ADVANCED RADIO TELECOM CORP
S-1, 1996-05-15
CABLE & OTHER PAY TELEVISION SERVICES
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<PAGE>
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY   , 1996
 
                                                      REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           --------------------------
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                          ADVANCED RADIO TELECOM CORP.
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                                   <C>                                   <C>
             DELAWARE                                4841                               52-1933157
  (State or Other Jurisdiction of        (Primary Standard Industrial                (I.R.S. Employer
  Incorporation or Organization)          Classification Code Number)               Identification 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 2600               500 108TH AVENUE, N.E., SUITE 2600
         BELLEVUE, WASHINGTON 98004                       BELLEVUE, WASHINGTON 98004
               (206) 688-8700                                   (206) 688-8700
 (Address, Including Zip Code, and Telephone        (Name, Address, Including Zip Code, and
Number, Including Area Code, of Registrant's        Telephone Number, Including Area Code,
        Principal Executive Offices)                         of Agent for Service)
</TABLE>
 
                           --------------------------
 
                                   COPIES TO:
 
<TABLE>
<S>                                   <C>                                   <C>
        JAMES KARDON, ESQ.                   JOHN D. WATSON, ESQ.             W. THEODORE PIERSON, JR., ESQ.
         HAHN & HESSEN LLP                     LATHAM & WATKINS                PIERSON, BURNETT & HANLEY LLP
         350 FIFTH AVENUE                1001 PENNSYLVANIA AVE., N.W.         1667 K. STREET, N.W., SUITE 801
     NEW YORK, NEW YORK 10118               WASHINGTON, D.C. 20004                WASHINGTON, D.C. 20036
          (212) 736-1000                        (202) 637-2200                        (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 MAXIMUM
                                                           PROPOSED MAXIMUM     AGGREGATE
        TITLE OF EACH CLASS OF              AMOUNT TO       OFFERING PRICE       OFFERING         AMOUNT OF
      SECURITIES TO BE REGISTERED         BE REGISTERED      PER UNIT (1)       PRICE (1)      REGISTRATION FEE
<S>                                      <C>               <C>               <C>               <C>
Units (2)..............................       Units               $            $125,000,000        $43,103
Senior Discount Notes due 2006.........        (2)               N/A               N/A               (3)
Warrants to Purchase Common Stock......        (2)               N/A               N/A               (3)
</TABLE>
 
(1) Estimated solely for purposes  of calculating the registration fee  pursuant
    to Rule 457 under the Securities Act.
 
(2)  The Units  will consist  of an  aggregate principal  amount at  maturity of
    Senior Discount Notes  due 2006 and  Warrants to purchase  shares of  Common
    Stock to raise an aggregate of $125,000,000 gross proceeds.
 
(3) As such securities are to be provided without additional cost to purchasers,
    no registration fee is required with respect thereto.
                           --------------------------
 
    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.............................................  Not Applicable
       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 Units; Description of Notes;
                                                                   Description of Warrants; Description of Capital
                                                                   Stock; Certain Federal Income Tax Considerations
      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; Certain
                                                                   Transactions; Principal Stockholders; Description of
                                                                   Units; Description of Notes; Description of
                                                                   Warrants; 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>
                             SUBJECT TO COMPLETION
                   PRELIMINARY PROSPECTUS DATED MAY 14, 1996
PROSPECTUS                                                                [LOGO]
                          $125,000,000 GROSS PROCEEDS
                          ADVANCED RADIO TELECOM CORP.
                                  UNITS CONSISTING OF
                         SENIOR DISCOUNT NOTES DUE 2006
                AND WARRANTS TO PURCHASE SHARES OF COMMON STOCK
                               ------------------
    Advanced  Radio  Telecom  Corp.,  a  Delaware  corporation  ("ART"  or   the
"Company"),  is hereby  offering       units  (the "Units"),  each consisting of
$1,000 principal  amount at  maturity of  Senior Discount  Notes due  2006  (the
"Notes")  and     warrants  (the "Warrants") to  purchase       shares of common
stock, par value $.001 per share (the "Common Stock"), of the Company. The Notes
and the Warrants will not be  separable until the earlier of (i)               ,
1996  and  (ii)  such  date  as the  Underwriters  (as  defined)  may,  in their
discretion, deem appropriate. Concurrently with  the offering of the Units  (the
"Unit  Offering"), the Company  is offering, pursuant  to a separate prospectus,
      shares of its Common Stock (the  "Equity Offering" and, together with  the
Unit  Offering,  the "Offerings").  The Unit  Offering  is conditioned  upon the
consummation of the Equity Offering.
    The issue price of the Units will be $    per Unit. The Notes will mature on
           , 2006. The issue price of  the Notes represents a yield to  maturity
of       % (computed  on a  semi-annual bond  equivalent basis)  calculated from
           , 1996.  The Notes  will  accrete at  a  rate of       %,  compounded
semiannually,  to an aggregate principal amount of $    million by             ,
2001. Cash interest will  not accrue on  the Notes prior to             ,  2001.
Commencing              , 2001, cash interest on the Notes will be payable, at a
rate of      % per annum,  semiannually in  arrears on  each                 and
           .  See  "Description  of  Notes"  and  "Certain  Federal  Income  Tax
Considerations."
    The Notes will be redeemable  at the option of the  Company, in whole or  in
part,  at any time on or after              ,  2001 at the redemption prices set
forth herein,  plus  accrued  and  unpaid  interest, if  any,  to  the  date  of
redemption.  In addition,  in the event  that the Company  receives net proceeds
from the sale of its Common Stock  in either an Equity Offering (as defined)  or
an investment by one or more Strategic Equity Investors (as defined) on or prior
to              , 1999, the Company may,  at its option, use all or a portion of
any such net  proceeds to redeem  up to a  maximum of 33  1/3% of the  initially
outstanding  aggregate principal amount at maturity of the Notes at a redemption
price equal to     % of the Accreted Value  (as defined) of the Notes;  PROVIDED
that  not less  than 66  2/3% of  the initially  outstanding aggregate principal
amount at maturity of  the Notes remain  outstanding following such  redemption.
See  "Description  of  Notes --  Redemption  -- Optional  Redemption."  Upon the
occurrence of a Change in Control (as defined), the Company is obligated to make
an offer  to purchase  all outstanding  Notes  at a  price of  (i) 101%  of  the
Accreted  Value thereof, if such purchase is prior to            , 2001, or (ii)
101% of the principal amount at maturity thereof, plus accrued interest thereon,
if any, to the date of  purchase, if such purchase is on  or after             ,
2001.  See "Description  of Notes  -- Certain  Covenants --  Change in Control."
There can be no assurance that the Company will have sufficient funds  available
at  the time of any Change in Control  to purchase all Notes tendered. See "Risk
Factors."
    The Notes will represent unsecured  senior obligations of the Company,  will
rank  PARI  PASSU  in right  of  payment  with all  existing  and  future senior
Indebtedness of the  Company and will  rank senior  in right of  payment to  all
existing  and future subordinated  Indebtedness of the  Company. At December 31,
1995, on a pro  forma basis after giving  effect to indebtedness incurred  after
December  31,  1995,  the Offerings  and  the  application of  the  net proceeds
therefrom, the aggregate principal amount of senior Indebtedness of the  Company
(excluding  trade  payables,  other  accrued  liabilities  and  the  Notes)  was
approximately $4.0 million, which  consisted of notes  payable arising from  the
acquisition  of the EMI Assets (as defined) and the Equipment Note (as defined).
The Indenture will  limit the  ability of the  Company and  its subsidiaries  to
incur  additional indebtedness. See  "Description of Notes"  and "Description of
Certain Indebtedness."
    Each Warrant will entitle the holder thereof, subject to certain conditions,
to purchase     shares of Common Stock  at an exercise price of  $   per  share,
subject to adjustment under certain circumstances. Upon exercise, the holders of
Warrants  would  be  entitled,  in  the  aggregate,  to  purchase  Common  Stock
representing approximately    % of the Common Stock on a fully-diluted basis  on
the  date hereof,  after giving  effect to the  Offerings. The  Warrants will be
exercisable at any time on or after            , 1996. Unless earlier exercised,
the Warrants will expire on            , 2006. See "Description of Warrants."
    There is no existing trading market for the Units, the Notes or the Warrants
and the Company does not intend to list the Units, the Notes or the Warrants  on
any  securities exchange.  The Company is  applying for quotation  of the Common
Stock on the Nasdaq National Market  under the symbol "ARTT." See "Risk  Factors
- -- Absence of Public Market; Possible Volatility of Stock Price."
    SEE  "RISK FACTORS" BEGINNING ON PAGE 10 FOR A DISCUSSION OF CERTAIN FACTORS
WHICH SHOULD BE CONSIDERED BY PROSPECTIVE INVESTORS IN EVALUATING AN  INVESTMENT
IN THE UNITS.
                             ---------------------
    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>
                                    PRINCIPAL AMOUNT          PRICE TO       UNDERWRITERS'     PROCEEDS TO
                                AT MATURITY OF THE NOTES      PUBLIC(1)       DISCOUNT(2)     COMPANY(1)(3)
<S>                            <C>                         <C>              <C>              <C>
Per Unit.....................             100%                    %                %                %
Total........................              $                      $                $                $
</TABLE>
 
(1)  Plus accrued original issue  discount, if any, on the  Notes from         ,
    1996.
(2) The  Company  has  agreed  to indemnify  the  Underwriters  against  certain
    liabilities,  including  liabilities under  the Securities  Act of  1933, as
    amended. See "Underwriting."
(3) Before deducting expenses payable by the Company estimated at $          .
                         ------------------------------
    The Units are  being offered  by the  Underwriters, subject  to prior  sale,
when,  as  and if  delivered to  and  accepted by  the Underwriters,  subject to
approval of certain legal  matters by counsel for  the Underwriters and  certain
other  conditions. The  Underwriters reserve  the right  to withdraw,  cancel or
modify such offer and to reject orders in whole or in part. It is expected  that
delivery  of the Units will be made in  New York, New York on or about         ,
1996.
                         ------------------------------
MERRILL LYNCH & CO.
                             MONTGOMERY SECURITIES
                                                               SMITH BARNEY INC.
                         ------------------------------
 
                 The date of this Prospectus is        , 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 THE 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.
 
                                       2
<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  APPROVAL  BY  THE  FCC AND
COMPLETION OF THE  PROPOSED MERGER  OF ADVANCED  RADIO TECHNOLOGIES  CORPORATION
("ART  CORP.") WITH AND  INTO ADVANCED RADIO TELECOM  CORP. (THE "MERGER"), (II)
THE CONVERSION OF ALL OUTSTANDING PREFERRED STOCK (AS DEFINED) INTO COMMON STOCK
UPON  THE  CONSUMMATION  OF  THE  OFFERINGS   AND  (III)  NO  EXERCISE  OF   THE
UNDERWRITERS'  OVER-ALLOTMENT OPTION  IN THE COMMON  STOCK OFFERING.  AS USED IN
THIS PROSPECTUS, THE TERMS "ART" OR THE "COMPANY" REFER EITHER TO ADVANCED RADIO
TELECOM CORP. ON A STAND-ALONE BASIS OR ON A COMBINED BASIS WITH ADVANCED  RADIO
TECHNOLOGIES  CORPORATION ("ART  CORP."), 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. The  Company believes  that it  will
derive   significant  competitive  advantages  from  the  widespread  geographic
coverage  provided   by  its   108  authorizations   granted  by   the   Federal
Communications  Commission ("FCC") in  91 U.S. market  areas. The Company, which
was one of the FCC's first 38  GHz licensees, owns or manages authorizations  in
41  of the top  45 markets and 74  of the top  100 markets. These authorizations
currently cover an aggregate population of approximately 94 million people.
 
    The ability to access and distribute information quickly has become critical
to business and government end users.  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  incumbent  local  exchange  carriers  ("LECs"). This
increasing demand, together  with changes  in the  regulatory environment,  have
created  an opportunity to offer cost  effective, high capacity last mile access
using both wireline and wireless solutions.
 
38 GHZ TECHNOLOGY
 
    ART 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 99.995%  availability, with  better than  a
10-13  bit  error rate.  This level  of  performance significantly  exceeds that
provided by copper  based networks and  is a viable  alternative to fiber  optic
based  networks. In addition, the Company believes that ART's last mile solution
is more cost effective than most  broadband wireline solutions. The 38 GHz  band
provides  for the following additional advantages  as compared to other spectrum
bands and wireline alternatives:
 
    - 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.
 
