its final scheduled
maturity and (2) any Subsidiary of an Unrestricted Subsidiary. The Board of
Directors 



                                      -25-

<PAGE>   37

may designate any Subsidiary to be an Unrestricted Subsidiary unless such
Subsidiary owns any Capital Stock of, or owns or holds any Lien on any property
of, any other Subsidiary of the Company which is not a Subsidiary of the
Subsidiary to be so designated or otherwise an Unrestricted Subsidiary, provided
that either (x) the Subsidiary to be so designated has total assets of $1,000 or
less or (y) immediately after giving effect to such designation, the Company
could Incur at least $1.00 of additional Debt pursuant to the first paragraph of
Section 1007 and provided, further, that the Company could make a Restricted
Payment in an amount equal to the greater of the fair market value and the book
value of such Subsidiary pursuant to Section 1009 and such amount is thereafter
treated as a Restricted Payment for the purpose of calculating the aggregate
amount available for Restricted Payments thereunder. The Board of Directors may
designate any Unrestricted Subsidiary to be a Restricted Subsidiary, provided
that if such Unrestricted Subsidiary has Debt outstanding at such time, either
(a) immediately after giving effect to such designation, the Company could Incur
at least $1.00 of additional Debt pursuant to the first paragraph of Section
1007 or (b) the Company or such Restricted Subsidiary could Incur such Debt
hereunder (other than as Acquired Debt).

               "Vendor Financing Facility" means any agreements between the
Company or a Restricted Subsidiary of the Company and one or more vendors or
lessors of equipment to the Company or any of its Restricted Subsidiaries (or
any affiliate of any such vendor or lessor) providing financing for the
acquisition by the Company or any such Restricted Subsidiary of equipment from
any such vendor or lessor.

               "Vice President", when used with respect to the Company or the
Trustee, means any vice president, whether or not designated by a number or a
word or words added before or after the title "vice president".

               "Voting Stock" of any Person means Capital Stock of such Person
which ordinarily has voting power for the election of directors (or persons
performing similar functions) of such Person, whether at all times or only so
long as no senior class of securities has such voting power by reason of any
contingency.

               "Wholly-Owned Restricted Subsidiary" of any Person means a
Restricted Subsidiary of such Person 99% or more of the outstanding Capital
Stock or other ownership interests of which (other than directors' qualifying
shares) shall at the time be owned by such Person or by one or more Wholly-Owned
Restricted Subsidiaries of such Person or by such Person and one or more
Wholly-Owned Restricted Subsidiaries of such Person.


SECTION 102.  Compliance Certificates and Opinions.



<PAGE>   38

               Upon any application or request by the Company to the Trustee to
take any action under any provision of this Indenture, the Company shall furnish
to the Trustee such certificates and opinions as may be required under the Trust
Indenture Act and under this Indenture. Each such certificate or opinion shall
be given in the form of an Officers' Certificate, if to be given by an officer
of the Company, or an Opinion of Counsel, if to be given by counsel, and shall
comply with the requirements of the Trust Indenture Act and any other
requirement set forth in this Indenture.

               Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Indenture shall include

               (1) a statement that each individual signing such certificate or
        opinion has read such covenant or condition and the definitions herein
        relating thereto;

               (2) a brief statement as to the nature and scope of the
        examination or investigation upon which the statements or opinions
        contained in such certificate or opinion are based;

               (3) a statement that, in the opinion of each such individual, he
        has made such examination or investigation as is necessary to enable him
        to express an informed opinion as to whether or not such covenant or
        condition has been complied with; and

               (4) a statement as to whether, in the opinion of each such
        individual, such condition or covenant has been complied with.


SECTION 103.  Form of Documents Delivered to Trustee.

               In any case where several matters are required to be certified
by, or covered by an opinion of, any specified Person, it is not necessary that
all such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

               Any certificate of an officer of the Company may be based,
insofar as it relates to legal matters, upon an opinion of counsel submitted
therewith, unless such officer knows, or in the exercise of reasonable care
should know, that the opinion with respect to the matters upon which his
certificate is based is 



                                      -27-

<PAGE>   39

erroneous. Any opinion of counsel may be based, insofar as it relates to factual
matters, upon a certificate of an officer or officers of the Company submitted
therewith stating the information on which counsel is relying, unless such
counsel knows, or in the exercise of reasonable care should know, that the
certificate with respect to such matters is erroneous.

               Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.


SECTION 104.  Acts of Holders; Record Dates.

               Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Indenture to be given or taken by
Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by agent duly
appointed in writing; and, except as herein otherwise expressly provided, such
action shall become effective when such instrument or instruments are delivered
to the Trustee and, where it is hereby expressly required, to the Company. Such
instrument or instruments (and the action embodied therein and evidenced
thereby) are herein sometimes referred to as the "Act" of the Holders signing
such instrument or instruments. Proof of execution of any such instrument or of
a writing appointing any such agent shall be sufficient for any purpose of this
Indenture and (subject to Section 601) conclusive in favor of the Trustee and
the Company, if made in the manner provided in this Section.

               The fact and date of the execution by any Person of any such
instrument or writing pursuant to this Section 104 may be proved by the
affidavit of a witness of such execution or by a certificate of a notary public
or other officer authorized by law to take acknowledgments of deeds, certifying
that the individual signing such instrument or writing acknowledged to him the
execution thereof. Where such execution is by a signer acting in a capacity
other than his individual capacity, such certificate or affidavit shall also
constitute sufficient proof of his authority. The fact and date of the execution
of any such instrument or writing, or the authority of the Person executing the
same, may also be proved in any other manner which the Trustee deems sufficient.

               The ownership of Securities shall be proved by the Security
Register.

               Any request, demand, authorization, direction, notice, consent,
waiver or other Act of the Holder of any Security shall bind every future Holder
of the same Security and the Holder of every Security issued upon the
registration 



<PAGE>   40

of transfer thereof or in exchange therefor or in lieu thereof in respect of
anything done, omitted or suffered to be done by the Trustee or the Company in
reliance thereon, whether or not notation of such action is made upon such
Security.

               The Company may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities entitled to give, make or take
any request, demand, authorization, direction, notice, consent, waiver or other
action provided or permitted by this Indenture to be given, made or taken by
Holders of Securities, provided that the Company may not set a record date for,
and the provisions of this paragraph shall not apply with respect to, the giving
or making of any notice, declaration, request or direction referred to in the
next paragraph. If not set by the Company prior to the first solicitation of a
Holder made by any Person in respect of any such matter referred to in the
foregoing sentence, the record date for any such matter shall be the 30th day
(or, if later, the date of the most recent list of Holders required to be
provided pursuant to Section 701) prior to such first solicitation. If any
record date is set pursuant to this paragraph, the Holders of Outstanding
Securities on such record date, and no other Holders, shall be entitled to take
the relevant action, whether or not such Holders remain Holders after such
record date; provided that no such action shall be effective hereunder unless
taken on or prior to the applicable Expiration Date by Holders of the requisite
principal amount of Outstanding Securities on such record date. Nothing in this
paragraph shall be construed to prevent the Company from setting a new record
date for any action for which a record date has previously been set pursuant to
this paragraph (whereupon the record date previously set shall automatically and
with no action by any Person be cancelled and of no effect), and nothing in this
paragraph shall be construed to render ineffective any action taken by Holders
of the requisite principal amount of Outstanding Securities on the date such
action is taken. Promptly after any record date is set pursuant to this
paragraph, the Company, at its own expense, shall cause notice of such record
date, the proposed action by Holders and the applicable Expiration Date to be
given to the Trustee in writing and to each Holder of Securities in the manner
set forth in Section 106.

               The Trustee may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities entitled to join in the giving
or making of (i) any Notice of Default, (ii) any declaration of acceleration
referred to in Section 502, (iii) any request to institute proceedings referred
to in Section 507(2) or (iv) any direction referred to in Section 512. If any
record date is set pursuant to this paragraph, the Holders of Outstanding
Securities on such record date, and no other Holders, shall be entitled to join
in such notice, declaration, request or direction, whether or not such Holders
remain Holders after such record date; provided that no such action shall be
effective hereunder unless taken on or prior to the applicable Expiration Date
by Holders of the requisite principal amount of Outstanding Securities on such
record date. Nothing in this paragraph shall be construed to prevent the Trustee
from setting a new record 



                                      -29-

<PAGE>   41

date for any action for which a record date has previously been set pursuant to
this paragraph (whereupon the record date previously set shall automatically and
with no action by any Person be cancelled and of no effect), and nothing in this
paragraph shall be construed to render ineffective any action taken by Holders
of the requisite principal amount of Outstanding Securities on the date such
action is taken. Promptly after any record date is set pursuant to this
paragraph, the Trustee, at the Company's expense, shall cause notice of such
record date, the proposed action by Holders and the applicable Expiration Date
to be given to the Company in writing and to each Holder of Securities in the
manner set forth in Section 106.

               With respect to any record date set pursuant to this Section, the
party hereto which sets such record dates may designate any day as the
"Expiration Date" and from time to time may change the Expiration Date to any
earlier or later day; provided that no such change shall be effective unless
notice of the proposed new Expiration Date is given to the other party hereto in
writing, and to each Holder of Securities in the manner set forth in Section
106, on or prior to the existing Expiration Date. If an Expiration Date is not
designated with respect to any record date set pursuant to this Section, the
party hereto which set such record date shall be deemed to have initially
designated the 180th day after such record date as the Expiration Date with
respect thereto, subject to its right to change the Expiration Date as provided
in this paragraph. Notwithstanding the foregoing, no Expiration Date shall be
later than the 180th day after the applicable record date.

               Without limiting the foregoing, a Holder entitled hereunder to
take any action hereunder with regard to any particular Security may do so with
regard to all or any part of the principal amount of such Security or by one or
more duly appointed agents each of which may do so pursuant to such appointment
with regard to all or any part of such principal amount.


SECTION 105.  Notices, Etc., to Trustee and Company.

               Any request, demand, authorization, direction, notice, consent,
waiver or Act of Holders or other document provided or permitted by this
Indenture to be made upon, given or furnished to, or filed with,

               (1) the Trustee by any Holder or by the Company shall be
        sufficient for every purpose hereunder if delivered in writing to the
        Trustee at its Corporate Trust Office, Attention: Corporate Trust
        Administration, or

               (2) the Company by the Trustee or by any Holder shall be
        sufficient for every purpose hereunder (unless otherwise herein
        expressly provided) if in writing and mailed, first-class postage
        prepaid, to the 



<PAGE>   42

        Company addressed to the Company at the address of its principal office
        specified in the first paragraph of this instrument or at any other
        address previously furnished in writing to the Trustee by the Company.


SECTION 106.  Notice to Holders; Waiver.

               Where this Indenture provides for notice to Holders of any event,
such notice shall be sufficiently given (unless otherwise herein expressly
provided) if (i) in the case of a Global Security, in writing by facsimile
and/or by overnight mail to the Depositary, and (ii) in the case of securities
other than Global Securities, in writing and mailed, first-class postage
prepaid, to each Holder affected by such event, at his address as it appears in
the Security Register, not later than the latest date (if any), and not earlier
than the earliest date (if any), prescribed for the giving of such notice. In
any case where notice to Holders is given by mail, neither the failure to mail
such notice, nor any defect in any notice so mailed, to any particular Holder
shall affect the sufficiency of such notice with respect to other Holders. Where
this Indenture provides for notice in any manner, such notice may be waived in
writing by the Person entitled to receive such notice, either before or after
the event, and such waiver shall be the equivalent of such notice. Waivers of
notice by Holders shall be filed with the Trustee, but such filing shall not be
a condition precedent to the validity of any action taken in reliance upon such
waiver.

               In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification as shall be made with the approval of the Trustee shall
constitute a sufficient notification for every purpose hereunder.


SECTION 107.  Application of Trust Indenture Act.

               The Trust Indenture Act shall apply as a matter of contract to
this Indenture for purposes of interpretation, construction and defining the
rights and obligations hereunder. If any provision hereof limits, qualifies or
conflicts with a provision of the Trust Indenture Act that is required under
such Act to be a part of and govern this Indenture, the latter provision shall
control. If any provision of this Indenture modifies or excludes any provision
of the Trust Indenture Act that may be so modified or excluded, the latter
provision shall be deemed to apply to this Indenture as so modified or to be
excluded, as the case may be.



                                      -31-

<PAGE>   43

SECTION 108.  Effect of Headings and Table of Contents.

               The Article and Section headings herein and the Table of Contents
are for convenience only and shall not affect the construction hereof.


SECTION 109.  Successors and Assigns.

               All covenants and agreements in this Indenture by the Company
shall bind its successors and assigns, whether so expressed or not.


SECTION 110.  Separability Clause.

               In case any provision in this Indenture or in the Securities
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.


SECTION 111.  Benefits of Indenture.

               Nothing in this Indenture or in the Securities, express or
implied, shall give to any Person, other than the parties hereto and their
successors hereunder and the Holders of Securities, any benefit or any legal or
equitable right, remedy or claim under this Indenture.


SECTION 112.  Governing Law.

               This Indenture and the Securities shall be governed by and
construed in accordance with the laws of the State of New York.


SECTION 113.  Legal Holidays.

               In any case where any Interest Payment Date, Redemption Date,
Purchase Date or Stated Maturity of any Security shall not be a Business Day,
then (notwithstanding any other provision of this Indenture or of the
Securities) payment of interest or principal (and premium, if any) need not be
made on such date, but may be made on the next succeeding Business Day with the
same force and effect as if made on the Interest Payment Date, Redemption Date,
Purchase Date or at the Stated Maturity, provided that no interest shall accrue
for the period from and after such Interest Payment Date, Redemption Date,
Purchase Date or Stated Maturity, as the case may be.



<PAGE>   44

                                   ARTICLE TWO

                                 Security Forms

SECTION 201.  Forms Generally.

               The Securities and the Trustee's certificates of authentication
thereof shall be in substantially the forms set forth in this Article, with such
appropriate legends, insertions, omissions, substitutions and other variations
as are required or permitted by this Indenture, and may have such letters,
numbers or other marks of identification and such legends or endorsements placed
thereon as may be required to comply with the rules of any securities exchange
or as may, consistently herewith, be determined by the officers executing such
Securities, as evidenced by their execution of the Securities.

               Upon their original issuance, Rule 144A Securities shall be
issued in the form of one or more Global Securities registered in the name of
the Depositary or its nominee and deposited with the Trustee, as custodian for
the Depositary, for credit by the Depositary to the respective accounts of
beneficial owners of the Securities represented thereby (or such other accounts
as they may direct). Such Global Securities, together with their Successor
Securities which are Global Securities other than the Regulation S Global
Security, are collectively herein called the "Restricted Global Security". Upon
their original issuance, Regulation S Securities shall be issued in the form of
one or more Global Securities registered in the name of the Depositary, or its
nominee and deposited with the Trustee, as custodian for the Depositary, for
credit to the respective accounts of the beneficial owners of the Securities
represented thereby (or such other accounts as they may direct), provided that
upon such deposit all such Securities shall be credited to or through accounts
maintained at the Depositary by or on behalf of Euroclear or Cedel. Such Global
Securities, together with their Successor Securities which are Global Securities
other than the Restricted Global Security, are collectively herein called the
"Regulation S Global Security".

               The definitive Securities shall be printed, lithographed or
engraved or produced by any combination of these methods on steel engraved
borders or may be produced in any other manner, all as determined by the
officers executing such Securities, as evidenced by their execution of such
Securities.

               In certain cases described elsewhere herein, the legends set
forth in Section 202 may be omitted from Securities issued hereunder.



                                      -33-

<PAGE>   45

SECTION 202.  Form of Face of Security.

               [If Restricted Securities, then insert -- THIS NOTE HAS NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT").
THE HOLDER HEREOF, BY PURCHASING THIS NOTE, AGREES FOR THE BENEFIT OF THE
COMPANY THAT THIS NOTE MAY NOT BE RESOLD, PLEDGED OR OTHERWISE TRANSFERRED (X)
PRIOR TO THE SECOND ANNIVERSARY OF THE ISSUANCE HEREOF (OR ANY PREDECESSOR
SECURITY HERETO) OR (Y) BY ANY HOLDER THAT WAS AN AFFILIATE OF THE COMPANY AT
ANY TIME DURING THE THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER, IN EITHER
CASE, OTHER THAN (1) TO THE COMPANY, (2) SO LONG AS THIS NOTE IS ELIGIBLE FOR
RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE 144A") TO A PERSON
WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN
THE MEANING OF RULE 144A, PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A
QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT RESALE, PLEDGE OR
OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A (3) IN AN OFFSHORE
TRANSACTION IN ACCORDANCE WITH REGULATIONS UNDER THE SECURITIES ACT, (4)
PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY
RULE 144 (IF APPLICABLE) UNDER THE SECURITIES ACT, OR (5) PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH CASE IN
ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED
STATES. THE HOLDER HEREOF, BY PURCHASING THIS NOTE REPRESENTS AND AGREES FOR THE
BENEFIT OF THE COMPANY THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER WITHIN THE
MEANING OF RULE 144A OR (2) A NON-U.S. PERSON OUTSIDE THE UNITED STATES WITHIN
THE MEANING OF (OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH (O)(2) OF
RULE 902 UNDER) REGULATIONS UNDER THE SECURITIES ACT.]

               [If a Regulation S Security, then insert -- THIS SECURITY HAS NOT
BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933 (THE "SECURITIES ACT") AND
MAY NOT BE OFFERED, SOLD OR DELIVERED IN THE UNITED STATES OR TO, OR FOR THE
ACCOUNT OR BENEFIT OF, ANY U.S. PERSON, UNLESS THIS SECURITY IS REGISTERED UNDER
THE SECURITIES ACT OR AN EXEMPTION FROM THE REGISTRATION REQUIREMENTS THEREOF IS
AVAILABLE.]

               THIS NOTE WAS ISSUED WITH ORIGINAL ISSUE DISCOUNT. FOR PURPOSES
OF SECTIONS 1272, 1273 AND 1275 OF THE UNITED STATES INTERNAL REVENUE CODE OF
1986, AS AMENDED, THE ISSUE 



<PAGE>   46

PRICE OF THIS SECURITY IS 62.797% OF ITS PRINCIPAL AMOUNT, THE AMOUNT OF
ORIGINAL ISSUE DISCOUNT IS $372.03 PER $1000 OF STATED FACE AMOUNT, THE ISSUE
DATE IS APRIL 1, 1998 AND THE YIELD TO MATURITY IS 9.45%.

                          NEXTLINK Communications, Inc.

                      9.45% SENIOR DISCOUNT NOTES DUE 2008


[IF RESTRICTED GLOBAL SECURITY - CUSIP NO. ________]
[IF ANY REGULATION S SECURITY - CUSIP NO. ________]
[IF REGULATION S GLOBAL SECURITY - ISIN NO. - __________]


No. ______     $_______________

               NEXTLINK Communications, Inc., a corporation organized under the
laws of the State of Washington (herein called the "Company", which term
includes any successor Person under the Indenture hereinafter referred to), for
value received, hereby promises to pay to Cede & Co., or registered assigns, the
principal sum of _____________ Dollars [if this Security is a Global Security,
then insert: (which principal amount may from time to time be increased or
decreased to such other principal amounts (which, taken together with the
principal amounts of all other Outstanding Securities, shall not exceed
$636,974,000 in the aggregate at any time) by adjustments made on the records of
the Trustee hereinafter referred to in accordance with the Indenture)] on April
15, 2008, and to pay interest thereon from April 15, 2003 or from the most
recent Interest Payment Date to which interest has been paid or duly provided
for, semi-annually on April 15 and October 15 in each year, commencing October
15, 2003 at the rate of 9.45% per annum, until the principal hereof is paid or
made available for payment. [If Original Securities, then insert: provided,
however, that if (i) the Company has not filed a registration statement (the
"Exchange Registration Statement") under the Securities Act of 1933, as amended
(the "Securities Act"), registering a security substantially identical to this
Security (except that such Security will not contain terms with respect to the
Additional Interest payments described below or transfer restrictions) pursuant
to an exchange offer (the "Exchange Offer") (or, in lieu thereof, a registration
statement registering this Security for resale (a "Resale Registration
Statement")) by June 30, 1998, or (ii) the Exchange Registration Statement
relating to the Exchange Offer or, if applicable, the Resale Registration
Statement has not become or been declared effective by July 30, 1998, or (iii)
the Exchange Offer has not been completed within 45 days after the date on which
the Exchange Registration Statement has become or been declared effective
initially (if the 



                                      -35-

<PAGE>   47

Exchange Offer is then required to be made pursuant to the Exchange and
Registration Rights Agreement (the "Exchange and Registration Rights
Agreement"), dated as of April 1, 1998, by and between the Company, the
Purchasers (as defined therein) and the Holders from time to time of the
Securities) or (iv) either the Exchange Registration Statement or, if
applicable, the Resale Registration Statement is filed and declared effective
(except as specifically permitted therein) but shall thereafter cease to be
effective without being succeeded promptly by an additional registration
statement filed and declared effective, in each case (i) through (iv) upon the
terms and conditions set forth in the Exchange and Registration Rights Agreement
(each such event referred to in clauses (i) through (iv), a "Registration
Default"), then interest will accrue (in addition to the original issue discount
and any stated interest on the Securities) (the "Step-Up") at a rate of 0.5% per
annum, determined daily, on the Accreted Value of the Securities (or after April
15, 2003 on the principal amount of the Securities), from the period from the
occurrence of the Registration Default until such time (the "Step-Down Date") as
no Registration Default is in effect and, provided, further, that if either the
Exchange Offer has not been consummated or, if applicable, the Resale
Registration Statement has not become or been declared effective, in each case
by September 13, 1998, then the per annum rate of such Additional Interest shall
increase (the "Subsequent StepUp") by an additional 0.25% per annum for each
subsequent 90day period (provided that the Step-Up and all Subsequent Step-Up
interest rates shall not exceed 1.0% per annum in the aggregate) and Additional
Interest will be payable at such increased rate until such time (the "Subsequent
Step Down Date") as the Company consummates the Exchange Offer or, if
applicable, the Resale Registration Statement becomes or has been declared
effective (after which such interest rate will be restored to its initial rate).
Interest accruing as a result of the StepUp or the Subsequent StepUp (which
shall be computed on the basis of a 365-day year) is referred to herein as
"Additional Interest." Accrued Additional Interest, if any, shall be paid
semi-annually on April 15 and October 15, in each year; and the amount of
accrued Additional Interest shall be determined on the basis of the number of
days actually elapsed. Any accrued and unpaid interest (including Additional
Interest) on this Security upon the issuance of an Exchange Security (as defined
in the Indenture) in exchange for this Security shall cease to be payable to the
Holder hereof but such accrued and unpaid interest (including Additional
Interest) shall be payable on the next Interest Payment Date for such Exchange
Security to the Holder thereof on the related Regular Record Date.] The interest
so payable, and punctually paid or duly provided for, on any Interest Payment
Date will, as provided in such Indenture, be paid to the Person in whose name
this Security (or one or more Predecessor Securities) is registered at the close
of business on the Regular Record Date for such interest, which shall be April 1
or October 1 (whether or not a Business Day), as the case may be, next preceding
such Interest Payment Date. Any such interest not so punctually paid or duly
provided for will forthwith cease to be payable to the Holder on such Regular
Record Date and may either 



<PAGE>   48

be paid to the Person in whose name this Security (or one or more Predecessor
Securities) is registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest to be fixed by the Trustee, notice
whereof shall be given to Holders of Securities not less than 10 days prior to
such Special Record Date, or be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange on which the
Securities may be listed, and upon such notice as may be required by such
exchange, all as more fully provided in said Indenture.

