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                                                                   Exhibit 10.36

                               FIRST AMENDMENT TO
                              AMENDED AND RESTATED
                               PURCHASE AGREEMENT

     This First Amendment to Amended and Restated Purchase Agreement (the
"Amendment") is made as of May 25, 1999 by and among Advanced Radio Telecom
Corp., a Delaware corporation ("Customer"), and Lucent Technologies Inc., a
Delaware corporation ("Seller").

                                    RECITALS
                                    --------

     1.  Customer and Seller are parties to a certain Amended and Restated
Purchase Agreement dated as of July 24, 1998 (the "Purchase Agreement").
Capitalized terms used in this Amendment without definition shall have the same
meaning as in the Purchase Agreement.

     2.  The parties wish to amend the Purchase Agreement to change certain
terms related to Customer's purchase commitment.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

     1.  Amendments.   The Purchase Agreement is amended as follows:
         ----------

         1.1.  Article 1 of the Purchase Agreement is hereby amended by changing
     the following subsections:

               (h) the language "Section 2.8(b)" in the definition of "Average
          Allocation" is hereby deleted and replaced with "Section 2.8."

               (i) the language "Section 2.8(b), including Cure Purchases" in
          the definition of "Average Allocation Test" is hereby deleted and
          replaced with "Section 2.8."

               (k) the definition of "Best In Class" is hereby deleted.

               (o) the definition of "Characteristics" is hereby deleted.

               (t) the definition of "Cure Purchases" is hereby deleted.

               (u) the definition of "Customer Comparison" is hereby deleted.
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               (w) the definition of "Deficiency Notice" is hereby deleted.

               (x) the definition of "Deliverable" is hereby deleted.

               (yyyy)  the definition of "Total Contract Value" shall be
          deleted.

       1.2.  Section 2.1 of the Purchase Agreement is hereby amended to replace
     the two instances of the word "will" with, in each case, the word "may."

       1.3.  Section 2.2 of the Purchase agreement is hereby amended to replace
     the phrase "that is not expected to exceed $1.2 billion" with the phrase
     "to the extent purchased by Customer hereunder."

       1.4.  Section 2.8 of the Purchase Agreement is hereby deleted and
     replaced with the following:

               "2.8.  Average Allocation.  Customer may from time to time place
                      ------------------
          RS Orders and Orders with Seller.  For purposes of this Agreement, the
          "Average Allocation" for any Allocation Period shall be calculated by
          averaging such RS Orders and Orders for any Allocation Period and all
          previous Allocation Periods, provided that Customer shall at no time
          have any obligation to place RS Orders or Orders and shall at all
          times have the right to purchase products and licensed materials from
          vendors other than Seller."

       1.5.  Section 2.9 of the Purchase Agreement is hereby deleted and
     replaced with the following:

               "2.9.  International Orders.  The parties agree that if the
                      --------------------
          parties agree upon the provision by Seller of products, licensed
          materials or services to Customer or its Subsidiaries in any
          territories outside the United States, the amount of any orders placed
          for such products, licensed materials and services shall be included
          in the calculation of Average Allocation pursuant to Section 2.8
          hereof."

       1.6.  A new Section 2.10 shall be added to the Purchase Agreement as
     follows:

               "2.10.  Commitment. The parties hereby agree that Customer has no
                       ----------
          commitment to purchase any equipment, software or services from Seller
          hereunder, including having no minimum purchase commitments hereunder,
          and that Customer may purchase equipment, software and services from
          other parties for its network.   The parties agree that,
          notwithstanding anything else in the Agreement, all other provisions
          of this agreement shall be interpreted consistently with the foregoing
          sentence."

