<PAGE>   1
                             Confidential Treatment

Note: Certain material has been omitted from this document pursuant to a request
for confidential treatment and has been filed separately with the SEC. Notations
of [REDACTED]* have been used to indicate such an omission.


                                                                   EXHIBIT 10.25



                              AMENDMENT AND CONSENT

               AMENDMENT AND CONSENT, dated as of March 30, 2001, to the CREDIT
AGREEMENT, dated as of July 2, 1998 (the "Credit Agreement"), among Teligent,
Inc., a Delaware corporation (the "Borrower"), the Lenders from time to time
parties thereto, Goldman Sachs Credit Partners L.P., as Syndication Agent,
Toronto Dominion (Texas), Inc., as Documentation Agent, and The Chase Manhattan
Bank, as Administrative Agent.

                            W I T N E S S E T H :

               WHEREAS, each of the Lenders is a party to the Credit Agreement
pursuant to which the Borrower may borrow from time to time Optional Term Loans
in an aggregate face amount of up to $400,000,000 (the "Original Optional Term
Facility Amount"); and

               WHEREAS, the Borrower wishes to increase the Original Optional
Term Facility Amount from $400,000,000 up to $600,000,000 (as so increased, the
"New Optional Term Facility Amount"); and

               WHEREAS, the Borrower wishes to utilize a portion, not in excess
of $350,000,000, of the New Optional Term Facility Amount as an optional vendor
financing facility; and

               WHEREAS, the Borrower wishes to allow certain vendors to the
Borrower to become parties to the Credit Agreement from time to time after the
Effective Date (as defined below) until December 31, 2001; and

               WHEREAS, the parties have agreed to modify certain of the
covenants and other terms in the Credit Agreement as set forth herein;


               NOW, THEREFORE, the Borrower, the Administrative Agent, and the
Required Prepayment Lenders hereby agree as follows:

               1.    Defined Terms. Capitalized terms used herein without
definition shall have the meaning ascribed to such terms in the Credit
Agreement.

               2.    Amendment to Section 1.1 - Defined Terms. (a) The following
definitions are hereby amended so that they shall read in their entirety
respectively as follows:

               "Applicable Margin": (a) for Tranche A Term Loans, Delayed Draw
               Term Loans, Conversion Term Loans and Revolving Credit Loans,
               [REDACTED] per annum, in the case of Eurodollar Loans, and
               [REDACTED], in the case of ABR Loans, and (b) for each Type of
               Optional Term Loans of each Tranche, the rate per annum for such
               Tranche and Type determined in accordance with the Optional Term
               Loan Amendment executed for such Tranche pursuant to Section 2.7.





<PAGE>   2
               "Asset Sale": (i) any Disposition of Non-Core Assets (excluding
               any such Disposition permitted by clause (a), (b), (d), (e) or
               (g) of Section 6.5) and (ii) the entering into of one or more
               management agreements with respect to spectrum by any Restricted
               Subsidiary to any Unrestricted Subsidiary or other Person;
               provided, that such agreements are (A) compliant with all
               material terms of this Agreement as determined by the
               Administrative Agent in good faith (including, without
               limitation, that all Net Cash Proceeds of such management
               agreement shall be applied in accordance with Section 2.13) and
               (B) reasonably satisfactory in form and substance to FCC counsel
               to the Lenders.

               "Consolidated Cash Interest Expense": for any fiscal quarter,
               total cash interest expense (including that attributable to
               Capital Lease Obligations) of the Borrower and its Restricted
               Subsidiaries to be paid during such fiscal quarter (including,
               without limitation, all commissions, discounts and other fees and
               charges owed with respect to letters of credit and bankers'
               acceptance financing and net costs under hedge agreements in
               respect of interest rates to the extent such net costs are
               allocable to such fiscal quarter in accordance with GAAP) as
               reasonably determined by the Borrower on the basis of (i) the
               aggregate amount of Indebtedness of the Borrower and its
               Restricted Subsidiaries outstanding on the first day of such
               fiscal quarter and (ii) interest rates applicable to such
               Indebtedness on such date.

               "Consolidated Fixed Charge Coverage Ratio": (a) from the
               Amendment Effective Date through the fiscal quarter ending
               September 30, 2003, on the last day of any fiscal quarter, the
               ratio of (i) the amount of Consolidated EBITDA required pursuant
               to Section 6.1(k) for the fiscal quarter immediately following
               such last day, to the extent that Consolidated EBITDA for such
               fiscal quarter is negative, plus the sum of (A) the amount of
               cash and Cash Equivalents held by the Borrower and its Restricted
               Subsidiaries, (B) the Available Revolving Credit Commitments, (C)
               the Available Tranche A Term Loan Commitments, (D) the Available
               Delayed Draw Term Loan Commitments, and (E) any available unused
               Optional Non-Vendor Loan Commitments, in each case, determined as
               of such last day to (ii) Consolidated Fixed Charges for the
               fiscal quarter immediately following such last day and (b) from
               the fiscal quarter ending December 31, 2003 and thereafter, for
               any period of four consecutive fiscal quarters, the ratio of (i)
               Consolidated EBITDA for such period plus the sum of (A) the
               Available Revolving Credit Commitments, (B) the Available Tranche
               A Term Loan Commitments, (C) the Available Delayed Draw Term Loan
               Commitments, and (D) any available unused Optional Non-Vendor
               Term Loan Commitments, in each case, determined as of the last
               day of such period of four consecutive fiscal quarters to (ii)
               Consolidated Fixed Charges for such period of four consecutive
               fiscal quarters.

               "Consolidated Fixed Charges": (a) from the Amendment Effective
               Date through the fiscal quarter ending September 30, 2003, for
               any fiscal quarter, the sum (without duplication) of (i)
               Consolidated Cash Interest Expense for such fiscal quarter, (ii)
               projected cash income taxes to be paid by the Borrower or any of
               its Restricted Subsidiaries on a consolidated basis in respect of
               such fiscal quarter, (iii) preferred dividends required to be
               paid in cash in such fiscal quarter and (iv)






                                       2
<PAGE>   3

               scheduled payments to be made during such fiscal quarter on
               account of principal of Indebtedness of the Borrower or any of
               its Restricted Subsidiaries and (b) from the fiscal quarter
               ending December 31, 2003 and thereafter, for any period of four
               consecutive fiscal quarters, the sum (without duplication) of (i)
               Consolidated Cash Interest Expense for such period, (ii)
               provision for cash income taxes made by the Borrower or any of
               its Restricted Subsidiaries on a consolidated basis in respect of
               such period and (iii) scheduled payments made during such period
               on account of principal of Indebtedness of the Borrower or any of
               its Restricted Subsidiaries.

               "Consolidated Secured Debt": all Consolidated Total Debt,
               excluding the Convertible Notes, secured pursuant to the Security
               Documents or by any other security interest in any assets of the
               Borrower or any of its Restricted Subsidiaries.

               "Default": any of the events specified in Section 7, whether or
               not any requirement for the giving of notice, the lapse of time,
               or both, has been satisfied.