               The principal of this Security shall not accrue interest (other
than Additional Interest, if any) until April 15, 2003, except in the case of a
default in payment of principal and premium, if any, upon acceleration or
redemption, in which case interest shall be payable pursuant to the preceding
paragraph on such overdue principal (and premium, if any), such interest shall
be payable on demand and, if not so paid on demand, such interest shall itself
bear interest at the rate of 9.45% per annum (to the extent that the payment of
such interest shall be legally enforceable), and shall accrue from the date of
such demand for payment to the date payment of such interest has been made or
duly provided for, and such interest on unpaid interest shall also be payable on
demand.

               If this Security is issued in the form of a Global Security,
payments of the principal of (and premium, if any) and interest on this Security
shall be made in immediately available funds to the Depositary. If this Security
is issued in certificated form, payment of the principal of (and premium, if
any) and interest on this Security will be made at the corporate trust office of
the Trustee and at the office or agency of the Company maintained for that
purpose in the Borough of Manhattan, The City of New York, New York, and at any
other office or agency maintained by the Company for such purpose, in such coin
or currency of the United States of America as at the time of payment is legal
tender for payment of public and private debts; provided, however, that at the
option of the Company payment of interest may be made by check mailed to the
address of the Person entitled thereto as such address shall appear in the
Security Register.

               Reference is hereby made to the further provisions of this
Security set forth on the reverse hereof, which further provisions shall for all
purposes have the same effect as if set forth at this place.

               Unless the certificate of authentication hereon has been executed
by the Trustee referred to on the reverse hereof by manual signature, this
Security shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

               IN WITNESS WHEREOF, the Company has caused this instrument to be
duly executed.



                                      -37-

<PAGE>   49

Dated:

                                    NEXTLINK Communications, Inc.


                                    By__________________________________
                                      Name:
                                      Title:
Attest:


______________________________
Name:
Title:

SECTION 203.  Form of Reverse of Security.

               This Security is one of a duly authorized issue of Securities of
the Company designated as its 9.45% Senior Discount Notes Due 2008 (the
"Securities") issued under an Indenture, dated as of April 1, 1998 (herein
called the "Indenture"), between the Company and United States Trust Company of
New York, as trustee (herein called the "Trustee", which term includes any
successor trustee under the Indenture). The Securities are limited in aggregate
principal amount to $636,974,000. Reference is hereby made to the Indenture and
all indentures supplemental thereto for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Company, the
Trustee and the Holders of the Securities and of the terms upon which the
Securities are, and are to be, authenticated and delivered.

               The Securities are subject to redemption upon not less than 30
nor more than 60 days' notice by mail to each Holder of Securities to be
redeemed at such Holder's address appearing in the Security Register, in amounts
of $1,000 or an integral multiple of $1,000, at any time on or after April 15,
2003 and prior to maturity, as a whole or in part, at the election of the
Company, at the following Redemption Prices (expressed as percentages of the
principal amount) plus accrued and unpaid interest to but excluding the
Redemption Date (subject to the right of Holders of record on the relevant
Regular Record Date to receive interest due on an Interest Payment that is on or
prior to the Redemption Date), if redeemed during the 12-month period beginning
April 15, of each of the years indicated below:

<TABLE>
<CAPTION>
                                Year                        Redemption
                                ----                           Price
                                                            -----------
<S>                                                         <C>     
                                2003                         104.725%
                                2004                         103.150%
</TABLE>




<PAGE>   50

<TABLE>
<S>                                                          <C>     
                                2005                         101.575%
</TABLE>

and thereafter at a Redemption Price equal to 100.000% of the principal amount,
together in the case of any such redemption with accrued interest to the
Redemption Date, but interest installments whose Stated Maturity is on or prior
to such Redemption Date will be payable to the Holders of such Securities, or
one or more Predecessor Securities, of record at the close of business on the
relevant Record Dates referred to on the face hereof, all as provided in the
Indenture.

               The Securities are further subject to redemption prior to April
15, 2003 only in the event that on or before April 15, 2001 the Company receives
net proceeds from a sale of its Common Equity, in which case the Company may, at
its option, use all or a portion of any such net proceeds to redeem Securities
in a principal amount of up to an aggregate amount equal to 33 % of the original
principal amount of the Securities, provided, however, that Securities in an
amount equal to at least 66 % of the original aggregate principal amount of the
Securities remain Outstanding after such redemption. Such redemption must occur
on a Redemption Date within 90 days of any such sale and upon not less than 30
nor more than 60 days' notice by mail to each Holder of Securities to be
redeemed at such Holder's address appearing in the Security Register, in amounts
of $1,000 or an integral multiple of $1,000 at a Redemption Price of 109.450% of
the Accreted Value of the Securities to be redeemed to but excluding the
Redemption Date.

               In the event of redemption of this Security in part only, a new
Security or Securities for the unredeemed portion hereof will be issued in the
name of the Holder hereof upon the cancellation hereof.

               The Securities do not have the benefit of any sinking fund
obligations.

               The Indenture provides that, subject to certain conditions, if
(i) a Change of Control occurs or (ii) certain Net Available Proceeds are
available to the Company as a result of any Asset Disposition, the Company shall
be required to make an Offer to Purchase for all or a specified portion of the
Securities.

               [If not a Global Security -- In the event of redemption or
purchase pursuant to an Offer to Purchase of this Security in part only, a new
Security or Securities of like tenor for the unredeemed or unpurchased portion
hereof will be issued in the name of the Holder hereof upon the cancellation
hereof.]

               [If a Global Security insert -- In the event of a deposit or
withdrawal of an interest in this Security (including upon an exchange,
transfer, 



                                      -39-

<PAGE>   51

redemption or repurchase of this Security in part only) effected in accordance
with the Applicable Procedures, the Security Registrar, upon receipt of notice
of such event from the Depositary's custodian for this Security, shall make an
adjustment on its records to reflect an increase or decrease of the Outstanding
principal amount of this Security resulting from such deposit or withdrawal, as
the case may be.]

               If an Event of Default shall occur and be continuing, the
principal of all the Securities may be declared due and payable in the manner
and with the effect provided in the Indenture.

               The Indenture contains provisions for defeasance at any time of
(i) the entire indebtedness of this Security, or (ii) certain restrictive
covenants and Events of Default with respect to this Security, in each case upon
compliance with certain conditions set forth therein.

               Unless the context otherwise requires, the Original Securities
(as defined in the Indenture) and the Exchange Securities (as defined in the
Indenture) shall constitute one series for all purposes under the Indenture,
including without limitation, amendments, waivers, redemptions and Offers to
Purchase.

               The Indenture permits, with certain exceptions as therein
provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Securities under
the Indenture at any time by the Company and the Trustee with the consent of the
Holders of a majority in aggregate principal amount of the Securities at the
time Outstanding. The Indenture also contains provisions permitting the Holders
of specified percentages in aggregate principal amount of the Securities at the
time Outstanding, on behalf of the Holders of all the Securities, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Security shall be conclusive and binding upon such
Holder and upon all future Holders of this Security and of any Security issued
upon the registration of transfer hereof or in exchange herefor or in lieu
hereof, whether or not notation of such consent or waiver is made upon this
Security.

               As provided in and subject to the provisions of the Indenture,
the Holder of this Security shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default, the Holders of not
less than 25% in principal amount of the Outstanding Securities shall have made
written request to the Trustee to institute proceedings in respect of such Event
of Default as Trustee and offered the Trustee reasonable indemnity, and the



<PAGE>   52

Trustee shall not have received from the Holders of a majority in principal
amount of Outstanding Securities a direction inconsistent with such request, and
shall have failed to institute any such proceeding, for 60 days after receipt of
such notice, request and offer of indemnity. The foregoing shall not apply to
any suit instituted by the Holder of this Security for the enforcement of any
payment of principal hereof or any premium or interest hereon on or after the
respective due dates expressed herein.

               No reference herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of (and
premium, if any) and interest on this Security at the times, place and rate, and
in the coin or currency, herein prescribed.

               As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for registration of transfer at the
office or agency of the Company in the Borough of Manhattan, The City of New
York, New York, duly endorsed by, or accompanied by a written instrument of
transfer in form satisfactory to the Company and the Security Registrar duly
executed by, the Holder hereof or his attorney duly authorized in writing, and
thereupon one or more new Securities, of authorized denominations and like tenor
and for the same aggregate principal amount, will be issued to the designated
transferee or transferees.

               The Securities are issuable only in registered form without
coupons in denominations of $1,000 and any integral multiple thereof. As
provided in the Indenture and subject to certain limitations therein set forth,
Securities are exchangeable for a like tenor and aggregate principal amount of
Securities of a different authorized denomination, as requested by the Holder
surrendering the same.

               No service charge shall be made for any such registration of
transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith.

               Prior to due presentment of this Security for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Security is registered as the owner
hereof for all purposes, whether or not this Security be overdue, and none of
the Company, the Trustee or any such agent shall be affected by notice to the
contrary.



                                      -41-

<PAGE>   53

               Interest [If an Original Security, then insert: (other than
Additional Interest)] on this Security shall be computed on the basis of a
360-day year of twelve 30-day months.

               All terms used in this Security which are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                          OPTION OF HOLDER TO ELECT PURCHASE

               If you want to elect to have this Security purchased in its
entirety by the Company pursuant to Section 1013 or 1016 of the Indenture, check
the box:



               If you want to elect to have only a part of this Security
purchased by the Company pursuant to Section 1013 or 1016 of the Indenture,
state the amount:
$___________


Dated:________________           Your Signature _______________________________
                                 (Sign exactly as name appears on the other side
                                 of this Security)




Signature Guarantee:____________________________________________________________
                    Notice: Signature(s) must be guaranteed by an "eligible
                    guarantor institution" meeting the requirements of the
                    Trustee, which requirements will include membership or
                    participation in STAMP or such other "signature guarantee
                    program" as may be determined by the Trustee in addition to,
                    or in substitution for STAMP, all in accordance with the
                    Securities Exchange Act of 1934, as amended.



SECTION 204.   Additional Provisions Required in Global Security.

               Any Global Security issued hereunder shall, in addition to the
provisions contained in Sections 202 and 203, bear a legend in substantially the
following form:



<PAGE>   54

               [If a Global Security, insert -- THIS SECURITY IS A GLOBAL
SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS
REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY MAY
NOT BE EXCHANGED IN WHOLE OR IN PART FOR A SECURITY REGISTERED, AND NO TRANSFER
OF THIS SECURITY IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY
PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED
CIRCUMSTANCES DESCRIBED IN THE INDENTURE.]

               [If a Global Security to be held by the Depository Trust Company,
insert -- UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY SECURITY
ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN 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 A PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE
& CO., HAS AN INTEREST HEREIN.]

SECTION 205.  Form of Trustee's Certificate of
                   Authentication.

               This is one of the Securities referred to in the within-mentioned
Indenture.


                       United States Trust Company of New  York,
                                                                      as Trustee


                                             By ________________________________
                                                Authorized Signatory



                                      -43-

<PAGE>   55

                                  ARTICLE THREE

                                 The Securities

SECTION 301.  Title and Terms.

               The aggregate principal amount of Securities which may be
authenticated and delivered under this Indenture is limited to $636,974,000,
except for Securities authenticated and delivered upon registration of transfer
of, or in exchange for, or in lieu of, other Securities pursuant to Section 304,
305, 306, 906 or 1108 or in connection with an Offer to Purchase pursuant to
Section 1013 or 1016.


               The Company may issue Exchange Securities from time to time
pursuant to an Exchange Offer or otherwise, in each case pursuant to a Board
Resolution, subject to Section 303, included in an Officers' Certificate
delivered to the Trustee, in authorized denominations in exchange for a like
principal amount of Original Securities. Upon any such exchange the Original
Securities shall be canceled in accordance with Section 309 and shall no longer
be deemed Outstanding for any purpose. In no event shall the aggregate principal
amount of Original Securities and Exchange Securities Outstanding exceed
$636,974,000.

               The Securities shall be known and designated as the "9.45% Senior
Discount Notes Due 2008" of the Company. The Stated Maturity of the Securities
shall be April 15, 2008. The Securities shall bear interest at the rate of 9.45%
per annum, from April 15, 2003 or from the most recent Interest Payment Date
thereafter to which interest has been paid or duly provided for, as the case may
be, payable semi-annually on April 15 and October 15, commencing October 15,
2003, until the principal thereof is paid or made available for payment;
provided, however, with respect to Original Securities, if there has been a
Registration Default, a Step-Up will occur and the Original Securities will from
then bear Additional Interest until the Step-Down Date and, if either the
Exchange Offer has not been consummated or, if applicable, the Resale
Registration Statement has not become or been declared effective, in each case,
by September 13, 1998, a Subsequent Step-Up will occur and the Original
Securities will from then bear Additional Interest until the Subsequent
Step-Down Date. Accrued Additional Interest, if any, shall be paid in cash in
arrears semi-annually on April 15 and October 15 in each year, and the amount of
accrued Additional Interest shall be determined on the basis of the number of
days actually elapsed. In connection with the cash payment of any Additional
Interest, the Company shall notify the Trustee (the "Additional Interest
Notice") on or before the later to occur of (i) the Regular Record Date
preceding such payment 



<PAGE>   56

of any Additional Interest, and (ii) the date on which any such Additional
Interest begins to accrue, of the amount of Additional Interest to be paid by
the Company on the next Interest Payment Date. In the event of the occurrence of
a Step-Down Date during the period between the date on which the Additional
Interest Notice is given and the next Interest Payment Date, the Company shall
so notify the Trustee and shall provide the Trustee with the revised amount of
Additional Interest to be paid by the Company on such Interest Payment Date.

               In the case of a default in payment of principal and premium, if
any, upon acceleration or redemption, interest shall be payable pursuant to the
preceding paragraph on such overdue principal (and premium, if any), such
interest shall be payable on demand and, if not so paid on demand, such interest
shall itself bear interest at the rate of 1% per annum (to the extent that the
payment of such interest shall be legally enforceable), and shall accrue from
the date of such demand for payment to the date payment of such interest has
been made or duly provided for, and such interest on unpaid interest shall also
be payable on demand.

               The principal of and premium, if any, and interest on the
Securities shall be payable at the corporate trust office of the Trustee in the
Borough of Manhattan, The City of New York, New York, maintained for such
purpose and at any other office or agency maintained by the Company for such
purpose; provided, however, that at the option of the Company payment of
interest may be made by check mailed to the address of the Person entitled
thereto as such address shall appear in the Security Register.

               The Securities shall be subject to repurchase by the Company
pursuant to an Offer to Purchase as provided in Sections 1013 and 1016.

               The Securities shall be redeemable as provided in Article Eleven.

               The Securities shall not have the benefit of any sinking fund
obligations.

               The Securities shall be subject to defeasance at the option of
the Company as provided in Article Twelve.

               Unless the context otherwise requires, the Original Securities
and the Exchange Securities shall constitute one series for all purposes under
the Indenture, including without limitation, amendments, waivers, redemptions
and Offers to Purchase.



                                      -45-

<PAGE>   57

SECTION 302.  Denominations.

               The Securities shall be issuable only in registered form without
coupons and only in denominations of $1,000 and any integral multiple thereof.

SECTION 303.  Execution, Authentication, Delivery
                   and Dating.

               The Securities shall be executed on behalf of the Company by its
Chief Executive Officer, its President, its Executive Vice President or one of
its Vice Presidents and attested by its Secretary. The signature of any of these
officers on the Securities may be manual or facsimile.

               Securities bearing the manual or facsimile signatures of
individuals who were at any time the proper officers of the Company shall bind
the Company, notwithstanding that such individuals or any of them have ceased to
hold such offices prior to the authentication and delivery of such Securities or
did not hold such offices at the date of such Securities.

               At any time and from time to time after the execution and
delivery of this Indenture, the Company may deliver Securities executed by the
Company to the Trustee for authentication, together with a Company Order for the
authentication and delivery of such Securities; and the Trustee in accordance
with such Company Order shall authenticate and deliver such Securities as in
this Indenture provided and not otherwise.

               At any time and from time to time after the execution and
delivery of this Indenture and after the effectiveness of a Registration
Statement under the Securities Act with respect thereto, the Company may deliver
Exchange Securities executed by the Company to the Trustee for authentication,
together with a Company Order for the authentication and delivery of such
Exchange Securities and a like principal amount of Original Securities for
cancellation in accordance with Section 309 of this Indenture, and the Trustee
in accordance with the Company Order shall authenticate and deliver such
Securities. In authenticating such Exchange Securities, and accepting the
additional responsibilities under this Indenture in relation to such Securities,
the Trustee shall be entitled to receive, and (subject to Section 601) shall be
fully protected in relying upon, an Opinion of Counsel stating,

               (a) that such Exchange Securities have been duly and validly
        issued in accordance with the terms of the Indenture, and are entitled
        to all the rights and benefits set forth herein; and



<PAGE>   58

               (b) that the issuance of the Exchange Securities in exchange for
        the Original Securities has been effected in compliance with the
        Securities Act of 1933, as amended.

               Each Security shall be dated the date of its authentication.

               No Security shall be entitled to any benefit under this Indenture
or be valid or obligatory for any purpose unless there appears on such Security
a certificate of authentication substantially in the form provided for herein
executed by the Trustee by manual signature, and such certificate upon any
Security shall be conclusive evidence, and the only evidence, that such Security
has been duly authenticated and delivered hereunder.

SECTION 304.  Temporary Securities.

               Pending the preparation of definitive Securities, the Company may
execute, and upon a Company Order the Trustee shall authenticate and deliver,
temporary Securities which are printed, lithographed, typewritten, mimeographed
or otherwise produced, in any authorized denomination, substantially of the
tenor of the definitive Securities in lieu of which they are issued and with
such appropriate insertions, omissions, substitutions and other variations as
the officers executing such Securities may determine, as evidenced by their
execution of such Securities.

               If temporary Securities are issued, the Company will cause
definitive Securities to be prepared without unreasonable delay. After the
preparation of definitive Securities, the temporary Securities shall be
exchangeable for definitive Securities upon surrender of the temporary
Securities at any office or agency of the Company designated pursuant to Section
1002, without charge to the Holder. Upon surrender for cancellation of any one
or more temporary Securities, the Company shall execute and the Trustee shall
authenticate and deliver in exchange therefor a like tenor and principal amount
of definitive Securities of authorized denominations. Until so exchanged, the
temporary Securities shall in all respects be entitled to the same benefits
under this Indenture as definitive Securities.



                                      -47-

<PAGE>   59

SECTION 305.  Registration, Registration of Transfer and Exchange.

               (a) The Company shall cause to be kept at the Corporate Trust
Office of the Trustee a register (the register maintained in such office and in
any other office or agency designated pursuant to Section 1002 being herein
sometimes collectively referred to as the "Security Register") in which, subject
to such reasonable regulations as they may prescribe, the Company shall provide
for the registration of Securities and of transfers and exchanges of Securities.
The Trustee is hereby appointed "Security Registrar" for the purpose of
registering Securities and transfers and exchanges of Securities as herein
provided. Such Security Register shall distinguish between Original Securities
and Exchange Securities.

               Subject to the other provisions of this Indenture regarding
restrictions on transfer, upon surrender for registration of transfer of any
Security at an office or agency of the Company designated pursuant to Section
1002 for such purpose in accordance with the terms hereof, the Company shall
execute, and the Trustee shall authenticate and deliver, in the name of the
designated transferee or transferees, one or more new Securities of any
authorized denominations and of a like tenor and aggregate principal amount and
bearing such restrictive legends as may be required by this Indenture.

               At the option of the Holder and subject to the other provisions
of this Section 305, Securities may be exchanged for other Securities of any
authorized denominations and of a like tenor and aggregate principal amount,
upon surrender of the Securities to be exchanged at such office or agency.
Whenever any Securities are so surrendered for exchange, the Company shall
execute, and the Trustee shall authenticate and deliver, the Securities which
the Holder making the exchange is entitled to receive.

               All Securities issued upon any registration of transfer or
exchange of Securities shall be the valid obligations of the Company, evidencing
the same debt, and (subject to the provisions in the Original Securities
regarding the payment of Additional Interest) entitled to the same benefits
under this Indenture, as the Securities surrendered upon such registration of
transfer or exchange.

               Every Security presented or surrendered for registration of
transfer or for exchange shall (if so required by the Company or the Trustee) be
duly endorsed, or be accompanied by a written instrument of transfer in form
satisfactory to the Company and the Security Registrar duly executed, by the
Holder thereof or his attorney duly authorized in writing.



<PAGE>   60

               No service charge shall be made to the Holder for any
registration of transfer or exchange of Securities, but the Company may require
payment of a sum sufficient to cover any tax or other governmental charge that
may be imposed in connection with any registration of transfer or exchange of
Securities, other than exchanges pursuant to Section 304, 305, 906 or 1108 or in
accordance with any Offer to Purchase pursuant to Section 1013 or 1016 not
involving any transfer.

               The Company shall not be required (i) to issue, register the
transfer of or exchange any Security during a period beginning at the opening of
business 15 days before the day of the mailing of a notice of redemption of
Securities selected for redemption under Section 1104 and ending at the close of
business on the day of such mailing, or (ii) to register the transfer of or
exchange any Security so selected for redemption in whole or in part, except the
unredeemed portion of any Security being redeemed in part.

               (b) Certain Transfers and Exchanges. Notwithstanding any other
provision of this Indenture or the Securities, transfers and exchanges of
Securities and beneficial interests in a Global Security of the kinds specified
in this Section 305(b) shall be made only in accordance with this Section
305(b).

