ADVANCED RADIO TELECOM CORP
S-1/A, 1996-07-03
CABLE & OTHER PAY TELEVISION SERVICES
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<PAGE>
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 3, 1996
                                                      REGISTRATION NO. 333-04388
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------
                                AMENDMENT NO. 1
                                       TO
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                          ADVANCED RADIO TELECOM CORP.
              (Currently Advanced Radio Technologies Corporation)
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                              <C>                            <C>
           DELAWARE                          4812                  52-1348016
 (State or Other Jurisdiction    (Primary Standard Industrial   (I.R.S. Employer
              of                 Classification Code Number)     Identification
Incorporation or Organization)                                        No.)
</TABLE>
 
<TABLE>
<S>                              <C>
                                    VERNON L. FOTHERINGHAM
                                   CHIEF EXECUTIVE OFFICER
 ADVANCED RADIO TELECOM CORP.    ADVANCED RADIO TELECOM CORP.
500 108TH AVENUE, N.E., SUITE      500 108TH AVENUE, N.E.,
             2600                         SUITE 2600
  BELLEVUE, WASHINGTON 98004      BELLEVUE, WASHINGTON 98004
        (206) 688-8700                  (206) 688-8700
(Address, Including Zip Code,     (Name, Address, Including
    and Telephone Number,          Zip Code, and Telephone
   Including Area Code, of       Number, Including Area Code,
    Registrant's Principal          of Agent for Service)
      Executive Offices)
</TABLE>
 
<TABLE>
<S>                              <C>                            <C>
                                   COPIES TO:
      JAMES KARDON, ESQ.          JOHN D. WATSON, JR., ESQ.       W. THEODORE
      HAHN & HESSEN LLP                LATHAM & WATKINS          PIERSON, JR.,
       350 FIFTH AVENUE          1001 PENNSYLVANIA AVE., N.W.         ESQ.
   NEW YORK, NEW YORK 10118         WASHINGTON, D.C. 20004         PIERSON &
        (212) 736-1000                  (202) 637-2200            BURNETT, LLP
                                                                1667 K. STREET,
                                                                N.W., SUITE 801
                                                                WASHINGTON, D.C.
                                                                     20006
                                                                 (202) 466-3044
</TABLE>
 
                            ------------------------
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
  AS SOON AS PRACTICABLE AFTER THIS REGISTRATION STATEMENT BECOMES EFFECTIVE.
                            ------------------------
    If  any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to  Rule 415 under the Securities Act  of
1933, check the following box.  / /
 
    If  this Form  is filed  to register  additional securities  for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration statement  number  of  the  earlier
effective registration statement for the same offering.  / /
 
    If  this Form  is a post-effective  amendment filed pursuant  to Rule 462(c)
under the Securities Act,  check the following box  and list the Securities  Act
registration  statement number  of the earlier  effective registration statement
for the same offering.  / /
 
    If delivery of the prospectus is expected  to be made pursuant to Rule  434,
please check the following box.  / /
                            ------------------------
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<CAPTION>
                                                    PROPOSED         PROPOSED
 TITLE OF EACH CLASS OF                              MAXIMUM          MAXIMUM         AMOUNT OF
    SECURITIES TO BE            AMOUNT TO        OFFERING PRICE      AGGREGATE      REGISTRATION
       REGISTERED             BE REGISTERED         PER SHARE     OFFERING PRICE         FEE
<S>                        <C>                   <C>              <C>              <C>
Common Stock, $.001 par
 value...................  8,625,000 Shares (1)    $      (2)       $77,625,000      $26,767(3)
</TABLE>
 
(1)  Includes 1,125,000 shares that the Underwriters have the option to purchase
    to cover over-allotments, if any.
(2) Proposed  maximum offering  price per  share to  be supplied  by  amendment.
    Estimated  solely for purposes of  calculating the registration fee pursuant
    to Rule 457 under the Securities Act.
(3) Includes $13,793  previously paid and  an increased filing  fee of  $12,974,
    which is being paid concurrently with this filing.
 
    THE  REGISTRANT HEREBY  AMENDS THIS REGISTRATION  STATEMENT ON  SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A  FURTHER  AMENDMENT  WHICH SPECIFICALLY  STATES  THAT  THIS  REGISTRATION
STATEMENT  SHALL THEREAFTER BECOME EFFECTIVE IN  ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT  OF 1933  OR UNTIL  THE REGISTRATION  STATEMENT SHALL  BECOME
EFFECTIVE  ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                             CROSS-REFERENCE SHEET
           PURSUANT TO ITEM 501(B) OF REGULATION S-K SHOWING LOCATION
           IN PROSPECTUS OF INFORMATION REQUIRED BY ITEMS OF FORM S-1
 
<TABLE>
<CAPTION>
                  ITEM AND CAPTION IN FORM S-1                                    CAPTION IN PROSPECTUS
- ----------------------------------------------------------------  -----------------------------------------------------
<C>        <S>                                                    <C>
       1.  Forepart of the Registration Statement and Outside
            Front Cover Page of Prospectus......................  Outside Front Cover Page of Prospectus
       2.  Inside Front and Outside Back Cover Pages of
            Prospectus..........................................  Inside Front Cover Page of Prospectus; Outside Back
                                                                   Cover Page of Prospectus
       3.  Summary Information, Risk Factors and Ratio of
            Earnings to Fixed Charges...........................  Prospectus Summary; Risk Factors
       4.  Use of Proceeds......................................  Use of Proceeds
       5.  Determination of Offering Price......................  Outside Front Cover Page of Prospectus; Risk Factors;
                                                                   Underwriting
       6.  Dilution.............................................  Dilution; Shares Eligible for Future Sale
       7.  Selling Security Holders.............................  Not Applicable
       8.  Plan of Distribution.................................  Outside Front Cover Page of Prospectus; Underwriting
       9.  Description of Securities to be Registered...........  Outside Front Cover Page of Prospectus; Prospectus
                                                                   Summary; Description of Capital Stock; Shares
                                                                   Eligible for Future Sale
      10.  Interests of Named Experts and Counsel...............  Legal Matters; Experts
      11.  Information with Respect to the Registrant...........  Prospectus Summary; Risk Factors; The Company;
                                                                   Dividend Policy; Capitalization; Selected Historical
                                                                   Combined and Pro Forma Financial Data; Management's
                                                                   Discussion and Analysis of Financial Condition and
                                                                   Results of Operations; Business; Management;
                                                                   Principal Stockholders; Certain Transactions;
                                                                   Description of Capital Stock; Description of Certain
                                                                   Indebtedness; Financial Statements.
      12.  Disclosure of Commission Position on Indemnification
            for Securities Act Liabilities......................  Not Applicable.
</TABLE>
<PAGE>
INFORMATION   CONTAINED  HEREIN  IS  SUBJECT   TO  COMPLETION  OR  AMENDMENT.  A
REGISTRATION STATEMENT  RELATING TO  THESE SECURITIES  HAS BEEN  FILED WITH  THE
SECURITIES  AND EXCHANGE  COMMISSION. THESE SECURITIES  MAY NOT BE  SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR  TO THE TIME THE REGISTRATION STATEMENT  BECOMES
EFFECTIVE.  THIS  PROSPECTUS  SHALL  NOT  CONSTITUTE AN  OFFER  TO  SELL  OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE  SECURITIES
IN  ANY STATE IN WHICH SUCH OFFER,  SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.
<PAGE>
                                7,500,000 SHARES
 
                                     [LOGO]
                                  COMMON STOCK
 
    ALL OF THE SHARES OF COMMON STOCK OFFERED HEREBY ARE BEING SOLD BY  ADVANCED
RADIO  TELECOM CORP. ("ART" OR THE "COMPANY"). PRIOR TO THIS OFFERING, THERE HAS
BEEN NO PUBLIC  MARKET FOR  THE COMMON  STOCK OF  THE COMPANY.  IT IS  CURRENTLY
ESTIMATED  THAT  THE INITIAL  PUBLIC OFFERING  PRICE WILL  BE BETWEEN  $8.00 AND
$10.00 PER  SHARE. SEE  "UNDERWRITING" FOR  A DISCUSSION  OF THE  FACTORS TO  BE
CONSIDERED  IN DETERMINING THE  INITIAL PUBLIC OFFERING  PRICE. THE COMMON STOCK
HAS BEEN APPROVED FOR QUOTATION ON  THE NASDAQ NATIONAL MARKET UNDER THE  SYMBOL
"ARTT."
 
    CONCURRENTLY  WITH THE OFFERING  OF THE SHARES OF  COMMON STOCK (THE "COMMON
STOCK OFFERING"), THE COMPANY  IS OFFERING, PURSUANT  TO A SEPARATE  PROSPECTUS,
     UNITS (THE "UNITS"), EACH CONSISTING OF $1,000 PRINCIPAL AMOUNT AT MATURITY
OF  SENIOR  DISCOUNT NOTES  DUE 2006  (THE "NOTES")  AND                WARRANTS
(COLLECTIVELY, THE  "WARRANTS")  TO PURCHASE          SHARES  OF  COMMON  STOCK,
SUFFICIENT  TO GENERATE GROSS PROCEEDS OF $175,000,000 (THE "UNIT OFFERING" AND,
TOGETHER WITH  THE COMMON  STOCK OFFERING,  THE "OFFERINGS").  THE COMMON  STOCK
OFFERING IS CONDITIONED UPON THE CONSUMMATION OF THE UNIT OFFERING.
 
    AN  INVESTMENT IN THE COMMON STOCK OFFERED  HEREBY INVOLVES A HIGH DEGREE OF
RISK. SEE "RISK FACTORS" BEGINNING ON PAGE 9 FOR A DISCUSSION OF CERTAIN FACTORS
WHICH SHOULD BE CONSIDERED BY PROSPECTIVE INVESTORS IN EVALUATING AN  INVESTMENT
IN THE COMMON STOCK.
                               -----------------
 
THESE  SECURITIES HAVE NOT BEEN APPROVED  OR DISAPPROVED BY THE SECURITIES AND
  EXCHANGE COMMISSION  OR  ANY  STATE  SECURITIES  COMMISSION  NOR  HAS  THE
    SECURITIES  AND EXCHANGE COMMISSION OR  ANY STATE SECURITIES COMMISSION
     PASSED UPON  THE  ACCURACY  OR  ADEQUACY  OF  THIS  PROSPECTUS.  ANY
       REPRESENTATION   TO   THE   CONTRARY   IS   A   CRIMINAL  OFFENSE.
 
<TABLE>
<CAPTION>
                                              PRICE          UNDERWRITING        PROCEEDS TO
                                            TO PUBLIC        DISCOUNT (1)        COMPANY (2)
<S>                                     <C>                <C>                <C>
PER SHARE.............................          $                  $                  $
TOTAL (3).............................          $                  $                  $
</TABLE>
 
(1)  SEE  "UNDERWRITING"  FOR  INFORMATION  CONCERNING  INDEMNIFICATION  OF  THE
    UNDERWRITERS AND OTHER MATTERS.
 
(2) BEFORE DEDUCTING EXPENSES PAYABLE BY THE COMPANY ESTIMATED AT $       .
 
(3)  THE COMPANY HAS GRANTED TO THE  UNDERWRITERS A 30-DAY OPTION TO PURCHASE UP
    TO  1,125,000   ADDITIONAL  SHARES   OF  COMMON   STOCK  SOLELY   TO   COVER
    OVER-ALLOTMENTS,  IF ANY. IF THE UNDERWRITERS  EXERCISE THIS OPTION IN FULL,
    THE PRICE TO PUBLIC WILL  TOTAL $          , THE UNDERWRITING DISCOUNT  WILL
    TOTAL  $          AND  THE PROCEEDS TO  COMPANY WILL TOTAL  $          . SEE
    "UNDERWRITING."
 
    THE SHARES OF  COMMON STOCK ARE  OFFERED BY THE  SEVERAL UNDERWRITERS  NAMED
HEREIN  SUBJECT TO RECEIPT AND ACCEPTANCE BY  THEM AND SUBJECT TO THEIR RIGHT TO
REJECT ANY  ORDER IN  WHOLE OR  IN PART.  IT IS  EXPECTED THAT  DELIVERY OF  THE
CERTIFICATES  REPRESENTING SUCH SHARES WILL BE  MADE AGAINST PAYMENT THEREFOR AT
THE OFFICE OF MONTGOMERY SECURITIES ON OR ABOUT           , 1996.
                              -------------------
MONTGOMERY SECURITIES
            MERRILL LYNCH & CO.
                                                        DEUTSCHE MORGAN GRENFELL
 
                                          , 1996
<PAGE>
                         [INSIDE FRONT COVER GATE FOLD]
 
                      38 GHz TECHNOLOGY PROVIDES SUPERIOR
                BANDWIDTH PER CHANNEL WHICH ALLOWS SIGNIFICANTLY
                          FASTER DATA TRANSFER RATES.
 
                   [GRAPHIC DISPLAYING BANDWIDTH PER CHANNEL
                  OF FREQUENCIES BETWEEN 530 KHz AND 38 GHz.]
<PAGE>
                        [GRAPHIC DISPLAYING 38 GHz LINKS
                        BETWEEN METROPOLITAN FIBER RING,
              OFF-FIBER NET BUILDINGS AND ON-FIBER NET BUILDINGS.]
 
    IN CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR  EFFECT
TRANSACTIONS  WHICH STABILIZE  OR MAINTAIN  THE MARKET  PRICE OF  THE SECURITIES
OFFERED HEREBY AT LEVELS ABOVE THOSE  WHICH MIGHT OTHERWISE PREVAIL IN THE  OPEN
MARKET. SUCH STABILIZING, IF COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
<PAGE>
                               PROSPECTUS SUMMARY
 
    THE  FOLLOWING SUMMARY SHOULD BE READ  IN CONJUNCTION WITH, AND IS QUALIFIED
IN ITS ENTIRETY BY, THE MORE DETAILED INFORMATION, INCLUDING "RISK FACTORS"  AND
THE  HISTORICAL  AND  PRO  FORMA FINANCIAL  STATEMENTS  AND  THE  NOTES THERETO,
APPEARING  ELSEWHERE  IN  THIS  PROSPECTUS.  UNLESS  OTHERWISE  INDICATED,   ALL
INFORMATION IN THIS PROSPECTUS ASSUMES (I) THE COMPLETION OF THE PROPOSED MERGER
(THE "MERGER"), AS A CONDITION OF THE OFFERINGS, OF A WHOLLY-OWNED SUBSIDIARY OF
ADVANCED  RADIO TECHNOLOGIES  CORPORATION ("ART")  WITH AND  INTO ADVANCED RADIO
TELECOM CORP.  ("TELECOM"),  (II)  THE  CONVERSION  (THE  "CONVERSION")  OF  ALL
OUTSTANDING  SHARES OF PREFERRED STOCK OF TELECOM INTO SHARES OF COMMON STOCK OF
TELECOM PRIOR  TO  THE MERGER,  (III)  THE  AMENDMENT OF  ART'S  CERTIFICATE  OF
INCORPORATION  TO CHANGE  ITS NAME TO  "ADVANCED RADIO TELECOM  CORP.," (IV) THE
29,450.16 FOR ONE SPLIT  OF THE COMMON  STOCK EFFECTED IN JUNE  1996 AND (V)  NO
EXERCISE  OF  THE  UNDERWRITERS'  OVER-ALLOTMENT  OPTION  IN  THE  COMMON  STOCK
OFFERING. FOLLOWING THE  MERGER, TELECOM  WILL BE A  WHOLLY-OWNED SUBSIDIARY  OF
ART.  AS USED IN THIS PROSPECTUS, THE  TERMS "ART" OR THE "COMPANY" REFER EITHER
TO ART ON A STAND-ALONE BASIS OR ON A COMBINED BASIS WITH TELECOM AS THE CONTEXT
MAY REQUIRE. SEE "THE  COMPANY." SEE "GLOSSARY" FOR  THE DEFINITIONS OF  CERTAIN
TERMS AND ACRONYMS USED HEREIN.
 
                                  THE COMPANY
 
    Advanced  Radio  Telecom Corp.  ("ART" or  the "Company")  provides wireless
broadband   telecommunications   services    using   point-to-point    microwave
transmissions  in the 37.0 to 40.0 gigahertz  portion of the radio spectrum ("38
GHz"). The Company is seeking to address the growing demand for high speed, high
capacity digital  telecommunications  services  on  the  part  of  business  and
government  end users who require cost effective, high bandwidth local access to
voice, video,  data  and  Internet  services. Upon  completion  of  its  pending
acquisition  of  129 38  GHz wireless  broadband authorizations  (the "CommcoCCC
Assets") from CommcoCCC, Inc.  ("CommcoCCC"), the Company will  own or manage  a
total  of 237  authorizations granted  by the  Federal Communications Commission
("FCC") covering an  aggregate population  of approximately 143  million in  169
U.S. markets. ART's footprint will allow it to provide 38 GHz wireless broadband
services  in 47 of the top 50 markets  and 82 of the top 100 markets. Presently,
the Company  owns or  manages  108 authorizations  (exclusive of  the  CommcoCCC
Assets)  that  allow it  to provide  38  GHz wireless  broadband services  in 89
markets.  See  "Risk   Factors  --   Risk  of   Non-Consummation  of   CommcoCCC
Acquisition,"   "Business   --   38   GHz   Wireless   Broadband   Licenses  and
Authorizations" and "--  Agreements Relating to  Licenses and Authorizations  --
CommcoCCC Acquisition."
 
    The ability to access and distribute information quickly has become critical
to   business  and   government  users   of  telecommunications   services.  The
proliferation  of  local  area  networks  ("LANs"),  rapid  growth  of  Internet
services,  rising demand for video teleconferencing and other demand factors are
significantly increasing the volume of broadband telecommunications traffic. The
inability of the existing infrastructure to meet this demand is creating a "last
mile" bottleneck in  the copper wire  networks of the  incumbent local  exchange
carriers  ("LECs").  This  increasing  demand,  together  with  changes  in  the
regulatory environment, are  creating an  opportunity to  offer cost  effective,
high  capacity last mile access using  both wireline and wireless solutions. See
"Business -- Telecommunications Industry Overview."
 
38 GHZ TECHNOLOGY
 
    The Company is positioned to solve the need for broadband last mile  access,
linking  end  users  to competitive  access  providers  ("CAPs"), inter-exchange
carriers ("IXCs"),  cellular and  mobile radio  service providers  and  Internet
service  providers  ("ISPs") using  38  GHz technology.  The  Company's wireless
broadband services are engineered to  provide 99.999% availability, with  better
than  a 10-13 (unfaded) bit  error rate. This level  of availability exceeds the
performance of copper based networks and is a viable alternative to fiber  optic
based  networks. See  "Business -- The  ART Solution." In  addition, the Company
believes that  ART's  last  mile  solution is  competitively  priced  with  most
broadband wireline solutions. See "Business -- 38 GHz Technology" and "--The ART
Solution."  The 38 GHz band provides  for the following additional advantages as
compared to other spectrum bands and wireline alternatives:
 
                                       3
<PAGE>
    - HIGH DATA TRANSFER RATES.  The total amount of  bandwidth for each 38  GHz
     channel  is  100 MHz,  which  exceeds the  bandwidth  of any  other present
     terrestrial  wireless  channel  allotment   and  supports  full   broadband
     capability. For example, one 38 GHz DS-3 link at 45 Mbps today can transfer
     data  at a rate which  is over 1,500 times the  rate of the fastest dial-up
     modem currently in  use (28.8  Kbps) and  over 350  times the  rate of  the
     fastest  integrated services digital network ("ISDN") line currently in use
     (128  Kbps).  In  addition  to   accommodating  standard  voice  and   data
     requirements,  45 Mbps data  transmission rates allow  end users to receive
     real time, full motion video and 3-D graphics at their workstations and  to
     utilize highly interactive applications on the Internet and other networks.
 
    - SIGNIFICANT CHANNEL CAPACITY. Because 38 GHz radio emissions have a narrow
     beam  width, a relatively short range  and in many instances the capability
     to intersect without  creating interference, 38  GHz service providers  can
     efficiently   reuse  their  bandwidth  within   a  licensed  area,  thereby
     increasing the number of customers to which such services can be  provided.
     Management  believes  that by  using technology  currently employed  by the
     Company it can serve virtually all of the immediately addressable market in
     its market areas.
 
    - RAPID  DEPLOYMENT. 38  GHz technology  can be  deployed considerably  more
     rapidly  than wireline and other wireless technologies, generally within 72
     hours after  obtaining access  to  customer premises.  In contrast  to  the
     relative  ease of installing a 38 GHz transmission link, extending fiber or
     copper-based networks to reach new customers requires significant time  and
     expense.  In addition, unlike providers of point-to-point microwave service
     in other spectrum bands, a 38 GHz license holder can install and operate as
     many transmission links  as it can  engineer in the  licensed area  without
     obtaining  additional  approvals  from  the  FCC.  This  is  a  substantial
     advantage over other portions of the microwave radio spectrum that must  be
     licensed on a link-by-link basis following frequency coordination, which in
     total can take from three to five months.
 
    -  EASE OF INSTALLATION. The  equipment used for point-to-point applications
     in 38 GHz  (i.e., antennae,  transceivers and digital  interface units)  is
     smaller,  less obtrusive  and less expensive  than that  used for microwave
     equipment applications at lower frequencies, making it less susceptible  to
     zoning restrictions. In addition, 38 GHz equipment can be easily redeployed
     to meet changing customer requirements.
 
    -  ADDITIONAL  ADVANTAGES  OVER  OTHER  PORTIONS  OF  RADIO  SPECTRUM.    At
     frequencies above 38 GHz, point-to-point applications become less practical
     because attenuation increases and the maximum distance between transceivers
     accordingly decreases. Additionally, the FCC has specified the use of  many
     portions  of the spectrum for  applications other than point-to-point, such
     as satellite and wireless cable services, and, accordingly, these  portions
     of   the  radio  spectrum  often   are  not  available  for  point-to-point
     applications. Finally,  38 GHz  has  characteristics which  provide  better
     signal  quality and performance in inclement  weather than those offered in
     other portions of the radio spectrum.
 
BUSINESS STRATEGY
 
    ART began providing 38 GHz wireless broadband services in the fourth quarter
of 1995 and has generated only nominal revenues from such services to date.  The
Company is seeking to capitalize on its broad footprint of 38 GHz authorizations
to  become a leading provider of wireless broadband solutions to a diverse group
of traditional and emerging telecommunications  service providers and end  users
of telecommunications services. See "Business -- Business Strategy." The Company
plans   to  implement  the  following  strategic  initiatives  to  achieve  this
objective:
 
    - EXPLOIT SPECTRUM POSITION IN KEY  MARKETS. Upon completion of its  pending
     acquisition of the CommcoCCC Assets, the Company will own or manage a total
     of  237  authorizations  that will  allow  it  to provide  38  GHz wireless
     broadband services  in 169  U.S.  markets. The  Company currently  owns  or
     manages  108 authorizations (exclusive of  the CommcoCCC Assets) that allow
     it to provide 38 GHz wireless broadband services in 89 markets, 73 of which
     are owned by the Company and the  remaining 35 of which are managed by  the
     Company through the Company's
 
                                       4
<PAGE>
     interests  in or arrangements with other  companies. The Company has agreed
     to acquire all of  the authorizations which it  currently manages but  does
     not  own. These spectrum assets provide  the Company with the foundation on
     which to  create  a  large  scale commercial  system  of  38  GHz  wireless
     broadband  operations.  As  of June  28,  1996, the  Company  was operating
     revenue-generating, wireless  broadband links  in  15 cities.  The  Company
     plans  to continue  to build  out its  infrastructure and  to intensify its
     marketing effort in its market areas in order to exploit the value inherent
     in its spectrum assets. The Company may seek to acquire additional spectrum
     rights in  new and  existing  markets in  order  to expand  its  geographic
     footprint  or enhance its services. See "Business -- Agreements Relating to
     Licenses and Authorizations."
 
    - MARKET  INITIALLY AS  A CARRIER'S  CARRIER. The  Company's initial  target
     customers  include CAPs, IXCs, cellular  and mobile radio service providers
     and ISPs. The Company's wireless  broadband services enable CAPs to  extend
     their broadband services to locations where it is either not cost-efficient
     or  too  difficult to  extend  their fiber  optic  network due  to physical
     limitations, franchise fees or  other restrictions. The Company's  services
     may  also be attractive  to certain LECs, which  generally do not currently
     have  broadband  networks  capable  of  reaching  the  majority  of   their
     customers.  The Company has entered into a strategic distribution agreement
     (the "Ameritech  Strategic Distribution  Agreement") with  Ameritech  Corp.
     ("Ameritech")  for delivery  of the  Company's wireless  broadband services
     throughout Ameritech's  midwest  operating  region and  for  certain  large
     customers  located  outside  its  region.  The  Company  currently provides
     services  to  Ameritech,  Bell  Atlantic  NYNEX  Mobile,  UUNet,   Electric
     Lightwave,   NEXTLINK,  American  Personal  Communications,  American  Show
     Management, Capital Area Internet Service, Brooks Fiber Communications  and
     Western   Wireless,   among  others.   See   "Business  --   Customers  and
     Applications." As regulatory and competitive  conditions permit and as  the
     Company's  customer base and  market presence develop,  the Company expects
     that its market focus will expand  from a wholesale "carrier's carrier"  to
     include provision of services directly to commercial end users.
 
    -  PURSUE  OPPORTUNITIES TO  PROVIDE VALUE-ADDED  SERVICES. The  Company has
     identified and  plans to  pursue additional  market niches  with  immediate
     needs  for reliable, high bandwidth last mile access services. For example,
     the market for  Internet services  urgently requires  broadband "pipes"  to
     facilitate  high  speed  access for  corporate  users, and  the  Company is
     pursuing agreements to package  its 38 GHz solutions  with the services  of
     leading   ISPs.   Other   potential   value-added   uses   include  desktop
     videoconferencing,  high  resolution   imaging  for   healthcare  and   law
     enforcement  applications and video on demand.  The Company may also decide
     to offer switched-based services  to end users who  desire a single  source
     telecommunications solution.
 
    -  MAINTAIN  TECHNOLOGY LEADERSHIP  IN SPECTRUM  MANAGEMENT. The  Company is
     currently developing proprietary site selection and network design software
     which it believes will provide for faster site development at a lower cost.
     In addition, through the Company's internal technology development efforts,
     as well as on-going participation in equipment manufacturers' research  and
     development  activities, the  Company is  seeking to  achieve a competitive
     advantage through proprietary methods designed to increase the capacity and
     quality of its networks.
 
    - ESTABLISH AND EXPAND KEY STRATEGIC ALLIANCES. The Company has  established
     and  will seek to continue to  establish key strategic alliances with major
     service  providers,  equipment   manufacturers,  systems  integrators   and
     enhanced  service  providers.  Ameritech  owns  a  5.5%  beneficial  equity
     interest in the Company as  of June 28, 1996  (4.3% after giving effect  to
     the  Common  Stock  Offering)  and  entered  into  the  Ameritech Strategic
     Distribution Agreement in April 1996. The Company also has agreements  with
     Harris  Corporation, Farinon Division ("Harris") for marketing ART's 38 GHz
     services to PCS providers and with GTE Corporation for installation,  field
     servicing  and network monitoring.  In addition, the  Company is seeking to
     develop relationships with a number of equipment manufacturers focusing  on
     38 GHz technology development, wireless broadband standards and joint sales
     efforts.  The Company plans to utilize  these strategic alliances to bundle
     its services  with  those  of  its partners,  to  provide  for  alternative
     distribution channels and to gain access to technological advancements. See
     "Business -- Strategic Alliances."
 
                                       5
<PAGE>
                           THE COMMON STOCK OFFERING
 
<TABLE>
<S>                                            <C>
Common Stock offered by the Company..........  7,500,000 shares
Common Stock outstanding after the
 offering....................................  37,586,498 shares (1)
Use of proceeds..............................  To  fund capital  expenditures, including the
                                               purchase of equipment and the acquisition  of
                                               certain spectrum rights, to repay outstanding
                                               indebtedness   and   for   general  corporate
                                               purposes, including the funding of  operating
                                               cash  flow shortfalls, technology development
                                               and the  acquisition of  additional  spectrum
                                               rights and, potentially, related businesses.
Nasdaq National Market symbol................  ARTT
</TABLE>
 
- ------------------------------
 
(1)  Assumes completion of  the Merger and the  Conversion. Excludes (i) 877,136
    shares of Common Stock subject to  the Ameritech Warrant (as defined),  (ii)
    1,100,000  shares  of  Common  Stock  subject  to  the  Bridge  Warrants (as
    defined), (iii)  325,000 shares  of Common  Stock subject  to the  Indemnity
    Warrants  (as defined),  (iv) 1,664,732  shares of  Common Stock  subject to
    outstanding options under the Equity Incentive Plan (as defined), (v) 28,000
    shares of  Common Stock  anticipated to  be subject  to outstanding  options
    under  the Directors Plan  (as defined) upon  consummation of the Offerings,
    (vi) 50,000 shares subject to the CommcoCCC Warrants (as defined) and  (vii)
    16,500,000   shares  issuable   upon  the  consummation   of  the  CommcoCCC
    Acquisition (as defined). As of June 28, 1996, an additional 835,268  shares
    of Common Stock were available for issuance under the Equity Incentive Plan.
    As  of the date of  this Prospectus, an additional  172,000 shares of Common
    Stock were available  for issuance  under the Directors  Plan. See  "Certain
    Transactions"  and "Management -- Stock Option Plans." In addition, does not
    give effect to the exercise of (i) the over-allotment option granted to  the
    Underwriters  by  the Company  in  the Common  Stock  Offering and  (ii) the
    Warrants. See "Underwriting."
 
                              CONCURRENT OFFERING
 
    Concurrently with  the  Common  Stock Offering,  the  Company  is  offering,
pursuant to a separate prospectus,    Units, each consisting of $1,000 principal
amount at maturity of Notes and
Warrants  to purchase       shares of Common Stock of the Company, sufficient to
generate gross proceeds of $175,000,000 (the "Unit Offering" and, together  with
the Common Stock Offering, the "Offerings"). The Warrants, when exercised, would
entitle  the holders thereof to purchase shares  of Common Stock representing  %
of the Common Stock of the Company on a fully diluted basis after giving  effect
to the Offerings. The Common Stock Offering is conditioned upon the consummation
of the Unit Offering. See "Description of Certain Indebtedness."
 
                                  RISK FACTORS
 
    An  investment in the Common Stock offered  hereby involves a high degree of
risk. See "Risk Factors" beginning on page 9 for a discussion of certain factors
which should be considered by prospective investors in evaluating an  investment
in the Common Stock.
 
                                       6
<PAGE>
              SUMMARY HISTORICAL AND PRO FORMA FINANCIAL DATA (1)
 
<TABLE>
<CAPTION>
                                  YEAR ENDED DECEMBER 31, 1995                     THREE MONTHS ENDED MARCH 31, 1996
                       --------------------------------------------------  --------------------------------------------------
                        HISTORICAL                          PRO FORMA       HISTORICAL                          PRO FORMA
                       COMBINED (2)    PRO FORMA (3)     AS ADJUSTED (4)   COMBINED (2)    PRO FORMA (3)     AS ADJUSTED (4)
                       -------------  ----------------  -----------------  -------------  ----------------  -----------------
<S>                    <C>            <C>               <C>                <C>            <C>               <C>
STATEMENT OF
 OPERATIONS DATA:
Operating revenue....   $     5,793     $      5,793      $      5,793      $     9,620     $      9,620      $       9,620
Non-cash compensation
 expense.............     1,089,605        1,089,605         1,089,605        7,221,000        7,221,000          7,221,000
Depreciation and
 amortization........        15,684           15,684         5,418,452           89,279           89,279          1,439,971
Interest, net........       121,986        1,974,275        23,931,008          151,145          528,739          5,989,300
Net loss.............     3,234,843        5,087,132        30,609,692       10,694,588       11,092,182         17,444,199
Pro forma net loss
 per share of Common
 Stock (5)...........            --     $       0.16      $       0.55               --     $       0.35      $        0.31
Pro forma weighted
 average number of
 shares of Common
 Stock outstanding
 (5).................            --       31,651,605        55,651,605               --       31,651,605         55,651,605
 
OTHER FINANCIAL DATA:
EBITDA (6)...........   $(1,936,141)    $ (1,936,141)     $ (1,936,141)     $(2,156,893)    $ (2,156,893)     $  (2,156,893)
Capital
 expenditures........     3,585,144        3,585,144         3,585,144        2,861,241        2,861,241          2,861,241
</TABLE>
 
<TABLE>
<CAPTION>
                                                 AS OF
                                           DECEMBER 31, 1995                  AS OF MARCH 31, 1996
                                           ------------------  --------------------------------------------------
                                               HISTORICAL       HISTORICAL                          PRO FORMA
                                              COMBINED (2)     COMBINED (2)    PRO FORMA (3)     AS ADJUSTED (4)
                                           ------------------  -------------  ----------------  -----------------
<S>                                        <C>                 <C>            <C>               <C>
BALANCE SHEET DATA:
Working capital surplus (deficit)........     $ (3,008,510)     $(1,128,130)    $  1,116,870     $   214,516,870
Property and equipment, net..............        3,581,561        6,380,895        6,380,895           6,380,895
FCC licenses.............................        4,235,734        4,235,734        4,235,734         216,110,734
Total assets.............................        9,876,559       15,036,337       20,432,236         448,589,961
Short-term debt..........................               --               --        2,975,000                  --
Long-term debt, including current
 portion.................................        6,450,000        5,483,082        7,394,521         163,211,439
Total stockholders' equity (deficit).....         (312,860)       5,339,738        5,849,198         230,675,005
</TABLE>
 
- ------------------------------
 
(1)  The unaudited summary historical and  pro forma financial data were derived
    from, and  should  be  read  in  conjunction  with,  the  audited  financial
    statements  of ART and Telecom and  the notes thereto, the unaudited interim
    condensed financial statements of ART and Telecom and the notes thereto, and
    the unaudited pro forma  condensed financial statements  of the Company  and
    the  notes thereto, included elsewhere in this Prospectus. The pro forma and
    pro forma as adjusted financial data are not necessarily indicative of  what
    the actual financial position and results of operations of the Company would
    have  been as of and for  the three months ended March  31, 1996 and for the
    year ended December 31, 1995, nor do they purport to represent the Company's
    future financial position and results of operations.
 
(2) The unaudited summary financial data under the caption "Historical Combined"
    are presented as if the historical  financial statements of ART and  Telecom
    had  been  combined  and reflect  (i)  the elimination  of  transactions and
    balances  between  ART  and  Telecom  and  (ii)  the  elimination  of  ART's
    investment in Telecom and Telecom's investment in ART.
 
(3)  The  unaudited summary  financial data  under the  caption "Pro  Forma" are
    presented as if the following transactions had occurred as of the  beginning
    of  the respective  periods for the  Statement of Operations  Data and Other
    Financial Data and as of the balance sheet date for the Balance Sheet  Data:
    (i)  the  March  8,  1996  issuance of  the  Bridge  Notes  (as  defined) in
    connection with the Bridge Financing (as defined); (ii) the receipt of  $2.2
    million  in  cash  proceeds from  the  issuance  of the  Equipment  Note (as
    defined) and Indemnity Warrants in  connection with the Equipment  Financing
    (as  defined), after deducting related fees  and expenses of $225,000, (iii)
    the receipt of $3.0  million in cash proceeds  from the CommcoCCC Notes  (as
    defined)  and CommcoCCC Warrants in  connection with the CommcoCCC Financing
    (as defined);  (iv)  the  Conversion;  and (v)  the  Merger,  including  the
    issuance of Common Stock to Telecom stockholders and the cancellation of all
    outstanding Telecom common stock. See "Certain Transactions."
 
(4)  The  unaudited  summary financial  data  under  the caption  "Pro  Forma As
    Adjusted" are presented as if the transactions referred to in (3) above  and
    the  following  transactions  had  occurred  as  of  the  beginning  of  the
    respective periods for the Statement of Operations Data and Other  Financial
    Data  and as of the  balance sheet date for the  Balance Sheet Data: (i) the
 
                                       7
<PAGE>
    sale by  the Company  of 7,500,000  shares of  Common Stock  offered in  the
    Common  Stock Offering based on an  assumed initial public offering price of
    $9.00 per share and the Units offered in the Unit Offering assuming,  $175.0
    million  of gross proceeds, and, in each case, after deducting the estimated
    underwriting  discount  and   offering  expenses,  (ii)   the  receipt   and
    application  of the net proceeds therefrom to repay the Bridge Notes and the
    CommcoCCC Notes and to  acquire the 50% ownership  interest of ART West  (as
    defined)  held by Extended (as defined) for $6.0 million in cash and the DCT
    Assets (as  defined) for  $3.6 million  in cash  and (iii)  the issuance  of
    16,500,000  shares of Common Stock based upon  an assumed value of $9.00 per
    share in connection with the CommcoCCC Acquisition (as defined). See "Use of
    Proceeds."
 
(5) Pro forma net loss  per share is computed based  on the loss for the  period
    divided by the weighted average number of shares of Common Stock outstanding
    during  the period, including the Conversion, the Merger and the issuance of
    potentially dilutive  instruments  issued  within  one  year  prior  to  the
    Offerings at exercise prices below the assumed initial public offering price
    of  $9.00 per share.  Pro forma as  adjusted net loss  per share include the
    items above noted plus the issuance  of 7,500,000 shares of Common Stock  in
    the  Common Stock Offering  and the issuance of  16,500,000 shares of Common
    Stock in  connection  with  the  CommcoCCC  Acquisition.  In  measuring  the
    dilutive effect, the treasury stock method was used.
 
(6)  EBITDA means loss before interest expense, income tax expense, depreciation
    and amortization expense, non-cash compensation expense and non-cash  market
    development  expense. Information with respect  to EBITDA is included herein
    because a similar measure  will be used in  the Indenture (as defined)  with
    respect  to the computation of certain  covenants. EBITDA is not intended to
    represent cash flows from operating activities, as determined in  accordance
    with  generally accepted accounting principles, nor has it been presented as
    an alternative to operating income as an indicator of operating  performance
    and  should not  be considered as  a substitute for  measures of performance
    prepared in accordance with generally accepted accounting principles.
 
                                       8
<PAGE>
                                  RISK FACTORS
 
    IN  ADDITION TO THE OTHER INFORMATION IN THIS PROSPECTUS, THE FOLLOWING RISK
FACTORS SHOULD BE CONSIDERED CAREFULLY IN EVALUATING AN INVESTMENT IN THE COMMON
STOCK OFFERED HEREBY.
 
                         BUSINESS AND REGULATORY RISKS
 
LIMITED OPERATIONS; HISTORY OF NET LOSSES
 
    Although the Company's business commenced in 1993, the Company has generated
only nominal revenues from operations to date. The Company's primary  activities
have  focused  on  the acquisition  of  wireless authorizations,  the  hiring of
management and other key personnel, the  raising of capital, the acquisition  of
equipment  and the development  of operating systems.  As of June  28, 1996, the
Company was operating revenue-generating, wireless broadband links in 15  cities
using  38  GHz  technology.  Prospective investors  have  limited  operating and
financial data  about  the Company  upon  which to  base  an evaluation  of  the
Company's  performance and an investment in the Common Stock offered hereby. The
Company's ability to  provide commercial service  on a widespread  basis and  to
generate positive operating cash flow will depend on its ability to, among other
things,  (i)  deploy its  38 GHz  technology on  a market-by-market  basis, (ii)
attract and retain an adequate customer base, (iii) develop its operational  and
support  systems  and (iv)  acquire appropriate  sites  for its  operations. See
"Business -- Business Strategy." Given the Company's limited operating  history,
there  can be  no assurance  that it  will be  able to  achieve these  goals, to
develop a sufficiently  large revenue-generating customer  base, to service  its
indebtedness or to compete successfully in the telecommunications industry.
 
    The development of the Company's business and the deployment of its services
and systems will require significant capital expenditures, a substantial portion
of  which  will  need  to  be incurred  before  the  realization  of significant
revenues. Together  with  the  associated  start-up  operating  expenses,  these
capital expenditures will result in negative cash flow until an adequate revenue
generating  customer base is established. On a historical combined basis for the
year ended December 31,  1995 and the three-month  period ended March 31,  1996,
the Company reported net losses of $3.2 million and $10.7 million, respectively.
On  a  combined historical  basis, from  inception through  March 31,  1996, the
Company reported net losses  of $14.1 million. The  financial statements of  the
Company included in this Prospectus have been prepared on a going concern basis.
See  "Management's Discussion and Analysis of Financial Condition and Results of
Operations." Through  1997,  the  Company currently  expects  to  incur  capital
expenditures of approximately $100.0 million as the development and expansion of
its  wireless  broadband business  continues.  The Company  expects  to generate
significant operating losses for at least  the next several years. There can  be
no assurance that the Company will develop a revenue-generating customer base or
will achieve or sustain profitability in the future.
 
EMERGING MARKET; UNCERTAIN ACCEPTANCE OF 38 GHZ SERVICES
 
    The  Company  has  only  recently begun  to  market  its  wireless broadband
services to potential customers and has generated only nominal revenues to date.
The provision of wireless broadband services on 38 GHz frequencies represents an
emerging sector  of the  telecommunications industry,  and the  demand for  such
services is uncertain. Market acceptance may be adversely affected by historical
perceptions  of the  unreliability and  lack of  security of  previous microwave
technologies using  frequencies other  than  38 GHz.  See  "Business --  38  GHz
Technology." There can be no assurance that substantial markets will develop for
38  GHz wireless broadband services,  or, if such markets  were to develop, that
the  Company   would   be   able   to  attract   and   maintain   a   sufficient
revenue-generating customer base or operate profitably.
 
    The Company's success in providing wireless broadband services is subject to
certain  factors beyond  the Company's  control. These  factors include, without
limitation, changes in  general and local  economic conditions, availability  of
equipment,  changes in telecommunications service rates charged by other service
providers, changes in  the supply  and demand for  wireless broadband  services,
competition from
 
                                       9
<PAGE>
wireline  and wireless operators in the same market area, changes in the federal
and state  regulatory  schemes affecting  the  operation of  wireless  broadband
systems (including the enactment of new statutes and the promulgation of changes
in  the interpretation or enforcement of  existing or new rules and regulations)
and changes in  technology that  have the  potential of  rendering obsolete  the
Company's wireless broadband equipment. In addition, the extent of the potential
demand  for wireless broadband services in  the Company's market areas cannot be
estimated with certainty. There can  be no assurance that  one or more of  these
factors will not have an adverse effect on the Company's financial condition and
results of operations.
 
RISK OF NON-CONSUMMATION OF COMMCOCCC ACQUISITION
 
    On  July  3, 1996,  the Company  entered into  an agreement  (the "CommcoCCC
Agreement") to  acquire  the CommcoCCC  Assets  from CommcoCCC  (the  "CommcoCCC
Acquisition")  in exchange for 16,500,000 shares  of Common Stock. See "Business
- -- Agreements Relating to Licenses and Authorizations -- CommcoCCC Acquisition."
The CommcoCCC Acquisition is subject to various conditions including receipt  of
FCC  and other approvals, receipt by CommcoCCC  of an opinion as to the tax-free
nature of the  transaction, consummation  of the Offerings  on terms  reasonably
satisfactory  to  CommcoCCC, minimum  population  coverage requirements  for the
authorizations of ART and CommcoCCC, accuracy of representations and  warranties
except for breaches that do not have in the aggregate a material adverse effect,
no  pending  or  threatened  material  litigation  and  other  customary closing
conditions. There  can  be  no  assurance  that  all  such  conditions  will  be
satisfied.  See "Business -- Agreements  Relating to Licenses and Authorizations
- -- CommcoCCC Acquisition." In  particular, to obtain  FCC approval, the  Company
will  need  to make  certain "anti-trafficking"  showings  and may  need certain
waivers or consents from the FCC. The FCC may be unwilling to grant its approval
or may grant  its approval  subject to  conditions that  may be  adverse to  the
Company.  There can be no assurance that the FCC will grant such waivers or that
there would not  be substantial  delays in  its doing  so. If  the Company  were
unable  to  complete the  CommcoCCC Acquisition  for  any reason,  the Company's
footprint would be considerably  smaller than planned  and the Company's  growth
could be limited.
 
COMPETITION
 
    The  telecommunications services industry is highly competitive. The Company
has only recently begun to market  its wireless broadband services to  potential
customers and is currently providing services on a limited basis. In each market
area  in  which  the Company  is  authorized  to provide  services,  the Company
competes or will compete with several other service providers and  technologies.
The  Company expects  to compete  primarily on  the basis  of wireless broadband
service features,  quality,  price,  reliability,  customer  service  and  rapid
response to customer needs. The Company faces significant competition from other
38  GHz  providers  and incumbent  LECs,  such  as the  Regional  Bell Operating
Companies ("RBOCs"). The Company  may also compete  with CAPs, cable  television
operators,  electric  utilities,  LECs  operating  outside  their  current local
service areas and IXCs. There can be no assurance that the Company will be  able
to   compete  effectively  in  any  of   its  market  areas.  See  "Business  --
Competition."
 
    COMPETITION FROM 38 GHZ  SERVICE PROVIDERS.   The Company faces  competition
from  other  38  GHz service  providers,  such as  WinStar  Communications, Inc.
("WinStar") and BizTel Communications, Inc. ("BizTel"), within its market areas.
In many cases, one or both of  these service providers hold licenses to  operate
in  other portions  of the 38  GHz band  in geographic areas  which encompass or
overlap the Company's market  areas. In certain of  the Company's market  areas,
other 38 GHz service providers may have a longer history of operations, a larger
geographic  footprint  or  substantially greater  financial  resources  than the
Company. WinStar commenced its 38 GHz operations approximately one year prior to
the Company, has raised significant  capital and has the competitive  advantages
inherent  in being the first  to market 38 GHz  services. In addition to WinStar
and BizTel, at least one other substantial entity, Milliwave L.P. ("Milliwave"),
and several  dozen smaller  ones  have been  granted  38 GHz  authorizations  in
geographic  regions in which the Company  plans to operate. WinStar has recently
entered into a
 
                                       10
<PAGE>
definitive agreement  with Milliwave  to acquire  Milliwave's 38  GHz  licenses,
subject  to FCC  approval, and  has agreed to  manage such  licenses pending the
consummation of  such  acquisition.  Due  to the  relative  ease  and  speed  of
deployment   of  38  GHz  technology,  the  Company  could  face  intense  price
competition and competition  for customers  (including other  telecommunications
service providers) from other 38 GHz service providers.
 
    The Company also faces potential competition from new entrants to the 38 GHz
market,  including LECs and other leading telecommunications companies. The NPRM
(as defined) contemplates an auction  of certain spectrum assets, including  the
lower fourteen proposed 100 MHz channels (which are similar to those used by the
Company)  and four proposed 50  MHz channels in the  38 GHz spectrum band, which
have not  been  previously available  for  commercial use.  See  "--  Government
Regulation."  The grant of  additional authorizations by  the FCC in  the 38 GHz
band, or  other portions  of the  spectrum with  similar characteristics,  could
result  in  increased  competition.  The Company  believes  that,  assuming that
additional channels  are made  available  as proposed  by the  NPRM,  additional
entities  having greater resources than the Company could acquire authorizations
to provide 38 GHz  services. See "Business --  Government Regulation --  Federal
Regulation -- FCC Rulemaking."
 
    COMPETITION  FROM  INCUMBENT  LECS.    The  Company  also  faces significant
competition from incumbent  LECs, irrespective  of whether they  provide 38  GHz
services.  Incumbent LECs have long-standing relationships with their customers,
generally own  significant  PCS  or  cellular  assets,  have  the  potential  to
subsidize  competitive services with  revenues from a  variety of businesses and
benefit from favorable  federal and state  policies and regulations.  Regulatory
decisions  and recent  legislation, such as  the Telecommunications  Act of 1996
(the "Telecommunications Act"), have partially deregulated the
telecommunications industry and reduced barriers  to entry into new segments  of
the industry. In particular, the Telecommunications Act, among other things, (i)
enhances  local exchange competition by  preempting laws prohibiting competition
in the  local exchange  market, by  requiring  LECs to  provide fair  and  equal
standards  for  interconnection  and  by  requiring  incumbent  LECs  to provide
unbundling of services and (ii) permits an RBOC to compete in the interLATA long
distance service market once certain competitive characteristics emerge in  such
RBOC's  service  area.  The Company  believes  that this  trend  towards greater
competition will continue to provide opportunities for broader entrance into the
local exchange markets. However, as LECs face increased competition,  regulatory
decisions  are likely to provide them  with increased pricing flexibility, which
in turn may  result in increased  price competition. There  can be no  assurance
that such increased price competition will not have a material adverse effect on
the Company's results of operations.
 
    OTHER  COMPETITORS.  The Company may compete  with CAPs for the provision of
last mile access and additional services  in most of its market areas.  However,
the  Company believes that  many CAPs may  utilize 38 GHz  transmission links to
augment their own service offerings to IXCs and end users, and that the  Company
is  well positioned to provide such 38  GHz services to CAPs. However, there can
be no assurance that  CAPs will utilize  the Company's 38  GHz services or  that
CAPs  will not  seek to  acquire their  own 38  GHz licenses  or use  the 38 GHz
licenses of other licensees. Furthermore, the ability of CAPs to compete in  the
local  exchange market is limited by regulations relating to number portability,
dialing  parity  and  reasonable  interconnection.  The  Telecommunications  Act
requires  the FCC and the  states to implement regulations  that place CAPs on a
more equal  competitive footing  with  LECs. To  the  extent these  changes  are
implemented,  CAPs may be  able to compete more  effectively with LECs. However,
there can be no  assurance that CAPs  or 38 GHz service  providers, such as  the
Company,  will be  able to  compete effectively for  the provision  of last mile
access and other services.
 
    The Company  may  also  face competition  from  cable  television  operators
deploying  cable modems, which provide high speed data capability over installed
coaxial  cable  television  networks.  Although  cable  modems  are  not  widely
available  currently, the Company  believes that the  cable industry may support
the deployment of cable  modems to residential  cable customers through  methods
such  as price subsidies. Notwithstanding the cable industry's interest in rapid
deployment of cable modems, the Company
 
                                       11
<PAGE>
believes that in order to provide broadband capacity to a significant number  of
business  and  government  users  cable  operators  will  be  required  to spend
significant time and capital in order to upgrade their existing networks to  the
next generation of hybrid fiber coaxial network architecture. However, there can
be  no assurance that cable television operators  will not emerge as a source of
competition to the Company.
 
    The  Company  may  also  face  competition  from  electric  utilities,  LECs
operating  outside their current local service  areas, IXCs and other providers.
These entities provide transmission services using technologies which may  enjoy
a  greater degree of market acceptance than 38 GHz wireless broadband technology
in the provision of last mile  broadband services. In addition, the Company  may
face  competition  from  new market  entrants  using wireless,  fiber  optic and
enhanced copper based networks to provide local service and from wireless  cable
providers  and other  service providers operating  in frequencies  other than 38
GHz.
 
    Many of  the Company's  competitors  have long-standing  relationships  with
customers  and  suppliers,  greater  name  recognition  and  greater  financial,
technical  and  marketing  resources  than  the  Company.  As  a  result,  these
competitors  may be  able to  more quickly develop  and exploit  new or emerging
technologies, adapt  to  changes in  customer  requirements, or  devote  greater
resources to the marketing of their services than the Company. The consolidation
of  telecommunications companies  and the  formation of  strategic alliances and
cooperative relationships  in the  telecommunications and  related industry,  as
well  as the development of new technologies, could give rise to significant new
competitors to the Company. In  such case, there can be  no assurance as to  the
degree to which the Company will be able to compete effectively.
 
GOVERNMENT REGULATION
 
    The  telecommunications  services  offered  by the  Company  are  subject to
regulation by  federal, state  and  local government  agencies. At  the  federal
level,  the FCC  has jurisdiction over  the use of  the electromagnetic spectrum
(I.E., wireless services)  and has  exclusive jurisdiction  over all  interstate
telecommunications  services, that  is, those  that originate  in one  state and
terminate in another state. State regulatory commissions have jurisdiction  over
intrastate  communications, that is,  those that originate  and terminate in the
same state.  Municipalities  may  regulate  limited  aspects  of  the  Company's
business   by,  for   example,  imposing   zoning  requirements   and  requiring
installation permits. See "Business -- Government Regulation."
 
    The Company  is  licensed  by  the  FCC as  a  common  carrier  provider  of
facilities-based  local telecommunications services. For  many of its intrastate
services, the Company will need to  seek authorizations from the states and,  in
most  cases, file tariffs. The  Company is in the  process of filing tariffs for
some of its  services with  the FCC  and with  certain state  authorities on  an
ongoing  basis. Certain of its proposed services  have not yet been permitted in
most states. Although the Telecommunications Act requires the states to open  up
all  of the Company's  services to competition,  there can be  no assurance that
this  will  occur  on  a  timely  basis.  Challenges  to  its  applications  for
authorizations  or its tariffs by third parties could cause the Company to incur
substantial legal and administrative expenses and time delay in implementing its
business  plan.   Although  many   of  the   Company's  applications   for   FCC
authorizations  were subject to  challenge, the Company  nonetheless was granted
authorizations for  a  majority of  its  applications. The  Company's  remaining
applications  were  either  dismissed,  voluntarily  or  involuntarily,  or  are
currently pending before  the FCC.  Some of  these pending  applications are  in
conflict  with applications filed by third parties  and could not, in any event,
be granted unless the  conflicts were eliminated.  Elimination of the  conflicts
generally would require dismissal of a majority of the applications as part of a
settlement.  All of the  pending applications are  subject to the  freeze on the
grant of  additional  authorizations  pending  completion  of  the  NPRM,  which
proposes dismissal of all such applications. The Company's business plans do not
assume  that any of these pending applications will be granted. The Company does
not believe that a failure to  grant these applications will impair its  ability
to operate. See "Business -- Government Regulation."
 
                                       12
<PAGE>
    In its provision of local wireless broadband services, the Company currently
is  not subject to rate  regulation by the FCC, but  is subject to regulation by
most states. Additionally, the Company is required to comply with all applicable
local zoning and  other laws  governing the  installation and  operation of  its
wireless broadband services.
 
    Changes  in existing laws  and regulations, including  those relating to the
provision of wireless local telecommunications services via 38 GHz licenses,  or
any  failure or significant  delay in obtaining  necessary regulatory approvals,
could have a material adverse effect on  the Company. On November 13, 1995,  the
FCC  released an  order barring  the acceptance of  new applications  for 38 GHz
authorizations. On December 15, 1995, the FCC announced the issuance of a notice
of proposed rulemaking (the "NPRM"), pursuant to which it proposed to amend  its
current rules to provide for, among other things, (i) the adoption of an auction
procedure  for the issuance  of authorizations in  the 38 GHz  band, including a
possible auction of the  lower fourteen 100 MHz  channels (which are similar  to
those used by the Company) and the lower four 50 MHz channels in the 38 GHz band
that   have  not  been  previously  available   for  commercial  use,  (ii)  the
continuation of  the  100 MHz-based  channeling  plan and  licensing  rules  for
point-to-point  microwave operations in  the lower 14  channels, (iii) licensing
frequencies using predefined geographic  service areas ("Basic Trading  Areas"),
(iv)  the  imposition of  substantially  stricter construction  requirements for
authorizations that are not received pursuant to auctions as a condition to  the
retention of such authorizations and (v) the implementation of certain technical
rules  designed  to  avoid  radio  frequency  interference  among  licensees. In
addition, the FCC ordered that those applications subject to mutual  exclusivity
with  other applicants or placed on public notice by the FCC after September 13,
1995 would be held in abeyance pending the outcome of the NPRM and might then be
dismissed. Final rules issued  in connection with the  NPRM may require that  38
GHz service providers share other yet-to-be licensed portions of the 38 GHz band
with  other telecommunications service  providers. The implementation  of such a
measure could materially affect the Company's ability to provide services to its
customers by  imposing power  and other  limitations upon  existing  operations.
There  can be no  assurance that the  final rules (if  any) issued in connection
with the NPRM will resemble the rules proposed in the NPRM. There also can be no
assurance that any  proposed or  final rules will  not have  a material  adverse
effect  on the Company. Statutes and  regulations which may become applicable to
the Company  as  it  expands could  require  the  Company to  alter  methods  of
operations  at costs which could be substantial  or otherwise limit the types of
services offered by the Company.
 
    The Company manages the systems of ART West, DCT, Telecom One and  CommcoCCC
pursuant to management agreements (during the pendency of certain acquisitions).
See  "Business  --  Agreements  Relating to  Licenses  and  Authorizations." The
Company believes that the provisions of these management agreements comply  with
the  FCC's  policies  concerning licensee  control  of  FCC-licensed facilities.
Because the 38 GHz service is a new service, however, there is no FCC  precedent
addressing  the  limits of  such management  arrangements  for this  service. No
assurance can be given that the management arrangements or proposed acquisitions
will,  if  challenged,  be  found  to   satisfy  the  FCC's  policies  or   what
modifications  may need to be made to satisfy those policies. If the FCC were to
void or require modifications of the management arrangements, the operations  of
the Company could be adversely affected.
 
RISK OF FORFEITURE, NON-RENEWAL AND FLUCTUATION IN VALUE OF FCC LICENSES
 
    Upon completion of the CommcoCCC Acquisition, the Company will own or manage
a  total of  237 authorizations that  will allow  it to provide  38 GHz wireless
broadband services in 169  U.S. markets. The Company  currently owns or  manages
108  authorizations (exclusive of the CommcoCCC Assets) that allow it to provide
38 GHz wireless broadband services in 89  markets, 73 of which are owned by  the
Company  and the remaining  35 of which  are managed by  the Company through the
Company's interests in or arrangements  with other companies. Under the  current
FCC  rules, the recipient of an authorization for 38 GHz microwave facilities is
required to complete  construction of such  facilities within 18  months of  the
date  of grant of the authorization  (authorizations for facilities that are not
constructed are referred  to in  this Prospectus as  "construction permits"  and
authorizations for facilities
 
                                       13
<PAGE>
that  are constructed  are referred to  in this Prospectus  as "licenses"). Upon
completion of construction, the licensee is required to certify that the station
is operational  and ready  to  provide service  to  the public.  Although  under
current  FCC regulations,  the term "operational"  is not  defined, the industry
custom is to establish at least one link between two transceivers in each market
area for which it holds a construction  permit. In the event that the  recipient
fails  to  comply with  the construction  deadline,  the construction  permit is
subject to  forfeiture,  absent  an  extension  of  the  deadline.  Of  the  108
authorizations  that the  Company owns  or manages  (exclusive of  the CommcoCCC
Assets), 77  are licenses.  Under the  terms of  its remaining  31  construction
permits,  the Company must complete construction  of facilities for the majority
of such construction  permits between mid-August  and mid-September 1996.  Under
the terms of the CommcoCCC authorizations and the Company's management agreement
with  CommcoCCC, the Company must complete  construction of facilities for eight
construction permits by mid-September 1996, 39 construction permits by  December
1996  and the remaining 82 construction permits between mid-April and mid-August
1997. The Company believes that, in light of current FCC practice, extensions of
construction periods are highly unlikely. Although the Company believes that  it
can complete the construction of all of its own and CommcoCCC's facilities using
the  proceeds of the  Offerings within respective  time limits, there  can be no
assurance that it will  be able to  do so or  that the Company  will be able  to
comply with whatever more stringent construction requirements the FCC ultimately
adopts  as a result of the NPRM. As a result, some of the Company's construction
permits could be  subject to  forfeiture, which  could have  a material  adverse
effect  on the Company's development and results of operations. See "Business --
Government  Regulation"  and  "--  38   GHz  Wireless  Broadband  Licenses   and
Authorizations."
 
    The  FCC's current  policy is to  align the  expiration dates of  all 38 GHz
licenses held  by a  particular  licensee such  that  all such  licenses  mature
concurrently  and then to  require renewal of  all such licenses  for a matching
ten-year period. All  of the  38 GHz  licenses owned or  to be  acquired by  the
Company will expire in February 2001. Although the Company currently anticipates
that  its licenses will be  renewed based upon the  FCC's custom and practice in
connection with other services which have established a presumption in favor  of
licensees  that  have complied  with regulatory  obligations during  the initial
license period, there can be no assurance  that all or any of the licenses  will
be  renewed upon expiration  of their initial  terms. In the  event that the FCC
does not renew one or more of  the licenses, the Company's business and  results
of operations could be materially adversely affected.
 
    The  Company plans to  use its authorizations  to develop wireless broadband
systems in all  of its  market areas. In  addition, a  limited secondary  market
exists for 38 GHz authorizations, and the Company may from time to time purchase
such  authorizations. The value of authorizations  held or acquired hereafter by
the Company will  depend upon the  success of the  Company's wireless  broadband
operations,   fluctuations  in  the   level  of  supply   and  demand  for  such
authorizations  and   the   telecommunications  industry's   response   to   the
availability  and efficacy of  wireless broadband systems.  In addition, federal
and  state  regulations   limit  the   ability  of  licensees   to  sell   their
authorizations.  Assignments of authorizations and  changes of control involving
entities holding authorizations require prior FCC and, in some instances,  state
regulatory  approval  and are  subject to  restrictions  and limitations  on the
identity and status of the assignee or successor. These regulatory  restrictions
on  transfer of authorizations  may adversely affect the  value of the Company's
authorizations.
 
MANAGEMENT OF GROWTH
 
    The Company  is currently  experiencing  a period  of  rapid growth  and  is
pursuing  a  business plan  that, if  successfully  implemented, will  result in
expansion of its operations and the provision of 38 GHz services on a widespread
basis over the next two to five years. The Company's success will depend on  its
ability  to manage growth effectively, to  enhance its operational and financial
control and information systems and to attract, assimilate and retain additional
qualified personnel. Failure by the Company to meet the demands of customers and
to manage the  expansion of its  business and operations  could have a  material
adverse effect on the Company's development and results of operations.
 
                                       14
<PAGE>
LINE OF SIGHT; ROOF RIGHTS; OTHER LIMITATIONS
 
    Wireless broadband services over 38 GHz frequencies require a direct line of
sight between two transceivers comprising a link and are subject to distance and
rain  attenuation. The maximum length  of a single link  is generally limited to
three to five miles, and, as  a result, intermediate links (or "repeaters")  are
required  to permit wireless broadband transmission to extend beyond this limit.
In the  absence  of  a direct  line  of  sight, repeaters  may  be  required  to
circumvent  obstacles, such as buildings in urban areas or hills in rural areas.
In addition, in areas of heavy rainfall, the intensity of rainfall and the  size
of   raindrops  can  affect  the  transmission   quality  of  38  GHz  services.
Transmission links  in these  areas  are engineered  for shorter  distances  and
greater power to maintain transmission quality. The use of intermediate links to
overcome  obstructions or rain  fade increases the cost  of service. While these
increased costs  may not  be significant  in all  cases, such  costs may  render
wireless broadband services uneconomical in certain circumstances.
 
    Due  to  line  of  sight limitations,  the  Company  currently  installs its
transceivers and  antennas  on the  rooftops  of  buildings and  on  other  tall
structures.  In order to obtain the necessary access, the Company generally must
secure roof rights from the owners of each building or other structure on  which
its  equipment is installed. Line of sight and distance limitations generally do
not present problems in urban areas due to the ability of the licensee to select
unobstructed  structures  from  which  to  transmit  and  the  concentration  of
customers  within  a  limited area  although  the  Company may  have  to install
intermediate links. Line of  sight and distance  limitations in non-urban  areas
can  arise  due to  lack of  structures  with sufficient  height to  clear local
obstructions. Although the Company has been able to construct intermediary links
in some  instances to  solve line  of sight  limitations in  urban or  non-urban
areas, line of sight limitations can adversely impact sales to certain potential
customers. Failure to obtain roof rights in a timely fashion may cause potential
customers  to use alternative  providers of 38  GHz services or  to refrain from
using 38 GHz  services altogether. There  can be no  assurance that the  Company
will  succeed  in  obtaining the  roof  rights necessary  to  establish wireless
broadband services to all potential customers  in its market areas on  favorable
terms,  if at  all, or  that delays  in obtaining  such rights  will not  have a
material adverse effect on the Company's development and results of operations.
 
    The relative significance of the size of a market area served depends on the
concentration within  that area  of potential  customers. The  Company's  market
areas  were defined by the Company in  preparing its FCC applications for 38 GHz
licenses. The definitions of these areas were based on the Company's analysis of
the then  existing local  demographic characteristics  in each  market, such  as
concentrations  of  employees and  income levels.  In  certain of  the Company's
market areas, other 38 GHz  service providers have larger geographic  footprints
or  greater bandwidth. To  the extent the Company's  authorizations do not track
the appropriate growth  and development patterns  of potential customers  within
its  market areas or other 38 GHz  providers have greater geographic coverage or
more bandwidth, the Company may have a competitive disadvantage.
 
RELIANCE ON EQUIPMENT SUPPLIERS; LACK OF INDUSTRY STANDARDS
 
    The Company  currently  purchases  the majority  of  its  telecommunications
equipment  pursuant  to an  agreement with  P-Com,  Inc. ("P-Com")  and recently
entered into  an equipment  purchase  agreement with  Harris. Any  reduction  or
interruption  in supply from  either supplier could have  a disruptive effect on
the Company.  Although six  manufacturers currently  produce or  are  developing
equipment  that will meet the Company's current and anticipated requirements, no
industry standard or  uniform protocol  currently exists for  38 GHz  equipment.
Consequently,  a single manufacturer's equipment must  be used in establishing a
link and generally will be used across  an entire market area. As a result,  the
failure  of the  Company to  procure sufficient  equipment produced  by a single
manufacturer for service in a particular market area could adversely affect  the
Company's results of operations. See "Business -- Strategic Alliances."
 
                                       15
<PAGE>
DEPENDENCE ON THIRD PARTIES FOR MARKETING AND SERVICE
 
    The  Company  is  partly  dependent upon  third  parties  for  marketing its
services and maintaining its operational  systems. The Company recently  entered
into  the Ameritech Strategic Distribution  Agreement, which allows Ameritech to
resell the Company's 38 GHz services to customers within Ameritech's  midwestern
region  and  to  major  Ameritech customers  nationwide.  The  Company  also has
agreements with  subsidiaries  of  GTE  to provide  field  service  and  network
monitoring  and a joint marketing  agreement with Harris. The  failure of any of
these third parties to perform or the loss of any of these agreements could have
a material adverse effect on the Company's results of operations or its  ability
to  service its customers. The  Company plans to enter  into sales and marketing
agreements with other companies, and the failure to successfully implement these
agreements could have an adverse effect on the Company's development and results
of operations. See "Business -- Strategic Alliances."
 
ACQUISITION OF ADDITIONAL BANDWIDTH IN SELECTED AREAS
 
    Although the Company believes the 38 GHz authorizations it owns, manages  or
has  agreed to acquire  are sufficient in  each of its  markets to implement its
current business strategy, the Company may  seek to acquire or lease  additional
authorizations  to expand its geographic footprint  or to enhance its ability to
provide service to its current target market  or customers it may target in  the
future.   The  FCC  has  suspended  granting  additional  licenses,  subject  to
resolution of the NPRM.  See "Business --  Government Regulation." However,  the
Company  believes that additional channels may become available by virtue of (i)
the obligations of  other 38 GHz  service providers as  common carriers to  make
their  services  available  and  (ii)  FCC auctions  of  and  adoption  of other
licensing procedures for additional  38 GHz authorizations. Nevertheless,  there
can  be no  assurance that  access to additional  38 GHz  authorizations will be
acquired on favorable terms, if at all. See "Business -- Business Strategy," "--
38 GHz  Wireless  Broadband  Licenses and  Authorizations"  and  "--  Government
Regulation."
 
NEW SERVICES; TECHNOLOGICAL CHANGE
 
    The   telecommunications   industry   has   been   characterized   by  rapid
technological advances, changes in end  user requirements, frequent new  service
introductions,  evolving  industry  standards  and  decreases  in  the  cost  of
equipment. The Company expects these changes to continue, and believes that  its
long-term  success will increasingly  depend on its  ability to exploit advanced
technologies and anticipate or adapt  to evolving industry standards. There  can
be  no assurance that (i) the Company's  wireless broadband services will not be
outmoded by technology or services now existing or developed and implemented  in
the  future,  (ii) the  Company  will have  sufficient  resources to  develop or
acquire new technologies or to introduce new services capable of competing  with
future  technologies  or service  offerings,  (iii) the  Company's  inventory of
equipment will not be  rendered obsolete or  (iv) the cost  of 38 GHz  equipment
will decline as rapidly as that of competitive alternatives. See "Business."
 
DEPENDENCE ON KEY EMPLOYEES
 
    The  success of the Company is dependent, in part, on its ability to attract
and retain  qualified  technical,  marketing, sales  and  management  personnel,
especially  the Company's executive officers.  Competition for such personnel is
intense, and  the  Company's inability  to  attract and  retain  additional  key
employees  or the loss of one or more  of its current key employees could have a
material adverse affect on the Company's business and results of operations. The
Company has employment agreements with each of its officers. See "Management."
 
                                FINANCIAL RISKS
 
SIGNIFICANT CAPITAL REQUIREMENTS; UNCERTAINTY OF ADDITIONAL FINANCING
 
    Management anticipates  that,  based on  its  current plan  of  development,
assuming  that no material new acquisitions are consummated, the net proceeds of
the Offerings, after  the use of  approximately $8.0 million  to repay  existing
indebtedness  and  $9.6  million  to complete  pending  acquisitions  of certain
spectrum  rights,  will  be  sufficient  to  fund  the  operations  and  capital
requirements of the Company for at
 
                                       16
<PAGE>
least  the next two years. See "Use  of Proceeds." Management also believes that
the Company's future capital needs will  continue to be significant and that  it
will  be necessary for the Company to  seek additional sources of financing. The
Company expects to  incur capital expenditures  of approximately $100.0  million
through 1997 as the development and expansion of its wireless broadband business
continues.  The Company expects to generate  significant operating losses for at
least the next several  years. The Company  will require substantial  investment
capital  for the continued  development and expansion  of its wireless broadband
operations, the continued funding of related operating losses, and the  possible
acquisition  of  additional licenses,  other assets  or  other businesses.  On a
historical combined  basis,  from its  inception  through March  31,  1996,  the
Company  reported a net loss of $14.1 million. In addition, if (i) the Company's
plan of development or  projections change or prove  to be inaccurate, (ii)  the
proceeds  of the  Offerings, together  with other  existing financial resources,
prove to be insufficient to fund the Company for at least the next two years  or
(iii)  the Company completes  any material acquisitions  not now under contract,
the Company may be required to  seek additional financing sooner than  currently
anticipated.  See "Management's  Discussion and Analysis  of Financial Condition
and Results of Operations." There can be  no assurance that the Company will  be
able  to obtain  any additional financing,  or, if such  financing is available,
that the Company will  be able to  obtain it on acceptable  terms. In the  event
that the Company fails to obtain additional financing, such failure could result
in  the  modification, delay  or abandonment  of  some or  all of  the Company's
development and expansion plans. Any such modification, delay or abandonment  is
likely  to have a material adverse effect on the Company's business, which could
adversely affect the value of the Common  Stock, the Notes and the Warrants  and
may  limit the Company's ability to make  principal and interest payments on its
indebtedness.
 
HIGH LEVERAGE; ABILITY TO SERVICE INDEBTEDNESS
 
    Following the Offerings, the Company will be highly leveraged and will  have
certain  restrictions on its  operations. As of  March 31, 1996,  on a pro forma
basis after giving effect to  the Equipment Financing, the CommcoCCC  Financing,
the  Conversion, the Merger, the Offerings and use of the proceeds therefrom and
completion of the  CommcoCCC Acquisition, all  as if they  had occurred on  that
date,  the  Company  would  have  had  approximately  $163.2  million  of  total
indebtedness and  stockholders'  equity  of  approximately  $230.7  million.  In
addition, the accretion of the principal amount of the Notes over time (based on
an  assumed rate of accretion of 13.5%) will  result in an increase in the total
indebtedness represented  by  the  Notes  of  approximately  $161.3  million  by
          ,  2001.  After giving  effect  to such  transactions  as if  they had
occurred at the  beginning of the  respective periods, the  Company's pro  forma
earnings  for the three months ended March  31, 1996 and the year ended December
31, 1995 would have  been insufficient to cover  fixed charges by  approximately
$17.9 million and $32.4 million, respectively.
 
    The  indebtedness expected to be  incurred as a result  of the Unit Offering
will have  several  important  consequences  to the  holders  of  the  Company's
securities,  including, but  not limited  to, the  following: (i)  a substantial
portion of the Company's cash flow  from operations will ultimately be  required
to  be dedicated to the payment of interest  with respect to the Notes; (ii) the
Company's flexibility may be  limited in responding to  changes in the  industry
and  economic conditions  generally; (iii) the  Indenture relating  to the Notes
(the  "Indenture")  will  contain  numerous  financial  and  other   restrictive
covenants,  the failure to comply with which  may result in an event of default,
which, if not  cured or  waived, could  have a  material adverse  effect on  the
Company;  (iv) the ability of the Company to satisfy its obligations pursuant to
such indebtedness will be dependent upon its future performance which, in  turn,
will  be subject to management, financial,  business and other factors affecting
the business and operations of the Company; (v) the Company's ability to  obtain
any  necessary financing in the future may  be limited; (vi) the Company will be
more highly  leveraged than  many of  its competitors,  which may  put it  at  a
competitive  disadvantage and (vii) the Company's high leverage may make it more
vulnerable in the event of  an economic downturn or  if the Company's cash  flow
does not significantly increase. Some of these factors are beyond the control of
the Company. See "Unaudited Pro Forma
 
                                       17
<PAGE>
Condensed  Financial Statements,"  "Selected Historical and  Pro Forma Financial
Data" and  "Management's  Discussion and  Analysis  of Financial  Condition  and
Results  of  Operations." In  addition, although  the  Indenture will  limit the
ability of the Company  and its subsidiaries  to incur additional  indebtedness,
the   Indenture  will  permit  the   Company  to  incur  substantial  additional
indebtedness, which may  or may not  be secured,  during the next  few years  to
finance  the  construction  of  networks,  the  purchase  of  equipment  and the
introduction of new services.  Additional indebtedness of  the Company may  rank
PARI  PASSU in  right of  payment with the  Notes in  certain circumstances. See
"Description of Certain Indebtedness -- The Notes" and "-- Credit Facility." Any
such indebtedness may contain covenants that may limit the Company's flexibility
in responding to changes in industry and economic conditions generally. The debt
service requirements of any additional indebtedness could make it more difficult
for the Company to make principal and  interest payments on the Notes and  could
exacerbate any of the foregoing consequences.
 
    There  can  be  no assurance  that  the  Company will  be  able  to generate
sufficient cash flow to meet required interest and principal payments associated
with the Notes and its other indebtedness. If the Company is unable to  generate
sufficient  cash flow to meet its debt  obligations, the Company may be required
to renegotiate  the payment  terms  or to  refinance all  or  a portion  of  its
indebtedness,  to sell assets or to  obtain additional financing. If the Company
is unable to  refinance such  indebtedness, substantially all  of the  Company's
long-term  debt would be  in default and  could be declared  immediately due and
payable. Furthermore, the  Indenture contains numerous  financial and  operating
covenants,  including, among  others, covenants  restricting the  ability of the
Company and its  subsidiaries to incur  indebtedness or to  create or suffer  to
exist certain liens. In the event the Company fails to comply with these various
covenants,  it could  be in default  under the  Indenture. In the  event of such
default, substantially all  of the  Company's long-term debt  could be  declared
immediately  due and  payable. See "Description  of Certain  Indebtedness -- The
Notes."
 
                            LEGAL AND TRADING RISKS
 
ABSENCE OF PUBLIC MARKET; POSSIBLE VOLATILITY OF STOCK PRICE
 
    Prior to the Common Stock Offering, there has been no public market for  the
Company's  Common Stock. While the Common  Stock has been approved for quotation
on the Nasdaq National Market, there can  be no assurance that an active  public
trading  market will  develop or  be sustained after  the Offerings  or that the
initial public offering price will correspond  to the price at which the  Common
Stock  will trade in  the public market thereafter.  The initial public offering
price will be  determined solely  by negotiations  between the  Company and  the
Representatives.  See  "Underwriting"  for a  discussion  of the  factors  to be
considered in  determining  the  initial  public  offering  price.  The  Company
believes  that factors, such as (i) announcements of developments related to the
Company's business, (ii)  announcements of new  services by the  Company or  its
competitors,   (iii)  developments  in  the  Company's  relationships  with  its
suppliers  or  customers,  (iv)  fluctuations   in  the  Company's  results   of
operations,  (v)  a  shortfall in  revenues  or earnings  compared  to analysts'
expectations and changes in analysts' recommendations or projections, (vi) sales
of substantial amounts of securities of the Company into the marketplace,  (vii)
regulatory  developments  affecting the  telecommunications  industry or  38 GHz
services or (viii) general conditions in the telecommunications industry or  the
worldwide  economy,  could cause  the price  of the  Common Stock  to fluctuate,
perhaps substantially.
 
CONTROL BY MANAGEMENT AND PRINCIPAL STOCKHOLDERS
 
    Upon consummation  of  the  Offerings,  the  Company's  executive  officers,
directors  and their affiliates, as a group, will beneficially own approximately
28.4% of  the Company's  outstanding Common  Stock (27.6%  if the  Underwriters'
over-allotment  option is exercised  in full and 19.5%  upon consummation of the
CommcoCCC  Acquisition).  In   addition,  upon  completion   of  the   CommcoCCC
Acquisition,  Columbia Capital  Corporation, as  general partner  of two  of the
stockholders of  CommcoCCC, and  Commco, L.L.C.,  the remaining  stockholder  of
CommoCCC, will beneficially own approximately 16.3%
 
                                       18
<PAGE>
and  14.2%, respectively  of the Company's  outstanding Common  Stock (15.9% and
13.9% if the Underwriters' over-allotment option is exercised in full), and  the
Company  has  agreed  to nominate  one  individual designated  by  the CommcoCCC
stockholders and acceptable to  the Company as a  director of the Company  after
the CommcoCCC Acquisition. As a result, these stockholders will have the ability
to  exercise  significant influence  over the  Company and  the election  of its
directors, the appointment  of new  management and  the approval  of any  action
requiring  the approval of the holders  of the Company's voting stock, including
adopting certain amendments  to the Company's  Certificate of Incorporation  and
approving  mergers or  sales of substantially  all of the  Company's assets. The
directors elected  by  these stockholders  will  have the  authority  to  effect
decisions affecting the capital structure of the Company, including the issuance
of additional capital stock, the implementation of stock repurchase programs and
the declaration of dividends. See "Principal Stockholders."
 
ABSENCE OF DIVIDENDS ON COMMON STOCK
 
    The  Company has not paid and does  not anticipate paying any cash dividends
on its Common Stock in the foreseeable future. The Company intends to retain its
earnings, if any,  for use in  the Company's growth  and ongoing operations.  In
addition, the terms of the Indenture will restrict the ability of the Company to
pay  dividends on the Common Stock.  See "Description of Certain Indebtedness --
The Notes."
 
ANTITAKEOVER PROVISIONS; POSSIBLE FUTURE ISSUANCES OF PREFERRED STOCK
 
    The Company's Certificate of Incorporation and Bylaws and the provisions  of
the  Delaware  General  Corporation  Law (the  "Delaware  GCL")  contain certain
provisions which may have  the effect of discouraging,  delaying or making  more
difficult  a  change in  control of  the  Company or  preventing the  removal of
incumbent directors.  The existence  of  these provisions  may have  a  negative
impact  on the price of the Common Stock, the Units, the Notes and the Warrants,
may discourage third  party bidders from  making a  bid for the  Company or  may
reduce  any premiums paid  to stockholders for  their Common Stock. Furthermore,
the Company is subject to Section 203 of the Delaware GCL, which could have  the
effect  of  delaying or  preventing  a change  in  control of  the  Company. See
"Description of Capital Stock -- Change in Control Provisions."
 
    The  Company's  Certificate  of  Incorporation  also  allows  the  Board  of
Directors  to issue up  to 10,000,000 shares  of Preferred Stock  and to fix the
rights, privileges and preferences  of such shares without  any further vote  or
action  by the stockholders. The  rights of the holders  of Common Stock will be
subject to, and may be adversely affected  by, the rights of the holders of  any
Preferred  Stock that  may be  issued in  the future.  While the  Company has no
present intention to issue shares of Preferred Stock, any such issuance could be
used to discourage,  delay or make  more difficult  a change in  control of  the
Company. See "Description of Capital Stock -- Preferred Stock."
 
DILUTION
 
    Purchasers  of  shares of  Common Stock  in the  Common Stock  Offering will
experience immediate dilution  of $7.19 in  net tangible book  value per  share,
assuming  an initial  public offering  price of $9.00  per share.  To the extent
outstanding options  and warrants  (including the  Warrants issued  in the  Unit
Offering)  are exercised, there will be  further dilution. Assuming the issuance
of  16,500,000  shares  of  Common  Stock  in  connection  with  the   CommcoCCC
Acquisition  as of  the date  of this  Prospectus, the  purchasers of  shares of
Common Stock in the Common Stock Offering will experience immediate dilution  of
$8.73 in net tangible book value per share. See "Dilution."
 
SHARES ELIGIBLE FOR FUTURE SALE
 
    Sales of a substantial number of shares of Common Stock in the public market
following  the Offerings could  adversely affect the market  price of the Common
Stock. Upon consummation  of the  Offerings, the Company  will have  outstanding
37,586,498  shares of Common Stock, assuming no exercise of outstanding options,
warrants, rights or other  convertible securities, 30,086,498  of which will  be
subject  to  resale  restrictions. Beginning  90  days  after the  date  of this
Prospectus, approximately 10,013,055  of the restricted  shares of Common  Stock
will become available for sale in the public market
 
                                       19
<PAGE>
pursuant  to Rule  144 under  the Securities  Act, subject  in certain  cases to
volume and other resale limitations under Rule 144. All of the restricted shares
are subject to lock-up  agreements with Montgomery  Securities which expire  180
days  after  the date  of this  Prospectus  or such  earlier time  as Montgomery
Securities may,  in  its  sole discretion  determine.  See  "Underwriting."  The
balance of the outstanding restricted shares of Common Stock (20,073,443 shares)
will become available for sale in the public market under Rule 144 approximately
two  years after the date of this  Prospectus. Upon the closing of the CommcoCCC
Acquisition, 16,500,000 shares will  be issued for  the CommcoCCC Assets,  which
shares  will become available for  sale in the public  market under Rule 144 two
years after  the date  of consummation  of the  CommcoCCC Acquisition.  Under  a
proposal  currently pending before  the Securities and  Exchange Commission (the
"Commission"), the  date  on which  such  shares  of Common  Stock  will  become
available  for sale under Rule 144 may be accelerated to one year after the date
of this Prospectus (or one year after  the date of the closing of the  CommcoCCC
Acquisition  in  the case  of  the 16,500,000  shares  issued for  the CommcoCCC
Assets). Holders of  30,086,498 shares (46,586,498  shares upon consummation  of
the  CommcoCCC Acquisition) of  Common Stock and  warrants to purchase 1,475,000
shares of Common Stock have contractual  rights to have those shares  registered
with  the Commission for resale  to the public. See  "Shares Eligible For Future
Sale."
 
                                       20
<PAGE>
                                  THE COMPANY
 
    Advanced  Radio Telecom Corp. provides wireless broadband telecommunications
services using  point-to-point  microwave  transmissions in  the  37.0  to  40.0
gigahertz  portion of the radio  spectrum ("38 GHz"). The  Company is seeking to
address  the   growing   demand   for  high   speed,   high   capacity   digital
telecommunications services on the part of business and government end users who
require  cost effective, high  bandwidth local access to  voice, video, data and
Internet services.  The Company's  last mile  services are  a complement  and  a
viable alternative to fiber optic networks and offer rapidly deployable coverage
throughout  the 89 markets in  which the Company is  currently authorized by the
FCC to provide services.
 
    The business of  the Company is  comprised of (i)  the business of  Advanced
Radio  Technologies Corporation ("ART" or the "Company"), a company organized by
Vernon L. Fotheringham and W. Theodore Pierson,  Jr. in 1993 for the purpose  of
acquiring 38 GHz licenses, and (ii) the business of Advanced Radio Telecom Corp.
("Telecom"),  a corporation organized  in Delaware in March  1995 under the name
Advanced Radio Technology, Ltd. for the purposes of acquiring additional 38  GHz
licenses and developing and operating the business of ART and Telecom on a joint
basis.  In April 1995, ART entered into the ART West Joint Venture Agreement (as
defined) to apply for, acquire and develop 38 GHz operations in 13 states in the
western  United  States.  In  November  1995,  the  Company  completed  the  EMI
Acquisition  (as  defined),  pursuant to  which  it acquired  thirty-two  38 GHz
licenses and certain  related assets  in the  northeast United  States. In  July
1996,  the Company entered into the CommcoCCC Agreement to acquire the CommcoCCC
Assets and other agreements to acquire authorizations it currently manages. Upon
completion of these pending acquisitions, the Company will own or manage a total
of 237 authorizations to provide 38 GHz wireless broadband services in 169  U.S.
markets.   See  "Risk   Factors  --   Risk  of   Non-Consummation  of  CommcoCCC
Acquisition," "Business -- Agreements Relating to Licenses and Authorizations --
ART West Joint Venture," "-- EMI Acquisition" and " -- CommcoCCC Acquisition."
 
    To date,  the  business  of  the  Company  has  been  operated  and  managed
(including  all FCC licenses  and construction permits held  by ART and Telecom)
pursuant to a services agreement. On June 26, 1996, ART and Telecom entered into
the Merger Agreement (as  defined), pursuant to which  a subsidiary of ART  will
merge  with  and into  Telecom. In  June 1996,  the FCC  indicated that  it will
approve the Merger. Upon completion of the Merger, Telecom will become a  wholly
owned  subsidiary of ART and change its  name to "ART Licenses Corporation," and
ART will change  its name  to "Advanced Radio  Telecom Corp."  See "Business  --
Proposed  Merger" and "Certain  Transactions -- Merger."  Prior to completion of
the Merger,  Telecom will  manage  the combined  businesses  of the  Company  in
accordance  with the terms of the  existing services agreement. See "Business --
Agreements Relating to Licenses and Authorizations -- ART Services Agreement."
 
    DIGIWAVE, ART, OZ BOX  and ADVANCED RADIO TELECOM  are service marks of  the
Company.  The Company's  principal executive  offices are  located at  500 108th
Avenue, N.E., Suite 2600, Bellevue, Washington 98004 and its telephone number is
(206) 688-8700.
 
                                       21
<PAGE>
                                USE OF PROCEEDS
 
    The net  proceeds to  the Company  from the  Offerings are  estimated to  be
approximately  $231.0 million in the aggregate, giving effect to the sale by the
Company of  7,500,000  shares  of  Common Stock  offered  in  the  Common  Stock
Offering,  based on an assumed initial public offering price of $9.00 per share,
and the Units  offered in the  Unit Offering, assuming  $175.0 million of  gross
proceeds, and, in each case, after deducting the estimated underwriting discount
and offering expenses.
 
    Of the net proceeds, approximately $100.0 million is expected to be used for
capital  expenditures through December  31, 1997 and  an additional $9.6 million
will be used for the  acquisition of certain spectrum  rights from ART West  and
DCT.  See "Business -- Agreements Relating to Licenses and Authorizations -- ART
West Joint Venture" and " -- DCT System Purchase Agreements." Approximately $8.0
million will be used for the repayment of indebtedness, consisting of the Bridge
Notes, which were issued  on March 8,  1996 and which bear  interest at 10%  per
annum,  and the CommcoCCC Notes,  which were issued on June  27 and July 3, 1996
and  which  bear  interest  at  the  prime  rate.  See  "Certain  Transactions,"
"Description  of  Certain  Indebtedness  --  Bridge  Notes"  and  "--  CommcoCCC
Financing." The  expected  amount  of capital  expenditures  includes  estimated
construction  costs under service  agreements with CommcoCCC,  ART West, DCT and
Telecom  One.   See   "Business  --   Agreements   Relating  to   Licenses   and
Authorizations."  Such amount also includes the cost to complete construction of
initial transmission facilities estimated at less than $5.0 million.
 
    The remainder  of  the net  proceeds  will  be used  for  general  corporate
purposes,  including the funding  of operating cash  flow shortfalls, technology
development and  acquisitions of  additional spectrum  rights and,  potentially,
related  businesses. Although the Company  considers potential acquisitions from
time to  time, no  agreement,  agreement in  principle, understanding  or  other
arrangement,  other than the Extended Agreement (as defined), the DCT Agreements
(as defined),  the  Telecom  One  Agreements  (as  defined)  and  the  CommcoCCC
Agreement,  has  been  reached with  respect  to any  acquisition.  Although the
Company may fund research  and development activities and  acquire or invest  in
related  businesses  from  time to  time,  no material  agreement,  agreement in
principle, understanding or other arrangement, other than the letters of  intent
with  American  Wireless  (as defined),  QuestTV  (as defined)  and  Helioss (as
defined) has been entered into with respect to any such funding, acquisition  or
investment.   Management  anticipates  that,  based   on  its  current  plan  of
development and assuming that  no material new  acquisitions or investments  are
consummated,  the remaining net proceeds of  the Offerings will be sufficient to
fund the operations of the Company for the next two years. See "Risk Factors  --
Significant Capital Requirements; Uncertainty of Additional Financing."
 
                                DIVIDEND POLICY
 
    The  Company has not paid and does  not anticipate paying any cash dividends
on the Common Stock in the foreseeable future. The Company intends to retain its
earnings, if any,  for use in  the Company's growth  and ongoing operations.  In
addition, the terms of the Indenture will restrict the ability of the Company to
pay  dividends on the Common Stock.  See "Description of Certain Indebtedness --
The Notes."
 
                                       22
<PAGE>
                                 CAPITALIZATION
 
    The following table sets forth the capitalization of the Company as of March
31, 1996 (i) on a historical combined basis, giving effect to the elimination of
balances between ART  and Telecom  and the  elimination of  ART's investment  in
Telecom  and Telecom's  investment in  ART, (ii)  on a  pro forma  basis, giving
effect to the Conversion,  the Merger and  certain other financing  transactions
occurring  subsequent to March 31, 1996 as  specified in Note 1 hereto and (iii)
on a pro forma as adjusted basis, giving  effect to (A) the sale by the  Company
of  7,500,000 shares of Common Stock offered  in the Common Stock Offering based
on an assumed initial  public offering price  of $9.00 per  share and the  Units
offered  in the Unit Offering assuming $175.0 million of gross proceeds, and, in
each case,  after deducting  the estimated  underwriting discount  and  offering
expenses, (B) the receipt and application of the net proceeds therefrom to repay
the  Bridge Notes and the CommcoCCC Notes and to acquire certain spectrum rights
from ART West and DCT (see "Use of Proceeds") and (C) the issuance of 16,500,000
shares of  Common Stock  based  upon an  assumed value  of  $9.00 per  share  in
connection  with the  CommcoCCC Acquisition. The  capitalization information set
forth in the table below is qualified by the more detailed information contained
in, and should be read in conjunction with, the audited financial statements  of
ART and Telecom and the notes thereto, the unaudited interim condensed financial
statements  of ART and Telecom and the notes thereto and the unaudited pro forma
condensed financial  statements  of  the  Company and  the  notes  thereto,  all
appearing elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                            AS OF MARCH 31, 1996
                                                            -----------------------------------------------------
                                                              HISTORICAL                            PRO FORMA
                                                               COMBINED        PRO FORMA (1)       AS ADJUSTED
                                                            ---------------  ------------------  ----------------
<S>                                                         <C>              <C>                 <C>
Cash and cash equivalents.................................  $     3,024,161  $     8,244,161     $    218,669,161
                                                            ---------------  ------------------  ----------------
                                                            ---------------  ------------------  ----------------
Short-term debt:
  CommcoCCC Notes.........................................  $            --  $     2,975,000     $             --
                                                            ---------------  ------------------  ----------------
                                                            ---------------  ------------------  ----------------
Long-term debt:
  Note payable to EMI.....................................  $     1,500,000  $     1,500,000     $      1,500,000
  Bridge Notes............................................        3,983,082        3,983,082                   --
  Equipment Note..........................................               --        1,911,439            1,911,439
  Senior Discount Notes offered concurrently (2)..........               --               --          159,800,000
                                                            ---------------  ------------------  ----------------
    Total long-term debt..................................        5,483,082        7,394,521          163,211,439
                                                            ---------------  ------------------  ----------------
Stockholders' equity:
  Telecom convertible serial preferred stock (3)..........              921               --                   --
  Common Stock (4)........................................           10,013           30,086               54,086
  Telecom common stock (5)................................           18,114               --                   --
  Additional paid-in capital..............................       19,375,335       19,883,757          245,727,482
  Deficit accumulated during the development stage........      (14,064,645)     (14,064,645)         (15,106,563)
                                                            ---------------  ------------------  ----------------
    Total stockholders' equity............................        5,339,738        5,849,198          230,675,005
                                                            ---------------  ------------------  ----------------
      Total capitalization................................  $    10,822,820  $    13,243,719     $    393,886,444
                                                            ---------------  ------------------  ----------------
                                                            ---------------  ------------------  ----------------
</TABLE>
 
- ------------------------
(1)  Reflects  pro forma adjustments  for the following  transactions as if they
     had occurred as of March 31, 1996: (i) the receipt of $2.2 million in  cash
     proceeds  from the issuance of the Equipment Note and Indemnity Warrants in
     connection with the Equipment  Financing, after deducting related  expenses
     of  $225,000; (ii) the  receipt of $3.0  million in cash  proceeds from the
     issuance of the CommcoCCC Notes  and CommcoCCC Warrants in connection  with
     the  CommcoCCC  Financing;  (iii)  the  Conversion  and  (iv)  the  Merger,
     including the  issuance  of  Common Stock  to  Telecom's  stockholders  and
     cancellation   of  all  outstanding  Telecom  common  stock.  See  "Certain
     Transactions."
 
(2)  The Company anticipates  gross proceeds  from the Unit  Offering of  $175.0
     million.  The  estimated value  of the  Warrants  ($15.2 million)  has been
     reflected both as  a debt  discount and  an element  of additional  paid-in
     capital.
 
(3)  Consists of Telecom convertible serial preferred stock, $.001 par value per
     share:  10,000,000 shares authorized; historical combined -- 455,550 shares
     of Series A, 114,679 shares of Series  B, 7,363 shares of Series C,  61,640
     shares  of Series D, 232,826 shares of Series E and 48,893 shares of Series
     F issued and outstanding; pro forma and pro forma as adjusted -- no  shares
     issued and outstanding.
 
(4)  Consists  of Common  Stock, $.001 par  value per  share: 100,000,000 shares
     authorized;  historical   combined   --  10,013,055   shares   issued   and
     outstanding;  pro forma  -- 30,086,498  shares issued  and outstanding; pro
     forma as adjusted -- 54,086,498 issued and outstanding.
 
(5)  Consists of Telecom  common stock,  $.001 par value  per share:  60,000,000
     shares  authorized;  historical combined  --  18,114,135 shares  issued and
     outstanding; pro forma and  pro forma as adjusted  -- no shares issued  and
     outstanding.
 
                                       23
<PAGE>
                                    DILUTION
 
    The  pro forma net tangible  book value of the Company  as of March 31, 1996
was $5,673,585, or $0.19 per share of  Common Stock, after giving effect to  the
Equipment  Financing,  the  Conversion,  the  CommcoCCC  Financing,  the  Merger
(including  the  issuance  of  Common   Stock  to  Telecom's  stockholders   and
cancellation  of all Telecom common stock) and  the issuance of the Units in the
Unit Offering and the  use of the  net proceeds therefrom  for the repayment  of
certain  indebtedness and completion of certain pending acquisitions of spectrum
rights. "Pro forma net tangible book  value per share" represents the amount  of
the  Company's total  tangible assets  comprised of  cash and  cash equivalents,
other current  assets,  net property  and  equipment, and  equipment  and  other
deposits,  less total liabilities (net of deferred finance costs) divided by the
pro forma number  of shares  of Common  Stock outstanding.  Without taking  into
account  any other changes in the net  tangible book value after March 31, 1996,
other than to  give effect  to the  receipt by the  Company of  net proceeds  of
approximately  $62.4 million from  the sale of 7,500,000  shares of Common Stock
offered by the Common Stock Offering based on an assumed initial public offering
price of $9.00 per  share, after deducting  the estimated underwriting  discount
and  offering expenses, the pro forma net  tangible book value of the Company as
of March 31,  1996 would  have been approximately  $68.0 million,  or $1.81  per
share  of Common Stock. This  represents an immediate increase  in pro forma net
tangible book value of $1.62 per share to existing stockholders and an immediate
dilution of $7.19 per  share to new investors.  The following table  illustrates
this per share dilution:
 
<TABLE>
<S>                                                                 <C>        <C>
Assumed initial public offering price per share...................             $    9.00
  Pro forma net tangible book value per share as of March 31, 1996
   before giving effect to the Common Stock Offering..............  $    0.19
  Increase in pro forma net tangible book value per share
   attributable to new investors..................................       1.62
                                                                    ---------
Pro forma net tangible book value per share as of March 31, 1996,
 as adjusted for the Common Stock Offering........................                  1.81
                                                                               ---------
Dilution in pro forma net tangible book value per share to new
 investors........................................................             $    7.19
                                                                               ---------
                                                                               ---------
</TABLE>
 
    The following table summarizes, as of March 31, 1996, after giving effect to
the  Offerings, the number of shares of Common Stock purchased from the Company,
the total consideration paid to the Company and the average price per share paid
by the existing stockholders and by new investors purchasing Common Stock in the
Common Stock Offering. In the Common Stock Offering, based on an assumed initial
public offering  price  of  $9.00  per  share  before  deducting  the  estimated
underwriting  discount and  offering expenses,  the number  of shares  of Common
Stock purchased from the Company is  7,500,000, the total consideration paid  to
the  Company is $67,500,000,  the average price  per share paid  by the existing
stockholders is $0.32 and the price per share paid by new investors is $9.00.
 
<TABLE>
<CAPTION>
                                         SHARES PURCHASED          TOTAL CONSIDERATION
                                     ------------------------  ---------------------------  AVERAGE PRICE
                                        NUMBER       PERCENT       AMOUNT        PERCENT      PER SHARE
                                     -------------  ---------  --------------  -----------  -------------
<S>                                  <C>            <C>        <C>             <C>          <C>
Existing stockholders..............     30,086,498       80.0% $    9,622,156        12.5%    $    0.32
New investors......................      7,500,000       20.0      67,500,000        87.5          9.00
                                     -------------  ---------  --------------  -----------
    Total..........................     37,586,498      100.0% $   77,122,156       100.0%
                                     -------------  ---------  --------------  -----------
                                     -------------  ---------  --------------  -----------
</TABLE>
 
    The foregoing computations do not give effect to the exercise of any of  the
following  as of March 31,  1996: (i) 877,136 shares  of Common Stock subject to
the Ameritech Warrant;  (ii) 1,100,000  shares of  Common Stock  subject to  the
Bridge  Warrants; (iii) 325,000 shares of  Common Stock subject to the Indemnity
Warrants; (iv) 50,000 shares of Common Stock subject to the CommcoCCC  Warrants;
(v)  1,664,732 shares of  Common Stock subject to  outstanding options under the
Equity Incentive Plan; and (vi) 28,000 shares of Common Stock anticipated to  be
subject  to outstanding options  under the Directors  Plan upon the  date of the
Offerings. As of  June 28, 1996,  an additional 835,268  shares of Common  Stock
were  available for issuance  under the Equity Incentive  Plan and an additional
172,000 shares of Common Stock were  available for issuance under the  Directors
Plan.  See "Certain  Transactions" and "Management  -- Stock  Option Plans." The
computations also do  not give effect  to the issuance  of 16,500,000 shares  of
Common  Stock in connection with the  CommcoCCC Acquisition which, at an assumed
value of  $9.00 per  share, would  result in  a decrease  in the  pro forma  net
tangible  book value of $53.5 million or $1.54 per share. In addition, the above
does not give effect to the exercise of (i) the over-allotment option granted to
the Underwriters  by the  Company in  the  Common Stock  Offering and  (ii)  the
Warrants.  See "Underwriting."  To the  extent that  any outstanding  options or
warrants are exercised,  there will be  further dilution to  new investors.  See
"Risk Factors -- Dilution."
 
                                       24
<PAGE>
                SELECTED HISTORICAL AND PRO FORMA FINANCIAL DATA
 
THE COMPANY -- HISTORICAL COMBINED AND PRO FORMA DATA
 
    The  unaudited  selected historical  combined and  pro forma  financial data
presented below as of and for the three months ended March 31, 1996 and for  the
year  ended December  31, 1995 and  the unaudited  historical combined financial
data presented below as of December 31, 1995 were derived from the unaudited pro
forma condensed financial statements of  the Company included elsewhere in  this
Prospectus.  For definitions  of certain  terms and  more information  about the
transactions cited in the notes thereto, see "Certain Transactions."
 
    The unaudited  selected historical  combined and  pro forma  financial  data
should  be read in conjunction with the  audited financial statements of ART and
Telecom, and  the  notes  thereto, the  unaudited  condensed  interim  financial
statements  of ART  and Telecom,  and the notes  thereto, and  the unaudited pro
forma condensed  financial statements  of the  Company, and  the notes  thereto,
included   elsewhere  in  the  Prospectus.  The  unaudited  selected  historical
combined, pro forma and pro forma as adjusted financial data are not necessarily
indicative of what the  actual financial position and  results of operations  of
the  Company would have been as of and for the three months ended March 31, 1996
and as of  and for  the year ended  December 31,  1995, nor do  they purport  to
represent the Company's future financial position and results of operations.
 
<TABLE>
<CAPTION>
                                          YEAR ENDED DECEMBER 31, 1995                 THREE MONTHS ENDED MARCH 31, 1996
                                  ---------------------------------------------  ---------------------------------------------
                                   HISTORICAL                    PRO FORMA AS     HISTORICAL                    PRO FORMA AS
                                  COMBINED (1)   PRO FORMA (2)   ADJUSTED (3)    COMBINED (1)   PRO FORMA (2)   ADJUSTED (3)
                                  -------------  -------------  ---------------  -------------  -------------  ---------------
<S>                               <C>            <C>            <C>              <C>            <C>            <C>
STATEMENT OF OPERATIONS DATA:
Operating revenue...............   $     5,793    $     5,793    $       5,793    $     9,620    $     9,620    $       9,620
Non-cash compensation expense...     1,089,605      1,089,605        1,089,605      7,221,000      7,221,000        7,221,000
Depreciation and amortization...        15,684         15,684        5,418,452         89,279         89,279        1,439,971
Interest, net...................       121,986      1,974,275       23,931,008        151,145        528,739        5,989,300
Net loss........................     3,234,843      5,087,132       30,609,692     10,694,588     11,092,182       17,444,199
Pro forma net loss per share of
 Common Stock (4)...............            --   $       0.16   $         0.55             --   $       0.35   $         0.31
Pro forma weighted average
 number of shares of Common
 Stock outstanding (4)..........            --     31,651,605       55,651,605             --     31,651,605       55,651,605
 
OTHER FINANCIAL DATA:
EBITDA (5)......................  $ (1,936,141 ) $ (1,936,141 ) $   (1,936,141 ) $ (2,156,893 ) $ (2,156,893 ) $   (2,156,893 )
Capital expenditures............     3,585,144      3,585,144        3,585,144      2,861,241      2,861,241        2,861,241
</TABLE>
 
<TABLE>
<CAPTION>
                                                   AS OF
                                               DECEMBER 31,
                                                   1995                      AS OF MARCH 31, 1996
                                               -------------  --------------------------------------------------
                                                HISTORICAL     HISTORICAL                        PRO FORMA AS
                                               COMBINED (1)   COMBINED (1)    PRO FORMA (2)      ADJUSTED (3)
                                               -------------  -------------  ----------------  -----------------
<S>                                            <C>            <C>            <C>               <C>
BALANCE SHEET DATA:
Working capital surplus (deficit)............   $(3,008,510)   $(1,128,130)   $    1,116,870    $   214,516,870
Property and equipment, net..................     3,581,561      6,380,895         6,380,895          6,380,895
FCC licenses.................................     4,235,734      4,235,734         4,235,734        216,110,734
Total assets.................................     9,876,559     15,036,337        20,432,236        448,589,961
Short-term debt..............................            --             --         2,975,000                 --
Long-term debt, including current portion....     6,450,000      5,483,082         7,394,521        163,211,439
Deficit accumulated during the development
 stage.......................................    (3,370,057)   (14,064,645)      (14,064,645)       (15,106,563)
Total stockholders' equity (deficit).........      (312,860)     5,339,738         5,849,198        230,675,005
</TABLE>
 
                                       25
<PAGE>
ART -- HISTORICAL FINANCIAL DATA
 
    The  selected historical financial data of ART below as of and for the years
ended December 31, 1995 and 1994, and for the period from August 23, 1993  (date
of  inception) to  December 31,  1993 were  derived from  and should  be read in
conjunction with the audited financial statements  of ART and the related  notes
thereto  included elsewhere in  this Prospectus. The  selected financial data of
ART below as of March 31, 1996 and for the three months ended March 31, 1996 and
1995 were derived  from and  should be read  in conjunction  with the  unaudited
condensed  interim financial  statements of  ART and  the related  notes thereto
included elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                              AUGUST 23, 1993
                            (DATE OF INCEPTION)                YEAR ENDED                       THREE MONTHS ENDED
                                    TO           --------------------------------------  --------------------------------
                             DECEMBER 31, 1993   DECEMBER 31, 1994   DECEMBER 31, 1995   MARCH 31, 1995   MARCH 31, 1996
                            -------------------  ------------------  ------------------  ---------------  ---------------
<S>                         <C>                  <C>                 <C>                 <C>              <C>
STATEMENT OF OPERATIONS
 DATA:
Operating revenue.........       $      --           $  137,489         $         --        $      --      $          --
Depreciation and
 amortization.............             688                8,281               10,378               --              2,595
Net loss..................       $   6,594           $  128,620         $  1,267,655        $  41,753      $   3,654,775
Pro forma net loss per
 share of Common Stock
 (4)......................              --                   --         $       0.04               --      $        0.12
Pro forma weighted average
 number of shares of
 Common Stock outstanding
 (4)......................              --                   --           31,651,605               --         31,651,605
OTHER FINANCIAL DATA:
Capital expenditures......       $      --           $    5,175         $         --        $      --      $          --
</TABLE>
 
<TABLE>
<CAPTION>
                                                                AS OF DECEMBER 31,                       AS OF MARCH 31,
                                            -----------------------------------------------------------  ---------------
                                                   1993                 1994                1995              1996
                                            -------------------  ------------------  ------------------  ---------------
<S>                                         <C>                  <C>                 <C>                 <C>
BALANCE SHEET DATA:
Working capital surplus (deficit).........       $  13,958           $  (76,556)        $   (976,563)     $    (494,630)
Property and equipment, net...............              --                3,448                1,723              1,292
FCC licenses..............................              --                   --                8,913              8,913
Total assets..............................          74,513               42,611            5,784,624          3,281,788
Long-term debt, including current
 portion..................................              --                   --            4,950,000                 --
Redeemable Preferred Stock................              --                   --               44,930             44,930
Deficit accumulated during the development
 stage....................................          (6,594)            (135,214)          (1,402,869)        (5,057,644)
Total stockholders' equity (deficit)......          54,542              (39,078)            (404,481)         2,736,258
</TABLE>
 
                                       26
<PAGE>
TELECOM -- HISTORICAL FINANCIAL DATA
    The selected historical financial data of  Telecom below as of December  31,
1995  and for the period from March 28, 1995 (date of inception) to December 31,
1995 were  derived from  and should  be  read in  conjunction with  the  audited
financial statements of Telecom and the related notes thereto included elsewhere
in  this Prospectus. The selected financial data  of Telecom below as of and for
the three months ended March  31, 1996 were derived from  and should be read  in
conjunction with the unaudited condensed interim financial statements of Telecom
and the related notes thereto included elsewhere in this Prospectus.
<TABLE>
<CAPTION>
                                                                                 MARCH 28, 1995
                                                                                    (DATE OF
                                                                                   INCEPTION)         THREE MONTHS
                                                                                       TO                ENDED
                                                                               DECEMBER 31, 1995     MARCH 31, 1996
                                                                               ------------------  ------------------
<S>                                                                            <C>                 <C>
STATEMENT OF OPERATIONS DATA:
Operating revenue............................................................     $      5,793       $        9,620
Non-cash compensation expense................................................        1,089,605            7,221,000
Depreciation and amortization................................................            5,306               86,684
Net loss.....................................................................     $  2,981,073       $   10,666,383
OTHER FINANCIAL DATA:
Capital expenditures.........................................................     $  3,585,144       $    2,861,241
 
<CAPTION>
 
                                                                                     AS OF               AS OF
                                                                                  DECEMBER 31,         MARCH 31,
                                                                                      1995                1996
                                                                               ------------------  ------------------
<S>                                                                            <C>                 <C>
BALANCE SHEET DATA:
Working capital surplus (deficit)............................................     $ (2,031,947)      $     (633,500)
Property and equipment, net..................................................        3,579,838            6,379,603
FCC licenses.................................................................        4,226,821            4,226,821
Total assets.................................................................        9,830,615           15,254,980
Long-term debt...............................................................        6,500,000            5,483,082
Deficit accumulated during the development stage.............................       (2,981,073)         (13,647,456)
Total stockholders' equity (deficit).........................................         (119,922)           5,560,881
</TABLE>
 
- ------------------------------
(1)  The  unaudited  selected  financial  data  under  the  caption  "Historical
     Combined" are presented as  if the historical  financial statements of  ART
     and   Telecom  had  been  combined  and  reflect  (i)  the  elimination  of
     transactions and balances between ART and Telecom and (ii) the  elimination
     of ART's investment in Telecom and Telecom's investment in ART.
 
(2)  The  unaudited selected  financial data under  the caption  "Pro Forma" are
     presented as if the following transactions had occurred as of the beginning
     of the respective periods  for the Statement of  Operations Data and  Other
     Financial Data and as of the balance sheet date for the Balance Sheet Data:
     (i)  the March 8, 1996 issuance of  the Bridge Notes in connection with the
     Bridge Financing; (ii) the  receipt of $2.2 million  in cash proceeds  from
     the  issuance of  the Equipment Note  and Indemnity  Warrants in connection
     with the Equipment Financing, after deducting related fees and expenses  of
     $225,000;  (iii)  the receipt  of $3.0  million in  cash proceeds  from the
     issuance of the CommcoCCC Notes  and CommcoCCC Warrants in connection  with
     the  CommcoCCC Financing; (iv) the Conversion and (v) the Merger, including
     the  issuance  of  ART  Common  Stock  to  Telecom  stockholders  and   the
     cancellation   of  all  outstanding  Telecom  common  stock.  See  "Certain
     Transactions."
 
(3)  The unaudited  selected financial  data  under the  caption "Pro  Forma  As
     Adjusted" are presented as if the transactions referred to in (2) above and
     the  following  transactions  had  occurred  as  of  the  beginning  of the
     respective periods for the Statement of Operations Data and Other Financial
     Data and as of the balance sheet  date for the Balance Sheet Data: (i)  the
     sale  by the  Company of  7,500,000 shares of  Common Stock  offered in the
     Common Stock Offering based on an assumed initial public offering price  of
     $9.00  per share and the Units offered in the Unit Offering assuming $175.0
     million of gross proceeds, and, in each case, after deducting the estimated
     underwriting  discount  and  offering   expenses;  (ii)  the  receipt   and
     application of the net proceeds therefrom to repay the Bridge Notes and the
     CommcoCCC  Notes and to acquire the 50% ownership interest of ART West held
     by Extended for $6.0 million in cash and the DCT Assets for $3.6 million in
     cash and (iii) the issuance of 16,500,000 shares of Common Stock based upon
     an assumed  value of  $9.00  per share  in  connection with  the  CommcoCCC
     Acquisition. See "Use of Proceeds."
 
(4)  Pro  forma net loss per share is computed  based on the loss for the period
     divided  by  the  weighted  average  number  of  shares  of  Common   Stock
     outstanding  during the period including the Conversion, the Merger and the
     issuance of potentially dilutive instruments  issued within one year  prior
     to  the  Offerings  at exercise  prices  below the  assumed  initial public
     offering price of $9.00  per share. In measuring  the dilutive effect,  the
     treasury stock method was used.
 
(5)  EBITDA means loss before interest expense, income tax expense, depreciation
     and amortization expense, non-cash compensation expense and non-cash market
     development  expense. Information with respect to EBITDA is included herein
     because a similar measure will be used in the Indenture with respect to the
     computation of certain covenants. EBITDA is not intended to represent  cash
     flows from operating activities, as determined in accordance with generally
     accepted accounting principles, nor has it been presented as an alternative
     to operating income as an indicator of operating performance and should not
     be  considered  as a  substitute for  measures  of performance  prepared in
     accordance with generally accepted accounting principles.
 
                                       27
<PAGE>
               MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                      CONDITION AND RESULTS OF OPERATIONS
 
GENERAL
 
    The  Company provides  wireless broadband  telecommunications services using
point-to-point microwave  transmissions  in the  38  GHz portion  of  the  radio
spectrum.  The Company is seeking to address  the growing demand for high speed,
high capacity digital telecommunications  services on the  part of business  and
government  end users who require cost effective, high bandwidth local access to
voice, video, data and Internet services.
 
    To facilitate a meaningful comparison, the following discussion and analysis
is based  on the  historical combined  financial information  of Advanced  Radio
Technologies Corporation ("ART") and Advanced Radio Telecom Corp. ("Telecom") as
of  all dates  and for  all periods  ending after  March 28,  1995, the  date of
Telecom's inception, and the  historical financial statements of  ART as of  all
dates  and for all the periods  ended prior to March 28,  1995. All of the above
financial  statements  appear  elsewhere  in  this  Prospectus.  The  historical
combined  financial  statements  include  the  elimination  of  transactions and
balances between the  two entities as  well as ART's  investment in Telecom  and
Telecom's investment in ART.
 
    The  following discussion includes certain forward-looking statements. For a
discussion of  important  factors,  including, but  not  limited  to,  continued
development  of the  Company's business,  actions of  regulatory authorities and
competitors, and  other  factors  that  could cause  actual  results  to  differ
materially from the forward-looking statements, see "Risk Factors."
 
OVERVIEW
 
    The Company's business commenced in 1993, and the Company has generated only
nominal  revenues from operations to date. The Company's primary activities have
focused on the acquisition of wireless construction permits (authorizations  for
facilities that are not constructed) and licenses (authorizations for facilities
that  are constructed),  the hiring of  management and other  key personnel, the
raising of capital,  the acquisition  of equipment  and the  development of  its
operating and support systems and infrastructure. The Company has obtained radio
spectrum  rights under FCC  issued licenses and  construction permits throughout
the United States by applying  to the FCC directly  and through the purchase  of
such rights held by others. The Company's ability to provide commercial services
on  a widespread basis and to generate  positive operating cash flow will depend
on its ability, among  other things, to  (i) deploy its 38  GHz technology on  a
market-by-market basis, (ii) attract and retain an adequate customer base, (iii)
successfully  develop and  deploy its operational  and support  systems and (iv)
acquire appropriate sites for its operations. Proper management of the Company's
anticipated growth and quality of its service will require the Company to expand
its technical, accounting and internal  management systems at a pace  consistent
with  the  Company's  planned  business  roll-out.  This  roll-out  will require
substantial capital  expenditures. See  "Liquidity  and Capital  Resources"  and
"Risk Factors."
 
    The  Company  has  experienced  significant  operating  and  net  losses and
negative operating cash flow in  connection with the development and  deployment
of  its  wireless broadband  services  and systems  and  expects to  continue to
experience net losses  and negative operating  cash flow until  such time as  it
develops  a  revenue-generating  customer  base  sufficient  to  fund  operating
expenses attributable to the Company's wireless broadband operations. See  "Risk
Factors." The Company expects to achieve positive operating margins over time by
(i)  increasing the  number of  revenue generating  customers and  responding to
growing demand for capacity among its customers without significantly increasing
related   hardware   and   roof   rights   costs   and   (ii)   inducing   other
telecommunications  service  providers  to  utilize  and  market  the  Company's
wireless broadband services as part of their own services, thereby reducing  the
Company's  related  marketing  costs.  The  Company  anticipates  that operating
revenues will  increase in  1996; however,  the Company  also expects  that  net
losses  and negative operating cash flow will increase as the Company implements
its   growth   strategy   and   that,   under   its   current   business   plan,
 
                                       28
<PAGE>
net  losses and negative operating cash flow will continue for at least the next
several years. Accordingly, the Company  will be dependent on various  financing
sources  to fund  its growth  as well as  continued losses  from operations. See
"Liquidity and Capital Resources."
 
ACQUISITIONS, BUSINESS DEVELOPMENT AND CAPITAL EXPENDITURES
 
    From inception through March 31, 1996, the Company has invested an aggregate
of $4.2  million  to  obtain  interests  in  FCC  authorizations  and  licenses,
including  those acquired from EMI, and invested  $285,000 in the ART West Joint
Venture. From inception, expenditures for  property and equipment have  totalled
$6.5  million. In addition, the Company has incurred significant other costs and
expenses in the development of its  business and has recorded cumulative  losses
from  inception through March 31, 1996 of approximately $14.1 million, including
$9.4 million of non-cash compensation and  marketing expenses, and used cash  in
operating  activities of approximately  $3.1 million. The  Company has agreed to
acquire,  subject  to  FCC  approval   and  other  conditions,  additional   FCC
authorizations  and licenses for an aggregate  purchase price of $9.6 million in
cash and 16.5  million shares of  the Company's Common  Stock. The Company  may,
when  and  if  the  opportunity  arises,  acquire  other  spectrum  rights  and,
potentially, related  businesses,  incur  expenses in  the  development  of  new
technologies and expand its wireless broadband services into new market areas.
 
    The   recoverability  of  property  and   equipment  and  intangible  assets
representing FCC authorizations is dependent upon the successful development  of
systems  in each  of the  respective markets,  or through  sale of  such assets.
Management estimates that it will recover  the carrying amounts of those  assets
from  cash flow generated by the systems once they have been developed. However,
it is possible that such estimate will change as a result of any failure by  the
Company  to develop its FCC authorizations  on a timely basis, or technological,
regulatory or other changes.
 
    The Company  is  exploring  the  possibilities  of  providing  its  wireless
broadband  services  in  other countries  including  Canada and  in  Europe. The
Company has  entered  into agreements  with  certain consultants  and  potential
partners  to identify foreign opportunities and  expects to file application for
licenses or to acquire 38 GHz licenses in several European countries. There  can
be  no  assurance that  the Company  can  acquire such  licenses or  develop and
operate such systems.
 
    The Company entered into a management consulting agreement in November  1995
with  Landover  Holdings  Corporation  ("LHC")  to  provide  strategic planning,
corporate development  and general  management  services. Under  the  agreement,
which  terminates on the date  of this Prospectus, the  Company pays LHC $35,000
per month for an initial one year term. In 1995 the Company paid $140,000 to LHC
for consulting services and  $391,750 for expenses in  connection with the  $7.0
million   investment  made  under  the  LHC  Purchase  Agreement.  See  "Certain
Transactions."
 
RESULTS OF OPERATIONS
 
    The Company  has generated  nominal revenue  from operations  to date.  From
inception through March 31, 1996, the Company has incurred aggregate expenses of
approximately $14.2 million, including $9.4 million of non-cash compensation and
marketing expenses. The remaining expenses consist of compensation and benefits,
sales  and marketing expenses,  consulting and legal  fees, facilities expenses,
systems development  costs,  management  consulting expenses  and  net  interest
expenses related to building the Company's business infrastructure and marketing
its  wireless  broadband services.  The  Company expects  to  generate increased
revenues beginning  in  1996; however,  there  can  be no  assurance  that  this
objective  will  be  achieved. The  Company  expects  that it  will  not achieve
profitable operations at least through fiscal 1998. See "Risk Factors -- Limited
Operations; History of Net Losses."
 
    THREE MONTHS ENDED MARCH 31, 1996 COMPARED TO MARCH 31, 1995
 
    Revenue for the three months ended March 31, 1996 was $9,620 compared to  no
revenue  in 1995. The increase in revenues  was due to operating revenues earned
from wireless broadband telecommunications services provided by the Company.
 
                                       29
<PAGE>
    Operating expenses  other than  interest were  $10.6 million  for the  three
months  ended  March 31,  1996 compared  to  $40,878 in  1995. The  increase was
primarily due to $7.2 million  of non-cash compensation expense, including  $6.8
million  arising  from  the  termination of  the  Escrow  Share  Arrangement (as
defined) and subsequent  release of  shares to certain  employees in  connection
with  the February 1996  Reorganization (as defined), as  well as higher general
and administrative, increased market  development, and research and  development
expenses.  See  "Certain  Transactions."  Excluding  the  non-cash  compensation
expense, general and administrative expenses  increased primarily due to  higher
payroll  and  consulting costs  relating  to the  ramp-up  in operations  of the
Company. Market  development  expenses increased  primarily  due to  a  non-cash
marketing   expense  of  $1.1   million  related  to   the  Ameritech  Strategic
Distribution Agreement.  Research and  development costs  were incurred  as  the
Company  initiated its research  and development of  microwave radio technology.
The Company expects cash expenses for general and administrative, marketing  and
research  and development  to increase  substantially in  future periods  as the
development and deployment of the Company's business continues.
 
    Interest expense was  $174,416 for  the three  months ended  March 31,  1996
compared  to $875 in 1995. The increase in interest expense was primarily due to
interest on the EMI Note  and the Bridge Notes.  Interest expense in the  second
quarter  of  1996 will  increase primarily  due  to a  full quarter  of interest
expense on the Bridge Notes and also due to the Equipment Note executed in April
1996, and the  issuance of  the Notes will  cause interest  expense to  increase
substantially  in future periods. The write-off of unamortized offering discount
and deferred  finance costs  associated with  the Bridge  Notes is  expected  to
result  in  a non-cash  extraordinary loss  of  approximately $1.0  million upon
repayment at the closing of the Offerings.
 
    FISCAL 1995 COMPARED TO FISCAL 1994
 
    ART was formed in 1993, and, accordingly, the Company's historical financial
statements for 1994 reflect ART's activities in applying for 38 GHz licenses and
building operating systems.
 
    The Company had $137,489 in  consulting services income for engineering  and
management  services related  to filing of  applications for 38  GHz licenses on
behalf of others, including Extended, in 1994 and $5,793 in operating revenue in
1995 derived from customers for wireless broadband services attributable to  the
markets  for  which  licenses  were  acquired from  EMI  in  November  1995. See
"Business  --  Agreements  Relating  to  Licenses  and  Authorizations  --   EMI
Acquisition."
 
    Total  expenses other than interest increased  from $261,734 in 1994 to $3.1
million in 1995  due to the  expansion of  the business and  the recognition  of
non-cash  compensation  expenses  associated  with  employee  stock  options  of
$287,603 and certain Escrow Shares (as defined) of $802,002 associated with  the
release  to certain  employees of  the Company  as a  result of  meeting certain
performance objectives for an aggregate of $1.1 million of non-cash compensation
expenses. See "Certain Transactions --  LHC Purchase Agreement -- February  1996
Reorganization."  General and administrative  expenses, including these non-cash
compensation expenses, increased to $2.9 million for fiscal 1995, from  $253,453
for  1994. Market development expenses increased to  $191,693 in 1995 from $0 in
1994. Net interest expenses increased to  $121,986 in 1995 from $4,375 in  1994.
As  a result, the net loss for 1995 was  $3.2 million, as compared to a net loss
of $128,620 in 1994.
 
    FISCAL 1994 COMPARED TO FISCAL 1993
 
    The Company had $137,489 in consulting  services income in 1994 compared  to
no  revenue  in 1993.  The  increase in  1994  was primarily  due  to consulting
services related to 38 GHz license applications.
 
    Total expenses other  than interest  expense increased to  $261,734 in  1994
from  $6,594 in 1993. The  increases were due primarily  to consulting and legal
fees related to the initial operations of the Company.
 
                                       30
<PAGE>
LIQUIDITY AND CAPITAL RESOURCES
 
    The Company's operations  have required substantial  capital investment  for
the  acquisition  of  FCC authorizations  and  related assets,  the  purchase of
telecommunications equipment, staffing, and the development and expansion of the
Company's infrastructure to support  anticipated growth. From inception  through
March  31,  1996,  the  Company  used $3.1  million  of  cash  in  its operating
activities and $7.3  million of  cash in  its investing  activities. These  cash
outflows  were financed  primarily through  private equity  and debt placements,
including the issuance of convertible  notes payable to the Advent  Partnerships
which  were converted  into equity  in February 1996.  At December  31, 1995 the
Company had a working capital deficit of  $3.0 million and cash of $633,654,  as
compared  to a working capital deficit of $76,556 and cash of $5,133 at December
31, 1994. The Company had a working capital deficit of $1.1 million and cash  of
$3.0 million at March 31, 1996. Subsequent to March 31, 1996, the Company raised
$2.2  million in cash  (net of expenses)  from the Equipment  Financing and $3.0
million in cash from the CommcoCCC Financing. See "Certain Transactions."
 
    The Company's total assets increased from $42,611 as of December 31, 1994 to
$9.9 million at December 31, 1995 and $15.0 million at March 31, 1996.  Property
and  equipment, net of accumulated depreciation, comprised $3.6 million of total
assets at December 31, 1995 and $6.4 million at March 31, 1996. FCC licenses and
the investment  in the  ART West  Joint  Venture increased  to $4.5  million  at
December 31, 1995 and March 31, 1996, as compared to $0.0 at December 31, 1994.
 
    Cash  used in operating activities increased by $1.4 million to $1.5 million
in 1995 over 1994.  The increase in cash  used in operating activities  resulted
primarily  from the increase  in net loss  to $3.2 million,  partially offset by
non-cash compensation expenses of $1.1 million and increased payables in 1995.
 
    Cash used in investing activities increased by $4.2 million in 1995 compared
to minimal amounts in 1994. The increase was primarily due to $3.0 million  paid
for  the  EMI  acquisition, and  approximately  $900,000 used  for  property and
equipment additions in 1995.
 
    Cash provided by financing activities increased by $6.2 million in 1995 over
1994. The  increase  was  primarily  due to  the  issuances  of  the  Advent/ART
Securities  of  $5.0  million and  of  Telecom  serial preferred  stock,  net of
redemptions of $2.0 million issued in 1995, partially offset by the use of  cash
for stock and debt issuance costs.
 
    Capital  expenditures, including deposits  on equipment for  fiscal 1995 and
1994,  were  $3.9  million  and  $5,175,  respectively.  The  Company  currently
purchases  the majority  of its  wireless transmission  equipment from  a single
vendor, P-Com, Inc., under an equipment purchase agreement which expires at  the
end  of 1998. The Company  is committed to purchase a  total of $13.3 million of
equipment under this agreement. The Company  has also entered into an  equipment
purchase agreement, expiring in 1997, with Harris, providing for the purchase of
wireless transmission equipment.
 
    Cash  used in operating  activities increased to $1.5  million for the three
months ended March 31, 1996 compared to $49,212 for the three months ended March
31, 1995. The increase was primarily due to higher operating costs. Cash used in
investing activities was approximately $3.1  million for the three months  ended
March  31, 1996 compared to $0.0 for the  three months ended March 31, 1995. The
increase was  due to  additions  to property  and  equipment. Cash  provided  by
financing  activities increased to $6.9 million  in the three months ended March
31, 1996 compared  to $44,334 for  the three  months ended March  31, 1995.  The
increase  was primarily due  to the private equity  placement with Ameritech and
the Bridge Notes.
 
    The Company does  not currently  manufacture, nor does  it have  or plan  to
develop  the  capability  to  manufacture,  any  of  the  wireless  transmission
equipment necessary to provide its services. Although there are a limited number
of manufacturers who  have, or  are developing,  equipment that  would meet  the
Company's  requirements, there can be no  assurance that such equipment would be
available to the
 
                                       31
<PAGE>
Company on comparable terms  or on terms more  favorable than those included  in
its  current arrangements  in the event  that such  arrangements are terminated.
Moreover, a change in vendors  could cause a delay  in the Company's ability  to
provide its services, which would affect future operating results adversely.
 
    The  Company has  entered into an  agreement with American  Wireless to fund
$700,000 to $1.0 million of research  and development costs related to  wireless
transmission  equipment. Vernon L. Fotheringham, the Chairman of the Company, is
a director and a 6% shareholder of American Wireless. The Company will receive a
first right of refusal on production capacity and a license fee in exchange  for
its  funding. The Company has also entered  into a letter of intent with Helioss
Communications Corporation ("Helioss")  for the development  of advanced 38  GHz
radios.   Under  the   letter  of  intent,   which  is   subject  to  definitive
documentation, the Company will fund up to $1.0 million of Helioss' research and
development expenses.  The  Company  will  have a  right  of  first  refusal  on
production  capacity of the radios  and will receive a royalty  on the sale of a
certain number of radios  to customers other than  the Company. The Company  has
also  entered into  a letter  of intent  to invest  $1.5 million  in QuestTV (as
defined), a provider of  video and data transmission  and storage services.  See
"Certain  Transactions  --  American  Wireless  Development  Agreement"  and "--
QuestTV Investment."  Although the  Company  does not  have any  other  material
commitments  to fund  research and development,  it expects  to incur additional
expenses for research and development.
 
    The Company currently expects that  its capital expenditures (excluding  the
acquisition  of  certain spectrum  rights)  will aggregate  approximately $100.0
million through  December  31,  1997.  The  Company  currently  expects  capital
expenditures through December 31, 1997 to consist of approximately $65.0 million
for  wireless transmission  equipment, approximately  $20.0 million  for network
design and development and related equipment and approximately $15.0 million for
computer equipment and other related capital. Included in these amounts are  the
costs of initial construction of all owned and managed authorizations, estimated
to  be less  than $5.0 million,  including wireless  transmission equipment. The
Company expects that  capital expenditures for  wireless transmission  equipment
will  be largely variable  with market demand, increasing  over the remainder of
1996 and the  next several years  as demand  for the Company's  38 GHz  services
increases in the targeted geographic markets and industry segments. In addition,
the  Company has agreed to acquire  authorizations and licenses for $9.6 million
from DCT and ART West. The Company has entered into an agreement to acquire  129
38 GHz authorizations from CommcoCCC in exchange for 16,500,000 shares of Common
Stock.  CommcoCCC has entered into a management agreement with the Company under
which the Company will  construct, manage and operate  the authorizations to  be
acquired  pending consummation of the CommcoCCC Acquisition. If the Company does
not consummate the CommcoCCC Acquisition, the Company expects that approximately
25% of its expected  capital expenditures through 1997  would be deferred  until
later  years  and incurred  in  the Company's  other  markets. See  "Business --
Agreements Relating to Licenses and Authorizations -- CommcoCCC Acquisition."
 
    The Company  is obliged  to  pay all  costs  and expenses  of  construction,
operation  and  management of  the authorizations  managed  by the  Company. The
Company is also  obligated under the  terms of the  service agreements  covering
such  authorizations to pay fees to  the current holders of those authorizations
approximating 10%  to  15%  of  the revenue  generated  from  such  assets.  See
"Business -- Agreements Relating to Licenses and Authorizations."
 
    The  Company  expects  that it  will  continue to  have  substantial capital
requirements in connection with (i) the acquisition of appropriate sites for its
operations, (ii)  deployment of  its  38 GHz  technology on  a  market-by-market
basis,  (iii) capturing  and retaining  an adequate  revenue generating customer
base and (iv) developing and deploying its operational and support systems.  The
Company believes it has an opportunity to expand its wireless broadband services
business  significantly and that access to capital will enable it to expand more
quickly and effectively.
 
    The Company has incurred significant  operating and net losses and  negative
operating  cash flow attributable  to the development  of its wireless broadband
services and anticipates that such losses and
 
                                       32
<PAGE>
negative operating cash flow will increase as the Company implements its  growth
strategy.  Accordingly, the Company  will be dependent  on additional capital to
fund its growth, as well as to fund continued losses from operations.
 
    Management anticipates that, based on current plans of development, assuming
that no new material  acquisitions (other than  those currently under  contract)
are consummated, the net proceeds of the Offerings after the use of $8.0 million
to   repay  existing   indebtedness  and   $9.6  million   to  complete  pending
acquisitions,  and  the  proceeds  of  the  Credit  Facility  (as  defined),  if
consummated,  will be sufficient  to fund the  operations of the  Company for at
least the next two years. See "Description of Certain Indebtedness."  Management
believes that the Company's future capital needs will continue to be significant
and  that thereafter  it will  be necessary for  the Company  to seek additional
sources of financing. In addition, if  (i) the Company's plan of development  or
projections  change  or  prove  to  be  inaccurate,  (ii)  the  proceeds  of the
Offerings, together  with  other  existing  financial  resources,  prove  to  be
insufficient  to fund  the Company for  at least  the next two  years, (iii) the
Company fails to consummate  the Credit Facility or  (iv) the Company  completes
any  material acquisitions, other than those now under contract or buys spectrum
at auction, the Company may be required to seek additional financing sooner than
currently anticipated. There can be no  assurance that the Company will be  able
to obtain any additional financing, or, if such financing is available, that the
Company  will be able  to obtain it on  acceptable terms. In  the event that the
Company fails to obtain additional financing,  such failure could result in  the
modification,  delay or abandonment of some  or all of the Company's development
and expansion plans. Any  such modification, delay or  abandonment is likely  to
have  a material adverse effect on the Company's business, which could adversely
affect the value of the Common Stock,  the Notes and the Warrants and may  limit
the   Company's  ability  to  make  principal   and  interest  payments  on  its
indebtedness.
 
NEW ACCOUNTING PRONOUNCEMENT
 
    In October 1995, the Financial  Accounting Standards Board issued  Statement
of   Financial  Accounting  Standards  No.   123,  "Accounting  for  Stock-Based
Compensation." This Statement encourages, but  does not require, accounting  for
stock  compensation awards granted to employees based on their fair value at the
date the awards are  granted. Companies may elect  to continue to apply  current
accounting  requirements for employee stock compensation awards, which generally
will result in no compensation cost for  most fixed stock option plans, such  as
the  Company's Equity Incentive Plan. The  expense measurement provisions of the
Statement apply to all equity instruments issued for goods and services provided
by persons other than employees. All  companies are required to comply with  the
disclosure  requirements  of  the  Statement. The  Company  expects  to continue
accounting for  employee  stock  compensation awards  using  current  accounting
requirements.
 
INFLATION
 
    Management  does not believe that its business is impacted by inflation to a
significantly different extent than is the general economy.
 
                                       33
<PAGE>
                                    BUSINESS
 
    Advanced  Radio  Telecom Corp.  ("ART" or  the "Company")  provides wireless
broadband   telecommunications   services    using   point-to-point    microwave
transmissions  in the 37.0 to 40.0 gigahertz  portion of the radio spectrum ("38
GHz"). The Company is seeking to address the growing demand for high speed, high
capacity digital  telecommunications  services  on  the  part  of  business  and
government  end users who require cost effective, high bandwidth local access to
voice, video,  data  and  Internet  services. Upon  completion  of  its  pending
acquisition  of  129 38  GHz wireless  broadband authorizations  (the "CommcoCCC
Assets") from CommcoCCC, Inc.  ("CommcoCCC"), the Company will  own or manage  a
total  of 237  authorizations granted  by the  Federal Communications Commission
("FCC") covering an  aggregate population  of approximately 143  million in  169
U.S. markets.
 
TELECOMMUNICATIONS INDUSTRY OVERVIEW
 
    The   current  telecommunications   landscape  is  being   reshaped  by  the
convergence of three  major trends: (i)  the accelerating growth  in demand  for
high   speed,  high  capacity  digital  telecommunications  services,  (ii)  the
deregulation of  telecommunications  markets and  (iii)  the rapid  advances  in
wireless   technologies.   The  growth   in  demand   for  high   speed  digital
telecommunications services is being driven by the revolution in  microprocessor
power  and  advances in  new  multimedia and  on-line  applications such  as the
Internet. The ability to  access and distribute  information quickly has  become
critical  to business and  government users of  telecommunications services. The
proliferation  of  local  area  networks  ("LANs"),  rapid  growth  of  Internet
services,  rising demand for video teleconferencing and other demand factors are
significantly increasing the volume of broadband telecommunications traffic. The
inability of the existing infrastructure to meet this demand is creating a "last
mile" bottleneck in  the copper wire  networks of the  incumbent local  exchange
carriers  ("LECs").  This  increasing  demand,  together  with  changes  in  the
regulatory environment, are  creating an  opportunity to  offer cost  effective,
high capacity last mile access using both wireline and wireless solutions.
 
    The  present structure  of the  U.S. telecommunications  industry was shaped
principally by  the 1984  court-directed  divestiture of  the Bell  System  (the
"Divestiture").  As  part  of  the Divestiture,  seven  Regional  Bell Operating
Companies ("RBOCs") were created  and separated from  the long distance  service
provider,  AT&T, resulting in two  distinct telecommunications industries: local
exchange and inter-exchange  (commonly known as  long distance). Local  exchange
services typically involve the carriage of telecommunications within FCC-defined
local  access and  transport areas  ("LATAs"), and  the provision  of access, or
connections,  between  LECs  and   inter-exchange  carriers  ("IXCs")  for   the
completion of long distance calls.
 
    Since  the Divestiture, the local exchange segment of the telecommunications
market has remained the domain of LECs. Recently, however, regulatory policy has
shifted away from  monopoly protection of  the LECs. U.S.  court decisions,  FCC
actions  and most recently the  Telecommunications Act have dramatically changed
the regulatory environment. These  changes have permitted increased  competition
in  the local exchange market and  created opportunities for new companies, such
as competitive access providers ("CAPs").
 
    Beginning in the late 1980s, CAPs emerged to compete with LECs by  providing
dedicated  private line transmission and access services. CAP networks typically
consist of fiber  optic facilities  connecting IXC points  of presence  ("POPs")
with  customer locations  and LEC switches  within a  limited metropolitan area.
Initially, demand for alternative local access  was driven by access charges  of
approximately  40% to 45% of the cost of  a long distance call levied by LECs on
the IXCs.  In  addition to  providing  lower  access charges,  CAP  fiber  optic
services,  where available, have  generally been considered  to provide superior
quality and  higher capacity  services than  those available  from LECs'  legacy
copper  wire networks.  A leading research  company estimates that  in 1994 CAPs
captured approximately $1.3 billion, or 1.3%,  of the $97.1 billion in  revenues
generated  by the  local exchange  market. Such  research company  also projects
that, as a result of increased competition and the growth of enhanced  services,
 
                                       34
<PAGE>
CAPs'  revenues will grow in excess of 150% per year over the next two years. In
addition to CAPs, a wide range of alternative access providers, including  cable
television  operators,  wireless local  loop service  providers and  others, are
expected to emerge.
 
    Continued growth  in the  quality and  number of  competitors in  the  local
telecommunications market will be driven principally by (i) the growing interest
among  business customers  for an  alternative to the  LEC networks  in order to
obtain  higher  capacity  and  better  pricing,  (ii)  the  increases  in   data
applications   and  capacity  requirements  for  local  and  wide  area  network
connections, high speed Internet access  and videoconferencing, (iii) the  LECs'
inability  to  upgrade their  copper networks  quickly,  (iv) the  preference of
competing telecommunications providers  to control the  points of connection  to
their   customers  and  prevent  LECs   from  obtaining  confidential  marketing
information and (v) new state and federal legislation mandating  interconnection
and competition in the local exchange market.
 
    Wireless  broadband  telecommunications services  are developing  rapidly to
handle these growing needs for alternative access. In particular, the successful
deployment of 38  GHz links by  European cellular service  providers and  recent
advances   in  38  GHz  technology,  coupled  with  metropolitan-wide  footprint
licensing, has enabled the  provision of greater capacity  and reliability at  a
lower  cost per customer than traditional  copper wire networks. Furthermore, 38
GHz facilities  can be  installed, deinstalled  and reinstalled  elsewhere  with
minimal time and cost compared to both fiber optic and copper wire facilities.
 
38 GHZ TECHNOLOGY
 
    The  FCC has allocated fourteen  100 MHz channels between  38.6 GHz and 40.0
GHz for wireless broadband transmissions and  has allocated the 37.0 - 38.5  GHz
band  to wireless broadband transmissions (the 37.0 - 38.5 GHz band and the 38.6
- -40.0 GHz  band are  collectively referred  to as  "38 GHz"),  which enable  the
licensee  to  provide  point-to-point  services  within  a  specified geographic
footprint usually of up to a 50-mile radius.
 
    38 GHz technology was first widely deployed in Europe by cellular  telephone
service  providers for the  interconnection of cell sites  with switches. In the
early 1990s, technological advances resulted  in a substantial reduction in  the
cost  and size of millimetric microwave  components with a simultaneous increase
in reliability and  quality, allowing  for the provision  of wireless  broadband
telecommunication  links  at competitive  prices. By  1993,  advances in  38 GHz
technology, combined with its growing use in Europe and Central America, led  to
increasing  awareness of  and interest in  the potential  uses of 38  GHz in the
United  States.  EMI   Communications  Corporation   ("EMI")  (whose   licenses,
authorizations and related assets ART purchased in November 1995) was one of the
first  companies to  undertake commercial exploitation  of 38 GHz  services on a
regional basis.
 
    The 38 GHz band provides for the following additional advantages as compared
to other spectrum bands and wireline alternatives:
 
    - HIGHER DATA TRANSFER RATES.  The total amount of bandwidth for each 38 GHz
      channel is  100 MHz,  which exceeds  the bandwidth  of any  other  present
      terrestrial   wireless  channel  allotment  and  supports  full  broadband
      capability. For example, one  38 GHz DS-3 link  at 45 megabits per  second
      ("Mbps")  today can transfer data at a  rate which is over 1,500 times the
      rate of the fastest  dial-up modem currently in  use (28.8 Kbps) and  over
      350  times the  rate of  the fastest  integrated services  digital network
      ("ISDN") line currently in  use (128 Kbps).  In addition to  accommodating
      standard  voice  and data  requirements, 45  Mbps data  transmission rates
      allow end users to receive real time full motion video and 3-D graphics at
      their workstations and to utilize  highly interactive applications on  the
      Internet and other networks.
 
    - SIGNIFICANT  CHANNEL  CAPACITY.   Because 38  GHz  radio emissions  have a
      narrow beam width,  a relatively  short range  and in  most instances  the
      capability  to  intersect without  creating  interference, 38  GHz service
      providers can efficiently  reuse their bandwidth  within a licensed  area,
 
                                       35
<PAGE>
      thereby  increasing the number of customers  to which such services can be
      provided. Management believes that by using technology currently  employed
      by  the Company it can serve  virtually all of the immediately addressable
      market in its market areas.
 
    - RAPID DEPLOYMENT.   38 GHz  technology can be  deployed considerably  more
      rapidly than wireline and other wireless technologies, generally within 72
      hours  after obtaining  access to  customer premises.  In contrast  to the
      relative ease of installing a 38 GHz transmission link, extending fiber or
      copper-based networks to reach new customers requires significant time and
      expense. In addition, unlike providers of point-to-point microwave service
      in other spectrum bands, a 38  GHz license holder can install and  operate
      as many transmission links as it can engineer in the licensed area without
      obtaining  additional  approvals  from  the  FCC.  This  is  a substantial
      advantage over other portions of the microwave radio spectrum that must be
      licensed on a link-by-link  basis following frequency coordination,  which
      in total can take from three to five months.
 
    - EASE  OF INSTALLATION.  The equipment used for point-to-point applications
      in 38 GHz (I.E.,  antennae, transceivers and  digital interface units)  is
      smaller,  less obtrusive and  less expensive than  that used for microwave
      equipment applications at lower frequencies, making it less susceptible to
      zoning  restrictions.  In  addition,  38  GHz  equipment  can  be   easily
      redeployed to meet changing customer requirements.
 
    - ADDITIONAL   ADVANTAGES  OVER  OTHER  PORTIONS  OF  RADIO  SPECTRUM.    At
      frequencies  above  38  GHz,   point-to-point  applications  become   less
      practical  because attenuation increases and  the maximum distance between
      transceivers accordingly decreases.  Additionally, the  FCC has  specified
      the  use  of many  portions of  the spectrum  for applications  other than
      point-to-point, such  as  satellite  and  wireless  cable  services,  and,
      accordingly,  these portions of the radio spectrum often are not available
      for point-to-point applications. Finally, 38 GHz has characteristics which
      provide better signal  quality and performance  in inclement weather  than
      those offered in other portions of the radio spectrum.
 
THE ART SOLUTION
 
    The  Company is positioned to solve the need for broadband last mile access,
linking  end  users  to  fiber  optic   based  facilities  of  CAPs  and   other
telecommunications  service providers without  the need to  deploy fiber all the
way to end users' premises. The Company provides point-to-point wireless digital
circuits ranging  in capacity  from DS-1  (capable of  carrying 24  simultaneous
voice conversations at 1.544 Mbps) to DS-3 (capable of carrying 672 simultaneous
voice  conversations at 45 Mbps). The  Company's wireless broadband services are
engineered to provide 99.999% availability,  with better than a 10-13  (unfaded)
bit  error rate.  This level of  availability exceeds the  performance of copper
based networks  and  is a  viable  alternative  to fiber  based  networks.  When
measured  as the  total amount  of time  "out of  service" over  a year, 99.999%
availability under conditions of no path fading equates to less than six minutes
of down-time  compared to  a  range of  four hours  to  44 hours  of  historical
performance  of  similar copper-based  LEC  circuits. In  addition,  the Company
believes that  ART's  last  mile  solution is  competitively  priced  with  most
broadband wireline solutions.
 
    The  Company's  initial target  customers include  CAPs, IXCs,  cellular and
mobile radio service  providers and  ISPs. The  Company's services  may also  be
attractive  to certain LECs which do  not currently have broadband networks that
reach the majority of their customers. The Company has entered into a  strategic
distribution  agreement with  Ameritech for  delivery of  the Company's wireless
broadband services  throughout  Ameritech's  midwest operating  region  and  for
certain  large customers located outside its region. See "-- Strategic Alliances
- -- Ameritech Strategic Distribution Agreement."
 
    The Company  believes that  the following  factors provide  it with  certain
significant  competitive  advantages  in offering  broadband  last  mile access,
including:
 
                                       36
<PAGE>
    - The characteristics  of  38  GHz technology  (high  data  transfer  rates,
      significant  channel  capacity,  rapid deployment,  easy  installation and
      efficient network design) are ideal for the provision of last mile access.
 
    - The Company  minimizes its  initial capital  expenditures because  of  the
      installation-to-meet-demand  and  redeployable  nature  of  the  Company's
      wireless broadband  equipment, as  compared to  the significant  cost  and
      expense of installation of fiber based networks.
 
    - As   one  of  the   first  38  GHz  service   providers,  the  Company  is
      well-positioned to capture a large percentage of early adopters, which are
      generally among the heaviest users.
 
    - The Company's industry relationships should  enable it to forge  strategic
      alliances   with   other  carriers,   equipment  vendors   and  technology
      development companies,  thus  gaining  access  to  important  channels  of
      distribution and early deployment of advanced technologies.
 
    - The  scope  of the  Company's  market area  enables  it to  offer wireless
      broadband services  targeting  much  of the  United  States's  addressable
      business market.
 
    As  regulatory and competitive conditions permit, the Company's market focus
will evolve  from a  wholesale  "carrier's carrier"  orientation to  the  retail
provision  of services directly to  government and commercial end-user customers
of telecommunications services. The Company will focus on its initial  wholesale
"carrier's  carrier" strategy at least  through the first half  of 1997. At that
time, the  Company anticipates  it will  have developed  its customer  base  and
market  presence to a  level that will  enable the Company  to expand its direct
sales efforts. At the  same time, the Company  anticipates it will commence  the
development  of switched services to expand the Company's service offerings both
geographically and  demographically,  to  business  and  residential  customers,
offering  a  wider  array  of voice,  data,  Internet  and  multimedia services,
depending on further advances in wireless technology.
 
BUSINESS STRATEGY
 
    ART began providing 38 GHz wireless broadband services in the fourth quarter
of 1995 and has generated only nominal revenues from such services to date.  The
Company is seeking to capitalize on its broad footprint of 38 GHz authorizations
to  become a leading provider of wireless broadband solutions to a diverse group
of traditional and emerging telecommunications  service providers and end  users
of  telecommunications services.  The Company  plans to  implement the following
strategic initiatives to achieve this objective:
 
    - EXPLOIT SPECTRUM POSITION IN KEY  MARKETS. Upon completion of its  pending
     acquisition of the CommcoCCC Assets, the Company will own or manage a total
     of  237  authorizations  that will  allow  it  to provide  38  GHz wireless
     broadband services  in 169  U.S.  markets. The  Company currently  owns  or
     manages  108 authorizations (exclusive of  the CommcoCCC Assets) that allow
     it to provide 38 GHz wireless broadband services in 89 markets, 73 of which
     are owned by the Company and the  remaining 35 of which are managed by  the
     Company  through  the Company's  interests  in or  arrangements  with other
     companies. The  Company has  agreed to  acquire all  of the  authorizations
     which  it currently manages but does not own. These spectrum assets provide
     the Company with the foundation on which to create a large scale commercial
     system of 38 GHz  wireless broadband operations. As  of June 28, 1996,  the
     Company  was operating  revenue-generating, wireless broadband  links in 15
     cities. The Company plans to continue  to build out its infrastructure  and
     to  intensify its marketing effort in its  market areas in order to exploit
     the value inherent in its spectrum assets. See " -- Agreements Relating  to
     Licenses  and Authorizations." The  Company may seek  to acquire additional
     spectrum rights  in  new  and  existing markets  in  order  to  expand  its
     geographic footprint or enhance its services.
 
    -  MARKET INITIALLY  AS A  CARRIER'S CARRIER.  The Company's  initial target
     customers include CAPs, IXCs, cellular  and mobile radio service  providers
     and  ISPs. The Company's wireless broadband  services enable CAPs to extend
     their broadband services to locations where it is either not cost-efficient
     or too  difficult to  extend  their fiber  optic  network due  to  physical
     limitations, franchise
 
                                       37
<PAGE>
     fees  or other restrictions. The Company's  services may also be attractive
     to certain LECs, which generally  do not currently have broadband  networks
     capable of reaching the majority of their customers. All telecommunications
     service  providers can use the Company's services as alternate or redundant
     routes to  increase network  reliability. The  Company has  entered into  a
     strategic  distribution  agreement (the  "Ameritech  Strategic Distribution
     Agreement")  with  Ameritech  Corp.  ("Ameritech")  for  delivery  of   the
     Company's   wireless  broadband  services  throughout  Ameritech's  midwest
     operating region  and  for  certain large  customers  located  outside  its
     region. The Company currently provides services to Ameritech, Bell Atlantic
     NYNEX  Mobile,  UUNet,  Electric  Lightwave,  NEXTLINK,  American  Personal
     Communications, American Show  Management, Capital  Area Internet  Service,
     Brooks  Fiber Communications and  Western Wireless, among  others. See " --
     Customers and  Applications."  As  regulatory  and  competitive  conditions
     permit  and as the Company's customer base and market presence develop, the
     Company expects  that  its  market  focus  will  expand  from  a  wholesale
     "carrier's carrier" to include provision of services directly to commercial
     end users.
 
    -  PURSUE  OPPORTUNITIES TO  PROVIDE VALUE-ADDED  SERVICES. The  Company has
     identified and  plans to  pursue additional  market niches  with  immediate
     needs  for reliable, high bandwidth last mile access services. For example,
     the market for  Internet services  urgently requires  broadband "pipes"  to
     facilitate  high speed  access for corporate  users. The amount  of time it
     takes to  download  graphics  and  images from  the  Internet  to  personal
     computers over dial-up copper circuits hinders demand for the Internet. For
     example, a 38 GHz DS-1 circuit (1.544 Mbps), linking a corporate user to an
     ISP's  POP, is approximately 53 times faster than a 28.8 kbps dial-up modem
     and  12  times  faster  than  the  fastest  ISDN  connection  (128   Kbps).
     Alternatively,  one 38 GHz DS-3 link at 45 Mbps can currently transfer data
     at a rate that is  over 1,500 times the rate  of the fastest dial-up  modem
     currently  in use (28.8  Kbps) and over  350 times the  rate of the fastest
     ISDN line currently in use (128 Kbps). Each of the Company's DS-3 links can
     support 28 DS-1 circuits per channel. The Company is pursuing agreements to
     package its  38 GHz  solutions with  the services  of leading  ISPs.  Other
     potential   value-added  uses   include  desktop   videoconferencing,  high
     resolution imaging  for healthcare  and  law enforcement  applications  and
     video  on  demand.  The Company  may  also decide  to  offer switched-based
     services to  end  users  who  desire  a  single  source  telecommunications
     solution.
 
    -  MAINTAIN  TECHNOLOGY LEADERSHIP  IN SPECTRUM  MANAGEMENT. The  Company is
     currently developing proprietary site selection and network design software
     which it believes will provide for faster site development at a lower cost.
     In addition, through the Company's internal technology development efforts,
     as well as on-going participation in equipment manufacturers' research  and
     development  activities, the  Company is  seeking to  achieve a competitive
     advantage through proprietary methods designed to increase the capacity and
     quality of its networks.
 
    - ESTABLISH AND  EXPAND KEY STRATEGIC  ALLIANCES. The Company  has and  will
     seek  to continue to  establish key strategic  alliances with major service
     providers,  equipment  manufacturers,  systems  integrators  and   enhanced
     service  providers.  Ameritech  Development Corp.  owns  a  5.5% beneficial
     equity interest  in the  Company as  of June  28, 1996  (4.3% after  giving
     effect  to  the  Common  Stock Offering)  and  entered  into  the Ameritech
     Strategic Distribution  Agreement  in  April 1996.  The  Company  also  has
     agreements   with  Harris  Corporation,  Farinon  Division  ("Harris")  for
     marketing ART's 38 GHz services to  PCS providers and with GTE  Corporation
     for  installation, field servicing and network monitoring. In addition, the
     Company is  seeking to  develop relationships  with a  number of  equipment
     manufacturers focusing on 38 GHz technology development, wireless broadband
     standards  and joint sales efforts. The  Company plans to utilize strategic
     alliances to bundle its services with those of its partners to provide  for
     alternative  distribution  channels  and to  gain  access  to technological
     advancements. See "-- Strategic Alliances."
 
                                       38
<PAGE>
WIRELESS BROADBAND SERVICES
 
    The Company's wireless broadband links  deliver high quality voice and  data
transmissions  at a level of performance which exceeds the performance of copper
based networks and is  a viable alternative to  fiber optic based networks.  The
Company  provides point-to-point  wireless digital circuits  ranging in capacity
from DS-1  (capable of  carrying 24  simultaneous voice  conversations at  1.544
Mbps)  to DS-3 (capable  of carrying 672 simultaneous  voice conversations at 45
Mbps). The Company believes that it generally owns or manages sufficient 38  GHz
bandwidth  to  satisfy  the  anticipated  service  requirements  of  its  target
customers in  each of  the  Company's existing  markets  and the  additional  78
markets to be acquired under the CommcoCCC Agreement.
 
    Significant  features of  the Company's wireless  broadband services include
(i) sufficient bandwidth and  flexibility in each channel  for most present  day
applications,  (ii) minimal  channel interference from  other sources, resulting
from dedicated spectrum, (iii)  range of up to  five miles between  transmission
links  (depending  upon  moisture conditions),  (iv)  performance  engineered to
provide a minimum of 99.999% availability, (v) transmission accuracy  engineered
to provide bit error rates of better than 10-13 (unfaded), (vi) optional forward
error  correction for  even higher data  reliability, insuring  the integrity of
transmitted data over  wireless broadband paths,  (vii) rapid deployment  (where
roof  rights have  been previously obtained),  (viii) 24-hour, seven-days-a-week
network monitoring  by the  Company's network  management control  center,  (ix)
available  nationwide  four-hour  emergency  restoral  time  from  GTE  in  most
circumstances and (x) optional  "hot" standby links that  remain powered up  and
switch "on line" if the primary link fails.
 
    Each  of ART's wireless  broadband links consists  of paired millimeter wave
radio transceivers installed at a distance of up to five miles from one  another
within  a direct line of  sight. The transceivers currently  used by the Company
are supplied principally by P-Com, Inc. ("P-Com") and are installed primarily on
rooftops and on other tall structures. In order to deploy its links quickly, the
Company plans to  obtain roof  rights on buildings  with fiber  optic points  of
termination  for transceiver sites. To accomplish this objective, the Company is
developing proprietary site  selection and  network design  software which  will
significantly  reduce the  amount of  time necessary  to select  optimal network
sites. In coordination with its marketing plans, the Company will dispatch  site
acquisition  specialists  to such  locations  to obtain  renewable  options. The
Company intends  to use  a  combination of  its  own employees  and  independent
contractors for site acquisition.
 
CUSTOMERS AND APPLICATIONS
 
    The  Company introduced its wireless broadband services in November 1995 and
began marketing its  services in January  1996. The Company  has generated  only
nominal  revenues  from  its  operations  to  date.  Currently,  the  Company is
providing or has received orders to provide carrier's carrier wireless broadband
services to CAPs, a  LEC, ISPs, cellular and  mobile carriers and several  IXCs,
and  is in the process of becoming a qualified vendor to all the major IXCs. The
Company currently provides  services to Ameritech,  Bell Atlantic NYNEX  Mobile,
UUNet,  Electric Lightwave, NEXTLINK, American Personal Communications, American
Show Management, Capital Area Internet Service, Brooks Fiber Communications  and
Western  Wireless, among others. As of June  28, 1996, the Company was operating
revenue-generating wireless broadband links in 15 cities.
 
    The Company currently provides, or anticipates providing, wireless broadband
services to the following types of customers, among others:
 
                                       39
<PAGE>
    COMPETITIVE ACCESS PROVIDERS AND LOCAL  EXCHANGE CARRIERS.  Currently,  CAPs
compete  with LECs by installing fiber optic  cable rings in the highest density
business locations to  connect with  long distance carriers  and for  intra-ring
transmissions.  Due to the  high cost inherent in  building fiber networks, CAPs
generally target  densely  populated areas  with  high concentrations  of  large
end-users.  In order  to reach  "off-net" customers,  CAPs must  either lease or
purchase facilities and services from  LECs or alternative suppliers until  such
time  as  it  becomes economical  to  extend  the CAP  fiber  networks  to these
customers.
 
    CAPs face  certain  implementation  obstacles that  the  Company's  wireless
broadband  services can assist in solving. CAPs need to reach new customers that
are off-net quickly  and inexpensively,  and are  expected to  prefer to  obtain
additional  network  facilities from  (and  share proprietary  information with)
someone other than  a direct competitor,  such as  a LEC. CAPs  can utilize  the
Company's  wireless broadband services as  an alternative to copper, fiber-based
or other  such network  facilities provided  to the  CAPs by  LECs (see  diagram
below),  to extend  their own  networks to reach  areas where  such extension is
neither  cost-efficient  nor  feasible,   because  of  rights-of-way  or   other
restrictions,  or to  provide redundant and  back-up capacity  to their existing
networks.
 
    The Company anticipates that LECs will encounter many of the same  obstacles
CAPs  are encountering in seeking to enhance their networks to deliver broadband
services. The  Company also  believes that  LECs  will seek  to utilize  38  GHz
technology to expand the range of their service offerings to match those offered
by  CAPs. Further,  as LECs  are permitted  to provide  inter-LATA long distance
services, they may seek to use 38 GHz technology to bypass other LECs outside of
their region. See  "-- Strategic Alliances  -- Ameritech Strategic  Distribution
Agreement."
 
                                   [GRAPHIC]
 
                                       40
<PAGE>
    INTERNET  SERVICE PROVIDERS.  The expanding  demand for Internet access, the
growing importance of  audio, video  and graphic Internet  applications to  both
business  and  consumers and  the  lack of  high  capacity access  through local
telephone company facilities  has created  a growing market  for ART's  wireless
broadband  services.  The  Company  offers  Internet  service  providers timely,
reliable and affordable access at the required high speed data rates -- both  45
Mbps  and 1.544 Mbps --  allowing ISPs to keep  pace with their customer growth.
The Company provides wireless  broadband links between  customers and their  ISP
providers  and between ISP POPs and the  Internet backbone. A single 38 GHz DS-1
circuit linking  a corporate  user to  an ISP's  POP is  approximately 53  times
faster  than a 28.8 Kbps dial-up modem and 12 times faster than the fastest ISDN
connection. Each of the Company's 38 GHz DS-3 links can support 28 DS-1 circuits
per channel or one DS-3 circuit per  channel, which can transfer data at a  rate
which  is over 1,500 times  the rate of the  fastest dial-up modems currently in
use (28 Kbps) and over 350 times the rate of the fastest ISDN lines currently in
use (128 Kbps).
 
                           [GRAPHIC]
 
                                       41
<PAGE>
    MOBILE COMMUNICATIONS SERVICE PROVIDERS.  ART's wireless broadband  services
can  help  cellular,  wireless dispatch  and  emerging PCS  carriers  compete in
expanding domestic  mobile communications  markets by  providing  cost-effective
backbone  network  connections between  cell sites,  base stations  and wireline
networks,  regardless  of  location.   Similar  38  GHz  mobile   communications
connections  have been proven  effective in Europe,  and ART's easily installed,
economical  wireless  broadband  links  can  give  domestic  mobile  carriers  a
competitive  edge  in  building  or  expanding  their  networks  through reduced
construction time and installation costs.
 
                               [GRAPHIC]
 
                                       42
<PAGE>
    INTER-EXCHANGE CARRIERS.  To minimize costly LEC access charges and to  gain
more  direct contact with the consumer,  IXCs can utilize the Company's wireless
broadband services  to connect  call origination  or termination  points  either
directly  to the  IXCs' POPs or  by way  of CAP intermediate  fiber rings. These
providers can  also  use  38 GHz  services  to  connect two  or  more  of  their
respective  POPs in  a single market  area. By utilizing  the Company's wireless
broadband services, IXCs can avoid the capacity barriers inherent in copper wire
connections, which have typically prevented them from providing their  customers
with  the end-to-end,  high bandwidth,  full digital  services available  from a
fiber optic or wireless-based  system. Wireless broadband  services also may  be
utilized  to  provide carriers  with  viable, cost-efficient  physical diversity
routes (I.E., back-up capacity)  for traffic in  situations when primary  routes
become   incapacitated   or  network   reliability  concerns   demand  alternate
telecommunications paths.
 
                                [GRAPHIC]
 
                                       43
<PAGE>
    PRIVATE USER NETWORKS.  ART's  wireless broadband services enable  business,
government and other heavy usage customers to create efficient, high speed, high
capacity  private voice, data and video communications networks within and among
their local  facilities and  buildings.  These customers  include  universities,
hospitals,  hotels, shopping centers  and multi-location manufacturing, business
and  governmental  institutions.  Working  directly  with  ART  or  through  ART
resellers,  customers will be able to  access cost-effective alternatives to LEC
copper networks.
 
    Providing high speed data transmission and real time communications services
by  linking   customer  computers   in  local,   metropolitan  and   wide   area
configurations  will be an important part  of ART's private networking business.
The ability  to  send large  amounts  of data  quickly  and efficiently  and  to
interconnect  personal  computers  both  within and  among  buildings  in campus
settings is  a growing  customer  need. ART's  wireless broadband  services  are
designed to serve this rapidly expanding market.
 
                               [GRAPHIC]
 
                                       44
<PAGE>
    INTERACTIVE VIDEO SERVICES USERS.  ART's wireless broadband services provide
high  speed, high capacity  access to communications  networks for customers who
require  reliable  videoconferencing,  video  on  demand,  and  Internet   video
services.  The  Company  believes the  increasing  popularity and  use  of these
services, particularly by  large business  and government  customers, provide  a
promising market for ART's wireless links. Videoconferencing requires high speed
communications  both to and  from the participants.  The Company's services meet
this requirement for high bandwidth, full duplex communications.
 
                                   [GRAPHIC]
 
MARKETING PLANS
 
    In January  1996,  the Company  commenced  implementation of  its  marketing
program.  The Company  is addressing its  initial target markets  as a carrier's
carrier, while building the internal capability to expand its marketing  efforts
to  include direct sales to end users of its services. The Company is augmenting
its marketing  and  sales  channels through  resale  agreements  with  strategic
marketing  partners and through alliances with  selected CAPs, LECs, ISPs, IXCs,
interconnect providers (PBX suppliers), LAN, MAN and WAN systems integrators and
other telecommunications equipment manufacturers and service providers.
 