               "Existing Affiliate Transactions": (a) transactions pursuant to
               the Administrative Services Agreement, dated as of March 5, 1996,
               between the Borrower (formerly DMT, LLC) and Microwave Services,
               Inc., a Subsidiary of Associated Group, Inc. as in effect on the
               date hereof, and as such agreement may be amended from time to
               time in a manner no less favorable to the Lenders, (b)
               transactions pursuant to the Technical Services Agreement, dated
               as of October 22, 1997, between the Company and NTT America, Inc.
               as in effect on the date hereof, and as such agreement may be
               amended from time to time in a manner no less favorable to the
               Lenders, (c) transactions pursuant to the Stockholders Agreement,
               dated as of November 26, 1997, between the Borrower, NTT America,
               Inc. and certain other stockholders of the Borrower as in effect
               on the date hereof and as such agreement may be amended from time
               to time in a manner no less favorable to the Lenders, (d)
               transactions pursuant to the Shareholders Agreement, dated
               January 13, 2000, by and among Alex J. Mandl, Liberty Media
               Corporation, Telcom-DTS Investors, L.L.C. and Microwave Services,
               Inc. as in effect on the date hereof and as such agreement may be
               amended from time to time in a manner no less favorable to the
               Lenders, (e) transactions pursuant to the Joint Venture
               Agreement, dated April 11, 2000, by and between Teligent
               International Ltd., Telcom Ventures LLC, BA Investments, Ltd.,
               and Argentina Telecom Holdings, Ltd. as in effect on the date
               hereof and as such agreement may be amended from time to time in
               a manner no less favorable to the Lenders, and (f) transactions
               pursuant to arrangements in effect on the Closing Date in an
               aggregate amount not to exceed $5,000,000.

               "Facility": each of (a) the Tranche A Term Loan Commitments and
               the Tranche A Term Loans made thereunder (the "Tranche A Term
               Loan Facility"), (b) the Delayed Draw Term Loan Commitments and
               the Delayed Draw Term Loans made thereunder (the "Delayed Draw
               Term Loan Facility"), (c) the Conversion Term Loans (the
               "Conversion Term Loan Facility"), (d) the Optional Non-Vendor
               Loan Commitments, if any, and the Optional Non-Vendor Loans made
               thereunder (the "Optional Non-Vendor Loan Facility"), (e) the
               Optional Vendor Commitments, if any, and the Optional Vendor
               Loans made thereunder (the






                                       3
<PAGE>   4

               "Optional Vendor Loan Facility") and (f) the Revolving Credit
               Commitments and the Revolving Credit Loans made thereunder
               (the "Revolving Credit Facility").

               "Majority Facility Lenders": at any time, with respect to any
               Facility, the holders of more than 50% of the aggregate unpaid
               principal amount of the Loans outstanding under such Facility
               plus the aggregate amount of undrawn Commitments then in effect
               under such Facility.

               "Optional Term Loan": any Optional Non-Vendor Loan and any
               Optional Vendor Loan.

               "Optional Term Loan Commitment": any Optional Non-Vendor Loan
               Commitment and any Optional Vendor Commitment.

               "Optional Term Loan Lender": any Optional Non-Vendor Loan Lender
               and any Optional Vendor Loan Lender.

               "Optional Term Loan Tranche": any Optional Non-Vendor Loan
               Tranche and any Optional Vendor Loan Tranche.

               "Required Lenders": at any time, the holders of more than 50% of
               the aggregate unpaid principal amount of the Loans then
               outstanding plus the aggregate amount of undrawn Commitments
               (other than Optional Vendor Commitments) then in effect.

               (b) Section 1.1 is hereby further amended by adding thereto the
following new definitions in proper alphabetical order:

               "Amendment Effective Date": the "Effective Date" as defined in
               the Amendment, dated as of March 30, 2001, to this Agreement.

               "Collateral and Securities Account":  as defined in Section 6.13.

               "Convertible Notes": notes issued by the Borrower to such Person
               or Persons as determined by the Borrower, substantially in the
               form and having the terms set forth in Exhibit A to the
               Amendment, dated as of March 30, 2001, to this Agreement; such
               terms shall in any event include subordination of such notes, in
               right of payment, to the Obligations, and subordination of any
               security interest securing such notes to the security interest of
               the Collateral Agent, in each case pursuant to subordination and
               intercreditor provisions reasonably acceptable to the
               Administrative Agent.

               "New Lender Supplement": the agreement made pursuant to Section
               2.7 substantially in the form of Exhibit J.

               "Non-Core Assets": at any time of determination (i) all
               international licenses held by the Borrower or any of its
               Subsidiaries in markets where full-scale commercial service has
               not been launched at such time and (ii) all international joint
               ventures and international Subsidiaries, which, in the case of
               clauses (i) and (ii) above, are not material to the business,
               property or condition (financial or otherwise) of the Borrower
               and its Subsidiaries taken as a whole.







                                       4
<PAGE>   5

               "Operating Accounts": as defined in Section 6.13.

               "Optional Non-Vendor Loan Commitment": as to any Lender, the
               obligation of such Lender, if any, to make an Optional Non-Vendor
               Loan to the Borrower hereunder in a principal amount not to
               exceed the amount set forth in the Optional Term Loan Amendment
               related thereto.

               "Optional Non-Vendor Loan":  as defined in Section 2.7.

               "Optional Non-Vendor Loan Lender": each Lender which has an
               Optional Non-Vendor Commitment or which is the holder of an
               Optional Non-Vendor Loan.

               "Optional Non-Vendor Loan Tranche":  as defined in Section 2.7.

               "Optional Vendor Commitment": as to any Optional Vendor Loan
               Lender, the obligation of such Optional Vendor Loan Lender, if
               any, to make an Optional Vendor Loan to the Borrower hereunder in
               a principal amount not to exceed the amount set forth in the
               Optional Term Loan Amendment related thereto.

               "Optional Vendor Loan":  as defined in Section 2.7.

               "Optional Vendor Loan Lender": each Lender which has an Optional
               Vendor Commitment or which is the holder of an Optional Vendor
               Loan.

               "Optional Vendor Loan Tranche":  as defined in Section 2.7.

               "Vendor": a vendor of plant, property, services or equipment
               and/or similar or related Property to the Borrower or its
               Subsidiaries, the sale or other provision of which is financed,
               in whole or in part, pursuant to Optional Vendor Loans.

               (c) Section 1.1 is hereby further amended by deleting the
definition of "Unused Proceeds Basket".

               3.    Amendment to Section 2.7. Section 2.7 is hereby amended so
that it shall read in its entirety as follows:

               (a) Optional Non-Vendor Loans. Subject to the terms and
               conditions hereof, the Borrower may, with the consent of the
               Required Lenders, at any time and from time to time prior to
               December 31, 2001, establish one or more additional non-vendor
               term loan tranches (each, an "Optional Non-Vendor Loan Tranche")
               pursuant to which non-vendor term loans ("Optional Non-Vendor
               Loans") may be made, provided, (i) each Optional Non-Vendor Loan
               Tranche shall be in a principal amount of at least $50,000,000
               and (ii) all Optional Non-Vendor Loan Tranches shall not exceed
               in the aggregate the difference of (A) $600,000,000 less (B) the
               aggregate amount of Optional Vendor Loan Tranches then in effect.
               The Borrower may offer to any existing Lender, or to one or more
               additional banks, financial institutions or other entities
               reasonably acceptable to the Administrative Agent, the
               opportunity to participate in all or a portion of an Optional
               Non-Vendor Loan Tranche.

               (b) Optional Vendor Loans. Subject to the terms and conditions
               hereof, the






                                       5
<PAGE>   6


               Borrower may at any time and from time to time prior to December
               31, 2001, establish one or more vendor loan tranches (each, an
               "Optional Vendor Loan Tranche") pursuant to which vendor loans
               ("Optional Vendor Loans") may be made by one or more Vendors,
               provided, (i) each Optional Vendor Loan Tranche shall be in a
               principal amount of at least $50,000,000 and (ii) all Optional
               Vendor Loan Tranches shall not exceed $350,000,000 in the
               aggregate or, if less, the difference of (A) $600,000,000 less
               (B) the aggregate amount of Optional Non-Vendor Loan Tranches
               then in effect. The Borrower may offer to any existing Optional
               Vendor Loan Lender, or to one or more additional Vendors
               reasonably acceptable to the Administrative Agent, the
               opportunity to participate in all or a portion of an Optional
               Vendor Loan Tranche. Proceeds of Optional Vendor Loans may be
               used only to finance Capital Expenditures and services related to
               Capital Expenditures.