                                       3
<PAGE>
    - EFFICIENT CHANNEL REUSE. Because 38 GHz radio emissions have a narrow beam
     width, a relatively short range and can in many instances 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 each 100 MHz channel
     in a given service area can accommodate at least 10,000 DS-3 links, each of
     which can carry 672 voice circuits.
 
    - RAPID  DEPLOYMENT. 38  GHz technology  can be  deployed considerably  more
     rapidly  than wireline and other wireless  technologies. 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. The time
     required to install a 38 GHz link within a licensed footprint is  typically
     less  than 72 hours after obtaining  access to customer premises, versus an
     estimated three to five  months in other microwave  frequency bands due  to
     regulatory delay.
 
    -  EASE OF INSTALLATION. The  equipment used for 38  GHz service 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.
 
    -  EFFICIENT NETWORK DESIGN. The exclusive right to use a particular channel
     or channels within a broad geographic area gives the licensee much  greater
     control  over its network design. A 38  GHz licensee can save costs, ensure
     interference-free  operations  and  increase  quality  and  reliability  by
     designing efficient 38 GHz networks in advance of their deployment.
 
BUSINESS STRATEGY
 
    ART  began providing 38 GHz wireless  broadband services in the last quarter
of 1995 and has generated only nominal revenues from such services to date.  The
Company  is seeking to  capitalize on the  broad geographic scope  of its 38 GHz
authorizations to become the premier provider of wireless broadband solutions to
a diverse group of traditional and emerging telecommunications service providers
and  end  users.  The  Company  plans  to  implement  the  following   strategic
initiatives to achieve this objective:
 
    -  EXPLOIT SPECTRUM  POSITION IN KEY  MARKETS TO REALIZE  VALUE. The Company
     currently owns or manages  108 authorizations to  construct and operate  38
     GHz  wireless broadband facilities in 91  market areas, including 74 of the
     top 100 U.S. markets.  These spectrum assets provide  the Company with  the
     foundation  on which to  create a large  scale commercial system  of 38 GHz
     wireless broadband  operations.  The  Company  is  now  operating  wireless
     broadband  links in nine cities  (Chicago; Boston; Philadelphia; Baltimore;
     Pittsburgh;   Portland,   Oregon;    Seattle;   Albany;   and    Bethlehem,
     Pennsylvania).   The   Company  plans   to  continue   to  build   out  its
     infrastructure and to intensify its  marketing effort in its market  areas,
     thereby realizing the value inherent in its spectrum assets.
 
    -  MARKET  TO TELECOMMUNICATIONS  SERVICE  PROVIDERS. 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 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, or anticipates providing,  services
     to Ameritech, Bell Atlantic NYNEX Mobile,
 
                                       4
<PAGE>
     UUNet,  American  Personal  Communications,  Electric  Lightwave, NEXTLINK,
     Western Wireless, Chadwick Telephone Co.  and CGX Telcom, among others.  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
     working on 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.
 
    -  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 market penetration  at a  lower
     cost.  Through the  Company's internal  technology development  efforts, as
     well as  on-going participation  in equipment  manufacturers' research  and
     development  activities,  the  Company  believes  that  it  will  achieve a
     competitive  advantage  through  proprietary  methods  that  increase   the
     capacity and quality of its networks.
 
    -  ESTABLISH AND  EXPAND KEY STRATEGIC  ALLIANCES. The Company  has and will
     continue to establish key strategic alliances with major service providers,
     equipment  manufacturers,   systems   integrators  and   enhanced   service
     providers. Ameritech holds a 5.4% beneficial equity interest in the Company
     as  of April  30, 1996  and recently  entered into  the Ameritech Strategic
     Distribution  Agreement.  The   Company  also  has   agreements  with   GTE
     Corporation  ("GTE")  for field  servicing  and network  monitoring  and is
     developing relationships with a number of equipment manufacturers  focusing
     on  38 GHz technology  development, wireless broadband  standards and joint
     sales efforts. The Company will utilize these strategic alliances to bundle
     its services with  those of its  partners, which the  Company expects  will
     help it to achieve a lower cost of sales and increased market penetration.
 
                                       5
<PAGE>
                                  THE OFFERING
 
THE UNITS
 
<TABLE>
<S>                                 <C>
Gross Proceeds....................  $125,000,000.
Units Offered.....................  Units,  each  consisting of  $1,000 principal  amount at
                                    maturity of the Company's Senior Discount Notes due 2006
                                    and   Warrants (the "Warrants") to purchase       shares
                                    of Common  Stock  of  the Company.  The  Notes  and  the
                                    Warrants  will not be separable until the earlier of (i)
                                           , 1996  and (ii)  such date  as the  Underwriters
                                    may,   in  their   discretion,  deem   appropriate  (the
                                    "Separation Date").
Issue Price.......................  $      per Unit.
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  acquisitions of  spectrum rights  and, potentially,
                                    related businesses.
THE NOTES
Maturity Date.....................  , 2006.
Yield and Interest................  % (computed on a semi-annual bond equivalent basis) cal-
                                    culated from             , 1996. The Notes will  accrete
                                    at  a  rate of       %,  compounded semiannually,  to an
                                    aggregate  principal   amount  of   $       million   by
                                                , 2001. Cash interest will not accrue on the
                                    Notes  prior to           , 2001. Commencing           ,
                                    2001, cash interest on the  Notes will be payable, at  a
                                    rate  of    % per annum, semiannually in arrears on each
                                                and             . For United States  federal
                                    income  tax purposes,  purchasers of  the Notes  will be
                                    required to include amounts  in gross income in  advance
                                    of  the receipt of the cash payments to which the income
                                    is attributable. See "Certain Federal Income Tax Consid-
                                    erations."
Mandatory Redemption..............  None.
Optional Redemption...............  The Notes  will  be  redeemable at  the  option  of  the
                                    Company,  in whole or  in part, at any  time on or after
                                              , 2001  at  the redemption  prices  set  forth
                                    herein, plus accrued and unpaid interest, if any, to the
                                    date  of redemption. In addition,  in the event that the
                                    Company receives  net  proceeds  from the  sale  of  its
                                    Common   Stock  in  either  an  Equity  Offering  or  an
                                    investment by one or more Strategic Equity Investors  on
                                    or  prior to             , 1999, the Company may, at its
                                    option, use all or a portion of any such net proceeds to
                                    redeem up  to a  maximum  of 33  1/3% of  the  initially
                                    outstanding  aggregate principal  amount at  maturity of
                                    the Notes at  a redemption  price equal to     % of  the
                                    Accreted Value of the Notes; PROVIDED that not less than
                                    66  2/3%  of the  initially outstanding  aggregate prin-
                                    cipal amount at maturity of the Notes remain outstanding
                                    following such redemption. See "Description of Notes  --
                                    Redemption -- Optional Redemption."
</TABLE>
 
                                       6
<PAGE>
 
<TABLE>
<S>                                 <C>
Change in Control.................  Upon  the occurrence of a Change in Control, the Company
                                    is  obligated  to   make  an  offer   to  purchase   all
                                    outstanding Notes at a price of (i) 101% of the Accreted
                                    Value   thereof,   if   such   purchase   is   prior  to
                                                , 2001, or (ii) 101% of the principal amount
                                    at maturity thereof, plus  accrued interest thereon,  if
                                    any,  to the date of purchase, if such purchase is on or
                                    after              , 2001. See "Description of Notes  --
                                    Certain Covenants -- Change in Control." There can be no
                                    assurance  that the  Company will  have sufficient funds
                                    available at  the  time  of any  Change  in  Control  to
                                    purchase  all Notes tendered. See  "Risk Factors -- Risk
                                    of Inability to Satisfy Change in Control Offer."
Ranking...........................  The Notes will represent unsecured senior obligations of
                                    the Company, will  rank PARI PASSU  in right of  payment
                                    with  all existing and future senior Indebtedness of the
                                    Company and will rank senior in right of payment to  all
                                    existing  and  future subordinated  Indebtedness  of the
                                    Company. At  December 31,  1995, on  a pro  forma  basis
                                    after  giving  effect  to  indebtedness  incurred  after
                                    December 31, 1995, the Offerings and the application  of
                                    the  net  proceeds  therefrom,  the  aggregate principal
                                    amount of senior Indebtedness of the Company  (excluding
                                    trade payables, other accrued liabilities and the Notes)
                                    was approximately $4.0 million, which consisted of notes
                                    payable  arising from the acquisition  of the EMI Assets
                                    and the  Equipment Note.  The Indenture  will limit  the
                                    ability  of the  Company and  its subsidiaries  to incur
                                    additional indebtedness. See "Description of Notes"  and
                                    "Description of Certain Indebtedness."
Original Issue Discount...........  The  Notes  are  being  offered  at  an  original  issue
                                    discount for United States federal income tax  purposes.
                                    Thus,  although cash interest will not be payable on the
                                    Notes prior to                  ,  2001, original  issue
                                    discount (I.E., the difference between the principal and
                                    interest  payable on  the Notes  and their  issue price)
                                    will accrue from the issue date of the Notes and will be
                                    included as interest income periodically (including  for
                                    periods  ending prior to              , 2001) in a Note-
                                    holder's gross income for  United States federal  income
                                    tax  purposes in advance of receipt of the cash payments
                                    to  which  the  income  is  attributable.  See  "Certain
                                    Federal Income Tax Considerations."
Certain Covenants.................  The  Indenture  will  contain  certain  covenants which,
                                    among other  things, will  restrict the  ability of  the
                                    Company  and its Restricted Subsidiaries (as defined) to
                                    (i) incur indebtedness or issue certain preferred stock,
                                    (ii) pay dividends or  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 certain businesses 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. These
                                    covenants are subject to important exceptions and quali-
                                    fications.  See   "Description  of   Notes  --   Certain
                                    Covenants."
</TABLE>
 
                                       7
<PAGE>
 
<TABLE>
<S>                                 <C>
THE WARRANTS
Warrants..........................  Warrants   which,  when  exercised,  would  entitle  the
                                    holders thereof to purchase an aggregate of       shares
                                    of Common  Stock  of  the  Company  ("Warrant  Shares"),
                                    representing  approximately    %  of the Common Stock of
                                    the Company on a fully diluted basis.
Registration Rights...............  The Company has agreed, subject to certain  limitations,
                                    that,  from   days after  the date of issuance until the
                                    expiration  of  all  Warrants,  it  will  maintain   the
                                    effectiveness  of a registration  statement with respect
                                    to the issuance of the  Warrant Shares upon exercise  of
                                    the Warrants.
Separation Date...................  The  Notes and the Warrants  will not be separable until
                                    the earlier of (i)         , 1996 and (ii) such date  as
                                    the   Underwriters  may,   in  their   discretion,  deem
                                    appropriate.
Exercise..........................  Each Warrant will entitle the holder thereof, subject to
                                    certain conditions, to purchase        shares of  Common
                                    Stock  at an exercise price of $      per share, subject
                                    to adjustment under certain circumstances. The  Warrants
                                    will   be   exercisable  at   any   time  on   or  after
                                                , 1996 and  prior to the  expiration of  the
                                    Warrants,  as set  forth below.  The exercise  price and
                                    number of shares of Common Stock issuable upon  exercise
                                    of  the Warrants will be subject to adjustment from time
                                    to time upon the occurrence of certain changes with  re-
                                    spect   to   the   Common   Stock,   including   certain
                                    distributions of shares  of Common  Stock, issuances  of
                                    options   or   convertible  securities,   dividends  and
                                    distributions  and  certain   changes  in  options   and
                                    convertible  securities of  the Company.  A Warrant does
                                    not entitle the holder thereof to receive any  dividends
                                    paid on shares of Common Stock.
Expiration........................  , 2006.
</TABLE>
 
    For additional information concerning the Units, the Notes, the Warrants and
the  Common Stock, and the definitions  of certain capitalized terms used above,
see "Description of  Units," "Description of  Notes," "Description of  Warrants"
and "Description of Capital Stock."
 
                              CONCURRENT OFFERING
 
    Concurrently  with the Unit Offering, the Company is offering, pursuant to a
separate prospectus,        shares of Common  Stock of the Company (the  "Common
Stock Offering" and, together with the Unit Offering, the "Offerings"). The Unit
Offering is conditioned upon the consummation of the Common Stock Offering.
 
                                  RISK FACTORS
 
    An  investment in the Units  offered hereby involves a  high degree of risk.
See "Risk Factors" commencing on page 10 hereof.
 