    The Company's  internal  salesforce  is currently  marketing  the  Company's
wireless  broadband services  by (i) performing  field demonstrations  of 38 GHz
service, (ii) making presentations at  industry trade shows, (iii) providing  an
interactive  Internet  home  page, (iv)  running  promotional  advertisements in
selected trade media and (v)  conducting extensive one-on-one presentations  and
demonstrations  through  its direct  sales  force with  major telecommunications
service providers and end users of telecommunications services.
 
    The Company currently expects to price  its services on a monthly  flat-rate
non-distance  sensitive basis. As  a non-dominant carrier, ART  does not have to
cost-justify its rates to regulatory bodies  and usually has a wide latitude  in
changing  customer-specific  rates.  As  a result,  ART  expects  to  enter into
customer and service specific arrangements,  which include volume, capacity  and
term  discounts and customized billing and payment options. The services offered
by ART are expected to be competitively
 
                                       45
<PAGE>
priced with those of the incumbent LECs. The Company also intends to charge  for
installation and network monitoring services where appropriate. The Company also
anticipates  offering metered  services to various  end users  at an appropriate
point in the future.
 
38 GHZ WIRELESS BROADBAND LICENSES AND AUTHORIZATIONS
 
    The Company was  granted the first  of its authorizations  to construct  and
operate  38 GHz wireless  broadband facilities in  February 1995. Authorizations
for facilities that are  not constructed are referred  to in this Prospectus  as
"construction  permits"; authorizations for facilities  that are constructed are
referred to in this Prospectus as  "licenses". Upon completion of the  CommcoCCC
Acquisition,  the Company will own or manage  a total of 237 authorizations that
will allow it to provide 38 GHz wireless broadband services in 169 U.S. markets.
The Company  currently owns  or  manages 108  authorizations (exclusive  of  the
CommcoCCC Assets) that allow it to provide 38 GHz wireless broadband services in
89  markets, 73 of which are owned by  the Company and the remaining 35 of which
are managed by the  Company through the Company's  interests in or  arrangements
with other companies.
 
    The table below lists, for the top 100 U.S. markets, the amount of bandwidth
covered  by authorizations which  the Company owns, manages  or has a definitive
agreement to acquire in the  top 100 U.S. markets,  in descending order of  size
based on the estimated population of the market:
 
<TABLE>
<CAPTION>
                                                  BANDWIDTH COVERED BY AUTHORIZATIONS (MHZ)
                                           --------------------------------------------------------
                                                                             UNDER
                                                                          DEFINITIVE
                                                                         AGREEMENT TO
                 MARKET                       OWNED       MANAGED (1)       ACQUIRE        TOTAL
- -----------------------------------------  -----------  ---------------  -------------     -----
<S>                                        <C>          <C>              <C>            <C>
300 MHZ OR MORE MARKETS
New York, NY                                      300         --              --               300
Washington, D.C.                                  300         --              --               300
Boston, MA                                        200         --                 100           300
Baltimore, MD                                     200            100          --               300
Cincinnati, OH                                    100         --                 200           300
Portland, OR                                   --                100             200           300
Norfolk/Virginia Beach, VA                     --                100             300           400
Columbus, OH                                   --                100             200           300
Providence, RI/Fall River, MA                     200         --                 200           400
Memphis, TN                                       100         --                 200           300
Oklahoma City, OK                              --                100             200           300
Birmingham, AL                                    100         --                 200           300
Buffalo/Niagara Falls, NY                         300         --                 100           400
Dayton/Springfield, OH                            100            100             100           300
Richmond/Petersburg, VA                           100         --                 200           300
Rochester, NY                                     300         --                 200           500
Hartford, CT                                      200            100             200           500
Albany/Schenectady, NY                            300         --                 200           500
Knoxville, TN                                     100         --                 200           300
New Haven/Waterbury, CT                           200         --                 100           300
Syracuse, NY                                      200         --                 100           300
Harrisburg, PA                                    200         --                 100           300
Scranton/Wilkes-Barre, PA                         300         --                 100           400
Springfield/Holyoke, MA                           200         --                 200           400
Jackson, MS                                       100         --                 200           300
Shreveport, LA                                    100         --                 200           300
</TABLE>
 
                                       46
<PAGE>
<TABLE>
<CAPTION>
                                                  BANDWIDTH COVERED BY AUTHORIZATIONS (MHZ)
                                           --------------------------------------------------------
                                                                             UNDER
                                                                          DEFINITIVE
                                                                         AGREEMENT TO
                 MARKET                       OWNED       MANAGED (1)       ACQUIRE        TOTAL
- -----------------------------------------  -----------  ---------------  -------------     -----
<S>                                        <C>          <C>              <C>            <C>
200 MHZ MARKETS
Philadelphia, PA/Trenton, NJ                      200         --              --               200
Miami/Fort Lauderdale, FL                         100         --                 100           200
Cleveland/Akron, OH                               100         --                 100           200
Seattle/Tacoma, WA                             --                100             100           200
St. Louis, MO                                     100         --                 100           200
Pittsburgh, PA                                    200         --              --               200
Charlotte/Gastonia, NC                         --             --                 200           200
Nashville, TN                                     100         --                 100           200
Indianapolis, IN                                  100         --                 100           200
Louisville, KY                                    100         --                 100           200
Greensboro/Winston-Salem, NC                   --                100             100           200
Las Vegas, NV                                  --                100             100           200
Austin, TX                                     --                100             100           200
Grand Rapids, MI                               --                100             100           200
Omaha, NE                                      --             --                 200           200
Honolulu, HI                                   --                100             100           200
Albuquerque, NM                                --                100             100           200
Des Moines, IA                                    100         --                 100           200
Tucson, AZ                                     --                100             100           200
El Paso, TX                                    --             --                 200           200
Worcester, MA                                     200         --                  --           200
Allentown/Bethlehem, PA                           200         --              --               200
Baton Rouge, LA                                   100         --                 100           200
Charleston, SC                                    100            100          --               200
Mobile, AL                                        100            100          --               200
 
100 MHZ MARKETS
Chicago, IL                                       100             --              --           100
Detroit, MI                                        --             --             100           100
Dallas/Fort Worth, TX                             100             --              --           100
Houston, TX                                       100             --              --           100
Atlanta, GA                                       100             --              --           100
Minneapolis, MN                                   100             --              --           100
Phoenix, AZ                                        --            100              --           100
San Diego, CA                                      --            100              --           100
Tampa-St. Petersburg, FL                           --             --             100           100
Denver, CO                                         --            100              --           100
Kansas City, MO                                   100             --              --           100
Sacramento, CA                                     --            100              --           100
Milwaukee, WI                                      --             --             100           100
San Antonio, TX                                   100             --              --           100
Salt Lake City, UT                                 --            100              --           100
Orlando, FL                                        --             --             100           100
New Orleans, LA                                   100             --              --           100
Raleigh-Durham, NC                                 --             --             100           100
Little Rock, AR                                    --             --             100           100
Tulsa, OK                                          --             --             100           100
Greenville/Spartanburg, SC                         --             --             100           100
</TABLE>
 
                                       47
<PAGE>
<TABLE>
<CAPTION>
                                                  BANDWIDTH COVERED BY AUTHORIZATIONS (MHZ)
                                           --------------------------------------------------------
                                                                             UNDER
                                                                          DEFINITIVE
                                                                         AGREEMENT TO
                 MARKET                       OWNED       MANAGED (1)       ACQUIRE        TOTAL
- -----------------------------------------  -----------  ---------------  -------------     -----
<S>                                        <C>          <C>              <C>            <C>
Toledo, OH                                         --             --             100           100
Spokane, WA                                        --            100              --           100
Kingsport, TN/Bristol, VA                          --             --             100           100
Fort Wayne, IN                                     --             --             100           100
Madison, WI                                       100             --              --           100
Wichita, KS                                       100             --              --           100
Springfield, MO                                    --             --             100           100
Sarasota/Bradenton, FL                             --             --             100           100
Corpus Christi, TX                                 --             --             100           100
Chattanooga, TN                                    --             --             100           100
</TABLE>
 
- ------------------------------
(1)  Includes authorizations (i) held by ART West, (ii) managed by ART under the
     DCT  services agreement  and (iii) managed  under the  Telecom One services
     agreement pursuant  to  a  revenue-sharing arrangement.  Does  not  include
     authorizations  included in the  CommcoCCC Assets which  are managed by the
     Company on  a  short-term basis,  pending  the CommcoCCC  Acquisition.  The
     Company  recently  has entered  into definitive  agreements to  acquire all
     outstanding interests  in the  authorizations  held by  ART West,  DCT  and
     Telecom   One.  See  "Business  --  Agreements  Relating  to  Licenses  and
     Authorizations."
 
    In addition to  the above  authorizations, the Company  has 71  applications
pending  before  the  FCC for  additional  authorizations. However,  due  to the
"freeze" imposed by  the NPRM and  the conflicts with  other applicants in  same
markets,  there can be  no assurance that  it or any  other company will receive
additional authorizations with  respect to any  pending applications. See  "Risk
Factors -- Government Regulation" and "-- Government Regulation."
 
    Excluding  the  CommcoCCC  Assets,  the Company  presently  owns  or manages
between 100 and  300 MHz of  transmission capacity within  each of its  markets.
Because  38 GHz paths  are very narrow  and because certain  microwave paths can
intersect each  other  without  creating  interference,  each  market  area  can
accommodate  thousands  of  paths. The  Company  believes it  generally  owns or
manages  sufficient  38  GHz  bandwidth  to  satisfy  the  anticipated   service
requirements  of its target customers in  each of the Company's existing markets
and the additional  80 markets  to be  acquired under  the CommcoCCC  Agreement.
Consistent  with the Company's  growth strategy, the Company  may seek to obtain
additional spectrum  by  either  leasing  excess  capacity  from  other  38  GHz
licensees,  entering into management agreements  or acquiring interests in other
38 GHz authorizations. See "Risk Factors -- Acquisition of Additional  Bandwidth
in Selected Areas."
 
    Under  the terms of its 31  construction permits (exclusive of the CommcoCCC
Assets), the Company must complete  construction of facilities for the  majority
of  such construction permits  between mid-August and  mid-September 1996. Under
the terms of the CommcoCCC authorizations and the Company's management agreement
with CommcoCCC, the Company must  complete construction of facilities for  eight
construction  permits by mid-September 1996, 39 construction permits by December
1996 and the remaining 82 construction permits between mid-April and  mid-August
1997.  The Company has begun installing the number of links required to complete
construction and currently expects it will meet the FCC deadlines. However,  the
FCC  may impose more stringent construction  requirements, as it has proposed to
do in the NPRM, which may jeopardize the status of the Company's authorizations.
All of the 38  GHz licenses owned or  to be acquired by  the Company are due  to
expire  in February 2001. The Company believes  that, in keeping with common FCC
practices, the  licenses will  be renewed  for successive  10-year periods  upon
expiration.
 
                                       48
<PAGE>
AGREEMENTS RELATING TO LICENSES AND AUTHORIZATIONS
 
    COMMCOCCC  ACQUISITION.    On July  3,  1996,  the Company  entered  into an
agreement (the "CommcoCCC Agreement") to  acquire 129 38 GHz wireless  broadband
authorizations  (the "CommcoCCC  Assets") from  CommcoCCC, Inc.  (the "CommcoCCC
Acquisition") in exchange for 16,500,000  shares of Common Stock. CommcoCCC  was
formed in a transaction arranged by Columbia Capital Corporation to acquire, own
and  operate the 38 GHz authorizations owned by Columbia Capital Corporation and
its affiliates and those  owned by Commco, L.L.C.  The CommcoCCC Acquisition  is
subject  to various  conditions including  receipt of  FCC and  other approvals,
receipt by CommcoCCC of an opinion as to the tax-free nature of the transaction,
consummation of the  Offerings on  terms reasonably  satisfactory to  CommcoCCC,
minimum  population coverage requirements for  the authorizations of the Company
and CommcoCCC, accuracy  of representations and  warranties except for  breaches
that  do not  have in  the aggregate  a material  adverse effect,  no pending or
threatened material litigation and other customary closing conditions. There can
be no assurance that  all such conditions will  be satisfied. In particular,  to
obtain  FCC approval, the  Company will need  to make certain "anti-trafficking"
showings and may need certain waivers or  consents from the FCC. The FCC may  be
unwilling  to grant its approval or may grant its approval subject to conditions
that may be adverse to the Company. The CommcoCCC Agreement may be terminated by
either party if the Offerings  are not completed within 90  days of the date  of
the  CommcoCCC  Agreement or  if the  CommcoCCC  Acquisition is  not consummated
within one year of  the date of  the CommcoCCC Agreement.  See "Risk Factors  --
Risk of Non-Consummation of CommcoCCC Acquisition."
 
    In  the CommcoCCC Agreement, the Company  and Telecom have each agreed that,
prior to the consummation of the transaction, except in certain circumstances or
with the consent of CommcoCCC, they  will not issue equity, incur debt,  acquire
spectrum,  make investments, consolidate, merge or sell all or substantially all
of its  assets. CommcoCCC  has  entered into  a  management agreement  with  the
Company  pursuant  to  which the  Company  bears the  responsibility  during the
pendency of  the CommcoCCC  Acquisition  to construct,  manage and  operate  the
CommcoCCC  Assets, consistent  with FCC  rules. Under  the management agreement,
CommcoCCC is  obligated  to  reimburse  ART for  up  to  $100,000  of  operating
expenses,  which obligation  will be cancelled  if the  CommcoCCC Acquisition is
consummated. In the event the management agreement is terminated other than as a
result of the consummation of the CommcoCCC Acquisition, CommcoCCC is  obligated
to  purchase and  ART is obligated  to sell  at the Company's  original cost the
equipment purchased by ART necessary  to meet the FCC construction  requirements
for the CommcoCCC authorizations.
 
    The  stockholders  of  CommcoCCC  loaned the  Company  $3.0  million payable
September 30, 1996  pursuant to  a subordinated bridge  financing facility  (the
"CommcoCCC   Financing")  and,  in  connection  therewith,  received  three-year
warrants to purchase  50,000 shares of  Common Stock  at a price  of $15.00  per
share  (the  "CommcoCCC  Warrants"). The  CommcoCCC  Financing is  secured  by a
security interest in all of the assets of the Company, including a pledge of the
Company's stock in Telecom. If the CommcoCCC Financing is not paid in full  when
due, the unpaid principal and interest could be converted into Common Stock on a
formula  basis at  the option  of the holders.  The CommcoCCC  Financing will be
repaid with the proceeds of the Offerings.
 
    The Company has given Commco, L.L.C., a stockholder of CommcoCCC, an  option
(the  "Commco Option")  to purchase  one authorization  in each  of 12 specified
market areas in which the Company  will have more than one authorization,  which
authorizations  cover  in the  aggregate  approximately 19  million  people. The
Commco Option  will be  exercisable only  if (i)  the CommcoCCC  Acquisition  is
consummated  and (ii) Commco, L.L.C.  obtains authorizations pursuant to certain
pending applications frozen under the NPRM in market areas covering an aggregate
population of at least 40  million people, and will  terminate on the date  nine
months  after the consummation of the  Common Stock Offering. The purchase price
for any  authorizations acquired  under the  Commco Option  is determined  by  a
formula  based  upon the  fair market  value at  the time  the Commco  Option is
exercised of up to approximately 2,600,000 shares of Common Stock depending upon
the number of authorizations
 
                                       49
<PAGE>
purchased. The purchase price  is payable in  cash or, if  the Commco Option  is
exercised  within  the later  of 120  days  after the  closing of  the CommcoCCC
Acquisition or the date of grant by  the FCC of the authorizations necessary  to
exercise  the Commco Option,  with a two-year  note secured by  shares of Common
Stock having a value on  the date of exercise equal  to two times the  principal
amount of the note.
 
    In  arranging the CommcoCCC Acquisition, Columbia Capital Corporation agreed
not to  compete  with  the  Company  in  the  provision  of  wireless  broadband
telecommunication  services in  the 38  GHz band of  the radio  spectrum and has
granted the Company a right of first offer to acquire any 38 GHz  authorizations
that  Columbia Capital Corporation  or its affiliates may  acquire in the future
with respect to their pending applications.
 
    Promptly upon closing of the  CommcoCCC Acquisition, the Company has  agreed
to nominate one individual designated by CommcoCCC's stockholders and acceptable
to the Company as a director of the Company.
 
    In  late  1994 and  1995, Columbia  Capital Corporation  and certain  of its
affiliates ("Columbia")  entered into  several  letter agreements  (the  "Letter
Agreements")  with Video/Phone  Systems, Inc.  ("Video/Phone"). In consideration
for services to  be rendered under  the Letter Agreements,  Columbia granted  or
agreed  to grant to Video/Phone options to purchase minority equity interests in
entities formed or to be  formed to apply for  38 GHz licenses. Columbia  agreed
not  to assign these licenses to any  person controlling, controlled by or under
common control with Columbia  unless such transferee  granted to Video/Phone  an
equivalent option. The CommcoCCC Assets include 67 authorizations transferred by
Columbia  to CommcoCCC, subject to FCC approval. Columbia and Video/Phone are in
a dispute with respect to the  performance and obligations of the parties  under
the  Letter Agreements. Columbia  has agreed to indemnify  and hold harmless the
Company with respect to any loss or damage resulting from the Letter Agreements.
 
    EMI ACQUISITION.  On April 4, 1995,  ART entered into an agreement with  EMI
Communications  Corporation ("EMI") to acquire EMI's  thirty two 38 GHz wireless
broadband licenses and  related assets  in the northeastern  United States  (the
"EMI Assets") in exchange for $3.0 million in cash and a $1.5 million three-year
non-negotiable  and  non-transferable  promissory  note  (the  "EMI  Note").  In
November 1995, ART assigned all of its rights and obligations under the purchase
agreement to Telecom.  The FCC  subsequently approved  the transfer  of the  EMI
Assets to Telecom, and the EMI Assets were acquired by Telecom in November 1995.
ART  has also agreed to provide wireless  broadband services to certain of EMI's
customers on behalf of EMI for the terms provided in such EMI service agreements
for a period  of five years  from the date  of the agreement  and EMI agreed  to
provide  certain services to Telecom for an  initial period of one year from the
date of the agreement. See "Description of Certain Indebtedness -- EMI Note."
 
    ART WEST JOINT VENTURE.  On April 4, 1995, ART and Extended  Communications,
Inc.  ("Extended")  entered  into  a  joint  venture  agreement  (the  "ART West
Agreement") resulting in the formation of ART West Joint Venture ("ART West"), a
Delaware partnership equally owned by ART  and Extended. Under the terms of  the
ART West Agreement, ART and Extended agreed to transfer to ART West all of their
respective  interests  in  all of  their  38 GHz  authorizations  (currently, 12
authorizations)  in  Alaska,  Arizona,  California,  Colorado,  Hawaii,   Idaho,
Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming (the "ART West
Markets"),  subject  to  FCC  approval. Under  a  separate  management agreement
between ART  and ART  West, ART  is obligated  to bear  all costs  and  expenses
relating  to construction, operation and management  of the ART West Markets and
has agreed to utilize  the ART West  authorizations before other  authorizations
owned  or managed by ART in the  ART West Markets. As compensation, ART receives
90% of the recurring revenues of ART West, with ART West receiving the remaining
10%. See "Certain Transactions -- ART West Joint Venture."
 
    In  June  1996,  the  Company  entered  into  an  agreement  (the  "Extended
Agreement")  to acquire Extended's interest in ART West for an aggregate of $6.0
million in cash, subject to adjustment and
 
                                       50
<PAGE>
subject to closing conditions including final FCC approval. Of the $6.0  million
purchase  price, $3.0 million is payable upon consummation of the Offerings as a
non-refundable deposit (the "ART West Deposit") and the balance is payable  upon
consummation  of the transaction.  Under this agreement, upon  payment by ART of
the ART West Deposit, Extended has agreed to surrender its rights under the  ART
West  Agreement (i) to participate in  the acquisition of additional licenses or
authorizations in certain of the ART West  Markets through ART West and (ii)  to
prohibit  the acquisition  by ART  of additional  licenses or  authorizations in
certain other ART West Markets.
 
    DCT SYSTEM PURCHASE AGREEMENTS.  On July 1, 1996 the Company entered into  a
definitive agreement (the "DCT Agreement") with DCT to acquire DCT's interest in
certain  38 GHz  licenses (the  "DCT Systems") in  exchange for  $3.6 million in
cash, subject to closing conditions including FCC approval. ART has entered into
an exclusive  services  agreement with  DCT  pursuant  to which  ART  bears  the
responsibility  for  the  construction,  operation  and  management  of  the DCT
Systems. The  agreement expires  on  December 31,  1998  and may  be  terminated
earlier  by DCT if the DCT Agreement terminates. Under the terms of the services
agreement, ART  is  obligated  to  bear  all  costs  and  expenses  relating  to
construction,  operation and management of the DCT Systems. As compensation, ART
is entitled to receive all  of the revenues generated  by the DCT Systems  until
December  31, 1996. From January 1, 1997 until  the later of January 1, 1998 and
the termination of the DCT  Agreement, a license fee equal  to 15% of the  gross
revenue  generated by  the DCT  Systems will  be paid  to DCT,  and thereafter a
license fee based on the number and  types of circuits operated by ART over  the
DCT  Systems will be paid to DCT. After  December 31, 1997, DCT has the right to
market to  third  parties utilizing  the  DCT Systems.  The  services  agreement
terminates  with respect to each DCT 38  GHz license upon the acquisition by ART
of such license. The  Company is currently  completing the initial  construction
requirements of the DCT Systems and expects such construction to be completed in
the third quarter of 1996.
 
    TELECOM  ONE SERVICES AGREEMENT.  On April 24, 1996, the Company and Telecom
One, Inc. ("Telecom One")  entered into a services  agreement (the "Telecom  One
Services  Agreement") pursuant to which the Company agreed to construct, operate
and manage all 38 GHz wireless broadband licenses and related telecommunications
systems owned by Telecom One that are granted by the FCC. At present Telecom One
has been granted two authorizations.  Under the Telecom One Services  Agreement,
the  Company is obligated to pay all costs and expenses related to construction,
operation and management of the  systems. As compensation, the Company  receives
90%  of the net revenues  generated by the systems  and Telecom One receives the
remaining 10% for ten years.
 
    TELECOM ONE PURCHASE AGREEMENT.  On  June 27, 1996, the Company and  Telecom
One  entered  into an  agreement  pursuant to  which  the Company  will acquire,
subject  to  FCC  approval,   from  Telecom  One   the  two  currently   granted
authorizations  that are the  subject of the Telecom  One Services Agreement for
approximately $111,000 in cash.  In addition, the Company  will have a right  of
first refusal on all future grants of 38 GHz authorizations to Telecom One.
 
STRATEGIC ALLIANCES
 
    AMERITECH  STRATEGIC DISTRIBUTION AGREEMENT.  On April 29, 1996, the Company
and Ameritech entered  into a three-year  strategic distribution agreement  (the
"Ameritech  Strategic  Distribution Agreement")  pursuant  to which  the Company
provides 38 GHz  services to Ameritech,  who will in  turn market the  Company's
services  under  the Ameritech  name.  Ameritech has  agreed  to be  the primary
provider of  the  Company's  services  in  the  midwest.  Under  the  agreement,
Ameritech  is targeting certain sales objectives and will spend internally up to
$7.0 million on its sales and  marketing of the Company's services. The  Company
believes  that  Ameritech's  sales and  marketing  expertise and  its  access to
extensive distribution channels within its region will accelerate the rollout of
the Company's business plan. The  Ameritech Strategic Distribution Agreement  is
subject to termination at any time by either party on 90 days' notice. See "Risk
Factors -- Dependence on Third Parties for Marketing and Service."
 
                                       51
<PAGE>
    GTE  SERVICES AGREEMENT.   On  April 25,  1996, the  Company entered  into a
two-year agreement with GTE Government Systems Corporation, a subsidiary of  GTE
Corporation  ("GTE"). GTE  will provide  equipment staging  and outfitting, site
preparation, equipment installation and  maintenance for the Company's  wireless
broadband services. Under the agreement, it is anticipated that GTE will perform
at least 75% of the Company's installations. The Company will pay a fee equal to
$1,550  for the installation of each link and a maintenance fee equal to $85 per
hour. The aggregate  amount of  the fee  will depend  on the  Company's rate  of
growth.  The Company believes that GTE's nationwide presence and experience will
provide the Company with efficient, quality installation and maintenance for its
nationwide services.  See  "Risk Factors  --  Dependence on  Third  Parties  for
Marketing and Service."
 
    GTE SOFTWARE LICENSE AGREEMENT.  On March 29, 1996, the Company entered into
a  software license agreement with  GTE's Network Management Organization. Under
this agreement, the Company  will purchase software  and centralize its  network
management functions to reduce costs and increase reliability. GTE's "Integrated
Network  Management  Products" enable  the Company  to quickly  identify service
interruptions and to simultaneously alert the field service teams, who are  able
to  restore services in a  timely manner. The Company will  pay a license fee of
approximately  $2.4  million   and  an   annual  maintenance   support  fee   of
approximately  $300,000. The  license fee will  be paid  in monthly installments
commencing January 1, 1997 of $67,000  per month, including interest. After  the
first  year,  fees  are subject  to  renegotiation  based on  market  prices and
conditions. See "Risk Factors -- Dependence  on Third Parties for Marketing  and
Service."
 
    HARRIS  AGREEMENTS.  On April 26,  1996, the Company and Harris Corporation,
Farinon Division ("Harris") entered into a one-year PCS marketing agreement (the
"Harris Marketing Agreement") pursuant  to which the  Company granted to  Harris
the  right to use  its 38 GHz  authorizations, including associated coordination
services, installation and  network monitoring and  field services. Pursuant  to
the  Harris Marketing Agreement, Harris agreed  to market the Company's services
in the  emerging PCS  market. The  Harris Marketing  Agreement is  automatically
renewable  for successive one-year terms unless  either party delivers notice of
non-renewal at  least 60  days prior  to  the end  of the  initial term  or  any
successive  term. The agreement  is also subject  to termination at  any time by
either party on 90 days' notice.
 
    Concurrently with the Harris Marketing Agreement, the parties entered into a
one-year purchase agreement (the "Harris Purchase Agreement") pursuant to  which
the  Company  agreed  to  purchase  certain  microwave  transmission  equipment,
software and services  relating thereto (the  "Harris Products"). The  agreement
sets  minimum purchase goals for the purchase by the Company of Harris Products.
If either the Harris Purchase Agreement or the Harris Marketing Agreement  shall
terminate, the other shall also terminate.
 
    TECHNOLOGY  DEVELOPMENT AGREEMENTS.   The  Company has  had discussions with
several microwave equipment or technology development companies for  development
of  technologies owned by such companies,  for advanced 38 GHz radios, highspeed
converters, innovative telecommunications platforms and other technologies.  The
Company will continue to monitor new developments in technology and may elect to
fund  research and development activity in  such new technology. The Company has
also entered  into  a  letter  of  intent  with  American  Wireless  Corporation
("American  Wireless") providing for  the funding by the  Company of $700,000 to
$1.0 million for research and development. In consideration of such funding, the
Company will  have  a first  right  to purchase  American  Wireless'  production
capacity  of the new  radios and will receive  a per-unit fee  on radios sold by
American Wireless  to  third  parties. See  "Certain  Transactions  --  American
Wireless  Development  Agreement."  This arrangement  is  subject  to definitive
documentation. The  Company  has entered  into  a non-binding  arrangement  with
QuestTV  providing for  an investment  of $1.5 million  in the  development of a
nationwide network of franchises offering  retail access to sophisticated  video
data  transmission and storage technology.  See "Certain Transactions -- QuestTV
Investment."
 
                                       52
<PAGE>
    The  Company  has  also  entered  into  a  letter  of  intent  with  Helioss
Communications  Corporation ("Helioss") for  the development of  advanced 38 GHz
radios. Under the letter of intent which is subject to definitive documentation,
the Company will fund  up to $1.0 million  of Helioss' research and  development
expenses.  The Company will have a right of first refusal on production capacity
of the radios, and  will receive a royalty  on the sale of  a certain number  of
radios to customers other than the Company.
 
    Through  June 15, 1996,  the Company has  incurred approximately $600,000 of
research and development expenses under such arrangements with several equipment
suppliers. There can be  no assurance that the  Company can complete  definitive
agreements  with  any  of such  suppliers  or  that such  suppliers  can develop
technologies with commercial value for the Company.
 
FOREIGN MARKETS
 
    The Company  is  exploring  the  possibilities  of  providing  its  wireless
broadband  services  in  other countries  including  Canada and  in  Europe. The
Company has  entered  into agreements  with  certain consultants  and  potential
partners  to identify foreign opportunities and expects to file applications for
licenses or to acquire 38 GHz licenses in several European countries. There  can
be  no  assurance that  the Company  can  acquire such  licenses or  develop and
operate such systems.
 
COMPETITION
 
    The telecommunications services industry is highly competitive. The  Company
has  only recently begun to market  its wireless broadband services to potential
customers and is currently providing services on a limited basis. In each market
area in  which  the Company  is  authorized  to provide  services,  the  Company
competes  or will compete with several other service providers and technologies.
The Company expects  to compete  primarily on  the basis  of wireless  broadband
service  features, quality, price, reliability, customer service and response to
customer needs.  The Company  faces significant  competition from  other 38  GHz
providers  and incumbent LECs, such  as the RBOCs. The  Company may also compete
with CAPs,  cable  television  operators,  electric  utilities,  LECs  operating
outside  their current local service  areas and IXCs. There  can be no assurance
that the Company will be able to compete effectively in any of its market areas.
 
    COMPETITION FROM 38 GHZ  SERVICE PROVIDERS.   The Company faces  competition
from  other 38  GHz service  providers, such as  WinStar and  BizTel, within its
market areas.  In  many cases,  one  or both  of  these service  providers  hold
licenses  to operate in  other portions of  the 38 GHz  band in geographic areas
which encompass  or  overlap the  Company's  market  areas. In  certain  of  the
Company's market areas, other 38 GHz service providers may have a longer history
of  operations, a larger geographic footprint or substantially greater financial
resources  than  the   Company.  WinStar   commenced  its   38  GHz   operations
approximately  one year prior to the Company, has raised significant capital and
has the competitive  advantages inherent  in being the  first to  market 38  GHz
services.  In addition  to WinStar  and BizTel,  at least  one other substantial
entity, Milliwave, L.P. ("Milliwave"), and several dozen smaller ones have  been
granted  38 GHz authorizations in geographic  regions in which the Company plans
to operate.  Winstar  has recently  entered  into a  definitive  agreement  with
Milliwave  to acquire Milliwave's 38 GHz  licenses, subject to FCC approval, and
has agreed to manage such licenses pending the consummation of such acquisition.
Due to the  relative ease  and speed  of deployment  of 38  GHz technology,  the
Company  could  face intense  price  competition and  competition  for customers
(including other telecommunications service providers) from other 38 GHz service
providers.
 
    The Company also faces potential competition from new entrants to the 38 GHz
market, including LECs and other leading telecommunications companies. The  NPRM
contemplates  an auction of certain spectrum assets, including fourteen proposed
100 MHz channels  (which are  similar to  those used  by the  Company) and  four
proposed  50  MHz channels  in the  38 GHz  spectrum band,  which have  not been
previously available  for  commercial  use.  See  "Risk  Factors  --  Government
Regulation."  The grant of  additional authorizations by  the FCC in  the 38 GHz
band, or other portions of the spectrum with similar
 
                                       53
<PAGE>
characteristics, could  result in  increased competition.  The Company  believes
that,  assuming that additional  channels are made available  as proposed by the
NPRM, additional  entities  having  greater resources  than  the  Company  could
acquire authorizations to provide 38 GHz services.
 
    COMPETITION  FROM  INCUMBENT  LECS.    The  Company  also  faces significant
competition from incumbent  LECs, irrespective  of whether they  provide 38  GHz
services.  Incumbent LECs have long-standing relationships with their customers,
generally own  significant  PCS  or  cellular  assets,  have  the  potential  to
subsidize  competitive services with  revenues from a  variety of businesses and
benefit from favorable  federal and state  policies and regulations.  Regulatory
decisions  and  recent legislation,  such  as the  Telecommunications  Act, have
partially deregulated the  telecommunications industry and  reduced barriers  to
entry  into new segments of the  industry. In particular, the Telecommunications
Act, among other things, (i)  enhances local exchange competition by  preempting
laws  prohibiting competition in the local exchange market, by requiring LECs to
provide fair and equal standards for interconnection and by requiring  incumbent
LECs  to provide unbundling of  services and (ii) permits  an RBOC to compete in
the  interLATA   long  distance   service   market  once   certain   competitive
characteristics  emerge in such  RBOC's service area.  The Company believes that
this trend towards  greater competition will  continue to provide  opportunities
for  broader entrance  into the  local exchange  markets. However,  as LECs face
increased competition,  regulatory decisions  are likely  to provide  them  with
increased  pricing  flexibility, which  in turn  may  result in  increased price
competition. There can  be no  assurance that such  increased price  competition
will not have a material adverse effect on the Company's results of operations.
 
    OTHER  COMPETITORS.  The Company may compete  with CAPs for the provision of
last mile access and additional services  in most of its market areas.  However,
the  Company believes that  many CAPs may  utilize 38 GHz  transmission links to
augment their own service offerings to IXCs and end users, and that the  Company
is  well positioned to provide such 38  GHz services to CAPs. However, there can
be no assurance that  CAPs will utilize  the Company's 38  GHz services or  that
CAPs  will not  seek to  acquire their  own 38  GHz licenses  or use  the 38 GHz
licenses of other licensees. Furthermore, the ability of CAPs to compete in  the
local  exchange market is limited by regulations relating to number portability,
dialing  parity  and  reasonable  interconnection.  The  Telecommunications  Act
requires  the FCC and the  states to implement regulations  that place CAPs on a
more equal  competitive footing  with  LECs. To  the  extent these  changes  are
implemented,  CAPs may be  able to compete more  effectively with LECs. However,
there can be no  assurance that CAPs  or 38 GHz service  providers, such as  the
Company,  will be  able to  compete effectively for  the provision  of last mile
access and other services.
 
    The Company  may  also  face competition  from  cable  television  operators
deploying  cable modems, which provide high speed data capability over installed
coaxial  cable  television  networks.  Although  cable  modems  are  not  widely
available  currently, the Company  believes that the  cable industry may support
the deployment of cable  modems to residential  cable customers through  methods
such  as price subsidies. Notwithstanding the cable industry's interest in rapid
deployment of  cable modems,  the  Company believes  that  in order  to  provide
broadband  capacity to  a significant  number of  business and  government users
cable operators will be required to spend significant time and capital in  order
to  upgrade  their existing  networks  to the  next  generation of  hybrid fiber
coaxial network  architecture. However,  there can  be no  assurance that  cable
television operators will not emerge as a source of competition to the Company.
 
    The  Company  may  also  face  competition  from  electric  utilities,  LECs
operating outside their current local  service areas, IXCs and other  providers.
These  entities provide transmission services using technologies which may enjoy
a greater degree of market acceptance than 38 GHz wireless broadband  technology
in  the provision of last mile broadband  services. In addition, the Company may
face competition  from  new market  entrants  using wireless,  fiber  optic  and
enhanced  copper based networks to provide local service and from wireless cable
providers and other  service providers  operating in frequencies  other than  38
GHz.
 
                                       54
<PAGE>
    Many  of  the Company's  competitors  have long-standing  relationships with
customers  and  suppliers,  greater  name  recognition  and  greater  financial,
technical  and  marketing  resources  than  the  Company.  As  a  result,  these
competitors may be  able to  more quickly develop  and exploit  new or  emerging
technologies,  adapt  to changes  in  customer requirements,  or  devote greater
resources to the marketing of their services than the Company. The consolidation
of telecommunications companies  and the  formation of  strategic alliances  and
cooperative  relationships in  the telecommunications  and related  industry, as
well as the development of new technologies, could give rise to significant  new
competitors  to the Company. In  such case, there can be  no assurance as to the
degree to which the Company will be able to compete effectively.
 
GOVERNMENT REGULATION
 
    The Company's  wireless  broadband services  are  subject to  regulation  by
federal,  state and local governmental agencies. The Company believes that it is
in  substantial  compliance  with  all  material  laws,  rules  and  regulations
governing  its operations and has  obtained, or is in  the process of obtaining,
all authorizations, tariffs and approvals  necessary and appropriate to  conduct
its   operations.  Nevertheless,  changes  in  existing  laws  and  regulations,
including those relating to the  provision of wireless local  telecommunications
services  via 38 GHz and/or the future granting of 38 GHz authorizations, or any
failure or significant delay in obtaining necessary regulatory approvals,  could
have a material adverse effect on the Company.
 
    FEDERAL REGULATION
 
    At  the  federal  level,  the  FCC has  jurisdiction  over  the  use  of the
electromagnetic  spectrum   (I.E.,   wireless  services)   and   has   exclusive
jurisdiction  over all  interstate telecommunications  services, that  is, those
that originate in  one state and  terminate in another  state. State  regulatory
commissions  have jurisdiction  over intrastate  communications, that  is, those
that originate  and terminate  in the  same state.  Municipalities may  regulate
limited  aspects  of the  Company's business  by,  for example,  imposing zoning
requirements and requiring installation permits. The Company also is subject  to
taxation at the federal and state levels and may be subject to varying taxes and
fees from local jurisdictions.
 
    FCC  LICENSING.  The  Communications Act of  1934 (the "Communications Act")
imposes certain requirements relating to licensing, common carrier  obligations,
reporting  and treatment of competition. Under  current FCC rules, the recipient
of an authorization  for 38  GHz microwave  facilities is  required to  complete
construction  of such facilities  within 18 months  of the date  of grant of the
authorization (authorizations  for  facilities  that  are  not  constructed  are
referred  to in this Prospectus as "construction permits" and authorizations for
facilities  that  are  constructed  are  referred  to  in  this  Prospectus   as
"licenses").  Upon  completion  of  construction, the  licensee  is  required to
certify that the  station is operational  and ready to  provide services to  the
public.  Although, under current FCC regulations,  the term "operational" is not
defined, the  industry custom  is to  establish at  least one  link between  two
transceivers  in each market area  for which it holds  a construction permit. In
the event that the recipient fails to comply with the construction deadline, the
construction permit  is  subject  to  forfeiture, absent  an  extension  of  the
deadline.  Effective August 1, 1996, the Company  will not be required to file a
form with  the  FCC  certifying  that its  station  is  operational  (i.e.  that
construction  is completed);  however, the  licensee will  still be  required to
complete  construction  within  18   months  of  the  date   of  grant  of   the
authorization.  In  addition,  effective  August  1,  1996,  a  station  will be
operational when  construction  is  complete  and  the  station  is  capable  of
providing  service. Upon  completion of  the CommcoCCC  Acquisition, the Company
will own or manage a total of  237 authorizations that will allow it to  provide
38  GHz wireless broadband  services in 169 U.S.  markets. The Company currently
owns or  manages 108  authorizations (exclusive  of the  CommcoCCC Assets)  that
allow  it  to  provide 38  GHz  wireless  broadband services  in  89  markets to
construct and operate  38 GHz  wireless broadband  facilities, 73  of which  are
owned  by the Company and  the remaining 35 of which  are managed by the Company
through the Company's interests in or arrangements with other companies. Of  the
108 authorizations (exclusive of the CommcoCCC Assets) which the Company owns or
manages, 77 are licenses. Under the
 
                                       55
<PAGE>
terms  of  its  remaining 31  construction  permits, the  Company  must complete
construction of  facilities  for the  majority  of such  authorizations  between
mid-August  and mid-September 1996,  but it expects  to complete construction of
all such construction permits by the  beginning of August 1996. Under the  terms
of  the  CommcoCCC authorizations  and the  Company's management  agreement with
CommcoCCC, the  Company  must  complete construction  of  facilities  for  eight
construction  permits by mid-September 1996, 39 construction permits by December
1996 and  the  remaining 82  between  mid-April  and August  1997.  The  Company
believes  that, in  light of  current FCC  practice, extensions  of construction
periods  are  highly  unlikely.  See  "Risk  Factors  --  Risk  of   Forfeiture,
Non-Renewal and Fluctuation in Value of FCC Licenses."
 
    COMMON  CARRIER REGULATION.  Under the terms of its licenses, the Company is
classified as a common carrier,  and as such is required  to offer service on  a
non-discriminatory  basis  at just  and  reasonable rates  to  anyone reasonably
requesting such service. Although the  Communications Act prohibits the  Company
from  discriminating among its  customers, the Communications  Act, as currently
interpreted by  the  FCC, does  permit  the Company  substantial  discretion  in
classifying  its customers  and discriminating  among such  classifications. The
Company generally is obligated to furnish  service to its competitors and  might
be  obligated to allow other 38 GHz providers to install links within one of the
Company's market areas for a non-discriminatory fee. Under the FCC's streamlined
regulation of non-dominant  carriers, the  Company, as  a non-dominant  carrier,
must  file tariffs with  the FCC for  certain interstate services  on an ongoing
basis. The Company  is in the  process of filing  tariffs with the  FCC, to  the
extent  required, with respect  to its provision of  interstate service. The FCC
has recently initiated a  rulemaking proceeding to  eliminate the tariff  filing
requirement   pursuant   to   new  forbearance   authority   contained   in  the
Telecommunications Act. The Company, as a non-dominant carrier, is not currently
subject to rate regulation, and it may install and operate non-radio  facilities
for  the transmission  of interstate communications  without prior  FCC or state
authorization.
 
    The Company manages the systems of ART West, DCT, Telecom One and  CommcoCCC
(during  the pendency  of the acquisition  of certain  acquisitions) pursuant to
management agreements.  See "Business  -- Agreements  Relating to  Licenses  and
Authorizations."  The Company believes  that the provisions  of these management
agreements comply  with  the  FCC's  policies  concerning  licensee  control  of
FCC-licensed  facilities. Because the 38 GHz  service is a new service, however,
there is no FCC precedent addressing the limits of such management  arrangements
for  these services. No assurance can be given that the arrangements or proposed
acquisitions will, if challenged, be found to satisfy the FCC's policies or what
modifications, if any, may need to be made to satisfy those policies. If the FCC
were to  void  or require  modifications  of the  management  arrangements,  the
Company's operating results would be adversely affected.
 
    FCC  REPORTING.    The Company,  as  an  operator of  millimeter  wave radio
facilities, is  subject  to the  FCC's  semiannual reporting  requirements  with
respect  to the deployment of wireless  local telecommunications services in its
licensed areas.  The  Company believes  that  it  has fully  complied  with  its
reporting  obligation. Effective August 1, 1996,  the FCC rules will not require
semiannual reporting.
 
    COMPETITION.  Over the last  several years, the FCC  has issued a series  of
decisions  and Congress has  recently enacted legislation  making the interstate
access services  market  more  competitive  by  requiring  reasonable  and  fair
interconnection   by  LECs.  Concomitant  with  its  decision  to  require  such
interconnection, the FCC has  provided LECs with a  greater degree of  increased
pricing flexibility between services (such as the ability to reduce local access
charges  paid  by long  distance carriers  utilizing  LECs' local  networks) and
between  geographic  markets  (such  as  cross-subsidizing  price  cuts   across
geographic  markets). The Company anticipates that this pricing flexibility will
result in LECs lowering their prices in  high density zones. To the extent  that
LECs  choose to take  advantage of increased pricing  flexibility to lower their
rates, the ability of the  Company and CAP customers  of the Company to  compete
for  certain markets  and services  and the  Company's operating  results may be
adversely affected.
 
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<PAGE>
    THE  TELECOMMUNICATIONS  ACT.    The  Telecommunications  Act  substantially
departs   from  prior   legislation  in   the  telecommunications   industry  by
establishing local exchange competition as a national policy through the removal
of  state  regulatory  barriers  to  competition  and  the  preemption  of  laws
restricting  competition in  the local  exchange market.  The Telecommunications
Act, among other things, mandates that LECs (i) permit resale of their  services
and facilities on reasonable and nondiscriminatory terms and at wholesale rates,
(ii)  allow customers to retain the same telephone number ("number portability")
when they  switch carriers,  (iii) permit  interconnection by  competitors to  a
LEC's network at any technically feasible point on the same terms as LEC charges
for  its own  services, (iv) unbundle  their network services  and facilities by
permitting competitors and others to use some but not all of their facilities at
cost-based and nondiscriminatory rates and (v) ensure that the end user does not
have to dial any more digits to reach local competitors than to reach the LEC to
the extent technically feasible  ("dialing parity"). The Telecommunications  Act
also  allows  RBOCs  to  provide  interLATA  services  once  certain competitive
characteristics emerge in their  local exchange markets.  The provisions of  the
Telecommunications  Act are designed to ensure that RBOCs take affirmative steps
to level the playing  field for their  competitors so that  CAPs and others  can
compete  effectively. The FCC, with advice  from the United States Department of
Justice, and the states  are given jurisdiction  to enforce these  requirements.
There  can be no assurance, however, that  the states and the FCC will implement
the Telecommunications  Act  in  a  manner favorable  to  the  Company  and  its
customers.
 
    FCC RULEMAKING.  On November 13, 1995, the FCC released an order barring the
acceptance  of new applications for 38 GHz authorizations. On December 15, 1995,
the FCC announced the  issuance of the  NPRM, pursuant to  which it proposed  to
amend  its current rules to provide for, among other things, (i) the adoption of
an auction procedure  for the  issuance of authorizations  in the  38 GHz  band,
including  a possible auction of the lower  fourteen 100 MHz channels (which are
similar to those used by the Company) and the lower four 50 MHz channels in  the
38 GHz band that have not been previously available for commercial use, (ii) the
continuation  of  the  100 MHz-based  channeling  plan and  licensing  rules for
point-to-point microwave operations  in the lower  14 channels, (iii)  licensing
frequencies  using predefined geographic service  areas ("Basic Trading Areas"),
(iv) the  imposition of  substantially  stricter construction  requirements  for
authorizations  that are not received pursuant to auctions as a condition to the
retention of such authorizations and (v) the implementation of certain technical
rules designed  to  avoid  radio  frequency  interference  among  licensees.  In
addition,  the FCC ordered that those applications subject to mutual exclusivity
with other applicants or placed on public notice by the FCC after September  13,
1995 would be held in abeyance pending the outcome of the NPRM and might then be
dismissed.  Final rules issued in  connection with the NPRM  may require that 38
GHz service providers share other yet-to-be licensed portions of the 38 GHz band
with other telecommunications  service providers. The  implementation of such  a
measure could materially affect the Company's ability to provide services to its
customers  by imposing power or other  limitations upon its existing operations.
The NPRM proposes substantial strengthening of the current rules concerning  the
steps  that a grantee of  a 38 GHz authorization must  take to satisfy the FCC's
construction requirements. At present,  the holder of  a construction permit  is
only  required to  certify that  it is  operational. Although  under current FCC
regulations the term  "operational" is not  defined, the industry  custom is  to
install  one link, which may be only  temporary and may not be producing revenue
for the operator. The  NPRM expresses concern that  this lenient standard  might
allow  the warehousing of 38  GHz spectrum. As a  consequence, the NPRM proposes
much more  stringent construction  requirements  for authorizations  other  than
those  received pursuant to an auction. There can be no assurance that the final
rules (if  any) issued  in connection  with  the NPRM  will resemble  the  rules
proposed  in the NPRM. There also can be no assurance that any proposed or final
rules will  not have  a material  adverse effect  on the  Company. Statutes  and
regulations  which  may become  applicable to  the Company  as it  expands could
require the  Company to  alter methods  of operations  at costs  which could  be
substantial or otherwise limit the types of services offered by the Company.
 
    The NPRM also proposes that 38 GHz authorizations be awarded by auction. The
NPRM  would  specify the  geographic  areas that  could  be licensed  instead of
continuing to allow the applicants to
 
                                       57
<PAGE>
design the  geographic  circumferences of  the  licenses. The  Company  has  not
determined  whether to seek additional licenses in  the event of an auction. The
Company believes  that the  FCC is  likely  to award  38 GHz  authorizations  by
auction, but there can be no assurance that this will occur.
 
    STATE REGULATION
 
    Many  of  the  Company's services,  either  now  or in  the  future,  may be
classified as intrastate and therefore may  be subject to state regulation.  The
Company  is  in  the process  of  obtaining  state authorizations  deemed  to be
sufficient to  conduct  most,  if not  all,  of  its proposed  business  in  the
near-term,  but there  can be  no assurance that  some portion  of the Company's
proposed  transmissions  might  not  be  considered  to  be  subject  to   state
jurisdiction  in  a  state  in  which  the  Company  does  not  have appropriate
authority. The Company expects that as its business and product lines expand and
the requirements  of  the Telecommunications  Act  favoring competition  in  the
provision  of local  communications services are  implemented, it  will offer an
increased number and type of intrastate services. The Company is implementing  a
program  to expand the  scope of its intrastate  certifications in various state
jurisdictions as its product line expands  and as the Telecommunications Act  is
implemented.
 
    Under  current state regulatory  schemes, entities can  compete with LECs in
the provision  of (i)  local access  services, (ii)  dedicated access  services,
(iii) private network services, including WAN services, for businesses and other
entities   and   (iv)  long   distance  toll   services.  The   remaining  local
telecommunications  services,   including  switched   local  exchange   services
encompassing  calls originating  and terminating within  a single  LATA, are not
currently subject  to  competition in  most  states. The  Telecommunication  Act
requires  each  of these  states  to remove  these  barriers to  competition. No
assurance can be given as to how quickly and how effectively each state will act
to implement the new legislation.
 
INTELLECTUAL PROPERTY RIGHTS
 
    The Company has filed for protection  for four service marks: DigiWave  (the
Company's  wireless  broadband  trademark), OZ  Box  (the  Company's proprietary
network management  interface),  ART and  Advanced  Radio Telecom.  These  first
filings  are  block  mark  applications,  which if  allowed  by  the  Patent and
Trademark Office, would  protect future  variations. The Company  will seek  the
maximum  protection for its future service marks. There can be no assurance that
the service marks  applied for  will be granted  nor that  the Company's  future
efforts   will  be  successful.  Although  the  Company  is  developing  various
proprietary processes, software  products and databases  and intends to  protect
its  rights vigorously and  to continue to develop  such proprietary systems and
databases, there can be no assurance  that these measures will be successful  in
establishing its proprietary rights in such assets.
 
EMPLOYEES
 
    As  of June 15, 1996, the Company had  a total of 70 employees, including 20
in  engineering  and  field  services,  25   in  sales  and  marketing,  13   in
administration  and finance, 8 in operations  and 4 in corporate development and
advanced  services.  None  of  the  Company's  employees  is  represented  by  a
collective  bargaining  agreement.  The  Company has  never  experienced  a work
stoppage and believes that its employee relations are good.
 
PROPERTIES
 
    The Company leases  approximately 22,000  square feet  of office,  technical
operations  and engineering field services  depot space in Bellevue, Washington.
The Company's  corporate headquarters,  network  operations center  and  western
regional  sales office occupy approximately 15,000  square feet under a sublease
expiring  in  January   2000.  The  Company's   engineering  department   leases
approximately  5,000 square feet and 2,000  square feet for technical operations
and an  engineering  field  services depot,  respectively,  pursuant  to  leases
expiring in May 1997. In addition the Company leases 1,100 square feet of office
space  in Portland, Oregon for sales and marketing personnel pursuant to a lease
expiring in  March 1998.  The  Company also  leases  temporary office  space  in
Washington,  D.C. under a sub-lease from  Pierson & Burnett, L.L.P. See "Certain
Transactions -- Pierson & Burnett Transactions."
 
LITIGATION
 
    The Company is not a party to any litigation.
 
                                       58
<PAGE>
                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    The  executive officers,  directors and  certain other  key officers  of the
Company, their ages and their positions  are as follows (after giving effect  to
the Merger):
 
<TABLE>
<CAPTION>
NAME                                              AGE      POSITION
- --------------------------------------------      ---      -------------------------------------------------------
<S>                                           <C>          <C>
Vernon L. Fotheringham (1)(2)(3)............          48   Chairman of the Board of Directors and Chief Executive
                                                            Officer
Steven D. Comrie............................          40   President, Chief Operating Officer and Director
Thomas A. Grina.............................          38   Executive Vice President and Chief Financial Officer
W. Theodore Pierson, Jr.....................          59   Executive Vice President, Secretary and General Counsel
James D. Miller.............................          53   Senior Vice President, Sales and Marketing
James C. Cook (6)(7)(8).....................          36   Director Designate
J.C. Demetree, Jr. (3)(4)(5)................          37   Director
Mark C. Demetree (1)(2).....................          39   Director
Andrew I. Fillat (2)(3)(4)..................          48   Director
Matthew C. Gove (2)(4)(5)...................          31   Director
T. Allan McArtor (6)(8)(9)..................          53   Director Designate
Laurence S. Zimmerman (1)(3)(5).............          36   Director
</TABLE>
 
- ------------------------------
(1)  Member of Option Committee.
 
(2)  Member of Compensation Committee.
 
(3)  Member of Finance Committee.
 
(4)  Member of Audit Committee.
 
(5)  These  directors will resign effective on  the date of this Prospectus, and
     James C.  Cook  and T.  Allan  McArtor will  be  elected to  the  Board  of
     Directors. See " -- Board Composition."
 
(6)  These directors have been elected effective on the date of this Prospectus.
     See "-- Board Composition."
 
(7)  Member of Option Committee effective on the date of this Prospectus.
 
(8)  Member of Audit Committee effective on the date of this Prospectus.
 
(9)  Member of Compensation Committee effective on the date of this Prospectus.
 
     VERNON  L. FOTHERINGHAM has  served as Chairman of  the Board of Directors,
Chief Executive Officer of the Company and Telecom since inception. From 1993 to
1995, Mr. Fotheringham served as president and chief executive officer of Norcom
Networks Corporation, a  nationwide provider  of mobile  satellite services.  In
1992,  Mr.  Fotheringham co-founded  Digital Satellite  Broadcasting Corporation
("DSBC"), a  development  stage  company planning  to  provide  satellite  radio
services  nationwide, served  as its  chairman from  1992 to  1993 and currently
serves as one of its  directors. From 1988 to  1994, Mr. Fotheringham served  as
senior   vice  president  of   The  Walter  Group,   Inc.  ("TWG"),  a  wireless
telecommunications consulting and  project management firm.  From 1983 to  1986,
Mr.  Fotheringham served as vice president  of marketing of Omninet Corporation,
which was the  original developer of  the current Qualcomm  Omni TRACS  network.
Over  the last ten years, Mr. Fotheringham has advised several businesses in the
telecommunications industry,  including American  Mobile Satellite  Corporation,
ClairCom Communications ("ClairCom") and McCaw Cellular Communications, Inc.
 
    STEVEN  D. COMRIE  has served  as President,  Chief Operating  Officer and a
director of the Company since July 1995. From 1992 to 1995, Mr. Comrie served as
vice president and general manager of
 
                                       59
<PAGE>
Cypress Broadcasting Inc., a California-based television subsidiary of  Ackerley
Communications  Inc., a diversified media  company based in Seattle, Washington.
From 1990 to 1992, Mr. Comrie  served as president of First Communication  Media
Inc.  and  as  an investor,  advisor  and  manager of  satellite,  broadcast and
telecommunications businesses  in the  United States  and Canada.  In 1986,  Mr.
Comrie  co-founded  Netlink,  the first  commercial  direct  broadcast satellite
service  operating   in   the   U.S.  which   was   subsequently   acquired   by
Tele-Communications  Inc. ("TCI"). Previously, Mr. Comrie served in a variety of
management positions with cable and media companies.
 
    THOMAS A. GRINA has served as  Executive Vice President and Chief  Financial
Officer of the Company since April 1996. From June 1989 to April 1996, Mr. Grina
was  Executive Vice President, Finance and  Chief Financial Officer of DialPage,
Inc. and  Executive Vice  President of  its wholly-owned  subsidiary, Dial  Call
Communications,  Inc.,  a  wireless  communications  company  operating  in  the
southeastern U.S.
 
    W. THEODORE PIERSON, JR. has served as Executive Vice President and  General
Counsel  of the Company and Telecom since inception. He has served as a director
of the  Company since  its inception  and  will resign  upon completion  of  the
Merger.  For more than five years, Mr. Pierson has been a partner of the firm of
Pierson & Burnett, L.L.P. (and its predecessor firms) in Washington, D.C., which
specializes in telecommunications law. As such, Mr. Pierson has advised a number
of start-up telecommunications companies,  including Home Box Office,  Satellite
Business Services, Omninet Corporation and DSBC. Mr. Pierson currently serves as
a  director  of DSBC.  Mr.  Pierson has  also  been counsel  to  the Competitive
Telecommunications  Association  (the  largest  association  of  long   distance
carriers)  and the Association for Local Telecommunications Services for several
years.
 
    JAMES D. MILLER has served as Senior Vice President, Sales and Marketing  of
the  Company  since  December 1995.  From  1993  to 1995,  Mr.  Miller  was vice
president and general  manager of U.S.  Intelco Wireless. Mr.  Miller served  as
executive  vice president  of Atlas  Telecom from 1987  to 1993  and as national
sales manager of Sidereal Corporation from 1977 to 1987.
 
    JAMES C. COOK will become  a director of the Company  upon the date of  this
Prospectus.  Mr. Cook is currently senior  vice president of First Union Capital
Partners, Inc. ("FUCPI"), the private equity investment affiliate of First Union
Corporation, where he has been employed since 1989. Prior to joining FUCPI,  Mr.
Cook  served in various capacities at The Bank of New York from 1982 to 1987 and
at Kidder, Peabody & Co. Inc. in 1988.
 
    J.C. DEMETREE, JR. has served as a  director of the Company since May  1995.
Since  1987, Mr. Demetree has served as  president of Demetree Brothers, Inc., a
real estate service company. Since  1980, he has been  a partner and trustee  of
Pentagon  Properties, a privately-held trust with investments in commercial real
estate and  other  operating  businesses including  banking  and  chemical.  Mr.
Demetree  has served since 1987 as a  director of Community First Bank and since
1995 as a director and officer of CFB Bancorp.
 
    MARK C. DEMETREE has  served as a  director of the  Company since May  1995.
Since  1993, Mr. Demetree has been president of North American Salt Company, the
second largest  salt producer  in North  America. From  1991 through  1993,  Mr.
Demetree  served as  president of  Trona Railway  Company, a  shortline railroad
division of  North  American  Chemical  Company. Mr.  Demetree  currently  is  a
director of J.C. Nichols Company, a real estate company, and serves on the Board
of  Governors  of  the  Canadian  Chamber of  Maritime  Commerce  for  the Great
Lakes/St. Lawrence Seaway and is the current chairman of the CEO Council of  the
Salt Institute.
 
    ANDREW  I. FILLAT  has served  as a director  of the  Company since November
1995.  Mr.  Fillat  has  been  employed  since  1989  by  Advent   International
Corporation  ("Advent"), a global venture  capital and private equity management
firm and currently serves  as senior vice president.  Prior to 1989, Mr.  Fillat
was  a  partner  at Fletcher  and  Company,  a consulting  firm  specializing in
assisting venture-backed  enterprises,  and  was  an  operating  executive  with
Fidelity Investments. Mr. Fillat is also a director of:
 
                                       60
<PAGE>
Interlink  Computer Sciences,  a systems management  and communications software
company;  Lightbridge,  Inc.,  a  company  providing  customer  acquisition  and
marketing  related  services for  cellular and  PCS  carriers; Voxware,  Inc., a
software company  providing  advanced  voice  compression  and  processing;  and
several private companies in the Advent portfolio.
 
    MATTHEW  C. GOVE  has served as  a director  of the Company  since May 1995.
Since  1994,  Mr.  Gove  has   been,  through  Hedgerow  Corporation  of   Maine
("Hedgerow"),  a consultant to  LHC, specializing in  domestic and international
telecommunications  transactions.  From  1991  through  1993,  he  attended  the
Columbia  University Graduate  School of Business  and worked  as an independent
consultant specializing in spreadsheet modeling and financial analysis. Prior to
1991, he  was custodial  manager of  foreign currency  derivative funds  at  The
Boston Company.
 
    T. ALLAN MCARTOR will become a director of the Company upon the date of this
Prospectus.  Since  1995,  Mr. McArtor  has  been chairman  and  chief executive
officer of  Quest  Computer Television  Company,  LLC, an  interactive  publicly
programmable  information network.  Since 1994, Mr.  McArtor has  also served as
chairman and chief executive officer  of Contrails, LLC, an aviation  consulting
firm.  From 1992 to 1994,  Mr. McArtor served as  president of FedEx Aeronautics
Corporation, a wholly-owned subsidiary of Federal Express Corporation ("FedEx").
From  1982  to  1987,  he  served   as  senior  vice  president  of  the   FedEx
Telecommunications  Division and from  1989 to 1992 as  senior vice president of
air operations at FedEx. From 1987 to 1989, Mr. McArtor was Administrator of the
Federal Aviation Administration. Mr.  McArtor currently serves  on the board  of
directors   of   Pilkington  Aerospace,   Inc.,   a  manufacturer   of  aviation
transparencies for fighter aircraft canopies, aircraft windshields and windows.
 
    LAURENCE S. ZIMMERMAN  has served  as a director  of the  Company since  May
1995.  Since  1985,  Mr.  Zimmerman  has  been  President  of  Landover Holdings
Corporation ("LHC"), of which he is the  founder and beneficial owner. LHC is  a
private  investment firm with  interests in wireless  cable, wireless telephone,
cellular and managed healthcare and specialty retail companies as well as  other
investments  in the United States  and abroad. From 1989  to 1990, Mr. Zimmerman
was a managing director of
Renaissance Capital Group Inc.,  a leveraged buyout  firm which concentrated  on
emerging   market   and   middle   market   telecommunications   and  healthcare
opportunities. In 1993, Mr.  Zimmerman was a founder  of, and provided the  seed
capital  for, National Wireless Holdings Inc.,  a wireless cable company serving
markets in Southern Florida. On February 1, 1995, Mr. Zimmerman consented to the
entry of an order of the  Securities and Exchange Commission, without  admitting
or  denying the matters  referred to therein, barring  him from association with
any  broker,  dealer,  municipal   securities  dealer,  investment  company   or
investment  adviser during the period  February 1, 1995 to  February 1, 1996 and
requiring him not to violate certain provisions of the Federal securities  laws.
The  order relates to alleged  violations arising out of  alleged conduct by Mr.
Zimmerman in 1986 as a broker for Breuer Capital, in connection with trading and
selling shares of  Balchem Corporation.  See "Principal  Stockholders --  Voting
Trust Agreement."
 
BOARD COMPOSITION
 
    Under  the terms  of the  Stockholders Agreement  (as described  in "Certain
Transactions -- February  1996 Reorganization"), the  Landover Stockholders  (as
defined  in the Stockholders Agreement) have the right to designate four members
of the Board of  Directors of the  Company and have  designated Messrs. Mark  C.
Demetree,  J.C. Demetree,  Jr., Gove  and Zimmerman  as directors.  In addition,
pursuant to the terms of the Stockholders Agreement, the Advent Partnerships (as
defined in the Stockholders  Agreement) and Ameritech,  as holders of  Telecom's
Series  E and F  preferred stock respectively,  have the right  to designate one
member of the Board of Directors of  the Company and have designated Mr.  Fillat
as  a director. Pursuant to the Stockholders  Agreement, the right of the Advent
Partnerships to  designate a  director terminates  at such  time as  the  Advent
Partnerships  cease  to own  at  least 50%  of  the aggregate  amount  of equity
securities of the Company currently owned by them. See "Certain Transactions  --
LHC  Purchase Agreement -- Advent Private Placement." The Stockholders Agreement
will terminate upon consummation of the Offerings.
 
                                       61
<PAGE>
    All directors  hold office  until  their successors  have been  elected  and
qualified.  Effective as of the date  of this Prospectus, Messrs. J.C. Demetree,
Jr., Gove and Zimmerman will resign as directors, and James C. Cook and T. Allan
McArtor, each of  whom is  unaffiliated with the  Company's present  management,
will be elected to the Board. After consummation of the Offerings, Mr. Zimmerman
may  attend meetings of the Board of Directors as an observer, at the invitation
of the Board of Directors. In addition, upon consummation of the Offerings,  the
Company's Board of Directors will be divided into three classes, with each class
of  directors to serve  three-year staggered terms  (after their initial terms).
Messrs. Comrie and McArtor will be elected  as Class I directors for an  initial
one-year term expiring in 1997. Messrs. Cook and Fotheringham will be elected as
Class  II directors for an initial two-year  term expiring in 1998. Messrs. Mark
C. Demetree and Fillat  will be elected  as Class III  directors for an  initial
three-year term expiring in 1999.
 
    Promptly  after closing of the CommcoCCC Acquisition, the Company has agreed
to nominate  one  individual  designated  by the  Commco  CCC  stockholders  and
acceptable to the Company as a director of the Company.
 
DIRECTOR COMPENSATION
 
    Upon  consummation of the Offerings, directors  who are not employees of the
Company will receive  $4,000 per year  for services rendered  as a director  and
$500  for  attending  each meeting  of  the Board  of  Directors or  one  of its
Committees. In  addition,  directors  may be  reimbursed  for  certain  expenses
incurred  in connection with attendance at any meeting of the Board of Directors
or Committees. Other than reimbursement of expenses, directors who are employees
of the Company receive no additional compensation for service as a director.
 
    In April 1996,  the Company adopted  the Directors Plan  (as defined)  which
provides  for automatic  grants of options  to purchase an  aggregate of 200,000
shares of Common Stock to non-employee  directors of the Company. See "--  Stock
Option  Plans."  Upon  consummation of  the  Offerings, options  to  purchase an
aggregate of 28,000 shares  at an exercise price  equal to the initial  offering
price  of  the  Common  Stock  are anticipated  to  be  granted  to non-employee
directors under the Directors Plan.
 
BOARD COMMITTEES
 
    The Company's bylaws, as amended (the  "Bylaws"), provide that the Board  of
Directors  may establish committees to exercise  certain powers delegated by the
Board of  Directors. Pursuant  to that  authority, the  Board of  Directors  has
established  an Option Committee, Compensation  Committee, Finance Committee and
Audit Committee.
 
    The  Option  Committee  reviews,  interprets  and  administers  the   Equity
Incentive  Plan (as defined), prescribes  rules and regulations relating thereto
and determines the stock options to be granted by the Company to its  employees.
Messrs.  Mark C.  Demetree, Fotheringham  and Zimmerman  currently serve  on the
Option Committee. Upon consummation of  the Offerings, Messrs. Mark C.  Demetree
and Fillat will serve on the Option Committee.
 
    The   Compensation   Committee   has   responsibility   for   reviewing  and
administering the  Company's program  with respect  to the  compensation of  its
officers,   employees  and  consultants  and  reviewing  transactions  with  its
officers, directors and affiliates. As a policy, the Compensation Committee pays
officers, directors and affiliates of the Company for services rendered  outside
the  scope of  their respective obligations  to the Company,  in accordance with
industry standards  for  such  services, which  may  include  introducing  major
transactions  or  providing  legal  services to  the  Company.  Messrs.  Mark C.
Demetree, Fillat,  Fotheringham and  Gove currently  serve on  the  Compensation
Committee. Upon consummation of the Offerings, Messrs. Mark C. Demetree, Fillat,
Fotheringham and McArtor will serve on the Compensation Committee.
 
                                       62
<PAGE>
    The  Finance  Committee  has responsibility  for  reviewing  and negotiating
financing proposals for the Company and  submitting such proposals to the  Board
of  Directors for approval. Messrs. J.C. Demetree, Jr., Fillat, Fotheringham and
Zimmerman currently serve  on the  Finance Committee. Upon  consummation of  the
Offerings, the Finance Committee will be disbanded.
 
    The  Audit Committee recommends the engagement of independent accountants to
audit the Company's  financial statements  and perform services  related to  the
audit,  reviews the scope and results of the audit with the accountants, reviews
with management and the independent accountants the Company's year-end operating
results, and considers the adequacy  of internal accounting procedures.  Messrs.
J.C. Demetree, Jr., Fillat and Gove currently serve on the Audit Committee. Upon
consummation  of the Offerings,  Messrs. Cook, Fillat and  McArtor will serve on
the Audit Committee.
 
RELATED PARTY TRANSACTIONS
 
    On February 2,  1996, the Company  adopted a policy  that all  transactions,
including  compensation,  between the  Company and  its officers,  directors and
affiliates will be  on terms  no less  favorable to  the Company  than could  be
obtained from unrelated third parties and shall be approved by a majority of the
disinterested  members of  the Compensation  Committee or  by a  majority of the
disinterested members of the Board of Directors.
 
EXECUTIVE COMPENSATION
 
    The following  table  sets  forth  all  compensation  received  by  (i)  the
Company's  Chief Executive Officer and (ii)  each person serving as an executive
officer of the Company whose  salary and bonus exceeded $100,000  (collectively,
the  "Named Executive  Officers"), for services  rendered to the  Company in all
capacities during the fiscal year ended December 31, 1995.
 
                           SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                                    LONG TERM
                                                                                   COMPENSATION
                                                                                      AWARDS
                                                                                  --------------
                                                         ANNUAL COMPENSATION        SECURITIES
                                                     ---------------------------    UNDERLYING      ALL OTHER
NAME AND PRINCIPAL POSITION                              SALARY         BONUS       OPTIONS(#)     COMPENSATION
- ---------------------------------------------------  --------------  -----------  --------------  --------------
<S>                                                  <C>             <C>          <C>             <C>
Vernon L. Fotheringham, Chief Executive Officer      $    97,167             --              --   $      9,600(1)
Steven D. Comrie, President and Chief Operating
 Officer(2)                                               77,000             --         756,691         33,200(1)(3)
W. Theodore Pierson, Jr., Executive Vice President        77,500             --              --        219,600(1)(4)
James D. Miller, Senior Vice President, Sales and
 Marketing (2)                                                --             --          50,000             --
</TABLE>
 
- ------------------------------
(1)  Automobile reimbursement benefits equal  to $9,600 in  the case of  Messrs.
     Fotheringham  and Pierson, $3,200 in  the case of Mr.  Comrie and $1,200 in
     the case of Mr. Menatti.
 
(2)  Reflects compensation for a partial year. See "-- Employment and Consulting
     Agreements."
 
(3)  Represents the  forgiveness of  a loan  on January  1, 1996  that has  been
     accounted  for as compensation expense on  the 1995 statement of operations
     of the Company.
 
(4)  The Company  paid Pierson  & Burnett,  L.L.P., of  which Mr.  Pierson is  a
     partner, $210,000 for services rendered to the Company through December 31,
     1995.
 
                                       63
<PAGE>
     OPTION  GRANTS.    The  following  table  sets  forth  certain  information
regarding stock option  grants made to  the Named Executive  Officers in  fiscal
year 1995.
 
                       OPTION GRANTS IN LAST FISCAL YEAR
 
<TABLE>
<CAPTION>
                                              INDIVIDUAL GRANTS (2)
                               ----------------------------------------------------  POTENTIAL REALIZABLE VALUE AT
                                NUMBER OF      PERCENT OF                            ASSUMED ANNUAL RATES OF STOCK
                                SECURITIES    TOTAL OPTIONS                          PRICE APPRECIATION FOR OPTION
                                UNDERLYING     GRANTED TO     EXERCISE                         TERM (1)
                                 OPTIONS      EMPLOYEES IN    PRICE PER  EXPIRATION  -----------------------------
NAME                             GRANTED       FISCAL YEAR      SHARE       DATE         5%             10%
- -----------------------------  ------------  ---------------  ---------  ----------  -----------  ----------------
<S>                            <C>           <C>              <C>        <C>         <C>          <C>
Steven D. Comrie                   756,691          71.9%     $  0.5907   6/17/05    $   179,428  $    427,102
James D. Miller                     50,000           4.8%         1.652   12/29/00            --        14,031
</TABLE>
 
- ------------------------------
(1)  The  potential  realizable value  is calculated  based on  the term  of the
     option at its time of grant (five years). It is calculated by assuming that
     the stock price on  the date of grant  appreciates at the indicated  annual
     rate,  compounded annually  for the entire  term of the  option. The actual
     realizable value of the options based on the price to public in the  Common
     Stock  Offering will  substantially exceed  the potential  realizable value
     shown in the table. The option price is based upon an estimate of the  fair
     market value of the Company's equity securities as determined by the Option
     Committee at the time of grant.
 
(2)  See "-- Stock Option Plans -- Equity Incentive Plan -- Grants."
 
     AGGREGATE  STOCK OPTION EXERCISES  IN LAST FISCAL  YEAR AND FISCAL YEAR-END
OPTION VALUES.   The  following table  sets forth  the number  and value  as  of
December  31, 1995 of shares underlying unexercised  options held by each of the
Named Executive Officers.  As of December  31, 1995, no  stock options had  been
exercised by any Named Executive Officers.
 
                         FISCAL YEAR-END OPTION VALUES
 
<TABLE>
<CAPTION>
                                                              NUMBER OF SHARES
                                                           UNDERLYING UNEXERCISED        VALUE OF UNEXERCISED
                                                                 OPTIONS AT             IN-THE-MONEY OPTIONS AT
                                                               FISCAL YEAR END            FISCAL YEAR END (1)
                                                         ---------------------------  ---------------------------
NAME                                                     EXERCISABLE  UNEXERCISABLE   EXERCISABLE  UNEXERCISABLE
- -------------------------------------------------------  -----------  --------------  -----------  --------------
<S>                                                      <C>          <C>             <C>          <C>
Steven D. Comrie                                            417,693        338,998     $ 254,500    $    206,552
James D. Miller                                              10,000         40,000            --              --
</TABLE>
 
- ------------------------------
(1)  Based  on the estimated fair market value  of the Company's Common Stock as
     of December 31, 1995  of $1.20 per share,  less the exercise price  payable
     upon  exercise  of such  options. Such  estimated fair  market value  as of
     December 31, 1995 is  substantially lower than the  price to the public  in
     the Common Stock Offering.
 
STOCK OPTION PLANS
 
    EQUITY INCENTIVE PLAN.
 
    The  Equity Incentive Plan  was adopted by  the Company on  May 30, 1996 and
approved by the stockholders on June 25, 1996.
 
    The Equity Incentive Plan is designed to advance the Company's interests  by
enhancing  its ability to attract and retain  employees and others in a position
to make  significant  contributions  to  the  success  of  the  Company  through
ownership  of shares of Common Stock. The Equity Incentive Plan provides for the
grant  of  incentive  stock   options  ("ISOs"),  non-statutory  stock   options
("NQSOs"),  stock appreciation  rights ("SARs"),  restricted stock, unrestricted
stock, deferred stock grants, and  performance awards, loans to participants  in
connection  with awards,  supplemental grants and  combinations of  the above. A
total of 2,500,000 shares  of common stock are  reserved for issuance under  the
Equity  Incentive Plan. The maximum number of shares as to which options or SARs
may be granted to any participant is
 
                                       64
<PAGE>
800,000. The shares of Common Stock issuable under the Equity Incentive Plan are
subject to adjustment for stock dividends  and similar events. Awards under  the
Equity  Incentive  Plan  may  also include  provision  for  payment  of dividend
equivalents with respect to the shares subject to the award.
 
    The Equity Incentive  Plan is administered  by the Option  Committee of  the
Board  of Directors (the "Option Committee"). The Option Committee shall consist
of at  least  two  directors.  If  the Common  Stock  is  registered  under  the
Securities  Exchange Act of 1934,  all members of the  Option Committee shall be
"outside directors" as  defiined. All employees  of the Company  and any of  its
subsidiaries  and other persons or entities (including non-employee directors of
the Company and its subsidiaries) who,  in the opinion of the Option  Committee,
are  in a  position to  make a  significant contribution  to the  success of the
Company or its subsidiaries are eligible to participate in the Equity  Incentive
Plan.
 
    STOCK  OPTIONS.   The  exercise price  of  an ISO  granted under  the Equity
Incentive Plan may not be less than 100% (110% in the case of 10%  shareholders)
of  the fair market value of the Common Stock at the time of grant. The exercise
price of  a nonstatutory  option  granted under  the  Equity Incentive  Plan  is
determined  by the Option Committee.  The term of each option  may be set by the
Option Committee but cannot exceed ten  years from grant (five years from  grant
in the case of an incentive stock option granted to a 10% shareholder), and each
option  will  be exercisable  at  such time  or  times as  the  Option Committee
specifies. The option  price may  be paid  in cash  or check  acceptable to  the
Company  or,  if  permitted  by  the Option  Committee  and  subject  to certain
additional limitations,  by  tendering  shares  of  Common  Stock,  by  using  a
promissory  note,  by  delivering to  the  Company  an undertaking  by  a broker
promptly to deliver sufficient funds to pay the exercise price, or a combination
of the foregoing.
 
    STOCK APPRECIATION RIGHTS.   SARs may be granted  either alone or in  tandem
with  stock option  grants. Each  SAR entitles  the participant,  in general, to
receive upon exercise  the excess  of a  share's fair  market value  in cash  or
common  stock at the date of exercise over  the share's fair market value on the
date the SAR was granted. The Option Committee may also grant SARs which provide
that following a change in  control of the Company  as determined by the  Option
Committee,  the  holder of  such right  will  be entitled  to receive  an amount
measured by  specified values  or averages  of  values prior  to the  change  in
control.  If  an SAR  is  granted in  tandem  with an  option,  the SAR  will be
exercisable only to  the extent  the option is  exercisable. To  the extent  the
option is exercised, the accompanying SAR will cease to be exercisable, and vice
versa.  An SAR  granted in  tandem with an  ISO may  be exercised  only when the
market price of common stock subject to the option exceeds the exercise price of
such option. SARs not granted in tandem shall be exercisable at such time as the
Option Committee may specify.
 
    STOCK  AWARDS.    The   Equity  Incentive  Plan   provides  for  awards   of
nontransferable  shares of restricted Common Stock subject to forfeiture as well
as of unrestricted shares of Common Stock. Awards may provide for acquisition of
restricted and unrestricted Common Stock for  a purchase price specified by  the
Option  Committee, but in no event less  than par value. Restricted Common Stock
is subject to repurchase  by the Company  at the original  purchase price or  to
forfeiture  if no cash was paid by  the participant if the participant ceases to
be an employee  before the  restrictions lapse.  Other awards  under the  Equity
Incentive  Plan may  also be  settled with  restricted Common  Stock. Restricted
securities  shall  become  freely  transferable  upon  the  completion  of   the
Restricted  Period including  the passage of  any applicable period  of time and
satisfaction of any  conditions to vesting.  The Option Committee,  in its  sole
discretion,  may waive  all or  part of the  restrictions and  conditions at any
time.
 
    The Equity Incentive Plan  also provides for  deferred grants entitling  the
recipient  to receive shares of Common Stock in  the future at such times and on
such conditions  as the  Option Committee  may specify,  and performance  awards
entitling the recipient to receive cash or Common Stock following the attainment
of  performance goals determined by the Option Committee. Performance conditions
and provisions for deferred stock may also be attached to other awards under the
Equity Incentive Plan.
 
    A loan may be made under the Equity Incentive Plan either in connection with
the purchase of Common Stock under an award or with the payment of any  federal,
state  and local tax with respect to income  recognized as a result of an award.
The   Option   Committee    will   determine    the   terms    of   any    loan,
 
                                       65
<PAGE>
including  the  interest rate  (which  may be  zero). No  loan  may have  a term
exceeding ten  years in  duration.  In connection  with  any award,  the  Option
Committee  may also provide for and grant  a cash award to offset federal, state
and local income taxes or to make a participant whole for certain taxes.
 
    Except as otherwise provided by the Option Committee, if a participant dies,
options and SARs exercisable immediately prior to death may be exercised by  the
participant's  executor, administrator or transferee during a period of one year
following such death  (or for the  remainder of their  original term, if  less).
Except  as otherwise  determined by the  Option Committee, options  and SARs not
exercisable at a participant's death terminate. Outstanding awards of restricted
Common Stock must be transferred to the Company upon a participant's death  and,
similarly,  deferred Common  Stock grants,  performance awards  and supplemental
awards to which a participant was  not irrevocably entitled prior to death  will
be forfeited, except as otherwise provided.
 
    In  the case of termination of  a participant's association with the Company
for reasons other than death, options and SARs remain exercisable, to the extent
they were exercisable immediately prior to termination, for three months (or for
the remainder of  their original  term, if  less), shares  of restricted  Common
Stock  must be resold to the Company,  and other awards to which the participant
was not  irrevocably entitled  prior to  termination will  be forfeited,  unless
otherwise   provided.  If  any  such  association   is  terminated  due  to  the
participant's discharge for cause which, in the opinion of the Option Committee,
casts such discredit on the participant  as to justify immediate termination  of
any  award under the Equity Incentive  Plan, such participant's options and SARs
may be terminated immediately.
 
    In the event of a  consolidation or merger in which  the Company is not  the
surviving  corporation or which results in  the acquisition of substantially all
of the Company's outstanding Common Stock by  a single person or entity or by  a
group  of persons and/or entities acting in concert  or in the event of the sale
or transfer of substantially all of  the Company's assets, the Option  Committee
may  determine that (i) each outstanding  option and SAR will become immediately
exercisable  unless  otherwise  provided  at  the  time  of  grant,  (ii)   each
outstanding share of restricted Common Stock will immediately become free of all
restrictions   and  conditions,   (iii)  all  conditions   on  deferred  grants,
performance awards and supplemental grants which  relate only to the passage  of
time  and continued  employment will  be removed  and (iv)  all loans  under the
Equity Incentive Plan will be forgiven.  The Committee may also arrange to  have
the  surviving or acquiring corporation or affiliate  assume any award held by a
participant or grant a replacement award. If the optionee is terminated after  a
change  in  control by  the Company  without cause,  or in  the case  of certain
officers designated from  time to  time by  the Option  Committee resigns  under
certain  circumstances, within  two years following  the change  in control, all
unvested options will vest and all  options will be exercisable for the  shorter
of  four years or their original duration and all other awards will vest. If the
option committee makes no such  determination, outstanding awards to the  extent
not fully vested will be forfeited.
 
    CERTAIN FEDERAL INCOME TAX CONSEQUENCES.  The following discussion, which is
based on the law as in effect on June 1, 1996, summarizes certain federal income
tax consequences of participation in the Equity Incentive Plan. The summary does
not  purport to cover  federal employment tax or  other federal tax consequences
that may  be associated  with  the plans,  nor does  it  cover state,  local  or
non-U.S. taxes.
 
    In  general,  an  optionee realizes  no  taxable  income upon  the  grant or
exercise of an ISO. However, the exercise of an ISO may result in an alternative
minimum tax liability to the optionee. With certain exceptions, a disposition of
shares purchased under an ISO within two years from the date of grant or  within
one  year  after  exercise  produces  ordinary income  to  the  optionee  (and a
corresponding deduction is available to the  company) equal to the value of  the
shares  at the  time of  exercise less the  exercise price.  Any additional gain
recognized in the disposition is treated as a capital gain for which the Company
is not entitled to a deduction. If  the optionee does not dispose of the  shares
until  after the expiration of these one- and two-year holding periods, any gain
or loss recognized upon a subsequent sale is treated as a long-term capital gain
or loss for which the Company is not entitled to a deduction.
 
                                       66
<PAGE>
    In general, in the case of a nonstatutory option the optionee has no taxable
income at the time of grant but  realizes income in connection with exercise  of
the  option in an  amount equal to the  excess (at the time  of exercise) of the
fair market value of the shares acquired upon exercise over the exercise  price,
a  corresponding deduction  is available to  the Company, and  upon a subsequent
sale or exchange of the shares,  appreciation or depreciation after the date  of
exercise  is  treated as  capital  gain or  loss for  which  the Company  is not
entitled to a deduction. In  general, an ISO that  is exercised more than  three
months  after termination  of employment  (other than  termination by  reason of
death) is treated  as a nonstatutory  option. ISOs granted  after 1986 are  also
treated  as nonstatutory options to the  extent they first become exercisable by
an individual  in  any calendar  year  for shares  having  a fair  market  value
(determined as of the date of grant) in excess of $100,000.
 
    Under  the so-called "golden  parachute" provisions of  the Internal Revenue
Code, the vesting or accelerated exercisability  of awards in connection with  a
change  in control of  the Company may be  required to be  valued and taken into
account in determining whether participants have received compensatory payments,
contingent on  the change  in control,  in excess  of certain  limits. If  these
limits   are  exceeded,  a  substantial  portion   of  amounts  payable  to  the
participant, including  income recognized  by reason  of the  grant, vesting  or
exercise  of  awards under  the  Equity Incentive  Plan,  may be  subject  to an
additional 20% federal tax and may be nondeductible to the Company.
 
    GRANTS.  Mr. Comrie has been granted NQSOs expiring on various dates through
June 17, 2005 to purchase 756,691 shares  of Common Stock at a price of  $0.5907
per  share. Of  the NQSOs, 417,693  are currently exercisable,  and 111,990 will
become exercisable on July 17, 1997 and up to an additional 227,008 shares  (the
"Additional  Shares") will become  exercisable on June 17,  2000. The vesting of
NQSOs to purchase  56,752 Additional  Shares will  be accelerated  in each  year
based  upon the  attainment of  certain performance  goals as  determined by the
Board of Directors. Each of Mr. Comrie's options are exercisable for a period of
five years from the date of vesting.
 
    Mr. Grina has been granted NQSOs expiring on various dates through April 26,
2003 to purchase 300,000 shares of Common  Stock at a price of $6.25 per  share.
The  NQSOs are subject to vesting over a three-year period, of which 100,000 are
fully vested and currently  exercisable. NQSOs to  purchase 200,000 shares  will
become  exercisable on April 26,  1999; however, the vesting  of 100,000 of such
shares will be accelerated on  each of the first  and second anniversary of  the
date  of grant based upon attainment  of certain performance goals as determined
by the Board of  Directors. Each of  Mr. Grina's options  are exercisable for  a
period of five years from the date of vesting. Mr. Grina's options will be fully
vested,  notwithstanding the attainment of performance goals, on April 26, 1999.
In addition, all of his  options become immediately exercisable, without  regard
to  the  vesting period,  upon a  Change of  Control (as  defined in  the Equity
Incentive Plan)  and upon  other corporate  changes described  in the  agreement
evidencing his options.
 
    Mr.  Miller has  been granted NQSOs  expiring December 29,  2000 to purchase
50,000 shares of Common Stock at a price of $1.652 per share. The NQSOs vest  at
a rate of 20% on each anniversary of the date of grant.
 
    THE DIRECTORS PLAN.
 
    On  May  30,  1996,  the Company  adopted  the  1996  Non-Employee Directors
Automatic Stock  Option Plan  (the  "Directors Plan"),  which provides  for  the
automatic  grant of stock options to non-employee directors to purchase up to an
aggregate of 200,000 shares. Under the Directors Plan, options to acquire  6,000
shares  of Common Stock are automatically  granted to each non-employee director
who is a  director on January  1 of  each year. In  addition, each  non-employee
director  serving on the Board of Directors  effective on the date of the Common
Stock Offering will receive, and in  the future each newly elected  non-employee
director on the date of his or her first appointment or election to the Board of
Directors will receive, an automatic grant of options to acquire 7,000 shares of
Common Stock.
 
    Although  grants of the options under  the Directors Plan are automatic, and
the Directors Plan is intended  to be largely self-administering, the  Directors
Plan will be administered by either the Board of
 
                                       67
<PAGE>
Directors  or a committee designated  by the Board of  Directors, which will, to
the extent necessary,  administer and  interpret the Directors  Plan (the  "Plan
Administrator").  Stock  options awarded  under  the Directors  Plan  are priced
automatically at an exercise price equal to the market price of the Common Stock
on the date  of grant.  If at any  time no  public market for  the Common  Stock
exists,  the Plan Administrator is empowered to determine the fair market value.
Under the Directors Plan,  initial option grants vest  over a three-year  period
and are exercisable for a period of 10 years from the date of grant. On the date
of  this Prospectus,  options to  purchase an aggregate  of 28,000  shares at an
exercise price equal to the initial offering  price of the Common Stock will  be
granted to non-employee directors under the Directors Plan.
 
EMPLOYMENT AND CONSULTING AGREEMENTS
 
    The  Company has  entered into  a three-year  employment agreement  with Mr.
Fotheringham providing for full-time employment at an annualized base salary  of
$250,000  for 1996, $275,000  for 1997 and  $300,000 for 1998.  In addition, Mr.
Fotheringham is entitled to receive an annual bonus of up to $100,000  depending
on  the achievement  of specified annual  link installation goals.  The goal for
each year will  be established  based on the  operating budget  approved by  the
Board of Directors. The agreement precludes Mr. Fotheringham from competing with
the  Company for one year  after the cessation of  his employment, regardless of
the reason for such cessation.
 
    The Company  has entered  into a  three-year employment  agreement with  Mr.
Comrie  providing  for full  time  employment at  an  annualized base  salary of
$160,000 through December 31,  1995, $200,000 from January  1, 1996 to July  16,
1997 and $240,000 from July 17, 1997 to July 16, 1998. Mr. Comrie is entitled to
receive  an  annual bonus  of up  to  $100,000 depending  on the  achievement of
specified annual  link  installation goals.  The  goal  for each  year  will  be
established based on the operating budget approved by the Board of Directors. As
part   of  the  employment  agreement,  the   Company  provided  Mr.  Comrie  an
interest-free loan in the amount of $30,000 and forgave payment of such loan  on
January  1,  1996.  The forgiveness  of  such  loan has  been  accounted  for as
compensation expense on  the 1995 statement  of operations of  the Company.  The
agreement also precludes Mr. Comrie from competing with the Company for one year
after  the cessation of employment, regardless of the reason for such cessation.
The agreement may be terminated at any  time by either party and provides  that,
if the Company terminates Mr. Comrie without cause or Mr. Comrie's employment is
terminated  due  to his  disability or  death,  Mr. Comrie  will be  entitled to
continue to receive the full amount of his base salary and any other benefits to
which he would have otherwise  been entitled for a period  of one year from  the
date  of such termination.  See "-- Stock Option  Plans" regarding stock options
granted to Mr. Comrie pursuant to his employment agreement.
 
    The Company  has  entered  into  an employment  agreement  with  Mr.  Grina,
providing  for full time  employment on an  at will basis  at an annualized base
salary of $190,000 through April 30, 1997. In addition, Mr. Grina is entitled to
receive an annual  bonus of  up to $100,000  depending upon  the achievement  of
specified  annual  link  installation goals.  The  goal  for each  year  will be
established based on the  operating budget approved by  the Board of  Directors.
The  agreement precludes Mr. Grina from competing  with the Company for one year
after the  cessation  of his  employment,  regardless  of the  reason  for  such
cessation.  The agreement  may be  terminated at  any time  by either  party and
provides that, if the Company terminates Mr. Grina without cause or Mr.  Grina's
employment  is terminated  due to  his disability  or death,  Mr. Grina  will be
entitled to continue to receive the full amount of his base salary and any other
benefits to which  he would have  otherwise been  entitled for a  period of  six
months  from the date of such termination. See "-- Stock Option Plans" regarding
stock options granted to Mr. Grina pursuant to his employment agreement.
 
    The Company has also entered into  an employment agreement with Mr.  Miller,
providing  for full time employment at an  annual base salary equal to $150,000.
His employment agreement provides  for the payment by  the Company of an  annual
bonus  in designated amounts based upon the achievement of specified performance
goals. The agreement has a term of three years and precludes him from  competing
with  the Company for one year after  the cessation of employment, regardless of
the reason for such
 
                                       68
<PAGE>
cessation. See "-- Stock  Option Plans" regarding stock  options granted to  Mr.
Miller  pursuant to  his employment agreement.  The employment  agreement may be
terminated at any time by  the Company or Mr. Miller  and provides that, if  the
Company  terminates Mr. Miller's  employment without cause  or his employment is
terminated due to his  disability or death, Mr.  Miller may continue to  receive
the full amount of his base salary and any other benefits to which he would have
otherwise  been  entitled for  a  period of  six months  from  the date  of such
termination.
 
    The Company  has entered  into a  three-year consulting  agreement with  Mr.
Pierson  on May 8, 1995,  providing for base fees  of $80,000 for 1995, $140,000
for 1996  and $80,000  for  1997, subject  to extension  at  the option  of  the
Company.  The  agreement  also precludes  Mr.  Pierson from  competing  with the
Company for  one year  after termination  of the  agreement, regardless  of  the
reason  for such  termination. The  agreement may be  terminated at  any time by
either party and provides  that, if the Company  terminates Mr. Pierson  without
cause  or Mr. Pierson terminates his  consulting agreement for "good reason" (as
specified in the agreement), Mr. Pierson will be entitled to continue to receive
the full amount of his base fees and  any other benefits to which he would  have
otherwise  been  entitled  for  a period  of  one  year from  the  date  of such
termination. See "Certain Transactions -- Pierson & Burnett Transactions."
 
                                       69
<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
    The following table  sets forth certain  information, as of  June 19,  1996,
regarding  the beneficial  ownership of  the Company's  Common Stock  by (i) the
directors and executive officers of the  Company, (ii) each person known by  the
Company  to own beneficially more than five percent of the outstanding shares of
the Company's Common Stock and (iii)  all executive officers and directors as  a
group  assuming,  in each  case,  that the  Merger  has been  completed  and the
Landover Partnerships have been dissolved.
 
<TABLE>
<CAPTION>
                                                             BENEFICIAL OWNERSHIP         BENEFICIAL OWNERSHIP AFTER
                                                              PRIOR TO OFFERINGS                  OFFERINGS
                                                           -------------------------  ----------------------------------
NAME                                                          NUMBER       PERCENT           NUMBER           PERCENT
- ---------------------------------------------------------  -------------  ----------  --------------------  ------------
<S>                                                        <C>            <C>         <C>                   <C>
Vernon L. Fotheringham (1)...............................      3,545,063       11.8%       3,545,063               9.4%
W. Theodore Pierson, Jr. (2).............................      2,455,407        8.2        2,455,407               6.5
High Sky Inc. (3)........................................      1,748,604        5.8        1,748,604               4.7
Landover Holdings Corporation (4)........................      8,268,582       27.4        8,268,582              22.0
Advent International Corporation (5).....................      3,186,238       10.5        3,186,238               8.4
Ameritech Development Corp. (6)..........................      1,677,745        5.5        1,677,745               4.3
Steven D. Comrie (7).....................................        302,676        1.0          302,676                 *
James C. Cook (8)........................................        133,830          *          140,830(14)             *
J.C. Demetree, Jr. (9)...................................      1,055,288        3.5        1,055,288               2.8
Mark C. Demetree (10)....................................      1,104,038        3.7        1,111,038(14)           2.9
Andrew I. Fillat (5).....................................      3,186,238       10.5        3,193,238(14)           8.4
Matthew C. Gove (11).....................................        441,753        1.5          441,753               1.2
T. Allan McArtor.........................................              0          *            7,000(14)             *
Laurence S. Zimmerman (4)................................      8,268,582       27.4        8,268,582              22.0
Thomas A. Grina (12).....................................        100,000          *          100,000                 *
James D. Miller (13).....................................         10,000          *           10,000                 *
All executive officers and directors as a group
 (1)(2)(4)(5)(7)(8)(9)(10)(11)(12)(13)(14)...............     20,476,045       66.6%      10,872,252(8)(15)       28.4%
</TABLE>
 
- ------------------------
Unless otherwise indicated, the business address of each director and  executive
officer  named above is c/o Advanced Radio Telecom Corp., 500 108th Avenue N.E.,
Suite 2600, Bellevue, Washington 98004.
 
 *  Less than 1.0%.
 
 (1) Includes 104,273 shares of Common Stock subject to an option owned by SERP.
    See "Certain Transactions -- SERP Agreement."
 
 (2) Includes 2,455,407 shares of Common  Stock issuable upon completion of  the
    Merger.  Also includes 44,694 shares subject to an option owned by SERP. See
    "Certain Transactions  --  SERP Agreement."  Mr.  Pierson's address  is  c/o
    Pierson & Burnett L.L.P., 1667 K. Street, N.W., Washington, D.C. 20006.
 
 (3) High Sky Inc. is the general partner of High Sky and High Sky II and may be
    deemed  the  beneficial  owner  of all  shares  held  by  such partnerships.
    Includes  1,398,883  and  349,721  shares  of  Common  Stock  issuable  upon
    completion  of the Merger  to High Sky  and High Sky  II, respectively. Also
    includes 119,171  and  29,796 shares  held  by High  Sky  and High  Sky  II,
    respectively,  subject to an option owned by SERP. See "Certain Transactions
    -- SERP  Agreement."  High Sky  Inc.'s  address  is c/o  Frank  S.  Phillips
    Company, 6106 MacArthur Blvd., Bethesda, Maryland 20816.
 
 (4)  Includes 37,500 shares issuable upon  exercise of Indemnity Warrants. Does
    not include 294,489  shares, 1,375,699 shares,  5,276,440 shares and  95,719
    shares issuable upon the Merger held by E1, E2, E2-2 and E2-3, respectively,
    each  a limited partnership whose general partner is controlled by LHC. Upon
    the effectiveness of the Merger, these partnerships will dissolve. Including
    the shares  owned by  such partnerships,  LHC beneficially  owns  15,310,929
    shares  of  Common Stock  constituting  50.9% of  the  Company's outstanding
    securities prior  to  the  Offerings.  LHC  is  controlled  by  Laurence  S.
    Zimmerman.  LHC's address is  667 Madison Avenue, New  York, New York 10021.
    See "-- Voting Trust Agreement."
 
 (5) Includes 2,882,659 shares,  3,029 shares and  141,050 shares issuable  upon
    the  Merger and  151,908 shares, 160  shares and 7,432  shares issuable upon
    exercise of Bridge Warrants, respectively owned by Global Private Equity II,
    L.P., Advent International II, L.P. and Advent Partners, L.P. (collectively,
    the "Advent Partnerships"), each a limited partnership whose general partner
    is controlled  by Advent  International Corp.  ("Advent"). Mr.  Fillat is  a
    director,  officer and stockholder of Advent. The address of Advent and each
    of the  Advent Partnerships  is 101  Federal Street,  Boston,  Massachusetts
    02110.
 
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 (6)  Includes 635,609  shares issuable upon  the Merger and  877,136 shares and
    165,000 shares issuable upon  exercise of the  Ameritech Warrant and  Bridge
    Warrants,  respectively. The address of Ameritech  is 30 South Wacker Drive,
    Chicago, Illinois 60601. See  "Certain Transactions -- Ameritech  Financing;
    Ameritech Strategic Distribution Agreement."
 
 (7)  Includes 302,676 shares currently issuable  upon exercise of options. Does
    not include  454,015 issuable  upon exercise  of the  non-vested portion  of
    options. See "Management -- Stock Option Plans."
 
 (8)  Includes  140,830 shares  beneficially owned  by  James C.  Cook including
    22,000 shares issuable upon  exercise of Bridge  Warrants and 73,542  shares
    and  38,288 shares issuable upon the Merger  as a limited partner in E-2 and
    E2-3, respectively. Mr. Cook will become a director of the Company upon  the
    date of this Prospectus.
 
(9)  Does not include 154,000 shares  issuable upon exercise of Bridge Warrants,
    162,500 shares issuable  upon exercise  of Indemnity  Warrants or  4,221,152
    shares  issuable  upon  the Merger  held  in  each case  by  members  of Mr.
    Demetree's family (or  a trust  for their  benefit), of  which he  disclaims
    beneficial ownership. J.C. Demetree, Jr.'s address is c/o Demetree Brothers,
    3740 Beach Boulevard, Suite 300, Jacksonville, Florida 32207.
 
(10)  Includes 48,750 shares issuable upon  exercise of Indemnity Warrants. Does
    not include  154,000  shares  issuable upon  exercise  of  Bridge  Warrants,
    113,750  shares issuable  upon exercise  of Indemnity  Warrants or 4,221,152
    shares issuable  upon  the  Merger held  in  each  case by  members  of  Mr.
    Demetree's  family (or  a trust  for their  benefit), of  which he disclaims
    beneficial ownership. Mark C. Demetree's address is c/o North American  Salt
    Co., 8300 College Boulevard, Overland Park, Kansas 66210.
 
(11)  Includes  441,753  shares  issuable  upon  the  Merger  owned  by Hedgerow
    Corporation of Maine ("Hedgerow"), which is controlled by Mr. Gove. Does not
    include shares  owned  beneficially by  LHC,  of which  Mr.  Gove  disclaims
    beneficial  ownership. Hedgerow  from time to  time acts as  a consultant to
    LHC. Mr. Gove's address is 215 West 84th Street, New York, New York 10024.
 
(12) Includes 100,000 shares currently issuable upon exercise of an option.
 
(13) Includes 10,000 shares currently issuable upon exercise of an option.
 
(14) Includes 7,000 shares issuable upon  exercise of options anticipated to  be
    granted under the Directors Plan upon the consummation of the Offerings.
 
(15) Reflects the resignations of Messrs. J.C. Demetree, Jr., Gove and Zimmerman
    and  the elections as directors of Messrs. Cook and McArtor upon the date of
    this Prospectus. Does not include 8,268,582 shares beneficially owned by LHC
    and held in trust  by trustees, all  of whom are  directors of the  Company,
    pursuant  to  a  Voting Trust  Agreement,  of which  such  trustees disclaim
    beneficial ownership. See "-- Voting Trust Agreement." Includes 7,000 shares
    beneficially owned by  each of Messrs.  Mark C. Demetree,  Fillat, Cook  and
    McArtor  issuable upon exercise of options to be granted under the Directors
    Plan upon the consummation of the Offerings.
 
    Upon completion of the CommcoCCC Acquisition, Columbia Capital  Corporation,
as  general partner of two of the stockholders of CommcoCCC, and Commco, L.L.C.,
the remaining  stockholder of  CommcoCCC, will  beneficially own  8,842,154  and
7,707,846  shares, respectively,  of Common  Stock, including  26,715 and 23,285
shares,  respectively,  issuable  upon  exercise  of  the  CommcoCCC   Warrants,
constituting  16.3% and 14.2%, respectively, of the Company's Common Stock after
the  Offerings  (assuming  the   Underwriters'  over-allotment  option  is   not
exercised).  Assuming  the  consummation  of  the  Offerings  and  the CommcoCCC
Acquisition as of the date of this Prospectus, the Company would have 54,086,498
shares of Common Stock outstanding.
 
VOTING TRUST AGREEMENT
 
    Pursuant to  a  proposed  Voting  Trust  and  Irrevocable  Proxy  Agreement,
effective  on the date of this Prospectus, LHC will deposit all of its shares of
ART Common Stock in trust  with Messrs. Mark C.  Demetree, Andrew I. Fillat  and
Vernon  L. Fotheringham with irrevocable instructions to vote such shares on all
matters submitted to a vote of the stockholders of the Company in proportion  to
the  vote of other stockholders of the  Company. The voting trust will expire on
the tenth anniversary of the  date of this Prospectus,  but is subject to  early
termination  in the event of (i) the death  of Laurence S. Zimmerman or (ii) the
sale by LHC of such  shares to unaffiliated parties.  The trustees of the  trust
will be indemnified by the Company.
 
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                              CERTAIN TRANSACTIONS
 
FORMATION OF ART
 
    The  Company was organized in  August 1993 by Vernon  L. Fotheringham and W.
Theodore Pierson, Jr.,  for the purpose  of obtaining 38  GHz licenses from  the
FCC.  The  initial  stockholders, including  Messrs.  Fotheringham  and Pierson,
purchased for $.01 per share ART Common Stock in a private placement which,  net
of  certain subsequent transfers, currently constitute an aggregate of 6,000,470
shares of Common Stock.
 
HIGH SKY PRIVATE PLACEMENTS
 
    In November 1993 and March 1994, ART raised $60,000 and $30,000 through  the
sale  of its common  stock (which, net  of sales and  acquisitions of additional
shares, now constitute an  aggregate of 1,398,883 shares  and 349,721 shares  of
Common  Stock, respectively)  to High  Sky Limited  Partnership and  High Sky II
Limited  Partnership  ("High   Sky  II"   and,  collectively,   the  "High   Sky
Partnerships").  In March 1994, ART borrowed $70,000  from High Sky II. The loan
was evidenced by a promissory  note executed by ART and  payable to High Sky  II
(the "High Sky Note"). Pursuant to an Agreement dated March 1, 1995, High Sky II
sold the High Sky Note to Vernon L. Fotheringham and W. Theodore Pierson, Jr. in
exchange  for  two new  promissory notes,  bearing interest  at 7.5%  per annum,
executed by Messrs. Fotheringham and Pierson in the principal amounts of $52,675
and $22,575,  respectively  (the  "Fotheringham/Pierson  Notes"),  with  payment
secured  by pledges of  shares of Common Stock  owned by them.  The terms of the
notes were as  favorable as could  be negotiated with  unrelated third  parties.
After  the assignment and exchange, Messrs. Fotheringham and Pierson transferred
the  High   Sky  Note   to  the   Company  as   a  capital   contribution.   The
Fotheringham/Pierson  Notes,  which are  due in  August 1997  and which  are now
unsecured, are currently held by LHC (as defined below).
 
ART WEST JOINT VENTURE
 
    The Company is party to the ART West Management Agreement, pursuant to which
it manages the business and assets of ART West, a joint venture between ART  and
Extended.  Mark  T. Marinkovich,  Vice  President and  General  Manager, Western
Region of the Company is also the  President and a stockholder of Extended.  See
"Business  -- Agreements  Relating to  Licenses and  Authorizations --  ART West
Joint Venture" and  "Principal Stockholders."  In connection with  the ART  West
Joint  Venture, ART issued to Extended 368,127  shares of Common Stock. Of these
368,127 shares,  15,678 shares  are  subject to  an  option owned  by  Southeast
Research  Partners. See "-- SERP Agreement." In June 1996, the Company agreed to
acquire Extended's interest in ART West  for $6,000,000 in cash, subject to  FCC
approval.
 
ORGANIZATION OF TELECOM
 
    ART  and  Landover  Holdings Corporation  ("LHC")  organized  Advanced Radio
Telecom Corp. ("Telecom") on March 28,  1995, and purchased for $.001 per  share
340,000  shares of  Class A common  stock and  640,000 shares of  Class B common
stock of  Telecom, respectively,  which, after  giving effect  to  anti-dilution
adjustments  resulting from issuances of preferred stock as described in "-- LHC
Purchase Agreement," certain  transfers and  the transactions  described in  "--
February  1996  Reorganization" and  "--  Merger," currently  are  equivalent to
10,013,055 shares and 7,512,076, shares respectively, after giving effect to the
November 1995  redemption  of shares  of  Common Stock.  In  addition,  Hedgerow
Corporation  of Maine ("Hedgerow")  and Toro Financial  Corp. ("Toro") purchased
for $.001 per  share 15,000 shares  and 5,000 shares,  respectively, of  Telecom
Class A common stock which, after such anti-dilution adjustments and the Merger,
currently  are equivalent to 441,753 shares  and 147,251 shares of Common Stock,
respectively. LHC is controlled by Laurence S. Zimmerman. Hedgerow is controlled
by Matthew C. Gove, a director of the Company. Hedgerow and Toro are consultants
to LHC.
 
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<PAGE>
LHC PURCHASE AGREEMENT
 
    GENERAL.  Pursuant to a Purchase  Agreement, dated April 21, 1995 (the  "LHC
Purchase  Agreement") among ART, LHC  and Telecom, LHC, on  behalf of itself and
its designees, agreed  to purchase  additional securities of  Telecom (the  "LHC
Stock")  for an aggregate  purchase price of  $7,000,000 (the "Purchase Price"),
which additional securities would dilute only LHC's interest in the Company.  In
addition, ART and Telecom entered into the ART Services Agreement. Moreover, ART
and  its stockholders agreed with  Telecom and its stockholders  to enter into a
revised stockholders  agreement  (the  "May  1995  Stockholders  Agreement"),  a
registration  rights agreement and a  merger agreement. Messrs. Fotheringham and
Pierson deposited 2,017,704 and 1,816,559  shares of Common Stock,  respectively
(the  "Escrow Shares"), under such agreement  to be released upon achievement by
the Company of certain performance goals (the "Escrow Arrangement"). The  Escrow
Shares were released to Messrs. Fotheringham and Pierson in part on November 13,
1995  as a result of the EMI Asset  Acquisition, and the balance was released on
February 2,  1996  in  connection  with the  February  1996  Reorganization  (as
defined).
 
    Upon  the first closing  under the LHC  Purchase Agreement, on  May 8, 1995,
Telecom received $700,000  from E2-2  Holdings, L.P. ("E2-2")  and E2  Holdings,
L.P.  ("E2"). In addition,  E2-2 committed to  subscribe for up  to 50.0% of the
Purchase Price, matching other investors  under the LHC Purchase Agreement  with
protection  from dilution to  the extent such matching  funds were not required.
The general partner of E2-2 and E2 is controlled by LHC. E2-2's limited partners
include J.C. Demetree, Jr. and Mark  C. Demetree, directors of the Company,  and
their  affiliates. In addition, E2-2  granted to LHC an  option to purchase from
E2-2 35,873  shares of  Series A  preferred stock  (which convert  into  466,349
shares  of Common Stock  prior to the  Offerings). This option  was exercised in
November 1995. See "Principal Stockholders."
 
    The additional payments  on the  Purchase Price  were made  by the  Landover
Partnerships  (as defined  below) as  follows: $700,000  on August  22, 1995 and
$600,000 on October 19, 1995. On November 13, 1995, the Advent Partnerships  (as
described  below) paid the  $5.0 million balance  of the Purchase  Price and the
Company paid LHC an  aggregate of $391,750 for  expenses. Also, on November  13,
1995,  Telecom,  ART  and  LHC  agreed  that  the  LHC  Purchase  Agreement  was
substantially completed.
 
    ART SERVICES AGREEMENT.   Pursuant to  the LHC Purchase  Agreement, ART  and
Telecom  entered into a Services Agreement, dated May 8, 1995 (the "ART Services
Agreement") pursuant to which, for  a 20-year term, Telecom provides  management
services  for,  and  receives  75.0%  of the  cash  flow  from  operations after
deducting certain related direct expenses under wireless licenses held by ART.
 
    LANDOVER PARTNERSHIPS.  Between May 8,  1995 and November 13, 1995, the  LHC
Stock was diluted by purchases of series of Telecom preferred stock by E2-2, E2,
E1  Holdings L.P. ("E1")  and E2-3 Holdings, L.P.  ("E2-3" and collectively with
E1, E2 and E2-2, the "Landover Partnerships"), each a limited partnership  whose
general  partner is  controlled by  LHC, in  separate private  placements. E2-2,
which committed  to purchase  up  to $3.5  million  of Telecom  preferred  stock
matching  other investors  under the  LHC Purchase  Agreement, purchased 405,880
shares of Telecom Series  A preferred stock (which  will convert into  5,276,440
shares of Common Stock prior to the Offerings) for an aggregate of $946,600, and
LHC  purchased 35,873 shares of such Series A preferred stock from E2-2 for $1.1
million pursuant to an  option. E2 purchased an  aggregate of 105,823 shares  of
Telecom Series B preferred stock (which converts into 1,375,699 shares of Common
Stock  prior to the Offerings) for an aggregate of $842,400. E1 purchased 13,797
shares of Telecom Series A preferred  stock (which converts into 179,361  shares
of  Common Stock prior to  the Offerings) for an  aggregate of $60,000 and 8,856
shares of Telecom Series B preferred  stock (which converts into 115,128  shares
of  Common  Stock prior  to the  Offerings)  for an  aggregate of  $38,300. E2-3
purchased an  aggregate of  7,363 shares  of Telecom  Series C  preferred  stock
(which  converts into 95,719 shares of Common  Stock prior to the Offerings) for
an aggregate of $112,700. All of  the Landover Partnerships will liquidate  upon
effectiveness of the Merger. See "Principal Stockholders."
 
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<PAGE>
    ADVENT  PRIVATE PLACEMENT.  On November 13, 1995, ART sold, for an aggregate
of $5.0 million, $4.95 million  principal amount of 10%  notes due May 13,  1997
(the  "Advent Notes") and $50,000 stated amount  of ART Series A Preferred Stock
(collectively, with the  Advent Notes,  the "Advent/ART  Securities") to  Global
Private  Equity II,  L.P., Advent  International Investors  II, L.P.  and Advent
Limited Partnership  (collectively the  "Advent Partnerships"),  each a  limited
partnership  whose general partner  is controlled by  Advent International Corp.
("Advent") pursuant to a Securities Purchase Agreement, dated November 13, 1995,
among the  Advent Partnerships,  ART,  Telecom, Vernon  L. Fotheringham  and  W.
Theodore  Pierson, Jr. (the  "Advent Agreement"). The  Advent Agreement provided
among other things that the Advent/ART Securities were convertible into, and  in
the  February 1996 Reorganization described  below, were converted into, 232,826
shares of Telecom Series E preferred stock (which convert into 3,026,738  shares
of  Common Stock prior to  the Offerings). The Telecom  Series E preferred stock
provides, among other things, that the holders thereof have a right to designate
a director of  Telecom (and, after  the Merger, the  Company), which  director's
term was extended to an initial term of three years pursuant to the Stockholders
Agreement, as described below.
 
LHC AGREEMENTS
 
    Pursuant  to  the LHC  Purchase Agreement,  LHC and  Telecom entered  into a
strategic and financial consulting agreement, dated May 8, 1995, under which LHC
agreed to  provide  financial and  strategic  planning and  other  advisory  and
management services to the Company for a fee of $10,000 per month. The strategic
and  financial consulting  agreement was  terminated on  November 13,  1995, and
Telecom entered into a management consulting agreement with LHC, dated  November
13,  1995, for an initial term of one  year under which the Company will pay LHC
$420,000 per year and may  pay a fee in the  event LHC provides other  services,
such  as merger and acquisition advisory services  to the Company. Upon the date
of this  Prospectus, this  agreement will  be terminated  and LHC  will  receive
amounts otherwise due under this agreement through November 13, 1996.
 
SERP AGREEMENT
 
    Pursuant  to  a  letter  agreement, dated  July  12,  1995,  among Southeast
Research Partners ("SERP")  ART, Vernon  L. Fotheringham,  W. Theodore  Pierson,
Jr.,  High Sky Limited Partnership, High Sky II Limited Partnership and Extended
(the "SERP  Agreement"), SERP  agreed to  procure additional  capitalization  or
financial  assistance on behalf of ART.  Under the SERP Agreement, SERP received
options from the other parties to  such agreement to purchase, for an  aggregate
consideration of $210,000, 313,612 shares of Common Stock after giving effect to
the Merger and $245,000 in cash as a fee for introducing LHC to ART.
 
SERIES D PREFERRED STOCK ISSUANCE
 
    On  November  9,  1995,  Telecom  sold 61,640  shares  of  Telecom  Series D
preferred stock (which convert into 801,320 shares of Common Stock prior to  the
Offerings)  for  $2.0 million  in  a private  placement.  Telecom simultaneously
redeemed 807,924 shares of  Telecom common stock from  LHC for $2.0 million.  In
connection with the February 1996 Reorganization described below, LHC granted to
the  holders of such  Series D preferred  stock a contingent  option to purchase
400,634 shares of Telecom  common stock owned  by LHC at  a nominal price.  This
option will expire unexercised upon consummation of the Offerings.
 
FEBRUARY 1996 REORGANIZATION
 
    On  February 2, 1996, Telecom, ART  and their respective stockholders agreed
(the "February 1996 Reorganization") to an amendment and restatement of the  May
1995 Stockholders Agreement (as amended, the "Stockholders Agreement") providing
for   (i)  termination  effective   on  consummation  of   the  Offerings,  (ii)
reorganization of the capital structure of Telecom, including providing for  the
conversion  of Telecom  Class A  and Class  B common  stock into  Telecom common
stock, the revision of the terms and conversion into Telecom common stock  (upon
consummation of the Offerings) of the
 
                                       74
<PAGE>
Telecom  Series A, B, C, D, E and F  preferred stock and a 13 for 1 stock split,
(iii) the exchange of the Advent/ART  Securities for Telecom Series E  preferred
stock,  (iv) revision of provisions for election of directors, (v) amendment and
restatement of the Company's registration rights agreement, including waiver  of
registration  rights relating  to this offering,  (vi) release  of the remaining
Escrow Shares  to the  original owners  thereof,  (vii) the  change of  name  of
Telecom  to Advanced Radio Telecom Corp. and (viii) approval of a revised merger
agreement (the "Old  Merger Agreement")  providing for  the merger  of ART  into
Telecom (the "Old Merger").
 
AMERITECH FINANCING; AMERITECH STRATEGIC DISTRIBUTION AGREEMENT
 
    On February 2, 1996, Ameritech Development Corp. ("Ameritech") purchased for
an  aggregate of $2.5 million 48,893 shares of Telecom Series F preferred stock,
par value $0.001 per share, (the "Ameritech Financing") convertible into 635,609
shares of Common Stock prior to the Offerings. In addition, Telecom entered into
a letter of intent with Ameritech Corp., the parent of Ameritech, to enter  into
the  Ameritech  Strategic  Distribution Agreement  and  in  connection therewith
granted to Ameritech  a ten-year warrant  to purchase 877,136  shares of  Common
Stock  of the Company exercisable  at a price of  $.01 per share (the "Ameritech
Warrant"). On  April 29,  1996,  Telecom entered  into the  Ameritech  Strategic
Distribution Agreement. The Company has a call on the Telecom Series F preferred
stock and the Ameritech Warrant in the event Ameritech terminates such agreement
in  the first  year or two  years, respectively,  of its term.  See "Business --
Strategic Alliances -- Ameritech Strategic Distribution Agreement."
 
BRIDGE FINANCING
 
    On March 8, 1996, Telecom entered into a financing (the "Bridge  Financing")
pursuant to which it issued $5.0 million of 10% unsecured notes due in 1998 (the
"Bridge  Notes")  and  five-year warrants  to  purchase  up to  an  aggregate of
1,100,000 shares of  Telecom common stock  at a  price of $6.25  per share  (the
"Bridge  Warrants")  to  private  investors  including  (i)  affiliates  of J.C.
Demetree, Jr. and Mark  C. Demetree, directors of  the Company, (ii) the  Advent
Partnerships  and (iii) Ameritech, who invested $700,000, $725,000 and $750,000,
respectively,  in  the  Bridge  Notes   and  Bridge  Warrants.  See   "Principal
Stockholders."
 
EQUIPMENT FINANCING
 
    On  April 1, 1996 CRA, Inc. ("CRA")  provided the Company with $2,445,000 in
equipment financing (the "Equipment Financing")  for the purchase from P-Com  of
38  GHz radio  equipment secured  by the  equipment, the  Company's $1.0 million
letter of credit and a $500,000 letter of credit provided by J.C. Demetree,  Jr.
and Mark C. Demetree, directors of the Company, and LHC, a principal stockholder
of  the  Company  (the "Indemnitors").  To  evidence its  obligations  under the
Equipment Financing  the  Company  executed  in  favor  of  CRA  its  $2,445,000
Promissory  Note  (the "Equipment  Note") which  note is  payable in  24 monthly
installments of $92,694 with a final payment of $624,305 due April 1, 1998.  The
Indemnitors  also agreed to provide the Company with funds and support for up to
$2.0 million of its obligations in the event of default on the Equipment Note or
draw against the Company's letter of credit. Pursuant to an arrangement approved
by the Company's disinterested directors on February 16, 1996, the Company  paid
to  the Indemnitors,  or their  designees an aggregate  of $225,000  in cash and
five-year warrants to purchase  an aggregate of 325,000  shares of Common  Stock
(the "Indemnity Warrants") on terms substantially similar to the Bridge Warrants
as  compensation  for such  indemnity. LHC  has  assigned Indemnity  Warrants to
purchase 125,000 shares of Common Stock to a consultant to LHC.
 
PIERSON & BURNETT TRANSACTIONS
 
    W. Theodore  Pierson, Jr.,  Executive Vice  President, General  Counsel  and
Secretary  of the Company is  a principal in the law  firm of Pierson & Burnett,
L.L.P., which regularly provides legal services to the Company. During the  year
ended December 31, 1995, the Company paid Pierson & Burnett, L.L.P. $210,000 for
such  services. The  Company believes  that the  terms of  its relationship with
Pierson & Burnett, L.L.P. are at least  as favorable to the Company as could  be
obtained from an unaffiliated party.
 
                                       75
<PAGE>
See  "Management -- Executive  Compensation" and "Principal  Stockholders" for a
description of  Mr. Pierson's  consulting  agreement with  the Company  and  for
information  regarding his share  ownership. The Company  subleases office space
for its regional office in Washington,  D.C. from Pierson & Burnett, L.L.P.  The
Company believes that the terms of its sublease are at least as favorable to the
Company  as  could be  obtained  from an  unaffiliated  party. See  "Business --
Properties."
 
AMERICAN WIRELESS DEVELOPMENT AGREEMENT
    The Company is party to a  letter of intent with American Wireless  pursuant
to which the Company will fund, subject to definitive documentation, $700,000 to
$1.0  million for  research and  development in  exchange for  a first  right to
purchase American  Wireless' production  capacity  of the  new radios  and  will
receive  a per-unit fee  on radios sold  by American Wireless  to third parties.
Vernon L. Fotheringham, the Chairman  of the Company, is  a director and a  6.0%
stockholder  of American Wireless.  Mr. Fotheringham has  recused himself in all
negotiations regarding agreements between the Company and American Wireless.
 
QUESTTV INVESTMENT
    The Company has  a non-binding  arrangement with  Quest Computer  Television
Company,  L.L.C.  ("QuestTV")  pursuant  to which  the  Company  would purchase,
subject to, among other things, definitive documentation and consummation of the
Offerings, equity interests of QuestTV for  $1.5 million. QuestTV is seeking  to
develop   a  nationwide  network   of  franchises  offering   retail  access  to
sophisticated video  and  data transmission  and  storage technology.  T.  Allan
McArtor,  who  will become  a  director of  the Company  upon  the date  of this
Prospectus, is the president and chief executive officer of QuestTV.
 
COMMCOCCC ACQUISITION
    On July    , 1996,  the Company  entered into the  CommcoCCC Agreement  with
CommcoCCC which provides for the acquisition, subject to FCC approval, of 129 38
GHz  wireless  broadband authorizations  in  exchange for  16,500,000  shares of
Common Stock, or  30.5% of the  Company on  a fully diluted  basis after  giving
effect  to the  Offerings. The  stockholders of  CommcoCCC simultaneously loaned
$3.0 million to the Company, bearing interest  at the prime rate and payable  on
September  30,  1996, and  received  three-year warrants  to  purchase up  to an
aggregate of 50,000 shares of Common Stock  at a price of $15.00 per share.  The
CommcoCCC  Financing is secured by  a security interest in  all of the assets of
the Company, including a pledge of the Company's stock in Telecom. After closing
of the CommcoCCC Acquisition, the Company has agreed to nominate one  individual
designated  by  CommcoCCC's  stockholders and  acceptable  to the  Company  as a
director of the Company.
 
MERGER
    On June 26, 1996, Telecom, ART and a wholly-owned subsidiary of ART ("Merger
Sub") entered  into  a revised  merger  agreement, superseding  the  Old  Merger
Agreement  (the "Merger Agreement"), which provides for the Merger of Merger Sub
into Telecom. Upon completion  of the Merger, the  stockholders of Telecom  will
receive   20,073,443  shares  of  Common  Stock,   and  Telecom  will  become  a
wholly-owned subsidiary of ART and change its name to "ART Licensing Corp."  The
consummation  of the Merger  is contingent on receipt  of FCC approval therefor,
approval of the holders  of Telecom capital stock  and all ART stockholders  and
receipt of a tax opinion. The FCC has indicated that it will approve the Merger,
and  the  Company expects  to  complete it  shortly prior  to  the date  of this
Prospectus. The Merger  Agreement further  provides that  if the  Merger is  not
approved by the FCC by May 13, 1997, the shares of Telecom common stock owned by
ART  will  be surrendered  to  Telecom for  nominal  consideration, and  the ART
Services Agreement will be amended to provide that (i) the term thereof will  be
extended  to 40 years, (ii) ART will receive, in the event of any dividends paid
by Telecom  to its  stockholders, an  amount equal  to the  percentage share  of
Telecom  on the date that the ART stockholders would have received in the Merger
of such aggregate dividends, (iii) ART would have a right of co-sale, subject to
FCC approval,  in accordance  with such  percentage share  in the  event of  any
merger or sale of substantial assets by Telecom and (iv) in the event ART agrees
to  merge into another entity or to sell substantially all its assets to another
entity, Telecom shall, upon  the request of the  Company, use its best  efforts,
subject to FCC approval, to merge into such entity or sell substantially all its
assets  to such entity for aggregate consideration equal to the percentage share
of the  aggregate  consideration  to  be  paid  for  ART  and  Telecom  in  such
transaction.
 
                                       76
<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
    The   authorized  capital  stock  of   the  Company  currently  consists  of
100,000,000 shares of Common Stock, $0.001  par value, and 10,000,000 shares  of
Serial Preferred Stock, $0.001 par value (the "Preferred Stock").
 
COMMON STOCK
 
    As  of  June  28,  1996,  there  were  10,013,055  shares  of  Common  Stock
outstanding held of  record by  11 stockholders  (without giving  effect to  the
Merger  or  any exercise  of outstanding  warrants or  options). The  holders of
Common Stock are entitled to one vote per share on all matters to be voted on by
the  stockholders.  Subject  to  preferences  that  may  be  applicable  to  the
outstanding  share of Preferred Stock, the  holders of Common Stock are entitled
to receive ratably such dividends  as may be declared from  time to time by  the
Board  of Directors out of funds legally available therefor. In the event of the
liquidation, dissolution or  winding up of  the Company, the  holders of  Common
Stock  are entitled to  share ratably in  all assets remaining  after payment of
liabilities, subject  to  prior  liquidation  rights  of  Preferred  Stock  then
outstanding.  The  Common Stock  has no  preemptive  conversion rights  or other
subscription  rights.  There  are  no  redemption  or  sinking  fund  provisions
applicable to the Common Stock. All outstanding shares of Common Stock are fully
paid  and non-assessable, and the shares of  Common Stock to be outstanding upon
consummation of the Common Stock Offering will be fully paid and non-assessable.
 
PREFERRED STOCK
 
    As of June 28,  1996, there was  one share of ART  Series A Preferred  Stock
outstanding  held of record by Telecom. Upon  the completion of the Merger, such
Preferred Stock will automatically be surrendered. See "Certain Transactions  --
Merger." The Board of Directors will have the authority to issue Preferred Stock
in  one  or more  series  and to  fix  the rights,  preferences,  privileges and
restrictions granted to or imposed upon any wholly unissued shares of  Preferred
Stock  and  to  fix  the  number  of  shares  constituting  any  series  in  the
designations of  such  series,  without  any  further  vote  or  action  by  the
stockholders.  The Board of  Directors, without stockholder  approval, can issue
Preferred Stock with voting and  conversion rights which could adversely  affect
the voting power of the holders of Common Stock. The issuance of Preferred Stock
may  have the effect of delaying, deferring or preventing a change in control of
the Company. The Company does not presently intend to issue Preferred Stock.  In
addition, the terms of the Indenture will restrict the ability of the Company to
issue Preferred Stock. See "Description of Certain Indebtedness -- The Notes."
 
CHANGE IN CONTROL PROVISIONS
 
    Certain  provisions of the Company's Certificate of Incorporation and Bylaws
may have the effect  of preventing, discouraging or  delaying any change in  the
control of the Company any may maintain the incumbency of the Board of Directors
and  management. The authorization of Preferred  Stock makes it possible for the
Board of  Directors to  issue Preferred  Stock with  voting or  other rights  or
preferences  that could impede the success of  any attempt to effect a change in
control of the  Company. In  addition, on  the effectiveness  of the  Offerings,
certain provisions of the Certificate of Incorporation will create three classes
of directors serving for staggered three-year terms and prevent any amendment to
such  provisions without the  consent of holders  of at least  two-thirds of the
then outstanding shares of Common Stock. These provisions could also impede  the
success of any attempt to effect a change in control of the Company.
 
    The  Company is subject  to Section 203 of  the Delaware General Corporation
Law ("Section 203"). Section 203 prohibits a publicly-held Delaware  corporation
from engaging in a "business combination" with an "interested stockholder" for a
period  of three  years after the  date of  the transaction in  which the person
became an interested stockholder,  unless (i) prior to  such date, the board  of
directors  of the  corporation approves either  the business  combination or the
transaction  which   resulted  in   the  stockholder   becoming  an   interested
stockholder,  (ii)  upon  consummation  of  the  transaction  which  resulted in
 
                                       77
<PAGE>
the stockholder becoming an  interested stockholder, the interested  stockholder
owns at least 85% of the outstanding voting stock (excluding certain shares held
by  persons who are both  directors and officers of  the corporation and certain
employee stock plans), or (iii) on or after the consummation date, the  business
combination is approved by the board of directors and by the affirmative vote of
at  least 66  2/3% of  the outstanding  voting stock  that is  not owned  by the
interested stockholder. For  purposes of Section  203, a "business  combination"
includes,  among  other  things,  a  merger,  asset  sale  or  other transaction
resulting  in  a  financial  benefit  to  the  interested  stockholder,  and  an
"interested stockholder" is generally a person who, together with affiliates and
associates, owns (or within three years, owned) 15% or more of the corporation's
voting stock.
 
TRANSFER AGENT AND REGISTRAR
 
    The  Transfer Agent and Registrar for  the Common Stock is Continental Stock
Transfer & Trust Company.
 
LISTING
 
    The Common Stock  has been  approved for  quotation on  the Nasdaq  National
Market under the symbol "ARTT."
 
                                       78
<PAGE>
                        SHARES ELIGIBLE FOR FUTURE SALE
 
GENERAL
 
    Upon  consummation  of  the Common  Stock  Offering, the  Company  will have
outstanding 37,586,498  shares of  Common  Stock (assuming  no exercise  of  the
Underwriters'  over-allotment  option and  options  or warrants  after  June 28,
1996). Of these  shares, the  7,500,000 shares being  sold in  the Common  Stock
Offering  will be freely tradable without  restriction under the Securities Act,
unless purchased by "affiliates" of the Company.
 
    The  remaining  30,086,498   shares  of  Common   Stock  held  by   existing
stockholders  are "restricted" shares under  the Securities Act (the "Restricted
Shares"), all of which  are also subject to  certain lock-up agreements  between
certain  stockholders and  the Representatives  (as defined).  Beginning 90 days
after the date of this Prospectus,  10,013,055 shares will become available  for
immediate  sale to the public market subject  to certain volume and other resale
restrictions pursuant  to Rule  144  promulgated under  the Securities  Act,  as
described  below, unless such shares  are registered. See "Registration Rights."
Upon the closing of the CommcoCCC Acquisition, 16,500,000 shares will be  issued
for  the CommcoCCC Assets,  which shares will  become available for  sale in the
public market under Rule  144 two years  after the date  of consummation of  the
CommcoCCC  Acquisition. In addition,  under a proposal  currently pending before
the Securities and Exchange Commission, the date on which shares of Common Stock
become available for sale under Rule 144 may be significantly accelerated.
 
    As of June 28, 1996, an aggregate  of 4,044,868 shares of Common Stock  will
be  subject to  outstanding options and  warrants and an  aggregate of 1,007,268
shares are  reserved  for  future  issuance pursuant  to  the  Company's  Equity
Incentive  Plan and Directors  Plan (collectively, the "Plans").  As of June 28,
1996, 639,302 of such shares  were vested, and, 180  days following the date  of
this Prospectus, an additional 59,109 of such shares will be vested. The Company
intends  to file a Registration Statement on  Form S-8 to register the shares of
Common Stock to be issued and issuable pursuant to the Plans. Thereafter, shares
of Common Stock issued under the Plans will be available for sale in the  public
market  upon vesting of such shares, subject,  with respect to affiliates of the
Company, to certain volume limitations under Rule 144.
 
    In general, under Rule 144 as  currently in effect, beginning 90 days  after
the  Effective Date, a person  (or persons whose shares  are aggregated) who has
beneficially owned Restricted Shares for at least two years, will be entitled to
sell in any  three-month period  a number  of shares  that does  not exceed  the
greater  of (i)  1% of  the number  of shares  of Common  Stock then outstanding
(approximately 375,865  shares  immediately  after  the  Common  Stock  Offering
assuming  no exercise of  the Underwriters' over-allotment  option) and (ii) the
average weekly  trading volume  of  the Company's  Common  Stock in  the  Nasdaq
National Market during the four calendar weeks immediately preceding the date on
which  notice of the sale is filed  with the Securities and Exchange Commission.
Sales pursuant  to Rule  144 are  subject to  certain requirements  relating  to
manner  of sale, notice and availability of current public information about the
Company. A person (or persons whose shares are aggregated) who is not deemed  to
have been an affiliate of the Company at any time during the 90 days immediately
preceding the sale and who has beneficially owned Restricted Shares for at least
three  years is  entitled to  sell such shares  pursuant to  Rule 144(k) without
regard to the limitations and requirements described above.
 
    All holders  of  the Company's  Common  Stock, as  well  as all  holders  of
warrants  or options to purchase Common Stock, have agreed not to sell, offer to
sell, contract to sell or otherwise sell, dispose of, loan, pledge or grant  any
rights  with respect to any  shares of Common Stock,  any options or warrants to
purchase Common Stock, or any securities convertible or exchangeable for  Common
Stock,  owned directly by such holders or  with respect to which they have power
of disposition  for a  period of  180 days  after the  date of  this  Prospectus
without   the  prior  written  consent   of  Montgomery  Securities.  Montgomery
Securities may, in its sole discretion  and at any time without notice,  release
all  or any portion  of the securities  subject to these  lock-up agreements. In
addition, the Company has agreed not to sell, offer to sell, contract to sell or
otherwise sell or dispose of any shares of Common Stock or any rights to acquire
 
                                       79
<PAGE>
Common Stock, other than  pursuant to the Restated  Equity Incentive Plan,  upon
exercise  of  outstanding  warrants and  options  or pursuant  to  the CommcoCCC
Agreement for a period of 180 days after the date of this Prospectus without the
prior consent of Montgomery Securities. See "Underwriting."
 
    Prior to the Common Stock Offering, there has been no public market for  the
Common  Stock and there can be no assurance that a significant public market for
the Common Stock will develop or  be sustained after the Common Stock  Offering.
Sales  of  substantial  amounts  of  Common Stock  in  the  public  market could
adversely affect  the market  price of  the Common  Stock and  could impair  the
Company's  future  ability  to raise  capital  through  the sale  of  its equity
securities.
 
REGISTRATION RIGHTS
 
    Under the terms of  an amended and  restated registration rights  agreement,
dated  as  of  July     , 1996,  among  the Company,  Telecom,  their respective
stockholders and  the holders  of the  Bridge Warrants,  Indemnity Warrants  and
CommcoCCC  Warrants (as amended, the "Registration Rights Agreement"), following
the consummation of  the Offerings,  such stockholders  and the  holders of  the
Bridge  Warrants, Indemnity Warrants and CommcoCCC Warrants, who are the holders
of an aggregate 31,561,498 shares of Common Stock on a fully-diluted basis  (the
"Registrable  Securities"), will be  entitled to certain  rights with respect to
the registration of such shares under the Securities Act. Under the Registration
Rights Agreement, if  the Company  proposes to  register any  of its  securities
under  the Securities Act,  either for its  own account or  the account of other
security holders, the holders of  Registrable Securities are entitled to  notice
of such registration and are entitled to include their Registrable Securities in
any   such  registration;  provided,  however,  among  other  things,  that  the
underwriters have the right, subject to certain limitations, to limit the number
of such shares included therein.
 
    Upon the consummation of the CommcoCCC Acquisition, the 16,500,000 shares to
be issued  in connection  therewith will  also be  subject to  the  Registration
Rights Agreement.
 
                                       80
<PAGE>
                      DESCRIPTION OF CERTAIN INDEBTEDNESS
 
THE NOTES
 
    Concurrently  with  the  Common  Stock Offering,  the  Company  is offering,
pursuant to  a separate  prospectus,         Units,  each consisting  of  $1,000
principal  amount at maturity of the Notes and   Warrants to purchase     shares
of Common  Stock  of the  Company,  sufficient  to generate  gross  proceeds  of
$175,000,000  in the Unit Offering. The  Warrants, when exercised, would entitle
the holders thereof to  purchase shares of Common  Stock representing 5% of  the
Common  Stock of the Company on a fully diluted basis after giving effect to the
Offerings.  The  Common  Stock  Offering  is  conditioned  upon  the  successful
consummation  of the Unit  Offering. The yield-to-maturity of  the Notes will be
   % (computed on a semiannual bond basis) calculated from               , 1996.
Cash interest will not  accrue on the Notes  prior to                   ,  2001,
however  the  principal  amount of  the  Notes  will accrete  from  the original
principal amount at issuance at a rate of    % per annum until                 ,
2001. Thereafter, cash interest will accrue at a rate of    % per annum, payable
semiannually  in arrears.  The Notes  will be  redeemable at  the option  of the
Company on or after               , 2001, and the holders of the Notes will have
the right to  require the Company  to repurchase  all or part  of such  holders'
Notes  in the event of certain events involving a change of control with respect
to, or certain sales of assets by, the Company and its subsidiaries.
 
    Subject to certain exceptions and qualifications, the Indenture will,  among
other  things, restrict the ability  of the Company and  its subsidiaries to (i)
incur indebtedness, (ii) pay dividends and make distributions in respect of  the
Company's  capital stock or make certain other restricted payments, (iii) create
certain liens, (iv) enter into  certain transactions with affiliates or  related
persons,  (v) conduct businesses other than  those permitted by the Indenture or
(vi) sell certain assets. In addition,  the Indenture will limit the ability  of
the  Company  to consolidate,  merge or  sell  all or  substantially all  of its
assets.
 
EMI NOTE
 
    In connection with  the acquisition by  Telecom of the  EMI Assets,  Telecom
issued   to   EMI   a   $1.5  million   principal   amount   non-negotiable  and
non-transferable, unsecured promissory  note (the "EMI  Note"). Interest on  the
EMI  Note accrues  at a rate  equal to  the prime rate  plus 2%.  The Company is
obligated to make quarterly principal repayments of $187,500, commencing January
1, 1997. The EMI Note matures on November 14, 1998. See "Business --  Agreements
Relating to Licenses and Acquisitions -- EMI Acquisition."
 
EQUIPMENT FINANCING
 
    On April 1, 1996, CRA, Inc. ("CRA") entered into secured Equipment Financing
with  the Company  for the  purchase from  P-Com of  38 GHz  radio equipment. To
evidence its obligations under  the Equipment Financing,  the Company issued  in
favor  of  CRA  a $2,445,000  Equipment  Note,  payable in  twenty  four monthly
installments of $92,694  with a  final payment equal  to $642,305  due April  1,
1998.
 
BRIDGE FINANCING
 
    On March 8, 1996, the Company issued $5.0 million principal amount of Bridge
Notes  in connection  with the  Bridge Financing.  See "Certain  Transactions --
Bridge Financing." The Bridge Notes are subordinated in right of payment to  the
EMI  Note  and will  be repaid  with proceeds  from the  Offerings. See  "Use of
Proceeds."
 
COMMCOCCC FINANCING
 
    On June  27 and  July     ,  1996, the  Company  issued to  stockholders  of
CommcoCCC,  in connection  with the  CommcoCCC Agreement  $3.0 million principal
amount of subordinated bridge notes (the "CommcoCCC Notes"), bearing interest at
the prime rate and payable  90 days after the  date of the CommcoCCC  Agreement.
The  CommcoCCC Notes  are secured by  a security  interest in all  of the assets
 
                                       81
<PAGE>
of the  Company, including  a pledge  of  the Company's  stock in  Telecom.  See
"Certain  Transactions  --  CommcoCCC  Acquisition."  The  CommcoCCC  Notes  are
subordinated in right of  payment to the  EMI and the Bridge  Notes and will  be
repaid with proceeds from the Offerings. See "Use of Proceeds."
 
CREDIT FACILITY
 
    Canadian  Imperial  Bank of  Commerce ("CIBC")  has  provided the  Company a
Summary of Terms and Conditions on which it and other banks might extend  credit
pursuant  to  a  Senior  Secured  Revolving  Credit  Facility  converting  to an
Amortizing Term Loan (the "Credit Facility").  Under the Credit Facility, up  to
$100,000,000   in  revolving  loans  would  be  available  based  on  incurrence
provisions which will be determined but would include measures of total debt  to
operating  cash flow, numbers of  links, numbers of links  per pop or market and
amount of  revenue  per  link.  The  proceeds  could  be  used  to  finance  the
construction   of  the   Company's  systems,   capital  expenditures,  permitted
acquisitions, operating losses and working capital. The Credit Facility would be
secured by all of  the assets of  the Company and  its subsidiaries including  a
pledge  of stock of  subsidiaries, and would be  guaranteed by all subsidiaries,
excluding unrestricted subsidiaries  to be determined.  The interest rate  would
initially  be at 2.50% over the bank's base  rate or 3.50% over LIBOR subject to
reduction. Mandatory prepayment will be required with respect to a percentage of
excess cash flow and proceeds of equity offerings. The revolving credit facility
will convert to a term loan after a period, for a term and with an  amortization
to be determined.
 
    In  addition, the  Credit Facility  will include  financial covenants  to be
determined relating to ratios of total  debt to annualized operating cash  flow,
operating  cash  flow to  cash interest  expense, cash  flow available  for debt
service to pro forma fixed charges and total debt per total links as well as  to
minimum  revenues, operating  cash flow (or  maximum loss),  minimum revenue per
link and minimum number of links. The Credit Facility will prohibit the  Company
from   making  restricted   payments  and  acquisitions   other  than  permitted
acquisitions, from  incurring indebtedness  except with  certain limitations  or
liens,  or  merging and  will  limit investments  and  assets sales.  The Credit
Facility will contain a provision relating to change of control of the  Company.
The Credit Facility will also contain customary events of default, including but
not  limited  to nonpayment  of principal  or interest  when due,  violations of
covenants, falsity of  representations and warranties  in any material  respect,
actual  or asserted invalidity of security  documents and security interests and
the occurrence of certain events with  respect to the Company or any  subsidiary
including  cross-default and cross-acceleration, bankruptcy, material judgments,
ERISA violations,  change in  control and  loss or  material impairment  of  FCC
licenses.
 
    The Company will be required to pay a structuring fee which has not yet been
determined,  a facility fee of  3.5% payable at closing  and a commitment fee of
0.5% per annum on the  unused portion of the  facility. Execution of the  Credit
Facility  will be dependent upon, among other things, satisfactory due diligence
review by the banks, consummation of the Offerings on terms satisfactory to  the
banks  and  negotiation and  execution  of mutually  satisfactory documentation.
There is no assurance that the Credit Facility will be executed, what the  terms
of the Credit Facility will be, or if executed, that the Company will be able to
borrow under the Credit Facility.
 
                                       82
<PAGE>
                                  UNDERWRITING
 
    The underwriters named below (the "Underwriters"), represented by Montgomery
Securities, Merrill Lynch, Pierce, Fenner & Smith Incorporated ("Merrill Lynch")
and    Deutsche   Morgan   Grenfell/C.   J.   Lawrence   Inc.   (together,   the
"Representatives"), have severally agreed, subject  to the terms and  conditions
set forth in the Underwriting Agreement, to purchase from the Company the number
of shares of Common Stock indicated below opposite their respective names at the
initial  public offering price  less the underwriting discount  set forth on the
cover page  of this  Prospectus. The  Underwriting Agreement  provides that  the
obligations  of the  Underwriters are  subject to  certain terms  and conditions
precedent and  that the  Underwriters  are committed  to  purchase all  of  such
shares, if any are purchased.
 
<TABLE>
<CAPTION>
                                                                   NUMBER OF
                  UNDERWRITERS                                      SHARES
                                                                   ---------
 
<S>                                                                <C>
Montgomery Securities............................................
Merrill Lynch, Pierce, Fenner & Smith
           Incorporated..........................................
Deutsche Morgan Grenfell/C. J. Lawrence Inc......................
                                                                   ---------
              Total..............................................  7,500,000
                                                                   ---------
                                                                   ---------
</TABLE>
 
    The Representatives have advised the Company that the Underwriters initially
propose  to offer the Common Stock  to the public on the  terms set forth on the
cover page of this Prospectus. The Underwriters may allow to selected dealers  a
concession  of not more than $        per share, and the Underwriters may allow,
and any such dealers may  reallow, a concession of not  more than $          per
share to certain other dealers. After the initial public offering, the price and
concessions  and reallowances to dealers may  be changed by the Representatives.
The  Common  Stock  is  offered  subject  to  receipt  and  acceptance  by   the
Underwriters  and to  certain other  conditions, including  the right  to reject
orders in whole or in part.
 
    The Company has granted  an option to  the Underwriters, exercisable  during
the 30-day period after the date of this Prospectus, to purchase up to a maximum
of 1,125,000 additional shares of Common Stock to cover over-allotments, if any,
at  the same price per share as the  initial 7,500,000 shares to be purchased by
the Underwriters. To the extent the  Underwriters exercise this option, each  of
the  Underwriters will be committed, subject  to certain conditions, to purchase
such additional shares in approximately the same proportion as set forth in  the
above table.
 
    The Underwriting Agreement contains certain covenants of indemnity among the
Underwriters  and  the  Company  against  certain  civil  liabilities, including
liability under the Securities Act of 1933, as amended (the "Securities Act").
 
    Concurrently with  the  Common  Stock Offering,  the  Company  is  offering,
pursuant  to a separate prospectus,       Units in the Unit Offering. Montgomery
Securities and Merrill Lynch are acting as underwriters in the Unit Offering and
will receive customary compensation in connection therewith. In connection  with
the  CommcoCCC  Acquisition,  Montgomery  Securities has  been  retained  by the
Company as  its financial  advisor  for which  it will  receive  fees of  up  to
approximately  $2.7 million  and the  reimbursement of  reasonable out-of-pocket
expenses incurred in connection therewith.
 
    All holders of the Company's Common Stock prior to this offering, as well as
all holders of options, warrants or other rights to purchase Common Stock,  have
agreed  not to sell, offer to sell,  contract to sell or otherwise sell, dispose
of, loan, pledge or grant any rights with respect to any shares of Common Stock,
any options or warrants to purchase Common Stock, or any securities  convertible
or exchangeable for Common Stock, owned directly by such holders or with respect
to  which they have power of disposition for a period of 180 days after the date
of this Prospectus without the  prior written consent of Montgomery  Securities.
Montgomery  Securities  may, in  its  sole discretion  and  at any  time without
notice, release all or  any portion of the  securities subject to these  lock-up
agreements. In addition, the
 
                                       83
<PAGE>
Company  has agreed not  to sell, offer  to sell, contract  to sell or otherwise
sell or dispose of any  shares of Common Stock or  any rights to acquire  Common
Stock,  other  than pursuant  to  the Equity  Incentive  Plan, upon  exercise of
outstanding options and warrants or pursuant  to the CommcoCCC Agreement, for  a
period  of  180 days  after  the Effective  Date  without the  prior  consent of
Montgomery Securities.
 
    The Representatives have advised  the Company that  the Underwriters do  not
intend  to confirm sales to any  accounts over which they exercise discretionary
authority in  excess of  5% of  the number  of shares  of Common  Stock  offered
hereby.
 
    Prior  to the Common Stock Offering, there has been no public market for the
Common Stock of  the Company.  Consequently, the initial  public offering  price
will   be   determined  through   negotiations   among  the   Company   and  the
Representatives. Among the factors to be considered in such negotiations will be
the history of,  and prospects for,  the Company  and the industry  in which  it
competes,  an assessment of  the Company's management, the  present state of the
Company's development, the  prospects for  future earnings of  the Company,  the
prevailing  market conditions at  the time of the  Common Stock Offering, market
valuations of publicly traded companies that the Company and the Representatives
believe to be comparable to the Company, and other factors deemed relevant.  See
"Risk Factors -- Absence of Public Market; Possible Volatility of Stock Price."
 
                                 LEGAL MATTERS
 
    The  validity of the issuance of shares  of Common Stock offered hereby will
be passed upon for the Company by Hahn & Hessen LLP, New York, New York. Certain
legal matters in connection with the  Common Stock Offering will be passed  upon
for  the Underwriters by  Latham & Watkins,  Washington, D.C. As  of the date of
this Prospectus, a member of Hahn & Hessen LLP owns $25,000 of the Bridge  Notes
and  5,500 Bridge Warrants and beneficially  owns 13,627 shares of Common Stock.
Latham &  Watkins,  Washington,  D.C., currently  represents  the  Company  with
respect to certain FCC matters.
 
                                    EXPERTS
 
    The   historical  financial   statements  of   Advanced  Radio  Technologies
Corporation as of December 31, 1995 and 1994, for the years then ended, and  for
the  period from August 23, 1993 (date of inception) to December 31, 1993 and of
Advanced Radio Telecom Corp.  as of December  31, 1995 and  for the period  from
March  28,  1995 (date  of  inception) to  December  31, 1995  included  in this
Prospectus, have been included herein in reliance on the reports, each of  which
includes  an explanatory paragraph regarding  the substantial doubt which exists
about the respective entity's ability to continue as a going concern, of Coopers
& Lybrand L.L.P., independent accountants, given  on the authority of that  firm
as experts in accounting and auditing.
 
                             AVAILABLE INFORMATION
 
    The  Company has filed with the  Commission a registration statement on Form
S-1 (together with all amendments, exhibits, schedules and supplements  thereto,
the  "Registration  Statement") under  the Securities  Act  with respect  to the
securities  offered  hereby.  This  Prospectus,  which  forms  a  part  of   the
Registration Statement, does not contain all of the information set forth in the
Registration  Statement, certain parts of which  have been omitted in accordance
with the rules and regulations of  the Commission. For further information  with
respect  to the Company and the securities  offered hereby, reference is made to
the Registration Statement and  to the schedules  and exhibits filed  therewith.
Statements  contained in this Prospectus as to the contents of certain documents
are not necessarily complete,  and, in each instance,  reference is made to  the
copy  of the  document filed  as an exhibit  to the  Registration Statement. The
Registration Statement, including  the exhibits  and schedules  thereto, can  be
inspected  and  copied  at the  public  reference facilities  maintained  by the
Commission at Room 1024,  Judiciary Plaza, 450  Fifth Street, N.W.,  Washington,
D.C.    20549,    and   at    the    following   regional    offices    of   the
 
                                       84
<PAGE>
Commission: New York Regional Office, 7  World Trade Center, New York, New  York
10007;  and Chicago Regional Office, Suite 1400, Northwestern Atrium Center, 500
West Madison Street, Chicago, Illinois 60661.  Copies of such material can  also
be obtained from the Commission at prescribed rates through its Public Reference
Section at 450 Fifth Street, N.W., Washington, D.C. 20549.
 
    Immediately  following the  Offerings, the  Company will  be subject  to the
informational requirements of the  Securities Exchange Act  of 1934, as  amended
(the  "Exchange  Act"), and  in accordance  therewith will  be required  to file
reports and other information with the Commission. Such reports may be inspected
and copied at the public reference  facilities at the addresses set forth  above
and  at the Public Reference Section of  the Commission at the address set forth
above.
 
                                       85
<PAGE>
                                    GLOSSARY
 
    ACCESS  CHARGES  -- The  fees paid  by  long distance  carriers to  LECs for
originating and terminating long distance calls on their local networks.
 
    BANDWIDTH -- At any  given level of compression,  the amount of  information
transportable  over  a link  per unit  of time.  A DS-1,  or Digital  Service 1,
circuit will carry up to 1,544,000 bits (or 1.544 megabits) per second.
 
    BPS -- Bits per second. A bit  is the basic unit of information,  yes-or-no,
on-or-off,  1-or-0 in the binary  (base 2) system which  is the basis of digital
computing. In contrast, a voice telephone  signal over a copper wire is  analog,
reflecting a continuous range of vocal tone (frequency) and volume (amplitude).
 
    BROADBAND  -- Data streams of at  least 1.544 megabits per second. Broadband
communications systems can transmit large quantities of voice, data and video by
way of digital or  analog signals. Examples  of broadband communication  systems
include  DS-3 systems, which can  transmit 672 simultaneous voice conversations,
or a broadcast television  station signal that  transmits high resolution  audio
and  video signals into the home. Broadband connectivity is an essential element
for interactive multimedia applications.
 
    BTA (BASIC  TRADING AREA)  -- An  area erected  by Rand  McNally based  upon
various  business  demographics to  establish a  contiguous urban  area, without
reference to political or similar boundaries.  The FCC has proposed to use  BTAs
to auction 38 GHz authorizations.
 
    CAP  (COMPETITIVE ACCESS PROVIDER) -- A  company that provides its customers
with an alternative  to the  local telephone  company for  local and  interstate
transport of private line, special access and switched access telecommunications
services.  CAPs  are  also referred  to  in  the industry  as  competitive local
exchange  carriers   (CLECs),  alternative   local  telecommunications   service
providers  (ALTs)  and  metropolitan  area  network  providers  (MANs)  and were
formerly referred to as alternative access vendors (AAVs).
 
    CELLULAR -- Characterized by "cells," the area accessible by  transceiver(s)
typically  located at one site. A cellular  phone connects to the transceiver in
its current cell, then the connection is  handed-off as and when the user  moves
to any other cell.
 
    COMPRESSION  -- Any process that transforms a  signal to a more compact form
(fewer bits) for easier transfer, and then restores the signal after transfer.
 
    CMRS -- Commercial mobile radio services.
 
    COPPER WIRE -- A  shorthand reference to  traditional telephone lines  using
electric current to carry signals over copper wire.
 
    DIGITAL  --  A method  of storing,  processing and  transmitting information
through the use  of distinct  electronic or  optical pulses  that represent  the
binary  code digits  0 and  1. Digital  transmission and  switching technologies
employ a sequence  of these  pulses to represent  infomation as  opposed to  the
continously   variable  analog   signal.  Digital   transmission  and  switching
technologies offer a  threefold improvement  in speed and  capacity over  analog
techniques,  allowing  much more  efficient  and cost-effective  transmission of
voice, video, and data.
 
    DIALING PARITY -- Dialing  parity is one of  the changes, intended to  level
the  competitive playing field, that are  required by the Telecommunication Act.
Dialing parity when implemented will enable customers to have dial only 1+ or 0+
service no matter which local or long distance carrier they choose.
 
    DS-0, DS-1,  DS-3 --  Standard  telecommunications industry  digital  signal
formats,  which are distinguishable by bit rate  (the number of binary digits (0
and 1) transmitted per second). DS-0 service  has a bit rate of 64 kilobits  per
second.  DS-1  service has  a bit  rate of  1.544 megabits  per second  and DS-3
service has a bit rate of 45 megabits per second.
 
                                       86
<PAGE>
    ESMR (ENHANCED SPECIALIZED MOBILE RADIO)  -- A recent mobile radio  services
category  involving technical and  service enhancements to  traditional "push to
talk" dispatch services.
 
    FCC -- Federal Communications Commission.
 
    FIBER OPTICS -- Fiber optic cable largely immune to electrical  interference
and  environmental factors that affect copper wiring and satellite transmission.
Fiber optic technology involves sending laser light pulses across glass  strands
in order to transmit digital information.
 
    GHZ  (GIGAHERTZ) -- Billions of  cycles or hertz per  second. A hertz is one
full cycle (an s-shaped sine curve with one peak and one valley).
 
    INTER-LATA LONG DISTANCE --  Inter-LATA long distance  calls are calls  that
pass  from one LATA to another. Typically, these calls are simply referred to as
"long distance" calls although intra-LATA calls can also be long distance calls.
 
    INTERNET --  An array  of  interconnected networks  using  a common  set  of
protocols  defining the information coding  and processing requirements that can
communicate across hardware  platforms and  over many  links now  operated by  a
consortium of telecommunications service providers and others.
 
    ISP -- Internet service provider.
 
    ITC (INDEPENDENT TELEPHONE COMPANY) -- A telephone company not associated or
formerly associated with the Bell Telephone system.
 
    IXC  (INTER-EXCHANGE  CARRIERS)  --  Usually referred  to  as  long distance
providers. There are many facilities-based IXCs, including AT&T, MCI,  WorldCom,
Sprint and Frontier.
 
    KILOBIT  --  One  thousand  bits  of  information.  The information-carrying
capacity (i.e.,  bandwidth  of  a  circuit may  be  measured  in  "kilobits  per
second").
 
    KBPS -- Kilobits per second.
 
    LANS  (LOCAL  AREA NETWORKS)  -- The  interconnection  of computers  for the
purpose of sharing files,  programs and various devices  such as work  stations,
printers  and high-speed  modems. LANs may  include dedicated  computers or file
servers that provide  a centralized source  of shared files  and programs.  Most
office  computer networks use a  LAN to share files,  printers, modems and other
items. Where computers are separated  by greater distances, a Metropolitan  Area
Net (MAN) or other Wide Area Net (WAN) may be used.
 
    LAST   MILE   --  A   shorthand  reference   to  the   last  section   of  a
telecommunications path  to the  ultimate end  user which  may be  less than  or
greater than a mile.
 
    LATAS (LOCAL ACCESS AND TRANSPORT AREAS) -- The geographically defined areas
in  which RBOCs were authorized  by the MFJ to  provide local exchange services.
These LATAs roughly reflect  the population density  of their respective  states
(California has 11 LATAs while Wyoming has only one). There are 164 LATAs in the
United States. LATAs have one or more area codes and may cross state lines.
 
    LEC (LOCAL EXCHANGE CARRIER) -- A company providing local exchange services.
The  traditional  local  telephone  companies  (also  known  as  incumbent local
exchange carriers), such as the RBOCs, which until recently were monopolies.
 
    LINE OF SIGHT -- An unobstructed view between two transceivers comprising  a
link.
 
    LINK -- A transmission link between two transceivers.
 
    MAN -- Metropolitan Area Network.
 
    MARKET  -- The  potential and  actual customers  within the  boundaries of a
wireless  license.  For  simplicity,  the  definition  of  the  market  in  this
Prospectus  has been  based on Basic  Trading Areas, though  each application as
granted defines its own actual boundaries.
 
                                       87
<PAGE>
    MEGABIT  --  One  million  bits  of  information.  The  information-carrying
capacity  (i.e.,  bandwidth)  of a  circuit  may  be measured  in  "megabits per
second."
 
    MFJ (MODIFIED  FINAL JUDGMENT)  -- The  MFJ was  an agreement  made in  1982
between  AT&T and the Department of Justice  which forced the breakup of the old
Bell System. This judgment, also known  as the Divestiture of AT&T,  established
seven  separate RBOCs and enhanced the establishment of two distinct segments of
telecommunications service: local  and long distance.  This laid the  groundwork
for  intense  competition  in  the  long distance  industry.  The  MFJ  has been
superseded by the Telecommunications Act of 1996.
 
    MICROWAVE -- A  portion of the  radio spectrum having  radio waves that  are
physically  very short,  ranging in length  between about  30 cm and  0.3 cm and
generally used to refer to frequencies above 2 GHz.
 
    MILLIMETRIC MICROWAVE OR MILLIMETER WAVE -- Those portions of the  microwave
radio  spectrum having wave lengths measured in millimeter lengths and generally
used to refer to frequencies above 20 GHz.  A shorter wave length means a higher
frequency and vice versa.
 
    MHZ (MEGAHERTZ) -- Millions of cycles or hertz per second.
 
    MBPS -- Megabits per second.
 
    NARROWBAND -- Data streams less than 64 kilobits per second.
 
    NPRM (NOTICE  OF  PROPOSED  RULEMAKING)  -- A  term  used  in  governmental,
principally FCC, rulemaking proceedings to refer to initiation of the process.
 
    NUMBER  PORTABILITY -- The ability  of an end user  to change local exchange
carriers while retaining the same  telephone number. If number portability  does
not  exist, customers will have  to change phone numbers  when they change local
exchange carriers.
 
    OFF-NET CUSTOMERS -- A customer that is not physically connected to a  CAP's
network  but who is  accessed through interconnection  with a LEC  network or an
alternative provider such as a 30 GHz licensee.
 
    ON-NET CUSTOMERS  -- A  customer that  is physically  connected to  a  CAP's
network.
 
    PCS  (PERSONAL COMMUNICATIONS SERVICE) -- Cellular-like services provided at
the 2 GHz band  of the radio spectrum  rather than 800 MHz.  A type of  wireless
telephone system that uses light, inexpensive handheld sets and communicates via
low power antennas.
 
    PIPE  -- A generic  term for telecommunications  transmission media, whether
wired or wireless, used to carry signals between the signal generating unit  and
the user.
 
    POPS  (POINTS  OF  PRESENCE)  -- Locations  where  a  carrier  has installed
transmission equipment in a service area that  serves as, or relays calls to,  a
network switching center of that carrier.
 
    PSTN  (PUBLIC SWITCHED  TELECOMMUNICATIONS NETWORK)  -- The  traditional LEC
networks that switch calls between different customers.
 
    RBOCS (REGIONAL BELL  OPERATING COMPANIES) --  The holding companies  owning
LEC affiliates of the old AT&T or Bell system.
 
    REPEATER  -- An intermediate transceiver  between two transceivers connected
to end  users and  established to  circumvent  obstacles in  the line  of  sight
between communication ports, such as buildings in urban areas and hills in rural
areas.
 
    RESELLERS  -- Companies which purchase telecommunications services wholesale
from underlying carriers and resell them to end users at retail rates.
 
    ROOF RIGHTS --  The legal right  to locate, maintain  and operate  equipment
(most  commonly transceivers)  on the roofs  of buildings, on  special towers or
even on utility poles or pylons.
 
                                       88
<PAGE>
    WIDEBAND -- Data streams between 64 kilobits and 1.544 megabits per second.
 
    10-13 BIT ERROR RATE -- The measurement of a transmission path's ability  to
pass  data in an  uncorrupted format. Bit  error rate ("BER")  is defined as the
number of  erroneous bits  ("errors"), divided  by  the number  of bits  over  a
stipulated  period of time.  In the example of  a BER of 10-13,  a BER tester (a
test and measurement  instrument), placed  in line to  measure the  transmission
path  (in real time)  would have to  measure, and analyze,  ten trillion bits of
data before it detected one bit of erroneous data.
 
                                       89
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                                                              PAGE
                                                                                                            ---------
<S>                                                                                                         <C>
Advanced Radio Technologies Corporation
  Unaudited Pro Forma:
    Unaudited Pro Forma Condensed Balance Sheets as of December 31, 1995 and March 31, 1996...............     F-3
    Unaudited Pro Forma Condensed Balance Sheets -- Supplementary Combining Balance Sheet Data as of
     December 31, 1995 and March 31, 1996.................................................................     F-4
    Unaudited Pro Forma Condensed Statement of Operations for the three months ended March 31, 1996 and
     for the year ended December 31, 1995.................................................................     F-5
    Notes to Unaudited Pro Forma Condensed Financial Statements...........................................     F-6
  Historical:
    Report of Independent Accountants.....................................................................     F-8
    Balance Sheets as of December 31, 1995 and 1994.......................................................     F-9
    Statements of Operations for the years ended December 31, 1995 and 1994, for the period from August
     23, 1993 (date of inception) to December 31, 1993 and cumulative for the period from August 23, 1993
     (date of inception) to December 31, 1995.............................................................    F-10
    Statements of Stockholders' Equity (Deficit) for the years ended December 31, 1995 and 1994, for the
     period from August 23, 1993 (date of inception) to December 31, 1993 and cumulative for the period
     from August 23, 1993 (date of inception) to December 31, 1995........................................    F-11
    Statements of Cash Flows for the years ended December 31, 1995 and 1994, for the period from August
     23, 1993 (date of inception) to December 31, 1993 and cumulative for the period from August 23, 1993
     (date of inception) to December 31, 1995.............................................................    F-12
    Notes to Financial Statements.........................................................................    F-13
    Unaudited Interim Condensed Balance Sheets as of March 31, 1996 and 1995..............................    F-24
    Unaudited Interim Condensed Statements of Operations for the three months ended March 31, 1996 and
     1995.................................................................................................    F-25
    Unaudited Interim Condensed Statements of Cash Flows for the three months ended March 31, 1996 and
     1995.................................................................................................    F-26
    Notes to Unaudited Interim Condensed Financial Statements.............................................    F-27
 
Advanced Radio Telecom Corp.
 