               (c) Optional Term Loan Procedures. The Borrower shall request the
               establishment of an Optional Term Loan Tranche by delivery to the
               Administrative Agent of a written request therefor (an "Optional
               Term Loan Request") which shall be promptly distributed by the
               Administrative Agent to the applicable Lenders. Each Optional
               Term Loan Request shall (i) set forth the aggregate principal
               amount of the requested Optional Term Loan Tranche and the
               Applicable Margin (or, if applicable, the formula for the
               calculation thereof) and the commitment fee rate, if any,
               applicable to the Optional Term Loans to be made under such
               Optional Term Loan Tranche, the amortization and maturity date of
               such Optional Term Loans and the borrowing procedures relating to
               the borrowing by the Borrower of such Optional Term Loans and
               (ii) if applicable, be accompanied by such information as the
               Administrative Agent shall reasonably request for use in
               syndication of the requested Optional Term Loans. All Optional
               Term Loans shall (I) have a Weighted Average Life (calculated on
               the date the related Optional Term Loan Tranche shall become
               effective) that is at least as long as the then Weighted Average
               Life (calculated on such date) of the Revolving Credit
               Commitments and the Term Loans, taken as a whole, (II) have a
               final scheduled maturity date on or after December 31, 2006,
               (III) bear interest at rates no higher than those applicable to
               the Tranche A Term Loans, (IV) otherwise be subject to the same
               terms and conditions as the other Term Loans outstanding
               hereunder, (V) be subject to no other conditions other than, in
               the case of Optional Vendor Loans, the requirement that the
               proceeds be used to purchase equipment and/or services from or
               through the applicable Vendors and (VI) be in form and substance
               otherwise reasonably satisfactory to the Administrative Agent. No
               Lender shall have any obligation to participate in any Optional
               Term Loan Tranche unless it agrees to do so in its sole
               discretion. All Optional Term Loan Tranches shall not exceed
               $600,000,000 in the aggregate.

               (d) New Lenders. In the case of any Optional Non-Vendor Loan
               Tranche, any banks, financial institutions or other entities,
               and, in the case of any Optional Vendor Loan Tranche, any Vendor,
               which elects to become a party to this Agreement and obtain an
               Optional Term Loan Commitment pursuant to this Section 2.7 shall
               execute a New Lender Supplement (each, a "New Lender Supplement")
               with the Borrower and the Administrative Agent, substantially in
               the form of Exhibit J, whereupon such lender (herein called a
               "New Lender")






                                       6
<PAGE>   7

               shall become an Optional Term Loan Lender for all purposes and to
               the same extent as if originally a party hereto and shall be
               bound by and entitled to the benefits of this Agreement and the
               other Loan Documents, and Schedule 1.1 shall be deemed to be
               amended to add the name and Optional Non-Vendor Loan Commitment
               or Optional Vendor Commitment, as applicable, of such New Lender.

               (e) Conditions to Effectiveness. The effectiveness of any
               Optional Term Loan Tranche shall be contingent upon (i) execution
               and delivery by the Administrative Agent, the Borrower and each
               Lender providing Optional Term Loan Commitments under such
               Optional Term Loan Tranche of an Optional Term Loan Amendment
               relating to such Optional Term Loan Tranche, (ii) receipt by the
               Administrative Agent of such corporate resolutions and officer's
               certificates of the Borrower and legal opinions of counsel to the
               Borrower as the Administrative Agent shall reasonably request
               with respect thereto, and (iii), if applicable, execution and
               delivery by the Borrower, the Administrative Agent and each New
               Lender providing Optional Term Loan Commitments under such
               Optional Term Loan Tranche of the New Lender Supplement, in each
               case in form and substance reasonably satisfactory to the
               Administrative Agent. The Borrower and the Administrative Agent
               agree to negotiate in good faith any Optional Term Loan Amendment
               relating to any Optional Term Loan Tranche.

               4.    Amendment to Section 2.12. Section 2.12 is hereby amended
so that it shall read in its entirety as follows:

               Optional Prepayments. The Borrower may at any time and from time
               to time prepay the Term Loans and reduce the Revolving Credit
               Commitments, in whole or in part, without premium or penalty
               except as provided in the last sentence of this Section, upon
               irrevocable notice delivered to the Administrative Agent at least
               three Business Days prior thereto in the case of Eurodollar Loans
               and at least one Business Day prior thereto in the case of ABR
               Loans, which notice shall specify the date and amount of
               prepayment and whether the prepayment is of Eurodollar Loans or
               ABR Loans; provided, that if a Eurodollar Loan is prepaid on any
               day other than the last day of the Interest Period applicable
               thereto, the Borrower shall also pay any amounts owing pursuant
               to Section 2.22; provided, further, that any prepayment made
               pursuant to this Section 2.12 shall be applied pro rata to (i)
               the Tranche A Term Loans, (ii) the Conversion Term Loans, (iii)
               the Optional Term Loans, (iv) the reduction of the Delayed Draw
               Term Loans and (v) the reduction of the Revolving Credit
               Commitments. Upon receipt of any such notice the Administrative
               Agent shall promptly notify each relevant Lender thereof. If any
               such notice is given, the amount specified in such notice shall
               be due and payable on the date specified therein, together with
               accrued interest to such date on the amount prepaid. Any
               reduction of the Revolving Credit Commitments pursuant to this
               Section 2.12 shall be accompanied by prepayment of the Revolving
               Credit Loans to the extent, if any, that the aggregate
               outstanding principal amount of Revolving Credit Loans exceeds
               the amount of the Total Revolving Credit Commitments as so
               reduced. Partial prepayments of Term Loans and Revolving Credit
               Commitments shall be in an aggregate principal amount of
               $1,000,000 or a whole multiple thereof. Optional prepayments of
               the






                                       7
<PAGE>   8

               Term Loans occurring prior to the first anniversary of the
               Closing Date shall be accompanied by a prepayment fee equal to 3%
               of the amount of such prepayment.

               5.    Amendment to Section 2.13. (a) Section 2.13(b) is hereby
amended so that it shall read in its entirety as follows:

               (b) Unless the Required Prepayment Lenders shall otherwise agree,
               if on any date the Borrower or any of its Subsidiaries shall
               receive Net Cash Proceeds from any Asset Sale or Recovery Event
               by the Borrower or its Subsidiaries then, unless a Reinvestment
               Notice shall be delivered in respect thereof within five Business
               Days after receipt of such Net Cash Proceeds, such Net Cash
               Proceeds shall be applied on such date toward the prepayment of
               the Term Loans and the reduction of the Revolving Credit
               Commitments as set forth in Section 2.13(d); provided, that, on
               each Reinvestment Prepayment Date, an amount equal to the
               Reinvestment Prepayment Amount with respect to the relevant
               Reinvestment Event shall be applied toward the prepayment of the
               Term Loans and the reduction of the Revolving Credit Commitments
               as set forth in Section 2.13(d); and provided, further, that (i)
               the Borrower may not at any time deliver a Reinvestment Notice
               with respect to more than 35% of the Net Cash Proceeds of any
               Asset Sale and (ii) any Net Cash Proceeds of Asset Sales in
               respect of which Reinvestment Notices have been delivered shall
               be reinvested in tangible Property, including the installation
               thereof and services reasonably related to such installation,
               located in the United States of America useful in the business of
               the Borrower consistent with its past practice and with normal
               industry practice in accordance with this Section 2.13. If at any
               time the aggregate amount of Net Cash Proceeds of Asset Sales in
               respect of which Reinvestment Notices have been delivered shall
               exceed 35% of the aggregate amount of Net Cash Proceeds
               theretofore received from Asset Sales, then the Borrower promptly
               shall apply such excess over 35% in accordance with Section
               2.13(d). In addition, if at any time the aggregate amount of Net
               Cash Proceeds in respect of which Reinvestment Notices have been
               delivered and which have not been reinvested in accordance with
               such Reinvestment Notices or applied in accordance with Section
               2.13(d) shall exceed $5,000,000, then the Borrower promptly shall
               deliver such excess over $5,000,000 to the Collateral Agent to be
               held by it in accordance with the Collateral Agency and
               Intercreditor Agreement.