                                       8
<PAGE>
              SUMMARY HISTORICAL AND PRO FORMA FINANCIAL DATA (1)
<TABLE>
<CAPTION>
                                                                          YEAR ENDED DECEMBER 31, 1995
                                                               ---------------------------------------------------
                                                                 HISTORICAL                          PRO FORMA
                                                                COMBINED (2)    PRO FORMA (3)     AS ADJUSTED (4)
                                                               --------------  ----------------  -----------------
<S>                                                            <C>             <C>               <C>
STATEMENT OF OPERATIONS DATA:
Operating revenue............................................  $        5,793   $        5,793     $
Non-cash compensation expense................................       1,089,605          287,603
Depreciation and amortization................................          60,060          191,466
Net loss.....................................................       3,234,843        5,104,952
Pro forma net loss per share of Common Stock (5).............
Weighted average number of shares of Common Stock outstanding
 (5).........................................................
OTHER FINANCIAL DATA:
EBITDA (6)...................................................  $   (1,936,141)  $   (2,187,139)    $
Capital expenditures.........................................       3,585,144        3,585,144
 
<CAPTION>
                                                                             AS OF DECEMBER 31, 1995
                                                               ---------------------------------------------------
                                                                 HISTORICAL                          PRO FORMA
                                                                COMBINED (2)    PRO FORMA (3)     AS ADJUSTED (4)
                                                               --------------  ----------------  -----------------
<S>                                                            <C>             <C>               <C>
 
BALANCE SHEET DATA:
Working capital surplus (deficit)............................  $   (3,008,510)  $    6,577,942     $
Property and equipment, net..................................       3,581,561        3,581,561
FCC licenses.................................................       4,235,734        4,235,734
Total assets.................................................       9,876,559       19,164,915
Long-term debt, including current portion....................       6,450,000        7,361,439
Total stockholders' equity (deficit).........................        (312,860)       8,175,439
</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  its predecessor ART Corp.  and the notes thereto  and
    the  unaudited  pro  forma  condensed  financial  statements  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  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 ART Corp.
    had  been  combined  and reflect  (i)  the elimination  of  transactions and
    balances between ART and ART Corp.  and (ii) the elimination of ART  Corp.'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 January  1,
    1995 for the Statement of Operations Data and Other Financial Data and as of
    December  31,  1995 for  the Balance  Sheet  Data: (i)  the exchange  of the
    Advent/ART Securities (as defined), including accrued interest, into 232,826
    shares of Preferred  Stock (which  convert into 3,026,738  shares of  Common
    Stock  upon consummation of  the Offerings) and  related anti-dilution share
    adjustments, net of deferred  financing costs; (ii)  the issuance of  48,893
    shares of Preferred Stock (which convert into 635,609 shares of Common Stock
    upon  consummation of the Offerings) and  the Ameritech Warrant (as defined)
    to Ameritech in exchange for $2.3 million in cash proceeds and the Ameritech
    Strategic  Distribution  Agreement,  after  deducting  related  expenses  of
    $150,000,  and the recognition of a  $1.1 million market development expense
    for the value  ascribed to the  Ameritech Strategic Distribution  Agreement;
    (iii)  the receipt of $4.9 million in cash proceeds from the issuance of the
    Bridge Notes (as defined) and the Bridge Warrants (as defined) in connection
    with the Bridge Financing (as defined), after deducting related expenses  of
    $50,000; (iv) the receipt of $2.2 million in cash proceeds from the issuance
    of the Equipment Note and Indemnity Warrants (as defined) in connection with
    the  Equipment  Financing (as  defined),  after deducting  related  fees and
    expenses of  $225,000; and  (v) the  effects of  the Merger,  including  the
    issuance  of Common Stock to ART  Corp. stockholders and the cancellation of
    all outstanding ART Corp. common stock. The Statement of Operations Data and
    Other Financial Data under the caption "Pro Forma" also reflect the reversal
    of a non-recurring $802,002 non-cash  compensation expense from the  release
    of  Escrow  Shares (as  defined) in  November 1995.  The Balance  Sheet Data
    reflects a non-cash compensation expense of $6.8 million from the release of
    Escrow Shares in February 1996. 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  January  1, 1995  for  the
    Statement of Operations Data and Other Financial Data and as of December 31,
    1995 for the Balance Sheet Data: (i) the sale by the Company of       shares
    of  Common Stock offered  in the Common  Stock Offering based  on an assumed
    initial public offering price of $       per share and the Units offered  in
    the  Unit  Offering,  and,  in  each  case,  after  deducting  the estimated
    underwriting discount  and  offering  expenses, and  (ii)  the  receipt  and
    application of the net proceeds therefrom. 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  issuance   of  potentially   dilutive
    instruments issued within one year prior to the Offerings at exercise prices
    below  the assumed initial  public offering price and  the conversion of all
    outstanding shares of Preferred Stock into shares of Common Stock.
(6) EBITDA means loss before interest expense, income tax expense,  depreciation
    and amortization expense and non-cash compensation 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, 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.
 
                                       9
<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  UNITS
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 its operating  systems. The Company  currently
provides  wireless broadband services on a limited basis in nine 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)
acquire  appropriate sites for its operations, (ii) deploy its 38 GHz technology
on a market-by-market basis, (iii) capture and retain an adequate customer  base
and  (iv)  develop  its operational  and  support systems.  Given  the Company's
limited operating history, there  can be no  assurance that it  will be able  to
overcome  these  barriers, 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, the  Company reported  a net  loss and  negative
EBITDA  of  $3.2  million  and  $1.9  million,  respectively.  See "Management's
Discussion and Analysis of Financial  Condition and Results of Operations."  The
Company expects to incur significant additional expenses and operating losses as
the  development  and expansion  of its  wireless broadband  business continues.
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. 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 over a sustainable period.
 
    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  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
 
                                       10
<PAGE>
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.
 
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. There  can be  no assurance  that the  Company will  be able  to
compete  effectively in any  of its market areas.  The Company faces significant
competition from other 38 GHz providers and incumbent LECs, such as the Regional
Bell Operating Companies ("RBOCs"). To a lesser extent, the Company may  compete
with  CAPs,  cable  television  operators,  electric  utilities,  LECs operating
outside their current local service areas and IXCs.
 
    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 certain cases,  these service  providers hold  licenses to  operate on  other
portions  of the 38 GHz band in  geographic areas which encompass or overlap the
Company's market areas. In a number of the Company's market areas, at least  one
other  38 GHz  service provider  has 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 five other entities have been granted 38 GHz authorizations
in geographic regions in which the Company plans to operate. Due to the relative
ease  and  speed of  deployment of  38  GHz technology,  the Company  could face
intense price  competition from  other 38  GHz service  providers.  Accordingly,
there  can be no assurance that the Company will be able to sustain a profitable
business in the face of prolonged price competition.
 
    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 the  lower 16 channels in  the 38 GHz spectrum band,
which have  not been  previously  available for  commercial  use. The  grant  of
additional  licenses 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  the adoption  of  the NPRM  as currently
proposed, additional entities  having greater resources  than the Company  could
acquire  licenses  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,
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) establishes  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 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
 
                                       11
<PAGE>
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.  To a  lesser degree, 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.
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 and  IXCs. 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.
 
    A  number 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 electromagnetic spectrum  (I.E.,
wireless   services)  and   has  exclusive  jurisdiction   over  all  interstate
telecommunications services that originate in one state and terminate in another
state or foreign  country. 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 issuing permits. See
"Business -- Government Regulation."
 
                                       12
<PAGE>
    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. Challenges to its applications for authorizations or its tariffs
by third  parties  could  cause  the Company  to  incur  substantial  legal  and
administrative expenses.
 
    In its provision of local wireless broadband services, the Company currently
is  not  subject  to rate  regulation  by the  FCC,  but is  subject  to minimal
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
licenses.  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 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.  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 may then be dismissed. Final  rules issued in connection with the  NPRM
may require that 38 GHz service providers share other unlicensed 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. 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  business of  ART  West (as  defined) and  DCT (as
defined) pursuant to service agreements. See "Business -- Agreements Relating to
Licenses and Authorizations." The Company believes that the provisions of  these
service  agreements and the ART Corp. Service Agreement (as defined) 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 arrangements will, if  challenged, be found to
satisfy the Commission's policies or what  modifications may need to be made  to
satisfy those policies.
 
RISK OF FORFEITURE, NON-RENEWAL AND FLUCTUATION IN VALUE OF FCC LICENSES
 
    The  Company owns or  manages 35 licenses and  an additional 73 construction
permits granted by the  FCC to construct and  operate 38 GHz wireless  broadband
facilities  in 91  market areas.  Under current FCC  rules, the  recipient of an
authorization (initially, a "construction  permit") for microwave facilities  is
required  to complete  construction of such  facilities within 18  months of the
date of  grant  of  the  permit.  To  satisfy  the  FCC's  current  construction
requirements,   the  permit  holder  is  required  to  establish  at  least  one
transmission link between  two transceivers  in each  market area  for which  it
holds  a  construction permit.  Upon completion  of  construction and  filing of
evidence thereof with the FCC, the
 
                                       13
<PAGE>
permit develops into a license to provide microwave services. In the event  that
the  recipient fails  to comply  with the  construction deadline,  the permit is
subject to forfeiture, absent an extension of the deadline. Of the Company's 108
authorizations, 35  have  developed  into  licenses.  Under  the  terms  of  its
remaining  73 construction  permits, the  Company must  complete construction of
facilities for  approximately 50  construction  permits between  mid-August  and
mid-September 1996. 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 such facilities using  the
proceeds  of the Offerings  within such time  limits, there can  be no assurance
that it will be  able to do so  or that the FCC  will not impose more  stringent
construction  requirements with which the Company will be unable to comply. 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."
 
    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 renew all such licenses for a matching ten-year period.
All of the Company's 38 GHz licenses 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   has
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  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 could be materially adversely affected.
 
    The Company plans to use its licenses to develop wireless broadband  systems
in  all of its market areas. In  addition, a limited secondary market exists for
38 GHz licenses, and the Company may  from time to time purchase such  licenses.
The   value  of  licenses  held  or  acquired  hereafter  by  the  Company  will
significantly depend  upon  the  success of  the  Company's  wireless  broadband
operations, fluctuations in the level of supply and demand for such licenses and
the  telecommunications industry's response to  the availability and efficacy of
wireless broadband systems. In addition, federal and state regulations limit the
liquidity of  such licenses.  Assignments  of licenses  and changes  of  control
involving  entities  holding licenses  require  prior FCC  and  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 licenses may adversely affect the value of the Company's licenses.
 
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.
 
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
 
                                       14
<PAGE>
intermediate links to overcome obstructions or rain fades 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. 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
local demographic characteristics in each market. Other 38 GHz service providers
may have larger geographic footprints encompassing the Company's market areas or
more bandwidth (I.E., more than one 100 MHz channel) in certain market areas. 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  from  a single  supplier, P-Com,  Inc. and  recently entered  into an
equipment  purchase  agreement   with  Harris   Corporation,  Farinon   Division
("Harris").  Any reduction or interruption in  supply from either supplier could
have a disruptive effect on the  Company until alternative supply sources  begin
shipping  their products  to 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.
 
DEPENDENCE ON THIRD PARTIES FOR MARKETING AND SERVICE
 
    The Company  is  largely dependent  upon  third parties  for  marketing  its
services  and maintaining its operational  systems. The Company recently entered
into an agreement with Ameritech 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 do so could have  an adverse effect on  the
Company's development and results of operations.
 
ACQUISITION OF ADDITIONAL BANDWIDTH IN SELECTED AREAS
 
    The  Company believes  that it generally  owns or manages  sufficient 38 GHz
bandwidth  to  satisfy  the  anticipated  service  requirements  of  its  target
customers in the Company's existing 91 market areas. Nevertheless, the Company's
future  plans include the acquisition of 38 GHz bandwidth in selected geographic
areas in  order to  expand and  enhance its  services by  leasing or  purchasing
channels  from other 38 GHz providers or by applications to the FCC. The Company
believes that these additional
 
                                       15
<PAGE>
channels will be  available by virtue  of (i)  the obligations of  other 38  GHz
service  providers as common carriers to make bandwidth available, (ii) the need
of 38 GHz construction permit holders to meet FCC construction requirements, and
(iii) FCC  auctions of  and other  licensing procedures  for additional  38  GHz
licenses.  However, there can be  no assurance that access  to additional 38 GHz
licenses will be acquired on favorable terms, if at all.
 
NEW SERVICES; TECHNOLOGICAL CHANGE
 
    The  telecommunications   industry   has   been   characterized   by   rapid
technological  advances, changes in end  user requirements, frequent new service
introductions and evolving industry standards. 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  or
(iii) the Company's inventory of equipment will not be rendered obsolete.
 