                      (i) Restricted Global Security to Regulation S Global
        Security. If the owner of a beneficial interest in the Restricted Global
        Security wishes at any time to transfer such interest to a Person who
        wishes to acquire the same in the form of a beneficial interest in the
        Regulation S Global Security, such transfer may be effected only in
        accordance with the provisions of this Clause (b)(i) and Clause (b)(iv)
        below and subject to the Applicable Procedures. Upon receipt by the
        Trustee, as Security Registrar, of (A) an order given by the Depositary
        or its authorized representative directing that a beneficial interest in
        the Regulation S Global Security in a specified principal amount be
        credited to a specified Agent Member's account and that a beneficial
        interest in the Restricted Global Security in an equal principal amount
        be debited from another specified Agent Member's account and (B) a
        Regulation S Certificate, satisfactory to the Trustee and duly executed
        by the owner of such beneficial interest in the Restricted Global
        Security or his attorney duly authorized in writing, then the Trustee,
        as Security Registrar but subject to Clause (b)(vii) below, shall reduce
        the principal amount of the Restricted Global Security and increase the
        principal amount of the Regulation S Global Security by such specified
        principal amount.

                      (ii) Regulation S Global Security to Restricted Global
        Security. If the owner of a beneficial interest in the Regulation S
        Global Security wishes at any time to transfer such interest to a Person
        who 



                                      -49-

<PAGE>   61

        wishes to acquire the same in the form of a beneficial interest in the
        Restricted Global Security, such transfer may be effected only in
        accordance with this Clause (b)(ii) and subject to the Applicable
        Procedures. Upon receipt by the Trustee, as Security Registrar, of (A)
        an order given by the Depositary or its authorized representative
        directing that a beneficial interest in the Restricted Global Security
        in a specified principal amount be credited to a specified Agent
        Member's account and that a beneficial interest in the Regulation S
        Global Security in an equal principal amount be debited from another
        specified Agent Member's account and (B) if such transfer is to occur
        during the Restricted Period, a Restricted Securities Certificate,
        satisfactory to the Trustee and duly executed by the owner of such
        beneficial interest in the Regulation S Global Security or his attorney
        duly authorized in writing, then the Trustee, as Security Registrar,
        shall reduce the principal amount of the Regulation S Global Security
        and increase the principal amount of the Restricted Global Security by
        such specified principal amount.

                      (iii) Non-Global Security to Non-Global Security. A
        Security that is not a Global Security may be transferred, in whole or
        in part, to a Person who takes delivery in the form of another Security
        that is not a Global Security as provided in Section 305(a), provided
        that, if the Security to be transferred in whole or in part is a
        Restricted Security, or is a Regulation S Security and the transfer is
        to occur during the Restricted Period, then the Trustee shall have
        received (A) a Restricted Securities Certificate, satisfactory to the
        Trustee and duly executed by the transferor Holder or his attorney duly
        authorized in writing, in which case the transferee Holder shall take
        delivery in the form of a Restricted Security, or (B) a Regulation S
        Certificate, satisfactory to the Trustee and duly executed by the
        transferor Holder or his attorney duly authorized in writing, in which
        case the transferee Holder shall take delivery in the form of a
        Regulation S Security (subject in every case to Section 305(c)).

                      (iv) Regulation S Global Security to be Held Through
        Euroclear or Cedel during Restricted Period. The Company shall use its
        best efforts to cause the Depositary to ensure that, until the
        expiration of the Restricted Period, beneficial interests in the
        Regulation S Global Security may be held only in or through accounts
        maintained at the Depositary by Euroclear or Cedel (or by Agent Members
        acting for the account thereof), and no person shall be entitled to
        effect any transfer or exchange that would result in any such interest
        being held otherwise than in or through such an account; provided that
        this Clause (b)(iv) shall not prohibit any transfer or exchange of such
        an interest in accordance with Clause (b)(ii) above.



<PAGE>   62

                      (v) Exchanges of Book-Entry Securities for Certificated
        Securities. A beneficial interest in a Global Security may not be
        exchanged for a Security in certificated form unless (i) DTC (x)
        notifies the Company that it is unwilling or unable to continue as
        Depositary for the Global Security or (y) has ceased to be a clearing
        agency registered under the Exchange Act and in either case the Company
        thereupon fails to appoint a successor Depositary, (ii) the Company, at
        its option, notifies the Trustee in writing that it elects to cause the
        issuance of the Securities in certificated form or (iii) there shall
        have occurred and be continuing an Event of Default or any event which
        after notice or lapse of time or both would be an Event of Default with
        respect to the Securities. In all cases, certificated Securities
        delivered in exchange for any Global Security or beneficial interests
        therein will be registered in the names, and issued in any approved
        denominations, requested by or on behalf of the Depositary (in
        accordance with its customary procedures). Any certificated Security
        issued in exchange for an interest in a Global Security will bear the
        legend restricting transfers that is borne by such Global Security. Any
        such exchange will be effected through the DWAC System and an
        appropriate adjustment will be made in the records of the Security
        Registrar to reflect a decrease in the principal amount of the relevant
        Global Security.

               (c) Securities Act Legends. Rule 144A Securities and their
Successor Securities shall bear a Restricted Securities Legend, and the
Regulation S Securities and their Successor Securities shall bear a Regulation S
Legend, subject to the following:

                      (i) subject to the following Clauses of this Section
        305(c), a Security or any portion thereof which is exchanged, upon
        transfer or otherwise, for a Global Security or any portion thereof
        shall bear the Securities Act Legend borne by such Global Security while
        represented thereby;

                      (ii) subject to the following Clauses of this Section
        305(c), a new Security which is not a Global Security and is issued in
        exchange for another Security (including a Global Security) or any
        portion thereof, upon transfer or otherwise, shall bear the Securities
        Act Legend borne by such other Security, provided that, if such new
        Security is required pursuant to Section 305(b)(v) or (vi) to be issued
        in the form of a Restricted Security, it shall bear a Restricted
        Securities Legend and, if such new Security is so required to be issued
        in the form of a Regulation S Security, it shall bear a Regulation S
        Legend;

                      (iii) Registered Securities shall not bear a Securities
        Act Legend;



                                      -51-

<PAGE>   63

                      (iv) at any time after the Securities may be freely
        transferred without registration under the Securities Act or without
        being subject to transfer restrictions pursuant to the Securities Act, a
        new Security which does not bear a Securities Act Legend may be issued
        in exchange for or in lieu of a Security (other than a Global Security)
        or any portion thereof which bears such a legend if the Trustee has
        received an Unrestricted Securities Certificate, satisfactory to the
        Trustee and duly executed by the Holder of such legended Security or his
        attorney duly authorized in writing, and after such date and receipt of
        such certificate, the Trustee shall authenticate and deliver such a new
        Security in exchange for or in lieu of such other Security as provided
        in this Article Three;

                      (v) a new Security which does not bear a Securities Act
        Legend may be issued in exchange for or in lieu of a Security (other
        than a Global Security) or any portion thereof which bears such a legend
        if, in the Company's judgment, placing such a legend upon such new
        Security is not necessary to ensure compliance with the registration
        requirements of the Securities Act, and the Trustee, at the direction of
        the Company, shall authenticate and deliver such a new Security as
        provided in this Article Three; and

                      (vi) notwithstanding the foregoing provisions of this
        Section 305(c), a Successor Security of a Security that does not bear a
        particular form of Securities Act Legend shall not bear such form of
        legend unless the Company has reasonable cause to believe that such
        Successor Security is a "restricted security" within the meaning of Rule
        144, in which case the Trustee, at the direction of the Company, shall
        authenticate and deliver a new Security bearing a Restricted Securities
        Legend in exchange for such Successor Security as provided in this
        Article Three.

SECTION 306.  Mutilated, Destroyed, Lost and Stolen Securities.

               If any mutilated Security is surrendered to the Trustee, the
Company shall execute and the Trustee shall authenticate and deliver in exchange
therefor a new Security of like tenor and principal amount and bearing a number
not contemporaneously outstanding.

               If there shall be delivered to the Company and the Trustee (i)
evidence to their satisfaction of the destruction, loss or theft of any Security
and (ii) such security or indemnity as may be required by them to save each of
them and any agent of either of them harmless, then, in the absence of notice to
the Company or the Trustee that such Security has been acquired by a bona fide
purchaser, the Company shall execute and the Trustee shall authenticate and



<PAGE>   64

deliver, in lieu of any such destroyed, lost or stolen Security, a new Security
of like tenor and principal amount and bearing a number not contemporaneously
outstanding.

               In case any such mutilated, destroyed, lost or stolen Security
has become or is about to become due and payable, the Company in the discretion
of the Company may, instead of issuing a new Security, pay such Security.

               Upon the issuance of any new Security under this Section, the
Company may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto and any other
expenses (including the fees and expenses of the Trustee) connected therewith.

               Every new Security issued pursuant to this Section in lieu of any
destroyed, lost or stolen Security shall constitute an original additional
contractual obligation of the Company, whether or not the destroyed, lost or
stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all the benefits of this Indenture equally and proportionately with
any and all other Securities duly issued hereunder.

               The provisions of this Section are exclusive and shall preclude
(to the extent lawful) all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Securities.


SECTION 307.  Payment of Interest; Interest Rights Preserved.

               Interest on any Security which is payable, and is punctually paid
or duly provided for, on any Interest Payment Date shall be paid to the Person
in whose name that Security (or one or more Predecessor Securities) is
registered at the close of business on the Regular Record Date for such
interest.
               Any interest (including Additional Interest) on any Security
which is payable, but is not punctually paid or duly provided for, on any
Interest Payment Date (herein called "Defaulted Interest") shall (a) bear
interest at the rate per annum stated in the form of Security included herein
(to the extent that the payment of such interest shall be legally enforceable),
and (b) forthwith cease to be payable to the Holder on the relevant Regular
Record Date by virtue of having been such Holder, and such Defaulted Interest
may be paid by the Company, at its election in each case, as provided in Clause
(1) or (2) below:

        (1) The Company may elect to make payment of any Defaulted Interest to
the Persons in whose names the Securities (or their respective Predecessor
Securities) are 



                                      -53-
<PAGE>   65

        registered at the close of business on a Special Record Date for the
        payment of such Defaulted Interest, which shall be fixed in the
        following manner. The Company shall notify the Trustee in writing of the
        amount of Defaulted Interest proposed to be paid on each Security and
        the date of the proposed payment, and at the same time the Company shall
        deposit with the Trustee an amount of money equal to the aggregate
        amount proposed to be paid in respect of such Defaulted Interest or
        shall make arrangements satisfactory to the Trustee for such deposit
        prior to the date of the proposed payment, such money when deposited to
        be held in trust for the benefit of the Persons entitled to such
        Defaulted Interest as in this Clause provided. Thereupon the Trustee
        shall fix a Special Record Date for the payment of such Defaulted
        Interest which shall be not more than 15 days and not less than 10 days
        prior to the date of the proposed payment and not less than 10 days
        after the receipt by the Trustee of the notice of the proposed payment.
        The Trustee shall promptly notify the Company of such Special Record
        Date and, in the name and at the expense of the Company, shall cause
        notice of the proposed payment of such Defaulted Interest and the
        Special Record Date therefor to be mailed, first-class postage prepaid,
        to each Holder at his address as it appears in the Security Register,
        not less than 10 days prior to such Special Record Date. Notice of the
        proposed payment of such Defaulted Interest and the Special Record Date
        therefor having been so mailed, such Defaulted Interest shall be paid to
        the Persons in whose names the Securities (or their respective
        Predecessor Securities) are registered at the close of business on such
        Special Record Date and shall no longer be payable pursuant to the
        following Clause (2).

               (2) The Company may make payment of any Defaulted Interest in any
        other lawful manner not inconsistent with the requirements of any
        securities exchange on which the Securities may be listed, and upon such
        notice as may be required by such exchange, if, after notice given by
        the Company to the Trustee of the proposed payment pursuant to this
        Clause, such manner of payment shall be deemed practicable by the
        Trustee.

               Subject to the foregoing provisions of this Section, each
Security delivered under this Indenture upon registration of transfer of or in
exchange for 



<PAGE>   66

or in lieu of any other Security shall carry the rights to interest
accrued and unpaid, and to accrue, which were carried by such other Security.

SECTION 308.  Persons Deemed Owners.

               Prior to due presentment of a Security for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name such Security is registered as the owner of
such Security for the purpose of receiving payment of principal of and premium,
if any, and (subject to Section 307) interest on such Security and for all other
purposes whatsoever, whether or not such Security be overdue, and none of the
Company, the Trustee or any agent of the Company or the Trustee shall be
affected by notice to the contrary.


SECTION 309.  Cancellation.

               All Securities surrendered for payment, redemption, registration
of transfer, exchange or pursuant to any Offer to Purchase pursuant to Section
1013 or 1016 shall, if surrendered to any Person other than the Trustee, be
delivered to the Trustee and shall be promptly cancelled by it. The Company may
at any time deliver to the Trustee for cancellation any Securities previously
authenticated and delivered hereunder which the Company may have acquired in any
manner whatsoever, and all Securities so delivered shall be promptly cancelled
by the Trustee. No Securities shall be authenticated in lieu of or in exchange
for any Securities cancelled as provided in this Section, except as expressly
permitted by this Indenture. All cancelled Securities held by the Trustee shall
be disposed of in accordance with its standard procedures or as directed by a
Company Order; provided, however, that the Trustee shall not be required to
destroy such Securities.


SECTION 310.  Computation of Interest.

               Interest on the Securities shall be computed on the basis of a
360day year of twelve 30-day months, except that Additional Interest shall be
computed on the basis of a 365-day year.



                                      -55-

<PAGE>   67

SECTION 311.  CUSIP and ISIN Numbers.

               The Company in issuing Securities may use "CUSIP" and "ISIN"
numbers (if then generally in use) in addition to serial numbers; if so, the
Trustee shall use such "CUSIP" and "ISIN" numbers in addition to serial numbers
in notices of redemption and repurchase as a convenience to Holders; provided
that any such notice may state that no representation is made as to the
correctness of such CUSIP and ISIN numbers either as printed on the Securities
or as contained in any notice of a redemption or repurchase and that reliance
may be placed only on the serial or other identification numbers printed on the
Securities, and any such redemption or repurchase shall not be affected by any
defect in or omission of such CUSIP and ISIN numbers.


                                  ARTICLE FOUR

                           Satisfaction and Discharge

SECTION  401.  Satisfaction and Discharge of Indenture.

               This Indenture shall cease to be of further effect as to all
outstanding Securities (except as to (i) rights of registration of transfer and
exchange and the Company's right of optional redemption, (ii) substitution of
apparently mutilated, defaced, destroyed, lost or stolen Securities, (iii)
rights of holders of Securities to receive payment of principal of and premium,
if any, and interest on the Securities, (iv) rights, obligations and immunities
of the Trustee under the Indenture and (v) rights of the holders of the
Securities as beneficiaries of the Indenture with respect to any property
deposited with the Trustee payable to all or any of them), and the Trustee, on
demand of and at the expense of the Company, shall execute proper instruments
acknowledging satisfaction and discharge of this Indenture, when

               (1)  either

                      (A) the Company will have paid or caused to be paid the
               principal of and premium, if any, and interest on the Securities
               as and when the same will have become due and payable; or

                      (B) all outstanding Securities (except lost, stolen or
               destroyed Securities which have been replaced or paid) have been
               delivered to the Trustee for cancellation;

               and the Company, in the case of (A) above, has deposited or
               caused to be deposited with the Trustee as trust funds in trust
               for



<PAGE>   68

               the purpose an amount sufficient to pay and discharge the entire
               indebtedness on such Securities not theretofore delivered to the
               Trustee for cancellation, for principal of and premium, if any,
               and interest to the date of such deposit (in the case of
               Securities which have become due and payable) or to the Stated
               Maturity or Redemption Date, as the case may be;

               (2) the Company has paid or caused to be paid all other sums
        payable hereunder by the Company;

               (3) the Company has delivered to the Trustee an Officers'
        Certificate and an Opinion of Counsel, each stating that all conditions
        precedent herein provided for relating to the satisfaction and discharge
        of this Indenture have been complied with; and

               (4) the Trustee shall have received such other documents and
        assurances as the Trustee shall have reasonably requested.

Notwithstanding the satisfaction and discharge of this Indenture, (i) the
obligations of the Company to the Trustee under Section 607, (ii) substitution
of apparently mutilated, defaced, destroyed, lost or stolen Securities, (iii)
rights of holders of Securities to receive payment of principal of and premium,
if any, and interest on the Securities, (iv) rights, obligations and immunities
of the Trustee under this Indenture (including, if money shall have been
deposited with the Trustee pursuant to subclause (B) of Clause (1) of this
Section, the obligations of the Trustee under Section 402 and the last paragraph
of Section 1003), and (v) rights of holders of the Securities as beneficiaries
of this Indenture with respect to any property deposited with the Trustee
payable to all or any of them, shall survive.


SECTION 402.  Application of Trust Money.

               Subject to the provisions of the last paragraph of Section 1003,
all money deposited with the Trustee pursuant to Section 401 shall be held in
trust and applied by it, in accordance with the provisions of the Securities and
this Indenture, to the payment, either directly or through any Paying Agent
(including the Company acting as its own Paying Agent) as the Trustee may
determine, to the Persons entitled thereto, of the principal (and premium, if
any) and interest for whose payment such money has been deposited with the
Trustee.



                                      -57-

<PAGE>   69

                                  ARTICLE FIVE

                                    Remedies

SECTION  501.  Events of Default.

               "Event of Default", wherever used herein, means any one of the
following events (whatever the reason for such Event of Default and whether it
shall be voluntary or involuntary or be effected by operation of law or pursuant
to any judgment, decree or order of any court or any order, rule or regulation
of any administrative or governmental body):

               (1) default in the payment of any interest upon any Security when
        it becomes due and payable, and continuance of such default for a period
        of 30 days; or

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

               (3) default in the payment of principal and interest upon any
        Security required to be purchased pursuant to an Offer to Purchase
        pursuant to Sections 1013 or 1016 when due and payable; or

               (4) default in the performance, or breach, of Section 801; or 

               (5) default in the performance, or breach, of any covenant or
        warranty of the Company in this Indenture or in any Security (other than
        a covenant or warranty a default in whose performance or whose breach is
        elsewhere in this Section specifically dealt with), and continuance of
        such default or breach for a period of 60 days after there has been
        given, by registered or certified mail, to the Company by the Trustee or
        to the Company and the Trustee by the Holders of at least 25% in
        aggregate principal amount of the Outstanding Securities a written
        notice specifying such default or breach and requiring it to be remedied
        and stating that such notice is a "Notice of Default" hereunder; or

               (6) a default or defaults under any bond(s), debenture(s),
        note(s) or other evidence(s) of Debt by the Company or any Significant
        Subsidiary of the Company or under any mortgage(s), indenture(s) or
        instrument(s) under which there may be issued or by which there may be
        secured or evidenced any Debt of such type by the Company or any such
        Significant Subsidiary with a principal amount then outstanding,
        individually or in the aggregate, in excess of $10 million, whether such
        Debt now exists or shall hereafter be created, which default or defaults
        shall constitute a failure to pay such Debt when due at the final
        maturity thereof, or shall have 



<PAGE>   70

        resulted in such Debt becoming or being declared due and payable prior
        to the date on which it would otherwise have become due and payable; or

               (7) a final judgment or final judgments (not subject to appeal)
        for the payment of money are entered against the Company or any
        Significant Subsidiary in an aggregate amount in excess of $10 million
        by a court or courts of competent jurisdiction, which judgments remain
        undischarged or unstayed for a period (during which execution shall not
        be effectively stayed) of 45 days after the right to appeal all such
        judgments has expired; or

               (8) the entry by a court having jurisdiction in the premises of
        (A) a decree or order for relief in respect of the Company or any
        Significant Subsidiary in an involuntary case or proceeding under any
        applicable Federal or State bankruptcy, insolvency, reorganization or
        other similar law or (B) a decree or order adjudging the Company or any
        Significant Subsidiary a bankrupt or insolvent, or approving as properly
        filed a petition seeking reorganization, arrangement, adjustment or
        composition of or in respect of the Company or any Significant
        Subsidiary under any applicable Federal or State law, or appointing a
        custodian, receiver, liquidator, assignee, trustee, sequestrator or
        other similar official of the Company or any Significant Subsidiary or
        of any substantial part of its property, or ordering the winding up or
        liquidation of its affairs, and the continuance of any such decree or
        order for relief or any such other decree or order unstayed and in
        effect for a period of 60 consecutive days; or

               (9) the commencement by the Company or any Significant Subsidiary
        of a voluntary case or proceeding under any applicable Federal or State
        bankruptcy, insolvency, reorganization or other similar law or of any
        other case or proceeding to be adjudicated a bankrupt or insolvent, or
        the consent by it to the entry of a decree or order for relief in
        respect of the Company or any Significant Subsidiary in an involuntary
        case or proceeding under any applicable Federal or State bankruptcy,
        insolvency, reorganization or other similar law or to the commencement
        of any bankruptcy or insolvency case or proceeding against it, or the
        filing by it of a petition or answer or consent seeking reorganization
        or relief under any applicable Federal or State law, or the consent by
        it to the filing of such petition or to the appointment of or taking
        possession by a custodian, receiver, liquidator, assignee, trustee,
        sequestrator or other similar official of the Company or any Significant
        Subsidiary or of any substantial part of its property, or the making by
        it of an assignment for the benefit of creditors, or the admission by it
        in writing of its inability to pay its debts generally as they become
        due, or the taking of corporate action by 



                                      -59-
<PAGE>   71

        the Company or any Significant Subsidiary in furtherance of any such
        action.


SECTION  502.  Acceleration of Maturity; Rescission and Annulment.

               If an Event of Default (other than an Event of Default specified
in Section 501(8) or (9) with respect to the Company) occurs and is continuing,
then and in every such case the Trustee or the Holders of not less than 25% in
aggregate principal amount of the Outstanding Securities may declare the Default
Amount of all the Securities to be due and payable immediately, by a notice in
writing to the Company (and to the Trustee if given by Holders), and upon any
such declaration such Default Amount and any accrued interest, together with all
other amounts due under this Indenture, shall become immediately due and
payable. If an Event of Default specified in Section 501(8) or (9) with respect
to the Company occurs, the Default Amount of and any accrued interest on the
Securities then Outstanding, together with all other amounts due under this
Indenture, shall ipso facto become immediately due and payable without any
declaration or other Act on the part of the Trustee or any Holder.

               The "Default Amount" in respect of any particular Security as of
any particular date of acceleration on or before April 15, 2003 shall equal the
Accreted Value of the Security on such date and as of any particular date of
acceleration thereafter, shall equal the principal amount of the Security plus
accrued and unpaid interest to such date.

               At any time after such a declaration of acceleration has been
made and before a judgment or decree for payment of the money due based on
acceleration has been obtained by the Trustee as hereinafter in this Article
provided, the Holders of a majority in aggregate principal amount of the
Outstanding Securities, by written notice to the Company and the Trustee, may
rescind and annul such declaration and its consequences if:

               (1)  the Company has paid or deposited with the Trustee a sum
        sufficient to pay

                      (A) all overdue interest on all Securities,

                      (B) the principal of (and premium, if any, on) any
               Securities which have become due otherwise than by such
               declaration of acceleration (including any Securities required to
               have been purchased on the Purchase Date pursuant to an Offer to
               Purchase 



<PAGE>   72

               made by the Company) and interest thereon at the rate borne by
               the Securities,

                      (C) to the extent that payment of such interest is lawful,
               interest upon overdue interest at the applicable rate borne by
               the Securities, and

                      (D) all sums paid or advanced by the Trustee hereunder and
               the reasonable compensation, expenses, disbursements and advances
               of the Trustee, its agents and counsel;

        and

               (2) all Events of Default, other than the non-payment of the
        principal of Securities which have become due solely by such declaration
        of acceleration, have been cured or waived as provided in Section 513.