               (b) Section 2.13(d) is hereby amended so that it shall read in
its entirety as follows:

               (d) Amounts to be applied in connection with prepayments and
               Commitment reductions made pursuant to Section 2.13(a), (b) or
               (c) or Section 6.6 shall be applied to the prepayment of the Term
               Loans, the reduction of the Revolving Credit Commitments and the
               reduction of any Delayed Draw Term Loan Commitments then unused
               and in effect, pro rata according to the respective amounts of
               the outstanding Term Loans, outstanding Revolving Credit
               Commitments and unused Delayed Draw Term Loan Commitments then in
               effect. Any such reduction of the Revolving Credit Commitments
               shall be accompanied by prepayment of the Revolving Credit Loans
               to the extent, if any, that the aggregate outstanding principal
               amount of Revolving Credit Loans exceeds the







                                       8
<PAGE>   9

               amount of the Total Revolving Credit Commitments as so reduced.
               The application of any prepayment pursuant to this Section shall
               be made first to ABR Loans and second to Eurodollar Loans. Each
               prepayment of the Loans under this Section (except in the case of
               Revolving Credit Loans that are ABR Loans) shall be accompanied
               by accrued interest to the date of such prepayment on the amount
               prepaid. No prepayment fee shall be payable in connection with
               any prepayment or Commitment reduction required by paragraphs (a)
               through (c) above.

               (c) Section 2.13(e) is hereby amended so that it shall read in
its entirety as follows:

               (e) [Reserved.]

               6.    Amendment to Lead-In to Section 5. The lead-in to Section
5 is hereby amended so that it shall read in its entirety as follows:

               The Borrower hereby agrees that, so long as any Commitment
               remains in effect or any Loan or other amount is owing to any
               Lender or any Agent hereunder, the Borrower shall and, except in
               the case of delivery of financial statements and information,
               reports and notices and except in the case of agreements pursuant
               to Section 5.12 and 5.13 hereof, shall cause each of its
               Restricted Subsidiaries to:

               7.    Waiver to Section 5.1(a). The requirement of Section
5.1(a)  of the Credit Agreement that the independent certified public
accountants' report which accompanies the audited financial statements shall
not contain a "`going concern' or like qualification or exception" shall be
waived for the fiscal year ended December 31, 2000 insofar as such "going
concern" qualification results from the Borrower having incurred recurring
operating losses and having a substantial need for working capital.

               8.    Amendment to Section 5.2(d). Section 5.2(d) is hereby
amended so that it shall read in its entirety as follows:

               (d)   concurrently with the delivery of any financial statements
               pursuant to Section 5.1, a narrative discussion and analysis of
               the financial condition and results of operations of the Borrower
               and its Subsidiaries for such fiscal quarter and for the period
               from the beginning of the then current fiscal year to the end of
               such fiscal quarter, as compared to the portion of the
               Projections covering such periods and to the comparable periods
               of the previous year;

               9.    Amendment to Section 5.10. (a) Section 5.10(a) is hereby
amended so that it shall read in its entirety as follows:

               (a) Promptly (i) transfer to LicenseCo any FCC License held by
               the Borrower or any Restricted Subsidiary and take any other
               actions as shall be required to cause the Collateral Agent to
               have a perfected first priority security interest therein (to the
               extent permissible under applicable law), (ii) create on terms
               reasonably acceptable to the Administrative Agent a perfected
               first priority security interest in favor of the Collateral Agent
               in all Personal Property Assets now owned or hereafter acquired
               by the Borrower or any Restricted Subsidiary (including any
               Personal Property Assets owned or hereafter acquired by AssetCo)
               and any





                                       9
<PAGE>   10

               Personal Property Assets of any Person that becomes a Restricted
               Subsidiary or is merged with or into or consolidated with the
               Borrower or any Restricted Subsidiary (in each case other than
               any such Personal Property Assets constituting Excluded Assets)
               and (iii) without limiting the requirements of Section 5.10(c),
               at the option of the Borrower, either (x) transfer to LeasingCo
               any Real Property Assets hereafter acquired by the Borrower or
               any Restricted Subsidiary and any Real Property Assets of any
               Person that becomes a Restricted Subsidiary or is merged with or
               into or consolidated with the Borrower or any Restricted
               Subsidiary (in each case other than any such Real Property Assets
               constituting Excluded Assets) or (y) create on terms reasonably
               acceptable to the Administrative Agent a perfected first priority
               security interest in favor of the Collateral Agent in such Real
               Property Assets, other than Excluded Assets (which security
               interest may be subject to any Liens permitted by Section 6.3
               (other than those referred to in the definition of the term
               "Excluded Assets)) .

               (b) Section 5.10(c) is hereby amended so that it shall read in
its entirety as follows:

               (c) Promptly create a mortgage on terms reasonably acceptable to
               the Administrative Agent in favor of the Collateral Agent on any
               fee simple title in real property owned by the Borrower or any
               Restricted Subsidiary having at the time of acquisition thereof a
               purchase price or fair market value greater than $1,000,000
               (other than Excluded Assets), including any such properties that
               are acquired by the Borrower or any Restricted Subsidiary after
               the date hereof and any such properties of any Person that
               becomes a Restricted Subsidiary or is merged with or into or
               consolidated with the Borrower or any Restricted Subsidiary.

               (b) Section 5.10(d) is hereby amended so that it shall read in
its entirety as follows:

               (d) Promptly cause (i) all Capital Stock of any Subsidiary
               (including, without limitation, any Subsidiary which shall be
               acquired by the Borrower or any Restricted Subsidiary) held by
               the Borrower or its Restricted Subsidiaries to be pledged to the
               Collateral Agent as Collateral; provided, that only 65% of the
               Capital Stock of any Excluded Foreign Subsidiary which is a
               Subsidiary of the Borrower or any Domestic Subsidiary, and none
               of the Capital Stock of any Subsidiary of an Excluded Foreign
               Subsidiary, shall be required to be pledged and (ii) each
               Restricted Subsidiary to become a party to the Guarantee and
               Collateral Agreement.

               10.    Amendment to Section 5. Section 5 is hereby amended to
add, after Section 5.11, the following new Sections 5.12 and 5.13 as follows:

               5.12 Convertible Notes. Deliver to the Administrative Agent, on
               or before April 30, 2001, definitive documentation, duly
               authorized, executed and delivered by the Borrower and such
               Person or Persons as determined by the Borrower with respect to
               the Convertible Notes, on terms and conditions reasonably
               satisfactory to the Administrative Agent and in an aggregate
               principal amount equal to or in excess of $100,000,000.






                                       10
<PAGE>   11

               5.13 Vendor Financing. Deliver to the Administrative Agent, on or
               before April 30, 2001, definitive documentation, duly authorized,
               executed and delivered by the Borrower and one or more Vendors,
               including a New Lender Supplement duly executed and delivered by
               the Borrower and each relevant Vendor, with respect to the
               establishment of one or more Optional Vendor Loan Tranches
               pursuant to Section 2.7 of, and in all material respects in
               accordance with, this Agreement in an aggregate principal amount
               equal to or in excess of $250,000,000.

