<PAGE>   1
                          REGISTRATION RIGHTS AGREEMENT

            THIS REGISTRATION RIGHTS AGREEMENT, dated as of June 30, 1999, is
between NEXTLINK COMMUNICATIONS, INC., a Delaware corporation (the "Company")
and Craig O. McCaw ("COM").

            WHEREAS, COM currently owns directly 535,369 shares of Class B
common stock, $.02 par value, of the Company, (the "Class B Common Stock"); and

            WHEREAS, the Company wishes to grant COM and certain of his
Affiliates, as hereinafter defined, certain registration rights with respect to
the shares of Class A common stock, par value $.02 per share of the Company (the
"Class A Common Stock") into which the shares of Class B Common Stock are
convertible, as provided further herein.

            NOW THEREFORE, in consideration of the promises herein contained and
other good and valuable consideration, the parties hereto agree as follows:

            1.    Definitions.

            As used in this Agreement:

            (i) the terms "register," "registered" and "registration" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Act (and any post-effective amendments filed or required to
be filed) and the declaration or ordering of effectiveness of such registration
statement;

            (ii) the term "Registrable Securities" means (A) any shares of Class
A Common Stock acquired by COM or any COM Affiliate through conversion of Class
B Common Stock and (B) any capital stock of the Company issued as a dividend or
other distribution with respect to, or in exchange for or in replacement of, the
shares of Class A Common Stock referred to in clause (A) above;

            (iii) the term "Other Holders" shall mean those parties that are a
signatory to that certain Registration Rights Agreement dated January 15, 1997
among the Company and the parties listed on Schedule A hereto,Wendy P. McCaw and
her affiliates, as defined in that certain Registration Rights Agreement dated
November 7, 1997, and any COM Affiliate;

            (iv) the term "Holder" shall mean COM or any COM Affiliate that
holds Registrable Securities;

            (v) "Commission" shall mean the Securities and Exchange Commission
or any other federal agency at the time administering the Act;

            (vi) "Registration Expenses" shall mean all third-party expenses
incurred by the Company in compliance with Sections 2 and 3 hereof, including,
without limitation, all registration and filing fees, printing expenses, fees
and disbursements of counsel for the Company and the underwriters, if any, blue
sky fees and expenses and the third-party expenses of any special audits
incident to or required by any such registration (but excluding the compensation
of regular employees of the Company, which shall be paid in any event by the
Company);



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            (vii) "Selling Expenses" shall mean all underwriting discounts and
selling commissions applicable to the sale of securities and all fees and
disbursements of counsel for each of the holders of registered securities;

            (viii) "Act" shall mean the Securities Act of 1933, as amended; and

            (ix) "Exchange Act" shall mean the Securities Exchange Act of 1934.

            (x) "COM Affiliates" means any entity, or employee or member of any
entity, over which COM has direct or indirect majority voting control.

            2.  Requested Registration.

            (i) Request for Registration. If the Company shall receive from a
 Holder, a written request that the Company effect any registration with
respect to all or a part of the Registrable Securities, the Company will,
subject to compliance with any applicable underwriters' lock-up agreements in
effect as of the date of such request:

                  (A) promptly give written notice of the proposed registration
      qualification or compliance to all Other Holders ; and

                  (B) as soon as practicable, use its diligent best efforts to
      effect such registration (including, without limitation, the execution of
      an undertaking to file post-effective amendments, appropriate
      qualification under applicable blue sky or other state securities laws and
      appropriate compliance with applicable regulations issued under the Act)
      as may be so requested and as would permit or facilitate the sale and
      distribution as soon as is practicable of all or such portion of such
      Registrable Securities as are specified in such request, together with all
      or such portion of the Registrable Securities of any Holder or Holders
      joining in such request as are specified in a written request received by
      the Company within twenty (20) business days after written notice from the
      Company is given under Section 2(i)(A) above; provided that the Company
      shall not be obligated to effect, or take any action to effect, any such
      registration pursuant to this Section 2:

                  (a) In any particular jurisdiction in which the Company would
            be required to execute a general consent to service of process in
            effecting such registration, qualification or compliance, unless the
            Company is already subject to service in such jurisdiction and
            except as may be required by the Act or applicable rules or
            regulations thereunder;

                  (b) After the Company has effected one (1) such registration
            pursuant to this Section 2 and such registration has been declared
            or ordered effective and the sales of such Registrable Securities
            shall have closed;

                  (c) If the securities requested by COM and all Other Holders
            to be registered pursuant to such request have an anticipated
            aggregate public offering price (before any underwriting discounts
            and commissions) of less than $10,000,000.