  Historical:
    Report of Independent Accountants.....................................................................    F-30
    Balance Sheet as of December 31, 1995.................................................................    F-31
    Statement of Operations for the period from March 28, 1995 (date of inception) to December 31, 1995...    F-32
    Statement of Stockholders' Deficit for the period from March 28, 1995 (date of inception) to December
     31, 1995.............................................................................................    F-33
    Statement of Cash Flows for the period from March 28, 1995 (date of inception) to December 31, 1995...    F-34
    Notes to Financial Statements.........................................................................    F-35
    Unaudited Interim Condensed Balance Sheet as of March 31, 1996........................................    F-47
    Unaudited Interim Condensed Statement of Operations for the three months ended March 31, 1996.........    F-48
    Unaudited Interim Condensed Statement of Stockholders' Equity (Deficit) for the three months ended
     March 31, 1996.......................................................................................    F-49
    Unaudited Interim Condensed Statement of Cash Flows for the three months ended March 31, 1996.........    F-50
    Notes to Unaudited Interim Condensed Financial Statements.............................................    F-51
</TABLE>
 
                                      F-1
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
               UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS
 
    The  following  unaudited  pro  forma  condensed  financial  statements  are
presented as if all of the following transactions had occurred: (i) the March 8,
1996 issuance of the Bridge Notes in connection with the Bridge Financing;  (ii)
the  receipt of $2,220,000 in  cash proceeds from the  issuance of the Equipment
Note and Indemnity Warrants  in connection with  the Equipment Financing,  after
deducting  related expenses of $225,000; (iii) the receipt of $3,000,000 in cash
proceeds from the issuance of the CommcoCCC Notes and the CommcoCCC Warrants  in
connection  with  the  CommcoCCC Financing;  (iv)  the Conversion;  and  (v) the
Merger, including the issuance of ART  Common Stock to Telecom stockholders  and
the cancellation of all outstanding Telecom common stock.
 
    The following unaudited pro forma as adjusted condensed financial statements
reflect  further adjustments assuming  (i) the sale by  the Company of 7,500,000
shares of Common Stock offered in the Common Stock Offering based on an  assumed
initial  public offering price of  $9.00 per share and  the Units offered in the
Unit Offering  assuming $175,000,000  in  gross proceeds,  in each  case,  after
deducting  the estimated underwriting  discount and offering  expenses; (ii) the
receipt and application of the net proceeds therefrom to repay the Bridge  Notes
and  the CommcoCCC Notes and  to acquire the 50%  ownership interest of ART West
held by Extended for $6.0 million in cash and the DCT Assets for $3.6 million in
cash; and  (iii) the  consummation of  the  acquisition by  the Company  of  the
CommcoCCC Assets in exchange for 16,500,000 shares of Common Stock at an assumed
value of $9.00 per share.
 
    All  such  transactions are  reflected as  if  they had  occurred as  of the
beginning of  the  respective periods  for  the unaudited  pro  forma  condensed
statements  of  operations and  at  the respective  balance  sheet date  for the
unaudited pro forma condensed balance sheet.
 
    These unaudited pro forma condensed  financial statements were derived  from
and  should  be  read in  conjunction  with  the audited  and  unaudited interim
condensed financial statements of ART and Telecom and the related notes thereto,
included elsewhere herein. In management's opinion, all adjustments necessary to
reflect the foregoing and related transactions have been made.
 
    The unaudited pro forma condensed  financial statements are not  necessarily
indicative  of what the actual financial position or results of operations would
have been assuming that the  transactions described in the preceding  paragraphs
had occurred on the dates indicated, nor does it purport to represent the future
financial position or results of operations of the Company.
 
                                      F-2
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                  UNAUDITED PRO FORMA CONDENSED BALANCE SHEETS
 
                                     ASSETS
<TABLE>
<CAPTION>
                         AS OF
                      DECEMBER 31,  AS OF MARCH
                          1995        31, 1996
                      ------------  ------------
                       HISTORICAL    HISTORICAL
                      COMBINED (A)  COMBINED (A)
                      ------------  ------------
<S>                   <C>           <C>
Current assets:
  Cash and cash
   equivalents......  $ 633,654     $ 3,024,161
  Other current
   assets...........     52,325          61,226
                      ------------  ------------
    Total current
     assets.........    685,979       3,085,387
Property and
 equipment, net.....  3,581,561       6,380,895
Equity
 investments........    285,000         285,000
FCC licenses........  4,235,734       4,235,734
Deferred financing
 costs..............    778,897         681,692
Equipment and other
 deposits...........    284,012         344,417
Other assets........     25,376          23,212
                      ------------  ------------
                      $9,876,559    $15,036,337
                      ------------  ------------
                      ------------  ------------
 
      LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Accounts payable
   and accrued
   liabilities......  $3,694,489    $ 4,213,517
  CommcoCCC Notes...                    --
                      ------------  ------------
    Total current
     liabilities....  3,694,489       4,213,517
Convertible notes
 payable............  4,950,000
Note payable to
 EMI................  1,500,000       1,500,000
Bridge notes
 payable............     --           3,983,082
Equipment financing
 note payable.......     --             --
Senior discount
 notes..............     --             --
Deferred tax
 liability..........     --             --
                      ------------  ------------
    Total
     liabilities....  10,144,489      9,696,599
                      ------------  ------------
Redeemable Preferred
 Stock..............     44,930         --
                      ------------  ------------
Stockholders'
 equity:
  Preferred stock,
   par..............        488             921
  Common stock,
   par..............     25,304          28,127
  Additional paid-in
   capital..........  3,031,405      19,375,335
  Accumulated
   deficit..........  (3,370,057  ) (14,064,645)
                      ------------  ------------
    Total
     stockholders'
     equity.........   (312,860   )   5,339,738
                      ------------  ------------
                      $9,876,559    $15,036,337
                      ------------  ------------
                      ------------  ------------
 
<CAPTION>
 
                         PRO FORMA                      OFFERING       PRO FORMA
                      ADJUSTMENTS (B)    PRO FORMA    ADJUSTMENTS (C) AS ADJUSTED
                      ---------------   ------------  -------------   -----------
<S>                   <C>               <C>           <C>             <C>
Current assets:
  Cash and cash
   equivalents......    $3,000,000(2)
                        $2,220,000(3)   $  8,244,161  62,35$7,474(1)
                                                      168,667,526(2)
                                                      (8,000,000)(3)
                                                      (6,000,000)(5)
                                                      (3,600,000)(6)
                                                      (3,000,000)(4)  218$,669,161
  Other current
   assets...........                          61,226                       61,226
                      ---------------   ------------  -------------   -----------
    Total current
     assets.........     5,220,000         8,305,387  210,425,000     218,730,387
Property and
 equipment, net.....                       6,380,895                    6,380,895
Equity
 investments........                         285,000    (285,000)(5)      --
FCC licenses........                       4,235,734  201,990,000(4)
                                                       6,285,000(5)
                                                       3,600,000(6)   216,110,734
Deferred financing
 costs..............       175,899(3)        857,591    (189,749)(1)
                                                       6,332,474(2)     7,000,316
Equipment and other
 deposits...........                         344,417                      344,417
Other assets........                          23,212                       23,212
                      ---------------   ------------  -------------   -----------
                        $5,395,899      $ 20,432,236  428,1$57,725    448$,589,961
                      ---------------   ------------  -------------   -----------
                      ---------------   ------------  -------------   -----------
      LIABILITIES AN
Current liabilities:
  Accounts payable
   and accrued
   liabilities......    $               $  4,213,517       $            4$,213,517
  CommcoCCC Notes...     2,975,000(2)      2,975,000  (2,975,000)(3)      --
                      ---------------   ------------  -------------   -----------
    Total current
     liabilities....     2,975,000         7,188,517  (2,975,000)       4,213,517
Convertible notes
 payable............       --                --                           --
Note payable to
 EMI................                       1,500,000                    1,500,000
Bridge notes
 payable............                       3,983,082  (3,983,082)(3)
Equipment financing
 note payable.......     1,911,439(3)      1,911,439                    1,911,439
Senior discount
 notes..............                         --       159,800,000(2)  159,800,000
Deferred tax
 liability..........                                  50,490,000(4)    50,490,000
                      ---------------   ------------  -------------   -----------
    Total
     liabilities....     4,886,439        14,583,038  203,331,918     217,914,956
                      ---------------   ------------  -------------   -----------
Redeemable Preferred
 Stock..............                         --           --              --
                      ---------------   ------------  -------------   -----------
Stockholders'
 equity:
  Preferred stock,
   par..............          (921)(1)       --
  Common stock,
   par..............         1,959(1)         30,086       7,500(1)       --
                                                          16,500(4)        54,086
  Additional paid-in
   capital..........        (1,038)(1)
                            25,000(2)
                           484,460(3)     19,883,757  62,160,225(1)
                                                      15,200,000(2)
                                                      148,483,500(4)  245,727,482
  Accumulated
   deficit..........                     (14,064,645) (1,041,918)(3)  (15,106,563)
                      ---------------   ------------  -------------   -----------
    Total
     stockholders'
     equity.........       509,460         5,849,198  224,825,807     230,675,005
                      ---------------   ------------  -------------   -----------
                        $5,395,899      $ 20,432,236  428,1$57,725    448$,589,961
                      ---------------   ------------  -------------   -----------
                      ---------------   ------------  -------------   -----------
</TABLE>
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                      F-3
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                  UNAUDITED PRO FORMA CONDENSED BALANCE SHEETS
                  SUPPLEMENTARY COMBINING BALANCE SHEET DATA:
<TABLE>
<CAPTION>
                                           AS OF DECEMBER 31, 1995
                      -----------------------------------------------------------------
                                                 HISTORICAL
                      -----------------------------------------------------------------
                      ADVANCED RADIO   ADVANCED RADIO
                       TECHNOLOGIES       TELECOM                           HISTORICAL
                      CORPORATION (D)    CORP. (E)      ELIMINATIONS (F)     COMBINED
                      --------------   --------------   ----------------   ------------
<S>                   <C>              <C>              <C>                <C>
Current assets:
  Cash and cash
   equivalents......   $     6,069      $    627,585                       $    633,654
  Due from ART......       --                738,680      $  (738,680)          --
  Other current
   assets...........       --                 52,325                             52,325
                      --------------   --------------   ----------------   ------------
    Total current
     assets.........         6,069         1,418,590         (738,680)          685,979
Note receivable from
 Telecom............     5,000,000          --             (5,000,000)          --
Property and
 equipment, net.....         1,723         3,579,838                          3,581,561
Equity investments..       285,000          --                                  285,000
FCC licenses........         8,913         4,226,821                          4,235,734
Deferred financing
 costs, net.........       457,543           321,354                            778,897
Equipment and other
 deposits...........       --                284,012                            284,012
Investment in ART...       --               --                                  --
Other assets........        25,376          --                                   25,376
                      --------------   --------------   ----------------   ------------
                       $ 5,784,624      $  9,830,615      $(5,738,680)     $  9,876,559
                      --------------   --------------   ----------------   ------------
                      --------------   --------------   ----------------   ------------
                    LIABILITIES AND STOCKHOLDERS' EQUITY (DEFICIT)
Current liabilities:
  Accounts payable
   and accrued
   liabilities......   $   243,952      $  3,450,537                       $  3,694,489
  Due to Telecom....       738,680          --            $  (738,680)          --
  Commco Notes......       --               --                                  --
                      --------------   --------------   ----------------   ------------
    Total current
     liabilities....       982,632         3,450,537         (738,680)        3,694,489
Convertible notes
 payable............     4,950,000          --                                4,950,000
Losses in excess of
 equity investment..       211,543          --               (211,543)          --
Note payable to
 ART................       --              5,000,000       (5,000,000)          --
Note payable to
 EMI................       --              1,500,000                          1,500,000
Bridge notes
 payable............       --               --                                  --
Equipment financing
 note payable.......       --               --                                  --
Senior discount
 notes..............       --               --                                  --
                      --------------   --------------   ----------------   ------------
    Total
     liabilities....     6,144,175         9,950,537       (5,950,223)       10,144,489
                      --------------   --------------   ----------------   ------------
Redeemable Preferred
 Stock..............        44,930          --                                   44,930
                      --------------   --------------   ----------------   ------------
Stockholders'
 equity:
  Preferred stock,
   par..............       --                    488                                488
  Common stock,
   par..............        10,013            15,291                             25,304
  Additional paid-in
   capital..........       988,375         2,845,372         (802,002)
                                                                 (340)        3,031,405
  Accumulated
   deficit..........    (1,402,869)       (2,981,073)       1,013,885        (3,370,057)
                      --------------   --------------   ----------------   ------------
    Total
     stockholders'
     equity
     (deficit)......      (404,481)         (119,922)         211,543          (312,860)
                      --------------   --------------   ----------------   ------------
                       $ 5,784,624      $  9,830,615      $(5,738,680)     $  9,876,559
                      --------------   --------------   ----------------   ------------
                      --------------   --------------   ----------------   ------------
 
<CAPTION>
                                          AS OF MARCH 31, 1996
                      -------------------------------------------------------------
 
                                               HISTORICAL
                      -------------------------------------------------------------
                                          ADVANCED
                      ADVANCED RADIO       RADIO
                       TECHNOLOGIES       TELECOM                       HISTORICAL
                      CORPORATION (D)    CORP. (E)    ELIMINATIONS (F)   COMBINED
                      ---------------   ------------  ---------------   -----------
<S>                   <C>               <C>           <C>               <C>
Current assets:
  Cash and cash
   equivalents......    $    5,970      $3,018,191                        3$,024,161
  Due from ART......       --              498,100      (49$8,100)          --
  Other current
   assets...........       --               61,226                           61,226
                      ---------------   ------------  ---------------   -----------
    Total current
     assets.........         5,970       3,577,517      (498,100)         3,085,387
Note receivable from
 Telecom............       --               --                              --
Property and
 equipment, net.....         1,292       6,379,603                        6,380,895
Equity investments..     3,242,401          --        (2,957,401)           285,000
FCC licenses........         8,913       4,226,821                        4,235,734
Deferred financing
 costs, net.........       --              681,692                          681,692
Equipment and other
 deposits...........       --              344,417                          344,417
Investment in ART...       --               44,930       (44,930)           --
Other assets........        23,212          --                               23,212
                      ---------------   ------------  ---------------   -----------
                        $3,281,788      $15,254,980   (3,50$0,431)       15$,036,337
                      ---------------   ------------  ---------------   -----------
                      ---------------   ------------  ---------------   -----------
 
Current liabilities:
  Accounts payable
   and accrued
   liabilities......         2,500      $4,211,017                        4$,213,517
  Due to Telecom....       498,100          --          (49$8,100)          --
  Commco Notes......       --               --                              --
                      ---------------   ------------  ---------------   -----------
    Total current
     liabilities....       500,600       4,211,017      (498,100)         4,213,517
Convertible notes
 payable............       --               --                              --
Losses in excess of
 equity investment..                        --                              --
Note payable to
 ART................                        --                              --
Note payable to
 EMI................       --            1,500,000                        1,500,000
Bridge notes
 payable............       --            3,983,082                        3,983,082
Equipment financing
 note payable.......       --               --                              --
Senior discount
 notes..............       --               --                              --
                      ---------------   ------------  ---------------   -----------
    Total
     liabilities....       500,600       9,694,099      (498,100)         9,696,599
                      ---------------   ------------  ---------------   -----------
Redeemable Preferred
 Stock..............        44,930          --           (44,930)           --
                      ---------------   ------------  ---------------   -----------
Stockholders'
 equity:
  Preferred stock,
   par..............       --                  921                              921
  Common stock,
   par..............        10,013          18,114                           28,127
  Additional paid-in
   capital..........     7,783,889      19,189,302    (7,597,856)        19,375,335
 
  Accumulated
   deficit..........    (5,057,644)     (13,647,456 )  4,640,455        (14,064,645)
                      ---------------   ------------  ---------------   -----------
    Total
     stockholders'
     equity
     (deficit)......     2,736,258       5,560,881    (2,957,401)         5,339,738
                      ---------------   ------------  ---------------   -----------
                        $3,281,788      $15,254,980   (3,50$0,431)       15$,036,337
                      ---------------   ------------  ---------------   -----------
                      ---------------   ------------  ---------------   -----------
</TABLE>
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                      F-4
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
             UNAUDITED PRO FORMA CONDENSED STATEMENT OF OPERATIONS
<TABLE>
<CAPTION>
                                                      THREE MONTHS ENDED MARCH 31, 1996
                         --------------------------------------------------------------------------------------------
                                                   HISTORICAL
                         --------------------------------------------------------------
                          ADVANCED RADIO   ADVANCED RADIO
                           TECHNOLOGIES       TELECOM                                       PRO FORMA
                         CORPORATION (D)     CORP. (E)     ELIMINATIONS (F)  COMBINED    ADJUSTMENTS (B)   PRO FORMA
                         ----------------  --------------  ---------------  -----------  ---------------  -----------
<S>                      <C>               <C>             <C>              <C>          <C>              <C>
Operating revenue......    $                $      9,620                    $     9,620                   $     9,620
                         ----------------  --------------                   -----------                   -----------
Expenses:
  General and
   administrative
   (H).................          24,939        8,889,364                      8,914,303                     8,914,303
  Market development
   (I).................         --             1,150,063                      1,150,063                     1,150,063
  Research &
   development.........         --               419,418                        419,418                       419,418
Depreciation and
 amortization..........           2,595           86,684                         89,279                        89,279
  Interest, net........             671          130,474                        131,145     $ 198,425(4)
                                                                                              157,316(5)
                                                                                               86,360(6)
                                                                                              (44,507)(7)     528,739
                         ----------------  --------------                   -----------  ---------------  -----------
    Total expenses.....          28,205       10,676,003                     10,704,208       397,594      11,101,802
Equity loss in
 Telecom...............       3,626,570          --          $(3,626,570)       --                            --
                         ----------------  --------------  ---------------  -----------  ---------------  -----------
Pretax loss............       3,654,775       10,666,383      (3,626,570)    10,694,588       397,594      11,092,182
Deferred tax benefit...         --               --                             --                            --
                         ----------------  --------------  ---------------  -----------  ---------------  -----------
      Net loss.........    $  3,654,775     $ 10,666,383     ($3,626,570)   $10,694,588     $ 397,594     $11,092,182
                         ----------------  --------------  ---------------  -----------  ---------------  -----------
                         ----------------  --------------  ---------------  -----------  ---------------  -----------
Pro forma net loss per
 share of common stock
 (G)...................    $       0.12                                                                   $      0.35
                         ----------------                                                                 -----------
                         ----------------                                                                 -----------
Pro forma weighted
 average number of
 shares of Common Stock
 outstanding (G).......      31,651,605                                                                    31,651,605
                         ----------------                                                                 -----------
                         ----------------                                                                 -----------
 
<CAPTION>
 
                             OFFERING       PRO FORMA
                         ADJUSTMENTS (C)   AS ADJUSTED
                         ----------------  ------------
<S>                      <C>               <C>
Operating revenue......                     $    9,620
                                           ------------
Expenses:
  General and
   administrative
   (H).................                      8,914,303
  Market development
   (I).................                      1,150,063
  Research &
   development.........                        419,418
Depreciation and
 amortization..........    $  1,350,692(8)   1,439,971
  Interest, net........
 
                               (264,658)(3)
                                (86,360)(3)
                              5,811,579(7)   5,989,300
                         ----------------  ------------
    Total expenses.....       6,811,253     17,913,055
Equity loss in
 Telecom...............                         --
                         ----------------  ------------
Pretax loss............       6,811,253     17,903,435
Deferred tax benefit...        (459,236)(8)    (459,236)
                         ----------------  ------------
      Net loss.........    $  6,352,017     $17,444,199
                         ----------------  ------------
                         ----------------  ------------
Pro forma net loss per
 share of common stock
 (G)...................                     $     0.31
                                           ------------
                                           ------------
Pro forma weighted
 average number of
 shares of Common Stock
 outstanding (G).......                     55,651,605
                                           ------------
                                           ------------
</TABLE>
<TABLE>
<CAPTION>
                                       YEAR ENDED DECEMBER 31, 1995
                      --------------------------------------------------------------
                                                HISTORICAL
                      --------------------------------------------------------------
                      ADVANCED RADIO     ADVANCED
                       TECHNOLOGIES    RADIO TELECOM
                      CORPORATION (D)    CORP. (E)     ELIMINATIONS (F)    COMBINED
                      --------------   -------------   ----------------   ----------
<S>                   <C>              <C>             <C>                <C>
Operating revenue...    $  --           $     5,793                       $   5,793
                      --------------   -------------                      ----------
Expenses:
  General and
   administrative
   (G)..............       204,937        2,706,336                       2,911,273
  Market
   development......       --               191,693                         191,693
  Depreciation and
   amortization.....        10,378            5,306                          15,684
  Interest, net.....        38,455           83,531                         121,986
                      --------------   -------------                      ----------
    Total
     expenses.......       253,770        2,986,866                       3,240,636
Equity loss in
 Telecom............     1,013,885                       $(1,013,885)        --
                      --------------   -------------   ----------------   ----------
Pretax Loss.........     1,267,655        2,981,073       (1,013,885)     3,234,843
Deferred tax
 benefit............       --               --                               --
                      --------------   -------------   ----------------   ----------
      Net loss......    $1,267,655      $ 2,981,073      $(1,013,885)     $3,234,843
                      --------------   -------------   ----------------   ----------
                      --------------   -------------   ----------------   ----------
Pro forma net loss
 per share of Common
 Stock (G)..........    $     0.04
                      --------------
                      --------------
Pro forma weighted
 average number of
 shares of Common
 Stock outstanding
 (G)................    31,651,605
                      --------------
                      --------------
 
<CAPTION>
 
                         PRO FORMA                     OFFERING        PRO FORMA
                      ADJUSTMENTS (B)   PRO FORMA   ADJUSTMENTS (C)   AS ADJUSTED
                      ---------------   ----------  ---------------   -----------
<S>                   <C>               <C>         <C>               <C>
Operating revenue...                    $   5,793       $               $5,793
                                        ----------  ---------------   -----------
Expenses:
  General and
   administrative
   (G)..............                    2,911,273                     2,911,273
  Market
   development......                      191,693                      191,693
  Depreciation and
   amortization.....                       15,684    5,402,768(8)     5,418,452
  Interest, net.....  $1,019,145(4)
                         673,534(5)
                         270,438(6)
                        (110,828)(7)    1,974,275   (1,019,145)(3)
                                                      (270,438)(3)
                                                    23,246,316(7)     23,931,008
                      ---------------   ----------  ---------------   -----------
    Total
     expenses.......   1,852,289        5,092,925   27,359,501        32,452,426
Equity loss in
 Telecom............                       --                            --
                      ---------------   ----------  ---------------   -----------
Pretax Loss.........   1,852,289        5,087,132   27,359,501        32,446,633
Deferred tax
 benefit............      --                        (1,836,941)(8)    (1,836,941)
                      ---------------   ----------  ---------------   -----------
      Net loss......  $1,852,289        $5,087,132  25,5$22,560       30$,609,692
                      ---------------   ----------  ---------------   -----------
                      ---------------   ----------  ---------------   -----------
Pro forma net loss
 per share of Common
 Stock (G)..........                    $    0.16                       $ 0.55
                                        ----------                    -----------
                                        ----------                    -----------
Pro forma weighted
 average number of
 shares of Common
 Stock outstanding
 (G)................                    31,651,605                    55,651,605
                                        ----------                    -----------
                                        ----------                    -----------
</TABLE>
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                      F-5
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
          NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS
 
(A)  Represents the historical  combined balance sheets of  ART and Telecom. See
    supplementary combining balance sheet data on page F-4.
 
(B) Pro forma adjustments:
 
    (1) Conversion of Telecom serial preferred stock into Telecom common  stock,
       issuance of ART Common Stock to Telecom stockholders, and cancellation of
       the  outstanding Telecom  common stock  and the  ART Redeemable Preferred
       Stock in connection with the Merger.
 
    (2) Proceeds of $3,000,000 in cash from the CommcoCCC Financing in  exchange
       for the CommcoCCC Notes and CommcoCCC Warrants. The value ascribed to the
       CommcoCCC Warrants totaled $25,000.
 
    (3) Proceeds of $2,220,000 in cash from the Equipment Financing and issuance
       of  the  Indemnity  Warrants,  net  of  the  related  financing  costs of
       $225,000. The value ascribed to the Indemnity Warrants totaled $484,460.
 
    (4) Interest expense from the  Bridge Financing provided by stockholders  of
       Telecom  at the effective interest rate  after giving effect to the value
       ascribed to the Bridge Warrants, as if the Bridge Notes were issued as of
       the beginning of the respective periods.
 
    (5) Interest expense from the Equipment Financing at the effective  interest
       rate after giving effect to the value ascribed to the Indemnity Warrants,
       as  if  the  Equipment Notes  were  issued  as of  the  beginning  of the
       respective periods.
 
    (6) Interest expense from the CommcoCCC Financing, at the effective interest
       rate after giving effect to the value ascribed to the CommcoCCC Warrants,
       as if  the  CommcoCCC  Notes were  issued  as  of the  beginning  of  the
       respective periods.
 
    (7)  Elimination  of  interest  expense  from  the  Advent  Notes  that were
       converted into shares of Telecom stock on February 2, 1996.
 
(C) Offering adjustments:
 
    (1) Issuance of 7,500,000 shares of Common Stock offered in the Common Stock
       Offering based on an assumed initial  public offering price of $9.00  per
       share,  after  deducting  the  estimated  offering  discount  and related
       expenses of $5,332,275.
 
    (2) Assumed gross proceeds  of $175,000,000 from the  issuance of the  Notes
       and  Warrants  in  the  Unit  Offering,  and  related  estimated offering
       discount and related expenses  of $6,824,417. The  value ascribed to  the
       Unit Warrants totaled $15,200,000.
 
    (3) Repayment of the Bridge Financing and CommcoCCC Financing out of the net
       proceeds  from the  Offerings and  the reversal  of the  related interest
       expense. The  unamortized offering  discount and  deferred finance  costs
       associated  with the Bridge Financing and CommcoCCC Financing will result
       in an  extraordinary  loss of  approximately  $1,000,000 which  has  been
       excluded from the pro forma as adjusted presentation.
 
    (4)  The  acquisition of  the CommcoCCC  Assets  in exchange  for 16,500,000
       shares of Common Stock of the Company based on an assumed value of  $9.00
       per share, the related deferred tax liabilities and the estimated related
       expenses of $3,000,000.
 
    (5)  The  acquisition of  the 50%  ownership  interest of  ART West  held by
       Extended for $6 million in cash, to be paid out of the net proceeds  from
       the Offerings..
 
    (6)  The acquisition of the DCT assets for  $3.6 million in cash, to be paid
       out of the net proceeds from the Offerings.
 
    (7) Interest  expense on  the Notes,  at  an assumed  coupon rate  of  13.5%
       (resulting in an effective interest rate of 15.2% on the Notes, including
       the  amortization of debt issuance costs and original issue discount), as
       if the Notes were issued as  of the beginning of the respective  periods.
       If the interest rate on the Notes changed by 0.5%, interest expense would
       change by approximately $765,000 and $191,250 for the year ended December
       31, 1995 and three months ended March 31, 1996, respectively.
 
                                      F-6
<PAGE>
    (8)  Depreciation and amortization expense related to the acquisition of the
       CommcoCCC Assets, the 50% ownership interest in ART West, the DCT  Assets
       and the related deferred taxes.
 
(D)  Represents the  historical amounts of  ART as  of and for  the three months
    ended March 31, 1996 and as of and for the year ended December 31, 1995.
 
(E) Represents the historical amounts of Telecom as of and for the three  months
    ended  March 31, 1996, as of December 31, 1995 and for the period from March
    28, 1995 (date of inception) to December 31, 1995.
 
(F)  Represents  the  elimination  of  inter-entity  transactions  and  balances
    consisting  of  (i)  receivables  and  payables,  (ii)  ART's  investment in
    Telecom,  Telecom's  corresponding  stockholder   equity  amounts  and   the
    recognition  by ART of its  equity in losses of  Telecom and (iii) Telecom's
    investment in ART Redeemable Preferred Stock.
 
(G) Pro forma net loss  per share and the weighted  average number of shares  of
    Common  Stock reflect  (i) the  conversion of  all shares  of Telecom serial
    preferred stock to Telecom common stock;  (ii) issuance of ART Common  Stock
    to  Telecom stockholders, (iii) the  cancellation of the outstanding Telecom
    common stock and the ART Series  A Redeemable Preferred Stock; and (iv)  the
    issuance of potentially dilutive instruments issued within one year prior to
    a  proposed initial  public offering  at exercise  prices below  the assumed
    initial public offering price of $9.00 per share as if they were outstanding
    as of the beginning of the respective periods.
 
<TABLE>
<S>                                                                   <C>
Pro Forma:
  Weighted average number of shares of Common Stock outstanding for
   primary computation..............................................      10,013,055(1)
  Issuances of shares of Telecom serial preferred stock as converted
   into shares of ART Common Stock..................................      10,916,807
  Issuances of shares of Telecom common stock as converted into
   shares of ART Common Stock.......................................       8,100,807(2)
  Options and warrants issued and outstanding.......................       2,620,936
                                                                      --------------
  Pro forma weighted average number of shares of Common Stock.......      31,651,605(3)
                                                                      --------------
                                                                      --------------
Pro Forma As Adjusted:
  Pro forma weighted average number of shares of Common Stock.......      31,651,605
  Common Stock issued in connection with the Common Stock Offering
   and the acquisition of the CommcoCCC Assets......................      24,000,000
                                                                      --------------
  Pro forma as adjusted weighted average number of shares of Common
   Stock............................................................      55,651,605(3)
                                                                      --------------
                                                                      --------------
</TABLE>
 
    (1) The  weighted average  number  of shares  of  Common Stock  for  primary
       computation   exclude   all   common   stock   equivalents,   which   are
       anti-dilutive.
 
    (2) Excludes shares of Telecom common stock owned by ART.
 
    (3)  The  Securities  and  Exchange  Commission  requires  that  potentially
       dilutive  instruments issued within one year  prior to a proposed initial
       public offering  at exercise  prices below  the expected  initial  public
       offering price be treated as outstanding for the entire period presented.
       The  weighted average number of shares of Common Stock on a pro forma and
       a pro  forma  as  adjusted  basis  reflects  those  potentially  dilutive
       instruments  assuming the sale  of shares of Common  Stock offered in the
       Common Stock Offering based on  an assumed initial public offering  price
       of $10.00 per share. In measuring the dilutive effect, the treasury stock
       method was used.
 
(H)  General  and  administrative  expense  includes  a  non-recurring, non-cash
    compensation expense of $802,002 and $6,795,514 for the year ended  December
    31,  1995  and for  the  three months  ended  March 31,  1996, respectively,
    associated with the release of Escrow Shares in 1995 and the termination  of
    the Escrow Shares arrangement in 1996.
 
(I)  Market  development  expense for  the  three  months ended  March  31, 1996
    includes $1,053,000,  representing  the  value  ascribed  to  the  Strategic
    Distribution  Agreement in connection  with the February  1996 investment in
    Telecom by Ameritech.
 
                                      F-7
<PAGE>
                       REPORT OF INDEPENDENT ACCOUNTANTS
 
To the Stockholders of
Advanced Radio Technologies Corporation:
 
    We   have  audited  the  accompanying   balance  sheets  of  Advanced  Radio
Technologies Corporation (a development stage  company) as of December 31,  1995
and  1994, and the  related statements of  operations, stockholders' deficit and
cash flows for the years ended December  31, 1995 and 1994, for the period  from
August  23, 1993 (date of inception) to December 31, 1993 and for the cumulative
period from August  23, 1993  (date of inception)  to December  31, 1995.  These
financial  statements are  the responsibility  of the  Company's management. Our
responsibility is to express an opinion  on these financial statements based  on
our audits.
 
    We  conducted  our audits  in  accordance with  generally  accepted auditing
standards. Those standards require that we plan and perform the audits to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence  supporting
the  amounts and disclosures in the financial statements. An audit also includes
assessing the  accounting  principles used  and  significant estimates  made  by
management,  as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
    In our opinion, the financial  statements referred to above present  fairly,
in  all material respects, the financial position of Advanced Radio Technologies
Corporation as of December 31, 1995 and 1994, and the results of its  operations
and  its cash flows for the years ended  December 31, 1995 and 1994, and for the
period from  August  23, 1993  (date  of inception)  to  December 31,  1993,  in
conformity with generally accepted accounting principles.
 
    The  accompanying  financial  statements  have been  prepared  on  the going
concern basis  of  accounting,  which contemplates  realization  of  assets  and
liquidation  of liabilities in the ordinary  course of business. As described in
Note 1, the Company  has a substantial working  capital deficit at December  31,
1995,  has  incurred operating  losses since  inception and  does not  expect to
generate significant operating revenues until fiscal 1996. The Company estimates
that revenues  in  1996 will  not  be sufficient  to  fund its  initial  capital
requirements,  operating expenses and other  working capital needs. In addition,
as set forth in  Notes 5, 7,  8, and 11, the  Company has significant  financial
commitments.   The   Company's  continued   funding   of  its   initial  capital
requirements,  operating  expenses,  working   capital  needs  and   contractual
commitments  is  dependent  upon  its  ability  to  raise  additional financing.
Management's plans in  this regard  are discussed  in Note  1. These  conditions
raise  substantial  doubt about  the Company's  ability to  continue as  a going
concern. The  financial statements  do not  include any  adjustments that  might
result from the outcome of these uncertainties.
 
                                          COOPERS & LYBRAND L.L.P.
 
New York, New York
April 26, 1996, except for Note 2C, Note 5B and
  the second paragraph of Note 9
  as to which the date is June 26, 1996
 
                                      F-8
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                                 BALANCE SHEETS
                           DECEMBER 31, 1995 AND 1994
 
<TABLE>
<CAPTION>
                                                                                           1995           1994
                                                                                      --------------  ------------
<S>                                                                                   <C>             <C>
                                                      ASSETS
Current assets:
  Cash..............................................................................  $        6,069  $      5,133
                                                                                      --------------  ------------
      Total current assets..........................................................           6,069         5,133
Note receivable from Telecom (Note 4)...............................................       5,000,000
Equity investments (Note 5).........................................................         285,000
Deferred financing costs, net.......................................................         457,543
FCC licenses........................................................................           8,913
Property and equipment, net.........................................................           1,723         3,448
Other assets........................................................................          25,376        34,030
                                                                                      --------------  ------------
      Total assets..................................................................  $    5,784,624  $     42,611
                                                                                      --------------  ------------
                                                                                      --------------  ------------
 
                                      LIABILITIES AND STOCKHOLDERS' DEFICIT
Current liabilities:
  Accounts payable and accrued liabilities..........................................  $      243,952  $     11,689
  Due to Telecom (Note 11)..........................................................         738,680
  Note payable to related party (Note 11)...........................................                        70,000
                                                                                      --------------  ------------
      Total current liabilities.....................................................         982,632        81,689
Equity loss in excess of investment (Note 5)........................................         211,543
Convertible note payable (Note 4)...................................................       4,950,000
                                                                                      --------------  ------------
      Total liabilities.............................................................       6,144,175        81,689
                                                                                      --------------  ------------
Redeemable Preferred Stock, $.01 par value; 1,000 shares authorized; 1 share issued
 and outstanding at December 31,
 1995 (Note 4)......................................................................          44,930
                                                                                      --------------  ------------
Commitments and contingencies (Notes 1, 5, 7, 8, 11 and 12).........................
 
Stockholders' deficit (Note 9):
  Common Stock, $.001 par value; 58,900,320 shares authorized; 10,013,055 and
   5,890,032 shares issued and outstanding..........................................          10,013         5,890
  Additional paid-in capital........................................................         988,375        90,246
  Deficit accumulated during the development stage..................................      (1,402,869)     (135,214)
                                                                                      --------------  ------------
      Total stockholders' deficit...................................................        (404,481)      (39,078)
                                                                                      --------------  ------------
        Total liabilities and stockholders' deficit.................................  $    5,784,624  $     42,611
                                                                                      --------------  ------------
                                                                                      --------------  ------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-9
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENTS OF OPERATIONS
                FOR THE YEARS ENDED DECEMBER 31, 1995 AND 1994,
            FOR THE PERIOD FROM AUGUST 23, 1993 (DATE OF INCEPTION)
               TO DECEMBER 31, 1993 AND CUMULATIVE FOR THE PERIOD
         FROM AUGUST 23, 1993 (DATE OF INCEPTION) TO DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
                                                                                                        CUMULATIVE
                                                                                         PERIOD FROM    FROM AUGUST
                                                                                         AUGUST 23,      23, 1993
                                                                   YEARS ENDED          1993 (DATE OF    (DATE OF
                                                                   DECEMBER 31,         INCEPTION) TO  INCEPTION) TO
                                                            --------------------------  DECEMBER 31,   DECEMBER 31,
                                                                1995          1994          1993           1995
                                                            -------------  -----------  -------------  -------------
<S>                                                         <C>            <C>          <C>            <C>
Consulting income.........................................  $    --        $   137,489    $  --         $   137,489
                                                            -------------  -----------  -------------  -------------
Expenses:
  General and administrative expenses.....................        204,937      253,453        5,906         464,296
  Depreciation and amortization...........................         10,378        8,281          688          19,347
  Interest expense, net (Note 11).........................         38,455        4,375                       42,830
                                                            -------------  -----------  -------------  -------------
      Total expenses......................................        253,770      266,109        6,594         526,473
Equity loss on investment in Telecom (Note 5).............      1,013,885                                 1,013,885
                                                            -------------  -----------  -------------  -------------
      Net loss............................................  $   1,267,655  $   128,620    $   6,594     $ 1,402,869
                                                            -------------  -----------  -------------  -------------
                                                            -------------  -----------  -------------  -------------
Pro forma net loss per share (unaudited)..................  $        0.04
                                                            -------------
                                                            -------------
Pro forma weighted average number of shares of Common
 Stock outstanding (unaudited)............................     31,651,605
                                                            -------------
                                                            -------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-10
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                  STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)
                FOR THE YEARS ENDED DECEMBER 31, 1995 AND 1994,
            FOR THE PERIOD FROM AUGUST 23, 1993 (DATE OF INCEPTION)
               TO DECEMBER 31, 1993 AND CUMULATIVE FOR THE PERIOD
         FROM AUGUST 23, 1993 (DATE OF INCEPTION) TO DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
                                                                                         DEFICIT
                                                                                       ACCUMULATED
                                                                         ADDITIONAL       DURING
                                                               COMMON      PAID-IN     DEVELOPMENT
                                                                STOCK      CAPITAL        STAGE           TOTAL
                                                              ---------  -----------  --------------  --------------
<S>                                                           <C>        <C>          <C>             <C>
Net issuance of 2,945,016 shares of Common Stock for cash...  $   2,945  $    58,191                  $       61,136
Net loss....................................................                          $       (6,594)         (6,594)
                                                              ---------  -----------  --------------  --------------
Balance, December 31, 1993..................................      2,945       58,191          (6,594)         54,542
Issuance of 2,945,016 shares of Common Stock for cash.......      2,945       32,055                          35,000
Net loss....................................................                                (128,620)       (128,620)
                                                              ---------  -----------  --------------  --------------
Balance, December 31, 1994..................................      5,890       90,246        (135,214)        (39,078)
Issuance of 73,625 shares of Common Stock to ART West.......         74       24,926                          25,000
Issuance of 4,049,398 shares of Common Stock to existing
 shareholders...............................................      4,049       (4,049)
Conversion of note payable and interest to paid-in
 capital....................................................                  75,250                          75,250
Investment in Telecom as a result of the release of escrow
 shares.....................................................                 802,002                         802,002
Net loss....................................................                              (1,267,655)     (1,267,655)
                                                              ---------  -----------  --------------  --------------
Balance, December 31, 1995..................................  $  10,013  $   988,375  $   (1,402,869) $     (404,481)
                                                              ---------  -----------  --------------  --------------
                                                              ---------  -----------  --------------  --------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-11
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENTS OF CASH FLOWS
                FOR THE YEARS ENDED DECEMBER 31, 1995 AND 1994,
            FOR THE PERIOD FROM AUGUST 23, 1993 (DATE OF INCEPTION)
               TO DECEMBER 31, 1993 AND CUMULATIVE FOR THE PERIOD
         FROM AUGUST 23, 1993 (DATE OF INCEPTION) TO DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
                                                                                            PERIOD FROM     CUMULATIVE
                                                                                            AUGUST 23,     FROM AUGUST
                                                                     YEARS ENDED           1993 (DATE OF  23, 1993 (DATE
                                                                    DECEMBER 31,           INCEPTION) TO  OF INCEPTION)
                                                            -----------------------------  DECEMBER 31,    TO DECEMBER
                                                                 1995           1994           1993          31, 1995
                                                            --------------  -------------  -------------  --------------
<S>                                                         <C>             <C>            <C>            <C>
Cash flows from operating activities:
  Net loss................................................  $   (1,267,655) $    (128,620)  $    (6,594)  $   (1,402,869)
  Adjustments to reconcile net loss to net cash used in
   operating activities:
    Non-cash interest expense.............................         110,828                                       110,828
    Depreciation and amortization.........................          10,378          8,281           688           19,347
    Equity loss on investment in Telecom..................       1,013,885                                     1,013,885
  Changes in operating assets and liabilities:
    Accounts payable and accrued liabilities..............          (3,939)        (8,282)       19,971            7,750
                                                            --------------  -------------  -------------  --------------
      Net cash (used in) provided by operating
       activities.........................................        (136,503)      (128,621)       14,065         (251,059)
                                                            --------------  -------------  -------------  --------------
Cash flows from investing activities:
  Additions to property and equipment.....................                         (5,175)                        (5,175)
  Investment in ART West and Telecom......................        (255,340)                                     (255,340)
  Note receivable from Telecom............................      (5,000,000)                                   (5,000,000)
  Acquisition of FCC Licenses.............................         (13,912)                                      (13,912)
  Increase in other assets................................                                      (41,272)         (41,272)
                                                            --------------  -------------  -------------  --------------
      Net cash used in investing activities...............      (5,269,252)        (5,175)      (41,272)      (5,315,699)
                                                            --------------  -------------  -------------  --------------
Cash flows from financing activities:
  Proceeds from issuance of Common Stock..................                         35,000        61,136           96,136
  Proceeds from loan and note payable.....................           8,500         70,000                         78,500
  Proceeds from issuance of Preferred Stock...............          50,000                                        50,000
  Preferred Stock issuance costs..........................          (5,070)                                       (5,070)
  Repayment of loan.......................................          (8,500)                                       (8,500)
  Proceeds from convertible note payable..................       4,950,000                                     4,950,000
  Deferred financing costs................................        (326,919)                                     (326,919)
  Due to Telecom..........................................         738,680                                       738,680
                                                            --------------  -------------  -------------  --------------
      Net cash provided by financing activities...........       5,406,691        105,000        61,136        5,572,827
                                                            --------------  -------------  -------------  --------------
      Net increase (decrease) in cash.....................             936        (28,796)       33,929            6,069
Cash, beginning of period.................................           5,133         33,929
                                                            --------------  -------------  -------------  --------------
Cash, end of period.......................................  $        6,069  $       5,133   $    33,929   $        6,069
                                                            --------------  -------------  -------------  --------------
                                                            --------------  -------------  -------------  --------------
Supplemental cash flow information:
Non-cash investing and financing activities:
  Release of escrow shares and increase in the investment
   in Telecom.............................................  $      802,002                                $      802,002
  Issuance of stock and contribution of licenses to ART
   West...................................................  $       30,000                                $       30,000
  Conversion of note payable and interest to Common
   Stock..................................................  $       75,250                                $       75,250
  Accrued deferred financing costs........................  $      175,000                                $      175,000
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-12
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                         NOTES TO FINANCIAL STATEMENTS
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION:
 
THE COMPANY
 
    Advanced  Radio  Technologies  Corporation  ("ART"  or  the  "Company")  was
organized as a  Delaware corporation on  August 23, 1993,  to provide  broadband
wireless  digital telecommunications services to the domestic telecommunications
market. The  Company's  operations  to  date include  the  application  for  and
acquisition  of certain  38 GHz licenses  granted by  the Federal Communications
Commission ("FCC") and costs incurred for the deployment of such services.
 
    During 1995,  The Company  established a  strategic alliance  with  Extended
Communications,  Inc. ("Extended") to form the  ART West joint venture. ART West
was formed on April 4, 1995 to develop and expand the Company's wireless digital
telecommunications services  in various  markets throughout  the western  United
States (see Note 5).
 
    During  1995, Advanced Radio Telecom Corp.  ("Telecom") was organized by the
Company and Landover Holdings Corporation  ("Landover") with one of its  initial
objectives  to acquire certain 38 GHz licenses in the northeastern United States
from EMI Communications, Corp. ("EMI"). Under the terms of a purchase  agreement
between  the Company, Landover, and Telecom dated April 21, 1995, (the "Purchase
Agreement") Landover  was  obligated to  purchase  $7,000,000 of  securities  of
Telecom.  Pursuant  to  the  Purchase Agreement  and  a  stockholders' agreement
between the Company, Telecom and their respective shareholders dated May 8, 1995
(the "Stockholders'  Agreement"), the  Company and  Telecom were  to merge  once
approval from the FCC had been granted. (See Note 2).
 
INITIAL CAPITALIZATION
 
    The  Company was  formed on August  23, 1993  by two of  its executives (the
"Founding Stockholders") by issuing 2,945,016 shares of Common Stock in exchange
for $1,136. During November 1993, ART redeemed 1,178,006 shares of Common  Stock
from  the Founding Stockholders and through a private placement issued 1,178,006
shares of Common Stock to High Sky Limited Partnership ("High Sky") in  exchange
for $60,000. During March 1994, High Sky II Limited Partnership ("High Sky II"),
an   affiliate  of  High  Sky  (collectively   referred  to  as  the  "High  Sky
Partnerships") contributed  $100,000  to the  Company  in exchange  for  589,003
shares  of Common Stock  and a $70,000  Promissory Note. In  connection with the
High Sky II financing, ART issued an additional aggregate of 2,356,013 shares to
the Founding Stockholders and High Sky whereby the Founding Stockholders and the
High Sky Partnerships would each own a 50% interest in ART. Additionally, during
1994, one  of the  Founding Stockholders  contributed an  additional $5,000  for
which contribution there were no shares issued.
 
    Pursuant  to an agreement dated March 1,  1995, High Sky II agreed to assign
the $70,000 Promissory Note, plus accrued interest, to the Founding Stockholders
in exchange for two new promissory notes executed by the Founding  Stockholders.
Concurrent  with the exchange of the promissory notes, the Founding Stockholders
contributed the $70,000 Promissory Note plus  accrued interest of $5,250 to  the
Company, for which contribution there were no additional shares issued.
 
BASIS OF PRESENTATION
 
    The  financial statements have  been prepared on the  going concern basis of
accounting,  which  contemplates  realization  of  assets  and  liquidation   of
liabilities  in the ordinary  course of business. The  Company has a substantial
working capital deficit, has incurred operating losses since inception and  does
not expect to recognize significant operating revenues until the commencement of
its  commercial  services, which  is anticipated  to occur  in fiscal  1996. The
Company estimates  that revenues  in 1996  will not  be sufficient  to fund  its
initial   operating  expenses   and  other  working   capital  needs,  including
 
                                      F-13
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION, CONTINUED:
consulting, service and purchase commitments set forth in Notes 5, 7, 8 and  11.
The  Company's  continued funding  of  its initial  operating  expenses, working
capital needs and contractual commitments is dependent upon its ability to raise
additional financing. The  Company and Telecom  have engaged various  investment
bankers  to assist them  in raising financing  through a public  equity and debt
offering. There  can  be no  assurance  that the  Company  and Telecom  will  be
successful in their effort to raise additional financing through these offerings
or,  if available,  that the Company  and Telecom will  be able to  obtain it on
acceptable terms. These conditions raise  substantial doubt about the  Company's
ability  to continue as a going concern. The financial statements do not include
any adjustments that might result from the outcome of these uncertainties.
 
2.  PURCHASE AGREEMENT:
 
A -- INITIAL CAPITALIZATION OF TELECOM
 
    Pursuant to  the  Purchase  Agreement, as  its  initial  capitalization,  an
aggregate of 8,580,000 shares of Class B and Class A common stock were issued by
Telecom  to Landover and consultants to Landover, respectively, for an aggregate
cash consideration of $1,020. Such  shares of Class B  and Class A common  stock
represented  64% and  2%, respectively,  of the  total number  shares of capital
stock of Telecom then outstanding. Concurrently, the Company received  4,420,000
shares  of Class A common stock, representing  34% of the total number of shares
of capital stock of Telecom  then outstanding in exchange  for $340. All of  the
above  references to  shares of  common stock of  Telecom have  been adjusted to
reflect a 13 for 1 stock split which occurred in February 1996, but are prior to
the issuance of anti-dilutive shares described below.
 
    Under the  Purchase Agreement,  Landover agreed  to invest  or cause  to  be
invested  $7,000,000 in ART, Telecom and their affiliates (the "Landover Funding
Commitment"). In consideration for this $7,000,000 investment, Telecom agreed to
issue preferred stock,  the number  of shares of  which would  be designated  by
Landover.  Under the  anti-dilution provisions of  the Class A  common stock, in
respect of each such preferred stock  issuance, Telecom agreed to issue, for  no
consideration,  additional shares of Class A common stock in number necessary to
maintain the 36% ownership interest in Telecom of the holders of Class A  common
stock.
 
    Under  the Purchase  Agreement, the  individual shareholders  of the Company
were required to place 5,153,778 shares of Common Stock in the Company in escrow
(the "Escrow Shares") to be released upon the completion of the then pending EMI
Asset acquisition  (see  Note 8),  Telecom's  attainment of  specific  operating
income  levels for the years 1997 through  1999 and the acquisition of interests
in a specified  number of FCC  license authorizations  by April 30,  2000. As  a
result  of  the consummation  of the  EMI Asset  acquisition, in  November 1995,
1,873,030 of the  Escrow Shares  of ART  were released.  The fair  value of  the
Escrow Shares released in 1995, amounting to $802,002, has been accounted for as
an  equity investment  in Telecom,  the effect of  which has  been recognized as
additional paid-in capital  in the  Company. Pursuant  to the  February 2,  1996
Reorganization,  the Escrow  Shares arrangement  was terminated  and all  of the
remaining Escrow Shares were  released to the stockholders  of the Company.  The
fair   value  of  the  remaining  Escrow  Shares  released,  in  the  amount  of
approximately $6.8 million,  will be  accounted for  in the  same manner  during
1996.
 
B -- MERGER
 
    Under the terms of the Purchase Agreement, the Company and Telecom intend to
operate  both companies as a single enterprise and are committed to merge if and
when permitted by the FCC.
 
                                      F-14
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
2.  PURCHASE AGREEMENT, CONTINUED:
Concurrent with the Purchase Agreement, the Company and Telecom entered into  an
exclusive   20-year  services  agreement  (the  "Services  Agreement")  for  the
construction, development and operation of systems in the Company's markets (see
Note 6).
 
    On February 2, 1996, the Company, Telecom and their respective  shareholders
agreed  to an amendment and restatement of the Stockholders' Agreement providing
for (i) termination effective  on the closing of  a public share offering,  (ii)
amendment and restatement of the Certificate of Incorporation and reorganization
of  the capital structure of Telecom; (iii) the exchange of the Advent Notes and
one share of  ART Series A  Redeemable Preferred  Stock for shares  of Series  E
preferred  stock  of  Telecom (see  Note  4);  (iv) revision  of  provisions for
election of  directors;  (v) amendment  and  restatement of  ART's  registration
rights  agreements;  (vi)  release of  shares  escrowed in  connection  with the
original Stockholders' Agreement; and (vii)  approval of a definitive  agreement
to merge the Company and Telecom (the "Reorganization").
 
C -- AMENDED MERGER
 
    The  definitive merger  agreement, as entered  into on February  2, 1996 and
subsequently restated and  amended on  June 26, 1996,  (the "Merger  Agreement")
provides for the merger of a newly-formed wholly owned subsidiary of the Company
("Merger  Sub")  into  Telecom  (the "Merger")  subject  to  certain conditions,
including the receipt  of FCC approval.  Prior to the  Merger, each  outstanding
share  of Telecom's serial preferred  stock will be converted  into 13 shares of
Telecom's common stock. In the Merger, each outstanding share of common stock of
Telecom will be exchanged for the right to receive an equal number of shares  of
Common  Stock of the  Company. As a  result, Telecom will  become a wholly owned
subsidiary of the Company. The Merger  Agreement provides that if the Merger  is
not  consummated by May 13, 1997, the  shares of Telecom's common stock owned by
the Company will be surrendered to Telecom, and the Services Agreements is to be
revised to, among other revisions, extend the term to 40 years and provide for a
proportionate participation by the Company's stockholders in any dividends  paid
by  Telecom or the proceeds from any  sale of Telecom. The Merger Agreement also
provides for the  assignment of Telecom's  interests in all  of its  agreements,
including  the  various  services agreements,  employment  agreements, equipment
purchase agreements and  purchase option  agreements, to  the Company.  Further,
upon  the Merger, the holders of warrants  to purchase an aggregate of 2,302,136
shares of Telecom common stock will be entitled to purchase an equivalent number
of shares of Common Stock on the same terms. Employee stock options to  purchase
1,664,732  shares of Telecom's common stock will be converted into similar stock
options of the Company.
 
3.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
 
DEVELOPMENT STAGE ENTERPRISE
 
    The Company is  a development stage  enterprise as defined  in Statement  of
Financial  Accounting Standards No. 7,  "Accounting and Reporting by Development
Stage Enterprises." The  financial statements  have been prepared  on the  going
concern basis of accounting.
 
PROPERTY AND EQUIPMENT
 
    Property  and equipment is stated at  cost. Depreciation and amortization is
computed using the straight-line method over the estimated useful lives of three
years.
 
                                      F-15
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
INVESTMENTS
 
    The Company accounts for its 50% interest in the ART West joint venture  and
its 34% interest in Telecom under the equity method.
 
FCC LICENSES
 
    The   Company  has   obtained  radio   spectrum  rights   under  FCC  issued
authorizations and licenses throughout the United States by petitioning the  FCC
directly  and through the purchase of such  rights held by others. Such licenses
are issued for an initial term of six years and are renewable subject to  review
by  the FCC.  The costs  associated with  the acquisition  of such  licenses are
capitalized and  amortized  on  a  straight-line basis  over  a  40-year  period
beginning  upon commencement  of operations in  the related  market. The 40-year
period is based upon management's license renewal expectations.
 
RECOVERABILITY OF LONG-LIVED ASSETS
 
    The  recoverability   of  property   and  equipment   and  capitalized   FCC
authorizations  and  licenses is  dependent upon  the successful  development of
systems in  each of  the respective  markets, or  through sale  of such  assets.
Management  estimates that  it will recover  the carrying amount  of those costs
from cash flow generated by the systems once they have been developed.  However,
it  is reasonably  possible that such  estimate will  change as a  result of the
failure to develop the FCC authorizations  on a timely basis, or  technological,
regulatory or other changes.
 
    The  Company's policy  is to assess  annually any impairment  in value based
upon a comparison of  projected operating cash flows  from each market over  its
expected  period of operation, on an  undiscounted basis, to the carrying amount
of the property and equipment, licenses  and other capitalized costs related  to
the market.
 
FINANCING COSTS
 
    Direct  costs  associated with  obtaining  debt financing  are  deferred and
charged to interest expense  using the effective interest  rate method over  the
term  of the debt.  Direct costs associated with  obtaining equity financing are
deferred and charged  to additional  paid-in capital  as the  related funds  are
raised.  Deferred costs associated  with unsuccessful financings  are charged to
expense.
 
    Accumulated amortization  of deferred  financing  costs totaled  $44,376  at
December 31, 1995.
 
REVENUE RECOGNITION
 
    Revenue  from telecommunications  services are  recognized ratably  over the
period such services are provided.
 
    During 1994, the Company recognized  income from consulting fees  associated
with  the  application of  FCC licenses  on behalf  of third  parties, including
consulting fees of approximately $80,000 from Extended.
 
INCOME TAXES
 
    The Company  accounts  for  income  taxes  under  the  liability  method  of
accounting.  Under the liability method, deferred  taxes are determined based on
the differences between  the financial  statement and  tax bases  of assets  and
liabilities  at enacted tax rates in effect in the year in which the differences
are expected to reverse. Valuation  allowances are established, when  necessary,
to reduce deferred tax assets to the amounts expected to be realized.
 
                                      F-16
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
NET LOSS PER SHARE
 
    Historical  net loss per share is computed  based on the loss for the period
divided by the  weighted average number  of shares of  Common Stock  outstanding
during the period. Historical net loss per share and the weighted average number
of shares of Common Stock outstanding are as follows:
 
<TABLE>
<CAPTION>
                                                                                       FOR THE PERIOD
                                                           FOR THE YEARS ENDED        FROM AUGUST 23,
                                                              DECEMBER 31,             1993 (DATE OF
                                                      -----------------------------    INCEPTION) TO
                                                           1995           1994       DECEMBER 31, 1993
                                                      --------------  -------------  ------------------
<S>                                                   <C>             <C>            <C>
Net loss per share..................................  $         0.13  $        0.01    $     --
                                                      --------------  -------------  ------------------
                                                      --------------  -------------  ------------------
Weighted average number shares of Common Stock
 outstanding........................................      10,013,055      9,178,633         5,006,527
                                                      --------------  -------------  ------------------
                                                      --------------  -------------  ------------------
</TABLE>
 
    The  Securities and  Exchange Commission requires  that potentially dilutive
instruments issued within one year prior  to a proposed initial public  offering
at  exercise prices below the expected  initial public offering price be treated
as outstanding for all periods presented. Accordingly, an additional  21,638,550
shares  are reflected in the  weighted average number of  shares of Common Stock
outstanding in computing the unaudited pro forma net loss per share for the year
ended December 31, 1995.
 
USE OF ESTIMATES
 
    The  preparation  of  financial  statements  in  conformity  with  generally
accepted  accounting  principles  requires  management  to  make  estimates  and
assumptions that  affect the  reported  amounts of  assets and  liabilities  and
disclosure  of contingent assets and liabilities as of the date of the financial
statements and  the  reported  amounts  of  revenues  and  expenses  during  the
reporting period. Actual results could differ from those estimates.
 
4.  NOTE RECEIVABLE FROM TELECOM AND CONVERTIBLE NOTES PAYABLE TO ADVENT:
    The   Company,  Telecom   and  several   entities  affiliated   with  Advent
International Corp. (collectively, "Advent"), entered into a securities purchase
agreement (the "Advent Purchase Agreement") dated November 13, 1995 under  which
Advent agreed to acquire a 10% interest in the combined entities of the Company,
Telecom  and certain specified affiliates. Pending  the merger of these entities
(see Note 2), the Company issued  promissory notes (the "Advent Notes") with  an
aggregate principal amount of $4,950,000 and one share of the Company's Series A
Redeemable Preferred Stock in exchange for $5,000,000 in cash.
 
    The  Advent  Notes carried  interest at  a rate  of 10%  per annum  and were
payable on demand at any  time on or after May  13, 1997. The Advent Notes  were
collateralized  by certain assets  of the Company and  Telecom. The Advent Notes
were convertible into that number of shares of preferred stock which represented
in the aggregate at least 10% of the fully diluted capital stock of the combined
entities described  above, as  defined  in the  Advent Purchase  Agreement.  The
Advent  Notes were convertible either (i) immediately prior to an initial public
offering with  aggregate gross  proceeds  of at  least  $10,000,000 or  (ii)  at
Advent's election.
 
    At December 31, 1995, the Company accrued interest expense of $66,542 on the
Advent   Notes,  which  has  been  included  in  accounts  payable  and  accrued
liabilities.
 
    On November  13, 1995,  the gross  proceeds of  $5,000,000 received  by  the
Company  from Advent  were transferred  to Telecom in  exchange for  a note with
terms equivalent to  the terms of  the Advent  Notes. On February  2, 1996,  the
Company,    Telecom   and   Advent   entered    into   an   exchange   agreement
 
                                      F-17
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
4.  NOTE RECEIVABLE FROM TELECOM AND CONVERTIBLE NOTES PAYABLE TO
ADVENT, CONTINUED:
under which the Advent Notes, including  accrued interest, and the one share  of
ART  Series  A Redeemable  Preferred  Stock held  by  Advent were  exchanged for
232,826 shares  of  Series  E preferred  stock  of  Telecom, and  the  note  was
canceled.  As a result,  the Advent Notes  were canceled and  Telecom became the
owner of the one share of the ART Series A Redeemable Preferred Stock.
 
5.  EQUITY INVESTMENTS:
 
A -- INVESTMENT IN ART WEST JOINT VENTURE
 
    On April 4,  1995, the Company  entered into an  agreement with Extended  to
form  ART West, a jointly controlled general partnership established to acquire,
develop, and operate  radio systems  using 38  GHz licenses  in certain  western
states  of the U.S. The ART West  joint venture will continue until December 31,
2055, unless  terminated earlier.  The  Company's initial  capital  contribution
consisted  of $255,000 in cash, FCC licenses  and related assets with a carrying
value of  approximately  $5,000, and  73,625  shares  of Common  Stock  of  ART.
Extended's  initial capital  contribution consisted  of $5,000  in cash  and FCC
licenses. The combined  systems are  collectively referred  to as  the ART  West
Systems.  Additionally, Extended received distributions  of $250,000 in cash and
the 73,625 shares of Common Stock contributed  by the Company to ART West. As  a
result  of these contributions and distributions, the Company and Extended share
equally in  the partnership  interests of  ART West.  The Company  recorded  its
investment  in ART West in  the amount of $285,000.  The excess of the Company's
share of  the underlying  net assets  of ART  West over  the Company's  recorded
investment will be amortized over the life of the ART West Systems.
 
    On  October 1, 1994,  ART entered into an  exclusive services agreement with
Extended, whereby  ART  is  responsible  for  the  construction,  operation  and
management  of Extended's telecommunications systems.  The term of the Agreement
is for  five years.  In connection  with  the formation  of ART  West,  Extended
assigned  its interest in the services agreement to ART West. Under the terms of
the services  agreement,  ART will  incur  all  costs and  expenses  related  to
construction, operation and management of the systems. As compensation, ART will
receive  all revenues generated  by the systems  after deducting certain related
direct expenses, less 45%  which is to  be paid to ART  West. ART's interest  in
this service agreement was subsequently assigned to Telecom (Note 6). An officer
of ART is also the President and a shareholder of Extended.
 
B -- ART WEST JOINT VENTURE ACQUISITION AND MANAGEMENT AGREEMENTS
 
    In  June  1996,  the  Company agreed  to  acquire  Extended's  50% ownership
interest in ART West for $6,000,000  in cash upon consummation of public  equity
and  debt offerings with aggregate net proceeds of $125.0 million to the Company
and receipt of FCC  approval. In addition, the  Company entered into a  ten-year
management  agreement  which,  effective  June 1,  1996,  replaces  the services
agreement referred to above  with an arrangement whereby  the Company agrees  to
construct, operate and manage the ART West Systems in exchange for a license fee
equal to 10% of recurring operating revenues.
 
C -- INVESTMENT IN TELECOM
 
    The Company acquired 4,420,000 shares of Class A common stock of Telecom, or
34%  of the outstanding  and issued shares, for  cash of $340  (see Note 2). The
Company also recorded $802,002 as an  investment in Telecom based upon the  fair
value  of  Escrow  Shares released  in  1995 (see  Note  2). The  excess  of the
Company's share  of the  underlying net  assets of  Telecom over  the  Company's
recorded  investment  will  be  amortized  over  the  estimated  useful  life of
Telecom's FCC licenses.
 
                                      F-18
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
5.  EQUITY INVESTMENTS, CONTINUED:
    The Company recognizes its proportionate share  of the losses of Telecom  in
excess of its investment to the extent of its funding and financial commitments.
During 1995, the Company recognized its proportionate share of Telecom's loss in
the  amount of  $1,013,885. Summarized financial  information for  Telecom as of
December 31, 1995 and for the period from March 28, 1995 (date of inception)  to
December 31, 1995 is as follows:
<TABLE>
<CAPTION>
                                                                                          DECEMBER 31,
                                                                                              1995
                                                                                         ---------------
<S>                                                                                      <C>
Total current assets...................................................................   $   1,418,590
Property and equipment, net............................................................       3,579,838
FCC licenses...........................................................................       4,226,821
Other assets...........................................................................         605,366
                                                                                         ---------------
  Total assets.........................................................................   $   9,830,615
                                                                                         ---------------
                                                                                         ---------------
Total current liabilities..............................................................   $   3,450,537
Note payable to EMI....................................................................       1,500,000
Note payable to ART....................................................................       5,000,000
Total stockholders' deficit............................................................        (119,922)
                                                                                         ---------------
  Total liabilities and stockholders' deficit..........................................   $   9,830,615
                                                                                         ---------------
                                                                                         ---------------
 
<CAPTION>
 
                                                                                         MARCH 28, 1995
                                                                                            (DATE OF
                                                                                          INCEPTION) TO
                                                                                          DECEMBER 31,
                                                                                              1995
                                                                                         ---------------
<S>                                                                                      <C>
Operating revenue......................................................................   $       5,793
Expenses...............................................................................       2,986,866
                                                                                         ---------------
Net loss...............................................................................   $   2,981,073
                                                                                         ---------------
                                                                                         ---------------
</TABLE>
 
6.  TELECOM SERVICES AGREEMENT:
    The  Company entered into an exclusive  Services Agreement with Telecom, for
the construction,  operation and  management  of the  FCC licenses  and  related
telecommunications  systems that are owned by ART  or for which ART has existing
services agreements. Under the Services Agreement, Telecom will incur all  costs
and  expenses related to construction, operation  and management of the systems.
As compensation,  Telecom will  receive all  revenues generated  by the  systems
after deducting certain related direct expenses, less 25% which is to be paid to
the Company. The Services Agreement is for a period of 20 years.
 
    Through  this Services Agreement, the Company  has assigned its interests in
other similar services agreements with ART West  (see Note 5) and DCT (see  Note
7). There have been no services provided through December 31, 1995 on any of the
services agreements.
 
7.  DCT AGREEMENTS:
 
SYSTEM PURCHASE AGREEMENT
 
    On  September  1,  1994, the  Company  entered  into an  agreement  with DCT
Communications, Inc.  ("DCT"),  in which  the  Company obtained  the  option  to
purchase  certain FCC licenses (the "Systems")  from DCT for $500,000 and shares
of ART Common Stock that represent 5% of its fully diluted equity as of the date
of transfer. The option is exercisable at  any time after December 31, 1995  and
up to the date
 
                                      F-19
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
7.  DCT AGREEMENTS, CONTINUED:
that  is three years after the FCC issues DCT's first license. At any time after
December 31, 1995,  DCT may require  that the Company  purchase the Systems  for
$50,000, plus reimbursement of certain costs defined in the agreement.
 
SERVICES AGREEMENT
 
    On  September  1,  1994,  the Company  entered  into  an  exclusive services
agreement with  DCT whereby  the Company  is responsible  for the  construction,
operation and management of DCT's Systems. The term of the Agreement is for five
years.  Under the terms  of the services  agreement, the Company  will incur all
costs and  expenses related  to construction,  operation and  management of  the
systems. As compensation, the Company will receive all revenues generated by the
systems after deducting certain related direct expenses, less 45% which is to be
paid to DCT.
 
CONSULTING AND LOAN AGREEMENT
 
    On  March 13, 1995, the Company entered into a consulting and loan agreement
(the "Consulting and  Loan Agreement"). Under  the terms of  the Consulting  and
Loan  Agreement, DCT agreed to  loan the Company $8,500,  bearing interest at 9%
per annum. The loan, including interest of $431, was due and paid on August  31,
1995.
 
DCT PRELIMINARY AGREEMENT
 
    On  April  25, 1996,  the  Company and  Telecom  entered into  a preliminary
agreement with DCT to acquire DCT's  interest in certain FCC authorizations  and
licenses  in exchange for $3.6  million in cash, subject  to the completion of a
definitive purchase agreement  and services agreement.  The definitive  purchase
agreement  will supersede and replace all  other existing agreements between DCT
and the Company. The  definitive purchase agreement must  be signed by June  28,
1996 and the closing of the transaction is subject to FCC approval.
 
8.  COMMITMENTS:
 
ACQUISITION OF ASSETS OF EMI
 
    On  April 4, 1995, the Company entered into a purchase option agreement with
EMI to acquire  EMI's interest  in certain 38  GHz radio  spectrum licenses  and
related  assets in the northeastern United States (the "EMI Assets") in exchange
for $3,000,000 in cash  and a three year  non-negotiable promissory note in  the
amount  of  $1,500,000. Pursuant  to  the Purchase  Agreement  (see Note  1), in
November, 1995,  the  Company assigned  its  rights and  obligations  under  the
purchase option agreement to Telecom. The FCC subsequently approved the transfer
of  the EMI licenses  and Telecom directly  acquired the EMI  Assets in November
1995. The Company  has also  issued a  guarantee to  EMI of  the obligations  of
Telecom under the promissory note.
 
TELECOM ONE OPTION
 
    On  May 25,  1995, the  Company entered into  an agreement  with TeleCom One
Incorporated ("TeleCom One") whereby the Company agreed to assist TeleCom One in
its applications for certain FCC  licenses (the "TeleCom One Agreement").  Under
the  terms  of the  TeleCom One  Agreement,  in exchange  for its  services, the
Company acquired options to purchase a 49% interest in each of the FCC  licenses
obtained  by TeleCom One at a purchase price of $.0133 per person covered by the
geographic license area. The  term of the TeleCom  One Agreement is five  years.
The Company has not exercised any of its options.
 
                                      F-20
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
EMPLOYMENT AND CONSULTING AGREEMENTS
 
    On  May 8,  1995, the  Company and  Telecom jointly  entered into consulting
agreements with two executive officers of the Company and Telecom, effective  as
of  January  1, 1995  and continuing  for a  term of  three years,  with minimum
payments aggregating approximately $170,000 annually. The costs associated  with
these  contracts have been recorded by Telecom  and no amounts have been charged
to the Company.
 
    On December  16, 1995,  one of  the executive  officers of  the Company  and
Telecom, previously a party to one of the consulting agreements described above,
entered into a full-time employment agreement. The employment agreement is for a
three-year term with an annual salary of $250,000 in the first year, $275,000 in
the  second year  and $300,000  in the  third year.  In addition,  the agreement
provides for a cash bonus of up to $100,000 for each year based upon achievement
of specific performance objectives. The costs associated with this contract have
been recorded by Telecom and no amounts have been charged to the Company.
 
    On July  11,  1995, the  Company  and  Telecom entered  into  an  employment
agreement,  as  amended January  8, 1996,  with  an officer  of the  Company and
Telecom. The  term of  the  agreement is  three years  at  an annual  salary  of
$160,000  in the  first year, $200,000  in the  second year and  $240,000 in the
third year. Options to purchase shares  of Telecom common stock were awarded  to
this officer equivalent to 2.5% of the outstanding capital stock of Telecom. The
agreement also provides for an engagement bonus of $17,000 upon execution of the
agreement  and  a  cash  bonus  of  up to  $100,000  for  each  year  based upon
achievement of specific performance objectives.  The costs associated with  this
contract  have been recorded by Telecom and  no amounts have been charged to the
Company.
 
    The Company and Telecom  have also entered  into employment agreements  with
other executives that provide for annual base salaries and cash bonuses based on
achievement  of specific performance goals. These contracts may be terminated at
any time by management.
 
FINANCING AGREEMENT
 
    During 1994, the Company entered  into an agreement with Southeast  Research
Partners  ("SERP"), a subsidiary  of Josephthal, Lyons &  Ross, a Florida broker
dealer, to procure additional financing for the Company in exchange for cash and
options to purchase capital stock of the Company. Pursuant to a letter agreement
dated July  12,  1995,  the Company  and  Telecom  paid SERP  $245,000  and  the
shareholders  of the Company granted SERP  options to purchase 313,644 shares of
the Company's  Common  Stock directly  from  the Founding  Stockholders  for  an
aggregate consideration of $210,000.
 
    As  of December 31, 1995, the Company and Telecom have accounted for the fee
of $245,000 as  part of  the financing  provided by  Landover and,  accordingly,
$175,000  has been recorded as deferred  financing costs related to the issuance
of the Advent Notes (See Note 4) and the balance of $70,000 has been  recognized
as  an offset  against the  proceeds from the  issuance of  the serial preferred
stock of Telecom.
 
9.  COMMON STOCK:
    On April 5, 1994, the Board of  Directors authorized a 5 for 1 stock  split.
Subsequently,  on April  5, 1995, the  Board of  Directors authorized a  1 for 5
reverse stock split and simultaneously issued an additional 4,049,398 shares  of
Common Stock.
 
    On  May 30, 1996, the Board of  Directors authorized a 29,450.16 for 1 stock
split, increased the number of authorized  shares of Preferred Stock and  Common
Stock to 10,000,000 and 100,000,000,
 
                                      F-21
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
9.  COMMON STOCK, CONTINUED:
respectively,  and  changed the  par value  per  share from  $.01 to  $.001. All
references to the number of shares and per share amounts of the Company's Common
Stock in the accompanying financial statements have been restated to reflect the
five for one stock split, the one for five reverse stock split and the 29,450.16
for 1 stock split, unless otherwise  indicated. All par value amounts have  been
restated to reflect the change in par value to $.001 per share.
 
10. INCOME TAXES:
    As  of  December 31,  1995  and 1994,  the  Company has  net  operating loss
carry-forwards for income tax purposes  of approximately $390,000 and  $134,000,
respectively,  which will expire  between 2008 and 2010.  Deferred tax assets of
approximately $130,000 and $46,000 at December 31, 1995 and 1994,  respectively,
principally  comprised of such net operating  tax loss carry-forwards, have been
offset in full by a valuation allowance.
 
11. RELATED PARTY TRANSACTIONS:
    On May 8, 1995, the Company and Telecom entered into a consulting  agreement
with  Landover as  a strategic and  financial consultant.  Telecom paid Landover
$70,000 for services under this agreement during 1995. The consulting  agreement
was terminated on November 13, 1995.
 
    On  November 13,  1995, the  Company and  Telecom entered  into a management
consulting agreement  with Landover  to  provide strategic  planning,  corporate
development and general management. Under the agreement, the Company and Telecom
will  pay Landover $35,000 per month for  an initial one year term, renewable by
the Company and Telecom for two additional one year terms. The aggregate expense
recognized by  Telecom under  this agreement  during 1995  amounted to  $70,000.
These  expenses have been recorded by Telecom  and no portion of such costs have
been charged  to the  Company. The  agreement also  provides that  in the  event
Landover  arranges financing, acquisitions or certain other transactions for the
Company and Telecom,  Landover will be  paid a fee  in accordance with  industry
standards.
 
    Pursuant  to the Purchase  Agreement, the Company  and Telecom paid Landover
$391,750 for expenses  in connection  with the Landover  Funding Commitment,  of
which  $250,000 has been capitalized as  deferred financing costs by the Company
and the balance of $141,750 has been charged to paid-in capital of Telecom.
 
    Telecom  has  funded  certain  expenses  and  investments  of  the  Company,
including  the Company's  investment in ART  West and payments  of financing and
other operating costs. The amounts funded by Telecom to date totaling  $805,803,
offset by accrued interest income of $67,123 related to the note receivable from
Telecom (see Note 4) have been included in the amount due to Telecom.
 
    In  1994,  the  Company shared  office  space with  a  law firm  in  which a
principal of the law firm was also one of the Founding Stockholders. The Company
paid rent in the amount of  $6,353 to the law firm  for the use of their  office
space.  The  law firm  also regularly  provides legal  services to  the Company.
During 1995  and  1994,  the  Company incurred  fees  of  $34,770  and  $74,550,
respectively, for such services.
 
                                      F-22
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
12. FAIR VALUES OF FINANCIAL INSTRUMENTS
    The  carrying amounts and fair values of the Company's financial instruments
at December 31 were as follows:
 
<TABLE>
<CAPTION>
                                                                          1995                      1994
                                                              ----------------------------  --------------------
                                                                CARRYING                    CARRYING     FAIR
                                                                 AMOUNT       FAIR VALUE     AMOUNT      VALUE
                                                              -------------  -------------  ---------  ---------
<S>                                                           <C>            <C>            <C>        <C>
Note receivable from Telecom................................  $   5,000,000  $   5,000,000     --         --
Notes payable...............................................      4,950,000      4,950,000  $  70,000  $  70,000
</TABLE>
 
    Note receivable from Telecom: The  carrying amounts reported in the  balance
sheet are a reasonable estimate of fair values.
 
    Notes   payable:  The  carrying  amounts   reported  in  the  balance  sheet
approximate fair values based upon  interest rates that are currently  available
to the Company for issuance of similar debt with similar terms and maturities.
 
                                      F-23
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                   UNAUDITED INTERIM CONDENSED BALANCE SHEETS
                         AS OF MARCH 31, 1996 AND 1995
 
<TABLE>
<CAPTION>
                                                                                           1996           1995
                                                                                      --------------  ------------
<S>                                                                                   <C>             <C>
                                                      ASSETS
Current assets:
  Cash..............................................................................  $        5,970  $        255
                                                                                      --------------  ------------
      Total current assets..........................................................           5,970           255
Equity investments..................................................................       3,242,401
FCC licenses........................................................................           8,913
Property and equipment, net.........................................................           1,292         3,448
Other assets........................................................................          23,212        34,030
                                                                                      --------------  ------------
      Total assets..................................................................  $    3,281,788  $     37,733
                                                                                      --------------  ------------
                                                                                      --------------  ------------
 
                                  LIABILITIES AND STOCKHOLDERS' EQUITY (DEFICIT)
Current liabilities:
  Accounts payable and accrued liabilities..........................................  $        2,500  $      4,230
  Due to Telecom....................................................................         498,100
  Notes payable.....................................................................                       114,334
                                                                                      --------------  ------------
      Total current liabilities.....................................................         500,600       118,564
Redeemable Preferred Stock, $.01 par value; 1,000 shares authorized; 1 share issued
 and outstanding at March 31, 1996..................................................          44,930
                                                                                      --------------  ------------
Commitments and contingencies
 
Stockholders' equity (deficit):
  Common Stock, $.001 par value; 58,900,320 shares authorized; 10,013,055 and
   5,890,032 shares issued and outstanding..........................................          10,013         5,890
  Additional paid-in capital........................................................       7,783,889        90,246
  Deficit accumulated during the development stage..................................      (5,057,644)     (176,967)
                                                                                      --------------  ------------
      Total stockholders' equity (deficit)..........................................       2,736,258       (80,831)
                                                                                      --------------  ------------
        Total liabilities and stockholders' equity (deficit)........................  $    3,281,788  $     37,733
                                                                                      --------------  ------------
                                                                                      --------------  ------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-24
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
              UNAUDITED INTERIM CONDENSED STATEMENTS OF OPERATIONS
               FOR THE THREE MONTHS ENDED MARCH 31, 1996 AND 1995
 
<TABLE>
<CAPTION>
                                                                                               1996         1995
                                                                                           -------------  ---------
<S>                                                                                        <C>            <C>
Expenses:
  General and administrative.............................................................  $      24,939  $  40,878
  Depreciation and amortization..........................................................          2,595
  Interest expense, net..................................................................            671        875
                                                                                           -------------  ---------
      Total expenses.....................................................................         28,205     41,753
Equity loss on investment in Telecom.....................................................      3,626,570
                                                                                           -------------  ---------
      Net loss...........................................................................  $   3,654,775  $  41,753
                                                                                           -------------  ---------
                                                                                           -------------  ---------
Pro forma net loss per share.............................................................  $        0.12
                                                                                           -------------
                                                                                           -------------
Pro forma weighted average number of shares of Common Stock outstanding (unaudited)......     31,651,605
                                                                                           -------------
                                                                                           -------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-25
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
              UNAUDITED INTERIM CONDENSED STATEMENTS OF CASH FLOWS
               FOR THE THREE MONTHS ENDED MARCH 31, 1996 AND 1995
 
<TABLE>
<CAPTION>
                                                                                                1996          1995
                                                                                           --------------  ----------
<S>                                                                                        <C>             <C>
Cash flows from operating activities:
  Net loss...............................................................................  $   (3,654,775) $  (41,753)
  Adjustments to reconcile net loss to net cash used in operating activities:
    Non-cash interest expense............................................................          69,347
    Depreciation and amortization........................................................           2,595
    Equity loss on investment in Telecom.................................................       3,626,570
  Changes in operating assets and liabilities:
    Accounts payable and accrued liabilities.............................................         (43,836)     (7,459)
                                                                                           --------------  ----------
      Net cash used in operating activities..............................................             (99)    (49,212)
                                                                                           --------------  ----------
Cash flows from financing activities:
  Proceeds from loan and note payable....................................................                      44,334
                                                                                           --------------  ----------
      Net cash provided by financing activities..........................................        --            44,334
                                                                                           --------------  ----------
      Net decrease in cash...............................................................             (99)     (4,878)
Cash, beginning of period................................................................           6,069       5,133
                                                                                           --------------  ----------
Cash, end of period......................................................................  $        5,970  $      255
                                                                                           --------------  ----------
                                                                                           --------------  ----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-26
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
           NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION:
 
THE COMPANY
 
    Advanced  Radio  Technologies  Corporation  ("ART"  or  the  "Company")  was
organized as a  Delaware corporation on  August 23, 1993,  to provide  broadband
wireless  digital telecommunications services to the domestic telecommunications
market.
 
BASIS OF PRESENTATION
 
    The unaudited interim  condensed financial statements  included herein  have
been  prepared by the Company. The  foregoing statements contain all adjustments
(consisting only of normal recurring adjustments)  which are, in the opinion  of
the  Company's management, necessary to present fairly the financial position of
the Company as of March 31, 1996 and 1995, and the results of its operations and
its cash flows for the three months ended March 31, 1996 and 1995.
 
    Certain information and footnote disclosures normally included in  financial
statements  have been condensed or omitted pursuant to the rules and regulations
of the Securities and Exchange Commission. These condensed financial  statements
should  be  read in  conjunction with  the Company's  December 31,  1995 audited
financial statements and notes thereto.
 
    The financial statements have  been prepared on the  going concern basis  of
accounting,   which  contemplates  realization  of  assets  and  liquidation  of
liabilities in  the  ordinary  course  of  business.  The  Company  has  limited
financial  resources,  incurred operating  losses since  inception and  does not
expect to recognize material  operating revenues until  the commencement of  its
commercial  services, which is anticipated to  occur in fiscal 1996. The Company
estimates that  revenues in  1996 will  not be  sufficient to  fund its  initial
operating  expenses  and  other  working  capital  needs,  including consulting,
service and purchase commitments. The Company's continued funding of its initial
operating  expenses,  working  capital  needs  and  contractual  commitments  is
dependent  upon  its  ability to  raise  additional financing.  The  Company and
Advanced Radio  Telecom Corp.  ("Telecom")  (see Note  2) have  engaged  various
investment  bankers to assist them in  raising financing through a public equity
and debt offering. There can be no  assurance that the Company and Telecom  will
be  successful in their effort to raise additional financing through this public
offering or, if available, that the Company  and Telecom will be able to  obtain
it  on  acceptable terms.  These conditions  raise  substantial doubt  about the
Company's ability to continue  as a going concern.  The financial statements  do
not  include  any  adjustments  that  might result  from  the  outcome  of these
uncertainties.
 
2.  STOCKHOLDERS' AGREEMENT:
    On February 2, 1996, the Company, Telecom and their respective  shareholders
agreed  to an amendment and restatement of the Stockholders' Agreement providing
for (i) termination effective  on the closing of  a public share offering,  (ii)
amendment and restatement of the Certificate of Incorporation and reorganization
of  the capital structure of Telecom; (iii) the exchange of the Advent Notes and
one share of  ART Series A  Redeemable Preferred  Stock for shares  of Series  E
preferred  stock  of  Telecom;  (iv)  revision  of  provisions  for  election of
directors;  (v)  amendment   and  restatement  of   ART's  registration   rights
agreements;  (vi) release  of shares  escrowed in  connection with  the original
Stockholders' Agreement; and (vii) approval of the definitive merger agreement.
 
    The definitive merger  agreement, as entered  into on February  2, 1996  and
subsequently  restated and  amended on June  26, 1996  (the "Merger Agreement"),
provides for the merger of a newly-formed wholly owned subsidiary of the Company
("Merger Sub")  into  Telecom  (the "Merger")  subject  to  certain  conditions,
including  the receipt  of FCC approval.  Prior to the  Merger, each outstanding
share of
 
                                      F-27
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
      NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS, CONTINUED
 
2.  STOCKHOLDERS' AGREEMENT: CONTINUED:
Telecom's serial preferred stock will be  converted into 13 shares of  Telecom's
common  stock. In the Merger  each outstanding share of  common stock of Telecom
will be exchanged for the right to  receive an equal number of shares of  Common
Stock of the Company. As a result, Telecom will become a wholly owned subsidiary
of  the  Company.  The Merger  Agreement  provides  that if  the  Merger  is not
consummated by May 13, 1997, the shares  of Telecom's common stock owned by  the
Company  will be  surrendered to  Telecom and  the Services  Agreement is  to be
revised to, among other revisions, extend the term to 40 years and provide for a
proportionate participation by the Company's stockholders in any dividends  paid
by  Telecom or the proceeds from any  sale of Telecom. The Merger Agreement also
provides for the  assignment of Telecom's  interests in all  of its  agreements,
including  the  various  services agreements,  employment  agreements, equipment
purchase agreements and  purchase option  agreements, to  the Company.  Further,
upon  the Merger, the holders of warrants  to purchase an aggregate of 2,302,136
shares of Telecom common stock will be entitled to purchase an equivalent number
of shares of Common Stock on the same terms. Employee stock options to  purchase
1,664,732  shares of Telecom's common stock will be converted into similar stock
options of the Company.
 
3.  NET LOSS PER SHARE
    Historical net loss per share is computed  based on the loss for the  period
divided  by the  weighted average number  of shares of  Common Stock outstanding
during the period. Historical net loss per share and the weighted average number
of shares of Common Stock outstanding are as follows:
 
<TABLE>
<CAPTION>
                                                                   FOR THE THREE MONTHS ENDED
                                                                           MARCH 31,
                                                                  ----------------------------
                                                                      1996           1995
                                                                  -------------  -------------
<S>                                                               <C>            <C>
Net loss per share..............................................  $         .37  $    --
                                                                  -------------  -------------
                                                                  -------------  -------------
Weighted average number shares of Common Stock outstanding......     10,013,055     10,013,055
                                                                  -------------  -------------
                                                                  -------------  -------------
</TABLE>
 
    The Securities and  Exchange Commission requires  that potentially  dilutive
instruments  issued within one year prior  to a proposed initial public offering
at exercise prices below the expected  initial public offering price be  treated
as  outstanding for all periods presented. Accordingly, an additional 21,638,550
shares are reflected in  the weighted average number  of shares of Common  Stock
outstanding  in computing  the unaudited  pro forma net  loss per  share for the
three months ended March 31, 1996.
 
4.  NOTES RECEIVABLE FROM TELECOM AND CONVERTIBLE NOTE PAYABLE TO ADVENT:
    On February  2,  1996, the  Company,  Telecom  and Advent  entered  into  an
exchange agreement under which the Advent Notes, including accrued interest, and
the  one share of ART's Series A  Redeemable Preferred Stock held by Advent were
exchanged for 232,826  shares of Series  E preferred stock  of Telecom, and  the
notes  payable  by the  Company to  Advent and  by Telecom  to the  Company were
canceled, the related interest forgiven, and Telecom became the owner of the one
share of ART Series A Redeemable Preferred Stock.
 
5.  INVESTMENTS:
    The Company accounts for its 50% interest in the ART West joint venture  and
its 34% interest in Telecom under the equity method.
 
    In  June  1996,  the  Company agreed  to  acquire  Extended's  50% ownership
interest in ART West for $6 million  in cash upon consummation of public  equity
and  debt offerings with aggregate  net proceeds of $125  million to the Company
and  receipt  of  FCC  approval.  In  addition,  the  Company  entered  into   a
 
                                      F-28
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
      NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS, CONTINUED
 
5.  INVESTMENTS: CONTINUED:
ten-year  management  agreement  which,  effective June  1,  1996,  replaced the
services agreement with ART West with an arrangement whereby the Company  agrees
to construct, operate, and manage the ART West systems in exchange for a license
fee equal to 10% of recurring operating revenues.
 
    During 1995, the Company recorded $802,002 as an investment in Telecom based
upon  the fair value of Escrow Shares released  in 1995, the effect of which was
recognized as additional paid-in  capital in the Company.  On February 2,  1996,
the  Company recorded an  additional $6,795,514 based  on the fair  value of the
remaining Escrow Shares released, which was accounted for in the same manner.
 
    The Company recognizes its proportionate share  of the losses of Telecom  to
the  extent of its  investment, funding and  financial commitments. During 1996,
the Company has recognized its proportionate  share of the losses of Telecom  in
the amount of $3,626,570.
 
6.  COMMCOCCC ASSET ACQUISITION
    During July 1996, the Company entered into an agreement with CommcoCCC, Inc.
("CommcoCCC")   to  acquire  CommcoCCC's   interests  in  certain   38  GHz  FCC
authorizations (the "CommcoCCC Assets") in  exchange for 16.5 million shares  of
Common  Stock. The  acquisition of  the CommcoCCC  Assets is  subject to various
conditions including (i)  minimum population coverage  of the authorizations  of
the  Company and CommcoCCC, (ii) receipt of final FCC and other approvals, (iii)
receipt by CommcoCCC of an opinion as to the tax-free nature of the  transaction
(iv)  the accuracy of representations and warranties except for breaches that do
not have  in  the  aggregate  a  material adverse  effect,  (v)  no  pending  or
threatened  material  litigation, (vi)  consummation of  public equity  and debt
offerings  on  terms  reasonably  satisfactory  to  CommcoCCC  and  (vii)  other
customary  closing conditions.  Pending the  completion of  the acquisition, the
Company has agreed to construct, manage and operate the CommcoCCC Assets.
 
    The Company has given  a stockholder ("Commco LLC")  of CommcoCCC an  option
(the "Option") to purchase FCC authorizations in specified market areas in which
the  Company will  have more than  one authorization. The  Option is exercisable
only in the event that the  CommcoCCC Acquisition is consummated and Commco  LLC
receives  authorizations  pursuant to  pending  applications covering  a minimum
specified population  and expires  nine  months after  the consummation  of  the
Common  Stock Offering.  The price of  authorizations to be  purchased under the
Option is based upon a formula that  considers the market price of Common  Stock
on the date of exercise.
 
    In  connection with the  agreement to acquire  the CommcoCCC Assets, certain
stockholders of CommcoCCC loaned the Company $3 million in cash in exchange  for
notes  due September 30, 1996 (the "CommcoCCC Notes") with interest at the prime
rate and received three year warrants to purchase 50,000 shares of Common  Stock
at  a price of $15  per share. The CommcoCCC Notes  are collateralized by all of
the assets of the Company and, if not paid in full when due, the unpaid  balance
is  convertible into Common Stock,  at the option of  each holder, at stipulated
per share prices based upon the timing of exercise.
 
7.  RELATED PARTY TRANSACTIONS
    Telecom has funded the payment of certain expenses of the Company, including
financing costs. The amounts  funded by Telecom during  the quarter ended  March
31,  1996 totaled $175,000.  The balance resulting  from the funding activities,
offset by  the  net  effect of  the  conversion  of the  Advent  Notes  and  the
cancellation  of the note receivable  from Telecom (Note 3),  is shown as due to
Telecom in the accompanying balance sheet.
 
                                      F-29
<PAGE>
                       REPORT OF INDEPENDENT ACCOUNTANTS
 
To the Board of Directors and Stockholders of
Advanced Radio Telecom Corp.:
 
    We  have audited  the accompanying balance  sheet of  Advanced Radio Telecom
Corp. (a development  stage company) as  of December 31,  1995, and the  related
statements  of operations, stockholders'  deficit and cash  flows for the period
from March 28, 1995  (date of inception) to  December 31, 1995. These  financial
statements   are   the   responsibility  of   the   Company's   management.  Our
responsibility is to express an opinion  on these financial statements based  on
our audit.
 
    We  conducted  our  audit  in accordance  with  generally  accepted auditing
standards. Those standards require that we plan and perform the audit to  obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also  includes
assessing  the  accounting principles  used  and significant  estimates  made by
management, as well as evaluating the overall financial statement  presentation.
We believe that our audit provides a reasonable basis for our opinion.
 
    In  our opinion, the financial statements  referred to above present fairly,
in all material respects, the financial position of Advanced Radio Telecom Corp.
as of December 31, 1995,  and the results of its  operations and its cash  flows
for  the period from March 28, 1995 (date of inception) to December 31, 1995, in
conformity with generally accepted accounting principles.
 
    The accompanying  financial  statements  have been  prepared  on  the  going
concern  basis  of  accounting,  which contemplates  realization  of  assets and
liquidation of liabilities in the ordinary  course of business. As described  in
Note  1, the Company has  a substantial working capital  deficit at December 31,
1995, has  incurred operating  losses since  inception and  does not  expect  to
generate significant operating revenues until fiscal 1996. The Company estimates
that  revenues  in 1996  will  not be  sufficient  to fund  its  initial capital
requirements, operating expenses and other  working capital needs. In  addition,
as  set  forth  in  Notes  8  and  2,  the  Company  has  significant  financial
commitments.  The   Company's  continued   funding   of  its   initial   capital
requirements,   operating  expenses,  working   capital  needs  and  contractual
commitments is  dependent  upon  its  ability  to  raise  additional  financing.
Management's  plans in  this regard  are discussed  in Note  1. These conditions
raise substantial  doubt about  the Company's  ability to  continue as  a  going
concern.  The financial  statements do  not include  any adjustments  that might
result from the outcome of these uncertainties.
 
                                          COOPERS & LYBRAND L.L.P.
 
New York, New York
April 26, 1996, except for Note 2B
as to which the date is June 26, 1996
 
                                      F-30
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                                 BALANCE SHEET
                               DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
                                           ASSETS
<S>                                                                              <C>
Current assets:
  Cash and cash equivalents....................................................  $   627,585
  Due from ART (Note 12).......................................................      738,680
  Other current assets.........................................................       52,325
                                                                                 -----------
    Total current assets.......................................................    1,418,590
Property and equipment, net (Note 5)...........................................    3,579,838
FCC licenses (Note 4)..........................................................    4,226,821
Equipment and other deposits (Note 8)..........................................      284,012
Deferred financing costs.......................................................      321,354
                                                                                 -----------
      Total assets.............................................................  $ 9,830,615
                                                                                 -----------
                                                                                 -----------
 
                           LIABILITIES AND STOCKHOLDERS' DEFICIT
Current liabilities:
  Accounts payable and accrued liabilities (Note 6)............................  $ 3,450,537
                                                                                 -----------
      Total current liabilities................................................    3,450,537
Note payable to ART (Note 7)...................................................    5,000,000
Note payable to EMI (Note 4)...................................................    1,500,000
                                                                                 -----------
      Total liabilities........................................................    9,950,537
                                                                                 -----------
Commitments and contingencies (Notes 1, 8, 12 and 14)
Stockholders' deficit (Note 9):
  Serial preferred stock, $.001 par value, 488,492 shares issued and
   outstanding.................................................................          488
  Class A common stock, $.001 par value, 7,779,135 shares issued and
   outstanding.................................................................        7,779
  Class B common stock, $.001 par value, 7,512,076 shares issued and
   outstanding.................................................................        7,512
  Additional paid-in capital...................................................    2,845,372
  Deficit accumulated during the development stage.............................   (2,981,073)
                                                                                 -----------
      Total stockholders' deficit..............................................     (119,922)
                                                                                 -----------
        Total liabilities and stockholders' deficit............................  $ 9,830,615
                                                                                 -----------
                                                                                 -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-31
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENT OF OPERATIONS
             FOR THE PERIOD FROM MARCH 28, 1995 (DATE OF INCEPTION)
                              TO DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
Operating revenue..............................................................  $    5,793
<S>                                                                              <C>
                                                                                 ----------
Expenses:
  General and administrative expenses (Notes 8, 9 and 10)......................   2,706,336
  Market development expenses..................................................     191,693
  Depreciation and amortization................................................       5,306
  Interest expense, net (Notes 4 and 7)........................................      83,531
                                                                                 ----------
    Total expenses.............................................................   2,986,866
                                                                                 ----------
      Net loss.................................................................  $2,981,073
                                                                                 ----------
                                                                                 ----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-32
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                       STATEMENT OF STOCKHOLDERS' DEFICIT
             FOR THE PERIOD FROM MARCH 28, 1995 (DATE OF INCEPTION)
                              TO DECEMBER 31, 1995
<TABLE>
<CAPTION>
                                        COMMON STOCK                             PREFERRED STOCK
                                    --------------------  -------------------------------------------------------------
SHARES                               CLASS A    CLASS B    SERIES A     SERIES B     SERIES C     SERIES D      TOTAL
- ----------------------------------  ---------  ---------  -----------  -----------  -----------  -----------  ---------
<S>                                 <C>        <C>        <C>          <C>          <C>          <C>          <C>
Issuance of common stock to ART
 for cash.........................  4,420,000
Issuance of common stock to
 Landover and affiliates for
 cash.............................    260,000  8,320,000
Issuance of preferred stock to
 limited partnerships affiliated
 with Landover for cash:
  Series A........................                           332,091                                            332,091
  Series B........................                                         82,318                                82,318
  Series C........................                                                       5,402                    5,402
Issuance of Series D preferred
 stock for cash...................                                                                   61,640      61,640
Shares issued to reflect
 anti-dilution adjustments........  3,099,135                  2,852        4,189                                 7,041
Redemption of common stock from
 Landover.........................              (807,924)
                                    ---------  ---------  -----------  -----------       -----   -----------  ---------
Balance at December 31, 1995......  7,779,135  7,512,076     334,943       86,507        5,402       61,640     488,492
                                    ---------  ---------  -----------  -----------       -----   -----------  ---------
                                    ---------  ---------  -----------  -----------       -----   -----------  ---------
 
<CAPTION>
SHARES
- ----------------------------------
<S>                                 <C>            <C>              <C>
Issuance of common stock to ART
 for cash.........................
Issuance of common stock to
 Landover and affiliates for
 cash.............................
Issuance of preferred stock to
 limited partnerships affiliated
 with Landover for cash:
  Series A........................
  Series B........................
  Series C........................
Issuance of Series D preferred
 stock for cash...................
Shares issued to reflect
 anti-dilution adjustments........
Redemption of common stock from
 Landover.........................
Balance at December 31, 1995......
</TABLE>
<TABLE>
<CAPTION>
                                                                               PAR VALUE
                                    -----------------------------------------------------------------------------------------------
                                          COMMON STOCK                                   PREFERRED STOCK
                                    ------------------------  ---------------------------------------------------------------------
AMOUNTS                               CLASS A      CLASS B     SERIES A      SERIES B       SERIES C       SERIES D        TOTAL
- ----------------------------------  -----------  -----------  -----------  -------------  -------------  -------------  -----------
<S>                                 <C>          <C>          <C>          <C>            <C>            <C>            <C>
Issuance of common stock to ART
 for cash.........................   $   4,420
Issuance of common stock to
 Landover and affiliates for
 cash.............................         260    $   8,320
Issuance of preferred stock to
 limited partnerships affiliated
 with Landover for cash:
  Series A........................                             $     332                                                 $     332
  Series B........................                                           $      82                                          82
  Series C........................                                                          $       5                            5
Issuance of Series D preferred
 stock for cash...................                                                                         $      62            62
Shares issued to reflect
 anti-dilution adjustments........       3,099                         3             4                                           7
Serial preferred stock issuance
 costs............................
Redemption of common stock from
 Landover.........................                     (808)
Investment by ART as a result of
 the release of escrow shares.....
Accrued stock option
 compensation.....................
Net loss..........................
                                                                                                   --
                                    -----------  -----------       -----           ---                           ---         -----
Balance at December 31, 1995......   $   7,779    $   7,512    $     335     $      86      $       5      $      62     $     488
                                                                                                   --
                                                                                                   --
                                    -----------  -----------       -----           ---                           ---         -----
                                    -----------  -----------       -----           ---                           ---         -----
 
<CAPTION>
 
                                    ADDITIONAL
                                      PAID-IN     ACCUMULATED
AMOUNTS                               CAPITAL       DEFICIT        TOTAL
- ----------------------------------  -----------  -------------  -----------
<S>                                 <C>          <C>            <C>
Issuance of common stock to ART
 for cash.........................  $    (4,080)                $       340
Issuance of common stock to
 Landover and affiliates for
 cash.............................       (7,560)                      1,020
Issuance of preferred stock to
 limited partnerships affiliated
 with Landover for cash:
  Series A........................    1,006,268                   1,006,600
  Series B........................      880,618                     880,700
  Series C........................      112,695                     112,700
Issuance of Series D preferred
 stock for cash...................    1,999,938                   2,000,000
Shares issued to reflect
 anti-dilution adjustments........       (3,106)
Serial preferred stock issuance
 costs............................     (229,814)                   (229,814)
Redemption of common stock from
 Landover.........................   (1,999,192)                 (2,000,000)
Investment by ART as a result of
 the release of escrow shares.....      802,002                     802,002
Accrued stock option
 compensation.....................      287,603                     287,603
Net loss..........................                $(2,981,073)   (2,981,073)
 
                                    -----------  -------------  -----------
Balance at December 31, 1995......  $ 2,845,372   $(2,981,073)  $  (119,922)
 
                                    -----------  -------------  -----------
                                    -----------  -------------  -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-33
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENT OF CASH FLOWS
             FOR THE PERIOD FROM MARCH 28, 1995 (DATE OF INCEPTION)
                              TO DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
Cash flows from operating activities:
<S>                                                                              <C>
  Net loss.....................................................................  $(2,981,073)
  Adjustments to reconcile net loss to net cash used in operating activities:
    Depreciation and amortization..............................................        5,306
    Non-cash compensation expense..............................................    1,089,605
    Changes in operating assets and liabilities:
      Deposits.................................................................       (4,012)
      Accounts payable and accrued liabilities.................................      567,290
      Other current assets.....................................................      (52,325)
                                                                                 -----------
        Net cash used in operating activities..................................   (1,375,209)
                                                                                 -----------
Cash flows from investing activities:
  Acquisition of EMI licenses and property and equipment.......................   (3,023,971)
  Additions to property and equipment..........................................     (621,364)
  Advances to ART..............................................................     (738,680)
  Deposits on equipment........................................................     (280,000)
                                                                                 -----------
        Net cash used in investing activities..................................   (4,664,015)
                                                                                 -----------
Cash flows from financing activities:
  Proceeds from issuance of common stock.......................................        1,360
  Proceeds from issuance of serial preferred stock.............................    4,000,000
  Stock issuance costs.........................................................     (208,814)
  Proceeds from issuance of note payable to ART................................    5,000,000
  Advances from Landover and affiliates........................................      175,000
  Payments on advances from Landover and affiliates............................     (175,000)
  Redemption of common stock...................................................   (2,000,000)
  Additions to deferred financing costs........................................     (125,737)
                                                                                 -----------
        Net cash provided by financing activities..............................    6,666,809
                                                                                 -----------
          Net increase in cash and cash equivalents and balance at end of
           period..............................................................  $   627,585
                                                                                 -----------
                                                                                 -----------
Supplemental cash flow information:
  Non-cash financing and investing activities:
    Additions to property and equipment........................................  $ 2,666,630
    Issuance of promissory note payable to EMI.................................    1,500,000
    Accrued stock issuance costs...............................................       21,000
    Accrued deferred financing costs...........................................      195,617
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-34
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                         NOTES TO FINANCIAL STATEMENTS
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION:
 
THE COMPANY
 
    Advanced  Radio  Telecom Corp.  ("Telecom"),  formerly named  Advanced Radio
Technology Ltd., was incorporated in Delaware as a subsidiary of Advanced  Radio
Technologies  Corporation  ("ART") on  March 28,  1995,  to develop,  market and
deliver broadband  telecommunication  and information  services  throughout  the
United States. The Company's business objective is to organize and finance local
operating  facilities,  establish  strategic  alliances  with  other businesses,
acquire new  wireless  telecommunications  technologies,  and  market  broadband
wireless services to telecommunications service providers and end users.
 
    Telecom  was organized by ART and Landover Holdings Corporation ("Landover")
with one of its  initial objectives to  acquire certain 38  GHz licenses in  the
Northeastern  United States from EMI Communications  Corp. ("EMI") (see Note 4).
Under the terms of a purchase agreement between Telecom, Landover and ART  dated
April  21, 1995 (the  "Purchase Agreement"), Landover  was obligated to purchase
$7.0 million of securities of Telecom. Pursuant to the Purchase Agreement and  a
stockholders'  agreement between Telecom, ART  and their respective shareholders
dated May 8, 1995  (the "Stockholders' Agreement"), Telecom  and ART will  merge
once  approval from the  Federal Communications Commission  (the "FCC") has been
granted. On February 2, 1996, Telecom  and ART entered into a definitive  merger
agreement  (the "Merger  Agreement") providing for  a merger of  Telecom and ART
(the "Merger"). (See Note 2).
 
INITIAL CAPITALIZATION
 
    As its initial capitalization,  Telecom issued 8,320,000  shares of Class  B
common  stock  to  Landover  and  260,000 shares  of  Class  A  common  stock to
consultants to Landover, for aggregate cash consideration of $1,020. Such shares
of Class  B common  stock  and Class  A common  stock  represented 64%  and  2%,
respectively,  of the total  number of shares  of capital stock  of Telecom then
outstanding. Concurrently, Telecom  issued 4,420,000  shares of  Class A  common
stock,  representing 34% of the total number  of shares of capital stock, to ART
for $340. The number of shares of Class A and Class B common stock issued at the
initial capitalization of Telecom shown above give effect to the 13 for 1  stock
split  but are prior to  the issuance of anti-dilutive  shares (see Note 9). All
references to number  of shares of  common stock  and per share  amounts in  the
accompanying  financial statements and  footnotes have been  restated to reflect
the 13 for 1 stock split unless otherwise indicated.
 
    Under the  Purchase Agreement,  Landover agreed  to invest  or cause  to  be
invested  $7.0  million in  Telecom and  its  affiliates (the  "Landover Funding
Commitment"). In consideration for this $7.0 million investment, Telecom  agreed
to  issue  serial  preferred stock,  the  number  of shares  of  which  would be
designated by Landover.
 
BASIS OF PRESENTATION
 
    The financial statements have  been prepared on the  going concern basis  of
accounting,   which  contemplates  realization  of  assets  and  liquidation  of
liabilities in the ordinary  course of business.  Telecom has limited  financial
resources,  has incurred operating losses since inception and does not expect to
generate significant operating revenues until the commencement of its commercial
services, which is anticipated to occur  in fiscal 1996. Telecom estimates  that
revenues  in 1996 will not be sufficient  to fund its initial operating expenses
and other  working capital  needs, including  consulting, service  and  purchase
commitments  set  forth in  Notes  8 and  2.  Telecom's funding  of  its initial
operating  expenses,  working  capital  needs  and  contractual  commitments  is
dependent upon its ability to raise additional
 
                                      F-35
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION, CONTINUED:
financing.  Telecom and  ART have engaged  various investment  bankers to assist
them in raising  financing through  a public equity  and debt  offering of  ART.
There  can be no assurance that Telecom and ART will be successful in its effort
to raise additional  financing through  these offerings or,  if available,  that
Telecom  and ART will be able to obtain it on acceptable terms. These conditions
raise substantial doubt about Telecom's ability to continue as a going  concern.
The  financial statements do not include  any adjustments that might result from
the outcome of these uncertainties.
 
2.  REORGANIZATION AND PENDING MERGER WITH ART:
 
A -- MERGER
 
    Under the terms of the Purchase Agreement, Telecom and ART intend to operate
both companies as a single  enterprise and were committed  to merge if and  when
permitted  by the FCC.  Concurrent with the Purchase  Agreement, Telecom and ART
entered into an exclusive 20-year services agreement (the "Services  Agreement")
for  the construction, development and operation  of systems in ART markets (see
Note 8).
 
    On February 2, 1996, Telecom,  ART and their respective shareholders  agreed
to an amendment and restatement of the Stockholders' Agreement providing for (i)
termination  effective on the closing of a public share offering; (ii) amendment
and restatement of the  Certificate of Incorporation  and reorganization of  the
capital  structure of  Telecom (see  Note 9); (iii)  the exchange  of the Advent
Notes and one  share of ART  Series A  Redeemable Preferred Stock  for Series  E
preferred  stock  of  Telecom (see  Note  7);  (iv) revision  of  provisions for
election of directors; (v) amendment  and restatement of Telecom's  registration
rights  agreements;  (vi)  release of  shares  escrowed in  connection  with the
original  Stockholders'  Agreement  (see  Note  9);  and  (vii)  approval  of  a
definitive agreement to merge ART and Telecom (the "Reorganization").
 
B -- AMENDED MERGER
 
    The  definitive merger  agreement, as entered  into on February  2, 1996 and
subsequently restated and  amended on  June 26, 1996,  (the "Merger  Agreement")
provides  for  the  merger of  a  newly-formed  wholly owned  subsidiary  of ART
("Merger Sub")  into  Telecom  (the "Merger")  subject  to  certain  conditions,
including  the receipt  of FCC approval.  Prior to the  Merger, each outstanding
share of Telecom's serial  preferred stock will be  converted into 13 shares  of
Telecom's common stock. In the Merger, each outstanding share of common stock of
Telecom  will be exchanged for the right to receive an equal number of shares of
Common Stock of ART. As a result, Telecom will become a wholly owned  subsidiary
of  ART. The Merger Agreement provides that  if the Merger is not consummated by
May 13,  1997,  the shares  of  Telecom's common  stock  owned by  ART  will  be
surrendered  to Telecom and  the Services Agreement  is to be  revised to, among
other revisions, extend  the term to  40 years and  provide for a  proportionate
participation  by ART's  stockholders in  any dividends  paid by  Telecom or the
proceeds from any sale  of Telecom. The Merger  Agreement also provides for  the
assignment  of  Telecom's  interests in  all  of its  agreements,  including the
various  services   agreements,   employment  agreements,   equipment   purchase
agreements and purchase option agreements, to ART. Further, upon the Merger, the
holders  of warrants  to purchase  an aggregate  of 2,302,136  shares of Telecom
common stock will be entitled to purchase an equivalent number of shares of  ART
Common  Stock on  the same terms.  Employee stock options  to purchase 1,664,732
shares of Telecom's common stock will be converted into similar stock options of
ART.
 
                                      F-36
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SIGNIFICANT ACCOUNTING POLICIES:
 
DEVELOPMENT STAGE ENTERPRISE
 
    Telecom is  a  development  stage  enterprise as  defined  in  Statement  of
Financial  Accounting Standards No. 7,  "Accounting and Reporting by Development
Stage Enterprises." The  financial statements  have been prepared  on the  going
concern basis of accounting.
 
CASH AND CASH EQUIVALENTS
 
    Telecom  considers all  highly liquid  investments purchased  with remaining
maturities of three months or less to be cash equivalents.
 
PROPERTY AND EQUIPMENT
 
    Property and equipment is stated at cost. Depreciation and amortization  are
computed  using the straight-line method over  the estimated useful lives of the
related assets as  follows: wireless  transmission equipment -  5 years;  office
furniture and equipment - 3 years.
 
FCC LICENSES
 
    Telecom  has  obtained  radio  spectrum  rights  under  FCC  issued licenses
throughout the United States through the purchase of such rights held by  others
and  by petitioning the  FCC directly. Such  licenses are issued  for an initial
term of six  years and are  renewable subject to  review by the  FCC. The  costs
associated  with the acquisition of such  licenses are capitalized and amortized
on a straight-line basis  over a 40-year period  beginning upon commencement  of
operations  in the related market. The 40-year period is based upon management's
license renewal expectations.
 
RECOVERABILITY OF LONG-LIVED ASSETS
 
    The  recoverability   of  property   and  equipment   and  capitalized   FCC
authorizations  and  licenses is  dependent upon  the successful  development of
systems in  each of  the respective  markets, or  through sale  of such  assets.
Management  estimates that it will recover  the carrying amounts of those assets
from cash flow generated by the systems once they have been developed.  However,
it  is reasonably  possible that such  estimate will  change as a  result of the
failure to  develop the  FCC authorizations  on a  timely basis,  technological,
regulatory or other changes.
 
    Telecom's  policy is to assess annually any impairment in value based upon a
comparison of projected operating cash flows from each market over its  expected
period  of operation, on  an undiscounted basis,  to the carrying  amount of the
property and equipment, FCC licenses and other capitalized costs related to  the
market.
 
FINANCING COSTS
 
    Direct  costs associated  with obtaining  equity financing  are deferred and
charged to additional paid-in  capital as the related  funds are raised.  Direct
costs  associated with obtaining debt financing are deferred and amortized using
the effective interest rate method commencing when the related funds are raised.
Deferred costs associated with unsuccessful financings are charged to expense.
 
REVENUE RECOGNITION
 
    Revenue from  telecommunications services  are recognized  ratably over  the
period such services are provided.
 
                                      F-37
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
INCOME TAXES
 
    Telecom  accounts for income taxes under the liability method of accounting.
Under  the  liability  method,  deferred  taxes  are  determined  based  on  the
differences  between  the  financial  statement  and  tax  bases  of  assets and
liabilities at enacted tax rates in effect in the year in which the  differences
are  expected to reverse. Valuation  allowances are established, when necessary,
to reduce deferred tax assets to the amounts expected to be realized.
 
NET LOSS PER SHARE
 
    Net loss per share  of $0.19 is  computed based on the  loss for the  period
from  March 28,  1995 (date of  inception) to  December 31, 1995  divided by the
weighted average number of shares of common stock outstanding of 15,919,596.
 
USE OF ESTIMATES
 
    The  preparation  of  financial  statements  in  conformity  with  generally
accepted  accounting  principles  requires  management  to  make  estimates  and
assumptions that  affect the  reported  amounts of  assets and  liabilities  and
disclosure  of contingent assets and liabilities as of the date of the financial
statements and  the  reported  amounts  of  revenues  and  expenses  during  the
reporting period. Actual results could differ from those estimates.
 
CONCENTRATION OF CREDIT RISKS
 
    Telecom   places  its  temporary  cash   investments  with  major  financial
institutions. At December 31, 1995, the Company's temporary cash investments are
principally placed  in  one entity.  Other  financial instruments  which  expose
Telecom  to potential credit risk include the  amount due from ART (Note 12) and
deposits on equipment (Note 8).
 
4.  ACQUISITION OF ASSETS OF EMI:
    On April 4, 1995, ART entered into  a purchase option agreement with EMI  to
acquire  EMI's interest  in certain 38  GHz radio spectrum  licenses and related
assets in the Northeastern United States (the "EMI Assets") in exchange for $3.0
million in cash and a three year non-negotiable promissory note in the amount of
$1.5 million. Pursuant to the terms of the Purchase Agreement, in November 1995,
ART assigned its rights and obligations under the EMI purchase option  agreement
to  Telecom. The FCC subsequently approved the  transfer of the EMI licenses and
Telecom directly purchased the EMI Assets  in November 1995. The total  purchase
price, including expenses, was allocated to the acquired assets as follows:
 
<TABLE>
<S>                                                              <C>
Property and equipment.........................................  $  297,150
FCC licenses...................................................   4,226,821
                                                                 ----------
                                                                 $4,523,971
                                                                 ----------
                                                                 ----------
</TABLE>
 
    The  promissory note issued by Telecom, with  a guarantee by ART, is payable
in quarterly installments of  principal of $187,500  beginning January 1,  1997.
Interest is payable quarterly at a major commercial bank's prime rate plus 2.0%,
or 10.5% as of December 31, 1995.
 
    On  November 8, 1995 Landover advanced $175,000 to Telecom to fund a portion
of the initial payment  to EMI. Telecom  repaid such advance  later in the  same
month.
 
                                      F-38
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
5.  PROPERTY AND EQUIPMENT:
 
PROPERTY AND EQUIPMENT COMPRISE:
 
<TABLE>
<S>                                                              <C>
Wireless transmission equipment................................  $3,496,905
Office furniture and equipment.................................      88,239
                                                                 ----------
                                                                  3,585,144
Accumulated depreciation.......................................      (5,306)
                                                                 ----------
                                                                 $3,579,838
                                                                 ----------
                                                                 ----------
</TABLE>
 
    As  of December 31, 1995, excluding the property and equipment acquired from
EMI (Note 4), the wireless transmission equipment acquired to date has not  been
placed into service.
 
6.  ACCOUNTS PAYABLE AND ACCRUED LIABILITIES:
 
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES COMPRISE:
 
<TABLE>
<S>                                                              <C>
Accrued interest payable.......................................  $   20,712
Salaries and other employee related costs......................     267,091
Trade accounts payable.........................................     496,104
Wireless transmission equipment payable........................   2,666,630
                                                                 ----------
                                                                 $3,450,537
                                                                 ----------
                                                                 ----------
</TABLE>
 
7.  NOTE PAYABLE TO ART:
    ART,   Telecom  and  several  entities  referred  to  as  the  Advent  Group
("Advent"), entered into a securities  purchase agreement (the "Advent  Purchase
Agreement")  dated November 13, 1995 under which  Advent agreed to acquire a 10%
interest in  the  combined  entities  of  ART,  Telecom  and  certain  specified
affiliates.  Pending  the merger  of  these entities  (see  Note 2),  ART issued
promissory notes  (the "Advent  Notes") with  an aggregate  principal amount  of
$4,950,000  and  one  share of  ART's  Series  A Redeemable  Preferred  Stock in
exchange for $5.0 million in cash.
 
    The Advent  Notes carried  interest at  a rate  of 10%  per annum  and  were
payable  on demand at any time  on or after May 13,  1997. The Advent Notes were
collateralized by  certain assets  of ART  and Telecom.  The Advent  Notes  were
convertible  into that number of shares  of preferred stock which represented in
the aggregate at least 10%  of the fully diluted  capital stock of the  combined
entities  described  above, as  defined in  the  Advent Purchase  Agreement. The
Advent Notes were convertible either (i) immediately prior to an initial  public
offering  with aggregate  gross proceeds  of at least  $10.0 million  or (ii) at
Advent's election.
 
    On November 13,  1995, the gross  proceeds of $5.0  million received by  ART
from  Advent  were transferred  to Telecom  in  exchange for  a note  with terms
equivalent  to  the  terms  of  the   Advent  Notes.  In  connection  with   the
Reorganization  on February  2, 1996,  ART, Telecom  and Advent  entered into an
exchange agreement under which the Advent Notes, including accrued interest, and
the one share of ART's Series A  Redeemable Preferred Stock held by Advent  were
exchanged  for 232,826 shares of  Series E preferred stock  of Telecom, the note
was canceled, and  Telecom became the  owner of the  one share of  ART Series  A
Redeemable Preferred Stock.
 
                                      F-39
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS:
 
EQUIPMENT PURCHASE AGREEMENT
 
    On  August 11, 1995, Telecom entered  into an agreement to purchase wireless
transmission equipment from a vendor. Under the terms of the agreement,  Telecom
is  obligated  to purchase  a specified  number  of wireless  transmission units
between August 11, 1995  and December 31, 1998,  subject to termination upon  90
days  advance notice by either  party. Telecom's initial non-cancelable purchase
order amounts to $13,260,000. Through  December 31, 1995, Telecom has  purchased
and paid for $522,812 of equipment under this contract. In addition, Telecom has
made  a $280,000  deposit under  this agreement which  is to  be applied against
future purchases after Telecom  has purchased a  specified amount of  equipment,
which is expected to occur in 1996.
 
    Telecom  currently  purchases  the  majority  of  its  wireless transmission
equipment from this vendor.  Any reduction or interruption  in supply from  this
vendor  could have a material adverse effect on Telecom until alternative supply
sources are established.  Telecom does  not manufacture,  nor does  it have  the
capability  to manufacture, any of the wireless transmission equipment necessary
to  provide  its  services.  Although  there  are  a  limited  number  of  other
manufacturers  who have, or are developing,  equipment that would meet Telecom's
requirements, there can be no assurance  that such equipment would be  available
to  Telecom on comparable terms or on  terms more favorable to those included in
its current arrangements. Moreover, a change  in vendors could cause a delay  in
Telecom's  ability to provide its services,  which would affect future operating
results adversely.
 
SERVICES AGREEMENTS
 
    Under the Services Agreement, Telecom  has agreed to construct, operate  and
manage the FCC licenses and related telecommunications systems that are owned by
ART  or  for which  ART  has existing  services  agreements. Under  the Services
Agreement, Telecom will incur  all costs and  expenses related to  construction,
operation  and management of the systems.  As compensation, Telecom will receive
all revenues generated  by the  systems after deducting  certain related  direct
expenses, less 25% which is to be paid to ART.
 
    Telecom,  through its Services  Agreement with ART,  has two other exclusive
services agreements, one with ART West, a  joint venture in which ART has a  50%
ownership  interest, and one with DCT Communications, Inc. ("DCT"). The terms of
these two services agreements  are substantially identical to  the terms in  the
Services  Agreement between ART and Telecom, except that the services agreements
are for five  years and compensation  to the  Company is based  on all  revenues
generated  by the systems after deducting  certain related direct expenses, less
45% which is  paid to ART  West and DCT.  There have been  no services  provided
under these agreements through December 31, 1995. One of the officers of Telecom
is the President and a shareholder of ART's joint venture partner in ART West.
 
    On  April 24, 1996,  Telecom entered into a  services agreement with TeleCom
One on terms  substantially identical  to the  terms of  the Services  Agreement
between  ART and Telecom,  except that compensation  to Telecom is  equal to all
revenues generated by the  systems, after deducting  certain expenses, less  10%
which is paid to TeleCom One.
 
    Under  the services agreements  described above, title  to the system assets
purchased by Telecom  and used  to provide  services in  the respective  markets
remains with Telecom upon termination of the services agreements.
 
                                      F-40
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
EMPLOYMENT AND CONSULTING AGREEMENTS
 
    On  May 8, 1995, Telecom and  ART jointly entered into consulting agreements
with two executive  officers of  Telecom, effective as  of January  1, 1995  and
continuing  for  a  term  of  three  years,  with  minimum  payments aggregating
approximately $170,000 annually. The aggregate expense incurred by Telecom under
these consulting agreements through December 31, 1995 amounted to $166,750.
 
    On December 16, 1995, one of the executive officers of Telecom, previously a
party to  one of  the  consulting agreements  described  above, entered  into  a
full-time  employment agreement.  The employment  agreement is  for a three-year
term with an annual salary of $250,000 in the first year, $275,000 in the second
year and $300,000 in the third year.  In addition, the agreement provides for  a
cash  bonus of up to  $100,000 for each year  based upon achievement of specific
performance objectives.
 
    On July 11, 1995, Telecom entered  into an employment agreement, as  amended
February  2, 1996, with an officer of Telecom.  The term of the agreement is for
three years at an annual salary of  $160,000 in the first year, $200,000 in  the
second year and $240,000 in the third year. Options to purchase shares of common
stock were awarded to this officer equivalent to 2.5% of the outstanding capital
stock  of Telecom (see Note  10). The agreement also  provides for an engagement
bonus of $17,000  upon execution  of the  agreement and a  cash bonus  of up  to
$100,000   for  each  year  based   upon  achievement  of  specific  performance
objectives.
 
    Telecom has entered  into employment agreements  with other executives  that
provide  for  annual base  salaries  and cash  bonuses  based on  achievement of
specific performance goals.  These contracts may  be terminated at  any time  by
management.
 
FINANCING AGREEMENT
 
    During  1994, ART entered into an agreement with Southeast Research Partners
("SERP"), a subsidiary of Joesephthal, Lyons & Ross, a Florida broker dealer, to
procure additional  financing  for ART  in  exchange  for cash  and  options  to
purchase  capital stock of  ART. Pursuant to  a letter agreement  dated July 12,
1995, ART and  Telecom paid SERP  $245,000 and the  shareholders of ART  granted
SERP  options to purchase 313,644  shares of ART Common  Stock directly from the
shareholders of ART for an aggregate consideration of approximately $210,000.
 
    As of December  31, 1995,  ART and  Telecom have  accounted for  the fee  of
$245,000 as part of the financing provided by Landover and, accordingly, $70,000
has  been recognized as an offset against  the proceeds from the issuance of the
Serial preferred stock of Telecom  (see Note 9) and the  balance as part of  the
deferred  financing costs recorded by ART in connection with the issuance of the
Advent Notes (See Note 7).
 
                                      F-41
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
LEASES
 
    Telecom and ART  have entered  into operating  leases for  office space  and
antenna  sites which  expire between  1997 and  2001. Lease  expense amounted to
$16,044 for 1995. The costs associated  with these leases have been recorded  by
Telecom  and no amounts  have been charged  to ART. Future  annual minimum lease
payments as of December 31, 1995 are as follows:
 
<TABLE>
<S>                                                              <C>
1996...........................................................  $  363,079
1997...........................................................     352,480
1998...........................................................     302,727
1999...........................................................     297,417
2000 and thereafter............................................      25,825
                                                                 ----------
                                                                 $1,341,528
                                                                 ----------
                                                                 ----------
</TABLE>
 
9.  STOCKHOLDERS' DEFICIT:
    At December  31,  1995,  the Certificate  of  Incorporation  authorized  the
issuance  of  20,000,000  shares  of  stock of  all  classes,  divided  into (i)
10,000,000 shares  of  common  stock,  $0.001 par  value  per  share,  of  which
7,000,000 shares are designated as Class A common stock and 3,000,000 shares are
designated  as  Class B  common stock  and (ii)  10,000,000 shares  of preferred
stock, $0.001 par  value per  share of which  451,513 shares  are designated  as
Series  A preferred stock,  113,663 shares are designated  as Series B preferred
stock, 7,297 shares are designated as Series C preferred stock and 61,640 shares
are designated as Series D preferred stock, before giving effect to the 13 for 1
stock split discussed below.  Pursuant to the Reorganization  (see Note 2),  the
Certificate of Incorporation was amended and restated on February 2, 1996 to (i)
convert  each share of  Class A common stock  and Class B  common stock into one
share of common stock,  par value $0.001 per  share, (ii) change the  authorized
capital  stock of the Corporation to 70,000,000  shares of stock of all classes,
(iii) change the authorized  common stock to 60,000,000  shares, (iv) amend  the
terms  of the preferred stock  and each series thereof,  (v) provide for two new
series of preferred stock designated as "Series E preferred stock" and "Series F
preferred stock", and (vi) effect a 13 for 1 stock split of each share of common
stock issued and outstanding.
 
    The holders of Class A common stock had anti-dilution protection, but in all
other respects such shares were identical to the Class B common stock. Under the
anti-dilution provisions, additional shares of Class A common stock were issued,
for no  consideration, to  the holders  of the  Class A  common stock  upon  the
issuance  of serial preferred stock, so that the holders of Class A common stock
maintained their  36%  ownership  interest through  the  $7.0  million  Landover
Funding Commitment as set forth in the Purchase Agreement.
 
    Under  the  Purchase  Agreement,  the individual  shareholders  of  ART were
required to place 5,153,778 shares of Common Stock in ART in escrow (the "Escrow
Shares") to be released upon the completion of the pending EMI Asset acquisition
(see Note 4), Telecom's attainment of  specific operating income levels for  the
years  1997 through 1999 and the acquisition  of interests in a specified number
of FCC license authorizations by April 30, 2000. As a result of the consummation
of the EMI Asset acquisition, in  November 1995, 1,873,030 shares of the  Escrow
Shares  of ART were released. The related compensation of $802,002, based on the
then  current  fair  value  of  the  Escrow  Shares,  has  been  recognized   as
compensation  expense in 1995, the offset of  which has been accounted for as an
investment by ART. Pursuant to the  February 2, 1996 Reorganization, the  Escrow
Shares arrangement was
 
                                      F-42
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
9.  STOCKHOLDERS' DEFICIT, CONTINUED:
terminated  and  all  of  the  remaining  Escrow  Shares  were  released  to the
stockholders of  ART. The  related compensation  expense of  approximately  $6.8
million,  based  upon the  fair value  of  the remaining  Escrow Shares  will be
recognized in 1996.
 
    Each issuance of  serial preferred  stock pursuant to  the Landover  Funding
Commitment  is a separate  class and, as  a class, has  a liquidation preference
equal to  the aggregate  price paid  for such  class and  an ownership  interest
designated  by Landover at issuance. The  ownership interest of each outstanding
class of serial preferred stock was not to be diluted by subsequent issuances of
shares of other classes  of serial preferred stock  through the satisfaction  of
the  Landover  Funding  Commitment. As  a  result, additional  shares  of serial
preferred stock were issued  to the existing holders  upon the issuance of  such
other  shares so that each outstanding class maintained its designated aggregate
liquidation preference and aggregate ownership interest.
 
    Each share of  serial preferred stock  outstanding at December  31, 1995  is
convertible  into 13  shares of common  stock, subject  to certain anti-dilution
adjustments. The holders  of serial  preferred stock  have a  vote, and  receive
dividends  or distributions, equivalent to the  votes and amounts which would be
obtainable by them upon conversion of their shares into common stock.
 
    In partial satisfaction  of the  Landover Funding  Commitment, during  1995,
Telecom  issued 332,091  shares of  Series A  preferred stock,  82,318 shares of
Series B preferred stock and 5,402 shares  of Series C preferred stock to  three
separate  limited partnerships of which an  affiliate of Landover is the general
partner, for aggregate cash consideration of $2.0 million.
 
    On November 9,  1995, Telecom  issued 61,640  shares of  Series D  preferred
stock  for cash of $2.0 million. The Series D preferred stock purchase agreement
provided that in the  event that Telecom  and ART on a  combined basis, did  not
achieve an equity valuation of $225.0 million, as defined, on or before November
1,  1997, the holders of the Series D preferred stock had the option to purchase
additional shares of serial preferred stock for $0.001 per share up to a maximum
of 1.33%  of  the  then outstanding  capital  stock  of Telecom.  The  Series  D
preferred  stock purchase  agreement was  amended February  2, 1996  whereby the
option to purchase additional serial preferred stock was replaced with an option
to purchase 400,634 shares  of Telecom common stock  directly from Landover  for
$0.001  per share in the event Telecom  does not attain certain equity valuation
objectives.
 
    On November  13,  1995, the  Advent  Group executed  a  securities  purchase
agreement  with ART  and Telecom.  As a result  of the  exchange agreement dated
February 2, 1996, Advent received 232,826 shares of Series E preferred stock  of
Telecom (see Note 7).
 
    The  serial  preferred  stock  transactions  described  above  satisfied the
Landover Funding Commitment. As a  result, the anti-dilution protection for  the
Class  A common stock and serial preferred  stock terminated. As the actual cash
proceeds received  were in  excess  of Landover's  $7.0 million  commitment,  on
November 13, 1995, Telecom used the proceeds from the sale of Series D preferred
stock to redeem 807,924 shares of Class B common stock held by Landover.
 
    The  Series E and F preferred stock  (see Note 14) are senior in liquidation
preference to the Series A, B, C  and D preferred stock. The Series D  preferred
stock  is senior in  liquidation preference to  the Series A,  B and C preferred
stock. At any time on or after November  13, 2000, the Series E and F  preferred
stock  may be redeemed  at the option  of the holders  of such stock  at a price
equal to the liquidation amount plus all accrued and unpaid dividends.
 
                                      F-43
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
10. STOCK OPTION PLANS:
    On July 22, 1995,  Telecom adopted the 1995  Stock Option Plan (the  "Plan")
that  provides  for  option  grants  to  employees,  directors  and  independent
consultants of Telecom. Telecom  has reserved 2,500,000  shares of common  stock
for  issuance under the Plan. Options granted  to employees may be designated as
incentive stock options ("ISO's") or non-qualified stock options ("NQSO's"),  as
defined  by  the  Internal  Revenue  Service.  Options  granted  to  independent
consultants and other non-employees may only be designated NQSO's.
 
    The exercise price of options  granted under the Plan  may not be less  than
100%  of the fair market value of the common stock on the grant date. Generally,
options will be exercisable for a term  that will not exceed ten years from  the
date of grant.
 
    Under  the Plan,  options to  purchase an  aggregate of  817,232 and 235,000
shares of common stock were granted to employees of Telecom on July 22, 1995 and
December 29, 1995,  respectively, at an  option price of  $.5907 and $1.652  per
share,  respectively. The difference  between the exercise  price of the options
issued at $.5907 and the deemed fair value of common stock of $1.20 per share as
determined on the measurement date,  is recognized as compensation expense  over
the respective vesting period. The options vest at various dates during a 5-year
period.  At  December 31,  1995,  361,785 options  were  vested and  Telecom has
recognized compensation expense of $287,603  during 1995. At December 31,  1995,
unearned  stock option compensation expense amounted  to $210,339. There were no
options exercised or canceled during 1995.
 
    On February 15, 1996, options to purchase an aggregate of 145,000 shares  of
common  stock were granted to  employees of Telecom under  the Plan at an option
price of $3.94 per share.
 
    On April 24, 1996, Telecom adopted the 1996 Non-Employee Directors Automatic
Stock Option Plan (the "Directors Plan"), subject to shareholder approval, which
provides for the automatic grant of  stock options to non-employee directors  to
purchase up to an aggregate of 200,000 shares. Under the Directors Plan, options
to  acquire 6,000 shares of common stock  are automatically granted to each non-
employee director who is a director on January 1 of each year. In addition, each
non-employee director serving on the Board of Directors effective on the date of
an initial public offering,  and in the future  each newly elected  non-employee
director on the date of his or her first appointment or election to the Board of
Directors  will receive an automatic grant of options to acquire 7,000 shares of
common stock.
 
    In October 1995, the Financial  Accounting Standards Board issued  Statement
of   Financial  Accounting  Standards  No.   123,  "Accounting  for  Stock-Based
Compensation". This Statement encourages, but  does not require, accounting  for
stock  compensation awards granted to employees based on their fair value at the
date the awards are  granted. Companies may elect  to continue to apply  current
accounting  requirements for employee stock compensation awards, which generally
will result in no compensation cost for  most fixed stock option plans, such  as
Telecom's Plan. The expense measurement provisions of the Statement apply to all
equity  instruments issued for goods and services provided by persons other than
employees. All companies are required to comply with the disclosure requirements
of the  Statement. Telecom  expects to  continue accounting  for employee  stock
compensation awards using current accounting requirements.
 
11. INCOME TAXES:
    As  of December  31, 1995, Telecom  has net operating  loss carryforwards of
approximately $1.9 million to  offset future taxable  income for Federal  income
tax  purposes which  will expire in  2010. Deferred tax  assets of approximately
$741,000, principally comprised  of such net  operating tax loss  carry-forwards
and temporary differences arising from compensation expense related to the stock
option plans have been offset in full by a valuation allowance.
 
                                      F-44
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
12. RELATED PARTY TRANSACTIONS:
    On  May 8, 1995,  Telecom and ART  entered into a  consulting agreement with
Landover as a strategic and financial consultant. Telecom paid Landover  $70,000
for  services under  this agreement  during 1995.  The consulting  agreement was
terminated on November 13, 1995.
 
    On November 13, 1995, Telecom and  ART entered into a management  consulting
agreement with Landover to provide strategic planning, corporate development and
general  management. Under the agreement, Telecom  will pay Landover $35,000 per
month for  an initial  one  year term,  renewable by  Telecom  and ART  for  two
additional  one year  terms. The aggregate  expense under  this agreement during
1995 amounted to $70,000, which amount is  payable as of December 31, 1995.  The
agreement   also  provides  that  in  the  event  Landover  arranges  financing,
acquisitions or certain other transactions for Telecom, it will be paid a fee by
Telecom in accordance with industry standards.
 
    Pursuant to the Purchase Agreement,  Telecom and ART paid Landover  $391,750
for  expenses  in  connection with  the  Landover Funding  Commitment,  of which
$141,750 has been charged  to paid-in capital by  Telecom and $250,000 has  been
capitalized as deferred financing costs by ART.
 
    An  executive  and shareholder  of ART  is a  principal in  a law  firm that
regularly provides legal services to Telecom.  During the period from March  28,
1995 through December 31, 1995, Telecom incurred $237,538 for such services.
 
    Telecom  has funded certain expenses and investments of ART, including ART's
investment in ART West and payments of financing and other operating costs.  The
amounts funded by Telecom to date totalling $805,803, offset by accrued interest
of $67,123 related to the note payable to ART (see Note 7) have been included in
the amount due from ART.
 
13. FAIR VALUES OF FINANCIAL INSTRUMENTS:
    The  carrying amount and  fair values of  Telecom's financial instruments at
December 31, 1995 were as follows:
 
<TABLE>
<CAPTION>
                                                                              CARRYING         FAIR
                                                                               AMOUNT          VALUE
                                                                            -------------  -------------
<S>                                                                         <C>            <C>
Cash and cash equivalents.................................................  $     627,585  $     627,585
Long-term notes payable...................................................      6,500,000      6,500,000
</TABLE>
 
    Cash and cash equivalents: The carrying amount reported in the balance sheet
approximates fair value.
 
    Long-term notes payable: The carrying  amount approximates fair value  based
upon interest rates that are currently available to Telecom for issuance of debt
with similar terms and maturity.
 
14. SUBSEQUENT EVENTS:
 
- -- AMERITECH FINANCING
 
    On  February 2, 1996, Telecom sold 48,893 shares of Series F preferred stock
for an  aggregate  purchase  price  of $2.5  million  to  Ameritech  Development
Corporation  ("Ameritech").  In  addition,  Telecom  entered  into  a  strategic
distribution agreement with Ameritech  Corp., the parent  of Ameritech, and,  as
partial  consideration, granted warrants to Ameritech  to purchase up to 877,136
shares of common stock from Telecom at  a price of $0.01 per share,  exercisable
on  February 2, 1996 through February 2,  2006. The Series F preferred stock and
warrants are collectively referred to as the Ameritech Securities. The strategic
distribution agreement provides for Ameritech to be the principal distributor of
Telecom's services  within  five midwestern  states.  Telecom incurred  fees  of
$150,000 in connection with this transaction.
 
                                      F-45
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
14. SUBSEQUENT EVENTS, CONTINUED:
    Under  the  terms  of  the  securities  purchase  agreement  with Ameritech,
Ameritech is  entitled to  a put  option to  require Telecom  to repurchase  the
Ameritech  Securities if the Department of Justice finds that this investment is
in violation of restrictions  under the Modification of  Final Judgement in  the
United  States vs. AT&T Civil Action  82-0192 ("MFJ"). Telecom would be required
to repurchase the  Ameritech Securities at  a purchase price  equal to the  fair
market value on the date it is determined that the investment is in violation of
the MFJ.
 
- -- BRIDGE FINANCING
 
    On  March 8, 1996, Telecom issued in  a private placement of $5.0 million of
two year, 10% notes (the "Bridge Notes")  and five year warrants to purchase  up
to  an aggregate  of 1,100,000 shares  of common stock  at a price  of $6.25 per
share (the "Bridge Warrants") to certain holders of serial preferred stock.  The
Bridge Warrants are exercisable on March 8, 1996 through March 8, 2001.
 
- -- EQUIPMENT FINANCING
 
    On  April  24,  1996,  the  Board  of  Directors  approved  the  adoption of
resolutions necessary  to  complete a  $2,445,000  equipment financing  for  the
purchase of wireless transmission equipment.
 
- -- RESEARCH AND DEVELOPMENT ARRANGEMENTS
 
    On  January 26, 1996, Telecom entered into a preliminary agreement to invest
from $700,000 to $1.0 million in an entity in which an executive of Telecom is a
director and a shareholder. The preliminary agreement provides for the entity to
perform research and  development of  wireless transmission  equipment in  which
Telecom  will receive  a right  of first  refusal on  production capacity  and a
license fee in exchange for its investment.
 
    On March 13, 1996,  Telecom issued a  letter of intent to  a third party  to
provide  Telecom  with specific  technology  consulting in  connection  with the
development of wireless transmission equipment. The aggregate amount to be  paid
pursuant  to  the letter  of intent  totals  $90,000. The  letter of  intent was
executed in connection with  an agreement currently  under negotiations for  the
development and manufacture of wireless transmission equipment.
 
- -- SOFTWARE LICENSE AGREEMENT
 
    On  March 29, 1996,  Telecom entered into a  software license agreement (the
"Software License  Agreement").  The terms  of  the Software  License  Agreement
provide  for licensed software and hardware for Telecom's network management and
maintenance support services.  The Software  License Agreement  provides for  an
initial   software  license  fee  of  approximately  $2,000,000  and  an  annual
maintenance support fee of approximately  $300,000 per year. An initial  payment
of  $250,000 for  the software  license fee  was payable  upon execution  of the
agreement with  the balance  payable in  monthly installments  of principal  and
interest commencing January 1, 1997.
 
- -- DCT PRELIMINARY AGREEMENT
 
    On April 25, 1996, Telecom and ART entered into a preliminary agreement with
DCT  (the "DCT Preliminary Agreement") to  acquire DCT's interest in certain FCC
authorizations and  licenses in  exchange  for $3.6  million  in cash.  The  DCT
Preliminary  Agreement is  subject to  the completion  of a  definitive purchase
agreement and services agreement (see Note 8). The definitive purchase agreement
will supersede and replace all  other existing agreements between Telecom,  ART,
ART's  shareholders and DCT. The definitive purchase agreement must be signed by
June 28, 1996 and the closing of the transaction is subject to FCC approval.
 
                                      F-46
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                   UNAUDITED INTERIM CONDENSED BALANCE SHEET
                                 MARCH 31, 1996
 
<TABLE>
<CAPTION>
                                           ASSETS
<S>                                                                             <C>
Current assets:
  Cash and cash equivalents...................................................  $  3,018,191
  Due from ART................................................................       498,100
  Other current assets........................................................        61,226
                                                                                ------------
    Total current assets......................................................     3,577,517
Property and equipment, net...................................................     6,379,603
FCC licenses..................................................................     4,226,821
Equipment and other deposits..................................................       344,417
Investment in ART.............................................................        44,930
Deferred financing costs......................................................       681,692
                                                                                ------------
      Total assets............................................................  $ 15,254,980
                                                                                ------------
                                                                                ------------
 
                            LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Accounts payable and accrued liabilities....................................  $  4,211,017
                                                                                ------------
      Total current liabilities...............................................     4,211,017
Bridge Notes..................................................................     3,983,082
Note payable to EMI...........................................................     1,500,000
                                                                                ------------
      Total liabilities.......................................................     9,694,099
                                                                                ------------
Commitments and contingencies
Stockholders' equity:
  Serial preferred stock, $.001 par value, 920,951 shares issued and
   outstanding................................................................           921
  Class A common stock, $.001 par value, 18,114,135 shares issued and
   outstanding................................................................        18,114
  Additional paid-in capital..................................................    19,189,302
  Deficit accumulated during the development stage............................   (13,647,456)
                                                                                ------------
      Total stockholders' equity..............................................     5,560,881
                                                                                ------------
        Total liabilities and stockholders' equity............................  $ 15,254,980
                                                                                ------------
                                                                                ------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-47
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
              UNAUDITED INTERIM CONDENSED STATEMENT OF OPERATIONS
                   FOR THE THREE MONTHS ENDED MARCH 31, 1996
 
<TABLE>
<CAPTION>
Operating revenue.............................................................  $     9,620
<S>                                                                             <C>
                                                                                -----------
Expenses:
  General and administrative..................................................    8,889,364
  Market development..........................................................    1,150,063
  Research and development....................................................      419,418
  Depreciation and amortization...............................................       86,684
  Interest expense, net.......................................................      130,474
                                                                                -----------
    Total expenses............................................................   10,676,003
                                                                                -----------
      Net loss................................................................  $10,666,383
                                                                                -----------
                                                                                -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-48
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
    UNAUDITED INTERIM CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT)
                   FOR THE THREE MONTHS ENDED MARCH 31, 1996
<TABLE>
<CAPTION>
                                                                           PREFERRED STOCK
                             COMMON    ---------------------------------------------------------------------------------------
SHARES                       STOCK      SERIES A     SERIES B     SERIES C     SERIES D     SERIES E     SERIES F      TOTAL
- -------------------------  ----------  -----------  -----------  -----------  -----------  -----------  -----------  ---------
<S>                        <C>         <C>          <C>          <C>          <C>          <C>          <C>          <C>
Balance at December 31,
 1995....................  15,291,211     334,943       86,507        5,402       61,640                               488,492
Issuance of Series E
 preferred stock.........                                                                     232,826                  232,826
Shares issued to reflect
 anti-dilution
 adjustments.............   2,822,924     120,607       28,172        1,961                                            150,740
Issuance of Series F
 preferred stock.........                                                                                   48,893      48,893
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
Balance of March 31,
 1996....................  18,114,135     455,550      114,679        7,363       61,640      232,826       48,893     920,951
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
 
<CAPTION>
 
                                                                        PAR VALUE
                           ---------------------------------------------------------------------------------------------------
                                                                           PREFERRED STOCK
                             COMMON    ---------------------------------------------------------------------------------------
AMOUNTS                      STOCK      SERIES A     SERIES B     SERIES C     SERIES D     SERIES E     SERIES F      TOTAL
- -------------------------  ----------  -----------  -----------  -----------  -----------  -----------  -----------  ---------
<S>                        <C>         <C>          <C>          <C>          <C>          <C>          <C>          <C>
Balance at December 31,
 1995....................  $   15,291   $     335    $      86    $       5    $      62                             $     488
Issuance of Series E
 preferred stock.........                                                                   $     233                      233
Shares issued to reflect
 anti-dilution
 adjustments.............       2,823         121           28            2                                                151
Issuance of Series F
 preferred stock and
 warrants in exchange for
 cash and the Strategic
 Distribution Agreement
 net of expenses of
 $150,000................                                                                                $      49          49
Value ascribed to the
 Bridge Warrants.........
Investment by ART as a
 result of the release of
 escrow shares...........
Accrued stock option
 compensation............
Net loss.................
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
Balance at March 31,
 1996....................  $   18,114   $     456    $     114    $       7    $      62    $     233    $      49   $     921
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
                           ----------  -----------  -----------       -----   -----------  -----------  -----------  ---------
 
<CAPTION>
 
SHARES
- -------------------------
<S>                        <C>          <C>            <C>
Balance at December 31,
 1995....................
Issuance of Series E
 preferred stock.........
Shares issued to reflect
 anti-dilution
 adjustments.............
Issuance of Series F
 preferred stock.........
 
Balance of March 31,
 1996....................
 
                           ADDITIONAL
                             PAID-IN     ACCUMULATED
AMOUNTS                      CAPITAL       DEFICIT        TOTAL
- -------------------------  -----------  -------------  -----------
<S>                        <C>          <C>            <C>
Balance at December 31,
 1995....................  $ 2,845,372   $(2,981,073)  $  (119,922)
Issuance of Series E
 preferred stock.........    4,672,953                   4,673,186
Shares issued to reflect
 anti-dilution
 adjustments.............       (2,974)
Issuance of Series F
 preferred stock and
 warrants in exchange for
 cash and the Strategic
 Distribution Agreement
 net of expenses of
 $150,000................    3,402,951                   3,403,000
Value ascribed to the
 Bridge Warrants.........    1,050,000                   1,050,000
Investment by ART as a
 result of the release of
 escrow shares...........    6,795,514                   6,795,514
Accrued stock option
 compensation............      425,486                     425,486
Net loss.................                (10,666,383)  (10,666,383)
                           -----------  -------------  -----------
Balance at March 31,
 1996....................  $19,189,302   $(13,647,456) $ 5,560,881
                           -----------  -------------  -----------
                           -----------  -------------  -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements
 
                                      F-49
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
              UNAUDITED INTERIM CONDENSED STATEMENT OF CASH FLOWS
                   FOR THE THREE MONTHS ENDED MARCH 31, 1996
 
<TABLE>
<CAPTION>
Cash flows from operating activities:
<S>                                                                             <C>
  Net loss....................................................................  $(10,666,383)
  Adjustments to reconcile net loss to net cash used in operating activities:
    Depreciation and amortization.............................................        86,684
    Non-cash interest expense.................................................        34,726
    Non-cash compensation expenses............................................     7,221,000
    Non-cash market development expense.......................................     1,053,000
    Changes in operating assets and liabilities:
      Deposits................................................................        (8,901)
      Accounts payable and accrued liabilities................................       881,492
      Other current assets....................................................       (60,405)
                                                                                ------------
        Net cash used in operating activities.................................    (1,458,787)
                                                                                ------------
Cash flows from investing activities:
  Additions to property and equipment.........................................    (3,050,607)
                                                                                ------------
        Net cash used in investing activities.................................    (3,050,607)
                                                                                ------------
Cash flows from financing activities:
  Proceeds from issuance of serial preferred stock............................     2,500,000
  Preferred stock issuance costs..............................................      (150,000)
  Proceeds from issuance of Bridge Notes and Bridge Warrants..................     5,000,000
  Payments of ART deferred finance costs......................................      (175,000)
  Additions to deferred financing costs.......................................      (275,000)
                                                                                ------------
        Net cash provided by financing activities.............................     6,900,000
                                                                                ------------
          Net increase in cash and cash equivalents...........................  $  2,390,606
          Cash and cash equivalents, beginning of period......................       627,585
                                                                                ------------
          Cash and cash equivalents, end of period............................  $  3,018,191
                                                                                ------------
                                                                                ------------
Supplemental cash flow information:
  Non-cash financing and investing activities:
    Additions to property and equipment.......................................  $  2,477,264
    Value ascribed to the Ameritech Strategic Distribution Agreement reflected
     as paid-in capital.......................................................     1,053,000
    Accrued deferred financing costs..........................................        85,338
    Exchange of Advent Notes and ART Notes for Series E preferred stock, net
     of deferred financing costs..............................................     4,673,186
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-50
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
           NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS
 
1.  THE COMPANY AND BASIS OF PRESENTATION:
 
THE COMPANY
 
    Advanced  Radio  Telecom Corp.  ("Telecom"),  formerly named  Advanced Radio
Technology Ltd., was incorporated in Delaware as a subsidiary of Advanced  Radio
Technologies  Corporation  ("ART") on  March 28,  1995,  to develop,  market and
deliver broadband  telecommunication  and information  services  throughout  the
United States.
 
BASIS OF PRESENTATION
 
    The  condensed financial  statements included  herein have  been prepared by
Telecom. The foregoing  statements contain all  adjustments (consisting only  of
normal recurring adjustments) which are, in the opinion of management, necessary
to present fairly the financial position of Telecom as of March 31, 1996 and the
results  of its operations and  its cash flows for  the three months ended March
31, 1996.
 
    Certain information and footnote disclosures normally included in  financial
statements  have been condensed or omitted pursuant to the rules and regulations
of the Securities and Exchange Commission. These condensed financial  statements
should  be read in  conjunction with Telecom's  audited financial statements and
notes thereto included elsewhere herein.
 
    The financial statements have  been prepared on the  going concern basis  of
accounting,   which  contemplates  realization  of  assets  and  liquidation  of
liabilities in the ordinary  course of business.  Telecom has limited  financial
resources,  has incurred operating losses since inception and does not expect to
generate material operating  revenues until the  commencement of its  commercial
services,  which is anticipated to occur  in fiscal 1996. Telecom estimates that
revenues in 1996 will not be  sufficient to fund its initial operating  expenses
and  other  working capital  needs, including  consulting, service  and purchase
commitments. Telecom's  funding  of  its  initial  operating  expenses,  working
capital needs and contractual commitments is dependent upon its ability to raise
additional financing. Telecom and ART have engaged various investment bankers to
assist  it in raising financing through a public equity and debt offering. There
can be no  assurance that  Telecom will  be successful  in its  effort to  raise
additional financing through this public offering or, if available, that Telecom
will  be  able  to  obtain  it  on  acceptable  terms.  These  conditions  raise
substantial doubt about Telecom's  ability to continue as  a going concern.  The
financial  statements do not include any  adjustments that might result from the
outcome of these uncertainties.
 
2.  REORGANIZATION AND PENDING MERGER WITH ART:
    On February 2, 1996, Telecom,  ART and their respective shareholders  agreed
to an amendment and restatement of the Stockholders' Agreement providing for (i)
termination  effective on the closing of a public share offering; (ii) amendment
and restatement of the  Certificate of Incorporation  and reorganization of  the
capital  structure of Telecom;  (iii) the exchange  of the Advent  Notes and one
share of ART Series A Redeemable Preferred Stock for Series E preferred stock of
Telecom; (iv) revision of  provisions for election  of directors; (v)  amendment
and  restatement of  Telecom's registration  rights agreements;  (vi) release of
shares escrowed in  connection with  the original  Stockholders' Agreement;  and
(vii)  approval  of  a  definitive  agreement  to  merge  ART  and  Telecom (the
"Reorganization").
 
    The definitive merger  agreement, as entered  into on February  2, 1996  and
subsequently  restated and  amended on June  26, 1996,  (the "Merger Agreement")
provides for  the  merger of  a  newly-formed  wholly owned  subsidiary  of  ART
("Merger  Sub")  into  Telecom  (the "Merger")  subject  to  certain conditions,
including the receipt of FCC approval.  Upon the Merger, each outstanding  share
of  Telecom's  serial  preferred  stock  will be  converted  into  13  shares of
Telecom's common stock and each outstanding
 
                                      F-51
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
     NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS, CONTINUTED
 
2.  REORGANIZATION AND PENDING MERGER WITH ART: CONTINUED:
share of common stock of Telecom will  be exchanged for the right to receive  an
equal  number of shares of Common Stock of ART. As a result, Telecom will become
a wholly owned  subsidiary of  ART. The Merger  Agreement provides  that if  the
Merger  is not consummated by May 13, 1997, the shares of Telecom's common stock
owned by ART will be surrendered  to Telecom for nominal consideration, and  the
Services  Agreement is to be revised to,  among other revisions, extend the term
to 40 years and provide for a proportionate participation by ART's  stockholders
in  any dividends paid by Telecom or the  proceeds from any sale of Telecom. The
Merger Agreement also provides for the assignment of Telecom's interests in  all
of  its  agreements,  including  the  various  services  agreements,  employment
agreements, equipment  purchase agreements  and purchase  option agreements,  to
ART.  Further, upon the Merger, the holders of warrants to purchase an aggregate
of 2,302,136 shares  of Telecom  common stock will  be entitled  to purchase  an
equivalent  number of  shares of  ART Common Stock  on the  same terms. Employee
stock options to  purchase 1,664,732 shares  of Telecom's common  stock will  be
converted into similar stock options of ART.
 
3.  NET LOSS PER SHARE:
    Net  loss per  share of $0.59  is computed based  on the loss  for the three
months ended March 31, 1996 divided by the weighted average number of shares  of
common stock outstanding of 18,114,135.
 
4.  AMERITECH FINANCING:
    On  February 2, 1996, Telecom sold 48,893 shares of Series F preferred stock
for an  aggregate  purchase  price  of $2.5  million  to  Ameritech  Development
Corporation  ("Ameritech").  In  addition,  Telecom  entered  into  a  strategic
distribution agreement with Ameritech  Corp., the parent  of Ameritech, and,  as
partial  consideration, granted warrants to Ameritech  to purchase up to 877,136
shares of common stock from Telecom at  a price of $0.01 per share,  exercisable
on  February 2, 1996 through February 2, 2006. Telecom has recorded the value of
$1,053,000  ascribed  to   the  strategic  distribution   agreement  as   market
development  expense  in the  first quarter  of 1996.  Telecom incurred  fees of
$150,000 in connection with this transaction.
 
5.  NOTE PAYABLE TO ART:
    In connection with the Reorganization on February 2, 1996, ART, Telecom  and
Advent  entered  into  an  exchange  agreement  under  which  the  Advent Notes,
including accrued  interest, and  the one  share of  ART's Series  A  Redeemable
Preferred  Stock held by  Advent were exchanged  for 232,826 shares  of Series E
preferred stock of Telecom, the notes payable by ART to Advent and by Telecom to
ART were canceled, the related interest  forgiven, and Telecom became the  owner
of the one share of ART Series A Redeemable Preferred Stock.
 
6.  COMMITMENTS:
 
DCT PRELIMINARY AGREEMENT
 
    On April 26, 1996, Telecom and ART entered into a preliminary agreement with
DCT  (the "DCT Preliminary Agreement") to  acquire DCT's interest in certain FCC
authorizations and  licenses in  exchange  for $3.6  million  in cash.  The  DCT
Preliminary  Agreement is  subject to  the completion  of a  definitive purchase
agreement  and  services  agreement.  The  definitive  purchase  agreement  will
supersede  and replace all other existing agreements between Telecom, ART, ART's
shareholders and DCT. The definitive purchase  agreement must be signed by  June
28, 1996 and the closing of the transaction is subject to FCC approval.
 
                                      F-52
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
     NOTES TO UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS, CONTINUTED
 
7.  FINANCINGS:
 
BRIDGE FINANCING
 
    On  March 8, 1996, Telecom  issued in a private  placement $5,000,000 of two
year, 10% notes (the "Bridge Notes") and five year warrants to purchase up to an
aggregate of 1,100,000 shares of common stock at a price of $6.25 per share (the
"Bridge Warrants")  to certain  holders of  serial preferred  stock. The  Bridge
Warrants are exercisable on March 8, 1996 through March 8, 2001.
 
EQUIPMENT FINANCING
 
    On  April 29, 1996,  Telecom completed a  $2,445,000 equipment financing for
the purchase of  wireless transmission  equipment. Telecom  issued a  $2,445,000
promissary  note, payable  in 24  monthly installments  of $92,694  with a final
payment of  $642,305  due April  29,  1998.  In connection  with  the  equipment
financing,  Telecom issued five year warrants to  purchase up to an aggregate of
325,000 shares of  common stock  of Telecom. Telecom  paid $225,000  in fees  to
stockholders of Telecom to guarantee the equipment financing.
 
8.  ESCROW SHARES:
    Pursuant  to the  February 2, 1996  Reorganization, the terms  of the Escrow
Shares arrangement were terminated and all  of the remaining Escrow Shares  were
released  to  the  stockholders  of ART.  The  related  compensation  expense of
$6,795,514, based upon the  then estimated fair value  of the Escrow Shares  was
recognized, the offset of which was accounted for as an investment in Telecom by
ART.
 
9.  COMMCOCCC ASSET ACQUISITION
    During  July  1996,  ART  entered into  an  agreement  with  CommcoCCC, Inc.
("CommcoCCC")  to  acquire   CommcoCCC's  interests  in   certain  38  GHz   FCC
authorizations  (the "CommcoCCC Assets") in exchange  for 16.5 million shares of
ART Common Stock. The acquisition of the CommcoCCC Assets is subject to  various
conditions  including (i) minimum  population coverage of  the authorizations of
ART and CommcoCCC, (ii) receipt of final FCC and other approvals, (iii)  receipt
by CommcoCCC of an opinion as to the tax-free nature of the transaction (iv) the
accuracy  of representations and warranties except for breaches that do not have
in the aggregate a material adverse  effect, (v) pending or threatened  material
litigation,  (vi)  consummation of  public equity  and  debt offerings  on terms
reasonably  satisfactory  to  CommcoCCC   and  (vii)  other  customary   closing
conditions.  Pending  the  completion  of the  acquisition,  ART  has  agreed to
construct, manage and operate the CommcoCCC Assets.
 
    At the closing  of the  acquisition, ART  will give  a stockholder  ("Commco
LLC")  of CommcoCCC an  option (the "Option") to  purchase FCC authorizations in
specified market areas in which ART  will have more than one authorization.  The
Option  is  exercisable only  in  the event  that  the CommcoCCC  Acquisition is
consummated  and  Commco  LLC   receives  authorizations  pursuant  to   pending
applications  covering a  minimum specified  population and  expires nine months
after the consummation of the Common Stock Offering. The price of authorizations
to be purchased  under the Option  is based  upon a formula  that considers  the
market price of ART Common Stock on the date of exercise.
 
    In  connection with the  agreement to acquire  the CommcoCCC Assets, certain
stockholders of CommcoCCC loaned  ART $3 million in  cash in exchange for  notes
due  September 30, 1996 (the "CommcoCCC Notes")  with interest at the prime rate
and received three year warrants to  purchase 50,000 shares of ART Common  Stock
at  a price of $15  per share. The CommcoCCC Notes  are collateralized by all of
the assets of  ART and,  if not paid  in full  when due, the  unpaid balance  is
convertible  into ART Common Stock, at the option of each holder, stipulated per
share prices based upon the timing of exercise.
 
                                      F-53
<PAGE>
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
 
    NO  DEALER, SALES REPRESENTATIVE OR ANY  OTHER PERSON HAS BEEN AUTHORIZED TO
GIVE ANY INFORMATION  OR TO  MAKE ANY  REPRESENTATIONS IN  CONNECTION WITH  THIS
OFFERING  OTHER THAN THOSE CONTAINED IN THIS  PROSPECTUS, AND, IF GIVEN OR MADE,
SUCH INFORMATION  OR REPRESENTATIONS  MUST NOT  BE RELIED  UPON AS  HAVING  BEEN
AUTHORIZED  BY THE COMPANY OR ANY OF  THE UNDERWRITERS. THIS PROSPECTUS DOES NOT
CONSTITUTE AN  OFFER  TO  SELL, OR  A  SOLICITATION  OF AN  OFFER  TO  BUY,  ANY
SECURITIES OTHER THAN THE SHARES OF COMMON STOCK TO WHICH IT RELATES OR AN OFFER
TO,  OR A SOLICITATION OF, ANY PERSON IN ANY JURISDICTION WHERE SUCH AN OFFER OR
SOLICITATION WOULD BE UNLAWFUL. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR  ANY
SALE  MADE HEREUNDER SHALL, UNDER ANY CIRCUMSTANCES, CREATE ANY IMPLICATION THAT
THERE HAS BEEN NO CHANGE IN THE AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF  OR
THAT  THE INFORMATION CONTAINED HEREIN  IS CORRECT AS OF  ANY TIME SUBSEQUENT TO
THE DATE HEREOF.
 
                            ------------------------
 
                               TABLE OF CONTENTS
                            ------------------------
 
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
PROSPECTUS SUMMARY.............................           3
RISK FACTORS...................................           9
THE COMPANY....................................          21
USE OF PROCEEDS................................          22
DIVIDEND POLICY................................          22
CAPITALIZATION.................................          23
DILUTION.......................................          24
SELECTED HISTORICAL AND PRO FORMA FINANCIAL
 DATA..........................................          25
MANAGEMENT'S DISCUSSION AND ANALYSIS OF
 FINANCIAL CONDITION AND RESULTS OF
 OPERATIONS....................................          28
BUSINESS.......................................          34
MANAGEMENT.....................................          59
PRINCIPAL STOCKHOLDERS.........................          70
CERTAIN TRANSACTIONS...........................          72
DESCRIPTION OF CAPITAL STOCK...................          77
SHARES ELIGIBLE FOR FUTURE SALE................          79
DESCRIPTION OF CERTAIN INDEBTEDNESS............          81
UNDERWRITING...................................          83
LEGAL MATTERS..................................          84
EXPERTS........................................          84
AVAILABLE INFORMATION..........................          84
GLOSSARY.......................................          86
INDEX TO FINANCIAL STATEMENTS..................         F-1
</TABLE>
 
                            ------------------------
    UNTIL               , 1996 (25 DAYS AFTER THE DATE OF THIS PROSPECTUS),  ALL
DEALERS  EFFECTING  TRANSACTIONS IN  THE REGISTERED  SECURITIES, WHETHER  OR NOT
PARTICIPATING IN THIS  DISTRIBUTION, MAY  BE REQUIRED TO  DELIVER A  PROSPECTUS.
THIS DELIVERY REQUIREMENT IS IN ADDITION TO THE OBLIGATION OF DEALERS TO DELIVER
A  PROSPECTUS  WHEN ACTING  AS  UNDERWRITERS AND  WITH  RESPECT TO  THEIR UNSOLD
ALLOTMENTS OR SUBSCRIPTIONS.
 
                                7,500,000 SHARES
 
                                     [LOGO]
 
                                  COMMON STOCK
 
                                ----------------
 
                                   PROSPECTUS
 
                                ----------------
 
                             MONTGOMERY SECURITIES
                              MERRILL LYNCH & CO.
                            DEUTSCHE MORGAN GRENFELL
 
                                           , 1996
 
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.
 
    The  following table sets forth the  various expenses in connection with the
sale and  distribution of  the securities  being registered,  not including  the
Representative's   non-accountable  expense   allowance.  Except   for  the  SEC
registration fee, the NASD  filing fee and  the Nasdaq listing  fee, all of  the
amounts in the table below are estimated.
 