No such rescission shall affect any subsequent default or impair any right
consequent thereon.


SECTION  503.  Collection of Indebtedness and Suits
                      for Enforcement by Trustee.

               The Company covenants that if

               (1) default is made in the payment of any interest on any
        Security when such interest becomes due and payable and such default
        continues for a period of 30 days, or

               (2) default is made in the payment of the principal of (or
        premium, if any, on) any Security at the Maturity thereof or, with
        respect to any Security required to have been purchased pursuant to an
        Offer to Purchase made by the Company, at the Purchase Date thereof,

the Company will, upon demand of the Trustee, pay to it, for the benefit of the
Holders of such Securities, the whole amount then due and payable on such
Securities for principal (and premium, if any) and interest, and, to the extent
that payment of such interest shall be legally enforceable, interest on any
overdue principal (and premium, if any) and on any overdue interest, at the rate
provided by the Securities, and, in addition thereto, such further amount as
shall be sufficient to cover the costs and expenses incurred by the Trustee
under this Indenture, including the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel.



                                      -61-

<PAGE>   73

               If the Company fails to pay such amounts forthwith upon such
demand, the Trustee, in its own name and as trustee of an express trust, may
institute a judicial proceeding for the collection of the sums so due and
unpaid, may prosecute such proceeding to judgment or final decree, and may
enforce the same against the Company or any other obligor upon the Securities
and collect the moneys adjudged or decreed to be payable in the manner provided
by law out of the property of the Company or any other obligor upon the
Securities, wherever situated.

               If an Event of Default occurs and is continuing, the Trustee may
in its discretion proceed to protect and enforce its rights and the rights of
the Holders by such appropriate judicial proceedings as the Trustee shall deem
most effective to protect and enforce any such rights, whether for the specific
enforcement of any covenant or agreement in this Indenture or in aid of the
exercise of any power granted herein, or to enforce any other proper remedy.


SECTION  504.  Trustee May File Proofs of Claim.

               In case of any judicial proceeding relative to the Company (or
any other obligor upon the Securities), its property or its creditors, the
Trustee shall be entitled and empowered, by intervention in such proceeding or
otherwise, to take any and all actions authorized under the Trust Indenture Act
in order to have claims of the Holders and the Trustee allowed in any such
proceeding. In particular, the Trustee shall be authorized to collect and
receive any moneys, securities or other property payable or deliverable upon the
exchange of the Securities or upon any such claims and to distribute the same;
and any custodian, receiver, assignee, trustee, liquidator, sequestrator or
other similar official in any such judicial proceeding is hereby authorized by
each Holder to make such payments to the Trustee and, in the event that the
Trustee shall consent to the making of such payments directly to the Holders, to
pay to the Trustee any amount due it for the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel, and any other
amounts due the Trustee under Section 607.

               No provision of this Indenture shall be deemed to authorize the
Trustee to authorize or consent to or accept or adopt on behalf of any Holder
any plan of reorganization, arrangement, adjustment or composition affecting the
Securities or the rights of any Holder thereof or to authorize the Trustee to
vote in respect of the claim of any Holder in any such proceeding; provided,
however, that the Trustee may, on behalf of the Holders, vote for the election
of a trustee in bankruptcy or similar official and be a member of a creditors or
other similar committee.




<PAGE>   74

SECTION  505.  Trustee May Enforce Claims Without Possession of Securities.

               All rights of action and claims under this Indenture or the
Securities may be prosecuted and enforced by the Trustee without the possession
of any of the Securities or the production thereof in any proceeding relating
thereto, and any such proceeding instituted by the Trustee shall be brought in
its own name as trustee of an express trust, and any recovery of judgment shall,
after provision for the payment of the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel, be for the
ratable benefit of the Holders of the Securities in respect of which such
judgment has been recovered.


SECTION  506.  Application of Money Collected.

               Any money collected by the Trustee pursuant to this Article shall
be applied in the following order, at the date or dates fixed by the Trustee
and, in case of the distribution of such money on account of principal (or
premium, if any) or interest, upon presentation of the Securities and the
notation thereon of the payment if only partially paid and upon surrender
thereof if fully paid:

               FIRST:  To the payment of all amounts due the Trustee under
        Section  607; and

               SECOND: To the payment of the amounts then due and unpaid for
        principal of (and premium, if any) and interest on the Securities in
        respect of which or for the benefit of which such money has been
        collected, ratably, without preference or priority of any kind,
        according to the amounts due and payable on such Securities for
        principal (and premium, if any) and interest, respectively.

The Trustee, upon prior written notice to the Company, may fix a record date and
payment date for any payment to the Holders pursuant to this Section 506.


SECTION  507.  Limitation on Suits.

               No Holder of any Security shall have any right to institute any
proceeding, judicial or otherwise, with respect to this Indenture, or for the
appointment of a receiver or trustee, or for any other remedy hereunder, unless

               (1) such Holder has previously given written notice to the
        Trustee of a continuing Event of Default;



                                      -63-

<PAGE>   75

               (2) the Holders of at least 25% in aggregate principal amount of
        the Outstanding Securities shall have made written request to the
        Trustee to institute proceedings in respect of such Event of Default in
        its own name as Trustee hereunder;

               (3) such Holder or Holders have offered and, if requested,
        provided to the Trustee reasonable indemnity against the costs, expenses
        and liabilities to be incurred in compliance with such request;

               (4) the Trustee for 60 days after its receipt of such notice,
        request and offer and, if requested, provision of indemnity has failed
        to institute any such proceeding; and

               (5) no direction inconsistent with such written request has been
        given to the Trustee during such 60day period by the Holders of a
        majority in principal amount of the Outstanding Securities;

it being understood and intended that no one or more Holders shall have any
right in any manner whatever by virtue of, or by availing of, any provision of
this Indenture to affect, disturb or prejudice the rights of any other Holders,
or to obtain or to seek to obtain priority or preference over any other Holders
or to enforce any right under this Indenture, except in the manner herein
provided and for the equal and ratable benefit of all the Holders.


SECTION  508.  Unconditional Right of Holders to Receive Principal, Premium and
               Interest.

               Notwithstanding any other provision in this Indenture, the Holder
of any Security shall have the right, which is absolute and unconditional, to
receive payment of the principal of (and premium, if any) and (subject to
Section 307) interest on such Security on the respective Stated Maturities
expressed in such Security (or, in the case of redemption, on the Redemption
Date or, in the case of an Offer to Purchase made by the Company and required to
be accepted as to such Security, on the Purchase Date) and to institute suit for
the enforcement of any such payment, and such rights shall not be impaired
without the consent of such Holder.




<PAGE>   76

SECTION  509.  Restoration of Rights and Remedies.

               If the Trustee or any Holder has instituted any proceeding to
enforce any right or remedy under this Indenture and such proceeding has been
discontinued or abandoned for any reason, or has been determined adversely to
the Trustee or to such Holder, then and in every such case, subject to any
determination in such proceeding, the Company, the Trustee and the Holders shall
be restored severally and respectively to their former positions hereunder and
thereafter all rights and remedies of the Trustee and the Holders shall continue
as though no such proceeding had been instituted.


SECTION  510.  Rights and Remedies Cumulative.

               Except as otherwise provided with respect to the replacement or
payment of mutilated, destroyed, lost or stolen Securities in the last paragraph
of Section 306, no right or remedy herein conferred upon or reserved to the
Trustee or to the Holders is intended to be exclusive of any other right or
remedy, and every right and remedy shall, to the extent permitted by law, be
cumulative and in addition to every other right and remedy given hereunder or
now or hereafter existing at law or in equity or otherwise. The assertion or
employment of any right or remedy hereunder, or otherwise, shall not prevent the
concurrent assertion or employment of any other appropriate right or remedy.


SECTION  511.  Delay or Omission Not Waiver.

               No delay or omission of the Trustee or of any Holder of any
Security to exercise any right or remedy accruing upon any Event of Default
shall impair any such right or remedy or constitute a waiver of any such Event
of Default or an acquiescence therein. Every right and remedy given by this
Article or by law to the Trustee or to the Holders may be exercised from time to
time, and as often as may be deemed expedient, by the Trustee or by the Holders,
as the case may be.


SECTION  512.  Control by Holders.

               The Holders of a majority in aggregate principal amount of the
Outstanding Securities shall have the right to direct the time, method and place
of conducting any proceeding for any remedy available to the Trustee or
exercising any trust or power conferred on the Trustee, provided that



                                      -65-

<PAGE>   77

               (1) such direction shall not be in conflict with any rule of law
        or with this Indenture or expose the Trustee to personal liability (as
        determined in the sole discretion of the Trustee), and

               (2) the Trustee may take any other action deemed proper by the
        Trustee which is not inconsistent with such direction.

The Trustee may refuse, however, to follow any direction that the Trustee, in
its sole discretion, determines may be unduly prejudicial to the rights of
another Holder or that may subject the Trustee to any liability or expense if
the Trustee determines, in its sole discretion, that it lacks indemnification
against such loss or expense.


SECTION  513.  Waiver of Past Defaults.

               The Holders of not less than a majority in aggregate principal
amount of the Outstanding Securities may on behalf of the Holders of all the
Securities by written notice to the Trustee waive any past default hereunder and
its consequences, except a default

               (1) in the payment of the principal of (or premium, if any) or
        interest on any Security (including any Security which is required to
        have been purchased pursuant to an Offer to Purchase which has been made
        by the Company), or

               (2) in respect of a covenant or provision hereof which under
        Article Nine cannot be modified or amended without the consent of the
        Holder of each Outstanding Security affected or

               (3) arising from failure to purchase any Security tendered
        pursuant to Sections 1013 and 1016.

               Upon any such waiver, such default shall cease to exist, and any
Event of Default arising therefrom shall be deemed to have been cured, for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other default or impair any right consequent thereon.




<PAGE>   78

SECTION  514.  Undertaking for Costs.

               In any suit for the enforcement of any right or remedy under this
Indenture, or in any suit against the Trustee for any action taken or omitted by
it as Trustee, a court may require any party litigant in such suit to file an
undertaking to pay the costs of such suit, and may assess costs against any such
party litigant, in the manner and to the extent provided in the Trust Indenture
Act; provided that neither this Section nor the Trust Indenture Act shall be
deemed to authorize any court to require such an undertaking or to make such an
assessment in any suit instituted by the Company.


SECTION  515.  Waiver of Stay or Extension Laws.

               The Company covenants (to the extent that it may lawfully do so)
that it will not at any time insist upon, or plead, or in any manner whatsoever
claim or take the benefit or advantage of, any stay or extension law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede the execution of any
power herein granted to the Trustee, but will suffer and permit the execution of
every such power as though no such law had been enacted.


                                   ARTICLE SIX

                                   The Trustee

SECTION  601.  Certain Duties and Responsibilities.

               The duties and responsibilities of the Trustee shall be as
provided by the Trust Indenture Act. Notwithstanding the foregoing, no provision
of this Indenture shall require the Trustee to expend or risk its own funds or
otherwise incur any financial liability in the performance of any of its duties
hereunder, or in the exercise of any of its rights or powers, if it shall have
reasonable grounds for believing that repayment of such funds or adequate
indemnity against such risk or liability is not reasonably assured to it.
Whether or not therein expressly so provided, every provision of this Indenture
relating to the conduct or affecting the liability of or affording protection to
the Trustee shall be subject to the provisions of this Section.



                                      -67-

<PAGE>   79

SECTION  602.  Notice of Defaults.

               The Trustee shall give the Holders notice of any Default
hereunder as and to the extent provided by the Trust Indenture Act, unless such
Default has been cured or waived; provided, however, that in the case of any
Default of the character specified in Section 501(5), no such notice to Holders
shall be given until at least 30 days after the occurrence thereof.


SECTION  603.  Certain Rights of Trustee.

               Subject to the provisions of Section  601:

               (a) the Trustee may rely and shall be protected in acting or
        refraining from acting upon any resolution, certificate, statement,
        instrument, opinion, report, notice, request, direction, consent, order,
        bond, debenture, note, other evidence of indebtedness or other paper or
        document believed by it to be genuine and to have been signed or
        presented by the proper party or parties;

               (b) any request or direction of the Company mentioned herein
        shall be sufficiently evidenced by a Company Request or a Company Order
        and any resolution of the Board of Directors may be sufficiently
        evidenced by a Board Resolution;

               (c) whenever in the administration of this Indenture the Trustee
        shall deem it desirable that a matter be proved or established prior to
        taking, suffering or omitting any action hereunder, the Trustee (unless
        other evidence be herein specifically prescribed) may, in the absence of
        bad faith on its part, rely upon an Officers' Certificate or an Opinion
        of Counsel;

               (d) the Trustee may consult with counsel and the written advice
        of such counsel or any Opinion of 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 reliance thereon;

               (e) the Trustee shall be under no obligation to exercise any of
        the rights or powers vested in it by this Indenture at the request or
        direction of any of the Holders pursuant to this Indenture, unless such
        Holders shall have offered to the Trustee reasonable security or
        indemnity against the costs, expenses and liabilities which might be
        incurred by it in compliance with such request or direction reasonably
        satisfactory to the Trustee;



<PAGE>   80

               (f) the Trustee shall not be bound to make any investigation into
        the facts or matters stated in any resolution, certificate, statement,
        instrument, opinion, report, notice, request, direction, consent, order,
        bond, debenture, note, other evidence of indebtedness or other paper or
        document, but the Trustee, in its discretion, may make such further
        inquiry or investigation into such facts or matters as it may see fit,
        and, if the Trustee shall determine to make such further inquiry or
        investigation, it shall be entitled to examine the books, records and
        premises of the Company, personally or by agent or attorney;

               (g) the Trustee may execute any of the trusts or powers hereunder
        or perform any duties hereunder either directly or by or through agents
        or attorneys and the Trustee shall not be responsible for any misconduct
        or negligence on the part of any agent or attorney appointed with due
        care by it hereunder; and

               (h) the Trustee shall not be liable for any action taken,
        suffered or omitted by it in good faith which the Trustee reasonably
        believed to have been authorized or within its rights or powers.


SECTION  604.  Not Responsible for Recitals or Issuance of Securities.

               The recitals contained herein and in the Securities, except the
Trustee's certificates of authentication, shall be taken as the statements of
the Company, and the Trustee assumes no responsibility for their correctness.
The Trustee makes no representations as to the validity or sufficiency of this
Indenture or the Securities. The Trustee shall not be accountable for the use or
application by the Company of Securities or the proceeds thereof.


SECTION  605.  May Hold Securities.

               The Trustee, any Paying Agent, any Security Registrar (if other
than the Trustee) or any other agent of the Company, in its individual or any
other capacity, may become the owner or pledgee of Securities and, subject to
Sections 608 and 613, may otherwise deal with the Company with the same rights
it would have if it were not Trustee, Paying Agent, Security Registrar or such
other agent.



<PAGE>   81

SECTION  606.  Money Held in Trust.

               Money held by the Trustee in trust hereunder need not be
segregated from other funds except to the extent required by law. The Trustee
shall be under no liability for interest on any money received by it hereunder
except as otherwise agreed with the Company.


SECTION  607.  Compensation and Reimbursement.

               The Company agrees

               (1) to pay to the Trustee from time to time reasonable
        compensation for all services rendered by it hereunder (which
        compensation shall not be limited by any provision of law in regard to
        the compensation of a trustee of an express trust);

               (2) except as otherwise expressly provided herein, to reimburse
        the Trustee upon its request for all reasonable expenses, disbursements
        and advances incurred or made by the Trustee in accordance with any
        provision of this Indenture (including the reasonable compensation and
        the expenses and disbursements of its agents and counsel), except any
        such expense, disbursement or advance as may be attributable to its
        negligence or bad faith; and

               (3) to indemnify the Trustee for, and to hold it harmless
        against, any loss, liability or expense (including the reasonable
        compensation, expenses and disbursements of its agents, accountants,
        experts and counsel) incurred without negligence or bad faith on its
        part, arising out of or in connection with the acceptance or
        administration of this trust, including the costs and expenses of
        enforcing this Indenture against the Company (including, without
        limitation, this Section 607) and of defending itself against any claim
        (whether asserted by any Holder or the Company) or liability in
        connection with the exercise or performance of any of its powers or
        duties hereunder. The provisions of this Section 607 shall survive any
        termination of this Indenture and the resignation or removal of the
        Trustee.

               As security for the performance of the obligations of the Company
under this Section 607, the Trustee shall have a lien prior to the Securities
upon all property and funds held or collected by the Trustee, except funds held
in trust for the payment of principal of (and premium, if any) or interest on
particular Securities. The Trustee's right to receive payment of any amounts due
under 



<PAGE>   82

this Section 607 shall not be subordinate to any other liability or indebtedness
of the Company (even though the Securities may be so subordinated).

               When the Trustee incurs expenses or renders services after an
Event of Default specified in Section 501(8) or (9) occurs, the expenses and the
compensation for such services are intended to constitute expenses of
administration under Title 11, U.S. Code, or any similar Federal state or
foreign law for the relief of debtors.


SECTION  608.  Disqualification; Conflicting Interests.

               If the Trustee has or shall acquire a conflicting interest within
the meaning of the Trust Indenture Act, the Trustee shall either eliminate such
interest or resign, to the extent and in the manner provided by, and subject to
the provisions of, the Trust Indenture Act and this Indenture.


SECTION  609.  Corporate Trustee Required; Eligibility.

               There shall at all times be a Trustee hereunder which shall be a
Person that is eligible pursuant to the Trust Indenture Act to act as such and
has a combined capital and surplus of at least $50,000,000 and its Corporate
Trust Office in the Borough of Manhattan, The City of New York, New York. If
such Person publishes reports of condition at least annually, pursuant to law or
to the requirements of a Federal, State, Territorial or District of Columbia
supervising or examining authority, then for the purposes of this Section, the
combined capital and surplus of such Person shall be deemed to be its combined
capital and surplus as set forth in its most recent report of condition so
published. If at any time the Trustee shall cease to be eligible in accordance
with the provisions of this Section, it shall resign immediately in the manner
and with the effect hereinafter specified in this Article.


SECTION  610.  Resignation and Removal; Appointment
                      of Successor.

               (a) No resignation or removal of the Trustee and no appointment
of a successor Trustee pursuant to this Article shall become effective until the
acceptance of appointment by the successor Trustee under Section 611, at which
time the retiring Trustee shall be fully discharged from its obligations
hereunder.



                                      -71-

<PAGE>   83

               (b) The Trustee may resign at any time by giving written notice
thereof to the Company. If an instrument of acceptance by a successor Trustee
shall not have been delivered to the Trustee within 30 days after the giving of
such notice of resignation, the resigning Trustee may petition any court of
competent jurisdiction for the appointment of a successor Trustee.

               (c) The Trustee may be removed at any time by Act of the Holders
of a majority in principal amount of the Outstanding Securities, delivered to
the Trustee and to the Company.

               (d) If at any time:

               (1) the Trustee shall fail to comply with Section 608 after
        written request therefor by the Company or by any Holder who has been a
        bona fide Holder of a Security for at least six months, or

               (2) the Trustee shall cease to be eligible under Section 609 and
        shall fail to resign after written request therefor by the Company or by
        any such Holder, or

               (3) the Trustee shall become incapable of acting or shall be
        adjudged a bankrupt or insolvent or a receiver of the Trustee or of its
        property shall be appointed or any public officer shall take charge or
        control of the Trustee or of its property or affairs for the purpose of
        rehabilitation, conservation or liquidation,

then, in any such case, (i) the Company, by Board Resolution, may remove the
Trustee, or (ii) subject to Section 514, any Holder who has been a bona fide
Holder of a Security for at least six months may, on behalf of himself and all
others similarly situated, petition any court of competent jurisdiction for the
removal of the Trustee and the appointment of a successor Trustee.

               (e) If the Trustee shall resign, be removed or become incapable
of acting, or if a vacancy shall occur in the office of Trustee for any cause,
the Company, by Board Resolution, shall promptly appoint a successor Trustee.
If, within one year after such resignation, removal or incapability, or the
occurrence of such vacancy, a successor Trustee shall be appointed by Act of the
Holders of a majority in principal amount of the Outstanding Securities
delivered to the Company and the retiring Trustee, the successor Trustee so
appointed shall, forthwith upon its acceptance of such appointment, become the
successor Trustee and supersede the successor Trustee appointed by the Company.
If no successor Trustee shall have been so appointed by the Company or the
Holders and accepted appointment in the manner hereinafter provided, any Holder
who has been a bona fide Holder of a Security for at least six months may, on
behalf 



<PAGE>   84

of himself and all others similarly situated, petition any court of competent
jurisdiction for the appointment of a successor Trustee.

               (f) The Company shall give notice of each resignation and each
removal of the Trustee and each appointment of a successor Trustee to all
Holders in the manner provided in Section 106. Each notice shall include the
name of the successor Trustee and the address of its Corporate Trust Office.


SECTION 611.  Acceptance of Appointment by Successor.

               Every successor Trustee appointed hereunder shall execute,
acknowledge and deliver to the Company and to the retiring Trustee an instrument
accepting such appointment, and thereupon the resignation or removal of the
retiring Trustee shall become effective and such successor Trustee, without any
further act, deed or conveyance, shall become vested with all the rights,
powers, trusts and duties of the retiring Trustee; but, on request of the
Company or the successor Trustee under Section 607, execute and deliver an
instrument transferring to such successor Trustee all the rights, powers and
trusts of the retiring Trustee and shall duly assign, transfer and deliver to
such successor Trustee all property and money held by such retiring Trustee
hereunder. Upon request of any such successor Trustee, the Company shall execute
any and all instruments for more fully and certainly vesting in and confirming
to such successor Trustee all such rights, powers and trusts.

               No successor Trustee shall accept its appointment unless at the
time of such acceptance such successor Trustee shall be qualified and eligible
under this Article.



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<PAGE>   85


SECTION 612.   Merger, Conversion, Consolidation or Succession to Business.

               Any corporation into which the Trustee may be merged or converted
or with which it may be consolidated, or any corporation resulting from any
merger, conversion or consolidation to which the Trustee shall be a party, or
any corporation succeeding to all or substantially all the corporate trust
business of the Trustee, shall be the successor of the Trustee hereunder,
provided that such corporation shall be otherwise qualified and eligible under
this Article, without the execution or filing of any paper or any further act on
the part of any of the parties hereto. In case any Securities shall have been
authenticated, but not delivered, by the Trustee then in office, any successor
by merger, conversion or consolidation to such authenticating Trustee may adopt
such authentication and deliver the Securities so authenticated with the same
effect as if such successor Trustee had itself authenticated such Securities.