            The registration statement filed pursuant to the request of COM may,
subject to the




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provisions of Section 2(ii) below, include other securities of the Company which
are held by officers or directors of the Company, or which are held by persons
who, by virtue of agreements with the Company, are entitled to include their
securities in any such registration, but the Company shall have no absolute
right to include any of its securities in any such registration.

            The registration rights set forth in this Section 2 are personal to
COM and shall not be assignable, by operation of law or otherwise, to any third
party other than a COM Affiliate.

            (ii) Underwriting. If COM or a COM Affiliate intends to distribute
the Registrable Securities covered by their request by means of an underwriting,
the initiating Holder shall so advise the Company as a part of their request
made pursuant to Section 2.

            If officers or directors of the Company holding other securities of
the Company shall request inclusion in any registration pursuant to Section 2,
or if holders of securities of the Company other than Registrable Securities who
are entitled, by contract with the Company or otherwise, to have securities
included in such a registration (the "Other Stockholders") request such
inclusion, COM shall offer to include the securities of such officers, directors
and Other Stockholders in the underwriting and may condition such offer on their
acceptance of the further applicable provisions of this Section 2. COM, any COM
Affiliate participating in the registration, and the Company shall (together
with all officers, directors and Other Stockholders proposing to distribute
their securities through such underwriting) enter into an underwriting agreement
in customary form with the representative of the underwriter or underwriters
selected for such underwriting by COM and reasonably acceptable to the Company.
Notwithstanding any other provision of this Section 2, if the representative
advises the Holders that marketing factors require a limitation on the number of
shares to be underwritten, the securities of the Company held by officers or
directors of the Company and the securities held by Other Stockholders (other
than the Other Holders) shall be excluded from such registration to the extent
so required by such limitation. If, after the exclusion of such shares, further
reductions are still required, the number of shares included in the registration
by COM and each Other Holder shall be reduced on a pro rata basis (based on the
number of shares proposed to be sold by COM or such Other Holders), by such
minimum number of shares as is necessary to comply with such request. No
Registrable Securities or any other securities excluded from the underwriting by
reason of the underwriter's marketing limitation shall be included in such
registration. If any officer, director or Other Stockholder who has requested
inclusion in such registration as provided above disapproves of the terms of the
underwriting, such person may elect to withdraw therefrom by written notice to
the Company, the underwriter and COM. The securities so withdrawn shall also be
withdrawn from registration. If the underwriter has not limited the number of
Registrable Securities or other securities to be underwritten, the Company may
include its securities for its own account in such registration if the
representative so agrees and if the number of Registrable Securities and other
securities which would otherwise have been included in such registration and
underwriting will not thereby be limited.

            (iii) Notwithstanding the foregoing, if the Company shall furnish to
the Holders a certificate signed by the President or Chief Executive Officer of
the Company stating that in the good faith judgment of the Board of Directors of
the Company, it would be seriously detrimental to the Company and its
shareholders for such registration statement to be filed and it is therefore
essential to defer the filing of such registration statement, then the Company
shall have the right to defer such filing for a period of not more than 120 days
after receipt of the request of the initiating Holder; provided, however, that
the Company may not utilize this right more than once in any twelve (12) month
period.



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            3.  Company Registration.