<TABLE>
<CAPTION>
Securities and Exchange Commission registration fee...................  $  26,767
<S>                                                                     <C>        <C>
NASD filing fee.......................................................
Nasdaq listing fee....................................................  $  50,000
Accounting fees and expenses..........................................      *
Printing..............................................................      *
Blue Sky fees and expenses (including counsel fees)...................     20,000
Legal fees and expenses...............................................      *
Transfer Agent and Registrar fees and expenses........................      *
Miscellaneous expenses................................................      *
                                                                        ---------
TOTAL (estimated).....................................................  $
                                                                        ---------
                                                                        ---------
</TABLE>
 
- ------------------------
*To be completed by amendment.
 
                                      II-1
<PAGE>
ITEM 14.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
    Section  145  of the  General Corporation  Law of  Delaware provides  that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation  and  certain  other  persons serving  at  the  request  of  the
corporation  in related capacities against amounts paid and expenses incurred in
connection with an action or  proceeding to which he is  or is threatened to  be
made a party be reason of such position. If such person shall have acted in good
faith and in a manner he reasonable believed to be in or not opposed to the best
interests  of the corporation,  and, in any criminal  proceeding, if such person
had no reasonable cause to believe  his conduct was unlawful; provided that,  in
the  case  of  actions  brought  by  or in  the  right  of  the  corporation, no
indemnification shall be made with respect to any matter as to which such person
shall have been adjudged to be liable to the corporation unless and only to  the
extent  that  the adjudicating  court  determines that  such  indemnification is
proper under the circumstances.
 
    Reference is made to  Article Ninth of the  Certificate of Incorporation  of
the  Registrant,  Section 6.4  of the  By-laws and  each of  the Indemnification
Agreements filed as Exhibits  10-5, 10-6, 10-7 and  10-8, respectively, to  this
Registration  Statement for  information regarding  indemnification of directors
and officers under certain circumstances.
 
    The  Registrant  has  agreed  to   indemnify  the  Underwriters  and   their
controlling   persons,  and  the  Underwriters  have  agreed  to  indemnify  the
Registrant and its controlling  persons, against certain liabilities,  including
liabilities  under the Securities Act of 1933, as amended (the "Act"). Reference
is made to the Underwriting Agreement filed as part of Exhibit 1-1 hereto.
 
    For  information  regarding  the  Registrant's  undertaking  to  submit   to
adjudication  the issue of indemnification for violation of the Act, see Item 17
hereof.
 
    The Registrant's Certificate of Incorporation provides that every  director,
officer  or agent of the Company shall be  entitled to be indemnified out of the
assets of the  Company against all  losses or  liabilities which he  or she  may
sustain or incur in or about the execution of the duties of his or her office or
otherwise in relation thereto, including any liability incurred by him or her in
defending any proceedings, whether civil or criminal, in which judgment is given
in his or her favor or in which he or she is acquitted, and no director or other
officer  shall be liable for any loss,  damage or misfortune which may happen to
or be incurred  by the  Company in the  execution of  the duties of  his or  her
office or in relation thereto.
 
ITEM 15.  RECENT SALES OF UNREGISTERED SECURITIES.
 
    TELECOM CLASS A AND B COMMON STOCK PRIVATE PLACEMENT
 
    In  April  1995,  the  Company  and  Landover  Holdings  Corporation ("LHC")
subscribed 340,000 shares of Telecom Class A common stock and 640,000 shares  of
Telecom  Class B common stock, respectively,  for $0.001 per share, which, after
giving effect to anti-dilution adjustments and the February 1996 Reorganization,
currently are equivalent upon  conversion prior to  the Offerings to  10,013,055
shares  and  7,512,076  shares,  respectively,  of  Common  Stock.  In addition,
Hedgerow Corporation of  Maine ("Hedgerow")  and Toro  Financial Corp.  ("Toro")
subscribed  15,000 shares  and 5,000  shares, respectively,  of Telecom  Class A
common stock at the  price of $0.001  per share, which,  after giving effect  to
anti-dilution  adjustments and  the February  1996 Reorganization  currently are
equivalent upon conversion prior to the Offerings to 441,753 shares and  147,251
shares  of the  Common Stock, respectively.  The securities issued  in the above
transactions  were  offered  and  sold  in  reliance  upon  the  exemption  from
registration  under  Section  4(2)  of  the  Act.  The  recipients  made certain
representations as to the nature of their investments and had adequacy of access
to information about the Registrant.
 
    PREFERRED STOCK PRIVATE PLACEMENTS
 
    Between May 8,  1995 and November  13, 1995,  the LHC Stock  was diluted  by
purchases  of series of  Telecom preferred stock  by E2-2, E2,  E1 Holdings L.P.
("E1") and E2-3 Holdings,  L.P. ("E2-3" and collectively  with E1, E2 and  E2-2,
the  "Landover Partnerships"), each a  limited partnership whose general partner
is controlled by LHC, in separate  private placements. E2-2, which committed  to
 
                                      II-2
<PAGE>
purchase  up to $3,500,000  of Telecom preferred  stock matching other investors
under the LHC Purchase Agreement, purchased  405,880 shares of Telecom Series  A
preferred  stock  (which converts  into 5,276,440  shares  of Common  Stock upon
completion of this  offering) for an  aggregate of $946,600,  and LHC  purchased
35,873  shares of such Telecom Series A preferred stock from E2-2 for $1,050,000
pursuant to an option.  E2 purchased an aggregate  of 105,823 shares of  Telecom
Series  B preferred stock (which converts  into 1,375,699 shares of Common Stock
upon completion of  this offering) for  an aggregate of  $842,400. E1  purchased
13,797  shares of Telecom Series A  preferred stock (which converts into 179,361
shares of Common  Stock upon completion  of this offering)  for an aggregate  of
$60,000  and 8,856  shares of Telecom  Series B preferred  stock (which converts
into 115,128 shares  of Common Stock  upon completion of  this offering) for  an
aggregate  of $38,300.  E2-3 purchased an  aggregate of 7,363  shares of Telecom
Series C preferred stock (which converts into 95,719 shares of Common Stock upon
completion of this offering) for an  aggregate of $112,700. All of the  Landover
Partnerships  will liquidate  upon completion  of this  offering. The securities
issued in each of the foregoing  transactions were offered and sold in  reliance
on an exemption from registration under Regulation D promulgated under the Act.
 
    On  November  9,  1995,  Telecom  sold 61,640  shares  of  Telecom  Series D
preferred stock  (which  convert  into  801,320  shares  of  Common  Stock  upon
completion  of this  offering) for  $2,000,000 in  a private  placement. Telecom
simultaneously redeemed  807,924 shares  of Telecom  common stock  from LHC  for
$2,000,000. In connection with the February 1996 Reorganization described below,
LHC  granted to  the holders  of Telecom Series  D preferred  stock a contingent
option to purchase  400,634 shares of  Telecom common stock  at a nominal  price
(the  "Series  D/LHC  Option"), which  option  expires upon  completion  of this
offering.
 
    On November  13,  1995, Global  Private  Equity II,  L.P.,  Advent  Partners
Limited  Partnership and Advent  International Investors II  L.P. each a limited
partnership  controlled  by  Advent  International  Corporation,  (collectively,
"Advent")  purchased  for an  aggregate of  $5,000,000, (i)  one share  of ART's
Series A Redeemable Preferred Stock for a purchase price of $50,000 and (ii) the
Company's 10%  Secured  Convertible Demand  Promissory  Notes in  the  aggregate
principal   amount  of  $4,950,000.   In  connection  with   the  February  1996
Reorganization, Advent  exchanged  such Preferred  Stock  and Note  for  232,826
shares of Telecom Series E preferred stock (which converts into 3,026,738 shares
of  Common Stock upon completion of this  offering), $0.001 par value per share.
The securities issued  in each of  the foregoing transactions  were offered  and
sold   in  reliance  on  an  exemption  from  registration  under  Regulation  D
promulgated under the Act. Advent made certain representations as to the  nature
of its investment and had adequate access to information about the Registrant.
 
    On February 2, 1996, Ameritech Development Corp. ("Ameritech") purchased for
an  aggregate of $2,500,000  48,893 shares of Telecom  Series F preferred stock,
par value $0.001 per share, (the "Ameritech Financing") convertible into 635,609
shares of Common Stock  upon completion of this  offering. In addition,  Telecom
entered  into the Ameritech  Strategic Distribution Agreement  and in connection
therewith granted to Ameritech a ten-year warrant to purchase 877,136 shares  of
Telecom  common stock exercisable at  a price of $.01  per share (the "Ameritech
Warrant"). The  securities issued  in each  of the  foregoing transactions  were
offered  and sold in reliance on an exemption from registration under Regulation
D promulgated under the  Act. Ameritech made certain  representations as to  the
nature  of  its investment  and  had adequate  access  to information  about the
Registrant.
 
BRIDGE NOTES
 
    On March 8, 1996, Telecom issued in a private placement $5,000,000 principal
amount of  two year,  10% unsecured  notes (the  "Bridge Notes")  and  five-year
warrants  to purchase up to  an aggregate of 1,100,000  shares of Telecom common
stock at  a  price of  $6.25  per share  (the  "Bridge Warrants")  to  investors
including:  (i) affiliates of J.C. Demetree, Jr. and Mark Demetree, directors of
the Company; (ii)  the Advent  Partnerships; and (iii)  Ameritech, who  invested
$700,000,  $725,000  and  $750,000  in the  Bridge  Notes  and  Bridge Warrants,
respectively.
 
                                      II-3
<PAGE>
EQUIPMENT FINANCING
 
    On April  1,  1996, CRA,  Inc.  ("CRA")  entered into  a  secured  equipment
financing  with Telecom (the "Equipment Financing")  for the purchase from P-Com
of 38  GHz  radio equipment.  To  evidence  its obligations  and  the  Equipment
Financing,  Telecom issued in favor of CRA a $2,445,000 promissory note, payable
in 24 monthly installments of $92,694 with a final payment equal to $642,305 due
April 1, 1998. The securities issued  in the foregoing transaction were  offered
and  sold  in reliance  on  an exemption  from  registration under  Regulation D
promulgated under the Act.
 
COMMCOCCC ACQUISITION
 
    On July 3, 1996, the Company entered into the CommcoCCC Agreement to acquire
129 38 GHz wireless  broadband authorizations from  CommcoCCC, Inc. in  exchange
for   16,500,000  shares  of   Common  Stock.  The   stockholders  of  CommcoCCC
simultaneously loaned  $3.0 million  on a  secured, subordinated  basis  bearing
interest  at  the  prime rate  and  payable  on September  30,  1996  and issued
three-year warrants to acquire 50,000 shares  of Common Stock at $15 per  share.
The  securities to be  issued in the  foregoing transaction will  be offered and
sold in reliance on a exemption from registration under Regulation D promulgated
under the Act.
 
ITEM 16.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 
    (a) Exhibits
 
    The following exhibits were delivered  with this Registration Statement,  or
will be delivered by amendment, for filing:
 
<TABLE>
<C>        <S>                                                                              <C>
      1-1  Underwriting Agreement.
      2-1  (a) Amended and Restated Certificate of Incorporation and Bylaws of Registrant.
           (b) Amendment to Amended and Restated Certificate of Incorporation.
           (c) Amended and Restated Certificate of Incorporation (to be effective prior to
            the consummation of the Offerings) and Restated and Amended Bylaws (effective
            on the date of the Prospectus) of Registrant.
      4-1  Specimen of Common Stock Certificate.*
      4-2  (a) Indenture.(2)
           (b) Specimen of Senior Discount Note. (See Exhibit 4-2(a)).
      4-3  Form of Lock-Up Agreement.
      4-4  Form of Warrant Agreement.(2)
      5-1  Opinion and Consent of Hahn & Hessen LLP, counsel for the Registrant, with
            respect to the Registrant's Common Stock and the Notes.*
      9-1  (a) Voting Trust Agreement.*
           (b) Form of Trustee Indemnification Agreement.*
           (c) Voting Agreement.*
           (d) Confidentiality Agreement.*
     10-1  Employment and Consulting Agreements.
           (a) Vernon L. Fotheringham, dated December 16, 1995.**
           (b) Steven D. Comrie, dated February 2, 1996.**
           (c) W. Theodore Pierson, Jr., dated May 8, 1995 and effective January 1,
            1995.**
           (d) I. Don Brown, dated February 16, 1996.**
           (e) Charles Menatti, dated March 8, 1996.**
           (f) James D. Miller, dated February 1, 1996.**
           (g) Thomas A. Grina, dated April 26, 1996.(1)
     10-2  (a) Second Amended and Restated Certificate of Incorporation and By-laws of
            Telecom (filed as Exhibit 2-1 to the Registration Statement on Form S-1 of the
            Company dated May 2, 1996).**
</TABLE>
 
                                      II-4
<PAGE>
<TABLE>
<C>        <S>                                                                              <C>
           (b) Certificate of Incorporation of ART Merger Corporation (to become the
            Certificate of Incorporation of Telecom upon the completion of the Merger).
     10-3  Form of Director Indemnification Agreement.**
     10-4  (a) Registrant's Equity Incentive Plan, as amended.
           (b) Form of Stock Option Agreement.*
     10-5  (a) Registrant's 1996 Non-Employee Directors Automatic Stock Option Plan.**
           (b) Form of Non-Employee Directors Stock Option Agreement.
     10-6  Stock Option Agreements.
           (a) Comrie Non-Qualified Stock Option Agreement.**
           (b) Comrie Incentive Stock Option Agreement.**
     10-7  Management Consulting Agreement with Landover Holdings Corporation, dated
            November 13, 1995.**
     10-8  (a)ART West Joint Venture Agreement dated April 4, 1995, with Extended
              Communications, Inc.**
           (b)Put/Call Agreement dated October 1, 1994, with Extended Communications,
              Inc.**
           (c)Services Agreement dated October 1, 1994, with Extended Communications,
              Inc.**
           (d)Amendment dated April 4, 1995 to the Put/Call Agreement dated October 1,
              1994, with Extended Communications, Inc.**
           (e)Asset Purchase Agreement dated June 24, 1996 with Extended Communications,
              Inc.
           (f) Management Agreement dated June 1, 1996 with ART West Partnership.
     10-9  (a)Put/Call Agreement dated September 1, 1994 with DCT Communications, Inc.**
           (b)Services Agreement dated September 1, 1994 with DCT Communications, Inc.**
           (c)Term Sheet dated April 26, 1996 with DCT.**
           (d) Purchase Agreement with DCT dated July 1, 1996.*
           (e) Amendment to Services Agreement dated June 1996 with DCT.
    10-10  (a)Asset Purchase Agreement dated April 4, 1995 with EMI Communications
              Corporation.**
           (b)$1,500,000 Nonnegotiable and Nontransferable Promissory Note.**
           (c)Maintenance Agreement dated November 14, 1995 with EMI Communications
              Corporation.**
           (d)Agreement dated November 14, 1995 with EMI Communications Corporations.**
    10-11  38 GHz Radio Links Purchase Agreement dated August 11, 1995 with P-Com, Inc.+**
    10-12  (a)Agreement dated May 25, 1995 with Telecom One.+**
           (b) Services Agreement dated April 24, 1996 with Telecom One.**
           (c) Asset Purchase Agreement and Management Agreement with Telecom One dated
            June 27, 1996.
    10-13  Agreement dated April 25, 1996 with GTE.**
    10-14  Software License Agreement dated March 29, 1996 with GTE.**
    10-15  Agreement dated July 12, 1995 with Southeast Research Partners, Inc.**
    10-16  Agreement dated March 1, 1995 with High Sky Limited Partnership, High Sky II
            Limited Partnership, Vernon L. Fotheringham, W. Theodore Pierson, Jr., and F.
            Thomas Tuttle.**
    10-17  Stock Purchase Agreement dated May 8, 1995 with Vernon L. Fotheringham, W.
            Theodore Pierson, Jr., High Sky Limited Partnership, High Sky II Limited
            Partnership, and Extended Communications, Inc.**
    10-18  (a)Purchase Agreement dated April 21, 1995 with Landover Holdings
              Corporation.**
           (b)Letter Agreement dated May 8, 1995 with the Demetrees, Telecom and Landover
              Holdings Corporation.**
           (c)Letter Agreement dated November 13, 1995 with Telecom, E2-2 Holdings, L.P.
              and the Demetrees.**
</TABLE>
 
                                      II-5
<PAGE>
<TABLE>
<C>        <S>                                                                              <C>
    10-19  Restated and Amended Stockholders' Agreement dated February 2, 1996 with
            Telecom and the stockholders of each of Telecom and the Company.**
    10-20  Second Restated and Amended Registration Rights Agreement dated July 3, 1996
            with Telecom and the stockholders of each of Telecom and the Company.
    10-21  Services Agreement dated May 8, 1995 with Telecom.**
    10-22  Option Agreement dated February 2, 1996 with Telecom.**
    10-23  (a)Securities Purchase Agreement dated November 13, 1995 with Telecom, Vernon
              Fotheringham, W. Theodore Pierson, Jr., the stockholders of Telecom named
              therein and the Advent Partnerships.**
           (b)Exchange Agreement dated February 2, 1996 with Telecom and the Advent
              Partnerships.**
    10-24  (a)Securities Purchase Agreement dated February 2, 1996 with Telecom and
              Ameritech Development Corporation ("Ameritech"), including letter of
              intent.**
           (b)Warrant issued on February 2, 1996 to Ameritech.**
           (c)Put/Call Agreement dated February 2, 1996 with Ameritech.**
    10-25  Strategic Distribution Agreement dated April 29, 1996 with Ameritech.**
    10-26  Restated and Amended Merger Agreement and Plan of Reorganization dated June 26,
            1996 between the Company and Telecom.
    10-27  (a)$2,445,000 Promissory Note in favor of CRA, Inc. ("CRA").**
           (b)Security Agreement with CRA (including UCC-1 Financing Statement).**
           (c)Indemnity Agreement.**
           (d) Form of Indemnity Warrant.**
    10-28  Memorandum of Terms of Development and Procurement Agreement with American
            Wireless with Extension Agreement dated April 25, 1996.**
    10-29  (a)Purchase Agreement dated April 26, 1996 with Harris Corporation Farinon
              Division ("Harris") (confidential treatment requested for certain terms).(1)
           (b)PCS Marketing Agreement dated April 26, 1996 with Harris (confidential
              treatment requested for certain terms).(1)
    10-30  Form of Subscription Agreement dated March 8, 1996, including Forms of Bridge
            Note and Bridge Warrant.
    10-31  (a) Asset Acquisition Agreement and Plan of Reorganization dated July 3, 1996
            with CommcoCCC, Inc.
           (b) Form of Note issued to Commco, L.L.C.
           (c) Form of Note issued to Columbia Capital Corporation.
           (d) Form of Warrant issued to Commco, L.L.C.
           (e) Form of Warrant issued to Columbia Capital Corporation.
           (f) Option Agreement dated July 3, 1996 with Commco, L.L.C.
           (g) Security Agreement dated June 27, 1996 with Columbia Capital Corporation.
           (h) Form of Noncompetition Agreement with CommcoCCC.
           (i) CommcoCCC Management Agreement dated July 3, 1996.
           (j) Right of First Offer Agreement dated July 3, 1996.
           (k) Engagement Letter with Montgomery Securities dated May 23, 1996.
    10-32  Letter of Intent dated April 29, 1996 with Helioss Communications Inc.
       11  Computation of Pro Forma Net Loss Per Share of Common Stock.
       21  Subsidiaries of the Registrant.
    23(a)  Consent of the Registrant's Independent Accountants.
    23(b)  Consent of the Registrant's Counsel will be contained in the Opinion of
            Counsel.*
</TABLE>
 
- ------------------------
 * To be filed by amendment.
 
** Previously filed.
+ Confidential treatment requested for the deleted portions of this document.
(1) Filed  with the Registration Statement on Form  S-1 of the Company dated May
    15, 1996 (SEC Reg. No. 333-03735) ("Unit Registration Statement").
 
(2) Filed with Amendment No. 1 to Unit Registration Statement.
 
                                      II-6
<PAGE>
ITEM 17.  UNDERTAKINGS.
 
    Insofar as indemnification for liabilities under the Act may be permitted to
directors, officers and  controlling person  of the Registrant  pursuant to  the
foregoing  provisions, or otherwise, the Registrant has been advised that in the
opinion of  the Commission  such  indemnification is  against public  policy  as
expressed in the Act and is, therefore, unenforceable. In the event that a claim
for  indemnification against  such liabilities  (other than  the payment  by the
Registrant of expenses incurred  or paid by a  director, officer or  controlling
person  of  the Registrant  in the  successful  defense of  any action,  suit or
proceeding) is  asserted by  such  director, officer  or controlling  person  in
connection  with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to  a  court  of  appropriate  jurisdiction  the  question  whether  such
indemnification  by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.
 
    The undersigned Registrant hereby undertakes to provide the Underwriters  at
the  closing  specified  in  the  Underwriting  Agreement  certificates  in such
denomination and registered  in such names  as required by  the Underwriters  to
permit prompt delivery to each purchaser.
 
    The undersigned Registrant hereby undertakes that:
 
        (1)  For  purposes  of  determining any  liability  under  the  Act, the
    information omitted  from the  form  of prospectus  filed  as part  of  this
    Registration Statement in reliance upon Rule 430A and contained in a form of
    prospectus  filed by  the Registrant pursuant  to Rule 424(b)(1)  or (4), or
    497(h) under  the  Act shall  be  deemed to  be  part of  this  Registration
    Statement as of the time it was declared effective.
 
        (2)  For the purposes  of determining any liability  under the Act, each
    post-effective amendment that contains a form of prospectus shall be  deemed
    to  be  a  new Registration  Statement  relating to  the  securities offered
    therein, and the offering of such securities at that time shall be deemed to
    be the initial bona fide offering thereof.
 
    The undersigned Registrant hereby undertakes:
 
        (1) To file, during any period in which offers or sales are being  made,
    a post-effective amendment to this Registration Statement;
 
            (i)  To include any  prospectus required by  Section 10(a)(3) of the
       Act;
 
           (ii) To reflect in the prospectus  any facts or events arising  after
       the  effective date  of the  Registration Statement  (or the  most recent
       post-effective  amendment  thereof)   which,  individually   or  in   the
       aggregate, represent a fundamental change in the information set forth in
       the Registration Statement;
 
           (iii) To include any material information with respect to the plan of
       distribution  not previously  disclosed in the  Registration Statement or
       any material change to such information in the Registration Statement;
 
        (2) That, for the  purpose of determining any  liability under the  Act,
    each  such post-effective amendment shall be deemed to be a new registration
    statement relating to the  securities offered therein,  and the offering  of
    such  securities at that  time shall be  deemed to be  the initial bona fide
    offering thereof.
 
        (3) To remove from registration  by means of a post-effective  amendment
    any   of  the  securities  being  registered  which  remain  unsold  at  the
    termination of the offering.
 
                                      II-7
<PAGE>
                                   SIGNATURES
 
    Pursuant  to the requirements of the  Securities Act of 1933, the Registrant
has duly caused this Registration  Statement to be signed  on its behalf by  the
undersigned,  thereunto duly authorized  in the City  of New York,  State of New
York, on July 2, 1996.
 
                                          Advanced Radio Technologies
                                          Corporation
 
                                          By:     /s/ VERNON L. FOTHERINGHAM
 
                                             -----------------------------------
                                                   Vernon L. Fotheringham
                                                CHAIRMAN AND CHIEF EXECUTIVE
                                                           OFFICER
 
<TABLE>
<C>                                                     <S>                                        <C>
                      SIGNATURES                                          TITLE                         DATE
- ------------------------------------------------------  -----------------------------------------  --------------
 
                 /s/ VERNON L. FOTHERINGHAM
     -------------------------------------------        Chairman, Chief Executive Officer and       July 2, 1996
                Vernon L. Fotheringham                   Director
 
                /s/ W. THEODORE PIERSON, JR.
     -------------------------------------------        Executive Vice President, General Counsel   July 2, 1996
               W. Theodore Pierson, Jr.                  and Director
 
                       /s/ MATTHEW C. GOVE
     -------------------------------------------        Director                                    July 2, 1996
                   Matthew C. Gove
 
                       /s/ THOMAS A. GRINA
     -------------------------------------------        Executive Vice President and Chief          July 2, 1996
                   Thomas A. Grina                       Financial Officer
</TABLE>
 
                                      II-8
<PAGE>
                               POWER OF ATTORNEY
 
    KNOW ALL MEN  BY THESE PRESENTS,  that each person  whose signature  appears
below  hereby  severally constitutes  and  appoints Vernon  L.  Fotheringham and
Thomas A. Grina,  and each of  them, his true  and lawful attorneys-in-fact  and
agents,  with full power of substitution and  resubstitution, for him and in his
name, place and stead, in any and all capacities, to sign any and all amendments
(including post-effective  amendments) to  this Registration  Statement and  all
documents  relating thereto, including one  or more registration statements that
may be filed to register additional securities for an offering pursuant to  Rule
462(b) under the Securities Act, and to file the same, with all exhibits hereto,
and  other documents in  connection therewith, with  the Securities and Exchange
Commission, granting  unto said  attorneys-in-fact and  agents, full  power  and
authority  to do and perform each and every act and thing necessary or advisable
to be done in and about the premises, as fully to all intents and purposes as he
might or  could do  in person,  hereby ratifying  and confirming  all that  said
attorneys-in-fact  and agents, or his substitute or substitutes, may lawfully do
or cause to be done in virtue hereof.
 
    Pursuant  to  the  requirements  of   the  Securities  Act  of  1933,   this
Registration  Statement has  been signed below  by the following  persons in the
capacities and on the dates indicated.
 
<TABLE>
<C>                                                     <S>                                        <C>
                      SIGNATURES                        TITLE                                           DATE
- ------------------------------------------------------  -----------------------------------------  --------------
 
                 /s/ VERNON L. FOTHERINGHAM
     -------------------------------------------        Chairman, Chief Executive Officer and       July 2, 1996
                Vernon L. Fotheringham                   Director
 
                /s/ W. THEODORE PIERSON, JR.
     -------------------------------------------        Executive Vice President, General Counsel   July 2, 1996
               W. Theodore Pierson, Jr.                  and Director
 
                       /s/ MATTHEW C. GOVE
     -------------------------------------------        Director                                    July 2, 1996
                   Matthew C. Gove
</TABLE>
 
                                      II-9
<PAGE>
                               INDEX TO EXHIBITS
 
<TABLE>
<CAPTION>
EXHIBITS                                          DESCRIPTION                                           PAGE
- ----------  ----------------------------------------------------------------------------------------  ---------
<C>         <S>                                                                                       <C>
       1-1  Underwriting Agreement.
       2-1  (a) Amended and Restated Certificate of Incorporation and Bylaws of Registrant.
            (b) Amendment to Amended and Restated Certificate of Incorporation.
            (c) Amended and Restated Certificate of Incorporation (to be effective prior to the
             consummation of the Offerings) and Restated and Amended Bylaws (effective on the date
             of the Prospectus) of Registrant.
       4-1  Specimen of Common Stock Certificate.*
       4-2  (a) Indenture.(2)
            (b) Specimen of Senior Discount Note. (See Exhibit 4-2(a)).
       4-3  Form of Lock-Up Agreement.
       4-4  Form of Warrant Agreement.(2)
       5-1  Opinion and Consent of Hahn & Hessen LLP, counsel for the Registrant, with respect to
             the Registrant's Common Stock and the Notes.*
       9-1  (a) Voting Trust Agreement.*
            (b) Form of Trustee Indemnification Agreement.*
            (c) Voting Agreement.*
            (d) Confidentiality Agreement.*
      10-1  Employment and Consulting Agreements.
            (a) Vernon L. Fotheringham, dated December 16, 1995.**
            (b) Steven D. Comrie, dated February 2, 1996.**
            (c) W. Theodore Pierson, Jr., dated May 8, 1995 and effective January 1, 1995.**
            (d) I. Don Brown, dated February 16, 1996.**
            (e) Charles Menatti, dated March 8, 1996.**
            (f) James D. Miller, dated February 1, 1996.**
            (g) Thomas A. Grina, dated April 26, 1996.(1)
      10-2  (a) Second Amended and Restated Certificate of Incorporation and By-laws of Telecom
             (filed as Exhibit 2-1 to the Registration Statement on Form S-1 of the Company dated
             May 2, 1996).**
            (b) Certificate of Incorporation of ART Merger Corporation (to become the Certificate of
             Incorporation of Telecom upon the completion of the Merger).
      10-3  Form of Director Indemnification Agreement.**
      10-4  (a) Registrant's Equity Incentive Plan, as amended.
            (b) Form of Stock Option Agreement.*
      10-5  (a) Registrant's 1996 Non-Employee Directors Automatic Stock Option Plan.**
            (b) Form of Non-Employee Directors Stock Option Agreement.
      10-6  Stock Option Agreements.
            (a) Comrie Non-Qualified Stock Option Agreement.**
            (b) Comrie Incentive Stock Option Agreement.**
      10-7  Management Consulting Agreement with Landover Holdings Corporation, dated November 13,
             1995.**
      10-8  (a)ART West Joint Venture Agreement dated April 4, 1995, with Extended Communications,
               Inc.**
            (b)Put/Call Agreement dated October 1, 1994, with Extended Communications, Inc.**
            (c)Services Agreement dated October 1, 1994, with Extended Communications, Inc.**
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
EXHIBITS                                          DESCRIPTION                                           PAGE
- ----------  ----------------------------------------------------------------------------------------  ---------
            (d)Amendment dated April 4, 1995 to the Put/Call Agreement dated October 1, 1994, with
               Extended Communications, Inc.**
<C>         <S>                                                                                       <C>
            (e)Asset Purchase Agreement dated June 24, 1996 with Extended Communications, Inc.
            (f) Management Agreement dated June 1, 1996 with ART West Partnership.
      10-9  (a)Put/Call Agreement dated September 1, 1994 with DCT Communications, Inc.**
            (b)Services Agreement dated September 1, 1994 with DCT Communications, Inc.**
            (c)Term Sheet dated April 26, 1996 with DCT.**
            (d) Purchase Agreement with DCT dated July 1, 1996.*
     10-10  (a)Asset Purchase Agreement dated April 4, 1995 with EMI Communications Corporation.**
            (b)$1,500,000 Nonnegotiable and Nontransferable Promissory Note.**
            (c)Maintenance Agreement dated November 14, 1995 with EMI Communications Corporation.**
            (d)Agreement dated November 14, 1995 with EMI Communications Corporations.**
            (e) Amendment to Services Agreement dated June 1996 with DCT.
     10-11  38 GHz Radio Links Purchase Agreement dated August 11, 1995 with P-Com, Inc.+**
     10-12  (a)Agreement dated May 25, 1995 with Telecom One.+**
            (b) Services Agreement dated April 24, 1996 with Telecom One.**
            (c) Asset Purchase Agreement and Management Agreement with Telecom One dated June 27,
             1996.
     10-13  Agreement dated April 25, 1996 with GTE.**
     10-14  Software License Agreement dated March 29, 1996 with GTE.**
     10-15  Agreement dated July 12, 1995 with Southeast Research Partners, Inc.**
     10-16  Agreement dated March 1, 1995 with High Sky Limited Partnership, High Sky II Limited
             Partnership, Vernon L. Fotheringham, W. Theodore Pierson, Jr., and F. Thomas Tuttle.**
     10-17  Stock Purchase Agreement dated May 8, 1995 with Vernon L. Fotheringham, W. Theodore
             Pierson, Jr., High Sky Limited Partnership, High Sky II Limited Partnership, and
             Extended Communications, Inc.**
     10-18  (a)Purchase Agreement dated April 21, 1995 with Landover Holdings Corporation.**
            (b)Letter Agreement dated May 8, 1995 with the Demetrees, Telecom and Landover Holdings
               Corporation.**
            (c)Letter Agreement dated November 13, 1995 with Telecom, E2-2 Holdings, L.P. and the
               Demetrees.**
     10-19  Restated and Amended Stockholders' Agreement dated February 2, 1996 with Telecom and the
             stockholders of each of Telecom and the Company.**
     10-20  Second Restated and Amended Registration Rights Agreement dated July 3, 1996 with
             Telecom and the stockholders of each of Telecom and the Company.
     10-21  Services Agreement dated May 8, 1995 with Telecom.**
     10-22  Option Agreement dated February 2, 1996 with Telecom.**
     10-23  (a)Securities Purchase Agreement dated November 13, 1995 with Telecom, Vernon
               Fotheringham, W. Theodore Pierson, Jr., the stockholders of Telecom named therein and
               the Advent Partnerships.**
            (b)Exchange Agreement dated February 2, 1996 with Telecom and the Advent Partnerships.**
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
EXHIBITS                                          DESCRIPTION                                           PAGE
- ----------  ----------------------------------------------------------------------------------------  ---------
     10-24  (a)Securities Purchase Agreement dated February 2, 1996 with Telecom and Ameritech
               Development Corporation ("Ameritech"), including letter of intent.**
<C>         <S>                                                                                       <C>
            (b)Warrant issued on February 2, 1996 to Ameritech.**
            (c)Put/Call Agreement dated February 2, 1996 with Ameritech.**
     10-25  Strategic Distribution Agreement dated April 29, 1996 with Ameritech.**
     10-26  Restated and Amended Merger Agreement and Plan of Reorganization dated June 26, 1996
             between the Company and Telecom.
     10-27  (a)$2,445,000 Promissory Note in favor of CRA, Inc. ("CRA").**
            (b)Security Agreement with CRA (including UCC-1 Financing Statement).**
            (c)Indemnity Agreement.**
            (d) Form of Indemnity Warrant.**
     10-28  Memorandum of Terms of Development and Procurement Agreement with American Wireless with
             Extension Agreement dated April 25, 1996.**
     10-29  (a)Purchase Agreement dated April 26, 1996 with Harris Corporation Farinon Division
               ("Harris") (confidential treatment requested for certain terms).(1)
            (b)PCS Marketing Agreement dated April 26, 1996 with Harris (confidential treatment
               requested for certain terms).(1)
     10-30  Form of Subscription Agreement dated March 8, 1996, including Forms of Bridge Note and
             Bridge Warrant.
     10-31  (a) Asset Acquisition Agreement and Plan of Reorganization dated July 3, 1996 with
             CommcoCCC, Inc.
            (b) Form of Note issued to Commco, L.L.C.
            (c) Form of Note issued to Columbia Capital Corporation.
            (d) Form of Warrant issued to Commco, L.L.C.
            (e) Form of Warrant issued to Columbia Capital Corporation.
            (f) Option Agreement dated July 3, 1996 with Commco, L.L.C.
            (g) Security Agreement dated June 27, 1996 with Columbia Capital Corporation.
            (h) Form of Noncompetition Agreement with CommcoCCC.
            (i) CommcoCCC Management Agreement dated July 3, 1996.
            (j) Right of First Offer Agreement dated July 3, 1996.
            (k) Engagement Letter with Montgomery Securities dated May 23, 1996.
     10-32  Letter of Intent dated April 29, 1996 with Helioss Communications Inc.
        11  Computation of Pro Forma Net Loss Per Share of Common Stock.
        21  Subsidiaries of the Registrant.
     23(a)  Consent of the Registrant's Independent Accountants.
     23(b)  Consent of the Registrant's Counsel will be contained in the Opinion of Counsel.*
</TABLE>
 
- ------------------------
 * To be filed by amendment.
 
** Previously filed.
+ Confidential treatment requested for the deleted portions of this document.
(1) Filed  with the Registration Statement on Form  S-1 of the Company dated May
    15, 1996 (SEC Reg. No. 333-03735) ("Unit Registration Statement").
 
(2) Filed with Amendment No. 1 to Unit Registration Statement.

<PAGE>


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




                          ADVANCED RADIO TELECOM CORP.




                       __________ Shares of Common Stock




                             UNDERWRITING AGREEMENT




                         Dated as of _____________, 1996





                              MONTGOMERY SECURITIES

                  DEUTSCHE MORGAN GRENFELL/C. J. LAWRENCE INC.






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

<PAGE>


                   _______________ SHARES

                ADVANCED RADIO TELECOM CORP.

                        COMMON STOCK


                   UNDERWRITING AGREEMENT



__________, 1996



MONTGOMERY SECURITIES
DEUTSCHE MORGAN GRENFELL/C. J. LAWRENCE INC.
  As Representatives of the several Underwriters
c/o MONTGOMERY SECURITIES
600 Montgomery Street
San Francisco, California  94111

Dear Sirs:

     SECTION 1.     INTRODUCTORY.  Advanced Radio Telecom Corp., f/k/a Advanced
Radio Technologies Corporation, a Delaware corporation (the "COMPANY"), proposes
to issue and sell __________ shares of its authorized but unissued common stock,
par value $.001 per share (the "COMMON STOCK"), to the several underwriters
named in Schedule A annexed hereto (the "UNDERWRITERS"), for whom you are acting
as representatives (the "REPRESENTATIVES").  Said aggregate of __________ shares
are herein called the "FIRM COMMON SHARES."  In addition, the Company proposes
to grant to the Underwriters an option to purchase up to __________ additional
shares of Common Stock (the "OPTIONAL COMMON SHARES"), as provided in Section 4
hereof.  The Firm Common Shares and, to the extent such option is exercised, the
Optional Common Shares are hereinafter collectively referred to as the "COMMON
SHARES."  This Agreement, the Price Determination Agreement attached hereto as
Exhibit B and the Lock-Up Agreement (as defined) are herein collectively
referred to as the "OPERATIVE DOCUMENTS."

     You have advised the Company that the Underwriters propose to make a public
offering of their respective portions of the Common Shares (the "OFFERING") on
the effective date of the registration statement hereinafter referred to, or as
soon thereafter as in your judgment is advisable.  Concurrently with the
Offering, the Company is offering, pursuant to a separate prospectus, units
consisting of Senior Discount Notes due 2006 and warrants to purchase Common
Stock (the "UNIT OFFERING" and, together with the Offering, the "OFFERINGS").
In addition, prior to consummation of the Offerings, (i) Advanced Radio Telecom
Corp. ("ART") will merge with and into ART Merger Corporation, a subsidiary of
the Company, (ii) the Company will amend its certificate of incorporation to
change its name to "Advanced Radio Telecom Corp." and (iii) ART Merger
Corporation will amend its certificate of incorporation to

                                        1
<PAGE>

change its name to ART Licenses Corporation ("ART LICENSES") (the "MERGER" and,
together with the Offerings, the "TRANSACTIONS").  Unless the context otherwise
requires, the "Company" shall refer to the Company after giving effect to the
Merger.  References to "subsidiaries" of the Company shall be deemed to include
ART.

     The Company hereby confirms its agreements with respect to the purchase of
the Common Shares by the Underwriters as follows:

     SECTION 2.   REPRESENTATIONS AND WARRANTIES OF THE COMPANY.  The Company
hereby represents and warrants to the several Underwriters that:

     (a)  A registration statement on Form S-1 (File No. 333-4388) with respect
to the Common Shares has been prepared by the Company in conformity with the
requirements of the Securities Act of 1933, as amended (the "ACT"), and the
rules and regulations (the "RULES AND REGULATIONS") of the Securities and
Exchange Commission (the "COMMISSION") thereunder, and has been filed with the
Commission.  The Company has prepared and has filed or proposes to file prior to
the effective date of such registration statement an amendment or amendments to
such registration statement, which amendment or amendments have been or will be
similarly prepared.  There have been delivered to you three signed copies of
such registration statement and amendments, together with three copies of each
exhibit filed therewith.  Conformed copies of such registration statement and
amendments (but without exhibits) and of the related preliminary prospectus have
been delivered to you in such reasonable quantities as you have requested for
each of the Underwriters.  The Company will next file with the Commission one of
the following: (i) prior to effectiveness of such registration statement, a
further amendment thereto, including the form of final prospectus, (ii) a final
prospectus in accordance with Rules 430A and 424(b) of the Rules and Regulations
or (iii) a term sheet (the "TERM SHEET") as described in and in accordance with
Rules 434 and 424(b) of the Rules and Regulations.  As filed, the final
prospectus, if one is used, or the Term Sheet and Preliminary Prospectus, if a
final prospectus is not used, shall include all Rule 430A Information and,
except to the extent that you shall agree in writing to a modification, shall be
in all substantive respects in the form furnished to you prior to the date and
time that this Agreement was executed and delivered by the parties hereto, or,
to the extent not completed at such date and time, shall contain only such
specific additional information and other changes (beyond that contained in the
latest preliminary prospectus) as the Company shall have previously advised you
in writing would be included or made therein.

     The term "REGISTRATION STATEMENT" as used in this Agreement shall mean such
registration statement at the time such registration statement becomes effective
and, in the event any post-effective amendment thereto becomes effective prior
to the First Closing Date (as hereinafter defined), shall also mean such
registration statement as so amended; PROVIDED, HOWEVER, that such term shall
also include (i) all Rule 430A Information deemed to be included in such
registration statement at the time such registration statement becomes effective
as provided by Rule 430A of the Rules and Regulations and (ii) any registration
statement filed pursuant to Rule 462(b) of the Rules and Regulations relating to
the Common Shares.  The term "PRELIMINARY PROSPECTUS" shall mean any preliminary
prospectus referred to in the preceding paragraph and any preliminary prospectus
included in the Registration Statement at the time it becomes effective that
omits Rule 430A Information.  The term "PROSPECTUS" as used in this Agreement
shall mean either (i) the prospectus relating to the Common Shares in the form
in which it is first filed with the Commission pursuant to Rule 424(b) of the
Rules and Regulations or, (ii) if a Term Sheet is not used and no filing
pursuant to Rule 424(b) of the Rules and Regulations is required, shall mean the
form of final prospectus included in the Registration Statement at the time such
registration statement becomes effective or (iii) if a Term Sheet is used, the
Term Sheet in the form in which it is

                                        2
<PAGE>

first filed with the Commission pursuant to Rule 424(b) of the Rules and
Regulations, together with the Preliminary Prospectus included in the
Registration Statement at the time it becomes effective.  The term "RULE 430A
INFORMATION" means information with respect to the Common Shares and the
Offering permitted to be omitted from the Registration Statement when it becomes
effective pursuant to Rule 430A of the Rules and Regulations.

     (b)  The Commission has not issued any order preventing or suspending the
use of any Preliminary Prospectus, and each Preliminary Prospectus has conformed
in all material respects to the requirements of the Act and the Rules and
Regulations and, as of its date, has not included any untrue statement of a
material fact or omitted to state a material fact necessary to make the
statements therein, in the light of the circumstances under which they were
made, not misleading; and at the time the Registration Statement becomes
effective, and at all times subsequent thereto up to and including each Closing
Date hereinafter mentioned, the Registration Statement and the Prospectus, and
any amendments or supplements thereto, will contain all material statements and
information required to be included therein by the Act and the Rules and
Regulations and will in all material respects conform to the requirements of the
Act and the Rules and Regulations, and neither the Registration Statement nor
the Prospectus, nor any amendment or supplement thereto, will include any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading;
PROVIDED, HOWEVER, no representation or warranty contained in this Section 2(b)
shall be applicable to information contained in or omitted from any Preliminary
Prospectus, the Registration Statement, the Prospectus or any such amendment or
supplement in reliance upon and in conformity with written information furnished
to the Company by or on behalf of any Underwriter, directly or through the
Representatives, specifically for use in the preparation thereof.

     (c)  No action has been taken and no local, state or Federal law, statute,
ordinance, rules, regulation, requirement, judgment or court decree has been
enacted, adopted or issued by any governmental agency that prevents the issuance
of the Common Shares or prevents or suspends the use of the Prospectus; no
jurisdiction, restraining order or order of any nature by a Federal or state
court of competent jurisdiction has been issued that prevents the issuance of
the Common Shares or prevents or suspends the sale of the Common Shares in any
jurisdiction referred to in Section 5(f) hereof; and every request of any
securities authority or agency of any jurisdiction for additional information
has been complied with in all material respects.

     (d)  There are no contracts or other documents required to be described in
the Registration Statement or to be filed as exhibits to the Registration
Statement by the Act or by the Rules and Regulations which have not been
described or filed as required.  The contracts so described in the Prospectus
are accurate and complete, and all such contracts are in full force and effect
on the date hereof.  Neither the Company nor any of its subsidiaries or, to the
best of the Company's knowledge, any other party is in breach of or default
under any such contract.

     (e)  Each of the Company and its subsidiaries has been duly formed as a
corporation and is validly existing in good standing under the laws of its
jurisdiction of incorporation and has all requisite corporate power and
authority to own, lease and operate its properties and to conduct its business
as described in the Prospectus.  Each of the Company and its subsidiaries is
duly qualified to do business and is in good standing as a foreign corporation
in each jurisdiction in which the nature of its business or its ownership or
leasing of property requires such qualification, except where the failure to be
so qualified would not have, either individually or in the aggregate, a material
adverse effect on the assets, properties, business, management, earnings, net
worth, results of operations, condition (financial or otherwise) or business
prospects of the Company and its subsidiaries, taken as a whole.  No proceeding

                                        3
<PAGE>

has been instituted in any such jurisdiction, revoking, limiting or curtailing,
or seeking to revoke, limit or curtail, such power and authority or
qualification.

     (f)  ART Licenses is the only subsidiary of the Company.  The Company owns
all of the outstanding capital stock of ART Licenses; all such capital stock has
been duly authorized and validly issued and is fully paid and nonassessable,
free and clear of any security interest, claim, lien, encumbrance or adverse
interest of any nature; and all of such capital stock was not issued in
violation of any preemptive or similar rights.  There are no outstanding
subscriptions, rights, warrants, calls, commitments of sale or options to
acquire, or instruments convertible into or exchangeable for, any such shares of
capital stock or other equity interest of ART Licenses.

     (g)  The Company and its subsidiaries do not have any ownership interest in
any joint venture, other than the Company's 50% ownership interest in ART West
Joint Venture, a Delaware partnership owned by the Company and Extended
Communications, Inc. ("ART WEST").

     (h)  Prior to consummation of the Transactions, the Company and ART have
authorized and outstanding capital stock as set forth in Exhibit A hereto.  All
such issued and outstanding shares of capital stock of the Company and ART have
been duly authorized and validly issued, are fully paid and non-assessable and
were not issued in violation of any preemptive or similar rights.  The shares of
capital stock of ART owned by the Company prior to completion of the Merger are
free and clear of any security interest, claim, lien, encumbrance or adverse
interest of any nature.  Upon consummation of the Transactions, the Company will
have authorized and outstanding capital stock as set forth in Exhibit B hereto
and an authorized and outstanding capitalization as set forth in the Prospectus
under the caption "Capitalization."  All such issued and outstanding shares of
capital stock of the Company will have been duly authorized and validly issued,
will be fully paid and non-assessable and will not have been issued in violation
of any preemptive or similar rights.  Except as disclosed in the Prospectus,
there are, and there will be, no outstanding subscriptions, rights, warrants,
calls, commitments of sale or options to acquire, or instruments convertible
into or exchangeable for, any capital stock of the Company or ART  The
description of the Company's stock option, stock bonus and other stock plans or
arrangements, and the options or other rights granted and exercised thereunder,
set forth in the Prospectus accurately and fairly presents the information
required to be shown with respect to such plans, arrangements, options and
rights.

     (i)  The Company has all requisite corporate power and authority to enter
into the Operative Documents and to perform the transactions contemplated hereby
and thereby.  Each of the Operative Documents has been duly authorized, executed
and delivered by the Company and constitutes a legally valid and binding
obligation of the Company, enforceable against the Company in accordance with
its terms.  No approval, authorization, order, consent, registration, filing,
qualification, license or permit of or with any court, regulatory,
administrative or other governmental body is required for the execution and
delivery of this Agreement by the Company or the consummation of the
transactions contemplated by this Agreement, except such as have been obtained
and are in full force and effect under the Act and such as may be required under
applicable Blue Sky laws in connection with the purchase and distribution of the
Common Shares by the Underwriters and the clearance of such offering with the
NASD.

     (j)  The Common Shares to be sold by the Company have been duly authorized
and, when issued, delivered and paid for in the manner set forth in this
Agreement, will be duly authorized, validly issued, fully paid and
nonassessable, and will conform to the description thereof contained in the
Prospectus.  No preemptive rights or other rights to subscribe for or purchase
exist with respect to the

                                        4
<PAGE>

issuance and sale of the Common Shares by the Company pursuant to this
Agreement.  No stockholder of the Company has any right which has not been
waived to require the Company to register the sale of any shares owned by such
stockholder under the Act in the Offering contemplated by this Agreement.  No
further approval or authority of the stockholders or the board of directors of
the Company (the "BOARD OF DIRECTORS") will be required for the issuance and
sale of the Common Shares to be sold by the Company as contemplated herein.

     (k)  None of the execution, delivery and performance of the Operative
Documents by the Company, the compliance by the Company with all of the
provisions hereof and thereof, the issuance and sale of the Common Shares, the
consummation by the Company and its subsidiaries of the Transactions and the
transactions contemplated hereby and thereby (i) require any consent, approval,
authorization or other order of or filing, registration, qualification, license
or permit of or with, any court, regulatory body, administrative agency or other
governmental body (including, without limitation, the Federal Communications
Commission (the "FCC")), other than those that have been obtained and are in
full force and effect, or (ii) violate, conflict with, or constitute a breach of
any of the terms or provisions of, or a default under (or an event that with
notice or the lapse of time, or both, would constitute a default), or require
consent under, or result in the imposition of a lien or encumbrance on any
properties of the Company and its subsidiaries pursuant to (A) the charter or
bylaws of the Company or any of its subsidiaries, (B) any bond, debenture, note,
mortgage, deed of trust or other agreement, indenture or other instrument to
which or by which any of them is a party or by which any of them or any of their
respective property is or may be bound, (C) any local, state or Federal law,
statute, ordinance, rule, regulation or requirement (including, without
limitation, the Communications Act of 1934, as amended by the Telecommunications
Act of 1996 (the "TELECOMMUNICATIONS ACT"), the rules and regulations of the FCC
and the environmental laws, statutes, ordinances, rules or regulations)
applicable to the Company, any of its subsidiaries or any of their respective
assets or properties or (D) any judgment, order or decree of any court or
governmental agency or authority having jurisdiction over the Company, any of
its subsidiaries or any of their assets or properties, that, in the case of
clauses (B), (C) and (D), (x) would reasonably be expected, either individually
or in the aggregate, to result in a material adverse effect on the assets,
properties, business, management, earnings, net worth, results of operations,
condition (financial or otherwise) or business prospects of the Company and its
subsidiaries, taken as a whole, (y) would materially interfere with or adversely
affect the issuance of the Common Shares or the consummation of the Transactions
or (z) in any manner draw into question the validity of any of the Operative
Documents (any of the events set forth in clauses (x), (y) or (z), a "MATERIAL
ADVERSE EFFECT").

     (l)  Neither the Company  nor any of its subsidiaries is or, after giving
effect to the Transactions, will be (i) in violation of its charter or bylaws,
(ii) in default in the performance of any material obligation, agreement or
condition contained in any bond, debenture, note or any other evidence of
indebtedness or in any other agreement, indenture or instrument material to the
conduct of the business of the Company and its subsidiaries, taken as a whole,
to which any of them is a party, or by which any of their respective properties
is bound or (iii) in violation of any local, state or Federal law, statute,
ordinance, rule, regulation, requirement, judgment or court decree (including,
without limitation, the Telecommunications Act and the rules and regulations of
the FCC and environmental laws, statutes, ordinances, rules, regulations,
judgments or court decrees) applicable to any of them or any of their respective
assets or properties (whether owned or leased), other than, in the case of
clauses (ii) and (iii), any default or violation that could not reasonably be
expected to have a Material Adverse Effect.  There exists no condition that,
with notice, the passage of time or otherwise, would constitute a default under
any such document or instrument that could be expected to have a Material
Adverse Effect.

                                        5
<PAGE>

     (m)  There is (i) no action, suit or proceeding before or by any court,
arbitrator or governmental agency, body or official, domestic or foreign, now
pending or threatened or contemplated to which the Company or any of its
subsidiaries is or may be a party or to which the business or property of any of
them is subject, (ii) no local, state or Federal law, statute, ordinance, rule,
regulation, requirement, judgment or court decree (including, without
limitation, the Telecommunications Act and the rules and regulations of the FCC)
or order has been enacted, adopted or issued by any governmental agency or, to
the best of the Company's knowledge, that has been proposed by any governmental
body or (iii) no injunction, restraining order or order of any nature by a
Federal or state court or foreign court of competent jurisdiction to which the
Company, any of its subsidiaries or their business, assets, or property are, or
could reasonably be expected to be, subject.

     (n)  Each of the Company and its subsidiaries has (i) good and marketable
title, free and clear of all liens, claims, encumbrances and restrictions,
except for liens for taxes not yet due and payable and other liens not material
to the business, prospects, financial condition or results of operations of the
Company and its subsidiaries, taken as a whole, to all property and assets
described in the Registration Statement as currently being owned by each of the
Company and its subsidiaries and (ii) all licenses, certificates, permits,
authorizations, approvals, franchises and other rights from, and has made all
declarations and filings with, all Federal, state and local authorities
(including, without limitation, the FCC), all self-regulatory authorities and
all courts and other tribunals (each an "AUTHORIZATION") necessary to engage in
the business as presently and to be conducted by either of them in the manner
described in the Prospectus, except as described in the Prospectus.  All such
Authorizations are valid and in full force and effect and each of the Company
and its subsidiaries is in compliance with the terms and conditions of all such
Authorizations and with the rules and regulations of the regulatory authorities
having jurisdictions with respect thereto.  All leases to which the Company or
any of its subsidiaries is a party are valid and binding, and no default has
occurred or is continuing thereunder which could reasonably be expected to
result in a Material Adverse Effect.  Each of the Company and its subsidiaries
enjoys peaceful and undisturbed possession under all such Leases to which it is
a party as lessee or as assignee of lessee with such exceptions as do not
materially interfere with the use made by the Company or its subsidiaries.

     (o)  Each of the Company and its subsidiaries has such permits, licenses,
franchises, trademarks and authorizations of governmental or regulatory
authorities ("PERMITS") as are necessary to own, lease and operate their
respective properties and to conduct their respective business in the manner
described in the Prospectus.  Each of the Company and its subsidiaries has
fulfilled and performed all of its material obligations with respect to such
Permits and no event has occurred which allows, or after notice or lapse of time
would allow, revocation or termination thereof or result in any other material
impairment of the rights of the holder of any such Permit, except for any such
impairments which would not, individually or in the aggregate, have a Material
Adverse Effect.  Except as described in the Prospectus, such Permits contain no
restrictions that are materially burdensome to the Company and its subsidiaries,
taken as a whole.

     (p)  Except as described in the Prospectus, (i) the Company and its
subsidiaries own, possess or have the right to employ or have applied for all
such Permits, licenses (including all FCC, state, local or other jurisdictional
regulatory licenses, franchises, trademarks and authorizations of governmental
or regulatory authorities ("LICENSES")), patents, patent rights, know-how
(including trade secrets and other unpatented and/or unpatentable proprietary or
confidential information, software, systems or procedures), inventions,
technical data and information (collectively with Licenses, the "INTELLECTUAL
PROPERTY") as are necessary to own, lease and operate their respective
properties and to conduct their respective business in the manner described in
the Prospectus, (ii) each of the Company and its subsidiaries has fulfilled and

                                        6
<PAGE>

performed all of its material obligations with respect to such Licenses and
other Intellectual Property and no event has occurred which allows, or after
notice or lapse of time would allow, revocation or termination thereof or result
in any other material impairment of the rights of the holder of any such
Intellectual Property, (iii) such Intellectual Property contain no restrictions
that are materially burdensome to the Company and its subsidiaries, taken as a
whole, and (iv) the use of the Intellectual Property in connection with the
business and operations of the Company and its subsidiaries does not infringe on
the rights of any person, except where such infringement would not have a
Material Adverse Effect.

     (q)  The Company and its subsidiaries have timely filed all renewal
applications with respect to all Licenses possessed by any of them.  No protests
or competing applications have been filed with respect to such renewal
applications, and nothing has come to the Company's or any of its subsidiaries'
attention that would lead them to conclude that such renewal applications will
not be granted by the appropriate regulatory agency or body in the ordinary
course.  The Company and its subsidiaries are authorized under the
Telecommunications Act, and the rules and regulations promulgated thereunder, to
continue to provide the services which are the subject of such renewal
applications during the pendency thereof.

     (r)  The development, implementation and operation of the 38 GHz wireless
broadband telecommunications services network as described, and in the markets
described, in the Prospectus will not (i) result in any violation of the
provisions of the charter or bylaws of the Company or any of its subsidiaries,
(ii) result in any violation of any applicable law, administrative regulation or
administrative or court decree (including, without limitation, the
Telecommunication Act, and the rules and regulations of the FCC and
environmental laws) or (iii) conflict with or constitute a breach or violation
of, or constitute a default under, or result in the creation or imposition of
any lien, charge or encumbrance upon any property or assets of the Company or
its subsidiaries pursuant to, any contract, indenture, mortgage, loan agreement,
note, lease or other instrument to which the Company or any of its subsidiaries
is a party or by which any of them may be bound, or to which any of their
property is subject, except, in the case of clauses (ii) and (iii) above, any
such violations, conflicts or breaches that would not individually or in the
aggregate, have a Material Adverse Effect.

     (s)  The business and operations conducted and proposed to be conducted by
the Company and its subsidiaries as described in the Prospectus are not
regulated by any public service or public utility commissions in the States in
which the Company and its subsidiaries conduct or propose to conduct such
business and operations as described in the Prospectus; and, subject to the
provisions of Section 332(c)(3) of the Telecommunications Act, neither the
Company nor any of its subsidiaries is or will be required to obtain any License
from any public service or public utility commission in any such State.

     (t)  None of the execution, delivery and performance of the Operative
Documents by the Company, the compliance by the Company with all of the
provisions hereof and thereof, the issuance and sale of the Common Shares, the
consummation by the Company and its subsidiaries of the Transactions and the
transactions contemplated hereby and thereby (i) require any consent, approval,
authorization or other order of or filing, registration, qualification, license
or permit of or with, the FCC, other than those that have been obtained and are
in full force and effect, or (ii) violate, conflict with, or constitute a breach
of any of the terms or provisions of, or a default under (or an event that with
notice or the lapse of time, or both, would constitute a default), or require
consent under, or result in the imposition of a lien or encumbrance on any
properties of the Company or any of its subsidiaries pursuant to (A) the
Telecommunications Act or the rules and regulations of the FCC applicable to the
Company, any of its subsidiaries or any of their respective assets or properties
or (B) any judgment, order or decree of any court or governmental agency or
authority having jurisdiction over the Company, any of its subsidiaries

                                        7
<PAGE>

or any of their assets or properties, that, in the case of clauses (A) and (B),
would reasonably be expected, either individually or in the aggregate, to result
in a Material Adverse Effect.

     (u)  Neither the Company nor any of its subsidiaries is or, after giving
effect to the Transactions, will be in violation of the Telecommunications Act
and the rules and regulations of the FCC applicable to the Company, any of its
subsidiaries or any of their respective assets or properties (whether owned or
leased), other than any violation that could not reasonably be expected to have
a Material Adverse Effect.

     (v)  Other than rulemaking procedures of general applicability to the
wireless broadband telecommunications industry, there is (i) no action, suit or
proceeding before or by the FCC, now pending or threatened or contemplated to
which the Company or any of its subsidiaries is or may be a party or to which
the business or property of the Company or any of its subsidiaries is subject,
or (ii) no amendment or change to the Telecommunications Act and the rules and
regulations of the FCC has been enacted, adopted or issued by the FCC or, to the
best of such counsel's knowledge, that has been proposed by the FCC.

     (w)  Each of the Company and its subsidiaries has filed all reports
required to be filed with the FCC.

     (x)  Neither the Company nor any of its subsidiaries has violated any
foreign, Federal, state or local law or regulation relating to the protection of
human health and safety, the environment or hazardous or toxic substances or
wastes, pollutants or contaminants, except where any such violations would not,
individually or in the aggregate, have a Material Adverse Effect.

     (y)  All tax returns required to be filed by the Company or any of its
subsidiaries in any jurisdiction have been so filed.  All taxes, including
withholding taxes, penalties and interest, assessments, fees and other charges
due or claimed to be due from such entities or that are due and payable have
been paid, other than those being contested in good faith and for which adequate
reserves have been provided for those currently payable without penalty or
interest.  There are no proposed additional taxes assessments against the
Company or its subsidiaries, and neither the Company nor any of its subsidiaries
has any knowledge of any tax deficiency which has been or might be asserted or
threatened against the Company or any of its subsidiaries which could have a
Material Adverse Effect.

     (z)  Each of the Company and its subsidiaries maintains adequate insurance
covering its properties, operations, personnel and business.  Such insurance
insures against such losses and risks as are adequate in accordance with
customary industry practice to protect the Company, its subsidiaries and their
respective businesses.  All such insurance is outstanding and duly in force on
the date hereof.

     (aa)      None of the Company, its subsidiaries or any of their respective
officers, directors, partners, employees, agents or affiliates or any other
person acting on behalf of the Company or any of its subsidiaries, as the case
may be, has, directly or indirectly, given or agreed to give any money, gift or
similar benefit (other than legal price concessions to consumers in the ordinary
course of business) to any customer, supplier, employee or agent of a customer
or supplier, official or employee of any governmental agency (domestic or
foreign), instrumentality of any government (domestic or foreign) or any
political party or candidate for office (domestic or foreign) or other person
who was, is or may be in a position to help or hinder the business of the
Company or its subsidiaries (or assist the Company or any of its subsidiaries in
connection with any actual or proposed transaction ) which (i) might subject the
Company, any of its subsidiaries or any other individual or entity to any damage
or penalty in any civil,

                                        8
<PAGE>

criminal or governmental litigation or proceeding (domestic or foreign) or (ii)
could reasonably be expected to have a Material Adverse Effect.

     (ab) Coopers & Lybrand, L.L.P., who have expressed their opinion with
respect to the financial statements and schedules filed with the Commission as
part of the Registration Statement and included in the Prospectus and in the
Registration Statement, are independent public accountants as required by the
Act and the Rules and Regulations.

     (ac) The financial statements, together with related schedules and notes
forming part of the Registration Statement and the Prospectus (and any amendment
or supplement thereto), present fairly the individual and consolidated financial
positions, results of operations and changes in financial position of the
Company, its subsidiaries and ART on the basis stated in the Registration
Statement and the Prospectus (and any amendment or supplement thereto) at the
respective dates or for the respective periods to which they apply.  Such
statements and related schedules and notes have been prepared in accordance with
generally accepted accounting principles consistently applied through the
periods involved, except as disclosed therein.  The other financial and
statistical information and data set forth in the Registration Statement and the
Prospectus (and any amendment or supplement thereto) is, in all material
respects, accurately presented and prepared on a basis consistent with such
financial statements and the books and records of the Company, its subsidiaries
and ART, as applicable.  The pro forma financial information and other financial
information included in the Prospectus present fairly the information shown
therein, have been prepared in accordance with the Commission's rules and
regulations with respect to pro forma financial information, have been properly
compiled on the pro forma basis described therein, and, in the opinion of the
Company, the assumptions used in the preparation thereof are reasonable and the
adjustments used therein are appropriate to give effect to the transactions or
circumstances referred to therein.  No other financial statements or schedules
are required to be included in the Registration Statement.  The selected
financial data set forth in the Prospectus under the captions "Capitalization"
and "Selected Historical and Pro Forma Financial Data" fairly present the
information set forth therein on the basis stated in the Registration Statement.

     (ad) Each of the Company and its subsidiaries maintains a system or
internal accounting controls sufficient to provide reasonable assurance that (i)
transactions are executed in accordance with management's general or specific
authorizations, (ii) transactions are recorded as necessary to permit
preparation of financial statements in conformity with generally accepted
accounting principles and to maintain accountability for assets, (iii) access to
assets is permitted only in accordance with management's general or specific
authorizations and (iv) the recorded accountability for assets is compared with
the existing assets at reasonable intervals and appropriate action is taken with
respect thereto.

     (ae) Subsequent to the respective dates as of which information is given in
the Prospectus and except as set forth in the Prospectus, (i) neither the
Company nor any of its subsidiaries has incurred any liabilities or obligations,
direct or contingent, which are material, individually or in the aggregate, to
the Company and its subsidiaries, taken as a whole, nor entered into any
transaction not in the ordinary course of business, (ii) neither the Company nor
any of its subsidiaries has sustained any material loss or interference with its
businesses or properties from fire, flood, windstorm, accident or other
calamity, whether or not covered by insurance, (iii) there has not been,
individually or in the aggregate, any change or development which could
reasonably be expected to result in a Material Adverse Effect and (iv) there has
been no dividend or distribution of any kind declared, paid or made by the
Company or any of its subsidiaries on any class of capital stock.

                                        9
<PAGE>

     (af) The Company does not intend to, nor does it believe that it will,
incur debts beyond its ability to pay such debts as they mature.  The present
fair saleable value of the assets of the Company on a consolidated basis exceeds
the amount that will be required to be paid on or in respect of the existing
debts and other liabilities (including contingent liabilities) of the Company on
a consolidated basis as they become absolute and matured.  The assets of the
Company on a consolidated basis do not constitute unreasonably small capital to
carry out the business of the Company and its subsidiaries, taken as a whole, as
conducted or as proposed to be conducted.

     (ag) Neither the Company nor any of its subsidiaries is (i) an "investment
company" or a company "controlled" by an "investment company" within the meaning
of the Investment Company Act of 1940, as amended, or (ii) a "holding company"
or a "subsidiary company" or an "affiliate" of a holding company within the
meaning of the Public Utility Holding Company Act of 1935, as amended.

     (ah) The Company has not distributed, and will not distribute prior to the
First Closing Date, any offering material in connection with the offering and
sale of the Common Shares other than the Prospectus, the Registration Statement
and the other materials permitted by the Act.

     (ai) Neither the Company nor any of its subsidiaries has (i) taken,
directly or indirectly, any action designed to, or that might reasonably be
expected to, cause or result in stabilization or manipulation of the price of
any security of the Company to facilitate the sale or resale of the Common
Shares or (ii) since the date of the Prospectus (A) sold, bid for, purchased or
paid any person any compensation for soliciting purchases of, the Common Shares
or (B) paid or agreed to pay to any person any compensation for soliciting
another to purchase any other securities of the Company.

     (aj) Except pursuant to this Agreement, there are no contracts, agreements
or understandings between the Company or any of its subsidiaries and any other
person that would give rise to a valid claim against the Company, any of its
subsidiaries or any of the Underwriters for a brokerage commission, finder's fee
or like payment in connection with the issuance, purchase and sale of the Common
Shares.

     (ak) Each of the Company and its subsidiaries has complied with all
provisions of Section 517.075, Florida Statutes.

     (al) Except as disclosed in the Prospectus, there are no business
relationships or related party transactions required to be disclosed therein
pursuant to Item 404 of Regulation S-K of the Commission.

     Each certificate signed by any officer of the Company and delivered to the
Underwriters or counsel to the Underwriters pursuant to this Agreement shall be
deemed to be a representation and warranty by the Company to the Underwriters as
to the matters covered thereby.

     The Company acknowledges that each of the Underwriters and, for purposes of
the opinions to be delivered to the Underwriters pursuant to Section 7 hereof,
counsel to the Company and counsel to the Underwriters, will rely upon the
accuracy and truth of the foregoing representations and hereby consents to such
reliance.

     SECTION 3.     REPRESENTATIONS AND WARRANTIES OF THE UNDERWRITERS.  The
Representatives, on behalf of the several Underwriters, represent and warrant to
the Company that the information set forth (i) on the cover page of the
Prospectus with respect to price, underwriting discounts and commissions and
terms of the Offering and (ii) under "Underwriting" in the Prospectus was
furnished to the Company by and on behalf of the Underwriters for use in
connection with the preparation of the Registration

                                       10
<PAGE>

Statement and the Prospectus and is correct in all material respects.  The
Representatives represent and warrant that they have been authorized by each of
the other Underwriters, as the Representatives, to enter into this Agreement on
its behalf and to act for it in the manner herein provided.

     SECTION 4.     PURCHASE, SALE AND DELIVERY OF COMMON SHARES.  On the basis
of the representations, warranties and agreements herein contained, but subject
to the terms and conditions herein set forth, the Company agrees to issue and
sell to the Underwriters __________ of the Firm Common Shares.  The Underwriters
agree, severally and not jointly, to purchase from the Company the number of
Firm Common Shares described below.  The purchase price per share to be paid by
the several Underwriters to the Company shall be $___ per share.

     The obligation of each Underwriter to the Company shall be to purchase from
the Company that number of full shares which (as nearly as practicable, as
determined by you) bears to __________ the same proportion as the number of
shares set forth opposite the name of such Underwriter in Schedule A hereto
bears to the total number of Firm Common Shares.

     Delivery of certificates for the Firm Common Shares to be purchased by the
Underwriters and payment therefor shall be made at the offices of Montgomery
Securities, 600 Montgomery Street, San Francisco, California (or such other
place as may be agreed upon by the Company and the Representatives) at such time
and date, not later than the third (or if the Firm Common Shares are priced, as
contemplated by Rule 15c6-1(c) under the Securities Exchange Act of 1934, as
amended (the "EXCHANGE ACT"), after 4:30 P.M., Washington, D.C. time, the
fourth) full business day following the first date that any of the Common Shares
are released by you for sale to the public, as you shall designate by at least
48 hours prior notice to the Company (or at such other time and date, not later
than one week after such third full business day as may be agreed upon by the
Company and the Representatives) (the "FIRST CLOSING DATE"); PROVIDED, HOWEVER,
that if the Prospectus is at any time prior to the First Closing Date
recirculated to the public, the First Closing Date shall occur upon the later of
the third or fourth, as the case may be, full business day following the first
date that any of the Common Shares are released by you for sale to the public or
the date that is 48 hours after the date that the Prospectus has been so
recirculated.

     Delivery of certificates for the Firm Common Shares shall be made by or on
behalf of the Company to you, for the respective accounts of the Underwriters
against payment by you, for the accounts of the several Underwriters, of the
purchase price therefor by fed funds to the order of the Company.  The
certificates for the Firm Common Shares shall be registered in such names and
denominations as you shall have requested at least two full business days prior
to the First Closing Date, and shall be made available for checking and
packaging on the business day preceding the First Closing Date at a location in
New York, New York, as may be designated by you.  Time shall be of the essence,
and delivery at the time and place specified in this Agreement is a further
condition to the obligations of the Underwriters.

     In addition, on the basis of the representations, warranties and agreements
herein contained, but subject to the terms and conditions herein set forth, the
Company hereby grants an option to the several Underwriters to purchase,
severally and not jointly, up to an aggregate of __________ Optional Common
Shares at the purchase price per share to be paid for the Firm Common Shares,
for use solely in covering any over-allotments made by you for the account of
the Underwriters in the sale and distribution of the Firm Common Shares.  The
option granted hereunder may be exercised at any time (but not more than once)
within 30 days after the first date that any of the Common Shares are released
by you for sale to the public, upon notice by you to the Company setting forth
the aggregate number of Optional Common

                                       11
<PAGE>

Shares as to which the Underwriters are exercising the option, the names and
denominations in which the certificates for such shares are to be registered and
the time and place at which such certificates will be delivered.  Such time of
delivery (which may not be earlier than the First Closing Date), being herein
referred to as the "SECOND CLOSING DATE," shall be determined by you, but if at
any time other than the First Closing Date shall not be earlier than three nor
later than five full business days after delivery of such notice of exercise.
The number of Optional Common Shares to be purchased by each Underwriter shall
be determined by multiplying the number of Optional Common Shares to be sold by
the Company pursuant to such notice of exercise by a fraction, the numerator of
which is the number of Firm Common Shares to be purchased by such Underwriter as
set forth opposite its name in Schedule A and the denominator of which is
__________ (subject to such adjustments to eliminate any fractional share
purchases as you in your discretion may make).  Certificates for the Optional
Common Shares will be made available for checking and packaging on the business
day preceding the Second Closing Date at a location in New York, New York, as
may be designated by you.  The manner of payment for and delivery of the
Optional Common Shares shall be the same as for the Firm Common Shares purchased
from the Company as specified in the two preceding paragraphs.  At any time
before lapse of the option, you may cancel such option by giving written notice
of such cancellation to the Company.  If the option is cancelled or expires
unexercised in whole or in part, the Company will deregister under the Act the
number of Option Shares as to which the option has not been exercised.

     You have advised the Company that each Underwriter has authorized you to
accept delivery of its Common Shares, to make payment and to accept receipt
therefor.  You, individually and not as the Representatives of the Underwriters,
may (but shall not be obligated to) make payment for any Common Shares to be
purchased by any Underwriter whose funds shall not have been received by you by
the First Closing Date or the Second Closing Date, as the case may be, for the
account of such Underwriter, but any such payment shall not relieve such
Underwriter from any of its obligations under this Agreement.

     Subject to the terms and conditions hereof, the Underwriters propose to
make a public offering of their respective portions of the Common Shares as soon
after the effective date of the Registration Statement as in the judgment of the
Representatives is advisable and at the public offering price set forth on the
cover page of, and on the terms set forth in, the final prospectus, if one is
used, or on the first page of the Term Sheet, if one is used.

     SECTION 5.     COVENANTS OF THE COMPANY.  The Company covenants and agrees
that:

     (a) The Company will use its best efforts to cause the Registration
Statement and any amendment thereof, if not effective at the time and date that
this Agreement is executed and delivered by the parties hereto, to become
effective.  If the Registration Statement has become or becomes effective
pursuant to Rule 430A of the Rules and Regulations, or the filing of the
Prospectus is otherwise required under Rule 424(b) of the Rules and Regulations,
the Company will file the Prospectus, properly completed, pursuant to the
applicable paragraph of Rule 424(b) of the Rules and Regulations within the time
period prescribed and will provide evidence satisfactory to you of such timely
filing.  The Company will promptly advise you in writing (i) of the receipt of
any comments of the Commission, (ii) of any request of the Commission for
amendment of or supplement to the Registration Statement (either before or after
it becomes effective), any Preliminary Prospectus or the Prospectus or for
additional information, (iii) when the Registration Statement shall have become
effective, and (iv) of the issuance by the Commission of any stop order
suspending the effectiveness of the Registration Statement or of the institution
of any proceedings for that purpose.  If the Commission shall enter any such
stop order at any time, the Company will use its best efforts to obtain the
lifting of such order at the earliest possible moment.  The Company will not
file any amendment or supplement to the Registration Statement (either

                                       12
<PAGE>

before or after it becomes effective), any Preliminary Prospectus or the
Prospectus of which you have not been furnished with a copy a reasonable time
prior to such filing or to which you reasonably object or which is not in
compliance with the Act and the Rules and Regulations.

     (b) The Company will prepare and file with the Commission, promptly upon
your request, any amendments or supplements to the Registration Statement or the
Prospectus which in your judgment may be necessary or advisable to enable the
several Underwriters to continue the distribution of the Common Shares and will
use its best efforts to cause the same to become effective as promptly as
possible.  The Company will fully and completely comply with the provisions of
Rule 430A of the Rules and Regulations with respect to information omitted from
the Registration Statement in reliance upon such Rule.

     (c) If at any time within the nine-month period referred to in Section
10(a)(3) of the Act during which a prospectus relating to the Common Shares is
required to be delivered under the Act any event occurs, as a result of which
the Prospectus, including any amendments or supplements, would include an untrue
statement of a material fact, or omit to state any material fact required to be
stated therein or necessary to make the statements therein not misleading, or if
it is necessary at any time to amend the Prospectus, including any amendments or
supplements, to comply with the Act or the Rules and Regulations, the Company
will promptly advise you thereof and will promptly prepare and file with the
Commission, at its own expense, an amendment or supplement which will correct
such statement or omission or an amendment or supplement which will effect such
compliance and will use its best efforts to cause the same to become effective
as soon as possible; and, in case any Underwriter is required to deliver a
prospectus after such nine-month period, the Company upon request, but at the
expense of such Underwriter, will promptly prepare such amendment or amendments
to the Registration Statement and such Prospectus or Prospectuses as may be
necessary to permit compliance with the requirements of Section 10(a)(3) of the
Act.

     (d) As soon as practicable, but not later than 45 days after the end of
the first quarter ending after one year following the "effective date of the
Registration Statement" (as defined in Rule 158(c) of the Rules and
Regulations), the Company will make generally available to its security holders
an earnings statement (which need not be audited) covering a period of 12
consecutive months beginning after the effective date of the Registration
Statement which will satisfy the provisions of the last paragraph of Section
11(a) of the Act.

     (e) During such period as a prospectus is required by law to be delivered
in connection with sales by an Underwriter or dealer, the Company, at its
expense, but only for the nine-month period referred to in Section 10(a)(3) of
the Act, will furnish to you or mail to your order copies of the Registration
Statement, the Prospectus, the Preliminary Prospectus and all amendments and
supplements to any such documents, in each case, as soon as available and in
such quantities as you may request, for the purposes contemplated by the Act.

     (f) The Company shall cooperate with you and your counsel in order to
qualify or register the Common Shares for sale under (or obtain exemptions from
the application of) the Blue Sky laws of such jurisdictions as you designate,
will comply with such laws and will continue such qualifications, registrations
and exemptions in effect so long as reasonably required for the distribution of
the Common Shares.  The Company shall not be required to qualify as a foreign
corporation or to file a general consent to service of process in any such
jurisdiction where it is not presently qualified or where it would be subject to
taxation as a foreign corporation.  The Company will advise you promptly of the
suspension of the qualification or registration of (or any such exemption
relating to) the Common Shares for offering,

                                       13
<PAGE>

sale or trading in any jurisdiction or any initiation or threat of any
proceeding for any such purpose, and, in the event of the issuance of any order
suspending such qualification, registration or exemption, the Company, with your
cooperation, will use its best efforts to obtain the withdrawal thereof.

     (g) During the period of five years hereafter, the Company will furnish to
the Representatives and, upon request of the Representatives, to each of the
other Underwriters (i) as soon as practicable after the end of each fiscal year,
copies of the Annual Report of the Company containing the balance sheet of the
Company as of the close of such fiscal year and statements of income,
stockholders' equity and cash flows for the year then ended and the opinion
thereon of the Company's independent public accountants, (ii) as soon as
practicable after the filing thereof, copies of each proxy statement, Annual
Report on Form 10-K, Quarterly Report on Form 10-Q, Report on Form 8-K or other
report filed by the Company with the Commission, the National Association of
Securities Dealers, Inc. (the "NASD") or any securities exchange and (iii) as
soon as available, copies of any report or communication of the Company mailed
generally to holders of its Common Stock.

     (h) During the period of 180 days after the first date that any of the
Common Shares are released by you for sale to the public, without the prior
written consent of Montgomery Securities (which consent may be withheld at the
sole discretion of Montgomery Securities), the Company will not, other than
pursuant to outstanding stock options and warrants disclosed in the Prospectus,
issue, offer, sell, grant options to purchase or otherwise dispose of any of the
Company's equity securities or any other securities convertible into or
exchangeable with its Common Stock or other equity security.  The Company will
enter into an agreement (the "LOCK-UP AGREEMENT") to the foregoing effect.

     (i) The Company will apply the net proceeds of the sale of the Common
Shares sold by it substantially in accordance with its statements under the
caption "Use of Proceeds" in the Prospectus.

     (j) The Company will use its best efforts to qualify or register its
Common Stock for sale in non-issuer transactions under (or obtain exemptions
from the application of) the Blue Sky laws of the State of California (and
thereby permit market making transactions and secondary trading in the Company's
Common Stock in California), will comply with such Blue Sky laws and will
continue such qualifications, registrations and exemptions in effect for a
period of five years after the date hereof.

     (k) The Company will use its best efforts to designate the Common Stock
for quotation as a national market system security on the Nasdaq National
Market.

     You, on behalf of the Underwriters, may, in your sole discretion, waive in
writing the performance by the Company of any one or more of the foregoing
covenants or extend the time for their performance.

     SECTION 6.     PAYMENT OF EXPENSES.  Whether or not the transactions
contemplated hereunder are consummated or this Agreement becomes effective or is
terminated, the Company agrees to pay all costs, fees and expenses incurred in
connection with the performance of its obligations hereunder and in connection
with the transactions contemplated hereby, including, without limiting the
generality of the foregoing, (i) all expenses incident to the issuance and
delivery of the Common Shares (including all printing and engraving costs), (ii)
all fees and expenses of the registrar and transfer agent of the Common Stock,
(iii) all necessary issue, transfer and other stamp taxes in connection with the
issuance and sale of the Common Shares to the Underwriters, (iv) all fees and
expenses of the Company's counsel and the Company's independent accountants, (v)
all costs and expenses incurred in connection with the preparation, printing,
filing, shipping and distribution of the Registration Statement, each
Preliminary Prospectus and the Prospectus (including all exhibits and financial
statements) and all amendments and

                                       14
<PAGE>

supplements provided for herein, the Operative Agreements, the Agreement Among
Underwriters, the Selected Dealers Agreement, the Underwriters' Questionnaire,
the Underwriters' Power of Attorney and the Blue Sky memorandum, (vi) all filing
fees, attorneys' fees and expenses incurred by the Company or the Underwriters
in connection with qualifying or registering (or obtaining exemptions from the
qualification or registration of) all or any part of the Common Shares for offer
and sale under the Blue Sky laws, (vii) the filing fee of the NASD, and (viii)
all other fees, costs and expenses referred to in Item 13 of the Registration
Statement.  Except as provided in this Section 6 and Sections 8 and 10 hereof,
the Underwriters shall pay all of their own expenses, including the fees and
disbursements of their counsel (excluding those relating to qualification,
registration or exemption under the Blue Sky laws and the Blue Sky memorandum
referred to above).

     SECTION 7.     CONDITIONS OF THE OBLIGATIONS OF THE UNDERWRITERS.  The
obligations of the several Underwriters to purchase and pay for the Firm Common
Shares on the First Closing Date and the Optional Common Shares on the Second
Closing Date shall be subject to the accuracy of the representations and
warranties on the part of the Company herein set forth as of the date hereof and
as of the First Closing Date or the Second Closing Date, as the case may be, to
the accuracy of the statements of Company officers made pursuant to the
provisions hereof, to the performance by the Company of its obligations
hereunder, and to the following additional conditions:

     (a) The Registration Statement shall have become effective not later than
5:00 P.M. (or, in the case of a registration statement filed pursuant to Rule
462(b) of the Rules and Regulations relating to the Common Shares, not later
than 10:00 P.M.), Washington, D.C. Time, on the date of this Agreement, or at
such later time as shall have been consented to by you; if the filing of the
Prospectus, or any supplement thereto, is required pursuant to Rule 424(b) of
the Rules and Regulations, the Prospectus shall have been filed in the manner
and within the time period required by Rule 424(b) of the Rules and Regulations;
and prior to such Closing Date, no stop order suspending the effectiveness of
the Registration Statement shall have been issued and no proceedings for that
purpose shall have been instituted or shall be pending or, to the knowledge of
the Company or you, shall be contemplated by the Commission; and any request of
the Commission for inclusion of additional information in the Registration
Statement, or otherwise, shall have been complied with to your satisfaction.

     (b) You shall be satisfied that, since the respective dates as of which
information is given in the Registration Statement and Prospectus, (i) there
shall not have been any change in the capital stock, other than pursuant to the
exercise of outstanding options and warrants disclosed in the Prospectus, of the
Company or any of its subsidiaries or any material change in the indebtedness
(other than in the ordinary course of business) of the Company or any of its
subsidiaries, (ii) except as set forth or contemplated by the Registration
Statement or the Prospectus, no material verbal or written agreement or other
transaction shall have been entered into by the Company or any of its
subsidiaries, which is not in the ordinary course of business or which could
result in a material reduction in the future earnings of the Company or any of
its subsidiaries, (iii) no loss or damage (whether or not insured) to the
property of the Company or any of its subsidiaries shall have been sustained
which could reasonably be expected to result, either individually or in the
aggregate, in a Material Adverse Effect, (iv) no legal or governmental action,
suit or proceeding affecting the Company or any of its subsidiaries which is
material to the Company and its subsidiaries or which affects or may affect the
transactions contemplated by this Agreement shall have been instituted or
threatened, and (v) there shall not have been any Material Adverse Effect which
makes it impractical or inadvisable in the judgment of the Representatives to
proceed with the public offering or purchase the Common Shares as contemplated
hereby.

                                       15
<PAGE>

     (c) There shall have been furnished to you, as Representatives of the
Underwriters, on each Closing Date, in form and substance satisfactory to you
except as otherwise expressly provided below:

         (i)   An opinion of Hahn & Hessen LLP, counsel to the Company,
     addressed to the Underwriters and dated the First Closing Date or the
     Second Closing Date, as the case may be, with respect to the matters set
     forth in Exhibit C.

         (ii)  An opinion of Pierson, Burnett & Hanley, special regulatory
     counsel to the Company, addressed to the Underwriters and dated the First
     Closing Date or the Second Closing Date, as the case may be, with respect
     to the matters set forth in Exhibit D.

         (iii)      Such opinion or opinions of Latham & Watkins, counsel to the
     Underwriters dated the First Closing Date or the Second Closing Date, as
     the case may be, with respect to the incorporation of the Company, the
     sufficiency of all corporate proceedings and other legal matters relating
     to this Agreement, the validity of the Common Shares, the Registration
     Statement and the Prospectus and other related matters as you may
     reasonably require, and the Company shall have furnished to such counsel
     such documents and shall have exhibited to them such papers and records as
     they may reasonably request for the purpose of enabling them to pass upon
     such matters.  In connection with such opinions, such counsel may rely on
     representations or certificates of officers of the Company and governmental
     officials.

         (iv)  A certificate of the Company executed by the Chairman of the
     Board or President and the chief financial or accounting officer of the
     Company, dated the First Closing Date or the Second Closing Date, as the
     case may be, to the effect that:

                    (1)  The representations and warranties of the Company set
         forth in Section 2 of this Agreement are true and correct as of the
         date of this Agreement and as of the First Closing Date or the Second
         Closing Date, as the case may be, and the Company has complied with
         all the agreements and satisfied all the conditions on its part to be
         performed or satisfied on or prior to such Closing Date;

                    (2)  The Commission has not issued any order preventing or
         suspending the use of the Prospectus or any Preliminary Prospectus
         filed as a part of the Registration Statement or any amendment
         thereto; no stop order suspending the effectiveness of the
         Registration Statement has been issued; and, to the best of the
         knowledge of the respective signers, no proceedings for that purpose
         have been instituted or are pending or contemplated under the Act;

                    (3)  Each of the respective signers of the certificate has
         carefully examined the Registration Statement and the Prospectus; in
         his opinion and to the best of his knowledge, the Registration
         Statement and the Prospectus and any amendments or supplements thereto
         contain all statements required to be stated therein regarding the
         Company; and neither the Registration Statement nor the Prospectus nor
         any amendment or supplement thereto includes any untrue statement of a
         material fact or omits to state any material fact required to be
         stated therein or necessary to make the statements therein not
         misleading;

                    (4)  Since the initial date on which the Registration
         Statement was filed, no agreement, written or oral, transaction or
         event has occurred which should have been set

                                       16
<PAGE>

         forth in an amendment to the Registration Statement or in a supplement
         to or amendment of any prospectus which has not been disclosed in such
         a supplement or amendment;

                    (5)  Since the respective dates as of which information is
         given in the Registration Statement and the Prospectus and except as
         disclosed in or contemplated by the Prospectus, there has not been any
         Material Adverse Effect or a development involving a Material Adverse
         Effect; and no legal or governmental action, suit or proceeding is
         pending or threatened against the Company which is material to the
         Company, whether or not arising from transactions in the ordinary
         course of business, or which may adversely affect the transactions
         contemplated by this Agreement; since such dates and except as so
         disclosed, none of the Company or any of its subsidiaries has entered
         into any verbal or written agreement or other transaction which is not
         in the ordinary course of business or which could result in a material
         reduction in the future earnings of the Company or incurred any
         material liability or obligation, direct, contingent or indirect, made
         any change in its capital stock, made any material change in its
         short-term debt or funded debt or repurchased or otherwise acquired
         any of the Company's capital stock; and neither the Company nor any of
         its subsidiaries has declared or paid any dividend, or made any other
         distribution, upon its outstanding capital stock payable to
         stockholders of record on a date prior to the First Closing Date or
         Second Closing Date; and

                    (6)  Since the respective dates as of which information is
         given in the Registration Statement and the Prospectus and except as
         disclosed in or contemplated by the Prospectus, the Company has not
         sustained a material loss or damage by strike, fire, flood, windstorm,
         accident or other calamity (whether or not insured).

         (v)   On the date before this Agreement is executed and also on the
     First Closing Date and the Second Closing Date a letter addressed to you,
     as Representatives of the Underwriters, from Coopers & Lybrand L.L.P.,
     independent accountants, the first one to be dated the day before the date
     of this Agreement, the second one to be dated the First Closing Date and
     the third one (in the event of a Second Closing) to be dated the Second
     Closing Date, in form and substance satisfactory to you.

         (vi)  On or before the First Closing Date, letters from each holder of
     the Company's Common Stock and ART's common stock, each holder of options,
     warrants or other rights convertible or exchangeable into Common Stock or
     ART common stock, and each director and officer of the Company, in form and
     substance satisfactory to you, confirming that for a period of 180 days
     after the date of the final prospectus for the Offering, such person will
     not directly or indirectly sell or offer to sell or otherwise dispose of
     any shares of Common Stock or any right to acquire such shares without the
     prior written consent of Montgomery Securities, which consent may be
     withheld at the sole discretion of Montgomery Securities.

         (vii)      On or before the First Closing Date, executed copies of the
     Lock-Up Agreement.

     (d) Prior to the date hereof, the Merger shall have been completed.

     (e) On or before the First Closing Date, the Unit Offering shall have been
consummated.

     All such opinions, certificates, letters and documents shall be in
compliance with the provisions hereof only if they are satisfactory to you and
to Latham & Watkins, counsel to the Underwriters.  The

                                       17
<PAGE>

Company shall furnish you with such manually signed or conformed copies of such
opinions, certificates, letters and documents as you request.  Any certificate
signed by any officer of the Company and delivered to the Representatives or to
counsel to the Underwriters shall be deemed to be a representation and warranty
by the Company to the Underwriters as to the statements made therein.


     If any condition to the Underwriters' obligations hereunder to be satisfied
prior to or at the First Closing Date is not so satisfied, this Agreement at
your election will terminate upon notification by you as Representatives to the
Company without liability on the part of any Underwriter or the Company except
for the expenses to be paid or reimbursed by the Company pursuant to Sections 6
and 8 hereof and except to the extent provided in Section 10 hereof.

     SECTION 8.     REIMBURSEMENT OF UNDERWRITERS' EXPENSES.  Notwithstanding
any other provisions hereof, if this Agreement shall be terminated by you
pursuant to Section 7 hereof, or if the sale to the Underwriters of the Common
Shares at the First Closing is not consummated because of any refusal, inability
or failure on the part of the Company to perform any agreement herein or to
comply with any provision hereof, the Company agrees to reimburse you and the
other Underwriters upon demand for all out-of-pocket expenses that shall have
been reasonably incurred by you and them in connection with the proposed
purchase and the sale of the Common Shares, including but not limited to fees
and disbursements of counsel, printing expenses, travel expenses, postage,
telegraph charges and telephone charges relating directly to the Offering
contemplated by the Prospectus.  Any such termination shall be without liability
of any party to any other party except that the provisions of this Section 8 and
Sections 6 and 10 shall at all times be effective and shall apply.

     SECTION 9.     EFFECTIVENESS OF REGISTRATION STATEMENT.  You and the
Company will use your and its best efforts to cause the Registration Statement
to become effective, to prevent the issuance of any stop order suspending the
effectiveness of the Registration Statement and, if such stop order be issued,
to obtain as soon as possible the lifting thereof.

     SECTION 10.    INDEMNIFICATION.  (a)  The Company agrees to indemnify and
hold harmless each Underwriter and each person, if any, who controls any
Underwriter within the meaning of the Act against any losses, claims, damages,
liabilities or expenses, joint or several, to which such Underwriter or such
controlling person may become subject, under the Act, the Exchange Act, or other
Federal or state statutory law or regulation, or at common law or otherwise
(including in settlement of any litigation, if such settlement is effected with
the written consent of the Company), insofar as such losses, claims, damages,
liabilities or expenses (or actions in respect thereof as contemplated below)
arise out of or are based upon any untrue statement or alleged untrue statement
of any material fact contained in the Registration Statement, any Preliminary
Prospectus, the Prospectus, or any amendment or supplement thereto, or arise out
of or are based upon the omission or alleged omission to state in any of them a
material fact required to be stated therein or necessary to make the statements
in any of them not misleading, or arise out of or are based in whole or in part
on any inaccuracy in the representations and warranties of the Company contained
herein or any failure of the Company to perform its obligations hereunder or
under law; and will reimburse each Underwriter and each such controlling person
for any legal and other expenses as such expenses are reasonably incurred by
such Underwriter or such controlling person in connection with investigating,
defending, settling, compromising or paying any such loss, claim, damage,
liability, expense or action; PROVIDED, HOWEVER, that the Company will not be
liable in any such case to the extent that any such loss, claim, damage,
liability or expense arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission made in the
Registration Statement, any Preliminary Prospectus, the Prospectus or any
amendment or supplement thereto in reliance upon and in conformity with the
information furnished to the Company pursuant to


                                       18
<PAGE>

Section 3 hereof.  In addition to its other obligations under this Section
10(a), the Company agrees that, as an interim measure during the pendency of any
claim, action, investigation, inquiry or other proceeding arising out of or
based upon any statement or omission, or any alleged statement or omission, or
any inaccuracy in the representations and warranties of the Company herein or
failure to perform its obligations hereunder, all as described in this Section
10(a), it will reimburse each Underwriter on a quarterly basis for all
reasonable legal or other expenses incurred in connection with investigating or
defending any such claim, action, investigation, inquiry or other proceeding,
notwithstanding the absence of a judicial determination as to the propriety and
enforceability of the Company's obligation to reimburse each Underwriter for
such expenses and the possibility that such payments might later be held to have
been improper by a court of competent jurisdiction.  To the extent that any such
interim reimbursement payment is so held to have been improper, each Underwriter
shall promptly return it to the Company together with interest, compounded
daily, determined on the basis of the prime rate (or other commercial lending
rate for borrowers of the highest credit standing) announced from time to time
by Bank of America NT&SA, San Francisco, California (the "PRIME RATE").  Any
such interim reimbursement payments which are not made to an Underwriter within
30 days of a request for reimbursement, shall bear interest at the Prime Rate
from the date of such request.  This indemnity agreement will be in addition to
any liability which the Company may otherwise have.

     (b)  Each Underwriter will severally indemnify and hold harmless the
Company, each of its directors, each of its officers who signed the Registration
Statement and each person, if any, who controls the Company within the meaning
of the Act, against any losses, claims, damages, liabilities or expenses to
which the Company, or any such director, officer or controlling person may
become subject, under the Act, the Exchange Act, or other Federal or state
statutory law or regulation, or at common law or otherwise (including in
settlement of any litigation, if such settlement is effected with the written
consent of such Underwriter), insofar as such losses, claims, damages,
liabilities or expenses (or actions in respect thereof as contemplated below)
arise out of or are based upon any untrue or alleged untrue statement of any
material fact contained in the Registration Statement, any Preliminary
Prospectus, the Prospectus, or any amendment or supplement thereto, or arise out
of or are based upon the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, in each case to the extent, but only to the extent, that
such untrue statement or alleged untrue statement or omission or alleged
omission was made in the Registration Statement, any Preliminary Prospectus, the
Prospectus, or any amendment or supplement thereto, in reliance upon and in
conformity with the information furnished to the Company pursuant to Section 3
hereof; and will reimburse the Company, or any such director, officer or
controlling person for any legal and other expense reasonably incurred by the
Company, or any such director, officer or controlling person in connection with
investigating, defending, settling, compromising or paying any such loss, claim,
damage, liability, expense or action.  In addition to its other obligations
under this Section 10(b), each Underwriter severally agrees that, as an interim
measure during the pendency of any claim, action, investigation, inquiry or
other proceeding arising out of or based upon any statement or omission, or any
alleged statement or omission, described in this Section 10(b) which relates to
information furnished to the Company pursuant to Section 3 hereof, it will
reimburse the Company (and, to the extent applicable, each officer, director,
controlling person on a quarterly basis for all reasonable legal or other
expenses incurred in connection with investigating or defending any such claim,
action, investigation, inquiry or other proceeding, notwithstanding the absence
of a judicial determination as to the propriety and enforceability of the
Underwriters' obligation to reimburse the Company (and, to the extent
applicable, each officer, director, controlling person for such expenses and the
possibility that such payments might later be held to have been improper by a
court of competent jurisdiction.  To the extent that any such interim
reimbursement payment is so held to have been improper, the Company (and, to the
extent applicable, each officer, director, controlling person) shall promptly
return it to the Underwriters together

                                       19
<PAGE>

with interest, compounded daily, determined on the basis of the Prime Rate.  Any
such interim reimbursement payments which are not made to the Company within 30
days of a request for reimbursement, shall bear interest at the Prime Rate from
the date of such request.  This indemnity agreement will be in addition to any
liability which such Underwriter may otherwise have.

     (c)  Promptly after receipt by an indemnified party under this Section of
notice of the commencement of any action, such indemnified party will, if a
claim in respect thereof is to be made against an indemnifying party under this
Section, notify the indemnifying party in writing of the commencement thereof;
but the omission so to notify the indemnifying party will not relieve it from
any liability which it may have to any indemnified party for contribution or
otherwise than under the indemnity agreement contained in this Section or to the
extent it is not prejudiced as a proximate result of such failure.  In case any
such action is brought against any indemnified party and such indemnified party
seeks or intends to seek indemnity from an indemnifying party, the indemnifying
party will be entitled to participate in, and, to the extent that it may wish,
jointly with all other indemnifying parties similarly notified, to assume the
defense thereof with counsel reasonably satisfactory to such indemnified party;
PROVIDED, HOWEVER, if the defendants in any such action include both the
indemnified party and the indemnifying party and the indemnified party shall
have reasonably concluded that there may be a conflict between the positions of
the indemnifying party and the indemnified party in conducting the defense of
any such action or that there may be legal defenses available to it and/or other
indemnified parties which are different from or additional to those available to
the indemnifying party, the indemnified party or parties shall have the right to
select separate counsel to assume such legal defenses and to otherwise
participate in the defense of such action on behalf of such indemnified party or
parties.  Upon receipt of notice from the indemnifying party to such indemnified
party of its election so to assume the defense of such action and approval by
the indemnified party of counsel, the indemnifying party will not be liable to
such indemnified party under this Section for any legal or other expenses
subsequently incurred by such indemnified party in connection with the defense
thereof unless (i) the indemnified party shall have employed such counsel in
connection with the assumption of legal defenses in accordance with the proviso
to the next preceding sentence (it being understood, however, that the
indemnifying party shall not be liable for the expenses of more than one
separate counsel, approved by the Representatives in the case of paragraph (a),
representing the indemnified parties who are parties to such action) or (ii) the
indemnifying party shall not have employed counsel reasonably satisfactory to
the indemnified party to represent the indemnified party within a reasonable
time after notice of commencement of the action, in each of which cases the fees
and expenses of counsel shall be at the expense of the indemnifying party.

     (d)  If the indemnification provided for in this Section 10 is required by
its terms but is for any reason held to be unavailable to or otherwise
insufficient to hold harmless an indemnified party under paragraphs (a), (b) or
(c) in respect of any losses, claims, damages, liabilities or expenses referred
to herein, then each applicable indemnifying party shall contribute to the
amount paid or payable by such indemnified party as a result of any losses,
claims, damages, liabilities or expenses referred to herein (i) in such
proportion as is appropriate to reflect the relative benefits received by the
Company and the Underwriters from the offering of the Common Shares or (ii) if
the allocation provided by clause (i) above is not permitted by applicable law,
in such proportion as is appropriate to reflect not only the relative benefits
referred to in clause (i) above but also the relative fault of the Company and
the Underwriters in connection with the statements or omissions or inaccuracies
in the representations and warranties herein which resulted in such losses,
claims, damages, liabilities or expenses, as well as any other relevant
equitable considerations.  The respective relative benefits received by the
Company and the Underwriters shall be deemed to be in the same proportion, in
the case of the Company as the total price paid to the Company for the Common
Shares sold by it to the Underwriters (net of underwriting commissions but
before deducting expenses) bears to the total price to the public set forth on
the cover 

                                       20
<PAGE>

of the Prospectus, and in the case of the Underwriters as the underwriting 
commissions received by them bears to the total price to the public set forth 
on the cover of the Prospectus.  The relative fault of the Company and the 
Underwriters shall be determined by reference to, among other things, whether 
the untrue or alleged untrue statement of a material fact or the omission or 
alleged omission to state a material fact or the inaccurate or the alleged 
inaccurate representation and/or warranty relates to information supplied by 
the Company or the Underwriters and the parties' relative intent, knowledge, 
access to information and opportunity to correct or prevent such statement or 
omission.  The amount paid or payable by a party as a result of the losses, 
claims, damages, liabilities and expenses referred to above shall be deemed 
to include, subject to the limitations set forth in subparagraph (c) of this 
Section 10, any legal or other fees or expenses reasonably incurred by such 
party in connection with investigating or defending any action or claim.  The 
provisions set forth in subparagraph (c) of this Section 10 with respect to 
notice of commencement of any action shall apply if a claim for contribution 
is to be made under this subparagraph (d); PROVIDED, HOWEVER, that no 
additional notice shall be required with respect to any action for which 
notice has been given under subparagraph (c) for purposes of indemnification. 
 The Company and the Underwriters agree that it would not be just and 
equitable if contribution pursuant to this Section 10 were determined solely 
by pro rata allocation (even if the Underwriters were treated as one entity 
for such purpose) or by any other method of allocation which does not take 
account of the equitable considerations referred to in the immediately 
preceding paragraph.  Notwithstanding the provisions of this Section 10, no 
Underwriter shall be required to contribute any amount in excess of the 
amount of the total underwriting commissions received by such Underwriter in 
connection with the Common Shares underwritten by it and distributed to the 
public.  No person guilty of fraudulent misrepresentation (within the meaning 
of Section 10(f) of the Act) shall be entitled to contribution from any 
person who was not guilty of such fraudulent misrepresentation.  The 
Underwriters' obligations to contribute pursuant to this Section 10 are 
several in proportion to their respective underwriting commitments and not 
joint.

     (e)  It is agreed that any controversy arising out of the operation of the
interim reimbursement arrangements set forth in Sections 10(a) and 10(b) hereof,
including theamounts of any requested reimbursement payments and the method of
determining such amounts, shall be settled by arbitration conducted under the
provisions of the Constitution and Rules of the Board of Governors of the New
York Stock Exchange, Inc. or pursuant to the Code of Arbitration Procedure of
the NASD.  Any such arbitration must be commenced by service of a written demand
for arbitration or written notice of intention to arbitrate, therein electing
the arbitration tribunal.  In the event the party demanding arbitration does not
make such designation of an arbitration tribunal in such demand or notice, then
the party responding to said demand or notice is authorized to do so.  Such an
arbitration would be limited to the operation of the interim reimbursement
provisions contained in Sections 10(a) and 10(b) hereof and would not resolve
the ultimate propriety or enforceability of the obligation to reimburse expenses
which is created by the provisions of such Sections 10(a) and 10(b) hereof.

     SECTION 11.    DEFAULT OF UNDERWRITERS.  It shall be a condition to this
Agreement and the obligation of the Company to sell and deliver the Common
Shares hereunder, and of each Underwriter to purchase the Common Shares in the
manner as described herein, that, except as hereinafter in this paragraph
provided, each of the Underwriters shall purchase and pay for all the Common
Shares agreed to be purchased by such Underwriter hereunder upon tender to the
Representatives of all such shares in accordance with the terms hereof.  If any
Underwriter or Underwriters default in their obligations to purchase Common
Shares hereunder on either the First or Second Closing Date and the aggregate
number of Common Shares which such defaulting Underwriter or Underwriters agreed
but failed to purchase on such Closing Date does not exceed 10% of the total
number of Common Shares which the Underwriters are obligated to purchase on such
Closing Date, the non-defaulting Underwriters shall be obligated

                                       21
<PAGE>

severally, in proportion to their respective commitments hereunder, to purchase
the Common Shares which such defaulting Underwriters agreed but failed to
purchase on such Closing Date.  If any Underwriter or Underwriters so default
and the aggregate number of Common Shares with respect to which such default
occurs is more than the above percentage and arrangements satisfactory to the
Representatives and the Company for the purchase of such Common Shares by other
persons are not made within 48 hours after such default, this Agreement will
terminate without liability on the part of any non-defaulting Underwriter or the
Company except for the expenses to be paid by the Company pursuant to Section 6
hereof and except to the extent provided in Section 10 hereof.

     In the event that Common Shares to which a default relates are to be
purchased by the non-defaulting Underwriters or by another party or parties, the
Representatives or the Company shall have the right to postpone the First or
Second Closing Date, as the case may be, for not more than five business days in
order that the necessary changes in the Registration Statement, Prospectus and
any other documents, as well as any other arrangements, may be effected.  As
used in this Agreement, the term "Underwriter" includes any person substituted
for an Underwriter under this Section.  Nothing herein will relieve a defaulting
Underwriter from liability for its default.

     SECTION 12.    EFFECTIVE DATE.  This Agreement shall become effective
immediately as to Sections 6, 8, 10, 13 and 14 and, as to all other provisions,
(i) if at the time of execution of this Agreement the Registration Statement has
not become effective, at 2:00 P.M., California time, on the first full business
day following the effectiveness of the Registration Statement, or (ii) if at the
time of execution of this Agreement the Registration Statement has been declared
effective, at 2:00 P.M., California time, on the first full business day
following the date of execution of this Agreement; but this Agreement shall
nevertheless become effective at such earlier time after the Registration
Statement becomes effective as you may determine on and by notice to the Company
or by release of any of the Common Shares for sale to the public.  For the
purposes of this Section 12, the Common Shares shall be deemed to have been so
released upon the release for publication of any newspaper advertisement
relating to the Common Shares or upon the release by you of telegrams (i)
advising Underwriters that the Common Shares are released for public offering,
or (ii) offering the Common Shares for sale to securities dealers, whichever may
occur first.

     SECTION 13.    TERMINATION.  Without limiting the right to terminate this
Agreement pursuant to any other provision hereof:

     (a)  This Agreement may be terminated by the Company by notice to you or by
you by notice to the Company at any time prior to the time this Agreement shall
become effective as to all its provisions, and any such termination shall be
without liability on the part of the Company to any Underwriter (except for the
expenses to be paid or reimbursed by the Company pursuant to Sections 6 and 8
hereof and except to the extent provided in Section 10 hereof) or of any
Underwriter to the Company (except to the extent provided in Section 10 hereof).

     (b)  This Agreement may also be terminated by you prior to the First
Closing Date by notice to the Company (i) if additional material governmental
restrictions, not in force and effect on the date hereof, shall have been
imposed upon trading in securities generally or minimum or maximum prices shall
have been generally established on the New York Stock Exchange, on the American
Stock Exchange or in the over the counter market by the NASD, or trading in
securities generally shall have been suspended on either such Exchange or in the
over the counter market by the NASD, or a general banking moratorium shall have
been established by Federal, New York or California authorities, (ii) if an
outbreak of major hostilities or other national or international calamity or any
substantial change in political,

                                       22
<PAGE>

financial or economic conditions shall have occurred or shall have accelerated
or escalated to such an extent, as, in the judgment of the Representatives, to
affect adversely the marketability of the Common Shares, (iii) if any adverse
event shall have occurred or shall exist which makes untrue or incorrect in any
material respect any statement or information contained in the Registration
Statement or Prospectus or which is not reflected in the Registration Statement
or Prospectus but should be reflected therein in order to make the statements or
information contained therein not misleading in any material respect, or (iv) if
there shall be any action, suit or proceeding pending or threatened, or there
shall have been any development or prospective development involving
particularly the business or properties or securities of the Company or any of
its subsidiaries or the transactions contemplated by this Agreement, which, in
the reasonable judgment of the Representatives, may materially and adversely
affect the Company's business or earnings and makes it impracticable or
inadvisable to offer or sell the Common Shares.  Any termination pursuant to
this subsection (b) shall without liability on the part of any Underwriter to
the Company or on the part of the Company to any Underwriter (except for
expenses to be paid or reimbursed by the Company pursuant to Sections 6 and 8
hereof and except to the extent provided in Section 10 hereof.

     (c)  This Agreement shall also terminate at 5:00 P.M., California time, on
the tenth full business day after the Registration Statement shall have become
effective if the initial public offering price of the Common Shares shall not
then as yet have been determined as provided in Section 4 hereof.  Any
termination pursuant to this subsection (c) shall without liability on the part
of any Underwriter to the Company or on the part of the Company to any
Underwriter (except for expenses to be paid or reimbursed by the Company
pursuant to Sections 6 and 8 hereof and except to the extent provided in
Section 10 hereof.

     SECTION 14.    REPRESENTATIONS AND INDEMNITIES TO SURVIVE DELIVERY.  The
respective indemnities, agreements, representations, warranties and other
statements of the Company, of its officers and of the several Underwriters set
forth in or made pursuant to this Agreement will remain in full force and
effect, regardless of any investigation made by or on behalf of any Underwriter
or the Company or any of its or their partners, officers or directors or any
controlling person, as the case may be, and will survive delivery of and payment
for the Common Shares sold hereunder and any termination of this Agreement.

     SECTION 15.    NOTICES.  All communications hereunder shall be in writing
and, if sent to the Representatives shall be mailed, delivered or telegraphed
and confirmed to you at 600 Montgomery Street, San Francisco, California 94111,
attention:  David Baylor, Esq., with a copy to Latham & Watkins, 1001
Pennsylvania Ave. N.W., Suite 1300, Washington, D.C.  20004-2505, attention:
John D. Watson, Jr., Esq.; and if sent to the Company shall be mailed, delivered
or telegraphed and confirmed to the Company at 500 108th Avenue, N.E., Suite
2600, Bellevue, WA 98004 with a copy to Hahn & Hessen LLP at 350 Fifth Avenue,
New York, NY 10118, attention: James Kardon, Esq.  The Company or you may change
the address for receipt of communications hereunder by giving notice to the
others.

     SECTION 16.    SUCCESSORS.  This Agreement will inure to the benefit of and
be binding upon the parties hereto, including any substitute Underwriters
pursuant to Section 11 hereof, and to the benefit of the officers and directors
and controlling persons referred to in Section 10, and in each case their
respective successors, personal representatives and assigns, and no other person
will have any right or obligation hereunder.  No such assignment shall relieve
any party of its obligations hereunder.  The term "successors" shall not include
any purchaser of the Common Shares as such from any of the Underwriters merely
by reason of such purchase.

                                       23
<PAGE>

     SECTION 17.    REPRESENTATION OF UNDERWRITERS.  You will act as
Representatives for the several Underwriters in connection with all dealings
hereunder, and any action under or in respect of this Agreement taken by you
jointly or by Montgomery Securities, as Representatives, will be binding upon
all the Underwriters.

     SECTION 18.    PARTIAL UNENFORCEABILITY.  The invalidity or
unenforceability of any Section, paragraph or provision of this Agreement shall
not affect the validity or enforceability of any other Section, paragraph or
provision hereof.  If any Section, paragraph or provision of this Agreement is
for any reason determined to be invalid or unenforceable, there shall be deemed
to be made such minor changes (and only such minor changes) as are necessary to
make it valid and enforceable.

     SECTION 19.    APPLICABLE LAW.  This Agreement shall be governed by and
construed in accordance with the internal laws (and not the laws pertaining to
conflicts of laws) of the State of California.

     SECTION 20.    GENERAL.  This Agreement constitutes the entire agreement of
the parties to this Agreement and supersedes all prior written or oral and all
contemporaneous oral agreements, understandings and negotiations with respect to
the subject matter hereof.  This Agreement may be executed in several
counterparts, each one of which shall be an original, and all of which shall
constitute one and the same document.

     In this Agreement, the masculine, feminine and neuter genders and the
singular and the plural include one another.  The section headings in this
Agreement are for the convenience of the parties only and will not affect the
construction or interpretation of this Agreement.  This Agreement may be amended
or modified, and the observance of any term of this Agreement may be waived,
only by a writing signed by the Company and you.

                                       24
<PAGE>

     If the foregoing is in accordance with your understanding of our agreement,
kindly sign and return to us the enclosed copies hereof, whereupon it will
become a binding agreement between the Company and the several Underwriters
including you, all in accordance with its terms.

                              Very truly yours,

                              ADVANCED RADIO TELECOM CORP.



                              By: __________________________
                                   Name:
                                   Title:


The foregoing Underwriting Agreement
is hereby confirmed and accepted by
us in San Francisco, California as of
the date first above written.

MONTGOMERY SECURITIES
DEUTSCHE MORGAN GRENFELL/C. J. LAWRENCE INC.

Acting as Representatives of the
several Underwriters named in
the attached Schedule A.

MONTGOMERY SECURITIES



By:
     Name:
     Title:

DEUTSCHE MORGAN GRENFELL/C.J. LAWRENCE INC.



By:
     Name:
     Title:

                                       25
<PAGE>


                                   SCHEDULE A


                                                                  Number of Firm
                                                             Common Shares to be
Name of Underwriter                                                    Purchased
- -------------------                                                    --------

Montgomery Securities. . . . . . . . . . . . . . . . . . . . . .
Deutsche Morgan Grenfell/C. J. Lawrence Inc. . . . . . . . . . .





                                                                  --------------
Total
                                                                  --------------
                                                                  --------------

                                       26
<PAGE>

                                   SCHEDULE B


                                                                __________, 1996

                          PRICE DETERMINATION AGREEMENT

     Referring to Section 4 of the Underwriting Agreement dated __________,
1996, between the Company and the Underwriters as therein defined with respect
to the purchase and sale of the Common Shares, we hereby confirm our agreement
that the initial public offering price of the Common Shares shall be $_____ per
share; that the underwriting discount shall be $_____ per share; and that the
purchase price to be paid by the several Underwriters for the Common Shares to
be purchased from the Company shall be $_____ per share.

     This Agreement may be executed in various counterparts which together shall
constitute one and the same Agreement.

                    MONTGOMERY SECURITIES
                    DEUTSCHE MORGAN GRENFELL/C. J. LAWRENCE INC.

                    Acting on behalf of the several Underwriters
                    named in Schedule A to the Underwriting Agreement


                    MONTGOMERY SECURITIES



                    By:
                         Name:
                         Title:

                    DEUTSCHE MORGAN GRENFELL/C. J. LAWRENCE INC.



                    By:
                         Name:
                         Title:



ADVANCED RADIO TELECOM CORP.



By:
     Name:
     Title:

                                       27
<PAGE>

                                    EXHIBIT A

             PRE-TRANSACTIONS CAPITALIZATION OF THE COMPANY AND ART

                                       A-1
<PAGE>

                                    EXHIBIT B

             POST-TRANSACTIONS CAPITALIZATION OF THE COMPANY AND ART

                                       B-1
<PAGE>

                                    EXHIBIT C

                      FORM OF OPINION OF HAHN & HESSEN LLP

     (a)  Each of the Company and its subsidiaries has been duly formed as a
corporation and is validly existing in good standing under the laws of its
jurisdiction of incorporation and has all requisite corporate power and
authority to own, lease and operate its properties and to conduct its business
as described in the Prospectus.  Each of the Company and its subsidiaries is
duly qualified to do business and is in good standing as a foreign corporation
in each jurisdiction in which the nature of its business or its ownership or
leasing of property requires such qualification, except where the failure to be
so qualified would not have, either individually or in the aggregate, a material
adverse effect on the assets, properties, business, management, earnings, net
worth, results of operations, condition (financial or otherwise) or business
prospects of the Company and its subsidiaries, taken as a whole.  No proceeding
has been instituted in any such jurisdiction, revoking, limiting or curtailing,
or seeking to revoke, limit or curtail, such power and authority or
qualification.

     (b)  ART Licenses is the only subsidiary of the Company.  The Company owns
all of the outstanding capital stock of ART Licenses; all such capital stock has
been duly authorized and validly issued and is fully paid and nonassessable,
free and clear of any security interest, claim, lien, encumbrance or adverse
interest of any nature; and all of such capital stock was not issued in
violation of any preemptive or similar rights.  There are no outstanding
subscriptions, rights, warrants, calls, commitments of sale or options to
acquire, or instruments convertible into or exchangeable for, any such shares of
capital stock or other equity interest of ART Licenses.

     (c)  The Company and its subsidiaries do not have any ownership interest in
any joint venture, other than the Company's 50% ownership interest in ART West.

     (d)  Prior to consummation of the Transactions, the Company and ART have
authorized and outstanding capital stock as set forth in Exhibit A hereto.  All
such issued and outstanding shares of capital stock of the Company and ART have
been duly authorized and validly issued, are fully paid and non-assessable and
were not issued in violation of any preemptive or similar rights.  The shares of
capital stock of ART owned by the Company prior to completion of the Merger are
free and clear of any security interest, claim, lien, encumbrance or adverse
interest of any nature.  Upon consummation of the Transactions, the Company will
have authorized and outstanding capital stock as set forth in Exhibit B hereto
and an authorized and outstanding capitalization as set forth in the Prospectus
under the caption "Capitalization."  All such issued and outstanding shares of
capital stock of the Company will have been duly authorized and validly issued,
will be fully paid and non-assessable and will not have been issued in violation
of any preemptive or similar rights.  Except as disclosed in the Prospectus,
there are, and there will be, no outstanding subscriptions, rights, warrants,
calls, commitments of sale or options to acquire, or instruments convertible
into or exchangeable for, any capital stock of the Company or ART  The
description of the Company's stock option, stock bonus and other stock plans or
arrangements, and the options or other rights granted and exercised thereunder,
set forth in the Prospectus accurately and fairly presents the information
required to be shown with respect to such plans, arrangements, options and
rights.

     (e)  The certificates evidencing the Common Shares to be delivered
hereunder are in due and proper form under Delaware law, and when duly
countersigned by the Company's transfer agent and registrar, and delivered to
you or upon your order against payment of the agreed consideration therefor in
accordance with the provisions of this Agreement, the Common Shares represented
thereby will be

                                       C-1
<PAGE>

duly authorized and validly issued, fully paid and nonassessable, will not have
been issued in violation of or subject to any preemptive rights or other rights
to subscribe for or purchase securities and will conform in all respects to the
description thereof contained in the Prospectus.  No preemptive rights or other
rights to subscribe for or purchase exist with respect to the issuance and sale
of the Common Shares by the Company pursuant to this Agreement.  No stockholder
of the Company has any right which has not been waived to require the Company to
register the sale of any shares owned by such stockholder under the Act in the
Offering contemplated by this Agreement.  No further approval or authority of
the stockholders or the Board of Directors will be required for the issuance and
sale of the Common Shares to be sold by the Company as contemplated herein.

     (f)  (i)  The Registration Statement has become effective under the Act,
and, to the best of such counsel's knowledge, no stop order suspending the
effectiveness of the Registration Statement or preventing the use of the
Prospectus has been issued and no proceedings for that purpose have been
instituted or are pending or contemplated by the Commission; any required filing
of the Prospectus and any supplement thereto pursuant to Rule 424(b) of the
Rules and Regulations has been made in the manner and within the time period
required by such Rule 424(b); (ii) the Registration Statement, the Prospectus
and each amendment or supplement thereto (except for the financial statements
and schedules included therein as to which such counsel need express no opinion)
comply as to form in all material respects with the requirements of the Act and
the Rules and Regulations; (iii) there are no franchises, leases, contracts,
agreements or documents of a character required to be disclosed in the
Registration Statement or Prospectus or to be filed as exhibits to the
Registration Statement which are not disclosed or filed, as required; (iv) there
are no legal or governmental actions, suits or proceedings pending or threatened
against the Company which are required to be described in the Prospectus which
are not described as required; and (v) such counsel has no reason to believe
that any of such documents (except for any financial statements and schedules
included in such documents as to which such counsel need express no opinion),
when read together and with the other information in the Registration Statement
or Prospectus as of the date of such Registration Statement or Prospectus
contained an untrue statement of a material fact or omitted to state a material
fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made not misleading.

     (g)  The Company has all requisite corporate power and authority to enter
into the Operative Documents and to perform the transactions contemplated hereby
and thereby.  Each of the Operative Documents has been duly authorized, executed
and delivered by the Company and constitutes a legally valid and binding
obligation of the Company, enforceable against the Company in accordance with
its terms.  No approval, authorization, order, consent, registration, filing,
qualification, license or permit of or with any court, regulatory,
administrative or other governmental body is required for the execution and
delivery of this Agreement by the Company or the consummation of the
transactions contemplated by this Agreement, except such as have been obtained
and are in full force and effect under the Act and such as may be required under
applicable Blue Sky laws in connection with the purchase and distribution of the
Common Shares by the Underwriters and the clearance of such offering with the
NASD.

     (h)  None of the execution, delivery and performance of the Operative
Documents by the Company, the compliance by the Company with all of the
provisions hereof and thereof, the issuance and sale of the Common Shares, the
consummation by the Company and its subsidiaries of the Transactions and the
transactions contemplated hereby and thereby (i) require any consent, approval,
authorization or other order of or filing, registration, qualification, license
or permit of or with, any court, regulatory body, administrative agency or other
governmental body (including, without limitation, the FCC), other than those
that have been obtained and are in full force and effect, or (ii) violate,
conflict with, or constitute a breach of any of the terms or provisions of, or a
default under (or an event that with notice

                                       C-2

<PAGE>

or the lapse of time, or both, would constitute a default), or require consent
under, or result in the imposition of a lien or encumbrance on any properties of
the Company and its subsidiaries pursuant to (A) the charter or bylaws of the
Company or any of its subsidiaries, (B) any bond, debenture, note, mortgage,
deed of trust or other agreement, indenture or other instrument to which or by
which any of them is a party or by which any of them or any of their respective
property is or may be bound, (C) any local, state or Federal law, statute,
ordinance, rule, regulation or requirement (including, without limitation, the
Telecommunications Act, the rules and regulations of the FCC and the
environmental laws, statutes, ordinances, rules or regulations) applicable to
the Company, any of its subsidiaries or any of their respective assets or
properties or (D) any judgment, order or decree of any court or governmental
agency or authority having jurisdiction over the Company, any of its
subsidiaries or any of their assets or properties, that, in the case of clauses
(B), (C) and (D), would reasonably be expected, either individually or in the
aggregate, to result in a Material Adverse Effect.

     (i)  Neither the Company nor any of its subsidiaries is or, after giving
effect to the Transactions, will be (i) in violation of its charter or bylaws,
(ii) in default in the performance of any material obligation, agreement or
condition contained in any bond, debenture, note or any other evidence of
indebtedness or in any other agreement, indenture or instrument material to the
conduct of the business of the Company and its subsidiaries, taken as a whole,
to which any of them is a party, or by which any of them or any of their
respective properties is bound or (iii) in violation of any local, state or
Federal law, statute, ordinance, rule, regulation, requirement, judgment or
court decree (including, without limitation, the Telecommunications Act and the
rules and regulations of the FCC and environmental laws, statutes, ordinances,
rules, regulations, judgments or court decrees) applicable to any of them or any
of their respective assets or properties (whether owned or leased), other than,
in the case of clauses (ii) and (iii), any default or violation that could not
reasonably be expected to have a Material Adverse Effect.  There exists no
condition that, with notice, the passage of time or otherwise, would constitute
a default under any such document or instrument that could be expected to have a
Material Adverse Effect.

     (j)  There is (i) no action, suit or proceeding before or by any court,
arbitrator or governmental agency, body or official, domestic or foreign, now
pending or threatened or contemplated to which the Company or any of its
subsidiaries is or may be a party or to which the business or property of any of
them is subject, (ii) no local, state or Federal law, statute, ordinance, rule,
regulation, requirement, judgment or court decree (including, without
limitation, the Telecommunications Act and the rules and regulations of the FCC)
or order has been enacted, adopted or issued by any governmental agency or, to
the best of such counsel's knowledge, that has been proposed by any governmental
body or (iii) no injunction, restraining order or order of any nature by a
Federal or state court or foreign court of competent jurisdiction to which the
Company, any of its subsidiaries or their business, assets, or property are, or
could reasonably be expected to be subject.

     (k)  The statements under the captions "Capitalization," "Description of
Capital Stock," "Description of Certain Indebtedness," "Shares Eligible for
Future Sale" and "Underwriting" in the Prospectus and Items 14 and 15 of Part II
of the Registration Statement, insofar as such statements constitute a summary
of legal matters, documents or proceedings referred to therein, fairly and
accurately present the information called for with respect to such legal
matters, documents and proceedings.


     (l)  Neither the Company nor any of its subsidiaries is (i) an "investment
company" or a company "controlled" by an "investment company" within the meaning
of the Investment Company Act of 1940, as amended, or (ii) a "holding company"
or a "subsidiary company" or an "affiliate" of a holding company within the
meaning of the Public Utility Holding Company Act of 1935, as amended.

                                       C-3
<PAGE>

     In rendering such opinion, such counsel may rely as to matters of local
law, on opinions of local counsel, and as to matters of fact, on certificates of
officers of the Company and of governmental officials, in which case their
opinion is to state that they are so doing and that the Underwriters are
justified in relying on such opinions or certificates and copies of said
opinions or certificates are to be attached to the opinion.  Such counsel shall
also include a statement to the effect that nothing has come to such counsel's
attention that would lead such counsel to believe that either at the effective
date of the Registration Statement or at the applicable Closing Date the
Registration Statement or the Prospectus, or any such amendment or supplement,
contains any untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading.

                                       C-4
<PAGE>

                                    EXHIBIT D

                  FORM OF OPINION OF PIERSON & BURNETT LLP

     (a)  Each of the Company and its subsidiaries has such Permits as are
necessary to own, lease and operate their respective properties and to conduct
their respective business in the manner described in the Prospectus.  Each of
the Company and its subsidiaries has fulfilled and performed all of its material
obligations with respect to such Permits and no event has occurred which allows,
or after notice or lapse of time would allow, revocation or termination thereof
or result in any other material impairment of the rights of the holder of any
such Permit, except for any such impairments which would not, individually or in
the aggregate, have a Material Adverse Effect.  Except as described in the
Prospectus, such Permits contain no restrictions that are materially burdensome
to the Company and its subsidiaries, taken as a whole.

     (b)  Except as described in the Prospectus, (i) the Company and its
subsidiaries own, possess or have the right to employ or have applied for all
such Permits, Licenses and Intellectual Property as are necessary to own, lease
and operate their respective properties and to conduct their respective business
in the manner described in the Prospectus; (ii) each of the Company and its
subsidiaries has fulfilled and performed all of its material obligations with
respect to such Licenses and other Intellectual Property and no event has
occurred which allows, or after notice or lapse of time would allow, revocation
or termination thereof or result in any other material impairment of the rights
of the holder of any such Intellectual Property; (iii) such Intellectual
Property contain no restrictions that are materially burdensome to the Company
and its subsidiaries, taken as a whole; and (iv) the use of the Intellectual
Property in connection with the business and operations of the Company and its
subsidiaries does not infringe on the rights of any person, except where such
infringement would not have a Material Adverse Effect.

     (c)  The Company and its subsidiaries have timely filed all renewal
applications with respect to all Licenses possessed by any of them.  No protests
or competing applications have been filed with respect to such renewal
applications, and nothing has come to the Company's or any of its subsidiaries'
attention that would lead them to conclude that such renewal applications will
not be granted by the appropriate regulatory agency or body in the ordinary
course.  The Company and its subsidiaries are authorized under the
Telecommunications Act, and the rules and regulations promulgated thereunder, to
continue to provide the services which are the subject of such renewal
applications during the pendency thereof.

     (d)  The development, implementation and operation of the 38 GHz wireless
broadband telecommunications services network as described, and in the markets
described, in the Prospectus will not (i) result in any violation of the
provisions of the charter or bylaws of the Company or any of its subsidiaries,
(ii) result in any violation of any applicable law, administrative regulation or
administrative or court decree (including, without limitation, the
Telecommunication Act, and the rules and regulations of the FCC and
environmental laws), or (iii) conflict with or constitute a breach or violation
of, or constitute a default under, or result in the creation or imposition of
any lien, charge or encumbrance upon any property or assets of the Company or
its subsidiaries pursuant to, any contract, indenture, mortgage, loan agreement,
note, lease or other instrument to which the Company or any of its subsidiaries
is a party or by which any of them may be bound, or to which any of their
property is subject, except, in the case of clauses (ii) and (iii) above, any
such violations, conflicts or breaches that would not, individually or in the
aggregate, have a Material Adverse Effect.

                                       D-1
<PAGE>

     (e)  The business and operations conducted and proposed to be conducted by
the Company and its subsidiaries as described in the Prospectus are not
regulated by any public service or public utility commissions in the States in
which the Company and its subsidiaries conduct or propose to conduct such
business and operations as described in the Prospectus; and, subject to the
provisions of Section 332(c)(3) of the Telecommunications Act, neither the
Company nor any of its subsidiaries is or will be required to obtain any License
from any public service or public utility commission in any such State.

     (f)  None of the execution, delivery and performance of the Operative
Documents by the Company, the compliance by the Company with all of the
provisions hereof and thereof, the issuance and sale of the Common Shares, the
consummation by the Company and its subsidiaries of the Transactions and the
transactions contemplated hereby and thereby (i) require any consent, approval,
authorization or other order of or filing, registration, qualification, license
or permit of or with, the FCC, other than those that have been obtained and are
in full force and effect, or (ii) violate, conflict with, or constitute a breach
of any of the terms or provisions of, or a default under (or an event that with
notice or the lapse of time, or both, would constitute a default), or require
consent under, or result in the imposition of a lien or encumbrance on any
properties of the Company or any of its subsidiaries pursuant to (A) the
Telecommunications Act or the rules and regulations of the FCC applicable to the
Company, any of its subsidiaries or any of their respective assets or properties
or (B) any judgment, order or decree of any court or governmental agency or
authority having jurisdiction over the Company, any of its subsidiaries or any
of their assets or properties, that, in the case of clauses (A) and (B), would
reasonably be expected, either individually or in the aggregate, to result in a
Material Adverse Effect.

     (g)  Neither the Company nor any of its subsidiaries is or, after giving
effect to the Transactions, will be in violation of the Telecommunications Act
and the rules and regulations of the FCC applicable to the Company, any of its
subsidiaries or any of their respective assets or properties (whether owned or
leased), other than any violation that could not reasonably be expected to have
a Material Adverse Effect.

     (h)  Other than rulemaking procedures of general applicability to the
wireless broadband telecommunications industry, there is (i) no action, suit or
proceeding before or by the FCC, now pending or threatened or contemplated to
which the Company or any of its subsidiaries is or may be a party or to which
the business or property of the Company or any of its subsidiaries is subject,
or (ii) no amendment or change to the Telecommunications Act and the rules and
regulations of the FCC has been enacted, adopted or issued by the FCC or, to the
best of such counsel's knowledge, that has been proposed by the FCC.

     (i)  Each of the Company and its subsidiaries has filed all reports
required to be filed with the FCC.

                                       D-2

<PAGE>


              RESTATED AND AMENDED CERTIFICATE OF INCORPORATION
                                       OF
                        ADVANCED RADIO TECHNOLOGY, LTD.




     Advanced Radio Technology, Ltd., a corporation organized and existing 
under the laws of the State of Delaware, hereby certifies as follows:

     1.  The name of the corporation ("Corporation") is Advanced Radio 
Technology, Ltd. and its Certificate of Incorporation was filed with the 
Secretary of State on March 28, 1995.

     2.  This Restated and Amended Certificate of Incorporation restates and 
integrates and further amends the Certificate of Incorporation of the 
Corporation by increasing the number of authorized shares of the Corporation.

     3.  The text of the Certificate of Incorporation is hereby amended to read
as herein set forth in full:

     FIRST: The name of the Corporation is Advanced Radio Technology, Ltd.

     SECOND: The address, including street, number, city and county, of the 
registered office of the corporation in the State of Delaware is 9 East 
Loockerman Street, City of Dover 19901, County of Kent; and the name of the 
registered agent of the corporation in the State of Delaware at such address 
is National Corporate Research, Ltd.

     THIRD: The purpose of the corporation is to engage in any lawful act or 
activity for which corporations may be organized under the General Corporation 
Law of the State of Delaware.

     FOURTH: The total number of shares of all classes of stock which the 
Corporation shall have authority to issue is twenty million (20,000,000), 
which are divided into ten million (10,000,000) shares of Common Stock of a 
par value of $0.001 per share and ten million (10,000,000) shares of 
Preferred Stock of a par value of $0.001 per share.

     (a) Seven million (7,000,000) of the shares of Common Stock shall be 
designated as Class A Common Stock and three million (3,000,000) of the shares 
of Common Stock shall be designated as Class B Common Stock.

     (b) The shares of Preferred Stock may be issued from time


                                     1

<PAGE>


to time in one or more series as set forth in the resolution or resolutions 
providing for the issuance of such shares adopted by the Board of Directors. 
Shares in each such series shall be identical to the Common Stock in all 
respects, except that with respect to the liquidation preference for the 
Preferred Stock, which shall be equal to the aggregate consideration paid for 
such series, and not each share of the Preferred Stock in such series, as 
shall be stated in the resolution or resolutions providing for the issuance of 
such shares adopted by the Board of Directors pursuant to authority hereby 
vested in it. The number of shares of any such series so set forth in such 
resolution or resolutions may be increased (but not above the total number of 
shares of the series) or decreased (but not below the number of shares 
thereof then outstanding) by further resolution or resolutions adopted by the 
Board of Directors pursuant to authority hereby vested in it.

     (c) Shares of the Corporation's Common Stock and Preferred Stock may 
entitle the holder thereof to preemptive rights upon such terms and with such 
limitations as may be set forth in an agreement between the Corporation and 
shareholders of the Corporation owning all of the issued and outstanding 
shares of Common Stock and Preferred Stock of the Corporation.

     FIFTH: The corporation is to have perpetual existence.

     SIXTH: Whenever a compromise or arrangement is proposed between this 
corporation and its creditors or any class of them and/or between this 
corporation and its stockholders or any class of them, any court of equitable 
jurisdiction within the State of Delaware may, on the application in a summary 
way of this corporation or of any creditor or stockholder thereof or on the 
application of any receiver or receivers appointed for this corporation under 
the provisions of Section 291 of Title 8 of the Delaware Code or on the 
application of trustees in dissolution or of any receiver or receivers 
appointed for this corporation under the provisions of Section 279 of Title 8 
of the Delaware Code, order a meeting of the creditors or class of creditors 
and/or of the stockholders or class of stockholders of this corporation, as 
the case may be, to be summoned in such manner as the said court directs. 
If a majority in number representing three fourths in value of the creditors 
or class of creditors, and/or of the stockholders or class of stockholders of 
this corporation, as the case may be, agree to any compromise or arrangement 
and to any reorganization of this corporation as consequence of such compromise 
or arrangement, the said compromise or arrangement and the said 
reorganization shall, if sanctioned by the court to which the said application 
has been made, be binding on all the creditors or class of creditors, and/or 
on all the stockholders or class of stockholders, of this corporation, as the 
case may be, and also on this corporation.

     SEVENTH: For the management of the business and for the conduct of the 
affairs of the corporation, and in further


                                     2


<PAGE>


definition, limitation, and the regulation of the powers of the corporation 
and of its directors and of its stockholders or any class thereof, as the case 
may be, it is further provided:

     1.  The management of the business and the conduct of the affairs of the 
corporation shall be vested in its Board of Directors. The number of 
directors which shall constitute the whole Board of Directors shall be fixed 
by, or in the manner provided in, the Bylaws. The phrase "whole Board" and 
the phrase "total number of directors" shall be deemed to have the same 
meaning, to wit, the total number of directors which the corporation would have 
if there were no vacancies. No election of directors need be by written 
ballot.

     2.  After the original or other Bylaws of the corporation have been 
adopted, amended, or repealed, as the case may be, in accordance with the 
provisions of Section 109 of the General Corporation Law of the State of 
Delaware, and, after the corporation has received any payment for any of its 
stock, the power to adopt, amend, or repeal the Bylaws of the corporation may
be exercised by the Board of Directors of the corporation; provided, however, 
that any provision for the classification of directors of the corporation for 
staggered terms pursuant to the provisions of subsection (d) of SECTION 141 
of the General Corporation Law of the State of Delaware shall be set forth in 
an initial Bylaw or in a Bylaw adopted by the stockholders entitled to vote 
of the corporation, unless provisions for such classification shall be set 
forth in this certificate of incorporation.

     3.  Whenever the corporation shall be authorized to issue only one class
of stock, each outstanding share shall entitle the holder thereof to notice of, 
and the right to vote at, any meeting of stockholders. Whenever the 
corporation shall Be authorized to issue more than one class of stock, no 
outstanding share of any class of stock which is denied voting power under 
the provisions of the certificate of incorporation shall entitle the holder 
thereof to the right to vote at any meeting of stockholders except as the 
provisions of paragraph (2) of subsection (b) of Section 242 of the General 
Corporation Law of the State of Delaware shall otherwise require; provided, 
that no share of any such class which is otherwise denied voting power shall 
entitle the holder thereof to vote upon the increase or decrease in the number 
of authorized shares of said class.

     EIGHTH: The personal liability of the directors of the corporation is 
hereby eliminated to the fullest extent permitted by the provisions of paragraph
(7) of subsection (b) of Section 102 of the General Corporation Law of the 
State of Delaware, as the same may be amended and supplemented.

     NINTH: The corporation shall, to the fullest extent permitted by the 
provisions of Section 145 of the General Corporation Law


                                     3

<PAGE>


of the State of Delaware, as the same may be amended and supplemented, 
indemnify any and all persons whom it shall have power to indemnify under 
said section from and against any and all of the expenses, liabilities, or 
other matters referred to in or covered by said section, and the 
indemnification provided for herein shall not be deemed exclusive of any 
other rights to which those indemnified may be entitled under any Bylaw, 
agreement, vote of stockholders or disinterested directors or otherwise, both 
as to action in his official capacity and as to action in another capacity 
while holding such officer, and shall continue as to a person who has ceased 
to be a director, office, employee, or agent and shall inure to the benefit 
of the heirs, executors, and administrators of such a person.

     TENTH: From time to time any of the provisions of this certificate of 
incorporation may be amended, altered, or repealed, and the provisions 
authorized by the laws of the State of Delaware at the time in force may be 
added or inserted in the manner and at the time prescribed by said laws, and 
all rights at any time conferred upon the stockholders of the corporation by 
this certificate of incorporation are granted subject to the provisions of 
this Article TENTH.

     4.  This Restated and Amended Certificate of Incorporation was duly adopted
by written consent of the stockholders in accordance with Sections 228, 242 and 
245 of the General Corporate Law of the State of Delaware and written notice 
of the adoption of this Restated and Amended Certificate of Incorporation has 
been given pursuant to Section 228 of the General Corporation Law of the 
State of Delaware to each and every stockholder entitled to such notice.

     IN WITNESS WHEREOF, the Corporation has caused this Restated and Amended 
Certificate of Incorporation to be signed and attested to by its duly 
authorized officers on this    day of April 1995.




                                          -----------------------
                                       By:   Matt Gove, Director,
                                               Vice President



ATTEST:

- ----------------------------
By: Dan Gulick, Director, Secretary

                                     4





<PAGE>

                                                                  EXHIBIT 2.1(a)

                                    AMENDED

                  CERTIFICATE OF DESIGNATION AND PREFERENCES
                                       OF
                           SERIES A PREFERRED STOCK
                               $0.001 PAR VALUE
                                        OF
                         ADVANCED RADIO TECHNOLOGY, LTD

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

                         PURSUANT TO SECTION 151 OF THE
                GENERAL CORPORATION LAW OF THE STATE OF DELAWARE

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


      ADVANCED RADIO TECHNOLOGY, LTD., a corporation organized and existing 
under and by virtue of the provisions of the General Corporation Law of the 
State of Delaware (the "Corporation") DOES HEREBY CERTIFY:

      1. That no shares of Series A Preferred Stock, $.001 par value per 
share, (the "Series A Preferred Stock" or the "Series"), have been issued; and

      2. That pursuant to authority conferred upon the Board of Directors of 
the Corporation (the "Board") by the Certificate of Incorporation of the 
Corporation, the Board, by a Unanimous Written Consent dated May 1, 1995, 
adopted the following resolution authorizing the creation and issuance of a 
series of 36,056 shares of Series A Preferred Stock, which resolution is as 
follows:

      RESOLVED, that pursuant to authority expressly granted to and vested in 
the Board of Directors by the Certificate of Incorporation, as amended, of 
the Corporation, the Board hereby creates a series of 36,056 shares of Series 
A Preferred Stock, $0.001 par value per share, of the Corporation and 
authorizes the issuance thereof, and hereby fixes the designation thereof, 
and the voting powers, preferences and relative, participating, optional and 
other special limitations or restrictions thereon (in addition to the 
designations, preferences and relative, participating and other special 
rights, and the qualifications, limitations or restrictions thereof, set 
forth in the Certificate of Incorporation, as amended, of the Corporation, 
which are applicable to the preferred stock of all series) as follows:

      1  DESIGNATION.  The shares of the Series shall be designated "Series A 
Preferred Stock" (hereinafter referred to as the "Series A Preferred Stock"). 
The number of shares constituting the Series shall be 36,056, $0.001 par 
value per share, and this series shall represent 3.2 percent of the issued

<PAGE>

and outstanding capital stock of all classes, both Common and Preferred, of 
the Corporation.  Upon issuance of the 36,056 shares of Series A 
Preferred Stock (and shares of Series B Preferred Stock representing four 
percent of the issued and outstanding shares of capital stock of the 
Corporation), the issued and outstanding shares of Class A Common Stock and 
the Class B Common Stock shall constitute 36 percent and 56.8 percent, 
respectively, of the issued and outstanding shares of capital stock of the 
Corporation.  The designation, rights and preferences of the shares of Series 
A Preferred Stock shall be identical to the Common Stock of the Corporation 
except with respect to the liquidation preference set forth in Section 3.

     The number of authorized shares of the Series mat be reduced to the 
extent any shares are not issued and outstanding by further resolution duly 
adopted by the Board of Directors of the Corporation and by filing amendments 
to the Certificate of Designations pursuant to the provisions of the General 
Corporation Law of the State of Delaware stating that such reduction has been 
so authorized, but the number of authorized shares of this Series shall not 
be increased.

     1 DIVIDENDS.  The Holders of the Series A Preferred Stock ("Holders") 
shall be entitled to receive dividends on each share of Preferred Stock on 
the same basis and in the same amounts as the holders of the Corporation's 
Common Stock are entitled to receive on each share of Common Stock when and 
if such dividends are declared by the Board and paid by the Corporation.

     2 LIQUIDATION.  

     1 PREFERENCE OF SERIES A PREFERRED STOCK.

     (i) Upon any liquidation, dissolution, or winding up of the Corporation, 
whether voluntary or involuntary, and after provision for the payment of 
creditors, the Holders shall be entitled to be paid an aggregate of $375,000, 
the amount equal to the aggregate consideration paid to the Corporation for 
all of the then issued and outstanding shares of the Series A Preferred 
Stock, before any distribution or payment is made upon any shares of Common 
Stock and any other series of stock junior to the Series A Preferred Stock 
but subject to the prior preferences of any series or class of stock of the 
Corporation senior to the Series A Preferred Stock.  The Series A Preferred 
Stock shall be deemed to be on a parity with any other series of Preferred 
Stock with respect to the preference of the shares of such series of 
Preferred Stock upon liquidation of the Corporation.

     (ii)  If upon any liquidation, dissolution or

                                  2

<PAGE>

winding up of the Corporation, the net assets of the Corporation to be 
distributed among the Holders shall be insufficient to permit payment in full 
to the Holders of such Series A Preferred Stock and any other series of 
Preferred Stock deemed to be on parity with the Preferred Stock, then all 
remaining net assets of the Corporation after the provision for the payment 
of the Corporation's debts and distribution to any senior stockholders shall 
be distributed ratably in proportion to the full amounts to which they would 
otherwise be entitled to receive.

     (iii) The sale, lease or exchange of all or substantially all of the 
Corporation's assets or the merger or consolidation of the Corporation which 
results in the holders of Common Stock of the Corporation receiving in 
exchange for such Common Stock cash, notes, debentures or other evidences of 
indebtedness or obligations to pay cash, or preferred stock of the surviving 
entity which ranks on a parity with or senior to the Series A Preferred Stock 
as to dividends or upon liquidation, dissolution or winding up shall be 
deemed to be a liquidation, dissolution or winding up of the affairs of the 
Corporation within the meaning of this paragraph iii of Section A. In the 
case of mergers or consolidations of the Corporation where holders of Common 
Stock of the Corporation receive, in exchange for such Common Stock, common 
stock or preferred stock in the surviving entity (whether or not the 
surviving entity is the Corporation) of such merger or consolidation, or 
common stock or preferred stock of another entity, which is junior as to 
dividends and upon liquidation, dissolution or winding up to the Series A 
Preferred Stock, the merger agreement or consolidation agreement shall 
expressly provide that the Series A Preferred Stock shall become preferred 
stock of such surviving entity or other entity, as the case may be, with the 
equivalent rights to the rights set forth herein. In the event of a merger or 
consolidation of the Corporation where the consideration received by the 
holders of common stock consists of two or more types of the consideration 
set forth above, the holders of the Series A Preferred Stock shall be 
entitled to receive either cash or securities based upon the foregoing in the 
same proportion as the holders of Common Stock of the Corporation are 
receiving cash or debt securities, or equity securities in the surviving 
entity or other entity.

     3. VOTING RIGHTS.  The Holders shall vote with the holders of the Common 
Stock, shall have one vote per share of Series A Preferred Stock and shall be 
entitled to such notice of any meeting as the holders of the Corporation's 
Common Stock.

     4. COVENANTS.  In addition to any other rights provided

                                  3
<PAGE>

by law, so long as any Series A Preferred Stock is outstanding, the 
Corporation, without first obtaining the affirmative vote or written consent 
of the holders of not less than a majority of such outstanding shares of 
Series A Preferred Stock, will not:

     1 amend or repeal any provision of, or add any provision to, the 
Corporation's Certificate of Incorporation or By-Laws if such action would 
alter adversely the liquidation preferences, of, or the restrictions provided 
for the benefit of, any Series A Preferred Stock;

     2 authorize or issue shares of any class or series of stock not 
expressly authorized herein having any preference or priority as to dividends 
or assets or other rights superior to any such preference or priority of the 
Series A Preferred Stock, or authorize or issue shares of stock of any class 
or any bonds, debentures, notes or other obligations convertible into or 
exchangeable for, or having option rights to purchase, any shares of stock of 
the Corporation having any preference or priority as to liquidation superior 
to any such preference or priority of the Series A Preferred Stock; or

     3 reclassify any class or series of any stock junior in liquidation 
rights to the Series A Preferred Stock ("Junior Stock") into stock senior to 
the Series A Preferred Stock with respect to any liquidation preference 
superior to any such preference or priority of the Series A Preferred Stock.

     The authorization and issuance of shares of Preferred Stock with a 
liquidation preference on a parity to the liquidation preference of the 
Series A Preferred Stock shall not require the approval of the holders of the 
outstanding shares of Series A Preferred Stock.

     5 ADJUSTMENT IN NUMBER OF SHARES.  If the Corporation shall (i) 
subdivide or reclassify the outstanding shares of Common Stock into a greater 
number of shares, or (ii) combine or reclassify the outstanding Common Stock 
into a smaller number of shares, the number of shares of Series A Preferred 
Stock held by each holder on the effective date of such subdivision, 
combination or reclassification shall be proportionately adjusted. Successive 
adjustments shall be made whenever any event specified above shall occur.

     6 EXCLUSION OF OTHER RIGHTS.  Except as may otherwise be required by 
law, the shares of Series A Preferred Stock shall not have any preferences or 
relative, participating, optional or

                                  4
<PAGE>

other special rights, other than a preference regarding liquidation as 
specifically set forth in this resolution and in the Corporation's 
Certificate of Incorporation.

     7 HEADINGS OF SUBDIVISIONS.  The headings of the various subdivisions 
hereof are for convenience of reference only and shall not affect the 
interpretation of any of the provisions hereof.

     8 SEVERABILITY OF PROVISIONS.  If any right, preference or limitation of 
the Series A Preferred Stock set forth in this Certificate (as such 
Certificate may be amended from time to time) is invalid, unlawful or 
incapable of being enforced by reason of any rule of law or public policy, 
all other rights, preferences and limitations set forth in this Certificate 
(as so amended) which can be given effect without the invalid, unlawful or 
unenforceable right, preference or limitation shall, nevertheless, remain in 
full force and effect, and no right, preference or limitation herein set 
forth shall be deemed dependent upon any other such right, preference or 
limitation unless so expressed herein.

     9 STATUS OF REACQUIRED SHARES.  Shares of Series A Preferred Stock which 
have been issued and reacquired in any manner shall (upon compliance with any 
applicable provisions of the laws of the State of Delaware) have the status 
of authorized and unissued shares of Preferred Stock issuable in series 
undesignated as to series and may be redesignated and reissued.

     11. AMENDMENT OF CERTIFICATE OF DESIGNATIONS. This Certificate of 
Designation may be amended by action of the Board of Directors of the 
Corporation without the vote of the Holders or any other stockholders of the 
Corporation to implement the provisions of the purchase agreement dated April 
21, 1995 between Landover Holdings Corporation and Advanced Radio Technologies 
Corporation.

     IN WITNESS WHEREOF, the Corporation has caused this Certificate to be 
signed in its name and on its behalf by its President and attested to this 
  th day of May, 1995.

                                           ADVANCED RADIO TECHNOLOGY, LTD.


                                           By: ____________________________
                                               Matt Gove, Vice President

                                  5
<PAGE>

ATTESTED

____________________________________
Dan Gulick, Secretary


                                  6

<PAGE>

                                                              Exhibit 2-1(b)


                                        
                            CERTIFICATE OF AMENDMENT
                                       OF
                AMENDED AND RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                     ADVANCED RADIO TECHNOLOGIES CORPORATION


     Advanced Radio Technologies Corporation, a corporation organized and
existing under the laws of the State of Delaware, hereby certifies as follows:
          
     FIRST: The name of the corporation (the "Corporation") is Advanced Radio
Technologies Corporation and its original Certificate of Incorporation was filed
with the Secretary of State on August 23, 1993.

     SECOND:   The Certificate of Incorporation currently authorizes the
issuance of 3,000 shares of all classes, which are divided into (i) 2,000 shares
of common stock, $.01 par value, of which 340 shares are outstanding and (ii)
1,000 shares of Preferred Stock, of which one (1) share is designated as Series
A Redeemable Preferred Stock, $0.01 par value. 

     THIRD:  The Corporation hereby amends its Amended and Restated Certificate
of Incorporation as follows:

     Paragraph 4A of the Amended and Restated Certificate of Incorporation is
hereby amended in its entirety to read as follows:

          "4A. The total number of shares of all classes of stock which the
     Corporation shall have authority to issue is one hundred ten million
     (110,000,000), which are divided into one hundred million (100,000,000)
     shares of Common Stock of a par value of $0.001 per share ("Common Stock")
     and ten million (10,000,000) shares of Preferred Stock of a par value of
     $0.001 per share ("Preferred Stock").  Upon the effectiveness of this
     Certificate of Amendment to Amended and Restated Certificate of
     Incorporation, each share of Common Stock issued and outstanding prior to
     the filing date of this Certificate of Amendment of Amended and Restated
     Certificate of Incorporation shall be converted into 29,450.16 fully paid
     and nonassessable shares of Common Stock, par value $0.001 per share,
     without further action by any holder of Common Stock.  To reflect said
     conversion, each certificate representing shares of Common Stock heretofore
     issued and outstanding shall represent, upon surrender of the certificate
     or certificates representing the shares being converted hereunder to the
     Corporation at its principal office, a like number of shares of Common
     Stock issued and outstanding after such conversion; and the holder of
     record of each such certificate shall receive a new certificate
     representing a number of shares of Common Stock of the kind authorized by
     this Certificate of Amendment of Amended and Restated Certificate of
     Incorporation, equal to the number of shares represented by said
     certificate for heretofore issued and outstanding shares, so that upon the
     filing 


                                        
<PAGE>


     of this Certificate of Amendment of Amended and Restated Certificate of
     Incorporation each holder of Common Stock will have or be entitled to
     certificates representing in the aggregate 29,450.16 shares of Common Stock
     for each share of Common Stock held prior to the filing of this Certificate
     of Amendment of Amended and Restated Certificate of Incorporation."

     FOURTH:  The amendment effected herein was authorized by the consent in
writing, setting forth the action so taken, of the holders of a majority of the
outstanding shares entitled to vote thereon pursuant to Sections 228 and 242 of
the General Corporation Law of the State of Delaware.

          IN WITNESS WHEREOF, the Corporation has caused this amendment to the
Amended and Restated Certificate of Incorporation to be signed and attested to
by its duly authorized officers on this 21 day of June, 1996.



                                          By:                            
                                             -------------------------------
                                             Name:  W. Theodore Pierson, Jr.
                                             Title: Executive Vice President
                                                      and General Counsel

By:                                 
   ---------------------------------
   James Kardon
   Assistant Secretary






<PAGE>


                                                              Exhibit 2-1(c)


               AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

                                       OF

                     ADVANCED RADIO TECHNOLOGIES CORPORATION


     Advanced Radio Technologies Corporation, a corporation organized and
existing under the laws of the State of Delaware, hereby certifies as follows:

          1.   The name of the corporation (the "Corporation") is Advanced Radio
Technologies Corporation and its original Certificate of Incorporation was filed
with the Secretary of State of the State of Delaware on August 23, 1993.

          2.   This Amended and Restated Certificate of Incorporation of the
Corporation restates and integrates and further amends the Certificate of
Incorporation of the Corporation, as the same heretofore has been amended,
supplemented or restated (the "Certificate of Incorporation").

          3.  The text of the Certificate of Incorporation is hereby further
amended and restated to read in full as herein set forth:

          "FIRST:  The name of the Corporation is Advanced Radio Telecom Corp.

          SECOND:  The address of its registered office in the State of Delaware
is 1013 Centre Road, City of Wilmington, Delaware, 19805, County of New Castle.
The name of the registered agent at such address is Corporation Service Company.

          THIRD:  The purpose of the Corporation is to engage in any lawful act
or activity for which Corporations may be organized under the General
Corporation Law of the State of Delaware.

          FOURTH:

          (a)  The total number of shares of all classes of stock which the
Corporation shall have authority to issue is one hundred ten million
(110,000,000), which are divided into one hundred million (100,000,000) shares
of Common Stock of a par value of $0.001 per share ("Common Stock") and ten
million (10,000,000) shares of Preferred Stock of a par value of $0.001 per
share ("Preferred Stock").

          (b)  The Board of Directors of the Corporation is expressly authorized
at any time, and from time to time, to provide for the issuance of shares of
Preferred Stock in one or more series, with such designations, preferences and
relative, participating, optional or other special rights, and qualifications,
limitations, or restrictions thereof, as shall be stated and expressed in the
resolution or resolutions providing for the issue thereof adopted by the Board
of Directors.

          FIFTH:  The Corporation is to have perpetual existence.



<PAGE>


          SIXTH:  Whenever a compromise or arrangement is proposed between the
Corporation and its creditors or any class of them and/or between the
Corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of the Corporation or of any creditor or stockholder thereof or on the
application of any receiver or receivers appointed for the Corporation under the
provisions of Section 291 of Title 8 of the Delaware Code or on the application
of trustees in dissolution or of any receiver or receivers appointed for the
Corporation under the provisions of Section 279 of Title 8 of the Delaware Code,
order a meeting of the creditors or class of creditors and/or of the
stockholders or class of stockholders of the Corporation, as the case may be, to
be summoned in such manner as the said court directs.  If a majority in number
representing three fourths in value of the creditors or class of creditors,
and/or of the stockholders or class of stockholders of the Corporation, as the
case may be, agree to any compromise or arrangement and to any reorganization of
the Corporation as consequence of such compromise or arrangement, the said
compromise or arrangement and the said reorganization shall, if sanctioned by
the court to which the said application has been made, be binding on all the
creditors or class of creditors, and/or on all the stockholders or class of
stockholders, of the Corporation, as the case may be, and also on the
Corporation.

          SEVENTH:  For the management of the business and for the conduct of
the affairs of the Corporation, and in further definition, limitation, and the
regulation of the powers of the Corporation and of its directors and of its
stockholders or any class thereof, as the case may be, it is further provided:

          1.   NUMBER OF DIRECTORS. The management of the business and the
     conduct of the affairs of the Corporation shall be vested in its Board of
     Directors.  The number of directors which shall constitute the whole Board
     of Directors shall be fixed by, or in the manner provided in, the Bylaws.
     The phrase "whole Board" and the phrase "total number of directors" shall
     be deemed to have the same meaning, to wit, the total number of directors
     which the Corporation would have if there were no vacancies.  No election
     of directors need be by written ballot.

          2.   TERMS OF DIRECTORS. Except as otherwise provided in or fixed by
     or pursuant to the provisions of Article FOURTH hereof relating to the
     rights of the holders of any class or series of stock having a preference
     over the Common Stock as to dividends or upon liquidation or to elect
     directors under specified circumstances, the directors shall be classified,
     with respect to the time for which they severally hold office, into three
     classes, as nearly equal in number as possible, as shall be provided in the
     manner specified in the By-Laws of the Corporation.  One class shall be
     originally elected for a term expiring at the annual meeting of
     stockholders to be held in 1997, another class shall be originally elected
     for a term expiring at the annual meeting of stockholders to be held in
     1998, and another class shall be originally elected for a term expiring at
     the annual meeting of stockholders to be held in 1999, with each member of
     each class to hold office until a successor is elected and qualified.  At
     each annual meeting of stockholders of the Corporation and except as
     otherwise provided in or fixed by or pursuant to the provisions of Article
     FOURTH hereof relating to the rights of the holders of any class or series
     of stock having a preference over the Common Stock as


                                       -2-
<PAGE>


     to dividends or upon liquidation to elect directors under specified
     circumstances, the successors of the class of directors whose term expires
     at that meeting shall be elected to hold office for a term of three years.

          3.   NEWLY CREATED DIRECTORSHIPS AND VACANCIES.  Except as otherwise
     required by law and except as otherwise provided in or fixed by or pursuant
     to the provisions of Article FOURTH hereof relating to the rights of the
     holders of any class or series of stock having a preference over the Common
     Stock as to dividends or upon liquidation to elect directors under
     specified circumstances:  (i) newly created directorships resulting from
     any increase in the number of directors and any vacancies on the Board of
     Directors resulting from death, resignation, disqualification, removal or
     other cause shall be filled by the affirmative vote of a majority of the
     remaining directors then in office, even though less than a quorum of the
     Board of Directors; (ii) any director elected in accordance with the
     preceding clause (i) shall hold office for the remainder of the full term
     of the class of directors in which the new directorship was created or the
     vacancy occurred and until such director's successor shall have been
     elected and qualified; and (iii) no decrease in the number of directors
     constituting the Board of Directors shall shorten the term of any incumbent
     director.

          4.   REMOVAL.  Except as otherwise provided in or fixed by or pursuant
     to the provisions of Article FOURTH hereof relating to the rights of the
     holders of any class or series of stock having a preference over the Common
     Stock as to dividends or upon liquidation to elect directors under
     specified circumstances, any director may be removed from office only for
     cause by the affirmative vote of the holders of at least a majority of the
     combined voting power of the then outstanding shares of the Corporation's
     stock entitled to vote generally, voting together as a single class.
     Whenever in this Article SEVENTH hereof, the phrase, "the then outstanding
     shares of the Corporation's stock entitled to vote generally" is used, such
     phrase shall mean each then outstanding share of any class or series of the
     Corporation's stock that is entitled to vote generally in the election of
     the Corporation's directors.

          5.   AMENDMENT OR REPEAL OF THIS ARTICLE.  Notwithstanding any other
     provisions of this Article SEVENTH or any other Article hereof or of the
     By-Laws of the Corporation (and notwithstanding the fact that a lesser
     percentage may be specified from time to time by law, this Article SEVENTH,
     any other Article hereof, or the By-Laws of the Corporation), the
     provisions of this Article SEVENTH may not be altered, amended or repealed
     in any respect, nor may any provision inconsistent therewith be adopted,
     unless such alteration, amendment, repeal or adoption is approved by the
     affirmative vote of at least 75% of the combined voting power of the then
     outstanding shares of the Corporation's capital stock entitled to vote
     generally, voting together as a single class.

          6.   AMENDMENT OF BYLAWS.  After the original or other Bylaws of the
     Corporation have been adopted, amended, or repealed, as the case may be, in
     accordance with the provisions of Section 109 of the General Corporation
     Law of the State of Delaware, and, after the Corporation has received any
     payment for any of its stock, the power to


                                       -3-
<PAGE>


     adopt, amend, or repeal the Bylaws of the Corporation may be exercised by
     the Board of Directors of the Corporation, unless otherwise provided in the
     Bylaws.

          7.   VOTING POWER.  Whenever the Corporation shall be authorized to
     issue only one class of stock, each outstanding share shall entitle the
     holder thereof to notice of, and the right to vote at, any meeting of
     stockholders.  Whenever the Corporation shall be authorized to issue more
     than one class of stock, no outstanding share of any class of stock which
     is denied voting power under the provisions of the Certificate of
     Incorporation shall entitle the holder thereof to the right to vote at any
     meeting of stockholders except as the provisions of paragraph (2) of
     subsection (b) of Section 242 of the General Corporation Law of the State
     of Delaware shall otherwise require; provided, that no share of any such
     class which is otherwise denied voting power shall entitle the holder
     thereof to vote upon the increase or decrease in the number of authorized
     shares of said class.

          EIGHTH:  The personal liability of the directors of the Corporation is
hereby eliminated to the fullest extent permitted by the provisions of paragraph
(7) of subsection (b) of Section 102 of the General Corporation Law of the State
of Delaware, as the same may be amended and supplemented.  No amendment or
repeal of this Article EIGHTH shall apply to or have any effect on the liability
or alleged liability of any director of this Corporation for or with respect to
any acts or omissions of such director occurring prior to such amendment or
repeal.

          NINTH:  The Corporation shall, to the fullest extent permitted by the
provisions of Section 145 of the General Corporation Law of the State of
Delaware, as the same may be amended and supplemented, indemnify, and upon
request advance expenses to, any and all persons who is or was a party or is
threatened to be made a party to any threatened, pending or completed action,
suit, proceeding or claim, whether civil, criminal, administrative or
investigative, by reason of the fact that such person is or was or has agreed to
be a director or officer of this Corporation or while a director or officer is
or was serving at the request of this Corporation as a director, officer,
partner, trustee, employee or agent of any corporation, partnership, joint
venture, trust or other enterprise, including service with respect to employee
benefit plans, from and against any and all of the expenses, liabilities, or
other matters referred to in or covered by said section (including without
limitation attorneys fees and expenses); PROVIDED, HOWEVER, that the foregoing
shall not require this Corporation to indemnify or advance expenses to any
person in connection with any action, suit, proceeding, claim or counterclaim
initiated by or on behalf of such person other than solely to enforce rights
under this ARTICLE NINTH.  The indemnification provided for herein shall not be
deemed exclusive of any other rights to which those indemnified may be entitled
under any Bylaw, agreement, vote of stockholders or disinterested directors or
otherwise, both as to action in his official capacity and as to action in
another capacity while holding such office, and shall continue as to a person
who has ceased to be a director, officer, employee, or agent and shall inure to
the benefit of the heirs, executors, and administrators of such a person.  Any
person seeking indemnification under this Article NINTH shall be deemed to have
met the standard of conduct required for such indemnification unless the
contrary shall be established by a court of competent jurisdiction.  Any repeal
or modification of the foregoing provisions of this Article NINTH shall not
adversely affect any


                                       -4-
<PAGE>


right or protection of a director or officer of the Corporation with respect to
any acts or omissions of such director or officer occurring prior to such repeal
or modification.

          TENTH:  From time to time any of the provisions of this Certificate of
Incorporation may be amended, altered, or repealed, and the provisions
authorized by the laws of the State of Delaware at the time in force may be
added or inserted in the manner and at the time prescribed by said laws, and all
rights at any time conferred upon the stockholders of the Corporation by this
Certificate of Incorporation are granted subject to the provisions of this
Article TENTH.

          ELEVENTH:  The Corporation hereby elects to be governed by Section 203
of the Delaware General Corporation Law.