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.
 
                                FINANCIAL RISKS
 
SIGNIFICANT CAPITAL REQUIREMENTS; UNCERTAINTY OF ADDITIONAL FINANCING
 
    The Company will  require substantial investment  capital for the  continued
development  and expansion of  its wireless broadband  operations, the continued
funding  of  related  operating  expenses,  and  the  possible  acquisition   of
additional  licenses, other  assets or other  businesses. Management anticipates
that, based  on its  current  plan of  development,  assuming that  no  material
acquisitions  are consummated,  the net proceeds  of the  Offerings and existing
financial resources, after repayment of  approximately $5.0 million of  existing
indebtedness,  will be sufficient to  fund the operations of  the Company for at
least the next two years. Management believes that the Company's future  capital
needs  will continue  to be significant  and that  after such period  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 or (iii) the Company completes any material acquisitions, 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.
 
RANKING; SIGNIFICANT SECURED INDEBTEDNESS
 
    The Notes will represent general unsecured senior obligations of the Company
and will rank senior in right of payment to all existing and future subordinated
indebtedness of the Company. Subject  to certain exceptions, the Indenture  will
limit   the   ability   of   the  Company   and   its   subsidiaries   to  incur
 
                                       16
<PAGE>
additional indebtedness.  However,  under the  Indenture,  the Company  will  be
permitted  to incur senior secured  indebtedness under certain circumstances. If
the Company  becomes  insolvent  or is  liquidated  or  if any  of  its  secured
indebtedness  is accelerated, the holders of  such secured indebtedness would be
entitled to payment in full out  of the assets securing such indebtedness  prior
to  payment to holders of the Notes. If the lenders party to, or the holders of,
any secured  indebtedness  were to  foreclose  on the  collateral  securing  the
Company's  obligations to them,  there can be  no assurance that  there would be
sufficient assets remaining after  payment of all  such secured indebtedness  to
satisfy the claims of holders of the Notes in full. See "Description of Notes --
Certain Covenants" and "Description of Certain 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 December 31, 1995, on a pro  forma
basis after giving effect to the Offerings as if they had occurred on that date,
the  Company would have had approximately $          million of total debt and a
stockholders' equity  of approximately  $            million. In  addition,  the
accretion  of the  principal amount  of the  Notes over  time will  result in an
increase in the  total indebtedness  represented by the  Notes of  approximately
$        million by           , 2001. After giving effect to the Offerings as if
they  had occurred on January 1, 1995,  the Company's pro forma earnings for the
fiscal year ended December 31, 1995 would have been insufficient to cover  fixed
charges by approximately $        .
 
    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  be required  to  be
dedicated  to the payment of  principal and 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 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; and  (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. Some of these  factors are beyond the control of  the
Company.  See "Unaudited  Pro Forma  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, the
Indenture  limits,  but  does  not   prohibit,  the  incurrence  of   additional
indebtedness  by the  Company and  its subsidiaries,  and the  Company may 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  Notes  --  Certain  Covenants."  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.
 
    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
 
                                       17
<PAGE>
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 Notes -- Certain
Covenants."
 
ORIGINAL ISSUE DISCOUNT
 
    The Notes will be issued at a substantial original issue discount from their
principal amount at maturity. Consequently, purchasers of Notes will 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. In addition, a
portion of the purchase price  for each Unit will  be allocable to the  Warrants
for federal income tax purposes. See "Certain Federal Income Tax Considerations"
for  a more detailed  discussion of the  federal income tax  consequences to the
purchasers of the Units  resulting from the  purchase, ownership or  disposition
thereof.
 
    If  a bankruptcy case is commenced by  or against the Company under Title 11
of the United States Code, as amended (the "Bankruptcy Code") after the issuance
of the Units, the claim of a holder  of the Notes with respect to the  principal
amount  thereof may be limited to an amount  equal to the sum of (i) the initial
public offering price of the Notes and  (ii) that portion of the original  issue
discount  that is not deemed to  constitute "unmatured interest" for purposes of
the Bankruptcy Code. Any original issue discount that was not accrued as of such
bankruptcy filing would constitute "unmatured interest." A holder of a Note will
not have any claim  with respect to that  portion of the issue  price of a  Unit
allocated to the Warrants issued as part of such Unit.
 
RISK OF INABILITY TO SATISFY CHANGE IN CONTROL OFFER
 
    Upon  the occurrence of a Change in Control, the Company will be required to
make an offer to purchase  all of the outstanding Notes  at a purchase price  in
cash  equal to (i) 101% of  the Accreted Value thereof, in  the case of any such
purchase prior to       , 2001, or (ii) 101% of the principal amount at maturity
thereof, together  with accrued  and unpaid  interest, if  any, to  the date  of
purchase,  in the case of any such purchase on or after        , 2001. There can
be no assurance that the Company will have the funds necessary to effect such  a
purchase if such an event were to occur. In the event a Change in Control occurs
at  a time when the  Company is unable to purchase  the Notes, the Company could
seek to refinance the Notes. If  the Company is unsuccessful in refinancing  the
Notes,  the Company's  failure to  purchase tendered  Notes would  constitute an
Event of  Default under  the Indenture.  See "Description  of Notes  --  Certain
Covenants -- Change in Control."
 
                            LEGAL AND TRADING RISKS
 
ABSENCE OF PUBLIC MARKET; POSSIBLE VOLATILITY OF STOCK PRICE
 
    There  is  currently  no public  market  for  the Units,  the  Notes  or the
Warrants. The Company does  not intend to  apply for listing  of the Units,  the
Notes  or the Warrants on any securities exchange or for quotation of the Units,
the Notes or the Warrants  on the Nasdaq National  Market. The Company has  been
advised  by the Underwriters that they presently  intend to make a market in the
Units, the  Notes  and  the  Warrants,  as  permitted  by  applicable  laws  and
regulations,  after  the consummation  of the  sale of  the Units;  however, the
Underwriters are not obligated to do so and any such market- making activity may
be discontinued  at any  time without  notice  at the  sole discretion  of  each
Underwriter.  Accordingly, there  can be  no assurance  as to  whether an active
public market for the  Units, the Notes  or the Warrants will  develop or, if  a
public  market does develop, as  to the liquidity of  the trading market for the
Units, the Notes or the Warrants. If  an active public market does not  develop,
the  market price and liquidity for the Units,  the Notes or the Warrants may be
adversely affected. See "Underwriting."
 
    Prior to the Offerings,  there has been no  public market for the  Company's
Common  Stock. While the Company  is applying for quotation  of the Common Stock
(including the Warrant Shares)  on the Nasdaq National  Market, there can be  no
assurance   that   an   active   public   trading   market   will   develop   or
 
                                       18
<PAGE>
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 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 Company's Common Stock to fluctuate, perhaps substantially.
 
CONTROL BY MANAGEMENT AND PRINCIPAL STOCKHOLDERS
 
    Upon   completion  of  the  Offerings,  the  Company's  executive  officers,
directors and their affiliates, as  a group will beneficially own  approximately
   %  of  the Company's  outstanding Common  Stock (     % if  the Underwriters'
over-allotment option is  exercised in  full). 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  Notes  --  Certain
Covenants."
 
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  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. 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 approximately  9,650,000 shares of Preferred Stock and
to fix the rights, privileges and preferences of such shares without any further
vote or action  by the stockholders.  However, the terms  of the Indenture  will
restrict  the ability  of the  Company to issue  shares of  Preferred Stock. See
"Description of Notes -- Certain Covenants." 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."
 
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 completion of the
 
                                       19
<PAGE>
Offerings,  the Company will have  outstanding           shares of Common Stock,
assuming  no  exercise  of  outstanding  options,  warrants,  rights  or   other
convertible securities. Beginning March 28, 1997, approximately 8,101,080 shares
of  Common Stock will become available for sale in the public market pursuant to
Rule 144 under the Securities Act, subject in certain cases to volume and  other
resale limitations under Rule 144. 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.
Holders  of 30,085,783 shares of Common Stock and warrants to purchase 1,425,000
shares of Common Stock have contractual  rights to have those shares  registered
with the Securities and Exchange Commission for resale to the public.
 
                                       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 91 market areas 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 Corp."), 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., 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 Corp. and ART on a joint basis.  In
April  1995, ART  Corp. 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.  See
"Business  -- Agreements  Relating to  Licenses and  Authorizations --  ART West
Joint Venture" and " -- EMI Acquisition."
 
    To date, ART has operated and managed  its business and the business of  ART
Corp.  (including all FCC  licenses and construction permits  held by ART Corp.)
pursuant to the ART Corp. Services Agreement (as defined). On February 2,  1996,
ART  and ART Corp. entered  into the Merger Agreement  (as defined), pursuant to
which ART Corp.  will merge with  and into  ART, subject only  to FCC  approval.
Prior  to the  receipt of the  FCC's approval,  ART will continue  to manage the
combined businesses of itself and ART Corp. in accordance with the terms of  the
ART  Corp. Services Agreement. See "Business  -- Agreements Relating to Licenses
and Authorizations -- ART Corp. Services Agreement."
 
    DIGIWAVE, ART and ADVANCED RADIO TELECOM are trademarks 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.
 
                                USE OF PROCEEDS
 
    The  net proceeds  to the  Company from the  Offerings, based  on an assumed
initial public offering price  of $          per share  and after deducting  the
estimated  underwriting  discount and  offering  expenses, are  estimated  to be
approximately $   million. Of  the net proceeds, approximately $90.0 million  is
expected  to  be  used  for  capital  expenditures,  including  the  purchase of
equipment and the  acquisition of  certain spectrum  rights. Approximately  $5.0
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. See "Certain  Transactions" and "Description  of Certain Indebtedness  --
Bridge  Notes."  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  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 DCT Agreements  (as defined), has been reached  with
respect to any acquisition.
                                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  Notes  -- Certain
Covenants -- Restricted Payments."
 
                                       21
<PAGE>
                                 CAPITALIZATION
 
    The following  table sets  forth the  capitalization of  the Company  as  of
December  31, 1995  (i) on  a historical  combined basis,  giving effect  to the
elimination of  balances between  ART  and its  predecessor  ART Corp.  and  the
elimination  of ART Corp.'s investment in ART, (ii) on a pro forma basis, giving
effect  to  the  Merger  and  certain  other  financing  transactions  occurring
subsequent  to December 31, 1995  as specified in Note 1  hereto, and (iii) on a
pro forma  as adjusted  basis,  giving effect  to the  sale  by the  Company  of
        shares  of Common Stock offered in the Common Stock Offering based on an
assumed initial public  offering price of  $           per share  and the  Units
offered  in  the Unit  Offering,  in each  case,  after deducting  the estimated
underwriting discount and offering expenses, the receipt and application of  the
net  proceeds  therefrom,  and  the  conversion  of  all  outstanding  shares of
Preferred Stock  into  shares  of  Common Stock.  See  "Use  of  Proceeds."  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
historical financial  statements and  unaudited  pro forma  condensed  financial
statements of the Company appearing elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                            AS OF DECEMBER 31, 1995
                                                              ----------------------------------------------------
                                                                HISTORICAL                           PRO FORMA
                                                                 COMBINED       PRO FORMA (1)       AS ADJUSTED
                                                              --------------  ------------------  ----------------
<S>                                                           <C>             <C>                 <C>
Cash and cash equivalents...................................  $      633,654  $    10,153,654     $
                                                              --------------  ------------------  ----------------
                                                              --------------  ------------------  ----------------
Long-term debt:
  Note payable to EMI.......................................  $    1,500,000  $     1,500,000
  Convertible notes payable.................................       4,950,000          --
  Bridge Notes..............................................        --              3,950,000
  Equipment Note............................................        --              1,911,439
  Senior Discount Notes due 2006............................        --                --
                                                              --------------  ------------------  ----------------
    Total long-term debt....................................       6,450,000        7,361,439
                                                              --------------  ------------------  ----------------
ART Corp. Redeemable Preferred Stock........................          44,930          --
                                                              --------------  ------------------  ----------------
Stockholders' equity (deficit):
  Convertible Serial Preferred Stock (2)....................             488              921
  ART Corp. common stock (3)................................               3          --
  Common Stock (4)..........................................          15,291           18,114
  Additional paid-in capital................................       3,041,415       19,374,975
  Deficit accumulated during the development stage..........      (3,370,057)     (11,218,571)
                                                              --------------  ------------------  ----------------
    Total stockholders' equity (deficit)....................        (312,860)       8,175,439
                                                              --------------  ------------------  ----------------
      Total capitalization..................................  $    6,182,070  $    15,536,878     $
                                                              --------------  ------------------  ----------------
                                                              --------------  ------------------  ----------------
</TABLE>
 
- ------------------------
(1)  Reflects  pro forma adjustments  for the following  transactions as if they
     had occurred as of  December 31, 1995: (i)  the exchange of the  Advent/ART
     Securities,  including accrued  interest, into 232,826  shares of Preferred
     Stock  (which  convert   into  3,026,738  shares   of  Common  Stock   upon
     consummation   of  the  Offerings)  and  the  related  anti-dilution  share
     adjustments; (ii) the issuance of  48,893 shares of Preferred Stock  (which
     convert  into  635,609  shares of  Common  Stock upon  consummation  of the
     Offerings) and  the Ameritech  Warrant to  Ameritech in  exchange for  $2.3
     million   in  cash  proceeds  and   the  Ameritech  Strategic  Distribution
     Agreement,  after  deducting   related  expenses  of   $150,000,  and   the
     recognition  of a  $1.1 million  market development  expense for  the value
     ascribed to  the  Ameritech  Strategic Distribution  Agreement;  (iii)  the
     receipt  of $4.9 million in  cash proceeds from the  issuance of the Bridge
     Notes and Bridge Warrants  in connection with  the Bridge Financing,  after
     deducting  related expenses of $50,000; (iv) 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; and (v) the effects of the Merger,  including
     the issuance of Common Stock to ART Corp. stockholders and the cancellation
     of all outstanding ART Corp. common stock. See "Certain Transactions."
 