            (i) If, at any time, the Company shall determine to register any of
its equity securities either for its own account or for the account of a
security holder or holders exercising their respective demand registration
rights, other than a registration relating solely to employee benefit plans, or
a registration relating solely to a Commission Rule 145 transaction, or a
registration on any registration form which does not permit secondary sales or
does not include substantially the same information as would be required to be
included in a registration statement covering the sale of Registrable
Securities, the Company will:

                  (A) promptly give to each of the Holders a written notice
      thereof (which shall include a list of the jurisdictions in which the
      Company intends to attempt to qualify such securities under the applicable
      blue sky or other state securities laws); and

                  (B) include in such registration (and any related
      qualification under blue sky laws or other compliance), and in any
      underwriting involved therein, all the Registrable Securities specified in
      a written request or requests, made by the Holders within twenty (20) days
      after receipt of the written notice from the Company described in clause
      (i) above, except as set forth in Section 3(ii) below. Such written
      request may specify all or a part of Registrable Securities held by COM or
      a COM Affiliate.

            (ii) Underwriting. If the registration of which the Company gives
notice is for a registered public offering involving an underwriting, the
Company shall so advise each of the Holders as a part of the written notice
given pursuant to Section 3(i)(A). In such event, the right of each of the
Holders to registration pursuant to this Section 3 shall be conditioned upon
such Holders' participation in such underwriting and the inclusion of such
Holders' Registrable Securities in the underwriting to the extent provided
herein. The Holders whose shares are to be included in such registration shall
(together with the Company and the Other Stockholders distributing their
securities through such underwriting) enter into an underwriting agreement in
customary form with the representative of the underwriter or underwriters
selected for underwriting by the Company. Notwithstanding any other provision of
this Section 3, if the representative determines that marketing factors require
a limitation on the number of shares to be underwritten, the representative may
(subject to the allocation priority set forth below) limit the number of
Registrable Securities to be included in the registration and underwriting. The
Company shall so advise all holders of securities requesting registration, and
the number of shares of securities that are entitled to be included in the
registration and underwriting shall be allocated in the following manner: The
securities of the Company held by officers, directors and Other Stockholders
(other than the Other Holders) of the Company (other than securities held by
holders who by contractual right initiated the demand for such registration
("Demanding Holders")) shall be excluded from such registration and underwriting
to the extent required by such limitation, and, if a limitation on the number of
shares is still required, the number of shares that may be included in the
registration and underwriting by COM and each of the Other Holders and Demanding
Holders shall be reduced, on a pro rata basis (based on the number of shares
proposed to be sold by COM and such Other Holders or Demanding Holders), by such
minimum number of shares as is necessary to comply with such limitation. If any
of COM or such Other Holders or Demanding Holders or any officer, director or
Other Stockholder disapproves of the terms of any such underwriting, he may
elect to withdraw therefrom by written notice to the Company and the
underwriter. Any Registrable Securities or other securities excluded or
withdrawn from such underwriting shall be withdrawn from such registration.

            (iii) Number and Transferability. Each of the Holders shall be
entitled to have his




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shares included in an unlimited number of registrations pursuant to this Section
3. The registration rights granted pursuant to this Section 3 are personal to
the Holders and shall not be assignable, by operation of law or otherwise to any
third party that is not a COM Affiliate.

            4. Expenses of Registration. All Registration Expenses and Selling
Expenses incurred in connection with any registration, qualification or
compliance pursuant to Section 2 of this Agreement shall be borne by the holders
of the securities so registered pro rata on the basis of the number of shares so
registered. Without limiting the generality of the foregoing, in the event the
Company includes shares in any registration, qualification or compliance
pursuant to Section 2 of this Agreement, the Company shall pay the Registration
Expenses in proportion to the Company's share of the total number of shares
included in such registration. All Registration Expenses incurred in connection
with any registration, qualification or compliance pursuant to Section 3 of this
Agreement shall be borne by the Company (or the Demanding Holders if so provided
in the applicable contract), and all Selling Expenses incurred in connection
with any such registration, qualification or compliance shall be borne by the
holders of securities so registered pro rata on the basis of the number of
shares so registered.