SECTION 613.   Preferential Collection of Claims Against the Company.

               If and when the Trustee shall be or become a creditor of the
Company (or any other obligor upon the Securities), the Trustee shall be subject
to the provisions of the Trust Indenture Act regarding the collection of claims
against the Company (or any such other obligor).


SECTION 614.   Appointment of Authenticating Agent.

               The Trustee may appoint an Authenticating Agent or Agents with
respect to the Securities which shall be authorized to act on behalf of the
Trustee to authenticate Securities issued upon original issue and upon exchange,
registration of transfer or partial redemption thereof or pursuant to Section
306, and Securities so authenticated shall be entitled to the benefits of this
Indenture and shall be valid and obligatory for all purposes as if authenticated
by the Trustee hereunder. Wherever reference is made in this Indenture to the
authentication and delivery of Securities by the Trustee or the Trustee's
certificate of authentication, such reference shall be deemed to include
authentication and delivery on behalf of the Trustee by an Authenticating Agent
and a certificate of authentication executed on behalf of the Trustee by an
Authenticating Agent. Each Authenticating Agent shall be acceptable to the
Company and shall at all times be a corporation organized and doing business
under the laws of the United States of America, any State thereof or the
District of Columbia, authorized under such laws to act as Authenticating Agent,
having a combined capital and surplus of not less than $50,000,000 and subject
to 



<PAGE>   86

supervision or examination by Federal or State authority. If such Authenticating
Agent publishes reports of condition at least annually, pursuant to law or to
the requirements of said supervising or examining authority, then for the
purposes of this Section, the combined capital and surplus of such
Authenticating Agent shall be deemed to be its combined capital and surplus as
set forth in its most recent report of condition so published. If at any time an
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section, such Authenticating Agent shall resign immediately
in the manner and with the effect specified in this Section.

               Any corporation into which an Authenticating Agent may be merged
or converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which such Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency or
corporate trust business of an Authenticating Agent, shall continue to be an
Authenticating Agent, provided such corporation shall be otherwise eligible
under this Section, without the execution or filing of any paper or any further
act on the part of the Trustee or the Authenticating Agent.

               An Authenticating Agent may resign at any time by giving written
notice thereof to the Trustee and to the Company. The Trustee may at any time
terminate the agency of an Authenticating Agent by giving written notice thereof
to such Authenticating Agent and to the Company. Upon receiving such a notice of
resignation or upon such a termination, or in case at any time such
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section, the Trustee may appoint a successor Authenticating
Agent which shall be acceptable to the Company and shall give notice of such
appointment in the manner provided in Section 106 to all Holders of Securities.
Any successor Authenticating Agent upon acceptance of its appointment hereunder
shall become vested with all the rights, powers and duties of its predecessor
hereunder, with like effect as if originally named as an Authenticating Agent.
No successor Authenticating Agent shall be appointed unless eligible under the
provisions of this Section.

               The Trustee agrees to pay to each Authenticating Agent from time
to time reasonable compensation for its services under this Section, and the
Trustee shall be entitled to be reimbursed for such payments, subject to the
provisions of Section 607.



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<PAGE>   87

               If an appointment is made pursuant to this Section, the
Securities may have endorsed thereon, in lieu of the Trustee's certificate of
authentication, an alternative certificate of authentication in the following
form:

               This is one of the Securities referred to in the within-mentioned
Indenture.

        United States Trust Company of New York,
                                                                      As Trustee

        By_____________________,

                                                        As Authenticating Agent

                                       By_______________________________________
                                                       Authorized Signatory



                                  ARTICLE SEVEN

              Holders' Lists and Reports by Trustee and the Company

SECTION 701.   Company to Furnish Trustee Names and Addresses of Holders.

               The Company will furnish or cause to be furnished to the Trustee

               (a) semi-annually, not more than 15 days after each Regular
        Record Date, a list, in such form as the Trustee may reasonably require,
        of the names and addresses of the Holders as of such Regular Record
        Date, and

               (b) at such other times as the Trustee may request in writing,
        within 30 days after the receipt by the Company of any such request, a
        list of similar form and content as of a date not more than 15 days
        prior to the time such list is furnished;

excluding from any such list names and addresses received by the Trustee in its
capacity as Security Registrar.



<PAGE>   88

SECTION 702.   Preservation of Information; Communications to Holders.

               (a) The Trustee shall preserve, in as current a form as is
reasonably practicable, the names and addresses of Holders contained in the most
recent list furnished to the Trustee as provided in Section 701 and the names
and addresses of Holders received by the Trustee in its capacity as Security
Registrar. The Trustee may destroy any list furnished to it as provided in
Section 701 upon receipt of a new list so furnished.

               (b) The rights of Holders to communicate with other Holders with
respect to their rights under this Indenture or under the Securities, and the
corresponding rights and duties of the Trustee, shall be as provided by the
Trust Indenture Act.

               (c) Every Holder of Securities, by receiving and holding the
same, agrees with the Company and the Trustee that none of the Company, the
Trustee or any agent of any of them shall be held accountable by reason of any
disclosure of information as to names and addresses of Holders made pursuant to
the Trust Indenture Act.


SECTION 703.  Reports by Trustee.

               (a) The Trustee shall transmit to Holders such reports concerning
the Trustee and its actions under this Indenture as may be required pursuant to
the Trust Indenture Act at the times and in the manner provided pursuant
thereto.

               (b) A copy of each such report shall, at the time of such
transmission to Holders, be filed by the Trustee with each stock exchange upon
which the Securities are listed, with the Commission and with the Company. The
Company will notify the Trustee when the Securities are listed on any stock
exchange.



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<PAGE>   89

SECTION 704.  Reports by Company.

               The Company shall file with the Trustee and the Commission, and
transmit to Holders, such information, documents and other reports, and such
summaries thereof, as may be required pursuant to the Trust Indenture Act at the
times and in the manner provided pursuant to such Act and in the manner set
forth in Section 1017; provided that any such information, documents or reports
required to be filed with the Commission pursuant to Section 13 or 15(d) of the
Exchange Act ("SEC Reports") shall be filed with the Trustee within 15 days
after the same is so required to be filed with the Commission. In the event the
Company shall cease to be required to file SEC Reports pursuant to the Exchange
Act, the Company will nonetheless continue to file such reports with the
Commission (unless the Commission will not accept such a filing) and the Trustee
and to furnish copies of such SEC Reports to the Holders of Securities at the
time the Company is required to file such reports with the Trustee and will make
such information available to investors who request it in writing.

SECTION 705.   Officers' Certificate with Respect to Change in Interest Rates.

               Within five days after any Step-Up, Subsequent Step-Up, Step-Down
Date or Subsequent Step-Down Date, the Company shall deliver an Officers'
Certificate to the Trustee stating the new interest rate and the date on which
it became effective.



<PAGE>   90

                                  ARTICLE EIGHT

                              Merger, Consolidation, Etc.

SECTION 801.  Mergers, Consolidations and Certain Sales of Assets.



                                      -79-

<PAGE>   91

               (a) The Company may not, in a single transaction or a series of
related transactions, (i) consolidate with or merge into any other Person or
permit any other Person to consolidate with or merge into the Company (other
than a consolidation or merger of a Wholly-Owned Restricted Subsidiary organized
under the laws of a State of the United States into the Company), or (ii)
directly or indirectly, transfer, sell, lease or otherwise dispose of all or
substantially all of its assets (determined on a consolidated basis for the
Company and its Restricted Subsidiaries taken as a whole and provided that the
creation of a Lien on or in any of its assets shall not in and of itself
constitute the transfer, sale, lease or disposition of the assets subject to the
Lien), unless: (1) in a transaction in which the Company does not survive or in
which the Company sells, leases or otherwise disposes of all or substantially
all of its assets to any other Person, the successor entity to the Company shall
be a corporation organized under the laws of the United States of America or any
State thereof or the District of Columbia and shall expressly assume, by a
supplemental indenture executed and delivered to the Trustee in form
satisfactory to the Trustee, all of the Company's obligations under this
Indenture; (2) immediately after giving pro forma effect to such transaction as
if such transaction had occurred at the beginning of the last full fiscal
quarter immediately prior to the consummation of such transaction with the
appropriate adjustments with respect to the transaction being included in such
pro forma calculation and treating any Debt which becomes an obligation of the
Company or a Subsidiary as a result of such transaction as having been Incurred
by the Company or such Subsidiary at the time of the transaction, no Default or
Event of Default shall have occurred and be continuing; (3) immediately after
giving effect to such transaction, the Consolidated Net Worth of the Company (or
other successor entity to the Company) is equal to or greater than that of the
Company immediately prior to the transaction; (4) if, as a result of any such
transaction, property or assets of the Company would become subject to a Lien
prohibited by the provisions of Section 1011, the Company or the successor
entity to the Company shall have secured the Securities as required by Section
1011;(5) the Company has delivered to the Trustee an Officer's Certificate and
an Opinion of Counsel, each in form and substance satisfactory to the Trustee
stating that such consolidation, merger, conveyance, transfer, lease or
acquisition and, if a supplemental indenture is required in connection with such
transaction, such supplemental indenture, complies with this Article and that
all conditions precedent herein provided for relating to such transaction have
been complied with, and, with respect to such Officer's Certificate, setting
forth the manner of determination of the Consolidated Net Worth in accordance
with Clause (3) of Section 801, of the Company or, if applicable, of the
Successor Company as required pursuant to the foregoing.

               (b) In the event of any transaction (other than a lease)
described in and complying with the immediately preceding paragraph in which the
Company is not the surviving Person and the surviving Person assumes all the
obligations of the Company under the Securities and this Indenture pursuant



<PAGE>   92

to a supplemental indenture, such surviving Person shall succeed to, and be
substituted for, and may exercise every right and power of, the Company, and the
Company will be discharged from its obligations under this Indenture and the
Securities; provided that solely for the purpose of calculating amounts under
Section 1009(3), any such surviving Person shall only be deemed to have
succeeded to and be substituted for the Company with respect to the period
subsequent to the effective time of such transaction, and the Company (before
giving effect to such transaction) shall be deemed to be the "Company" for such
purposes for all prior periods.


SECTION 802.  Successor  Substituted.

               Upon any consolidation of the Company with, or merger of the
Company with or into, any other Person or any conveyance, transfer or lease of
the properties and assets of the Company substantially as an entirety in
accordance with Section 801, the successor Person formed by such consolidation
or into which the Company is merged or to which such conveyance, transfer or
lease is made shall succeed to, and be substituted for, and may exercise every
right and power of, the Company under this Indenture with the same effect as if
such successor Person had been named as the Company herein, and thereafter,
except in the case of a lease, the predecessor Person shall be relieved of all
obligations and covenants under this Indenture and the Securities.


                                  ARTICLE NINE

                                Supplemental Indentures

SECTION 901.  Supplemental Indentures Without Consent of Holders.

               Without the consent of any Holders, the Company, when authorized
by Board Resolution, and the Trustee, at any time and from time to time, may
enter into one or more indentures supplemental hereto, in form satisfactory to
the Trustee, for any of the following purposes:

               (1) to evidence the succession of another Person to the Company
        and the assumption by any such successor of the covenants of the Company
        herein and in the Securities; or



                                      -81-

<PAGE>   93

               (2) to add to the covenants of the Company for the benefit of the
        Holders, or to surrender any right or power herein conferred upon the
        Company; or

               (3) to secure the Securities pursuant to the requirements of
        Section 1011 or otherwise; or

               (4) to modify, eliminate or add to the provisions of this
        Indenture to such extent as shall be necessary to comply with any
        requirement of the Commission in order to effect qualification of this
        Indenture under the Trust Indenture Act in connection with the issuance
        of Exchange Securities or thereafter to maintain the qualification of
        this Indenture under the Trust Indenture Act;

               (5) to cure any ambiguity, to correct or supplement any provision
        herein which may be inconsistent with any other provision herein, or to
        make any other provisions with respect to matters or questions arising
        under this Indenture which shall not be inconsistent with the provisions
        of this Indenture, provided that such action pursuant to this Clause (5)
        shall not adversely affect the legal rights of the Holders; or

               (6) to provide for uncertificated Securities in addition to or in
        place of certificated Securities.


SECTION 902.  Supplemental Indentures with Consent of Holders.

               With the consent of the Holders of not less than a majority in
aggregate principal amount of the Outstanding Securities, by Act of said Holders
delivered to the Company and the Trustee, and consistent with Section 513, the
Company, when authorized by Board Resolution, and the Trustee may enter into an
indenture or indentures supplemental hereto for the purpose of adding any
provisions to or changing in any manner or eliminating any of the provisions of
this Indenture or of modifying in any manner the rights of the Holders under
this Indenture; provided, however, that no such supplemental indenture shall,
without the consent of the Holder of each Outstanding Security affected thereby,

               (1) change the Stated Maturity of the principal of, or any
        installment of interest on, any Security, or reduce the principal amount
        thereof or the rate of interest thereon or any premium payable thereon,
        or change the place of payment where, or the coin or currency in which,
        any Security or any premium or interest thereon is payable, or impair
        the right to institute suit for the enforcement of any such payment on
        or after the Stated Maturity thereof (or, in the case of redemption, on
        or after the 



<PAGE>   94

        Redemption Date) or, in the case of an Offer to Purchase which has been
        made, on or after the applicable Purchase Date, or

               (2) reduce the percentage in principal amount of the Outstanding
        Securities, the consent of whose Holders is required for any such
        supplemental indenture, or the consent of whose Holders is required for
        any waiver (of compliance with certain provisions of this Indenture or
        certain defaults hereunder and their consequences) provided for in this
        Indenture, or

               (3) modify any of the provisions of this Section, Section 513 or
        Section 1019, except to increase any such percentage or to provide that
        certain other provisions of this Indenture cannot be modified or waived
        without the consent of the Holder of each Outstanding Security affected
        thereby, or

               (4) following the mailing of an Offer with respect to an Offer to
        Purchase pursuant to Section 1013 or 1016 and until the Expiration Date
        of such Offer to Purchase, modify the provisions of this Indenture with
        respect to such Offer to Purchase in a manner materially adverse to such
        Holder.

               It shall not be necessary for any Act of Holders under this
Section to approve the particular form of any proposed supplemental indenture,
but it shall be sufficient if such Act shall approve the substance thereof.


SECTION 903.  Execution of Supplemental Indentures.

               In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article or the modifications thereby of
the trusts created by this Indenture, the Trustee shall be entitled to receive,
and (subject to Section 601) shall be fully protected in relying upon, an
Opinion of Counsel stating that the execution of such supplemental indenture is
authorized or permitted by this Indenture. The Trustee may, but shall not be
obligated to, enter into any such supplemental indenture which affects the
Trustee's own rights, duties or immunities under this Indenture or otherwise.



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<PAGE>   95

SECTION 904.  Effect of Supplemental Indentures.

               Upon the execution of any supplemental indenture under this
Article, this Indenture shall be modified in accordance therewith, and such
supplemental indenture shall form a part of this Indenture for all purposes; and
every Holder of Securities theretofore or thereafter authenticated and delivered
hereunder shall be bound thereby.


SECTION 905.  Conformity with Trust Indenture Act.

               Every supplemental indenture executed pursuant to this Article
shall conform to the requirements of the Trust Indenture Act.


SECTION 906.  Reference in Securities to Supplemental Indentures.

               Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article may, and shall if required by
the Trustee, bear a notation in form approved by the Trustee as to any matter
provided for in such supplemental indenture. If the Company shall so determine,
new Securities so modified as to conform, in the opinion of the Trustee and the
Company, to any such supplemental indenture may be prepared and executed by the
Company and authenticated and delivered by the Trustee in exchange for
Outstanding Securities.


                                   ARTICLE TEN

                                    Covenants

SECTION 1001.  Payment of Principal,  Premium and
                      Interest.

               The Company will duly and punctually pay the principal of and
premium, if any, and interest on the Securities in accordance with the terms of
the Securities and this Indenture.



<PAGE>   96

SECTION 1002.  Maintenance of Office or Agency.

               The Company will maintain in the Borough of Manhattan, The City
of New York, New York, an office or agency where Securities may be presented or
surrendered for payment, where Securities may be surrendered for registration of
transfer or exchange and where notices and demands to or upon the Company in
respect of the Securities and this Indenture may be served. The Company will
give prompt written notice to the Trustee of the location, and any change in the
location, of such office or agency. If at any time the Company shall fail to
maintain any such required office or agency or shall fail to furnish the Trustee
with the address thereof, such presentations, surrenders, notices and demands
may be made or served at the Corporate Trust Office of the Trustee, and the
Company hereby appoints the Trustee as its agent to receive all such
presentations, surrenders, notices and demands.

               The Company may also from time to time designate one or more
other offices or agencies (in or outside the Borough of Manhattan, The City of
New York, New York) where the Securities may be presented or surrendered for any
or all such purposes and may from time to time rescind such designations;
provided, however, that no such designation or rescission shall in any manner
relieve the Company of its obligation to maintain an office or agency in the
Borough of Manhattan, The City of New York, New York for such purposes. The
Company will give prompt written notice to the Trustee of any such designation
or rescission and of any change in the location of any such other office or
agency.


SECTION 1003.  Money for Security Payments to be Held in Trust.

               If the Company shall at any time act as its own Paying Agent, it
will, on or before each due date of the principal of (and premium, if any) or
interest on any of the Securities, segregate and hold in trust for the benefit
of the Persons entitled thereto a sum sufficient to pay the principal (and
premium, if any) or interest so becoming due until such sums shall be paid to
such Persons or otherwise disposed of as herein provided and will promptly
notify the Trustee in writing of its action or failure so to act. As provided in
Section 504, upon any bankruptcy or reorganization proceeding relative to the
Company, the Trustee shall serve as the Paying Agent for the Securities.

               Whenever the Company shall have one or more Paying Agents, it
will, prior to each due date of the principal of (and premium, if any) or
interest on any Securities, deposit with a Paying Agent a sum sufficient to pay
the principal 



                                      -85-

<PAGE>   97

(and premium, if any) or interest so becoming due, such sum to be held in trust
for the benefit of the Persons entitled to such principal, premium or interest,
and (unless such Paying Agent is the Trustee) the Company will promptly notify
the Trustee in writing of its action or failure so to act. As provided in
Section 504, upon any bankruptcy or reorganization proceeding relative to the
Company the Trustee shall serve as the Paying Agent for the Securities.

               The Company will cause each Paying Agent other than the Trustee
to execute and deliver to the Trustee an instrument in which such Paying Agent
shall agree with the Trustee, subject to the provisions of this Section, that
such Paying Agent will:

               (1) hold all sums held by it for the payment of the principal of
        (and premium, if any) or interest on Securities in trust for the benefit
        of the Persons entitled thereto until such sums shall be paid to such
        Persons or otherwise disposed of as herein provided;

               (2) give the Trustee notice of any default by the Company (or any
        other obligor upon the Securities) in the making of any payment of
        principal (and premium, if any) or interest;

               (3) at any time during the continuance of any such default, upon
        the written request of the Trustee, forthwith pay to the Trustee all
        sums so held in trust by such Paying Agent; and

               (4) acknowledge, accept and agree to comply in all respects with
        the provisions of this Indenture relating to the duties, rights and
        obligations of such Paying Agent.

               The Company may at any time, for the purpose of obtaining the
satisfaction and discharge of this Indenture or for any other purpose, pay, or
by Company Order direct any Paying Agent to pay, to the Trustee all sums held in
trust by the Company or such Paying Agent, such sums to be held by the Trustee
upon the same trusts as those upon which such sums were held by the Company or
such Paying Agent; and, upon such payment by any Paying Agent to the Trustee,
such Paying Agent shall be released from all further liability with respect to
such money.

               Any money deposited with the Trustee or any Paying Agent, or then
held by the Company, in trust for the payment of the principal of (and premium,
if any) or interest on any Security and remaining unclaimed for two years after
such principal (and premium, if any) or interest has become due and payable
shall be paid to the Company on the Company Request, or (if then held by the
Company) shall be discharged from such trust; and the Holder of such Security
shall thereafter, as an unsecured general creditor, look only to the



<PAGE>   98

Company for payment thereof, and all liability of the Trustee or such Paying
Agent with respect to such trust money, and all liability of the Company 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 Company cause to be published once, in a newspaper published in
the English language, customarily published on each Business Day and of general
circulation in the Borough of Manhattan, The City of New York, New York, 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 publication, any
unclaimed balance of such money then remaining will be repaid to the Company.


SECTION  1004.  Existence.

               Subject to Article Eight, the Company will do or cause to be done
all things necessary to preserve and keep in full force and effect its
existence, rights (charter and statutory) and franchises; provided, however,
that the Company shall not be required to preserve any such right or franchise
if the Board of Directors shall determine that the preservation thereof is no
longer desirable in the conduct of the business of the Company and that the loss
thereof is not disadvantageous in any material respect to the Holders.


SECTION  1005.  Maintenance of Properties and Insurance.

               The Company will cause all properties used or useful in the
conduct of its business or the business of any Subsidiary, to be maintained and
kept in good condition, repair and working order and supplied with all necessary
equipment and will cause to be made all necessary repairs, renewals,
replacements, betterments and improvements thereof, all as in the judgment of
the Company may be necessary so that the business carried on in connection
therewith may be properly and advantageously conducted at all times; provided,
however, that nothing in this Section shall prevent the Company from
discontinuing the operation or maintenance of any of such properties if such
discontinuance is, as determined in the good faith judgment of the Board of
Directors evidenced by a Board Resolution, desirable in the conduct of its
business or, in the case of the Company, the business of any Subsidiary, and not
disadvantageous in any material respect to the Holders.

               The Company shall, and shall cause the Subsidiaries of the
Company to, keep at all times all of their properties which are of an insurable
nature insured against loss or damage with insurers believed by the Company to
be responsible to the extent that property of similar character is usually so



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<PAGE>   99

insured by corporations similarly situated and owning like properties in
accordance with good business practice.


SECTION 1006.  Payment of Taxes and Other Claims.

               The Company will pay or discharge or cause to be paid or
discharged, before the same shall become delinquent, (1) all taxes, assessments
and governmental charges levied or imposed upon the Company or any Subsidiaries
of the Company or upon the income, profits or property of the Company or any
Subsidiaries, and (2) all lawful claims for labor, materials and supplies which,
if unpaid, might by law become a lien upon the property of the Company or any
Subsidiaries of the Company; provided, however, that the Company shall not be
required to pay or discharge or cause to be paid or discharged any such tax,
assessment, charge or claim whose amount, applicability or validity is being
contested in good faith by appropriate proceedings.


SECTION 1007.  Limitation on Consolidated Debt.