(2)  Consists  of ART  Convertible Serial Preferred  Stock, $.001  par value per
     share: 10,000,000 shares authorized; historical combined -- 334,943  shares
     of  Series A, 86,507 shares  of Series B, 5,402  shares of Series C, 61,640
     shares of Series D issued and  outstanding; pro forma -- 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 (which convert into an aggregate 11,972,363 shares
     of  Common Stock upon consummation of the Offerings); pro forma as adjusted
     -- no shares issued and outstanding.
 
(3)  Consists of ART Corp. common stock, $.01 par value per share: 2,000  shares
     authorized;  historical combined -- 340  shares 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: 60,000,000  shares
     authorized;   historical   combined   --  15,291,211   shares   issued  and
     outstanding; pro forma  -- 18,114,135  shares issued  and outstanding;  pro
     forma as adjusted --               shares issued and outstanding.
 
                                       22
<PAGE>
                SELECTED HISTORICAL AND PRO FORMA FINANCIAL DATA
 
ART
 
    The selected historical financial data below under the captions Statement of
Operations  Data,  Other  Financial  Data and  Balance  Sheet  Data  present the
financial data of ART as of December 31, 1995 and for the period from March  28,
1995 (date of inception) to December 31, 1995. Such selected financial data were
derived  from  and should  be  read in  conjunction  with the  audited financial
statements of ART included elsewhere in this Prospectus.
 
    The unaudited  selected historical  combined and  pro forma  financial  data
presented below under the captions Statement of Operations Data, Other Financial
Data  and Balance Sheet Data for the year ended and as of December 31, 1995 were
derived from the  unaudited pro  forma condensed  financial statements  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
ART  Corp.,  and  the  notes  thereto, and  the  unaudited  pro  forma condensed
financial  statements,  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 year  ended December 31, 1995, nor  do they purport to  represent
the Company's future financial position and results of operations.
<TABLE>
<CAPTION>
                                           MARCH 28, 1995
                                              (DATE OF
                                             INCEPTION)
                                                 TO                     YEAR ENDED DECEMBER 31, 1995
                                         DECEMBER 31, 1995   ---------------------------------------------------
                                         ------------------    HISTORICAL                        PRO FORMA AS
                                             HISTORICAL       COMBINED (1)    PRO FORMA (2)      ADJUSTED (3)
                                         ------------------  --------------  ----------------  -----------------
<S>                                      <C>                 <C>             <C>               <C>
STATEMENT OF OPERATIONS DATA:
Operating revenue......................    $        5,793    $        5,793   $        5,793     $
Non-cash compensation expense..........         1,089,605         1,089,605          287,603
Depreciation and amortization..........             5,306            60,060          191,466
Net loss...............................         2,981,073         3,234,843        5,104,952
Pro forma net loss per share of Common
 Stock (4).............................
Pro forma weighted average number of
 shares of Common Stock outstanding
 (4)...................................
 
OTHER FINANCIAL DATA:
EBITDA (5).............................    $   (1,798,327)   $   (1,936,141)  $   (2,187,139)    $
Capital expenditures...................         3,585,144         3,585,144        3,585,144
Ratio of earnings to fixed charges
 (6)...................................          --                --               --
 
<CAPTION>
 
                                                                 AS OF DECEMBER 31, 1995
                                         -----------------------------------------------------------------------
                                                               HISTORICAL                        PRO FORMA AS
                                             HISTORICAL       COMBINED (1)    PRO FORMA (2)      ADJUSTED (3)
                                         ------------------  --------------  ----------------  -----------------
<S>                                      <C>                 <C>             <C>               <C>
BALANCE SHEET DATA:
Working capital surplus (deficit)......    $   (2,031,947)   $   (3,008,510)  $    6,577,942     $
Property and equipment, net............         3,579,838         3,581,561        3,581,561
FCC licenses...........................         4,226,821         4,235,734        4,235,734
Total assets...........................         9,830,615         9,876,559       19,164,915
Long-term debt, including current
 portion...............................         6,500,000         6,450,000        7,361,439
Redeemable preferred stock.............          --                  44,930         --
Deficit accumulated during the
 development stage.....................        (2,981,073)       (3,370,057)     (11,218,571)
Total stockholders' equity (deficit)...          (119,922)         (312,860)       8,175,439
</TABLE>
 
                                       23
<PAGE>
ART CORP. -- PREDECESSOR
 
    The selected financial data below under the captions Statement of Operations
Data,  Other Financial Data and Balance Sheet Data present the financial data of
ART's predecessor ART Corp. for the years ended and as of December 31, 1995  and
1994,  for the period from  August 23, 1993 (date  of inception) to December 31,
1993, and as of December 31, 1993. The selected financial data were derived from
and should be read in conjunction  with the audited financial statements of  ART
Corp. included elsewhere in this Prospectus.
<TABLE>
<CAPTION>
                                                       AUGUST 23, 1993
                                                           (DATE OF
                                                          INCEPTION)
                                                              TO              YEAR ENDED          YEAR ENDED
                                                      DECEMBER 31, 1993   DECEMBER 31, 1994   DECEMBER 31, 1995
                                                      ------------------  ------------------  ------------------
 
<S>                                                   <C>                 <C>                 <C>
STATEMENT OF OPERATIONS DATA:
Operating revenue...................................                         $    137,489
Depreciation and amortization.......................      $      688                8,281       $       54,754
Net loss............................................           6,594              128,620            1,267,655
Net loss per share of common stock (4)..............           65.94               702.84             4,495.23
Weighted average number of shares of common stock
 outstanding (4)....................................             100                  183                  282
 
OTHER FINANCIAL DATA:
EBITDA (5)..........................................      $   (5,906)        $   (115,964)      $   (1,151,699)
Capital expenditures................................          --                    5,175             --
Ratio of earnings to fixed charges (6)..............          --                  --                  --
 
<CAPTION>
 
                                                                          AS OF DECEMBER 31,
                                                      ----------------------------------------------------------
                                                             1993                1994                1995
                                                      ------------------  ------------------  ------------------
<S>                                                   <C>                 <C>                 <C>
BALANCE SHEET DATA:
Working capital surplus (deficit)...................      $   13,958         $    (76,556)      $     (976,563)
Property and equipment, net.........................                                3,448                1,723
FCC licenses........................................                                                     8,913
Total assets........................................          74,513               42,611            5,784,624
Long-term debt, including current portion...........                                                 4,950,000
Redeemable preferred stock..........................          --                  --                    44,930
Deficit accumulated during the development stage....          (6,594)            (135,214)          (1,402,869)
Total stockholders' equity (deficit)................          54,542              (39,078)            (404,481)
</TABLE>
 
- ------------------------------
(1)  The  unaudited  selected  financial  data  under  the  caption  "Historical
     Combined" are presented as  if the historical  financial statements of  ART
     and  its predecessor,  ART Corp.,  had been  combined and  reflects (i) the
     elimination of transactions and balances between ART and ART Corp. and (ii)
     the elimination of ART Corp.'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 January 1,
     1995 for the Statement of Operations  Data and Other Financial Data and  as
     of  December 31, 1995 for  the Balance Sheet Data:  (i) the exchange of the
     Advent/ART Securities, including accrued  interest, into 232,826 shares  of
     Preferred  Stock (which convert into 3,026,738  shares of Common Stock upon
     consummation  of  the  Offerings)  and  the  related  anti-dilution   share
     adjustments,  net of deferred financing costs;  (ii) the issuance of 48,893
     shares of  Preferred Stock  (which convert  into 635,609  shares of  Common
     Stock  upon consummation  of the  Offerings) and  the Ameritech  Warrant to
     Ameritech in exchange for $2.3 million  in cash proceeds and the  Ameritech
     Strategic  Distribution  Agreement,  after  deducting  related  expenses of
     $150,000, and the recognition of a $1.1 million market development  expense
     for  the value ascribed to  the Ameritech Strategic Distribution Agreement;
     (iii) the receipt of $4.9 million in cash proceeds from the issuance of the
     Bridge Notes  and  the  Bridge  Warrants  in  connection  with  the  Bridge
     Financing, after deducting related expenses of $50,000; (iv) 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, and (v) the effects of the
     Merger,  including the issuance  of Common Stock  to ART Corp. stockholders
     and the  cancellation  of  all  outstanding ART  Corp.  common  stock.  The
     Statement  of Operations  Data and Other  Financial Data  under the caption
     "Pro Forma" also reflect the reversal of a non-recurring $802,002  non-cash
     compensation  expense from the  release of Escrow  Shares in November 1995.
     The Balance Sheet  Data reflects  a non-cash compensation  expense of  $6.8
     million  from the release  of Escrow Shares in  February 1996. See "Certain
     Transactions."
 
                                       24
<PAGE>
(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 January  1, 1995  for the
     Statement of Operations Data  and Other Financial Data  and as of  December
     31,  1995  for the  Balance  Sheet Data:  (i) the  sale  by the  Company of
             shares of Common Stock offered  in the Common Stock Offering  based
     on  an assumed initial public offering price of $         per share and the
     Units offered in the Unit Offering, and, in each case, after deducting  the
     estimated  underwriting discount and offering expenses and (ii) the receipt
     and application of the net proceeds therefrom. 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  issuance  of  potentially
     dilutive  instruments  issued within  one year  prior  to the  Offerings at
     exercise prices below  the assumed  initial public offering  price and  the
     conversion  of all  outstanding shares  of Preferred  Stock into  shares of
     Common Stock. Net loss per share for ART Corp. is based on the loss for the
     period divided by  the weighted average  number of shares  of common  stock
     outstanding during the period.
 
(5)  EBITDA means loss before interest expense, income tax expense, depreciation
     and  amortization  expense and  non-cash compensation  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, 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.
 
(6)  For  the purposes  of determining earnings  coverage of  fixed charges, net
     losses  include  fixed  charges   representing  interest  expense  on   all
     indebtedness  (including the amortization of deferred debt issuance costs).
     For the  purposes of  the  pro forma  combined information,  fixed  charges
     include  interest  expense  from  the Bridge  Financing  and  the Equipment
     Financing (including the amortization of deferred debt issuance costs), and
     the reversal of interest  expense on the Advent  Notes that were  converted
     into  ART Series E  Preferred Stock. For  the purposes of  the pro forma as
     adjusted information, fixed charges include  interest on the Notes  offered
     hereby,  offset by  the reversal  of interest  expense on  the Bridge Notes
     which are assumed to be repaid out of the proceeds therefrom. Earnings were
     deficient to cover fixed charges by  the following amounts for the  periods
     indicated:
 
<TABLE>
<S>                                                                                     <C>
ART
  March 28, 1995 (date of inception) to December 31, 1995.............................  $2,981,073
  Year ended December 31, 1995
    Historical combined...............................................................   3,234,843
    Pro forma.........................................................................   5,104,952
    Pro forma as adjusted.............................................................
ART Corp. -- Predecessor
    Year ended December 31, 1995......................................................   1,267,655
    Year ended December 31, 1994......................................................     128,620
    August 23, 1993 (date of inception) to December 31, 1993..........................       6,594
</TABLE>
 
                                       25
<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 1995 historical combined financial information of Advanced Radio
Telecom  Corp.  ("ART")  and   its  predecessor,  Advanced  Radio   Technologies
Corporation ("ART Corp."). The 1995 historical combined financial information is
based  upon the separate  historical financial statements of  ART as of December
31, 1995 and for the period from March 28, 1995 (date of inception) to  December
31,  1995 and of ART Corp.  as of and for the  year ended December 31, 1995, all
appearing elsewhere in  this Prospectus, after  elimination of transactions  and
balances  between the two entities as well as ART Corp.'s investment in ART. The
pre-1995 historical financial information is based upon the historical financial
statements of ART Corp. appearing elsewhere in the Prospectus.
 