            5. Registration Procedures. In the case of each registration
effected by the Company pursuant to this Agreement, the Company will keep the
Holders advised in writing as to the initiation of each registration and as to
the completion thereof. The Company will:

                  (i) Keep such registration effective for a period of one
      hundred eighty (180) days or until the Holders have completed the
      distribution described in the registration statement relating thereto,
      whichever first occurs; provided, however, that (A) such 180-day period
      shall be extended for a period of time equal to the period during which
      the Holders will refrain from selling any securities included in such
      registration in accordance with provisions in Section 9 hereof; and (B) in
      the case of any registration of Registrable Securities on Form S-3 which
      are intended to be offered on a continuous or delayed basis, such 180-day
      period shall be extended until all such Registrable Securities are sold,
      provided that Rule 415, or any successor rule under the Act, permits an
      offering on a continuous or delayed basis, and provided further that
      applicable rules under the Act governing the obligation to file a
      post-effective amendment permit, in lieu of filing a post-effective
      amendment which (1) includes any prospectus required by Section 10(a) of
      the Act or (2) reflects facts or events representing a material or
      fundamental change in the information set forth in the registration
      statement, the incorporation by reference of information required to be
      included in (1) and (2) above to be contained in periodic reports filed
      pursuant to Section 12 or 15(d) of the Exchange Act in the registration
      statement.

                  (ii) Furnish such number of prospectuses and other documents
      incident thereto as each of the Holders from time to time may reasonably
      request; provided, however, that COM and the other holders of securities
      so registered, pro rata on the basis of the number of their shares so
      included in such registration, shall reimburse the Company for expenses
      incurred in performing its obligations under this Section 5.

                  (iii) Prepare and file with the SEC such amendments and
      supplements to such registration statement and the prospectus used in
      connection with such registration statement as may be necessary to comply
      with the provisions of the Act with respect to the disposition of all
      securities covered by such registration statement.


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                  (iv) Use its best efforts to register and qualify the
      securities covered by such registration statement under such other
      securities or Blue Sky laws of such jurisdictions as shall be reasonably
      requested by the Holders, provided that the Company shall not be required
      in connection therewith or as a condition thereto to qualify to do
      business or to file a general consent to service of process in any such
      states or jurisdictions.

                  (v) In the event of any underwritten public offering, enter
      into and perform its obligations under an underwriting agreement, in usual
      and customary form, with the managing underwriter of such offering. Each
      Holder participating in such underwriting shall also enter into and
      perform his obligations under such an agreement.

                  (vi) Furnish, at the request of any Holder requesting
      registration pursuant to this Agreement, on the date that such Registrable
      Securities are delivered to the underwriters for sale in connection with a
      registration pursuant to this Agreement, if such securities are being sold
      through underwriters, or, if such securities are not being sold through
      underwriters, on the date that the registration statement with respect to
      such securities becomes effective, (A) an opinion, dated such date, of the
      counsel representing the Company for the purposes of such registration, in
      form and substance as is customarily given to underwriters in an
      underwritten public offering, addressed to the underwriters, if any, and
      to the Holders requesting registration and (B) a letter dated such date,
      from the independent certified public accountants of the Company, in form
      and substance as is customarily given by independent certified public
      accountants to underwriters in an underwritten public offering, addressed
      to the underwriters, if any, and to the Holders requesting registration of
      Registrable Securities.

            6.  Indemnification.

            (i) The Company will indemnify COM, each COM Affiliate and each of
the officers, directors and partners and each person controlling each of the COM
entities (collectively the "COM Indemnified Parties"), with respect to each
registration which has been effected pursuant to this Agreement, and each
underwriter, if any, and each person who controls any underwriter, against all
claims, losses, damages and liabilities (or actions in respect thereof) arising
out of or based on any untrue statement (or alleged untrue statement) of a
material fact contained in any prospectus, offering circular or other document
(including any related registration statement, notification or the like)
incident to any such registration, qualification or compliance, or based on any
omission (or alleged omission) to state therein a material fact required to be
stated therein or necessary to make the statements therein not misleading, or
any violation by the Company of the Act or any rule or regulation thereunder
applicable to the Company and relating to action or inaction required of the
Company in connection with any such registration, qualification or compliance,
and will reimburse each of the COM Indemnified Parties, each such underwriter
and each person who controls any such underwriter, for any legal and any other
expenses reasonably incurred in connection with investigating and defending any
such claim, loss, damage, liability or action, provided that the Company will
not be liable in any such case to the extent that any such claim, loss, damage,
liability or expense arises out of or is based on any untrue statement or
omission based upon written information furnished to the Company by COM, or
other COM indemnified parties, or the underwriter and stated to be specifically
for use therein.