          TWELFTH:  If at any time the Corporation shall have a class of stock
registered pursuant to the provisions of the Securities Exchange Act of 1934,
for so long as such class is so registered, any action by the stockholders of
such class must be taken at an annual or special meeting of stockholders and may
not be taken by written consent.

          THIRTEENTH:  The Board of Directors of the Corporation, when
evaluating any offer of another party (a) to make a tender or exchange offer for
any equity security of the Corporation or (b) to effect a business combination,
shall, in connection with the exercise of its judgment in determining what is in
the best interests of the Corporation as a whole, be authorized to give due
consideration to any such factors as the Board of Directors determines to be
relevant, including, without limitation:

               a.   the interests of the Corporation's stockholders;

               b.   whether the proposed transaction might violate federal or
                    state laws;

               c.   not only the consideration being offered in the proposed
                    transaction, in relation to the then current market price
                    for the outstanding capital stock of this Corporation, but
                    also to the market price for the capital stock of the
                    Corporation over a period of years, the estimated price that
                    might be achieved in a negotiated sale of the Corporation as
                    a whole or in part or through orderly liquidation, the
                    premiums over market price for the securities of other
                    corporations in similar transactions, current political,
                    economic and other factors bearing on securities prices and
                    the Corporation's financial condition and future prospects;
                    and

               d.   the social, legal and economic effects upon employees,
                    suppliers, customers and others having similar relationships
                    with the Corporation, and the communities in which the
                    Corporation conducts its business.


                                       -5-
<PAGE>


In connection with any such evaluation, the Board of Directors is authorized to
conduct such investigations and engage in such legal proceedings as the Board of
Directors may determine.

          FOURTEENTH:  Notwithstanding any other provisions of this Certificate
of Incorporation or the Bylaws (and notwithstanding the fact that a lesser
percentage may be specified by law, this Certificate of Incorporation or the
Bylaws of this Corporation), the affirmative vote of 75% of the total number of
votes of the then outstanding shares of capital stock of the Corporation
entitled to vote generally in the election of directors, voting together as a
single class, shall be required to amend or repeal, or to adopt any provision
inconsistent with the purpose or intent of ARTICLES SEVENTH, EIGHTH, NINTH,
TENTH, ELEVENTH, TWELFTH, THIRTEENTH and this ARTICLE FOURTEENTH.  Notice of any
such proposed amendment, repeal or adoption, shall be contained in the notice of
the meeting at which it is to be considered.  Subject to the provisions set
forth herein, this Corporation reserves the right to amend, alter, repeal or
rescind any provision contained in this Certificate of Incorporation in the
manner now or hereafter prescribed by law.

          4.   This Amended and Restated Certificate of Incorporation was
duly adopted in accordance with Sections 228, 242 and 245 of the General
Corporation Law of the State of Delaware and written notice of the adoption of
this Amended and Restated Certificate of Incorporation has been given
pursuant to Section 228 of the General Corporation Law of the State of Delaware
to each and every stockholder entitled to such notice.

          IN WITNESS WHEREOF, the Corporation has caused this Amended and
Restated Certificate of Incorporation to be signed and attested to by its duly
authorized officers on this ___ day of __________, 1996.


                                   ADVANCED RADIO TECHNOLOGIES
                                   CORPORATION


                                   By:
                                      -----------------------------


ATTEST:


By:
   ---------------------------------
   Secretary


                                     -6-
<PAGE>

                                                                  

                              RESTATED AND AMENDED

                                     BYLAWS

                                       OF

                     Advanced Radio Technologies Corporation

                            (a Delaware corporation)

                            Effective ______ __, 1996
                            -------------------------

                                    ARTICLE I

                                  STOCKHOLDERS

     1.  CERTIFICATES REPRESENTING STOCK. Certificates representing stock in the
Corporation shall be signed by, or in the name of, the Corporation by the
Chairman or Vice-Chairman of the Board of Directors, if any, or by the President
or a Vice President and by the Treasurer or an Assistant Treasurer or the
Secretary or an Assistant Secretary of the Corporation. Any or all the
signatures on any such certificate may be a facsimile. In case any officer,
transfer agent, or registrar who has signed or whose facsimile signature has
been placed upon a certificate shall have ceased to be such officer, transfer
agent, or registrar before such certificate is issued, it may be issued by the
Corporation with the same effect as if he were such officer, transfer agent or
registrar at the date of issue.

     Whenever the Corporation shall be authorized to issue more than one class
of stock or more than one series of any class of stock, and whenever the
Corporation shall issue any shares of its stock as partly paid stock, the
certificates representing shares of any such class or series or of any such
partly paid stock shall set forth thereon the statements prescribed by the
General Corporation Law. Any restrictions on the transfer or registration of
transfer of any shares of stock of any class or series shall be noted
conspicuously on the certificate representing such shares.

     The Corporation may issue a new certificate of stock or uncertificated
shares in place of any certificate theretofore issued by it, alleged to have
been lost, stolen, or destroyed, and the Board of Directors may require the
owner of the lost, stolen, or destroyed certificate, or his legal
representative, to give the Corporation a bond sufficient to indemnify the
Corporation against any claim that may be made against it on account of the
alleged loss, theft, or destruction of any such certificate or the issuance of
any such new certificate or uncertificated shares.

     2. UNCERTIFICATED SHARES.  Subject to any conditions imposed by the General
Corporation Law, the Board of Directors of the Corporation may provide by
resolution or resolutions that some or all of any or all classes or series of
the stock of the Corporation shall be uncertificated shares. Within a reasonable
time after the issuance or transfer of any uncertificated shares, the
Corporation shall send to the registered owner thereof any written notice
prescribed by the General Corporation Law.

<PAGE>

     3.  FRACTIONAL SHARE INTERESTS.  The Corporation may, but shall not be
required to, issue fractions of a share. If the Corporation does not issue
fractions of a share, it shall (1) arrange for the disposition of fractional
interests by those entitled thereto, (2) pay in cash fair value of fractions of
a share as of the time when those entitled to receive such fractions are
determined, or (3) issue scrip or warrants in registered form (either
represented by a certificate or uncertificated) or bearer form (represented by a
certificate) which shall entitle the holder to receive a full share upon the
surrender of such scrip or warrants aggregating a full share. A certificate for
a fractional share or an uncertificated fractional share shall, but scrip or
warrants shall not unless otherwise provided therein, entitle the holder to
exercise voting rights, to receive dividends thereon, and to participate in any
of the assets of the Corporation in the event of liquidation. The Board of
Directors may cause scrip or warrants to be issued subject to the conditions
that they shall become void if not exchanged for certificates representing the
full shares or uncertificated full shares before a specified date, or subject to
the conditions that the shares for which scrip or warrants are exchangeable may
be sold by the Corporation and the proceeds thereof distributed to the holders
of scrip or warrants, or subject to any other conditions which the Board of
Directors may impose.

     4.  STOCK TRANSFERS.

          (a)  Upon compliance with provisions restricting the transfer or
registration of transfer of shares of stock, if any, transfers or registration
of transfers of shares of stock of the Corporation shall be made only on the
stock ledger of the Corporation by the registered holder thereof, or by his
attorney thereunto authorized by power of attorney duly executed and filed with
the Secretary of the Corporation or with a transfer agent or a registrar, if
any, and, in the case of shares represented by certificates, on surrender of the
certificate or certificates for such shares of stock properly endorsed and the
payment of all taxes due thereon.

          (b)  No shares of stock of any class or series outstanding at any time
shall be owned of record or beneficially by a person whose ownership thereof
would constitute a violation of Section 310 of the Communications Act of 1934,
as amended, or any similar or successor federal statutes.

          (c)  The Corporation may, in its sole discretion, redeem any
outstanding shares of stock of any class or series which are owned in violation
of Section 4.1(b) above.  Shares redeemed by the Corporation under this
subparagraph (c) may be redeemed for cash, property or rights, including
securities of the Corporation or another corporation, at their fair market value
at the time of the redemption.  The Board of Directors of the Corporation shall
have sole discretion to determine whether shares are owned in violation of
Section 4.1(b) hereof, the fair market value of any shares to be redeemed, and
the value of any non-cash consideration to be provided for such shares in any
such redemption.

          (d)  The Corporation will furnish to any stockholder, upon request and
without charge, copies of the certificate of incorporation, by-laws, and any
applicable resolutions of the Board of Directors of the Corporation adopted for
the purpose of ensuring the control of the Corporation remains with loyal
citizens of the United States as required by the Communications Act of 1934, as
amended.


                                     -2-

<PAGE>

     5.  RECORD DATE FOR STOCKHOLDERS.  In order that the Corporation may
determine the stockholders entitled to notice of or to vote at any meeting of
stockholders or any adjournment thereof, the Board of Directors may fix a record
date, which record date shall not precede the date upon which the resolution
fixing the record date is adopted by the Board of Directors, and which record
date shall not be more than sixty nor less than ten days before the date of such
meeting. If no record date is fixed by the Board of Directors, the record date
for determining stockholders entitled to notice of or to vote at a meeting of
stockholders shall be at the close of business on the day next preceding the day
on which notice is given, or, if notice is waived, at the close of business on
the day next preceding the day on which the meeting is held. A determination of
stockholders of record entitled to notice of or to vote at a meeting of
stockholders shall apply to any adjournment of the meeting; provided, however,
that the Board of Directors may fix a new record date for the adjourned meeting.
In order that the Corporation may determine the stockholders entitled to consent
to corporate action in writing without a meeting, the Board of Directors may fix
a record date, which record date shall not precede the date upon which the
resolution fixing the record date is adopted by the Board of Directors, and
which date shall not be more than ten days after the date upon which the
resolution fixing the record date is adopted by the Board of Directors. If no
record date has been fixed by the Board of Directors, the record date for
determining the stockholders entitled to consent to corporate action in writing
without a meeting, when no prior action by the Board of Directors is required by
the General Corporation Law, shall be the first date on which a signed written
consent setting forth the action taken or proposed to be taken is delivered to
the Corporation by delivery to its registered office in the State of Delaware,
its principal place of business, or an officer or agent of the Corporation
having custody of the book in which proceedings of meetings of stockholders are
recorded. Delivery made to the Corporation's registered office shall be by hand
or by certified or registered mail, return receipt requested. If no record date
has been fixed by the Board of Directors and prior action by the Board of
Directors is required by the General Corporation Law, the record date for
determining stockholders entitled to consent to corporate action in writing
without a meeting shall be at the close of business on the day on which the
Board of Directors adopts the resolution taking such prior action. In order that
the Corporation may determine the stockholders entitled to receive payment of
any dividend or other distribution or allotment of any rights or the
stockholders entitled to exercise any rights in respect of any change,
conversion, or exchange of stock, or for the purpose of any other lawful action,
the Board of Directors may fix a record date, which record date shall not
precede the date upon which the resolution fixing the record date is adopted,
and which record date shall be not more than sixty days prior to such action. If
no record date is fixed, the record date for determining stockholders for any
such purpose shall be at the close of business on the day on which the Board of
Directors adopts the resolution relating thereto.

     6.  MEANING OF CERTAIN TERMS. As used herein in respect of the right to
notice of a meeting of stockholders or a waiver thereof or to participate or
vote thereat or to consent or dissent in writing in lieu of a meeting, as the
case may be, the term "share" or "shares" or "share of stock" or "shares of
stock" or "stockholder" or "stockholders" refers to an outstanding share or
shares of stock and to a holder or holders of record of outstanding shares of
stock when the Corporation is authorized to issue only one class of shares of
stock, and said reference is also intended to include any outstanding share or
shares of stock and any holder or holders of record of outstanding shares of
stock of any class upon which or upon whom the certificate of


                                       -3-

<PAGE>

incorporation confers such rights where there are two or more classes or series
of shares of stock or upon which or upon whom the General Corporation Law
confers such rights notwithstanding that the certificate of incorporation may
provide for more than one class or series of shares of stock, one or more of
which are limited or denied such rights thereunder, provided, however, that no
such right shall vest in the event of an increase or a decrease in the
authorized number of shares of stock of any class or series which is otherwise
denied voting rights under the provisions of the certificate of incorporation,
except as any provision of law may otherwise require.

     7.  STOCKHOLDER MEETINGS.

     - TIME.  The annual meeting shall be held on the date and at the time
fixed, from time to time, by the directors.  A special meeting shall be held on
the date and at the time fixed by the directors.

     - PLACE. Annual meetings and special meetings shall be held at such place,
within or without the State of Delaware, as the directors may, from time to
time, fix. Whenever the directors shall fail to fix such place, the meeting
shall be held at the registered office of the Corporation in the State of
Delaware.

     - CALL. Annual meetings and special meetings may be called by a majority of
the directors or by any officer instructed by a majority of the directors to
call the meeting.

     - NOTICE OR WAIVER OF NOTICE. Written notice of all meetings shall be
given, stating the place, date, and hour of the meeting and stating the place
within the city or other municipality or community at which the list of
stockholders of the Corporation may be examined. The notice of an annual meeting
shall state that the meeting is called for the election of directors and for the
transaction of other business which may properly come before the meeting, and
shall (if any other action which could be taken at a special meeting is to be
taken at such annual meeting) state the purpose or purposes. The notice of a
special meeting shall in all instances state the purpose or purposes for which
the meeting is called. The notice of any meeting shall also include, or be
accompanied by, any additional statements, information, or documents prescribed
by the General Corporation Law. Except as otherwise provided by the General
Corporation Law, a copy of the notice of any meeting shall be given, personally
or by mail, not less than ten days nor more than sixty days before the date of
the meeting, unless the lapse of the prescribed period of time shall have been
waived, and directed to each stockholder at his record address or at such other
address which he may have furnished by request in writing to the Secretary of
the Corporation. Notice by mail shall be deemed to be given when deposited, with
postage thereon prepaid, in the United States Mail. No business shall be
conducted at an annual meeting except in accordance with this procedure.  The
Chairman of an annual meeting shall, if the facts warrant, determine and declare
to the meeting that business was not properly brought before the meeting and in
accordance with the provisions of this section, and if so determined, shall
declare to the meeting that any such business not properly bought before the
meeting shall not be transacted.  If a meeting is adjourned to another time, not
more than thirty days hence, and/or to another place, and if an announcement of
the adjourned time and/or place is made at the meeting, it shall not be
necessary to give notice of the adjourned meeting unless


                                       -4-

<PAGE>

the directors, after adjournment, fix a new record date for the adjourned
meeting. Notice need not be given to any stockholder who submits a written
waiver of notice signed by him before or after the time stated therein.
Attendance of a stockholder at a meeting of stockholders shall constitute a
waiver of notice of such meeting, except when the stockholder attends the
meeting for the express purpose of objecting, at the beginning of the meeting,
to the transaction of any business because the meeting is not lawfully called or
convened. Neither the business to be transacted at, nor the purpose of, any
regular or special meeting of the stockholders need be specified in any written
waiver of notice.

     - STOCKHOLDER LIST.  The officer who has charge of the stock ledger of the
Corporation shall prepare and make, at least ten days before every meeting of
stockholders, a complete list of the stockholders, arranged in alphabetical
order, and showing the address of each stockholder and the number of shares
registered in the name of each stockholder. Such list shall be open to the
examination of any stockholder, for any purpose germane to the meeting, during
ordinary business hours, for a period of at least ten days prior to the meeting,
either at a place within the city or other municipality or community where the
meeting is to be held, which place shall be specified in the notice of the
meeting, or if not so specified, at the place where the meeting is to be held.
The list shall also be produced and kept at the time and place of the meeting
during the whole time thereof, and may be inspected by any stockholder who is
present. The stock ledger shall be the only evidence as to who are the
stockholders entitled to examine the stock ledger, the list required by this
section or the books of the Corporation, or to vote at any meeting of
stockholders.

     - CONDUCT OF MEETING.  Meetings of the stockholders shall be presided over
by one of the following officers in the order of seniority and if present and
acting - the Chairman of the Board, if any, the Vice-Chairman of the Board, if
any, the President, a Vice-President, or, if none of the foregoing is in office
and present and acting, by a chairman to be chosen by the stockholders. The
Secretary of the Corporation, or in his absence, an Assistant Secretary, shall
act as secretary of every meeting, bur if neither the Secretary nor an Assistant
Secretary is present the Chairman of the meeting shall appoint a secretary of
the meeting.

     - PROXY REPRESENTATION.  Every stockholder may authorize another person or
persons to act for him by proxy in all matters in which a stockholder is
entitled to participate, whether by waiving notice of any meeting, voting or
participating at a meeting, or expressing consent or dissent without a meeting.
Every proxy must be signed by the stockholder or by his attorney-in-fact. No
proxy shall be voted or acted upon after three years from its date unless such
proxy provides for a longer period. A duly executed proxy shall be irrevocable
if it states that it is irrevocable and, if, and only as long as, it is coupled
with an interest sufficient in law to support an irrevocable power. A proxy may
be made irrevocable regardless of whether the interest with which it is coupled
is an interest in the stock itself or an interest in the Corporation generally.

     - INSPECTORS. The directors, in advance of any meeting, may, but need not,
appoint one or more inspectors of election to act at the meeting or any
adjournment thereof. If an inspector or inspectors are not appointed, the person
presiding at the meeting may, but need not, appoint one or more inspectors. In
case any person who may be appointed as an inspector fails


                                       -5-

<PAGE>

to appear or act, the vacancy may be filled by appointment made by the directors
in advance of the meeting or at the meeting by the person presiding thereat.
Each inspector, if any, before entering upon the discharge of his duties, shall
take and sign an oath faithfully to execute the duties of inspectors at such
meeting with strict impartiality and according to the best of his ability. The
inspectors, if any, shall determine the number of shares of stock outstanding
and the voting power of each, the shares of stock represented at the meeting,
the existence of a quorum, the validity and effect of proxies, and shall receive
votes, ballots, or consents, hear and determine all challenges and questions
arising in connection with the right to vote, count and tabulate all votes,
ballots, or consents, determine the result, and do such acts as are proper to
conduct the election or vote with fairness to all stockholders. On request of
the person presiding at the meeting, the inspector or inspectors, if any, shall
make a report in writing of any challenge, question, or matter determined by him
or them and execute a certificate of any fact found by him or them. Except as
otherwise required by subsection (e) of Section 231 of the General Corporation
Law, the provisions of that Section shall not apply to the Corporation.

     - QUORUM. The holders of a majority of the outstanding shares of stock
shall constitute a quorum at a meeting of stockholders for the transaction of
any business. The stockholders present may adjourn the meeting despite the
absence of a quorum.

     - VOTING. Each share of stock shall entitle the holder thereof to one vote.
Directors shall be elected by a plurality of the votes of the shares present in
person or represented by proxy at the meeting and entitled to vote on the
election of directors. Any other action shall be authorized by a majority of the
votes cast except where the General Corporation Law prescribes a different
percentage of votes and/or a different exercise of voting power, and except as
may be otherwise prescribed by the provisions of the certificate of
incorporation and these Bylaws. In the election of directors, and for any other
action, voting need not be by ballot.

     8.  STOCKHOLDER ACTION WITHOUT MEETINGS.  Any action required by the
General Corporation Law to be taken at any annual or special meeting of
stockholders, or any action which may be taken at any annual or special meeting
of stockholders, may be taken without a meeting, without prior notice and
without a vote, if a consent in writing, setting forth the action so taken,
shall be signed by the holders of outstanding stock having not less than the
minimum number of votes that would be necessary to authorize or take such action
at a meeting at which all shares entitled to vote thereon were present and
voted; provided that if at any time the Corporation shall have a class of stock
registered pursuant to the provisions of the Securities Exchange Act of 1934,
for so long as such class is so registered, any action by the stockholders of
such class must be taken at an annual or special meeting of stockholders and may
not be taken by written consent.  Prompt notice of the taking of the corporate
action without a meeting by less than unanimous written consent shall be given
to those stockholders who have not consented in writing. Action taken pursuant
to this paragraph shall be subject to the provisions of Section 228 of the
General Corporation Law.


                                   ARTICLE II

                                    DIRECTORS


                                       -6-

<PAGE>


     1.   FUNCTIONS AND DEFINITION.  The business and affairs of the Corporation
shall be managed by or under the direction of the Board of Directors of the
Corporation. The Board of Directors shall have the authority to fix the
compensation of the members thereof. The use of the phrase "whole board" herein
refers to the total number of directors which the Corporation would have if
there were no vacancies.

     2.   QUALIFICATIONS AND NUMBER.  A director need not be a stockholder, a
citizen of the United States, or a resident of the State of Delaware. The
initial Board of Directors shall consist of seven persons. Thereafter the number
of directors constituting the whole board shall be at least five. Subject to the
foregoing limitation and except for the first Board of Directors, the number of
directors shall be fixed by resolution of the Board of Directors and may be
increased at any time or from time to time by the directors by vote of a
majority of the directors then in office but not to a greater number than nine
without action by the stockholders.  The number of directors may be decreased to
any number permitted by the foregoing at any time by the directors by vote of a
majority of the directors then in office, but only to eliminate vacancies
existing by reason of the death, resignation or removal of one or more
directors.

     3.   ELECTION AND TERM.  All members of the Board of Directors shall be
classified, with respect to the time for which they each hold office, into three
classes.  One class shall originally be elected for an initial one year term
expiring at the annual meeting of stockholders to be held in 1997, another class
shall be originally elected for an initial two year term expiring at the annual
meeting of stockholders to be held in 1998, and another class shall be
originally elected for an initial three year term expiring at the annual meeting
of stockholders to be held in 1999, with each member of each class to hold
office until a successor is elected and qualified or until his earlier
resignation or removal.  Thereafter, at each annual meeting of stockholders, the
successors of the class of directors whose term expires at that meeting shall be
elected to hold office for a three year term until their successors are elected
and qualified or until their earlier resignation or removal.

     Except as otherwise provided in or fixed by or pursuant to the
Corporation's Certificate of Incorporation, nominations for the election of
directors may be made by the Board of Directors or by any stockholder of record
entitled to vote in the election of directors generally.  However, any such
stockholders may nominate one or more persons for election as director or
directors at a stockholders' meeting only if written notice of intent to make
such nomination or nominations has been given either by personal delivery or by
mail to the Secretary of the Corporation not less than 30 days before the
meeting of stockholders at which such election is held.  Each such notice shall
state (a) the name and address of the stockholder who intends to make the
nomination and of the person or persons to be nominated; (b) a representation
that the stockholder is a holder of record of stock of the Corporation entitled
to vote at such meeting and intends to appear in person or by proxy at the
meeting to nominate the person or persons specified in the notice; (c) a
description of all arrangements or understandings between the stockholder and
each nominee and any other person or persons (naming such person or persons)
pursuant to which the nomination or nominations are to be made by the nominee
proposed by such stockholder as would be required to be included in a proxy
statement filed pursuant to the proxy rules of the Securities and Exchange
Commission, had the nominee been nominated, or


                                       -7-

<PAGE>

intended to be nominated, by the Board of Directors; and (d) the consent of each
nominee to serve as a director of the Corporation if so elected, and shall be
accompanied by a petition in support of such nomination signed by at least 50
holders of record of stock entitled to vote in the election of directors holding
in the aggregate not less than 5% of such stock.  The chairman of the meeting
may refuse to acknowledge the nomination of any person not made in compliance
with the foregoing procedure.

     4.   MEETINGS.

     - TIME.  Meetings shall be held at such time as the Board shall fix, except
that the first meeting of a newly elected Board shall be held as soon after its
election as the directors may conveniently assemble.

     - PLACE.  Meetings shall be held at such place within or without the State
of Delaware as shall be fixed by the Board.

     - CALL.  No call shall be required for regular meetings for which the time
and place have been fixed. Special meetings may be called: by or at the
direction of the Chairman of the Board, if any, the Vice-Chairman of the Board,
if any, or the President, or of a majority of the directors in office.


     - NOTICE OR ACTUAL OR CONSTRUCTIVE WAIVER.  No notice shall be required for
regular meetings for which the time and place have been fixed. Written, oral, or
any other mode of notice of the time and place shall be given for special
meetings in sufficient time for the convenient assembly of the directors
thereat. Notice need not be given to any director or to any member of a
committee of directors who submits a written waiver of notice signed by him
before or after the time stated therein. Attendance of any such person at a
meeting shall constitute a waiver of notice of such meeting, except when he
attends a meeting for the express purpose of objecting, at the beginning of the
meeting, to the transaction of any business because the meeting is not lawfully
called or convened. Neither the business to be transacted at, nor the purpose
of, any regular or special meeting of the directors need be specified in any
written waiver of notice.

     - QUORUM AND ACTION.  A majority of the whole Board shall constitute a
quorum except when a vacancy or vacancies prevents such majority, whereupon a
majority of the directors in office shall constitute a quorum, provided, that
such majority shall constitute at least one-third of the whole Board. A majority
of the directors present, whether or not a quorum is present, may adjourn a
meeting to another time and place. Except as herein otherwise provided, and
except as otherwise provided by the General Corporation Law, the vote of the
majority of the directors present at a meeting at which a quorum is present
shall be the act of the Board. The quorum and voting provisions herein stated
shall not be construed as conflicting with any provisions of the General
Corporation Law and these Bylaws which govern a meeting of directors held to
fill vacancies and newly created directorships in the Board or action of
disinterested directors.


                                       -8-

<PAGE>

     Any member or members of the Board of Directors or of any committee
designated by the Board, may participate in a meeting of the Board, or any such
committee, as the case may be, by means of conference telephone or similar
communications equipment by means of which all persons participating in the
meeting can hear each other.

     - CHAIRMAN OF THE MEETING.  The Chairman of the Board, if any and if
present and acting, shall preside at all meetings. Otherwise, the Vice-Chairman
of the Board, if any and if present and acting, or the President, if present and
acting, or any other director chosen by the Board, shall preside.

     5.   RESIGNATION AND REMOVAL OF DIRECTORS.  Any director may resign at any
time by delivering his resignation in writing to the chairman of the board, if
any, the president, or the secretary or to a meeting of the board of directors.
Such resignation shall be effective upon receipt unless specified to be
effective at some other time, and without in either case the necessity of it
being accepted unless the resignation shall so state.  Except as otherwise
provided in the certificate of incorporation or these by-laws relating to the
rights of the holders of any class or series of preferred stock, voting
separately by class or series, to elect directors under specified circumstances,
any director or directors may be removed from office at any time, but only for
cause and only by the affirmative vote, at any regular meeting or special
meeting of the stockholders, of not less than 50% of the total number of votes
of the then outstanding shares of capital stock of the corporation entitled to
vote generally in the election of directors, voting together as a single class,
but only if notice of such proposal was contained in the notice of such meeting.
Any vacancy in the board of directors resulting from any such removal shall be
filled only by vote of a majority of the directors then in office, although less
than a quorum, and any director or directors so chosen shall hold office until
the next election of the class for which such directors shall have been chosen
and until their successors shall be elected and qualified or until their earlier
death, resignation or removal. No director resigning and (except where a right
to receive compensation shall be expressly provided in a duly authorized written
agreement with the corporation) no director removed shall have any right to any
compensation as such director for any period following his resignation or
removal, or any right to damages on account of such removal, whether his
compensation be by the month or by the year or otherwise; unless, in the case of
a resignation, the directors, or, in the case of removal, the body acting on the
removal, shall in their or its discretion provide for compensation.

     6.   VACANCIES. Vacancies and any newly created directorships resulting
from any increase in the number of directors shall be filled only by vote of a
majority of the directors then in office, although less than a quorum, or by a
sole remaining director.  Stockholders shall have no power to fill any vacancies
or newly created directorships.  When one or more directors shall resign from
the board, effective at a future date, a majority of the directors then in
office, including those who have resigned, shall have power to fill such vacancy
or vacancies, the vote or action by writing thereon to take effect when such
resignation or resignations shall become effective.  The directors shall have
and may exercise all their powers notwithstanding the existence of one or more
vacancies in their number, subject to any requirement of law or of the
certificate of incorporation or of these by-laws as to the number of directors
required for a quorum or for any vote or other actions.


                                       -9-

<PAGE>

     7.  COMMITTEES.  The Board of Directors may, by resolution passed by a
majority of the whole Board, designate one or more committees, each committee to
consist of one or more of the directors of the Corporation. The Board may
designate one or more directors as alternate members of any committee, who may
replace any absent or disqualified member at any meeting of the committee.  Any
such committee, to the extent provided in the resolution of the Board, shall
have and may exercise the powers and authority of the Board of Directors in the
management of the business and affairs of the Corporation with the exception of
any authority the delegation of which is prohibited by Section 141 of the
General Corporation Law, and may authorize the seal of the Corporation to be
affixed to all papers which may require it.

     8.   WRITTEN ACTION.  Any action required or permitted to be taken at any
meeting of the Board of Directors or any committee thereof may be taken without
a meeting if all members of the Board or committee, as the case may be, consent
thereto in writing, and the writing or writings are filed with the minutes of
proceedings of the Board or committee.

     9.   INTERESTED DIRECTORS AND OFFICERS.

          (a)  No contract or transaction between the Corporation and one or
more of its directors or officers, or between the Corporation and any other
corporation, partnership, association, or other organization in which one or
more of the Corporation's directors or officers are directors or officers, or
have a financial interest, shall be void or voidable solely for this reason, or
solely because the director or officer is present at or participates in the
meeting of the board or committee thereof which authorizes the contract or
transaction, or solely because his or their votes are counted for such purpose,
if:

                    (1)  The material facts as to his relationship or interest
          and as to the contract or transaction are disclosed or are known to
          the board of directors or the committee, and the board or committee in
          good faith authorizes the contract or transaction by the affirmative
          votes of a majority of the disinterested directors, even though the
          disinterested directors be less than a quorum; or

                    (2)  The material facts as to his relationship or interest
          and as to the contract or transaction are disclosed or are known to
          the stockholders entitled to vote thereon, and the contract or
          transaction is specifically approved in good faith by vote of the
          stockholders; or

                    (3)  The contract or transaction is fair as to the
          corporation as of the time it is authorized, approved or ratified, by
          the Board of Directors, a committee thereof, or the stockholders.

          (b)  Common or interested directors may be counted in determining the
presence of a quorum at a meeting of the Board of Directors or of a committee
which authorizes the contract or transaction.


                                   ARTICLE III


                                      -10-

<PAGE>

                                    OFFICERS

     The officers of the Corporation shall consist of a President, a Secretary,
a Treasurer, and, if deemed necessary, expedient, or desirable by the Board of
Directors, a Chairman of the Board, a Vice-Chairman of the Board, one or more
Executive Vice Presidents, one or more other Vice-Presidents, one or more
Assistant Secretaries, one or more Assistant Treasurers, and such other officers
with such titles as the resolution of the Board of Directors choosing them shall
designate. Except as may otherwise be provided in the resolution of the Board of
Directors choosing him, no officer other than the Chairman or Vice-Chairman of
the Board, if any, need be a director. Any number of offices may be held by the
same person, as the directors may determine.

     Unless otherwise provided in the resolution choosing him, each officer
shall be chosen for a term which shall continue until the meeting of the Board
of Directors following the next annual meeting of stockholders and until his
successor shall have been chosen and qualified.

     All officers of the Corporation shall have such authority and perform such
duties in the management and operation of the Corporation as shall be prescribed
in the resolutions of the Board of Directors designating and choosing such
officers and prescribing their authority and duties, and shall have such
additional authority and duties as are incident to their office except to the
extent that such resolutions may be inconsistent therewith. The Secretary or an
Assistant Secretary of the Corporation shall record all of the proceedings of
all meetings and actions in writing of stockholders, directors, and committees
of directors, and shall exercise such additional authority and perform such
additional duties as the Board shall assign to him. Any officer may be removed,
with or without cause, by the Board of Directors. Any vacancy in any office may
be filled by the Board of Directors.



                                   ARTICLE IV

                                 CORPORATE SEAL

     The corporate seal shall be in such form as the Board of Directors shall
prescribe.


                                    ARTICLE V

                                   FISCAL YEAR

     The fiscal year of the Corporation shall be fixed, and shall be subject to
change, by the Board of Directors.


                                   ARTICLE VI


                                      -11-

<PAGE>

                               CONTROL OVER BYLAWS

     Subject to the provisions of the certificate of incorporation and the
provisions of the General Corporation Law, the power to amend, alter, or repeal
these Bylaws and to adopt new Bylaws may be exercised by the Board of Directors
or by the stockholders except that the power to amend, alter or repeal Article
II Sections 2 and 3 may be exercised only by the stockholders acting by at least
75% vote of the outstanding voting shares.


                                     -12-

<PAGE>

                                LOCK UP AGREEMENT



Montgomery Securities
Deutsche Morgan Grenfell/C. J. Lawrence Inc.
c/o Montgomery Securities
600 Montgomery Street
San Francisco, California 94111


Re:  Advanced Radio Technologies Corporation (name to be changed to Advanced
     Radio Telecom Corp. (the "Company")

Ladies & Gentlemen:

The undersigned is an owner of record or beneficially of certain shares of
Common Stock of the Company ("Common Stock") or securities convertible into or
exchangeable or exercisable for Common Stock.  The Company proposes to carry out
a public offering of Common Stock (the "Common Stock Offering") for which you
will act as the representatives (the "Representatives") of the underwriters.
The undersigned recognizes that the Common Stock Offering will be of benefit to
the undersigned and will benefit the Company by, among other things, raising
additional capital for its operations.  The undersigned acknowledges that you
and the other underwriters are relying on the representations and agreements of
the undersigned contained in this letter in carrying out the Common Stock
Offering and in entering into underwriting arrangements with the Company with
respect to the Common Stock Offering.

In consideration of the foregoing, the undersigned hereby agrees that the
undersigned will not, without the prior written consent of Montgomery Securities
(which consent may be withheld in its sole discretion), directly or indirectly,
sell, offer, contract or grant any option to sell (including without limitation
any short sale), pledge, transfer, establish an open "put equivalent position"
within the meaning of Rule 16a-1(h) under the Securities Exchange Act of 1934,
as amended (the "Exchange Act"), or otherwise dispose of any shares of Common
Stock, options or warrants to acquire shares of Common Stock, or securities
exchangeable or exercisable for or convertible into shares of Common Stock
currently or hereafter owned either or record or beneficially (as defined in
Rule 13d-3 under the Exchange Act) by the undersigned, or publicly announce the
undersigned's intention to do any of the foregoing, for a period commencing on
the date hereof and continuing to a date 180 days after the date of the final
prospectus for the Common Stock Offering.  The undersigned also agrees and
consents to the entry of stop transfer instructions with the Company's transfer
agent and registrar against the transfer of shares of Common Stock or securities
convertible into or exchangeable or exercisable for Common Stock held by the
undersigned except in compliance with the foregoing restrictions.

This agreement is irrevocable and will be binding on the undersigned and the
respective successors, heirs, personal representatives, and assigns of the
undersigned.

Dated: _______________, 1996

___________________________________________
Printed Name of Holder


By:________________________________________
   Signature

<PAGE>


                          CERTIFICATE OF INCORPORATION

                                       OF

                             ART MERGER CORPORATION

                                     * * * *

     FIRST:  The name of the Corporation is ART Merger Corporation.

     SECOND:  The address of its registered office in the State of Delaware is
1013 Centre Road, City of Wilmington, Delaware, 19805, County of New Castle.
The name of the registered agent at such address is Corporation Service Company.

     THIRD:  The purpose of the Corporation is to engage in any lawful act or
activity for which Corporations may be organized under the General Corporation
Law of the State of Delaware.

     FOURTH:  The aggregate number of shares of capital stock which the
Corporation shall be authorized to issue shall be One Thousand (1000) shares
Common Stock at $.001 par value per share (the "Common Stock").  Holders of
capital stock shall have no pre-emptive rights with respect to any authorized
but unissued shares of Common Stock.

     FIFTH:  The name and mailing address of the incorporator is as follows:

               Todd A. Matthias
               Hahn & Hessen LLP
               350 Fifth Avenue
               New York, New York 10118-0075

     SIXTH:    The Board of Directors is expressly authorized to make, alter or
repeal the By-Laws of the Corporation.

     SEVENTH:  Elections of directors need not be by written ballot unless the
By-Laws of the Corporation shall so provide.

     EIGHTH:   The Corporation is to have perpetual existence.

     NINTH:  The books of the Corporation may be kept (subject to any provision
contained in the statutes) outside the State of Delaware at such place or places
as may be designated from time to time by the Board of Directors or in the By-
Laws of the Corporation.

     TENTH:  The personal liability of the directors of the Corporation is
hereby eliminated to the fullest extent permitted by the provisions of paragraph
(7) of subsection (b) of Section 102 of the General Corporation Law of the State
of Delaware, as the same may be amended and supplemented.  No amendment or
repeal of this Article TENTH shall apply to or have any effect on the liability
or alleged liability of any director of this Corporation for or



<PAGE>


with respect to any acts or omissions of such director occurring prior to such
amendment or repeal.

     ELEVENTH:  The Corporation shall, to the fullest extent permitted by the
provisions of Section 145 of the General Corporation Law of the State of
Delaware, as the same may be amended and supplemented, indemnify, and upon
request advance expenses to, any and all persons who is or was a party or is
threatened to be made a party to any threatened, pending or completed action,
suit, proceeding or claim, whether civil, criminal, administrative or
investigative, by reason of the fact that such person is or was or has agreed to
be a director or officer of this Corporation or while a director or officer is
or was serving at the request of this Corporation as a director, officer,
partner, trustee, employee or agent of any corporation, partnership, joint
venture, trust or other enterprise, including service with respect to employee
benefit plans, from and against any and all of the expenses, liabilities, or
other matters referred to in or covered by said section (including without
limitation attorneys fees and expenses); PROVIDED, HOWEVER, that the foregoing
shall not require this Corporation to indemnify or advance expenses to any
person in connection with any action, suit, proceeding, claim or counterclaim
initiated by or on behalf of such person other than solely to enforce rights
under this ARTICLE ELEVENTH.  The indemnification provided for herein shall not
be deemed exclusive of any other rights to which those indemnified may be
entitled under any Bylaw, agreement, vote of stockholders or disinterested
directors or otherwise, both as to action in his official capacity and as to
action in another capacity while holding such office, and shall continue as to a
person who has ceased to be a director, officer, employee, or agent and shall
inure to the benefit of the heirs, executors, and administrators of such a
person.  Any person seeking indemnification under this Article ELEVENTH shall be
deemed to have met the standard of conduct required for such indemnification
unless the contrary shall be established by a court of competent jurisdiction.
Any repeal or modification of the foregoing provisions of this Article ELEVENTH
shall not adversely affect any right or protection of a director or officer of
the Corporation with respect to any acts or omissions of such director or
officer occurring prior to such repeal or modification.

     IN WITNESS WHEREOF, the undersigned, being the incorporator hereinbefore
named, for the purposes of forming a corporation pursuant to the General
Corporation Law of Delaware, does make this certificate, hereby declaring and
certifying that it is his act and deed and that the facts herein stated are
true, and accordingly has set his hand this ____ day of June, 1996.



                                             _____________________________
                                              Todd A. Matthias

                                -2-





<PAGE>

                          ADVANCED RADIO TELECOM CORP.
                         RESTATED EQUITY INCENTIVE PLAN


1.   PURPOSE

     The purpose of this Restated Equity Incentive Plan (the "Plan") is to
advance the interests of Advanced Radio Telecom Corp. (the "Company") by
enhancing its ability to attract and retain employees and other persons or
entities who are in a position to make significant contributions to the success
of the Company and its subsidiaries through ownership of shares of the Company's
common stock ("Stock").

     The Plan was adopted by the Company on July 22, 1996 under the name "Stock
Option Plan", and adopted by stockholders on February 2, 1996. The Plan was
amended on April 24, April 26 and May 20, 1996.  In order to incorporate the
amendments including broadening of the Plan to include additional equity
incentives, the Plan was restated and amended by the Company on May 30, 1996 and
renamed the "Restated Equity Incentive Plan".

     The Plan is intended to accomplish these goals by enabling the Company to
grant Awards in the form of Options, Stock Appreciation Rights, Restricted Stock
or Unrestricted Stock Awards, Deferred Stock Awards, Performance Awards, Loans
or Supplement Grants, or combinations thereof, all as more fully described
below.

2.   ADMINISTRATION

     Unless otherwise determined by the Board of Directors of the Company (the
"Board"), the Plan will be administered by a Committee of the Board designated
for such purpose (the "Committee").  The Committee shall consist of at least two
directors.  A majority of the members of the Committee shall constitute a
quorum, and all determinations of the Committee shall be made by a majority of
its members.  Any determination of the Committee under the Plan may be made
without notice or meeting of the Committee by a writing signed by a majority of
the Committee members.  During such times as the Stock is registered under the
Securities Exchange Act of 1934 (the "1934 Act"), all members of the Committee
shall be disinterested persons within the meaning of Rule 16b-3 under the 1934
Act and "outside directors" within the meaning of Section 162(m)(4)(C)(i) of the
Internal Revenue Code of 1986, as amended (the "Code").

     The Committee will have authority, not inconsistent with the express
provisions of the Plan and in addition to other authority granted under the
Plan, to (a) grant Awards at such time or times as it may choose; (b) determine
the size of each Award, including the number of shares of Stock subject to the
Award; (c) determine the type or types of each Award; (d) determine the terms
and conditions of each Award; (e) waive compliance by a holder of an Award with
any obligations to be performed by such holder under an Award and waive any
terms or conditions of an Award; (f) amend or cancel an existing Award in whole
or in part (and if an award is canceled, grant another Award in its place on
such terms and conditions as the Committee shall specify), except that the
Committee may not, without the consent of the holder of an Award, take any
action under this clause with

<PAGE>

respect to such Award if such action would adversely affect the rights of such
holder; (g) prescribe the form or forms of instruments that are required or
deemed appropriate under the Plan, including any written notices and elections
required of Participants (as defined below), and change such forms from time to
time; (h) adopt, amend and rescind rules and regulations for the administration
of the Plan; and (i) interpret the Plan and decide any questions and settle all
controversies and disputes that may arise in connection with the Plan.  Such
determinations and actions of the Committee, and all other determinations and
actions of the Committee made or taken under authority granted by any provision
of the Plan, will be conclusive and will bind all parties.  Nothing in this
paragraph shall be construed as limiting the power of the Committee to make
adjustments under Section 7.3 or Section 8.6.

     With respect to persons subject to Section 16 of the 1934 Act, transactions
under the Plan are intended to comply with all applicable conditions of Rule
16b-3 or its successors under the 1934 Act.

3.   EFFECTIVE DATE AND TERM OF PLAN

     The Plan will become effective on the date on which it is approved by the
stockholders of the Company.  No Award may be granted under the Plan ten years
following the date of stockholder approval, but Awards previously granted may
extend beyond that date.

4.   SHARES SUBJECT TO THE PLAN

     Subject to the adjustment as provided in Section 8.6 below, the aggregate
number of shares of Stock that may be delivered under the Plan will be
2,500,000.  If any Award requiring exercise by the Participant for delivery of
Stock terminates without having been exercised in full, or if any Award payable
in Stock or cash is satisfied in cash rather than Stock, the number of shares of
Stock as to which such Award was not exercised or for which cash was substituted
will be available for future grants.

     Subject to Section 8.6(a), the maximum number of shares of Stock as to
which Options and Stock Appreciation Rights may be granted to any Participant in
any one calendar year is 800,000, which limitation shall be construed and
applied consistently with the rules under Section 162(m) of the Internal Revenue
Code.

     Stock delivered under the Plan may be either authorized but unissued Stock
or previously issued Stock acquired by the Company and held in treasury.  No
fractional shares of Stock will be delivered under the Plan.

5.   ELIGIBILITY AND PARTICIPATION

     Each person in the employ of the Company or any of its subsidiaries (an
"Employee") and each other person or entity (including without limitation
non-Employee directors of the Company or a subsidiary of the Company) who, in
the opinion of the Committee, is in a position to make a significant
contribution to the success of the Company or its subsidiaries will be eligible
to receive Awards under the Plan (each such Employee,


                                       -2-

<PAGE>


person or entity receiving an Award, a "Participant").  A "subsidiary" for
purposes of the Plan will be a corporation in which the Company owns, directly
or indirectly, stock possessing 50 % or more of the total combined voting power
of all classes of stock.

6.   TYPES OF AWARDS

     6.1. OPTIONS

     (a)  NATURE OF OPTIONS.  An Option is an Award giving the recipient the
right on exercise thereof to purchase Stock.

     Both "incentive stock options," as defined in Section 422 of the Internal
Revenue of 1986, as amended (the "Code") (any Option intended to qualify as an
incentive stock option being hereinafter referred to as an "ISO"), and Options
that are not incentive stock options, may be granted under the Plan.  ISOs shall
be awarded only to Employees.  Any Option not identified at the time of grant as
being either an ISO or a non-incentive stock option shall be a non-incentive
stock option.

     (b)  EXERCISE PRICE.  The exercise price of an Option will be determined by
the Committee subject to the following:

               (1)  The exercise price of an ISO shall not be less than 100%
          (110% in the case of an ISO granted to a ten-percent stockholder) of
          the fair market value of the Stock subject to the Option, determined
          as of the time the Option is granted.  A "ten percent stockholder" is
          any person who at the time of grant owns, directly or indirectly, or
          is deemed to own by reason of the attribution rules of section 424(d)
          of the Code, stock possessing more than 10% of the total combined
          voting power of all classes of stock of the Company or of any of its
          subsidiaries.

               (2)  In no case may the exercise price paid for Stock which is
          part of an original issue of authorized Stock be less than the par
          value per share of the Stock.

               (3)  The Committee may reduce the exercise price of an Option at
          any time after the time of grant, but in the case of an Option
          originally awarded as an ISO, only with the consent of the
          Participant.

     (c)  DURATION OF OPTIONS.  The latest date on which an Option may be
exercised will be the tenth anniversary (fifth anniversary, in the case of an
ISO granted to a ten-percent shareholder) of the day immediately preceding the
date the Option was granted, or such earlier date as may have been specified by
the Committee at the time the Option was granted.

     (d)  EXERCISE OF OPTIONS.  An Option will become exercisable at such time
or times, and on such conditions, as the Committee may specify.  The Committee
may at any


                                       -3-

<PAGE>


time and from time to time accelerate the time at which all or any part of the
Option may be exercised.

     Any exercise of an Option must be in writing, signed by the proper person
and delivered or mailed to the Company, accompanied by (1) any documents
required by the Committee and (2) payment in full in accordance with paragraph
(e) below for the number of shares for which the Option is exercised.

     (e)  PAYMENT FOR STOCK.  Stock purchased on exercise of an Option must be
paid for as follows: (1) in cash or by check (acceptable to the Company in
accordance with guidelines established for this purpose), bank draft or money
order payable to the order of the Company or (2) if so permitted by the
Committee at or after the grant of the Option (with the consent of the optionee
of an ISO if permitted after the grant) or by the instrument evidencing the
Option, (i) through the delivery of shares of Stock which have been outstanding
for at least six months (unless the Committee approves a shorter period) and
which have a fair market value equal to the exercise price, (ii) by delivery of
a promissory note of the person exercising the Option to the Company, payable on
such terms as are specified by the Committee, (iii) by delivery of an
unconditional and irrevocable undertaking by a broker to deliver promptly to the
Company sufficient funds to pay the exercise price, or (iv) by any combination
of the foregoing permissible forms of payment.

     (f)  DISCRETIONARY PAYMENTS.  If (i) the market price of shares of Stock
subject to an Option (other than an Option which is in tandem with a Stock
Appreciation Right as described in Section 6.2 below) exceeds the exercise price
of the Option at the time of its exercise, and (ii) the person exercising the
Option so requests the Committee in writing, the Committee may in its sole
discretion cancel the Option and cause the Company to pay in cash or in shares
of Common Stock (at a price per share equal to the fair market value per share)
to the person exercising the Option an amount equal to the difference between
the fair market value of the Stock which would have been purchased pursuant to
the exercise (determined on the date the Option is canceled) and the aggregate
exercise price which would have been paid.

     6.2. STOCK APPRECIATION RIGHTS.

     (a)  NATURE OF STOCK APPRECIATION RIGHTS.  A Stock Appreciation Right is an
Award entitling the holder on exercise to receive an amount in cash or Stock or
a combination thereof (such form to be determined by the Committee) determined
in whole or in part by reference to appreciation in the fair market value of a
share of Stock on the date of grant as compared to its fair market value on the
date of exercise or any performance standard selected or established by the
Committee.

     (b)  GRANT OF STOCK APPRECIATION RIGHTS.  Stock Appreciation Rights may be
granted in tandem with, or independently of, Options granted under the Plan.  A
Stock Appreciation Right granted in tandem with an Option which is not an ISO
may be granted either at or after the time the Option is granted.  A Stock
Appreciation Right granted in tandem with an ISO may be granted only at the time
the Option is granted.  The Committee may also grant Stock Appreciation Rights
which provide that following a change in control of


                                       -4-

<PAGE>


the Company, as determined by the Committee, the holder of such Right will be
entitled to receive, with respect to each share of Stock subject to the Right,
an amount equal to the excess of a specified value (which may include an average
of values) for a share of Stock during a period preceding such change in control
over the fair market value of a share of Stock on the date the Right was
granted.

     (c)  RULES APPLICABLE TO TANDEM AWARDS.  When Stock Appreciation Rights are
granted in tandem with Options, the following will apply:

               (1)  The Stock Appreciation Right will be exercisable only at
          such time or times, and to the extent, that the related Option is
          exercisable and will be exercisable in accordance with the procedure
          required for exercise of the related Option.

               (2)  The Stock Appreciation Right will terminate and no longer be
          exercisable upon the termination or exercise of the related Option,
          except that a Stock Appreciation Right granted with respect to less
          than the full number of shares covered by an Option will not be
          reduced until the number of shares as to which the related Option has
          been exercised or has terminated exceeds the number of shares not
          covered by the Stock Appreciation Right.

               (3)  The Option will terminate and no longer be exercisable upon
          the exercise of the related Stock Appreciation Right.

               (4)  The Stock Appreciation Right will be transferable only with
          the related Option.

               (5)  A Stock Appreciation Right granted in tandem with an ISO may
          be exercised only when the market price of the Stock subject to the
          Option exceeds the exercise price of such option.

     (d)  EXERCISE OF INDEPENDENT STOCK APPRECIATION RIGHTS.  A Stock
Appreciation Right not granted in tandem with an Option will become exercisable
at such time or times, and on such conditions, as the Committee may specify.
The Committee may at any time accelerate the time at which all or any part of
the Right may be exercised.

     Any exercise of an independent Stock Appreciation Right must be in writing,
signed by the proper person and delivered or mailed to the Company, accompanied
by any other documents required by the Committee.

     6.3. RESTRICTED AND UNRESTRICTED STOCK.

     (a)  GRANT OF RESTRICTED STOCK.  Subject to the terms and provisions of the
Plan, the Committee, at any time and from time to time, may grant shares of
Restricted Stock in such amounts and upon such terms and conditions as the
Committee shall determine subject to the restrictions described below.


                                       -5-
<PAGE>


     (b)  RESTRICTED STOCK AGREEMENT.  The Committee may require, as a condition
to an Award, that a recipient of a Restricted Stock Award enter into a
Restricted Stock Award Agreement, setting forth the terms and conditions of the
Award.  In lieu of a Restricted Stock Award Agreement, the Committee may provide
the terms and conditions of an Award in a notice to the Participant of the
Award, on the Stock certificate representing the Restricted Stock, in the
resolution approving the Award, or in such other manner as it deems appropriate.

     (c)  TRANSFERABILITY AND OTHER RESTRICTIONS.  Except as otherwise provided
in this Section 6.3, the shares of Restricted Stock granted herein may not be
sold, transferred, pledged, assigned, or otherwise alienated or hypothecated
until the end of the applicable period or periods established by the Committee
and the satisfaction of any other conditions or restrictions established by the
Committee (such period during which a share of Restricted Stock is subject to
such restrictions and conditions is referred to as the "Restricted Period").
Except as the Committee may otherwise determine, if a Participant ceases to be
an Employee or otherwise suffers a Status Change (as defined at Section 7.2(a)
below) for any reason during the Restricted Period, the Company may purchase the
shares of Restricted Stock subject to such restrictions and conditions for the
amount of cash paid by the Participant for such shares, or such shares of
Restricted Stock shall be forfeited to the Company if no cash was paid by the
Participant.

     The Company shall also have the right to retain the certificates
representing shares of Restricted Stock in the Company's possession during the
Restricted Period.

     (d)  REMOVAL OF RESTRICTIONS.  Except as otherwise provided in this Section
6.3, a share of Restricted Stock covered by a Restricted Stock grant shall
become freely transferable by the Participant upon completion of the Restricted
Period including the passage of any applicable period of time and satisfaction
of any conditions to vesting.  However, unless otherwise provided by the
Committee, the Committee, in its sole discretion, shall have the right to
immediately waive all or part of the restrictions and conditions with regard to
all or part of the shares held by any Participant at any time.

     (e)  VOTING RIGHTS, DIVIDENDS AND OTHER DISTRIBUTIONS.  During the
Restricted Period, Participants holding shares of Restricted Stock granted
hereunder may exercise full voting rights and shall receive all regular cash
dividends paid with respect to such shares.  Except as the Committee shall
otherwise determine, any other cash dividends and other distributions paid to
Participants with respect to shares of Restricted Stock including any dividends
and distributions paid in shares shall be subject to the same restrictions and
conditions as the shares of Restricted Stock with respect to which they were
paid.

     (f)  OTHER AWARDS SETTLED WITH RESTRICTED STOCK.  The Committee may, at the
time any Award described in this Section 6 is granted, provide that any or all
the Stock delivered pursuant to the Award will be Restricted Stock.


                                       -6-
<PAGE>


     (g)  UNRESTRICTED STOCK.  The Committee may, in its sole discretion, sell
to any Participant shares of Stock free of restrictions under the Plan for a
price which is not less than the par value of the Stock.

     (h)  NOTICE OF SECTION 83(B) ELECTION.  Any Participant making an election
under Section 83(b) of the Code with respect to Restricted Stock must provide a
copy thereof to the Company within 10 days of filing such election with the
Internal Revenue Service.

     6.4. DEFERRED STOCK.

     A Deferred Stock Award entitles the recipient to receive shares of Stock to
be delivered in the future.  Delivery of the Stock will take place at such time
or times, and on such conditions, as the Committee may specify.  The Committee
may at any time accelerate the time at which delivery of all or any part of the
Stock will take place.  At the time any Award described in this Section 6 is
granted, the Committee may provide that, at the time Stock would otherwise be
delivered pursuant to the Award, the Participant will instead receive an
instrument evidencing the Participant's right to future delivery of Deferred
Stock.

     6.5. PERFORMANCE AWARDS; PERFORMANCE GOALS.

     (a)  NATURE OF PERFORMANCE AWARDS.  A Performance Award entitles the
recipient to receive, without payment, an amount in cash or Stock or a
combination thereof (such form to be determined by the Committee) following the
attainment of performance goals.  Performance goals may be related to personal
performance, corporate performance, departmental performance or any other
category of performance established by the Committee.  The Committee will
determine the performance goals, the period or periods during which performance
is to be measured and all other terms and conditions applicable to the Award.

     (b)  OTHER AWARDS SUBJECT TO PERFORMANCE CONDITION.  The Committee may, at
the time any Award described in this Section 6 is granted, impose the condition
(in addition to any conditions specified or authorized in this Section 6 or any
other provision of the Plan) that Performance Goals be met prior to the
Participant's realization of any payment or benefit under the Award.

     6.6. LOANS AND SUPPLEMENTAL GRANTS.

     (a)  LOANS.  The Company may make a loan to a Participant ("Loan"), either
on the date of or after the grant of any Award to the Participant.  A Loan may
be made either in connection with the purchase of Stock under the Award or with
the payment of any Federal, state and local income tax with respect to income
recognized as a result of the Award.  The Committee will have full authority to
decide whether to make a Loan and to determine the amount, terms and conditions
of the Loan, including the interest rate (which may be zero), whether the Loan
is to be secured or unsecured or with or without recourse against the borrower,
the terms on which the Loan is to be repaid and the conditions, if any, under
which it may be forgiven.  However, no Loan may have a term (including
extensions) exceeding ten years in duration.


                                       -7-
<PAGE>


     (b)  SUPPLEMENTAL GRANTS.  In connection with any Award, the Committee may
at the time such Award is made or at a later date, provide for and grant a cash
award to the Participant ("Supplemental Grant") not to exceed an amount equal to
(1) the amount of any Federal, state and local income tax on ordinary income for
which the Participant may be liable with respect to the Award, determined by
assuming taxation at the highest marginal rate, plus (2) an additional amount on
a grossed-up basis intended to make the Participant whole on an after-tax basis
after discharging all the Participant's income tax liabilities arising from all
payments under this Section 6.  Any payments under this subsection (b) will be
made at the time the Participant incurs Federal income tax liability with
respect to the Award.

7.   EVENTS AFFECTING OUTSTANDING AWARDS

     7.1. DEATH.

     If a Participant dies, the following will apply:

     (a)  All Options and Stock Appreciation Rights held by the Participant
immediately prior to death, to the extent then exercisable, may be exercised by
the Participant's executor or administrator or the person or persons to whom the
Option or Right is transferred by will or the applicable laws of descent and
distribution, at any time within the one year period ending with the first
anniversary of the Participant's death (or such shorter or longer period as the
Committee may determine), and shall thereupon terminate.  In no event, however,
shall an Option or Stock Appreciation Right remain exercisable beyond the latest
date on which it could have been exercised without regard to this Section 7.
Except as otherwise determined by the Committee, all Options and Stock
Appreciation Rights held by a Participant immediately prior to death that are
not then exercisable shall terminate at death.

     (b)  Except as otherwise determined by the Committee, all Restricted Stock
held by the Participant must be transferred to the Company (and, in the event
the certificates representing such Restricted Stock are held by the Company,
such Restricted Stock will be so transferred without any further action by the
Participant) in accordance with Section 6.3(d) above.

     (c)  Any payment or benefit under a Deferred Stock Award, Performance
Award, or Supplemental Grant to which the Participant was not irrevocably
entitled prior to death will be forfeited and the Award canceled as of the time
of death, unless otherwise determined the Committee.

     7.2. TERMINATION OF SERVICE (OTHER THAN BY DEATH).

     If a Participant who is an Employee ceases to be an Employee for any reason
other than death, or if there is a termination (other than by reason of death)
of the consulting, service or similar relationship in respect of which a
non-Employee Participant was granted an Award hereunder (such termination of the
employment or other relationship being hereinafter referred to as a "Status
Change"), the following will apply:


                                       -8-
<PAGE>


     (a)  Except as otherwise determined by the Committee, all Options and Stock
Appreciation Rights held by the Participant that were not exercisable
immediately prior to the Status Change shall terminate at the time of the Status
Change.  Any Options or Rights that were exercisable immediately prior to the
Status Change will continue to be exercisable for a period of three months (or
such longer period as the Committee may determine), and shall thereupon
terminate, unless the Award provides by its terms for immediate termination in
the event of a Status Change (unless otherwise determined by the Committee) or
unless the Status Change results from a discharge for cause which in the opinion
of the Committee casts such discredit on the Participant as to justify immediate
termination of the Award (unless otherwise determined by the Committee).  In no
event, however, shall an Option or Stock Appreciation Right remain exercisable
beyond the latest date on which it could have been exercised without regard to
this Section 7.  For purposes of this paragraph, in the case of a Participant
who is an Employee, a Status Change shall not be deemed to have resulted by
reason of (i) a sick leave or other bona fide leave of absence approved for
purposes of the Plan by the Committee, so long as the Employee's right to
reemployment is guaranteed either by statute or by contract, or (ii) a transfer
of employment between the Company and a subsidiary or between subsidiaries, or
to the employment of a corporation (or a parent or subsidiary corporation of
such corporation) issuing or assuming an option in a transaction to which
section 424(a) of the Code applies.

     (b)  Except as otherwise determined by the Committee, all Restricted Stock
held by the Participant at the time of the Status Change must be transferred to
the Company (and, in the event the certificates representing such Restricted
Stock are held by the Company, such Restricted Stock will be so transferred
without any further action by the Participant) in accordance with Section 6.3
(c) above.

     (c)  Any payment or benefit under a Deferred Stock Award, Performance
Award, or Supplemental Grant to which the Participant was not irrevocably
entitled prior to the Status Change will be forfeited and the Award cancelled as
of the date of such Status Change unless otherwise determined by the Committee.

     7.3. CERTAIN CORPORATE TRANSACTIONS.

     Except as otherwise provided by the Committee at the time of grant, in the
event of a consolidation or merger in which the Company is not the surviving
corporation or which results in the acquisition of substantially all the
Company's outstanding Stock by a single person or entity or by a group of
persons and/or entities acting in concert, or in the event of the sale or
transfer of substantially all the Company's assets or a dissolution or
liquidation of the Company (a "covered transaction"), the following rules shall
apply:

     (a)  Subject to paragraph (b) below, all outstanding Awards requiring
exercise will cease to be exercisable, and all other Awards to the extent not
fully vested (including Awards subject to conditions not yet satisfied or
determined) will be forfeited, as of the effective time of the covered
transaction, provided that the Committee may in its sole discretion, on or prior
to the effective date of the covered transaction, (1) make any outstanding
Option and Stock Appreciation Right exercisable in full, (2) remove the
restrictions from any Restricted Stock, (3) cause the Company to make any
payment and


                                       -9-
<PAGE>


provide any benefit under any Deferred Stock Award, Performance Award, or
Supplemental Grant, (4) remove any performance or other conditions or
restrictions on any Award, and (5) forgive all or any portion of the principal
of or interest on a Loan; or

     (b)  With respect to an outstanding Award held by a participant who,
following the covered transaction, will be employed by or otherwise providing
services to a corporation which is a surviving or acquiring corporation in the
covered transaction or an affiliate of such a corporation, the Committee may at
or prior to the effective time of the covered transaction, in its sole
discretion and in lieu of the action described in paragraph (a) above, arrange
to have such surviving or acquiring corporation or affiliate assume any Award
held by such participant outstanding hereunder or grant a replacement award
which, in the judgment of the Committee, is substantially equivalent to any
Award being replaced.

     7.4. TERMINATION FOLLOWING CHANGE OF CONTROL.

     Notwithstanding any other provision of this Plan, if the Participant's
employment terminates because of a "Qualified Termination" as defined in Exhibit
A, all unvested Options and Stock Appreciation Rights then held by such person
shall immediately become fully vested, all Options and Stock Appreciation Rights
then held by such person shall remain exercisable until the earlier of (i) the
fourth anniversary of such Qualified Termination and (ii) the latest date on
which such Option or Right could have been exercised without regard to Section
7.1 and Section 7.2, and all other Awards shall immediately become fully vested
and all restrictions, conditions and performance goals with respect to such
Awards shall be deemed satisfied and shall no longer be applicable.

8.   GENERAL PROVISIONS

     8.1. DOCUMENTATION OF AWARDS.

     Awards will be evidenced by such written instruments, if any, as may be
prescribed by the Committee from time to time.  Such instruments may be in the
form of agreements to be executed by both the Participant and the Company, or
certificates, letters or similar instruments, which need not be executed by the
Participant but acceptance of which will evidence agreement to the terms
thereof.

     8.2. RIGHTS AS A STOCKHOLDER, DIVIDEND EQUIVALENTS.

     Except as specifically provided by the Plan, the receipt of an Award will
not give a Participant rights as a stockholder; the Participant will obtain such
rights, subject to any limitations imposed by the Plan or the instrument
evidencing the Award, upon actual receipt of Stock.  However, the Committee may,
on such conditions as it deems appropriate, provide that a Participant will
receive a benefit in lieu of cash dividends that would have been payable on any
or all Stock subject to the Participant's Award had such Stock been outstanding.
Without limitation, the Committee may provide for payment to the Participant of
amounts representing such dividends, either currently or in the future, or for
the investment of such amounts on behalf of the Participant.


                                      -10-
<PAGE>


     8.3. CONDITIONS ON DELIVERY OF STOCK.

     The Company will not be obligated to deliver any shares of Stock pursuant
to the Plan or to remove restriction from shares previously delivered under the
Plan (a) until all conditions of the Award have been satisfied or removed, (b)
until, in the opinion of the Company's counsel, all applicable Federal and state
laws and regulation have been complied with, (c) if the outstanding Stock is at
the time listed on any stock exchange or The Nasdaq National Market, until the
shares to be delivered have been listed or authorized to be listed on such
exchange or market upon official notice of notice of issuance, and (d) until all
other legal matters in connection with the issuance and delivery of such shares
have been approved by the Company's counsel.  If the sale of Stock has not been
registered under the Securities Act of 1933, as amended, the Company may
require, as a condition to exercise of the Award, such representations or
agreements as counsel for the Company may consider appropriate to avoid
violation of such Act and may require that the certificates evidencing such
Stock bear an appropriate legend restricting transfer.

     If an Award is exercised by the Participant's legal representative, the
Company will be under no obligation to deliver Stock pursuant to such exercise
until the Company is satisfied as to the authority of such representative.

     8.4. TAX WITHHOLDING.

     The Company will withhold from any cash payment made pursuant to an Award
an amount sufficient to satisfy all federal, state and local withholding tax
requirements (the "withholding requirements").

     In the case of an Award pursuant to which Stock may be delivered, the
Committee will have the right to require that the Participant or other
appropriate person remit to the Company an amount sufficient to satisfy the
withholding requirements, or make other arrangements satisfactory to the
Committee with regard to such requirements, prior to the delivery of any Stock.
If and to the extent that such withholding is required, the Committee may permit
the Participant or such other person to elect at such time and in such manner as
the Committee provides to have the Company hold back from the shares to be
delivered, or to deliver to the Company, Stock having a value calculated to
satisfy the withholding requirement.  The Committee may make such share
withholding mandatory with respect to any Award at the time such Award is made
to a Participant.

     If at the time an ISO is exercised the Committee determines that the
Company could be liable for withholding requirements with respect to a
disposition of the Stock received upon exercise, the Committee may require as a
condition of exercise that the person exercising the ISO agree (a) to inform the
Company promptly of any disposition (within the meaning of section 424(c) of the
Code) of Stock received upon exercise, and (b) to give such security as the
Committee deems adequate to meet the potential liability of the Company for the
withholding requirements and to augment such security from time to time in any
amount reasonably deemed necessary by the Committee to preserve the adequacy of
such security.

     8.5. NONTRANSFERABILITY OF AWARDS.


                                      -11-
<PAGE>


     Unless otherwise permitted by the Committee, no Award (other than an Award
in the form of an outright transfer of cash or Unrestricted Stock) may be
transferred other than by will or by the laws of descent and distribution, and
during a Participant's lifetime an Award requiring exercise may be exercised
only by the Participant (or in the event of the Participant's incapacity, the
person or persons legally appointed to act on the Participant's behalf).

     8.6. ADJUSTMENTS IN THE EVENT OF CERTAIN TRANSACTIONS.

     (a)  In the event of a stock dividend, stock split or combination of
shares, recapitalization or other change in the Company's capitalization, or
other distribution to common stockholders other than normal cash dividends,
after the effective date of the Plan, the Committee will make any appropriate
adjustments to the maximum number of shares that may be delivered under the Plan
under Section 4 above.

     (b)  In any event referred to in paragraph (a), the Committee will also
make any appropriate adjustments to the number and kind of shares of stock or
securities subject to Awards then outstanding or subsequently granted, any
exercise prices relating to Awards and any other provision of Awards affected by
such change.  The Committee may also make such adjustments to take into account
material changes in law or in accounting practices or principles, mergers,
consolidations, acquisitions, dispositions or similar corporate transactions, or
any other event, if it is determined by the Committee that adjustments are
appropriate to avoid distortion in the operation of the Plan.

     (c)  In the case of ISOs or for purposes of the limits set forth in the
second paragraph of Section 4, the adjustments described in (a) and (b) will be
made only to the extent consistent with continued qualification of the option
under Section 422 of the Code (in the case of an ISO) or Section 162(m) of the
Code (in the case of the limits in Section 4).

     8.7. EMPLOYMENT RIGHTS, ETC.

     Neither the adoption of the Plan nor the grant of Awards will confer upon
any person any right to continued retention by the Company or any subsidiary as
an Employee or otherwise, or affect in any way the right of the Company or
subsidiary to terminate an employment, service or similar relationship at any
time.  Except as specifically provided by the Committee in any particular case,
the loss of existing or potential profit in Awards granted under the Plan will
not constitute an element of damages in the event of termination of an
employment, service or similar relationship even if the termination is in
violation of an obligation of the Company to the Participant.

     8.8. DEFERRAL OF PAYMENTS.

     The Committee may agree at any time, upon request of the Participant, to
defer the date on which any payment under an Award will be made.

     8.9. PAST SERVICES AS CONSIDERATION.


                                      -12-
<PAGE>


     Where a Participant purchases Stock under an Award for a price equal to the
par value of the Stock the Committee may determine that such price has been
satisfied by past services rendered by the Participant.

9.   EFFECT, AMENDMENT AND TERMINATION

     Neither adoption of the Plan nor the grant of Awards to a Participant will
affect the Company's right to grant to such Participant awards that are not
subject to the Plan, to issue to such Participant Stock as a bonus or otherwise,
or to adopt other plans or arrangements under which Stock may be issued to
Employees.

     The Committee may at any time or times amend the Plan or any outstanding
Award for any purpose which may at the time be permitted by law, or may at any
time terminate the Plan as to any further grants of Awards, provided that
(except to the extent expressly required or permitted by the Plan) no such
amendment will, without the approval of the stockholders of the Company,
effectuate a change for which stockholder approval is required in order for the
Plan to continue to qualify for the award of ISOs under section 422 of the Code,
for the award of performance-based compensation under Section 162(m) of the Code
or under Rule 16b-3 promulgated under Section 16 of the 1934 Act.




                                      -13-
<PAGE>


                                                                       EXHIBIT A

     For purposes of Section 7.4 of the Plan, the following terms have the
following meanings:

     "Base Salary" means Participant's annual base salary, exclusive of any
bonus or other benefits the Participant may receive.

     "Cause" means the following, determined by the Committee in its reasonable
judgment:

          (i)    willful failure to perform, or gross negligence in the
                 performance of, Participant's duties and responsibilities to
                 the Company and its subsidiaries; or

          (ii)   fraud, embezzlement or other material dishonesty with respect
                 to the Company or any of its subsidiaries; or

          (iii)  conviction of, or plea of nolo contendere to, a felony or other
                 crime involving moral turpitude; or

          (iv)   other conduct by Participant that is materially harmful to the
                 business, interests or reputation of the Company or any of its
                 subsidiaries.

     "Change of Control" means such time as:

          (i)    a "person" or "group" (within the meaning of Sections 13(d) and
                 14(d)(2) of the Exchange Act) becomes the ultimate "beneficial
                 owner" (as defined in Rule 13d-3 under the Exchange Act) of
                 Voting Stock representing more than 50 % of the total voting
                 power of the Voting Stock of the Company on a fully diluted
                 basis,

          (ii)   individuals who on the May 30, 1996 constitute the Board
                 (together with any new directors whose election by the Board or
                 whose nomination for election by the Company's stockholders was
                 approved by a vote of at least two-thirds of the members of the
                 Board then in office who either were members of the Board on
                 May 30, 1996 or whose election or nomination for election was
                 previously so approved) cease for any reason to constitute a
                 majority of the members of the Board then in office and

          (iii)  the merger or consolidation of the Company with or into another
                 corporation; or the merger or consolidation of another
                 corporation with and into the Company, with the effect that,
                 immediately after such transaction, the Voting Stock of the
                 entity surviving such


                                      -14-
<PAGE>


                 merger or consolidation received in such transaction by the
                 stockholders of the Company immediately prior to such
                 transaction represents the ultimate beneficial ownership of
                 less than 50% of Voting Stock of the entity surviving such
                 merger or consolidation.

     "Disability" has the meaning given it in any long-term disability plan of
the Company in which Participant participates. Participant's employment shall be
deemed terminated for Disability when Participant is entitled to receive
long-term disability compensation pursuant to such long-term disability plan.
If the Company does not maintain such a plan, Participant shall be deemed
terminated for Disability if the Company terminates his employment due to
illness, injury, accident or condition of either a physical or psychological
nature as a result of which Participant is unable to perform substantially the
duties and responsibilities of his position for 180 days during a period of 365
consecutive calendar days.

     "Good Reason" means the voluntary termination by Participant of his or her
employment after the occurrence, without Participant's express written consent,
of any of the following events:

          (i)    assignment to Participant of duties materially inconsistent
                 with his or her positions, duties, responsibilities, or
                 reporting requirements with the Company (or a subsidiary)
                 immediately prior to a Change of Control or a material adverse
                 alteration in Participant's status or the nature of his or her
                 responsibilities with the Company immediately prior to a Change
                 in Control; or

          (ii)   reduction in Participant's rate of Base Salary to less than 100
                 percent of the rate of Base Salary paid to the Participant
                 immediately preceding the Change of Control, or reduction in
                 Participant's total cash compensation opportunities, including
                 salary, incentives and other benefits, for any fiscal year to
                 less than 100 percent of the total cash compensation
                 opportunities made available to the Participant immediately
                 preceding the Change of Control (for this purpose, such
                 opportunities shall be deemed reduced if the objective
                 standards by which Participant's incentive compensation is
                 measured become materially more stringent or if the amount of
                 such compensation is materially reduced on a discretionary
                 basis from the amount that would be payable solely by reference
                 to the objective standards).

     "Qualified Termination" means the termination of Participant's employment
during a Standstill Period (1) by the Company other than for Cause, death or
Disability, and (2) in the case of a Participant who at the time of the Change
of Control holds an office specifically designated by the Committee in its sole
discretion to have such right, by Participant for Good Reason.


                                      -15-
<PAGE>


     "Standstill Period" is the period commencing on the date of a Change of
Control and continuing until the close of business on the last business day of
the 24th calendar month following such Change of Control.

     "Voting Stock" means the capital stock of any class or kind ordinarily
having the power to vote for the election of directors, managers or other voting
members of the governing body of such Person.






                                      -16-



<PAGE>

                          ADVANCED RADIO TELECOM CORP.
                  NON-EMPLOYEE DIRECTOR STOCK OPTION AGREEMENT
                             (Initial Option Grant)

          THIS AGREEMENT, made and entered into as of the ____ day of
___________, 199_ between ADVANCED RADIO TELECOM CORP., a Delaware corporation
(herein called the "Corporation"), and _____________ (herein called the
"Optionee").


                              W I T N E S S E T H:


     WHEREAS, on the date hereof Optionee was elected a director of the
Corporation and qualifies as an Eligible Person under the Corporation's 1996
Non-Employee Directors Automatic Stock Option Plan (the "Plan"); and

     WHEREAS, under the terms and conditions hereinafter stated, the Corporation
hereby grants to the Optionee on the date hereof (the "Grant Date") pursuant to
the Plan options (the "Options") to purchase 7,000 shares of the Corporation's
common stock, $.001 par value per share ("Common Stock") at an exercise price of
$_____ per share, subject to adjustment as provided in the Plan (the "option
price").

     NOW, THEREFORE, the Corporation and the Optionee agree as follows:

     1.   DEFINITIONS.  All capitalized terms not otherwise defined herein shall
have the meanings given to them in the Plan.

     2.   TERM. The term of each Option shall commence on the Grant Date and
shall terminate at 5:00 P.M., P.S.T., on the fifth anniversary of the Grant Date
(the "Expiration Date").

     3.   EXERCISE. Each Option may be exercised in whole or in part in
accordance with the following schedule: up to 2,334 shares upon and after the
Grant Date, and up to an additional 2,333 shares upon and after the first and
second anniversary of the Grant Date, for an aggregate of 7,000 shares. The
method for exercise described in this Paragraph shall be the sole method of such
exercise. The Optionee may exercise the Options by delivery to the Corporation
of written notice accompanied by payment of the Option Price as provided in the
Plan. The Options shall be considered exercised on the date the notice and
payment are delivered to the President of the Corporation or deposited in the
mail, as the case may be.

     4.   TRANSFERABILITY OF OPTIONS. The Options shall not be transferable by
the Optionee otherwise than by will or under the laws of descent and
distribution. The Options shall be exercisable during the lifetime of the
Optionee only by the Optionee, the Optionee's guardian or the Optionee's legal
representative.

<PAGE>

     5.  TERMINATION OF AFFILIATION. If Optionee's service as a Board member
ceases prior to the Expiration Date for any reason while an Option remains
outstanding and unexercised, then the Option term shall immediately terminate
and the Option shall cease to be outstanding in accordance with the Plan.  In no
event, however, may any Option be exercised after the Expiration Date of such
Option.

     6.  REQUIREMENTS OF LAW. The Corporation shall not be required to sell or
issue Common Stock under the Options if the issuance of such Common Stock would
constitute a violation by the Optionee or the Corporation of any provisions of
any state or federal law, rule or regulation. In addition, in connection with
the Securities Act of 1933 (as now in effect or hereafter amended), upon
exercise of the Options, the Corporation shall not be required to issue such
Common Stock unless the Corporation has received evidence satisfactory to it to
the effect that the Optionee will not transfer such shares except pursuant to a
registration statement in effect under such Act, or unless an opinion of counsel
to the Corporation has been received by the Corporation to the effect that such
registration is not required. Any determination in this connection by the
Corporation shall be final, binding and conclusive. In the event the shares
issuable on exercise of the Options are not registered under the Securities Act
of 1933, the Corporation may imprint the following legend or any other legend
which counsel for the Corporation considers necessary or advisable to comply
with the Securities Act of 1933:

          "The shares of stock represented by this certificate have not been
     registered under the Securities Act of 1933 or under the securities laws of
     any state and may not be sold or transferred except upon such registration
     or upon receipt by the Corporation of an opinion of counsel satisfactory to
     the Corporation, in form and substance satisfactory to the Corporation,
     that registration is not required for such sale or transfer."

     The Corporation may, but shall in no event be obligated to, register any
securities covered hereby pursuant to the Securities Act of 1933 (as now in
effect or as hereafter amended); and in the event any shares are so registered
the Corporation may remove any legend on certificates representing such shares.
The Corporation shall not be obligated to take any other affirmative action in
order to cause the exercise of the Options or the issuance of shares pursuant
thereto to comply with any state or federal law, rule or regulation.

     7.  NO RIGHTS AS STOCKHOLDER. Except as otherwise provided in the Plan, the
Optionee shall have no rights as a stockholder with respect to Common Stock
covered by the Options until the date of issuance to the Optionee of a stock
certificate for such Common Stock.

     8.  EMPLOYMENT OBLIGATION. The granting of the Options shall not impose
upon the Corporation any obligation to employ or become affiliated with or
continue to employ or


                                       -2-
<PAGE>


be affiliated with the Optionee. The right of the Corporation to terminate the
employment of or its affiliation with the Optionee or any other person shall not
be diminished or affected by reason of the fact that the Options has been
granted to the Optionee.

     9.  WITHHOLDING AND REPORTING.  The Corporation's obligation to deliver
shares of Common Stock or to make any payment upon the exercise of the Options
shall be subject to applicable federal, state and local tax withholding and
reporting requirements.

     10.  SUBJECT TO PLAN.  The Options are subject to all the terms,
conditions, limitations and restrictions contained in the Plan, as amended from
time, which shall be controlling in the event of any conflicting or inconsistent
provisions.

     11.  INTERPRETATION OF AGREEMENT; GOVERNING LAW. The Options granted
pursuant hereto are intended to be "incentive stock options" within the meaning
of the Internal Revenue Code of 1986, as amended. This Agreement shall be
construed and enforced in accordance with, and governed by, the laws of the
State of Washington.


                         ADVANCED RADIO TELECOM CORP.



                         By:______________________________
                         Name:____________________________
                         Title:___________________________


     The optionee hereby acknowledges that he has received and reviewed a copy
of the Plan and accepts and agrees to be bound by all terms and conditions
hereof and thereof.



___________________________________
     [OPTIONEE]

Date: ___________________________





                                       -3-
<PAGE>


                          ADVANCED RADIO TELECOM CORP.
                  NON-EMPLOYEE DIRECTOR STOCK OPTION AGREEMENT
                             (Annual Option Grants)

          THIS AGREEMENT, made and entered into as of the 1st day of January,
199_ between ADVANCED RADIO TELECOM CORP., a Delaware corporation (herein called
the "Corporation"), and _____________ (herein called the "Optionee").


                              W I T N E S S E T H:


     WHEREAS, Optionee is a director of the Corporation and qualifies as an
Eligible Person under the Corporation's 1996 Non-Employee Directors Automatic
Stock Option Plan (the "Plan"); and

     WHEREAS, under the terms and conditions hereinafter stated, the Corporation
hereby grants to the Optionee on the date hereof (the "Grant Date") pursuant to
the Plan options (the "Options") to purchase 6,000 shares of the Corporation's
common stock, $.001 par value per share ("Common Stock") at an exercise price of
$_____ per share, subject to adjustment as provided in the Plan (the "option
price").

     NOW, THEREFORE, the Corporation and the Optionee agree as follows:

     1.   DEFINITIONS.  All capitalized terms not otherwise defined herein shall
have the meanings given to them in the Plan.

     2.   TERM. The term of each Option shall commence on the Grant Date of such
option and shall terminate at 5:00 P.M., P.S.T., on the fifth anniversary of the
Grant Date (the "Expiration Date").

     3.  EXERCISE. Each Option may be exercised in whole or in part in
accordance with the following schedule: up to 2,000 shares upon and after the
Grant Date, and up to an additional 2,000 shares upon and after the first and
second anniversary of the Grant Date, for an aggregate of 6,000 shares. The
method for exercise described in this Paragraph shall be the sole method of such
exercise. The Optionee may exercise the Options by delivery to the Corporation
of written notice accompanied by payment of the Option Price as provided in the
Plan. The Options shall be considered exercised on the date the notice and
payment are delivered to the President of the Corporation or deposited in the
mail, as the case may be.

     4.  TRANSFERABILITY OF OPTIONS. The Options shall not be transferable by
the Optionee otherwise than by will or under the laws of descent and
distribution. The Options shall be exercisable during the lifetime of the
Optionee only by the Optionee, the Optionee's guardian or the Optionee's legal
representative.

     5.  TERMINATION OF AFFILIATION. If Optionee's service as a Board member
ceases prior to the Expiration Date for any reason


                                       -3-
<PAGE>


while an Option remains outstanding and unexercised, then the Option term shall
immediately terminate and the Option shall cease to be outstanding in accordance
with the Plan.  In no event, however, may any Option be exercised after the
Expiration Date of such Option.

     6.  REQUIREMENTS OF LAW. The Corporation shall not be required to sell or
issue Common Stock under the Options if the issuance of such Common Stock would
constitute a violation by the Optionee or the Corporation of any provisions of
any state or federal law, rule or regulation. In addition, in connection with
the Securities Act of 1933 (as now in effect or hereafter amended), upon
exercise of the Options, the Corporation shall not be required to issue such
Common Stock unless the Corporation has received evidence satisfactory to it to
the effect that the Optionee will not transfer such shares except pursuant to a
registration statement in effect under such Act, or unless an opinion of counsel
to the Corporation has been received by the Corporation to the effect that such
registration is not required. Any determination in this connection by the
Corporation shall be final, binding and conclusive. In the event the shares
issuable on exercise of the Options are not registered under the Securities Act
of 1933, the Corporation may imprint the following legend or any other legend
which counsel for the Corporation considers necessary or advisable to comply
with the Securities Act of 1933:

          "The shares of stock represented by this certificate have not been
     registered under the Securities Act of 1933 or under the securities laws of
     any state and may not be sold or transferred except upon such registration
     or upon receipt by the Corporation of an opinion of counsel satisfactory to
     the Corporation, in form and substance satisfactory to the Corporation,
     that registration is not required for such sale or transfer."

     The Corporation may, but shall in no event be obligated to, register any
securities covered hereby pursuant to the Securities Act of 1933 (as now in
effect or as hereafter amended); and in the event any shares are so registered
the Corporation may remove any legend on certificates representing such shares.
The Corporation shall not be obligated to take any other affirmative action in
order to cause the exercise of the Options or the issuance of shares pursuant
thereto to comply with any state or federal law, rule or regulation.

     7.  NO RIGHTS AS STOCKHOLDER. Except as otherwise provided in the Plan, the
Optionee shall have no rights as a stockholder with respect to Common Stock
covered by the Options until the date of issuance to the Optionee of a stock
certificate for such Common Stock.

     8.  EMPLOYMENT OBLIGATION. The granting of the Options shall not impose
upon the Corporation any obligation to employ or become affiliated with or
continue to employ or be affiliated with the Optionee. The right of the
Corporation to terminate the


                                       -2-
<PAGE>


employment of or its affiliation with the Optionee or any other person shall not
be diminished or affected by reason of the fact that the Options has been
granted to the Optionee.

     9.  WITHHOLDING AND REPORTING.  The Corporation's obligation to deliver
shares of Common Stock or to make any payment upon the exercise of the Options
shall be subject to applicable federal, state and local tax withholding and
reporting requirements.

     10.  SUBJECT TO PLAN.  The Options are subject to all the terms,
conditions, limitations and restrictions contained in the Plan, as amended from
time, which shall be controlling in the event of any conflicting or inconsistent
provisions.

     11.  INTERPRETATION OF AGREEMENT; GOVERNING LAW. The Options granted
pursuant hereto are intended to be "incentive stock options" within the meaning
of the Internal Revenue Code of 1986, as amended. This Agreement shall be
construed and enforced in accordance with, and governed by, the laws of the
State of Washington.


                         ADVANCED RADIO TELECOM CORP.



                         By:______________________________
                         Name:____________________________
                         Title:___________________________


     The optionee hereby acknowledges that he has received and reviewed a copy
of the Plan accepts and agrees to be bound by all terms and conditions hereof
and thereof.



___________________________________
     [OPTIONEE]

Date: ___________________________


                                       -3-


<PAGE>

                                                                EXHIBIT 10-8(c)

                            ASSET PURCHASE AGREEMENT
 

     This Asset Purchase Agreement made as of June __, 1996 (the "Agreement")
among Advanced Radio Technologies Corporation, a Delaware corporation, ("ART"),
Extended Communications, Inc., a Washington corporation ("Extended"), and Thomas
A. Marinkovich, Teresa E. Marinkovich, Mark T. Marinkovich and James A.
Marinkovich (collectively, the "Selling Stockholders"" and each a "Selling
Stockholder" and together with Extended, the "Sellers").

     WHEREAS, ART and Extended entered into a Joint Venture Agreement dated
April 4, 1995 (the "Joint Venture Agreement") pursuant to which ART and Extended
formed a general partnership (the "Partnership") with each of ART and Extended
owning a fifty percent (50%) interest in the Partnership (each such fifty
percent interest being referred to herein as a "Partnership Interest");

     WHEREAS, ART wishes to purchase, and Extended wishes to sell, certain
assets, property and rights of Extended, listed in Section 1.1 hereof, and
defined as the "Assets" therein, in exchange for the consideration described in
Section 1.3 hereof (the "Transaction").

     WHEREAS, the Selling Stockholders collectively own 100% of the outstanding
capital stock of Extended;

      NOW, THEREFORE, in consideration of the premises and the respective
covenants and representations and warranties herein contained, the parties
hereto agree as follows:

1.   SALE OF ASSETS.

     1.1.  SALE OF ASSETS.  Subject to and upon the terms and conditions of this
Agreement, Extended agrees to sell and transfer to ART and ART agrees to acquire
from Extended, free and clear of any pledge, lien, options, warrants, security
interest, mortgage claim, charge, liability or other encumbrance of any kind
whatsoever (the "Liens"), at the Closing all of Extended's right, title and
interest in, to and under the assets, properties and rights described in the
following Paragraphs (a) and (b):

          (a)  all governmental permits, certificates, approvals, variances,
     waivers, consents, grants, filings and other authorizations, and
     applications for any of the foregoing, including any grants or applications
     (including those contributed by Extended to the Partnership) including all
     38 GHz radio authorizations granted by the Federal Communications
     Commission ("FCC") in all of the various places in the United States (the
     "Authorizations"), including those listed on Schedule 1.1(a); and

          (b)  Extended's Partnership Interest.


<PAGE>

     All of the foregoing, including the Authorizations and the Partnership
Interest, are sometimes hereinafter collectively referred to as the "Assets".

     1.2.  NO ASSUMPTION OF ANY LIABILITIES.  ART will not assume, satisfy or
perform any of the debts, liabilities, obligations or commitments of Extended. 
Extended will retain all such debts, liabilities, obligations and commitments.

     1.3.  DETERMINATION OF THE CONSIDERATION.  The Purchase Price that ART 
shall pay for the Assets and the other agreements of the Sellers herein is six 
million dollars ($6,000,000), subject to adjustment as provided in Section 1.4 
hereof (with such adjustments, if any, the "Purchase Price").

     1.4.  ADJUSTMENTS DUE TO TRANSFER OF LESS THAN ALL OF THE AUTHORIZATIONS. 
Without limiting any rights, if any, of ART for breach of contract, in the event
that the FCC denies the transfer by Extended to ART of less than all of the
Authorizations but does approve the transfer of one or more of the
Authorizations, the Purchase Price shall be the sum of (i) Three Million Dollars
($3,000,000) and (ii) the product of Three Million Dollars ($3,000,000)
multiplied by the fraction in which the numerator is the number of POPs
contained in all of the granted 38 GHz authorizations held by the Partnership
that have been approved by the FCC for transfer as listed on Exhibit 1.4, and
the denominator is the total number of POPs contained in all of the granted 38
GHz authorizations held by the Partnership as listed on Exhibit 1.4 (for
purposes of this Section, "authorizations held by the Partnership" shall include
authorizations required to be contributed to the Partnership by either ART or
Extended pursuant to the Joint Venture Agreement).  "POPs" shall mean the
population of the geographic area of a Authorization (as defined herein) as
calculated according to the latest official statistics from the United States
Bureau of the Census available as of the date of the Closing (as defined below).

     1.5.  DEPOSIT.  ART shall pay to Extended, if and only if, a sale of
securities that satisfies the condition of Section 9.10 hereof is consummated
three million dollars ($3,000,000) as a deposit under this Agreement (the
"Deposit") within five business days of the consummation of such sale.  If the
Closing occurs, the Deposit shall be credited against the Purchase Price, as
adjusted.  If the Closing does not occur, Extended shall retain the Deposit.

2.   CLOSING.

     2.1.  The closing of the Transaction (the "Closing") shall take place on
such date and at such time within 30 days of the satisfaction of the conditions
contained in Sections 9 and 10 as mutually agreed by the parties (the "Closing
Date") (i) at the offices of Ropes & Gray, One International Place, Boston,
Massachusetts 02110 or (ii) at such other place and time as the parties agree.

                                     -2-

<PAGE>

     2.2.  DELIVERIES BY THE COMPANY AT CLOSING.  At Closing, the Sellers shall
deliver to ART:

          (a)  any Bills of Sale or other instruments of assignment reasonably
     required or requested by ART to transfer, convey and assign the Assets to
     ART;

          (b)  updated Schedules to this Agreement;

          (c)  certified copies of resolutions of the shareholders and the board
     of directors of Extended authorizing Extended to enter into and perform its
     obligations under this Agreement;

          (d)  a copy of the charter documents of Extended certified by the
     appropriate public official and a copy of the by-laws of Extended certified
     by its Secretary;

          (e)  all such other documents and instruments as ART or its counsel
     shall reasonably request to consummate or evidence the transactions
     contemplated hereby; and

          (f)  any tax clearance certificates or other similar certificates.

     2.3.  DELIVERIES BY ART AT CLOSING.  At Closing, ART shall deliver to
Extended the Purchase Price in cash or by certified check or wire transfer; and
such documents and instruments as Extended or its counsel shall reasonably
request to consummate or evidence the transactions contemplated hereby.

     2.4.  CERTIFICATIONS; OPINIONS.  At Closing ART and Extended shall deliver
the certificates, opinion of counsel and other documents described in Sections 9
and 10 hereof unless waived.

     2.5.  CONSENTS.  At Closing, Extended shall deliver evidence satisfactory
to ART that the Final Order required pursuant to Section 9.3 has been granted by
the FCC.

     2.6.  FORM OF DOCUMENTS AND INSTRUMENTS.  All of the documents and
instruments delivered at Closing shall be in form and substance, and shall be
executed and delivered in a manner, reasonably satisfactory to the parties'
respective counsel.

3.   REPRESENTATIONS AND WARRANTIES OF EXTENDED AND THE SELLING STOCKHOLDERS
Extended and each Selling Stockholder jointly and severally represent and
warrant to ART as follows:

     3.1.  ENTITY STATUS.  Extended is a corporation duly organized, validly
existing and in good standing in the state of Washington.  Extended has full
power and authority to carry on

                                     -3-

<PAGE>

its business as and where now conducted, and to own or lease and to operate 
its properties and assets where such properties and assets are now owned, 
leased or operated by it and where such business is now conducted by it.  
Extended is qualified to do business and is in good standing in each of the 
jurisdictions in which the nature of its business or the property owned or 
leased by it make such qualification necessary. Extended has delivered to ART 
complete and correct copies of any organizational, by-laws or charter 
documents applicable to it, each as amended and in effect on the date hereof. 
The Selling Stockholders own 100% of the outstanding capital stock of 
Extended, and there are no outstanding subscriptions, options, warrants or 
other rights convertible into or exercisable for, or any agreements to issue, 
capital stock of Extended.

     3.2.  AUTHORITY FOR AGREEMENT; CONFLICTS.

          (a)  Each of Extended and the Selling Stockholders has all necessary
     power and authority, corporate or otherwise, to enter into, execute and
     deliver this Agreement and the other documents to be delivered by Sellers
     at the Closing (and such other documents are collectively the "Seller
     Documents") and to perform fully his or its obligations hereunder and the
     transactions contemplated hereby and thereby.  The execution, delivery and
     performance of this Agreement and the applicable Seller Documents by
     Extended has been duly authorized by all necessary corporate action.

          (b)  This Agreement has been, and the Seller Documents, at the
     Closing, will have been, duly and validly executed and delivered by
     Extended and each Selling Stockholder and this Agreement constitutes, and
     the Seller Documents will constitute, the legal, valid and binding
     obligation of Extended and each Selling Stockholder and this Agreement is,
     and the Seller Documents will be, enforceable by and against Extended and
     each Selling Stockholder in accordance with their terms, except as
     enforceability thereof may be limited by applicable bankruptcy,
     reorganization, insolvency or other laws affecting creditors' rights
     generally or by general principles of equity, regardless of whether such
     enforceability is considered in equity or at law.

          (c)  The execution and delivery of this Agreement and the Seller
     Documents by Extended and each Selling Stockholder and the consummation of
     the transactions contemplated hereby and thereby will not conflict with or
     result in any violations of or defaults under: (i) any statute, regulation,
     order, judgment or decree of any federal, state or local governmental body
     or regulatory authority applicable to Extended, any Selling Stockholder or
     any of the Assets; (ii) any other statute, regulation, order, judgment or
     decree applicable to Extended, any Selling Stockholder or any of the Assets
     under or in any other applicable jurisdiction; (iii) any mortgage,
     indenture, lease, agreement, instrument or other obligation to which
     Extended or any Selling Stockholder is a party or by which any of the
     Assets are bound; or (iv) any permit, concession, grant, franchise,
     license, of or applicable to Extended or any Selling

                                     -4-

<PAGE>

     Stockholder.  Such execution, delivery and consummation will not result in
     the creation of any lien, charge, encumbrance or security interest upon
     any of the Assets.

     3.3.  SUBSIDIARIES.  Extended does not have, and never has had, any
subsidiary. Except for the Partnership, Extended does not presently own, of
record or beneficially, or control, directly or indirectly, any capital stock,
securities convertible into capital stock or any other equity interest in any
corporation, association or business entity.  Except for the Partnership,
Extended is not, directly or indirectly a participant in and has no involvement
in any joint venture, partnership or other noncorporate entity.

     3.4.  CONSENTS AND APPROVALS OF GOVERNMENTAL AUTHORITIES.  Except for the
consent of the FCC to the transfer or change of control of the Authorizations,
no consent, approval or authorization of, or declaration, filing or registration
with, any governmental or regulatory authority is required to be made or
obtained by Extended or any Selling Stockholder in connection with its execution
and delivery of and performance of its or his obligations under, this Agreement.

     3.5.  FCC REGULATORY MATTERS. 

          (a)  Each of the Sellers is in compliance with the Federal
     Communications Act of 1934, as amended (the "Communications Act"), and the
     rules, regulations and policies of the FCC promulgated thereunder
     applicable to Extended in connection with the Assets, and each of the
     Sellers is in compliance with all other federal, state and local laws,
     rules, regulations and ordinances applicable to Extended and is not in
     default under any order, writ, injunction or decree of any court or
     governmental agency or instrumentality applicable to Extended.

          (b)  SHARING AGREEMENTS.  None of the Sellers have entered into any
     agreement for the shared use of facilities, trunk lines, airspace, radio
     frequencies or other assets used in connection with the Assets.

          (c)  FCC AUTHORIZATIONS.  Schedule 1.1(a) sets forth a true and
     complete list of each Authorization that is being transferred to ART
     hereunder (including every Authorization held by Extended or contributed to
     the Partnership by Extended).  Extended has provided to ART true and
     correct copies of the Authorizations received by it from the FCC.  To the
     knowledge of the Sellers, except as set forth on Schedule 3.5, none of such
     Authorizations are subject to any purchase, sale, option or right of first
     refusal agreements.  Extended or the Partnership owns all of the right,
     title and interest in, to and under such Authorizations.  Extended is
     qualified under all laws, rules and regulations to hold the Authorizations
     held by it and its Partnership Interest.

          (d)  AUTHORIZATION COMPLIANCE.  The Authorizations are valid and in
     full force and effect without materially adverse conditions except for such
     conditions as are 

                                     -5-

<PAGE>


     generally applicable to FCC Authorizations or holders of FCC
     Authorizations.  No event has occurred and is continuing that could:
     (i) result in the revocation, termination or adverse modification of any
     Authorization listed on Schedule 1.1(a); or (ii) materially and adversely
     affect any rights of Extended or, to the knowledge of the Sellers, the
     Partnership thereunder prior to Closing or of ART after Closing.  Extended
     has no reason to believe that the Authorizations will not be renewed by the
     FCC in the ordinary course. 

          (e)  REPORTS.  Any and all reports and filings filed with the FCC by
     Extended with respect to the Authorizations were accurate and complete in
     all material respects on the date thereof. 

          (f)  DISCLOSURE.  Extended knows of no facts pertaining to its
     qualifications to be a licensee which would cause the FCC not to issue its
     approval with respect to, or otherwise prevent, the transfer to ART
     pursuant to this Agreement of the Authorizations.

     3.6.  TITLE TO THE TRANSFERRED ASSETS; LIENS.  Extended or, to the
knowledge of the Sellers, the Partnership has good, indefeasible and
transferable title to all of the Assets, free and clear of all Liens.

     3.7.  OTHER ASSETS.  Extended owns no assets other than the Assets, capital
stock of ART and cash that are material either individually or in the aggregate.

     3.8.  CONTRACTS.  Except for this Agreement and the Joint Venture
Agreement, and except as disclosed on Schedule 3.8, Extended is not a party to
any contract, commitment or similar agreement or arrangement, whether written or
oral, by which it or any of the Assets is bound.  Extended has no liabilities or
obligations of any kind, whether accrued, absolute, secured or unsecured,
contingent or otherwise which are material either individually or in the
aggregate. 

     3.9.  LITIGATION.  There are no actions, claims, proceedings, suits and
investigations pending, or, to the best knowledge of each of Extended and the
Selling Stockholders threatened against any of Extended, the Assets or any of
its properties, assets or rights before any court, arbitrator or administrative
or governmental body: (i) relating to the Assets or which seek to revoke,
rescind, cancel, modify or refuse to renew any Authorization or; (ii) in
connection with the transactions contemplated hereby, nor is there any basis for
any such action.  There is no judgment, order or decree affecting the Assets or
the transactions contemplated hereby.

     3.10. DISCLOSURE.  Neither this Agreement nor any exhibit or schedule
hereto nor any statement, list or certificate delivered to ART at or prior to
the Closing pursuant to this Agreement contains any untrue statement of a
material fact or omits to state a material fact

                                     -6-

<PAGE>

necessary in order to make the statement contained herein and therein in the 
context in which they were made not misleading.  Except as otherwise 
disclosed herein, none of Extended or the Selling Stockholders know of any 
information or fact that has or would have a material adverse effect, or that 
might in the future have a material adverse effect, on the Assets or the 
financial condition of the business of Extended that has not been disclosed 
to ART in writing.  

     3.11. TAXES.  Extended has timely filed all requisite federal, state and
local tax and information returns which are required to be filed by it and has
paid, or made adequate provision for the payment of, all taxes which may have or
may become due and there are no assessments or any basis therefor.  There are no
examinations in progress or claims against Extended for federal or other taxes
(including penalties and interest) for any period and no notice of any claim,
whether pending or threatened, for taxes has been received.

     3.12. BROKERAGE.  There are no claims for brokerage commissions or finder's
fees or similar compensation in connection with the transactions contemplated by
this Agreement based on any arrangement or agreement made by or on behalf of
Extended or any Selling Stockholder.
     
4.   REPRESENTATIONS AND WARRANTIES BY ART.  ART represents and warrants as
follows:

     4.1.  CORPORATE STATUS; AUTHORITY.

          (a)  ART is a corporation duly organized, validly existing and in good
     standing under the laws of the State of Delaware and has full corporate
     power and authority to carry on its business as now conducted and to own or
     lease and operate its properties as and in the places where such business
     is now conducted and as such properties are now owned, leased or operated. 

          (b)  ART has all necessary corporate power and authority to execute
     and deliver this Agreement and to carry out its obligations hereunder.  The
     execution and delivery of this Agreement and the consummation of the
     transactions contemplated hereby has been duly authorized by the Board of
     Directors of ART.  This Agreement constitutes the valid and legally binding
     obligation of ART and is enforceable against it in accordance with its
     terms, except as enforceability thereof may be limited by applicable
     bankruptcy, reorganization, insolvency or other laws affecting creditors'
     rights generally or by general principles of equity, regardless of whether
     such enforceability is considered in equity or at law.  The execution and
     delivery of this Agreement and the consummation of the transactions
     contemplated hereby, will not conflict with or result in any violation of
     or default under any provision of the charter documents or by- laws of ART
     or any material mortgage, indenture, lease, agreement or other instrument,
     permit, concession, grant, franchise, license, judgment, order, decree,
     statute, law, ordinance, rule or regulation applicable to it or any of its
     respective properties. 

                                     -7-

<PAGE>

     4.2.  LITIGATION.  There are no judicial or administrative actions, suits,
proceedings or investigations pending, or to the knowledge of ART threatened,
that question the validity of this Agreement or of any action taken or to be
taken pursuant to or in connection with the provisions of this Agreement, nor
does ART know of any basis for any such action, suit, proceeding or
investigation.

     4.3.   CONSENTS AND APPROVALS OF GOVERNMENT AUTHORITIES.  Except for the
approval by the FCC of the transfer or change of control, as applicable, of the
Authorizations and except as set forth on Schedule 4.3 hereto, no consent,
approval or authorization of, or declaration, filing or registration with any
court or governmental or regulatory authority is required to be made or obtained
by ART in connection with its execution, delivery and performance of this
Agreement.

     4.4.  BROKERAGE.  There are no claims for brokerage commissions or finder's
fees or similar compensation in connection with the transactions contemplated by
this Agreement based on any arrangement or agreement made by or on behalf of
ART.

5.   EXPENSES.  Each party to this Agreement shall assume and bear all of its
own respective expenses, costs and fees incurred or assumed by each in the
preparation and execution of this Agreement and compliance herewith, whether or
not the transaction herein provided for shall be consummated.

6.   SURVIVAL OF REPRESENTATIONS AND WARRANTIES.  All representations,
warranties and agreements of each of Extended, the Selling Stockholders and ART
contained herein (including all schedules and exhibits hereto) or in any
document, statement, certificate or other instrument referred to herein or
delivered at the Closing in connection with the transactions contemplated hereby
shall survive the execution and delivery of this Agreement, any investigation by
ART of the Sellers or the Assets, the Closing and the consummation of the
transactions contemplated by this Agreement for two years from the Closing Date.

7.   INDEMNITIES.

     7.1.  INDEMNIFICATION BY THE SELLERS.

     The Sellers shall jointly and severally indemnify ART and its successors
and assigns for any and all damages, claims, losses, liabilities, and expenses,
including without limitation reasonable legal and accounting expenses
(collectively, "Losses"), which may arise out of:  (i) any breach of any
Sellers' covenants and agreements hereunder; (ii) any inaccuracy or
misrepresentation in any representation or warranty of any Seller hereunder, in
each case as such representation or warranty would read if all materiality and
knowledge standards and disclosure schedules were deleted from it, or any
inaccuracy or misrepresentation in any certificate or document delivered in
accordance with the terms of this Agreement by any

                                     -8-

<PAGE>

Seller; (iii) any liabilities of Extended; or (iv) any claim or action 
asserted by any third party arising out of or in connection with any event, 
act or omission relating to any of the Assets occurring prior to the Closing 
Date.  The aggregate liability of the Selling Stockholders under this 
Section 7 shall not exceed the Purchase Price.

     7.2.  INDEMNIFICATION BY ART.  ART shall indemnify and hold harmless the
Sellers from and against any and all Losses which may arise out of:  (i) ART's
breach of any of the covenants and agreements made in this Agreement by ART; or
(ii) any inaccuracy or misrepresentation in any representation or warranty of
ART hereunder, in each case as such representation or warranty would read if all
materiality and knowledge standards and disclosure schedules were deleted from
it, or any inaccuracy or misrepresentation in any certificate or document
delivered in conjunction with this Agreement.

     7.3.  TIME LIMIT ON INDEMNIFICATION.  No claim may be brought under this
Section 7 by either party more than two years after the Closing Date.

8.    COVENANTS.

     8.1.  PREPARATION FOR CLOSING.  Extended, the Selling Stockholders and ART
agree to use their best efforts to maintain the accuracy of their respective
representations and warranties contained in this Agreement until the Closing.

     8.2.  FCC AND OTHER APPROVAL.  The Sellers and ART will use their best
efforts to join in and submit as quickly as possible one or more applications
(the "Applications") to the FCC requesting the FCC's written consent to the
change in control or the transfer, as the case may be, of the Authorizations to
ART or designees of ART. 

     8.3.  FURTHER ASSURANCES.  At any time and from time to time at or after
the Closing, at the request of ART and without further consideration, except as
stated below, the Sellers will execute and deliver such other instruments of
sale, transfer, conveyance, assignment and confirmation and take such action as
ART may reasonably determine is necessary to transfer, convey and assign to ART,
and to confirm ART's title to or interest in the Assets to put ART in actual
possession and operating control of the Assets and to assist ART in exercising
all rights with respect thereto. 

     8.4.  PUBLIC ANNOUNCEMENTS.  Neither Extended or any of the Selling
Stockholders will, at any time, without the prior written consent of ART, make
any announcement, issue any press release or make any statement to any third
party with respect to this Agreement any of the specific matters discussed
between the parties.

     8.5.  NO SOLICITATION BY THE SELLERS.  The Sellers each undertake and agree
that between the date of the execution of this Agreement and the Closing or
termination of this Agreement, none of the Sellers or their respective officers,
directors, partners, representatives

                                     -9-

<PAGE>

and agents will indirectly or directly solicit, encourage or initiate the 
submission of proposals or offers from, or provide any confidential 
information to, or participate in discussions or negotiations or enter into 
any agreement or understanding with, any corporation, partnership, person or 
other entity or group (other than ART or their respective officers, 
employees, directors, representatives and agents) concerning the sale of 
shares of capital stock of Extended, or any merger, combination, sale of 
assets, or similar transactions with respect to Extended or the Assets.  The 
Sellers each agree to immediately cease any discussions or communications 
with any parties conducted prior hereto with respect to any of the foregoing. 
The Sellers each will promptly notify ART if any of them receive any written 
proposals, offers or invitations to discuss any of the foregoing.

     8.6.  AGREEMENT RELATING TO JOINT VENTURE AGREEMENT.  Notwithstanding any
other provision of this Agreement, Extended transfers to ART all of its rights
under Section 1.8(b) and (c) of the Joint Venture Agreement; except that
applications to the FCC for new 38 GHz authorizations in Designated States (as
defined by the Joint Venture Agreement) or modifications to existing
authorizations held by the Partnership shall be made by the Partnership and not
by the Partners.  For this purpose, applications for authorizations to be
awarded by competitive bidding are to be treated as acquisitions of Systems (as
defined in the Joint Venture Agreement) and not as applications.  In that
regard, Extended agrees that the provisions of Section 1.8(b) and (c) of the
Joint Venture Agreement (except as aforesaid) with respect to acquisitions of
Systems (as defined in the Joint Venture Agreement) committed to, now or
hereafter, by ART or ART's affiliates including, without limitation, the
prohibition on acquisitions of Systems in any Existing Market System (as defined
in the Joint Venture Agreement) and the requirement to comply with the
provisions of 1.8(c) with respect to acquisition of interests in Open Systems
(as defined in the Joint Venture Agreement) shall no longer be enforceable by
Extended unless and until this Agreement has terminated without payment of the
Deposit to Extended.  Extended will execute such documents requested by ART to
further reflect the agreement of Extended in this Section 8.6.

     8.7.  CONDUCT OF BUSINESS BY SELLERS.  Sellers covenant that until the
Closing:

          (a)  Sellers will each take all necessary steps requested by ART to
     maintain the Authorizations in good standing with the FCC and will maintain
     its qualifications under all laws, rules and regulations to hold the
     Authorizations and the Partnership Interest;

          (b)  Sellers will comply with all statutes, laws, ordinances, rules
     and regulations applicable to its business;

          (c)  Extended will not enter into or assume any agreement, contract or
     commitment of any kind, which relates to or affects in any way the Assets
     or the Seller's ability to consummate the transactions contemplated hereby;

                                     -10-

<PAGE>

          (d)  Extended will not merge or consolidate with, or agree to merge or
     consolidate with, or purchase substantially all of the assets of, or
     otherwise acquire any business or any corporation, partnership, association
     or other business organization or division thereof;

          (e)  Extended will not dispose of any of the Assets, or incur, or
     permit to be incurred, any Liens with respect to any of the Assets;

          (f)  Sellers will not permit any change to be made in Extended's
     charter documents or by-laws, which relates to or affects in any way the
     Assets or the Seller's ability to consummate the transactions contemplated
     hereby;

          (g)  Sellers will not enter into any agreements or commitments for any
     of 8.7(c) through 8.7(f).

9.   CONDITIONS PRECEDENT TO ART'S OBLIGATIONS.  All obligations of ART under
this Agreement are subject to the fulfillment to the reasonable satisfaction of
ART prior to or at the Closing of each of the following conditions, any of which
may be waived by ART in its sole discretion:

     9.1.  REPRESENTATIONS AND WARRANTIES.  The representations and warranties
made by the Sellers (excluding Sections 3.3, 3.7 and 3.8) in this Agreement
(including all exhibits and schedules hereto), shall be true and correct in all
material respects when made and shall be repeated and shall be true and correct
in all material respects at and as of the Closing Date, and ART shall have
received a certificate dated the date of the Closing signed by the chief
executive officer of Extended to the foregoing effect.

     9.2.  CONSENTS.  All filings with and consents from all federal, state and
local governmental agencies required to consummate the transactions contemplated
by this Agreement shall have been made or received, as applicable.

     9.3.  FCC AUTHORIZATIONS.  Without limiting the generality of Section 9.2,
the FCC shall have authorized the transfer or change of control, as applicable,
of all of the Authorizations by a Final Order (as defined below), without any
conditions or restrictions that materially affect the value of the
Authorizations or operations pursuant to the Authorizations or any conditions or
restrictions materially different than the normal authorizations issued by the
FCC to other 38 GHz license holders at the date of this Agreement.  In the event
that any FCC order approving the transfer of the Authorizations to ART imposes
such conditions, this condition shall not be satisfied until such conditions are
removed or eliminated, and Sellers shall fully cooperate in obtaining the
removal or elimination of such restrictions.  "Final Order" means an action by
the FCC granting its consent to the assignment of a Authorization, with respect
to which no request for stay, petition for rehearing, reconsideration or appeal
is pending, and as to which the time for filing any petition for rehearing,
reconsideration or appeal has expired and with respect to which the time for
agency reconsideration or review taken on its own motion has expired, or in the
event of the filing of such

                                     -11-

<PAGE>

request, petition or appeal, an action which shall have been reaffirmed or 
upheld and with respect to which the time for seeking further administrative 
or judicial review shall have expired. 

     9.4.  PERFORMANCE BY EXTENDED; CERTIFICATE.  Extended shall have performed
and complied with all agreements and conditions required by this Agreement to be
performed or complied with by them prior to or at the Closing, and the chief
executive officer of Extended shall deliver to ART a certificate dated the
Closing Date, to such effect.

     9.5.  ABSENCE OF ERRORS AND OMISSIONS.  ART shall not have discovered any
material error, misstatement or omission in any of the representations or
warranties, or any material failure to perform or satisfy any covenants or
conditions required by this Agreement to be performed or satisfied by the
Sellers on or prior to the date of Closing.

     9.6.  OPINIONS OF COUNSEL FOR EXTENDED.  ART shall have received a 
favorable opinion addressed to it and dated the Closing Date of counsel for
Extended in form and substance acceptable to ART and its counsel.

     9.7.  ABSENCE OF LITIGATION.  No action or proceeding shall have been
instituted or threatened prior to or at the Closing Date before any court or
governmental body or authority pertaining to the transactions contemplated
hereby, the result of which could prevent or make illegal the consummation of
such transactions or which could be materially adverse to the Assets.

     9.8.  UCC SEARCHES.  ART shall have obtained Uniform Commercial Code
(including fixture filings) and state and federal tax and judgment lien searches
against Extended all dated within 5 days of the Closing Date.

     9.9.  RELEASE OF LIENS.  All of the Assets shall be free and clear of all
Liens and ART shall have received evidence of the release of all liens and the
termination of all financing statements, if any, as may be reasonably requested
by ART.

     9.10. EQUITY SALE.  ART shall have consummated a sale of equity securities
with aggregate net proceeds to ART of at least $30 million.

10.  CONDITIONS PRECEDENT TO THE OBLIGATIONS OF THE SELLERS.  All obligations of
the Sellers under this Agreement are subject to the fulfillment to the
reasonable satisfaction of Extended, prior to or at the Closing, of each of the
following conditions, any of which may be waived by Extended in its sole
discretion:

     10.1.  REPRESENTATIONS AND WARRANTIES.  The representations and warranties
made by ART in this Agreement shall be true and correct in all material respects
when made and shall be repeated and shall be true and correct in all material
respects at and as of the Closing Date, except as specifically provided for
herein, and the Sellers shall have received a certificate dated the date of
Closing signed by an officer of ART, to the foregoing effect.

                                     -12-

<PAGE>

     10.2.  GOVERNMENT CONSENTS.  All filings with and consents from all
federal, state and local governmental agencies required to consummate the
transactions contemplated hereby shall have been obtained at or prior to the
Closing.

     10.3.  PERFORMANCE OF ART.  ART shall have performed and complied with all
agreements and conditions required by this Agreement to be performed or complied
with by it prior to or at the Closing and an officer of ART shall deliver a
certificate or certificates to the Sellers to such effect.

     10.4.  ABSENCE OF LITIGATION.  No action or proceeding shall have been
instituted or threatened prior to or at the Closing Date before any court or
governmental body or authority pertaining to the transactions contemplated
hereby, the result of which could prevent or make illegal the consummation of
such transactions.

     10.5.  PURCHASE PRICE.  The Purchase Price shall have been delivered to
Extended.

11.  TERMINATION.  This Agreement may be terminated by the parties as set forth
in this Section 11:

          (a)  at any time by the mutual written consent of Extended and ART;

          (b)   by ART at any time after June 30, 1997, if the conditions set
     forth in Section 9 shall not have been complied with or performed and such
     noncompliance or nonperformance shall not have been cured or eliminated by
     the Sellers by such time;

          (c)   by the Sellers at any time after June 30, 1997 (the "Seller
     Date"), if the conditions set forth in Section 10 hereof shall not have
     been complied with or performed and such noncompliance or nonperformance
     shall not have been cured or eliminated by ART by such time; provided that
     if prior to the Seller Date, the FCC has issued an order approving the
     transfer or change in control, as applicable, of the Authorizations, which
     is not a Final Order, to ART, ART may extend the Seller Date until June 30,
     1998 by notice to Extended;

          (d)  by the Sellers on the one hand, or by ART, on the other, if there
     shall have been a breach of any material representation, warranty, covenant
     or agreement on the part of the others set forth or contemplated by this
     Agreement, which breach cannot be cured prior to the Closing;

          (e)  by the Sellers at any time after December 31, 1996, if the sale
     of securities that would satisfy the condition set forth in Section 9.11 is
     not consummated prior to December 31, 1996.

                                     -13-

<PAGE>

provided, however, that the terminating party may not terminate its obligations
under this Agreement if such terminating party has breached this Agreement in
any material respect.

     Notwithstanding any termination of this Agreement pursuant to this
Section 11, the provisions of Section 7, and, in consideration of the payment of
the Deposit to Extended, if paid, the provisions of Section 8.6 hereof, shall
remain in full force and effect.  The parties agree that the payment of the
non-refundable Deposit does not constitute a penalty or damages.

12.  ENTIRE AGREEMENT; ASSIGNABILITY.  This Agreement, together with the
schedules and exhibits hereto, constitutes the entire agreement between the
parties hereto pertaining to the subject matter hereof and supersedes all prior
and contemporaneous agreements, understandings, negotiations and discussions,
whether oral or written, of the parties, and there are no warranties,
representations or other agreements between the parties in connection with the
subject matter hereof except as specifically set forth herein.  This Agreement
may not be assigned by any of the Sellers without the prior written consent of
ART and any such attempted assignment shall be null and void.

13.  AMENDMENT.  This Agreement may be amended by the parties hereto at any
time, but only by an instrument in writing duly executed and delivered on behalf
of each of the parties hereto.

14.  HEADINGS.  Section headings are not to be considered part of this Agreement
and are included solely for convenience and are not intended to be full or
accurate descriptions of the contents thereof.  References to Sections are to
portions of this Agreement unless the context requires otherwise.

15.  EXHIBITS, ETC.  Exhibits, schedules and other documents referred to in this
Agreement are an integral part of this Agreement. 

16.  SUCCESSORS AND ASSIGNS.  All of the terms and provisions of this Agreement
shall be binding upon and shall inure to the benefit of the parties hereto and
their respective transferees, successors and assigns.

17.  NOTICES, ETC.  All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given on the
date of delivery if delivered or mailed, first-class postage prepaid,

          (a)    if to Extended, to:

                    Extended Communications, Inc.
                    22904 Northeast 19th Drive
                    Redmond, Washington, 98053
                    Attention: Thomas A. Marinkovich

                                     -14-

<PAGE>

          (b)    if to ART to:

                    Advanced Radio Technologies Corporation
                    500 108th Avenue, N.E., Suite 2600
                    Bellevue, Washington, 98004
                    Attention:  W. Theodore Pierson, Jr. and
                              Thomas A. Grina
 
          with a copy to:

                    Ropes & Gray
                    One International Place
                    Boston, Massachusetts, 02110-2624
                    Attention:  Mary E. Weber, Esq.

18.  GOVERNING LAW.  This Agreement and the rights and obligations of the
parties hereto arising out of this Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware without regard to the
internal conflict of law provisions thereof.

19.  SEVERABILITY.  The provisions of this Agreement are severable, and if any
one or more provisions are deemed illegal or unenforceable, the remaining
provisions shall remain in full force and effect.

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

         [The remainder of this page has been intentionally left blank]


                                     -15-
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as
of the day and year first above written.


                              EXTENDED COMMUNICATIONS, INC.


                              By: ________________________________
                                    Name:
                                    Title:

                              ADVANCED RADIO TECHNOLOGIES
                                CORPORATION


                              By: ________________________________
                                    Name:
                                    Title:


                              SELLING STOCKHOLDERS



                              ____________________________________
                              Name:  Thomas A. Marinkovich


                              ____________________________________
                              Name:  Teresa E. Marinkovich


                              ____________________________________
                              Name:  Mark T. Marinkovich


                              ____________________________________
                              Name:  James A. Marinkovich

                                     -16-



<PAGE>

                                                                EXHIBIT 10-8(f)

                              MANAGEMENT AGREEMENT


     THIS MANAGEMENT AGREEMENT ("Agreement") between ART West Partnership ("Art
West," or "Licensee"), a general partnership formed pursuant to the laws of the
State of Delaware and Advanced Radio Technologies Corporation ("ART" or
"Manager"), a Delaware corporation, is entered into as of the dates set forth
next to the signatures below and is effective as of June 1, 1996.

     WHEREAS, Licensee has acquired, or has the right to acquire, certain
Federal Communications Commission ("FCC") licenses and construction permits
(collectively with any other licenses and permits which may be held by Licensee
in the future, the "Licenses") for 38 GHz frequency radio systems (collectively
with any other 38 GHz frequency radio systems for which Licensee may be licensed
or permitted in the future, the "Systems") in various locations ("Markets"); and

     WHEREAS, Licensee and Manager desire to enter into an exclusive agreement
for the construction, operation, and management by Manager of the Systems,
including without limitation those listed in Exhibit A hereto, consistent with
Licensee's obligations in connection with the Licenses under all of the Federal
and state laws, rules, and regulations;

     NOW, THEREFORE, in consideration of the premises and covenants hereinafter
set forth, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties, intending to be
legally bound, hereby agree as follows:

     1.  TERM OF AGREEMENT AND TERMINATION.  

          (a)   This Agreement becomes effective on the date set forth above. 
Unless it is terminated earlier pursuant to the  provisions of this Section, 
the term of this Agreement ("Term") shall extend for ten years and shall 
renew for additional ten year terms, if agreed to by the parties.

          (b)   This Agreement shall terminate thirty days after notification 
of a material breach of the Agreement by the non-breaching party to the 
breaching party, if such breach is not cured within the thirty-day period 
following notification, provided that if the default or breach shall be of 
such nature that it cannot reasonably be cured with due diligence within said 
thirty-day period, the time in which to cure the same shall be extended for 
such period as may be necessary to cure the same with due diligence.  If 
Manager materially discriminates against licenses held by Licensee in favor 
of licenses in Manager's own name or managed by Manager with respect to 
operations or marketing, then this Agreement shall terminate thirty days 
after Licensee reasonably determines that Manager has so discriminated and so 
notifies Manager, if such discrimination is not cured within the thirty-day 
period following such notification, provided that if such discrimination 
shall be of such nature that it cannot reasonably be cured 

<PAGE>

with due diligence within said thirty-day period, the time in which to cure 
the same shall be extended for such period as may be necessary to cure the 
same with due diligence.

          (c)  This Agreement shall terminate with respect to any License 
acquired by ART.

     2.  SYSTEM CONSTRUCTION AND MANAGEMENT; EQUIPMENT LEASE.  Licensee 
hereby grants Manager the exclusive right to manage the Systems under the 
following terms and conditions; provided that, Licensee may solicit and 
contract with customers for the Systems.  Subject to Licensee's supervision 
and control, Manager will use its reasonable best efforts to undertake the 
design, construction, installation, marketing, sales and operations of the 
Systems. Subject to the general authority of the Licensee and Manager's 
obligation not to discriminate against Licensee and in favor of licenses 
issued in its name in its marketing, sales, purchases or operations, these 
efforts will include, but are not limited to, the following:

          (a)  The preparation of the design for the Systems and the planning 
and design thereof;

          (b)  The leasing of assets or rights to use assets (collectively 
the "Equipment") necessary for the planning design, construction and 
operation of the Systems, including any expansion, modification or reduction 
thereof. 

          (c)  Hiring and supervision of the personnel necessary to construct 
and operate the Systems;

          (d)  Creating services (including prices for such services at fair 
market rates) for the Systems;

          (e)  The construction of the Systems (all rights with respect to 
the product of such construction shall be included within the definition of 
"Equipment"); 

          (f)  The development and implementation of marketing programs;

          (g)  Making reasonable efforts consistent with usual industry 
practices to obtain sales and otherwise provide for loading of the Systems;

          (h)  The billing and collection of fees, charges or other 
compensation due to the Systems, and the payment of all expenses and fees 
incurred or payable by the Systems;

          (i)  The maintenance of the Systems according to standards 
consistent with FCC rules and regulations, and the provision of necessary 
repairs and replacements;

                                     -2-

<PAGE>

          (j)  In conjunction with Subsection (k) below and applicable FCC 
rules and regulations, coordinating with Licensee the preparation, execution, 
delivery and filing of applications and other instruments to comply with 
rules, regulations and orders of any Federal, state, county, municipal or 
other governmental authority having jurisdiction over Licensee or the Systems;

          (k)  Appropriate office record keeping, bookkeeping and internal 
accounting services and arranging for and overseeing outside accounting 
services;

          (l)  In the event Systems construction proves unfeasible, promptly 
identifying any License modifications which would permit Systems 
construction, including, but not limited to, site changes, and preparation 
and submission to Licensee of any associated FCC documentation to Licensee 
for its review. Licensee agrees it will complete its review and promptly 
submit any requests for modifications of its License which may be needed to 
make construction feasible, or any filings or appeals which are necessary to 
extend the period for construction under the FCC's rules.  Such requests 
would include, but not be limited to, applications to the FCC for special 
temporary authority; and

          (m)  Generally, managing the day-to-day operations of the Systems 
and doing or assisting with any and all other acts or executing such other 
agreements, documents or instruments, as are consistent with FCC rules and 
regulations and, in the good faith judgment of Manager, are necessary to 
carry out the development, construction and operation of the Systems, whether 
or not specifically enumerated herein.

          (n)  All Equipment shall be acquired and constructed by Manager and 
shall be the property of Manager.  The Equipment shall be leased to Licensee 
for the consideration described in Section 4 hereof during the term of this 
Agreement.  Such lease shall terminate simultaneously with the termination of 
this Agreement for any reason.  Upon such termination, the Equipment shall 
remain the property of the Manager, and Manager may take immediate possession 
thereof.
     
     3.  REGULATORY COMPLIANCE.  The parties agree that Licensee is in sole 
control of the Licenses and that it is required by FCC regulations to be in 
sole control so long as it is the Licensee.  The Manager acknowledges and 
agrees that Licensee has ultimate control over all decisions affecting 
System, notwithstanding any other provision of this Agreement.  The parties 
agree to cooperate with each other in complying with all applicable Federal, 
state and local regulations.  This cooperation includes, but is not limited 
to, the following:

          (a)  Each System customer will be advised that service is provided 
over facilities controlled by Licensee;

          (b)  Manager agrees to use its reasonable best efforts to comply 
with all FCC timetables concerning construction and operation and to take 
such steps as may be needed to 

                                      -3-

<PAGE>

preserve any licenses that may be granted by the FCC. Manager expressly 
acknowledges that the Systems must be constructed by dates to be determined 
by FCC;

          (c)  Neither Manager nor Licensee shall represent themselves as the 
legal agents or one another; and

          (d)  Licensee shall, with the cooperation and assistance of 
Manager, fully comply with all regulations necessary to keep the License in 
full force and effect.  Licensee shall prepare and submit to the FCC and any 
other relevant Federal, state or local agency all reports, applications, 
renewals, or other filings or documents that may be required to do this, 
provided that Manager shall timely advise Licensee of all such requirements 
and shall provide any assistance required by Licensee in fulfilling this 
obligation.

     4.  LICENSE FEES.  During the term of this Agreement, Manager shall pay 
Licensee ten percent (10%) of all Recurring Revenue (as defined below) 
relating to the operation of any of the Licenses (each such payment made from 
time to time is referred to as a "Licensee Payment").  As Manager's 
compensation for managing the Systems pursuant hereto and as lease payments 
for the Equipment pursuant to Section 2(b) hereof, Manager shall retain all 
revenue relating to the Licenses other than the Licensee Payments.  Each 
Licensee Payment, for each calendar quarter, shall be distributed to Licensee 
within sixty days of the end of such quarter.  "Recurring Revenue" shall mean 
all recurring revenue from customers for the use of the Licenses, including 
revenue received from customers relating to equipment provided, leased or 
sold by Manager to customers and used by customers in connection with 
Licenses, but excluding reasonable installation and other one-time charges.

     5.  NOTICE.  All notices and other communications shall be in writing 
and shall be deemed given the same day if delivered personally or sent by 
telecopy or the next business day if sent by express mail or courier 
(overnight delivery), or five (5) business days later if sent by registered 
mail or certified mail, return receipt requested, postage prepaid, to the 
parties at the following addresses or at such other address for a party as 
shall be specified by like notice, provided that notice of change of address 
shall be effective only upon receipt thereof:

          (a)  If to Licensee, to:

               Art West Partnership
               500 108th Avenue, N.E. Suite 2600
               Bellevue, Washington 98004
               Attn:  Thomas A. Grina
                      Tom Marinkovich

               With a copy to:

               W. Theodore Pierson, Jr.

                                      -4-

<PAGE>
               Executive Vice President and General Counsel
               1200 Nineteenth St., N.W., Suite 607
               Washington, D.C.  20036



          (b)  If to Manager, to

               Advanced Radio Technologies Corporation
               500 108th Avenue, N.E., Suite 2600
               Bellevue, Washington 98004
               Attn:  Thomas A. Grina

               With a copy to:

               W. Theodore Pierson, Jr.
               Executive Vice President and General Counsel
               1200 Nineteenth St., N.W., Suite 607
               Washington, D.C.  20036


     6.  REPRESENTATIONS AND WARRANTIES.

          (a)  Licensee represents and warrants that it is either (i) the 
licensee or permit holder with respect to the Licenses listed in Exhibit A or 
(ii) has the right to acquire the Licenses listed in Exhibit A without any 
conditions other than the necessary FCC approvals, and Licensee represents 
and warrants that it is duly qualified under all laws, rules and regulations 
to hold such Licenses.  Licensee further represents and warrants that it is 
the sole owner and real party in interest in the Licenses and that no other 
party has an interest of any kind.  Licensee further represents that it has 
the requisite authority and/or capacity, as applicable, to perform its 
undertakings pursuant to this Agreement.

          (b)  Licensee represents and warrants that it will take all 
necessary steps, to maintain the Licenses with the FCC in good standing.

          (c)  Each of the parties hereto represents and warrants that each 
shall take such steps and execute such documents as may be necessary from 
time to time to effectuate the terms and conditions of this Agreement.

          (d)  Manager represents and warrants that it is a corporation duly 
authorized and in good standing under the laws of the State of Delaware and 
has the requisite authority to perform its undertakings pursuant to this 
Agreement.

                                      -5-

<PAGE>

          (e)  Manager represents and warrants that it is familiar with the 
applicable rules and regulations of the FCC and that it is aware of no 
impediment to the performance of its undertakings hereunder.  Manager 
represents and warrants that it will assist Licensee in taking all necessary 
steps to maintain the license in good standing.

          (f)  Manager represents and warrants that it will exercise its best 
efforts to perform its duties according to industry standards and practices.

          (g)  Manager represents and warrants that it will use its 
reasonable best efforts to complete construction of Systems within the 
construction period specified by the FCC and will assist the Licensee in 
timely filing FCC Form 404 or its replacement, and all other papers necessary 
to obtain a coverage license for Systems.

          (h)  Manager represents and warrants that it will utilize Licenses 
held by Licensee managed hereunder before any other license which Manager may 
own or manage in the same market as Licenses of Licensee.

     7.  INDEMNIFICATION AND INSURANCE.

          (a)  Manager agrees to indemnify and hold harmless Licensee 
harmless from and against all liabilities, obligations, claims, damages, 
penalties, causes of action, costs and expenses (including, but not limited 
to, reasonable attorney's fees and costs), imposed upon or incurred by, or 
asserted against Licensee, that arise as a result of the negligence or 
misconduct of Manager or Manager's employees or agents.

          (b)  Licensee agrees to indemnify and hold harmless Manager from 
and against all liabilities, obligations, claims, damages, penalties, causes 
of action, costs and expenses (including, without limitation, reasonable 
attorney's fees and costs), imposed upon or incurred by or asserted against 
Manager that arise as a result of the gross negligence or willful misconduct 
of Licensee or Licensee's employees or agents.

          (c)  Liability insurance for the Systems shall be maintained by 
Manager as follows:

               (i)  Comprehensive general liability policies of insurance in 
standard form protecting Manager and Licensee and their agents against any 
liability occasioned by accident or disaster in connection with the operation 
of the Systems contemplated this Agreement.  The minimum limits of such 
liability insurance shall be one million dollars ($1,000,000) for injury or 
death for one or more persons or with respect to damage to property; and.

               (ii)  Such other insurance as Manager and Licensee deem 
necessary with respect to the operation of the Systems.

                                      -6-

<PAGE>

     8.  ASSIGNABILITY; SUCCESSORS AND ASSIGNS.

          (a)  Subject to the prior consent of the Manager, which consent 
shall not be unreasonably withheld or delayed, and provided it does not 
violate any of the other terms and conditions of this Agreement or any 
applicable rule and/or regulations of the FCC, Licensee may only assign this 
Agreement to a purchaser of the Systems, provided such purchaser expressly 
assumes in a writing reasonably acceptable to Manager all of the obligations 
of the Licensee hereunder and otherwise agrees to comply with the terms and 
conditions of this Agreement.  Such assignment shall be effective only upon 
thirty days notification from the Licensee, satisfaction of the above said 
conditions and, to the extent applicable, consent of the FCC to the transfer 
of the Licenses. Any such assignment shall not relieve the Licensee of its 
obligations hereunder.

          (b)  Manager may assign its right to manage the Systems hereunder 
to another party, provided such assignee of Manager has experience in the 
management of 38 GHz systems or other telecommunications facilities or, 
alternatively, is an affiliate of the Manager or employs either personnel of 
the Manager or other persons who have experience in the management of 38 GHz 
systems or other telecommunications facilities.  Manager may assign its 
rights to a wholly-owned subsidiary.  Such assignment shall be effective only 
upon thirty days notice to the Licensee by the Manager.  Manager may employ 
such subcontractors or agents as it deems necessary in the performance of its 
duties hereunder.

          (c)  This Agreement shall be binding upon and inure to the benefit 
of the parties hereto, and their respective heirs, representatives, successor 
and permissible assigns.

     9.  SEVERABILITY.  In the event that any provision herein is held to 
invalid, void, or illegal by any Federal, state or local court, or any 
regulatory agency, the remaining provisions of the Agreement shall remain in 
full force and effect and this Agreement shall be reasonably construed so as 
to preserve the original intent of the parties hereto insofar as practicable. 
 In the event that any provision herein is deemed to be invalid, void, in 
violation of any agency rules, or otherwise unlawful, the parties shall use 
their respective best efforts to amend the offending provisions to bring them 
into legal compliance with minimum disruption to the expectations of the 
parties as set forth in this Agreement.

     10.  COUNTERPARTS.  This agreement may be executed in any number of 
counterparts with the same as if the signature of each counterpart were in 
the same instrument.

     11.  NO WAIVER OF RIGHTS; AMENDMENT.  The failure of either party to 
insist, in any one or more instances, upon the performance of any of the 
terms, covenants or conditions herein, or to exercise any right hereunder, 
shall not be construed as a waiver or relinquishment of the future 
performance of any such term, covenant or condition, or the future exercise 
of such right, but the obligation of the other party with respect to such 
future 

                                      -7-

<PAGE>

performance shall continue in full force and effect.  This Agreement may only 
be amended, modified or changed by a writing signed by all parties hereto.

     12.  WARRANTY.  THERE ARE NO EXPRESS OR IMPLIED WARRANTIES, INCLUDING, 
WITHOUT LIMITATION, IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A 
PARTICULAR PURPOSE, RESPECTING THIS AGREEMENT OR THE SERVICE PROVIDED 
HEREUNDER.

     13.  ENTIRE AGREEMENT.  This Agreement supersedes any other agreements 
between the parties, including the Services Agreement ("Services Agreement") 
effective as of October 1, 1994 between the parties hereto, whether oral or 
written, relating to the matter contemplated herein, and constitutes the 
entire agreement by and between the parties, there being no other agreements 
or understandings between the parties as expressly set forth herein.  The 
parties agree the Services Agreement is hereby terminated and will be of no 
further force or effect.

     14.  GOVERNING LAW/PROCEDURE.  This Agreement will be governed by the 
laws of the State of Delaware; provided that any dispute under this Agreement 
will be resolved by arbitration under the Commercial Arbitration rules of the 
American Arbitration Association, using one arbitrator.


                                      -8-

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as 
of the date first written above.

MANAGER:                           LICENSEE:

Advanced Radio Technologies        ART West Partnership
Corporation                        By:  Extended Communications, Inc.,
                                   a partner of ART West Partnership


By:____________________________    By:_____________________________

Printed Name:___________________   Printed Name:____________________

Title:___________________________  Title:___________________________

Dated:__________________________   Dated:__________________________


                                   By: Advanced Radio Technologies Corporation,
                                   a partner of ART West Partnership


                                   By:__________________________________

                                   Printed Name:__________________________

                                   Title:_________________________________

                                   Date:_________________________________

                                      -9-


<PAGE>

                                                               EXHIBIT 10-9(e)

                                  AMENDMENT TO
                               SERVICES AGREEMENT

     THIS AMENDMENT TO SERVICES AGREEMENT (this "AMENDMENT"), is entered into 
this           day of June, 1996, by and between DCT COMMUNICATIONS, INC., a 
California corporation ("DCT"), and ADVANCED RADIO TECHNOLOGIES CORPORATION, 
a Delaware corporation ("ART").

     In consideration of the premises and mutual representations, warranties, 
covenants and promises herein contained, the parties hereto agree as follows:

     1.   AMENDMENT TO SERVICES AGREEMENT.  The Services Agreement (the 
"SERVICES AGREEMENT"), effective as of September 1, 1994, between DCT and ART 
is amended as follows:

          a.   In Section 1(a) the phrase "five years" is changed to "through 
               December 31, 1998."

          b.   A new section (c) is added to Section 1 as follows:

               "(c)  This Agreement shall terminate with respect to any
               Authorization upon the acquisition of such Authorization by
               Manager."

          c.   A new Section (d) is added to Section 1 as follows:

               "(d)  This Agreement may be terminated by Licensee upon 180 days'
               prior written notice to Manager at any time after the termination
               pursuant to its terms of the Asset Purchase Agreement (the
               "Acquisition Agreement") dated as of the date hereof between the
               parties hereto."

          d.   In Section 2 (i) the word "Appendix" in the first sentence is
               changed to "Exhibit" and (ii) the third sentence (beginning "In
               order to avoid the appearance of conflict...") is deleted.

          e.   In subsection (g) of Section 3, the number "5" is substituted for
               the number "10."

          f.   A new Section 4A is added after Section 4 as follows:

               "4A   At any time after December 31, 1997, Licensee may, with
               prior written notice to Manager, elect to market to third-
               parties, and to construct and operate systems for such purpose;
               provided that if Licensee so elects, Manager shall not be
               obligated in any way to 


<PAGE>
               construct, but may construct, additional
               systems.  Licensee and Manager will coordinate all construction
               after such election to ensure neither party constructs systems
               that interfere with then existing systems.  After any such
               election, Manager will continue to maintain sufficient
               construction links and traffic levels to satisfy the FCC
               construction requirements in effect at the time of such election
               except for any customer of ART that becomes a customer of DCT.

          g.   In Section 6, the number "45" is changed to "15" and the
               parenthetical phrase beginning with "calculated" and ending with
               "equipment" is deleted.

          h.   In Section 15, everything after "District of Columbia" is
               deleted.

          i.   Three new sentences are added to the end of Section 6 as follows:

               "Beginning with the later of January 1, 1998 and the first full
               month following the termination of the Acquisition Agreement
               pursuant to its terms, in lieu of the cash gross revenue sharing
               arrangement described in the preceding sentence, ART shall be
               entitled to keep all of the revenue generated with respect to the
               Systems except for the "Licensee Fee," which will be paid to
               Licensee every calendar quarter within thirty days of the end of
               such quarter.  The "Licensee Fee" for each month in a quarter
               shall be the sum of (a) $25 multiplied by the number of DS-1
               circuits operated by Manager utilizing the Authorizations during
               such month and (b) $200 multiplied by the number of DS-3 circuits
               operated by Manager utilizing the Authorizations during such
               month; provided that the Licensee Fee shall not in any event be
               less than the Licensee Fee for the first month following the
               termination of the Acquisition Agreement.  Notwithstanding the
               provisions of this Section 6, Licensee will not be entitled to
               any portion of gross revenue or any Licensee Fee for the period
               beginning July 1, 1996 and ending December 31, 1996.

          i.   In Exhibit A, markets 4, 5, 6, 10, 12, 15 and 20 are deleted and
               the markets of Charleston, SC, Dayton, OH and Mobile, AL are
               added.

     2.   RATIFICATION OF SERVICES AGREEMENT; ENTIRE AGREEMENT.  The Services
Agreement, as amended hereby, is ratified but no existing breach thereof, if
any, is waived or excused.  The Services Agreement, as amended hereby,
constitutes the entire agreement among the parties relating to the subject
matter hereof and supersedes all other prior agreements and understandings, oral
or written, of the parties including without limitation the Superseded
Agreements (as defined in the Acquisition Agreement).

                                -2-

<PAGE>
     IN WITNESS WHEREOF, the parties have caused this Amendment to be duly
executed on the day and year first above written.

                              DCT COMMUNICATIONS, INC.


                              By:
                                 ------------------------------
                              Name:  Martin A. Rubin
                              Title:  President


                              ADVANCED RADIO TECHNOLOGIES
                              CORPORATION

                              By:
                                 --------------------------------
                              Name:  W. Theodore Pierson, Jr.
                              Title:  Executive Vice President


                              Title:
                                    -----------------------------

                                      -3-

 

<PAGE>

                                                               EXHIBIT 10-12(c)

                        TELECOM ASSET PURCHASE AGREEMENT


     This Asset Purchase Agreement made as of June __, 1996 (the "Agreement")
among Advanced Radio Technologies Corporation, a Delaware corporation, ("ART"),
Telecom One, Inc. a Delaware corporation ("Telecom"), William Rodi, Gordon
Hutchins, Jr. (Mr. Rodi and Mr. Hutchins are referred to herein as the "Selling
Stockholders" and together with Telecom, the "Sellers").

     WHEREAS, ART wishes to purchase, and Telecom wishes to sell, certain
assets, property and rights of Telecom, listed in Section 1.1 hereof, and
defined as the "Assets" therein, in exchange for the consideration described in
Section 1.4 hereof (the "Transaction").

      NOW, THEREFORE, in consideration of the premises and the respective
covenants and representations and warranties herein contained, the parties
hereto agree as follows:

1.   SALE OF ASSETS.

     1.1.   SALE OF ASSETS.  Subject to and upon the terms and conditions of
this Agreement, Telecom agrees to sell and transfer to ART and ART agrees to
acquire from Telecom, free and clear of any pledge, lien, options, warrants,
security interest, mortgage claim, charge, liability, right of first refusal or
other encumbrance of any kind whatsoever (the "Liens"), at the Closing (defined
below) all of Telecom's right, title and interest in, to and under the following
assets (the "Assets"):

          all rights and incidents of interest in and to the 38 GHz radio
          authorizations granted by the FCC listed on Schedule 1.1 hereto (the
          "Authorizations") and all other licenses, permits, authorizations and
          approvals from all Federal, state, municipal, county, local and any
          other governmental or quasi governmental department, commission,
          board, bureau, agency, court or other instrumentality (collectively,
          the "Governmental Authorities") with respect to the foregoing.

     1.2.   NO ASSUMPTION OF ANY LIABILITIES.  ART will not assume, satisfy or
perform any of the debts, liabilities, obligations or commitments of Telecom.
Telecom will retain all such debts, liabilities, obligations and commitments.

     1.3.   ADVANCE PAYMENT.  ART shall pay to Telecom, upon the execution of
this Agreement by each party, twenty-two thousand three hundred and
forty-seven dollars ($22,347) as an advance payment under this Agreement
(together with accrued interest, the "Advance Payment").  If the Closing
occurs, the Advance Payment shall become the exclusive property of Telecom and
the amount of the Advance Payment shall be credited against the Closing Payment
(as hereinafter defined).  If the Closing does not occur because of ART's
breach of its obligations herein, Telecom shall retain the Advance Payment as
complete


<PAGE>

satisfaction of any damages hereunder.  If the Closing does not occur for any
other reason, the Advance Payment shall be retained by Telecom and offset
payments owed from time to time by ART to Telecom under the Management Agreement
(as herein defined) up to $22,347.

     1.4.   DETERMINATION OF THE CONSIDERATION.  The Purchase Price that ART
shall pay for the Assets and the other agreements of the Sellers herein is one
hundred eleven thousand seven hundred thirty-five dollars ($111,735.00) (the
"Purchase Price").

     1.5.   RIGHT OF FIRST REFUSAL.  In addition to its purchase of the
Authorization hereunder, ART shall have a right of first refusal with resect to
any and all future 38 GHz authorizations granted by the FCC to Telecom or any of
the Selling Stockholders, (the "Future Licenses")  including without limitation
the pending applications filed in the name of Telecom and listed on Schedule 1.5
("Pending Applications") whether issued in the name of Telecom or any of its
present or future affiliates. Should Telecom at any time after the date hereof,
receive a bona fide offer to purchase, manage or lease Telecom's interest, or
any portion thereof, directly or indirectly, in and to the Future Licenses, on
terms and conditions acceptable to Telecom, Telecom shall refrain from accepting
such offer until Telecom has given ART written notice of such offer, together
with a true, correct and complete copy of such offer, and has afforded ART
twenty-one business days following ART's receipt of such notice in which to
review and consider the same.  ART shall have a right of first refusal as to the
purchase, management or lease of Telecom's interest in and to the Future
Licenses on substantially identical terms and conditions stated in such offer,
except as otherwise provided below, and except that, if the proposed price to be
paid by such other party consist of assets, services or rights, the purchase
price shall be the fair market value of the assets, services or rights offered. 
Such right may be exercised by ART by delivering to Telecom, prior to the
twenty-first business day following ART's receipt of Telecom's notice of said
bona fide offer, unequivocal written notice of ART's election to exercise such
right to purchase, manage or lease.  The closing of the transaction resulting
from ART's exercise of ART's right of first refusal shall take place at a
location mutually satisfactory to Telecom and ART at no earlier than thirty days
following ART's exercise of this right of first refusal, subject to the receipt
of a Final Order and as soon as practicable thereafter.  If ART fails or
declines to exercise ART's right of first refusal herein provided, then Telecom
may sell or lease the Future Licenses on the terms of said bona fide offer.

2.   CLOSING.

     2.1.   The closing of the Transaction (the "Closing") shall take place on
such date and at such time within 30 days of the satisfaction of the conditions
contained in Sections 9 and 10 as mutually agreed by the parties (the "Closing
Date") (i) at the offices of Ropes & Gray, One International Place, Boston,
Massachusetts 02110 or (ii) at such other place and time as the parties agree.


                                      -2-


<PAGE>

     2.2.   DELIVERIES BY THE COMPANY AT CLOSING.  At Closing, the Sellers shall
deliver to ART:

            (a)  any Bills of Sale or other instruments of assignment reasonably
     required or requested by ART to transfer, convey and assign the Assets to
     ART;

            (b)  updated Schedules to this Agreement;

            (c)  certified copies of resolutions of the shareholders and the
     board of directors of Telecom authorizing Telecom to enter into and
     perform its obligations under this Agreement;

            (d)  a copy of the charter documents of Telecom certified by the
     appropriate public official and a copy of the by-laws of Telecom certified
     by its Secretary;

            (e)  all such other documents and instruments as ART or its counsel
     shall reasonably request to consummate or evidence the transactions
     contemplated hereby; and

            (f)  any tax clearance certificates or other similar certificates.

     2.3.   DELIVERIES BY ART AT CLOSING.  At Closing, ART shall deliver to
Telecom the Purchase Price in cash or by certified check or wire transfer; and
such documents and instruments as Telecom or its counsel shall reasonably
request to consummate or evidence the transactions contemplated hereby.

     2.4.   CERTIFICATIONS; OPINIONS.  At Closing ART and Telecom shall deliver
the certificates, opinion of counsel and other documents described in Sections 9
and 10 hereof unless waived.

     2.5.   CONSENTS.  At Closing, Telecom shall deliver evidence satisfactory
to ART that the Final Order required pursuant to Section 9.3 has been granted by
the FCC.

     2.6.   FORM OF DOCUMENTS AND INSTRUMENTS.  All of the documents and
instruments delivered at Closing shall be in form and substance, and shall be
executed and delivered in a manner, reasonably satisfactory to the parties'
respective counsel.

3.   REPRESENTATIONS AND WARRANTIES OF TELECOM AND THE SELLING STOCKHOLDERS
Telecom and each Selling Stockholder jointly and severally represent and warrant
to ART as follows:

     3.1.   ENTITY STATUS.  Telecom is a corporation duly organized, validly
existing and in good standing in the state of Delaware.  Telecom has full power
and authority to carry on its business as and where now conducted, and to own or
lease and to operate its properties and


                                      -3-


<PAGE>

assets where such properties and assets are now owned, leased or operated by
it and where such business is now conducted by it.  Telecom is qualified to
do business and is in good standing in each of the jurisdictions in which the
nature of its business or the property owned or leased by it make such
qualification necessary. Telecom has delivered to ART complete and correct
copies of any organizational, by-laws or charter documents applicable to it,
each as amended and in effect on the date hereof.  The Selling Stockholders
own 100% of the outstanding capital stock of Telecom, and there are no
outstanding subscriptions, options, warrants or other rights convertible into
or exercisable for, or any agreements to issue, capital stock of Telecom.

     3.2.   AUTHORITY FOR AGREEMENT; CONFLICTS.

            (a)  Telecom and each of the Selling Stockholders have all necessary
     power and authority, corporate or otherwise, to enter into, execute and
     deliver this Agreement, the Telecom Management Agreement (the "Management
     Agreement") entered into between ART and Telecom dated the date hereof and
     the other documents to be delivered by Sellers at the Closing (the
     Management Agreement and such other documents are collectively the "Seller
     Documents") and to perform fully his or its obligations hereunder and the
     transactions contemplated hereby and thereby.  The execution, delivery and
     performance of this Agreement and the applicable Seller Documents by
     Telecom has been duly authorized by all necessary corporate action.

            (b)  Each of this Agreement and the Management Agreement has been,
     and the other Seller Documents, at the Closing, will have been, duly and
     validly executed and delivered by Telecom and each Selling Stockholder and
     each of this Agreement and the Management Agreement constitutes, and the
     other Seller Documents will constitute, the legal, valid and binding
     obligation of Telecom and each Selling Stockholder and each of this
     Agreement and the Management Agreement is, and the other Seller Documents
     will be, enforceable by and against Telecom and each Selling Stockholder in
     accordance with its respective terms, except as enforceability thereof may
     be limited by applicable bankruptcy, reorganization, insolvency or other
     laws affecting creditors' rights generally or by general principles of
     equity, regardless of whether such enforceability is considered in equity
     or at law.

            (c)  The execution and delivery of this Agreement and the Seller
     Documents by Telecom and each Selling Stockholder and the consummation of
     the transactions contemplated hereby and thereby will not conflict with or
     result in any violations of or defaults under: (i) any statute, regulation,
     order, judgment or decree of any federal, state or local governmental body
     or regulatory authority applicable to Telecom, any Selling Stockholder or
     any of the Assets; (ii) any other statute, regulation, order, judgment or
     decree applicable to Telecom, any Selling Stockholder or any of the Assets
     under or in any other applicable jurisdiction; (iii) any mortgage,
     indenture, lease, agreement, instrument or other obligation to which
     Telecom or any Selling Stockholder


                                      -4-


<PAGE>

     is a party or by which any of the Assets are bound; or (iv) any permit,
     concession, grant, franchise, license, of or applicable to Telecom or any
     Selling Stockholder.  Such execution, delivery and consummation will not
     result in the creation of any lien, charge, encumbrance or security
     interest upon any of the Assets.

     3.3.   CONSENTS AND APPROVALS OF GOVERNMENTAL AUTHORITIES.  Except for the
consent of the FCC to the transfer or change of control of the Authorizations,
no consent, approval or authorization of, or declaration, filing or registration
with, any governmental or regulatory authority is required to be made or
obtained by Telecom or any Selling Stockholder in connection with its execution
and delivery of and performance of its or his obligations under, this Agreement.

     3.4.   FCC REGULATORY MATTERS.

            (a)  Each of the Sellers is in compliance with the Federal
     Communications Act of 1934, as amended (the "Communications Act"), and the
     rules, regulations and policies of the FCC promulgated thereunder
     applicable to either Telecom or the Assets, and each of the Sellers is in
     compliance with all other federal, state and local laws, rules, regulations
     and ordinances applicable to either Telecom or the Assets and is not in
     default under any order, writ, injunction or decree of any court or
     governmental agency or instrumentality applicable to either Telecom or the
     Assets.

            (b)  SHARING AGREEMENTS.  No agreement exists for the shared use of
     facilities, trunk lines, airspace, radio frequencies or other assets used
     in connection with the Assets or the Pending Applications.

            (c)  FCC AUTHORIZATIONS.  Schedule 1.1 sets forth a true and
     complete list of each Authorization that is being transferred to ART
     hereunder, the name of the licensee or permit holder, the call sign, the
     Authorization expiration date, and the status of any applications for
     assignment, transfer or waiver of FCC rules filed (or to be filed) with the
     FCC and a true and complete list of each Pending Application.  Telecom has
     provided to ART true and correct copies of the Authorizations received by
     it from the FCC.  Except for the Superseded Agreements, none of such
     Authorizations or Pending Applications are subject to any purchase, sale,
     option or right of first refusal agreements, and Telecom owns all of the
     right, title and interest in, to and under such Authorizations and Pending
     Applications.  Telecom is qualified under all laws, rules and regulations
     to hold the Authorizations held by it.

            (d)  FEES.  All franchise, license or other fees and charges that
     have become due and payable with respect to the Assets pursuant to any
     applications, filings, recordings and registrations with, and all
     validations or exemptions, approvals, orders or authorizations, consents,
     Authorizations, certificates and permits from, the FCC, any


                                      -5-


<PAGE>

     state public utility commission and any other federal, state or local
     regulatory or governmental bodies or authorities, including any
     subdivision thereof, have been paid.

            (e)  AUTHORIZATION COMPLIANCE.  The Authorizations are valid and in
     full force and effect without materially adverse conditions except for such
     conditions as are generally applicable to FCC Authorizations or holders of
     FCC Authorizations.  No event has occurred and is continuing that could:
     (i) result in the revocation, termination or adverse modification of any
     Authorization listed on Schedule 1.1; or (ii) materially and adversely
     affect any rights of Telecom thereunder prior to Closing or of ART after
     Closing.  Telecom has no reason to believe that the Authorizations will not
     be renewed by the FCC in the ordinary course.  The current ownership and
     operation by Telecom, as applicable, of the Authorizations comply in all
     material respects with all the regulations and policies of the FCC.

            (f)  REPORTS.  Any and all reports and filings required to be filed
     with the FCC by Telecom with respect to the Authorizations have been filed
     and Telecom has provided true and correct copies of all such reports and
     filings to ART.  All such reports and filings were accurate and complete in
     all material respects on the date thereof.  From the date hereof through
     the Closing, all such required reports and filings will be filed by Telecom
     on a timely basis.

            (g)  DISCLOSURE.  Telecom knows of no facts pertaining to its
     qualifications to be a licensee which would cause the FCC not to issue its
     approval with respect to, or otherwise prevent, the transfer to ART
     pursuant to this Agreement of the Authorizations.

     3.5.   TITLE TO THE TRANSFERRED ASSETS; LIENS; OTHER ASSETS.  Telecom has
good, indefeasible and transferable title to all of the Assets, free and clear
of all Liens.

     3.6.   CONTRACTS.  Except for this Agreement, and except as disclosed on
Schedule 3.6, Telecom is not a party to any contract, commitment or similar
agreement or arrangement, whether written or oral, by which any of the Assets is
bound or affected.

     3.7.   LITIGATION.  There are no actions, claims, proceedings, suits and
investigations pending, or, to the best knowledge of each of Telecom and the
Selling Stockholders threatened against any of Telecom, the Assets or any of its
properties, assets or rights before any court, arbitrator or administrative or
governmental body: (i) relating to the Assets or which seek to revoke, rescind,
cancel, modify or refuse to renew any Authorization or; (ii) in connection with
the transactions contemplated hereby, nor is there any basis for any such
action.  There is no judgment, order or decree affecting the Assets or the
transactions contemplated hereby.

     3.8.   DISCLOSURE.  Neither this Agreement nor any exhibit or schedule
hereto nor any statement, list or certificate delivered to ART at or prior to
the Closing pursuant to this


                                      -6-


<PAGE>

Agreement contains any untrue statement of a material fact or omits to state
a material fact necessary in order to make the statement contained herein and
therein in the context in which they were made not misleading.  Except as
otherwise disclosed herein, none of Telecom or the Selling Stockholders know
of any information or fact that has or would have a material adverse effect,
or that might in the future have a material adverse effect, on the Assets.

     3.9.   TAXES.  Telecom has timely filed all requisite federal, state and
local tax and information returns which are required to be filed by it and has
paid, or made adequate provision for the payment of, all taxes which may have or
may become due and there are no assessments or any basis therefor.  There are no
examinations in progress or claims against Telecom for federal or other taxes
(including penalties and interest) for any period and no notice of any claim,
whether pending or threatened, for taxes has been received.

     3.10.  BROKERAGE.  There are no claims for brokerage commissions or
finder's fees or similar compensation in connection with the transactions
contemplated by this Agreement based on any arrangement or agreement made by or
on behalf of Telecom or any Selling Stockholder.

4.   REPRESENTATIONS AND WARRANTIES BY ART.  ART represents and warrants as
follows:

     4.1.   CORPORATE STATUS; AUTHORITY.

            (a)  ART is a corporation duly organized, validly existing and in
     good standing under the laws of the State of Delaware and has full
     corporate power and authority to carry on its business as now conducted
     and to own or lease and operate its properties as and in the places where
     such business is now conducted and as such properties are now owned,
     leased or operated.

            (b)  ART has all necessary corporate power and authority to execute
     and deliver this Agreement and to carry out its obligations hereunder.  At
     the Closing Date, the execution and delivery of this Agreement and the
     consummation of the transactions contemplated hereby shall have been duly
     authorized by the Board of Directors of ART.  This Agreement constitutes
     the valid and legally binding obligation of ART and is enforceable against
     it in accordance with its terms, except as enforceability thereof may be
     limited by applicable bankruptcy, reorganization, insolvency or other laws
     affecting creditors' rights generally or by general principles of equity,
     regardless of whether such enforceability is considered in equity or at
     law.  The execution and delivery of this Agreement and the consummation of
     the transactions contemplated hereby, will not conflict with or result in
     any violation of or default under any provision of the charter documents or
     by-laws of ART or any material mortgage, indenture, lease, agreement or
     other instrument, permit, concession, grant, franchise, license, judgment,
     order, decree, statute, law, ordinance, rule or regulation applicable to it
     or any of its respective properties.


                                      -7-


<PAGE>

     4.2.   LITIGATION.  There are no judicial or administrative actions, suits,
proceedings or investigations pending, or to the knowledge of ART threatened,
that question the validity of this Agreement or of any action taken or to be
taken pursuant to or in connection with the provisions of this Agreement, nor
does ART know of any basis for any such action, suit, proceeding or
investigation.

     4.3.   CONSENTS AND APPROVALS OF GOVERNMENT AUTHORITIES.  Except for the
approval by the FCC of the transfer or change of control, as applicable, of the
Authorizations and except as set forth on Schedule 4.3 hereto, no consent,
approval or authorization of, or declaration, filing or registration with any
court or governmental or regulatory authority is required to be made or obtained
by ART in connection with its execution, delivery and performance of this
Agreement.

     4.4.   BROKERAGE.  There are no claims for brokerage commissions or
finder's fees or similar compensation in connection with the transactions
contemplated by this Agreement based on any arrangement or agreement made by or
on behalf of ART.

5.   EXPENSES.  Each party to this Agreement shall assume and bear all of its
own respective expenses, costs and fees incurred or assumed by each in the
preparation and execution of this Agreement and compliance herewith, whether or
not the transaction herein provided for shall be consummated.

6.   SURVIVAL OF REPRESENTATIONS AND WARRANTIES.  All representations,
warranties and agreements of each of Telecom, the Selling Stockholders and ART
contained herein (including all schedules and exhibits hereto) or in any
document, statement, certificate or other instrument referred to herein or
delivered at the Closing in connection with the transactions contemplated hereby
shall survive the execution and delivery of this Agreement, any investigation by
ART of the Sellers or the Assets, the Closing and the consummation of the
transactions contemplated by this Agreement.

7.   INDEMNITIES.

     7.1.   INDEMNIFICATION BY THE SELLERS.  The Sellers shall jointly and
severally indemnify ART and its successors and assigns for any and all damages,
claims, losses, liabilities, and expenses, including without limitation
reasonable legal and accounting expenses (collectively, "Losses"), which may
arise out of:  (i) any breach of any Sellers' covenants and agreements
hereunder; (ii) any inaccuracy or misrepresentation in any representation or
warranty of any Seller hereunder, in each case as such representation or
warranty would read if all materiality and knowledge standards and disclosure
schedules were deleted from it, or any inaccuracy or misrepresentation in any
certificate or document delivered in accordance with the terms of this Agreement
by any Seller; (iii) any liabilities of Telecom; or (iv) any claim or action
asserted


                                      -8-


<PAGE>

by any third party arising out of or in connection with any event, act or
omission relating to any of the Assets occurring prior to the Closing Date.

     7.2.   INDEMNIFICATION BY ART.  ART shall indemnify and hold harmless the
Sellers from and against any and all Losses which may arise out of:  (i) ART's
breach of any of the covenants and agreements made in this Agreement by ART; or
(ii) any inaccuracy or misrepresentation in any representation or warranty of
ART hereunder, in each case as such representation or warranty would read if all
materiality and knowledge standards and disclosure schedules were deleted from
it, or any inaccuracy or misrepresentation in any certificate or document
delivered in conjunction with this Agreement.

8.   COVENANTS.

     8.1.   PREPARATION FOR CLOSING.  Telecom, the Selling Stockholders and ART
agree to use their best efforts to maintain the accuracy of their respective
representations and warranties contained in this Agreement until the Closing.

     8.2.   FCC AND OTHER APPROVAL.

            (a)  The Sellers and ART will use their best efforts to join in and
     submit as quickly as possible one or more applications (the "Applications")
     to the FCC requesting the FCC's written consent to the change in control or
     the transfer, as the case may be, of the Authorizations to ART or designees
     of ART.

            (b)  Except as otherwise provided herein, each party shall bear its
     own expenses in connection with the preparation and prosecution of the
     Applications.  ART and the Sellers shall equally share in any application,
     consent or other fees charged by the FCC in connection with the
     Applications, and the cost of publishing any public notices in connection
     therewith.

     8.3.   FURTHER ASSURANCES.  At any time and from time to time at or after
the Closing, at the request of ART and without further consideration, the
Sellers will execute and deliver such other instruments of sale, transfer,
conveyance, assignment and confirmation and take such action as ART may
reasonably determine is necessary to transfer, convey and assign to ART, and to
confirm ART's title to or interest in the Assets to put ART in actual possession
and operating control of the Assets and to assist ART in exercising all rights
with respect thereto.

     8.4.   PUBLIC ANNOUNCEMENTS.  Neither ART, Telecom or any of the Selling
Stockholders  will, at any time, without the prior written consent of the other
party, make any announcement, issue any press release or make any statement to
any third party with respect to this Agreement any of the specific matters
discussed between the parties; provided that ART


                                      -9-


<PAGE>

may make any disclosures it deems appropriate in any documents filed with the
Securities Exchange Commission.

     8.5.   INFORMATION AND ACCESS; COMPLIANCE.  During the period from the date
of this Agreement and continuing until the Closing Date or until the termination
of this Agreement pursuant to Section 11 hereof, Telecom shall afford to the
officers, independent certified public accountants, counsel and other
representatives of ART, reasonable access to the properties, books, records and
personnel of Telecom used in or relating to the Assets. Telecom's provisions of
access pursuant to this Section 8.5 shall in no way affect or otherwise obviate
or diminish any representations and warranties of Telecom.  Telecom shall take
all reasonable actions necessary to comply promptly with all legal requirements
which may be imposed on Telecom with respect to this Agreement and the
transactions contemplated hereby (including furnishing all information required
by the FCC in connection with transfer of the Authorizations and Pending
Applications) and shall take all reasonable actions necessary to cooperate
promptly with and furnish information to ART in connection with any such
requirements imposed upon ART in connection with this Agreement and the
transactions contemplated hereby. Telecom shall not take or reasonably fail to
take any action which it believes would cause its disqualification as an
assignor of the Authorizations.