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  authorizations and licenses, 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
authorizations  throughout the United States through the purchase of such rights
held  by  others  and  by  petitioning  the  FCC  directly.  Upon  meeting   FCC
construction  requirements, such authorizations are converted into licenses with
initial terms of  six years and  are renewable for  successive ten-year  periods
subject  to  review by  the  FCC. 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) acquire appropriate sites  for
its  operations, (ii) deploy its 38  GHz technology on a market-by-market basis,
(iii) capture and retain an adequate customer base and (iv) successfully develop
and deploy  its  operational  and  support systems.  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."
 
    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.  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 net losses and negative  operating
cash  flow  will  increase  as  the  Company  implements  its  growth  strategy.
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."
 
                                       26
<PAGE>
ACQUISITIONS, BUSINESS DEVELOPMENT AND CAPITAL EXPENDITURES
 
    From inception  through  December 31,  1995,  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 on property and equipment have
totalled $3.6 million. In addition,  the Company has incurred significant  other
costs  and  expenses in  the development  of these  businesses and  has recorded
cumulative losses from inception through December 31, 1995 of $3.4 million.  The
Company  may, when and if the  opportunity arises, acquire other spectrum rights
and,  potentially,  related  businesses,  invest  in  the  development  of   new
technologies and expand its wireless broadband services in new market areas.
 
    The   recoverability  of   property  and   equipment  and   capitalized  FCC
authorizations and 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, technological,
regulatory or other changes.
 
RESULTS OF OPERATIONS
 
    The Company  has generated  nominal revenue  from operations  to date.  From
inception through December 31, 1995, the Company has incurred aggregate expenses
of  $3.5 million, consisting  of compensation and  benefits, sales and marketing
expenses, consulting and  legal fees, facilities  expenses, billing and  systems
development costs and net interest expenses building its business infrastructure
and  marketing its  wireless broadband  services. See  "Risk Factors  -- Limited
Operations; History of Net Losses."
 
    FISCAL 1995 COMPARED TO FISCAL 1994
 
    ART's predecessor,  ART Corp.  was  formed in  1993, and,  accordingly,  the
Company's   historical  financial  statements  for   1994  reflect  ART  Corp.'s
activities in applying for 38 GHz licenses and building operating systems.
 
    The Company had $137,489 in consulting services income 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.  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 $1.1
million of non-cash compensation expenses associated with employee stock options
($287,603)  and an escrow  share arrangement ($802,002).  The Company expects to
recognize an additional  $6.8 million non-cash  charge in the  first quarter  of
1996 in connection with the termination of the escrow share arrangement. General
and  administrative  expenses, including  these non-cash  compensation expenses,
increased by $2.7 million  to $2.9 million for  fiscal 1995, from $261,734,  for
1994. Market development expenses increased to $191,693 in 1995 from $0 in 1994.
The  Company will recognize a $1.1 million non-cash charge to market development
expense in  the  first  quarter  of 1996  related  to  the  Ameritech  strategic
distribution agreement. 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.
 
LIQUIDITY AND CAPITAL RESOURCES
 
    The  Company's operations  have required substantial  capital investment for
the  acquisition  of  FCC   licenses  and  related   assets,  the  purchase   of
telecommunications  equipment and the development and expansion of the Company's
infrastructure to support  anticipated growth. From  inception through  December
31,  1995, the Company used $1.5 million of cash in its operating activities and
$4.2 million  of cash  in its  investing activities.  These cash  outflows  were
financed primarily through private equity
 
                                       27
<PAGE>
placements  and  the  issuance  of  convertible  notes  payable  to  the  Advent
Partnerships. 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
$76,566 and cash  of $5,133  at December 31,  1994. Subsequent  to December  31,
1995,  the Company raised  $2.3 million in  cash (net of  expenses) in a private
equity placement with  Ameritech, $4.9 million  in cash (net  of expenses) in  a
private  placement  of notes  and  warrants and  $2.2  million in  cash  (net of
expenses) in the Equipment 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. Property and  equipment, net of  accumulated
depreciation,  comprised $3.6 million of total  assets at December 31, 1995. FCC
licenses and the  investment in  the ART West  Joint Venture  increased to  $4.5
million at December 31, 1995, as compared to $0 at December 31, 1994.
 
    Capital  expenditures, including deposits  on equipment for  fiscal 1994 and
1995,  were  $5,175  and  $3.9  million,  respectively.  The  Company  currently
purchases  the majority  of its  wireless transmission  equipment from  a single
vendor 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. Any reduction or interruption  in supply from this vendor could
have a material adverse effect on  the Company until alternative supply  sources
are  established. The Company  has entered into a  preliminary agreement with an
entity in which an  executive of the  Company is a  director and shareholder  to
fund  from $700,000 to $1.0 million of research and development costs related to
wireless transmission  equipment. The  Company  will receive  a first  right  of
refusal  on production capacity and  a license fee in  exchange for its funding.
See "Certain Transactions." However, the Company does not currently 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
the  Company's requirements, there can be no assurance that such equipment would
be available to the Company on comparable terms or on terms more favorable  than
those  included in its current arrangements. 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 currently expects that in
fiscal 1996 and fiscal 1997, its capital expenditures (including the acquisition
of   certain  spectrum  rights)  will  be   $33.0  million  and  $57.0  million,
respectively.
 
    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 negative operating cash flow will
increase as the  Company executes  the initial  phases of  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.
 
    The Company  has recently  entered  into a  preliminary agreement  with  DCT
Communications,  Inc.  ("DCT")  to  acquire DCT's  interest  in  certain  38 GHz
licenses in  exchange  for  $3.6  million in  cash.  The  preliminary  agreement
contemplates  the  execution  of  a  definitive  purchase  agreement,  which  is
contingent upon the execution of a mutually agreeable services agreement between
the Company and DCT for the operation  of those licenses through the closing  of
the agreement. The closing of the transaction is subject to FCC approval.
 
    Management anticipates that, based on current plans of development, assuming
that no material acquisitions are consummated, the net proceeds of the Offerings
and,   together  with  existing  financial  resources  and  after  repayment  of
approximately $5.0 million of existing indebtedness, will be sufficient to  fund
the  operations  of the  Company for  at  least the  next two  years. Management
believes that the
 
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<PAGE>
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 or  (iii) the  Company completes any
material acquisitions, 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 1995 Stock Option 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.
 
                                       29
<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.
 
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) 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 end users. 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. Connecticut Research Inc. ("CRI") estimates that in 1994,
CAPs captured approximately $1.3 billion, or 1.3%, of $97.1 billion in  revenues
generated  by the local exchange market. CRI  also projects that, as a result of
increased competition and the growth  of enhanced services, 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
 
                                       30
<PAGE>
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 thirty 100 MHz channels between 37.0 GHz and 40.0  GHz
for  wireless broadband  transmissions (collectively  referred to  as "38 GHz"),
which enable the licensee to provide point-to-point services within a  specified
geographic footprint 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  facilities ART
purchased in  November  1995) was  the  first company  to  undertake  commercial
exploitation of 38 GHz services.
 
    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 channel 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). The  broadband capacity of  38
      GHz   transmission  provides  improved  speed,   clarity  and  quality  in
      transmissions, as compared to legacy copper wire networks. In addition  to
      accommodating   standard  voice  and  data   requirements,  45  Mbps  data
      transmission rates allow end  users to receive full  motion video and  3-D
      graphics   at  their  workstations  and   to  utilize  highly  interactive
      applications on the Internet and other networks.
 
    - EFFICIENT CHANNEL REUSE.   Because 38  GHz radio emissions  have a  narrow
      beam  width, a relatively short range  and can in many instances 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, each
      100 MHz channel in  a given service area  can accommodate at least  10,000
      DS-3 links, each of which can carry 672 voice circuits.
 
    - RAPID  DEPLOYMENT.   38 GHz technology  can be  deployed considerably more
      rapidly than wireline and other wireless technologies. 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
 
                                       31
<PAGE>
      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.  The
      time  required to  install a  38 GHz link  within a  licensed footprint is
      typically less than 72 hours after obtaining access to customer  premises,
      versus  an estimated  three to  five months  in other  microwave frequency
      bands due to regulatory delay.
 
    - 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.
 
    - EFFICIENT NETWORK DESIGN.  The exclusive right to use a particular channel
      or channels within a broad geographic area gives the licensee much greater
      control over its network design. A 38 GHz licensee can save costs,  ensure
      interference-free  operations  and  increase  quality  and  reliability by
      designing efficient 38 GHz networks in advance of their deployment.
 
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 99.995% availability, with  better than a 10-13 bit error
rate. This level of  performance significantly exceeds  that provided by  copper
based  networks and is  a viable alternative  to fiber optic  based networks. In
addition, the  Company believes  that  ART's last  mile  solution is  more  cost
effective than 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:
 
    - The characteristics  of 38  GHz technology  -- high  data transfer  rates,
      efficient  channel  reuse,  rapid  deployment,  ease  of  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.
 
    - 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.
 
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<PAGE>
    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  commercial end-user  customers. 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 last  quarter
of  1995 and has generated only nominal revenues from such services to date. The
Company is seeking to  capitalize on the  broad geographic scope  of its 38  GHz
authorizations to become the premier provider of wireless broadband solutions to
a diverse group of traditional and emerging telecommunications service providers
and   end  users.  The  Company  plans  to  implement  the  following  strategic
initiatives to achieve this objective:
 
    - EXPLOIT SPECTRUM  POSITION IN KEY  MARKETS TO REALIZE  VALUE. The  Company
     currently  owns or manages  108 authorizations to  construct and operate 38
     GHz wireless broadband facilities in 91  market areas, including 74 of  the
     top  100 U.S. markets.  These spectrum assets provide  the Company with the
     foundation on which  to create a  large scale commercial  system of 38  GHz
     wireless  broadband  operations.  The  Company  is  now  operating wireless
     broadband links in nine  cities (Chicago; Boston; Philadelphia;  Baltimore;
     Pittsburgh;    Portland,   Oregon;   Seattle;    Albany;   and   Bethlehem,
     Pennsylvania).  The   Company  plans   to  continue   to  build   out   its
     infrastructure  and to intensify its marketing  effort in its market areas,
     thereby realizing the value inherent in its spectrum assets.
 
    - MARKET  TO TELECOMMUNICATIONS  SERVICE  PROVIDERS. 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 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 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, or  anticipates
     providing,  services  to  Ameritech,  Bell  Atlantic  NYNEX  Mobile, UUNet,
     American Personal  Communications,  Electric Lightwave,  NEXTLINK,  Western
     Wireless,   Chadwick  Telephone  Co.  and  CGX  Telcom,  among  others.  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
 
                                       33
<PAGE>
     38 GHz DS-3 channel 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  working on 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.
 
    - 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 market penetration  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  believes that  it  will
     achieve  a competitive advantage through  proprietary methods that increase
     the capacity and quality of its networks.
 
    - ESTABLISH AND  EXPAND KEY STRATEGIC  ALLIANCES. The Company  has and  will
     continue to establish key strategic alliances with major service providers,
     equipment   manufacturers,   systems  integrators   and   enhanced  service
     providers. Ameritech Development Corp. recently acquired a 5.4%  beneficial
     equity  interest in the Company  as of April 30,  1996 and recently entered
     into the Ameritech Strategic Distribution  Agreement. The Company also  has
     agreements  with  GTE for  field servicing  and  network monitoring  and is
     developing relationships with a number of equipment manufacturers  focusing
     on  38 GHz technology  development, wireless broadband  standards and joint
     sales efforts. The Company will utilize these strategic alliances to bundle
     its services with  those of its  partners, which the  Company expects  will
     help it to achieve a lower cost of sales and increased market penetration.
 