            (ii)   COM will, if Registrable Securities held by COM are
                   included in the securities as to which such registration,
                   qualification or compliance is being effected, indemnify




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                  the Company, each of its directors and officers and each
                  underwriter, if any, of the Company's securities covered by
                  such a registration statement, each person who controls the
                  Company or such underwriter within the meaning of the Act
                  and the rules and regulations thereunder, each Other
                  Stockholder and each of their officers, directors, and
                  partners, and each person controlling such Other
                  Stockholder against all claims, losses, damages and
                  liabilities (or actions in respect thereof) arising out of
                  or based on any untrue statement (or alleged untrue
                  statement) of a material fact contained in any such
                  registration statement, prospectus, offering circular or
                  other document made by COM, or any omission (or alleged
                  omission) to state therein a material fact required to be
                  stated therein or necessary to make the statements by COM
                  therein not misleading, and will reimburse the Company and
                  such Other Stockholders, directors, officers, partners,
                  persons, underwriters or control persons for any legal or
                  any other expenses reasonably incurred in connection with
                  investigating or defending any such claim, loss, damage,
                  liability or action, in each case to the extent, but only
                  to the extent, that such untrue statement (or alleged
                  untrue statement) or omission (or alleged omission) is made
                  in such registration statement, prospectus, offering
                  circular or other document in reliance upon and in
                  conformity with written information furnished to the
                  Company by COM or other COM indemnified parties and stated
                  to be specifically for use therein; provided, however, that
                  the obligations of COM hereunder shall be limited to an
                  amount equal to the net proceeds to of securities sold as
                  contemplated herein.

            (iii) Each party entitled to indemnification under this Section 6
(the "Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom; provided that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or any litigation resulting
therefrom, shall be approved by the Indemnified Party (whose approval shall not
unreasonably be withheld) and the Indemnified Party may participate in such
defense at such party's expense (unless the Indemnified Party shall have
reasonably concluded that there may be a conflict of interest between the
Indemnifying Party and the Indemnified Party in such action, in which case the
fees and expenses of counsel shall be at the expense of the Indemnifying Party),
and provided further that the failure of any Indemnified Party to give notice as
provided herein shall not relieve the Indemnifying Party of its obligations
under this Section 6 unless the Indemnifying Party is materially prejudiced
thereby. No Indemnifying Party, in the defense of any such claim or litigation,
shall, except with the consent of each Indemnified Party, consent to entry of
any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation. Each Indemnified Party shall furnish such information regarding
itself or the claim in question as an Indemnifying Party may reasonably request
in writing and as shall be reasonably required in connection with the defense of
such claim and litigation resulting therefrom.

            (iv) If the indemnification provided for in this Section 6 is held
by a court of competent jurisdiction to be unavailable to an Indemnified Party
with respect to any loss, liability, claim, damage or expense referred to
herein, then the Indemnifying Party, in lieu of indemnifying such Indemnified
Party hereunder, shall contribute to the amount paid or payable by such
Indemnified Party as a result of such loss, liability, claim, damage or expense
in such proportion as is appropriate to reflect the relative fault of the


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Indemnifying Party on the one hand and of the Indemnified Party on the other in
connection with the statements or omissions which resulted in such loss,
liability, claim, damage or expense, as well as any other relevant equitable
considerations. The relative fault of the Indemnifying Party and of the
Indemnified Party shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission to state a material fact relates to information supplied by the
Indemnifying Party or by the Indemnified Party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission.