               The Company may not, and may not permit any Restricted Subsidiary
of the Company to, Incur any Debt unless either (a) the ratio of (i) the
aggregate consolidated principal amount of Debt of the Company outstanding as of
the most recent available quarterly or annual balance sheet, after giving pro
forma effect to the Incurrence of such Debt and any other Debt Incurred since
such balance sheet date and the receipt and application of the proceeds thereof
to (ii) Consolidated Cash Flow Available for Fixed Charges for the four full
fiscal quarters next preceding the Incurrence of such Debt for which
consolidated financial statements are available, determined on a pro forma basis
as if (x) any such Debt had been Incurred and the proceeds thereof had been
applied at the beginning of such four fiscal quarters, (y) the net income (or
loss) for such period of any Person or related to any assets disposed of by the
Company or a Restricted Subsidiary of the Company prior to the end of such
period had been excluded from Consolidated Net Income and (z) the net income (or
loss) for such period of any Person or related to any assets acquired by the
Company or any Restricted Subsidiary prior to the end of such period had been
included in Consolidated Net Income, would be less than 5.5 to 1 for such
four-quarter periods ending on or prior to December 31, 1999 and 5.0 to 1 for
such periods ending thereafter, or (b) the Company's Consolidated Capital Ratio
as of the most recent available quarterly or annual balance sheet, after giving
pro forma effect to the Incurrence of such Debt, any issuance of Capital Stock
(other than Disqualified Stock) since such balance sheet date, any increase in
paid in-capital (other than in respect of Disqualified Stock) since such balance
sheet date and the Incurrence of any other Debt since such balance sheet date
and the receipt and application of the proceeds thereof, is less than 2.0 to 1.



<PAGE>   100

               Notwithstanding the foregoing limitation, the Company and any
Restricted Subsidiary may Incur the following:

               (i) Debt under any one or more Bank Credit Agreements or Vendor
        Financing Facilities in an aggregate principal amount at any one time
        not to exceed the greater of (x) $175 million and (y) 85% of the
        Eligible Receivables, and any renewal, extension, refinancing or
        refunding thereof in an amount which, together with any principal amount
        remaining outstanding or available under all Bank Credit Agreements and
        Vendor Financing Facilities of the Company and its Restricted
        Subsidiaries, plus the amount of any premium required to be paid in
        connection with such refinancing pursuant to the terms of any Bank
        Credit Agreement so refinanced plus the amount of expenses incurred in
        connection with such refinancing, does not exceed the aggregate
        principal amount outstanding or available under all such Bank Credit
        Agreements and Vendor Financing Facilities of the Company and its
        Restricted Subsidiaries immediately prior to such renewal, extension,
        refinancing or refunding;

               (ii) Purchase Money Debt Incurred to finance the construction,
        acquisition or improvement of Telecommunications Assets, provided that
        the net proceeds of such Purchase Money Debt do not exceed 100% of the
        cost of construction, acquisition or improvement price of the applicable
        Telecommunications Assets;

               (iii) Debt owed by the Company to any Restricted Subsidiary of
        the Company or Debt owed by a Restricted Subsidiary of the Company to
        the Company or a Restricted Subsidiary of the Company; provided,
        however, that upon either (x) the transfer or other disposition by such
        Restricted Subsidiary or the Company of any Debt so permitted to a
        Person other than the Company or another Restricted Subsidiary of the
        Company or (y) the issuance (other than directors' qualifying shares),
        sale, lease, transfer or other disposition of shares of Capital Stock
        (including by consolidation or merger) of such Restricted Subsidiary as
        a result of which the obligor of such Debt ceases to be a Restricted
        Subsidiary, the provisions of this clause (iii) shall no longer be
        applicable to such Debt and such Debt shall be deemed to have been
        Incurred at the time of such transfer or other disposition;

               (iv) Debt Incurred to renew, extend, refinance or refund (each, a
        "refinancing") Debt outstanding at the date of this Indenture or
        Incurred pursuant to the preceding paragraph or clause (ii) of this
        paragraph or the Securities in an aggregate principal amount not to
        exceed the aggregate principal amount of and accrued interest on the
        Debt so refinanced plus the amount of any premium required to be paid in
        connection with such 



                                      -89-

<PAGE>   101

        refinancing pursuant to the terms of the Debt so refinanced or the
        amount of any premium reasonably determined by the Company as necessary
        to accomplish such refinancing by means of a tender offer or privately
        negotiated repurchase, plus the amount of expenses of the Company
        incurred in connection with such refinancing; provided, however, that
        Debt the proceeds of which are used to refinance the Securities or Debt
        which is pari passu to the Securities or debt which is subordinate in
        right of payment to the Securities shall only be permitted if (A) in the
        case of any refinancing of the Securities or Debt which is pari passu to
        the Securities, the refinancing Debt is made pari passu to the
        Securities or subordinated to the Securities, and, in the case of any
        refinancing of Debt which is subordinated to the Securities, the
        refinancing Debt constitutes Subordinated Debt and (B) in either case,
        the refinancing Debt by its terms, or by the terms of any agreement or
        instrument pursuant to which such Debt is issued, (x) does not provide
        for payments of principal of such Debt at the stated maturity thereof or
        by way of a sinking fund applicable thereto or by way of any mandatory
        redemption, defeasance, retirement or repurchase thereof by the Company
        (including any redemption, retirement or repurchase which is contingent
        upon events or circumstances, but excluding any retirement required by
        virtue of acceleration of such Debt upon any event of default
        thereunder), in each case prior to the time the same are required by the
        terms of the Debt being refinanced and (y) does not permit redemption or
        other retirement (including pursuant to an offer to purchase made by the
        Company) of such Debt at the option of the holder thereof prior to the
        final stated maturity of the Debt being refinanced, other than a
        redemption or other retirement at the option of the holder of such Debt
        (including pursuant to an offer to purchase made by the Company) which
        is conditioned upon a change substantially similar to the provisions of
        Section 1016 or which is pursuant to provisions substantially similar to
        the provisions of Section 1013;

               (v)  Debt consisting of Permitted Interest Rate and Currency
        Protection Agreements;

               (vi)  Debt outstanding under the Securities;

               (vii) Subordinated Debt invested by (a) a group of employees of
        the Company, which includes the Chief Executive Officer of the Company,
        who own, directly or indirectly, through an employee stock ownership
        plan or arrangement, shares of the Company's Capital Stock or (b) any
        other Person that controls the Company (i) on the Issue Date or (ii)
        after a Change of Control, provided that the Company is not in default
        with respect to its obligations under Section 1016;



<PAGE>   102

               (viii) Debt consisting of performance and other similar bonds and
        reimbursement obligations Incurred in the ordinary course of business
        securing the performance of contractual, franchise or license
        obligations of the Company or a Restricted Subsidiary, or in respect of
        a letter of credit obtained to secure such performance; and

               (ix) Debt not otherwise permitted to be Incurred pursuant to
        clauses (i) through (viii) above, which, together with any other
        outstanding Debt Incurred pursuant to this clause (ix), has an aggregate
        principal amount (or, in the case of Debt issued at a discount, an
        accreted amount (determined in accordance with generally accepted
        accounting principles) at the time of Incurrence) not in excess of $10
        million at any time outstanding.

               For purposes of determining compliance with this Section 1007, in
the event that an item of Debt meets the criteria of more than one of the types
of Debt the Company is permitted to incur pursuant to the foregoing clauses (i)
through (ix) or the first paragraph of this Section 1007, the Company shall have
the right, in its sole discretion, to classify such item of Debt and shall only
be required to include the amount and type of such Debt under the clause or
paragraph permitting the Debt as so classified. For purposes of determining any
particular amount of Debt under such covenant, Guarantees or Liens with respect
to letters of credit supporting Debt otherwise included in the determination of
a particular amount shall not be included.


SECTION 1008.  Limitation on Debt and Preferred Stock of Restricted
               Subsidiaries.

               The Company may not permit any Restricted Subsidiary of the
Company (other than a Restricted Subsidiary that has fully and unconditionally
Guaranteed the Securities on an unsubordinated basis) to Incur or suffer to
exist any Debt or issue any Preferred Stock except:

               (i) Debt or Preferred Stock outstanding on the date of this
        Indenture after giving effect to the application of the proceeds of the
        Securities;

               (ii) Debt Incurred or Preferred Stock issued to and held by the
        Company or a Restricted Subsidiary of the Company (provided that such
        Debt or Preferred Stock is at all times held by the Company or a
        Restricted Subsidiary of the Company);



                                      -91-

<PAGE>   103

               (iii) Debt Incurred or Preferred Stock issued by a Person prior
        to the time (A) such Person became a Restricted Subsidiary of the
        Company, (B) such Person merges into or consolidates with a Restricted
        Subsidiary of the Company or (C) another Restricted Subsidiary of the
        Company merges into or consolidates with such Person (in a transaction
        in which such Person becomes a Restricted Subsidiary of the Company),
        which Debt or Preferred Stock was not Incurred or issued in anticipation
        of such transaction and was outstanding prior to such transaction;

               (iv)  Debt consisting of Permitted Interest Rate and Currency
        Protection Agreements;

               (v)   Debt or Preferred Stock of a Joint Venture;

               (vi) Debt under any one or more Bank Credit Agreements or Vendor
        Financing Facilities (and renewals, extensions, refinancings or
        refundings thereof) which is permitted to be outstanding under clause
        (i) of Section 1007;

               (vii)   Debt consisting of Guarantees of the Securities;

               (viii) Debt or Preferred Stock which is exchanged for, or the
        proceeds of which are used to refinance, refund or redeem, any Debt or
        Preferred Stock permitted to be outstanding pursuant to clauses (i),
        (iii) and (ix) hereof (or any extension or renewal thereof) (for
        purposes hereof, a "refinancing"), in an aggregate principal amount, in
        the case of Debt, or with an aggregate liquidation preference, in the
        case of Preferred Stock, not to exceed the aggregate principal amount of
        the Debt so refinanced or the aggregate liquidation preference of the
        Preferred Stock so refinanced, plus the amount of any premium required
        to be paid in connection with such refinancing pursuant to the terms of
        the Debt or Preferred Stock so refinanced or the amount of any premium
        reasonably determined by the Company as necessary to accomplish such
        refinancing by means of a tender offer or privately negotiated
        repurchase, plus the amount of expenses of the Company and the
        Restricted Subsidiary incurred in connection therewith and provided the
        Debt or Preferred Stock incurred or issued upon such refinancing by its
        terms, or by the terms of any agreement or instrument pursuant to which
        such Debt or Preferred Stock is Incurred or issued, (x) does not provide
        for payments of principal or liquidation value at the stated maturity of
        such Debt or Preferred Stock or by way of a sinking fund applicable to
        such Debt or Preferred Stock or by way of any mandatory redemption,
        defeasance, retirement or repurchase of such Debt or Preferred Stock by
        the Company or any Restricted Subsidiary of the Company (including any
        redemption, retirement or repurchase which is contingent upon events or
        circumstances, but 



<PAGE>   104

        excluding any retirement required by virtue of acceleration of such Debt
        upon an event of default thereunder), in each case prior to the time the
        same are required by the terms of the Debt or Preferred Stock being
        refinanced and (y) does not permit redemption or other retirement
        (including pursuant to an offer to purchase made by the Company or a
        Restricted Subsidiary of the Company) of such Debt or Preferred Stock at
        the option of the holder thereof prior to the stated maturity of the
        Debt or Preferred Stock being refinanced, other than a redemption or
        other retirement at the option of the holder of such Debt or Preferred
        Stock (including pursuant to an offer to purchase made by the Company or
        a Restricted Subsidiary of the Company) which is conditioned upon the
        change of control of the Company pursuant to provisions substantially
        similar to the provisions of Section 1016 or which is pursuant to
        provisions substantially similar to the provisions of Section 1013, and
        provided, further, that in the case of any exchange or redemption of
        Preferred Stock of a Restricted Subsidiary of the Company, such
        Preferred Stock may only be exchanged for or redeemed with Preferred
        Stock of such Restricted Subsidiary;

               (ix) Purchase Money Debt Incurred to finance the construction,
        acquisition or improvement of Telecommunications Assets, provided that
        the net proceeds of such Purchase Money Debt do not exceed 100% of the
        cost of construction, acquisition or improvement price of the applicable
        Telecommunications Assets; and

               (x) Debt consisting of performance and other similar bonds and
        reimbursement obligations Incurred in the ordinary course of business
        securing the performance of contractual, franchise or license
        obligations of the Company or a Restricted Subsidiary, or in respect of
        a letter of credit obtained to secure such performance; and

               (xi) Debt not otherwise permitted to be incurred pursuant to
        clauses (i) through (x) above, which, together with any other
        outstanding Debt incurred pursuant to this clause (xi), has an aggregate
        principal amount (or, in the case of Debt issued at a discount, an
        accreted amount (determined in accordance with generally accepted
        accounting principles) at the time of Incurrence) not in excess of $10
        million at any time outstanding.

        For purposes of determining compliance with this Section 1008, in the
event that an item of Debt meets the criteria of more than one of the types of
Debt a Restricted Subsidiary of the Company is permitted to incur pursuant to
the foregoing clauses (i) through (xi), the Company shall have the right, in its
sole discretion, to classify such item of Debt and shall be only required to
include 



                                      -93-

<PAGE>   105

the amount and type of such Debt under the clause permitting the Debt as so
classified. For purposes of determining any particular amount of Debt under such
covenant, Guarantees or Liens with respect to letters of credit supporting Debt
or otherwise included in the determination of a particular amount shall not be
included.



<PAGE>   106

SECTION 1009.  Limitation on Restricted Payments.



                                      -95-

<PAGE>   107

               The Company (i) may not, directly or indirectly, declare or pay
any dividend, or make any distribution, in respect of its Capital Stock or to
the holders thereof (in their capacity as such), excluding any dividends or
distributions payable solely in shares of its Capital Stock (other than
Disqualified Stock) or in options, warrants or other rights to acquire its
Capital Stock (other than Disqualified Stock); (ii) may not, and may not permit
any Restricted Subsidiary to, purchase, redeem, or otherwise retire or acquire
for value (a) any Capital Stock of the Company or any Related Person of the
Company; or (b) any options, warrants or rights to purchase or acquire shares of
Capital Stock of the Company or any Related Person of the Company or any
securities convertible or exchangeable into shares of Capital Stock of the
Company or any Related Person of the Company; (iii) may not make, or permit any
Restricted Subsidiary to make, any Investment in, or payment on a Guarantee of
any obligation of, any Person, other than the Company or a Restricted Subsidiary
of the Company, except for Permitted Investments; and (iv) may not, and may not
permit any Restricted Subsidiary to, redeem, defease, repurchase, retire or
otherwise acquire or retire for value, prior to any scheduled maturity,
repayment or sinking fund payment, Debt of the Company which is subordinate in
right of payment to the Securities (each of clauses (i) through (iv) being a
"Restricted Payment") if: (1) a Default or an Event of Default shall have
occurred and is continuing; or (2) upon giving effect to such Restricted
Payment, the Company could not Incur at least $1.00 of additional Debt pursuant
to the provisions of the first paragraph of Section 1007; or (3) upon giving
effect to such Restricted Payment, the aggregate of all Restricted Payments from
April 25, 1996 exceeds the sum of: (a) 50% of cumulative Consolidated Net Income
(or, in the case Consolidated Net Income shall be negative, less 100% of such
deficit) since the end of the last full fiscal quarter prior to April 25, 1996
through the last day of the last full fiscal quarter ending immediately
preceding the date of such Restricted Payment; plus (b) $5 million; plus (c)
100% of the net reduction in Investments in any Unrestricted Subsidiary
resulting from payments of interest on Debt, dividends, repayments of loans or
advances, or other transfers of assets, in each case to the Company or any
Restricted Subsidiary of the Company from such Unrestricted Subsidiary (except
to the extent that any such payment is included in the calculation of
Consolidated Net Income) or from redesignations of Unrestricted Subsidiaries as
Restricted Subsidiaries; provided that the amount included in this clause (c)
shall not exceed the amount of Investments previously made by the Company and
its Restricted Subsidiaries in such Unrestricted Subsidiary; provided, further,
that the Company or a Restricted Subsidiary of the Company may make any
Restricted Payment with the aggregate net proceeds received after April 25,
1996, including the fair value of property other than cash (determined in good
faith by the Board of Directors, as conclusively evidenced by a Board Resolution
filed with the Trustee), as capital contributions to the Company or from the
issuance (other than to a Restricted Subsidiary) of Capital Stock (other than
Disqualified Stock) of the Company and warrants, rights or options on Capital
Stock (other than Disqualified Stock) of the Company and the



<PAGE>   108

principal amount of Debt of the Company that has been converted into Capital
Stock (other than Disqualified Stock and other than by a Restricted Subsidiary)
of the Company after April 25, 1996.

               Notwithstanding the foregoing, the Company may (i) pay any
dividend on Capital Stock of any class within 60 days after the declaration
thereof if, on the date when the dividend was declared, the Company could have
paid such dividend in accordance with the foregoing provisions; (ii) repurchase
any shares of its Common Equity or options to acquire its Common Equity from
Persons who were formerly officers or employees of the Company, provided that
the aggregate amount of all such repurchases made pursuant to this clause (ii)
shall not exceed $2 million, plus the aggregate cash proceeds received by the
Company since April 25, 1996 from issuances of its Common Equity or options to
acquire its Common Equity to members, officers, managers, directors and
employees of the Company or any of its Subsidiaries; (iii) the Company and its
Restricted Subsidiaries may refinance any Debt otherwise permitted by clause
(iv) of the second paragraph of Section 1007; and (iv) the Company and its
Restricted Subsidiaries may retire or repurchase any Capital Stock or
Subordinated Debt of the Company in exchange for, or out of the proceeds of the
substantially concurrent sale (other than to a Restricted Subsidiary of the
Company) of, Capital Stock (other than Disqualified Stock) of the Company. If
the Company makes a Restricted Payment which, at the time of the making of such
Restricted Payment, would in the good faith determination of the Company be
permitted under this Indenture, such Restricted Payment shall be deemed to have
been made in compliance with this Indenture notwithstanding any subsequent
adjustments made in good faith to the Company financial statements affecting
Consolidated Net Income for any period.

        In determining the aggregate amount expended or available for Restricted
Payments in accordance with clause (3) of the first paragraph above, (1) no
amounts expended under clauses (iii) or (iv) of the immediately preceding
paragraph shall be included, (2) 100% of the amounts expended under clauses (i)
and (ii) of the immediately preceding paragraph shall be included, and (3) no
amount shall be credited in respect of issuances of Capital Stock in
transactions under clause (iv) of the immediately preceding paragraph.



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<PAGE>   109

SECTION 1010.  Limitation on Dividend and Other Payment Restrictions Affecting
               Restricted Subsidiaries.




<PAGE>   110


               The Company may not, and may not permit any Restricted Subsidiary
to, directly or indirectly, create or otherwise cause or suffer to exist or
become effective any consensual encumbrance or restriction on the ability of any
Restricted Subsidiary of the Company (i) to pay dividends (in cash or otherwise)
or make any other distributions in respect of its Capital Stock owned by the
Company or any other Restricted Subsidiary of the Company or pay any Debt or
other obligation owed to the Company or any other Restricted Subsidiary; (ii) to
make loans or advances to the Company or any other Restricted Subsidiary; or
(iii) to transfer any of its property or assets to the Company or any other
Restricted Subsidiary. Notwithstanding the foregoing, the Company may, and may
permit any Restricted Subsidiary to, suffer to exist any such encumbrance or
restriction (a) pursuant to any agreement in effect on the Issue Date; (b)
pursuant to an agreement relating to any Acquired Debt, which encumbrance or
restriction is not applicable to any Person, or the properties or assets of any
Person, other than the Person so acquired and its Subsidiaries; (c) pursuant to
any one or more Bank Credit Agreements or Vendor Financing Facilities (and
renewals, extensions, refinancings or refundings thereof) which is permitted to
be outstanding under clause (i) of Section 1007, provided that such restriction
is consistent with, and not materially more restrictive (as conclusively
determined in good faith by the Chief Financial Officer of the Company), taken
as a whole, than, comparable provisions included in similar agreements or
facilities extended to comparable credits engaged in the Telecommunications
Business; (d) pursuant to an agreement effecting a renewal, refunding or
extension of Debt Incurred pursuant to an agreement referred to in clause (a) or
(b) above or (e) below, provided, however, that the provisions contained in such
renewal, refunding or extension agreement relating to such encumbrance or
restriction are not materially more restrictive (as conclusively determined in
good faith by the Chief Financial Officer of the Company), taken as a whole,
than the provisions contained in the agreement the subject thereof; (e) in the
case of clause (iii) above, restrictions contained in any security agreement
(including a Capital Lease Obligation) securing Debt of the Company or a
Restricted Subsidiary otherwise permitted under this Indenture, but only to the
extent such restrictions restrict the transfer of the property subject to such
security agreement; (f) in the case of clause (iii) above, customary
nonassignment provisions entered into in the ordinary course of business in
leases and other agreements; (g) any restriction with respect to a Restricted
Subsidiary of the Company imposed pursuant to an agreement which has been
entered into for the sale or disposition of all or substantially all of the
Capital Stock or assets of such Restricted Subsidiary, provided that
consummation of such transaction would not result in a Default or an Event of
Default, that such restriction terminates if such transaction is not consummated
and that such consummation or abandonment of such transaction occurs within one
year of the date such agreement was entered into; (h) pursuant to applicable law
or regulations; (i) pursuant to this Indenture and the Securities; or (j) any
restriction on the sale or other disposition of assets or 



                                      -99-

<PAGE>   111

property securing Debt as a result of a Permitted Lien on such assets or
property.


SECTION 1011.  Limitation on Liens.

               The Company may not, and may not permit any Restricted Subsidiary
of the Company to, Incur or suffer to exist any Lien on or with respect to any
property or assets now owned or hereafter acquired to secure any Debt without
making, or causing such Restricted Subsidiary to make, effective provision for
securing the Securities (x) equally and ratably with (or prior to) such Debt as
to such property for so long as such Debt will be so secured or (y) in the event
such Debt is Debt of the Company which is subordinate in right of payment to the
Securities, prior to such Debt as to such property for so long as such Debt will
be so secured.