WIRELESS BROADBAND SERVICES
 
    The  Company's wireless broadband links deliver  high quality voice and data
transmissions at  a  level  of  performance  which  significantly  exceeds  that
provided  by copper based  networks and is  a viable alternative  to fiber optic
facilities.  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  its wireless  broadband
capacity  meets or exceeds the anticipated service requirements of the Company's
target customers in its existing 91 market areas.
 
    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 99.995% availability, (v) transmission accuracy engineered
to provide bit  error rates of  better than 10-13,  (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 centers,  (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
 
                                       34
<PAGE>
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  is in  the
process  of  becoming a  qualified vendor  to  all the  major IXCs.  The Company
currently provides,  or  anticipates  providing,  services  to  Ameritech,  Bell
Atlantic  NYNEX  Mobile  Systems,  American  Personal  Communications,  Electric
Lightwave, NEXTLINK, UUNet,  Western Wireless,  Chadwick Telephone  Co. and  CGX
Telcom,  among others. The Company is  now operating wireless broadband links in
nine cities  (Chicago; Boston;  Philadelphia; Baltimore;  Pittsburgh;  Portland,
Oregon; Seattle; Albany; and Bethlehem, Pennsylvania).
 
    The Company currently provides, or anticipates providing, wireless broadband
services to the following types of customers, among others:
 
                                       35
<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
transmission. 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  would 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 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 DISPLAYING 38 GHz LINK BETWEEN AN
              OFF-FIBER NET BUILDING AND AN ON-FIBER NET BUILDING]
 
                                       36
<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 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 and over 350
times the rate of the fastest ISDN lines currently in use.
 
                        [GRAPHIC DISPLAYING 38 GHz LINKS
                  BETWEEN ISP POPS, REMOTE SERVER AND PC LAN]
 
                                       37
<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 DISPLAYING 38 GHz LINKS BETWEEN
                     MOBILE SWITCHING CENTER, BASE STATION
                   CONTROLLERS AND BASE STATION/CELL SITES.]
 
                                       38
<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 DISPLAYING 38 GHz LINKS BETWEEN
                     AN IXC POP, AN OFF-FIBER NET BUILDING,
            AN ON-FIBER NET BUILDING AND A METROPOLITAN FIBER RING.]
 
                                       39
<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 DISPLAYING 38 GHz LINKS BETWEEN
              AN ON-FIBER NET BUILDING, AN OFF-FIBER NET BUILDING,
     PC LAN, METROPOLITAN FIBER RING AND GEOGRAPHICALLY DISTANT NETWORKS.]
 
                                       40
<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 DISPLAYING 38 GHz LINKS BETWEEN
              WIDE AREA NETWORK VIDEO SERVER, DIGITAL VIDEO HUBS,
              DIGITAL EDITING PC LANs AND LIVE ANALOG BROADCASTS.]
 
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  also  markets  its  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 sale force with major telecommunications service providers and end users.
 
    The Company currently prices its services on a monthly flat-rate basis. As a
non-dominant carrier, ART does not have to cost-justify its rates to  regulatory
bodies  and 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  priced at a
modest discount to the prices 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.
 
                                       41
<PAGE>
38 GHZ WIRELESS BROADBAND LICENSES AND AUTHORIZATIONS
 
    The Company believes that it derives significant competitive advantages from
the widespread  geographic  coverage  and broadband  capacity  provided  by  108
authorizations  granted by the  FCC. An authorization  is initially considered a
construction permit; once installation requirements have been met, however,  the
authorization  develops into a license. The Company was granted the first of its
authorizations to construct and operate 38 GHz wireless broadband facilities  in
February  1995.  The  Company  currently  owns or  manages  35  licenses  and an
additional 73 authorizations  in 91 market  areas. The Company  owns or  manages
authorizations  in 41 of the top 45 markets and 74 of the top 100 markets. These
authorizations currently  cover  an  aggregate population  of  approximately  94
million people.
 
    The Company has authorizations (including licenses and construction permits)
in  the 91 market areas listed below. Such market areas are listed in descending
order of  size  based on  the  estimated  population covered  by  the  Company's
authorization(s)  in  such area  within each  such  area, and  represent channel
capacity of 100 MHz each, unless otherwise indicated:
 
<TABLE>
<S>          <C>  
New York, NY (1)(7)
Chicago, IL
Washington, DC (1)/
 Baltimore, MD (4)(7)
Miami, FL
Boston, MA (1)(6)
Philadelphia, PA (1)(6)
Atlanta, GA
St. Louis, MO
Minneapolis, MN
San Jose, CA (3)(4)
Norfolk, VA (4)
Portland, OR (1)(3)(4)(6)
Sacramento, CA (4)
Dallas, TX (3)
NY-Long Island, NY (1)(6)
Pittsburgh, PA (1)(6)
Seattle, WA (1)(2)(6)
Houston, TX
Hartford, CT (1)(4)(7)
Columbus, OH (4)
Wilmington, DE (1)(4)(7)
San Diego, CA (2)
Trenton, NJ (1)(6)
Oklahoma City, OK (4)
Grand Rapids, MI (5)
Cleveland, OH
Las Vegas, NV (2)
Dayton, OH (4)
Buffalo, NY (1)(6)
San Antonio, TX
Greensboro, NC (4)
Denver, CO (2)
New Orleans, LA
Honolulu, HI (2)
Providence, RI (1)(6)
Tacoma, WA (3)(4)
Birmingham, AL
Indianapolis, IN
Bridgeport, NH (1)(6)
Salt Lake City, UT (2)
Cincinnati, OH
Albany, NY (1)(7)
Rochester, NY (1)(7)
Knoxville, TN
Phoenix, AZ (2)
Baton Rouge, LA
Albuquerque, NM (2)
Tucson, AZ (3)(4)
Wichita, KS
Austin, TX (4)
Canton, OH
Kansas City, MO
Charleston, SC (4)(6)
Mobile, AL (4)(6)
Des Moines, IA
White Plains, NY (1)(6)
Scranton, PA (1)(7)
Allentown, PA (1)(6)
Louisville, KY
Spokane, WA (2)
Shreveport, LA
Memphis, TN
Springfield, MA (1)(6)
York, PA
Richmond, VA
Syracuse, NY (1)(7)
Madison, WI
Stamford, CT (1)(6)
Pensacola, FL
Ogden, UT
Huntington, WV
Worcester, MA (6)
Harrisburg, PA (6)
Nashville, TN
Jackson, MS
Reno, NV (2)
Eugene, OR (2)
Lorain, OH
Kingston, NY (6)
Charleston, WV
Jackson, MS (5)
Anchorage, AK (2)
Binghamton, NY (6)
Utica-Rome, NY (6)
Billings, MT (2)
Corning, NY (6)
Eureka, CA (2)
Altoona, PA (6)
Fairbanks, AK (2)
Lincoln, NE
Juneau, AK (2)
</TABLE>
 
- ------------------------------
 
(1) Indicates two or more authorizations.
 
(2) Interests in these markets  held by ART West, a  joint venture in which  the
    Company  has a  50% interest.  See "--  Agreements Relating  to Licenses and
    Authorizations -- ART West Joint Venture" and "Certain Transactions."
 
                                       42
<PAGE>
(3) DCT owns these authorizations subject to the Put/Call Agreement and  Service
    Agreement  with ART  Corp. Interests  in these markets  held by  ART West, a
    joint venture in which  the Company has a  50% interest. See "--  Agreements
    Relating to Licenses and Authorizations -- ART West Joint Venture."
 
(4)  DCT owns these authorizations subject to the Put/Call Agreement and Service
    Agreement with  ART  Corp.  See  "-- Agreements  Relating  to  Licenses  and
    Authorizations -- DCT System Purchase Agreements."
 
(5)  ART Corp. has  the right to acquire  49% of these  markets and manage them,
    sharing revenue with Telecom  One. See "--  Agreements Relating to  Licenses
    and Authorizations -- Telecom One Services Agreement."
 
(6) 200 MHz.
 
(7) 300 MHz.
 
    In  addition to  the above authorizations,  the Company  has 75 applications
pending with the FCC for additional authorizations. However, due to the "freeze"
imposed by the NPRM, the  Company does not expect that  it or any other  company
will  receive additional authorizations with respect to any pending applications
in the  near  future.  See  "Risk Factors  --  Government  Regulation"  and  "--
Government Regulation."
 
    The Company has between 100 and 300 MHz of transmission capacity within each
of  its market areas. Because 38 GHz paths are very narrow and because 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 the Company's existing 91 market areas.
Consistent with the Company's  growth strategy, the Company  may seek to  obtain
additional  capacity by either  leasing channels on a  common carrier basis from
other 38 GHz licensees, entering into services agreements or acquiring interests
in other 38 GHz licenses. To the  extent certain 38 GHz licensees are unable  to
satisfy  the FCC construction requirements,  the Company believes these licenses
will be available for purchase in the secondary market, subject to FCC approval.
 
    Under  the  terms   of  its  authorizations,   the  Company  must   complete
construction   of  facilities   for  approximately   50  authorizations  between
mid-August and mid-September 1996. The Company has begun installing the  minimum
number  of links required, and currently expects  it will meet the FCC deadline.
However, the FCC may impose  more stringent construction requirements which  may
jeopardize  the status of  the Company's authorizations.  The Company's licenses
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.
 
AGREEMENTS RELATING TO LICENSES AND AUTHORIZATIONS
 
    ART CORP. SERVICES  AGREEMENT.   Under a  services agreement,  dated May  8,
1995,  between  ART and  ART  Corp. (the  "ART  Corp. Services  Agreement"), the
Company agreed to  construct, operate and  manage all FCC  licenses and  related
telecommunications  systems owned  or managed by  ART Corp. Under  the ART Corp.
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 75%  of the  net revenues  generated by  the
systems  and  ART  Corp. receives  the  remaining  25%. The  ART  Corp. Services
Agreement expires  on  the  earlier  to  occur  of  (i)  May  8,  2015  or  (ii)
consummation of the Merger. See "-- Proposed Merger."
 
    EMI ACQUISITION.  On April 4, 1995, ART Corp. 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 Corp. assigned all of its rights and obligations under the
purchase agreement to ART. The FCC subsequently approved the transfer of the EMI
Assets to ART. ART Corp. has also guaranteed the obligations of ART to EMI under
the  EMI Note and has agreed to provide wireless broadband services on behalf of
EMI for a period of one year from the date of the agreement to certain of  EMI's
customers. See "Description of Certain Indebtedness -- EMI Note."
 
                                       43
<PAGE>
    ART  WEST  JOINT  VENTURE.    On  April  4,  1995,  ART  Corp.  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 Corp. and Extended. In
accordance with the  terms of  the ART West  Agreement, ART  Corp. and  Extended
agreed to transfer to ART West all of their respective interests in all of their
38  GHz  authorizations  (currently,  22  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. Each
of Extended and ART Corp. owns 50% of  ART West. ART Corp. is obligated to  bear
all costs and expenses relating to construction, operation and management of the
ART  West Markets. As compensation, ART Corp. receives 77.5% of the net revenues
of ART West, with Extended receiving the remaining 22.5%. Pursuant to the  terms
of  the  ART  West  Agreement,  each joint  venture  partner  has  the  right to
participate in the acquisition by the other partner or any of its affiliates  of
5%  or greater interest in any 38 GHz authorization or license in any additional
ART  West  Market.  In  such  case,  such  authorization  or  license  would  be
contributed  to ART West. In  the event any joint  venture partner elects not to
participate in any such acquisition, the other partner has the right to purchase
such authorization or  license directly. On  October 1, 1994,  the Company,  ART
Corp.  and  Extended  entered  into  an  agreement  (the  "ART  West  Management
Agreement"), pursuant to which the Company agreed to manage the business of  ART
West and operate its assets as part of the Company's nationwide system of 38 GHz
assets.  Pursuant to  the ART  West Management  Agreement, the  Company owns all
equipment, provides  all services  and is  entitled to  market and  operate  the
Company's  wireless broadband  services in  the ART  West Markets.  See "Certain
Transactions -- ART West Joint Venture."
 