               11.    Amendment to Section 6.1. (a) Section 6.1(a) is hereby
amended so that it shall read in its entirety as follows:

               (a) Consolidated Total Debt to Consolidated Adjusted
               Capitalization. Permit the ratio of Consolidated Total Debt to
               Consolidated Adjusted Capitalization during any test period set
               forth below to be greater than the ratio set forth below opposite
               such test period:

               Test Period                                Ratio
               -----------                                -----

               Closing Date - 12/31/98                    60%
               1/1/99 - thereafter                        65%

               (b) Section 6.1(b) is hereby amended so that it shall read in its
entirety as follows:

               (b) Consolidated Secured Debt to Consolidated Adjusted
               Capitalization. Permit the ratio of Consolidated Secured Debt to
               Consolidated Adjusted Capitalization during any test period set
               forth below to be greater than the ratio set forth below opposite
               such test period:

               Test Period                                Ratio
               -----------                                -----

               Closing Date - 12/31/98                    30%
               1/1/99 -  thereafter                       40%

               (c) Section 6.1(c) is hereby amended so that it shall read in its
entirety as follows:

               (c) Minimum Consolidated Total Revenue. Permit Consolidated Total
               Revenue for any fiscal quarter set forth below to be less than
               the amount set forth opposite such fiscal quarter below:

               Fiscal Quarter Ending                          Amount
               ---------------------                          ------

                3/31/01                                   [REDACTED]*
                6/30/01                                   [REDACTED]*

               (d) Section 6.1(f) is hereby amended to delete the last sentence
thereof, which read, "In addition to the amounts set forth above, Capital
Expenditures may be funded from the Unused Proceeds Basket".

               (e) Section 6.1(j) is hereby amended so that it shall read in its
entirety as follows:







                                       11
<PAGE>   12

               (j) Consolidated Fixed Charge Coverage Ratio. (a)(i) From the
               fiscal quarter ending June 30, 2001 through the fiscal quarter
               ending September 30, 2003, permit the Consolidated Fixed Charge
               Coverage Ratio on the last day of any fiscal quarter ending on
               any date set forth below to be less than the ratio set forth
               opposite such date below:

                      Fiscal Quarter Ending               Ratio
                      ---------------------               -----

                      6/30/01                             2.00

                      9/30/01                             1.75

                      12/31/01                            2.50

                      3/31/02 through 9/30/03             1.25; and

               (ii) From the fiscal quarter ending December 31, 2003 and
               thereafter, permit the Consolidated Fixed Charge Coverage Ratio
               for any period of four consecutive fiscal quarters ending during
               any test period set forth below to be less than the ratio set
               forth opposite such test period below:

                      12/31/03 through 9/30/04            1.10

                      12/31/04 and thereafter             1.25; or

               (b) From the fiscal quarter ending June 30, 2001 through the
               fiscal quarter ending September 30, 2003, fail to deliver to the
               Administrative Agent and the Lenders, on or before the date which
               is ten Business Days after the end of any fiscal quarter, a
               certificate of a Responsible Officer showing calculations
               demonstrating compliance with the foregoing clause (i) on the
               last day of such fiscal quarter.

               (f) Section 6.1 is hereby amended to add the following new
Section 6.1(k) below:

               (k) Minimum Consolidated EBITDA. Permit Consolidated EBITDA for
               the period ending on the last day of the fiscal quarter set forth
               below to be less than the amount set forth opposite such fiscal
               quarter below:

               Fiscal Quarter Ending                        Amount
               ---------------------                        ------

                     3/31/01                              [REDACTED]*
                     6/30/01                              [REDACTED]*
                     9/30/01                              [REDACTED]*
                     12/31/01                             [REDACTED]*
                     3/31/02                              [REDACTED]*
                     6/30/02                              [REDACTED]*
                     9/30/02                              [REDACTED]*
                     12/31/02                             [REDACTED]*
                     3/31/03                              [REDACTED]*
                     6/30/03                              [REDACTED]*
                     9/30/03                              [REDACTED]*
                     12/31/03                             [REDACTED]*







                                       12
<PAGE>   13

                    3/31/04                               [REDACTED]*
                    6/30/04                               [REDACTED]*
                    9/30/04                               [REDACTED]*
                    12/31/04                              [REDACTED]*

               (g) Section 6.1 is hereby amended to add the following new
Section 6.1(l) below:

               (l) Minimum Liquidity. Permit the aggregate amount of cash and
               Cash Equivalents held in (i) the Operating Accounts of the
               Borrower and (ii) the Collateral and Securities Account of the
               Borrower held at The Chase Manhattan Bank, in each case pursuant
               to Section 6.13 of this Agreement, to be less than $150,000,000
               on March 31, 2001.

               12.    Waiver of Section 6.1(j). The parties hereto hereby agree
that the requirement of Section 6.1(j) that the Consolidated Fixed Charge
Coverage Ratio on the last day of the fiscal quarter ending December 31, 2000 be
equal to or more than 1.10 shall be waived.

               13.    Amendment to Section 6.2. (a) Section 6.2(c) is hereby
amended so that it shall read in its entirety as follows:

               (c) Indebtedness (including, without limitation, Capital Lease
               Obligations) secured by Liens permitted by Section 6.3(g);
               provided, that (i) not more than $25,000,000 of such Indebtedness
               may be incurred to finance the acquisition of Network Assets
               (other than fiber or fiber capacity) and (ii) that not more than
               $[REDACTED]* of such Indebtedness may be incurred to finance the
               acquisition of fiber or fiber capacity;

               (b) Section 6.2 is hereby further amended by (i) deleting the
word "and" at the end of clause (j), (ii) deleting the period at the end of
clause (k) and inserting a semi-colon and the word "and" in lieu thereof and
(iii) adding the following new clause (l):

               (l) Indebtedness incurred under the Convertible Notes in an
               aggregate principal amount not to exceed [REDACTED]*.

               14.    Consent to Section 6.2(g). The parties hereto hereby
agree that the requirement of Section 6.2(g)(x) that unsecured Indebtedness or
preferred stock of the Borrower issued or incurred after July 2, 1998 generating
the first $500,000,000 in Net Cash Proceeds shall provide for interest or
dividends thereon to be paid in kind (or to be paid out of amounts deposited in
escrow or pledged as collateral from the proceeds thereof) for at least three
years after the date of incurrence or issuance thereof shall be deemed
satisfied.

               15.    Amendment to Section 6.3. (a) Section 6.3(g) is hereby
amended to read in its entirety as follows:

               (g) Liens securing Indebtedness of the Borrower or any Restricted
               Subsidiary incurred pursuant to Section 6.2(c) to finance the
               acquisition or capital lease of fixed or capital assets, provided
               that (i) such Liens shall be created within 90 days from the
               acquisition of such fixed or capital assets and (ii) such Liens
               do not at any time encumber any Property other than the Property
               financed by such Indebtedness;






                                       13
<PAGE>   14
               (b) Section 6.3 is hereby further amended by (i) deleting the
word "and" at the end of clause (k), (ii) deleting the period at the end of
clause (l) and inserting a semi-colon in lieu thereof and (iii) adding the
following new clauses (m), (n) and (o):

               (m) Uniform Commercial Code filings with respect to operating
               leases or consignment arrangements entered into in the ordinary
               course of business of the Borrower or any of its Restricted
               Subsidiaries, to the extent filed to reflect the interests of the
               lessor or relevant party in respect of such leases or consignment
               arrangements, as the case may be;

               (n) Liens in favor of banking institutions arising by operation
               of law encumbering deposits held by such banking institution
               incurred by the Borrower or its Restricted Subsidiaries in the
               ordinary course of business; and

               (o) second priority Liens on the Collateral securing the
               obligations under the Convertible Notes permitted pursuant to
               Section 6.2(l), provided, that (i) such Liens shall be subject to
               customary second lien and Indebtedness subordination provisions
               satisfactory to the Administrative Agent providing, among other
               things, that such Liens shall be subject to the priority of Liens
               securing the Obligations (including with respect to the exercise
               of remedies and decisions relating to the Collateral) and that
               the obligations under the Convertible Notes shall be subordinated
               to the Obligations and (ii) the documentation with respect to
               such Liens shall include an intercreditor agreement and such
               other documentation reasonably requested by the Administrative
               Agent, satisfactory in form and substance to the Administrative
               Agent.