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       1.7.  Section 3.1 of the Purchase Agreement is hereby deleted and
     replaced with the following:

               "3.1.  Configuration of the Network.  With respect to equipment,
                      ----------------------------
          software and services purchased prior to the date of the effectiveness
          of Amendment 1 hereto and, with respect to equipment purchased after
          the date of the effectiveness of Amendment 1 hereto then to the extent
          agreed by the parties from time to time, Seller will configure and
          engineer a state of the art Network to provide wireless, packet-based,
          broadband data services to those major metropolitan areas throughout
          the United States agreed upon by the parties, in accordance with the
          Specifications and Responsibility Matrix which may be updated or
          amended from time to time by mutual written agreement.  In designing
          the Network, in order to accommodate the ultimate demands on the
          Network, Seller will assist Customer in evaluating the size and
          potential requirements of the market for wireless, broadband data
          services and in planning and structuring the Network to best realize
          such potential."

       1.8.  Section 3.2 of the Purchase Agreement is hereby amended by adding
     the following text to the beginning of the Section, immediately preceding
     the word "Seller":

               "With respect to equipment, software and services purchased prior
          to the date of the effectiveness of Amendment 1 hereto and, with
          respect to equipment purchased after the date of the effectiveness of
          Amendment 1 hereto then to the extent agreed by the parties from time
          to time,"

       1.9.  Section 3.4 of the Purchase Agreement shall be deleted in its
     entirety.

       1.10. Section 6.10 of the Purchase Agreement is hereby deleted and
     replaced with the following:

               "6.10.  Security Interest.  Seller retains and Customer hereby
                       -----------------
          grants Seller a purchase money security interest in the Network to
          secure any and all amounts due Seller under this Agreement for the
          Purchase Price of the Network.  Seller shall have the right, at any
          time during the Term, to file in any state or local jurisdiction such
          financing statements (e.g., UCC-1 financing statements) as Seller
          deems necessary to perfect its purchase money security interest
          hereunder, provided Customer is furnished a copy of such financing
          statements before filing.  Upon Seller's reasonable request, Customer
          shall execute all documents necessary or desirable to evidence or
          perfect Seller's purchase money security interest in the Network
          including without limitation, UCC-1 financing statements.  Customer
          also agrees that this Agreement may be filed by Seller in any state or
          local jurisdiction as a financing statement (or as other evidence of
          the Seller's purchase money security interest).  To the extent
          Customer has no outstanding financial obligations to Seller hereunder,
          Seller will, if

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          requested by Customer, take reasonable steps necessary to terminate
          and release such security interests, including filing UCC-3
          termination statements."

     2.  Ratification.  Except as modified by this Amendment, the Purchase
         ------------
Agreement is hereby ratified and reconfirmed in all respects.

     3.  Indebtedness.  Immediately following the closing of Customer's sale of
         ------------
convertible preferred stock pursuant to a Preferred Stock Purchase Agreement to
be executed in May 1999 among Customer and certain "Purchasers" named therein,
Customer shall repay Seller all amounts due Seller under the Purchase Money
Credit Agreement, dated September 17, 1998 and the Working Capital Credit
Agreement, dated September 17, 1998, each between Customer and Seller.  Customer
and Seller intend to enter into an Amendment No. 1, Waiver and Consent Agreement
dated on or about the date hereof pursuant to which certain terms of the
foregoing agreements are to be modified.  This agreement is intended to operated
in conjunction with such agreement and to be interpreted consistently therewith.

     4.  Counterparts.  The Amendment may be executed simultaneously in one or
         ------------
more counterparts hereof, each of which shall be deemed an original, but all of
which together shall constitute one and the same agreement.

     5.  Effectiveness.  This Amendment shall be effective upon the execution by
         -------------
Customer and Seller.

                    [Remainder of Page Intentionally Blank]

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     The foregoing Amendment is hereby executed as of the date first above
written.

                              ADVANCED RADIO TELECOM CORP.



                              By: /s/ Henry C. Hirsch
                                  -------------------------------
                                    Name:  Henry C. Hirsch
                                    Title: Chairman & CEO


                              LUCENT TECHNOLOGIES INC.



                              By: /s/ Bill Plunkett
                                  -------------------------------
                                    Name:  Bill Plunkett
                                    Title: Senior Vice President

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