            (v) Notwithstanding the foregoing, to the extent that the provisions
on indemnification and contribution contained in the underwriting agreement
entered into in connection with any underwritten public offering contemplated by
this Agreement are in conflict with the foregoing provisions, the provisions in
such underwriting agreement shall be controlling.

            (vi) The foregoing indemnity agreement of the Company and COM is
subject to the condition that, insofar as they relate to any loss, claim,
liability or damage made in a preliminary prospectus but eliminated or remedied
in the amended prospectus on file with the Commission at the time the
registration statement in question becomes effective or the amended prospectus
filed with the Commission pursuant to Commission Rule 424(b) (the "Final
Prospectus"), such indemnity agreement shall not inure to the benefit of any
underwriter if a copy of the Final Prospectus was furnished to the underwriter
and was not furnished to the person asserting the loss, liability, claim or
damage at or prior to the time such action is required by the Act.

            7. Information by the Holders. Each of the Holders and each Other
Stockholder holding securities included in any registration shall furnish to the
Company such information regarding such Holder or Other Stockholder and the
distribution proposed by such Holder or Other Stockholder as the Company may
reasonably request in writing and as shall be reasonably required in connection
with any registration, qualification or compliance referred to in this
Agreement.

            8.  Rule 144 Reporting.

            With a view to making available the benefits of certain rules and
regulations of the Commission which may permit the sale of restricted securities
to the public without registration, the Company agrees to:

                  (i) make and keep public information available as those terms
      are understood and defined in Rule 144, at all times from and after ninety
      (90) days following the effective date of the first registration under the
      Act filed by the Company for an offering of its securities to the general
      public;

                  (ii) use its best efforts to file with the Commission in a
      timely manner all reports and other documents required of the Company
      under the Act and the Exchange Act at any time after it has become subject
      to such reporting requirements; and

                  (iii) so long as the Holder owns any Registrable Securities,
      furnish to the Holder upon request, a written statement by the Company as
      to its compliance with the reporting requirements of Rule 144 (at any time
      from and after ninety (90) days following the effective date of the first
      registration statement filed by the Company for an offering of its
      securities to the general


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      public), and of the Act and the Exchange Act (at any time after it has
      become subject to such reporting requirements), a copy of the most recent
      annual or quarterly report of the Company, and such other reports and
      documents so filed as the Holder may reasonably request in availing
      himself of any rule or regulation of the Commission allowing the Holder to
      sell any such securities without registration.

            9. "Market Stand-off" Agreement. Each Holder will agree, if
requested by the Company and an underwriter of Common Stock (or other
securities) of the Company, not to sell or otherwise transfer or dispose of any
Class A Common Stock (or other securities) of the Company held by such Holder
during the 90 day period following any registration statement filed under the
Act to register Common Stock of the Company.

            If requested by the underwriters, the Holders shall execute a
separate agreement to the foregoing effect. The Company may impose stop-transfer
instructions with respect to the shares (or securities) subject to the foregoing
restriction until the end of such period.

            10. Termination. The registration rights set forth in this Agreement
shall not be available to COM or the COM Affiliates if, in the opinion of
counsel to the Company, all of the Registrable Securities then owned by COM and
the COM Affiliates could be sold in any 90-day period pursuant to Rule 144 under
the Act (without giving effect to the provisions of Rule 144(k)). In addition,
the registration rights set forth in this Agreement shall terminate upon the
transfer or assignment of the Registrable Securities to any non-affiliated third
party.

            11. Notices. All communications provided for hereunder shall be sent
by first-class mail or facsimile and (a) if addressed to COM, addressed to COM
at the address or fax number contained on Schedule B to this Agreement, or at
such other address or fax number as COM shall have furnished to the Company in
writing or (b) if addressed to the Company, at 500 108th Avenue NE, 8th Floor,
Bellevue, Washington 98004, Attention: General Counsel, or fax number (425)
519-8910 or at such other address or fax number, or to the attention of such
other officer, as the Company shall have furnished to COM in writing. Notices
sent by first-class mail shall be deemed received three days after the date of
deposit of such notice in the United States mail. Notices sent by facsimile
shall be deemed received upon receipt by the notified party's facsimile machine.