               16.    Amendment to Section 6.5. (a) Sections 6.5(c) is hereby
amended so as to read in its entirety as follows:

               (c) so long as after giving effect thereto the Borrower is in Pro
               Forma Compliance, any Asset Sale for fair market value; provided,
               that (i) the aggregate consideration in connection with all Asset
               Sales shall not exceed [REDACTED]* and (ii) the Net Cash Proceeds
               of all Asset Sales shall be applied in accordance with Section
               2.13;

               (b) The proviso at the end of Sections 6.5 is hereby amended so
as to read in its entirety as follows:

               provided that in each case described in clauses (c) and (e)
               above, at least 75% of the consideration received by the
               Borrower or its Restricted Subsidiaries for such Disposition
               shall consist of cash and Cash Equivalents.

               17.    Amendment to Section 6.7. (a) Sections 6.7(d), (e) and (f)
are hereby amended so as to read in their entirety as follows:

               (d) Investments by the Borrower and its Restricted Subsidiaries
               (other than the Special Purpose Subsidiaries) in Unrestricted
               Subsidiaries and joint ventures, provided, that (x) the
               consideration for such Investments made after the Effective Date
               in excess of [REDACTED]* in the aggregate shall be the common
               stock of the Borrower, (y) the consideration for such Investments
               made after the Effective






                                       14
<PAGE>   15

               Date may not include, directly or indirectly, the Disposition of
               any Network Assets of the Borrower or any Restricted Subsidiary
               (including, without limitation, licenses, whether domestic or
               foreign, but excluding, the entering into of one or more
               management agreements with respect to spectrum by any Restricted
               Subsidiary to any Unrestricted Subsidiary or other Person;
               provided, that such agreements are (A) compliant with all
               material terms of this Agreement as determined by the
               Administrative Agent in good faith (including, without
               limitation, that all Net Cash Proceeds of such management
               agreement shall be applied in accordance with Section 2.13) and
               (B) reasonably satisfactory in form and substance to FCC counsel
               to the Lenders), and (z) after giving effect to such Investment
               the Borrower shall be in Pro Forma Compliance;

               (e) Investments in wireless telecommunications licenses issued by
               a governmental authority, including FCC Licenses, and in Persons
               engaged in the telecommunications business and substantially all
               of whose assets consist of wireless telecommunications licenses
               which become Restricted Subsidiaries as a result of such
               Investment, provided, that (w) the consideration for such
               Investments shall be the common stock of the Borrower, (x) with
               respect to Investments in Persons pursuant to this clause (e),
               such Investments shall be made only in Persons which have
               provided to the Administrative Agent financial statements
               certified by the chief financial officer of such Person
               reflecting a positive EBITDA for such Person for the immediately
               preceding consecutive twelve-month period, (y) after giving
               effect to such Investment the Borrower shall be in Pro Forma
               Compliance and (z) the consideration for Investments made in
               telecommunications licenses issued by any Governmental Authority
               outside the United States shall be the common stock of the
               Borrower;

               (f) Investments in additional Telecommunications Assets,
               excluding wireless telecommunications licenses, and in Persons
               engaged in the telecommunications business which become
               Restricted Subsidiaries as a result of such Investment, provided,
               that (x) the consideration for such Investments shall be the
               common stock of the Borrower, (y) with respect to Investments in
               Persons pursuant to this clause (f), such Investments shall be
               made only in Persons which have provided to the Administrative
               Agent financial statements certified by the chief financial
               officer of such Person reflecting a positive EBITDA for such
               Person for the immediately preceding consecutive twelve-month
               period, and (z) after giving effect to each such Investment the
               Borrower shall be in Pro Forma Compliance;

               18.    Amendment to Section 6.12(b). Sections 6.12(b) is hereby
amended so as to read in its entirety as follows:

               (b) Permit LicenseCo to incur any material liabilities (other
               than pursuant to the Loan Documents) or to engage in any business
               or activities other than (i) the holding of Licenses, (ii) the
               entering into of one or more management agreements with respect
               to spectrum with any Unrestricted Subsidiary or other Person
               (provided, that such agreements are (A) compliant with all
               material terms of this Agreement as determined by the
               Administrative Agent in good faith (including, without
               limitation, that all Net Cash Proceeds of such management
               agreement shall be applied in accordance with Section 2.13) and
               (B) reasonably satisfactory







                                       15
<PAGE>   16

               in form and substance to FCC counsel to the Lenders) and (iii) in
               each case, to engage in activities directly incident or directly
               related thereto.

               19.   Addition of Section 6.13. The following shall be added as
Section 6.13:

               6.13. Maintenance of Cash and Cash Equivalents. From and after
               the Amendment Effective Date, hold, directly or indirectly, any
               cash or Cash Equivalents, except as follows:

                     (a) the Borrower and its Restricted Subsidiaries may hold
               cash in operating accounts maintained with any bank or other
               financial institution reasonably satisfactory to the
               Administrative Agent (the "Operating Accounts") so long as, at
               the close of business on any day (after giving effect to any
               transfers at such close of business to the Collateral and
               Securities Account), the amount on deposit in all Operating
               Accounts shall not exceed, in the aggregate, [REDACTED]*; and

                     (b) the Borrower and its Restricted Subsidiaries shall
               maintain all cash and Cash Equivalents, other than cash on
               deposit in an Operating Account to the extent permitted by the
               foregoing paragraph (a), in an account or accounts (collectively,
               the "Collateral and Securities Account") at The Chase Manhattan
               Bank, which shall be established and maintained upon the
               following terms:

                             (i) the Collateral and Securities Account shall be
                     established pursuant to agreements in form and substance
                     reasonably satisfactory to the Administrative Agent, which
                     shall in any event provide that (1) the Collateral and
                     Securities Account, and all cash and Cash Equivalents from
                     time to time credited thereto, and all earnings thereon,
                     shall constitute Collateral in which the Collateral Agent
                     has a security interest to secure the Secured Obligations
                     (as defined in the Collateral Agency and Intercreditor
                     Agreement) and (2) the Collateral Agent shall have sole
                     dominion and control of the Collateral and Securities
                     Account, and neither the Borrower nor any Restricted
                     Subsidiary shall have any right of withdrawal therefrom,
                     except as provided in clause (ii) below;

                             (ii) upon receipt by the Collateral Agent of a
                     request from the Borrower (1) stating that the aggregate
                     amount on deposit in all Operating Accounts as of the
                     close of business on the immediately preceding Business
                     Day was not more than [REDACTED]* and (2) requesting that
                     the Collateral Agent transfer from the Collateral and
                     Securities Account to an Operating Account funds in an
                     amount which, after giving effect to such transfer, will
                     not cause the provisions of this Section 6.13 to be
                     violated, the Collateral Agent will transfer such
                     requested amount in accordance with such request.