     8.6.   CONFIDENTIALITY.  Telecom acknowledges that ART is considering a
public and/or private sale of stock and debt and has filed material with the
Securities and Exchange Commission.  Telecom further acknowledges that,
accordingly, it is important that no public communications of any kind and no
communications to any third parties including without limitation to any
investment bankers, investment analysts, journalists or reporters of any aspects
or facts relating to this Agreement and the transactions related hereto be made
by Telecom or any of its advisers, consultants or agents.  Telecom shall take
all steps reasonably necessary to ensure that its employees, officers,
directors, advisers, attorneys, financial technical and other consultants,
investment bankers and agents are informed and agree to abide by all of the
relevant provisions of this Section 8.6.  Telecom understands that ART may not
have an adequate remedy at law for a beach or threatened breach by such party of
the terms of this Section 8.6, and Telecom therefore agrees that, if there is
any such breach or threatened breach, ART may, in addition to any other legal or
equitable remedies available to it, obtain an injunction or restraining order to
enjoin Telecom from the breach or threatened breach of this Section 8.6.

     8.7.   CONDUCT OF BUSINESS BY SELLERS.  Sellers covenant that the Seller
shall not:

            (a)  sell, transfer, convey or otherwise dispose of any of the
     Assets or, except in accordance with the provisions of this Agreement, any
     of the Pending Applications or any right thereto or interest therein,

            (b)  encumber, or agree to encumber, in any way, or enter into any
     consensual restriction with respect to, any of the Assets or, except in
     accordance with the


                                      -10-


<PAGE>

     provisions of this Agreement, the Pending Applications or any right
     thereto or interest therein, or

            (c)  enter into any contract, agreements or understanding with
     respect to any of the Assets or, except in accordance with the provisions
     of this Agreement, the Pending Applications.

            (d)  enter into any agreements or commitments for any of 8.7(a)
     through 8.7(c).

9.   CONDITIONS PRECEDENT TO ART'S OBLIGATIONS.  All obligations of ART under
this Agreement are subject to the fulfillment to the reasonable satisfaction of
ART prior to or at the Closing of each of the following conditions, any of which
may be waived by ART in its sole discretion:

     9.1.   REPRESENTATIONS AND WARRANTIES.  The representations and warranties
made by the Sellers in this Agreement (including all exhibits and schedules
hereto), shall be true and correct in all material respects when made and shall
be repeated and shall be true and correct in all material respects at and as of
the Closing Date, and ART shall have received a certificate dated the date of
the Closing signed by the chief executive officer of Telecom to the foregoing
effect.

     9.2.   CONSENTS.  All filings with and consents from all federal, state and
local governmental agencies required to consummate the transactions contemplated
by this Agreement shall have been made or received, as applicable.

     9.3.   FCC AUTHORIZATIONS.  Without limiting the generality of Section 9.2,
the FCC shall have authorized the transfer or change of control, as applicable,
of all of the Authorizations by a Final Order (as defined below), without any
conditions or restrictions that materially affect the value of the
Authorizations or operations pursuant to the Authorizations or any conditions or
restrictions materially different than the normal authorizations issued by the
FCC to other 38 GHz license holders at the date of this Agreement.  In the event
that any FCC order approving the transfer of the Authorizations to ART imposes
such conditions, this condition shall not be satisfied until such conditions are
removed or eliminated, and Sellers shall fully cooperate in obtaining the
removal or elimination of such restrictions.  "Final Order" means an action by
the FCC granting its consent to the assignment of a Authorization, with respect
to which no request for stay, petition for rehearing, reconsideration or appeal
is pending, and as to which the time for filing any petition for rehearing,
reconsideration or appeal has expired and with respect to which the time for
agency reconsideration or review taken on its own motion has expired, or in the
event of the filing of such request, petition or appeal, an action which shall
have been reaffirmed or upheld and with respect to which the time for seeking
further administrative or judicial review shall have expired.


                                      -11-


<PAGE>

     9.4.   PERFORMANCE BY TELECOM; CERTIFICATE.  Telecom shall have performed
and complied with all agreements and conditions required by this Agreement to
be performed or complied with by them prior to or at the Closing, and the chief
executive officer of Telecom shall deliver to ART a certificate dated the
Closing Date, to such effect.

     9.5.   ABSENCE OF ERRORS AND OMISSIONS.  ART shall not have discovered
any material error, misstatement or omission in any of the representations or
warranties, or any material failure to perform or satisfy any covenants or
conditions required by this Agreement to be performed or satisfied by the
Sellers on or prior to the date of Closing.

     9.6.   OPINIONS OF COUNSEL FOR TELECOM.  ART shall have received favorable
opinions addressed to it and dated the Closing Date of Fleischman & Walsh LLP,
counsel and FCC counsel for Telecom in form and substance acceptable to ART and
its counsel.

     9.7.   ABSENCE OF LITIGATION.  No action or proceeding shall have been
instituted or threatened prior to or at the Closing Date before any court or
governmental body or authority pertaining to the transactions contemplated
hereby, the result of which could prevent or make illegal the consummation of
such transactions or which could be materially adverse to the Assets.

     9.8.   UCC SEARCHES.  ART shall have obtained Uniform Commercial Code
(including fixture filings) and state and federal tax and judgment lien
searches against Telecom all dated within 5 days of the Closing Date.

     9.9.   RELEASE OF LIENS.  All of the Assets shall be free and clear of all
liens and ART shall have received evidence of the release of all liens and the
termination of all financing statements, if any, as may be reasonably requested
by ART.

     9.10.  CORPORATE APPROVAL.  This Agreement and the transactions
contemplated hereby shall have been approved by the Board of Directors of ART.

10.  CONDITIONS PRECEDENT TO THE OBLIGATIONS OF THE SELLERS.  The obligations of
the Sellers to consummate the transactions contemplated hereby shall be subject
to the fulfillment by ART, prior to or at the Closing, of each of the following
conditions:

     10.1.  REPRESENTATIONS AND WARRANTIES.  The representations and warranties
made by ART in this Agreement shall be true and correct in all material respects
when made and shall be repeated and shall be true and correct in all material
respects at and as of the Closing Date, except as specifically provided for
herein, and Telecom shall have received a certificate dated the date of Closing
signed by an officer of ART, to the foregoing effect.


                                      -12-


<PAGE>

     10.2.  GOVERNMENT CONSENTS.  All filings with and consents from all
federal, state and local governmental agencies required to consummate the
transactions contemplated hereby shall have been obtained at or prior to the
Closing.

     10.3.  PERFORMANCE OF ART.  ART shall have performed and complied with all
agreements and conditions required by this Agreement to be performed or complied
with by it prior to or at the Closing and an officer of ART shall deliver a
certificate or certificates to Telecom to such effect.

     10.4.  ABSENCE OF LITIGATION.  No action or proceeding shall have been
instituted or threatened prior to or at the Closing Date before any court or
governmental body or authority pertaining to the transactions contemplated
hereby, the result of which could prevent or make illegal the consummation of
such transactions.

     10.5.  PURCHASE PRICE.  The Purchase Price shall have been delivered to
Telecom.

11.  TERMINATION.  This Agreement may be terminated by the parties as set forth
in this Section 11:

            (a)  at any time by the mutual written consent of Telecom and ART;

            (b)  by ART at any time after July 1, 1997, if the conditions set
     forth in Section 9 shall not have been complied with or performed and such
     noncompliance or nonperformance shall not have been cured or eliminated by
     the Sellers by such time;

            (c)  by Telecom at any time after July 1, 1997 (the "Seller Date"),
     if the conditions set forth in Section 10 hereof shall not have been
     complied with or performed and such noncompliance or nonperformance shall
     not have been cured or eliminated by ART by such time; provided that if
     prior to the Seller Date, the FCC has issued an order, that is not yet a
     Final Order, approving the transfer or change in control, as applicable, of
     the Authorizations, to ART, ART may extend the Seller Date until July 1,
     1998 by notice to Telecom.

            (d)  by the Sellers on the one hand, or by ART, on the other, if
     there shall have been a breach of any material representation, warranty,
     covenant or agreement on the part of the others set forth or contemplated
     by this Agreement, which breach cannot be cured prior to the Closing.

provided, however, that the terminating party may not terminate its obligations
under this Agreement if such terminating party has breached this Agreement in
any material respect.

     Notwithstanding any termination of this Agreement pursuant to this Section
11, the provisions of Sections 7, 8.4, 8.6 and 12.1 hereof shall remain in full
force and effect.


                                      -13-


<PAGE>

12.  POST CLOSING COVENANTS.

     12.1.  DISCLOSURE OF INFORMATION.  From and after the Closing, the Sellers
shall not use or disclose to any person any proprietary information of ART for
any reason or purpose whatsoever, nor shall it make use of any such information
for its own purposes or for the benefit of any person except ART or any
affiliate thereof.  The restrictions on use and disclosure of information
contained in this Section 12.1 do not extend to any item of information that (A)
is publicly known at the time of its disclosure, (B) is lawfully received from a
third party not bound in a confidential relationship to ART, (C) is published or
otherwise made known to the public by ART, or (D) is required to be disclosed
pursuant to a court order, provided that, upon receiving notice such disclosure
is required, the Sellers shall promptly give ART notice thereof, and the Sellers
shall cooperate with ART's efforts, if any, to contest the applicability of such
order.

     12.2.  NON-COMPETITION/NON-INTERFERENCE/NON-SOLICITATION.  The Sellers
recognize and acknowledge the highly competitive nature of 38 Ghz operations and
that ART would be irreparably harmed if Sellers were to compete with ART in the
geographic areas covered by the Authorizations.  Accordingly, in consideration
of the premises contained herein, the consideration to be received hereunder and
in consideration of and as an inducement to the transactions contemplated
hereby, neither the Sellers nor any of their affiliates shall, from and after
the date hereof until the fifth anniversary of the Closing Date:  (i) apply for,
manage, or acquire all or any part of any 38 Ghz authorizations in any area
covered in whole or in any part by any of the 38 Ghz Authorizations being
transferred pursuant hereto; (ii) interfere with, disrupt or attempt to disrupt
the relationship, contractual or otherwise, between ART and any third party,
including, without limitation, any customer, supplier or employee of ART, or
(iii) solicit any employee of ART for employment by the sellers or any of their
affiliates.

     12.3.  INJUNCTIVE RELIEF.  The parties recognize and acknowledge that a
breach of sections 12.1 or 12.2 by the Sellers may cause irreparable and
material loss and damage to ART as to which ART may not have an adequate remedy
at law or in damages.  Accordingly, the Seller acknowledge and agree that, in
addition to which ART may be entitled, the issuances of an injunction or other
equitable remedy is an appropriate remedy for any such breach.  It is the desire
and intent of Sellers and ART that the provisions of sections 12.1 and 12.2
shall be enforced to the fullest extent permissible under the laws and public
policies applied in each jurisdiction in which enforcement is sought. 
Accordingly, if any particular provision of any of said subsections shall be
adjudicated to be invalid or unenforceable, such provision shall be deemed
amended to delete therefrom the portion adjudicated to be invalid or
unenforceable, such deletion to apply only with respect to the operation of such
provision in the particular jurisdiction in which such adjudication is made.

13.  ENTIRE AGREEMENT; ASSIGNABILITY.  This Agreement, together with the
schedules and exhibits hereto, constitutes the entire agreement between the
parties hereto pertaining to the subject matter hereof and supersedes all prior
and contemporaneous agreements,


                                      -14-


<PAGE>

understandings, negotiations and discussions, whether oral or written, of the
parties, and there are no warranties, representations or other agreements
between the parties in connection with the subject matter hereof except as
specifically set forth herein.  This Agreement may not be assigned by any of
the Sellers without the prior written consent of ART and any such attempted
assignment shall be null and void.

14.  AMENDMENT.  This Agreement may be amended by the parties hereto at any
time, but only by an instrument in writing duly executed and delivered on behalf
of each of the parties hereto.

15.  HEADINGS.  Section headings are not to be considered part of this Agreement
and are included solely for convenience and are not intended to be full or
accurate descriptions of the contents thereof.  References to Sections are to
portions of this Agreement unless the context requires otherwise.

16.  EXHIBITS, ETC.  Exhibits, schedules and other documents referred to in this
Agreement are an integral part of this Agreement.

17.  SUCCESSORS AND ASSIGNS.  All of the terms and provisions of this Agreement
shall be binding upon and shall inure to the benefit of the parties hereto and
their respective transferees, successors and assigns.

18.  NOTICES, ETC.  All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given on the
date of delivery if delivered or mailed, first-class postage prepaid,

            (a)  if to Telecom, to:

                           Telecom One, Inc.
                           1004 Woburn Court, Suite 100
                           McLean, Virginia  22102
                           Attention:  Gordon Hutchins, Jr.

            with a copy to:

                           Fleischman & Walsh, LLP
                           1400 16th Street, N.W.
                           Washington, D.C.  20036
                           Attention:  Mitchell F. Brecher

            (b)  if to ART to:

                           Advanced Radio Technologies Corporation


                                      -15-


<PAGE>

                           500 108th Avenue, N.E., Suite 2600
                           Bellevue, Washington, 98004
                           Attention:  W. Theodore Pierson, Jr. and
                                        Thomas A. Grina

            with a copy to:

                           Ropes & Gray
                           One International Place
                           Boston, Massachusetts, 02110-2624
                           Attention:  Mary E. Weber, Esq.

19.  GOVERNING LAW.  This Agreement and the rights and obligations of the
parties hereto arising out of this Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware without regard to the
internal conflict of law provisions thereof.

20.  SEVERABILITY.  The provisions of this Agreement are severable, and if any
one or more provisions are deemed illegal or unenforceable, the remaining
provisions shall remain in full force and effect.

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

         [The remainder of this page has been intentionally left blank]


                                      -16-


<PAGE>

     IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement
as of the day and year first above written.

                           TELECOM ONE. INC.

                           By: ________________________________
                               Name:
                               Title:

                           ADVANCED RADIO TECHNOLOGIES
                            CORPORATION

                           By: ________________________________
                               Name:
                               Title:

                           SELLING STOCKHOLDERS

                           ____________________________________
                           Name:  William Rodi

                           ____________________________________
                           Name:  Gordon Hutchins, Jr.


                                      -17-


<PAGE>

                        TELECOM MANAGEMENT AGREEMENT


     THIS MANAGEMENT AGREEMENT ("Agreement") between Telecom One, Inc.
("Licensee"), a Delaware corporation, and Advanced Radio Technologies
Corporation ("ART"), a Delaware corporation, is entered into as of the dates set
forth next to the signatures below and is effective as of June __, 1996.

     WHEREAS, Licensee is the licensee for the Federal Communications Commission
("FCC") authorizations (collectively, the "Authorizations") for 38 GHz frequency
radio systems (the "Systems") in various locations ("Markets"); and

     WHEREAS, Licensee and ART desire to enter into an exclusive agreement for
the construction, operation, and management by ART of the Systems, including
without limitation those listed in Exhibit A hereto, consistent with Licensee's
obligations in connection with the Authorizations under all of the Federal and
state laws, rules, and regulations;

     NOW, THEREFORE, in consideration of the premises and covenants hereinafter
set forth, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties, intending to be
legally bound, hereby agree as follows:

     1.  TERM OF AGREEMENT AND TERMINATION.

         (a)   This Agreement becomes effective on the date set forth above. 
Unless it is terminated earlier pursuant to the  provisions of this Section, the
term of this Agreement ("Term") shall extend for ten years and shall renew
automatically for additional ten year terms, unless either party terminates this
Agreement as of the end of any such ten year term on at least 365 days' written
notice prior to the end of any such term;

         (b)   This Agreement shall terminate with respect to any of the
Authorizations, upon the acquisition of any such Authorization by ART pursuant
to FCC consent

         (c)   At any time after the termination, pursuant to its terms, of the
Asset Purchase Agreement between the parties hereto, dated the date hereof,
either party may terminate this Agreement with up to 180 days' prior written 
notice to the other party.

     2.  SYSTEM CONSTRUCTION AND MANAGEMENT; EQUIPMENT LEASE.  Licensee hereby
grants ART the exclusive right to manage the Systems under the following terms
and conditions. Licensee agrees that it shall not grant any other party the
right to manage its Systems and Authorizations, provided, however, that Telecom
One, Inc. retains the right to construct and operate its Systems, provided that
License agrees to coordinate the construction of all Systems with ART.  Subject
to Licensee's supervision and control, ART will use its reasonable efforts


<PAGE>

to undertake the planning, design, construction, installation, marketing, sales
and operations of the Systems.

     In particular, the parties agree as follows:

         (a)  ART shall propose a schedule of construction to Licensee that will
identify the proposed date for each System to become operational in a manner
designed to satisfy all FCC and other regulatory requirements.  Licensee shall
have ten business days in which to approve or reject such proposed schedule, not
to be unreasonably withheld.

         (b)  Once the schedule has been approved, ART shall use its reasonable
efforts to construct the Systems in accordance with such schedule.

         (c)  ART shall acquire, lease, or otherwise obtain the right to use all
assets (collectively, the "Equipment"), necessary for the operation of the
Systems, including any expansion, modification or reduction thereof.

         (d)  On behalf of Licensee, ART shall bill and collect, from the users
of the Systems, all fees, charges, or other compensation arising from such use,
and shall pay all expenses and fees incurred or payable by the Systems.

         (e)  Subject to Licensee's ultimate supervision and control, ART shall
generally manage the day-to-day operations of the Systems and do or assist with
any and all other acts and shall execute such other agreements, documents or
instruments, as are consistent with FCC rules and regulations and, in the good
faith judgment of ART, are necessary to carry out the development, construction
and operation of the Systems, whether or not specifically enumerated herein.

         (f)  All Equipment shall be acquired and constructed by ART and shall
be the property of ART.  The Equipment shall be leased to Licensee for the
consideration described in Section 4 hereof during the term of this Agreement
and solely for the purposes described herein.  During the term of such lease,
Licensee shall have full and unfettered access to all the Equipment used in
Licensee's System.  Such lease shall terminate simultaneously with the
termination of this Agreement for any reason.  Upon such termination, the
Equipment shall remain the property of the ART, and ART may take immediate
possession thereof.

     3.  REGULATORY COMPLIANCE.  The parties agree that Licensee is in sole
control of the Authorizations and that it is required by FCC regulations to be
in sole control of the licensed facilities so long as it is the Licensee.  ART
acknowledges and agrees that Licensee has ultimate control over all decisions
affecting System, notwithstanding any other provision of this Agreement.  ART
will assist Licensee in complying with all applicable Federal, state and local
regulations.  This assistance includes, but is not limited to, the following:


                                      -2-


<PAGE>

         (a)  Each System customer will be advised that service is provided
over facilities licensed to and subject to the ultimate control by Licensee;

         (b)  ART agrees to use its reasonable efforts to comply with all FCC
timetables concerning construction and operation and to take such steps as may
be needed to preserve any Authorizations that may be granted by the FCC,
including discontinuing operations if so directed by Licensee to avoid any
violations of FCC rules or regulations; ART will provide Licensee with advance
written notice if it comes into possession of facts indicating that it will be
unable to render a System operational within the timetable specified by the
terms of the applicable authorization;

         (c)  Neither ART nor Licensee shall represent themselves as the legal
agents or one another;

         (d)  Licensee shall, with the cooperation and assistance of ART, fully
comply with the applicable requirements of the Communications Act of 1934, as
amended (the "Act"), and all regulations necessary to keep the Authorization in
full force and effect, including FCC regulations.  Licensee shall prepare and
submit to the FCC and any other relevant Federal, state or local agency all
reports, applications, renewals, or other filings or documents that may be
required for this purpose, provided that ART shall provide any assistance
required by Licensee in fulfilling this obligation; and

         (e)  In the event that ART determines that any modification to any
System Authorization are necessary or desirable, ART will submit to Licensee a
description of such proposed modifications for Licensee's review and approval,
which shall not be unreasonably withheld.  Upon approval, Licensee shall
promptly file with the FCC any requests for modifications of the relevant
Authorization submitted to such Licensee by ART which may be needed to make
construction feasible, or any filings or appeals which are necessary to extend
the period for construction under the FCC's rules.  Such requests may include,
but not be limited to, applications to the FCC for special temporary authority.

         (f)  Each party has determined in good faith that this Agreement is
consistent with the Act and the FCC's rules.  In the event that the FCC
determines that this Agreement is inconsistent with Licensee's obligations under
the Act or it is otherwise contrary to FCC policies, rules and regulations, the
parties agree to modify this Agreement in any reasonable way to maintain
consistency with the Act and the FCC's rules, preserving to the maximum extent
possible the essential business terms and conditions contained herein.

     4.  LICENSE FEES.  During the term of this Agreement, Licensee shall pay
ART fifteen percent (15%) of all Gross Revenue (as defined below) as lease
payments for the  Equipment pursuant to Section 2(f) hereof (each such payment
made from time to time is referred to as a "Lease Payment"), and Licensee shall
pay ART seventy-five percent (75%) of all Gross Revenue as ART's compensation
for managing the Systems pursuant hereto (each payment


                                      -3-


<PAGE>

made from time to time is referred to as a "Management Payment").  ART shall
remit all revenue relating to the Authorizations other than the Lease
Payments and Management Payments.  Such revenue to be remitted to Licensee,
for each calendar quarter, shall be distributed to Licensee within sixty days
of the end of such quarter.  "Gross Revenue" shall mean all revenue derived
from the operation of the Systems less expenses paid to third parties in
respect of equipment and facilities directly related to the provision of
services.

     5.  NOTICE.  All notices and other communications shall be in writing and
shall be deemed given the same day if delivered personally or sent by telecopy
or the next business day if sent by express mail or courier (overnight
delivery), or five (5) business days later if sent by registered mail or
certified mail, return receipt requested, postage prepaid, to the parties at the
following addresses or at such other address for a party as shall be specified
by like notice, provided that notice of change of address shall be effective
only upon receipt thereof:

         (a)  If to Licensee, to:
              Telecom One, Inc.
              1004 Woburn Ct., Suite 100
              McLean, Virginia  22102
              Attn:  Gordon Hutchins, Jr.

              With a copy to:

              Fleischman & Walsh LLP
              1400 16th St., N.W.
              Washington, DC 20036
              Attn:  Mitchell Brecher

         (b)  If to ART, to

              Advanced Radio Technologies Corporation
              500 108th Avenue, N.E., Suite 2600
              Bellevue, Washington 98004
              Attn:  Thomas A. Grina

              With a copy to:

              W. Theodore Pierson, Jr.
              Executive Vice President and General Counsel
              1200 Nineteenth St., N.W., Suite 607
              Washington, D.C.  20036


                                      -4-


<PAGE>

     6.  REPRESENTATIONS AND WARRANTIES.

         (a)  Licensee represents and warrants that it is the licensee or
permit holder with respect to the Authorizations listed in Exhibit A and that it
is duly qualified under all laws, rules and regulations to hold such
Authorizations.  Licensee further represents and warrants that it is the sole
holder of the Authorization and is the real party in interest with respect to
the Authorizations and that no other party has an interest of any kind. 
Licensee further represents that it has the requisite authority and/or capacity,
as applicable, to perform its undertakings pursuant to this Agreement.

         (b)  Licensee represents and warrants that it will take all necessary
steps, to maintain the Authorizations with the FCC in good standing.

         (c)  Each of the parties hereto represents and warrants that each
shall take such steps and execute such documents as may be necessary from time
to time to effectuate the terms and conditions of this Agreement.

         (d)  ART represents and warrants that it is a corporation duly
authorized and in good standing under the laws of the State of Delaware and has
the requisite authority to perform its undertakings pursuant to this Agreement.

         (e)  ART represents and warrants that it is familiar with the
applicable rules and regulations of the FCC and that it is aware of no
impediment to the performance of its undertakings hereunder.

     7.  INDEMNIFICATION.

         (a)  Licensee agrees to indemnify and hold harmless ART from and
against all liabilities, obligations, claims, damages, penalties, causes of
action, costs and expenses (including, without limitation, reasonable attorney's
fees and costs), imposed upon or incurred by or asserted against ART that arise
as a result of the negligence or misconduct of Licensee or Licensee's employees
or agents.

         (b)  ART agrees to indemnify and hold harmless Licensee from and
against all liabilities, obligations, claims, damages, penalties, causes of
action, costs and expenses (including, without limitation, reasonable attorney's
fees and costs), imposed upon or incurred by or asserted against Licensee that
arise as a result of the negligence or misconduct of ART or ART's employees or
agents, including but not limited, to conduct in violation of the Act, the rules
and regulations of the FCC and the terms and conditions of the Authorization.


                                      -5-


<PAGE>

     8.  ASSIGNABILITY; SUCCESSORS AND ASSIGNS.

         (a)  Licensee may not assign this Agreement without ART's prior written
consent, which consent shall not be unreasonably  withheld.  Any assignment in
violation of this Section 8 shall be null and void.

         (b)  ART may assign its right to manage the Systems hereunder, with
Licensee's prior written consent not to be unreasonably withheld, to another
party, provided such assignee of ART has experience in the management of 38 GHz
systems or other telecommunications facilities or, alternatively, employs either
personnel of ART or other persons who have experience in the management of 38
GHz systems or other telecommunications facilities.  Notwithstanding the
foregoing, ART may assign its rights hereunder to a corporate affiliate.  ART
may employ such subcontractors or agents as it deems necessary in the
performance of its duties hereunder.

         (c)  This Agreement shall be binding upon and inure to the benefit of
the parties hereto, and their respective heirs, representatives, successor and
permissible assigns.

     9.  SEVERABILITY.  In the event that any provision herein is held to
invalid, void, or illegal by any Federal, state or local court, or any
regulatory agency, the remaining provisions of the Agreement shall remain in
full force and effect and this Agreement shall be reasonably construed so as to
preserve the original intent of the parties hereto insofar as practicable.  In
the event that any provision herein is deemed to be invalid, void, in violation
of any agency rules, or otherwise unlawful, the parties shall use their
respective best efforts to amend the offending provisions to bring them into
legal compliance with minimum disruption to the expectations of the parties as
set forth in this Agreement.

     10. COUNTERPARTS.  This agreement may be executed in any number of
counterparts with the same as if the signature of each counterpart were in the
same instrument.

     11. NO WAIVER OF RIGHTS; AMENDMENT.  The failure of either party to
insist, in any one or more instances, upon the performance of any of the terms,
covenants or conditions herein, or to exercise any right hereunder, shall not be
construed as a waiver or relinquishment of the future performance of any such
term, covenant or condition, or the future exercise of such right, but the
obligation of the other party with respect to such future performance shall
continue in full force and effect.  This Agreement may only be amended, modified
or changed by a writing signed by all parties hereto.

     12. WARRANTY.  THERE ARE NO EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
WITHOUT LIMITATION, IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE, RESPECTING THIS AGREEMENT OR THE SERVICE PROVIDED HEREUNDER.


                                      -6-


<PAGE>

     13. ENTIRE AGREEMENT.  This Agreement supersedes any other agreements
between the parties, whether oral or written, including but not limited to the
Services Agreement entered into April 24, 1996 between Telecom One, Inc. and
Advanced Radio Telecom Corp., with respect to the Authorizations, relating to
the matter contemplated herein, and constitutes the entire agreement by and
between the parties, there being no other agreements or understandings between
the parties as expressly set forth herein.

     14. GOVERNING LAW/PROCEDURE.  This Agreement will be governed by the laws
of the State of Delaware; provided that any dispute under this Agreement will be
resolved by arbitration under the Commercial Arbitration rules of the American
Arbitration Association, using one arbitrator.


                                      -7-


<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first written above.

ART:                               LICENSEE:

Advanced Radio Technologies        Telecom One, Inc.
Corporation

By:____________________________    By:____________________________

Printed Name:__________________    Printed Name:__________________

Title:_________________________    Title:_________________________

Dated:_________________________    Dated:_________________________


Advanced Radio Telecom Corp.
(for purposes of Section 13 hereof only)

By:____________________________

Printed Name:__________________

Title:_________________________

Dated:_________________________


                                      -8-


<PAGE>

                                                                 EXHIBIT 10-20


                           SECOND RESTATED AND AMENDED

                          REGISTRATION RIGHTS AGREEMENT

                                      among

                          Advanced Radio Telecom Corp.

                     Advanced Radio Technologies Corporation

       the stockholders and warrantholders of Advanced Radio Telecom Corp.

                                     and the

   stockholders and warrantholders of Advanced Radio Technologies Corporation






                                  July 3, 1996
<PAGE>


SECTION 1.     Definitions . . . . . . . . . . . . . . . . . . . . . . . .4

SECTION 2.     Piggyback Registration. . . . . . . . . . . . . . . . . . .6

SECTION 4.     Holdback Agreement. . . . . . . . . . . . . . . . . . . . .9

SECTION 5.     Preparation and Filing. . . . . . . . . . . . . . . . . . .9

SECTION 6.     Expenses. . . . . . . . . . . . . . . . . . . . . . . . . 12

SECTION 7.     Indemnification . . . . . . . . . . . . . . . . . . . . . 12

SECTION 8.     Underwriting Agreement. . . . . . . . . . . . . . . . . . 14

SECTION 9.     Information by Holder . . . . . . . . . . . . . . . . . . 14

SECTION 10.    Exchange Act Compliance . . . . . . . . . . . . . . . . . 14

SECTION 11.    No Conflict of Rights . . . . . . . . . . . . . . . . . . 14

SECTION 12.    Restriction on Transfer . . . . . . . . . . . . . . . . . 15

SECTION 13.    Termination . . . . . . . . . . . . . . . . . . . . . . . 16

SECTION 14.    Successors and Assigns. . . . . . . . . . . . . . . . . . 16

SECTION 15.    Assignment. . . . . . . . . . . . . . . . . . . . . . . . 16

SECTION 16.    Entire Agreement. . . . . . . . . . . . . . . . . . . . . 16

SECTION 17.    Notices . . . . . . . . . . . . . . . . . . . . . . . . . 17

SECTION 18.    Modifications; Amendments; Waivers. . . . . . . . . . . . 17

SECTION 19.    Counterparts. . . . . . . . . . . . . . . . . . . . . . . 18

SECTION 20.    Headings. . . . . . . . . . . . . . . . . . . . . . . . . 18

SECTION 21.    Severability. . . . . . . . . . . . . . . . . . . . . . . 18


                                       -2-
<PAGE>


SECTION 22.    Acknowledgment. . . . . . . . . . . . . . . . . . . . . . 18

SECTION 23.    Governing Law . . . . . . . . . . . . . . . . . . . . . . 19


                                       -3-
<PAGE>

SECOND RESTATED AND AMENDED REGISTRATION RIGHTS AGREEMENT, dated July 3, 1996
(the "Restated Registration Agreement") among (i) ADVANCED RADIO TELECOM CORP.
(formerly Advanced Radio Technology, Ltd., a Delaware corporation (the "Company"
or "Telecom") (ii) ADVANCED RADIO TECHNOLOGIES CORPORATION, a Delaware
corporation ("ART"), (iii) the existing stockholders of the Company listed under
Part I(a) of Schedule I (the "Existing Landover Stockholders"), (iv) the
stockholders of ART listed under Part II(a) of Schedule I (the "Existing ART
Stockholders"), (v) the stockholders of the Company listed under Part I(b) of
Schedule I (the "New Landover Stockholders"), (vi) the stockholders of the
Company listed under Part 1(c) of Schedule I (the "New Unaffiliated
Stockholders" and, collectively with the Existing Landover Stockholders and the
New Landover Stockholders, the "Investor Telecom Stockholders"), (vii) the
stockholders of ART listed under Part II(b) of Schedule I (the "New ART
Stockholders" and collectively with the Existing ART Stockholders, the "ART
Stockholders"), (viii) the holders of Bridge Warrants listed under Part III(A)
of Schedule I (the "Bridge Warrant Holders"), (ix) the holders of New Bridge
Warrants listed under Part III(c) of Schedule I (the "New Bridge Warrant
Holders") and (x) CommcoCCC, Inc.  The Existing Landover Stockholders and the
Existing ART Stockholders are collectively referred to as the "Existing
Stockholders" and the New Landover Stockholders, the New Unaffiliated
Stockholders and the New ART Stockholders are collectively referred to as the
"New Stockholders".

     Background:

     ART, Telecom, the New Stockholders, the Existing Stockholders and the
Bridge Warrant Holders are parties to a Restated Registration Rights Agreement
dated February 2, 1996, as amended, (the "First Restated Registration
Agreement") and wish to amend and restate the First Restated Registration
Agreement in order to admit the New Stockholders and Telecom as parties and to
effect certain amendments.

     Since the Company cannot complete a Public Offering until it completes the
Merger, this Agreement is effective only after the Merger.

     The following provisions amend, restate and supersede all the provisions of
the First Restated Registration Agreement.

     The parties agree as follows:

     SECTION 1.  DEFINITIONS.  As used in this Agreement, the following terms
shall have the following meanings:

     "Acquisition Holders" means persons  who acquire shares of Common Stock
pursuant to the Asset Acquisition Agreement and Plan of Reorganization dated the
date hereof, by and among CommcoCCC, Inc., CCC Millimeter, L.P., Columbia
Millimeter Communications, L.P., Commco, L.L.C., Columbia Capital Corporation,
ART and Telecom.


                                       -4-
<PAGE>

     "Advent" means Advent International Corporation, a Delaware corporation.

     "Advent Group" means Advent and persons controlled by Advent.

     "Affiliate" means as to any Person, any other Person that, directly or
indirectly, alone or through others, controls, is controlled by or is under
common control with such Person. For purposes of this definition "controls"
(including with correlative meanings, the terms "controlled by" and "under
common control with" as applied to any Person) means the possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of that Person, whether through the ownership of voting securities or
by contracts or otherwise.

     "Ameritech" means Ameritech Development Corporation, a Delaware
corporation.

     "Bridge Warrants" means the warrants to purchase an aggregate of 1,100,000
shares of Telecom Common Stock issued on March 8, 1996.

     "Commission" means the Securities and Exchange Commission or any other
Federal agency at the time administering the Securities Act.

     "Common Stock" means the Common Stock, $.001 par value, of Telecom and its
successors.

     "Exchange Act" means the Securities Exchange Act of 1934, and the rules and
regulations of the Commission promulgated thereunder, all as the same shall be
in effect from time to time.

     "Indemnity Warrants" means the warrants to purchase an aggregate of 325,000
shares of Telecom Common Stock issued on April 19, 1996.

     "Investor ART Stockholders" means, collectively, Sintra Fund, Ltd., Stephen
Osman PFG Corp and Telecom Partners, L.P.

     "Landover" means Landover Holdings Corporation.

     "Merger" is defined in the Stockholders Agreement.

     "New Bridge Warrant" means the warrants to purchase an aggregate of 50,000
shares of Common Stock issued on the date hereof.

     "Other Shares" means at any time those shares of Common Stock which do not
constitute Primary Shares or Registrable Shares.


                                       -5-
<PAGE>

     "Party" shall mean any of the Stockholders, Telecom Warrant Holders,
Acquisition Holders or New Bridge Warrant Holders.

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

     "Primary Shares" means at any time the authorized but unissued shares of
Common Stock or shares of Common Stock held by the Company in its treasury.

     "Registrable Shares" means at any time, with respect to any Party, the
shares of Common Stock, or any other securities which by their terms are
exercisable and exchangeable for or convertible into Common Stock and any
securities received in respect thereof, held by such Party which constitute
Restricted Shares.

     "Registration Date" means the date upon which the registration statement
pursuant to which the Company shall have initially registered shares of Common
Stock under the Securities Act for sale to the public shall have been declared
effective.

     "Restricted Shares" means at any time, with respect to any Stockholder, the
shares of Common Stock, any other securities which by their terms are
exercisable or exchangeable for or convertible into Common Stock and any
securities received in respect thereof, which are held by such Stockholder and
which have not previously been sold to the public pursuant to a registration
statement under the Securities Act.

     "Rule 144" means Rule 144 promulgated under the Securities Act or any
successor rule thereto or any complementary rule thereto.

     "Securities Act" means the Securities Act of 1933, and the rules and
regulations of the Commission thereunder, all as the same shall be in effect
from time to time.

     "Stockholders" is defined in the Stockholders Agreement.

     "Stockholders Agreement" means the Restated and Amended Stockholders
Agreement dated February 2, 1996, as amended from time to time, among the
parties to this Agreement.

     "Transfer" means any disposition of any Restricted Shares or of any
interest therein which constitutes a sale within the meaning of the Securities
Act, other than any disposition pursuant to an effective registration statement
under the Securities Act and complying with all applicable state securities and
"blue sky" laws.

     SECTION 2.  PIGGYBACK REGISTRATION.  If the Company at any time proposes
for any reason to register shares of Common Stock under the Securities Act
(other than in an initial


                                       -6-
<PAGE>

Public Offering of Primary Shares or on Form S-4 or Form S-8 promulgated under
the Securities Act or any successor forms thereto), including any registrations
requested pursuant to Section 3(b) hereof, it shall promptly give written notice
to each Stockholder, Telecom Warrant Holder, New Bridge Warrant Holder and
Acquisition Holder of its intention and, upon the written request, given within
30 days after delivery of any such notice by the Company, of any Telecom Warrant
Holder, New Bridge Warrant Holder, Investor Telecom Stockholder, Acquisition
Holder or Telecom Stockholder to include in such registration Registrable Shares
(which request shall specify the number of Registrable Shares proposed to be
included in such registration), the Company shall use its best efforts to cause
all such Registrable Shares to be included in such registration on the same
terms and conditions as the securities otherwise being sold in such
registration; PROVIDED, HOWEVER, that if (i) the managing underwriter advises
the Company that the inclusion of all shares of Common Stock proposed to be
included in such registration would interfere with the successful marketing
(including pricing) of the offering or (ii) the number of such shares exceeds
the limitations imposed by Section 3(a) below, then the number of shares of
Common Stock proposed to be included in such registration shall be included in
the following order:

     (a)  FIRST, the Primary Shares;

     (b)  SECOND, the Registrable Shares held by the Warrant Holders pro rata
based on the number of Registrable Shares issuable upon exercise of Telecom
Warrants owned of record (except in the case of Landover, beneficially owned) by
each such Warrant Holder;

     (c)  THIRD, the Registrable Shares held by the New Bridge Warrant Holders,
Investor Telecom Stockholders and Acquisition Holders pro rata based on the
number of Registrable Shares owned of record (except in the case of Landover,
beneficially owned) by each such New Bridge Warrant Holder, Investor Telecom
Stockholder and Acquisition Holder;

     (d)  FOURTH, the Registrable Shares held by the New ART Stockholders pro
rata based on the number of Registrable Shares owned of record held by each such
Investor ART Stockholder; and

     (e)  FIFTH, the Registrable Shares held by the Existing ART Stockholders
pro rata based on the number of Registrable Shares held by each such Existing
ART Stockholder.

     SECTION 3.  DEMAND REGISTRATION; LIMITATIONS.  (a)  REGISTRATION ON FORM
S-3.  At such time as the Company shall have qualified for the use of Form S-3
promulgated under the Securities Act or any successor form thereto, each of (1)
one or more Investor Telecom Stockholders, New Bridge Warrantholders or
Acquisition Holders who own beneficially in the aggregate Registrable Shares
consisting of at least 6% of the outstanding shares of the Common Stock
(collectively the "Demand Holders") and (2) one or more Telecom Warrant Holders
who own beneficially in the aggregate at least 40% of the Telecom Warrants (or
shares issued upon exercise thereof) shall have the right to request in writing
an unlimited


                                       -7-
<PAGE>

number of registrations on Form S-3 (or any successor form) of Registrable
Shares, which request or requests shall (i) specify the number of Registrable
Shares intended to be sold or disposed of, (ii) state the intended method of
disposition of such Registrable Shares, and (iii) relate to Registrable Shares
having an anticipated aggregate offering price of at least $5,000,000; PROVIDED,
THAT, if the Company is then involved in (x) a primary registration of its
shares of Common Stock under the Securities Act, (y) an acquisition of another
entity which requires registration of securities to be issued in connection
therewith or (z) a registered repurchase or acquisition of its shares of Common
Stock, then, at the request of the Company, the respective rights of the Demand
Holders and the Telecom Warrant Holders to registration pursuant to this Section
3 shall be deferred until the conditions set forth in clause (x), (y) or (z) no
longer apply except that notwithstanding such deferral, the Company shall be
obliged to complete such a registration at least once in each fiscal year;
PROVIDED, FURTHER, that the Demand Holders or Telecom Warrant Holders at the
time of such request own at least in the aggregate 50% of the securities of the
Company which they respectively owned on the date they acquired such securities;
AND PROVIDED FURTHER THAT upon the request of investors or the placement agent
in any private placement in which the Company shall receive proceeds of at least
$20,000,000 from sale of its securities, whether in a private placement for cash
or in an acquisition of assets or another Company, the Demand Holders and
Telecom Warrant Holders shall subordinate their rights under this Section 3 to
the rights of such investors or placement agent.

     (b)  LANDOVER REGISTRATION.  Commencing six months after the effective date
of a registered initial Public Offering of Primary Shares, Landover shall have
the right to request in writing an aggregate of three registrations of
Registrable Shares (of which two shall be at the expense of the Company as
provided in Section 6 below and one at Landover's expense), which request or
requests shall (i) specify the number of Registrable Shares intended to be sold
or disposed of, (ii) state the intended method of disposition of such
Registrable Shares, and (iii) relate to Registrable Shares having an anticipated
aggregate offering price of at least $5,000,000; PROVIDED, THAT, if the Company
is then involved in (x) a primary registration of its shares of Common Stock
under the Securities Act, (y) an acquisition of another entity which requires
registration of securities to be issued in connection therewith or (z) a
registered repurchase or acquisition of its shares of Common Stock, then at the
request of the Company, the rights of Landover to registration pursuant to this
Section 3A shall be deferred until the conditions set forth in clause (x), (y)
or (z) no longer apply except that notwithstanding such deferral, the Company
shall be obliged to complete such a registration at least once in each fiscal
year; AND PROVIDED FURTHER THAT upon the request of investors or the placement
agent in any private placement in which the Company shall receive proceeds of at
least $20,000,000 from sale of its securities, whether in a private placement
for cash or in an acquisition of assets, the Landover shall subordinate their
rights under this Section 3 to the rights of such investors or placement agent.


                                       -8-
<PAGE>


     (c)  CERTAIN LIMITATIONS.  Notwithstanding any other provisions of this
Agreement, in the event that the Company is requested to file any registration
statement covering Registrable Securities pursuant to Sections 2 or 3:

          (i)  the Company shall not be obligated to effect the filing of such
registration statement in any calendar year for Registrable Securities
constituting in the aggregate more than 10% of the capital stock of the Company
outstanding at the end of such year;

         (ii)  the Company shall not be obligated to effect the filing of such
registration statement during the 180 days following the effective date of any
other registration statement pertaining to an underwritten Public Offering of
Primary Shares; and

        (iii)  if, in the good faith judgment of the Company, it would not be in
the best interests of the Company and its stockholders generally for such
registration statement to be filed, the Company shall have the right to defer
such filing for a period of not more than 180 days after receipt of the request
of the relevant Demand Holders or Telecom Warrant Holders; PROVIDED, HOWEVER,
that the Company may not utilize the right set forth in this Section 3(c) more
than once in any 12-month period.

     SECTION 4.  HOLDBACK AGREEMENT.

     (a)  If the Company at any time shall register shares of Common Stock under
the Securities Act (including any registration pursuant to Section 2 or 3) for
sale to the public, no Party shall sell, make any short sale of, grant any
option for the purchase of, or otherwise dispose of any Restricted Shares (other
than those shares of Common Stock included in such registration) without the
prior written consent of the Company for a period designated by the Company in
writing to the Parties, which period shall not begin more than 10 days prior to
the effectiveness of the registration statement pursuant to which such public
offering shall be made and shall not last more than 120 days after the effective
date of such registration statement; provided that neither Ameritech nor any
member of the Advent Group shall be bound by Section 4(a) if such Stockholder
did not participate in the offering of the Company's securities which gives rise
to the limitations set forth in Section 4(a)

     (b)  In furtherance and not in  limitation of Section 4(a) above, in the
event of a registered initial public offering in the Company, each Party,
including without limitation Ameritech and the Advent Group, shall enter into a
lock-up agreement with the underwriter(s) of such offering for a reasonable
period in form agreed upon by the Company and such underwriter(s).

     SECTION 5.  PREPARATION AND FILING.  If and whenever the Company is under
an obligation pursuant to the provisions of this Agreement to use its best
efforts to effect the registration of any Registrable Shares, the Company shall,
as expeditiously as practicable:


                                       -9-
<PAGE>

     (a)  use its best efforts to cause a registration statement that registers
such Registrable Shares to become and remain effective for a period of 90 days
or until all of such Registrable Shares have been disposed of (if earlier):

     (b)  furnish, at least five business days before filing a registration
statement that registers such Registrable Shares, a prospectus relating thereto
or any amendments or supplements relating to such a registration statement or
prospectus, to one counsel selected by the holders of a majority of such
Registrable Shares (the "Selling Stockholders' Counsel"), copies of all such
documents proposed to be filed (it being understood that such five-business-day
period need not apply to successive drafts of the same document proposed to be
filed so long as such successive drafts are supplied to such counsel in advance
of the proposed filing by a period of time that is customary and reasonable
under the circumstances);

     (c)  prepare and file with the Commission such amendments and supplements
to such registration statement and the prospectus used in connection therewith
as may be necessary to keep such registration statement effective for at least a
period of 90 days or until all of such Registrable Shares have been disposed of
(if earlier) to comply with the provisions of the Securities Act with respect to
the sale or other disposition of such Registrable Shares:

     (d)  notify in writing the Selling Stockholders' Counsel promptly (i) of
the receipt by the Company of any notification with respect to any comments by
the Commission with respect to such registration statement or prospectus or any
amendment or supplement thereto or any request by the Commission for the
amending or supplementing thereof or for additional information with respect
thereto, (ii) or the receipt by the Company of any notification with respect to
the issuance by the Commission of any stop order suspending the effectiveness of
such registration statement or prospectus or any amendment or supplement thereto
or the initiation or threatening of any proceeding for that purpose and (iii) of
the receipt by the Company of any notification with respect to the suspension of
the qualification of such Registrable Shares for sale in any jurisdiction or the
initiation or threatening of any proceeding for such purposes;

     (e)  use its best efforts to register or qualify such Registrable Shares
under such other securities or blue sky laws of such jurisdictions as any seller
of Registrable Shares reasonably requests and do any and all other acts and
things which may be reasonably necessary or advisable to enable such seller of
Registrable Shares to consummate the disposition in such jurisdictions of the
Registrable Shares owned by such seller; PROVIDED, HOWEVER, that the Company
will not be required to qualify generally to do business, subject itself to
general taxation or consent to general service of process in any jurisdiction
where it would not otherwise be required so to do but for this paragraph (e);

     (f)  furnish to each seller of such Registrable Shares such number of
copies of a summary prospectus or other prospectus, including a preliminary
prospectus in conformity with the requirements of the Securities Act, and such
other documents as such seller of


                                      -10-
<PAGE>

Registrable Shares may reasonably request in order to facilitate the public sale
or other disposition of such Registrable Shares.

     (g)  use its best efforts to cause such Registrable Shares to be registered
with or approved by such other governmental agencies or authorities as may be
necessary by virtue of the business and operations of the Company to enable the
seller or sellers thereof to consummate the disposition of such Registrable
Shares;

     (h)  notify on a timely basis each seller of such Registrable Shares at any
time when a prospectus relating to such Registrable Shares is required to be
delivered under the Securities Act within the appropriate period mentioned in
paragraph  (a) of this Section, of the happening of any event as a result of
which the prospectus included in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading in light of the circumstances then existing and, at the request
of such seller prepare and furnish to such seller a reasonable number of copies
of a supplement to or an amendment of such prospectus as may be necessary so
that, as thereafter delivered to the offerees of such shares, such prospectus
shall not include an untrue statement of a material fact or omit to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in light of the circumstances then existing;

     (i)  make available for inspection by any seller of such Registrable
Shares, any underwriter participating in any disposition pursuant to such
registration statement and any attorney, accountant or other agent retained by
any such seller or underwriter (collectively, the "Inspectors"), all pertinent
financial and other records, pertinent corporate documents and properties of the
Company collectively, the "Records"), as shall be reasonably necessary to enable
them to exercise their due diligence responsibility, and cause the Company's
officers, directors and employees to supply all information (together with the
Records, the "Information") reasonably requested by any such Inspector in
connection with such registration statement.  Any of the Information which the
Company determines in good faith to be confidential, and of which determination
the Inspectors are so notified, shall not be disclosed by the Inspectors unless
(i) the disclosure of such information is necessary to avoid or correct a
misstatement or omission in the registration statement, (ii) the release of such
Information is ordered pursuant to a subpoena or other order from a court of
competent jurisdiction or (iii) such Information has been made generally
available to the public.  The seller of Registrable Shares agrees that it will,
upon learning that disclosure of such Information is sought in a court of
competent jurisdiction, give notice to the Company and allow the Company, at the
Company's expense, to undertake appropriate action to prevent disclosure of the
Information deemed confidential.

     (j)  use its best efforts to obtain from its independent certified public
accountants "cold comfort" letters in customary form and at customary times and
covering matters of the type customarily covered by cold comfort letters;


                                      -11-
<PAGE>

     (k)  use its best efforts to obtain from its counsel an opinion or opinions
in customary form;

     (l)  provide a transfer agent and registrar (which may be the same entity
and which may be the Company) for such Registrable Shares;

     (m)  issue to any underwriter to which any seller of Registrable Shares may
sell shares on such offering certificates evidencing such Registrable Shares;

     (n)  register such Registrable Shares on any national securities exchange
on which any shares of the Common Stock are listed or, if the Common Stock is
not listed on a national securities exchange, use its best efforts to qualify
such Registrable Shares for inclusion on the automated quotation system of the
National Association of Securities Dealers, Inc.  (the "NASD") or such national
securities exchange as the holders of a majority of such Registrable Shares
shall request;

     (o)  otherwise use its best efforts to comply with all applicable rules and
regulations of the Commission and make available to its security holders, as
soon as reasonably practicable, earnings statements (which need not be audited)
covering a period of 12 months beginning within three months after the effective
date of the registration statement, which earnings statements shall satisfy the
provisions of Section 11(a) of the Securities Act; and

     (p)  use its best efforts to take all other steps necessary to effect the
registration of such Registrable Shares contemplated hereby.

     SECTION 6.     EXPENSES.  All expenses incurred by the Company in complying
with Section 5, including, without limitation, all registration and filing fees
(including all expenses incident to filing with the NASD), fees and expenses of
complying with securities and blue sky laws, printing expenses, fees and
expenses of the Company's counsel and accountants and fees and expenses of the
Selling Stockholders' Counsel, shall be paid by the Company; PROVIDED, HOWEVER,
that all underwriting discounts and selling commissions applicable to the
Registrable Shares shall be borne by the seller or sellers thereof, in
proportion to the number of Registrable Shares sold by such seller or sellers.

     SECTION 7.  INDEMNIFICATION.

     (a)  The Company agrees to indemnify, to the extent permitted by law, each
holder of Registrable Shares, its officers and directors and each Person who
controls such holder (within the meaning of the Securities Act) against all
losses, claims, damages, liabilities and expenses caused by any untrue or
alleged untrue statement of material fact contained in any registration
statement, prospectus or preliminary prospectus or any amendment thereof or
supplement thereto or any omission or alleged omission of a material fact
required to be stated


                                      -12-
<PAGE>

therein or necessary to make the statements therein not misleading, except
insofar as the same are caused by or contained in any information furnished in
writing to the Company by such holder expressly for use therein or by such
holders failure to deliver a copy of the registration statement or prospectus or
any amendments or supplements thereto after the Company has furnished such
holder with a sufficient number of copies of the same.  In connection with an
underwritten offering, the Company shall indemnify such underwriters, their
officers and directors and each Person who controls such underwriters (within
the meaning of the Securities Act) to the same extent as provided above with
respect to the indemnification of the holders of Registrable Shares.

     (b)  In connection with any registration statement in which a holder of
Registrable Shares is participating, each such holder shall furnish to the
Company in writing such information and affidavits as the Company reasonably
requests for use in connection with any such registration statement or
prospectus and, to the extent permitted by law, shall indemnify the Company, its
directors and officers and each Person who controls the Company (within the
meaning of the Securities Act) against any losses, claims, damages, liabilities
and expenses resulting from any untrue or alleged untrue statement of material
fact contained in the registration statement, prospectus or preliminary
prospectus or any amendment thereof or supplement thereto or any omission or
alleged omission of a material fact required to be stated therein or necessary
to make the statements therein not misleading, but only to the extent that such
untrue statement or omission is contained in any information or affidavit so
furnished in writing by such holder; provided that the obligation to indemnify
shall be individual, not joint and several, for each holder and shall be limited
to the net amount of proceeds received by such holder from he sale of
Registrable Shares pursuant to such registration statement.

     (c)  Any Person entitled to indemnification hereunder shall (i) give prompt
written notice to the indemnifying party of any claim with respect to which it
seeks indemnification (provided that the failure to give prompt notice shall not
impair any Person's right to indemnification hereunder to the extent such
failure has not prejudiced the indemnifying party) and (ii) unless in such
indemnified party's reasonable judgment a conflict of interest between such
indemnified party's reasonable judgment a conflict of interest between such
indemnified and indemnifying parties may exist with respect to such claim,
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party.  If such defense is assumed,
the indemnifying party shall not be subject to any liability for any settlement
made by the indemnified party without its consent (but such consent shall not be
unreasonably withheld).  An indemnifying party who is not entitled to, or elects
not to, assume the defense of a claim shall not be obligated to pay the fees and
expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the reasonable judgment
of any indemnified party a conflict of interest may exist between such
indemnified party and any other of such indemnified parties with respect to such
claim.


                                      -13-
<PAGE>

     (d)  The indemnification provided for under this Agreement shall remain in
full force and effect regardless of any investigation made by or on behalf of
the indemnified party or any officer, director or controlling Person of such
indemnified party and shall survive the transfer of securities.  The Company
also agrees to make such provisions, as are reasonably requested by any
indemnified party for contribution to such party in the event the Company's
indemnification is unavailable for any reason.

     SECTION 8.  UNDERWRITING AGREEMENT.  No Person may participate in any
registration hereunder which is underwritten unless such Person (i) agrees to
sell such Person's securities on the basis provided in any underwriting
arrangements approved by the Person or Persons entitled hereunder to approve
such arrangements and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents required
under the terms of such underwriting arrangements; provided that no holder of
Registrable Shares included in any underwritten registration shall be required
to make any representations or warranties to the Company or the underwriters
(other than representations and warranties regarding such holder and such
holder's intended method of distribution) or to undertake any indemnification
obligations to the Company or the underwriters with respect thereto, except as
otherwise provided in Section 7 above.

     SECTION 9.  INFORMATION BY HOLDER.  Each holder of Registrable Shares to be
included in any registration shall furnish to the Company such written
information regarding such holder and the distribution proposed by such holder
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.

     SECTION 10. EXCHANGE ACT COMPLIANCE.  From and after the Registration Date
or such earlier date as a registration statement filed by the Company pursuant
to the Exchange Act relating to any class of the Company's securities shall have
become effective, the Company shall comply with all of the reporting
requirements of the Exchange Act and with all other public information reporting
requirements of the Commission which are conditions to the availability of Rule
144 for the sale of the Common Stock.  The Company shall cooperate with each
Stockholder in supplying such information as may be necessary for such
Stockholder to complete and file any information reporting forms presently or
hereafter required by the Commission as a condition to the availability of Rule
144.

     SECTION 11. NO CONFLICT OF RIGHTS.  The Company represents and warrants to
the Stockholders that the registration rights granted to the Stockholders hereby
do not conflict with any other registration rights granted by the Company.  The
Company shall not, after the date hereof, grant any registration rights which
conflict with or impair the registration rights granted hereby.


                                      -14-
<PAGE>


     SECTION 12.  RESTRICTION ON TRANSFER.  (a)  The Restricted Shares shall not
be transferable except upon the conditions specified in this Section, which
conditions are intended to insure compliance with the provisions of the
Securities Act.

     (b)  Each certificate representing Restricted Shares shall (unless
otherwise permitted by the provisions of paragraph (c) and (d) below) be stamped
or otherwise imprinted with a legend in substantially the following form:

     "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR
     INVESTMENT AND HAVE  NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933.
     THESE SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH
     REGISTRATION OR AN EXEMPTION THEREFROM UNDER SUCH ACT.  ADDITIONALLY, THE
     TRANSFER OF THESE SECURITIES IS SUBJECT TO THE CONDITIONS SPECIFIED IN (i)
     SECTION 12 OF THE REGISTRATION RIGHTS AGREEMENT DATED [THE DATE OF THIS
     AGREEMENT], AMONG ADVANCED RADIO TELECOM CORP.  ADVANCED RADIO TECHNOLOGIES
     CORPORATION AND CERTAIN OTHER SIGNATORIES THERETO AND (ii) THE RESTATED AND
     AMENDED STOCKHOLDERS AGREEMENT DATED [DATE OF AGREEMENT] AMONG ADVANCED
     RADIO TELECOM CORP.  ADVANCED RADIO TECHNOLOGIES CORPORATION AND CERTAIN
     OTHER SIGNATORIES THERETO, AND NO TRANSFER OF THESE SECURITIES SHALL BE
     VALID OR EFFECTIVE UNTIL SUCH CONDITIONS HAVE BEEN FULFILLED UPON THE
     FULFILLMENT OF CERTAIN OF SUCH CONDITIONS, ADVANCED RADIO TELECOM CORP.,
     AND ADVANCED RADIO TECHNOLOGIES CORPORATION HAVE AGREED TO DELIVER TO THE
     HOLDER HEREOF A NEW CERTIFICATE, NOT BEARING THIS LEGEND, FOR THE
     SECURITIES REPRESENTED HEREBY REGISTERED IN THE NAME OF SUCH HOLDER. COPIES
     OF SUCH AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE
     HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF ADVANCED RADIO
     TECHNOLOGIES CORPORATION."

     (c)  The holder of any Restricted Shares agrees, prior to any Transfer of
any Restricted Shares, to give written notice to the Company of such holder's
intention to effect such Transfer and to comply in all other respects with the
provisions of this Section.  Each such notice shall describe the manner and
circumstances of the proposed Transfer.  Upon request by the Company, the holder
delivering such notice shall deliver a written opinion, addressed to the
Company, of counsel for the holder of Restricted Shares, stating that in the
opinion of such counsel (which opinion and counsel shall be reasonably
satisfactory to the Company) such proposed Transfer does not involve a
transaction requiring registration or qualification of such Restricted Shares
under the Securities Act or the securities or "blue sky" laws of any state of
the United States.  Such holder of Restricted Shares shall be entitled to
Transfer such


                                      -15-
<PAGE>

Restricted Shares in accordance with the terms of the notice delivered to the
Company, if the Company does not reasonably object to such Transfer and request
such opinion within five days after delivery of such notice, or, if it requests
such opinion, does not reasonably object to such Transfer within five days after
delivery of such opinion.  Each certificate or other instrument evidencing the
securities issued upon the Transfer of any Restricted Shares (and cash
certificate or other instrument evidencing any untransferred balance of such
Registered Shares) shall bear the legend set forth in paragraph (b) above unless
(i) in such opinion of counsel registration of any future Transfer is not
required by the applicable provisions of the Securities Act or (ii) the Company
shall have waived the requirement of such legends.

     (a)  Notwithstanding the foregoing provisions of this Section, the
restrictions imposed by this Section upon the transferability of any Restricted
Shares shall cease and terminate when (i) any such Restricted Shares are sold or
otherwise disposed of (A) pursuant to an effective registration statement under
the Securities Act or (B) in a transaction contemplated by paragraph (c) above
which does not require that the Restricted Shares so transferred bear the legend
set forth in paragraph (b) hereof, or (ii) the Company has completed a
registered public offering of its securities and the holder of such Restricted
Shares has met the requirements for Transfer of such Restricted Shares under
Rule 144(k).  Whenever the restrictions imposed by this Section shall terminate,
the holder of any Restricted Shares as to which such restrictions have
terminated shall be entitled to receive from the Company, without expense, a new
certificate not bearing the restrictive legend set forth in paragraph (b) above
and not containing any other reference to the restrictions imposed by this
Section.

     SECTION 13.  TERMINATION.  This Agreement shall terminate and be of no
further use or effect when there shall not be any Restricted Shares.

     SECTION 14.  SUCCESSORS AND ASSIGNS.  This Agreement shall bind and inure
to the benefit of the Company and the Stockholders and, subject to Section 15
their respective successors and assigns.

     SECTION 15.  ASSIGNMENT.  This Agreement, and the rights and obligations of
each Party may be assigned by such Party (i) to any Affiliate of such Party or
(ii) to any person or entity to which Registrable Shares representing at least
10% of the Company's issued and outstanding capital stock are transferred by
such Party; PROVIDED, HOWEVER, that such transferee shall, as a condition to the
effectiveness of such assignment, be required to exercise a counterpart to this
Agreement agreeing to be treated like the transferring Party, whereupon such
transferee shall have the benefits of, and shall be subject to the restrictions
contained in, this Agreement.  Any attempted transfer or assignment not in
compliance with the foregoing sentence of this Section 15 shall be invalid.

     SECTION 16.  ENTIRE AGREEMENT.  This Agreement contains the entire
agreement among the parties with respect to the subject matter hereof and
supersedes all prior arrangements or understandings with respect hereto.


                                      -16-
<PAGE>

     SECTION 17.  NOTICES.  All notices, consents and other communications
hereunder to any party shall be deemed to be sufficient if contained in a
written instrument and shall be deemed to have been duly given when delivered in
person, by telecopy, by nationally-recognized overnight courier, or by first
class registered or certified mail, postage prepaid, addressed to such party at
the address set forth below or such other address as may hereafter be designated
in writing by the addressee to the addressor:

     (i)  If to the Company, to:

               Advanced Radio Telecom Corp.
                    500 108th Ave., N.E. Suite 1910
                    Bellevue, WA  98004
                    Attention:  Vernon L.  Fotheringham, Chairman
                    Fax:  (206) 646-6570

                         with a copy to:

               Pierson, Burnett & Hanley
                    1200 Nineteenth Street, N.W.
                    Washington, D.C.  20036
                    Attention:  W. Theodore Pierson, Jr.
                    Fax:  (202) 466-3055

                         and

               Hahn & Hessen LLP
                    350 Fifth Avenue
                    New York, NY  10118
                    Attention:  James Kardon, Esq.
                    Fax:  (212) 594-7167

     (ii)      to any Stockholder, at his or its address set forth on
Schedule I.

All such notices, requests, consents and other communications shall be deemed to
have been delivered (a) in the case of personal delivery or delivery by
telecopy, on the date of such delivery, (b) in the case of nationally-recognized
overnight courier on the next business day, and (c) in the case of mailing, on
the third business day following such mailing.

     SECTION 18.  MODIFICATIONS; AMENDMENTS; WAIVERS.  This Agreement may not be
modified, or amended, except by an instrument in writing signed (i) before the
Merger by (A) the Company, (B) ART, (C) the holders of at least 85% of the
outstanding voting shares of ART owned by the ART Stockholders, and (D) the
holders of at least 85% of the outstanding


                                      -17-
<PAGE>

voting shares owned by the Investor Telecom Stockholders, including the holders
of at least 50% of the shares of Series E Preferred Stock if any such shares are
outstanding, and (ii) after the Merger by (A) the Company and (B) the holders of
at least 85% of the outstanding voting shares owned by the Stockholders,
including the holders of at least 50% of the shares of Series E Preferred Stock
if any such shares are outstanding; PROVIDED, HOWEVER, that (x) no modification
or amendment shall discriminate against any Stockholder without the consent of
such Stockholder, and (y) any modification or amendment to this Agreement the
effect of which is solely to waive the rights of any or all of the parties
hereto may be effected (i) before the Merger by (A) the Company, (B) ART,
(C) the holders of at least 67% of the oustanding voting shares of ART owned by
the ART Stockholders, and (D) the holders of at least 67% of the outstanding
voting shares owned by the Investor Telecom Stockholders, and (ii) after the
Merger by (A) the Company, and (B) the holders of at least 67% of the oustanding
voting shares owned by the Stockholders.  This Section may only be amended with
the consent of all parties to this Agreement.

     SECTION 19.  COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, and each such counterpart hereof shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.

     SECTION 20.  HEADINGS.  The headings of the various sections of this
Agreement have been inserted for convenience of reference only and shall not be
deemed to be a part of this Agreement.

     SECTION 21.  SEVERABILITY.  It is the desire and intent of the parties that
the provisions of this Agreement be enforced to the fullest extent permissible
under the law and public policies applied in each jurisdiction in which
enforcement is sought.  Accordingly, if any provision of this Agreement would be
held in any jurisdiction to be invalid, prohibited or unenforceable for any
reason, such provision, as to such jurisdiction, shall be ineffective, without
invalidating the remaining provisions of this Agreement or affecting the
validity or enforceability of such provision in any other jurisdiction.
Notwithstanding the foregoing, if such provision could be more narrowly drawn so
as not to be invalid, prohibited or unenforceable in such jurisdiction, it
shall, as to such jurisdiction, be so narrowly drawn, without invalidating the
remaining provisions of this Agreement or affecting the validity or
enforceability of such provision in any other jurisdiction.

     SECTION 22.  ACKNOWLEDGMENT.  Each of the Stockholders acknowledges that
such Stockholder has reviewed and understands, and has had an opportunity to ask
questions and has received adequate answers of management and counsel of ART and
the Company concerning, the documents embodying the transactions, actions and
amendments set forth in this Agreement.


                                      -18-
<PAGE>

     SECTION 23.  GOVERNING LAW.  This Agreement shall be governed by and
construed in accordance with the laws of the State of New York, without giving
effect to principles governing conflicts of laws.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement on the
date first written above.


                                        ADVANCED RADIO TELECOM CORP.


                                        By: _______________________________
                                            Name:
                                            Title:

                                        ADVANCED RADIO TECHNOLOGIES
                                        CORPORATION


                                        By: _______________________________
                                            Name:
                                            Title:

                                        LANDOVER HOLDINGS
                                        CORPORATION


                                        By: ______________________________
                                            Name:
                                            Title:


                                        HEDGEROW CORPORATION OF
                                        MAINE


                                        By:_______________________________
                                            Name:
                                            Title:


                                      -19-
<PAGE>

                                        TORO FINANCIAL CORP.


                                        By: _______________________________
                                            Name:  Dan Gulick
                                            Title: President


                                        E2 HOLDINGS, L.P.

                                        By:  AVR MANAGEMENT, INC.
                                             General Partner


                                        By: _______________________________
                                            Laurence Zimmerman
                                              President


                                        E2-2 HOLDINGS, L.P.

                                        By:  AVR MANAGEMENT, INC.
                                             General Partner


                                        By: _______________________________
                                            Laurence Zimmerman
                                              President


                                        E1 HOLDINGS, L.P.

                                        By:  AVR MANAGEMENT, INC.
                                             General Partner


                                        By: _______________________________
                                            Laurence Zimmerman
                                              President


                                      -20-
<PAGE>

                                        E2-3 HOLDINGS, L.P.

                                        By:  AVR-3, INC.
                                             General Partner


                                        By: _______________________________
                                            Laurence Zimmerman
                                              President


                                        ______________________________
                                        CAROLYN CUNNINGHAM


                                        ______________________________
                                        SAMUEL B. KELLETT


                                        ______________________________
                                        BRUCE PINKNEY


                                        ______________________________
                                        LESLIE R. PARTEE


                                        ______________________________
                                        PAUL WITHINGTON


                                        KELLETT INVESTMENT
                                        CORPORATION


                                        By: __________________________
                                            Name:
                                            Title:


                                        ______________________________
                                        Vernon L. Fotheringham


                                      -21-
<PAGE>

                                        _____________________________
                                        W. Theodore Pierson, Jr.


                                        HIGH SKY LIMITED PARTNERSHIP

                                        By: HIGH SKY, INC., its General
                                            Partner


                                        By: _____________________________
                                            Name:  Leland H. Phillips
                                            Title: President


                                        HIGH SKY II LIMITED PARTNERSHIP

                                        By: HIGH SKY, INC., its General
                                            Partner


                                        By: _____________________________
                                            Name:
                                            Title: President


                                        EXTENDED COMMUNICATIONS,
                                        INC.


                                        By: _____________________________
                                            Name:
                                            Title:


                                        SINTRA FUND, LTD.


                                        By: _____________________________
                                            Name:
                                            Title:


                                      -22-
<PAGE>

                                        GLOBAL PRIVATE EQUITY
                                        II, L.P.

                                        By: ADVENT INTERNATIONAL
                                            its General Partner


                                        By: _____________________________
                                            Name:
                                            Title:


                                        ADVENT LIMITED PARTNERSHIP

                                        By: ADVENT INTERNATIONAL
                                            CORPORATION, its
                                            General Partner


                                        By: _____________________________
                                            Name:
                                            Title:



                                        ADVENT INTERNATIONAL
                                        INVESTORS II LIMITED
                                        PARTNERSHIP

                                        By: ADVENT INTERNATIONAL
                                            CORPORATION, its
                                            General Partner


                                        By: _____________________________
                                            Name:
                                            Title:


                                      -23-
<PAGE>

                                        PFG CORP.



                                        By: _____________________________
                                            Name:
                                            Title:


                                        TELECOM PARTNERS, L.P.


                                        By: _____________________________
                                            James J. Pinto,
                                            General Partner


                                            _____________________________
                                            Steven Osman


                                            _____________________________
                                            William Weinstein



                                        AMERITECH DEVELOPMENT
                                        CORPORATION


                                        By: ________________________
                                            Name:
                                            Title:




                                      -24-
<PAGE>

                                        COMMCOCCC, INC.


                                        By: ________________________
                                            Name:
                                            Title:


                                        By: ________________________
                                            Name:
                                            Title:


                                        COLUMBIA CAPITAL CORPORATION


                                        By: ________________________
                                            Name:
                                            Title:



                                        COMMCO, L.L.C.


                                        By: ________________________
                                            Name:
                                            Title:


                                      -25-
<PAGE>

                                                                      SCHEDULE I

                                  STOCKHOLDERS

NAME AND ADDRESS

PART 1(a) - EXISTING LANDOVER STOCKHOLDERS

Landover Holdings Corporation
Hedgerow Corp.
Toro Financial Corp.
E2 Holdings, L.P.
E2-2 Holdings, L.P.
667 Madison Avenue
New York, New York  10021

PART 1(b) - NEW LANDOVER STOCKHOLDERS

E1 Holdings, L.P.
E2-3 Holdings, L.P.
667 Madison Avenue
New York, New York  10021

PART 1(c) - NEW UNAFFILIATED STOCKHOLDERS

Carolyn Cunningham
Samuel B. Keller
Bruce Pinkney
Leslie R. Partee
Paul Withington
Kellett Investment Corporation
c/o Kellett Investment Corporation
200 Galleria Parkway
Suite 1800
Atlanta, GA  30339
Attention:  John Cunningham

With a copy to:
     Troutman Sanders LLP
     NationsBank Plaza
     600 Peachtree Street, N.E., Suite 6200
     Attention:  Hazen Dempster, Esq.


                                      -26-
<PAGE>

Global Private Equity II L.P.
Advent Limited Partnership
Advent International Investors II Limited Partnership
c/o Advent International Corp.
101 Federal Street
Boston, MA  02110
Attention:  Andrew Fillat

With a copy to:
     Hutchins, Wheeler & Dittmar, P.C.
     101 Federal Street
     Boston, MA  02110
     Attention:  Anthony Medaglia, Esq.

Ameritech Development Corporation
30 South Wacker Drive
Chicago, IL  60606
Attention:  Greg Smitherman and Kenneth Dunn, Esq.

With a copy to:
     Kirkland & Ellis
     200 East Randolph Drive
     Chicago, IL  60601
     Attention:  Mark B. Tresnowski, Esq.

PART II(a) - EXISTING ART STOCKHOLDERS

Vernon I. Fotheringham
Advanced Radio Telecom Corp.
500 108th Ave., N.E., Suite 1910
Bellevue, WA  98004

W. Theodore Pierson, Jr.
Pierson, Burnett & Hanley
1200 Nineteenth Street, N.W.
Washington, D.C.  20036

High Sky Limited Partnership
c/o Frank S. Phillips Company
6106 MacArthur Blvd.
Bethesda, MD  20816


                                      -27-
<PAGE>

High Sky II Limited Partnership
c/o Frank S. Phillips Company
6106 MacArthur Blvd.
Bethesda, MD 20816

Extended Communications, Inc.
22904 NE 19th Drive
Redmond, VA  98053

PART II(b) - NEW ART STOCKHOLDERS:

Sintra Fund, Ltd.
c/o Sintra Capital Corp.
515 Madison Avenue
New York, New York  10021

Stephen Osman
57 West Hill Road
Stamford, CT  06902

PFG Corp.
c/o James Pinto
Resource Holdings
520 Madison Avenue
New York, New York 10022

Telecom Partners, L.P.
c/o James Pinto
Resource Holdings
520 Madison Avenue
New York, New York  10022

William Weinstein
c/o Feltman & Company
1800 First Union Plaza
999 Peachtree Street, N.E.
Atlanta, GA  30309


                                      -28-
<PAGE>

PART III(A) - HOLDERS OF BRIDGE WARRANTS

Ameritech Development Corp.
30 South Wacker Drive
37th Floor
Chicago, Illinois 60606

Global Private Equity II L.P.
Advent Int'l Investors II L.P.
Advent Partners L.P.
c/o Advent International Corp.
101 Federal Street
Boston, MA  02110

Charles H. Abraham
Charles Department Store
1314 Washington Street
Vicksburg, Mississippi  39180

Blue Ridge Associates
4425 Corporation Lane
Suite 400
Virginia Beach, VA  23462

Betty Demetree
3740 Beach Boulevard
Suite 300
Jacksonville, Florida 32207

Jack C. Demetree, Sr.
3740 Beach Boulevard
Suite 300
Jacksonville, Florida  32207

William C. Demetree, as Trustee
3221 Ardsley Drive
Orlando, Florida  32804

W.W. Gay
W.W. Gay Mechanical Contractors, Inc.
524 Stockton Street
Jacksonville, Florida  32204


                                      -29-
<PAGE>

Ron Helinger
19 Paradise Lane
Treasure Island, Florida  33706

John Lupo
6655 Epping Forest Way North
Jacksonville, Florida  32217

Marc Associates
4425 Corporation Lane
Ste. 400
Virginia Beach, VA  23462

W.A. McRae, Jr.
1725 Memorial Park Drive
Jacksonville, Florida  32204

CL Investment Partnership III
(Ammon/Mait Partnership)
3 East 54th Street
New York, New York  10022

Edward B. Salem
7002 Epping Forest Ter.
Jacksonville, Florida  32217

Jack L. Scott
1725 Memorial Park Drive
Jacksonville, Florida  32204

Dr. Ralph Simon
1320 Park Avenue
Clinton, Oklahoma  73601

Terry Family Partners, Ltd.
C. Herman Terry, President of
CHT Corporation
1301 Riverplace Boulevard
Suite 2216
Jacksonville, Florida 32207


                                      -30-
<PAGE>

Gerald Murphy
10205 Mission Road
Leawood, Kansas  66206

James C. Cook
4837 Water Oak Road, #12
Charlotte, NC  28211

Steven Wolf
8300 College Boulevard
Overland Park, Kansas  66210

James Kardon
74 Brewster Road
Scarsdale, New York 10583

The Barkett Partnership
120 South Lynwood
Wichita, Kansas  67218

F& H Investments
c/o Fred Schramm, Jr.
3740 Beach Boulevard
Suite 300
Jacksonville, Florida  32207

Matthews, Jackson, Warnock Joint Venture
3740 Beach Boulevard
Suite 300
Jacksonville, Florida  32207

David H. Levin
c/o Levin, Middlebrooks, Mabie, Thomas, Mays & Mitchell, P.A.
316 S. Baylen Street
Pensacola, Florida  32501


                                      -31-
<PAGE>

PART III(b) - HOLDERS OF INDEMNITY WARRANTS

ALJN Demetree Trust

Jack C. Demetree
Demetree Brothers
3740 Beach Boulevard, Suite 300
Jacksonville, Florida  32207

Mark C. Demetree
c/o North American Salt Co.
8300 College Boulevard
Overland Park, KS  66210

Christopher C. Demetree

Landover Holdings Corporation
667 Madison Avenue
New York, New York  10021

Pecunia Capital Management, Inc.

PART III(c) - HOLDERS OF NEW BRIDGE WARRANTS

Columbia Capital Corporation
201 North Union Street, Suite 300
Alexandria, VA  22314

Commco, L.L.C.
4513 Pin Oak Court
Sioux Falls, SD  57103


                                      -32-

<PAGE>

                                                                   EXHIBIT 10-26


                         RESTATED AND AMENDED MERGER AGREEMENT AND PLAN OF
                         REORGANIZATION, dated June 26, 1996, among ADVANCED
                         RADIO TELECOM CORP. (formerly known as ADVANCED RADIO
                         TECHNOLOGY, LTD.), a Delaware corporation ("TELECOM"),
                         ADVANCED RADIO TECHNOLOGIES CORPORATION, a Delaware
                         corporation ("ART") and ART MERGER CORPORATION, a
                         Delaware corporation ("Merger Sub").


     TELECOM and ART entered into a Merger Agreement and Plan of Reorganization,
dated February 2, 1996 (the "Old Merger Agreement") and have determined to amend
and restate the Old Merger Agreement and revise the merger and plan of
reorganization contemplated therein.  ART has formed a wholly owned subsidiary,
Merger Sub, which has and will not carry out any business and which has and will
not take any action other than entering into this Agreement.  The parties agree
that the Old Merger Agreement is amended and restated in its entirety by this
Agreement.

     The respective Boards of Directors of TELECOM, ART and Merger Sub deem it
advisable and in the best interests of such corporations and their respective
stockholders that Merger Sub be merged with and into TELECOM on the terms and
conditions set forth in this Agreement.

     Accordingly, the parties agree as follows:

     DEFINITIONS.  As used in this Agreement and in any amendments thereto, the
following terms shall have the following meanings respectively:

     (a) "Closing" shall refer to the closing under this Agreement as described
in Section 6.

     (b) "Effective Time" shall mean the date and time when the Merger becomes
effective pursuant to the General Corporation Law of the State of Delaware
("GCL").

     (c) "Merger" shall refer to the merger of Merger Sub into and with TELECOM
as provided in Section 1.

     (d) "ART Common Stock" shall refer to the Common Stock, $0.001 par value
per share, of ART.

     (e) "TELECOM Common Stock" shall refer to the Common Stock, $0.001 par
value per share, of TELECOM.


<PAGE>

     1.   THE MERGER.  Merger Sub shall be merged into and with TELECOM upon the
terms set forth in this Agreement in a transaction intended to qualify as a
reorganization described in Section 36B(a)(1)(B) of the Internal Revenue Code.

     2.   CERTIFICATE OF MERGER.  After satisfaction or waiver of all conditions
established herein to the obligations of the parties, TELECOM shall file with
the Secretary of State of the State of Delaware a duly executed Certificate of
Merger in the form of ANNEX I (the "Certificate of Merger").  The parties shall
use their best efforts to cause such conditions to be fulfilled as soon as
possible.

     3.   EFFECT OF MERGER.  The effect of the Merger shall be as provided in
this Agreement, the Certificate of Merger and the GCL.  At the Effective Time:

          (a)  TELECOM shall be the surviving corporation in the Merger (in such
     capacity, the "Surviving Corporation");

          (b)  the certificate of incorporation of the Surviving Corporation
     shall be as set forth on EXHIBIT A to ANNEX I hereto, so that as amended,
     in its entirety it shall be substantially identical to the Certificate of
     Incorporation of Merger Sub as restated and amended immediately prior to
     the Effective Time;

          (c)  the Bylaws of the Surviving Corporation shall be as set forth on
     ANNEX II hereto, so that, as amended, in their entirety they shall be
     substantially identical to the Bylaws of Merger Sub, as amended immediately
     prior to the Effective Time;

          (d)  the initial directors of the Surviving Corporation shall be those
     persons who immediately prior to the Effective Time were serving as the
     directors of Merger Sub to hold office in accordance with the Certificate
     of Incorporation and Bylaws of the Surviving Corporation until their
     successors are duly elected or appointed;

          (e)  the initial officers of the Surviving Corporation shall be those
     persons who immediately prior to the Effective Time were serving as the
     officers of Merger Sub until their successors are duly elected or
     appointed;

          (f)  the corporate existence, franchises and rights of TELECOM, with
     its purposes, powers and objects, shall continue unaffected and unimpaired
     by the Merger, and TELECOM shall succeed to and be fully vested insofar as
     permitted by law and not otherwise expressly provided herein, with the
     corporate

<PAGE>

     existence, identity and all rights, franchises, assets, liabilities and
     obligations of Merger Sub, all as set forth in and subject to Section 259
     of the GCL;

          (g)  the name of the Surviving Corporation shall be changed to "ART
     Licensing Corporation"; and

          (h)  the separate existence and corporate organization of Merger Sub
     shall cease.

     4.   TREATMENT OF SHARES.  At the Effective Time, by virtue of the Merger
and without any action on the part of any stockholder of ART, TELECOM, Merger
Sub or their stockholders:

          (a)  each share of Common Stock, $.01 par value per share, of Merger
     Sub outstanding immediately prior to the Effective Time shall be converted
     into one share of TELECOM Common Stock;

          (b)  each issued share of TELECOM Common Stock (excluding any shares
     to be cancelled pursuant to section 4(f)) outstanding immediately prior to
     the Effective Time shall be converted into the right to receive one share
     of ART Common Stock;

          (c)  the sole outstanding share of ART Series A Preferred Stock, $.001
     par value per share, held by TELECOM, shall be cancelled;

          (d)  each outstanding option to purchase TELECOM Common Stock issued
     pursuant to TELECOM's Restated Equity Incentive Plan, shall be replaced by
     an option of similar tenor under ART's Equity Incentive Plan in accordance
     with the terms thereof;

          (e)  no fractional shares of ART Common Stock will be issued as a
     result of the Merger, either at the Closing or at the time of issuance of
     certificates in the names of the TELECOM stockholders.  In lieu of the
     issuance of fractional shares, each holder of TELECOM Common Stock who
     otherwise would be entitled to receive a fractional share of ART shall
     receive one share of ART Common Stock; and

          (f)  Each outstanding share of TELECOM Common Stock held in treasury
     of TELECOM or owned by ART immediately prior to Effective Time, shall by
     virtue of the Merger and without any action on the part of the holder
     thereof, cease to be outstanding, be canceled and retired without payment
     of any consideration therefor and cease to exist.

     5.   FURTHER ASSURANCES.  If at any time after the Effective Time, TELECOM
shall consider or be advised that any

<PAGE>

further assignments or assurances in law or any other things are necessary or
desirable to vest, perfect or confirm, of record or otherwise, in TELECOM the
title to any property or right of TELECOM acquired or to be acquired by reason
of or as a result of the Merger, the officers of Merger Sub in office
immediately prior to the Effective Time shall in the name and on behalf of
Merger Sub have and may exercise power and authority to execute and deliver all
such proper deeds, assignments and assurances in law and do all things necessary
and proper to vest, perfect or confirm title to such property or rights in
TELECOM and otherwise to carry out the purposes of this Agreement, and the
proper officers and directors of TELECOM are hereby additionally authorized in
the name of Merger Sub or otherwise to take any and all such action.

     6.   CLOSING AND EXCHANGE OF STOCK CERTIFICATES.

          (a)  The Closing (provided that the Effective Time shall already have
arrived) will take place at 10:00 A.M. New York time on the date of the
Effective Time, or at such other time as the parties to this Agreement, acting
through their Boards of Directors or the Executive Committees thereof, may
mutually agree.  The place of Closing will be at the offices of Hahn & Hessen
LLP, 350 Fifth Avenue, New York, New York or at such other place as may be
mutually agreed upon by the parties.

          (b)  As soon as practicable after the Effective Time, each holder of
shares of TELECOM Common Stock outstanding immediately prior to the Effective
Time (excluding shares to be cancelled pursuant to 4(f)) shall surrender the
certificate or certificates representing such shares to ART and shall receive in
exchange therefor a certificate or certificates representing the number of whole
shares of ART Common Stock which such holders shall be entitled to receive as
provided in Section 4.  The certificate or certificates so surrendered shall be
duly endorsed as ART may require.  Subject to the following provisions of this
Section 6(b), after the Effective Time each certificate which represented
outstanding shares of TELECOM Common Stock prior to the Effective Time shall be
deemed for all corporate purposes to evidence the ownership of the shares of ART
Common Stock provided in Section 4.  No dividend or other distribution payable
with respect to the ART Common Stock shall be paid to any holder of any
certificate representing shares of TELECOM Common Stock issued and outstanding
immediately prior to the Effective Time until such holder surrenders such
certificate for exchange as provided in this Section 6(b).

          (c)  All shares of ART Common Stock for and into which shares of
TELECOM Common Stock shall have been exchanged and converted pursuant to this
Agreement shall be deemed to have been issued in full satisfaction of all rights
pertaining to such exchanged and converted shares.  Except for such rights and
except as provided in Section 6(b), the holder of certificate(s) representing
shares of TELECOM Common Stock issued and

<PAGE>

outstanding immediately prior to the Effective Time shall have no rights with
respect to such shares other than to surrender such certificate or certificates
pursuant to Section 6(b).

     7.   REPRESENTATIONS, WARRANTIES AND COVENANTS OF ART.  ART represents,
warrants and agrees as follows:

          (a)  ART is a corporation duly incorporated, validly existing and in
good standing under the laws of the State of Delaware with corporate power and
authority to carry on the business in which it is engaged, to own, lease, and
operate its properties, to execute and deliver this Agreement and to perform its
obligations under this Agreement;

          (b)  The authorized capital stock of ART consists of 100,000,000
shares of ART Common Stock, $.001 par value per share, of which 10,013,055
shares are issued and outstanding on the date of this Agreement, and 10,000,000
shares of serial preferred stock, $.001 par value per share, of which 1 share of
Series A Preferred Stock (the "Series A Preferred Stock") is issued and
outstanding on the date of this Agreement.  ART does not hold any shares of its
authorized capital stock in its treasury. All of the issued and outstanding
shares of such capital stock are duly and validly issued and outstanding and are
fully paid and nonassessable.

          (c)  Except with the prior written approval of TELECOM, between the
date of this Agreement and the Effective Time, there will be no change in the
Certificate of Incorporation or By-Laws or in the authorized or issued capital
stock of ART.

          (d)  Except with the prior written approval of TELECOM, between the
date of this Agreement and the Effective Time, ART will not (i) issue any
additional capital stock or other security, (ii) declare, set aside or pay any
dividend or make any other distribution in respect to its capital, (iii)
directly or indirectly redeem, purchase or otherwise acquire any shares of its
capital stock, or (iv) issue to any person options, warrants or other rights to
acquire any securities of ART.

          (e) From the date of this Agreement up to and including the Effective
Time, except with the prior written approval of TELECOM, the business of ART
will be conducted in the usual, regular and ordinary manner, and ART will not
make any material change in its methods of management, distribution, marketing,
accounting or operations.

          (f)  In the event the Merger is not effective for any reason by May
13, 1997, in addition to its obligations under Section 12 hereof, ART agrees to
surrender all of the shares of TELECOM Common Stock held by ART to TELECOM
without any additional consideration.

<PAGE>

     8.   REPRESENTATIONS, WARRANTIES AND COVENANT OF ART, MERGER SUB AND
TELECOM.  Each of ART, Merger Sub and TELECOM will use its respective best
efforts to cause all of the conditions set forth in Sections 9 through 13 that
are within its control to be satisfied as soon as practicable after the date
hereof.

     9.   REPRESENTATIONS, WARRANTIES AND COVENANTS OF MERGER SUB.

          (a)  Merger Sub is a corporation duly organized, validly existing and
in good standing under the laws of the State of Delaware with power and
authority to carry on its business, to own its properties, and to execute and
deliver this Agreement and perform its obligations hereunder.

          (b)  Between the date of this Agreement and the Effective Time, there
will be no change in the Certificate of Incorporation or By-Laws or in the
authorized or issued capital stock of Merger Sub.

          (c)  Except as otherwise provided herein, between the date of this
Agreement and the Effective Time, Merger Sub will not (i) issue any additional
capital stock or other security, (ii) declare, set aside or pay any dividend or
make any other distribution in respect to its capital, (iii) directly or
indirectly redeem, purchase or otherwise acquire any shares of its capital
stock, or (iv) issue to any person options, warrants or other rights to acquire
any securities of Merger Sub.

          (d) From the date of this Agreement up to and including the Effective
Time, except with the prior written approval of TELECOM, Merger Sub will not
engage in any business or incur any indebtedness.

     10.  REPRESENTATIONS, WARRANTIES AND COVENANTS OF TELECOM.  TELECOM
represents, warrants and agrees as follows:

          (a)  TELECOM is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware with power and authority
to carry on its business, to own its properties, and to execute and deliver this
Agreement and perform its obligations hereunder.

          (b)  TELECOM shall not issue or sell any Series A Preferred Stock of
ART held by TELECOM.

          (c)  TELECOM waives any rights to dividends on the Series A Preferred
Stock of ART held by TELECOM.

     11.  CONDITIONS PRECEDENT TO THE OBLIGATION OF TELECOM.     The obligations
of TELECOM under this Agreement and the Certificate of Merger are subject to the
fulfillment prior to or on the Effective Time of the following conditions:

<PAGE>

          (a)  This Agreement and the Merger shall have been approved by the
     affirmative vote of the holders of all of the shares of ART Common Stock
     entitled to vote thereon;

          (b)  The Merger shall have been approved by the Federal Communication
     Commission; and

          (c)  TELECOM shall have received an opinion of its counsel to the
     effect that the Merger will be a reorganization described in Section
     368(a)(1)(B) of the Internal Revenue Code.

     12.  CONDITIONS PRECEDENT TO OBLIGATIONS OF ART.  The obligations of ART
under this Agreement are subject to the fulfillment prior to or on the Effective
Time of the following conditions:

          (a)  This Agreement and the Merger shall have been approved by the
     affirmative vote of the holders of TELECOM capital stock entitled to vote
     thereon;

          (b)  The Merger shall have been approved by the Federal Communication
     Commission; and

          (c)  ART shall have received an opinion of its counsel to the effect
     that the Merger will be a reorganization described in Section 368(a)(1)(B)
     of the Internal Revenue Code.

     13.  CONDITIONS PRECEDENT TO OBLIGATIONS OF MERGER SUB.  The obligations of
Merger Sub under this Agreement are subject to the fulfillment prior to or on
the Effective Time of the following conditions:

          (a)  This Agreement and the Merger shall have been approved by the
     affirmative vote of the holders of TELECOM capital stock entitled to vote
     thereon; and

          (b)  The Merger shall have been approved by the Federal Communication
     Commission.

     14.  EFFECT OF FAILURE TO CONSUMMATE MERGER.  In the event the Merger is
not effective for any reason by May 13, 1997, ART shall surrender all of its
shares of TELECOM Common Stock to TELECOM, and TELECOM and ART shall revise the
terms of that certain Services Agreement, dated May 8, 1995, to provide that (i)
the term thereof will be extended to 40 years, (ii) ART will receive, in the
event of any dividends paid by TELECOM to its stockholders, an amount equal to
the percentage share (the "Percentage Share") that the ART stockholders would
have owned of the combined corporations after giving effect to the Merger
(without taking into account any issuances of stock by ART or TELECOM after the
date hereof) of such aggregate dividends, (iii)

<PAGE>

ART will have a right of co-sale, subject to FCC approval, in accordance with
its Percentage Share of the aggregate consideration payable to TELECOM and ART
in such transaction in the event of any merger or sale of substantial assets by
TELECOM and (iv), in the event TELECOM agrees to merge into another entity or to
sell substantially all its assets to another entity, ART shall, upon the request
of TELECOM, use its best efforts, subject to FCC approval, to merge into such
entity or sell substantially all its assets to such entity for aggregate
consideration equal to the Percentage Share of the aggregate consideration to be
paid for ART and TELECOM in such transaction.

     15.  MODIFICATION AND TERMINATION.  To the fullest extent permitted under
the GCL, TELECOM, Merger Sub and ART, by mutual consent of their respective
Boards of Directors, may amend, modify and supplement this Agreement in such
manner as may be agreed upon by them in writing at any time before the Closing.
TELECOM, Merger Sub and ART may at any time, by mutual consent of their Boards
of Directors, terminate this Agreement.

     16.  MISCELLANEOUS.

          (a)  PARTIES IN INTEREST.  This Agreement shall only bind and inure to
the benefit of the parties and their respective successors and assigns.

          (b)  ENTIRE AGREEMENT.  This Agreement contains the entire
understanding of the parties with respect to the subject matter hereof and
supersedes all prior agreements and understandings between the parties with
respect to such subject matter.

          (c)  COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, and each such counterpart shall be deemed to be an original
instrument, but all such counterparts together shall constitute only one
agreement.

          (d)  HEADINGS.  The section headings contained in this Agreement are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.

          (e)  GOVERNING LAW.  This Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware, without giving effect to
principles of conflicts of law.

<PAGE>

     IN WITNESS WHEREOF, the Board of Directors of each of the parties hereto
first having duly adopted and approved the same, this Restated and Amended
Merger Agreement and Plan of Reorganization has been executed and delivered on
the date first above written.

Attest:                            ADVANCED RADIO TELECOM CORP.
                                   (formerly Advanced Radio
                                   Technology, Ltd.)
- --------------------
Name:
Title:                             By:

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


Attest:                            ADVANCED RADIO TECHNOLOGIES
                                   CORPORATION


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


Attest:                            ART MERGER CORPORATION


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

<PAGE>

                                                                         ANNEX I
                                                  TO RESTATED AND AMENDED MERGER
                                            AGREEMENT AND PLAN OF REORGANIZATION


                              CERTIFICATE OF MERGER
                                       OF
                             ART MERGER CORPORATION
                                  WITH AND INTO
                          ADVANCED RADIO TELECOM CORP.

     The undersigned corporation, organized and existing under the General
Corporation Law of the State of Delaware (the "General Corporation Law"), DOES
HEREBY CERTIFY:

     FIRST:  The name and state of incorporation of each of the constituent
corporations in the merger are as follows:

          Name                          State of Incorporation
          ----                          ----------------------
ADVANCED RADIO TELECOM CORP.
   (formerly known as Advanced
   Radio Technology, Ltd.)                     Delaware

ART MERGER CORPORATION                         Delaware

     SECOND:  A Restated and Amended Merger Agreement and Plan of Reorganization
dated June 20, 1996 (the "Merger Agreement") has been approved, adopted,
certified, executed, and acknowledged by each constituent corporation in
accordance with Section 251 of the General Corporation Law of the State of
Delaware.

     THIRD:  The name of the surviving corporation shall be ART LICENSING CORP.

     FOURTH:  Such amendments or changes to the certificate of incorporation of
the surviving corporation as are desired to be effected by the merger are set
forth on Exhibit A attached hereto and incorporated herein by reference, which
sets forth such certificate of incorporation, as so amended, in its entirety.

     FIFTH:  The executed Merger Agreement is on file at the principal place of
business of the surviving corporation at 500 - 108th Avenue NE, Bellevue,
Washington 98004.

     SIXTH:  A copy of the Merger Agreement will be furnished by the surviving
corporation, on request and without cost, to any stockholder of any constituent
corporation.

<PAGE>

     IN WITNESS WHEREOF, this Certificate of Merger has been executed and
acknowledged this __ day of June, 1996.

                              ADVANCED RADIO TELECOM CORP.



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


ACKNOWLEDGED:


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

<PAGE>

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

                          ADVANCED RADIO TELECOM CORP.
                              SUBSCRIPTION BOOKLET

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



SUBSCRIBER: ________________


<PAGE>

                                     NOTICES

INVESTORS SHOULD NOT CONSTRUE THE CONTENTS HEREOF (THE "OFFERING MATERIALS") OR
ANY COMMUNICATION FROM ADVANCED RADIO TELECOM CORP. (THE "COMPANY") AS LEGAL,
TAX OR ACCOUNTING ADVICE. EACH INVESTOR SHOULD SEEK HIS OWN LEGAL, TAX AND
ACCOUNTING ADVICE. IN MAKING AN INVESTMENT DECISION INVESTORS MUST RELY ON THEIR
OWN EXAMINATION OF THE ISSUER AND THE TERMS OF THE OFFERING, INCLUDING THE
MERITS AND RISKS INVOLVED.

THESE SECURITIES HAVE NOT BEEN RECOMMENDED BY ANY FEDERAL OR STATE SECURITIES
COMMISSION OR REGULATORY AUTHORITY. FURTHERMORE, THE FOREGOING AUTHORITIES HAVE
NOT CONFIRMED THE ACCURACY OR DETERMINED THE ADEQUACY OF THIS SUBSCRIPTION
BOOKLET. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. THE ATTORNEY
GENERAL OF THE STATE OF NEW YORK DOES NOT PASS UPON OR ENDORSE THE MERITS OF ANY
PRIVATE OFFERING. NO OFFERING DOCUMENT HAS BEEN FILED WITH OR OTHERWISE APPROVED
BY THE BUREAU OF INVESTOR PROTECTION AND SECURITIES OF THE DEPARTMENT OF LAW OF
THE STATE OF NEW YORK. ANY REPRESENTATION TO THE CONTRARY IS UNLAWFUL.

THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE SECURITIES ACT OF
1933, AS AMENDED, AND APPLICABLE STATE SECURITIES LAWS. INVESTORS SHOULD BE
AWARE THAT THEY MAY BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS INVESTMENT
FOR AN INDEFINITE PERIOD OF TIME.

THE OFFERING MATERIALS DO NOT CONSTITUTE AN OFFER OR SOLICITATION IN ANY STATE
OR OTHER JURISDICTION IN WHICH SUCH AN OFFER OR SOLICITATION IS NOT AUTHORIZED.
IN ADDITION, THE OFFERING MATERIALS CONSTITUTE AN OFFER ONLY TO THE INVESTOR
NAMED ON THE COVER PAGE OF THIS SUBSCRIPTION BOOKLET. ANY FURTHER DISTRIBUTION
OR REPRODUCTION OF THE OFFERING MATERIALS, IN WHOLE OR IN PART, OR THE
DISCLOSURE OF ANY OF THEIR CONTENTS, IS PROHIBITED.

NO OFFERING LITERATURE OR ADVERTISING IN ANY FORM MAY BE EMPLOYED IN THE
OFFERING OTHER THAN THE OFFERING MATERIALS AND THE INFORMATION AUTHORIZED IN
WRITING BY THE COMPANY. NO PERSON IS AUTHORIZED TO GIVE ANY INFORMATION OR TO
MAKE ANY REPRESENTATION NOT CONTAINED IN THE OFFERING MATERIALS OR AUTHORIZED IN
WRITING BY THE COMPANY IN CONNECTION WITH THE MATTERS DESCRIBED HEREIN OR
THEREIN, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATION MUST NOT BE
RELIED UPON. HOWEVER,


<PAGE>

NOTHING HEREIN CONTAINED SHALL LIMIT THE OPPORTUNITY OF ANY INVESTOR OR HIS
REPRESENTATIVES TO ASK QUESTIONS OF AND RECEIVE ANSWERS FROM THE COMPANY
CONCERNING THE TERMS AND CONDITIONS OF THIS OFFERING OR TO OBTAIN ADDITIONAL
INFORMATION NECESSARY TO VERIFY THE ACCURACY OF ANY OF THE INFORMATION CONTAINED
IN THE OFFERING MATERIALS OR IN ANY DOCUMENT REFERRED TO HEREIN.

     The following legends apply to an investment in the Notes and Warrants:


FOR FLORIDA RESIDENTS:

     PURSUANT TO SECTION 517.061(11)(a)(5) OF THE FLORIDA SECURITIES ACT, WHERE
SALES ARE MADE TO FIVE OR MORE PERSONS, FLORIDA INVESTORS HAVE A THREE-DAY RIGHT
OF WITHDRAWAL OF ACCEPTANCE.  IF YOU HAVE EXECUTED THE SUBSCRIPTION AGREEMENT,
YOU MAY ELECT, WITHIN THREE BUSINESS DAYS AFTER SIGNING THE AGREEMENT, TO
WITHDRAW FROM YOUR AGREEMENT AND RECEIVE A FULL REFUND OF ANY MONEY PAID BY YOU.
YOUR WITHDRAWAL WILL BE WITHOUT FURTHER LIABILITY TO ANY PERSON.  TO ACCOMPLISH
SUCH WITHDRAWAL, YOU NEED ONLY SEND A LETTER OR TELEGRAM TO ADVANCED RADIO
TELECOM CORP., C/O HAHN & HESSEN LLP, 350 FIFTH AVENUE, NEW YORK, NEW YORK
10188, ATTENTION: JAMES KARDON, INDICATING YOUR INTENTION TO WITHDRAW.  SUCH
LETTER OR TELEGRAM MUST BE SENT AND POSTMARKED PRIOR TO THE END OF THE
AFOREMENTIONED THIRD BUSINESS DAY.  IF YOU ARE SENDING A LETTER, IT IS PRUDENT
TO SEND IT BY CERTIFIED MAIL, RETURN RECEIPT REQUESTED, TO ENSURE THAT IT IS
RECEIVED AND ALSO TO EVIDENCE THE TIME WHEN IT IS MAILED.  SHOULD YOU MAKE THIS
REQUEST ORALLY, YOU MUST ALSO ASK FOR WRITTEN CONFIRMATION THAT YOUR REQUEST HAS
BEEN RECEIVED.  THE FLORIDA DEPARTMENT OF BANKING AND FINANCE HAS NOT REVIEWED
THE OFFERING OR THE DISCLOSURE DOCUMENTS AND THE SECURITIES HAVE NOT BEEN
REGISTERED UNDER THE FLORIDA SECURITIES ACT. UNLESS THE SECURITIES ARE
REGISTERED, THEY MAY NOT BE SOLD OR TRANSFERRED IN FLORIDA EXCEPT IN A
TRANSACTION WHICH IS EXEMPT UNDER SAID ACT.

FOR NEW YORK RESIDENTS:

     THIS SUBSCRIPTION AGREEMENT HAS NOT BEEN FILED WITH OR REVIEWED BY THE
ATTORNEY GENERAL OF THE STATE OF NEW YORK PRIOR TO ITS ISSUANCE AND USE.  THE
ATTORNEY GENERAL OF THE STATE OF NEW YORK HAS NOT PASSED ON OR ENDORSED THE
MERITS OF THIS OFFERING.  ANY REPRESENTATION TO THE CONTRARY IS UNLAWFUL.


                                       -3-
<PAGE>

FOR NORTH CAROLINA RESIDENTS:

     THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE
AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, AND THE APPLICABLE STATE SECURITIES LAWS, PURSUANT TO
REGISTRATION OR EXEMPTION THEREFROM.  INVESTORS SHOULD BE AWARE THAT THEY WILL
BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE
PERIOD OF TIME.

FOR PENNSYLVANIA RESIDENTS:

     PURSUANT TO SECTION 207(m)(2) OF PENNSYLVANIA SECURITIES ACT OF 1972, AS
AMENDED, PENNSYLVANIA INVESTORS HAVE A TWO-DAY RIGHT OF WITHDRAWAL OF
ACCEPTANCE.  IF YOU HAVE EXECUTED THE SUBSCRIPTION AGREEMENT, YOU MAY ELECT,
WITHIN TWO BUSINESS DAYS AFTER SIGNING THE AGREEMENT, TO WITHDRAW FROM YOUR
AGREEMENT AND RECEIVE A FULL REFUND OF ANY MONEY PAID BY YOU.  YOUR WITHDRAWAL
WILL BE WITHOUT FURTHER LIABILITY TO ANY PERSON.  TO ACCOMPLISH SUCH WITHDRAWAL,
YOU NEED ONLY SEND A LETTER OR TELEGRAM TO ADVANCED RADIO TELECOM CORP., C/O
HAHN & HESSEN LLP, 350 FIFTH AVENUE, NEW YORK, NEW YORK 10188, ATTENTION: JAMES
KARDON, INDICATING YOUR INTENTION TO WITHDRAW.  SUCH LETTER OR TELEGRAM MUST BE
SENT AND POSTMARKED PRIOR TO THE END OF THE AFOREMENTIONED SECOND BUSINESS DAY.
IF YOU ARE SENDING A LETTER, IT IS PRUDENT TO SEND IT BY CERTIFIED MAIL, RETURN
RECEIPT REQUESTED, TO ENSURE THAT IT IS RECEIVED AND ALSO TO EVIDENCE THE TIME
WHEN IT IS MAILED.  SHOULD YOU MAKE THIS REQUEST ORALLY, YOU MUST ALSO ASK FOR
WRITTEN CONFIRMATION THAT YOUR REQUEST HAS BEEN RECEIVED.  THE PENNSYLVANIA
SECURITIES COMMISSION HAS NOT REVIEWED THE SUBSCRIPTION AGREEMENT AND THE
SECURITIES HAVE NOT BEEN REGISTERED UNDER THE PENNSYLVANIA SECURITIES ACT OF
1972, AS AMENDED.

     THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE
AND MAY NOT BE TRANSFERRED OR RESOLD FOR A PERIOD OF TWELVE (12) MONTHS AFTER
THE DATE OF THE PURCHASE EXCEPT IN ACCORDANCE WITH SECTION 203(d) OF THE
PENNSYLVANIA SECURITIES ACT OF 1972, AS AMENDED AND SECTIONS 203.041 AND 204.011
OF PENNSYLVANIA CODE, AS AMENDED.


                                       -4-
<PAGE>

                          ADVANCED RADIO TELECOM CORP.

                             SUBSCRIPTION AGREEMENT


Advanced Radio Telecom Corp.
500 108th Ave., N.E., Suite 1910
Bellevue, WA 98004
Attention: Steven D. Comrie, President

Gentlemen:

This will evidence the agreement of the undersigned to subscribe for and
purchase from Advanced Radio Telecom Corp., a Delaware corporation (the
"Company") unit(s) (the "Unit(s)") at a purchase price of $100,000.00 per Unit,
each Unit consisting of (i) a note (the "Note") in the original principal amount
of $100,000.00, in the form annexed hereto as EXHIBIT A and (ii) a Common Stock
Purchase Warrant (the "Warrant") to purchase 22,000 shares (the "Shares") of the
Company's Common Stock, par value $.001 per share, (the "Common Stock"), in the
form annexed hereto as EXHIBIT B. The Units, Notes, Warrants and any shares of
Common Stock issued or issuable upon exercise of the Warrant are collectively
referred to as the "Securities".

     1.   SUBSCRIPTION. The undersigned hereby agrees to purchase and herewith
delivers the full purchase price for the Unit(s) subscribed for as set forth on
the signature page hereof to the Company, and the Company hereby acknowledges
receipt thereof.

     2.   RELATED AGREEMENTS AND AMERITECH AGREEMENT.

          (a)  If the undersigned is not already a party thereto, the
undersigned hereby agrees to enter into and hereby executes and delivers (i) the
Restated and Amended Registration Rights Agreement, dated February 2, 1996, by
and among the Company, Advanced Radio Technologies Corporation ("ART") and the
parties thereto (the "Registration Rights Agreement"); and (ii) the Amended and
Restated Stockholders' Agreement, dated February 2, 1996, among the Company, ART
and the stockholders of each of the Company and ART named therein (collectively,
the "Related Agreements") in each case as a New Unaffiliated Stockholder, as
defined therein, with all the obligations and benefits of a New Unaffiliated
Stockholder under the Related Agreements.

          (b)  The undersigned acknowledges receipt of a copy of the Securities
Purchase Agreement, dated February 2, 1996, by and among the Company, ART and
Ameritech Development Corporation, including all Exhibits and Schedules thereto
(the "Ameritech Agreement").


                                       -1-
<PAGE>

     3.   REPRESENTATIONS.    A)  The Company represents and warrants that the
representations and warranties made in the Ameritech Agreement were true and
correct in all material respects as of the date thereof.

                              B)  The undersigned represents and warrants to and
agrees with the Company and its officers, directors, stockholders, agents,
employees, representatives and counsel (collectively, the "Representatives") as
follows:

          (a)  The Securities are being purchased by the undersigned for its own
     account, for investment and without any view to the distribution,
     assignment or resale to others or fractionalization in whole or in part.
     The undersigned agrees not to assign or in any way transfer the
     undersigned's rights to the Securities or any interest therein and
     acknowledges that the Company will not recognize any purported assignment
     or transfer. No other person has or will have a direct or indirect
     beneficial interest in the Securities. The undersigned agrees not to sell,
     hypothecate or otherwise transfer the undersigned's Securities unless the
     Securities are registered under Federal and applicable state securities
     laws or unless, in the opinion of counsel satisfactory to the Company, an
     exemption from such laws is available.

          (b)  All of the information that the undersigned has heretofore
     furnished to the Company and the Representatives or which is set forth
     herein with respect to the undersigned's financial position and business
     experience, is correct, complete and not misleading as of the date hereof
     and the undersigned will advise the Company immediately in writing of any
     change in any response hereto. The undersigned understands that this
     investment is suitable for and is available only to "Accredited Investors",
     as that term is defined in Regulation D ("Regulation D") promulgated under
     the Securities Act of 1933, as amended (the "Act"), and that the
     undersigned satisfies at least one of the categories enumerated below as an
     Accredited Investor.

               Accordingly, the undersigned acknowledges that the information
     set forth herein is not intended to be exhaustive and is provided only as a
     guide to assist each potential investor in making an independent
     investigation of the Company and the Securities being offered.

          (c)  The undersigned meets the requirements of one of the
     subparagraphs listed below (please insert your initials in the appropriate
     place beneath the description applicable to you):

               i)   A natural person who had individual income of more than U.S.
$200,000 in each of the most recent two years or joint income with that person's
spouse in excess of U.S. $300,000 in each of the most recent two years and who
reasonably expects to reach that same income level for the current year.  For
this purpose, individual income means adjusted gross income, as reported for
federal income tax purposes less any income


                                       -2-
<PAGE>

attributable to a spouse or to property owned by a spouse, (A) increased by the
individual's share (and not a spouse's share) of: (w) the amount of any tax
exempt interest income received, (x) amounts contributed to an IRA or Keogh
retirement plan, (y) alimony paid, and (z) the excluded portion of any long-term
capital gains, and (B) adjusted, plus or minus, for any non-cash gain or loss,
respectively, reported for federal income tax purposes;


                                             ----------
                                              initial

               ii)  A natural person whose individual net worth, or joint net
worth with that person's spouse, is in excess of U.S. $1,000,000.  For this
purpose, "net worth" means the excess of total assets at fair market value,
including home and personal property, over total liabilities, provided, however,
for the purpose of determining a person's net worth, the principal residence
owned by an individual shall be valued at cost, including the cost of
improvements, net of current encumbrances upon the property or valued on the
basis of a written appraisal used by an institutional lender making a loan
secured by the property.  For the purposes of this provision, "institutional
lender" means a bank, savings and loan company, industrial loan company, credit
union, or personal property broker or a company whose principal business is a
lender upon loans secured by real property and which has such loans receivable
in the amount of U.S. $200,000,000 or more;


                                             ----------
                                              initial

               iii)  A natural person whose total purchase is U.S. $250,000 or
more and the purchase price does not exceed 20% of the undersigned's net worth
at the time of sale, or joint net worth with the undersigned's spouse;


                                             ----------
                                              initial

               iv)  A trust, with total assets in excess of U.S. $5,000,000,
which is not formed for the purpose of acquiring the Units offered hereby and
whose purchase is directed by a person who has such knowledge and experience in
financial and business matters that he is capable of evaluating the risks and
merits of an investment in the Units;


                                             ----------
                                              initial

               v)  A bank as defined in Section 3(a)(2) of the Securities Act or
a savings and loan association or other institution as defined in Section
3(a)(5)(A) of the Securities Act whether acting in its individual or fiduciary
capacity; a broker or dealer registered pursuant to Section 15 of the Securities
Exchange Act of 1934; an insurance


                                       -3-
<PAGE>

company as defined in Section 2(13) of the Securities Act; an investment company
registered under the Investment Company Act of 1940 or a business development
company as defined in Section 2(a)(48) of the Investment Company of 1940; a
small business investment company licensed by the U.S. Small Business
Administration under Section 301(c) or (d) of the Small Business Investment Act
of 1958; a plan established and maintained by a state, its political
subdivisions, or an agency or instrumentality of a state or its political
subdivisions, for the benefit of its employees, if such plan has total assets in
excess of U.S. $500,000,000; or an employee benefit plan within the meaning of
Title I of the Employee Retirement Income Security Act of 1974, if the
investment decision is made by a plan fiduciary, as defined in Section 3(21) of
the Employee Retirement Income Security Act of 1974, which is either a bank,
savings and loan association, insurance company, or registered investment
adviser, or if the employee benefit plan has total assets in excess of U.S.
$5,000,000, or if the employee benefit plan is a self-directed plan and the
investment decision is made solely by persons who are accredited investors;


                                             ----------
                                              initial

               vi)  A private business development company as defined in Section
202(a)(22) of the Investment Advisers Act in 1940;


                                             ----------
                                              initial

               vii)  An organization described in Section 501(c)(3) of the
Internal Revenue Code of 1986, as amended, a corporation, Massachusetts or
similar business trust, or partnership not formed for the specific purpose of
acquiring the Shares, with total assets in excess of U.S. $5,000,000; or


                                             ----------
                                              initial

               viii)  An entity in which all of the equity owners are accredited
investors.


                                             ----------
                                              initial


          (d)  The undersigned has the right, power and capacity to enter into
     this Agreement and to carry out the transactions contemplated hereunder. If
     the undersigned is an entity, this Agreement has been duly authorized and
     executed and


                                       -4-
<PAGE>

     delivered by or on behalf of the undersigned and constitutes the valid and
     binding obligation of the undersigned enforceable in accordance with its
     terms.

          (e)  The undersigned, either individually or together with the
     representative on which the undersigned has relied, has such knowledge and
     experience in financial and business matters that the undersigned is
     capable of evaluating the merits and risks of an investment in the
     Securities.

          (f)  The undersigned has carefully read and is familiar with this
     Agreement, the Related Agreements and the Ameritech Agreement, has
     evaluated the merits and risks of the undersigned's investment in the
     Securities, and has determined that the Securities are a suitable
     investment.  The undersigned understands that this Agreement does not
     contain all of the information that would normally be contained in a
     prospectus used in a public offering or in an offering memorandum used in a
     private offering made to non-accredited investors. Therefore, the
     undersigned has availed himself of the opportunity to ask questions of the
     Company concerning the terms and conditions of this offering and obtained
     such additional information as the undersigned may deem necessary. The
     Company has answered all inquiries concerning the terms and conditions of
     this offering and has afforded the undersigned the opportunity to obtain
     any additional information (to the extent that the Company possesses such
     information or can acquire it without unreasonable effort or expense)
     necessary to verify the accuracy of the information. The undersigned
     acknowledges that all documents, instruments, records and books pertaining
     to the Company and this investment have been made available and that the
     same will be available upon reasonable notice for inspection during
     reasonable business hours at the offices of the Company.

          (g)  In evaluating the suitability of an investment in Securities, the
     undersigned has not relied upon any representation or other information
     (whether oral or written) from the Company, the Representatives, any
     selling agent or other third party; any advertisement, notice or other
     communication contained in any newspaper, magazine or similar publication
     or broadcast on television or radio; or any seminar or meeting relating to
     this investment. The undersigned has undertaken an independent
     investigation and has relied, to the extent the undersigned believed
     advisable, on the undersigned's professional legal, tax and financial
     advisers.

          (h)  The undersigned has had an opportunity to discuss the Company,
     business, management and financial affairs with the Company's management
     and has received (or had made available to it) any financial and business
     documents requested by it.

          (i)  The undersigned understands that the Securities are a highly
     speculative investment which involve a high risk of loss. The undersigned
     can afford to hold the


                                       -5-
<PAGE>

     unregistered Securities being offered for an indefinite period of time and
     to sustain a complete loss of the amount for which the undersigned hereby
     offers to subscribe and has adequate means for providing for the
     undersigned's current needs and possible contingencies and has no need for
     liquidity of the undersigned's investment in Securities. The undersigned's
     commitment to all similar illiquid investments is reasonable in
     relationship to its net worth. The undersigned understands all of the risk
     factors relating to the purchase of the Securities.

          (j)  The undersigned acknowledges that the Securities have not been
     filed, registered with, approved or disapproved by the United States
     Securities and Exchange Commission ("SEC") nor by the securities regulatory
     authority of any state and no such filing or registration will take place.
     Neither the SEC nor any state authority has passed upon or endorsed the
     merits of the offering of the Securities, nor is it intended that any of
     the above will do so. Any representation contrary to the foregoing may be a
     criminal offense.

          (k)  Except as set forth in the Registration Rights Agreement, the
     undersigned understands that the Company is under no obligation to register
     the Securities on behalf of the undersigned or to assist the undersigned in
     complying with any exemption from registration. There is no public market
     for the Securities and no such public market is expected to develop. There
     can be no assurance that the undersigned will be able to sell or dispose of
     the Securities.

          (l)  All contacts and contracts between the undersigned and the
     Company regarding the offer and sale of the Securities have been made
     within the state of the undersigned's residence, and the undersigned has no
     permanent residence other than the residence address indicated on the
     signature page of this Agreement and has no present intention of becoming a
     permanent resident elsewhere.

          (m)  The undersigned certifies that the undersigned is not subject to
     backup withholding.

          (n)  The undersigned understands and acknowledges that investment in
     the Units involves significant risks, including those set forth in the RISK
     FACTORS attached hereto as EXHIBIT C.

          (o)  Omitted.

          (p)  The undersigned does hereby indemnify and hold harmless the
     Company and the Representatives against and from any and all loss,
     liability, claim, damage and expense (including, without limitation,
     attorneys' fees and disbursements) incurred as a result of a
     misrepresentation, or breach of an agreement or warranty, made by the
     undersigned to the Company or the Representatives. The undersigned


                                       -6-
<PAGE>

     acknowledges that this obligation will survive the purchase of the
     Securities hereunder.

     4.   ACCEPTANCE OR REJECTION OF SUBSCRIPTION.

          (a)  This subscription shall not be binding on the Company unless (i)
     the undersigned satisfies the conditions of Section 2(a) above and (ii) it
     is accepted on behalf of the Company, such acceptance to be indicated by
     the execution of this Agreement on behalf of the Company at the place
     provided at the foot hereof.

          (b)  The undersigned acknowledges that the Company has the right to
     accept or reject this subscription, in whole or in part, for any reason
     whatsoever.

     5.   LIMITATIONS ON TRANSFER.  The undersigned recognizes (a) that the
Securities have not been registered under applicable federal and state
securities laws (the "Securities Laws") and, accordingly, the undersigned must
bear the economic risk of an investment in the Securities for an indefinite
period of time; (b) that neither this Subscription Agreement nor the Securities
may be assigned, pledged, encumbered or otherwise transferred by him without
registration under such Securities Laws, unless exempt therefrom, and unless, in
the opinion of his counsel satisfactory to the Company, such transfer would be
in compliance with the Securities Laws; (c) that the undersigned is not and will
not be entitled to make any transfers of the Securities pursuant to the
exemption afforded by Regulation D under the Securities Act unless the
undersigned has received the written approval of the Company and that any
certificate or other document evidencing the Securities will bear a legend
stating that the Securities have not been registered under the Securities Laws
and referring to the foregoing restrictions on their transferability and sale;
and (d) that the transfer of the Warrants is limited under the Related
Agreements.

     6.   DEFAULT ON NOTES.  In the event of a default on the Note, the Company
shall grant to the holder of each $100,000 principal amount thereof a five year
warrant, having the same terms and in substantially the same form as the
Warrants issued on the date hereof, exercisable to purchase 11,000 shares of
Common Stock.

     7.   NOTICES. Any notice, demand or other communication which any party
hereto may be required, or may elect, to give to anyone interested hereunder
shall be sufficiently given only if (a) deposited, postage prepaid, in the
United States mail, registered or certified mail, return receipt requested,
addressed to such address as may be given herein, (b) delivered personally or by
telefax at such address or (c) transmitted by nationally recognized overnight
delivery service.

     8.   MISCELLANEOUS. Neither this Agreement nor any provision hereof may be
waived, modified, discharged or terminated except by an instrument in writing
signed by the party against whom any of the same is sought. This Agreement shall
be binding upon the undersigned, the undersigned's heirs, estate, legal
representatives, successors and permitted


                                       -7-
<PAGE>

assigns and shall inure to the benefit of the Company, its successors and
assigns. The subscription made hereby is irrevocable and may not be transferred
or assigned by the undersigned. In the event that any provision of this
Agreement is deemed invalid or unenforceable under any applicable statute or
rule of law, then such provision shall be deemed inoperative to the extent that
it may conflict herewith and shall be deemed modified to conform with such
statute or rule of law. Any provision hereto which may prove invalid or
unenforceable under any law shall not affect the validity or enforceability of
any other provision thereof. This Agreement constitutes the entire agreement
between the parties with respect to the subject matter hereof and may be amended
only by a writing executed by all of the parties.

     9.   GOVERNING LAW.  Notwithstanding the place where this Agreement may be
executed by any of the parties, the parties expressly agree that all the terms
and provisions hereof shall be construed in accordance with and governed by the
internal laws of the State of Delaware, without giving effect to conflicts of
law.

     10.  COUNTERPARTS.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same agreement.

     IN WITNESS WHEREOF, the undersigned has executed this Agreement and, if
required pursuant to Section 2(a) above, each of the Related Agreements.



____________________________________    ____________________________________
Print Name of Purchaser                 Date

X___________________________________    Number of Units subscribed
     Signature                          for at $100,000 per Unit: ______

____________________________________    Aggregate Purchase
Print Name and Title (if applicable)         Price: $_______

____________________________________    ____________________________________
Address of Legal Residence              City, State, Zip Code

____________________________________    ____________________________________
Mailing Address (if different)          City, State, Zip Code

____________________________________    ____________________________________
Telephone (include area code)           Telefax (include area code)


                                       -8-
<PAGE>

____________________________________     ___________________________________
Additional Contact Information
  (if applicable)



Subscription accepted as of
March 8, 1996:

ADVANCED RADIO TELECOM CORP.


By:_________________________
Name:
Title:


                                       -9-
<PAGE>

                                    EXHIBIT A

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, (THE "ACT") OR ANY STATE SECURITIES LAWS AND NEITHER
THE SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD, TRANSFERRED,
PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER SUCH ACT OR SUCH LAWS OR AN EXEMPTION FROM REGISTRATION UNDER
SUCH ACT AND SUCH LAWS WHICH, IN THE OPINION OF COUNSEL SATISFACTORY TO THE
COMPANY, IS AVAILABLE.  THIS NOTE MAY BE SUBJECT TO ORIGINAL ISSUE DISCOUNT.

                                 PROMISSORY NOTE

Due:  March 8, 1998

$_________________                                                 March 8, 1996

     FOR VALUE RECEIVED, ADVANCED RADIO TELECOM CORP., a Delaware corporation
(the "Maker") having an office at 500 108th Avenue, N.E., Bellevue, Washington
98004 hereby promises to pay in cash on March 8, 1998 to the order of
_________________ (the "Payee") the principal sum of ________________________
($___________) DOLLARS together with interest in cash at the rate of ten (10%)
percent per annum, based on the actual number of days elapsed over a 360-day
year, as provided herein, with interest payable semi-annually in arrears, on
March 8 and September 8 of each year.  Notwithstanding the foregoing, the
outstanding principal sum together with interest thereon shall be due and
payable upon the consummation of an initial public offering or private placement
of the Maker's securities that results in gross proceeds to the Maker of at
least $25,000,000.

     This Note is one of the Notes (the "Notes") of like tenor issued on the
date hereof in the aggregate principal amount of $5,000,000.

     In consideration for the indebtedness evidenced by this Note, Maker shall
issue warrants exercisable to purchase certain shares of Common Stock of Maker
(the "Warrants") as more particularly described in that certain Common Stock
Purchase Warrant executed by Maker in favor of Payee on the date hereof.

     The following shall be deemed events of default hereunder:

          1.   If any payment shall not be made within ten (10) days when the
     same shall become due and payable;

          2.   If the Maker shall (i) apply for or consent to the appointment of
     a receiver, trustee or liquidator of a substantial part of its assets or
     property; (ii) make a general assignment for the benefit of creditors;
     (iii) be adjudicated a bankrupt; (iv) file a voluntary petition in
     bankruptcy or petition or an answer seeking reorganization,


<PAGE>

     or make a plan with creditors or take advantage of any bankruptcy,
     reorganization, insolvency, readjustment of debt, dissolution or
     liquidation law or statute now or hereafter in effect or an answer
     admitting the material allegations of any petition filed against it in any
     proceeding under any such law or statute; or (v) admit in writing the
     Maker's inability to pay the Maker's debts as they become due;

          3.   If any proceeding against the Maker seeking reorganization,
     arrangement, composition, adjustment, liquidation, dissolution or similar
     relief under the present or any future Federal Bankruptcy Act or other
     applicable Federal or state statute, law or regulation shall remain
     undismissed or continue unstayed and in effect for any period of sixty (60)
     days; or

          4.   If a court of competent jurisdiction shall enter an order,
     judgment or decree appointing a receiver for a substantial part of the
     assets or properties of the Maker and such order, judgment or decree shall
     continue unvacated or unstayed and in effect for a period of sixty (60)
     days.

     Unless the Payee otherwise elects, in the Payee's sole discretion, this
Note shall automatically become immediately due and payable, without further
notice or demand, upon the occurrence of any event of default hereinabove
described.  Upon the acceleration of the entire or any portion of the unpaid
balance of this Note, the holder, without prejudice to any other rights, is
authorized to proceed against Maker and shall not be required to have recourse
to any security given for payment of this Note.

     In the event of a default on the Notes, Maker shall grant to the holder of
each $100,000 principal amount of Notes, an additional Warrant, having the same
term and in substantially the same form as the Warrants, exercisable to purchase
11,000 shares of Common Stock of Maker.

     This Note shall be unsecured and shall rank senior to all other
indebtedness of Maker incurred after the date hereof or currently existing and
not by its terms senior to other indebtedness, except that this Note shall rank
junior to any existing secured indebtedness of the Company to the extent of the
collateral securing such indebtedness and PARI PASSU with indebtedness owed to
EMI Communications Corporation pursuant to a note dated November 13, 1995, in
the initial principal amount of $1,500,000; provided that, with the written
consent of holders of at least 70% of the outstanding principal amount of Notes
outstanding, Maker may incur additional indebtedness either senior or PARI PASSU
with this Note.

     At the option of the Maker, the unpaid balance of this Note may be prepaid
in whole or in part, from time to time, without penalty or premium.

     Except as otherwise expressly provided herein, Maker, sureties, guarantors
and endorsers of this Note hereby severally waive presentment, demand for
payment, dishonor,


                                        2
<PAGE>

notice of dishonor, protest and notice of protest, and any and all other
requirements necessary to hold them liable as Maker.

     The liability of Maker hereunder shall be unconditional. No act, failure or
delay by the holder hereof to declare a default as set forth herein or to
exercise any right or remedy it may have hereunder, or otherwise, shall
constitute a waiver of its rights to declare such default or to exercise any
such right or remedy at such time as it shall determine in its sole discretion.

     Each Maker, surety, guarantor and endorser further agrees, jointly and
severally, to pay all costs of collection, including a reasonable attorney's fee
and all costs of levy or appellate proceedings or review, or both, in case the
principal or any interest thereon is not paid at the respective maturity
thereof, or in case it becomes necessary to protect the security hereof, whether
suit be brought or not.

     Any and all notices or other communications required or permitted to be
given under this Note shall be in writing and shall be deemed to have been duly
given upon personal delivery or the mailing thereof by certified or registered
mail (a) if to the Maker, addressed to it at its address set forth above; and
(b) if to Payee, addressed to it or at such other address any person or entity
entitled to receive notices may specify by written notice given as aforesaid.

     This Note may not be changed or terminated orally.

     This Note shall be binding upon Maker, its legal representatives,
successors or assigns and shall inure to the benefit of Payee and its
successors, endorsers, assigns or holder(s) in due course.

     This Note shall be governed by and construed in accordance with the laws of
the State of Delaware, without giving effect to principles of conflicts of law.
By signing below, the Maker hereby irrevocably submits to the jurisdiction of
such state and to service of process by certified or registered mail at the
Maker's last known address. No provision of this Note may be changed unless in
writing signed by the Payee.


                                        3
<PAGE>

     IN WITNESS WHEREOF, the Maker has caused this Note to be executed by its
duly authorized representative as of the date and year first above written.

                         ADVANCED RADIO TELECOM CORP.


                         By:_________________________
                         Name:
                         Title:

     The undersigned hereby guarantees payment of this Note.

                         ADVANCED RADIO TECHNOLOGIES
                          CORPORATION


                         By:_________________________
                         Name:
                         Title:


                                        4
<PAGE>

                                    EXHIBIT B

Void after March __, 2001


     THIS WARRANT AND ANY SHARES ACQUIRED UPON THE EXERCISE OF THIS WARRANT
     HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933.  THIS
     WARRANT AND SUCH SHARES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE
     OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT.  THIS
     WARRANT AND SUCH SHARES MAY NOT BE TRANSFERRED EXCEPT UPON THE
     CONDITIONS SPECIFIED IN THIS WARRANT AND IN THE SUBSCRIPTION
     AGREEMENT, DATED AS OF THE DATE HEREOF (AS AMENDED AND MODIFIED FROM
     TIME TO TIME), AND NO TRANSFER OF THIS WARRANT OR SUCH SHARES SHALL BE
     VALID OR EFFECTIVE UNLESS AND UNTIL SUCH CONDITIONS SHALL HAVE BEEN
     COMPLIED WITH.

     THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR
     INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
     1933.  THESE SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE
     OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SUCH ACT.
     ADDITIONALLY, THE TRANSFER OF THESE SECURITIES IS SUBJECT TO THE
     CONDITIONS SPECIFIED IN (I) SECTION 12 OF THE REGISTRATION RIGHTS
     AGREEMENT DATED FEBRUARY 2, 1996, (THE "REGISTRATION RIGHTS
     AGREEMENT") AMONG ADVANCED RADIO TELECOM CORP., ADVANCED RADIO
     TECHNOLOGIES CORPORATION AND CERTAIN OTHER SIGNATORIES THERETO AND
     (II) THE RESTATED AND AMENDED STOCKHOLDERS AGREEMENT DATED FEBRUARY 2,
     1996, (THE "STOCKHOLDERS AGREEMENT") AMONG ADVANCED RADIO TELECOM
     CORP., ADVANCED RADIO TECHNOLOGIES CORPORATION AND CERTAIN OTHER
     SIGNATORIES THERETO, AND NO TRANSFER OF THESE SECURITIES SHALL BE
     VALID OR EFFECTIVE UNTIL SUCH CONDITIONS HAVE BEEN FULFILLED.  UPON
     THE FULFILLMENT OF CERTAIN OF SUCH CONDITIONS, ADVANCED RADIO TELECOM
     CORP., AND ADVANCED RADIO TECHNOLOGIES CORPORATION HAVE AGREED TO
     DELIVER TO THE HOLDER HEREOF A NEW CERTIFICATE, NOT BEARING THIS
     LEGEND, FOR THE SECURITIES REPRESENTED HEREBY REGISTERED IN THE NAME
     OF SUCH HOLDER.  COPIES OF SUCH AGREEMENT MAY BE OBTAINED AT NO COST
     BY WRITTEN REQUEST MADE BY THE HOLDER OF RECORD OF THIS CERTIFICATE TO
     THE SECRETARY OF ADVANCED RADIO TECHNOLOGIES CORPORATION.

                          ADVANCED RADIO TELECOM CORP.

                          COMMON STOCK PURCHASE WARRANT


      ADVANCED RADIO TELECOM CORP. (the "Company"), having its principal office
at 500 108th Ave., N.E., Bellevue, WA 98004 hereby certifies that, for value
received, ____________________, or assigns, is entitled, subject to the terms
set forth below, to purchase from the


<PAGE>

Company at any time on or from time to time after March 8, 1996 and before 5:00
P.M., New York City time, on March __, 2001 (the "Expiration Date") _______
fully paid and non-assessable shares of Common Stock of the Company, at the
price per share (the "Purchase Price") of $6.25.  The number and character of
such shares of Common Stock and the Purchase Price are subject to adjustment as
provided herein.

     This Warrant is one of the Common Stock Purchase Warrants (the "Warrants")
originally issued as of the Original Issue Date (as defined below) and
evidencing the right to purchase an aggregate of 1,100,000 shares of Common
Stock of the Company, subject to adjustment as provided herein.

     As used herein the following terms, unless the context otherwise requires,
have the following respective meanings:

               (a)  The term "Company" includes any corporation which shall
succeed to or assume the obligations of the Company hereunder.

               (b)  The term "Common Stock" means the Common Stock, $.001 par
value, of the Company and its successors.

               (c)  The "Original Issue Date" is March __, 1996, the date as of
which the Warrants were first issued.

               (d)  The term "Other Securities" refers to any stock (other than
Common Stock) and other securities of the Company or any other person (corporate
or otherwise) which the holders of the Warrants at any time shall be entitled to
receive, or shall have received, upon the exercise of the Warrants, in lieu of
or in addition to Common Stock, or which at any time shall be issuable or shall
have been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to section 6 or otherwise.

               (e)  The term "Purchase Price" shall be the then applicable
exercise price for one share of Common Stock.

               (f)  The terms "registered" and "registration" refer to a
registration effected by filing a registration statement in compliance with the
Securities Act, to permit the disposition of Common Stock (or Other Securities)
issued or issuable upon the exercise of Warrants, and any post-effective
amendments and supplements filed or required to be filed to permit any such
disposition.

               (g)  The term "Securities Act" means the Securities Act of 1933
as the same shall be in effect at the time.


                                       -2-
<PAGE>

     1.   REGISTRATION, ETC.  The Company shall have the same obligations to the
holder of the Warrant as it has to the Investor Telecom Stockholders of the
Company as set forth in that certain Registration Rights Agreement by and among
the Company, the stockholders of the Company named therein, Advanced Radio
Technologies Corporation ("ART") and the stockholders of ART named therein.

     2.   SALE OR EXERCISE WITHOUT REGISTRATION.  If, at the time of any
exercise, transfer or surrender for exchange of a Warrant or of Common Stock (or
Other Securities) previously issued upon the exercise of Warrants, such Warrant
or Common Stock (or Other Securities) shall not be registered under the
Securities Act, the Company may require, as a condition of allowing such
exercise, transfer or exchange, that the holder or transferee of such Warrant or
Common Stock (or Other Securities), as the case may be, furnish to the Company a
satisfactory opinion of counsel to the effect that such exercise, transfer or
exchange may be made without registration under the Securities Act, provided
that the disposition thereof shall be in compliance with the provisions of the
Stockholders Agreement, and provided further that nothing contained in this
Section 2 shall relieve the Company from complying with any request for
registration pursuant to Section 1 hereof.

     3.   EXERCISE OF WARRANT; PARTIAL EXERCISE; CASHLESS EXERCISE.

          3.1. EXERCISE IN FULL.  Subject to the provisions hereof, this Warrant
may be exercised in full by the holder hereof by surrender of this Warrant, with
the form of subscription attached hereto as SCHEDULE I duly executed by such
holder, to the Company at its principal office accompanied by payment, in cash
or by certified or official bank check payable to the order of the Company, in
the amount obtained by multiplying the number of shares of Common Stock called
for on the face of this Warrant (without giving effect to any adjustment
therein) by the Purchase Price.

          3.2. PARTIAL EXERCISE.  Subject to the provisions hereof, this Warrant
may be exercised in part by surrender of this Warrant in the manner and at the
place provided in Section 3.1 except that the amount payable by the holder upon
any partial exercise shall be the amount obtained by multiplying (a) the number
of shares of Common Stock (without giving effect to any adjustment therein)
designated by the holder in the subscription at the end hereof by (b) the
Purchase Price.  Upon any such partial exercise, the Company at its expense will
forthwith issue and deliver to or upon the order of the holder hereof a new
Warrant or Warrants of like tenor, in the name of the holder hereof or as such
holder (upon payment by such holder of any applicable transfer taxes) may
request, calling in the aggregate on the face or faces thereof for the number of
shares of Common Stock equal (without giving effect to any adjustment therein)
to the number of such shares called for on the face of this Warrant minus the
number of such shares designated by the holder in the subscription at the end
hereof.

          3.3. EXERCISE BY SURRENDER OF WARRANT.  In addition to the method of
payment set forth in Sections 3.1 and 3.2 and in lieu of any cash payment
required thereunder, the


                                       -3-
<PAGE>

holder(s) of the Warrants shall have the right at any time and from time to time
to exercise the Warrants in full or in part by surrendering the Warrant
Certificate in the manner specified in Section 3.1 as payment of the aggregate
Purchase Price.  The number of Warrants to be surrendered in payment of the
aggregate Exercise Price for the Warrants to be exercised shall be determined by
multiplying the number of Warrants to be exercised by the Purchase Price, and
then dividing the product thereof by an amount equal to the Market Price (as
defined below).  Solely for the purposes of this paragraph, Market Price shall
be calculated as the average of the Market Prices for each of the ten (10)
trading days preceding the date which the form of election attached hereto is
deemed to have been sent to the Company ("Notice Date").

          3.4. DEFINITION OF MARKET PRICE.  As used herein, the phrase "Market
Price" at any date shall be deemed to be (i) if the principal trading market for
such securities is an exchange, the last reported sale price, or, in case no
such reported sale takes place on such date, the average of the last reported
sale prices for the last three (3) trading days, in either case as officially
reported on any consolidated tape, (ii) if the principal market for such
securities is the over-the-counter market, the high bid price on such date as
set forth by Nasdaq or, if the security is not quoted on Nasdaq, the high bid
price as set forth in the National Quotation Bureau sheet listing such
securities for such day.  Notwithstanding the foregoing, if there is no reported
closing price or high bid price, as the case may be, on the date next preceding
the event requiring an adjustment hereunder, then the Market Price shall be
determined as of the latest date prior to such day for which such closing price
or high bid price is available, or if the securities are not quoted on Nasdaq,
as determined in good faith by resolution of the Board of Directors of the
Company, based on the best information available to it.

          3.5. COMPANY TO REAFFIRM OBLIGATIONS.  The Company will, at the time
of any exercise of this Warrant, upon the request of the holder hereof,
acknowledge in writing its continuing obligation to afford to such holder any
rights (including, without limitation, any right to registration of the shares
of Common Stock or Other Securities issued upon such exercise) to which such
holder shall continue to be entitled after such exercise in accordance with the
provisions of this Warrant, PROVIDED that if the holder of this Warrant shall
fail to make any such request, such failure shall not affect the continuing
obligation of the Company to afford such holder any such rights.

     4.   DELIVERY OF STOCK CERTIFICATES, ETC., ON EXERCISE.  As soon as
practicable after the exercise of this Warrant in full or in part, and in any
event within 10 days thereafter, the Company at its expense (including the
payment by it of any applicable issue taxes) will cause to be issued in the name
of and delivered to the holder hereof, or as such holder (upon payment by such
holder of any applicable transfer taxes) may direct, a certificate or
certificates for the number of full paid and non-assessable shares of Common
Stock (or Other Securities) to which such holder shall be entitled upon such
exercise, plus, in lieu of any fractional share to which such holder would
otherwise be entitled, cash equal to such fraction multiplied by the then
current market value of one full share, together with any other stock or other
securities and property (including cash, where applicable) to which such holder
is entitled upon such exercise pursuant to Section 5


                                       -4-
<PAGE>

or otherwise.

     5.   ADJUSTMENT FOR DIVIDENDS IN OTHER STOCK, PROPERTY, ETC.;
RECLASSIFICATION, ETC.  In case at any time or from time to time after the
Original Issue Date the holders of Common Stock (or Other Securities) shall have
received, or (on or after the record date fixed for the determination of
stockholders eligible to receive) shall have become entitled to receive, without
payment therefor

               (a)  other or additional stock or other securities or property
     (other than cash) by way of dividend, or

               (b)  any cash paid or payable (including, without limitation, by
     way of dividend), except out of earned surplus of the Company, or

               (c)  other or additional (or less) stock or other securities or
     property (including cash) by way of spin-off, split-up, reclassification,
     recapitalization, combination of shares or similar corporate rearrangement,

then, and in each such case, the holder of this Warrant, upon the exercise
hereof as provided in Section 3, shall be entitled to receive the amount of
stock and other securities and property (including cash in the cases referred to
in subdivisions (b) and (c) of this Section 5 which such holder would hold on
the date of such exercise if on the Original Issue Date he had been the holder
of record of the number of shares of Common Stock called for on the face of this
Warrant and had thereafter, during the period from the Original Issue Date to
and including the date of such exercise, retained such shares and all such other
or additional (or less) stock and other securities and property (including cash
in the cases referred to in subdivisions (b) and (c) of this Section 5)
receivable by him as aforesaid during such period, giving effect to all
adjustments called for during such period by Sections 6 and 7 hereof.

     6.   REORGANIZATION, CONSOLIDATION, MERGER, ETC.

          In case the Company after the Original Issue Date shall (a) effect a
reorganization, (b) consolidate with or merge into any other person, or (c)
transfer all or substantially all of its properties or assets to any other
person under any plan or arrangement contemplating the dissolution of the
Company, then, in each such case, the holder of this Warrant, upon the exercise
hereof as provided in Section 3 at any time after the consummation of such
reorganization, consolidation or merger or the effective date of such
dissolution, as the case may be, shall be entitled to receive (and the Company
shall be entitled to deliver), in lieu of the Common Stock (or Other Securities)
issuable upon such exercise prior to such consummation or such effective date,
the stock and other securities and property (including cash) to which such
holder would have been entitled upon such consummation or in connection with
such dissolution, as the case may be, if such holder had so exercised this
Warrant immediately prior thereto, all subject to further adjustment thereafter
as provided in Sections 5 and 7 hereof.


                                       -5-
<PAGE>

     7.   OTHER ADJUSTMENTS.

          7.1. GENERAL.  In any case to which Sections 5 and 6 hereof are not
applicable, where the Company shall issue or sell shares of its Common Stock
after the Original Issue Date without consideration or for a consideration per
share less than the Purchase Price in effect pursuant to the terms of this
Warrant at the time of issuance or sale of such additional shares, except where
such shares are issued or sold pursuant to the exercise of any warrant or option
or issued prior to the date of this Warrant, then the Purchase Price in effect
hereunder shall simultaneously with such issuance or sale be reduced to a price
determined by dividing (1) an amount equal to (a) the total number of shares of
Common Stock outstanding immediately prior to such issuance or sale multiplied
by the Purchase Price in effect hereunder at the time of such issuance or sale,
plus (b) the consideration, if any, received by the Company upon such issuance
or sale, by (2) the total number of shares of Common Stock outstanding
immediately after issuance or sale of such additional shares, and the number of
shares of Common Stock which may be purchased upon exercise of this Warrant
shall be increased so that the aggregate amount to be paid upon full exercise of
this Warrant, after giving effect to each reduction in the Purchase Price, shall
not be reduced.

          7.2. CONVERTIBLE SECURITIES.  In case the Company shall issue or sell
any securities convertible into Common Stock of the Company ("Convertible
Securities") after the date hereof, there shall be determined the price per
share for which Common Stock is issuable upon the conversion or exchange
thereof, such determination to be made by dividing (a) the total amount received
or receivable by the Company as consideration for the issue or sale of such
Convertible Securities, plus the minimum aggregate amount of additional
consideration, if any, payable to the Company upon the conversion or exchange
thereof, by (b) the maximum number of shares of Common Stock of the Company
issuable upon the conversion or exchange of all of such Convertible Securities.

               If the price per share so determined shall be less than the
applicable Purchase Price, then such issue or sale shall be deemed to be an
issue or sale for cash (as of the date of issue or sale of such Convertible
Securities) of such maximum number of shares of Common Stock at the price per
share so determined, provided that, if such Convertible Securities shall by
their terms provide for an increase or increases, with the passage of time, in
the amount of additional consideration, if any, to the Company, or in the rate
of exchange, upon the conversion or exchange thereof, the adjusted Purchase
Price shall, forthwith upon any such increase becoming effective, be readjusted
to reflect the same, and provided further, that upon the expiration of such
rights of conversion or exchange of such Convertible Securities, if any thereof
shall not have been exercised, the adjusted Purchase Price shall forthwith be
readjusted and thereafter be the price which it would have been had an
adjustment been made on the basis that the only shares of Common Stock so issued
or sold were issued or sold upon the conversion or exchange of such Convertible
securities, and that they were issued or sold for the consideration actually
received by the Company upon such conversion or exchange, plus the
consideration, if any, actually received by the Company for the issue or sale of
all of such Convertible Securities


                                       -6-
<PAGE>

which shall have been converted or exchanged.

          7.3. RIGHTS AND OPTIONS.  In case the Company shall grant any rights
or options to subscribe for, purchase or otherwise acquire Common Stock, there
shall be determined the price per share for which Common Stock is issuable upon
the exercise of such rights or options, such determination to be made by
dividing (a) the total amount, if any, received or receivable by the Company as
consideration for the granting of such rights or options, plus the minimum
aggregate amount of additional consideration payable to the Company upon the
exercise of such rights or options, by (b) the maximum number of shares of
Common Stock of the Company issuable upon the exercise of such rights or
options.

               If the price per share so determined shall be less than the
applicable Purchase Price, then the granting of such rights or options shall be
deemed to be an issue or sale for cash (as of the date of the granting of such
rights or options) of such maximum number of shares of Common Stock at the price
per share so determined, provided that, if such rights or options shall be their
terms provide for an increase or increases, with the passage of time, in the
amount of additional consideration payable to the Company upon the exercise
thereof, the adjusted purchase price per share shall, forthwith upon any such
increase becoming effective, be readjusted to reflect the same, and provided,
further, that upon the expiration of such rights or options, if any thereof
shall not have been exercised, the adjusted Purchase Price shall forthwith be
readjusted and thereafter be the price which it would have been had an
adjustment been made on the basis that the only shares of Common Stock so issued
or sold were those issued or sold upon the exercise of such rights or options
and that they were issued or sold for the consideration actually received by the
Company upon such exercise, plus the consideration, if any, actually received by
the Company for the granting of all such rights or options, whether or not
exercised.

     8.   FURTHER ASSURANCES.  The Company will take all such action as may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and non-assessable shares of stock upon the exercise of all Warrants
from time to time outstanding.

     9.   ACCOUNTANTS' CERTIFICATE AS TO ADJUSTMENTS.  In each case of any
adjustment or readjustment in the shares of Common Stock (or Other Securities)
issuable upon the exercise of the Warrants, the Company at its expense will
promptly cause the Company's regularly retained auditor to compute such
adjustment or readjustment in accordance with the terms of the Warrants and
prepare a certificate setting forth such adjustment or readjustment and showing
in detail the facts upon which such adjustment or readjustment is based, and the
number of shares of Common Stock outstanding or deemed to be outstanding.  The
Company will forthwith mail a copy of each such certificate to each holder of a
Warrant.

     10.  NOTICES OF RECORD DATE, ETC.  In the event of

               (a)  any taking by the Company of a record of the holders of any
     class of securities for the purpose of determining the holders thereof who
     are entitled


                                       -7-
<PAGE>

     to receive any dividend (other than a cash dividend payable out of earned
     surplus of the Company) or other distribution, or any right to subscribe
     for, purchase or otherwise acquire any shares of stock of any class or any
     other securities or property, or to receive any other right, or

               (b)  any capital reorganization of the Company, any
     reclassification or recapitalization of the capital stock of the Company or
     any transfer of all or substantially all the assets of the Company to or
     consolidation or merger of the Company with or into any other person, or

               (c)  any voluntary or involuntary dissolution, liquidation or
     winding-up of the Company, or

               (d)  any proposed issue or grant by the Company of any shares of
     stock of any class or any other securities, or any right or option to
     subscribe for, purchase or otherwise acquire any shares of stock of any
     class or any other securities (other than the issue of Common Stock on the
     exercise of the Warrants), then and in each such event the Company will
     mail or cause to be mailed to each holder of a Warrant a notice specifying
     (i) the date on which any such record is to be taken for the purpose of
     such dividend, distribution or right, and stating the amount and character
     of such dividend, distribution or right, (ii) the date on which any such
     reorganization, reclassification, recapitalization, transfer,
     consolidation, merger, dissolution, liquidation or winding-up is to take
     place, and the time, if any, as of which the holders of record of Common
     Stock (or Other Securities) shall be entitled to exchange their shares of
     Common Stock (or Other Securities) for securities or other property
     deliverable upon such reorganization, reclassification, recapitalization,
     transfer, consolidation, merger, dissolution, liquidation or winding-up,
     and (iii) the amount and character of any stock or other securities, or
     rights or options with respect thereto, proposed to be issued or granted,
     the date of such proposed issue or grant and the persons or class of
     persons to whom such proposed issue or grant and the persons or class of
     persons to whom such proposed issue or grant is to be offered or made.
     Such notice shall be mailed at least 20 days prior to the date therein
     specified.

     11.  RESERVATION OF STOCK, ETC., ISSUABLE ON EXERCISE OF WARRANTS.  The
Company will at all times reserve and keep available, solely for issuance and
delivery upon the exercise of the Warrants, all shares of Common Stock (or Other
Securities) from time to time issuable upon the exercise of the Warrants.

     12.  LISTING ON SECURITIES EXCHANGES; REGISTRATION.  If the Company at any
time shall list any Common Stock on any national securities exchange and shall
register such Common Stock under the Securities Exchange Act of 1934 (as then in
effect, or any similar statute then in effect), the Company will, at its
expense, simultaneously list on such exchange, upon official


                                       -8-
<PAGE>

notice of issuance upon the exercise of the Warrants, and maintain such listing
of all shares of Common Stock from time to time issuable upon the exercise of
the Warrants; and the Company will so list on any national securities exchange,
will so register and will maintain such listing of, any Other Securities if and
at the time that any securities of like class or similar type shall be listed on
such national securities exchange by the Company.

     13.  EXCHANGE OF WARRANTS.  Subject to the provisions of Section 2 hereof,
upon surrender for exchange of any Warrant, properly endorsed, to the Company,
the Company at its own expense will issue and deliver to or upon the order of
the holder thereof a new Warrant or Warrants of like tenor, in the name of such
holder or as such holder (upon payment by such holder of any applicable transfer
taxes) may direct, calling in the aggregate on the face or faces thereof for the
number of shares of Common Stock called for on the face or faces of the Warrant
or Warrants so surrendered.

     14.  REPLACEMENT OF WARRANTS.  Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of any
Warrant and, in the case of any such loss, theft or destruction, upon delivery
of an indemnity agreement reasonably satisfactory in form and amount to the
Company or, in the case of any such mutilation, upon surrender and cancellation
of such Warrant, the Company at its expense will execute and deliver, in lieu
thereof, a new Warrant of like tenor.

     15.  WARRANT AGENT.  The Company may, by written notice to each holder of a
Warrant, appoint an agent having an office in New York, New York, for the
purpose of issuing Common Stock (or Other Securities) upon the exercise of the
Warrants pursuant to Section 3, exchanging Warrants pursuant to Section 13, and
replacing Warrants pursuant to Section 14, or any of the foregoing, and
thereafter any such issuance, exchange or replacement, as the case may be, shall
be made at such office by such agent.

     16.  REMEDIES.  The Company stipulates that the remedies at law of the
holder of this Warrant in the event of any default or threatened default by the
Company in the performance of or compliance with any of the terms of this
Warrant are not and will not be adequate, and that such terms may be
specifically enforced by a decree for the specific performance of any agreement
contained herein or by an injunction against a violation of any of the terms
hereof or otherwise.

     17.  NEGOTIABILITY, ETC.  This Warrant is issued upon the following terms,
to all of which each holder or owner hereof by the taking hereof consents and
agrees:

               (a)  subject to the provisions hereof, title to this Warrant may
     be transferred by endorsement (by the holder hereof executing the form of
     assignment attached hereto as SCHEDULE II) and delivery in the same manner
     as in the case of a negotiable instrument transferable by endorsement and
     delivery;

               (b)  subject to the foregoing, any person in possession of this


                                       -9-
<PAGE>

     Warrant properly endorsed is authorized to represent himself as absolute
     owner hereof and is empowered to transfer absolute title hereto by
     endorsement and delivery hereof to a bona fide purchaser hereof for value;
     each prior taker or owner waives and renounces all of his equities or
     rights in this Warrant in favor of each such bona fide purchaser and each
     such bona fide purchaser shall acquire absolute title hereto and to all
     rights represented hereby; and

               (c)  until this Warrant is transferred on the books of the
     Company, the Company may treat the registered holder hereof as the absolute
     owner hereof for all purposes, notwithstanding any notice to the contrary.

     18.  NOTICES, ETC.  All notices and other communications from the Company
to the holder of this Warrant shall be mailed by first class registered or
certified mail, postage prepaid, at such address as may have been furnished to
the Company in writing by such holder, or, until an address is so furnished, to
and at the address of the last holder of this Warrant who has so furnished an
address to the Company.

     19.  MISCELLANEOUS.  This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.  This Warrant is being delivered in the State of New York and shall
be construed and enforced in accordance with and governed by the laws of such
State.  The headings in this Warrant are for purposes of reference only, and
shall not limit or otherwise affect any of the terms hereof.

     20.  ASSIGNABILITY.  Subject to the transfer conditions referred to in the
legend endorsed hereon, this Warrant is fully assignable at any time upon
surrender of this Warrant with a properly executed Assignment (in the form of
SCHEDULE II hereto) at the principal office of the Company.


Dated:  March __, 1996
                                             ADVANCED RADIO TELECOM CORP.


                                             By
                                               ---------------------------------
[Corporate Seal]

Attest:



- -----------------------------
          Secretary


                                      -10-
<PAGE>

                                   SCHEDULE I
                              FORM OF SUBSCRIPTION
                  (To be signed only upon exercise of Warrant)

To:  ADVANCED RADIO TELECOM CORP.

     The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder,     *     shares of Common Stock of ADVANCED RADIO TELECOM
CORP., and herewith makes payment of
$          therefor, and requests that the certificates for such shares be
issued in the name of, and delivered to,                  , whose address is


Dated:


                              -----------------------------------------
                              (Signature must conform in all respects to name of
                              holder as specified on the face of the Warrant)


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



- ------------------------
*    Insert here the number of shares called for on the face of the Warrant (or,
     in the case of a partial exercise, the portion thereof as to which the
     Warrant is being exercised), in either case without making any adjustment
     for additional Common Stock or any other stock or other securities or
     property or cash which, pursuant to the adjustment provisions of the
     Warrant, may be deliverable upon exercise.


                                      -11-
<PAGE>

                                   SCHEDULE II

                               FORM OF ASSIGNMENT

                  (To be signed only upon transfer of Warrant)



     For value received, the undersigned hereby sells, assigns and transfers
unto                                                        the right
represented by the within Warrant to purchase               shares of Common
Stock of [_____________] to which the within Warrant relates, and appoints
                      Attorney to transfer such right on the books of
[_________________] with full power of substitution in the premises.  The
Warrant being transferred hereby is one of an aggregate of [___________] Common
Stock Purchase Warrants issued by [______________] as of [_______________], 19__

Dated:


                              -----------------------------------------
                              (Signature must conform in all respects to name of
                              holder as specified on the face of the Warrant)


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



- ------------------------
Signature guaranteed by a Bank
or Trust Company having its
principal office in New York City
or by a Member Firm of the New
York or American Stock Exchange


                                      -12-
<PAGE>

                                    EXHIBIT C


                                  RISK FACTORS


     AN INVESTMENT IN THE SECURITIES INVOLVES A HIGH DEGREE OF RISK. THE
FOLLOWING RISK FACTORS SHOULD BE CONSIDERED WHEN EVALUATING AN INVESTMENT IN THE
SECURITIES.

LIMITED OPERATING HISTORY; HISTORY OF LOSSES; ANTICIPATED FUTURE OPERATING
LOSSES

     Since its inception in 1993, the Company has received only minimal revenues
and has experienced a history of net losses.  Although the Company has initiated
efforts to develop a network using 38 GHz technology and market its 38 GHz
services to potential customers, the Company currently provides its services
only on a limited basis in five cities.  The Company's primary activities to
date have focused on the acquisition of wireless licenses, the hiring of
management and other key personnel and the acquisition of the equipment
necessary to provide 38 GHz services.  The Company has made significant
expenditures related to the development of its wireless telecommunications
services and expects to incur significant additional expenses and operating
losses as the development and expansion of its telecommunications business
continues.  The Company's limited operating history makes the prediction of
future operating results difficult or impossible, and there can be no assurance
that the Company will establish a significant customer base or achieve or
sustain profitable operations.

ABILITY TO SERVICE INDEBTEDNESS

     Although the proceeds from sale of the Notes, expected to be approximately
$5,000,000 prior to expenses, are expected to enhance liquidity and improve the
Company's financial flexibility in the near term, the Company's total
indebtedness and total interest expense will be significantly increased as a
result of the issuance of the Notes.

     The level of the Company's indebtedness could have important consequences
to holders of the Notes, including the following:  (i) the debt service
requirements of any additional indebtedness could make it more difficult for the
Company to make payments on the notes; (ii) the ability of the Company to obtain
any necessary financing in the future for working capital, capital expenditures,
debt service requirements or other purposes may be limited; (iii) a substantial
portion of the company's cash flow from operations, if any, must be dedicated to
the payment of principal and interest on its indebtedness and other obligations
and will not be available for other purposes; (iv) the Company's level of
indebtedness could limit its flexibility in planning for, or reacting to changes
in, its business; (v) the Company is more highly leveraged than some of its
competitors, which may place it at a competitive disadvantage; and (vi) the
Company's high degree of indebtedness could make it more vulnerable in the event
of a downturn in its business.

     If the Company is unable to obtain additional financing sufficient to meet
its obligations or fund its operations, the Company could face substantial
liquidity problems and could cause defaults under other indebtedness of the
Company.  Such defaults could result in a default on the Notes and


<PAGE>

could delay or preclude payment of principal of, or interest on, the Notes.

NEED FOR ADDITIONAL FINANCING

     The Company will require substantial investment capital for the development
and expansion of its wireless telecommunications operations, the continued
funding of related operating expenses, and for the possible acquisition of
additional licenses or other assets or businesses.  Based on its current plan of
development, management anticipates that the net proceeds of this offering and
existing financial resources will be sufficient to fund the Company for the next
seven months.  Management believes that the Company's capital needs at the end
of this seven month period will continue to be significant and that it may be
necessary for the Company to continue to seek additional sources of financing.
In addition, if the Company's plan of development or projections change or prove
to be inaccurate, or the proceeds of this Offering, together with other existing
financial resources, prove to be insufficient to fund the Company for the next
four months, or if the Company completes any acquisitions, the Company may be
required to seek additional financing sooner than currently anticipated.  Such
additional financing may take the form of public and private equity or debt
offerings, sales of assets and other financing arrangements.  There can be no
assurance that the Company will be able to obtain any additional financing, or,
if such financing is available, that the Company will be able to obtain it on
acceptable terms.  In the event that the Company fails to obtain additional
financing, such failure could result in the modification, delay or abandonment
of some or all of the Company's development and expansion plans.  Any such
modification, delay or abandonment is likely to have a material adverse effect
on the Company's business, which could adversely affect the value of the Common
Stock and the Company's ability to make principal and interest payments related
to the Notes.

GOVERNMENT REGULATION; FCC LICENSES

     The telecommunication services offered by the Company are subject to
varying degrees of federal, state and local regulation.  The Federal
Communications Commission ("FCC") exercises jurisdiction over all
telecommunications services providers to the extent such services involve the
provision of jurisdictionally interstate or international telecommunications,
including the resale of long distance services and the provision of local access
services necessary to connect callers to long distance carriers.  The state
regulatory commissions retain jurisdiction over services to the extent such
services involve the provision of jurisdictionally intrastate
telecommunications.  The Company, as a provider of facilities-based local
telecommunications services, files tariffs with the FCC and for some services
with state authorities for domestic service on an ongoing basis. Failure to
obtain state authorizations could prevent the Company from offering some of its
services or delay such offerings.   Challenges to these tariffs by third parties
could cause the Company to incur substantial legal and administrative expenses.
Additionally, the Company expects that, as its business and product lines expand
as regulatory initiatives favoring competition in the provision of local
telecommunications services are adopted and implemented, it will offer increased
intrastate services which will be subject to state regulation.  In its provision
of local telecommunications services, the Company currently is not subject to
price-cap or rate-of-return regulation by the


                                       -2-
<PAGE>

FCC.  The Company is, however, required to comply with all applicable local
zoning and other ordinances governing the installation and operation of its
wireless telecommunications services.

     Although the Company believes that it is in substantial compliance with all
material laws, rules and regulations governing its operations and has obtained,
or is in the process of obtaining, all authorizations, tariffs and approvals
necessary and appropriate to conduct its operations, changes in existing laws
and regulations, including those relating to the provision of wireless local
telecommunications services via 38 GHz and/or the future granting of 38 GHz
authorizations, or any failure or significant delay in obtaining necessary
regulatory approvals, could have a material adverse effect on the Company.  In
recent periods, the FCC has increasingly looked for opportunities to raise funds
for the government by auctioning portions of the radio spectrum.  In addition,
the FCC is considering the possibility of allocating additional portions of the
radio spectrum (above and below 38 GHz) for commercial use.  The FCC recently
issued an order that prohibits any additional 38 GHz applications, pending
conclusion of a proposed rulemaking.  The Company believes that the FCC will
continue to propose and/or adopt rules to auction portions of the radio spectrum
available for commercial use, which may include pending or proposed applications
in 38 GHz and other portions of the radio spectrum.  The FCC might at the same
time limit operations under existing licenses or might dismiss all pending 38
GHz applications, in order to auction the spectrum which the applicants seek.
In the event that an auction procedure is proposed, which the Company believes
is currently being considered, or adopted by the FCC for granting additional
authorizations in 38 GHz or other portions of the radio spectrum, changes to the
existing regulations governing 38 GHz, such as stricter construction
requirements, might be adopted, which could have an impact on the scope of the
Company's authorizations and the operations of present and future licensees,
including the Company.  The Company is unable to predict the impact upon its
proposed operations should some or all of these events occur, except that the
failure of the Commission to grant some or all of its pending applications or
actions of the FCC to restrict operations under the Company's licenses could
have a material adverse effect upon the Company.

      Many of the Company's licenses will expire in March 2001.  Although the
Company currently anticipates that the licenses will be renewed based upon the
Commission's custom and practice establishing a presumption in favor of
licensees that have complied with regulatory obligations during the initial
license period, there can be no assurance that all or any of the Company's
licenses will be renewed upon expiration of their initial terms.  In the event
that the FCC does not renew one or more of the Company's licenses, the Company's
business and results of operations are likely to be materially adversely
affected.

     Legislation to substantially revise the Communications Act was recently
enacted.  The legislation establishes local exchange competition as a national
policy by allowing the FCC to preempt laws that prohibit competition in the
local exchange and by the establishment of uniform and fair requirements and
standards for interconnection and unbundling of services.  To the extent this
legislation, and its successful implementation by the FCC, establish fair, cost-
based, enforceable national standards of interconnection and unbundling for
local exchange services, it


                                       -3-
<PAGE>

could significantly enhance the Company's ability and the ability of the
Company's customers to improve their competitive position in local  exchange
markets.  The proposed legislation could also permit a Regional Bell Operating
Company ("RBOC") to compete in the provision of inter-Local Access and Transport
Area ("inter-LATA") long distance services once certain time periods have
elapsed or certain competitive characteristics emerge in such RBOC's service
area.   There can be no assurance that any legislation or regulation will
broaden the opportunities available to the Company or will not have a material
adverse effect upon the Company and its operations.