            12. No Assignment. This Agreement is personal to COM and shall not
be assignable, by operation of law or otherwise to any third party other than a
COM Affiliate.

            13. Descriptive Headings. The descriptive headings of the several
sections and paragraphs of this Agreement are inserted for reference only and
shall not limit or otherwise affect the meaning hereof.

            14.  Governing Law.  This Agreement shall be construed and
enforced in accordance with, and the rights of the parties shall be governed
by, the laws of the State of Delaware

            15. No Inconsistent Agreements. The Company will not on or after the
date of this Agreement enter into any agreement with respect to its securities
that conflicts with or would limit the rights granted to COM in this Agreement
or otherwise conflicts with the provisions hereof.

            16. Amendments and Waivers. No provision of this Agreement may be
amended or


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waived except by an instrument in writing signed by the party sought to be
bound.

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

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


                                    By:  /s/ Craig O. McCaw
                                        ------------------------------
                                             Craig O. McCaw

                                    NEXTLINK COMMUNICATIONS, INC.


                                    By: /s/ R. Bruce Easter
                                        ------------------------------
                                          Name: R. Bruce Easter
                                                ----------------------
                                          Title: Vice President
                                                ----------------------



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                                   SCHEDULE A

                      OTHER HOLDERS' ADDRESSES FOR NOTICES

EAGLE RIVER INVESTMENTS, L.L.C.
c/o C. James Judson
2300 Carillon Point
Kirkland, WA 98033
Fax:  (425) 828-8061

NEXTLINK, INC. c/o R. Bruce Easter, Jr.
500 108th Avenue N.E., Suite 2200
Bellevue, WA 98004
Fax:  (425) 519-8910

BWP, INC.
c/o Robert Kingery
707 S.W. Washington, 8th Floor
Portland, OR 97205
Fax:  (503) 727-6821

ROWENA FAMILY LIMITED LIABILITY COMPANY
c/o Scot Jarvis
4153 Issaquah Pine Lake Road
Issaquah, WA 98029
Fax:  (425) 392-9944

PENNS LIGHT COMMUNICATIONS, INC.
c/o Gary Rawding
925 Berkshire Blvd.
Wyomissing, PA 91610
Fax:  (610) 288-5666

PROBE VENTURES CORP.
c/o Victor Schnee
Three Wing Drive, Suite 240
Cedar Knolls, NJ 07927-1000
Fax:  (201) 285-1519

CITY SIGNAL, INC.
c/o Richard Postma
Miller, Johnson, Snell & Cummiskey
800 Calder Plaza Building
Grand Rapids, MI 49503
Fax:  (616) 459-6708



Page - 11 REGISTRATION RIGHTS AGREEMENT

<PAGE>   12

U.S. NETWORK CORPORATION
c/o Ron Gavillet
10 South Riverside Plaza, Suite 401
Chicago, IL 60606-3709
Fax:  (312) 906-3636

G. ANDREW BARFUSS
1499 North Cherry Blossom Drive
Farmington, UT 84025-3900
Fax:  (801)451-9708

J. MERRILL BEAN
1972 North 2600 East
Layton, UT 84040
Fax:  (801)451-9708

JOAN BEAN
1972 North 2600 East
Layton, UT 84040
Fax:  (801)451-9708

SCOT JARVIS
4153 Issaquah Pine Lake Road
Issaquah, Washington 98029
Fax:  (206) 392-9944

WENDY P. MCCAW
C/O Greg Parker
Ampersand Holdings, Inc.
1301 Santa Barbara St.
Santa Barbara, CA. 93101
Fax: (805) 884-0249






Page - 12 REGISTRATION RIGHTS AGREEMENT


<PAGE>   13

                                   SCHEDULE B

                      CRAIG O. McCAW'S ADDRESS FOR NOTICES


Craig O.  McCaw
Eagle River, Inc.
2300 Carillon Point
Kirkland, WA  98083-2908
Fax:  (425) 828-8061





Page - 13 REGISTRATION RIGHTS AGREEMENT