               20.   Amendment to Section 7(c). Section 7(c) is hereby amended
to read in its entirety as follows:

               (c) The Borrower shall default in the observance or performance
               of any agreement contained in Section 5.12 or Section 5.13 or any
               Loan Party shall






                                       16
<PAGE>   17

               default in the observance or performance of any agreement
               contained in Section 6;

               21.    Amendment to Section 9.5. Section 9.5 of the Credit
Agreement is hereby amended by deleting clause (a) in its entirety and
substituting the following in lieu thereof:

               (a) to pay or reimburse the Agents, and the formal and informal
               members of any steering committee of Lenders, for all their
               reasonable out-of-pocket costs and expenses incurred in
               connection with the development, preparation and execution of,
               and any amendment, supplement or modification to, this Agreement
               and the other Loan Documents and any other documents prepared in
               connection herewith or therewith, and the consummation and
               administration of the transactions contemplated hereby and
               thereby, including, without limitation, the reasonable fees and
               disbursements of one counsel for all of the Agents and any other
               consultants or professional advisors (including, without
               limitation, financial advisors) retained by the Administrative
               Agent,

               22.    Amendment to Annex A. Annex A to the Credit Agreement is
hereby deleted in its entirety.

               23.    Amendment to Exhibits. Exhibit J attached hereto as Annex
A shall hereby be added as Exhibit J to the Credit Agreement.

               24.    Amendment to Section 3.2 of the Guarantee and Collateral
Agreement. Section 3.2 is hereby amended to read in its entirety as follows:

               3.2 Limitation on Obligation to Perfect. Notwithstanding the
               foregoing, it is understood and agreed that no Grantor will be
               required to take any action to perfect any security interest
               created hereby other than (A) the filing of financing statements
               under the Uniform Commercial Code in the states (and, where
               applicable, counties, towns and parishes) necessary or, in the
               reasonable judgment of the Administrative Agent, desirable to
               create a perfected first priority security interest in the
               Personal Property Assets of such Grantor, (B) the filings
               required in the United States Patent and Trademark Office to
               perfect the security interest created hereby in any material
               United States Patents or U.S. Trademarks owned or held by such
               Grantor, (C) the filings and registrations required in the United
               States Copyright Office to perfect the security interest created
               hereby in any material United States Copyrights owned or held by
               such Grantor, (D) delivery to the Collateral Agent of any
               Possessory Collateral owned by such Grantor and (E) any actions
               required to perfect the security interest created hereby in any
               Non-Excluded Personal Property which, in the case of any Real
               Property Assets, has not been transferred to a LeasingCo;
               provided, that if after the date hereof there is any change in
               law which requires actions in addition to those described above
               to cause the security interests created hereby to be perfected to
               the same extent as the perfection effected by the foregoing
               actions under laws in effect on the date hereof, the Grantors
               will take such additional actions.

               25.    Amendment to Section 5.3(a) of the Guarantee and
Collateral Agreement. Section 5.3(a) is hereby amended by deleting the reference
to "Section 4.5" and substituting in lieu thereof a reference to "Section 4.3".







                                       17
<PAGE>   18

               26.    Amendment to Section 5.6(b)(ii) of the Guarantee and
Collateral Agreement. Section 5.6(b)(ii) is hereby amended by inserting the
following phrase immediately after the word "instruments" and immediately before
the symbol ")":

               , and any such Pledged Securities so sold, assigned, transferred,
               exchanged or otherwise disposed of as permitted by the Secured
               Instruments shall cease to be Pledged Securities hereunder

               27.    Conditions Precedent. Subject to the satisfaction of the
following conditions, this Amendment will become effective as of March 30, 2001
(the "Effective Date"):

              (a) Amendment. The Administrative Agent shall have received
        counterparts of this Amendment, duly executed by the Borrower, the
        Administrative Agent and the Required Lenders.

              (b) No Default or Event of Default. On and as of the Effective
        Date after giving effect to this Amendment, no Default or Event of
        Default shall have occurred and be continuing.

              (c) Representations and Warranties. The representations and
        warranties made by the Borrower in the Credit Agreement and the other
        Loan Documents after giving effect to this Amendment and the
        transactions contemplated hereby shall be true and correct in all
        material respects on and as of the Effective Date as if made on such
        date, except that where such representations and warranties relate to an
        earlier date, such representations and warranties shall have been true
        and correct in all material respects as of such earlier date, provided
        that all references to the Credit Agreement in such representations and
        warranties shall be and are deemed to mean this Amendment as well as the
        Credit Agreement as amended hereby.

              (d) Certificate. The Administrative Agent shall have received a
        Certificate of a Responsible Officer of the Borrower certifying the
        matters referred to in paragraphs (b) and (c).

              (e) Secretary's Certificate. The Administrative Agent shall have
        received a certificate from the Secretary or Assistant Secretary of the
        Borrower dated as of the Effective Date, (i) certifying attached copies
        of resolutions of the Board of Directors of the Borrower, authorizing
        the execution, delivery and performance of this Amendment, including the
        increase in the amount of the Optional Term Loan Commitments,
        contemplated hereby, (ii) certifying that the By-Laws and the
        Certificate of Incorporation of the Borrower have not been amended,
        restated, supplemented or otherwise modified since July 2, 1998, except
        for the amendments, restatements, supplements or modifications attached
        as an exhibit to such certificate, and (iii) evidencing the incumbency
        and signatures of the officers signing this Amendment.

              (f) Opinions. The Administrative Agent shall have received in
        connection with this Amendment (i) an opinion of in-house counsel to the
        Borrower, covering such matters that the Administrative Agent shall
        reasonably request and customary for transactions of this type, and (ii)
        an enforceability opinion of Cravath, Swaine & Moore, special New York
        counsel to the Borrower, which opinion shall also cover the creation and
        perfection of the security interest of the Collateral Agent in the
        Collateral and






                                       18
<PAGE>   19


        Securities Account and the enforceability of the agreements entered
        into in connection therewith.

              (g) Approvals. The Administrative Agent shall have received
        copies of all necessary corporate and governmental approvals (if any) of
        the Borrower for the increase of the aggregate amount of the Optional
        Term Loan Tranches, the addition of the Optional Vendor Loan Tranches
        therein, and any other transactions contemplated hereby.

              (h) Fees and Expenses. The Administrative Agent shall have
        received all fees required to be paid, including, without limitation, an
        amendment fee for the account of each Lender which executes and delivers
        this Amendment on or before the date hereof of 25 basis points on such
        Lender's Commitment, and all expenses for which invoices have been
        presented, including, without limitation, all expenses required to be
        paid pursuant to Section 9.5 (after giving effect to this Amendment), on
        or before the date hereof.

              (i) Subsidiary and Collateral Schedule. The Administrative Agent
        shall have received in connection with this Amendment a schedule or
        schedules listing (i) each direct and indirect Subsidiary of the
        Borrower, (ii) the Borrower's and each such Subsidiary's jurisdiction of
        incorporation, (iii) the location of the chief executive office of the
        Borrower and each Domestic Subsidiary, (iv) the locations of any
        tangible personal property of the Borrower and each Domestic Subsidiary,
        (v) the identity of the owner of the Capital Stock of each direct and
        indirect Subsidiary of the Borrower (and specifying whether such Capital
        Stock is certificated or uncertificated and, with respect to each
        Domestic Subsidiary and each Excluded Foreign Subsidiary which is a
        Subsidiary of the Borrower or any Domestic Subsidiary, if certificated,
        the share certificate number and the number of shares issued and
        outstanding) and (vi) each filing office in which UCC financing
        statements should be filed to perfect the security interest of the
        Collateral Agent in all personal property of the Borrower and each
        Restricted Subsidiary. Such schedules shall be accompanied by a
        certificate of the Borrower certifying such schedules to be true and
        correct.

               28.    Continuing Effect; No Other Amendments. Except as
expressly amended or waived hereby, all of the terms and provisions of the
Credit Agreement and the other Loan Documents are and shall remain in full force
and effect. The amendments and consent contained herein shall not constitute an
amendment or consent of any other provision of the Credit Agreement or the other
Loan Documents or for any purpose except as expressly set forth herein.