               The foregoing restrictions shall not apply to: (i) Liens existing
on the Issue Date and securing Debt outstanding on the Issue Date or securing
the Securities or Liens securing Debt Incurred pursuant to any Bank Credit
Agreement or Vendor Financing Facility (whether or not such Bank Credit
Agreement or Vendor Financing Facility was outstanding on the Issue Date); (ii)
Liens securing Debt in an amount which, together with the aggregate amount of
Debt then outstanding or available under the Bank Credit Agreement and Vendor
Financing Facility (or under refinancings or amendments of such agreements),
does not exceed 1.5 times the Company's Consolidated Cash Flow Available for
Fixed Charges for the four full fiscal quarters preceding the Incurrence of such
Lien for which consolidated financial statements are available, determined on a
pro forma basis as if such Debt had been Incurred and the proceeds thereof had
been applied at the beginning of such four fiscal quarters; (iii) Liens in favor
of the Company or any Wholly-Owned Restricted Subsidiary of the Company; (iv)
Liens on real or personal property of the Company or a Restricted Subsidiary of
the Company acquired, constructed or constituting improvements made after the
Issue Date to secure Purchase Money Debt which is Incurred for the construction,
acquisition and improvement of Telecommunications Assets and is otherwise
permitted under this Indenture, provided, however, that (a) the net proceeds of
any Debt secured by such a Lien does not exceed 100% of such purchase price or
cost of construction or improvement of the property subject to such Lien, (b)
such Lien attaches to such property prior to, at the time of or within 180 days
after the acquisition, completion of construction or commencement of operation
of such property and (c) such Lien does not extend to or cover any property
other than the property (or identifiable portions thereof) acquired, constructed
or constituting the improvements made with the proceeds of such Purchase Money
Debt (it being understood and agreed that all Debt owed to any single lender or
group of lenders or outstanding under any single credit facility shall be
considered a 



<PAGE>   112

single Purchase Money Debt, whether drawn at one time or from time to time); (v)
Liens to secure Acquired Debt, provided, however, that (a) such Lien attaches to
the acquired asset prior to the time of the acquisition of such asset and (b)
such Lien does not extend to or cover any other asset; (vi) Liens to secure Debt
Incurred to extend, renew, refinance or refund (or successive extensions,
renewals, refinancings or refundings), in whole or in part, Debt secured by any
Lien referred to in the foregoing clauses (i), (ii), (iv) and (v) so long as
such Lien does not extend to any other property and the principal amount of Debt
so secured is not increased except as otherwise permitted under clause (iv) of
Section 1007; (vii) Liens securing Debt not otherwise permitted by the foregoing
clauses (i) through (vi) in an amount not to exceed 5% of the Company's
Consolidated Tangible Assets determined as of the most recent available
quarterly or annual balance sheet; and (viii) Permitted Liens.


SECTION 1012.  Limitation on Sale and Leaseback Transactions.

               The Company may not, and may not permit any Restricted Subsidiary
to, enter into any Sale and Leaseback Transaction unless (i) the Company or such
Restricted Subsidiary would be entitled to Incur a Lien to secure Debt by reason
of the provisions of Section 1011, equal in amount to the Attributable Value of
the Sale and Leaseback Transaction without equally and ratably securing the
Securities; or (ii) the Sale and Leaseback Transaction is treated as an Asset
Disposition and all of the conditions of Section 1013 (including the provisions
concerning the application of Net Available Proceeds) are satisfied with respect
to such Sale and Leaseback Transaction, treating all of the consideration
received in such Sale and Leaseback Transaction in the same manner as
consideration in respect of an Asset Disposition for purposes of such covenant.



                                     -101-

<PAGE>   113

SECTION  1013.  Limitation on Asset Dispositions.

               (a) The Company may not, and may not permit any Restricted
Subsidiary to, make any Asset Disposition in one or more related transactions
occurring within any 12month period unless: (i) the Company or the Restricted
Subsidiary, as the case may be, receives consideration for such disposition at
least equal to the fair market value for the assets sold or disposed of as
determined by the Board of Directors in good faith and evidenced by a Board
Resolution filed with the Trustee, which determination shall be conclusive; (ii)
at least 75% of the consideration for such disposition consists of (1) cash or
readily marketable cash equivalents or the assumption of Debt of the Company
(other than Debt that is subordinated to the Securities) or of the Restricted
Subsidiary and release from all liability on the Debt assumed; (2)
Telecommunications Assets; or (3) shares of publicly-traded Voting Stock of any
Person engaged in the Telecommunications Business in the United States; and
(iii) all Net Available Proceeds, less any amounts invested in
Telecommunications Assets (within 180 days prior to and 360 days following such
disposition), are applied within 360 days of such disposition (1) first, to the
permanent repayment or reduction of Debt then outstanding under any Bank Credit
Agreement or Vendor Financing Facility, to the extent such agreements would
require such application or prohibit payments pursuant to clause (2) following,
(2) second, to the extent of remaining Net Available Proceeds, to make an Offer
to Purchase outstanding Securities at 100% of their Accreted Value (if such
Offer to Purchase is made on or before April 15, 2003) or 100% of their
principal amount plus accrued interest to the date of purchase (if such Offer to
Purchase is made thereafter) and, to the extent required by the terms thereof,
any other Debt of the Company that is pari passu with the Securities at a price
no greater than 100% of the principal amount thereof plus accrued interest to
the date of purchase (or 100% of the accreted value in the case of original
issue discount Debt) and (3) third, to the extent of any remaining Net Available
Proceeds following the completion of the Offer to Purchase, to the repayment of
other Debt of the Company or Debt of a Restricted Subsidiary of the Company, to
the extent permitted under the terms thereof. To the extent any Net Available
Proceeds remain after such uses, the Company and its Restricted Subsidiaries may
use such amounts for any purposes not prohibited by this Indenture.

               (b) The Company will mail the Offer for an Offer to Purchase
required pursuant to Section 1013(a) not more than 360 days after consummation
of the disposition referred to in Section 1013(a). The aggregate principal
amount of the Securities to be offered to be purchased pursuant to the Offer to
Purchase shall equal the Net Available Proceeds available therefor pursuant to
Clause (iii)(2) of Section 1013(a) (rounded down to the next lowest integral
multiple of $1,000). Each Holder shall be entitled to tender all or any portion
of the Securities owned by such Holder pursuant to the Offer to



<PAGE>   114

Purchase, subject to the requirement that any portion of a Security tendered
must be tendered in an integral multiple of $1,000 principal amount.

               The Company shall not be entitled to any credit against its
obligations under this Section 1013 for the principal amount of any Securities
acquired or redeemed by the Company otherwise than pursuant to the Offer to
Purchase pursuant to this Section 1013.

               (c) Not later than the date of the Offer with respect to an Offer
to Purchase pursuant to this Section 1013, the Company shall deliver to the
Trustee an Officers' Certificate as to (i) the Purchase Amount, (ii) the
allocation of the Net Available Proceeds from the Asset Disposition pursuant to
which such Offer is being made, including, if amounts are invested in
Telecommunication Assets, the amount of the assets acquired and (iii) the
compliance of such allocation with the provisions of Section 1013(a).

               The Company and the Trustee shall perform their respective
obligations specified in the Offer for the Offer to Purchase. On or prior to the
Purchase Date, the Company shall (i) accept for payment (on a pro rata basis, if
necessary) Securities or portions thereof tendered pursuant to the Offer, (ii)
deposit with the Paying Agent (or, if the Company is acting as its own Paying
Agent, segregate and hold in trust as provided in Section 1003) money sufficient
to pay the purchase price of all Securities or portions thereof so accepted and
(iii) deliver or cause to be delivered to the Trustee all Securities so accepted
together with an Officers' Certificate stating the Securities or portions
thereof accepted for payment by the Company. The Paying Agent (or the Company,
if so acting) shall promptly mail or deliver to Holders of Securities so
accepted payment in an amount equal to the purchase price, and the Trustee shall
promptly authenticate and mail or deliver to such Holders a new Security of like
tenor equal in principal amount to any unpurchased portion of the Security
surrendered. Any Security not accepted for payment shall be promptly mailed or
delivered by the Company to the Holder thereof.

               (d) Notwithstanding the foregoing, this Section 1013 shall not
apply to any Asset Disposition which constitutes a transfer, conveyance, sale,
lease or other disposition of all or substantially all of the Company's
properties or assets within the meaning of Section 801 hereof.



                                     -103-

<PAGE>   115

SECTION 1014.  Limitation on Issuances and Sales of Capital Stock of Restricted
               Subsidiaries.

               The Company may not, and may not permit any Restricted Subsidiary
of the Company to, issue, transfer, convey, sell or otherwise dispose of any
shares of Capital Stock of a Restricted Subsidiary of the Company or securities
convertible or exchangeable into, or options, warrants, rights or any other
interest with respect to, Capital Stock of a Restricted Subsidiary of the
Company to any person other than the Company or a Wholly-Owned Restricted
Subsidiary of the Company except (i) in a transaction consisting of a sale of
Capital Stock of such Restricted Subsidiary owned by the Company or any
Restricted Subsidiary of the Company and that complies with the provisions of
Section 1013 to the extent such provisions apply; (ii) if required, the
issuance, transfer, conveyance, sale or other disposition of directors'
qualifying shares; (iii) in a transaction in which, or in connection with which,
the Company or a Restricted Subsidiary acquires at the same time sufficient
Capital Stock of such Restricted Subsidiary to at least maintain the same
percentage ownership interest it had prior to such transaction; (iv)
constituting the issuance of Preferred Stock permitted by the provisions of
Section 1008; and (v) Disqualified Stock issued in exchange for, or upon
conversion of, or the proceeds of the issuance of which are used to redeem,
refinance, replace or refund shares of Disqualified Stock of such Restricted
Subsidiary, provided that the amounts of the redemption obligations of such
Disqualified Stock shall not exceed the amounts of the redemption obligations
of, and such Disqualified Stock shall have redemption obligations no earlier
than those required by, the Disqualified Stock being exchanged, converted,
redeemed, refinanced, replaced or refunded.



<PAGE>   116

SECTION 1015.  Transactions with Affiliates and Related Persons.

               The Company may not, and may not permit any Restricted Subsidiary
of the Company to, enter into any transaction (or series of related
transactions) with an Affiliate or Related Person of the Company (other than the
Company or a Wholly-Owned Restricted Subsidiary of the Company), including any
Investment, but excluding transactions pursuant to employee compensation
arrangements approved by the Board of Directors, either directly or indirectly,
unless such transaction is on terms no less favorable to the Company or such
Restricted Subsidiary than those that could reasonably be obtained in a
comparable arm's-length transaction with an entity that is not an Affiliate or
Related Person and is in the best interests of such Company or such Restricted
Subsidiary. For any transaction that involves in excess of $1 million but less
than or equal to $15 million, the Chief Executive Officer of the Company shall
determine that the transaction satisfies the above criteria and shall evidence
such a determination by an Officer's Certificate filed with the Trustee. For any
transaction that involves in excess of $15 million, the Company shall also
obtain an opinion from a nationally recognized expert with experience in
appraising the terms and conditions, taken as a whole, of the type of
transaction (or series of related transactions) for which the opinion is
required stating that such transaction (or series of related transactions) is on
terms and conditions, taken as a whole, no less favorable to the Company or such
Restricted Subsidiary than those that could be obtained in a comparable
arm's-length transaction with an entity that is not an Affiliate or Related
Person of the Company, which opinion shall be filed with the Trustee. This
covenant shall not apply to Investments by an Affiliate or a Related Person of
the Company in the Capital Stock (other than Disqualified Stock) of the Company
or any Restricted Subsidiary of the Company.


SECTION 1016.  Change of Control.

               (a) Within 30 days of the occurrence of a Change of Control, the
Company will be required to make an Offer to Purchase all Outstanding Securities
at a purchase price equal to 101% of their Accreted Value (if such Offer to
Purchase is made on or prior to April 15, 2003) or 101% of their principal
amount plus accrued and unpaid interest to the date of purchase (if such Offer
to Purchase is consummated thereafter).

               (b) The Company and Trustee shall perform their respective
obligations specified in the Offer for the Offer to Purchase. On or prior to the
Purchase Date, the Company shall (i) accept for payment Securities or portions
thereof tendered pursuant to the Offer, (ii) deposit with the Paying Agent (or,
if 



                                     -105-

<PAGE>   117

the Company is acting as its own Paying Agent, segregate and hold in trust as
provided in Section 1003) money sufficient to pay the purchase price of all
Securities or portions thereof so accepted and (iii) deliver or cause to be
delivered to the Trustee all Securities so accepted together with an Officers'
Certificate stating the Securities or portions thereof accepted for payment by
the Company. The Paying Agent shall promptly mail or deliver to Holders of
Securities so accepted payment in an amount equal to the purchase price, and the
Trustee shall promptly authenticate and mail or deliver to such Holders a new
Security or Securities equal in principal amount to any unpurchased portion of
the Security surrendered as requested by the Holder. Any Security not accepted
for payment shall be promptly mailed or delivered by the Company to the Holder
thereof.

               (c) A "Change of Control" will be deemed to have occurred at such
time as either (a) any Person or any Persons acting together that would
constitute a "group" (a "Group") for purposes of Section 13(d) of the Exchange
Act, or any successor provision thereto (other than Eagle River, Mr. Craig O.
McCaw and their respective Affiliates or an underwriter engaged in a firm
commitment underwriting on behalf of the Company), shall beneficially own
(within the meaning of Rule 13d-3 under the Exchange Act, or any successor
provision thereto) more than 50% of the aggregate voting power of all classes of
Voting Stock of the Company; or (b) neither Mr. Craig O. McCaw nor any person
designated by him to the Company as acting on his behalf shall be a director of
the Company; or (c) during any period of two consecutive years, individuals who
at the beginning of such period constituted the Board of Directors (together
with any new directors whose election by the Board of Directors or whose
nomination for election by the shareholders of the Company was proposed by a
vote of a majority of the directors of the Company then still in office who were
either 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 Board of Directors then in office.

               (d) In the event that the Company makes an Offer to Purchase the
Securities, the Company intends to comply with any applicable securities laws
and regulations, including any applicable requirements of Section 14(e) of, and
Rule 14e-1 under, the Exchange Act.

               (e) Unless the Company defaults in the payment of the Purchase
Price, any Security accepted for payment pursuant to an Offer to Purchase shall
cease to accrue interest after the Purchase Date.



<PAGE>   118

SECTION 1017.  Provision of Financial Information.

               The Company has agreed to file with the Trustee, within 15 days
after it files them with the Commission, copies of the SEC Reports. In the event
the Company shall cease to be required to file SEC Reports pursuant to the
Exchange Act, the Company will nevertheless continue to file such reports with
the Commission (unless the Commission will not accept such a filing) and the
Trustee. The Company will furnish copies of the SEC Reports to the Holders of
Securities at the time the Company is required to file the same with the Trustee
and will make such information available to investors who request it in writing.


SECTION  1018.  Statement by Officers as to Default.

               (a) The Company will deliver to the Trustee, within 90 days after
the end of each quarter of each fiscal year of the Company ending after the date
hereof, an Officers' Certificate, stating whether or not to the best knowledge
of the signers thereof the Company is in default in the performance and
observance of any of the terms, provisions and conditions of this Indenture and
if the Company shall be in default, specifying all such defaults and the nature
and status thereof of which they may have knowledge.

               (b) The Company shall deliver to the Trustee, as soon as possible
and in any event within 10 days after the Company becomes aware of the
occurrence of a Default or an Event of Default, an Officers' Certificate setting
forth the details of such Default or Event of Default and the action which the
Company proposes to take with respect thereto.


SECTION  1019.  Waiver of Certain Covenants.

               The Company may omit in any particular instance to comply with
any covenant or condition set forth in Sections 1004 to 1017, inclusive, if
before or after the time for such compliance the Holders of at least a majority
in aggregate principal amount of the Outstanding Securities shall, by Act of
such Holders, either waive such compliance in such instance or generally waive
compliance with such covenant or condition, but no such waiver shall extend to
or affect such covenant or condition except to the extent so expressly waived,
and, until such waiver shall become effective, the obligations of the Company
and the duties of the Trustee in respect of any such covenant or condition shall
remain in full force and effect.



                                     -107-

<PAGE>   119

                                 ARTICLE ELEVEN

                            Redemption of Securities

SECTION  1101.  Right of Redemption.

               (a) The Securities may be redeemed prior to April 15, 2003 only
in the event that on or before April 15, 2001 the Company receives net proceeds
from a sale of its Common Equity, in which case the Company may, at its option,
use all or a portion of any such net proceeds to redeem Securities in a
principal amount of up to an aggregate amount equal to 33 % of the original
principal amount of the Securities provided, however, that Securities in an
amount equal to at least 66 % of the original aggregate principal amount of the
Notes remain outstanding after such redemption. Such redemption must occur on a
Redemption Date within 90 days of any such sale and upon not less than 30 nor
more than 60 days' notice by mail to each Holder of Securities to be redeemed at
such Holder's address appearing in the Security Register, in amounts of $1,000
or an integral multiple of $1,000 at a Redemption Price of 109.450% of the
Accreted Value of the Securities to but excluding the Redemption Date.

               (b) The Securities further may be redeemed, as a whole or in
part, at the election of the Company, at any time on or after April 15, 2003 and
prior to maturity, upon not less than 30 nor more than 60 days' notice by mail
to each Holder of Securities to be redeemed at such Holder's address appearing
in the Security Register, in amounts of $1,000 or an integral multiple of
$1,000, at the Redemption Prices specified in the form of Security hereinbefore
set forth, together with accrued and unpaid interest to, but excluding, the
Redemption Date (subject to the right of Holders of record on the relevant
Regular Record Date to receive interest due on an Interest Payment Date that is
on or prior to the Redemption Date).


SECTION  1102.  Applicability of Article.

               Redemption of Securities at the election of the Company, as
permitted or required by any provision of this Indenture, shall be made in
accordance with such provision and this Article.



<PAGE>   120

SECTION  1103.  Election to Redeem; Notice to Trustee.

               The election of the Company to redeem any Securities pursuant to
Section 1101 shall be evidenced by Board Resolution. In case of any redemption
at the election of the Company of less than all the Securities, the Company
shall, at least 60 days prior to the Redemption Date fixed by the Company
(unless a shorter notice shall be satisfactory to the Trustee), notify the
Trustee in writing of such Redemption Date and of the principal amount of
Securities to be redeemed. In the case of any redemption of Securities prior to
the expiration of any restriction on such redemption provided in the terms of
such Securities or elsewhere in this Indenture, the Company shall furnish the
Trustee with an Officers' Certificate evidencing compliance with such
restriction.


SECTION  1104.  Securities to Be Redeemed Pro Rata.

               If less than all the Securities are to be redeemed in any
redemption, the Securities to be redeemed shall be selected by the Trustee by
prorating, as nearly as may be practicable, the principal amount of Securities
to be redeemed. In any proration pursuant to this Section, the Trustee shall
make such adjustments, reallocations and eliminations as it shall deem proper
(and in compliance with the requirements of the principal national securities
exchange, if any, on which the Securities are listed) to the end that the
principal amount of Securities so prorated shall be $1,000 or a multiple
thereof, by increasing or decreasing or eliminating the amount which would be
allocable to any Holder on the basis of exact proportion by an amount not
exceeding $1,000. The Trustee in its discretion may determine the particular
Securities (if there are more than one) registered in the name of any Holder
which are to be redeemed, in whole or in part.

               The Trustee shall promptly notify the Company and each Security
Registrar (other than the Trustee) in writing of the Securities selected for
redemption and, in the case of any Securities selected for partial redemption,
the principal amount thereof to be redeemed.

               For all purposes of this Indenture, unless the context otherwise
requires, all provisions relating to the redemption of Securities shall relate,
in the case of any Securities redeemed or to be redeemed only in part, to the
portion of the principal amount of such Securities which has been or is to be
redeemed.



                                     -109-

<PAGE>   121

SECTION  1105.  Notice of Redemption.

               Notice of redemption shall be given by first-class mail, postage
prepaid, mailed not less than 30 nor more than 60 days prior to the Redemption
Date, to each Holder of Securities to be redeemed, at such Holder's address
appearing in the Security Register.

               All notices of redemption shall state:

               (1)  the Redemption Date,

               (2)  the Redemption Price,

               (3) whether the redemption is being made pursuant to Section
        1101(a) or (b) and, if being made pursuant to Section 1101(a), a brief
        statement setting forth the Company's right to effect such redemption
        and the Company's basis therefor,

               (4) if less than all the Outstanding Securities are to be
        redeemed, the identification (and, in the case of partial redemption of
        any Securities, the principal amounts) of the particular Securities to
        be redeemed,

               (5) that on the Redemption Date the Redemption Price will become
        due and payable upon each such Security to be redeemed and that interest
        thereon will cease to accrue on and after said date,

               (6) the place or places where such Securities are to be
        surrendered for payment of the Redemption Price,

               (7) that in the case that a Security is only redeemed in part,
        the Company shall execute and the Trustee shall authenticate and deliver
        to the Holder of such Security without service charge, a new Security or
        Securities in an aggregate amount equal to the unredeemed portion of the
        Security,

               (8) the aggregate principal amount of Securities being redeemed,
        and

               (9) the CUSIP number or numbers of the Securities being redeemed.

               Notice of redemption of Securities to be redeemed at the election
of the Company shall be given by the Company or, if request is made to the
Trustee no less than 35 days prior to the Redemption Date, by the Trustee in the
name and at the expense of the Company.



<PAGE>   122

SECTION  1106.  Deposit of Redemption Price.

               Prior to any Redemption Date, the Company shall deposit with the
Trustee or with a Paying Agent (or, if the Company is acting as its own Paying
Agent, segregate and hold in trust as provided in Section 1003) an amount of
money sufficient to pay the Redemption Price of, and (except if the Redemption
Date shall be an Interest Payment Date) accrued and unpaid interest on, all the
Securities which are to be redeemed on that date.


SECTION  1107.  Securities Payable on Redemption Date.

               Notice of redemption having been given as aforesaid, the
Securities so to be redeemed shall, on the Redemption Date, become due and
payable at the Redemption Price therein specified, and from and after such date
(unless the Company shall default in the payment of the Redemption Price and
accrued and unpaid interest) such Securities shall cease to bear interest. Upon
surrender of any such Security for redemption in accordance with said notice,
such Security shall be paid by the Company at the Redemption Price, together
with accrued and unpaid interest to the Redemption Date; provided, however, that
installments of interest whose Stated Maturity is on or prior to the Redemption
Date shall be payable to the Holders of such Securities, or one or more
Predecessor Securities, registered as such at the close of business on the
relevant Record Dates according to their terms and the provisions of Section
307.

               If any Security called for redemption shall not be so paid upon
surrender thereof for redemption, the principal (and premium, if any) shall,
until paid, bear interest from the Redemption Date at the rate provided by the
Security.



                                     -111-

<PAGE>   123

SECTION  1108.  Securities Redeemed in Part.

               Any Security which is to be redeemed only in part shall be
surrendered at an office or agency of the Company designated for that purpose
pursuant to Section 1002 (with, if the Company or the Trustee so requires, due
endorsement by, or a written instrument of transfer in form satisfactory to the
Company and the Trustee duly executed by, the Holder thereof or his attorney
duly authorized in writing), and the Company shall execute, and the Trustee
shall authenticate and deliver to the Holder of such Security without service
charge, a new Security or Securities of like tenor, of any authorized
denomination as requested by such Holder, in aggregate principal amount equal to
and in exchange for the unredeemed portion of the principal of the Security so
surrendered. If a Global Security is so surrendered, such new Security shall
also be a Global Security.