     The value of the licenses held or acquired hereafter by the Company will
depend significantly upon the success of the Company's wireless
telecommunications operations and the future direction of the wireless
telecommunications segment of the telecommunications industry.  The value of the
licenses may also be affected by fluctuations in the level of supply and demand
for such licenses.  Any assignment of a license or transfer of control by an
entity holding a license is subject to certain restrictions and limitations
relating to the identity and status of the transferee and requires prior FCC
and/or state regulatory approval.  These restrictions and limitations, and the
regulatory approval requirements, may serve to adversely affect the value of the
Company's licenses.

EMERGING MARKET; UNCERTAIN ACCEPTANCE OF 38 GHZ SERVICES

     The Company has only recently initiated efforts to market its DigiWave
Access Link services to potential customers, and has received only insignificant
revenues to date.  The provision of wireless local telecommunications services
over 38 GHz represents an emerging sector of the telecommunications industry and
the demand for and acceptance of such services are uncertain. There can be no
assurance that substantial markets will develop for wireless local
telecommunications services delivered over 38 GHz, or that, even if such markets
develop, that the Company will be able to succeed in its efforts to attract and
maintain a sufficient customer base, or that it will be able to operate
profitably given the price competition that is common in the market for
telecommunications services.

NEW SERVICES AND TECHNOLOGICAL CHANGE

     The telecommunications industry has been characterized by rapid
technological change, frequent new service introductions and evolving industry
standards.  The Company expects these changes to continue, and believes that its
future success will depend on its ability to anticipate or adapt to such changes
and to offer new services or enhancements to existing services that meet these
evolving industry standards. There can be no assurance that existing or proposed
technology or service introductions, or technology or services developed and
implemented in the future, will not render 38 GHz-based telecommunications
services less profitable or obsolete.  There can be no assurance that the
Company will have sufficient resources to develop or acquire new technologies or
to introduce new services that could compete with future technologies or service
offerings or that equipment held by the Company in inventory will not be
rendered less valuable or obsolete.


                                       -4-
<PAGE>

COMPETITION

     The market for telecommunications services is characterized by substantial
competition.  Although the Company was formed in 1993, it has just recently
begun to market its wireless telecommunications services to potential customers
and is currently providing wireless services to a very limited number of
customers. Many of the Company's competitors have long-standing relationships
with customers and suppliers, industries, greater name recognition and
significantly greater financial, technical and marketing resources than the
Company.  As a result, these competitors may be able to more quickly develop and
exploit new or emerging technologies, adapt to changes in customer requirements,
or devote greater resources to the marketing of their services than the Company.
Furthermore, current and potential competitors have established or may establish
cooperative relationships among themselves or with third parties to increase
their ability to address the telecommunications needs of the Company's existing
and prospective customers.  In each area in which the Company is authorized or
may be authorized under the licenses to provide services, the Company's services
compete with those offered by the LECs, such as the Regional Bell Operating
Companies.  The LECs have long-standing relationships with their customers, have
the potential to subsidize competitive services with revenues from a variety of
businesses, and benefit from existing state and federal policies and regulations
that currently favor the LECs over the Company in certain respects.

     While certain regulatory decisions have provided increased business
opportunities for CAPs and other telecommunications providers such as the
Company, these same decisions have given the LECs flexibility to decrease prices
of their competitive services such as local access charges paid by long distance
carriers utilizing the LECs' local networks.  Regulatory decisions affording the
LECs increased pricing flexibility or other regulatory relief or benefits also
could have a material adverse effect on the Company.  Further, as competition
increases in the local telecommunications market, pricing competition and
pressures could significantly increase.  In September 1995, the FCC announced
proposals that, if adopted, would significantly lessen the regulation of LECs
that are subject to competition in their service areas and would provide such
LECs with greater pricing flexibility.  If the LECs lower their rates, CAPs and
other telecommunications providers such as the Company may be forced by market
conditions to charge less for their services in order to compete. Any such price
reduction could have a material adverse effect on the Company's results of
operations.

     In addition to competition from the LECs, the Company also faces
competition from at least one fiber optic-based CAP in most of the markets in
which it offers services.  The Company also may face competition from new market
entrants, including CAPs which deliver services over fiber optic- and copper-
based networks, as well as competitors offering wireless telecommunications
services, including leading telecommunications companies and other entities
which hold or have applied for licenses in the 38 GHz band in many larger
metropolitan areas or which may purchase such licenses from others.  The
granting of additional licenses by the FCC in the 38 GHz band, or other portions
of the spectrum which have characteristics that would allow the provision of
services similar to those provided by the Company, would result in increased
competition.  The Company


                                       -5-
<PAGE>

also may face competition from cable television companies, electric utilities,
LECs operating outside their current local service areas and long distance
carriers in the provision of local telecommunications services.  The great
majority of these entities provide transmission services primarily over fiber
optic-, copper-based or microwave networks, which, unlike the Company's DigiWave
Access Link services, enjoy proven market acceptance for the carriage of
telecommunications traffic.  The consolidation of telecommunications companies
and the formation of strategic alliances within the telecommunications industry,
as well as the development of new technologies, could give rise to significant
new competitors to the Company.  There can be no assurance that the Company will
be able to compete effectively in any of its markets.

RELIANCE ON SUPPLIERS AND EQUIPMENT PERFORMANCE

     The Company currently purchases all of its 38 GHz wireless
telecommunications equipment from a single supplier.  Any reduction or
interruption in supply from this supplier could have a material adverse effect
on the Company until alternative supply sources are established. To date, the
Company has not experienced any delays in obtaining the necessary equipment. The
Company does not manufacture, nor does it have the capability to manufacture,
any of the telecommunications equipment necessary to provide its wireless
telecommunications services.  Although there are several other manufacturers who
have, or are developing, equipment that would meet the Company's requirements,
there can be no assurance that such equipment would be available to the Company
on terms similar or more favorable to those included in its arrangements with
its current supplier.

TECHNOLOGICAL LIMITATIONS: LINE OF SIGHT; ROOF RIGHTS; RAIN ATTENUATION

     Wireless telecommunications services over 38 GHz require a line of sight
between two transceivers comprising a link, with a maximum distance between any
two corresponding transceivers generally of five miles or less (depending on
weather conditions).  This line of sight condition generally can be met by
careful network engineering, some locations may require intermediate
transceivers, which will increase the cost of the service and might make a
particular path uneconomical to provide.  Similarly, the distance limitation
generally will not affect a local distribution service and can be overcome by
adding intermediate links or using lower frequencies.  However, use of lower
frequency microwave for longer paths might create delays of several months in
providing services.  Wireless links at 38 GHz also are subject to outages in
severe rain conditions. The length and severity of these outages can be reduced,
and in many cases eliminated, by the use of shorter paths, route diversity or
"hot standby" equipment.  Each of these solutions, however, increases the cost
of the providing of the service and might make the providing of service in a
given instance uneconomical.   The establishment of wireless services also
generally requires access to roofs or other structures to allow the Company to
install its transceivers and antennas.   In order to obtain the necessary access
the Company generally must secure "roof rights" from the owners of each building
or other structure upon which its equipment will be placed.  There can be no
assurance that the Company will be successful in obtaining the roof rights
necessary to establish its DigiWave Access Link services in its potential
markets, or that delays in


                                       -6-
<PAGE>

obtaining such rights would not have a material adverse effect on the Company's
development of a wireless network.

MANAGEMENT OF GROWTH

     The Company is currently pursuing and experiencing a period of rapid growth
that has placed, and may continue to place, a significant strain on its
managerial, operational and financial resources.  The Company's success will
depend on its ability to manage growth effectively and to enhance its
operational and financial control and information systems, and on its ability to
attract, assimilate and retain additional qualified personnel necessitated by
the Company's growth.  Failure by the Company to meet the demands of and to
manage expansion of its business and operations could have a material adverse
effect on the Company's business.

DEPENDENCE ON KEY EMPLOYEES

     The Company's success is substantially dependent on Vernon Fotheringham and
Steven Comrie, its Chairman and President, the loss of one or more of whom could
have a material adverse effect on the Company. The future success of the Company
will also depend in large part on its ability to attract and retain talented and
qualified employees.  Competition in the recruitment of highly-qualified
personnel in the telecommunications industry is intense.  There can be no
assurance that the Company can retain its key employees or that it can attract,
assimilate and retain qualified personnel in the future.

CONCENTRATION OF SHARE OWNERSHIP; CONTROL BY LANDOVER HOLDINGS CORPORATION;
STOCKHOLDERS AGREEMENT

     Landover Holdings Corporation and its affiliates, as a group, will
beneficially own approximately 50.1% of the Company's outstanding Common Stock,
and, under the terms of the Stockholders Agreement, can designate a majority of
the directors of the Company.  As a result, these stockholders will be able to
exercise significant influence over all matters requiring stockholder approval,
including the election of directors and approval of significant corporate
transactions. In addition, this concentration of ownership may have the effect
of delaying or preventing a change in control of the Company.  On February 1,
1995, Laurence Zimmerman, who controls Landover Holdings Corporation, consented
to entry of an order of the SEC, without admitting or denying the matters
referred to therein, providing that he was barred through February 1, 1996 from
association with any broker, dealer, municipal securities dealer, investment
company or investment adviser.  The order relates to alleged violations of
Section 17(a) of the Securities Act, Section 10(b) and 15 (c)(1) of the
Securities Exchange Act of 1934 and Rules 10b-5 and 15c1-2 thereunder arising
out of actions allegedly done by Mr. Zimmerman in 1986, when he was 26 years old
and a broker for Breuer Capital, in connection with trading and selling shares
of Balchem Corporation.


                                       -7-
<PAGE>

LACK OF PUBLIC TRADING MARKET; DETERMINATION OF OFFERING PRICE

     Prior to this offering, there has been no public market for the Company's
Securities.  The exercise price of the Warrants has been determined solely by
the Board of Directors of the Company.

EFFECT OF OUTSTANDING OPTIONS, WARRANTS AND RIGHTS

     As of February 9, 1996, there are outstanding options, warrants, rights and
other convertible securities with respect to an aggregate of 1,929,368 shares of
Common Stock at per-share exercise prices ranging from $.001 to $1.652.  The
exercise of outstanding stock options, warrants, rights and other convertible
securities will dilute the percentage ownership of the holders of the Company's
Common Stock.

ABSENCE OF DIVIDENDS ON COMMON STOCK

     The Company has not paid and does not anticipate paying any cash dividends
on its Common Stock in the foreseeable future, but instead intends to retain its
capital for use in the Company's growth and ongoing operations.

PUT/CALL

     Ameritech Development Corporation has the right, commencing February 2,
1997, to put its Series F Preferred Stock to the Company for $2,500,000 in the
event the Company fails to enter into a proposed strategic distribution
agreement with Ameritech Corp. by May 3, 1996.  Exercise of such put may
adversely affect the Company's ability to repay the Notes.

ANTITAKEOVER PROVISIONS; POSSIBLE FUTURE ISSUANCES OF  PREFERRED STOCK

     The Certificate of Incorporation of the Company allows the Board of
Directors to issue up to 10,000,000 shares of Preferred Stock and fix the
rights, privileges and preferences of those shares without any further vote or
action by the shareholders.  The rights of the holders of Common Stock will be
subject to, and may be adversely affected by, the rights of the holders of any
Preferred Stock that may be issued in the future.  While the Company has no
present intention to issue additional shares of Preferred Stock, any such
issuance could be used to discourage, delay or make more difficult a change in
control of the Company.

RANKING OF NOTES AS UNSECURED OBLIGATIONS

     The Notes are not secured by any of the assets of the Company and are
general unsecured obligations of the Company.  The Company and its subsidiaries
are permitted to incur a substantial amount of secured indebtedness.  In the
event of any distribution or payment of the assets of the Company in any
foreclosure, dissolution, winding-up, liquidation or reorganization, holders of


                                       -8-
<PAGE>

secured indebtedness will have a secured prior claim to the assets of the
Company which constitute their collateral.  In the event of a bankruptcy,
liquidation or reorganization of the Company, holders of the Notes will
participate ratably with all holders of indebtedness of the Company which is
unsecured and all other general creditors of the Company, based upon the
respective amounts owed to each holder or creditor in the remaining assets of
the Company, and there may not be sufficient assets to pay amounts due on the
Notes.

ORIGINAL ISSUE DISCOUNT

     The Notes will be issued in a Unit with Warrants which may result in a
deemed original issue discount on the Notes from their principal amount at
maturity.  Consequently, purchasers of Notes may be required to include amounts
in gross income for federal income tax purposes in advance of receipt of the
cash payments to which the income is attributable.

MERGER

  The Company and ART Corp. plan to merge, subject only to FCC approval of the
Merger; however, while management believes that such approval will be obtained,
there can be no assurance that the Merger will be approved.  Until the Merger is
approved, the Company will continue to be able to operate its business, using
the wireless licenses owned by ART Corp., under the Services Agreement.  If the
Merger is not approved by May 13, 1997, ART Corp. will surrender all its shares
of Company Common Stock to the Company, and the Company and ART Corp. will
revise the terms of the Services Agreement to provide that (i) the term thereof
will be extended to 40 years, (ii) ART Corp. will receive, in the event of any
dividends paid by the Company to its stockholders, an amount equal to the
percentage share of the Company on that date that the ART Corp. stockholders
would have received in the Merger of such aggregate dividends, (iii) ART Corp.
would have a right of co-sale, subject to FCC approval, in accordance with such
percentage share in the event of any merger or sale of substantial assets by the
Company and (iv) in the event the Company agrees to merge into another entity or
to sell substantially all its assets to another entity, ART Corp. shall, upon
the request of the Company, use its best efforts, subject to FCC approval, to
merge into such entity or sell substantially all its assets to such entity for
aggregate consideration equal to such percentage share of the aggregate
consideration to be paid for ART Corp. and the Company in such transaction.


                                       -9-


<PAGE>

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


                           ASSET ACQUISITION AGREEMENT

                           AND PLAN OF REORGANIZATION

                            Dated as of July 3, 1996

                                  By and Among

                                 COMMCOCCC, INC.

                              CCC MILLIMETER, L.P.

                    COLUMBIA MILLIMETER COMMUNICATIONS, L.P.

                          COLUMBIA CAPITAL CORPORATION

                                 COMMCO, L.L.C.

                     ADVANCED RADIO TECHNOLOGIES CORPORATION

                                       and

                          ADVANCED RADIO TELECOM CORP.

                      -------------------------------------
                      -------------------------------------
 
<PAGE>

                                             TABLE OF CONTENTS


<TABLE>
<CAPTION>

<S>                                                                                                  <C>
 
ARTICLE I



          DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    2

ARTICLE II



          TRANSFER AND ACQUISITION . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .     8
             Section    2.1   Transfer and Acquisition. . . . . . . . . . . . . . . . . . . . . . .     8
             Section    2.2   No Assumption of Liabilities  . . . . . . . . . . . . . . . . . . . .     8
ARTICLE III



          CLOSING . . . . . .   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     9
             Section    3.1   Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     9
ARTICLE IV



          DELIVERIES . . . .    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     9
             Section    4.1   Deliveries to Tech  . . . . . . . . . . . . . . . . . . . . . . . . .     9
             Section    4.2   Deliveries to CommcoCCC . . . . . . . . . . . . . . . . . . . . . . .     9

ARTICLE  V



REPRESENTATIONS OF COMMCOCCC ENTITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     9
             Section    5     Representations with respect to CommcoCCC Entities  . . . . . . . . .     9
             Section    5.1   Corporate Existence . . . . . . . . . . . . . . . . . . . . . . . . .     9
             Section    5.2   Power and Authority . . . . . . . . . . . . . . . . . . . . . . . . .    10
             Section    5.3   Enforceability, etc.  . . . . . . . . . . . . . . . . . . . . . . . .    10
             Section    5.4   Capitalization  . . . . . . . . . . . . . . . . . . . . . . . . . . .    10
             Section    5.5   Subsidiaries and Investments  . . . . . . . . . . . . . . . . . . . .    10
             Section    5.6   Consents, Approvals and Non-Contravention . . . . . . . . . . . . . .    10
             Section    5.7   Balance Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . .    11
             Section    5.8   Material Adverse Change . . . . . . . . . . . . . . . . . . . . . . .    11
             Section    5.9   Absence of Undisclosed Liabilities  . . . . . . . . . . . . . . . . .    11
             Section    5.10  Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    11
             Section    5.11  Litigation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    12
             Section    5.12  38 GHz Authorizations . . . . . . . . . . . . . . . . . . . . . . . .    12
             Section    5.13  Compliance with Laws  . . . . . . . . . . . . . . . . . . . . . . . .    13
             Section    5.14  Investment Company Act  . . . . . . . . . . . . . . . . . . . . . . .    13
             Section    5.15  Brokers, etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . .    13
             Section    5.16  Disclosure  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    14
 

                                                   -i-
<PAGE>

             Section    5.17  Contracts and Commitments . . . . . . . . . . . . . . . . . . . . . .    14
             Section    5.18  Customers and Suppliers . . . . . . . . . . . . . . . . . . . . . . .    14
             Section    5.19  Properties  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    14
             Section    5.20  FCC and Other Governmental Reports  . . . . . . . . . . . . . . . . .    14
             Section    5.21  Accredited Investors  . . . . . . . . . . . . . . . . . . . . . . . .    14
             Section    5.22  Assumptions, Guaranties, Etc. of Indebtedness of Other Persons. . . .    15



ARTICLE VI



          REPRESENTATIONS OF ART COMPANIES  . . . . . . . . . . . . . . . . . . . . . . . . . . . .    15
             Section    6     Representations with respect to the ART Companies . . . . . . . . . .    15
             Section    6.1   Corporate Existence . . . . . . . . . . . . . . . . . . . . . . . . .    15
             Section    6.2   Power and Authority . . . . . . . . . . . . . . . . . . . . . . . . .    16
             Section    6.3   Enforceability, etc.  . . . . . . . . . . . . . . . . . . . . . . . .    16
             Section    6.4   Capitalization  . . . . . . . . . . . . . . . . . . . . . . . . . . .    16
             Section    6.5   Telecom, Subsidiaries and Investments . . . . . . . . . . . . . . . .    17
             Section    6.6   Consents, Approvals and Non-Contravention . . . . . . . . . . . . . .    17
             Section    6.7   SEC Filings; Financial Statements . . . . . . . . . . . . . . . . . .    18
             Section    6.8   Material Adverse Change . . . . . . . . . . . . . . . . . . . . . . .    18
             Section    6.9   Absence of Undisclosed Liabilities  . . . . . . . . . . . . . . . . .    18
             Section    6.10  Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    18
             Section    6.11  Litigation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    19
             Section    6.12  Other Relationships . . . . . . . . . . . . . . . . . . . . . . . . .    19
             Section    6.13  38 GHz Authorizations . . . . . . . . . . . . . . . . . . . . . . . .    19
             Section    6.14  Compliance with Laws  . . . . . . . . . . . . . . . . . . . . . . . .    20
             Section    6.15  Investment Company Act  . . . . . . . . . . . . . . . . . . . . . . .    20
             Section    6.16  Brokers, etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . .    20
             Section    6.17  Contracts and Commitments . . . . . . . . . . . . . . . . . . . . . .    21
             Section    6.18  Properties  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    21
             Section    6.19  Assumptions, Guaranties, Etc. of Indebtedness of Other Persons  . . .    21



ARTICLE VII



          COVENANTS . . . . .   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    22
             Section    7.1   Conduct of Business of CommcoCCC and the ART Companies  . . . . . . .    22
             Section    7.2   Exclusive Dealing . . . . . . . . . . . . . . . . . . . . . . . . . .    22
             Section    7.3   Application for Commission Consent  . . . . . . . . . . . . . . . . .    22
             Section    7.4   Other Governmental Consents . . . . . . . . . . . . . . . . . . . . .    22
             Section    7.5   Third Party Consents  . . . . . . . . . . . . . . . . . . . . . . . .    23
             Section    7.6   Restrictive Agreements Prohibited . . . . . . . . . . . . . . . . . .    23
             Section    7.7   Dividends and Distributions; Acquisition of Capital Stock . . . . . .    23
 

                                                   -ii-
<PAGE>

             Section    7.8   Additional Negative Covenants of CommcoCCC  . . . . . . . . . . . . .    23
             Section    7.9   Corporate Existence . . . . . . . . . . . . . . . . . . . . . . . . .    24
             Section    7.10  Additional Affirmative Covenants  . . . . . . . . . . . . . . . . . .    24
             Section    7.11  Reasonable Best Efforts . . . . . . . . . . . . . . . . . . . . . . .    24
             Section    7.12  Review of Tech and CommcoCCC  . . . . . . . . . . . . . . . . . . . .    24
             Section    7.13  Disclosure to Parties . . . . . . . . . . . . . . . . . . . . . . . .    24
             Section    7.14  CommcoCCC Obligation to Provide Information . . . . . . . . . . . . .    24
             Section    7.15  Financial Reports . . . . . . . . . . . . . . . . . . . . . . . . . .    25
             Section    7.16  Public Announcements  . . . . . . . . . . . . . . . . . . . . . . . .    25
             Section    7.17  Confidentiality . . . . . . . . . . . . . . . . . . . . . . . . . . .    25
             Section    7.18  Distribution of Tech Securities Pursuant to Plan of Reorganization  .    26


             Section    7.19  Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    26
             Section    7.20  Negative Covenants of the ART Companies . . . . . . . . . . . . . . .    26
             Section    7.22  Tax Certificates  . . . . . . . . . . . . . . . . . . . . . . . . . .    28

ARTICLE VIII



          CONDITIONS TO TECH'S OBLIGATIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . .    28
             Section    8     Conditions to Tech's Obligations  . . . . . . . . . . . . . . . . . .    28
             Section    8.1   Truth of Representations and Warranties . . . . . . . . . . . . . . .    28
             Section    8.2   Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    28
             Section    8.3   No Litigation Threatened  . . . . . . . . . . . . . . . . . . . . . .    29
             Section    8.4   Commission Consent  . . . . . . . . . . . . . . . . . . . . . . . . .    29
             Section    8.5   Governmental Approvals; Consents  . . . . . . . . . . . . . . . . . .    29
             Section    8.6   Opinion of CommcoCCC's Counsel  . . . . . . . . . . . . . . . . . . .    29
             Section    8.7   Noncompetition Agreement  . . . . . . . . . . . . . . . . . . . . . .    29
             Section    8.8   CommcoCCC Coverage Pops . . . . . . . . . . . . . . . . . . . . . . .    29
             Section    8.9   NASDAQ Listing. . . . . . . . . . . . . . . . . . . . . . . . . . . .    29
             Section    8.10  Certificate.  . . . . . . . . . . . . . . . . . . . . . . . . . . . .    29

ARTICLE IX



          CONDITIONS TO COMMCOCCC's OBLIGATIONS . . . . . . . . . . . . . . . . . . . . . . . . . .    30
             Section    9     Conditions to the CommcoCCC's Obligations . . . . . . . . . . . . . .    30
             Section    9.1   Truth of Representations and Warranties . . . . . . . . . . . . . . .    30
             Section    9.2   Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    30
             Section    9.3   No Material Adverse Change  . . . . . . . . . . . . . . . . . . . . .    30
             Section    9.4   No Litigation Threatened  . . . . . . . . . . . . . . . . . . . . . .    30
             Section    9.5   Commission Consent  . . . . . . . . . . . . . . . . . . . . . . . . .    30
             Section    9.6   Governmental Approvals; Consents  . . . . . . . . . . . . . . . . . .    30
             Section    9.7   Tax Opinions of CommcoCCC's Counsel . . . . . . . . . . . . . . . . .    31
             Section    9.8   Other Opinions of Tech's Counsel  . . . . . . . . . . . . . . . . . .    31
 

                                                  -iii-
<PAGE>

             Section    9.9   Equity and Debt Offerings . . . . . . . . . . . . . . . . . . . . . .    31
             Section    9.10  ART Coverage Pops . . . . . . . . . . . . . . . . . . . . . . . . . .    31
             Section    9.11  CLC Option Agreement  . . . . . . . . . . . . . . . . . . . . . . . .    31

             Section    9.12  Tech Board Representation . . . . . . . . . . . . . . . . . . . . . .    31
             Section    9.13  NASDAQ Listing. . . . . . . . . . . . . . . . . . . . . . . . . . . .    31
             Section    9.14  Certificate.  . . . . . . . . . . . . . . . . . . . . . . . . . . . .    31

ARTICLE X



          INDEMNIFICATION . .   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    31
             Section    10.1  Indemnification by the CommcoCCC Entities . . . . . . . . . . . . . .    31
             Section    10.2  Threshold for Indemnification . . . . . . . . . . . . . . . . . . . .    33
             Section    10.3  Indemnification by the ART Companies. . . . . . . . . . . . . . . . .    34
             Section    10.4  Third Party Claims  . . . . . . . . . . . . . . . . . . . . . . . . .    35
             Section    10.5  Notice of Direct Claims . . . . . . . . . . . . . . . . . . . . . . .    35
ARTICLE XI



          NO SURVIVAL OF REPRESENTATIONS AND WARRANTIES . . . . . . . . . . . . . . . . . . . . . .    36
             Section    11    No Survival of Representations and Warranties . . . . . . . . . . . .    36

ARTICLE XII



          OFFER, SALE AND RESALE OF TECH SECURITIES . . . . . . . . . . . . . . . . . . . . . . . .    36
             Section    12.1  Limitations on Disposition  . . . . . . . . . . . . . . . . . . . . .    36
             Section    12.2  Legends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    36
ARTICLE XIII



          MISCELLANEOUS         . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    37
             Section    13.1  Expenses  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    37
             Section    13.2  Governing Law . . . . . . . . . . . . . . . . . . . . . . . . . . . .    37
             Section    13.3  Captions  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    37
             Section    13.4  Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    37


             Section    13.5  Parties in Interest . . . . . . . . . . . . . . . . . . . . . . . . .    39
             Section    13.6  Counterparts  . . . . . . . . . . . . . . . . . . . . . . . . . . . .    39
             Section    13.7  Entire Agreement  . . . . . . . . . . . . . . . . . . . . . . . . . .    39
             Section    13.8  Amendments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    39
             Section    13.9  Third Party Beneficiaries . . . . . . . . . . . . . . . . . . . . . .    39
             Section    13.10 Termination and Abandonment . . . . . . . . . . . . . . . . . . . . .    39

</TABLE>

                                                   -iv-
<PAGE>

                                                 EXHIBITS

     Exhibit A                Bridge Notes
     Exhibit B                CLC Option Agreement
     Exhibit C                CLC Right of First Offer Agreement
     Exhibit D                Columbia Right of First Offer Agreement
     Exhibit E                Coverage Pops
     Exhibit F                Management Agreement
     Exhibit G                Noncompetition Agreement
     Exhibit H                Registration Rights Agreement
     Exhibit I                Security Agreement
     Exhibit J                Warrants
     Exhibit K                Tax Opinion of CommcoCCC's Counsel

                                                SCHEDULES

     Schedule 5.4             Capitalization
     Schedule 5.6             Consents, Approvals and Non-Continuation
     Schedule 5.7             Balance Sheet
     Schedule 5.8             Material Adverse Change
     Schedule 5.9             Absence of Undisclosed Liabilities
     Schedule 5.10            Taxes
     Schedule 5.11            Litigation
     Schedule 5.12            38 GHz Authorization
     Schedule 5.15            Brokers
     Schedule 5.17            Contracts and Commitments
     Schedule 6.6             Consents, Approvals and Non-Contravention
     Schedule 6.8             Material Adverse Change
     Schedule 6.10            Taxes
     Schedule 6.13            38 GHz Authorizations
     Schedule 6.16            Brokers
     Schedule 6.17            Contracts and Commitments

                                                    -v-
<PAGE>
 
             ASSET ACQUISITION AGREEMENT AND PLAN OF REORGANIZATION



     THIS ASSET ACQUISITION AGREEMENT AND PLAN OF REORGANIZATION (the
"AGREEMENT"), dated as of July 3, 1996, by and among COMMCOCCC, INC., a Delaware
corporation ("COMMCOCCC"), CCC MILLIMETER, L.P., a Delaware limited partnership
("CCC"), COLUMBIA MILLIMETER COMMUNICATIONS, L.P., a Delaware limited
partnership ("CMC"), COMMCO, L.L.C.,  a Delaware limited liability company
("CLC"), COLUMBIA CAPITAL CORPORATION, a Virginia corporation ("COLUMBIA"),
ADVANCED RADIO TECHNOLOGIES CORPORATION, a Delaware corporation ("TECH"), and
ADVANCED RADIO TELECOM CORP., a Delaware corporation ("TELECOM") (Tech and
Telecom are sometimes collectively hereinafter referred to as the "ART
COMPANIES").

                                    RECITALS:

     1.   CommcoCCC owns, or has the right to acquire and at the closing will
own, 38 GHz Authorizations covering approximately 90,000,000 Coverage Pops, and
intends to transfer these 38 GHz Authorizations and its other assets to Tech on
the terms and conditions and for the consideration described in this Agreement.

     2.   Tech and Telecom, either directly or through joint ventures or
partnerships which they control, own, or have the right to acquire and at the
Closing will own or lease, 38 GHz Authorizations covering approximately
93,000,000 Coverage Pops, and Tech intends to acquire the CommcoCCC Assets on
the terms and conditions and for the consideration described in this Agreement.

     3.   CommcoCCC, Tech and Telecom desire to combine their ownership of 38
GHz Authorizations and construct and operate 38 GHz telecommunication networks
as a single Business.

     4.   In order to combine their Businesses, CommcoCCC, Tech and Telecom
intend to consummate the following series of transactions (the "TRANSACTIONS"):

          a.   The ART Reorganization;

          b.   The issuance by Tech of Tech Common Stock to the public in the
               Equity Offering;

          c.   The issuance to the public by Tech of units consisting of its
               senior discount notes and warrants to purchase Tech Common Stock
               in the Debt Offering; and
 


                                       -1-

<PAGE>

          d.   The Acquisition.

The ART Reorganization is a condition to the closing of the Equity Offering and
the Debt Offering, which in turn are conditions to the Asset Acquisition.  The
FCC Consent is a condition to the Asset Acquisition.

     5.   It is intended that the ART Reorganization qualify as a reorganization
described in Section   368(a)(1)(B) of the Code, that the Asset Acquisition
qualify as a reorganization described in Section   368(a)(1)(C) of the Code, and
that the ART Reorganization, the Equity Offering and the Asset Acquisition
together qualify as transfer to a controlled corporation, Tech, under Section
351 of the Code, with the result that neither the shareholders of CommcoCCC nor
Telecom shall recognize income or gain under the Code as a result of combining
the Businesses of Tech, Telecom and CommcoCCC into a single Business.

     6.   The purpose of this Agreement is to set forth the terms and conditions
of the Asset Acquisition and to constitute an agreement and plan of
reorganization with respect to the foregoing transactions.

     NOW, THEREFORE, in consideration of the mutual promises and covenants
hereinafter set forth, and for other good and valuable consideration, the
sufficiency of which is hereby acknowledged, the parties hereby agree as
follows:


                                    ARTICLE I

                                   DEFINITIONS

     "ACQUISITION" means the acquisition of the CommcoCCC Assets in exchange for
the Tech Securities pursuant to this Agreement.

     "AFFILIATES" means as to any Person, any other Person that, directly or
indirectly, alone or through others, controls, is controlled by or is under
common control with such Person.  For purposes of this definition "controls"
(including with correlative meanings, the terms "controlled by" and "under
common control with" as applied to any Person) means the possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of that Person, whether through the ownership of voting securities or
by contract or otherwise.

     "AGREEMENT" means this Asset Acquisition Agreement and Plan of
Reorganization.

     "ART COMPANIES" mean Tech and Telecom.

     "ART FINANCIAL STATEMENTS" means the financial statements contained in the
ART Registration Statements.
 


                                       -2-

<PAGE>

     "ART REGISTRATION STATEMENTS" mean the Equity Registration Statement and
the Debt Registration Statement.

     "ART REORGANIZATION" means the transaction pursuant to which a wholly-owned
subsidiary of Tech shall be merged with and into Telecom with Telecom's existing
shareholders (other than Tech) receiving shares of Tech Common Stock as
disclosed in the Preliminary ART Registration Statements.

     "ART WEST" means ART West Joint Venture, a general partnership governed by
Delaware law, between Tech and Extended Communications, Inc.

     "ASSIGNMENT APPLICATION" means the application or applications requesting
the Commission's written consent to the assignment of the 38 GHz Authorizations
listed on SCHEDULE 5.12 from Columbia, CMC and CLC, respectively, to CommcoCCC
and the subsequent assignment of such 38 GHz Authorizations by CommcoCCC to
Tech.

     "BRIDGE NOTES" means the Bridge Notes due September 30, 1996 issued by Tech
to each of Columbia and CLC, substantially in the form attached hereto as
EXHIBIT A.

     "BUSINESS" means the provision of wireless broadband telecommunications
services using point-to-point microwave transmissions in the 37.0 to 40.0
gigahertz portion of the radio spectrum.

     "CCC" means CCC Millimeter, L.P., a Delaware limited partnership.

     "CLC" means Commco, L.L.C., a Delaware limited liability company.

     "CMC" means Columbia Millimeter Communications, L.P., a Delaware limited
partnership.

     "CLC OPTION AGREEMENT" means the Option Agreement dated as of the date
hereof among Tech, Telecom and CLC attached hereto as EXHIBIT B.

     "CLOSING" means the consummation of the transactions as provided in
Articles II and IV hereof.

     "CLOSING DATE" means the date on which the Closing takes place.

     "CODE" means the Internal Revenue Code of 1986, as amended.

     "COLUMBIA" means Columbia Capital Corporation, a Virginia corporation.
 



                                       -3-

<PAGE>


     "COLUMBIA RIGHT OF FIRST OFFER AGREEMENT" means the Right of First Offer
Agreement dated as of the date hereof among Columbia, CMC and Tech attached
hereto as EXHIBIT D.

     "COMMCOCCC" means CommcoCCC, Inc., a Delaware corporation.

     "COMMCOCCC ASSETS" means all assets of CommcoCCC tangible and intangible,
real, personal or mixed and wherever located, including but not limited to all
of  the 38 GHz Authorizations in the name of CommcoCCC or any of the CommcoCCC
Entities' identified on SCHEDULE 5.12, all Real Estate of CommcoCCC and all cash
and cash equivalents, excluding all agreements, contracts, commitments and
understandings.

     "COMMCOCCC BALANCE SHEET" means the unaudited balance sheet of CommcoCCC as
of June 7, 1996.

     "COMMCOCCC COMMON STOCK" means common stock, par value $.01 per share, of
CommcoCCC.

     "COMMCOCCC ENTITIES" shall mean collectively CommcoCCC, CCC, CMC, CLC and
Columbia.

     "COMMISSION" or "FCC" means the Federal Communications Commission.

     "COMMUNICATIONS ACT" means the Communications Act of 1934, as amended.

     "COVERAGE POPS" means (i) 100% of the human beings resident within the
coverage areas of all 38 GHz Authorizations owned by the referenced Person, plus
(ii) 60% of the human beings resident within the coverage areas of all 38 GHz
Authorizations which are managed or leased by such Person under agreements
giving exclusive rights to such Person (together with the licensees) to utilize
such 38 Ghz Authorizations for at least a five year term and entitling such
Person at least 80% of the gross revenue or a substantially equivalent financial
arrangement with respect to such leased or managed Authorizations, plus (iii)
80% of the human beings within the coverage areas of all 38 GHz Authorizations
owned by Art West, with the number of human beings determined in each case based
upon the methodology set forth on EXHIBIT E hereto, and in the case of 38 GHz
Authorizations with overlapping coverage areas duplicate coverage of the same
human beings shall be ignored.

     "DGCL" means the Delaware General Corporation Law.

     "DCT" means DCT Communications, Inc., a California corporation.

     "DEBT REGISTRATION STATEMENT" means the Registration Statement on Form S-1
(No. 333-03735) of Tech filed with the SEC, as amended, with respect to the
Senior Discount Notes due 2006 and Warrants to purchase Tech Common Stock.
 



                                       -4-

<PAGE>

     "DEBT OFFERING" means the issuance and sale of the Senior Discount Notes
due 2006 and Warrants to purchase Tech Common Stock as contemplated by the Debt
Registration Statement.

     "DEBT PROSPECTUS" means the prospectus of Tech which is part of the Debt
Registration Statement.

     "EMPLOYEE BENEFIT PLANS" means all employee benefit plans within the
meaning of Section   3(3) of ERISA whether or not any such Employee Benefit
Plans are otherwise exempt from the provisions of ERISA.

     "EQUITY REGISTRATION STATEMENT" means the Registration Statement of Tech on
Form S-1 (No. 333-4388) filed with the SEC, as amended, with respect to the
initial public offering of Tech Common Stock.

     "EQUITY OFFERING" means the initial public offering of Tech Common Stock as
contemplated by the Equity Registration Statement.

     "EQUITY PROSPECTUS" means the prospectus of Tech which is part of the
Equity Registration Statement, as supplemented.

     "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended.

     "FCC CONSENT" means the Commission's grant of consent to the Assignment
Application.

     "FCC RULES" means the rules, regulations and policies of the Commission.

     "FINAL AMENDMENT DATE" means the date on which the ART Companies file the
last pre-effective amendment to the ART Registration Statements.

     "FINAL ORDER" means an action by the FCC, state regulatory authority or a
court of competent jurisdiction as to which (i) no request for stay by the FCC,
state regulatory authority or a court of competent jurisdiction, as applicable,
is pending, no such stay is in effect, and, if any deadline for filing any such
request is designated by statute or regulation, such deadline has passed; (ii)
no petition for rehearing or reconsideration or application for review of the
action is pending before the FCC, state regulatory authority or court of
competent jurisdiction, as applicable, and the time for filing any such petition
has passed; (iii) the FCC, state regulatory authority or court of competent
jurisdiction, as applicable, does not have the action under reconsideration on
its own motion and the time for such reconsideration has passed; and (iv) no
appeal to a court of competent jurisdiction, or request for stay by a court of
competent jurisdiction, of the FCC's, the state regulatory authority's or the
court's action, as applicable, is pending or in effect and, if any deadline for
filing any such appeal or request is designated by statute or rule, such
deadline has passed.
 



                                       -5-

<PAGE>

     "GAAP" means generally accepted accounting principles in the United States
of America, consistently applied throughout the indicated periods.

     "HSR ACT" means the Hart-Scott-Rodino Antitrust Improvements Act of 1976,
as amended.

     "INTEREST" means any equity ownership of any kind of any Person, including
without limitation, equity ownership represented by common stock, preferred
stock, securities convertible into or exercisable for the purchase or other
acquisition of common stock (including convertible debentures, warrants and
options), trust certificates, general or limited partnership interests or
limited liability company member interests.

     "INVESTMENT"  means any purchase or other acquisition of (i) any Interest
in any Person, (ii) any radio frequency spectrum, (iii) any capital contribution
to such Person or (iv) any other investment in such Person.

     "LIENS" means liens, claims, charges and other encumbrances.

     "LOAN DOCUMENTS" means the Bridge Notes, the Security Agreement and the
Warrants.

     "MANAGEMENT AGREEMENT" means the Management Agreement dated as of the date
hereof among Tech and the CommcoCCC Entities attached hereto as EXHIBIT F.

     "MATERIAL ADVERSE CHANGE" with respect to any Person means a material
adverse change in the financial condition, business, assets, results of
operations or prospects of such Person, other than as a result of adverse
changes to the wireless telecommunications industry in general.

     "MATERIAL ADVERSE EFFECT" with respect to any Person means a material
adverse effect on the financial condition, business, assets, results of
operations or prospects of such Person, other than as a result of adverse
changes to the wireless telecommunications industry in general.

     "NONCOMPETITION AGREEMENT" means the Noncompetition Agreement dated as of
the Closing Date among CCC, CMC, Columbia and Tech, relating to the limitations
on CCC, CMC and Columbia from engaging in the Business, substantially in the
form attached hereto as EXHIBIT G.

     "NPRM" shall mean the notice of proposed rulemaking issued by the FCC on
December 15, 1995, 61 FR 2465, Proposed Rules, Federal Communications Commission
(FCC), 47 CFR Parts 1, 2, 21 and 94 [FCC 95-500], Fixed Point-to-Point Microwave
Service, Friday, January 26, 1996, Action:  Proposed Rule, Federal Register Vol.
61 No. 18.

     "PENDING APPLICATION" means an application that was filed with the FCC
prior to November 13, 1995, to obtain a 38 GHz Authorization, which as of the
date hereof has not been
 



                                       -6-

<PAGE>


granted or dismissed by the FCC, and which was placed on public notice by the
FCC and held in abeyance pursuant to the NPRM.

     "PERMITS" means all licenses, permits, orders, consents, approvals,
registrations, authorizations, qualifications and filings under all federal,
state, local or foreign laws with governmental or regulatory bodies, except for
the 38 GHz Authorizations and the Pending Applications.

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

     "POPS" mean the aggregate number of human beings resident within a
particular geographic area determined based upon methodology set forth on
EXHIBIT E hereto.

     "PRELIMINARY ART REGISTRATION STATEMENTS" means Amendment No. 1 to the
Equity Registration Statement and Amendment No. 1 to the Debt Registration
Statement as filed with the SEC on July 3, 1996 and July 3, 1996, respectively.

     "REAL ESTATE" means real property, including roof tops, and improvements,
whether owned or leased.

     "REGISTRATION RIGHTS AGREEMENT" means the Second Restated and Amended
Registration Rights Agreement dated the date hereof among the ART Companies and
certain of their stockholders named therein attached hereto as EXHIBIT H.

     "SEC" means the Securities and Exchange Commission.

     "SECURITY AGREEMENT" means the Security Agreement dated as of the date
hereof between Tech, as debtor, and Columbia, as collateral agent for the
benefit of Columbia and CLC under the Bridge Notes, pursuant to which the debtor
will grant security interests in the assets of Tech to secure the repayment of
the Bridge Notes, substantially in the form attached hereto as EXHIBIT I.

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

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

     "SUBSIDIARY" of any Person means any corporation or other entity of which
securities or other ownership interests having ordinary voting power to elect a
majority of the Board of Directors or other Persons performing similar functions
are at the time directly or indirectly owned or controlled by such Person or one
or more Subsidiaries of such Person.

     "TECH" means Advanced Radio Technologies Corporation, a Delaware
corporation.
 



                                       -7-

<PAGE>


     "TECH COMMON STOCK" means common stock, par value $.001 per share, of Tech.

     "TECH SECURITIES" means 16,500,000 shares of Tech Common Stock (after
giving effect to the ART Reorganization and related stock split) issued in
exchange for the CommcoCCC Assets pursuant to Article II of this Agreement,
adjusted to reflect the effect of any other subsequent stock split, reverse
split, stock dividend, reorganization, recapitalization or other like change
with respect to the Tech Common Stock.

     "TELECOM" means Advanced Radio Telecom Corp., a Delaware corporation.

     "TELECOM ONE" means Telecom One, Inc.

     "TELECOM WARRANTS" means Warrants outstanding as of the date hereof to
purchase in the aggregate 2,302,136 shares of Common Stock of Telecom.

     "TRANSACTION DOCUMENTS" means the agreements and instruments to be executed
and delivered in connection herewith.

     "38 GHZ AUTHORIZATIONS" means construction permits and licenses granted by
the FCC for the construction and operation of millimetric microwave
telecommunications systems on specific 100 MHz channels between 37.0 GHz and
40.0 GHz on the radio frequency spectrum within specified geographic footprints.

     "WARRANTS" mean the Common Stock Purchase Warrants to purchase an aggregate
of 50,000 shares of Tech Common Stock (after giving effect to the ART
Reorganizations and related stock split), substantially in the form attached
hereto as EXHIBIT J.

                                   ARTICLE II

                            TRANSFER AND ACQUISITION

     Section  2.1   TRANSFER AND ACQUISITION.  Subject to the terms and
conditions hereof, CommcoCCC hereby agrees to transfer, and Tech hereby agrees
to acquire all of the CommcoCCC Assets.  Tech will issue the Tech Securities in
exchange for all of the CommcoCCC Assets, free and clear of all Liens and the
other agreements of the CommcoCCC Entities hereunder.

     Section  2.2   NO ASSUMPTION OF LIABILITIES.  Tech shall not assume any
obligations, debts, liabilities or commitments of any nature whatsoever, whether
matured or unmatured or whether fixed or contingent.  CommcoCCC agrees that it
shall retain and remain unconditionally liable for all of its obligations,
debts, liabilities and commitments.
 



                                       -8-

<PAGE>


                                   ARTICLE III

                                     CLOSING

     Section  3.1   CLOSING.  Subject to the provisions of Articles VIII and IX,
the closing of the  transactions contemplated by this Agreement shall take place
on such date and at such time as the parties shall mutually agree at the offices
of Nelson Mullins Riley & Scarborough, L.L.P., NationsBank Corporate Center,
Suite 3350, 100 North Tryon Street, Charlotte, NC 28202 no later than thirty
(30) business days after the satisfaction or waiver of the conditions precedent
described in Articles VIII and IX or at such other time and place as the parties
shall agree.

                                   ARTICLE IV

                                   DELIVERIES

     Section  4.1   DELIVERIES TO TECH.  At the Closing, the CommcoCCC Entities
shall deliver to Tech:  (i) a bill of sale conveying the CommcoCCC Assets, (ii)
the documents required to be delivered by CommcoCCC pursuant to Article VIII
hereof, and (iii) such other documents and instruments as Tech may reasonably
request.

     Section  4.2   DELIVERIES TO COMMCOCCC.  At the Closing, Tech shall deliver
to CommcoCCC:  (i) certificates representing the Tech Securities issued in such
names and amounts as CommcoCCC may direct, (ii) the documents required to be
delivered by Tech pursuant to Article IX hereof, and (iii) such other documents
and instruments as CommcoCCC may reasonably request.

                                   ARTICLE  V

                      REPRESENTATIONS OF COMMCOCCC ENTITIES

     Section  5     REPRESENTATIONS WITH RESPECT TO COMMCOCCC ENTITIES.  Each of
the CommcoCCC Entities represents and warrants, jointly and severally, as
follows:

     Section  5.1   CORPORATE EXISTENCE.  Each of the CommcoCCC Entities, if a
corporation, has been duly incorporated, and, if not a corporation, has been
duly organized, is validly existing and in good standing under the laws of its
jurisdiction of organization and is duly qualified to do business as a foreign
corporation and is in good standing in each jurisdiction in which the ownership
or use of its assets or properties, or the conduct or nature of its business,
makes such qualification necessary (except for jurisdictions in which the
failure to so qualify or be in good standing would not be reasonably likely to
have a Material Adverse Effect).  Each of the CommcoCCC Entities has all
requisite corporate power and authority to conduct its business and own its
properties as now conducted and owned.  The CommcoCCC Entities have provided
Tech
 



                                       -9-

<PAGE>


with true and correct copies of each of the CommcoCCC Entities' organizational
documents as in effect on the date hereof and its by-laws as in effect on the
date hereof.

     Section  5.2   POWER AND AUTHORITY.  Each of the Commco Entities has all
requisite corporate power and authority, and as of the Closing Date will have
taken all required corporate and other action necessary, to execute, deliver and
perform this Agreement and consummate the transactions contemplated hereby.

     Section  5.3   ENFORCEABILITY, ETC.  This Agreement and all Transaction
Documents to be executed and delivered in connection herewith by any of the
CommcoCCC Entities have been, or will be as of the Closing Date, duly executed
and delivered by the applicable CommcoCCC Entity and, assuming that this
Agreement and the Transaction Documents, as applicable, are or will be as of the
Closing Date, duly executed and delivered by, and are within the power and
authority of each of the other parties thereto, constitute, or will constitute,
the legal, valid and binding obligation of each of the CommcoCCC Entities, as
applicable, enforceable against it in accordance with their respective terms,
except as the enforceability thereof may be limited by bankruptcy, insolvency,
moratorium, reorganization or other similar laws affecting creditors' rights
generally and subject to general principles of equity (regardless of whether
considered in a proceeding in equity or at law).

     Section  5.4   CAPITALIZATION.  Set forth on SCHEDULE 5.4 hereof (the
"COMMCOCCC CAPITALIZATION SCHEDULE") is a true and complete statement of the
capitalization of CommcoCCC, including a list of all holders of Interests of or
in CommcoCCC (and the amount and type of such Interests).  Except as set forth
on the CommcoCCC Capitalization Schedule, CommcoCCC has not issued any Interests
in CommcoCCC, nor are any Interests in CommcoCCC (or any rights to acquire or
purchase any Interests in CommcoCCC) outstanding.  The CommcoCCC Capitalization
Schedule also sets forth a true and complete description, in reasonable detail,
of all indebtedness owing to CommcoCCC.

     Section  5.5   SUBSIDIARIES AND INVESTMENTS.  CommcoCCC does not own,
directly or indirectly, of record or beneficially, any capital stock or other
Interest in any Person.

     Section  5.6   CONSENTS, APPROVALS AND NON-CONTRAVENTION.  Except for the
FCC Consent, any consents required under the HSR Act and as set forth on
SCHEDULE 5.6 hereof, neither the execution, delivery and performance of this
Agreement by any of the CommcoCCC Entities, nor the consummation of any
transaction contemplated hereunder, will:

                    (a)  require any consent or approval of, filing or taking of
                         any other action with, or notice to, any Person;

                    (b)  result in a breach or constitute a default under any
                         contract, agreement, instrument or other arrangement to
                         which any of the
 



                                      -10-

<PAGE>


                         CommcoCCC Entities is a party or by which any of them
                         or any of the CommcoCCC Assets is bound;

                    (c)  result in the creation of any Lien on any of the
                         CommcoCCC Assets;

                    (d)  violate (i) any order, writ, judgment, injunction or
                         decree or (ii) any statute, law, rule or regulation of
                         any court, tribunal or governmental entity or
                         authority, applicable to or bearing upon CommcoCCC or
                         any of its assets or business; or

                    (e)  violate any of the CommcoCCC 38 GHz Authorizations;

except as to (a), (b) and (d) above, as would not have a Material Adverse Effect
on CommcoCCC  Assets.

     Section  5.7   BALANCE SHEET.  Set forth on SCHEDULE 5.7 hereof is a true,
correct and complete copy of the CommcoCCC Balance Sheet.  The CommcoCCC Balance
Sheet has been prepared in accordance with GAAP applied on a consistent basis
(except that the CommcoCCC Balance Sheet does not contain any notes thereto) and
presents fairly the financial position of CommcoCCC at the date thereof.

     Section  5.8   MATERIAL ADVERSE CHANGE.  Except as set forth on SCHEDULE
5.8 hereof, since June 7, 1996, there has been no Material Adverse Change with
respect to the CommcoCCC Assets, taken as a whole.

     Section  5.9   ABSENCE OF UNDISCLOSED LIABILITIES.  Since the date of the
CommcoCCC Balance Sheet, CommcoCCC had no material liabilities (matured or
unmatured, fixed or contingent), which are not fully reflected or provided for
on the CommcoCCC Balance Sheet, or any material loss contingency (as defined in
Statement of Financial Accounting Standards No. 5) whether or not required by
GAAP to be shown on the CommcoCCC Balance Sheet, except (i) obligations to
perform under commitments incurred in the ordinary course of business, (ii) tax
and related liabilities which have been disclosed pursuant to Section   5.10
below and (iii) other liabilities as set forth on SCHEDULE 5.9 hereof.

     Section  5.10  TAXES.  Except as set forth on SCHEDULE 5.10 hereof, 
CommcoCCC has accurately completed and filed or will file within the time 
prescribed by law (including extensions of time approved by the appropriate 
taxing authority) all tax returns and reports required to be filed with the 
Internal Revenue Service, the Commonwealth of Virginia, any other states or 
governmental subdivisions and all foreign countries except where the failure 
to file would not have a Material Adverse Effect; has paid all taxes, 
interest, penalties, assessments or deficiencies shown to be due (or, to the 
knowledge of CommcoCCC, claimed by such authority or jurisdiction to be due) 
on or in respect of such tax returns and reports; and has established 
reserves, to the knowledge of

                                      -11-

<PAGE>


the CommcoCCC Entities, adequate for all taxes accrued but not yet payable.
CommcoCCC knows of (i) no other federal, state, county, municipal or foreign
taxes (or other liabilities in respect thereof) which are due and payable by
CommcoCCC which have not been so paid, (ii) no other federal, Delaware, state,
county, municipal or foreign tax returns or reports which are required to be
filed which have not been so filed, (iii) no other unpaid assessment for, or any
fact which would constitute grounds for the assessment of, additional taxes or
penalties for any fiscal period or any basis, thereof and (iv) no material tax
lien, whether imposed by any federal, state, county, municipal or foreign taxing
authority, outstanding against the assets or business of CommcoCCC.  Neither the
federal nor state income tax returns of CommcoCCC have been audited.

     Section  5.11  LITIGATION.  As of the date hereof, except as set forth on
SCHEDULE 5.11, there are no actions, suits, proceedings, orders, investigations
or claims pending or, to the best of CommcoCCC Entities' knowledge, threatened
against or affecting any of the CommcoCCC Entities, the CommcoCCC Assets or any
other of its assets, its business or any of its directors or employees, at law
or in equity, before any court, arbitration panel, tribunal or governmental
department, commission, board, bureau, agency or instrumentality (i) which could
have a Material Adverse Effect on the CommcoCCC Assets or (ii) in connection
with the Acquisition hereby.  None of the CommcoCCC Entities is in default with
respect to any judgment, order, writ, injunction or decree of any court or
governmental agency, except where such default will not have a Material Adverse
Effect on CommcoCCC before the Closing Date or on Tech after the Closing Date,
and there are no unsatisfied judgments against any of the CommcoCCC Entities
other than any as to which the time for payment has not elapsed, including by
reason of any appeal.

     Section  5.12  38 GHZ AUTHORIZATIONS.  Set forth on SCHEDULE 5.12 hereof
are all 38 GHz Authorizations owned by CommcoCCC or that CommcoCCC has rights to
acquire and manage exclusively as of the date hereof, including the city and
population covered by the geographic footprint of each 38 GHz Authorization (the
"COMMCOCCC 38 GHZ AUTHORIZATIONS").  The statements made to the FCC in the
applications for the CommcoCCC 38 GHz Authorizations were true and correct at
the time made and at the time the FCC issued the relevant CommcoCCC 38 GHz
Authorizations.  The CommcoCCC 38 GHz Authorizations were duly issued by the
FCC, are in full force and effect, and contain all the conditions placed upon
the entire authorization for each market, except as are found in the FCC Rules.
The CommcoCCC 38 GHz Authorizations permit Columbia, CMC, CLC or CommcoCCC to
operate within the service area and on the channels specified.  Columbia, CMC or
CLC has good and marketable title to the CommcoCCC 38 GHz Authorizations
(subject to FCC Rules on transfers of ownership) free and clear of any Liens,
management or service agreements, whether oral or written, other than the rights
of CommcoCCC under the stock purchase agreement and related assignment
agreements and construction and management agreements entered into by Columbia,
CMC, CLC and CommcoCCC on June 7, 1996, in connection with the initial
capitalization of CommcoCCC.  Columbia, CMC, CLC and CommcoCCC will, have fully
complied with the terms of the CommcoCCC 38 GHz Authorizations, representations
made to the FCC and the FCC Rules, except to the extent such failure to comply
with the foregoing would not be likely to have a
 



                                      -12-

<PAGE>


Material Adverse Effect on any of the CommcoCCC 38 GHz Authorizations.  There
are no pending petitions for reconsideration or judicial review of the grants of
the CommcoCCC 38 GHz Authorizations and the grants of the CommcoCCC 38 GHz
Authorizations have become Final Orders, no longer subject to reconsideration by
the FCC on its own motion or to judicial review.  None of the CommcoCCC Entities
has been notified of any unresolved protest to the grants of the CommcoCCC 38
GHz Authorizations or objections by the FCC or has any reason to believe that
the grants of the CommcoCCC 38 GHz Authorizations will be rescinded or, except
for the NPRM, in any way modified.  Except for filings, if any, required
pursuant to Section   21.711 of the FCC Rules, each of Columbia, CMC, CLC or
CommcoCCC has timely made all filings, reports, paid any fees, and otherwise met
all FCC applicable requirements concerning the CommcoCCC 38 GHz Authorizations,
except to the extent such failure to comply with the foregoing would be likely
to have a Material Adverse Effect on any of the CommcoCCC 38 GHz Authorizations.
None of the CommcoCCC Entities has taken any action or failed to take any action
and there are no formal or other proceedings pending against any of them with
respect to any of the CommcoCCC 38 GHz Authorizations that could reasonably be
expected to lead to the revocation, cancellation, forfeiture or failure to renew
any license issued to Columbia, CMC, CLC or CommcoCCC.  There are no outstanding
notices of apparent liability against Columbia, CMC, CLC or CommcoCCC.  None of
the CommcoCCC Entities knows of any facts relating to it or its Affiliates that
could reasonably be expected to cause the FCC to deny its approval of the
Assignment Application or revoke or restrict any of the CommcoCCC 38 GHz
Authorizations or deny its approval of or place restrictions on the consummation
of the Acquisition, and should any such facts come to the attention of any of
the CommcoCCC Entities, its officers or directors, they will promptly notify the
ART Companies and take all reasonable measures to remove any such impediments to
consent.  Each of the CommcoCCC Entities is fully qualified to be an FCC
licensee and does not violate FCC requirements pertaining to the CommcoCCC 38
GHz Authorizations, including without limitation, rules restricting alien
ownership of FCC licenses.

     Section  5.13  COMPLIANCE WITH LAWS.  The CommcoCCC Entities and the
conduct of their respective businesses is in compliance with all applicable
laws, statutes, ordinances, rules, regulations and orders of any federal,
foreign, state or local government and any other governmental department or
agency, and any judgment, decision, decree or order of any court or governmental
agency, department or authority except where the failure to comply would not
have a Material Adverse Effect on the CommcoCCC Assets.

     Section  5.14  INVESTMENT COMPANY ACT.  CommcoCCC is not an "investment
company" or a company "controlled" by an "investment company" within the meaning
of the Investment Company Act of 1940, as amended.

     Section  5.15  BROKERS, ETC.  Except as set forth on SCHEDULE 5.15 hereof,
none of the CommcoCCC Entities is obligated to pay any fee or commission in
connection with, any broker, finder or other similar Person in connection with
any of the transactions contemplated by this Agreement.
 



                                      -13-

<PAGE>


     Section  5.16  DISCLOSURE.  This Agreement and the exhibits, schedules,
attachments, written statements, documents, certificates and other items
delivered in connection with this Agreement do not contain any untrue statement
of a material fact or omit to state a material fact necessary in order to make
the statements contained herein or therein, in light of the circumstances under
which they were made, not misleading.  There is no fact which CommcoCCC has not
disclosed to the ART Companies in writing and of which any of its officers,
directors or executive employees is aware (other than general economic
conditions and the NPRM) and which has had or would reasonably be expected to
have a Material Adverse Effect upon the existing or expected financial
condition, operating results, assets, customer or supplier relations, employee
relations or business prospects of CommcoCCC.

     Section  5.17  CONTRACTS AND COMMITMENTS.  Except as expressly contemplated
by this Agreement or set forth on SCHEDULE 5.17 hereof, CommcoCCC is not a party
to, or otherwise bound by, any material written or oral contract or instrument
or other restriction or any other written or oral contract or instrument or
other restriction affecting the CommcoCCC Assets.

     Section  5.18  CUSTOMERS AND SUPPLIERS.  As of the date hereof, there are
no customers or suppliers of CommcoCCC.

     Section  5.19  PROPERTIES.  CommcoCCC has good and marketable title to,
free and clear of any liens, claims, pledges, mortgages, charges, options or
other encumbrances, and the right to possession of, all of the CommcoCCC Assets.

     Section  5.20  FCC AND OTHER GOVERNMENTAL REPORTS.  All reports required to
be filed with the FCC by CommcoCCC, Columbia, CMC or CLC with respect to the
business of CommcoCCC have been timely filed and are accurate and complete in
all material respects.  All material reports required to be filed with all other
governmental or administrative authorities, federal, state and local, by
CommcoCCC with respect to the business of CommcoCCC have been timely filed and
are accurate and complete in all material respects.

     Section  5.21  ACCREDITED INVESTORS.

                    (a)  Each of the CommcoCCC Entities is an "accredited
                         investor" within the meaning of Rule 501 under the
                         Securities Act and was not organized for the specific
                         purpose of acquiring the Tech Securities;

                    (b)  each of the CommcoCCC Entities has sufficient knowledge
                         and experience in investing in companies similar to
                         Tech in terms of Tech's stage of development so as to
                         be able to evaluate the risks and merits of its
                         investment in Tech and it is able financially to bear
                         the risks thereof;
 



                                      -14-

<PAGE>


                    (c)  each of the CommcoCCC Entities has had an opportunity
                         to discuss the business, management and financial
                         affairs of Tech with Tech's management and has received
                         (or had made available to it) any financial and
                         business documents requested by it;

                    (d)  the Tech Securities being acquired by each of the
                         CommcoCCC Entities are being acquired for its own
                         account and not with a view to or for sale in
                         connection with any unregistered distribution thereof
                         in violation of the Securities Act or any state
                         securities act;

                    (e)  each of the CommcoCCC Entities understands that (i) the
                         Tech Securities must be held indefinitely unless a
                         subsequent disposition thereof is registered under the
                         Securities Act or is exempt from such registration,
                         (ii) Tech will make a notation on its transfer books to
                         such effect and (iii) the Tech Securities will bear a
                         legend to such effect;

                    (f)  none of the CommcoCCC Entities has any contract,
                         arrangement or understanding with any broker, finder or
                         similar agent with respect to the transactions
                         contemplated by this Agreement; and

                    (g)  none of the CommcoCCC Entities will violate FCC
                         requirements, including without limitation, rules
                         restricting alien ownership of FCC licenses, in a
                         manner that affects Tech.

     Section  5.22  ASSUMPTIONS, GUARANTIES, ETC. OF INDEBTEDNESS OF OTHER
PERSONS.  CommcoCCC has not guaranteed, endorsed or otherwise become directly or
contingently liable on any indebtedness of any other Person (including, without
limitation, liability by way of agreement, contingent or otherwise, to purchase,
to provide funds for payment, to supply funds to or otherwise invest in the
debtor, or otherwise to assure the creditor against loss), except guaranties by
endorsement of negotiable instruments for deposit or collection in the ordinary
course of business.

                                   ARTICLE VI
                        REPRESENTATIONS OF ART COMPANIES

     Section  6     REPRESENTATIONS WITH RESPECT TO THE ART COMPANIES.  Each of
the ART Companies, jointly and severally, represents and warrants as follows:

     Section  6.1   CORPORATE EXISTENCE.  Each of the ART Companies is a 
corporation duly incorporated, validly existing and in good standing under 
the laws of its jurisdiction of incorporation and is duly qualified to do 
business as a foreign corporation and is in good standing 

                                      -15-

<PAGE>


in each jurisdiction in which the ownership or use of its assets or 
properties, or the conduct or nature of its business, makes such 
qualification necessary (except for jurisdictions in which the failure to so 
qualify or be in good standing would not be reasonably likely to have a 
Material Adverse Effect).  The ART Companies have all requisite corporate 
power and authority to own their properties and to conduct the Business.  
True and complete copy of the Bylaws and the Certificate of Incorporation, as 
in effect and as on file with the Secretary of State of the jurisdiction of 
incorporation, of Tech and the Bylaws and Certificate of Incorporation of 
Tech in the form proposed to be amended have previously been delivered to 
CommcoCCC.

     Section  6.2   POWER AND AUTHORITY.  Each of the ART Companies has all
requisite corporate power and authority, and as of the Closing Date will have
taken all required corporate and other action necessary, to execute, deliver and
perform this Agreement and the Transaction Documents and consummate the
transactions contemplated hereby and thereby.

     Section  6.3   ENFORCEABILITY, ETC.  This Agreement and all the Transaction
Documents to be executed and delivered in connection herewith by either of the
ART Companies have been, or will be as of the Closing Date, duly executed and
delivered and, assuming that this Agreement and the Transaction Documents, as
applicable, are, or as of the Closing Date will be, duly executed and delivered
by, and are within the power and authority of, the other parties thereto,
constitute, or will constitute, the legal, valid and binding obligations of each
of the ART Companies enforceable against each of them in accordance with their
respective terms, except as the enforceability thereof may be limited by
bankruptcy, insolvency, moratorium, reorganization or other similar laws
affecting creditors' rights generally and subject to general principles of
equity (regardless of whether considered in a proceeding in equity or at law).

     Section  6.4   CAPITALIZATION.   As of June 19, 1996, (a) Tech had
outstanding 340 shares of Common Stock, $.01 par value, one share of Series A
Preferred Stock, $.01 par value, and no options or warrants; (b) Telecom had
outstanding 18,114,135 shares of Common Stock, $.001 par value, 445,550 shares
of Series A Preferred Stock, $.001 par value, 114,679 shares of Series B
Preferred Stock, $.001 par value, 7,363 shares of Series C Preferred Stock,
$.001 par value,  61,640 shares of Series D Preferred Stock, $.001 par value,
232,826 shares of Series E Preferred Stock, $.001 par value, 48,893 shares of
Series F Preferred Stock, $.001 par value, options to acquire 1,664,732 shares
of Common Stock and warrants to acquire 2,302,136 shares of Common Stock; and
(c) on a pro forma basis assuming consummation of the ART Reorganization, Tech
would have outstanding 30,086,498 shares of Common Stock, $.001 par value (of
which 20,073,443 shares would have been issued in the ART Reorganization to
existing shareholders of Telecom in respect of Telecom Stock), options to
acquire 1,664,732 shares of Common Stock, and Telecom would have outstanding
1,000 shares of Common Stock, all of which will be held by Tech, and warrants to
acquire 2,302,136 shares of Tech Common Stock.  As of the date hereof, assuming
consummation of the 29,450.16 to 1 stock split, owners of Telecom Stock hold an
aggregate of 276,095 shares of Tech Common Stock.  As of the date hereof, there
are no other outstanding Interests in Tech or Telecom. The Tech Securities have
been duly authorized and will as of the Closing Date be validly issued, fully
paid and non-assessable and will be delivered to
 



                                      -16-

<PAGE>


CommcoCCC as of the Closing Date, free and clear of any Liens, preemptive
rights, escrows, options, rights of first refusal or other agreements, or any
other restrictions affecting rights and other incidents of record and beneficial
ownership, other than (i) as set forth herein and (ii) restrictions on
transferability imposed generally under the Securities Act and under the
securities laws of the several states and the rules and regulations issued in
respect thereto (such state laws, rules and regulations being, collectively,
"BLUE SKY LAWS").  Assuming the accuracy of the representations and warranties
and the compliance with the covenants made by CommcoCCC herein, the issuance and
delivery of the shares of Tech Securities is exempt from the registration
requirements of the Securities Act and the Blue Sky Laws or have been qualified
as may be necessary.

     Section  6.5   TELECOM, SUBSIDIARIES AND INVESTMENTS.  Upon consummation of
the ART Reorganization, Tech will own all the outstanding shares of capital
stock and all other Interests of Telecom other than the Telecom Warrants.   All
outstanding shares of capital stock of Telecom have been duly authorized and
validly issued and are fully paid and nonassessable.  Except as disclosed in the
Preliminary ART Registration Statements, as of the date hereof, Tech does not
own, directly or indirectly, of record or beneficially any capital stock or
other Interest in any Person.

     Section  6.6   CONSENTS, APPROVALS AND NON-CONTRAVENTION.  Except for the
FCC Consent, any consents required under the HSR Act and as set forth on
SCHEDULE 6.6 hereof, the execution, delivery and performance of this Agreement
by each of the ART Companies, nor the consummation of any transaction
contemplated hereby, do not and will not:

          (a)  require any consent or approval of, filing or taking of any other
action with, or notice to, any Person;

          (b)  violate any provision of the Certificate of Incorporation or
ByLaws of Tech or either of the ART Companies;

          (c)  result in a breach of or constitute a default under any contract,
agreement or instrument to which either of the ART Companies is a party or by
which either is bound;

          (d)  result in the creation of any Lien, on any assets of the ART
Companies under any agreement to which either is a party;

          (e)  violate (x) any order, writ, judgment, injunction or decree known
to Tech, or (y) any statute, law, rule or regulation of any court, tribunal or
governmental entity or authority, applicable to either of the ART Companies or
any of their respective properties or assets; or

          (f)  violate any of the ART 38 GHz Authorizations;
 



                                      -17-

<PAGE>


except, as to (a) through (e) above, as would not have a Material Adverse Effect
on the ART Companies, taken as a whole.

     Section  6.7   SEC FILINGS; FINANCIAL STATEMENTS.  (a)  As of the date
hereof, the Preliminary ART Registration Statements conform, and as of their
respective dates, the ART Registration Statements will conform, in all material
respects with the requirements of the Securities Act and as of the date hereof
the Preliminary ART Registration Statement does not, and as of their respective
dates the ART Registration Statements will not, contain any untrue statement of
a material fact or omit to state a material fact required to be stated therein,
or necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading.

          (b)  Each of the ART Financial Statements  (including, in each case,
any related notes thereto) has been prepared in accordance with GAAP applied on
a consistent basis throughout the periods involved (except as may be indicated
in the notes thereto and except that the quarterly financial statements do not
contain all of the footnote disclosures required to be contained in audited
financial statements prepared in accordance with GAAP), and each presents fairly
the consolidated financial position of Tech and Telecom, respectively, at the
respective dates thereof and the consolidated results of its operations and
changes in cash flows for the periods indicated, except that the unaudited
interim financial statements are subject to normal and recurring year-end
adjustments which are not expected to be material in amount.

     Section  6.8   MATERIAL ADVERSE CHANGE.  Except as set forth on SCHEDULE
6.8 hereof or disclosed in the Preliminary ART Registration Statements, since
December 31, 1995, there has been no Material Adverse Change with respect to the
ART Companies taken as a whole.

     Section  6.9   ABSENCE OF UNDISCLOSED LIABILITIES.  As of the date hereof,
neither of the ART Companies has any liabilities of a type required in
accordance with GAAP to be reflected or reserved against (matured or unmatured,
fixed or contingent), which are not fully reflected or provided for on the ART
Financial Statements dated as of March 31, 1995 or otherwise set forth in the
Preliminary ART Registration Statements, except obligations incurred in the
ordinary course of business since March 31, 1995 or as disclosed in the
Preliminary ART Registration Statements.

     Section  6.10  TAXES.  Except as set forth on SCHEDULE 6.10 hereof, the ART
Companies have accurately completed and filed or will file within the time
prescribed by law (including extensions of time approved by the appropriate
taxing authority) all tax returns and reports required to be filed with the
Internal Revenue Service, the State of Delaware, any other states or
governmental subdivisions and all foreign countries except, where the failure to
file would not have a Material Adverse Effect; has paid all taxes, interest,
penalties, assessments or deficiencies shown to be due (or, to the knowledge of
the ART Companies, claimed by such authority or jurisdiction to be due) on or in
respect of such tax returns and reports; and has established reserves, to the
knowledge of the ART Companies, adequate for all taxes accrued but not yet
payable.  Neither of the ART
 



                                      -18-

<PAGE>


Companies knows of (i) any other federal, state, county, municipal or foreign
taxes (or other liabilities in respect thereof) that are due and payable by the
ART Companies which have not been so paid, (ii) any other federal, Delaware,
state, county, municipal or foreign tax returns or reports which are required to
be filed which have not been so filed, (iii) any other unpaid assessment for, or
any fact which would constitute grounds for the assessment of, additional taxes
or penalties for any fiscal period or (iv) any material tax lien, whether
imposed by any federal, state, county, municipal or foreign taxing authority,
outstanding against the assets or business of the ART Companies.  Neither the
federal nor state income tax returns of the ART Companies have been audited.
Neither of the ART Companies has made any election under Section   341(f) of the
Code.

     Section  6.11  LITIGATION.  There are no actions, suits, proceedings,
orders, investigations or claims pending or, to the best of the ART Companies'
knowledge, threatened against or specifically identifying either of the ART
Companies or their respective assets or business or any of their directors or
employees, at law or in equity, before any court, arbitration panel, tribunal or
governmental department, commission, board, bureau, agency or instrumentality
(i) which could have a Material Adverse Effect or (ii) in connection with the
transactions contemplated hereby.  None of the ART Companies is in default with
respect to any judgment, order, writ, injunction or decree of any court or
governmental agency, except where such default will not have a Material Adverse
Effect, and there are no unsatisfied judgments against the ART Companies other
than any as to which the time for payment has not elapsed, including by reason
of any appeal.

     Section  6.12  OTHER RELATIONSHIPS.  All transactions known to either of
the ART Companies of a type required to be disclosed pursuant to Rule 404(a) of
Regulation S-K  pursuant to the Securities Act have been described in the
Preliminary ART Registration Statements.

     Section  6.13  38 GHZ AUTHORIZATIONS.  Set forth on SCHEDULE 6.13 hereof
are all 38 GHz Authorizations owned by Tech, Telecom and ART West, and all 38
GHz Authorizations owned by DCT and Telecom One on the date hereof, including
the city and population covered by the geographic footprint of each 38 GHz
Authorization (the "ART 38 GHz AUTHORIZATIONS").  Tech, Telecom or ART West
owns, manages exclusively or has the right to acquire all of the ART 38 GHz
Authorizations.  The statements made to the FCC by the owners listed on SCHEDULE
6.13 in the applications for the ART 38 GHz Authorizations were true and correct
at the time made and at the time the FCC issued the relevant ART 38 GHz
Authorizations.  The ART 38 GHz Authorizations were duly issued by the FCC, are
in full force and effect, and contain all the conditions placed upon the entire
authorization for each market, except as are found in the FCC Rules.  The ART 38
GHz Authorizations permit the owners listed on SCHEDULE 6.13 to operate within
the service area and on the channels specified.  The owners listed on SCHEDULE
6.13 have good and marketable title to the ART 38 GHz Authorizations (subject to
FCC Rules on transfers of ownership) free and clear of any Lien or management or
service agreement, whether oral or written, except for any of the foregoing in
favor of Tech, Telecom or ART West.  The owners listed on SCHEDULE 6.13 have
fully complied with the terms of all ART 38 GHz Authorizations, the
representations made to the FCC and the FCC Rules, except to the extent such
failure to
 



                                      -19-

<PAGE>


comply with the foregoing would be likely to have a Material Adverse Effect on
any of the ART 38 GHz Authorizations.  There are no pending petitions for
reconsideration or judicial review of the grants of the ART 38 GHz
Authorizations and the grants of the ART 38 GHz Authorizations have become Final
Orders, no longer subject to reconsideration by the FCC on its own motion or to
judicial review.  None of the owners listed on SCHEDULE 6.13 has been notified
of any unresolved protest to the grants of the ART 38 GHz Authorizations or
objections by the FCC and, except for the NPRM, have no reason to believe that
the grants of the ART 38 GHz Authorizations will be rescinded or in any way
modified.  Except for filings, if any, required pursuant to Section   21.711 of
the FCC Rules, each of the owners listed on SCHEDULE 6.13 has timely made all
filings, reports, paid any fees, and otherwise met all FCC applicable
requirements concerning the ART 38 GHz Authorizations, except to the extent such
failure to comply with the foregoing would be likely to have a Material Adverse
Effect on any of the ART 38 GHz Authorizations.  None of the owners listed on
SCHEDULE 6.13 has taken any action or failed to take any action and there are no
formal or other proceedings pending against the owners listed on SCHEDULE 6.13
with respect to any of the ART 38 GHz Authorizations that could reasonably be
expected to lead to the revocation, cancellation, forfeiture or failure to renew
any license issued to the owners listed on SCHEDULE 6.13.  There are no
outstanding notices of apparent liability against the owners listed on SCHEDULE
6.13.  Tech does not know of any facts relating to the owners listed on SCHEDULE
6.13 or any of their respective Affiliates that could reasonably be expected to
cause the FCC to deny its approval of the Assignment Application or revoke or
restrict any of the ART 38 GHz Authorizations or deny its approval of or place
restrictions on the consummation of the ART Reorganization or the Acquisition,
and should any such facts come to the attention of any of the Tech, their
officers or directors, Tech will promptly notify CommcoCCC and take all
reasonable measures to remove any such impediments to consent.  Each of the
owners listed on SCHEDULE 6.13 are fully qualified to be an FCC licensee and
have not violated FCC requirements pertaining to the ART 38 GHz Authorizations,
including without limitation, rules restricting alien ownership of FCC licenses.

     Section  6.14  COMPLIANCE WITH LAWS.  The ART Companies and the conduct of
their respective businesses are in compliance with all applicable laws,
statutes, ordinances, rules, regulations and orders of any federal, foreign,
state or local government and any other governmental department or agency, and
any judgment, decision, decree or order of any court or governmental agency,
department or authority, except where the failure to comply would not have a
Material Adverse Effect on the ART Companies taken as a whole.

     Section  6.15   INVESTMENT COMPANY ACT.  Neither of the ART Companies is an
"investment company" or a company "controlled" by an "investment company" within
the meaning of the Investment Company Act of 1940, as amended.

     Section  6.16   BROKERS, ETC.  Except as set forth on SCHEDULE 6.16 hereof,
neither of the ART Companies is obligated to pay any fee or commission in
connection with, any broker, finder or other similar Person in connection with
any of the transactions contemplated by this Agreement.
 



                                      -20-

<PAGE>


     Section  6.17   CONTRACTS AND COMMITMENTS.  (a) Except as expressly
contemplated by this Agreement or as set forth or disclosed in the Preliminary
ART Registration Statements or on SCHEDULE 6.17 hereof, as of the date hereof,
neither of the ART Companies is a party to, or otherwise bound by any agreement
of a nature required to be disclosed in the Registration Statements pursuant to
Item 601 of Regulation S-K under the Securities Act.

          (b)  Except as set forth in SCHEDULE 6.17 hereof, as of the date
hereof, (a) all of the contracts, agreements and instruments set forth or
described in the Preliminary ART Registration Statements or on SCHEDULE 6.17
hereof are valid, binding and enforceable against the applicable ART Company in
accordance with their respective terms; (b) the applicable ART Company has
performed all material obligations required to be performed by it under such
contracts, agreements and instruments; (c) the applicable ART Company is not, in
any material respect, in default under or in breach of, nor in receipt of any
claim of default or breach, in any material respect, of any such contract,
agreement or instrument to which any applicable ART Company or Subsidiary is
subject; (d) no event has occurred which with the passage of time or the giving
of notice or both would result in a material default, breach or event of
noncompliance under any such contract, agreement or instrument; and (e) none of
the ART Companies has any knowledge of any breach or anticipated breach by the
other parties to any such contract or agreement.

     Section  6.18  PROPERTIES.  Except as disclosed in the Preliminary ART
Registration Statements, as of the date hereof, ART Companies and their
Subsidiaries have good and marketable title to, free and clear of any Liens, and
the right to possession of their respective material tangible and intangible
property reflected in the ART Financial Statements (except for properties and
assets which have been sold or disposed of in the ordinary course of business
since March 31, 1995) or properties, and all such properties and assets acquired
(and not disposed of) since March 31, 1995, as is requisite to the conduct of
the Business.

     Section  6.19  ASSUMPTIONS, GUARANTIES, ETC. OF INDEBTEDNESS OF OTHER
PERSONS.  As of the date hereof, except as disclosed in the Preliminary ART
Registration Statements, neither of the ART Companies has guaranteed, endorsed
or otherwise become directly or contingently liable on any indebtedness of any
other Person (including, without limitation, liability by way of agreement,
contingent or otherwise, to purchase, to provide funds for payment, to supply
funds to or otherwise invest in the debtor, or otherwise to assure the creditor
against loss), except guaranties by endorsement of negotiable instruments for
deposit or collection in the ordinary course of business.
 



                                      -21-

<PAGE>


                                   ARTICLE VII

                                    COVENANTS

     Section  7.1   CONDUCT OF BUSINESS OF COMMCOCCC AND THE ART COMPANIES.
During the period from the date of this Agreement to the Closing Date or the
termination of this Agreement, whichever first occurs, each of CommcoCCC and the
ART Companies shall conduct their respective operations and business according
to its ordinary and usual course of business and use its reasonable best efforts
to preserve intact its business organizations and maintain satisfactory
relationships with licensors, suppliers, distributors, clients and others having
material business relationships with it.  Each of the CommcoCCC Entities and the
ART Companies shall promptly notify (but in any event within five (5) business
days) the other party of any Material Adverse Change (or event or occurrence
reasonably expected to result in a Material Adverse Change) affecting such party
or parties (including, without limitation, governmental complaints,
investigations or hearings (or communications indicating that the same may be
contemplated), or adjudicatory proceedings involving any of the parties, their
businesses or any of their material assets).

     Section  7.2   EXCLUSIVE DEALING.  During the period from the date of this
Agreement to the earlier of the Closing Date or termination of this Agreement,
the CommcoCCC Entities shall not and shall  cause their respective officers,
directors, employees, agents or advisors or other representatives or consultants
not to, directly or indirectly, encourage, solicit, initiate, participate in or
otherwise be a party to any discussions or negotiations with any Person
concerning any Interest in CommcoCCC, the CommcoCCC Assets, the Acquisition, or
any transaction involving the sale of the business or assets of CommcoCCC.
Promptly upon receiving any (or any information about any) such inquiry,
expression of interest, request or proposal from or contract by any Person with
respect to the transaction, the CommcoCCC Entity shall notify Tech as promptly
as practicable of such inquiry, request, proposal or contact and provide Tech
with all relevant information.  If in writing, the CommcoCCC Entity shall
deliver to Tech a copy.

     Section  7.3   APPLICATION FOR COMMISSION CONSENT.   Within ten (10)
business days after the date of this Agreement, CommcoCCC shall cause its FCC
counsel, Covington & Burling, to prepare the Assignment Application.  Such FCC
counsel for  CommcoCCC and the ART Companies shall jointly agree upon, the
Assignment Application, CommcoCCC and Tech shall join in and file such
Assignment Application at such time as jointly determined by such FCC counsel,
and they will diligently take all steps necessary or desirable to prosecute
expeditiously the Assignment Application and to obtain the Commission's
determination that approval of the Assignment Application will serve the public
interest, convenience and necessity.  The failure of the parties to timely file
or diligently prosecute its portion of the Assignment Application, or to
cooperate fully with the other party with respect thereto, shall be deemed a
material breach of this Agreement.

     Section  7.4   OTHER GOVERNMENTAL CONSENTS.  Promptly following the
execution of this



                                      -22-

<PAGE>
 

Agreement but in no event later than thirty (30) business days after the date of
this Agreement, CommcoCCC and the Tech shall proceed to prepare and file with
the appropriate governmental authorities (other than the Commission) such
requests, if any, for approval or waiver as may be required from such
governmental authorities in connection with the transactions contemplated by
this Agreement, including any requests for approvals under the HSR Act.
CommcoCCC and Tech shall jointly, diligently and expeditiously prosecute, and
shall cooperate fully with each other in the prosecution of, such requests for
approval or waiver in all proceedings necessary to secure such approvals and
waivers.

     Section  7.5   THIRD PARTY CONSENTS.  CommcoCCC will use all reasonable
efforts to obtain the consents set forth on SCHEDULE 5.6.  Tech will use all
reasonable efforts to obtain the consents set forth on SCHEDULE 6.6.

     Section  7.6   RESTRICTIVE AGREEMENTS PROHIBITED.  None of the parties
hereto shall become a party to any agreement which by its terms restricts such
party's performance of this Agreement or the consummation of the transactions
contemplated hereunder.

     Section  7.7   DIVIDENDS AND DISTRIBUTIONS; ACQUISITION OF CAPITAL STOCK.
Except as contemplated by the ART Reorganization and the Preliminary ART
Registration Statements, neither CommcoCCC nor either of the ART Companies shall
declare, pay or make any dividend or distribution with respect to, or purchase,
redeem, retire, decease or otherwise acquire for value any Interest in any of
CommcoCCC or the ART Companies, as the case may be.

     Section  7.8   ADDITIONAL NEGATIVE COVENANTS OF COMMCOCCC.  From the date
hereof until the Closing Date, CommcoCCC covenants and agrees that it shall not:

          (a)  amend, modify, terminate, waive or otherwise alter any material
contracts,  nor breach the terms of any such contracts;

          (b)  knowingly take any action or omit to take any action which would
result in the material violation by CommcoCCC of any law or cause a breach in
any material respect by CommcoCCC of any of the representations and warranties
of CommcoCCC set forth in this Agreement;

          (c)  take any other action which would reasonably be expected to cause
a material decrease in the value of the CommcoCCC Assets;

          (d)  consolidate or merge into or with or sell or transfer any of its
assets or otherwise combine with any Person; or

          (e)  make or allow any changes or modifications to be made to its
capital structure as set forth in Section   5.4 hereto.



                                      -23-

<PAGE>
 
     Section  7.9   CORPORATE EXISTENCE.  Each of CommcoCCC and the ART
Companies shall maintain their respective corporate existence, rights and
franchises in full force and effect.

     Section  7.10  ADDITIONAL AFFIRMATIVE COVENANTS.  Each of  the CommcoCCC
Entities and the ART Companies shall use all reasonable efforts to maintain the
accuracy of their respective representations and warranties contained in this
Agreement through and including the Closing Date.

     Section  7.11  REASONABLE BEST EFFORTS.  Subject to the terms and
conditions herein provided, each of the parties hereto agrees to use all
reasonable efforts to take, or cause to be taken, all action, and to do, or
cause to be done, all things necessary, proper or advisable under applicable
laws and regulations to consummate and make effective the transactions
contemplated by this Agreement.

     Section  7.12  REVIEW OF TECH AND COMMCOCCC.  Upon reasonable notice, each
of CommcoCCC and the ART Companies may, prior to the Final Amendment Date,
through their respective representatives, review the properties, books and
records of the ART Companies or CommcoCCC, as the case may be, and their
financial and legal condition as each of CommcoCCC and the ART Companies deem
necessary or advisable to familiarize themselves with such properties and other
matters.  Upon reasonable notice, each of CommcoCCC and Tech shall afford the
others' officers, employees, counsel, accountants and other authorized
representatives access, during reasonable business hours throughout the period
prior to the Closing Date, to its premises, properties, books and records for
the purpose of conducting a complete and thorough investigation and review of
the businesses of the ART Companies or CommcoCCC, as the case may be.

     Section  7.13  DISCLOSURE TO PARTIES.  CommcoCCC and the ART Companies
covenant and agree that if any party should become aware, prior to Closing, that
any of its representations, warranties or covenants is inaccurate or incapable
of being performed in any material respect, written notice of such inaccuracy or
incapability shall be promptly given to the other party.  Nothing contained in
this Section   7.13 shall relieve the party bound by such representation,
warranty or covenant from complying with all terms and conditions of this
Agreement applicable to it.

     Section  7.14  COMMCOCCC OBLIGATION TO PROVIDE INFORMATION.  CommcoCCC
covenants and agrees to furnish to Tech written information necessary to prepare
and file the Preliminary ART Registration Statement and any amendments or
supplements thereto, with regard to the CommcoCCC Assets and each of the
CommcoCCC Entities (the "COMMCOCCC INFORMATION").  The CommcoCCC Information
that is supplied to Tech specifically for inclusion in the Preliminary ART
Registration Statements shall not contain any untrue statement of a material
fact, omit to state any material fact required to be stated therein, or omit any
material fact necessary in order to make the statements therein not misleading.
If at any time prior to the Closing Date any event or circumstance should be
discovered by any of the CommcoCCC Entities with respect to CommcoCCC
Information which is required to be set forth in an amendment or supplement to



                                      -24-

<PAGE>
 
the ART Registration Statements, the CommcoCCC Entities shall immediately notify
Tech and shall use all reasonable efforts to assist Tech in appropriately
amending or supplementing the ART Registration Statements.

     Section  7.15  FINANCIAL REPORTS.  Prior to the Closing Date, Tech shall
furnish to CommcoCCC, within five (5) days after transmission thereof, copies of
all financial statements, reports and any other general written communications
which Tech sends to its stockholders and copies of all registration statements
and all regular, special or periodic reports which it files, or any of its
officers or directors file with respect to Tech, with the SEC or with any
securities exchange on which any of its securities are then listed, and copies
of all press releases and other statements made available generally by Tech to
the public concerning material developments in the businesses of Tech.

     Section  7.16  PUBLIC ANNOUNCEMENTS.  CommcoCCC and the ART Companies will
mutually agree as to timing, form and content before issuing any press release
or otherwise making any public statements with respect to the transactions
contemplated herein and shall not issue any such press release or make any such
public statement prior to reaching such mutual agreement, except as may be
required by law or by obligations pursuant to any listing agreement with any
securities exchange on which their shares are traded.

     Section  7.17  CONFIDENTIALITY.  Whether or not the transactions
contemplated hereby are consummated, each of the parties hereto agrees to keep
confidential any and all information with respect to the other party which it
has received as a result of any investigation made in connection with this
Agreement, and not to disclose or use it for any purpose except in connection
with the transactions contemplated hereby.  Notwithstanding the foregoing,
however, each of CommcoCCC and the ART Companies shall be entitled to disclose
any such information (a) to their respective existing or prospective lenders or
investors in connection with obtaining the financing or consents required in
order to consummate the transactions contemplated hereby; (b) to the extent
required by applicable law, (c) as is necessary to obtain consents to the
consummation of the transactions contemplated hereby, (d) as is necessary in
connection with filings, approvals or rulings to be obtained from any government
agency, including, but not limited to, the Federal Trade Commission, the
Department of Justice, the SEC, and the Internal Revenue Service, and (e) during
the course of or in connection with any litigation, arbitration or other
proceeding based upon or in connection with the subject matter of this
Agreement, including, without limitation, the failure of the transactions
contemplated hereby to be consummated.  This obligation shall not extend to
information that (i) was in the possession of the receiving party at the time of
disclosure; (ii) prior to or after the time of disclosure becomes generally
available to the public, not as a result of any breach of this Agreement by the
receiving party or its employees, directors, officers, attorneys, lenders,
advisors or agents; or (iii) is lawfully acquired by the receiving party from
sources other than the other party and not known by the receiving party to be
subject to a confidentiality agreement by which either party is bound; or (iv)
is approved by the disclosing party in writing for release.  In the event that
the transactions contemplated hereunder are not consummated, the parties shall
return all information received



                                      -25-

<PAGE>
 
from the other parties upon such parties' request.

     Section  7.18  DISTRIBUTION OF TECH SECURITIES PURSUANT TO PLAN OF
REORGANIZATION.  This Agreement shall constitute a plan of reorganization to
which Tech and CommcoCCC are parties.  Promptly, and in any event within 12
months, following receipt of the Tech Securities in exchange for the CommcoCCC
Assets, CommcoCCC shall distribute pursuant to this Agreement all of the Tech
Securities received and any other assets of CommcoCCC to the shareholders of
CommcoCCC in exchange for all of the issued and outstanding shares of capital
stock of CommcoCCC, and following the closing and until such distributions are
made CommcoCCC shall not engage in the active conduct of any trade or business
except to the extent necessary to wind up its affairs.

     Section  7.19   TAXES.  It is intended that the ART Reorganization qualify
as a reorganization described in Section   368 (a)(1)(B) of the Code, that the
Acquisition qualify as a reorganization described in Section   368(a)(1)(C) of
the Code, and that the ART Reorganization, the Equity Offering and the
Acquisition together qualify as transfers to a controlled corporation, Tech,
under Section   351. The parties hereto shall not file any tax return, issue any
document or take any position in any administrative or judicial proceeding with
respect to any tax return or document in a manner inconsistent with the
preceding sentence or otherwise take any action that would prevent the intention
expressed in the preceding sentence from being fulfilled.

     Section  7.20  NEGATIVE COVENANTS OF THE ART COMPANIES.  Without the prior
written consent of CommcoCCC (which shall not be unreasonably withheld or
delayed after the consummation of the Debt Offering and the Equity Offering),
from the date hereof until the Closing Date, each of the ART Companies will
engage in the business described in the Preliminary ART Registration Statements,
will carry on such business in the ordinary course and will not (and will not
permit any of their Subsidiaries to):

          (a)  issue any of its capital stock or any other Interest, except (i)
in connection with the ART Reorganization, as disclosed in Section   6.4 hereof,
(ii) as disclosed in the Preliminary ART Registration Statements, (iii) in a
transaction the purpose of which is to create a holding company, (iv) issuance
of options and other awards pursuant to Tech's Equity Incentive Plan and Tech's
or Telecom's Director's Stock Option Plan, (v) upon the exercise or conversion
of any Interest outstanding as of the date hereof for Tech Common Stock or (vi)
with respect to any Investment permitted by Section   7.20(d);

          (b)  consolidate or merge into or with, sell or  transfer all or
substantially all of its assets or otherwise combine with any Person (whether by
operation of law or otherwise), except as contemplated by the Preliminary ART
Registration Statement, in a transaction the purpose of which is to create a
holding company or in a transaction in which the survivor of the consolidation
or merger becomes a subsidiary;



                                      -26-

<PAGE>
 
          (c)  create, incur or assume any indebtedness for borrowed money in
excess of $25 million in aggregate principal amount at any time outstanding,
except (i) purchase money indebtedness, the net proceeds of which are used to
purchase equipment, software or systems in connection with Business of the ART
Companies; provided such indebtedness is not secured by any assets or property
of the ART Companies other than the equipment so acquired, (ii) without
duplication of clause (d) below, indebtedness in an aggregate amount not to
exceed $20 million of either of the ART Companies incurred primarily in
connection with the acquisition of (A) 38 GHz Authorizations or (B) other
licenses or authorizations of other spectrum approved for microwave point-to-
point transmissions or (iii) indebtedness represented by the Notes issued in the
Debt Offering; or

          (d)  make any Investment in any Person which is not a Subsidiary,
except (i) without duplication of clause (c) above, Investments in an aggregate
amount not to exceed $20 million in connection with the acquisition of (A) 38
GHz Authorizations or (B) other licenses or authorizations of other spectrum
approved for microwave point-to-point transmissions, or (ii) without duplication
of clause (c) above, after the consummation of the Debt Offering and the Equity
Offering, Investments (other than contemplated by (i) above) in connection with
the operation of the Business; provided that the obligations incurred in
connection with such Investments do not in the aggregate exceed $4 million.

The ART Companies shall give CommcoCCC written notice prior to taking any action
prohibited by this Section   7.20, and CommcoCCC covenants to advise the ART
Companies in writing as soon as practicable but in no event later than ten
business days after receipt of such notice (i) whether or not CommcoCCC consents
to such action, and (ii) if it does not consent, whether it will terminate this
Agreement pursuant to Section   13.10 hereof if such action is taken.  If
CommcoCCC has not advised the ART Companies within ten business days, CommcoCCC
shall be deemed to have consented to such action.

     Section  7.21  POST CLOSING CAPITAL CONTRIBUTION REQUIRED.  In the event
that on the date that is six (6) months after the Closing Date (the "ADDITIONAL
CONTRIBUTION DATE") any Pending Applications owned by the ART Companies have
been granted, then as soon as reasonably possible thereafter Columbia, CMC and
CLC shall contribute to the capital of Tech, for no additional consideration,
Pending Applications owned by them that have been granted determined based upon
the following formula:

          (a)  determine the number of Pops covered by Pending Application owned
by the ART Companies that have been granted as of such date;

          (b)  multiply the number determined in (a) above by .3413;



                                      -27-

<PAGE>
 
          (c)  Columbia and CMC shall be obligated jointly to contribute 38 GHz
Authorizations with respect to Pending Applications owned by them that have been
granted that cover an amount of Pops equal to 53.43% of the amount determined in
(b) above, and CLC shall be obligated to contribute 38 GHz Authorizations with
respect to Pending Applications owned by it that have been granted that cover an
amount of Pops equal to 46.57% of the amount determined in (b) above; provided
that neither Columbia, CMC nor CLC shall have any obligation to contribute more
38 GHz Authorizations resulting from Pending Applications that are owned by it
on the Additional Contribution Date.

Columbia, CMC and CLC shall select the 38 GHz Authorizations to be contributed,
which selected 38 GHz Authorizations shall cover no less than the number of Pops
described in clause (c) above.  Columbia and CMC shall make no transfer of any
38 GHz Authorizations resulting from a Pending Application prior to the
Additional Contribution Date unless after giving effect to such transfer
Columbia and CMC continue to own 38 GHz Authorizations resulting from Pending
Applications covering at least 1,068,600 Pops.  CLC shall make no transfer of
any 38 GHz Authorization resulting from a Pending Application prior to the
Additional Contribution Date unless after giving effect to such transfer CLC
shall continue to own 38 GHz Authorization resulting from Pending Applications
covering at least 931,400 Pops.

     Section  7.22  TAX CERTIFICATES.  The Company shall provide to CommcoCCC
the officers' certificates contemplated in the opinion provided for in Section
9.7, which shall be true and correct in all material respects.

                                  ARTICLE VIII

                        CONDITIONS TO TECH'S OBLIGATIONS

     Section  8     CONDITIONS TO TECH'S OBLIGATIONS.  The obligations of  Tech
to consummate the Acquisition in accordance with this Agreement shall be subject
to the satisfaction, at or before the Closing Date, of each of the following
conditions any one or more of which may be waived by Tech:

     Section  8.1   TRUTH OF REPRESENTATIONS AND WARRANTIES.  The
representations and warranties of the CommcoCCC Entities contained in this
Agreement shall be true and correct in all material respects on and as of the
Closing Date with the same effect as though such representations and warranties
had been made on and as of such date (other than those representations and
warranties of the CommcoCCC Entities made as of a certain date, which shall be
true and correct only as of such date), except for changes after the date hereof
which are contemplated or expressly permitted by this Agreement and further,
except to the extent that any breach thereof does not in the aggregate have a
Material Adverse Effect on the CommcoCCC Assets.

     Section  8.2   PERFORMANCE.  Each and all of the agreements, obligations,
covenants, or conditions required by this Agreement to be performed or complied
with by the CommcoCCC



                                      -28-

<PAGE>
 

Entities, on or before the Closing Date pursuant to the terms hereof shall have
been duly performed or complied with in all material respects.

     Section  8.3   NO LITIGATION THREATENED.  No action or proceedings shall
have been instituted and continuing or, to the knowledge of the CommcoCCC
Entities, shall have been threatened before a court or other government body or
by any public authority to restrain or prohibit any of the transactions
contemplated hereby or which, if determined adversely, would have a Material
Adverse Effect on the CommcoCCC Assets.

     Section  8.4   COMMISSION CONSENT.  The FCC Consent shall have become a
Final Order and shall be in full force and effect on the Closing Date, and shall
not impose any unusual or onerous conditions other than the NPRM or any other
condition applicable to the owners or operators of 38 GHz Authorizations
generally.

     Section  8.5   GOVERNMENTAL APPROVALS; CONSENTS.  The waiting period
applicable to the consummation of the Acquisition under the HSR Act shall have
expired or been terminated and, all filings set forth on SCHEDULE 5.6 required
to be made prior to the Closing Date by CommcoCCC shall have been made, and all
consents, approvals and authorizations set forth on SCHEDULE 5.6, shall have
been obtained.

     Section  8.6   OPINION OF COMMCOCCC'S COUNSEL. CommcoCCC shall have
furnished Tech with opinions, dated the Closing Date, of Nelson Mullins Riley &
Scarborough, L.L.P. with respect to corporate and general commercial law matters
and of Covington and Burling with respect to FCC matters, each in form and
substance reasonably acceptable to Tech.

     Section  8.7   NONCOMPETITION AGREEMENT.  CCC, CMC and Columbia shall have
executed and delivered the Noncompetition Agreement.

     Section  8.8   COMMCOCCC COVERAGE POPS.  The Coverage Pops represented by
the 38 GHz Authorizations conveyed to Tech on the Closing Date shall be not less
than 87 million.

     Section  8.9   NASDAQ LISTING.  The Tech Securities shall have been listed
or approved for listing upon notice of issuance by the NASDAQ.

     Section  8.10  CERTIFICATE.  The President or the Executive Vice 
President of CommcoCCC shall have executed and delivered a certificate 
certifying that the conditions set forth in Section 8.1, Section 8.2, and 
Section 8.8 have been satisfied.

                                      -29-
 

<PAGE>

                                                              EXHIBIT 10-31(b)

BOTH BY ACQUIRING THIS NOTE AND BY CONVERTING THIS NOTE, THE HOLDER SHALL BE
DEEMED TO REPRESENT AND WARRANT TO THE BORROWER AND TO ANY AND EVERY PRIOR
HOLDER OF THIS NOTE THAT (i) THE HOLDER IS ACQUIRING THE SECURITIES SO ACQUIRED
FOR THE HOLDER'S OWN ACCOUNT, FOR INVESTMENT, AND NOT WITH A VIEW TO THE RESALE
OR OTHER TRANSFER THEREOF IN A DISTRIBUTION, HAVING NO PARTICIPATION IN ANY SUCH
UNDERTAKING AND NO PARTICIPATION IN THE UNDERWRITING THEREOF, (ii) THE HOLDER
CAN AFFORD TO LOSE THE ENTIRETY OF THE HOLDER'S INVESTMENT IN SUCH SECURITIES
AND (iii) THE HOLDER IS AN ACCREDITED INVESTOR AS DEFINED IN RULE 501(A) UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND HAS SUCH KNOWLEDGE AND EXPERIENCE IN
FINANCIAL AND BUSINESS MATTERS AS TO BE CAPABLE OF EVALUATING THE MERITS AND
RISKS OF ACQUIRING SUCH SECURITIES.  BOTH BY ACQUIRING THIS NOTE AND BY
CONVERTING THIS NOTE, THE HOLDER SHALL BE DEEMED TO COVENANT WITH THE BORROWER
AND WITH ANY AND EVERY PRIOR HOLDER OF THIS NOTE THAT THE HOLDER WILL NOT
RESELL, PLEDGE OR OTHERWISE TRANSFER ANY OR ALL OF THE SECURITIES SO ACQUIRED
UNLESS AND UNTIL EITHER SUCH SECURITIES ARE REGISTERED PURSUANT TO THE
SECURITIES ACT OF 1933, AS AMENDED, AND UNDER APPLICABLE STATE SECURITIES LAWS
OR ELSE THE BORROWER HAS RECEIVED AN OPINION OF COUNSEL ACCEPTABLE TO THE
BORROWER, IN FORM REASONABLY ACCEPTABLE TO THE BORROWER, TO THE EFFECT THAT THE
PROPOSED TRANSFER DOES NOT REQUIRE REGISTRATION UNDER SUCH ACT OR UNDER
APPLICABLE STATE SECURITIES LAWS.

Date of Issuance:  July 3, 1996                                       $1,397,100

                    ADVANCED RADIO TECHNOLOGIES CORPORATION


                        BRIDGE NOTE DUE SEPTEMBER 30, 1996

     Advanced Radio Technologies Corporation, a Delaware corporation (the
"BORROWER"), for value received, hereby promises to pay to Commco, L.L.C., a
Delaware limited  liability company  (together with its successors and permitted
transferees and assigns, the "HOLDER"), and its successors and permitted
transferees and assigns, subject to the terms and conditions of this Note, the
aggregate principal amount of ONE MILLION THREE HUNDRED NINETY-SEVEN THOUSAND
ONE HUNDRED DOLLARS (the "COMMITMENT"), at a bank in the United States specified
by the Holder (the "BANK ACCOUNT"), by transfer of same day funds to the
Holder's account no later than 11:00 A.M. (Washington, D.C. time) on or before
September 30, 1996 (the "MATURITY DATE"), and to pay interest at the Prime Rate
as announced from time to time on such principal amount remaining unpaid
hereunder from time to time outstanding from the Date of Issuance until said
principal amount is paid in full, payable in full upon any prepayment of the
entire Commitment and otherwise at the Maturity Date.

     This Note and the Bridge Notes Due September 30, 1996 in the original
aggregate principal amount of $1,602,900 issued by the Borrower on the date
hereof to Columbia Capital Corporation, a Virginia corporation ("COLUMBIA") (the
"COLUMBIA NOTE") have been issued in connection with the transactions
contemplated by the Asset Acquisition Agreement and Plan of Reorganization dated
July 3, 1996 (the "ASSET ACQUISITION AGREEMENT") among the Borrower, Advanced
Radio Telecom Corp., CommcoCCC, Inc., a Delaware corporation ("COMMCOCCC"), CCC
Millimeter, L.P., a Delaware limited partnership, 



                                       

<PAGE>

Columbia Millimeter Communications, L.P., a Delaware limited partnership, the 
Holder and Columbia. In order to induce each of the parties to enter into the 
Asset Acquisition Agreement and to consummate the transactions contemplated 
thereby, the Holder has agreed to provide the Commitment evidenced by this 
Note for the benefit of the Borrower.  The execution and delivery of this 
Note is required pursuant to the terms of the Asset Acquisition Agreement.  
Payment of the principal of and interest on this Note is secured by the terms 
and conditions of a certain Security Agreement of even date herewith among 
the Borrower and Columbia, as Collateral Agent  (the "SECURITY AGREEMENT").

     This Note is transferrable or assignable to one or more purchasers,
PROVIDED that such transfer or assignment is made in accordance with Section 8.3
hereof.  The Borrower agrees to issue from time to time a replacement Note or
Notes in substantially the form hereof, with changes herein to reflect transfer
or assignment, and in such denominations as the Holder may request to facilitate
such transfers and assignments.  In addition, the Borrower agrees to issue a
replacement Note if this Note has been lost, stolen, mutilated or destroyed.

     The Borrower shall keep a register (the "REGISTER") in which shall be
entered the name and address of the registered holder of this Note and
particulars of this Note and of any transfer of this Note. References to the
"Holders" shall mean the persons listed in the Registers as the payees of the
Notes unless any payee shall have presented a Note to the Borrower for transfer
and the transferee shall have been entered in the Register as a subsequent
holder, in which case the term shall mean such subsequent holder. Ownership of
this Note shall be proven by the Register.

     Article 1.     DEFINITIONS.

     The following terms (except as otherwise expressly provided or unless the
context otherwise clearly requires) for all purposes of this Note shall have the
respective meanings specified below.  All accounting terms used herein and not
expressly defined shall have the meanings given to them in accordance with U.S.
generally accepted accounting principles, and the terms "GENERALLY ACCEPTED
ACCOUNTING PRINCIPLES" and "GAAP" shall mean such accounting principles which
are generally accepted in effect from time to time. Other terms defined
elsewhere in this Agreement shall have the meanings ascribed thereto herein.

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

     "BOARD OF DIRECTORS" means the board of directors of the Borrower or a duly
authorized committee thereof.

     "BUSINESS DAY" means any day other than a Saturday or a Sunday or a day on
which commercial banking institutions in Washington, D.C. are authorized by law
to be closed.

     "CLOSING PRICE" means the last reported sales price on a Trading Day
regular way or, in case no such reported sale takes place on such day, the
average of the reported closing bid and asked prices regular 



                                      -2-

<PAGE>

way, in either case on the principal national securities exchange on which 
the Common Stock is listed or admitted to trading or, if not listed or 
admitted to trading on any national securities exchange, on the Nasdaq 
National Market or, if the Common Stock is not listed or admitted to trading 
on any national securities exchange or quoted on such Nasdaq National Market, 
the average of the closing bid and asked prices in the over-the-counter 
market as furnished by any New York Stock Exchange member firm selected from 
time to time by the Borrower for that purpose.

     "COMMISSION" means the Securities and Exchange Commission as from time to
time constituted, created under the Exchange Act.

     "COMMON STOCK" means the Common Stock, par value $0.001 per share, of the
Borrower.

     "CONVERSION PRICE" means the price per share of Common Stock at which the
principal of and interest on this Note shall be convertible, at the Holder's
option, into Common Stock, which price shall be the lesser of (i) the Scheduled
Price and (ii) 80% of the Current Market Price on the date immediately prior to
the conversion date of this Note, in each case subject to adjustment as and to
the extent provided in this Note.

     "CURRENT MARKET PRICE" on any date means the average of the daily Closing
Prices for the ten consecutive Trading Days preceding such date.

     "DEFAULT" means any condition or event that constitutes an Event of Default
or that, with the giving of notice or lapse of time or both would, unless cured
or waived, become an Event of Default.

     "EVENT OF DEFAULT" means any event or condition specified as such in 
Section 4.1 that shall have continued for the period of time, if any, therein 
designated.

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

     "GUARANTEE" by any Person means any obligation, contingent or otherwise, of
such Person directly or indirectly guaranteeing any Indebtedness or other
obligation of any Person and, without limiting the generality of the foregoing,
any obligation, direct or indirect, contingent or otherwise, of such Person (i)
to purchase or pay (or advance or supply funds for the purchase or payment of)
such Indebtedness or other obligation of such other Person (whether arising by
virtue of partnership arrangements, by agreement to keep well, to purchase
assets, goods, securities or services, to take or pay or to maintain financial
statement conditions, or otherwise) or (ii) entered into for the purpose of
assuring in any other manner the obligee of such Indebtedness or other
obligation for the payment thereof or to protect such obligee against loss in
respect thereof (in whole or in part), provided that the term "Guarantee" shall
not include endorsements for collection or deposit in the ordinary course of
business.  The term "Guarantee" used as a verb has a corresponding meaning.

     "INDEBTEDNESS" of any Person means at any date, without duplication, (i)
all obligations of such Person for borrowed money, (ii) all obligations of such
Person evidenced by bonds, debentures, notes, or other similar instruments,
(iii) all obligations of such Person in respect of letters of credit or other
similar instruments (or reimbursement obligations with respect thereto), except
letters of credit or other similar instruments issued to secure payment of Trade
Payables, (iv) all obligations of such Person to pay the deferred purchase price
of property or services, except Trade Payables, (v) all obligations of such
Person 



                                      -3-

<PAGE>

as lessee under capital leases, (vi) all Indebtedness of others secured by a 
lien on any asset of such Person, whether or not such Indebtedness is assumed 
by such Person, and (vii) all Indebtedness of others Guaranteed by such 
Person.

     "LOAN DOCUMENTS" means this Note and the Security Agreement.

     "NOTES" means this Note and any and all other promissory notes with
substantially the same terms and conditions, which other notes may be issued by
the Issuers to replace this Note as contemplated by the introductory statements
in this Note.

     "PERSON" means any individual, corporation, partnership, limited liability
company, joint venture, trust, unincorporated organization or government or any
agency or political subdivision thereof.

     "PRIME RATE" means the rate of interest announced publicly by NationsBank,
N.A. (Carolinas) from time to time as its "prime rate."

     "SCHEDULED PRICE" means the price per share of Common Stock set forth below
opposite the date this Note is converted as provided herein:

           PAYMENT DATE                 
       MATURITY DATE THROUGH                SCHEDULED RATE

     October  1, 1996 through                   $8.00
     October  31, 1996                    
     November 1, 1996 through                   $7.00
     November 30, 1996                    
     December 1, 1996 through                   $6.00
     December 31, 1996                    
     January 1, 1997 through                    $5.00
     January 31, 1997                     
     February 1, 1997 through                   $4.00
     February 28, 1997                    
     March 1, 1997 through                      $3.00
     March 31, 1997                       
     April 1, 1997 through                      $2.00
     April 30, 1997                       
     May 1, 1997                                $1.00
     On or after May 31, 1997                   $0.01

     in each case subject to adjustment as and to the extent provided in this 
Note.

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

     "SENIOR INDEBTEDNESS" means (i) an aggregate principal amount of $5,000.000
plus interest thereon pursuant to the 10% Promissory Notes dated March 8, 1996
issued by Advanced Radio Telecom Corp. and (ii) the principal sum of $1,500,000
plus interest pursuant to the Nonnegotiable and Nontransferable 



                                      -4-

<PAGE>

Promissory Note issued by Borrower to EMI Communications Corp. pursuant to 
the Asset Purchase Agreement dated April 4, 1995.

     "SUBSIDIARY" means, with respect to any Person, any corporation or other
entity of which a majority of the capital stock or other ownership interests
having ordinary voting power to elect a majority of the board of directors or
other persons performing similar functions are at the time directly or
indirectly owned by such Person.

     "TRADE PAYABLES" means accounts payable or any other indebtedness or
monetary obligations to trade creditors created or assumed in the ordinary
course of business in connection with the obtaining of materials, equipment or
services.

     "TRADING DAY" means each Monday, Tuesday, Wednesday, Thursday and Friday,
other than any day on which securities are generally not traded on the
applicable national securities exchange or over-the- counter.

     "WARRANTS" means Common Stock Purchase Warrants issued by the Borrower as
of the date hereof and bearing Certificate Nos. W-1 through W-2, together with
any other such warrants hereafter issued in replacement or substitution
therefor.

     Article 2.     PAYMENT AND PREPAYMENT.

     Section 2.1    OPTIONAL PREPAYMENTS.  The Borrower may, upon at least 2
Business Days' notice to the Holder, prepay this Note in whole or in part, with
interest accrued to the date of such prepayment on the amount prepaid, provided
that each partial prepayment shall be in a principal amount not less than
$100,000.  No amounts so repaid may be reborrowed hereunder.

     Section 2.2    COMPUTATIONS.  Each payment under this Note shall be made in
same day funds not later than 11:00 A.M. (Washington, D.C. time) on the day when
due in lawful money of the United States of America.  All computations of
interest under this Note shall be made by the Holder on the basis of a year of
365 or 366 days, as the case may be, for the actual number of days elapsed
(including the first day but excluding the last day).  Each change in the Prime
Rate shall take effect immediately upon the occurrence thereof with respect to
the entire principal amount hereof at the time outstanding.    

     Section 2.3    PAYMENT OF PRINCIPAL AND INTEREST.  No provision of this
Note shall alter or impair the obligations of each Issuer, which are absolute
and unconditional, to pay the principal of and interest on this Note at the
place, times and rate, and in the currency, herein prescribed.  The obligations
of the Issuers on this Note are joint and several.

     Article 3.     COVENANTS OF THE ISSUERS.

     Section 3.1    INFORMATION.  The Borrower covenants with the Holder that it
will deliver to the Holder, at its address set forth in the Register, all such
registration statements and prospectuses, and amendments and supplements
thereto, and all such other information, reports and other documents, as re
either filed or required to be filed with the Commission, in each case no more
than two Business Days after the same is either filed or required to be filed
with the Commission.



                                      -5-

<PAGE>

     Section 3.2    SUBORDINATION OF OTHER INDEBTEDNESS.  The Borrower covenants
with the Holder that it will not (nor will it permit any of its subsidiaries to)
incur or assume any Indebtedness other than Indebtedness evidenced by this Note
and the Columbia Note, unless such Indebtedness by its terms is subordinate in
right of payment to this Note and does not in the aggregate exceed $2.5 million
in aggregate principal amount outstanding at any one time; provided such
Indebtedness is not secured by any assets or property of the Borrower (or any of
its subsidiaries) other than equipment, software and systems (if any) purchased
with the proceeds of such Indebtedness.

     Section 3.3    BORROWER MAY MERGE, CONSOLIDATE, ETC., ONLY ON CERTAIN
TERMS.  The Borrower covenants with the Holder that neither it nor any of its
subsidiaries will consolidate with or merge with or into any other Person or
sell, assign, convey, transfer or lease its properties and assets substantially
as an entirety to any Person in any transaction or series of related
transactions, and that it will not permit any Person to consolidate with or
merge into the Borrower (or subsidiary), unless:

          (a)  in case the Borrower or its subsidiary shall consolidate with or
merge into another Person or convey, transfer or lease its properties and assets
substantially as an entirety to any Person in any transaction or series of
related transactions, the Person formed by such consolidation or into which the
Borrower or its subsidiary is merged or the Person that acquires by conveyance,
transfer or lease the properties and assets of the Borrower or its subsidiary
substantially as an entirety shall expressly assume in writing all obligations
of the Borrower under this Note, by an instrument in form satisfactory to the
Holder, the due and punctual payment of the principal of and interest on this
Note and the performance or observance of every covenant herein on the part of
the Borrower to be performed or observed and the Borrower and such person shall
have otherwise complied with the provisions of Article 7;

          (b)  such consolidation, merger, conveyance, transfer or lease will
not adversely affect the validity or enforceability of this Note; and

          (c)  immediately after giving effect to such transaction or series of
related transactions, no Default or Event of Default shall have occurred and be
continuing.

     Section 3.3    STATEMENT BY OFFICERS AS TO DEFAULT.  The Borrower shall
deliver to the Holder, as promptly as practicable and in any event no later than
five Business Days after the Borrower becomes aware of the occurrence of an
Event of Default, a certificate signed by its Chief Executive Officer or Chief
Financial Officer setting forth the details of such Default or Event of Default
and the action that the Issuer proposes to take with respect thereto.

     Article 4.     SUBORDINATION

     Section   4.1  SENIOR INDEBTEDNESS.  The Indebtedness evidenced by this
Note is hereby expressly subordinated, to the extent and in the manner hereafter
set forth, in right of payment to the prior payment in full of all the Senior
Indebtedness.  Any and all claims arising under this Note are and shall be at
all times subject and subordinate to the Senior Indebtedness.

     Section 4.2    INSOLVENCY.  Upon any receivership, insolvency, assignment
for the benefit of creditors, bankruptcy, reorganization or arrangements with
creditors (whether or not pursuant to bankruptcy or other insolvency laws),
dissolution, liquidation, or other marshalling of the assets and liabilities of
the Borrower (i) no amount shall be paid by the Borrower in respect of the
principal of or 



                                      -6-

<PAGE>

interest on this Note at the time outstanding, unless and until the Senior 
Indebtedness then outstanding shall be paid in full, and (ii) no claim or 
proof of claim shall be filed with the Borrower by or on behalf of the Holder 
of this Note which shall assert any right to receive any payments in respect 
of principal of and interest on this Note except subject to the payment in 
full of the Senior Indebtedness then outstanding.

     Section 4.3    DEFAULT ON SENIOR INDEBTEDNESS.  In the instance of an event
of default which has been declared in writing with respect to any Senior
Indebtedness which results in the acceleration of such Senior Indebtedness,
then, unless and until such event of default shall have been cured or waived or
shall have ceased to exist, or all Senior Indebtedness shall have been paid in
full, no payment shall be made in respect of the principal of or interest on
this Note; provided, however, that nothing contained in this Article 4 shall
prohibit the holder from exercising its rights pursuant to Article 7 hereof upon
an Event of Default. 

     Section 4.4    Should any payment or distribution or security, or the
proceeds of any thereof, be collected or received by the Holder of this Note
which is prohibited under the terms of Article 4 of this Note or which is
required to be paid to the holders of Senior Indebtedness by this Article 4, the
Holder of this Note will forthwith, upon notice from any holder of Senior
Indebtedness, deliver the same to the holders of the Senior Indebtedness in
precisely the form received (except for the indorsement without recourse or the
assignment without recourse of the Holder of this Note where necessary) and,
until so delivered, the same shall be held in trust by the Holder of this Note
as the property of the holders of the Senior Indebtedness.

     Article 5.     EVENTS OF DEFAULT AND REMEDIES.

     Section 5.1    "EVENT OF DEFAULT" DEFINED; RIGHTS AND REMEDIES; WAIVER OF
DEFAULT.  In case one or more of the following events (each, an "EVENT OF
DEFAULT") shall have occurred and be continuing (whatever the reason for such
Event of Default and whether it shall be voluntary or involuntary or be effected
by operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

          (a)  failure to pay on or before September 30, 1996 any part of the
principal of, or any interest on, the Note or the Columbia Note; or

          (b)  failure on the part of the Borrower or any of its subsidiaries
duly to observe or perform any of the covenants or agreements on the part of the
Borrower or any of its subsidiaries contained in the Notes (other than those
covered by clause (a) above) for a period of 2 Business Days after the date on
which written notice specifying such failure, stating that such notice is a
"Notice of Default" hereunder and demanding that the Issuer remedy the same,
shall have been given by registered or certified mail, return receipt requested,
to the Issuer; or

          (c)  the Borrower or any of its subsidiaries shall fail to make any
payment at maturity in respect of any Indebtedness of the Borrower or any
subsidiary of an Issuer (other than the Notes) due or within any applicable
grace period; or



                                      -7-

<PAGE>

          (d)  any event or condition shall occur that results in the
acceleration of the maturity of any Indebtedness of the Borrower or any of its
subsidiaries or enables (or, with the giving of notice or lapse of time or both,
would enable) the holder or holders of such Indebtedness or any Person acting on
such holders' behalf to accelerate the maturity thereof; or


          (e)  a court having jurisdiction in the premises shall enter a decree
or order (i) for relief in respect of the Borrower or any of its subsidiaries in
an involuntary case under any applicable bankruptcy, insolvency or other similar
law now or hereafter in effect; (ii) adjudging the Borrower or any of its
subsidiaries a bankrupt or insolvent or approving a petition seeking
reorganization, arrangement or composition in respect of the Borrower or any of
its subsidiaries under any applicable bankruptcy, insolvency or other similar
law; (iii) appointing a receiver, liquidator, assignee, custodian, trustee,
sequestrator (or similar official) of such Issuer or for any substantial part of
the property of the Issuer; or (iv) ordering the winding-up or liquidation of
the affairs of the Borrower or any of its subsidiaries; or

          (f)  the Borrower or any of its subsidiaries shall (i) commence a
voluntary case under any applicable bankruptcy, insolvency or other similar law
now or hereafter in affect or any other case or proceeding to be adjudicated a
bankrupt or insolvent; (ii) shall consent to the entry of an order for relief in
any involuntary case under any such law; (iii) shall consent to the appointment
of or taking possession by a receiver, liquidator, assignee, trustee, custodian,
sequestrator (or similar official) of an Issuer or for any substantial part of
the property of such Issuer; or (iv) shall make any general assignment for the
benefit of creditors; or

          (g)  any material representation or warranty made by the Borrower or
any of its subsidiaries in the Acquisition Agreement, the Security Agreement or
the Warrants, or in any certificate, financial statement or other document
delivered pursuant to any of them, shall prove to have been incorrect or in any
material respect when made; or

          (h)  the Borrower shall fail to convert any Note as provided in
Article 7; then, and in each and every such case (other than an Event of Default
specified in Section 5.1(e) or (f) hereof), the Holder, by notice in writing to
the Borrower, may declare the entire principal amount of this Note and the
interest accrued hereon to be due and payable immediately, and upon any such
declaration the same shall become immediately due and payable; PROVIDED that, if
an Event of Default specified in Section 5.1(e) or (f) occurs, then the
principal of and the accrued interest on this Note shall become and be
immediately due and payable without any declaration or other act on the part of
the Holder; and PROVIDED FURTHER that, in the case of an Event of Default
specified in Section 5.1(a) hereof, the Holder, by notice in writing to the
Borrower, may exercise the conversion rights specified in Article 7.

     Section 5.2    POWERS AND REMEDIES GENERALLY CUMULATIVE; DELAY OR OMISSION
NOT A WAIVER. No right or remedy conferred upon or reserved to the Holder herein
or in the Security Agreement is intended to be exclusive of any other right or
remedy, except that the conversion rights specified in Article 7 are an
exclusive remedy.  With that exception, every right and remedy shall, to the
extent permitted by law, be cumulative and in addition to every other right and
remedy given hereunder or now or hereafter existing at law or in equity or
otherwise.  The assertion or employment of any right or remedy hereunder, or
otherwise, shall not prevent the concurrent assertion or employment of any other
appropriate right or remedy.  No delay or omission of the Holder to exercise any
right or power accruing upon any Event of 



                                      -8-

<PAGE>

Default occurring and continuing as aforesaid shall impair any such right or 
power or shall be construed to be a waiver of any such Event of Default or an 
acquiescence therein; and every power and remedy given by this Note or by law 
may be exercised from time to time, and as often as shall be deemed 
expedient, by the Holder.

     Section 5.3    WAIVER OF PAST DEFAULTS.  The Holder may waive, in
accordance with Section 8.2, any past Default or Event of Default hereunder and
its consequences.  In the case of any such waiver, the Issuer and the Holders
shall be restored to their former positions and rights hereunder, respectively;
but no such waiver shall extend to any subsequent or other Default or impair any
right consequent thereon. Upon any such waiver, such Default shall cease to
exist and be deemed to have been cured and not to have occurred, and any Event
of Default arising therefrom shall be deemed to have been cured and not to have
occurred for every purpose of this Note; but no such waiver shall extend to any
subsequent or other Default or Event of Default or impair any right consequent
thereon.

     Article 6.     REPRESENTATIONS AND WARRANTIES OF THE ISSUERS.

     The Borrower hereby represents and warrants to the Holder as follows:

     Section 6.1    DUE ORGANIZATION.  The Borrower is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware, with full corporate power and authority to conduct its business as
presently conducted and as proposed to be conducted.

     Section 6.2    DUE AUTHORIZATION.  The execution, delivery and performance
by the Borrower of this Note and the Security Agreement (together, the "LOAN
DOCUMENTS") (a) are within the Borrower's corporate powers, (b) have been duly
authorized by all necessary corporate action, (c) do not contravene (i) the
Borrower's charter or bylaws or (ii) law or any contractual restriction binding
on or affecting the Borrower and (d) do not result in the creation of any lien,
security interest or other charge or encumbrance (other than pursuant to the
Loan Documents) upon or with respect to any of its properties.

     Section 6.3    GOVERNMENTAL APPROVALS.  No authorization or approval or
other action by, and no notice to or filing with, any governmental authority or
regulatory body is required for the due execution, delivery and performance by
the Borrower of this Note.

     Section 6.4    ENFORCEABILITY.  Each Loan Document is the legal, valid and
binding obligation of such Issuer enforceable against such Issuer in accordance
with its terms.

     Article 7.     CONVERSION OF THE NOTE.

     Section 7.1    RIGHT TO CONVERT UPON EVENT OF DEFAULT.  The Holder shall
have the right, upon the occurrence and during the continuance of an Event of
Default under Section 5.1(a), to convert all or any portion of the principal
amount of and interest accrued on this Note into that number of fully paid and
non-assessable shares of Common Stock equal to that portion of the principal
amount and accrued interest to be converted divided by the Conversion Price (or
at the then-current adjusted Conversion Price if an adjustment has been made as
provided herein).  Such right may be exercised by the delivery of written notice
to the Borrower that the holder hereof elects to convert this Note.  This Note
shall be deemed to have been converted pursuant to this Section immediately upon
receipt by the Borrower of such notice, which may be transmitted by telecopier,
by reliable overnight courier, by mail or by hand; and at such time 



                                      -9-

<PAGE>

the rights of the Holder of this Note as Holder shall cease, and the Person 
entitled to receive the Common Stock issuable upon conversion shall be 
treated for all purposes as the record holder of such Common Stock as and 
after such time.  The Holder agrees to surrender this Note to the Borrower 
for cancellation promptly following any exercise of its conversion right.  As 
promptly as practicable on or after the conversion date, the Borrower shall 
issue and deliver a certificate or certificates for the number of full shares 
of Common Stock issuable upon conversion, together with payment in lieu of 
any fraction of a share, as provided in Section 7.2.  If this Note is 
converted in part only, upon such conversion the Borrower shall execute to 
the Holder, at the expense of the Borrower, a new Note in the aggregate 
principal amount equal to the unconverted principal amount hereof.

     Section 7.2    FRACTIONS OF SHARES.  No fractional shares of Common Stock
shall be issued upon conversion of this Note.  Instead of any fractional share
of Common Stock that would otherwise be issuable upon conversion of the Note,
the Borrower shall pay a cash adjustment in respect of such fractional share in
an amount equal to such fraction multiplied by the Closing Price (as defined
herein) at the close of business on the day of conversion (or, if such day is
not a Trading Day (as defined herein), on the Trading Day immediately preceding
such day) or, if the Closing Price cannot be determined, the then current market
value.

     Section 7.3    ADJUSTMENT OF CONVERSION PRICE.  (a)  In order to prevent
dilution of the conversion rights evidenced by this Note, the Conversion Price
shall be subject to adjustment from time to time as provided in this Section,
and the number of shares of Common Stock underlying this Note shall be subject
to adjustment from time to time as provided in this Section.

          (b)  If the Borrower at any time subdivides (by any stock split, stock
dividend, recapitalization or otherwise) one or more classes of its outstanding
shares of Common Stock into a greater number of shares, then the Conversion
Price in effect immediately prior to such subdivision shall be proportionately
reduced and the number of shares of Common Stock underlying this Note shall be
proportionately increased.  If the Borrower at any time combines (by reverse
stock split or otherwise) one or more classes of its outstanding shares of
Common Stock into a smaller number of shares, then the Conversion Price in
effect immediately prior to such combination shall be proportionately increased
and the number of shares of Common Stock underlying this Note shall be
proportionately decreased.

          (c)  Any recapitalization, reorganization, reclassification,
consolidation, merger, sale of all or substantially all of the Borrower's assets
or other transaction, in each case effected in such a way that holders of Common
Stock are entitled to receive (either directly or upon subsequent liquidation)
stock, other securities or other assets with respect to or in exchange for
Common Stock, is referred to herein as an "ORGANIC CHANGE."  Prior to the
consummation of any Organic Change, the Borrower shall make appropriate
provision (in form and substance satisfactory to the Holder) to ensure that the
Holder shall thereafter have the right to acquire and receive, in lieu of or in
addition to (as the case may be) the shares of Common Stock immediately
theretofore underlying this Note, such shares of stock, other securities or
other assets as may be issued or payable with respect to or in exchange for the
number of shares of Common Stock immediately theretofore underlying this Note
had such Organic Change not occurred.  In any such case, the Borrower shall make
appropriate provision (in form and substance satisfactory to the Holder) with
respect to the Holder's rights and interests to ensure that the provisions of
this subsection and subsections (f) and (g) hereof shall thereafter be
applicable to the Note (including, in the case of any such consolidation, merger
or sale in which the successor or purchaser is other than the Borrower and in
which the value for the Common Stock reflected by the terms of such
consolidation, merger or sale is less than 



                                      -10-

<PAGE>

the Conversion Price in effect immediately prior to such consolidation, 
merger or sale, an immediate adjustment of the Conversion Price to the 
product of such Conversion Price immediately prior to such consolidation, 
merger or sale multiplied by the ratio of such value of the Common Stock 
divided by the Conversion Price in effect immediately prior to such 
consolidation, merger or sale and a corresponding immediate adjustment in the 
number of shares of Common Stock underlying this Note).  The Borrower shall 
not effect any such consolidation, merger or sale unless, prior to the 
consummation thereof, the successor (if other than the Borrower) resulting 
from consolidation or merger or the purchaser of such assets (as the case may 
be) assumes by written instrument (in form and substance satisfactory to the 
Holder) the obligation to deliver to the Holder such shares of stock, other 
securities or other assets as, in accordance with the foregoing provisions, 
the Holder may be entitled to acquire.

          (d)  If any event occurs of the nature contemplated by the provisions
of this Section but not expressly provided for by such provisions, then the
Board of Directors shall make an appropriate adjustment in the Conversion Price
and the number of shares of Common Stock underlying this Note so as to protect
the rights of the holder of the Note, provided that no such adjustment shall
increase the Conversion Price or decrease the number of shares of Common Stock
underlying this Warrant as otherwise determined pursuant to this Section.

          (e)  Each adjustment to the Conversion Price shall be made to the
nearest .001 of a cent. Immediately upon any adjustment of the Conversion Price,
the Borrower shall give written notice thereof to the Holder, setting forth in
reasonable detail and certifying the calculation of such adjustment.  In
addition, the Borrower shall give written notice to the Holder at least 20 days
prior to the date on which the Borrower takes any action contemplated by
subsection (b), (c) or (d) above.

          (f)  If the Borrower declares or pays a dividend upon the Common Stock
payable otherwise than in cash (except for a stock dividend payable in shares of
Common Stock) out of earnings or earned surplus, determined in accordance with
GAAP consistently applied (a "LIQUIDATING DIVIDEND"), then the Borrower shall
pay to the Holder of this Note at the time of payment thereof the Liquidating
Dividend that would have been paid to such Holder on the Common Stock had this
Note been fully exercised immediately prior to the date on which a record is
taken for such Liquidating Dividend or, if no record is taken, the date as of
which the record holders of Common Stock entitled to such dividend are to be
determined.

          (g)  If at any time the Borrower grants, issues or sells any Options,
Convertible Securities or rights to purchase Capital Stock, Convertible
Securities, Options, other securities or other property pro rata to the record
holders of any class or series of Capital Stock (the "PURCHASE RIGHTS"), then
the Holder of this Note shall be entitled to acquire, upon the terms applicable
to such Purchase Rights, the aggregate Purchase Rights that such holder could
have acquired had such holder held the number of shares of Common Stock
underlying this Note immediately before the date on which a record is taken for
the grant, issuance or sale of such Purchase Rights or, if no such record is
taken, the date as of which the record holders of Common Stock are to be
determined for the grant, issuance or sale of such Purchase Rights. For the
purposes of this subsection:  "CAPITAL STOCK" means common stock, preferred
stock or any other class or series of security representing an equity interest
in a corporation; "CONVERTIBLE SECURITIES" means any Capital Stock or other
securities directly or indirectly convertible into or exchangeable for Capital
Stock; and "OPTIONS" means any options, warrants or other rights to subscribe
for or purchase Capital Stock or Convertible Securities.



                                    -11-

<PAGE>

          (h)  Notwithstanding anything to the contrary contained in this Note,
including this Section 7.3, no adjustment shall be made to the Conversion Price
as a result of the proposed 29,450.16 for 1 Stock Split.

     Section 7.4    NOTICE OF ADJUSTMENTS OF CONVERSION PRICE.  Whenever the
Conversion Price is adjusted as herein provided, the Borrower shall compute the
adjusted Conversion Price and shall prepare a certificate signed by the
Treasurer, any Assistant Treasurer or the Chief Financial Officer of the
Borrower setting forth the adjusted Conversion Price and showing in reasonable
detail the facts upon which such adjustment is based, and such certificate shall
forthwith be delivered to the Holder at its address set forth in the Register.

     Section 7.5    NOTICE OF CERTAIN CORPORATE ACTION.  In case:

          (a)  the Borrower shall declare a dividend or other distribution on
its Common Stock; or

          (b)  the Borrower shall authorize the granting to the holders of its
Common Stock of rights or warrants to subscribe for or purchase any shares of
capital stock of any class or of any other rights (excluding shares of capital
stock or options for capital stock issued pursuant to a benefit plan or
agreement for one or more employees, officers or directors of the Borrower); or

          (c)  of any reclassification of Common Stock (other than a subdivision
or combination of the outstanding shares of Common Stock), or of any
consolidation, merger or share exchange to which the Borrower is a party and for
which approval of any shareholders of the Borrower is required, or of the sale
or transfer of all or substantially all of the assets of the Borrower; or

          (d)  of the voluntary or involuntary dissolution, liquidation or
winding up of the Borrower;

then the Borrower shall cause to be delivered to the Holder at its address set
forth in the Register, at least 20 days (or 10 days in any case specified in
clause (a), (b) or (c) above) prior to the applicable record or effective date
hereinafter specified, a notice stating (x) the date on which a record is to be
taken for the purpose of such dividend, distribution or granting of rights or
warrants, or, if a record is not to be taken, the date as of which the holders
of Common Stock of record who will be entitled to such dividend, distribution,
rights or warrants are to be determined or (y) the date on which such
reclassification, consolidation, merger, share exchange, sale, transfer,
dissolution, liquidation or winding up is expected to become effective, and the
date as of which it is expected that holders of Common Stock of record shall be
entitled to exchange their shares of Common Stock for securities, cash or other
property deliverable upon such reclassification, consolidation, merger, share
exchange, sale, transfer, dissolution, liquidation or winding up.  Neither the
failure to give any such notice nor any defect therein shall affect the legality
or validity of any action described in clauses (a) through (d) of this Section.

     Section 7.6    BORROWER TO RESERVE COMMON STOCK.  The Borrower shall at all
times reserve and keep available, free from preemptive rights, out of the
authorized but unissued Common Stock or out of the Common Stock held in
treasury, for the purpose of effecting the conversion of this Note, the full
number of shares of Common Stock then issuable upon the conversion of all
outstanding Notes.



                                      -12-

<PAGE>

     Section 7.7    TAXES ON CONVERSIONS.  The Borrower will pay any and all
original issuance, transfer, stamp and other similar taxes that may be payable
in respect of the issue or delivery of shares of Common Stock on conversion of
this Note pursuant hereto.  The Issuer shall not, however, be required to pay
any tax that may be payable in respect of any transfer involved in the issue and
delivery of shares of Common Stock in a name other than that of the Holder of
this Note to be converted, and no such issue or delivery shall be made unless
and until the Person requesting such issue has paid to the Borrower the amount
of any such tax or has established to the satisfaction of the Borrower that such
tax has been paid.

     Section 7.8    COVENANT AS TO COMMON STOCK.  The Borrower covenants with
the Holder that all shares of Common Stock that may be issued upon conversion of
this Note will, upon issue, be validly issued, fully paid and nonassessable.

     Section 7.9    PROVISIONS AS TO CONSOLIDATION, MERGER OR SALE OF ASSETS. 
In case of any consolidation of the Borrower with, or merger of the Borrower
into, any other Person, any merger of another Person into the Borrower (other
than a merger that does not result in any reclassification, conversion, exchange
or cancellation of outstanding shares of Common Stock) or any sale or transfer
of all or substantially all of the assets of the Borrower, the Person formed by
such consolidation or resulting from such merger or that acquires such assets,
as the case may be, shall execute and deliver to the Holder a supplemental
instrument providing that the Holder of this Note shall have the right
thereafter to convert such Note only into the kind and amount of securities,
cash and other property, if any, receivable upon such consolidation, merger,
sale or transfer by a holder of the number of shares of Common Stock into which
this Note might have been converted immediately prior to such consolidation,
merger, sale or transfer, assuming such holder of Common Stock (i) is not a
Person with which the Borrower consolidated or into which the Borrower merged or
that merged into the Borrower or to which such sale or transfer was made, as the
case may be (a "CONSTITUENT PERSON"), or an Affiliate of a Constituent Person
and (ii) failed to exercise his rights of election, if any, as to the kind or
amount of securities, cash and other property receivable upon such
consolidation, merger, sale or transfer; PROVIDED that, if the kind or amount of
securities, cash and other property receivable upon such consolidation, merger,
sale or transfer is not the same for each share of Common Stock held immediately
prior to such consolidation, merger, sale or transfer by other than a
Constituent Person or an Affiliate thereof and in respect of which such rights
of election shall not have been exercised ("NONELECTING SHARE"), then for the
purpose of this Section the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, sale or transfer by each
nonelecting share shall be deemed to be the kind and amount so receivable per
share by a plurality of the nonelecting shares.  Such supplemental instrument
shall provide for adjustments, which, for events subsequent to the effective
date of such supplemental instrument, shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Article.  The above
provisions of this Section shall similarly apply to successive consolidations,
mergers, sales or transfers.

     Article 8.     MISCELLANEOUS.

     Section 8.1    GOVERNING LAW.  THIS NOTE SHALL BE DEEMED TO BE A CONTRACT
UNDER THE LAWS OF THE STATE OF DELAWARE AND FOR ALL PURPOSES SHALL BE CONSTRUED
IN ACCORDANCE WITH THE LAWS OF SAID STATE, EXCEPT AS MAY OTHERWISE BE REQUIRED
BY MANDATORY PROVISIONS OF LAW.  THE PARTIES HERETO HEREBY WAIVE PRESENTMENT,
DEMAND, NOTICE, PROTEST AND ALL OTHER DEMANDS AND NOTICES IN CONNECTION WITH THE
DELIVERY, ACCEPTANCE, PERFORMANCE AND ENFORCEMENT OF THIS NOTE, EXCEPT AS
SPECIFICALLY PROVIDED HEREIN.  THE



                                      -13-

<PAGE>

HOLDER OF THIS NOTE BY ACCEPTANCE HEREOF AGREES TO BE BOUND BY THE PROVISIONS 
OF THE NOTE WHICH ARE EXPRESSLY BINDING ON THE HOLDER.  THE SECTION HEADINGS 
HEREIN ARE FOR CONVENIENCE ONLY AND SHALL NOT AFFECT THE CONSTRUCTION HEREOF.

     Section 8.2    AMENDMENT OR MODIFICATION.  Any provision of this Note may
be amended or, subject to Section 5.3, waived with the written consent of the
Issuers and the Holder.

     Section 8.3    TRANSFERS AND ASSIGNMENTS. This Note and any securities
issued upon conversion of this Note may not be sold, transferred, pledged,
hypothecated or otherwise disposed of unless and until:

          (i)  There is then in effect a registration statement under the
     Securities Act covering such proposed disposition and such disposition is
     made in accordance with such registration statement and all applicable
     state securities laws; or

          (ii) (A)  The transferor shall have notified the Borrower of the
     proposed disposition and shall have furnished the Borrower with a statement
     of the circumstances surrounding the proposed disposition, and with an
     opinion of counsel, reasonably satisfactory to the Borrower, that such
     disposition will not require registration of the Note, or such securities
     under the Securities Act and that all requisite action has been or will, on
     a timely basis, be taken under any applicable state securities laws in
     connection with such disposition; and

          (iii)     The proposed transferee shall have agreed in writing to be
     bound by the terms and provisions of this Section 8.

     Notwithstanding the provisions of paragraphs (i) and (ii) above, no such
registration statement or opinion of counsel shall be necessary for transfers
pursuant to Rule 144 (k) promulgated under the Securities Act.

     IN WITNESS WHEREOF, each of the Issuers and the Holder has caused this Note
to be duly executed under its corporate seal.

Dated:  July 3, 1996

[Seal]                        ADVANCED RADIO TECHNOLOGIES CORPORATION


                         By:                                                   
                            ___________________________________________________
                              Name:
                              Title:    

[Seal]                        COMMCO, L.L.C.


                         By:                                                   
                            ___________________________________________________
                              Name:
                              Title:    



                                      -14-

<PAGE>

                                                              EXHIBIT 10-31(c)


BOTH BY ACQUIRING THIS NOTE AND BY CONVERTING THIS NOTE, THE HOLDER SHALL BE
DEEMED TO REPRESENT AND WARRANT TO THE BORROWER AND TO ANY AND EVERY PRIOR
HOLDER OF THIS NOTE THAT (i) THE HOLDER IS ACQUIRING THE SECURITIES SO ACQUIRED
FOR THE HOLDER'S OWN ACCOUNT, FOR INVESTMENT, AND NOT WITH A VIEW TO THE RESALE
OR OTHER TRANSFER THEREOF IN A DISTRIBUTION, HAVING NO PARTICIPATION IN ANY SUCH
UNDERTAKING AND NO PARTICIPATION IN THE UNDERWRITING THEREOF, (ii) THE HOLDER
CAN AFFORD TO LOSE THE ENTIRETY OF THE HOLDER'S INVESTMENT IN SUCH SECURITIES
AND (iii) THE HOLDER IS AN ACCREDITED INVESTOR AS DEFINED IN RULE 501(A) UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND HAS SUCH KNOWLEDGE AND EXPERIENCE IN
FINANCIAL AND BUSINESS MATTERS AS TO BE CAPABLE OF EVALUATING THE MERITS AND
RISKS OF ACQUIRING SUCH SECURITIES.  BOTH BY ACQUIRING THIS NOTE AND BY
CONVERTING THIS NOTE, THE HOLDER SHALL BE DEEMED TO COVENANT WITH THE BORROWER
AND WITH ANY AND EVERY PRIOR HOLDER OF THIS NOTE THAT THE HOLDER WILL NOT
RESELL, PLEDGE OR OTHERWISE TRANSFER ANY OR ALL OF THE SECURITIES SO ACQUIRED
UNLESS AND UNTIL EITHER SUCH SECURITIES ARE REGISTERED PURSUANT TO THE
SECURITIES ACT OF 1933, AS AMENDED, AND UNDER APPLICABLE STATE SECURITIES LAWS
OR ELSE THE BORROWER HAS RECEIVED AN OPINION OF COUNSEL ACCEPTABLE TO THE
BORROWER, IN FORM REASONABLY ACCEPTABLE TO THE BORROWER, TO THE EFFECT THAT THE
PROPOSED TRANSFER DOES NOT REQUIRE REGISTRATION UNDER SUCH ACT OR UNDER
APPLICABLE STATE SECURITIES LAWS.

Date of Issuance:  June 27, 1996                                 $1,000,000

                         ADVANCED RADIO TECHNOLOGIES CORPORATION


                           BRIDGE NOTE DUE SEPTEMBER 30, 1996

     Advanced Radio Technologies Corporation, a Delaware corporation (the
"BORROWER"), for value received, hereby promises to pay to Columbia Capital
Corporation, a Virginia corporation (together with its successors and permitted
transferees and assigns, the "HOLDER"), and its successors and permitted
transferees and assigns, subject to the terms and conditions of this Note, the
aggregate principal amount of ONE MILLION DOLLARS (the "COMMITMENT"), at a bank
in the United States specified by the Holder (the "BANK ACCOUNT"), by transfer
of same day funds to the Holder's account no later than 11:00 A.M. (Washington,
D.C. time) on or before September 30, 1996 (the "MATURITY DATE"), and to pay
interest at the Prime Rate as announced from time to time on such principal
amount remaining unpaid hereunder from time to time outstanding from the Date of
Issuance until said principal amount is paid in full, payable in full upon any
prepayment of the entire Commitment and otherwise at the Maturity Date.

     This Note and the Bridge Note Due September 30, 1996 in the original
principal amount of $1,397,100 issued by the Borrower to Commco, L.L.C., a
Delaware limited  liability company ("CLC") (the "CLC NOTE") have been issued in
connection with the transactions contemplated by the Asset Acquisition Agreement
and Plan of Reorganization dated July 3, 1996 (the "ASSET ACQUISITION
AGREEMENT") among the Borrower, Advanced Radio Telecom Corp., CommcoCCC, Inc., a
Delaware corporation ("COMMCOCCC"), CCC Millimeter, L.P., a Delaware limited
partnership, Columbia Millimeter Communications, L.P., a Delaware limited
partnership, the Holder, and CLC.  In order to induce each 

<PAGE>

of the parties to enter into the Asset Acquisition Agreement and to consummate
the transactions contemplated thereby, the Holder has agreed to provide the
Commitment evidenced by this Note for the benefit of the Borrower.  The
execution and delivery of this Note is required pursuant to the terms of the
Asset Acquisition Agreement.  Payment of the principal of and interest on this
Note is secured by the terms and conditions of a certain Security Agreement of
even date herewith among the Borrower and the Holder, as Collateral Agent  (the
"SECURITY AGREEMENT").

     This Note is transferrable or assignable to one or more purchasers,
PROVIDED that such transfer or assignment is made in accordance with Section 8.3
hereof.  The Borrower agrees to issue from time to time a replacement Note or
Notes in substantially the form hereof, with changes herein to reflect transfer
or assignment, and in such denominations as the Holder may request to facilitate
such transfers and assignments.  In addition, the Borrower agrees to issue a
replacement Note if this Note has been lost, stolen, mutilated or destroyed.

     The Borrower shall keep a register (the "REGISTER") in which shall be
entered the name and address of the registered holder of this Note and
particulars of this Note and of any transfer of this Note. References to the
"Holders" shall mean the persons listed in the Registers as the payees of the
Notes unless any payee shall have presented a Note to the Borrower for transfer
and the transferee shall have been entered in the Register as a subsequent
holder, in which case the term shall mean such subsequent holder. Ownership of
this Note shall be proven by the Register.

     Article 1.     DEFINITIONS.

     The following terms (except as otherwise expressly provided or unless the
context otherwise clearly requires) for all purposes of this Note shall have the
respective meanings specified below.  All accounting terms used herein and not
expressly defined shall have the meanings given to them in accordance with U.S.
generally accepted accounting principles, and the terms "GENERALLY ACCEPTED
ACCOUNTING PRINCIPLES" and "GAAP" shall mean such accounting principles which
are generally accepted in effect from time to time. Other terms defined
elsewhere in this Agreement shall have the meanings ascribed thereto herein.

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

     "BOARD OF DIRECTORS" means the board of directors of the Borrower or a duly
authorized committee thereof.

     "BUSINESS DAY" means any day other than a Saturday or a Sunday or a day on
which commercial banking institutions in Washington, D.C. are authorized by law
to be closed.

     "CLOSING PRICE" means the last reported sales price on a Trading Day
regular way or, in case no such reported sale takes place on such day, the
average of the reported closing bid and asked prices regular way, in either case
on the principal national securities exchange on which the Common Stock is
listed or admitted to trading or, if not listed or admitted to trading on any
national securities exchange, on the 


                                       -2-

<PAGE>

Nasdaq National Market or, if the Common Stock is not listed or admitted to
trading on any national securities exchange or quoted on such Nasdaq National
Market, the average of the closing bid and asked prices in the over-the-counter
market as furnished by any New York Stock Exchange member firm selected from
time to time by the Borrower for that purpose.

     "COMMISSION" means the Securities and Exchange Commission as from time to
time constituted, created under the Exchange Act.

     "COMMON STOCK" means the Common Stock, par value $0.001 per share, of the
Borrower.

     "CONVERSION PRICE" means the price per share of Common Stock at which the
principal of and interest on this Note shall be convertible, at the Holder's
option, into Common Stock, which price shall be the lesser of (i) the Scheduled
Price and (ii) 80% of the Current Market Price on the date immediately prior to
the conversion date of this Note, in each case subject to adjustment as and to
the extent provided in this Note.

     "CURRENT MARKET PRICE" on any date means the average of the daily Closing
Prices for the ten consecutive Trading Days preceding such date.

     "DEFAULT" means any condition or event that constitutes an Event of Default
or that, with the giving of notice or lapse of time or both would, unless cured
or waived, become an Event of Default.

     "EVENT OF DEFAULT" means any event or condition specified as such in
Section 4.1 that shall have
continued for the period of time, if any, therein designated.

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

     "GUARANTEE" by any Person means any obligation, contingent or otherwise, of
such Person directly or indirectly guaranteeing any Indebtedness or other
obligation of any Person and, without limiting the generality of the foregoing,
any obligation, direct or indirect, contingent or otherwise, of such Person (i)
to purchase or pay (or advance or supply funds for the purchase or payment of)
such Indebtedness or other obligation of such other Person (whether arising by
virtue of partnership arrangements, by agreement to keep well, to purchase
assets, goods, securities or services, to take or pay or to maintain financial
statement conditions, or otherwise) or (ii) entered into for the purpose of
assuring in any other manner the obligee of such Indebtedness or other
obligation for the payment thereof or to protect such obligee against loss in
respect thereof (in whole or in part), provided that the term "Guarantee" shall
not include endorsements for collection or deposit in the ordinary course of
business.  The term "Guarantee" used as a verb has a corresponding meaning.

     "INDEBTEDNESS" of any Person means at any date, without duplication, (i)
all obligations of such Person for borrowed money, (ii) all obligations of such
Person evidenced by bonds, debentures, notes, or other similar instruments,
(iii) all obligations of such Person in respect of letters of credit or other
similar instruments (or reimbursement obligations with respect thereto), except
letters of credit or other similar instruments issued to secure payment of Trade
Payables, (iv) all obligations of such Person to pay the deferred purchase price
of property or services, except Trade Payables, (v) all obligations of such
Person as lessee under capital leases, (vi) all Indebtedness of others secured
by a lien on any asset of such Person, 


                                       -3-

<PAGE>

whether or not such Indebtedness is assumed by such Person, and (vii) all
Indebtedness of others Guaranteed by such Person.

     "LOAN DOCUMENTS" means this Note and the Security Agreement.

     "NOTES" means this Note and any and all other promissory notes with
substantially the same terms and conditions, which other notes may be issued by
the Issuers to replace this Note as contemplated by the introductory statements
in this Note.

     "PERSON" means any individual, corporation, partnership, limited liability
company, joint venture, trust, unincorporated organization or government or any
agency or political subdivision thereof.

     "PRIME RATE" means the rate of interest announced publicly by NationsBank,
N.A. (Carolinas) from time to time as its "prime rate."

     "SCHEDULED PRICE" means the price per share of Common Stock set forth below
opposite the date this Note is converted as provided herein:

           Payment Date      
     Maturity Date through                   Scheduled Rate
     ---------------------                   --------------

     October 31, 1996                             $8.00
     October 31, 1996 through
     November 30, 1996                            $7.00
     November 30, 1996 through
     December 31, 1996                            $6.00
     December 31, 1996 through
     January 31, 1997                             $5.00
     January 31, 1997 through
     February 28, 1997                            $4.00
     February 28, 1997 through
     March 31, 1997                               $3.00
     March 31, 1997 through
     April 30, 1997                               $2.00
     April 30, 1997 through
     May 31, 1997                                 $1.00
     On or after May 31, 1997                     $0.01

     in each case subject to adjustment as and to the extent provided in this
Note.

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

     "SENIOR INDEBTEDNESS" means (i) an aggregate principal amount of $5,000.000
plus interest thereon pursuant to the 10% Promissory Notes dated March 8, 1996
issued by Advanced Radio Telecom Corp. and (ii) the principal sum of $1,500,000
plus interest pursuant to the Nonnegotiable and Nontransferable Promissory Note
issued by Borrower to EMI Communications Corp. pursuant to the Asset Purchase
Agreement dated April 4, 1995.


                                       -4-

<PAGE>

     "SUBSIDIARY" means, with respect to any Person, any corporation or other
entity of which a majority of the capital stock or other ownership interests
having ordinary voting power to elect a majority of the board of directors or
other persons performing similar functions are at the time directly or
indirectly owned by such Person.

     "TRADE PAYABLES" means accounts payable or any other indebtedness or
monetary obligations to trade creditors created or assumed in the ordinary
course of business in connection with the obtaining of materials, equipment or
services.

     "TRADING DAY" means each Monday, Tuesday, Wednesday, Thursday and Friday,
other than any day on which securities are generally not traded on the
applicable national securities exchange or over-the- counter.

     "WARRANTS" means Common Stock Purchase Warrants issued by the Borrower as
of the date hereof and bearing Certificate Nos. W-1 through W-2, together with
any other such warrants hereafter issued in replacement or substitution
therefor.

     Article 2.     PAYMENT AND PREPAYMENT.

     Section 2.1    OPTIONAL PREPAYMENTS.  The Borrower may, upon at least 2
Business Days' notice to the Holder, prepay this Note in whole or in part, with
interest accrued to the date of such prepayment on the amount prepaid, provided
that each partial prepayment shall be in a principal amount not less than
$100,000.  No amounts so repaid may be reborrowed hereunder.

     Section 2.2    COMPUTATIONS.  Each payment under this Note shall be made in
same day funds not later than 11:00 A.M. (Washington, D.C. time) on the day when
due in lawful money of the United States of America.  All computations of
interest under this Note shall be made by the Holder on the basis of a year of
365 or 366 days, as the case may be, for the actual number of days elapsed
(including the first day but excluding the last day).  Each change in the Prime
Rate shall take effect immediately upon the occurrence thereof with respect to
the entire principal amount hereof at the time outstanding.    

     Section 2.3    PAYMENT OF PRINCIPAL AND INTEREST.  No provision of this
Note shall alter or impair the obligations of each Issuer, which are absolute
and unconditional, to pay the principal of and interest on this Note at the
place, times and rate, and in the currency, herein prescribed.  The obligations
of the Issuers on this Note are joint and several.

     Article 3.     COVENANTS OF THE ISSUERS.

     Section 3.1    INFORMATION.  The Borrower covenants with the Holder that it
will deliver to the Holder, at its address set forth in the Register, all such
registration statements and prospectuses, and amendments and supplements
thereto, and all such other information, reports and other documents, as re
either filed or required to be filed with the Commission, in each case no more
than two Business Days after the same is either filed or required to be filed
with the Commission.

     Section 3.2    SUBORDINATION OF OTHER INDEBTEDNESS.  The Borrower covenants
with the Holder that it will not (nor will it permit any of its subsidiaries to)
incur or assume any Indebtedness other than Indebtedness evidenced by this Note
and the CLC Note, unless such Indebtedness by its terms is 


                                       -5-

<PAGE>

subordinate in right of payment to this Note and does not in the aggregate
exceed $2.5 million in aggregate principal amount outstanding at any one time;
provided such Indebtedness is not secured by any assets or property of the
Borrower (or any of its subsidiaries) other than equipment, software and systems
(if any) purchased with the proceeds of such Indebtedness.

     Section 3.3    BORROWER MAY MERGE, CONSOLIDATE, ETC., ONLY ON CERTAIN
TERMS.  The Borrower covenants with the Holder that neither it nor any of its
subsidiaries will consolidate with or merge with or into any other Person or
sell, assign, convey, transfer or lease its properties and assets substantially
as an entirety to any Person in any transaction or series of related
transactions, and that it will not permit any Person to consolidate with or
merge into the Borrower (or subsidiary), unless:

          (a)  in case the Borrower or its subsidiary shall consolidate with or
merge into another Person or convey, transfer or lease its properties and assets
substantially as an entirety to any Person in any transaction or series of
related transactions, the Person formed by such consolidation or into which the
Borrower or its subsidiary is merged or the Person that acquires by conveyance,
transfer or lease the properties and assets of the Borrower or its subsidiary
substantially as an entirety shall expressly assume in writing all obligations
of the Borrower under this Note, by an instrument in form satisfactory to the
Holder, the due and punctual payment of the principal of and interest on this
Note and the performance or observance of every covenant herein on the part of
the Borrower to be performed or observed and the Borrower and such person shall
have otherwise complied with the provisions of Article 7;

          (b)  such consolidation, merger, conveyance, transfer or lease will
not adversely affect the validity or enforceability of this Note; and

          (c)  immediately after giving effect to such transaction or series of
related transactions, no Default or Event of Default shall have occurred and be
continuing.

     Section 3.3    STATEMENT BY OFFICERS AS TO DEFAULT.  The Borrower shall
deliver to the Holder, as promptly as practicable and in any event no later than
five Business Days after the Borrower becomes aware of the occurrence of an
Event of Default, a certificate signed by its Chief Executive Officer or Chief
Financial Officer setting forth the details of such Default or Event of Default
and the action that the Issuer proposes to take with respect thereto.

     Article 4.     SUBORDINATION

     Section 4.1    SENIOR INDEBTEDNESS.  The Indebtedness evidenced by this
Note is hereby expressly subordinated, to the extent and in the manner hereafter
set forth, in right of payment to the prior payment in full of all the Senior
Indebtedness.  Any and all claims arising under this Note are and shall be at
all times subject and subordinate to the Senior Indebtedness.

     Section 4.2    INSOLVENCY.  Upon any receivership, insolvency, assignment
for the benefit of creditors, bankruptcy, reorganization or arrangements with
creditors (whether or not pursuant to bankruptcy or other insolvency laws),
dissolution, liquidation, or other marshalling of the assets and liabilities of
the Borrower (i) no amount shall be paid by the Borrower in respect of the
principal of or interest on this Note at the time outstanding, unless and until
the Senior Indebtedness then outstanding shall be paid in full, and (ii) no
claim or proof of claim shall be filed with the Borrower by or on behalf of the
Holder of this Note which shall assert any right to receive any payments in
respect of principal of and 


                                       -6-

<PAGE>

interest on this Note except subject to the payment in full of the Senior
Indebtedness then outstanding.

     Section 4.3    DEFAULT ON SENIOR INDEBTEDNESS.  In the instance of an event
of default which has been declared in writing with respect to any Senior
Indebtedness which results in the acceleration of such Senior Indebtedness,
then, unless and until such event of default shall have been cured or waived or
shall have ceased to exist, or all Senior Indebtedness shall have been paid in
full, no payment shall be made in respect of the principal of or interest on
this Note; provided, however, that nothing contained in this Article 4 shall
prohibit the holder from exercising its rights pursuant to Article 7 hereof upon
an Event of Default under Section 5.1(a) hereof. 

     Section 4.4    Should any payment or distribution or security, or the
proceeds of any thereof, be collected or received by the Holder of this Note
which is prohibited under the terms of Article 4 of this Note or which is
required to be paid to the holders of Senior Indebtedness by this Article 4, the
Holder of this Note will forthwith, upon notice from any holder of Senior
Indebtedness, deliver the same to the holders of the Senior Indebtedness in
precisely the form received (except for the indorsement without recourse or the
assignment without recourse of the Holder of this Note where necessary) and,
until so delivered, the same shall be held in trust by the Holder of this Note
as the property of the holders of the Senior Indebtedness.

     Article 5.     EVENTS OF DEFAULT AND REMEDIES.

     Section 5.1    "EVENT OF DEFAULT" DEFINED; RIGHTS AND REMEDIES; WAIVER OF
DEFAULT.  In case one or more of the following events (each, an "EVENT OF
DEFAULT") shall have occurred and be continuing (whatever the reason for such
Event of Default and whether it shall be voluntary or involuntary or be effected
by operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

          (a)  failure to pay on or before September 30 1996 any part of the
principal of, or any interest on, the Note or failure to pay on or before
September 30, 1996 any part of the principal of, or any interest on, the CLC
Note; or

          (b)  failure on the part of the Borrower or any of its subsidiaries
duly to observe or perform any of the covenants or agreements on the part of the
Borrower or any of its subsidiaries contained in the Notes (other than those
covered by clause (a) above) for a period of 2 Business Days after the date on
which written notice specifying such failure, stating that such notice is a
"Notice of Default" hereunder and demanding that the Issuer remedy the same,
shall have been given by registered or certified mail, return receipt requested,
to the Issuer; or

          (c)  the Borrower or any of its subsidiaries shall fail to make any
payment at maturity in respect of any Indebtedness of the Borrower or any
subsidiary of an Issuer (other than the Notes) due or within any applicable
grace period; or

          (d)  any event or condition shall occur that results in the
acceleration of the maturity of any Indebtedness of the Borrower or any of its
subsidiaries or enables (or, with the giving of notice or lapse of time or both,
would enable) the holder or holders of such Indebtedness or any Person acting on
such holders' behalf to accelerate the maturity thereof; or


                                       -7-

<PAGE>

          (e)  a court having jurisdiction in the premises shall enter a decree
or order (i) for relief in respect of the Borrower or any of its subsidiaries in
an involuntary case under any applicable bankruptcy, insolvency or other similar
law now or hereafter in effect; (ii) adjudging the Borrower or any of its
subsidiaries a bankrupt or insolvent or approving a petition seeking
reorganization, arrangement or composition in respect of the Borrower or any of
its subsidiaries under any applicable bankruptcy, insolvency or other similar
law; (iii) appointing a receiver, liquidator, assignee, custodian, trustee,
sequestrator (or similar official) of such Issuer or for any substantial part of
the property of the Issuer; or (iv) ordering the winding-up or liquidation of
the affairs of the Borrower or any of its subsidiaries; or

          (f)  the Borrower or any of its subsidiaries shall (i) commence a
voluntary case under any applicable bankruptcy, insolvency or other similar law
now or hereafter in affect or any other case or proceeding to be adjudicated a
bankrupt or insolvent; (ii) shall consent to the entry of an order for relief in
any involuntary case under any such law; (iii) shall consent to the appointment
of or taking possession by a receiver, liquidator, assignee, trustee, custodian,
sequestrator (or similar official) of an Issuer or for any substantial part of
the property of such Issuer; or (iv) shall make any general assignment for the
benefit of creditors; or

          (g)  any material representation or warranty made by the Borrower or
any of its subsidiaries in the Acquisition Agreement, the Security Agreement or
the Warrants, or in any certificate, financial statement or other document
delivered pursuant to any of them, shall prove to have been incorrect or in any
material respect when made; or

          (h)  the Borrower shall fail to convert any Note as provided in
Article 7; then, and in each and every such case (other than an Event of Default
specified in Section 5.1(e) or (f) hereof), the Holder, by notice in writing to
the Borrower, may declare the entire principal amount of this Note and the
interest accrued hereon to be due and payable immediately, and upon any such
declaration the same shall become immediately due and payable; PROVIDED that, if
an Event of Default specified in Section 5.1(e) or (f) occurs, then the
principal of and the accrued interest on this Note shall become and be
immediately due and payable without any declaration or other act on the part of
the Holder; and PROVIDED FURTHER that, in the case of an Event of Default
specified in Section 5.1(a) hereof, the Holder, by notice in writing to the
Borrower, may exercise the conversion rights specified in Article 7.

     Section 5.2    POWERS AND REMEDIES GENERALLY CUMULATIVE; DELAY OR OMISSION
NOT A WAIVER. No right or remedy conferred upon or reserved to the Holder herein
or in the Security Agreement is intended to be exclusive of any other right or
remedy, except that the conversion rights specified in Article 7 are an
exclusive remedy.  With that exception, every right and remedy shall, to the
extent permitted by law, be cumulative and in addition to every other right and
remedy given hereunder or now or hereafter existing at law or in equity or
otherwise.  The assertion or employment of any right or remedy hereunder, or
otherwise, shall not prevent the concurrent assertion or employment of any other
appropriate right or remedy.  No delay or omission of the Holder to exercise any
right or power accruing upon any Event of Default occurring and continuing as
aforesaid shall impair any such right or power or shall be construed to be a
waiver of any such Event of Default or an acquiescence therein; and every power
and remedy given by this Note or by law may be exercised from time to time, and
as often as shall be deemed expedient, by the Holder.