               29.    Binding Effect. This Amendment shall apply equally to
each of the Lenders parties to the Credit Agreement, and shall be binding upon
the Borrower, the Lenders, the Administrative Agent, the Arrangers, the
Documentation Agent, the Syndication Agent and all future holders of the Notes.

               30.    Governing Law. THIS AMENDMENT AND THE RIGHTS AND
OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND
BE GOVERNED BY THE LAW OF THE STATE OF NEW YORK.

               31.    Counterparts. This Amendment may be executed in any
number of counterparts and by the different parties hereto in separate
counterparts, each of which when so executed and delivered shall be deemed to be
an original and all of which taken together shall








                                       19
<PAGE>   20


constitute one and the same instrument. Delivery of an executed counterpart of a
signature page of this Amendment by facsimile transmission shall be as effective
as delivery of a manually executed counterpart of this Amendment.

               32.    Headings. Section headings in this Amendment are included
herein for convenience of reference only and shall not constitute a part of this
Amendment for any other purpose.

  [Remainder of this page left blank intentionally; Signature page to follow.]





                                       20
<PAGE>   21

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

                                      TELIGENT, INC.


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

                                      THE CHASE MANHATTAN BANK,
                                      As Administrative Agent

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

                                      [INSERT NAME OF LENDER],
                                      As a Lender


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






<PAGE>   22

                                                                        ANNEX A


                                                                      EXHIBIT J


                          FORM OF NEW LENDER SUPPLEMENT

               SUPPLEMENT, dated _________________, to the Credit Agreement
dated as of July 2, 1998 (as amended, restated, supplemented or otherwise
modified from time to time, the "Credit Agreement"), among Teligent, Inc., a
Delaware corporation (the "Borrower"), the Lenders from time to time parties
thereto, Goldman Sachs Credit Partners L.P., as Syndication Agent, Toronto
Dominion (Texas), Inc., as Documentation Agent, and The Chase Manhattan Bank, as
Administrative Agent. Capitalized terms used herein without definition shall
have the meaning ascribed to such terms in the Credit Agreement.

                              W I T N E S S E T H :

                WHEREAS, the Credit Agreement provides in Section 2.7 thereof
that, in the case of any Optional Non-Vendor Loan Tranche, any banks, financial
institutions or other entities, and, in the case of any Optional Vendor Loan
Tranche, any Vendor, to the Borrower may become a party to the Credit Agreement
as an Optional Term Loan Lender with the consent of the Borrower and the
Administrative Agent (which consent, in the case of the Administrative Agent,
shall not be unreasonably withheld) by executing and delivering to the Borrower
and the Administrative Agent a supplement to the Credit Agreement in
substantially the form of this Supplement; and

               WHEREAS, the undersigned now desires to become a party to the
Credit Agreement;

               NOW, THEREFORE, the undersigned hereby agrees as follows:

               1. The undersigned agrees to be bound by the provisions of the
        Credit Agreement, and agrees that it shall, on the date this Supplement
        is accepted by the Borrower and the Administrative Agent, become an
        Optional [Non-]Vendor Loan Lender for all purposes of the Credit
        Agreement to the same extent as if originally a party thereto, with an
        Optional [Non-]Vendor Loan Commitment of [$____________].

               2. The undersigned (a) represents and warrants that it is legally
        authorized to enter into this Supplement; (b) confirms that it has
        received a copy of the Credit Agreement, together with copies of the
        financial statements referred to in Section 5.1 thereof and such other
        documents and information as it has deemed appropriate to make its own
        credit analysis and decision to enter into this Supplement; (c) agrees
        that it has made and will, independently and without reliance upon any
        Agents or any other Lender and based on such documents and information
        as it shall deem appropriate at the time, continue to make its own
        credit decisions in taking or not taking action under the Credit
        Agreement or any







<PAGE>   23

        instrument or document furnished pursuant hereto or thereto; (d)
        appoints and authorizes the Administrative Agent to take such action as
        agent on its behalf and to exercise such powers and discretion under
        the Credit Agreement or any instrument or document furnished pursuant
        hereto or thereto as are delegated to the Administrative Agent by the
        terms thereof, together with such powers as are incidental thereto;
        and (e) agrees that it will be bound by the provisions of the Credit
        Agreement and will perform in accordance with its terms all the
        obligations which by the terms of the Credit Agreement are required to
        be performed by it as a Lender including, without limitation, if it is
        organized under the laws of a jurisdiction outside the United States,
        its obligation pursuant to Section 2.21 of the Credit Agreement.

               3. The undersigned's address for notices for the purposes of the
        Credit Agreement is as follows:





   [Remainder of the page left blank intentionally; Signature page to follow.]





<PAGE>   24

               IN WITNESS WHEREOF, the undersigned has caused this Supplement to
be executed and delivered by a duly authorized officer on the date first above
written.

                                    [INSERT NAME OF LENDER]



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



Accepted this _____ day of

--------------, ----.


TELIGENT, INC.



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




Accepted this ____ day of

--------------, ----.

THE CHASE MANHATTAN BANK, as Administrative Agent


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


<PAGE>   25

                                                              Exhibit A to the
                                                        Amendment and Consent,
                                                    dated as of March 30, 2001


                              CONVERTIBLE NOTES
                                 TERM SHEET

ISSUER:            Teligent, Inc. (the "Company").

INVESTORS:         Such Persons as determined by the Company.

ISSUE:             Convertible Notes, in one or more series (all series taken
                   together the "Notes").

AMOUNT:            Not to be less than $100 million nor to exceed $150 million.

TERM:              [REDACTED]* from date of first draw down of the respective
                   Series.

INTEREST RATE:
(APPLICABLE TO ALL SERIES)

                   1.     From initial draw down to shareholder approval of the
                          Exchange Rights and Warrants: Libor plus [REDACTED]*
                          basis point, [REDACTED], on drawn Notes.

                   2.     Upon shareholder approval of the Exchange Rights and
                          the Warrants the rate is reset at [REDACTED]*.

                   3.     If the Exchange Rights and the Warrants are not
                          approved at the shareholder's meeting, then the
                          Notes become due and payable [REDACTED]* after such
                          shareholders meeting. The Company will hold the
                          shareholders meeting as soon as practicable, but in
                          no case later than [REDACTED]*.

AVAILABILITY:      Each series shall be available for draw down to the Company
                   in tranches at any time after closing.  All draws must be
                   made within [REDACTED]* after the execution of the definitive
                   agreements for the Notes.

CONDITIONS
PRECEDENT:         The availability of one series, which shall be in an amount
                   equal to or in excess of [REDACTED]* ("Series A"), is
                   contingent only on [REDACTED]*.

                   One series, which shall be in an amount equal to or in
                   excess of [REDACTED]* ("Series B"), shall close after the
                   end of [REDACTED]*, subject only to the [REDACTED]*.




<PAGE>   26

RANKING:           The Notes shall be subordinate, in right of payment, to
                   the Obligations, and any security interest securing the
                   Notes shall be subordinate to the security interest of the
                   Collateral Agent, in each case pursuant to subordination
                   and intercreditor provisions reasonably acceptable to the
                   Administrative Agent.

PURPOSE:           The Company may draw down on the Notes from time to time
                   only to finance the acquisition and development of
                   telecommunications assets.

EXCHANGE RIGHTS:   Subject to shareholders approval, the Note holders may
                   exchange the Notes for the Company's common stock
                   [REDACTED]*.

OPERATING
MILESTONES:        There shall be no financial covenant requirements (i)
                   other than those set forth in Section 6.1 clauses (c) and
                   (k) of the Credit Agreement (as amended by the Amendment)
                   and (ii) for any period except Q1 and Q2 2001.