                                 ARTICLE TWELVE

                       Defeasance and Covenant Defeasance

SECTION 1201.  Company's Option to Effect Defeasance or Covenant Defeasance.

               The Company may, at its option by Board Resolution at any time
(subject to 10-day prior written notification to the Trustee), elect to have
either Section 1202 or Section 1203 applied to the Outstanding Securities upon
compliance with the conditions set forth below in this Article Twelve.



<PAGE>   124

SECTION  1202.  Defeasance and Discharge.

               Upon the Company's exercise of the option provided in Section
1201 applicable to this Section, the Company shall be deemed to have been
discharged from its obligations with respect to the Outstanding Securities on
the date the conditions set forth below are satisfied (hereinafter,
"defeasance"). For this purpose, such defeasance means that the Company shall be
deemed to have paid and discharged the entire indebtedness represented by the
Outstanding Securities and to have satisfied all its other obligations under
such Securities and this Indenture insofar as such Securities are concerned (and
the Trustee, at the expense of the Company, shall execute proper instruments
acknowledging the same), except for the following which shall survive until
otherwise terminated or discharged hereunder: (A) the rights of Holders of
Outstanding Securities to receive, solely from the trust fund described in
Section 1204 and as more fully set forth in such Section, payments in respect of
the principal of (and premium, if any) and interest on such Securities when such
payments are due, (B) the Company's obligations with respect to such Securities
under Sections 304, 305, 306, 1002 and 1003, (C) the rights, powers, trusts,
duties and immunities of the Trustee hereunder and (D) this Article Twelve.
Subject to compliance with this Article Twelve, the Company may exercise its
option under this Section 1202 notwithstanding the prior exercise of its option
under Section 1203.


SECTION 1203.  Covenant Defeasance.

               Upon the Company's exercise of the option provided in Section
1201 applicable to this Section (i) the Company shall be released from its
obligations under Sections 1005 through 1017, inclusive, and Clauses (3) and (4)
of Section 801, (ii) the occurrence of an event specified in Sections 501(3),
501(4) (with respect to Clauses (3) and (4) of Section 801), and 501 (5) (with
respect to Sections 1005 through 1017, inclusive) shall not be deemed to be an
Event of Default, on and after the date the conditions set forth below are
satisfied (hereinafter, "covenant defeasance"). For this purpose, such covenant
defeasance means that the Company may omit to comply with and shall have no
liability in respect of any term, condition or limitation set forth in any such
Section or Article, whether directly or indirectly by reason of any reference
elsewhere herein to any such Section or Article or by reason of any reference in
any such Section or Article to any other provision herein or in any other
document, but the remainder of this Indenture and such Securities shall be
unaffected thereby.



                                     -113-

<PAGE>   125

SECTION 1204.  Conditions to Defeasance or Covenant Defeasance.

               The following shall be the conditions to application of either
Section 1202 or Section 1203 to the Outstanding Securities:

               (1) The Company shall irrevocably have deposited or caused to be
        deposited with the Trustee as trust funds in trust for the purpose of
        making the following payments, specifically pledged as security for, and
        dedicated solely to, the benefit of the Holders of such Securities, (A)
        money in an amount, or (B) U.S. Government Obligations which through the
        scheduled payment of principal and interest in respect thereof in
        accordance with their terms will provide, not later than one day before
        the due date of any payment, money in an amount, or (C) a combination
        thereof, sufficient, in the opinion of a nationally recognized firm of
        independent certified public accountants expressed in a written
        certification thereof delivered to the Trustee, to pay and discharge,
        and which shall be applied by the Trustee to pay and discharge, the
        principal of, premium, if any, and each installment of interest on the
        Securities on the Stated Maturity of such principal or installment of
        interest on the day on which such payments are due and payable in
        accordance with the terms of this Indenture and of such Securities. For
        this purpose, "U.S. Government Obligations" means securities that are
        (x) direct obligations of the United States of America for the payment
        of which its full faith and credit is pledged or (y) obligations of a
        Person controlled or supervised by and acting as an agency or
        instrumentality of the United States of America the payment of which is
        unconditionally guaranteed as a full faith and credit obligation by the
        United States of America, which, in either case, are not callable or
        redeemable at the option of the issuer thereof, and shall also include a
        depositary receipt issued by a bank (as defined in Section 3(a)(2) of
        the Securities Act) as custodian with respect to any such U.S.
        Government Obligation or a specific payment of principal of or interest
        on any such U.S. Government Obligation held by such custodian for the
        account of the holder of such depositary receipt, provided that (except
        as required by law) such custodian is not authorized to make any
        deduction from the amount payable to the holder of such depositary
        receipt from any amount received by the custodian in respect of the U.S.
        Government Obligation or the specific payment of principal of or
        interest on the U.S. Government Obligation evidenced by such depositary
        receipt.

               (2) No Default or Event of Default shall have occurred and be
        continuing on the date of such deposit or, insofar as subsections 501(8)
        and (9) are concerned, at any time during the period ending on the 91st



<PAGE>   126

        day after the date of such deposit (it being understood that this
        condition shall not be deemed satisfied until the expiration of such
        period).

               (3) Such defeasance or covenant defeasance shall not cause the
        Trustee to have a conflicting interest as defined in Section 608 and for
        purposes of the Trust Indenture Act with respect to any securities of
        the Company.

               (4) Such defeasance or covenant defeasance shall not result in a
        breach or violation of, or constitute a default under, this Indenture or
        any other agreement or instrument to which the Company is a party or by
        which it is bound.

               (5) The Company shall have delivered to the Trustee an Officers'
        Certificate and an Opinion of Counsel, each stating that all conditions
        precedent provided for relating to either the defeasance under Section
        1202 or the covenant defeasance under Section 1203 (as the case may be)
        have been complied with.

               (6) In the case of an election under Section 1202, the Company
        shall have delivered to the Trustee an Opinion of Counsel stating that
        (x) the Company has received from, or there has been published by, the
        Internal Revenue Service a ruling, or (y) since the date of this
        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
        shall confirm that, the Holders of the Outstanding Securities will not
        recognize income, gain or loss for Federal income tax purposes as a
        result of such deposit, defeasance and discharge and will 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 deposit, defeasance and
        discharge had not occurred.

               (7) In the case of an election under Section 1203, the Company
        shall have delivered to the Trustee an Opinion of Counsel to the effect
        that the Holders of the Outstanding Securities will not recognize
        income, gain or loss for Federal income tax purposes as a result of such
        deposit and covenant defeasance and will 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.

               (8) The Company shall have delivered to the Trustee an Opinion of
        Counsel to the effect that such deposit and defeasance or covenant
        defeasance shall not result in the trust arising from such deposit
        constituting an investment company as defined in the Investment Company
        Act of 



                                     -115-

<PAGE>   127

        1940, as amended, or such trust shall be qualified under such act or
        exempt from regulation thereunder.


SECTION 1205.  Deposited Money and U.S. Government Obligations to Be Held in
               Trust;

                         Other Miscellaneous Provisions.

               Subject to the provisions of the last paragraph of Section 1003,
all money and U.S. Government Obligations (including the proceeds thereof)
deposited with the Trustee (or other qualifying trustee--collectively, for
purposes of this Section 1205, the "Trustee") pursuant to Section 1204 in
respect of the Securities shall be held in trust and applied by the Trustee, in
accordance with the provisions of such Securities and this Indenture, to the
payment, either directly or through any Paying Agent (including the Company
acting as its own Paying Agent) as the Trustee may determine, to the Holders of
such Securities, of all sums due and to become due thereon in respect of
principal (and premium, if any) and interest, but such money need not be
segregated from other funds except to the extent required by law.

               The Company shall pay and indemnify the Trustee against any tax,
fee or other charge imposed on or assessed against the U.S. Government
Obligations deposited pursuant to Section 1204 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 Securities.

               Anything in this Article Twelve to the contrary notwithstanding,
the Trustee shall deliver or pay to the Company from time to time upon Company
Request any money or U.S. Government Obligations held by it as provided in
Section 1204 which, in the opinion of a nationally recognized accounting firm
expressed in a written certification thereof delivered to the Trustee, are in
excess of the amount thereof which would then be required to be deposited to
effect an equivalent defeasance or covenant defeasance.



<PAGE>   128

SECTION 1206.  Reinstatement.

               If the Trustee or the Paying Agent is unable to apply any money
in accordance with Section 1202 or 1203 by reason of any order or judgment of
any court or governmental authority enjoining, restraining or otherwise
prohibiting such application, then the Company's obligations under this
Indenture and the Securities shall be revived and reinstated as though no
deposit had occurred pursuant to this Article Twelve until such time as the
Trustee or Paying Agent is permitted to apply all such money in accordance with
Section 1202 and 1203; provided, however, that if the Company makes any payment
of principal of (and premium, if any) any Security following the reinstatement
of its obligations, the Company shall be subrogated to the rights of the Holders
of such Securities to receive such payment from the money held by the Trustee or
the Paying Agent.


SECTION 1207.  Repayment to Company.

               Any money deposited with the Trustee or any Paying Agent, or then
held by the Company, in trust for the payment of the principal of, premium, if
any, or interest on any Security and remaining unclaimed for two years after
such principal, and premium, if any, or interest has become due and payable
shall be paid to the Company on its written request or (if then held by the
Company) shall be discharged from such trust; and the Holder of such security
shall thereafter, as a creditor, look only to the Company for payment thereof,
and all liability of the Trustee or such Paying Agent with respect to such trust
money, and all liability of the Company 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 Company 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
will be repaid to the Company.



               This instrument may be executed in any number of counterparts,
each of which so executed shall be deemed to be an original, but all such
counterparts shall together constitute but one and the same instrument.



                                     -117-
<PAGE>   129

               IN WITNESS WHEREOF, the parties hereto have caused this Indenture
to be duly executed and attested, and the Trustee has caused its seal to be
hereunto affixed and attested, all as of the day and year first above written.


                                             NEXTLINK Communications, Inc.

                                             By /s/ R. BRUCE EASTER, JR.
                                               ---------------------------------
                                               Name: R. Bruce Easter, Jr.
                                               Title: Vice President, General
                                                       Counsel and Secretary



Attest:

/s/ DAVID GOESLING
------------------------------
Name:  David Goesling
Title: Assistant Treasurer


                                             UNITED STATES TRUST COMPANY
                                               OF NEW YORK


                                             By /s/ PATRICIA STERMER
                                               ---------------------------------
                                               Name:  Patricia Stermer
                                               Title: Assistant Vice President

[SEAL]

Attest:
/s/ ROBERT F. LEE
------------------------------
Name:  Robert F. Lee
Title: Assistant Secretary



<PAGE>   130

STATE OF WASHINGTON   )   ss.:
COUNTY OF KING        )

               On this 1st day of April, 1998, before me personally appeared R.
Bruce Easter, Jr., to me known, who, being duly sworn, did depose and say that
he is the Vice President of NEXTLINK Communications, Inc., one of the
corporations described in and which executed the foregoing instrument, and duly
acknowledged to me that he executed the same by authority of the Board of
Directors of said corporation.

                                              /S/  JULIA A. AVILES
                                            ------------------------------
        [Seal]                                      Notary Public
                                            Julia A. Aviles
                                            My Appointment Expires: 1-19-02



STATE OF NEW YORK  )   ss.:
COUNTY OF NEW YORK )

               On this 31st day of March, 1998, before me personally appeared
Patricia Stermer, to me known, who, being duly sworn, did depose and say that
she is the Assistant Vice President of United States Trust Company of New York,
one of the corporations described in and which executed the foregoing
instrument, and duly acknowledged to me that she executed the same by authority
of the Board of Directors of said corporation.

                                              /S/  CHRISTINE C. COLLINS    
                                            ------------------------------
                                                    Notary Public
                                            Christine C. Collins
                                            Notary Public, State of New York
                                            No. 03-4624735
                                            Qualified in Bronx County
                                            Certificate filed in New York County
                                            Commission Expires March 30, 2000
                                            


<PAGE>   131


                                                              ANNEX A -- Form of
                                                        Regulation S Certificate


                            REGULATION S CERTIFICATE

           (For transfers pursuant to Section 305(b)(i), (iii) and (v)
                                   of the Indenture)


United States Trust Company of New York,
  as Trustee
114  West 47th Street, 25th Floor
New York, New York  10036
Attention:  Corporate Trust Trustee Administration


        Re:    9.45% Senior Discount Notes due April 15, 2008
               of NEXTLINK Communications, Inc.
               (the "Securities")

               Reference is made to the Indenture, dated as of April 1, 1998
(the "Indenture"), between NEXTLINK Communications, Inc. (the "Company") and
United States Trust Company of New York, as Trustee. Terms used herein and
defined in the Indenture or in Regulation S or Rule 144 under the U.S.
Securities Act of 1933, as amended (the "Securities Act") are used herein as so
defined.

               This certificate relates to U.S. $____________ principal amount
of Securities, which are evidenced by the following certificate(s) (the
"Specified Securities"):

                    CUSIP No(s). ___________________________

                    CERTIFICATE No(s). _____________________

The person in whose name this certificate is executed below (the "Undersigned")
hereby certifies that either (i) it is the sole beneficial owner of the
Specified Securities or (ii) it is acting on behalf of all the beneficial owners
of the Specified Securities and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Securities are represented by a Global Security, they are held
through the Depositary or an Agent Member in the name of the Undersigned, as or
on behalf of the Owner. If the Specified Securities are not represented by a
Global Security, they are registered in the name of the Undersigned, as or on
behalf of the Owner.

               The Owner has requested that the Specified Securities be
transferred to a person (the "Transferee") who will take delivery in the form of
a 



                                      A-1

<PAGE>   132

Regulation S Security. In connection with such transfer, the Owner hereby
certifies that, unless such transfer is being effected pursuant to an



<PAGE>   133

effective registration statement under the Securities Act, it is being effected
in accordance with Rule 904 or Rule 144 under the Securities Act and with all
applicable securities laws of the states of the United States and other
jurisdictions. Accordingly, the Owner hereby further certifies as follows:

               (1) Rule 904 Transfers. If the transfer is being effected in
        accordance with Rule 904:

                      (A) the Owner is not a distributor of the Securities, an
               affiliate of the Company or any such distributor or a person
               acting on behalf of any of the foregoing;

                      (B) the offer of the Specified Securities was not made to
               a person in the United States;

                      (C) either:

                             (i) at the time the buy order was originated, the
                      Transferee was outside the United States or the Owner and
                      any person acting on its behalf reasonably believed that
                      the Transferee was outside the United States, or

                             (ii) the transaction is being executed in, on or
                      through the facilities of the Eurobond market, as
                      regulated by the Association of International Bond
                      Dealers, or another designated offshore securities market
                      and neither the Owner nor any person acting on its behalf
                      knows that the transaction has been prearranged with a
                      buyer in the United States;

                      (D) no directed selling efforts have been made in the
               United States by or on behalf of the Owner or any affiliate
               thereof;

                      (E) if the Owner is a dealer in securities or has received
               a selling concession, fee or other remuneration in respect of the
               Specified Securities, and the transfer is to occur during the
               Restricted Period, then the requirements of Rule 904(c)(1) have
               been satisfied; and

                      (F) the transaction is not part of a plan or scheme to
               evade the registration requirements of the Securities Act. 

               (2) Rule 144 Transfers. If the transfer is being effected
pursuant to Rule 144:



                                      A-3

<PAGE>   134

                      (A) the transfer is occurring after a holding period of at
               least one year (computed in accordance with paragraph (d) of Rule
               144) has elapsed since the Specified Securities were last
               acquired from the Company or from an affiliate of the Company,
               whichever is later, and is being effected in accordance with the
               applicable amount, manner of sale and notice requirements of Rule
               144; or

                      (B) the transfer is occurring after a holding period of at
               least two years has elapsed since the Specified Securities were
               last acquired from the Company or from an affiliate of the
               Company, whichever is later, and the Owner is not, and during the
               preceding three months has not been, an affiliate of the Company.

               This certificate and the statements contained herein are made for
your benefit and the benefit of the Company and the Purchasers.



Dated:                __________________________________________________________
                      (Print the name of the Undersigned, as such term is
                      defined in the second paragraph of this certificate.)



                      By:_______________________________________________________
                         Name:
                         Title:

                      (If the Undersigned is a corporation, partnership or
                      fiduciary, the title of the person signing on behalf of
                      the Undersigned must be stated.)



<PAGE>   135

                                                   ANNEX B -- Form of Restricted
                                                          Securities Certificate



                        RESTRICTED SECURITIES CERTIFICATE

       (For transfers pursuant to Section 305(b)(ii), (iii), (iv) and (v)
                                   of the Indenture)



United States Trust Company of New York,
  as Trustee
114 West 47th Street, 25th Floor
New York, New York 10036
Attention:  Corporate Trust Trustee Administration

        Re:    9.45% Senior Discount Notes due April 15, 2008
               of NEXTLINK Communications, Inc.
               (the "Securities")

               Reference is made to the Indenture, dated as of April 1, 1998
(the "Indenture"), between NEXTLINK Communications Inc. (the "Company") and
United States Trust Company of New York, as Trustee. Terms used herein and
defined in the Indenture or in Regulation S or Rule 144 under the U.S.
Securities Act of 1933, as amended (the "Securities Act") are used herein as so
defined.

               This certificate relates to U.S. $_____________ principal amount
of Securities, which are evidenced by the following certificate(s) (the
"Specified Securities"):

                    CUSIP No(s). ___________________________

                    CERTIFICATE No(s). _____________________

The person in whose name this certificate is executed below (the "Undersigned")
hereby certifies that either (i) it is the sole beneficial owner of the
Specified Securities or (ii) it is acting on behalf of all the beneficial owners
of the Specified Securities and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Securities are represented by a Global Security, they are held
through the Depositary or an Agent Member in the name of the Undersigned, as or
on behalf of the Owner. If the Specified Securities are not represented by a
Global Security, they are registered in the name of the Undersigned, as or on
behalf of the Owner.



                                      B-1

<PAGE>   136

               The Owner has requested that the Specified Securities be
transferred to a person (the "Transferee") who will take delivery in the form of
a Restricted Security. In 



<PAGE>   137

connection with such transfer, the Owner hereby certifies that, unless such
transfer is being effected pursuant to an effective registration statement under
the Securities Act, it is being effected in accordance with Rule 144A or Rule
144 under the Securities Act and all applicable securities laws of the states of
the United States and other jurisdictions. Accordingly, the Owner hereby further
certifies as follows:

               (1) Rule 144A Transfers. If the transfer is being effected in
        accordance with Rule 144A:

                      (A) the Specified Securities are being transferred to a
               person that the Owner and any person acting on its behalf
               reasonably believe is a "qualified institutional buyer" within
               the meaning of Rule 144A, acquiring for its own account or for
               the account of a qualified institutional buyer; and

                      (B) the Owner and any person acting on its behalf have
               taken reasonable steps to ensure that the Transferee is aware
               that the Owner may be relying on Rule 144A in connection with the
               transfer; and

               (2) Rule 144 Transfers. If the transfer is being effected
        pursuant to Rule 144:

                      (A) the transfer is occurring after a holding period of at
               least one year (computed in accordance with paragraph (d) of Rule
               144) has elapsed since the Specified Securities were last
               acquired from the Company or from an affiliate of the Company,
               whichever is later, and is being effected in accordance with the
               applicable amount, manner of sale and notice requirements of Rule
               144; or

                      (B) the transfer is occurring after a holding period of at
               least two years has elapsed since the Specified Securities were
               last acquired from the Company or from an affiliate of the
               Company, whichever is later, and the Owner is not, and during the
               preceding three months has not been, an affiliate of the Company.

               This certificate and the statements contained herein are made for
your benefit and the benefit of the Company and the Purchasers.



Dated:                __________________________________________________________
                      (Print the name of the Undersigned,



                                      B-3

<PAGE>   138

                      as such term is defined in the second paragraph of this
                      certificate.)



                      By:_______________________________________________________
                         Name:
                         Title:

                      (If the Undersigned is a corporation, partnership or
                      fiduciary, the title of the person signing on behalf of
                      the Undersigned must be stated.)



<PAGE>   139

                                                 ANNEX C -- Form of Unrestricted
                                                          Securities Certificate



                       UNRESTRICTED SECURITIES CERTIFICATE

       (For removal of Securities Act Legends pursuant to Section 305(c))



United States Trust Company of New York,
  as Trustee
114 West 47th Street, 25th Floor
New York, New York 10036
Attention:  Corporate Trust Trustee Administration

        Re:    9.45% Senior Discount Notes due April 15, 2008
               of NEXTLINK Communication, Inc.
               (the "Securities")

               Reference is made to the Indenture, dated as of April 1, 1998
(the "Indenture"), between NEXTLINK Communication, Inc. (the "Company") and
United States Trust Company of New York, as Trustee. Terms used herein and
defined in the Indenture or in Regulation S or Rule 144 under the U.S.
Securities Act of 1933, as amended (the "Securities Act") are used herein as so
defined.

               This certificate relates to U.S. $_____________ principal amount
of Securities, which are evidenced by the following certificate(s) (the
"Specified Securities"):

                    CUSIP No(s). ___________________________

                    CERTIFICATE No(s). _____________________

The person in whose name this certificate is executed below (the "Undersigned")
hereby certifies that either (i) it is the sole beneficial owner of the
Specified Securities or (ii) it is acting on behalf of all the beneficial owners
of the Specified Securities and is duly authorized by them to do so. Such
beneficial owner or owners are referred to herein collectively as the "Owner".
If the Specified Securities are represented by a Global Security, they are held
through the Depositary or an Agent Member in the name of the Undersigned, as or
on behalf of the Owner. If the Specified Securities are not represented by a
Global Security, they are registered in the name of the Undersigned, as or on
behalf of the Owner.



                                      C-1

<PAGE>   140

               The Owner has requested that the Specified Securities be
exchanged for Securities bearing no Securities Act Legend pursuant to Section
305(c) of the Indenture. In connection with such exchange, the Owner hereby
certifies



<PAGE>   141

 that the exchange is occurring after a holding period of at least two
years (computed in accordance with paragraph (d) of Rule 144) has elapsed since
the Specified Securities were last acquired from the Company or from an
affiliate of the Company, whichever is later, and the Owner is not, and during
the preceding three months has not been, an affiliate of the Company. The Owner
also acknowledges that any future transfers of the Specified Securities must
comply with all applicable securities laws of the states of the United States
and other jurisdictions.

               This certificate and the statements contained herein are made for
your benefit and the benefit of the Company and the Purchasers.



Dated:                __________________________________________________________
                      (Print the name of the Undersigned, as such term is
                      defined in the second paragraph of this certificate.)



                      By:_______________________________________________________
                         Name:
                         Title:

                      (If the Undersigned is a corporation, partnership or
                      fiduciary, the title of the person signing on behalf of
                      the Undersigned must be stated.)



                                      C-3