     Section 5.3    WAIVER OF PAST DEFAULTS.  The Holder may waive, in
accordance with Section 8.2, any past Default or Event of Default hereunder and
its consequences.  In the case of any such waiver, the 


                                       -8-

<PAGE>

Issuer and the Holders shall be restored to their former positions and rights
hereunder, respectively; but no such waiver shall extend to any subsequent or
other Default or impair any right consequent thereon. Upon any such waiver, such
Default shall cease to exist and be deemed to have been cured and not to have
occurred, and any Event of Default arising therefrom shall be deemed to have
been cured and not to have occurred for every purpose of this Note; but no such
waiver shall extend to any subsequent or other Default or Event of Default or
impair any right consequent thereon.

     Article 6.     REPRESENTATIONS AND WARRANTIES OF THE ISSUERS.

     The Borrower hereby represents and warrants to the Holder as follows:

     Section 6.1    DUE ORGANIZATION.  The Borrower is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware, with full corporate power and authority to conduct its business as
presently conducted and as proposed to be conducted.

     Section 6.2    DUE AUTHORIZATION.  The execution, delivery and performance
by the Borrower of this Note and the Security Agreement (together, the "LOAN
DOCUMENTS") (a) are within the Borrower's corporate powers, (b) have been duly
authorized by all necessary corporate action, (c) do not contravene (i) the
Borrower's charter or bylaws or (ii) law or any contractual restriction binding
on or affecting the Borrower and (d) do not result in the creation of any lien,
security interest or other charge or encumbrance (other than pursuant to the
Loan Documents) upon or with respect to any of its properties.

     Section 6.3    GOVERNMENTAL APPROVALS.  No authorization or approval or
other action by, and no notice to or filing with, any governmental authority or
regulatory body is required for the due execution, delivery and performance by
the Borrower of this Note.

     Section 6.4    ENFORCEABILITY.  Each Loan Document is the legal, valid and
binding obligation of such Issuer enforceable against such Issuer in accordance
with its terms.

     Article 7.     CONVERSION OF THE NOTE.

     Section 7.1    RIGHT TO CONVERT UPON EVENT OF DEFAULT.  The Holder shall
have the right, upon the occurrence and during the continuance of an Event of
Default under Section 5.1(a) hereof, to convert all or any portion of the
principal amount of and interest accrued on this Note into that number of fully
paid and non-assessable shares of Common Stock equal to that portion of the
principal amount and accrued interest to be converted divided by the Conversion
Price (or at the then-current adjusted Conversion Price if an adjustment has
been made as provided herein).  Such right may be exercised by the delivery of
written notice to the Borrower that the holder hereof elects to convert this
Note.  This Note shall be deemed to have been converted pursuant to this Section
immediately upon receipt by the Borrower of such notice, which may be
transmitted by telecopier, by reliable overnight courier, by mail or by hand;
and at such time the rights of the Holder of this Note as Holder shall cease,
and the Person entitled to receive the Common Stock issuable upon conversion
shall be treated for all purposes as the record holder of such Common Stock as
and after such time.  The Holder agrees to surrender this Note to the Borrower
for cancellation promptly following any exercise of its conversion right.  As
promptly as practicable on or after the conversion date, the Borrower shall
issue and deliver a certificate or certificates for the number of full shares of
Common Stock issuable upon conversion, together with payment in lieu of any
fraction of a share, as provided in Section 7.2.  If this Note is converted in
part only, upon such conversion the 


                                       -9-

<PAGE>

Borrower shall execute to the Holder, at the expense of the Borrower, a new Note
in the aggregate principal amount equal to the unconverted principal amount
hereof.

     Section 7.2    FRACTIONS OF SHARES.  No fractional shares of Common Stock
shall be issued upon conversion of this Note.  Instead of any fractional share
of Common Stock that would otherwise be issuable upon conversion of the Note,
the Borrower shall pay a cash adjustment in respect of such fractional share in
an amount equal to such fraction multiplied by the Closing Price (as defined
herein) at the close of business on the day of conversion (or, if such day is
not a Trading Day (as defined herein), on the Trading Day immediately preceding
such day) or, if the Closing Price cannot be determined, the then current market
value.

     Section 7.3    ADJUSTMENT OF CONVERSION PRICE.  (a)  In order to prevent
dilution of the conversion rights evidenced by this Note, the Conversion Price
shall be subject to adjustment from time to time as provided in this Section,
and the number of shares of Common Stock underlying this Note shall be subject
to adjustment from time to time as provided in this Section.

          (b)  If the Borrower at any time subdivides (by any stock split, stock
dividend, recapitalization or otherwise) one or more classes of its outstanding
shares of Common Stock into a greater number of shares, then the Conversion
Price in effect immediately prior to such subdivision shall be proportionately
reduced and the number of shares of Common Stock underlying this Note shall be
proportionately increased.  If the Borrower at any time combines (by reverse
stock split or otherwise) one or more classes of its outstanding shares of
Common Stock into a smaller number of shares, then the Conversion Price in
effect immediately prior to such combination shall be proportionately increased
and the number of shares of Common Stock underlying this Note shall be
proportionately decreased.

          (c)  Any recapitalization, reorganization, reclassification,
consolidation, merger, sale of all or substantially all of the Borrower's assets
or other transaction, in each case effected in such a way that holders of Common
Stock are entitled to receive (either directly or upon subsequent liquidation)
stock, other securities or other assets with respect to or in exchange for
Common Stock, is referred to herein as an "ORGANIC CHANGE."  Prior to the
consummation of any Organic Change, the Borrower shall make appropriate
provision (in form and substance satisfactory to the Holder) to ensure that the
Holder shall thereafter have the right to acquire and receive, in lieu of or in
addition to (as the case may be) the shares of Common Stock immediately
theretofore underlying this Note, such shares of stock, other securities or
other assets as may be issued or payable with respect to or in exchange for the
number of shares of Common Stock immediately theretofore underlying this Note
had such Organic Change not occurred.  In any such case, the Borrower shall make
appropriate provision (in form and substance satisfactory to the Holder) with
respect to the Holder's rights and interests to ensure that the provisions of
this subsection and subsections (f) and (g) hereof shall thereafter be
applicable to the Note (including, in the case of any such consolidation, merger
or sale in which the successor or purchaser is other than the Borrower and in
which the value for the Common Stock reflected by the terms of such
consolidation, merger or sale is less than the Conversion Price in effect
immediately prior to such consolidation, merger or sale, an immediate adjustment
of the Conversion Price to the product of such Conversion Price immediately
prior to such consolidation, merger or sale multiplied by the ratio of such
value of the Common Stock divided by the Conversion Price in effect immediately
prior to such consolidation, merger or sale and a corresponding immediate
adjustment in the number of shares of Common Stock underlying this Note).  The
Borrower shall not effect any such consolidation, merger or sale unless, prior
to the consummation thereof, the successor (if other than the Borrower)
resulting from consolidation or merger or the purchaser of such 


                                      -10-

<PAGE>

assets (as the case may be) assumes by written instrument (in form and substance
satisfactory to the Holder) the obligation to deliver to the Holder such shares
of stock, other securities or other assets as, in accordance with the foregoing
provisions, the Holder may be entitled to acquire.

          (d)  If any event occurs of the nature contemplated by the provisions
of this Section but not expressly provided for by such provisions, then the
Board of Directors shall make an appropriate adjustment in the Conversion Price
and the number of shares of Common Stock underlying this Note so as to protect
the rights of the holder of the Note, provided that no such adjustment shall
increase the Conversion Price or decrease the number of shares of Common Stock
underlying this Warrant as otherwise determined pursuant to this Section.

          (e)  Each adjustment to the Conversion Price shall be made to the
nearest .001 of a cent. Immediately upon any adjustment of the Conversion Price,
the Borrower shall give written notice thereof to the Holder, setting forth in
reasonable detail and certifying the calculation of such adjustment.  In
addition, the Borrower shall give written notice to the Holder at least 20 days
prior to the date on which the Borrower takes any action contemplated by
subsection (b), (c) or (d) above.

          (f)  If the Borrower declares or pays a dividend upon the Common Stock
payable otherwise than in cash (except for a stock dividend payable in shares of
Common Stock) out of earnings or earned surplus, determined in accordance with
GAAP consistently applied (a "LIQUIDATING DIVIDEND"), then the Borrower shall
pay to the Holder of this Note at the time of payment thereof the Liquidating
Dividend that would have been paid to such Holder on the Common Stock had this
Note been fully exercised immediately prior to the date on which a record is
taken for such Liquidating Dividend or, if no record is taken, the date as of
which the record holders of Common Stock entitled to such dividend are to be
determined.

          (g)  If at any time the Borrower grants, issues or sells any Options,
Convertible Securities or rights to purchase Capital Stock, Convertible
Securities, Options, other securities or other property pro rata to the record
holders of any class or series of Capital Stock (the "PURCHASE RIGHTS"), then
the Holder of this Note shall be entitled to acquire, upon the terms applicable
to such Purchase Rights, the aggregate Purchase Rights that such holder could
have acquired had such holder held the number of shares of Common Stock
underlying this Note immediately before the date on which a record is taken for
the grant, issuance or sale of such Purchase Rights or, if no such record is
taken, the date as of which the record holders of Common Stock are to be
determined for the grant, issuance or sale of such Purchase Rights. For the
purposes of this subsection:  "CAPITAL STOCK" means common stock, preferred
stock or any other class or series of security representing an equity interest
in a corporation; "CONVERTIBLE SECURITIES" means any Capital Stock or other
securities directly or indirectly convertible into or exchangeable for Capital
Stock; and "OPTIONS" means any options, warrants or other rights to subscribe
for or purchase Capital Stock or Convertible Securities.

          (h)  Notwithstanding anything to the contrary contained in this Note,
including this Section 7.3, no adjustment shall be made to the Conversion Price
as a result of the proposed 29,450.16 for 1 Stock Split.

     Section 7.4    NOTICE OF ADJUSTMENTS OF CONVERSION PRICE.  Whenever the
Conversion Price is adjusted as herein provided, the Borrower shall compute the
adjusted Conversion Price and shall prepare a certificate signed by the
Treasurer, any Assistant Treasurer or the Chief Financial Officer of the
Borrower setting forth the adjusted Conversion Price and showing in reasonable
detail the facts upon which 


                                      -11-

<PAGE>

such adjustment is based, and such certificate shall forthwith be delivered to
the Holder at its address set forth in the Register.

     Section 7.5    NOTICE OF CERTAIN CORPORATE ACTION.  In case:

          (a)  the Borrower shall declare a dividend or other distribution on
its Common Stock; or

          (b)  the Borrower shall authorize the granting to the holders of its
Common Stock of rights or warrants to subscribe for or purchase any shares of
capital stock of any class or of any other rights (excluding shares of capital
stock or options for capital stock issued pursuant to a benefit plan or
agreement for one or more employees, officers or directors of the Borrower); or

          (c)  of any reclassification of Common Stock (other than a subdivision
or combination of the outstanding shares of Common Stock), or of any
consolidation, merger or share exchange to which the Borrower is a party and for
which approval of any shareholders of the Borrower is required, or of the sale
or transfer of all or substantially all of the assets of the Borrower; or

          (d)  of the voluntary or involuntary dissolution, liquidation or
winding up of the Borrower;

then the Borrower shall cause to be delivered to the Holder at its address set
forth in the Register, at least 20 days (or 10 days in any case specified in
clause (a), (b) or (c) above) prior to the applicable record or effective date
hereinafter specified, a notice stating (x) the date on which a record is to be
taken for the purpose of such dividend, distribution or granting of rights or
warrants, or, if a record is not to be taken, the date as of which the holders
of Common Stock of record who will be entitled to such dividend, distribution,
rights or warrants are to be determined or (y) the date on which such
reclassification, consolidation, merger, share exchange, sale, transfer,
dissolution, liquidation or winding up is expected to become effective, and the
date as of which it is expected that holders of Common Stock of record shall be
entitled to exchange their shares of Common Stock for securities, cash or other
property deliverable upon such reclassification, consolidation, merger, share
exchange, sale, transfer, dissolution, liquidation or winding up.  Neither the
failure to give any such notice nor any defect therein shall affect the legality
or validity of any action described in clauses (a) through (d) of this Section.

     Section 7.6    BORROWER TO RESERVE COMMON STOCK.  The Borrower shall at all
times reserve and keep available, free from preemptive rights, out of the
authorized but unissued Common Stock or out of the Common Stock held in
treasury, for the purpose of effecting the conversion of this Note, the full
number of shares of Common Stock then issuable upon the conversion of all
outstanding Notes.

     Section 7.7    TAXES ON CONVERSIONS.  The Borrower will pay any and all
original issuance, transfer, stamp and other similar taxes that may be payable
in respect of the issue or delivery of shares of Common Stock on conversion of
this Note pursuant hereto.  The Issuer shall not, however, be required to pay
any tax that may be payable in respect of any transfer involved in the issue and
delivery of shares of Common Stock in a name other than that of the Holder of
this Note to be converted, and no such issue or delivery shall be made unless
and until the Person requesting such issue has paid to the Borrower the amount
of any such tax or has established to the satisfaction of the Borrower that such
tax has been paid.


                                      -12-

<PAGE>

     Section 7.8    COVENANT AS TO COMMON STOCK.  The Borrower covenants with
the Holder that all shares of Common Stock that may be issued upon conversion of
this Note will, upon issue, be validly issued, fully paid and nonassessable.

     Section 7.9    PROVISIONS AS TO CONSOLIDATION, MERGER OR SALE OF ASSETS. 
In case of any consolidation of the Borrower with, or merger of the Borrower
into, any other Person, any merger of another Person into the Borrower (other
than a merger that does not result in any reclassification, conversion, exchange
or cancellation of outstanding shares of Common Stock) or any sale or transfer
of all or substantially all of the assets of the Borrower, the Person formed by
such consolidation or resulting from such merger or that acquires such assets,
as the case may be, shall execute and deliver to the Holder a supplemental
instrument providing that the Holder of this Note shall have the right
thereafter to convert such Note only into the kind and amount of securities,
cash and other property, if any, receivable upon such consolidation, merger,
sale or transfer by a holder of the number of shares of Common Stock into which
this Note might have been converted immediately prior to such consolidation,
merger, sale or transfer, assuming such holder of Common Stock (i) is not a
Person with which the Borrower consolidated or into which the Borrower merged or
that merged into the Borrower or to which such sale or transfer was made, as the
case may be (a "CONSTITUENT PERSON"), or an Affiliate of a Constituent Person
and (ii) failed to exercise his rights of election, if any, as to the kind or
amount of securities, cash and other property receivable upon such
consolidation, merger, sale or transfer; PROVIDED that, if the kind or amount of
securities, cash and other property receivable upon such consolidation, merger,
sale or transfer is not the same for each share of Common Stock held immediately
prior to such consolidation, merger, sale or transfer by other than a
Constituent Person or an Affiliate thereof and in respect of which such rights
of election shall not have been exercised ("NONELECTING SHARE"), then for the
purpose of this Section the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, sale or transfer by each
nonelecting share shall be deemed to be the kind and amount so receivable per
share by a plurality of the nonelecting shares.  Such supplemental instrument
shall provide for adjustments, which, for events subsequent to the effective
date of such supplemental instrument, shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Article.  The above
provisions of this Section shall similarly apply to successive consolidations,
mergers, sales or transfers.

     Article 8.     MISCELLANEOUS.

     Section 8.1    GOVERNING LAW.  THIS NOTE SHALL BE DEEMED TO BE A CONTRACT
UNDER THE LAWS OF THE STATE OF DELAWARE AND FOR ALL PURPOSES SHALL BE CONSTRUED
IN ACCORDANCE WITH THE LAWS OF SAID STATE, EXCEPT AS MAY OTHERWISE BE REQUIRED
BY MANDATORY PROVISIONS OF LAW.  THE PARTIES HERETO HEREBY WAIVE PRESENTMENT,
DEMAND, NOTICE, PROTEST AND ALL OTHER DEMANDS AND NOTICES IN CONNECTION WITH THE
DELIVERY, ACCEPTANCE, PERFORMANCE AND ENFORCEMENT OF THIS NOTE, EXCEPT AS
SPECIFICALLY PROVIDED HEREIN.  THE HOLDER OF THIS NOTE BY ACCEPTANCE HEREOF
AGREES TO BE BOUND BY THE PROVISIONS OF THE NOTE WHICH ARE EXPRESSLY BINDING ON
THE HOLDER.  THE SECTION HEADINGS HEREIN ARE FOR CONVENIENCE ONLY AND SHALL NOT
AFFECT THE CONSTRUCTION HEREOF.

     Section 8.2    AMENDMENT OR MODIFICATION.  Any provision of this Note may
be amended or, subject to Section 5.3, waived with the written consent of the
Issuers and the Holder.


                                      -13-

<PAGE>

     Section 8.3    TRANSFERS AND ASSIGNMENTS. This Note and any securities
issued upon conversion of this Note may not be sold, transferred, pledged,
hypothecated or otherwise disposed of unless and until:

          (i)       There is then in effect a registration statement under the
     Securities Act covering such proposed disposition and such disposition is
     made in accordance with such registration statement and all applicable
     state securities laws; or

          (ii)      (A)  The transferor shall have notified the Borrower of the
     proposed disposition and shall have furnished the Borrower with a statement
     of the circumstances surrounding the proposed disposition, and with an
     opinion of counsel, reasonably satisfactory to the Borrower, that such
     disposition will not require registration of the Note, or such securities
     under the Securities Act and that all requisite action has been or will, on
     a timely basis, be taken under any applicable state securities laws in
     connection with such disposition; and

          (iii)     The proposed transferee shall have agreed in writing to be
     bound by the terms and provisions of this Section 8.

     Notwithstanding the provisions of paragraphs (i) and (ii) above, no such
registration statement or opinion of counsel shall be necessary for transfers
pursuant to Rule 144 (k) promulgated under the Securities Act.


                                      -14-

<PAGE>

     IN WITNESS WHEREOF, each of the Borrower and the Holder has caused this
Note to be duly executed under its corporate seal.

Dated:  June 27, 1996

[Seal]                             ADVANCED RADIO TECHNOLOGIES CORPORATION



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



[Seal]                        COLUMBIA CAPITAL CORPORATION




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


                                      -15-
 

<PAGE>

                                                               EXHIBIT 10-31(d)

Void after July 3, 1999

         This Warrant and any shares acquired upon the exercise of this
         Warrant have not been registered under the Securities Act of
         1933.  This Warrant and such shares may not be sold or
         transferred in the absence of such registration or an exemption
         therefrom under said Act.  This Warrant and such shares may not
         be transferred except upon the conditions specified in this
         Warrant and no transfer of this Warrant or such shares shall be
         valid or effective unless and until such conditions shall have
         been complied with.

         The Securities represented by this Certificate have been acquired
         for investment and have not been registered under the Securities
         Act of 1933.  These Securities may not be sold or transferred in
         the absence of such Registration or an exemption therefrom under
         such Act. Additionally, the transfer of these Securities is
         subject to the conditions specified in Section 12 of the Second
         Amended and Restated Registration Rights Agreement dated the date
         hereof (the "Registration Rights Agreement") among Advanced Radio
         Telecom Corp., Advanced Radio Technologies Corporation and
         certain other signatories thereto and no transfer of these
         Securities shall be valid or effective until such conditions have
         been fulfilled.  Upon the fulfillment of certain of such
         conditions, Advanced Radio Telecom Corp. and Advanced Radio
         Technologies Corporation have agreed to deliver to the holder
         hereof a new certificate, not bearing this legend, for the
         Securities represented hereby registered in the name of such
         holder.  Copies of such Agreement may be obtained at no cost by
         written request made by the holder of record of this Certificate
         to the Secretary of Advanced Radio Technologies Corporation.

                       ADVANCED RADIO TECHNOLOGIES CORPORATION

                            COMMON STOCK PURCHASE WARRANT

    ADVANCED RADIO TECHNOLOGIES CORPORATION, a Delaware corporation (the
"Company"), having its principal office at 500 108th Ave., N.E., Bellevue, WA
98004, hereby certifies that, for value received, Commco, L.L.C.,  a Delaware
limited liability company, or assigns, is entitled, subject to the terms set
forth below, to purchase from the Company at any time on or from time to time
after July 3, 1999 and before 5:00 P.M., New York City time, on July 3, 1999
(the "Expiration Date") 23,285 fully paid and non-assessable shares of Common
Stock of the Company, at the price per share (the "Purchase Price") of $15.00.
The number and character of such shares of Common Stock and the Purchase Price
are subject to adjustment as provided herein.

<PAGE>

    This Warrant was originally issued by the Company in connection with the
transactions contemplated by the Asset Acquisition Agreement and Plan of
Reorganization dated the date hereof among the Company, CommcoCCC, Inc.,
Columbia Capital Corporation, CCC Millimeter, L.P., Columbia Millimeter
Communications, L.P., Commco, L.L.C. and Advanced Radio Telecom Corp. (the
"Asset Acquisition Agreement").  In order to induce the holder hereof to provide
the commitment set forth in the Bridge Note Due September __, 1996, the Company
has agreed to grant the holder the rights set forth in this Warrant.  This
Warrant shall continue in full force and effect regardless of any termination or
breach of the Asset Acquisition Agreement.

    As used herein the following terms, unless the context otherwise requires,
have the following respective meanings:

         (a)  The term "Company" includes any corporation which shall succeed
to or assume the obligations of the Company hereunder.

         (b)  The term "Common Stock" means the Common Stock, $.001 par value
per share, of the Company and its successors, assuming the proposed 29,450.16
for 1 stock split (the "Proposed Stock Split") of the Company's Common Stock has
been effected; provided that until the Proposed Stock Split is effected, this
Warrant may be exercised to purchase the number of shares of Common Stock equal
to the number of shares set forth in this in the first paragraph hereof divided
by 29,450.16 and the Purchase Price shall be $441,752.40, subject to adjustment
as provided herein.

         (c)  The "Original Issue Date" is July 3, 1996, the date as of which
the Warrants were first issued.

         (d)  The term "Other Securities" refers to any stock (other than
Common Stock) and other securities of the Company or any other person (corporate
or otherwise) which the holders of the Warrants at any time shall be entitled to
receive, or shall have received, upon the exercise of the Warrants, in lieu of
or in addition to Common Stock, or which at any time shall be issuable or shall
have been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to section 6 or otherwise.

         (e)  The term "Purchase Price" shall be the then applicable exercise
price for one share of Common Stock.

         (f)  The terms "registered" and "registration" refer to a registration
effected by filing a registration statement in compliance with the Securities
Act, to permit the disposition of Common Stock (or Other Securities) issued or
issuable upon the exercise of Warrants, and any post-effective amendments and
supplements filed or required to be filed to permit any such disposition.


                                         -2-

<PAGE>

         (g)  The term "Securities Act" means the Securities Act of 1933 as the
same shall be in effect at the time.

    1.   REGISTRATION, ETC. The Company shall have the same obligations to the
holder of the Warrant as it has to the Investor Telecom Stockholders and
Acquisition Holders of the Company as set forth in that certain Second Restated
and Amended Registration Rights Agreement by and among the Company, the
stockholders of the Company named therein, Advanced Radio Telecom Corp.
("Telecom") and the stockholders of Telecom named therein.

    2.   SALE OR EXERCISE WITHOUT REGISTRATION.  If, at the time of any
exercise, transfer or surrender for exchange of a Warrant or of Common Stock (or
Other Securities) previously issued upon the exercise of Warrants, such Warrant
or Common Stock (or Other Securities) shall not be registered under the
Securities Act, the Company may require, as a condition of allowing such
exercise, transfer or exchange, that the holder or transferee of such Warrant or
Common Stock (or Other Securities), as the case may be, furnish to the Company a
satisfactory opinion of counsel to the effect that such exercise, transfer or
exchange may be made without registration under the Securities Act, provided
that the disposition thereof shall be in compliance with the provisions of the
Stockholders Agreement, and provided further that nothing contained in this
Section 2 shall relieve the Company from complying with any request for
registration pursuant to Section 1 hereof.

    3.   EXERCISE OF WARRANT; PARTIAL EXERCISE; CASHLESS EXERCISE.

         3.1  EXERCISE IN FULL.  Subject to the provisions hereof, this Warrant
may be exercised in full by the holder hereof by surrender of this Warrant, with
the form of subscription attached hereto as SCHEDULE I duly executed by such
holder, to the Company at its principal office accompanied by payment, in cash
or by certified or official bank check payable to the order of the Company, in
the amount obtained by multiplying the number of shares of Common Stock called
for on the face of this Warrant (without giving effect to any adjustment
therein) by the Purchase Price.

         3.2  PARTIAL EXERCISE.  Subject to the provisions hereof, this Warrant
may be exercised in part by surrender of this Warrant in the manner and at the
place provided in Section 3.1 except that the amount payable by the holder upon
any partial exercise shall be the amount obtained by multiplying (a) the number
of shares of Common Stock (without giving effect to any adjustment therein)
designated by the holder in the subscription at the end hereof by (b) the
Purchase Price.  Upon any such partial exercise, the Company at its expense will
forthwith issue and deliver to or upon the order of the holder hereof a new
Warrant or Warrants of like tenor, in the name of the holder hereof or as such
holder (upon payment by such holder of any applicable transfer taxes) may
request, calling in the aggregate on the face or faces thereof for the number of
shares of Common Stock equal (without giving effect to any adjustment therein)
to the number of such shares called for on the face of this Warrant minus the
number of such shares designated by the holder in the subscription at the end
hereof.


                                         -3-

<PAGE>

         3.3  EXERCISE BY SURRENDER OF WARRANT.  In addition to the method of
payment set forth in Sections 3.1 and 3.2 and in lieu of any cash payment
required thereunder, the holder(s) of the Warrants shall have the right at any
time and from time to time to exercise the Warrants in full or in part by
surrendering the Warrant Certificate in the manner specified in Section 3.1 as
payment of the aggregate Purchase Price.  The number of Warrants to be
surrendered in payment of the aggregate Exercise Price for the Warrants to be
exercised shall be determined by multiplying the number of Warrants to be
exercised by the Purchase Price, and then dividing the product thereof by an
amount equal to the Market Price (as defined below).  Solely for the purposes of
this paragraph, Market Price shall be calculated as the average of the Market
Prices for each of the ten (10) trading days preceding the date which the form
of election attached hereto is deemed to have been sent to the Company ("Notice
Date").

         3.4  DEFINITION OF MARKET PRICE.  As used herein, the phrase "Market
Price" at any date shall be deemed to be (i) if the principal trading market for
such securities is an exchange, the last reported sale price, or, in case no
such reported sale takes place on such date, the average of the last reported
sale prices for the last three (3) trading days, in either case as officially
reported on any consolidated tape, (ii) if the principal market for such
securities is the over-the-counter market, the high bid price on such date as
set forth by Nasdaq or, if the security is not quoted on Nasdaq, the high bid
price as set forth in the National Quotation Bureau sheet listing such
securities for such day.  Notwithstanding the foregoing, if there is no reported
closing price or high bid price, as the case may be, on the date next preceding
the event requiring an adjustment hereunder, then the Market Price shall be
determined as of the latest date prior to such day for which such closing price
or high bid price is available, or if the securities are not quoted on Nasdaq,
as determined in good faith by resolution of the Board of Directors of the
Company, based on the best information available to it.

         3.5  COMPANY TO REAFFIRM OBLIGATIONS.  The Company will, at the time
of any exercise of this Warrant, upon the request of the holder hereof,
acknowledge in writing its continuing obligation to afford to such holder any
rights (including, without limitation, any right to registration of the shares
of Common Stock or Other Securities issued upon such exercise) to which such
holder shall continue to be entitled after such exercise in accordance with the
provisions of this Warrant, PROVIDED that if the holder of this Warrant shall
fail to make any such request, such failure shall not affect the continuing
obligation of the Company to afford such holder any such rights.

    4.   DELIVERY OF STOCK CERTIFICATES, ETC. ON EXERCISE.  As soon as
practicable after the exercise of this Warrant in full or in part, and in any
event within 10 days thereafter, the Company at its expense (including the
payment by it of any applicable issue taxes) will cause to be issued in the name
of and delivered to the holder hereof, or as such holder (upon payment by such
holder of any applicable transfer taxes) may direct, a certificate or
certificates for the number of fully paid and non-assessable shares of Common
Stock (or Other


                                         -4-

<PAGE>

Securities) to which such holder shall be entitled upon such exercise, plus, in
lieu of any fractional share to which such holder would otherwise be entitled,
cash equal to such fraction multiplied by the then current market value of one
full share, together with any other stock or other securities and property
(including cash, where applicable) to which such holder is entitled upon such
exercise pursuant to Section 5 or otherwise.

    5.   ADJUSTMENT FOR DIVIDENDS IN OTHER STOCK, PROPERTY, ETC.;
RECLASSIFICATION, ETC. In case at any time or from time to time after the
Original Issue Date the holders of Common Stock (or Other Securities) shall have
received, or (on or after the record date fixed for the determination of
stockholders eligible to receive) shall have become entitled to receive, without
payment therefor

              (a)  other or additional stock or other securities or property
    (other than cash) by way of dividend, or

              (b)  any cash paid or payable (including, without limitation, by
    way of dividend), except out of earned surplus of the Company, or

              (c)  other or additional (or less) stock or other securities or
    property (including cash) by way of spin-off, split-up, reclassification,
    recapitalization, combination of shares or similar corporate rearrangement,

then, and in each such case, the holder of this Warrant, upon the exercise
hereof as provided in Section 3, shall be entitled to receive the amount of
stock and other securities and property (including cash in the cases referred to
in subdivisions (b) and (c) of this Section 5 which such holder would hold on
the date of such exercise if on the Original Issue Date he had been the holder
of record of the number of shares of Common Stock called for on the face of this
Warrant and had thereafter, during the period from the Original Issue Date to
and including the date of such exercise, retained such shares and all such other
or additional (or less) stock and other securities and property (including cash
in the cases referred to in subdivisions (b) and (c) of this Section 5)
receivable by him as aforesaid during such period, giving effect to all
adjustments called for during such period by Section 6.  Notwithstanding
anything to the contrary contained in this Warrant, including this Section 5, no
adjustment shall be made to the number of shares of Common Stock recited in the
first paragraph hereof issuable upon exercise hereof as a result of the Proposed
Stock Split.

    6.   REORGANIZATION, CONSOLIDATION, MERGER, ETC.  In case the Company after
the Original Issue Date shall (a) effect a reorganization, (b) consolidate with
or merge into any other person, or (c) transfer all or substantially all of its
properties or assets to any other person under any plan or arrangement
contemplating the dissolution of the Company, then, in each such case, the
holder of this Warrant, upon the exercise hereof as provided in Section 3 at any
time after the consummation of such reorganization, consolidation or merger or
the effective date of such dissolution, as the case may be, shall be entitled to
receive (and the


                                         -5-

<PAGE>

Company shall be entitled to deliver), in lieu of the Common Stock (or Other
Securities) issuable upon such exercise prior to such consummation or such
effective date, the stock and other securities and property (including cash) to
which such holder would have been entitled upon such consummation or in
connection with such dissolution, as the case may be, if such holder had so
exercised this Warrant immediately prior thereto, all subject to further
adjustment thereafter as provided in Section 5 hereof.

    7.   CERTAIN EVENTS.  If any event occurs of the nature contemplated by the
provisions of Sections 5 or 6 hereof but not expressly provided for by such
provisions, then the Company's board of directors shall make an appropriate
adjustment in the amount of stock or other securities to which the holder hereof
shall be entitled to receive upon exercise hereof so as to protect the rights of
the holder.

    8.   FURTHER ASSURANCES.  The Company will take all such action as may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and non-assessable shares of stock upon the exercise of all Warrants
from time to time outstanding.

    9.   ACCOUNTANTS' CERTIFICATE AS TO ADJUSTMENTS.  In each case of any
adjustment or readjustment in the shares of Common Stock (or Other Securities)
issuable upon the exercise of the Warrants, the Company at its expense will
promptly cause the Company's regularly retained auditor to compute such
adjustment or readjustment in accordance with the terms of the Warrants and
prepare a certificate setting forth such adjustment or readjustment and showing
in detail the facts upon which such adjustment or readjustment is based, and the
number of shares of Common Stock outstanding or deemed to be outstanding.  The
Company will forthwith mail a copy of each such certificate to each holder of a
Warrant.

    10.  NOTICES OF RECORD DATE, ETC.  In the event of

              (a)  any taking by the Company of a record of the holders of any
    class of securities for the purpose of determining the holders thereof who
    are entitled to receive any dividend (other than a cash dividend payable
    out of earned surplus of the Company) or other distribution, or any right
    to subscribe for, purchase or otherwise acquire any shares of stock of any
    class or any other securities or property, or to receive any other right,
    or

              (b)  any capital reorganization of the Company, any
    reclassification or recapitalization of the capital stock of the Company or
    any transfer of all or substantially all the assets of the Company to or
    consolidation or merger of the Company with or into any other person, or

              (c)  any voluntary or involuntary dissolution, liquidation or
    winding-up of the Company, or


                                         -6-

<PAGE>

              (d)  any proposed issue or grant by the Company of any shares of
    stock of any class or any other securities, or any right or option to
    subscribe for, purchase or otherwise acquire any shares of stock of any
    class or any other securities (other than the issue of Common Stock on the
    exercise of the Warrants), then and in each such event the Company will
    mail or cause to be mailed to each holder of a Warrant a notice specifying
    (i) the date on which any such record is to be taken for the purpose of
    such dividend, distribution or right, and stating the amount and character
    of such dividend, distribution or right, (ii) the date on which any such
    reorganization, reclassification, recapitalization, transfer,
    consolidation, merger, dissolution, liquidation or winding-up is to take
    place, and the time, if any, as of which the holders of record of Common
    Stock (or Other Securities) shall be entitled to exchange their shares of
    Common Stock (or Other Securities) for securities or other property
    deliverable upon such reorganization, reclassification, recapitalization,
    transfer, consolidation, merger, dissolution, liquidation or winding-up,
    and (iii) the amount and character of any stock or other securities, or
    rights or options with respect thereto, proposed to be issued or granted,
    the date of such proposed issue or grant [and the persons or class of
    persons to whom such proposed issue or grant] and the persons or class of
    persons to whom such proposed issue or grant is to be offered or made.
    Such notice shall be mailed at least 20 days prior to the date therein
    specified.

    11.  RESERVATION OF STOCK, ETC. ISSUABLE ON EXERCISE OF WARRANTS.  The
Company will at all times reserve and keep available, solely for issuance and
delivery upon the exercise of the Warrants, all shares of Common Stock (or Other
Securities) from time to time issuable upon the exercise of the Warrants.

    12.  LISTING ON SECURITIES EXCHANGES; REGISTRATION.  If the Company at any
time shall list any Common Stock on any national securities exchange and shall
register such Common Stock under the Securities Exchange Act of 1934 (as then in
effect, or any similar statute then in effect), the Company will, at its
expense, simultaneously list on such exchange, upon official notice of issuance
upon the exercise of the Warrants, and maintain such listing of all shares of
Common Stock from time to time issuable upon the exercise of the Warrants; and
the Company will so list on any national securities exchange, will so register
and will maintain such listing of, any Other Securities if and at the time that
any securities of like class or similar type shall be listed on such national
securities exchange by the Company.

    13.  EXCHANGE OF WARRANTS.  Subject to the provisions of Section 2 hereof,
upon surrender for exchange of any Warrant, properly endorsed, to the Company,
the Company at its own expense will issue and deliver to or upon the order of
the holder thereof a new Warrant or Warrants of like tenor, in the name of such
holder or as such holder (upon payment by such holder of any applicable transfer
taxes) may direct, calling in the aggregate on the face or faces thereof for the
number of shares of Common Stock called for on the face or faces of the Warrant
or Warrants so surrendered.


                                         -7-

<PAGE>

    14.  REPLACEMENT OF WARRANTS.  Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of any
Warrant and, in the case of any such loss, theft or destruction, upon delivery
of an indemnity agreement reasonably satisfactory in form and amount to the
Company or, in the case of any such mutilation, upon surrender and cancellation
of such Warrant, the Company at its expense will execute and deliver, in lieu
thereof, a new Warrant of like tenor.

    15.  WARRANT AGENT.  The Company may, by written notice to each holder of a
Warrant, appoint an agent having an office in New York, New York, for the
purpose of issuing Common Stock (or Other Securities) upon the exercise of the
Warrants pursuant to Section 3, exchanging Warrants pursuant to Section 13, and
replacing Warrants pursuant to Section 14, or any of the foregoing, and
thereafter any such issuance, exchange or replacement, as the case may be, shall
be made at such office by such agent.

    16.  REMEDIES.  The Company stipulates that the remedies at law of the
holder of this Warrant in the event of any default or threatened default by the
Company in the performance of or compliance with any of the terms of this
Warrant are not and will not be adequate, and that such terms may be
specifically enforced by a decree for the specific performance of any agreement
contained herein or by an injunction against a violation of any of the terms
hereof or otherwise.

    17.  NEGOTIABILITY, ETC.  This Warrant is issued upon the following terms,
to all of which each holder or owner hereof by the taking hereof consents and
agrees:

              (a)  subject to the provisions hereof, title to this Warrant may
    be transferred by endorsement (by the holder hereof executing the form of
    assignment attached hereto as SCHEDULE II) and delivery in the same manner
    as in the case of a negotiable instrument transferable by endorsement and
    delivery;

              (b)  subject to the foregoing, any person in possession of this
    Warrant properly endorsed is authorized to represent himself as absolute
    owner hereof and is empowered to transfer absolute title hereto by
    endorsement and delivery hereof to a bona fide purchaser hereof for value;
    each prior taker or owner waives and renounces all of his equities or
    rights in this Warrant in favor of each such bona fide purchaser and each
    such bona fide purchaser shall acquire absolute title hereto and to all
    rights represented hereby; and

              (c)  until this Warrant is transferred on the books of the
    Company, the Company may treat the registered holder hereof as the absolute
    owner hereof for all purposes, notwithstanding any notice to the contrary.


                                         -8-

<PAGE>

    18.  NOTICES, ETC.  All notices and other communications from the Company
to the holder of this Warrant shall be mailed by first class registered or
certified mail, postage prepaid, at such address as may have been furnished to
the Company in writing by such holder, or, until an address is so furnished, to
and at the address of the last holder of this Warrant who has so furnished an
address to the Company.

    19.  MISCELLANEOUS.  This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.  This Warrant is being delivered in the State of New York and shall
be construed and enforced in accordance with and governed by the laws of such
State.  The headings in this Warrant are for purposes of reference only, and
shall not limit or otherwise affect any of the terms hereof.

    20.  ASSIGNABILITY.  Subject to the transfer conditions referred to in the
legend endorsed hereon, this Warrant is fully assignable at any time upon
surrender of this Warrant with a properly executed Assignment (in the form of
SCHEDULE II hereto) at the principal office of the Company.

                                       ADVANCED RADIO TECHNOLOGIES
                                       CORPORATION


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


[Corporate Seal]

Attest:


- -------------------------
    Secretary


                                         -9-

<PAGE>
                                      SCHEDULE I

                                 FORM OF SUBSCRIPTION

                     (To be signed only upon exercise of Warrant)


To: ADVANCED RADIO TECHNOLOGIES CORPORATION


    The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder,  * shares of Common Stock of ADVANCED RADIO TECHNOLOGIES
CORPORATION, and herewith makes payment of
$                  therefor, and requests that the certificates for such shares
be issued in the name of, and delivered to,
  , whose address is


Dated:

                                  ---------------------------------------------
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of
                                  the Warrant)


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

- ---------------------------------------------
*   Insert here the number of shares called for on the face of the Warrant (or,
    in the case of a partial exercise, the portion thereof as to which the
    Warrant is being exercised), in either case without making any adjustment
    for additional Common Stock or any other stock or other securities or
    property or cash which, pursuant to the adjustment provisions of the
    Warrant, may be deliverable upon exercise.


                                         -10-

<PAGE>

                                     SCHEDULE II

                                  FORM OF ASSIGNMENT

                     (To be signed only upon transfer of Warrant)



    For value received, the undersigned hereby sells, assigns and transfers
unto
                                         the right represented by the within
Warrant to purchase shares of Common Stock of [____________________] to which
the within Warrant relates, and appoints
Attorney to transfer such right on the books of [_________________] with full
power of substitution in the premises.  The Warrant being transferred hereby is
one of an aggregate of [______________] Common Stock Purchase Warrants issued by
[________________________] as of [_______________], 19__.


Dated:

                                  ---------------------------------------------
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of
                                  the Warrant)

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


- ---------------------------------------------
Signature guaranteed by a Bank or
Trust Company having its principal
office in New York City or by a
Member Firm of the New York or
+American Stock Exchange


                                         -11-


<PAGE>

                                                               EXHIBIT 10-31(e)

Void after July 3, 1999

          This Warrant and any shares acquired upon the exercise of this
          Warrant have not been registered under the Securities Act of
          1933.  This Warrant and such shares may not be sold or
          transferred in the absence of such registration or an exemption
          therefrom under said Act.  This Warrant and such shares may not
          be transferred except upon the conditions specified in this
          Warrant and no transfer of this Warrant or such shares shall be
          valid or effective unless and until such conditions shall have
          been complied with.

          The Securities represented by this Certificate have been acquired
          for investment and have not been registered under the Securities
          Act of 1933.  These Securities may not be sold or transferred in
          the absence of such Registration or an exemption therefrom under
          such Act. Additionally, the transfer of these Securities is
          subject to the conditions specified in Section 12 of the Second
          Amended and Restated Registration Rights Agreement dated the date
          hereof (the "Registration Rights Agreement") among Advanced Radio
          Telecom Corp., Advanced Radio Technologies Corporation and
          certain other signatories thereto and no transfer of these
          Securities shall be valid or effective until such conditions have
          been fulfilled.  Upon the fulfillment of certain of such
          conditions, Advanced Radio Telecom Corp. and Advanced Radio
          Technologies Corporation have agreed to deliver to the holder
          hereof a new certificate, not bearing this legend, for the
          Securities represented hereby registered in the name of such
          holder.  Copies of such Agreement may be obtained at no cost by
          written request made by the holder of record of this Certificate
          to the Secretary of Advanced Radio Technologies Corporation.

                       ADVANCED RADIO TECHNOLOGIES CORPORATION

                            COMMON STOCK PURCHASE WARRANT

     ADVANCED RADIO TECHNOLOGIES CORPORATION, a Delaware corporation (the
"Company"), having its principal office at 500 108th Ave., N.E., Bellevue, WA
98004, hereby certifies that, for value received, Columbia Capital Corporation,
a Virginia corporation, or assigns, is entitled, subject to the terms set forth
below, to purchase from the Company at any time on or from time to time after
July 3, 1996 and before 5:00 P.M., New York City time, on July 3, 1999 (the
"Expiration Date") 26,715 fully paid and non-assessable shares of Common Stock
of the Company, at the price per share (the "Purchase Price") of $15.00.    The
number and character of such shares of Common Stock and the Purchase Price are
subject to adjustment as provided herein.

<PAGE>

     This Warrant was originally issued by the Company in connection with the
transactions contemplated by the Asset Acquisition Agreement and Plan of
Reorganization dated the date hereof among the Company, CommcoCCC, Inc.,
Columbia Capital Corporation, CCC Millimeter, L.P., Columbia Millimeter
Communications, L.P., Commco, L.L.C. and Advanced Radio Telecom Corp. (the
"Asset Acquisition Agreement").  In order to induce the holder hereof to provide
the commitment set forth in the Bridge Note Due September 30, 1996, the Company
has agreed to grant the holder the rights set forth in this Warrant.  This
Warrant shall continue in full force and effect regardless of any termination or
breach of the Asset Acquisition Agreement.

     As used herein the following terms, unless the context otherwise requires,
have the following respective meanings:

          (a)     The term "Company" includes any corporation which shall
succeed to or assume the obligations of the Company hereunder.

          (b)     The term "Common Stock" means the Common Stock, $.001 par
value per share, of the Company and its successors, assuming the proposed
29,450.16 for 1 stock split (the "Proposed Stock Split") of the Company's Common
Stock has been effected; provided that until the Proposed Stock Split is
effected, this Warrant may be exercised to purchase the number of shares of
Common Stock equal to the number of shares set forth in this in the first
paragraph hereof divided by 29,450.16 and the Purchase Price shall be
$441,752.40, subject to adjustment as provided herein.

          (c)     The "Original Issue Date" is July 3, 1996, the date as of
which the Warrants were first issued.

          (d)     The term "Other Securities" refers to any stock (other than
Common Stock) and other securities of the Company or any other person (corporate
or otherwise) which the holders of the Warrants at any time shall be entitled to
receive, or shall have received, upon the exercise of the Warrants, in lieu of
or in addition to Common Stock, or which at any time shall be issuable or shall
have been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to section 6 or otherwise.

          (e)     The term "Purchase Price" shall be the then applicable
exercise price for one share of Common Stock.

          (f)     The terms "registered" and "registration" refer to a
registration effected by filing a registration statement in compliance with the
Securities Act, to permit the disposition of Common Stock (or Other Securities)
issued or issuable upon the exercise of Warrants, and any post-effective
amendments and supplements filed or required to be filed to permit any such
disposition.


                                         -2-

<PAGE>

          (g)     The term "Securities Act" means the Securities Act of 1933 as
the same shall be in effect at the time.

     1.   REGISTRATION, ETC. The Company shall have the same obligations to the
holder of the Warrant as it has to the Investor Telecom Stockholders and
Acquisition Holders of the Company as set forth in that certain Second Restated
and Amended Registration Rights Agreement by and among the Company, the
stockholders of the Company named therein, Advanced Radio Telecom Corp.
("Telecom") and the stockholders of Telecom named therein.

     2.   SALE OR EXERCISE WITHOUT REGISTRATION.  If, at the time of any
exercise, transfer or surrender for exchange of a Warrant or of Common Stock (or
Other Securities) previously issued upon the exercise of Warrants, such Warrant
or Common Stock (or Other Securities) shall not be registered under the
Securities Act, the Company may require, as a condition of allowing such
exercise, transfer or exchange, that the holder or transferee of such Warrant or
Common Stock (or Other Securities), as the case may be, furnish to the Company a
satisfactory opinion of counsel to the effect that such exercise, transfer or
exchange may be made without registration under the Securities Act, provided
that the disposition thereof shall be in compliance with the provisions of the
Stockholders Agreement, and provided further that nothing contained in this
Section 2 shall relieve the Company from complying with any request for
registration pursuant to Section 1 hereof.

     3.   EXERCISE OF WARRANT; PARTIAL EXERCISE; CASHLESS EXERCISE.

          3.1.    EXERCISE IN FULL.  Subject to the provisions hereof, this
Warrant may be exercised in full by the holder hereof by surrender of this
Warrant, with the form of subscription attached hereto as SCHEDULE I duly
executed by such holder, to the Company at its principal office accompanied by
payment, in cash or by certified or official bank check payable to the order of
the Company, in the amount obtained by multiplying the number of shares of
Common Stock called for on the face of this Warrant (without giving effect to
any adjustment therein) by the Purchase Price.

          3.2.    PARTIAL EXERCISE.  Subject to the provisions hereof, this
Warrant may be exercised in part by surrender of this Warrant in the manner and
at the place provided in Section 3.1 except that the amount payable by the
holder upon any partial exercise shall be the amount obtained by multiplying (a)
the number of shares of Common Stock (without giving effect to any adjustment
therein) designated by the holder in the subscription at the end hereof by (b)
the Purchase Price.  Upon any such partial exercise, the Company at its expense
will forthwith issue and deliver to or upon the order of the holder hereof a new
Warrant or Warrants of like tenor, in the name of the holder hereof or as such
holder (upon payment by such holder of any applicable transfer taxes) may
request, calling in the aggregate on the face or faces thereof for the number of
shares of Common Stock equal (without giving effect to any adjustment therein)
to the number of such shares called for on the face of this Warrant minus the
number of such shares designated by the holder in the subscription at the end
hereof.


                                         -3-

<PAGE>

          3.3.    EXERCISE BY SURRENDER OF WARRANT.  In addition to the method
of payment set forth in Sections 3.1 and 3.2 and in lieu of any cash payment
required thereunder, the holder(s) of the Warrants shall have the right at any
time and from time to time to exercise the Warrants in full or in part by
surrendering the Warrant Certificate in the manner specified in Section 3.1 as
payment of the aggregate Purchase Price.  The number of Warrants to be
surrendered in payment of the aggregate Exercise Price for the Warrants to be
exercised shall be determined by multiplying the number of Warrants to be
exercised by the Purchase Price, and then dividing the product thereof by an
amount equal to the Market Price (as defined below).  Solely for the purposes of
this paragraph, Market Price shall be calculated as the average of the Market
Prices for each of the ten (10) trading days preceding the date which the form
of election attached hereto is deemed to have been sent to the Company ("Notice
Date").

          3.4.    DEFINITION OF MARKET PRICE.  As used herein, the phrase
"Market Price" at any date shall be deemed to be (i) if the principal trading
market for such securities is an exchange, the last reported sale price, or, in
case no such reported sale takes place on such date, the average of the last
reported sale prices for the last three (3) trading days, in either case as
officially reported on any consolidated tape, (ii) if the principal market for
such securities is the over-the-counter market, the high bid price on such date
as set forth by Nasdaq or, if the security is not quoted on Nasdaq, the high bid
price as set forth in the National Quotation Bureau sheet listing such
securities for such day.  Notwithstanding the foregoing, if there is no reported
closing price or high bid price, as the case may be, on the date next preceding
the event requiring an adjustment hereunder, then the Market Price shall be
determined as of the latest date prior to such day for which such closing price
or high bid price is available, or if the securities are not quoted on Nasdaq,
as determined in good faith by resolution of the Board of Directors of the
Company, based on the best information available to it.

          3.5.    COMPANY TO REAFFIRM OBLIGATIONS.  The Company will, at the
time of any exercise of this Warrant, upon the request of the holder hereof,
acknowledge in writing its continuing obligation to afford to such holder any
rights (including, without limitation, any right to registration of the shares
of Common Stock or Other Securities issued upon such exercise) to which such
holder shall continue to be entitled after such exercise in accordance with the
provisions of this Warrant, PROVIDED that if the holder of this Warrant shall
fail to make any such request, such failure shall not affect the continuing
obligation of the Company to afford such holder any such rights.

     4.   DELIVERY OF STOCK CERTIFICATES, ETC. ON EXERCISE.  As soon as
practicable after the exercise of this Warrant in full or in part, and in any
event within 10 days thereafter, the Company at its expense (including the
payment by it of any applicable issue taxes) will cause to be issued in the name
of and delivered to the holder hereof, or as such holder (upon payment by such
holder of any applicable transfer taxes) may direct, a certificate or
certificates for the number of fully paid and non-assessable shares of Common
Stock (or Other


                                         -4-

<PAGE>

Securities) to which such holder shall be entitled upon such exercise, plus, in
lieu of any fractional share to which such holder would otherwise be entitled,
cash equal to such fraction multiplied by the then current market value of one
full share, together with any other stock or other securities and property
(including cash, where applicable) to which such holder is entitled upon such
exercise pursuant to Section 5 or otherwise.

     5.   ADJUSTMENT FOR DIVIDENDS IN OTHER STOCK, PROPERTY, ETC.;
RECLASSIFICATION, ETC. In case at any time or from time to time after the
Original Issue Date the holders of Common Stock (or Other Securities) shall have
received, or (on or after the record date fixed for the determination of
stockholders eligible to receive) shall have become entitled to receive, without
payment therefor

                  (a)    other or additional stock or other securities or
     property (other than cash) by way of dividend, or

                  (b)    any cash paid or payable (including, without
     limitation, by way of dividend), except out of earned surplus of the
     Company, or

                  (c)    other or additional (or less) stock or other securities
     or property (including cash) by way of spin-off, split-up,
     reclassification, recapitalization, combination of shares or similar
     corporate rearrangement,

then, and in each such case, the holder of this Warrant, upon the exercise
hereof as provided in Section 3, shall be entitled to receive the amount of
stock and other securities and property (including cash in the cases referred to
in subdivisions (b) and (c) of this Section 5 which such holder would hold on
the date of such exercise if on the Original Issue Date he had been the holder
of record of the number of shares of Common Stock called for on the face of this
Warrant and had thereafter, during the period from the Original Issue Date to
and including the date of such exercise, retained such shares and all such other
or additional (or less) stock and other securities and property (including cash
in the cases referred to in subdivisions (b) and (c) of this Section 5)
receivable by him as aforesaid during such period, giving effect to all
adjustments called for during such period by Section 6.  Notwithstanding
anything to the contrary contained in this Warrant, including this Section 5, no
adjustment shall be made to the number of shares of Common Stock recited in the
first paragraph hereof issuable upon exercise hereof as a result of the Proposed
Stock Split.

     6.   REORGANIZATION, CONSOLIDATION, MERGER, ETC.  In case the Company after
the Original Issue Date shall (a) effect a reorganization, (b) consolidate with
or merge into any other person, or (c) transfer all or substantially all of its
properties or assets to any other person under any plan or arrangement
contemplating the dissolution of the Company, then, in each such case, the
holder of this Warrant, upon the exercise hereof as provided in Section 3 at any
time after the consummation of such reorganization, consolidation or merger or
the effective date of such dissolution, as the case may be, shall be entitled to
receive (and the


                                         -5-

<PAGE>

Company shall be entitled to deliver), in lieu of the Common Stock (or Other
Securities) issuable upon such exercise prior to such consummation or such
effective date, the stock and other securities and property (including cash) to
which such holder would have been entitled upon such consummation or in
connection with such dissolution, as the case may be, if such holder had so
exercised this Warrant immediately prior thereto, all subject to further
adjustment thereafter as provided in Section 5 hereof.

     7.   CERTAIN EVENTS.  If any event occurs of the nature contemplated by the
provisions of Sections 5 or 6 hereof but not expressly provided for by such
provisions, then the Company's board of directors shall make an appropriate
adjustment in the amount of stock or other securities to which the holder hereof
shall be entitled to receive upon exercise hereof so as to protect the rights of
the holder.

     8.   FURTHER ASSURANCES.  The Company will take all such action as may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and non-assessable shares of stock upon the exercise of all Warrants
from time to time outstanding.

     9.   ACCOUNTANTS' CERTIFICATE AS TO ADJUSTMENTS.  In each case of any
adjustment or readjustment in the shares of Common Stock (or Other Securities)
issuable upon the exercise of the Warrants, the Company at its expense will
promptly cause the Company's regularly retained auditor to compute such
adjustment or readjustment in accordance with the terms of the Warrants and
prepare a certificate setting forth such adjustment or readjustment and showing
in detail the facts upon which such adjustment or readjustment is based, and the
number of shares of Common Stock outstanding or deemed to be outstanding.  The
Company will forthwith mail a copy of each such certificate to each holder of a
Warrant.

     10.  NOTICES OF RECORD DATE, ETC.  In the event of

                  (a)    any taking by the Company of a record of the holders of
     any class of securities for the purpose of determining the holders thereof
     who are entitled to receive any dividend (other than a cash dividend
     payable out of earned surplus of the Company) or other distribution, or any
     right to subscribe for, purchase or otherwise acquire any shares of stock
     of any class or any other securities or property, or to receive any other
     right, or

                  (b)    any capital reorganization of the Company, any
     reclassification or recapitalization of the capital stock of the Company or
     any transfer of all or substantially all the assets of the Company to or
     consolidation or merger of the Company with or into any other person, or

                  (c)    any voluntary or involuntary dissolution, liquidation
     or winding-up of the Company, or


                                         -6-

<PAGE>

                  (d)    any proposed issue or grant by the Company of any
     shares of stock of any class or any other securities, or any right or
     option to subscribe for, purchase or otherwise acquire any shares of stock
     of any class or any other securities (other than the issue of Common Stock
     on the exercise of the Warrants), then and in each such event the Company
     will mail or cause to be mailed to each holder of a Warrant a notice
     specifying (i) the date on which any such record is to be taken for the
     purpose of such dividend, distribution or right, and stating the amount and
     character of such dividend, distribution or right, (ii) the date on which
     any such reorganization, reclassification, recapitalization, transfer,
     consolidation, merger, dissolution, liquidation or winding-up is to take
     place, and the time, if any, as of which the holders of record of Common
     Stock (or Other Securities) shall be entitled to exchange their shares of
     Common Stock (or Other Securities) for securities or other property
     deliverable upon such reorganization, reclassification, recapitalization,
     transfer, consolidation, merger, dissolution, liquidation or winding-up,
     and (iii) the amount and character of any stock or other securities, or
     rights or options with respect thereto, proposed to be issued or granted,
     the date of such proposed issue or grant [and the persons or class of
     persons to whom such proposed issue or grant] and the persons or class of
     persons to whom such proposed issue or grant is to be offered or made.
     Such notice shall be mailed at least 20 days prior to the date therein
     specified.

     11.  RESERVATION OF STOCK, ETC. ISSUABLE ON EXERCISE OF WARRANTS.  The
Company will at all times reserve and keep available, solely for issuance and
delivery upon the exercise of the Warrants, all shares of Common Stock (or Other
Securities) from time to time issuable upon the exercise of the Warrants.

     12.  LISTING ON SECURITIES EXCHANGES; REGISTRATION.  If the Company at any
time shall list any Common Stock on any national securities exchange and shall
register such Common Stock under the Securities Exchange Act of 1934 (as then in
effect, or any similar statute then in effect), the Company will, at its
expense, simultaneously list on such exchange, upon official notice of issuance
upon the exercise of the Warrants, and maintain such listing of all shares of
Common Stock from time to time issuable upon the exercise of the Warrants; and
the Company will so list on any national securities exchange, will so register
and will maintain such listing of, any Other Securities if and at the time that
any securities of like class or similar type shall be listed on such national
securities exchange by the Company.

     13.  EXCHANGE OF WARRANTS.  Subject to the provisions of Section 2 hereof,
upon surrender for exchange of any Warrant, properly endorsed, to the Company,
the Company at its own expense will issue and deliver to or upon the order of
the holder thereof a new Warrant or Warrants of like tenor, in the name of such
holder or as such holder (upon payment by such holder of any applicable transfer
taxes) may direct, calling in the aggregate on the face or faces thereof for the
number of shares of Common Stock called for on the face or faces of the Warrant
or Warrants so surrendered.


                                         -7-

<PAGE>

     14.  REPLACEMENT OF WARRANTS.  Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of any
Warrant and, in the case of any such loss, theft or destruction, upon delivery
of an indemnity agreement reasonably satisfactory in form and amount to the
Company or, in the case of any such mutilation, upon surrender and cancellation
of such Warrant, the Company at its expense will execute and deliver, in lieu
thereof, a new Warrant of like tenor.

     15.  WARRANT AGENT.  The Company may, by written notice to each holder of a
Warrant, appoint an agent having an office in New York, New York, for the
purpose of issuing Common Stock (or Other Securities) upon the exercise of the
Warrants pursuant to Section 3, exchanging Warrants pursuant to Section 13, and
replacing Warrants pursuant to Section 14, or any of the foregoing, and
thereafter any such issuance, exchange or replacement, as the case may be, shall
be made at such office by such agent.

     16.  REMEDIES.  The Company stipulates that the remedies at law of the
holder of this Warrant in the event of any default or threatened default by the
Company in the performance of or compliance with any of the terms of this
Warrant are not and will not be adequate, and that such terms may be
specifically enforced by a decree for the specific performance of any agreement
contained herein or by an injunction against a violation of any of the terms
hereof or otherwise.

     17.  NEGOTIABILITY, ETC.  This Warrant is issued upon the following terms,
to all of which each holder or owner hereof by the taking hereof consents and
agrees:

                  (a)    subject to the provisions hereof, title to this Warrant
     may be transferred by endorsement (by the holder hereof executing the form
     of assignment attached hereto as SCHEDULE II) and delivery in the same
     manner as in the case of a negotiable instrument transferable by
     endorsement and delivery;

                  (b)    subject to the foregoing, any person in possession of
     this Warrant properly endorsed is authorized to represent himself as
     absolute owner hereof and is empowered to transfer absolute title hereto by
     endorsement and delivery hereof to a bona fide purchaser hereof for value;
     each prior taker or owner waives and renounces all of his equities or
     rights in this Warrant in favor of each such bona fide purchaser and each
     such bona fide purchaser shall acquire absolute title hereto and to all
     rights represented hereby; and

                  (c)    until this Warrant is transferred on the books of the
     Company, the Company may treat the registered holder hereof as the absolute
     owner hereof for all purposes, notwithstanding any notice to the contrary.


                                         -8-

<PAGE>

     18.  NOTICES, ETC.  All notices and other communications from the Company
to the holder of this Warrant shall be mailed by first class registered or
certified mail, postage prepaid, at such address as may have been furnished to
the Company in writing by such holder, or, until an address is so furnished, to
and at the address of the last holder of this Warrant who has so furnished an
address to the Company.

     19.  MISCELLANEOUS.  This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.  This Warrant is being delivered in the State of New York and shall
be construed and enforced in accordance with and governed by the laws of such
State.  The headings in this Warrant are for purposes of reference only, and
shall not limit or otherwise affect any of the terms hereof.

     20.  ASSIGNABILITY.  Subject to the transfer conditions referred to in the
legend endorsed hereon, this Warrant is fully assignable at any time upon
surrender of this Warrant with a properly executed Assignment (in the form of
SCHEDULE II hereto) at the principal office of the Company.

                                        ADVANCED RADIO TECHNOLOGIES
                                        CORPORATION


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


[Corporate Seal]

Attest:


- ----------------------------------------
     Secretary


                                         -9-

<PAGE>

                                      SCHEDULE I

                                 FORM OF SUBSCRIPTION

                     (To be signed only upon exercise of Warrant)


To:  ADVANCED RADIO TECHNOLOGIES CORPORATION


     The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder,  * shares of Common Stock of ADVANCED RADIO TECHNOLOGIES
CORPORATION, and herewith makes payment of
$                  therefor, and requests that the certificates for such shares
be issued in the name of, and delivered to,
  , whose address is


Dated:

                                        ----------------------------------------
                                        (Signature must conform in all respects
                                        to name of holder as specified on the
                                        face of the Warrant)


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

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

*    Insert here the number of shares called for on the face of the Warrant (or,
     in the case of a partial exercise, the portion thereof as to which the
     Warrant is being exercised), in either case without making any adjustment
     for additional Common Stock or any other stock or other securities or
     property or cash which, pursuant to the adjustment provisions of the
     Warrant, may be deliverable upon exercise.


                                         -10-

<PAGE>

                                     SCHEDULE II

                                  FORM OF ASSIGNMENT

                     (To be signed only upon transfer of Warrant)



     For value received, the undersigned hereby sells, assigns and transfers
unto                                         the right represented by the within
Warrant to purchase shares of Common Stock of [____________________] to which
the within Warrant relates, and appoints
Attorney to transfer such right on the books of [_________________] with full
power of substitution in the premises.  The Warrant being transferred hereby is
one of an aggregate of [______________] Common Stock Purchase Warrants issued by
[________________________] as of [_______________], 19__.


Dated:

                                        ----------------------------------------
                                        (Signature must conform in all respects
                                        to name of holder as specified on the
                                        face of the Warrant)

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


- ----------------------------------------
Signature guaranteed by a Bank or
Trust Company having its principal
office in New York City or by a
Member Firm of the New York or
+American Stock Exchange


                                         -11-


<PAGE>

                                                               EXHIBIT 10-31(f)


                                   OPTION AGREEMENT


    AGREEMENT made this 3rd day of July, 1996 by and between COMMCO, L.L.C., a
Delaware limited liability company ("CLC")  and ADVANCED RADIO TECHNOLOGIES
CORPORATION, a Delaware corporation ("TECH").

    WHEREAS, Tech has agreed to acquire from CommcoCCC, Inc., a Delaware
("COMMCOCCC") substantially all of the assets of CommcoCCC, including 38 GHz
Authorizations covering approximately 117,750,000 Pops pursuant to an Asset
Acquisition Agreement and Plan of Reorganization (the "ASSET AGREEMENT") dated
the date hereof by and among Tech, Advanced Radio Telecomm Corp., CLC,
CommcoCCC, Columbia Millimeter Communications, L.P. ("CMC") and CCC Millimeter,
L.P. ("CCC"); and

    WHEREAS, in order to induce CLC to enter into the Asset Agreement, Tech
desires to grant CLC the option to purchase certain 38 GHz Authorizations on the
terms and conditions set forth below, if and only if, CLC is granted by the FCC
New Authorizations covering at least 40 million Pops.

    NOW, THEREFORE, in consideration of the foregoing and the mutual promises
herein contained, and for other good and valuable consideration, the receipt and
adequacy of which is acknowledged by each of the parties hereto, the parties
hereto do hereby agree as follows:

    1.   DEFINITIONS.  Capitalized terms used in this Agreement and not
otherwise defined shall have the meanings set forth below.

         1.1.    "CLOSING DATE" means the Closing Date under the Asset
         Agreement.

         1.2.    "FAIR MARKET VALUE" means with respect to a share of Tech
         Common Stock (i) if the principal trading market for such securities
         is an exchange, the last reported sale price, or, in case no such
         reported sale takes place on such date, the average of the last
         reported sale prices for the last three (3) trading days, in either
         case as officially reported on any consolidated tape, (ii) if the
         principal market for such securities is the over-the-counter market,
         the last reported sale on such date as reported by Nasdaq or, if the
         security is not quoted on Nasdaq, the last reported sale as set forth
         in the National Quotation Bureau sheet listing such securities for
         such day.  Notwithstanding the foregoing, if there is no reported
         closing price on the date next preceding the event requiring
         determination hereunder, then the Fair Market Value shall be
         determined as of the latest date prior to such day for which such
         closing price is available, or if the securities are not quoted on
         Nasdaq, as determined in good faith by resolution of the Board of
         Directors of Tech based on the best

<PAGE>

         information available to it.

         1.3.    "FINAL ORDER" means  an action by the FCC, state regulatory
         authority or a court of competent jurisdiction as to which (i) no
         request for stay by the FCC, state regulatory authority or a court of
         competent jurisdiction, as applicable, is pending, no such stay is in
         effect, and, if any deadline for filing any such request is designated
         by statute or regulation, such deadline has passed; (ii) no petition
         for rehearing or reconsideration or application for review of the
         action is pending before the FCC, state regulatory authority or court
         of competent jurisdiction, as applicable, and the time for filing any
         such petition has passed; (iii) the FCC, state regulatory authority or
         court of competent jurisdiction, as applicable, does not have the
         action under reconsideration on its own motion and the time for such
         reconsideration has passed; and (iv) no appeal to a court of competent
         jurisdiction, or request for stay by a court of competent
         jurisdiction, of the FCC's, the state regulatory authority's or the
         court's action, as applicable, is pending or in effect and, if any
         deadline for filing any such appeal or request is designated by
         statute or rule, such deadline has passed.

         1.4.    "FINANCING OPTION" means the option, at the sole discretion of
         CLC, whereby Tech finances the purchase pursuant to the exercise of
         the Option by CLC on the terms and conditions described in Section
         3.3.

         1.5.    "NEW AUTHORIZATIONS" shall mean any 38 GHz Authorizations
         granted to CLC with respect to any Pending Applications owned by CLC.

         1.6.    "OPTION CLOSING" means the date of the purchase and sale of 38
         GHz Authorizations as provided herein.

         1.7.    "OPTION PERIOD" means the period commencing on the Closing
         Date and terminating nine (9) months after the consummation of the
         initial public offering of Tech Common Stock.

         1.8.    "OPTION PRICE" means the amount determined by (a) dividing the
         number of Pops covered by the Eligible Authorizations to be purchased
         by the Pops Per Share Factor and (b) multiplying the result by the
         Fair Market Value of a share of Tech Common Stock on the date on which
         the Option is exercised.

         1.9.    "PENDING APPLICATION" means an application that was filed with
         the FCC prior to November 13, 1995, to obtain a 38 GHz Authorization,
         which as of the date hereof has not been granted or dismissed by the
         FCC, and which was placed on public notice by the FCC and held in
         abeyance pursuant to the NPRM.


                                         -2-

<PAGE>

         1.10.   "POPS" means the number of human beings resident within a
         particular geographic area determined pursuant to EXHIBIT E to the
         Asset Agreement.

         1.11.   "POPS PER SHARE FACTOR" means 117,752,241 (representing the
         Pops covered by the 38 GHz Authorizations to be acquired by Tech from
         CommcoCCC) divided by 16.5 million (representing the number of shares
         to be issued by Tech to CommcoCCC for its assets), which number of
         shares shall be adjusted for stock splits stock dividends, and similar
         events described in Section 5 of the Warrants (other than the
         29,450.16 to 1 stock split in connection with the ART Reorganization).

         1.12.   "ELIGIBLE AUTHORIZATIONS" means one 38 GHz Authorization
         covering each of the cities listed on EXHIBIT A.

         1.13.   "38 GHZ AUTHORIZATIONS" means construction permits granted by
         the FCC for the construction and operation of millimetric microwave
         telecommunications systems on specific 100 MHZ channels between 37.0
         GHz and 40.0 GHz on the radio frequency spectrum within specified
         geographic footprints each with up to a 50-mile radius.

         1.14.   "TECH COMMON STOCK" means common stock, par value $.001 per
         share, of Tech.

    2.   REPRESENTATIONS.

         2.1.    CLC.  CLC represents and warrants to Tech that it has full
         power and authority to enter into this Agreement and that this
         Agreement does not conflict with any other Agreement to which it is a
         party or by which it is or shall be bound at the time of the Option
         Closing.

         2.2.    TECH.  Tech represents and warrants to CLC that it has full
         power and authority to enter into this Agreement and that this
         Agreement does not conflict with any other Agreement to which it is a
         party or by which it is or shall be bound at the time of the Option
         Closing.

    3.   THE OPTION.

         3.1.    GRANT.  In the event that CLC is granted by the FCC New
         Authorizations covering at least 40 million Pops prior to the end of
         the Option Period, Tech hereby grants to CLC an irrevocable option
         (the "OPTION") to elect to purchase all or any one or more of the
         Eligible Authorizations during the Option Period for the Option Price.


                                         -3-

<PAGE>

         3.2.    TIME AND MANNER OF EXERCISE.  CLC may exercise the Option at
         any time but not more than once, during the Option Period.

         3.3.    PAYMENT OF OPTION PRICE.  At the closing of the purchase
         pursuant to the exercise of the Option (the "CLOSING"), CLC shall pay
         the Option Price by wire transfer, or certified or bank check to Tech.
         Provided, however, if CLC exercises its Option within 120 days
         following the later of the Closing Date or the date of grant by the
         FCC of New Authorizations covering more than 40 million Pops, then CLC
         shall have the option to pay the Option Price by delivery to Tech of
         CLC's nonrecourse promissory note for the Option Price, which note
         shall bear interest at prime + 1% per annum and be due in two (2)
         years with interest thereon payable quarterly in arrears and shall be
         secured solely by a pledge of Tech Common Stock received by CLC upon
         the closing of the Asset Agreement.  The number of shares of Tech
         Common Stock to be pledged shall be the amount required to
         collateralize (2.0) times the outstanding principal balance of the
         promissory note based upon the Fair Market Value of the Tech Common
         Stock on the date of the Option exercise.  Such number of shares
         pledged shall be increased, as necessary, to continue to collateralize
         1.25 times the promissory note amount based upon the Fair Market Value
         of the shares as redetermined from time to time.  The promissory note
         and stock pledge agreement shall be in such form as is reasonably
         acceptable to CLC and Tech.

         3.4.    OPTION CLOSING.  The Option Closing shall take place at the
         offices of Tech at 3:00 p.m. on the later of (a) the date which shall
         be the first business day after the thirtieth (30th) day after the
         exercise of the Option, or (b) if FCC consent for the Option Closing
         is required, Tech agrees to file within ten (10) business days of the
         exercise of the option and diligently prosecute all appropriate
         application for FCC consent to the transfer of the Eligible
         Authorizations subject to the exercise, and the Option Closing shall
         be held on the first business day after the fifth (5th) day after an
         order for the FCC consenting to the transaction has become a Final
         Order.  However, CLC has the right to waive finality.

    4.   MISCELLANEOUS.

         4.1.    OBLIGATION TO PURCHASE EQUIPMENT.  In the event CLC exercises
         its Option hereunder, CLC shall purchase for cash at original cost
         equipment previously purchased by Tech and reasonably required in
         order to perfect the 38 GHz Authorization purchased by CLC hereunder.

         4.2.    TECH'S RESELLER RIGHTS.  Tech shall have the right to be a
         reseller, and to enter into a reseller agreement with CLC with respect
         to any 38 GHz


                                         -4-

<PAGE>

         Authorization purchased by CLC hereunder for a term of 5 years at
         market rates, or elect to move its customers utilizing the 38 GHz
         Authorizations within 6 months after the Closing.

         4.3.    ASSIGNMENT.  Neither party hereto may assign its rights or
         obligations hereunder without the prior written consent of the other
         party.

         4.4.    AMENDMENTS; WAIVERS.  The terms of this Agreement may not be
         waived, amended, modified, terminated or discharged unless in a
         writing signed by the parties hereto.

         4.5.    NOTICES.  All notices or other communications provided for
         under this Agreement shall be in writing (including facsimile) and
         mailed, hand delivered, sent by overnight courier or by telecopier to
         the parties effective when received at the addresses specified:

                 If to Tech:           Advanced Radio Technologies Corporation
                                       500 108th Street, N.E., Suite 2600
                                       Bellevue, Washington  98004
                                       Attn:  Chief Executive Officer

                 with a copy to:       Pierson & Burnett, LLP
                                       1667 K Street, N.W.
                                       Suite 801
                                       Washington, D.C.  20036
                                       Attn:  W. Theodore Pierson, Jr., Esq.

                 If to CLC:            Commco, L.L.C.
                                       4513 Pin Oak Court
                                       Sioux Falls, SD  57103
                                       Attn:  Scott Reardon

                 with a copy to:       David Knudson, Esq.
                                       Davenport, Evans, Hurwitz & Smith,
                                       L.L.P.
                                       513 South Main Avenue
                                       Sioux Falls, South Dakota  57104-6813
                                       Fax:  (605) 335-3639

         4.6.    GOVERNING LAW.  This Agreement shall be governed by and
         construed in accordance with the laws of the State of Delaware.


                                         -5-

<PAGE>

         4.7.    COUNTERPARTS.  This Agreement may be executed in counterparts,
         each of which shall be deemed an original but all of which taken
         together shall constitute one and the same instrument.

         4.8.    ENTIRE AGREEMENT.  This Agreement contains the entire
         understanding of the parties hereto with respect to the subject matter
         contained herein and therein.  This Agreement supersedes all prior
         agreement and understandings between the parties with respect to the
         subject matter.

         4.9.    SECTION HEADINGS.  Section headings in this Agreement are for
         convenience only and shall not form a part of this Agreement.

         4.10.   SEVERABILITY.  If any provision of this Agreement shall be 
         found by any court of competent jurisdiction to be invalid or 
         unenforceable, the parties waive such provision to the extent that it 
         is found to be invalid or unenforceable.  Such provision shall, to the 
         maximum extent allowable by law, be modified by such court so that it 
         becomes enforceable and, as modified, shall be enforced as any other 
         provision hereof, all the other provisions hereof continuing in full 
         force and effect.

    IN WITNESS WHEREOF, this Agreement has been duly exercised by the parties
hereto as of the day and year first above written.

                                       ADVANCED RADIO TECHNOLOGIES CORPORATION


                                       By:
                                          -------------------------------------


                                       COMMCO, L.L.C.



                                       By:
                                          -------------------------------------


                                         -6-

<PAGE>

                                      EXHIBIT A



Boston
Portland
Charlotte
Norfolk
Richmond
Rochester
Memphis
Greensboro
Buffalo
Long Island, NY
St. Louis, MO
Knoxville, TN


                                         -7-


<PAGE>

                                                              EXHIBIT 10-31(g)

                               SECURITY AGREEMENT


     This Security Agreement (the "AGREEMENT") dated June 27, 1996, made by
Advanced Radio Technologies Corporation, a Delaware corporation with an office
at 500 108th Street, N.E., Suite 2600, Bellevue, Washington 98004 (the
"BORROWER" or the "GRANTOR"), to Columbia Capital Corporation, a Virginia
corporation ("COLUMBIA"), as collateral agent for the benefit of the Secured
Parties.

                                    RECITALS

     The registered holders (the "SECURED PARTIES") of the Bridge Note due
September 30, 1996 in the original principal amount of $1,000,000, the Bridge
Note due September 30, 1996 in the original principal amount of $602,900 and the
Bridge Note due September 30, 1996 in the original principal amount of
$1,397,100 (said Notes, as they may hereafter be amended or otherwise modified
from time to time, being the "Notes," the terms defined therein and not
otherwise defined herein being used herein as therein defined) issued by the
Grantor.  The Notes have been issued in connection with the transactions
contemplated by the Asset Acquisition Agreement and Plan of Reorganization dated
July 3, 1996 (the "ASSET ACQUISITION AGREEMENT") among the Grantor, Advanced
Radio Telecom Corp. ("Telecom"), a Delaware corporation, CommcoCCC, Inc., a
Delaware corporation ("COMMCOCCC"), CCC Millimeter, L.P., a Delaware limited
partnership ("CCC"), Columbia Millimeter Communications, L.P., a Delaware
limited partnership ("CMC"), Columbia and Commco, L.L.C. ("CLC") which provides
for the purchase by the Borrower of substantially all of the assets of CommcoCCC
in exchange for the Tech Securities (as defined in the Asset Acquisition
Agreement).  In order to induce the Secured Parties to make the commitment set
forth in the Notes, the Grantor has agreed to grant to the Secured Parties a
security interest in its assets pursuant to this Agreement.  The execution and
delivery of this Agreement is a condition precedent to CommcoCCC's obligation to
execute and deliver the Asset Acquisition Agreement and to consummate the
transactions contemplated thereby.  

          NOW, THEREFORE, in consideration of the premises and in order to
induce the Secured Parties to make the advances under the Notes, the Grantor
hereby agrees as follows:

          SECTION 1. CERTAIN DEFINITIONS.  The following terms for all purposes
of this Agreement shall have the respective meanings specified below.

          "ART 38 GHZ AUTHORIZATIONS" refers to all 38 GHz Authorizations of the
Grantor, including a list containing latitude and longitude of the rectangular
service area, date granted and channels authorized.

          "ART PENDING APPLICATIONS" refers to the Pending Applications of the
Grantor, including latitude and longitude of the requested rectangular service
area, channels requested, date filed, public notice dates and amendments.

<PAGE>

          "ART PERMITS" refers to all material Permits which are necessary or
required for the conduct of the business of the Grantor and its subsidiaries as
currently conducted and as contemplated to be conducted.

          "ART INTELLECTUAL PROPERTY" refers to all material patents, patent
rights, trademarks, service marks, trade names, copyrights, rights or licenses
to use the same, and any and all applications therefor, presently owned or held
by the Grantor or any of its subsidiaries or of which such Issuer or any of its
subsidiaries is a licensor or licensee or in which such Grantor or any of its
subsidiaries has any right.

          "COLUMBIA" means Columbia Capital Corporation, a Virginia corporation.

          "CLC" means Commco, L.L.C., a Delaware limited liability partnership.

          "CMC" means Columbia Millimeter Communications, L.P., a Delaware
limited partnership.

          "COMMCOCCC 38 GHZ AUTHORIZATIONS" refers to all 38 GHz Authorizations
of Columbia, CMC and CLC, including  latitude and longitude of the rectangular
service area, date granted and channels authorized.

          "COMMCOCCC PENDING APPLICATIONS" refers to the Pending Applications of
Columbia, CMC and CLC, including latitude and longitude of the requested
rectangular service area, channels requested, date filed, public notice dates
and amendments.

          "COMMCOCCC PERMITS" refers to all material Permits which are necessary
or required for the conduct of the business of CommcoCCC as currently conducted
and as contemplated to be conducted.

          "COMMCOCCC INTELLECTUAL PROPERTY" refers to all material patents,
patent rights, trademarks, service marks, trade names, copyrights, rights or
licenses to use the same, and any and all applications therefor, presently owned
or held by CommcoCCC or of which CommcoCCC is a licensor or licensee or in which
CommcoCCC has any right.

          "DISTRIBUTION" means (a) the declaration or payment of any dividend or
distribution on or in respect of any shares of capital stock, other than
dividends payable solely in shares of common stock, (b) the purchase or other
retirement of any shares of capital stock or (c) any other distribution on or in
respect of any shares of capital stock.

          "EVENT OF DEFAULT" means an Event of Default as defined in the Notes.

          "FCC" means the Federal Communications Commission.

                                      -2-
<PAGE>

          "PENDING APPLICATION" means an application that was filed with the FCC
prior to November 13, 1995, to obtain a 38 GHz Authorization, which as of the
date hereof has not been granted or dismissed by the FCC, and which was placed
on public notice by the FCC and held in abeyance pursuant to the notice of
proposed rulemaking issued by the FCC on December 15, 1995 pursuant to which it
proposed to amend its current rules to provide for, among other things, (i) the
adoption of an auction procedure for the issuance of licenses in the 38 GHz
band, including a possible auction of the lower 16 channels in the 38 GHz band
that have not been previously available for commercial use, (ii) the
continuation of the 100 MHZ-based channeling plan and licensing rules for point-
to-point microwave operations in the lower 16 channels, (iii) licensing
frequencies using predefined geographic service areas, (iv) the imposition of
minimum construction requirements for new authorizations and existing 38 GHz
licenses as a condition to the retention of existing authorizations and (v) the
implementation of certain technical rules designed to avoid radio frequency
interference among licensees.

          "PERMITS" means all licenses, permits, orders, consents, approvals,
registrations, authorizations, qualifications and filings under all federal,
state, local or foreign laws with governmental or regulatory bodies, except for
the 38 GHz Authorizations and the Pending Applications.

          "38 GHZ AUTHORIZATIONS" means construction permits granted by the FCC
for the construction and operation of millimetric microwave telecommunications
systems on specific 100 MHZ channels between 37.0 GHz and 40.0 GHz on the radio
frequency spectrum each within a specified geographic footprint with up to a 50-
mile radius.

Unless otherwise defined herein, terms used in Article 9 of the Uniform
Commercial Code (the "CODE) as in effect in the State of Delaware are used
herein as therein defined.

          SECTION 2. GRANT OF SECURITY.  The Grantor hereby assigns and pledges
to Columbia, as collateral agent for the benefit of the Securities Parties, and
hereby grants to Columbia, as collateral agent for the benefit of the Secured
Parties a security interest in, to the extent permitted by law, all of the
Grantor's right, title and interest in and to the following, whether now owned
or hereafter acquired (the "COLLATERAL"):

          (a)  the ART 38 GHZ Authorizations, the ART Pending Applications, the
ART Permits, the ART Intellectual Property, the CommcoCCC 38 GHz Authorizations,
the CommcoCCC Pending Applications, the CommcoCCC Permits and the CommcoCCC
Intellectual Property, to the extent a security interest therein is permitted by
applicable law;

          (b)  all equipment in all of its forms, wherever located, now or
hereafter existing, and all parts thereof and all accessions thereto (any and
all such equipment, parts and accessions being the "EQUIPMENT");

                                      -3-
<PAGE>

          (c)  all inventory in all of its forms, wherever located, now or
hereafter existing (including, but not limited to, (i) all finished goods and
raw materials and work in process, and materials used or consumed in the
manufacture or production thereof, (ii) goods in which the Grantor has an
interest in mass or a joint or other interest or right of any kind (including,
without limitation, goods in which the Grantor has an interest or right as
consignee) and (iii) goods that are returned to or repossessed by the Grantor,
and all accessions thereto and products thereof and documents therefor (any and
all such inventory, accessions, products and documents being the "INVENTORY");

          (d)  10,013,055 shares of Common Stock, $.001 par value in Telecom
(the "PLEDGED STOCK"), representing all shares of capital stock in Telecom owned
by the Grantor on the date hereof;

          (e)  all accounts, contract rights, chattel paper, instruments,
general intangibles and other obligations of any kind, now or hereafter
existing, whether or not arising out of or in connection with the sale or lease
of goods or the rendering of services, and all rights now or hereafter existing
in and to all security agreements, leases and other contracts securing or
otherwise relating to any such accounts, contract rights, chattel paper,
instruments, general intangibles and obligations (any and all such accounts,
contract rights, chattel paper, instruments, general intangibles and obligations
being the "RECEIVABLES," and any and all such leases, security agreements and
other contracts being the "RELATED CONTRACTS"); and

          (f)  all proceeds of any and all of the foregoing Collateral
(including, without limitation, proceeds that constitute property of the types
described in clauses (a), (b), (c) and (d) of this Section and, to the extent
not otherwise included, all payments under insurance (whether or not the Secured
Party is the loss payee thereof), or any indemnity, warranty or guaranty,
payable by reason of loss or damage to or otherwise with respect to any of the
foregoing Collateral.

          SECTION 3. SECURITY FOR OBLIGATIONS.  This Agreement secures the
payment of all obligations of the Grantor now or hereafter existing under the
Notes, whether for principal, interest, fees, expenses or otherwise, and all
obligations of the Grantor now or hereafter existing under this Agreement (all
such obligations of the Grantor being the "OBLIGATIONS").

          SECTION 4. GRANTOR REMAINS LIABLE.  Anything herein to the contrary
notwithstanding, (a) the Grantor shall remain liable under the contracts and
agreements included in the Collateral to the extent set forth therein to perform
all of its duties and obligations thereunder to the same extent as if this
Agreement had not been executed, (b) the exercise by Columbia of any of the
rights hereunder shall not release the Grantor from any of its duties or
obligations under the contracts and agreements included in the Collateral, and
(c) the Secured Parties shall not have any obligation or liability under the
contracts and agreements included in the Collateral by reason of this Agreement,
nor shall the Secured Parties be obligated to perform

                                      -4-
<PAGE>

any of the obligations or duties of the Grantor thereunder or to take any 
action to collect or enforce any claim for payment assigned hereunder.

          SECTION 5. REPRESENTATIONS AND WARRANTIES.  The Grantor represents 
and warrants to the Secured Parties as follows:

          (a)  The chief place of business and chief executive office of the 
Grantor and the office where the Grantor keeps its records concerning the 
Receivables, and all originals of all chattel paper that evidence 
Receivables, have been delivered to the Secured Parties.  None of the 
Receivables is evidenced by a promissory note or other instrument.

          (b)  All shares of Pledged Stock are and shall be at all times duly 
authorized, validly issued, fully paid and nonassessable.  The Grantor will 
deliver to Columbia certificates representing the Pledged Stock, registered, 
if Columbia so requests, in the name of Columbia or its nominee, as pledgee, 
or accompanied by a stock transfer power executed in blank and, if Columbia 
so requests, in the name of Columbia or its nominee, as pledgee, or 
accompanied by a stock transfer power executed in blank and, if Columbia so 
requests, with the signature guaranteed, all in form and manner satisfactory 
to Columbia.

          (c)  The Grantor owns the Collateral to this Agreement free and 
clear of any lien, security interest, charge or encumbrance, except for the 
security interest created by this Agreement and the security interest of CRA, 
Inc. pursuant to the Security Agreement dated April 1, 1996 between Advanced 
Radio Telecom Corp. and CRA, Inc. (the "CRA Security Interest"). No effective 
financing statement or other instrument similar in effect covering all or any 
part of the Collateral is on file in any recording office, except such as may 
have been filed in favor of the Secured Parties relating to this Agreement or 
such relating to the CRA Security Interest.  The Grantor has no trade name.

          (d)  Each Receivable and Related Contract is a bona fide, valid and
legally enforceable property right of the Grantor and, so far as the Grantor
knows, is enforceable against any other party thereto in respect thereof, except
for Receivables and Related Contracts that do not, in the aggregate, materially
and adversely affect the value of the Collateral taken as a whole. All consents,
licenses, approvals and authorizations of, and declarations with, any
governmental authority required to be obtained, effected or given in connection
with the execution, delivery and performance of each Receivable and Related
Contract by the Grantor have been or will be duly obtained, effected or given
and are or will be in full force and effect, except where the failure to do so
does not materially and adversely affect the value of the Collateral taken as a
whole.

          (e)  The Grantor has exclusive possession and control of the Equipment
and Inventory.

          (f)  With respect to each Receivable, neither the Grantor nor, so far
as the Grantor knows, any other party to such Receivable is in default in the
performance or observance

                                      -5-
<PAGE>

of any of the terms thereof and the Grantor has fully performed in all 
material respects all its material obligations under each Receivable as of 
the date such performance is due; and, to the best of the Grantor's 
knowledge, the right, title and interest of the Grantor in and to any 
Receivable is not subject to any defense, offset, counterclaim or claim 
(except as otherwise explicitly provided therein), nor have any of the 
foregoing been asserted or, to the best of the Grantor's knowledge, 
threatened against the Grantor as to any Receivable, except for such 
defaults, defenses, offsets, counterclaims and claims as do not materially 
and adversely affect the value of the Collateral taken as a whole.

          (g)  This Agreement creates a valid and perfected security interest in
all of the Collateral other than the ART 38 GHz Authorizations, the ART Pending
Applications, the CommcoCCC 38 GHz Authorizations and the CommcoCCC Pending
Applications, securing the payment of the Obligations, and all filings and other
actions necessary or desirable to perfect and protect such security interest
have been duly taken.

          (h)  This Agreement creates a valid security interest in the
Collateral, other than the ART 38 GHZ Authorizations, the ART Pending
Applications, the CommcoCCC 38 GHz Authorizations and the CommcoCCC Pending
Applications, in favor of the Secured Parties; upon the filing of the financing
statements and the payment of applicable filing fees, such security interest
will be prior to all other liens, claims, security interests, encumbrances and
rights of others, except the CRA Security Interest; such security interest is
enforceable, except as it relates to the ART 38 GHz Authorizations, the ART
Pending Applications, the CommcoCCC 38 GHz Authorizations and the CommcoCCC
Pending Applications, as such as against creditors of and purchasers from the
Grantor and as against any owner of the real property where any of the Equipment
is located and as against any purchaser of real property and any present or
future creditor obtaining a lien on such real property; and all action necessary
to protect and perfect such security interest in each item of the Collateral
will have been duly taken prior to the initial Advance.

          (i)  The amount represented by the Grantor to the Secured Parties from
time to time as owing by each account debtor or by all account debtors in
respect of the Receivables of the Grantor will at such time be the correct
amount actually and, to the best of the Grantor's knowledge, unconditionally
owing by such account debtors thereunder.

          (j)  No authorization, approval or other action by, and no notice to
or filing with, any governmental authority or regulatory body is required either
(i) for the grant by the Grantor of the security interest granted hereby or for
the execution, delivery or performance of this Agreement by the Grantor or (ii)
for the perfection of or the exercise by the Secured Parties of its rights and
remedies hereunder.

          SECTION 6. FURTHER ASSURANCES.  (a)     The Grantor agrees that from
time to time, at the expense of the Grantor, the Grantor will promptly execute
and deliver all further instruments and documents, and take all further action,
that may be necessary or desirable, or that

                                      -6-
<PAGE>

Columbia may request, in order to perfect and protect the security interest 
granted hereby or to enable Columbia, on behalf of the Secured Parties to 
exercise and enforce its rights and remedies hereunder with respect to the 
Collateral.  Without limiting the generality of the foregoing, the Grantor 
will: (i) mark conspicuously each document included in its Inventory and each 
chattel paper included in its Receivables and each of its Related Contracts 
and, at the request of Columbia, each of its records pertaining to the 
Collateral with a legend, in form and substance satisfactory to Columbia, 
indicating that such document, chattel paper, Related Contract or Collateral 
is subject to the security interest granted hereby; (ii) if any of its 
Receivables shall be evidenced by a promissory note or other instrument or 
chattel paper, deliver and pledge to Columbia on behalf of the Secured 
Parties hereunder such note, instrument or chattel paper duly indorsed and 
accompanied by duly executed instruments of transfer or assignment, all in 
form and substance satisfactory to Columbia; (iii) execute and deliver any 
and all such further chattel paper and instruments and take such further 
action as Columbia may reasonably request to obtain the full benefits of this 
Agreement and of the rights and powers herein granted, including, without 
limitation, the filing of any financing or continuation statements under the 
Code in effect in any jurisdiction with respect to the security interest 
granted hereby; and (iv) execute and file such financing or continuation 
statements, or amendments thereto, and such other instruments or notices, as 
may be necessary or desirable, or as Columbia may request, in order to 
perfect and preserve the security interests granted hereby.  Upon entering 
into any material contract hereafter, the Grantor will use its best efforts 
to obtain a collateral assignment of such contract hereunder, by a writing in 
form and substance reasonably satisfactory to Columbia, if and to the extent 
requested by the Secured Parties.

          (b)  The Grantor hereby authorizes Columbia  to file one or more
financing or continuation statements, and amendments thereto, relative to all or
any part of its Collateral without the signature of the Grantor where permitted
by law.  A carbon, photographic or other reproduction of this Agreement or any
financing statement covering the Collateral or any part thereof shall be
sufficient as a financing statement where permitted by law.

          (c)  The Grantor will furnish to Columbia from time to time statements
and schedules further identifying and describing the Collateral and such other
reports in connection with the Collateral as Columbia may reasonably request,
all in reasonable detail.

          SECTION 7. AS TO EQUIPMENT AND INVENTORY.  The Grantor shall:

          (a)  cause its Equipment to be maintained and preserved in the same
condition, repair and working order as when new, ordinary wear and tear
excepted, and in accordance with any manufacturer's manual, and shall forthwith,
or in the case of any loss or damage to any of its Equipment as quickly as
practicable after the occurrence thereof, make or cause to be made all repairs,
replacements and other improvements in connection therewith that are necessary
or desirable to such end; and the Grantor shall promptly furnish to Columbia a
statement respecting any loss or damage to any of its Equipment; and

                                      -7-
<PAGE>

          (b)  pay promptly when due all property and other taxes, assessments
and governmental charges or levies imposed upon, and all claims (including
claims for labor, materials and supplies) against, the Equipment and Inventory,
except to the extent the validity thereof is being contested in good faith.

          SECTION 8. INSURANCE.  The Grantor shall, at its own expense,
maintain insurance with respect to the Equipment and Inventory in such amounts,
against such risks, in such form and with such insurers as shall be reasonably
satisfactory to Columbia from time to time.  The Grantor shall, if so requested
by Columbia, deliver to Columbia the original or duplicate policies of such
insurance and, as often as Columbia may reasonably request, a report of a
reputable insurance broker with respect to such insurance.  The Grantor shall,
at the request of Columbia, duly execute and deliver instruments of assignment
of such insurance policies to comply with the requirements of Section 6 and
cause the respective insurers to acknowledge notice of such assignment.

          SECTION 9. AS TO RECEIVABLES AND RELATED CONTRACTS.  (a)  The Grantor
shall keep its chief place of business and chief executive office and the office
where it keeps its records concerning its Receivables, and all originals of all
chattel paper that evidence its Receivables, at the location therefore specified
in Section 5(a) or, upon 30 days' prior written notice to Columbia, at such
other location in a jurisdiction where all action required by Section 6 shall
have been taken with respect to its Receivables.  The Grantor will hold and
preserve such records and chattel paper and will permit representatives of
Columbia at any time during normal business hours to inspect and make abstracts
from such records and chattel paper.

          (b)  Except as otherwise provided in this subsection (b), the Grantor
shall continue to collect, at its own expense, all amounts due or to become due
to such Grantor under its Receivables.  In connection with such collections, the
Grantor may take (and, at the Secured Party's direction, shall take) such action
as the Grantor or Columbia reasonably may deem necessary or advisable to enforce
collection of its Receivables.

          (c)  The Grantor will not (i) amend, modify, terminate or waive any
provision of any material Receivable in any manner that could be reasonably
anticipated to materially and adversely affect the value of such Receivable as
Collateral or that materially and adversely affects the rights granted to
Columbia, for the benefit of the Secured Parties thereunder, including, without
limitation, provisions regarding notices of default, (ii) fail to exercise
promptly and diligently each and every material right that it may have under
each material Receivable (other than any right of termination) or (iii) fail to
deliver to Columbia a copy of each material demand, notice or other document
received by it relating in any way to any material Receivable. 

          SECTION 10.         AS TO PLEDGED STOCK.  (a)  Until an Event of
Default shall occur, the Grantor shall be entitled to receive all Distributions
on or with respect to the Pledged Stock. If an Event of Default shall have
occurred, all Distributions on or with respect to the Pledged Stock shall be
retained by Columbia (or if received by the Grantor shall be held by the Grantor

                                      -8-
<PAGE>

in trust and shall be immediately delivered by the Grantor to Columbia in the
original form received, endorsed in blank) and held by Columbia as part of the
Collateral.

          (b)  Until an Event of Default shall occur, the Grantor shall be
entitled to vote or consent with respect to the Pledged Stock in any manner not
inconsistent with the terms of the Notes, and Columbia will, if so requested,
execute appropriate revocable proxies therefor.  If an Event of Default shall
have occurred, if and to the extent that Columbia shall so notify the Grantor in
writing, only Columbia shall be entitled to vote or consent or take any other
action with respect to the Pledged Stock (and the Grantor will, if so requested,
execute or cause to be executed appropriate proxies therefor).

          SECTION 11.         TRANSFERS AND OTHER LIENS.  The Grantor shall not:

          (a)  sell, assign (by operation of law or otherwise) or otherwise
dispose of any of the Collateral, except Inventory in the ordinary course of
business; or

          (b)  create or suffer to exist any lien, security interest or other
charge or encumbrance upon or with respect to any of the Collateral to secure
Indebtedness of any Person, except for (i) the security interest created by this
Agreement and (ii) the CRA Security Interest.

          SECTION 12.         COLUMBIA APPOINTED ATTORNEY-IN-FACT.  The Grantor
hereby irrevocably appoints Columbia such Grantor's attorney-in-fact, with full
authority in the place and stead of the Grantor and in the name of the Grantor,
Columbia or otherwise, from time to time in Columbia's discretion, to take any
action and to execute any instrument that Columbia may deem necessary or
advisable to accomplish the purposes of this Agreement (subject to the rights of
the Grantor under Section 9), including, without limitation:

          (i)  to ask, demand, collect, sue for, recover, compromise, receive
and give acquittance and receipts for moneys due and to become due under or in
respect of any of the Collateral,

          (ii) to receive, indorse, and collect any drafts or other instruments,
documents and chattel paper, in connection with clause (i) above,

          (iii)      to file any claims or take any action or institute any
proceedings that Columbia may deem necessary or desirable for the collection of
any of the Collateral or otherwise to enforce the rights of Columbia with
respect to any of the Collateral and

          (iv) to file any application, petition or other request with the FCC
or any other governmental authority for the purpose of obtaining any consent or
approval from or satisfying any filing or notice requirement of such
governmental authority in order to effect a sale or transfer of any or all of
the Collateral or a change in control of the Grantor.

                                      -9-
<PAGE>

          SECTION 13.         COLUMBIA MAY PERFORM.  If the Grantor fails to
perform any agreement contained herein, then Columbia may itself perform, or
cause performance of, such agreement, and the expenses of Columbia incurred in
connection therewith shall be payable by the Grantor under Section 16(b).

          SECTION 14.         THE SECURED PARTIES.  The powers conferred on
Columbia hereunder are solely to protect its interest in the Collateral and
shall not impose any duty upon it to exercise any such powers.  Except for the
safe custody of any Collateral in its possession and the accounting for moneys
actually received by it hereunder, Columbia shall have no duty as to any
Collateral or as to the taking of any necessary steps to preserve rights against
prior parties or any other rights pertaining to any Collateral.

          SECTION 15.         REMEDIES.   If any Event of Default shall have
occurred and be continuing:

          (a)  Columbia may exercise in respect of the Collateral, in addition
to other rights and remedies provided for herein or in the Note or otherwise
available to it, all the rights and remedies of a Secured Party on default under
the Code, whether or not the Code applies to the affected Collateral, and also
may (i) require the Grantor to, and the Grantor hereby agrees that it will at
its expense and upon request of Columbia forthwith, assemble all or part of the
Collateral as directed by Columbia and make it available to Columbia at a place
to be designated by Columbia that is reasonably convenient to both parties and
(ii) without notice except as specified below, sell the Collateral or any part
thereof in one or more parcels at public or private sale, at any of the Secured
Parties's offices or elsewhere, for cash, on credit or for future delivery, and
upon such other terms as Columbia may deem commercially reasonable.  The Grantor
agrees that, to the extent notice of sale shall be required by law, at least ten
days' notice to the Grantor of the time and place of any public sale or the time
after which any private sale is to be made shall constitute reasonable
notification.  Columbia shall not be obligated to make any sale of Collateral
regardless of notice of sale having been given.  Columbia may adjourn any public
or private sale from time to time by announcement at the time and place fixed
therefor, and such sale may, without further notice, be made at the time and
place to which it was so adjourned.


          (b)  All cash proceeds received by Columbia in respect of any sale of,
collection from or other realization upon all or any part of the Collateral may,
in the discretion of Columbia, be held by Columbia as collateral for, and/or
then or at any time thereafter applied (after payment of any amounts payable to
Columbia pursuant to Section 16) in whole or in part by Columbia against, all or
any part of the Obligations in such order as Columbia shall elect.  Any surplus
of such cash or cash proceeds held by Columbia and remaining after payment in
full of all the Obligations shall be paid over to the Grantors or to whomsoever
may be lawfully entitled to receive such surplus.  The Grantors also agree to
execute, in order to effectuate any sale provided for in subsection (a) of this
Section, any endorsements, assignments or other instruments of conveyance or
transfer with respect to any or all of the Collateral. 

                                      -10-
<PAGE>

Notwithstanding any other provision of this Agreement, the exercise of the
Secured Parties' rights and remedies under this Agreement shall in all events be
subject to obtaining any necessary FCC approval.

          SECTION 16.         INDEMNITY AND EXPENSES.  (a)  The Grantor agrees
to indemnify Columbia from and against any and all claims, losses and
liabilities growing out of or resulting from this Agreement (including, without
limitation, enforcement of this Agreement), except claims, losses or liabilities
resulting from Columbia's gross negligence or willful misconduct.

          (b)  The Grantor will upon demand pay to Columbia the amount of any
and all reasonable expenses, including the reasonable fees and disbursements of
its counsel and of any experts and agents, that Columbia may incur in connection
with (i) the administration of this Agreement, (ii) the custody, preservation,
use or operation of, or the sale of, collection from or other realization upon,
any of the Collateral, (iii) the exercise or enforcement of any of the rights of
the Secured Parties hereunder or (iv) the failure by the Grantor to perform or
observe any of the provisions hereof.

          SECTION 17.         SECURITY INTEREST ABSOLUTE.  All rights of the
Secured Parties and security interests hereunder, and all obligations of the
Grantors hereunder, shall be absolute and unconditional, irrespective of:

          (i)  any lack of validity or enforceability of the Asset Acquisition
Agreement, the Note or any other agreement or instrument relating thereto;

          (ii) any change in the time, manner or place of payment of, or in any
other term of, all or any of the Obligations or any other amendment or waiver of
or any consent to any departure from the Asset Acquisition Agreement or the
Note;

          (iii)      any exchange, release or non-perfection of any other
collateral, or any release or amendment or waiver of or consent to departure
from any guaranty, for all or any of the Obligations; or


          (iv) any other circumstance that might otherwise constitute a defense
available to, or a discharge of, the Grantor or a third party grantor of a
security interest.

          SECTION 18.         FURTHER INDEMNIFICATION.  The Grantor agrees to
pay, and to save Columbia and the Secured Parties harmless from and against, any
and all liabilities with respect to, or resulting from any delay in paying, any
and all excise, sales or other taxes (other than any gross receipt tax that is
in the nature of a net income tax, any franchise tax and any tax measured by net
income) that may be payable or determined to be payable by the Grantor with
respect to any of the Collateral or in connection with any of the transactions
contemplated by this Agreement.

                                      -11-
<PAGE>

          SECTION 19.         FCC NOTIFICATION.  In the event that the
requirements of 47 C.F.R. Section 22.917, or any successor regulation, are or
become applicable to this Agreement, Columbia agrees, to the extent required to
do so, to notify the Grantor and the FCC in writing at least ten days prior to
repossession, in accordance with this Agreement, of all or any part of the
Collateral that is subject to said regulation.

          SECTION 20.         APPOINTMENT OF RECEIVER.  It is further agreed
that, upon acceleration of the Note following the occurrence of an Event of
Default, Columbia shall be entitled to the appointment of a receiver of the
Collateral as a matter of absolute right and without notice and to collect the
rents, issues and profits of the Collateral due and coming due without regard to
the value of the Collateral or the solvency of any person or persons liable for
payment of the Note.  This provision for the appointment of a receiver is an
express condition upon which the Advances hereby secured are made.  The
reasonable expenses incurred by Columbia pursuant to the powers herein contained
shall be an Obligation secured by this Agreement.

          SECTION 21.         COUNTERPARTS.  This Agreement may be executed in
any number of counterparts and by the parties hereto in separate counterparts,
each of which, when so executed, shall be deemed an original, but all such
counterparts shall together constitute one and the same agreement.

          SECTION 22.         AMENDMENTS, WAIVERS, ETC.  No amendment or waiver
of any provision of this Agreement nor consent to any departure by the Grantor
herefrom shall in any event be effective unless the same shall be in writing and
signed by Columbia, and then such waiver or consent shall be effective only in
the specific instance and for the specific purpose for which given.

          SECTION 23.         ADDRESSES FOR NOTICES.  All notices and other
communications provided for hereunder shall be in writing (which may be a
facsimile transmission) and, if to the Grantor, mailed or telegraphed or
delivered to it, addressed to it at 500 108th Ave., N.E. Suite 2600, Bellevue,
WA  98004, Attention of Thomas A. Grina, telecopier number (206) 990-1642; if to
Columbia, mailed or delivered to it, addressed to it at 201 North Union Street,
Suite 300, Alexandria, Virginia 22314, Attention of James B. Fleming, telecopier
number (703) 519-3904; or, as to either party, at such other address as shall be
designated by such party in a written notice to each other party complying as to
delivery with the terms of this Section.  All such notices and other
communications shall, when mailed or telecopied, respectively, be effective when
deposited in the mails or delivered by telecopier, addressed as aforesaid.

          SECTION 24.         CONTINUING SECURITY INTEREST; TRANSFER OF NOTE. 
This Agreement shall create a continuing security interest in the Collateral and
shall (i) remain in full force and effect until payment in full of the
Obligations, (ii) be binding upon the Grantor, its successors and assigns and
(iii) inure to the benefit of the Secured Parties and their successors,
transferees and assigns.  Without limiting the generality of the foregoing
clause (iii), each of the Secured Parties may assign or otherwise transfer the
Note held by it to any other person, and such other person

                                      -12-
<PAGE>

shall thereupon become vested with all the benefits in respect thereof 
granted to each of the Secured Parties herein or otherwise.  Upon the payment 
in full of the Obligations, the security interest granted hereby shall 
terminate and all rights to the Collateral shall revert to the Grantor. Upon 
such termination, Columbia will, at the Grantor's expense, execute and 
deliver to such Grantor such documents as such Grantor shall reasonably 
request to evidence such termination.

          SECTION 25.         GOVERNING LAWS.  This Agreement shall be governed
by and construed in accordance with the laws of the State of Delaware, except to
the extent that the validity or perfection of the security interests thereunder,
or remedies hereunder, in respect of any particular Collateral are governed by
the laws of a jurisdiction other than the State of Delaware. 

                                      -13-
<PAGE>

          IN WITNESS WHEREOF, the Grantor has caused this Agreement to be 
duly executed and delivered by their officers thereunto duly authorized as of 
the date first above written.

                              ADVANCED RADIO TECHNOLOGIES
                              CORPORATION


                              By:______________________________
                                 Name:
                                 Title:


                              COLUMBIA CAPITAL CORPORATION,
                                as Collateral Agent for the Benefit
                                of the Secured Parties

                              By:______________________________
                                 Its:
                                  

                                      -14-

<PAGE>

                                                               EXHIBIT 10-31(h)


                            NONCOMPETITION AGREEMENT


     This Noncompetition Agreement (the "AGREEMENT") is made and entered into as
of this      day of           , 1996, by and among Advanced Radio Technologies
Corporation, a Delaware corporation ("ACQUIROR"), Advanced Radio Telecom Corp.,
a Delaware corporation ("TELECOM") (Acquiror and Telecom are collectively
referred to as the "ART COMPANIES"), CCC Millimeter, L.P., a Delaware limited
partnership ("CLP"), Columbia Millimeter Communications, L.P., a Delaware
limited partnership ("CMC"), and Columbia Capital Corporation, a Virginia
corporation ("COLUMBIA") (CLP, CMC and Columbia are collectively referred to as
"CCC").

                                 R E C I T A L S

     This Agreement is entered into in connection with the consummation of the
transactions contemplated by the Asset Acquisition Agreement and Plan of
Reorganization dated July 3 , 1996 (the "ASSET ACQUISITION AGREEMENT") among the
ART Companies, CCC and CommcoCCC, Inc., a Delaware corporation ("COMMCOCCC"),
which provides for the acquisition by Acquiror of the CommoCCC Assets (as
defined in the Asset Acquisition Agreement) from CommoCCC in exchange for the
Tech Securities (as defined in the Asset Acquisition Agreement).  In order to
induce the ART Companies to enter into the Asset Acquisition Agreement and to
consummate the Asset Acquisition, CCC, jointly and severally, has agreed not to
compete with the business of the ART Companies as provided in this Agreement. 
The execution and delivery of this Agreement is a condition to the ART
Companies' obligations to consummate the transactions contemplated by the Asset
Acquisition Agreement.

     The parties agree as follows:

     1.   DEFINITIONS.

          (a)  "AFFILIATE" shall mean any Person who, Directly or Indirectly
     through one or more intermediaries, controls, is controlled by or is under
     common control with the referenced party.  For purposes of this definition
     "controls" (including with correlative meanings, the terms "controlled by"
     and "under common control with" as applied to any Person) means the
     possession, Directly or Indirectly, of the power to direct or cause the
     direction of the management and policies of that Person, whether through
     the ownership of voting securities or other equity interests or by contract
     or otherwise.

          (b)  "BUSINESS" shall mean (i) the provision of wireless broadband
     telecommunications services using point-to-point microwave transmissions in
     the 37.0 to 40.0 gigahertz portion of the radio spectrum ("38 GHz") or (ii)
     the application, management or acquisition of all or any part of any 38 GHz
     Authorizations.



                                       

<PAGE>

          (c)  "CLOSING DATE" shall mean the date of the closing under the Asset
     Acquisition Agreement.

          (d)  "COMPETE" shall mean Directly or Indirectly to engage or assist
     any Person to engage in the Business. 

          (e)  "DIRECTLY or INDIRECTLY" shall mean (i) acting as an agent,
     representative, consultant, manager or independent contractor of any Person
     engaged in the Business, or (ii) being an owner, partner, limited partner,
     member, joint venturer, creditor or stockholder of any Person engaged in
     the Business (except as a stockholder holding less than a five percent (5%)
     interest in a corporation whose shares are actively traded on a regional or
     national securities exchange or in the over-the-counter market).

          (f)  "FCC" shall mean the Federal Communications Commission.

          (g)  "NONCOMPETE PERIOD" shall mean the period beginning at the
     Closing Date and ending on the fifth (5th) anniversary of the Closing Date.

          (h)  "NPRM" shall mean the notice of proposed rulemaking issued by the
     FCC and defined in the Asset Acquisition Agreement.

          (i)  "PENDING APPLICATIONS" shall mean the applications filed by CCC
     or CMC with the FCC for the 38 GHz authorizations set forth on EXHIBIT A
     attached hereto which were placed on public notice by the FCC and which
     have been held in abeyance pending the outcome of the NPRM.

          (j)  "PERSON" shall mean any individual, corporation, partnership,
     limited liability company, association, trust, or other entity or
     organization, including a government or political subdivision or any agency
     or instrumentality thereof.

          (k)  "TERRITORY" shall mean the United States of America and all of
     its possessions and territories.

     2.   NONCOMPETITION.  CCC, jointly and severally, covenants and agrees
that, during the Noncompete Period, neither it nor any of its Affiliates will
Compete within the Territory with the ART Companies or its Affiliates or any of
their permitted assigns or successors. 

     3.   BUSINESS WITH RESPECT TO THE PENDING APPLICATIONS.  Notwithstanding
anything contained in this Agreement to the contrary, neither CCC nor any of its
Affiliates shall be deemed to Compete with the ART Companies under this
Agreement due to (i) the ownership of Pending Applications or authorizations
(including construction permits and licenses) granted by the FCC in connection
therewith, (ii) the construction of microwave facilities in order to meet
construction deadlines set forth in the construction permits granted by the FCC
with respect to the Pending 



                                      -2-

<PAGE>

Applications, (iii) the sale, transfer, assignment or other disposition, by 
operation of law or otherwise, of the Pending Applications or the 
authorizations (including construction permits and licenses) granted by the 
FCC in connection therewith to any other Person, (iv) engaging in the 
Business utilizing the radio frequencies covered by the Pending Applications 
and any subsequent grant by the FCC of authorizations or licenses with 
respect thereto, or (v) the ownership of less than 50% of the voting 
securities or other equity interests in any Person acquired in exchange for 
the Pending Applications or the authorizations (including construction 
permits and licenses) granted by the FCC in connection therewith and any 
related assets.

     4.   EQUITABLE RELIEF.  CCC acknowledges that a breach by it or any of its
Affiliates of the provisions of this Agreement cannot reasonably or adequately
be compensated in damages in an action at law and that a breach of any of the
provisions contained in this Agreement may cause the ART Companies irreparable
injury and damage.  CCC further acknowledges that CCC possesses unique skills,
knowledge and ability and that competition in violation of this Agreement or any
other breach of the provisions of this Agreement could be extremely detrimental
to the ART Companies.  By reason thereof, CCC agrees that the ART Companies
shall be entitled, in addition to any other remedies it may have under this
Agreement or otherwise, to seek preliminary and permanent injunctive and other
equitable relief to prevent or curtail any breach of this Agreement, and in such
case CCC shall not assert that the ART Companies have an adequate remedy at law;
provided, however, that no specification in this Agreement of a specific legal
or equitable remedy shall be construed as a waiver or prohibition against the
pursuing of other legal or equitable remedies in the event of such a breach.  In
the event that the ART Companies must enforce any of the rights herein granted
to it through an attorney, CCC shall be liable for any and all reasonable
attorneys fees, expenses and court costs incurred in connection with the
enforcement of the ART Companies' rights hereunder.

     5.   SEVERABILITY.  In the event that any provision of this Agreement or
any word, phrase, clause, sentence or other portion thereof (including, without
limitation, the geographical and temporal restrictions contained herein) should
be held to be unenforceable or invalid for any reason, such provision or portion
thereof shall be modified or deleted in such a manner so as to make this
Agreement as modified legal and enforceable to the fullest extent permitted
under applicable laws.  CCC further acknowledges that the period and geographic
area of restriction imposed by Section 2 is fair and reasonable and is
reasonably required for the protection of the ART Companies.

     6.   SUCCESSORS AND ASSIGNS.  This Agreement shall be binding upon and
shall inure to the benefit of the parties hereto, their respective Affiliates,
and their respective successors and assigns, and shall survive any merger or
consolidation of any of such parties, or any of their Affiliates, with or into
any other Person.  This Agreement is nonassignable except that the ART
Companies' rights, duties and obligations under this Agreement may be assigned
to its acquirer in the event the ART Companies is merged, acquired, or sells
substantially all of its assets to any other entity.



                                      -3-

<PAGE>

     7.   INTEGRATED AGREEMENT AND CONSIDERATION.  This Agreement constitutes
the entire Agreement among the parties hereto with regard to the subject matter
hereof, and there are no agreements, understandings, restrictions, warranties or
representations relating to said subject matter among the parties other than
those set forth herein or herein provided for.   CCC hereby acknowledges that
the Asset Acquisition (as defined in the Asset Acquisition Agreement) is good
and valuable consideration received by CCC for the covenants and undertakings as
described in this Agreement.  

     8.   COUNTERPARTS.  This Agreement may be executed in two or more
counterparts, each of which need not contain the signatures of more than one
party, but such counterparts taken together shall constitute one and the same
Agreement.

     9.   GOVERNING LAW.  The terms of this Agreement shall be governed by and
construed in accordance with the laws of the State of Delaware.

     10.  MODIFICATIONS.  This Agreement shall not be amended or modified except
by an instrument in writing signed by each party to be bound thereby, and
reciting that the parties thereby intend to so amend or modify this Agreement.
     
     11.  WAIVER.  Failure of any party to enforce at any time any of the
provisions of this Agreement shall in no way be construed to be a waiver of any
such provision, nor in any way to affect the validity of this Agreement or any
part thereof or the right of any party thereafter to enforce each and every
provision.   Neither party hereto shall be deemed to have waived any rights or
remedies hereunder unless such waiver is by an instrument in writing signed by
each party to be bound thereby.  No waiver of any breach or noncompliance of
this Agreement shall be held to be a waiver of any other or subsequent breach or
noncompliance.       



                                      -4-

<PAGE>

     IN WITNESS WHEREOF, the undersigned have executed this Agreement on the
date first above written.

                         ADVANCED RADIO TECHNOLOGIES CORPORATION

                         By:                                                   
                            ---------------------------------------------------
                              Its:                                             
                                  ---------------------------------------------


                         ADVANCED RADIO TELECOM CORP.

                         By:                                                   
                            ---------------------------------------------------
                              Its:                                             
                                  ---------------------------------------------


                         CCC MILLIMETER, L.P.

                         By:  Columbia Capital Corporation
                              Its:   General Partner

                              By:                                              
                                 ----------------------------------------------
                                   Its:                                        
                                       ----------------------------------------


                         COLUMBIA MILLIMETER COMMUNICATIONS, L.P.

                         By:  Columbia Capital Corporation
                              Its: General Partner

                              By:                                               
                                 -----------------------------------------------
                                   Its:                                         
                                       -----------------------------------------

                         COLUMBIA CAPITAL CORPORATION


                              By:                                               
                                 -----------------------------------------------
                                   Its:                                         
                                       -----------------------------------------



                                      -5-




<PAGE>

                                                               EXHIBIT 10-31(i)

                         COMMCOCCC MANAGEMENT AGREEMENT


     THIS MANAGEMENT AGREEMENT ("Agreement") among CommcoCCC, Inc., a Delaware
corporation ("CommcoCCC"), Columbia Millimeter Communications, L.P., a Delaware
limited partnership, ("CMC"), Commco, L.L.C., a Delaware limited liability
company ("CLC") and Columbia Capital Corporation ("Columbia") (CommcoCCC, CMC,
CLC, and Columbia are collectively the "Licensees" and individually a
"Licensee") and Advanced Radio Technologies Corporation ("ART"), a Delaware
corporation, is entered into as of the dates set forth next to the signatures
below and is effective as of July 3, 1996.

     WHEREAS, CommcoCCC has acquired, or has the right to acquire and manage,
certain Federal Communications Commission ("FCC") authorizations listed on
Exhibit A hereto, each granted in the name of one of the Licensees (the
"Authorizations"), for 38 GHz frequency radio systems (collectively the
"Systems") in various locations ("Markets"); and 

     WHEREAS, Licensees and ART desire to enter into an agreement for the
construction, operation, and management by ART of the Systems, consistent with
Licensees' obligations in connection with the Authorizations under all of the
Federal and state laws, rules, and regulations;

     NOW, THEREFORE, in consideration of the premises and covenants hereinafter
set forth, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties, intending to be
legally bound, hereby agree as follows:

     1.  TERM OF AGREEMENT AND TERMINATION.  

          (a)   This Agreement becomes effective on the date set forth above. 
Unless it is terminated earlier pursuant to the  provisions of this Section, the
term of this Agreement ("Term") shall extend for one year and shall renew
automatically for thirty-day terms, unless (i) subject to Section 7 hereof, with
respect to any Licensee, such Licensee terminates this Agreement with respect to
such Licensee and Authorizations then in the name of such Licensee on at least
30 days' prior written notice to ART after the first one year term or (ii)
subject to Section 7 hereof, ART terminates this Agreement at any time after the
end of the first one year term on at least 30 days' prior written notice to
CommcoCCC.

          (b)   This Agreement shall terminate immediately on the consummation,
pursuant to the Asset Acquisition Agreement and Plan of Reorganization (the
"Acquisition Agreement") dated as of the date hereof among the parties hereto,
of the Acquisition (as defined in the Acquisition Agreement).

          (c)   Subject to Section 7 hereof, if the Acquisition Agreement is
terminated pursuant to the terms of the Acquisition Agreement, this Agreement
may be terminated on 



                                       

<PAGE>

thirty days' written notice by (i) ART to CommcoCCC or (ii) any Licensee to 
ART with respect to Authorizations then in the name of such Licensee.

     2.  SYSTEM CONSTRUCTION AND MANAGEMENT; EQUIPMENT LEASE.  Each Licensee
hereby grants ART the right to manage such Licensee's Systems under the
following terms and conditions.  Licensee agrees that it shall not grant any
other party the right to manage its Systems and Authorizations, provided,
however, that each Licensee retains the right to construct and operate its
Systems.  The parties agree to coordinate the construction of all Systems. 
Subject to such Licensee's supervision and control, ART will use its reasonable
efforts to undertake the planning, design, construction, installation,
marketing, sales and operations of such Licensee's Systems.

     In particular, the parties agree as follows:

          (a)  ART shall propose a schedule of construction to each Licensee
that will identify the proposed date for each System to become operational in a
manner designed to satisfy all FCC and other regulatory requirements.  Licensee
shall have ten business days in which to approve or reject such proposed
schedule.

          (b)  Once the schedule has been approved, ART shall use its reasonable
efforts to construct the Systems in accordance with such schedule.

          (c)  ART shall acquire, lease, or otherwise obtain the right to use
all assets (collectively, the "Equipment"), necessary for the operation of the
Systems, including any expansion, modification or reduction thereof.

          (d)  On behalf of each Licensee, ART shall bill and collect, from the
users of such Systems, all fees, charges, or other compensation arising from
such use, and shall pay all expenses and fees incurred or payable by such
Systems.

          (e)  ART shall generally manage the day-to-day operations of such
Systems and do or assist with any and all other acts and shall execute such
other agreements, documents or instruments, as are consistent with FCC rules and
regulations and, in the good faith judgment of ART, are necessary to carry out
the development, construction and operation of the Systems, whether or not
specifically enumerated herein.

          (f)  All Equipment shall be acquired and constructed by ART and shall
be the property of ART.  The Equipment with respect to each Licensee's
Authorization shall be leased to such Licensee for the consideration described
in Section 4 hereof during the term of this Agreement and solely for the
purposes described herein.  During the term of such lease, Licensee shall have
full and unfettered access to all the Equipment used in Licensee's System. Such
lease shall terminate simultaneously with the termination of this Agreement for
any 



                                      -2-

<PAGE>

reason.  Upon such termination, the Equipment shall remain the property of 
the ART, and ART may take immediate possession thereof.

     3.  REGULATORY COMPLIANCE.  The parties agree that each Licensee is in sole
control of the Authorizations granted in the name of such Licensee and that it
is required by FCC regulations to be in sole control so long as it is the
Licensee.  ART acknowledges and agrees that each Licensee has ultimate control
over all decisions affecting the Systems, notwithstanding any other provision of
this Agreement.  ART will assist each Licensee in complying with all applicable
Federal, state and local regulations.  This assistance includes, but is not
limited to, the following:

          (a)  Each System customer will be advised that service is provided
over facilities controlled by the applicable Licensee;

          (b)  ART agrees to use its reasonable efforts to comply with all FCC
timetables concerning construction and operation and to take such steps as may
be needed to preserve any Authorizations that may be granted by the FCC,
including discontinuing operations if so directed by the applicable Licensee to
avoid any violations of FCC rules or regulations; ART will provide Licensee with
advance written notice if it comes into possession of facts indicating that it
will be unable to render a System operational within the timetable specified by
the terms of the applicable authorization; 

          (c)  Neither ART nor the applicable Licensee shall represent
themselves as the legal agents of one another;

          (d)  The applicable Licensee shall, with the cooperation and
assistance of ART, fully comply with all regulations necessary to keep the
Authorization in full force and effect. Each Licensee shall prepare and submit
to the FCC and any other relevant Federal, state or local agency all reports,
applications, renewals, or other filings or documents that may be required for
this purpose, provided that ART shall provide any assistance required by such
Licensee in fulfilling this obligation;

          (e)  In the event that ART determines that any modification to any
System Authorization are necessary or desirable, ART will submit to Licensee a
description of such proposed modifications for Licensee's review and approval,
which shall not be unreasonably withheld.  Upon approval, Licensee shall
promptly submit any requests for modifications of the relevant Authorization
submitted to such Licensee by ART which may be needed to make construction
feasible, or any filings or appeals which are necessary to extend the period for
construction under the FCC's rules.  Such requests would include, but are not
limited to, applications to the FCC for special temporary authority; and

          (f)  Each party has determined in good faith that this Agreement is in
compliance with the FCC's rules.  In the event that the FCC determines that this
Agreement is 



                                      -3-

<PAGE>

inconsistent with Licensee's obligations or it is otherwise contrary to FCC 
policies, rules and regulations, the parties agree to modify this Agreement 
in any reasonable way to maintain compliance with the FCC's rules, preserving 
to the maximum extent possible the essential business terms and conditions 
contained herein.

     4.  LEASE; MANAGEMENT FEES; EXPENSES.  During the term of this Agreement,
each Licensee shall pay ART ten percent (10%) of all gross revenue relating to
the operation of such Licensee's Authorizations as lease payments for the
Equipment pursuant to Section 2(a) hereof (each such payment made from time to
time is referred to as a "Lease Payment") and twenty-five percent (25%) of all
gross revenue relating to the operation of such Licensee's Authorizations as
ART's compensation for managing the Systems pursuant hereto (each such payment
made from time to time is referred to as a "Management Payment").  ART shall
remit to each Licensee all revenue relating to the Authorizations other than the
Lease Payments and Management Payments.  The amount of the Management Payment
will be renegotiated every three months to an amount no less than twenty-five
percent (25%) of gross revenue.  ART will invoice each Licensee for all
operating expenses relating to ART's operation of such Licensee's
Authorizations, which invoices will not be payable if the Acquisition is
consummated; provided, however, that in no event shall the Licensees be
obligated to reimburse ART for operating expenses in an aggregate greater than
$100,000.

     5.  NOTICE.  All notices and other communications shall be in writing and
shall be deemed given the same day if delivered personally or sent by telecopy
or the next business day if sent by express mail or courier (overnight
delivery), or five (5) business days later if sent by registered mail or
certified mail, return receipt requested, postage prepaid, to the parties at the
following addresses or at such other address for a party as shall be specified
by like notice, provided that notice of change of address shall be effective
only upon receipt thereof:

          (a)  If to CommcoCCC, Columbia, CMC or CLC:

               Commco, L.L.C.
               4513 Pin Oak Court
               Sioux Falls, SD 57103
               Attn:  Scott Reardon
               Fax:  (203) 656-4620 and
                       (605) 335-5504   

               - and -

               Columbia Capital Corporation
               201 North Union Street
               Alexandra, Virginia 22314
               Attn:  James B. Fleming
               Fax:   (703) 519-3904



                                      -4-

<PAGE>

               with a copy to:

               Nelson Mullins Riley & Scarborough, L.L.P.
               100 North Tryon Street
               NationsBank Corporate Center
               Suite 3350
               Charlotte, North Carolina  28202
               Attn:  H. Bryan Ives III, Esq.
               Fax:   (704) 377-4814
                                   
               - and -

               David Knudson, Esq.
               Davenport, Evans, Hurwitz & Smith, L.L.P.
               513 South Main Avenue
               Sioux Falls, South Dakota  57104-6813
               Fax:  (605) 335-3639
          
          (b)  If to ART, to

               Advanced Radio Technologies Corporation
               500 108th Avenue, N.E., Suite 2600
               Bellevue, Washington  98004
               Attn:  Thomas A. Grina

               With a copy to:

               W. Theodore Pierson, Jr.
               Executive Vice President and General Counsel
               1200 Nineteenth St., N.W., Suite 607
               Washington, D.C.  20036

     6.  REPRESENTATIONS AND WARRANTIES.

          (a)  Each Licensee represents and warrants that it is the licensee or
permit holder with respect to the Authorizations listed in Exhibit A in the name
of such Licensee and that it is duly qualified under all laws, rules and
regulations to hold such Authorizations.  Each Licensee further represents and
warrants that it is the sole owner and real party in interest in the
Authorizations and that no other party (other than CommcoCCC) has an interest of
any kind.  Licensee further represents that it has the requisite authority
and/or capacity, as applicable, to perform its undertakings pursuant to this
Agreement.



                                      -5-

<PAGE>

          (b)  Each of the parties hereto represents and warrants that each
shall take such steps and execute such documents as may be necessary from time
to time to effectuate the terms and conditions of this Agreement.

          (c)  ART represents and warrants that it is a corporation duly
authorized and in good standing under the laws of the State of Delaware and has
the requisite authority to perform its undertakings pursuant to this Agreement.

          (d)  ART represents and warrants that it is familiar with the
applicable rules and regulations of the FCC and that it is aware of no
impediment to the performance of its undertakings hereunder. 

     7.   EFFECTS OF TERMINATION.  In the event of any termination pursuant to
Sections 1(a) or 1(c) hereof, the following provisions will apply.

          (a)  ART will sell to the applicable Licensee, and each Licensee will
purchase from ART, any Equipment operated on the Authorizations then in the name
of such Licensee, to the extent such Equipment is necessary to meet the FCC
construction requirements with respect to such Authorizations.  In addition, ART
may sell additional Equipment to Licensee. The purchase price to be paid for
such Equipment shall be payable in cash and shall be equal to the original cost
of such Equipment to ART.  On payment of such purchase price to ART, ART shall
transfer such Equipment free and clear of any liens and encumbrances and shall
execute a bill of sale evidencing such transfer.

          (b)    The provision of this Section 7 shall survive any termination
of this Agreement pursuant to Sections 1(a) and 1(c) hereof.

     8.  ASSIGNABILITY; SUCCESSORS AND ASSIGNS.

          (a)  Subject to the prior consent of the ART, which consent shall not
be unreasonably withheld or delayed, and provided it does not violate any of the
other terms and conditions of this Agreement or any applicable rule and/or
regulations of the FCC, Licensee may only assign this Agreement to a purchaser
of the Systems.  Further, such purchaser must expressly assume in a writing
reasonably acceptable to ART all of the obligations of the Licensee hereunder
and otherwise agrees to comply with the terms and conditions of this Agreement. 
Such assignment shall be effective only upon thirty days notification from the
Licensee, satisfaction of the above said conditions and, to the extent
applicable, consent of the FCC to the transfer of the Authorizations.  Any such
assignment shall not relieve the Licensee of its obligations hereunder.  Any
assignment in violation of this Section 8 shall be null and void.

          (b)  ART may assign its right to manage the Systems hereunder to
another party, provided such assignee of ART has experience in the management of
38 GHz systems 



                                      -6-

<PAGE>

or other telecommunications facilities or subject to Licensees consent, not 
to be unreasonably withheld, alternatively, is an affiliate of the ART or 
employs either personnel of the ART or other persons who have experience in 
the management of 38 GHz systems or other telecommunications facilities.  ART 
may employ such subcontractors or agents as it deems necessary in the 
performance of its duties hereunder.

          (c)  This Agreement shall be binding upon and inure to the benefit of
the parties hereto, and their respective heirs, representatives, successor and
permissible assigns.

     9.  SEVERABILITY.  In the event that any provision herein is held to
invalid, void, or illegal by any Federal, state or local court, or any
regulatory agency, the remaining provisions of the Agreement shall remain in
full force and effect and this Agreement shall be reasonably construed so as to
preserve the original intent of the parties hereto insofar as practicable.  In
the event that any provision herein is deemed to be invalid, void, in violation
of any agency rules, or otherwise unlawful, the parties shall use their
respective best efforts to amend the offending provisions to bring them into
legal compliance with minimum disruption to the expectations of the parties as
set forth in this Agreement.

     10.  COUNTERPARTS.  This agreement may be executed in any number of
counterparts with the same as if the signature of each counterpart were in the
same instrument.

     11.  NO WAIVER OF RIGHTS; AMENDMENT.  The failure of either party to
insist, in any one or more instances, upon the performance of any of the terms,
covenants or conditions herein, or to exercise any right hereunder, shall not be
construed as a waiver or relinquishment of the future performance of any such
term, covenant or condition, or the future exercise of such right, but the
obligation of the other party with respect to such future performance shall
continue in full force and effect.  This Agreement may only be amended, modified
or changed by a writing signed by all parties hereto.

     12.  WARRANTY.  THERE ARE NO EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
WITHOUT LIMITATION, IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE, RESPECTING THIS AGREEMENT OR THE SERVICE PROVIDED HEREUNDER.

     13.  ENTIRE AGREEMENT.  This Agreement supersedes any other agreements
between the parties, whether oral or written, relating to the matter
contemplated herein, and constitutes the entire agreement by and between the
parties, there being no other agreements or understandings between the parties
as expressly set forth herein.

     14.  GOVERNING LAW/PROCEDURE.  This Agreement will be governed by the laws
of the State of Delaware; provided that any dispute under this Agreement will be
resolved by arbitration under the Commercial Arbitration rules of the American
Arbitration Association, using one arbitrator.



                                      -7-

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first written above.

ART:                                   LICENSEES:
                                     
Advanced Radio Technologies            CommcoCCC, Inc.
Corporation                          
                                     
                                     
By:____________________________        By:________________________________
                                     
Printed Name:__________________        Printed Name:______________________
                                     
Title:_________________________        Title:_____________________________
                                     
Dated:_________________________        Dated:_____________________________
                                     
                                       By:________________________________
                                     
                                       Printed Name:______________________

                                       Title:_____________________________
                                     
                                       Dated:_____________________________
                                     
                                     
                                       CCC Millimeter Communications, L.P.
                                     
                                       By:________________________________
                                     
                                       Printed Name:______________________

                                       Title:_____________________________
                                     
                                       Dated:_____________________________



                                      -8-

<PAGE>

                                       Columbia Millimeter Communications, L.P.
                                       
                                       ________________________________________
                                     
                                       Printed Name:___________________________

                                       Title:__________________________________
                                     
                                       Dated:__________________________________
                                     
                                     
                                     
                                     
                                     
                                       Commco, L.L.C.
                                     
                                     
                                     
                                       By:_____________________________________
                                     
                                       Printed Name:___________________________

                                       Title:__________________________________
                                     
                                       Dated:__________________________________
                                     
                                     
                                     
                                       Columbia Capital Corporation
                                     
                                       By:_____________________________________
                                     
                                       Printed Name:___________________________

                                       Title:__________________________________
                                     
                                       Dated:__________________________________



                                      -9-

<PAGE>

                                                               EXHIBIT 10-31(j)

                                                                                
                         RIGHT OF FIRST OFFER AGREEMENT


     AGREEMENT made this 3rd day of July, 1996 by and among COLUMBIA MILLIMETER
COMMUNICATIONS, L.P., a Delaware limited partnership ("CMC"), COLUMBIA CAPITAL
CORPORATION, a Virginia corporation ("CCC") (CMC and CCC are collectively
referred to as "COLUMBIA") and ADVANCED RADIO TECHNOLOGIES CORPORATION, a
Delaware corporation ("TECH").

     WHEREAS, Tech has agreed to purchase from CommcoCCC, Inc., a Delaware
corporation ("COMMCOCCC"), substantially all of its assets, including 38 Ghz
Authorizations covering approximately 117,750,000 Pops (the "38 GHZ
AUTHORIZATIONS") pursuant to an Asset Acquisition Agreement and Plan of
Reorganization (the "ACQUISITION AGREEMENT") dated the date hereof by and among
Tech, Advanced Radio Telecom Corp., CommcoCCC, Columbia, and Commco, L.L.C., a
Delaware limited liability company.  Capitalized terms used in this Agreement
and not otherwise defined shall have the meanings set forth in the Acquisition
Agreement.

     WHEREAS, in order to induce Tech to enter into the Acquisition Agreement,
Columbia desires to grant Tech a right of first offer on any 38 Ghz
Authorizations granted to Columbia with respect to any Pending Applications
owned by Columbia and listed on EXHIBIT  A attached hereto (the "NEW
AUTHORIZATIONS") on the terms and conditions set forth below.

     NOW, THEREFORE, in consideration of the foregoing and the mutual promises
herein contained, and for other good and valuable consideration, the receipt and
adequacy of which is acknowledged by each of the parties hereto, the parties
hereto do hereby agree as follows:

     1.   RIGHT OF THE FIRST OFFER.  Columbia shall notify Tech in writing (the
"OFFER NOTICE") prior to entering into any binding agreement with any Person,
other than an Affiliate of Columbia in which Columbia owns more than 50% of the
voting securities or other equity interests, with respect to (i) the sale,
transfer, assignment or other disposition (whether by merger, operation of law
or otherwise) of any New Authorization or (ii) the management or lease of any
New Authorization that gives such Person more than 50% of the net profit derived
from the New Authorization for a period longer than five (5) years ((i) and (ii)
above are referred to collectively as a "TRANSFER").  The Offer Notice shall set
forth all New Authorizations which Columbia wishes to Transfer.  Tech may offer
to purchase all (but not less than all) of the New Authorizations specified in
the Offer Notice by delivery of a written offer (the "OFFER")  to Columbia
within thirty (30) days after delivery of the Offer Notice. The Offer shall
specify the price and other terms on which Tech proposes to purchase the New
Authorizations.  After receipt of the Offer, Columbia may elect to enter into a
binding agreement for the transfer of the New Authorizations set forth in the
Offer Notice either (i) 



                                       

<PAGE>

with Tech at the price and other terms set forth in the Offer or (ii) with 
any other Person at a price greater than set forth in the Offer, free and 
clear of the terms of this Agreement; PROVIDED, HOWEVER, if (i) Columbia has 
not entered into a binding agreement for the Transfer of such New 
Authorizations with any other Person within ninety (90) days after receipt of 
the Offer, if any, or (ii) such binding agreement for the Transfer is 
terminated for any reason, then such New Authorizations shall be subject once 
again to the provisions of this Agreement In the event the price is payable 
in property, the value of the property shall be determined by a mutually 
acceptable investment banking company.  

     2.   TERM.  This Agreement shall continue in full force and effect until
the earlier of (i) the termination of the Acquisition Agreement pursuant to its
terms and (ii) six (6) months after the date on which the first New
Authorization is granted to Columbia by the FCC.

     3.   MISCELLANEOUS.

          3.1  ASSIGNMENT; SUCCESSORS.  Neither party hereto may assign its
          rights or obligations hereunder without the prior written consent of
          the other party.  In the event Columbia Transfers any New
          Authorizations to an Affiliate of Columbia in which Columbia owns more
          than 50% of the voting securities or other equity interests, as a
          condition to such Transfer such Affiliate shall assume and be bound by
          the provisions of this Agreement with respect to such New
          Authorizations.

          3.2  AMENDMENTS; WAIVERS.  The terms of this Agreement may not be
          waived, amended, modified, terminated or discharged unless in a
          writing signed by the parties hereto.

          3.3  NOTICES.  All notices or other communications provided for under
          this Agreement shall be in writing (including facsimile) and mailed,
          hand delivered, sent by overnight courier or by telecopier to the
          parties effective when received at the addresses specified:

               If to Tech:      Advanced Radio Technologies Corporation
                                500 108th Street, N.E., Suite 2600
                                Bellevue, Washington  98004
                                Attn:  Chief Executive Officer

               with a copy to:  Pierson & Burnett, LLP
                                1667 K Street, N.W.
                                Suite 801
                                Washington, D.C.  20036
                                Attn:  W. Theodore Pierson, Jr., Esq.



                                      -2-

<PAGE>

               If to Columbia:  Columbia Capital Corporation
                                201 North Union Street
                                Alexandria, Virginia
                                Attn: James B. Fleming
     
               with a copy to:  Nelson Mullins Riley & Scarborough, L.L.P.
                                100 North Tryon Street, Suite 3350
                                Charlotte, North Carolina  28202
                                Attn:  H. Bryan Ives, III, Esq.
               
          3.4  GOVERNING LAW.  This Agreement shall be governed by and construed
          in accordance with the laws of the State of Delaware.

          3.5  COUNTERPARTS.  This Agreement may be executed in counterparts,
          each of which shall be deemed an original but all of which taken
          together shall constitute one and the same instrument.

          3.6  ENTIRE AGREEMENT.  This Agreement contains the entire
          understanding of the parties hereto with respect to the subject matter
          contained herein and therein.  This Agreement supersedes all prior
          agreement and understandings between the parties with respect to the
          subject matter.

          3.7  SECTION HEADINGS.  Section headings in this Agreement are for
          convenience only and shall not form a part of this Agreement.

          3.8  SEVERABILITY.  If any provision of this Agreement shall be found
          by any court of competent jurisdiction to be invalid or unenforceable,
          the parties waive such provision to the extent that it is found to be
          invalid or unenforceable.  Such provision shall, to the maximum extent
          allowable by law, be modified by such court so that it becomes
          enforceable and, as modified, shall be enforced as any other provision
          hereof, all the other provisions hereof continuing in full force and
          effect.



                                      -3-

<PAGE>

     IN WITNESS WHEREOF, this Agreement has been duly exercised by the parties
hereto as of the day and year first above written.

                    ADVANCED RADIO TECHNOLOGIES CORPORATION

                    By:  ___________________________________

                      Its: _________________________________
                              

                    COLUMBIA CAPITAL CORPORATION

                    By: ____________________________________

                      Its: _________________________________


                    COLUMBIA MILLIMETER COMMUNICATIONS, L.P.

                    By:  Columbia Capital Corporation

                      Its:    General Partner


                         By: _______________________________

                           Its: ____________________________



                                      -4-

<PAGE>
                                                                Exhibit 10.31(h)





                                   Montgomery


PERSONAL AND CONFIDENTIAL


May 23, 1996


Advanced Radio Telecom Corp.
500 108th Avenue, N.E., Suite 2600
Bellevue, WA 98004
Attn: Vernon L. Fotheringham, Chief Executive Officer


Dear Vernon:
         We are pleased to have been selected to assist you in the acquisition
you are contemplating. This letter will confirm the understanding and agreement
between Montgomery Securities ("us" or "Montgomery") and Advanced Radio Telecom
Corp. ("you" or the "Company").

         We will serve as your exclusive representative and financial advisor
for the purpose of advising you concerning the possible acquisition (the
"Acquisition") of 38 GHz licenses and related assets (the "Licenses") owned
directly or indirectly by Columbia Capital Corporation and CommCo LLC and their
subsidiaries or other affiliated entities (the "Licenses"). For purposes of this
agreement, the Acquisition shall mean any transaction or related series or
combination of transactions whereby, directly or indirectly, control of any
Licenses or all or substantially all of the business or assets of any Licensee
is acquired by you or any of your subsidiaries or other affiliates in a sale or
exchange of stock, merger or consolidation, sale of assets or other similar
transaction.

<PAGE>

Advanced Radio Telecom Corp.
May 23, 1996                      Montgomery
Page 2


         We will render to you whatever services are mutually agreeable in order
to assist you in accomplishing the Acquisition. In particular, we will consult
with and advise you concerning the Acquisition and, if you request, participate
on your behalf in negotiations concerning the Acquisition. We will consult with
you with respect to the financial aspects of any transaction as described in the
agreements effecting the transaction. We will assist you in conducting your
business investigation of the Licenses and/or Licensees and assist you in the
administration of the closing of any transaction.

         If requested by you, we will render to your board of directors our
opinion with respect to the fairness from a financial point of view to you of
the consideration to be paid by you in the Acquisition, as of the date of the
opinion (the "Opinion"). We will render the Opinion as of the date of the
meeting of your board of directors to approve the transaction.

         In order for us to advise you effectively, it is necessary that you
make available to us all pertinent information which we reasonably request in
connection with the performance of our services hereunder, including information
concerning the business, assets, operations, or financial condition of the
Company. You agree that we may rely upon the accuracy and completeness of such
information without independent verification and are authorized to make
appropriate use of such information.

         In addition, you agree to conduct each transaction in a manner which
will comply in all respects with the applicable provisions of the Securities Act
of 1933, the Securities Exchange Act of 1934 and all other applicable federal
and state statutes, rules and regulations. You will also be responsible for the
completeness, accuracy and format of all information furnished to the Licensees
and their shareholders and furnish to them any appropriate information which may
be required by them in order to make a sale decision.

         The term of our engagement hereunder will extend from the date hereof
until May 31, 1997. However, subject to the provisions on fees, either of us may
terminate our engagement hereunder at any time upon 30 days' written notice.

<PAGE>

Advanced Radio Telecom Corp.
May 23, 1996                         Montgomery
Page 3


         As compensation for our services hereunder, you will pay us a retainer
fee of $100,000, such fee to be payable upon consummation of the Company's
initial public offering of equity or debt securities ("IPO"). The retainer will
be credited against any compensation due to us upon consummation of the
Acquisition.

         An additional fee of $500,000 shall be payable upon the later to occur
of: (i) the execution by you of a definitive agreement for the Acquisition; or
(ii) the consummation of the IPO, and will also be credited against any
compensation due us upon consummation of the Acquisition.

         If a definitive agreement for the Acquisition is executed at any time
during this engagement or within eighteen months from the termination of this
engagement, you will pay us a fee of $2,000,000 payable in cash at the time the
Acquisition is consummated; provided that, if the number of shares to be issued
in the Acquisition exceeds 37% of the outstanding shares of the common stock of
the Company (calculated on a fully diluted basis as of the date hereof and after
giving effect to the issuance of such shares), such fee shall be $1,500,000, and
if the number of shares to be so issued represents less than 35%, of the
outstanding shares of common stock of the Company (calculated on the same
basis), such fees shall be $2,000,000 plus an additional $300,000 (or fraction
thereof) for each percentage point (or fraction thereof) that the number of
shares to be issued is less than 35% of the outstanding shares of common stock
of the Company. Our compensation is to be free and clear of any obligation that
you may have to any other party.

         In addition to the foregoing fees, you agree to reimburse us for all
reasonable out-of-pocket costs and expenses (including counsel fees) incurred by
us in connection with the services to be rendered by us hereunder, whether or
not a transaction is consummated or our services are terminated or completed.
These expenses shall be billed by us and payable by you quarterly. In addition,
in the event we are requested to appear at a judicial or administrative hearing
in connection with this engagement, ,you will pay us a per diem fee of $2,000
per person per day and reimburse our reasonable out-of-pocket expenses in
connection with such appearance.

<PAGE>

Advanced Radio Telecom Corp.
May 23, 1996                       Montgomery
Page 4


         As we will be acting on your behalf, it is our practice to obtain an
indemnification and contribution agreement from you. That agreement is attached
and incorporated by reference. The obligations contained in that agreement will
remain operative regardless of any termination or completion of our scrviccs
hereunder.

         You have advised us that the transaction will not require any vote or
other approval by the shareholders of the Company. Accordingly, you have not
requested that the Opinion be disclosed in any public document. The Opinion will
not be used or referred to by you, quoted or disclosed to any person
(other than your directors, executive officers and attorneys) in any manner
without our express prior written consent.

         This engagement agreement, together with the agreement on
indemnification and contribution, contains our entire agreement concerning the
proposed transaction and supersedes any prior understandings and agreements.
This engagement agreement is made and shall be construed under and in accordance
with the laws of the State of California (without reference to any principle of
the conflict of laws). Any waiver of any right or obligation set forth in this
agreement must be in writing signed by the party against whom enforcement would
be sought.

         If  the foregoing correctly sets forth our understanding and agreement,
please sign below and return to us. We thank you for the opportunity to share in
your business endeavors and are looking forward to a successful and mutually
beneficial relationship.

     Very truly yours,

     MONTGOMERY SECURITIES
     By: SEWEL Investments, Inc., a General Partner

     By:              /s/ Joseph M. Schell
        ----------------------------------------
          Joseph M. Schell, President


<PAGE>

Advanced Radio Telecom Corp.
May 23, 1996                       Montgomery
Page 5


Accepted and Agreed to on this ___ day of May, 1996

ADVANCED RADIO TELECOM CORP.

By:          /s/Vernon L. Fotheringham
   ----------------------------------------------
     Vernon L. Fotheringham, Chief Executive Officer

<PAGE>

INDEMNIFICATION AND CONTRIBUTION AGREEMENT

         In consideration of the agreement of Montgomery Securities
("Montgomery") to act on behalf of  ADVANCED RADIO TELECOM CORP.  (the
"Company") pursuant to the attached Engagement Letter, dated  MAY 23, 1996
the Company agrees to indemnify and hold harmless Montgomery, its affiliates,
and each of their respective partners, directors, officers, agents, consultants,
employees and controlling persons (within the meaning of the Securities Act of
1933) (Montgomery and each such other person or entity are hereinafter referred
to as an "Indemnified Person"), from and against any losses, claims, damages,
expenses and liabilities or actions in respect thereof (collectively, "Losses"),
as they may be incurred (including all legal fees and other expenses incurred in
connection with investigating, preparing, defending, paying, settling or
compromising any Losses, whether or not in connection with any pending or
threatened litigation in which any Indemnified Person is a named party) to which
any of them may become subject (including in any settlement effected with the
Company's consent) and which are related to or arise out of any act, omission,
transaction or event contemplated by the Engagement Letter. The Company will
not, however, be responsible under the foregoing provisions with respect to any
Losses to the extent that a court of competent jurisdiction shall have
determined by a final judgement that such Losses resulted primarily from actions
taken or omitted to be taken by an Indemnified Person due to his gross
negligence, bad faith or willful misconduct. If multiple claims are brought
against MONTGOMERY in an arbitration, with respect to at least one of which
indemnification is permitted under applicable law and provided for under this
agreement, any arbitration award shall be conclusively deemed to be based on
claims as to which indemnification is permitted and provided for, except to the
extent the arbitration award expressly states that the award, or any portion
thereof, is based solely on a claim as to which indemnification is not
available.

         If the indemnity referred to in this agreement should be, for any
reason whatsoever, unenforceable, unavailable or otherwise insufficient to hold
each Indemnified Person harmless, the Company shall pay to or on behalf of each
Indemnified Person contributions for Losses so that each Indemnified Person
ultimately bears only a portion of such Losses as is appropriate to reflect the
relative benefits received by and the relative fault of each such Indemnified
Person, respectively, on the one hand and the Company on the other hand in
connection with the transaction: provided, however, that in no event shall the
aggregate contribution of all Indemnified Persons to all Losses in connection
with any transaction exceed the amount of the fee actually received by
Montgomery pursuant to the Engagement Letter. The relative fault of each
Indemnified Person and the Company shall be determined by reference to among
other things, whether the actions or omissions to act were by such Indemnified
Person or the Company and the parties relative intent, knowledge, access to
information and opportunity to correct or prevent such action or omission to
act.

         The Company also agrees that no Indemnified Person shall have any
liability to the Company or its affiliates, directors, officers, employees,
agents or shareholders, directly or indirectly, related to or arising out of the
Engagement Letter, except Losses incurred by the Company which a court of
competent jurisdiction shall have determined by a final judgement to have
resulted primarily from actions taken or omitted to be taken by such Indemnified
Person due to its gross negligence, bad faith or willful misconduct. In no
event, regardless of the legal theory advanced, shall any Indemnified Person be
liable for any consequential, indirect, incidental or special damages of any
nature. The Company agrees that without Montgomery's prior written consent it
shall not settle, compromise or consent to the entry of any judgment in any
pending or threatened claim, action, suit or proceeding related to the
Engagement Letter unless the settlement, compromise or consent also includes an
express unconditional release of all Indemnified Persons from all liability and
obligations arising therefrom.

         If an agreement for the sale of the Company is entered into and the
obligations of the Company referred to above are not assumed, satisfactory to
Montgomery, by operation of law or by contract by the acquiring entity, the
Company agrees to arrange alternative means of providing for such obligations
prior to consummation of such agreement, including providing insurance or
creating an escrow, in each case in an amount and upon terms and conditions
satisfactory to Montgomery.

         The obligations of the Company referred to above shall be in addition
to any rights that any Indemnified Person may otherwise have and shall be
binding upon and inure to the benefit of any successors, assigns, heirs, and
personal representatives of any Indemnified Person and the Company. It is
understood that the obligations of the Company will remain operative regardless
of any terminations or completion of Montgomery's services.


MONTGOMERY SECURITIES                    ADVANCED RADIO TELECOM CORP.
BY: SEWEL Investments Inc.               BY:    /s/Vernon L. Fotheringham
    ----------------------                  -----------------------------
BY:    /s/Joseph M. Schell               NAME: Vernon L. Fotheringham
   -----------------------                     ----------------------
       Joseph M. Schell, President       TITLE: Chief Executive Officer



<PAGE>


April 29, 1996

Mr. Thomas Cheatham
Ossipee/Helicomm
391 Totten Pond Road, Suite 303
Waltham, MA 02154


Subject:      Terms for OC-3 SONET Development and Purchase, Version III

Dear Thomas:

Now that we have cleared up most of the issues with the SAND product I would 
like to do the same for the OC-3 radio. As we discussed in our phone 
conversation today, the availability  of a low cost OC-3 radio is vital to 
ART's aggressive business plan for the coming years.

I have reviewed your prior proposal and discussed it with the principals here 
at ART. On behalf of ART, I am proposing the following terms for the OC-3 
Development and Purchase Agreement with HCI. These terms assume a June 1, 
1996 project start:

    1)   NRE FUNDING - Advanced Radio Telecom, Ltd. will pay to HCI $1MM 
         toward the $3MM estimated total NRE for the OC-3 SONET radio. The ART 
         payment will be divided into milestone segments as agreed by ART and 
         HCI. HCI will secure the balance of the NRE funding from other sources.

    2)   ART REQUIREMENTS - The OC-3 SONET radio will be built to ART's Design
         Standards and Network Architecture Requirements.

    3)   INTELLECTUAL PROPERTY TRANSFER - Should HCI substantially fail, after 
         normal remedy opportunities are depleted, to complete the development 
         of the OC-3 SONET radio for any reason other than causes originating
         with ART or force majeure, and HCI fails to repay all funds paid by
         ART for the development within (90) days of ART's notification of 
         failure, then HCI would transfer to ART a non-exclusive, transferable, 
         perpetual license to manufacture and sell the OC-3 SONET radio by 
         whatever means necessary to service ART's market.

   4)    EXCLUSIVE PURCHASE - At ART's options, ART will have the unrestricted 
         right to purchase 100% of HCI's OC-3 radio pair production capacity 
         for a period starting from delivery of the first production radio and 
         lasting for (3) years. Exclusivity is predicated on ART's maintenance
         of sequential orders equivalent to 100% of HCI's production capacity. 
         ART and HCI will agree on methods for assessing HCI's OC-3 capacity.

   5)    PRICING - OC-3 SONET radio pairs delivered to ART will be priced at 
         $20,000 per pair or less based on ART's consumption at a rate 
         equivalent to (800) radio pairs per year or HCI's production capacity, 
         whichever is less. At ART's option this volume and price level can be
         renewed on the yearly anniversary date of delivery of the first 
         production radio pair. If the above arrangement is renewed, then the 
         only year-over-year price increases 

<PAGE>

         will be per an established index calculation method mutually agreeable
         to ART and HCI.

         The price for the first (25) OC-3 radio pairs will be determined by 
         their special short-run production costs, but will not exceed $30,000.

         In all cases the OC-3 SONET radio pairs sold by HCI to ART will be at
         HCI's most favorable sales price.

   6)    BEST PRICE ROYALTY - Best price to ART will be assured by way of 
         royalty payments from HCI equal to 5% of actual purchase price on the
         first (1500) radio pairs delivered to HCI customers other than ART.

   7)    PILOT PRODUCTION DELIVERY - HCI commits to deliver (25) production
         specification OC-3 radio pairs to ART not later than January 30, 1998. 
         Delivery of these (25) radio pairs will be considered the last 
         milestone of the OC-3 development program and will release the final
         installment of the agreed NRE funding. For any reason attributable to
         HCI and other than force majeure, failure to deliver the entire lot of 
         (25) radio pairs by January 30, 1998, will result in a price reduction 
         of 25% for each of the (25) original radio pairs delivered after that
         date.

   8)    PRODUCTION RAMP-UP - By February 28, 1998, HCI will deliver to ART 
         (35) additional OC-3 radio pairs. Failure on the part of HCI to deliver
         all or part of the (35) radio pairs will result in price discounts
         on the undelivered radio pairs as described in Item 7.

         For the months of March and April 1998, HCI will deliver to ART an 
         additional (50) and (75) radio pairs per month, with the same
         penalty conditions as Item [7].

   9)    NORMAL PRODUCTION RATE - ART and HCI will negotiate a normal OC-3
         monthly production rate sufficient to meet ART's requirements, but 
         in any event no less than (100) radio pairs, starting with the month
         of May 1998 and for each month thereafter. The penalty for HCI's 
         failure to deliver the agreed volume under normal production 
         circumstances will be a 7.5% reduction in price for radio pairs 
         delivered late on a month-by-month basis.

  10)    ADDITIONAL NRE FUNDING - HCI's ability to fund the $2MM non-ART 
         portion of the OC-3 radio project is critical to the development 
         schedule. In the event that HCI cannot procure commitments for
         this funding by August 1, 1996, and upon mutual agreement of ART
         and HCI, then ART may choose to offer additional funding under one
         of the following scenarios:

         a)   for an additional $1MM payment by ART in NRE (new ART total: 
              $2MM), ART will acquire 20% equity interest in HCI. In the event
              that ART contributes an additional $2MM (ART total: $3MM), ART
              will acquire a 33% equity interest in HCI.

         b)   in return for additional ART NRE funding, ART will receive from
              HCI an additional 5% discount from HCI's best price radio pair
              cost for each $1MM contribution over the initial $1MM described in
              Item 1. This condition would be left in place for whatever period 
              required for ART to recover the additional amount + 75% in savings
              resulting from the discount.

         c)   in return for the first additional $1MM NRE payment, ART will 
              receive an additional 3% Best Price Royalty (new total: 8%) on all
              non-ART radio pairs sold by HCI, calculated against the first 
              (1500) non-ART radio pairs delivered. If the


<PAGE>

              above option were exercised, and an additional $1MM NRE payment
              were required on top of the first additional $1MM (ART total 
              NRE $3MM), then ART will acquire a 20% equity interest in HCI.


Tom, please feel free to call me at any time in regard to these proposed terms. 
The OC-3 SONET radio is strategically important for ART and I am at your 
disposal for the process of finalizing the term sheet and the definitive 
Development and Sale Agreement.


Regards,

/s/ Ric Shields                            /s/ Thomas P. Cheatham

Ric Shields                                Thomas P. Cheatham
V.P. Technology Development                President and CEO
                                           HeliOss Communications Inc.

cc: V. Fotheringham
    C. Comrie



<PAGE>
                                                                      EXHIBIT 11
 
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
               COMPUTATION OF NET LOSS PER SHARE OF COMMON STOCK
                                  (UNAUDITED)
<TABLE>
<CAPTION>
                                                                                                                    YEAR ENDED
                                                                                                                   DECEMBER 31,
                                                                                                                       1995
                                                                                                                  ---------------
 
<S>                                                                                                               <C>
Net loss applicable to Common Stock.............................................................................  $   1,267,655
                                                                                                                  ---------------
                                                                                                                  ---------------
  Shares:
    Weighted average number of shares of Common Stock outstanding for primary computation.......................     10,013,055(1)
                                                                                                                  ---------------
                                                                                                                  ---------------
Net loss per share of Common Stock..............................................................................  $        0.13
                                                                                                                  ---------------
                                                                                                                  ---------------
 
Pro Forma:
  Shares:
    Weighted average number of shares of Common Stock outstanding for primary computation.......................     10,013,055
    Issuances of shares of Telecom serial preferred stock as converted into shares of ART Common Stock..........     10,916,807
    Issuance of Telecom common stock as converted into shares of ART Common Stock...............................      8,100,807(2)
    Options and warrants issued and outstanding ................................................................      2,620,936
                                                                                                                  ---------------
  Pro forma weighted average number of shares of Common Stock...................................................     31,651,605(3)
                                                                                                                  ---------------
                                                                                                                  ---------------
Pro forma net loss per share of Common Stock....................................................................  $        0.04
                                                                                                                  ---------------
                                                                                                                  ---------------
 
Pro Forma As Adjusted
  Shares:
    Pro forma weighted average number of shares of Common Stock.................................................     31,651,605
    Common Stock issued in connection with the Common Stock Offering and the acquisition of the CommcoCCC
     Assets.....................................................................................................     24,000,000
                                                                                                                  ---------------
  Pro forma as adjusted weighted average number of shares of Common Stock.......................................     55,651,605(3)
                                                                                                                  ---------------
                                                                                                                  ---------------
Pro forma as adjusted net loss per share of Common Stock........................................................  $        0.02
                                                                                                                  ---------------
                                                                                                                  ---------------
 
<CAPTION>
                                                                                                                   FOR THE THREE
 
                                                                                                                   MONTHS ENDED
 
                                                                                                                  MARCH 31, 1996
 
                                                                                                                  ---------------
 
<S>                                                                                                               <C>
Net loss applicable to Common Stock.............................................................................  $   3,654,775
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
  Shares:
    Weighted average number of shares of Common Stock outstanding for primary computation.......................     10,013,055(1)
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
Net loss per share of Common Stock..............................................................................  $        0.37
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
Pro Forma:
  Shares:
    Weighted average number of shares of Common Stock outstanding for primary computation.......................     10,013,055
 
    Issuances of shares of Telecom serial preferred stock as converted into shares of ART Common Stock..........     10,916,807
 
    Issuance of Telecom common stock as converted into shares of ART Common Stock...............................      8,100,807(2)
 
    Options and warrants issued and outstanding ................................................................      2,620,936
 
                                                                                                                  ---------------
 
  Pro forma weighted average number of shares of Common Stock...................................................     31,651,605(3)
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
Pro forma net loss per share of Common Stock....................................................................  $        0.12
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
Pro Forma As Adjusted
  Shares:
    Pro forma weighted average number of shares of Common Stock.................................................     31,651,605
 
    Common Stock issued in connection with the Common Stock Offering and the acquisition of the CommcoCCC
     Assets.....................................................................................................     24,000,000
 
                                                                                                                  ---------------
 
  Pro forma as adjusted weighted average number of shares of Common Stock.......................................     55,651,605(3)
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
Pro forma as adjusted net loss per share of Common Stock........................................................  $        0.07
 
                                                                                                                  ---------------
 
                                                                                                                  ---------------
 
</TABLE>
 
(1)  The  weighted  average  number  of  shares  of  Common  Stock  for  primary
    computation exclude all common stock equivalents, which are anti-dilutive.
 
(2) Excludes shares of Telecom common stock owned by ART.
 
(3) The Securities  and Exchange Commission  requires that potentially  dilutive
    instruments  issued  within  one year  prior  to a  proposed  initial public
    offering at exercise prices below the expected initial public offering price
    be treated  as outstanding  for the  entire period  presented. The  weighted
    average  number of shares of Common Stock on  a pro forma and on a pro forma
    as adjusted basis  reflect those potentially  dilutive instruments  assuming
    the  sale of  shares of  Common Stock offered  in the  Common Stock Offering
    based on an assumed  initial public offering price  of $10.00 per share.  In
    measuring the dilutive effect, the treasury stock method was used.

<PAGE>
                                                                   EXHIBIT 23(A)
 
                       CONSENT OF INDEPENDENT ACCOUNTANTS
 
    We  consent to the inclusion  in this registration statement  on Form S-1 of
our report dated  April 26, 1996,  except for Note  2C, Note 5B  and the  second
paragraph  of Note 9, as to which the date is June 26, 1996, on our audit of the
financial statements of Advanced Radio  Technologies Corporation as of  December
31,  1995 and 1994, for the years then ended, and for the period from August 23,
1993 (date of inception) to December 31, 1993 and of our report dated April  26,
1996, except for Note 2B, as to which the date is June 26, 1996, on our audit of
the financial statements of Advanced Radio Telecom Corp. as of December 31, 1995
and for the period from March 28, 1995 (date of inception) to December 31, 1995.
We also consent to the reference to our firm under the caption "Experts."
 
                                          COOPERS & LYBRAND L.L.P.
 
New York, New York
July 2, 1996


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