    DCT SYSTEM PURCHASE  AGREEMENTS.  On  September 1, 1994,  ART Corp.  entered
into  an agreement with DCT Communications,  Inc. ("DCT"), pursuant to which ART
Corp. obtained an option  to purchase certain FCC  licenses (the "DCT  Systems")
from DCT for $500,000 and shares representing 5% of ART Corp's common stock on a
fully  diluted basis as of the date of  transfer. The option may be exercised at
any time after December 31, 1995 and expires three years after the date on which
the FCC issues DCT's  first license. DCT  may at any time  require ART Corp.  to
purchase  the DCT Systems for $50,000  and the reimbursement of certain expenses
related to the acquisition thereof. On September 1, 1994, ART Corp. entered into
an exclusive services agreement with DCT  pursuant to which ART Corp. bears  the
responsibility  for  the  construction,  operation  and  management  of  the DCT
Systems. The agreement  expires on  September 1, 1999.  Under the  terms of  the
services  agreement,  ART Corp.  is  obligated to  bear  all costs  and expenses
relating to  construction,  operation and  management  of the  DCT  Systems.  As
compensation, ART Corp. is entitled to receive 55% of the net revenues generated
by the DCT Systems, with DCT receiving the remaining 45%.
 
    On April 25, 1996, the Company entered into a preliminary agreement with DCT
pursuant  to which the Company agreed to purchase from DCT the 13 authorizations
subject to existing  agreements and 3  additional licenses for  $3.6 million  in
cash,  subject to  completion of a  definitive purchase agreement  and a revised
services agreement  under which  the Company  will have  responsibility for  the
construction,  operation and  management of  the DCT  Systems as  well as  the 3
additional systems. The Company  will also have  a right of  first offer on  all
future  FCC license grants to DCT. A definitive agreement must be signed by June
28, 1996 and the closing of the transactions is subject to FCC approval. In  the
event  that the closing takes place more  than six months after the execution of
the agreement,  DCT  will be  entitled  to receive  15%  of the  gross  revenues
generated  by  links deployed  in  the DCT  channels  until the  closing  of the
transfer of the FCC licenses.
 
    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 two 38 GHz wireless broadband licenses and
 
                                       44
<PAGE>
related  telecommunications systems owned by Telecom  One. 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 gross  revenues generated by  the
systems and Telecom One receives the remaining 10%.
 
    TELECOM  ONE OPTION   On May 25,  1995, the Company  and Telecom One entered
into an agreement  pursuant to which  the Company acquired  from Telecom One  an
option  to acquire a 49%  interest in two authorizations.  The option expires on
May 25, 2000 and  the Company has  not decided whether or  not to exercise  this
option.
 
                                     [LOGO]
 
STRATEGIC ALLIANCES
 
    AMERITECH  STRATEGIC DISTRIBUTION AGREEMENT.  On April 29, 1996, the Company
and  Ameritech  Corp.   ("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 will  be
the  primary provider  of the  Company's services  in the  midwest. Ameritech is
targeting certain  sales  objectives and  proposes  to commit  $7.0  million  to
support  the 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."
 
    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, GTE  will provide 75% of the Company's
 
                                       45
<PAGE>
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 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  $2.0  million   and  an   annual  maintenance   support  fee   of
approximately  $300,000. In  addition, the  Company made  an initial  payment of
$250,000 upon  execution  of the  agreement  and  is obligated  to  pay  monthly
installments  commencing January  1, 1997.  After the  first year,  all fees are
subject to  change.  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  a
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 entered into preliminary
understandings   with  three  microwave   equipment  or  technology  development
companies for development of  advanced 38 GHz  radios, highspeed converters  and
innovative  telecommunications platforms. The Company expects to be able to fund
development of this  technology in stages  and to obtain  rights to license  the
specific  technology.  In addition,  the Company  has entered  into a  letter of
intent with American Wireless Corporation ("American Wireless") providing for an
investment by  the  Company  of  $700,000  to  $1.0  million  for  research  and
development.  In consideration of its investment,  the Company will have a right
of first refusal on  production capacity of  the new radios  and will receive  a
per-unit license fee. See "Certain Transactions -- American Wireless Development
Agreement." Each of these agreements is subject to definitive documentation.
 
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. There  can be  no assurance  that the  Company will  be able to
compete effectively in any  of its market areas.  The Company faces  significant
 
                                       46
<PAGE>
competition  from other 38 GHz providers and  incumbent LECs, such as the RBOCs.
To a  lesser  extent,  the  Company may  compete  with  CAPs,  cable  television
operators,  electric  utilities,  LECs  operating  outside  their  current local
service areas and IXCs.
 
    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 certain cases, these service providers hold licenses to operate
on other portions  of the 38  GHz band  in geographic areas  which encompass  or
overlap  the Company's market areas. In a  number of the Company's market areas,
at least one other 38 GHz service provider has 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  five other  entities  have been  granted  38 GHz
authorizations in geographic regions in which the Company plans to operate.  Due
to  the relative ease and speed of  deployment of 38 GHz technology, the Company
could face  intense  price competition  from  other 38  GHz  service  providers.
Accordingly,  there can be no assurance that the Company will be able to sustain
a profitable business in the face of prolonged price competition.
 
    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 the  lower 16 channels in  the 38 GHz spectrum band,
which have  not been  previously  available for  commercial  use. The  grant  of
additional  licenses 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  the adoption  of  the NPRM  as currently
proposed, additional entities  having greater resources  than the Company  could
acquire licenses to provide 38 GHz services.
 
    COMPETITION  FROM  INCUMBENT  LECS.    The  Company  also  faces significant
competition from incumbent LECs, irrespective  of whether they provide  service.
Incumbent  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   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) establishes
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 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.  To  a lesser degree, 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.
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.
 
                                       47
<PAGE>
    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 and  IXCs. 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.
 
    A number 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 originate  in
one  state and terminate  in another state or  foreign country. 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 issuing 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  competition.  Under  current  FCC  rules,  the  recipient  of  a
construction permit (or authorization) for  microwave facilities is required  to
complete  construction of such facilities within 18  months of the date of grant
of the  permit. To  satisfy  the FCC's  current construction  requirements,  the
permit   holder  is  required  to  establish  at  least  one  link  between  two
transceivers in each market area for which it holds a construction permit.  Upon
completion of construction and filing of certification thereof with the FCC, the
permit develops into a
 
                                       48
<PAGE>
license  to provide microwave services. In the event that the recipient fails to
comply with  the construction  deadline, the  permit is  subject to  forfeiture,
absent  an extension  of the deadline.  Of the Company's  108 authorizations, 35
have developed into licenses. Under the  terms of its remaining 73  construction
permits,  the Company must complete construction of facilities for approximately
50 construction permits between mid-August  and mid-September 1996. 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
authorization.
 
    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.
 
    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.
 
    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
prohibiting  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
 
                                       49
<PAGE>
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.
 
    The Company believes that the Telecommunications Act substantially  benefits
its  business plans by allowing  the Company to provide  a much broader array of
services, including switched services and services interconnected to the  Public
Switched  Telecommunications Network  ("PSTN"), in many  more states,  at a much
earlier time  and at  a  substantially lower  cost. The  Telecommunications  Act
should  be  of equal,  if  not greater,  benefit to  one  of the  Company's most
important initial customer groups, CAPs. CAPs are promised substantial  benefits
under  the  Telecommunications  Act  which  should  significantly  improve their
revenues and profits, attracting  more CAPs into business  and enabling them  to
fund  expansion.  These developments  should lead  to  increased demand  for the
Company's services. 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 licenses.  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 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.  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 may then be dismissed. Final  rules issued in connection with the  NPRM
may require that 38 GHz service providers share other unlicensed 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. 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 proposes to substantially  strengthen the current rules concerning
the steps that a grantee of a 38 GHz authorization, which is in the nature of  a
construction  permit, must take in  order to receive a  license. At present, the
holder of  a  construction  permit  is  only required  to  certify  that  it  is
operational.  Although  the  FCC has  not  defined the  term  "operational," 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.
The Company has supported the  concept of stiffer construction requirements  and
has  proposed a set of construction requirements that would require construction
of long-term revenue-producing  links throughout the  authorized area, with  the
requirements being applicable to each channel and increasing over the first five
years  of the  license term.  None of  the other  38 GHz  licensees and grantees
supported such strong  construction requirements. The  Company believes that  it
can meet the construction requirements that it has proposed and that it would be
comparatively harder for the other 38 GHz licensees and grantees to satisfy such
requirements.  However,  there  is no  assurance  that  the FCC  will  adopt the
Company's proposal or that the Company will be able to satisfy whatever proposal
is adopted.
 
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<PAGE>
    The NPRM proposes to auction any pending and future 38 GHz applications that
are mutually exclusive. The NPRM would  specify the geographic areas that  could
be  licensed  instead  of  continuing  to allow  the  applicants  to  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 auction pending and future mutually exclusive
38 GHz licenses, 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 required
for  calls originating and terminating within  a single LATA and intrastate long
distance services, 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.
 
PROPOSED MERGER
 
    ART and ART Corp. plan to merge, subject only to FCC approval of the Merger.
In the Merger, ART Corp. will merge with and into ART, stockholders of ART Corp.
will  receive  an  aggregate  of  10,013,055  shares  of  Common  Stock  and the
10,013,055  shares  of  Common  Stock  currently  held  by  ART  Corp.  will  be
surrendered  to ART. Completion of the Merger  is a condition to consummation of
the Offerings.
 
INTELLECTUAL PROPERTY RIGHTS
 
    The Company has filed for protection for three service marks: DigiWave  (the
Company's  wireless broadband trademark), 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 May 1, 1996, the Company had a total of 36 employees, including  seven
in   engineering  and  field  services,  11  in  sales  and  marketing,  six  in
administration  and  finance,  five  in   operations  and  seven  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.
 
                                       51
<PAGE>
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 & Hanley. See  "Certain
Transactions -- Pierson, Burnett & Hanley Transactions."
 
LITIGATION
 
    The Company is not a party to any litigation.
 
                                       52
<PAGE>
                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    The  current executive officers and directors of the Company, their ages and
their positions are as follows:
 
<TABLE>
<CAPTION>
NAME                                         AGE      POSITION
- ---------------------------------------      ---      -------------------------------------------------------
<S>                                      <C>          <C>
Vernon L. Fotheringham (1)(2)(3).......          47   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................          58   Executive Vice President, Secretary and General Counsel
James D. Miller........................          53   Senior Vice President, Sales and Marketing
Thomas C. Bennett......................          48   Vice President and General Manager, Northeast Region
Paul Brandenburg.......................          48   Vice President, Engineering and Field Services
I. Don Brown...........................          39   Vice President, Internet Services
Sheila Darling.........................          50   Vice President, Network Operations
Mark T. Marinkovich....................          31   Vice President and General Manager, Western Region
Charles D. Menatti.....................          42   Vice President, Corporate Development
Richard A. Shields, Jr.................          39   Vice President, Technology
William J. Smilie......................          52   Vice President and General Manager, Midwest Region
J.C. Demetree, Jr. (3)(4)(5)...........          37   Director
Mark C. Demetree (1)(2)................          39   Director
Andrew I. Fillat (2)(3)(4).............          47   Director
Matthew C. Gove (2)(4)(5)..............          31   Director
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
     two  directors, unaffiliated with the Company's present management, will be
     elected to the Board of Directors. See " -- Board Composition."
 
    VERNON L. FOTHERINGHAM  has served as  Chairman of the  Board of  Directors,
Chief  Executive Officer of the Company and ART Corp. 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  1992, 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.
Over the last ten years, Mr. Fotheringham has advised several businesses in  the
telecommunications  industry, including  American Mobile  Satellite Corporation,
ClairCom Communications  ("ClairCom"),  several international  cellular  systems
developed  by  McCaw Cellular  Communications, Inc.  and the  Qualcomm OmniTRACS
network.
 
                                       53
<PAGE>
    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   Cypress  Broadcasting   Inc.,  a
California-based  television  subsidiary  of  Ackerley  Communications  Inc.,  a
diversified  media company based in Seattle,  Washington. From 1987 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,
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 ART Corp.  since inception. Mr. Pierson is a  partner
of  the firm of Pierson, Burnett & Hanley 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.
 
    THOMAS  C.  BENNETT  has  served  as  Vice  President  and  General Manager,
Northeast Region of the Company since  February 1996. From July 1994 to  January
1996,  Mr. Bennett served as  the director of PCS  development for GTE Worldwide
Telecommunications Services  ("GTEW").  Prior to  1994,  Mr. Bennett  served  in
various positions with GTEW.
 
    PAUL  BRANDENBURG  has  served  as  Vice  President,  Engineering  and Field
Services of the Company since December 1995. From January 1995 to January  1996,
he  was an independent consultant in telecommunications technology. From October
1992 to  January 1995,  Mr. Brandenburg  served as  vice president  and  general
manager  of ICG Wireless Services, Inc. Prior  to October 1992, he served as the
director of business development of TCI.
 
    I. DON BROWN has served as Vice President, Internet Services of the  Company
since  February 1996. From 1995 to 1996, Mr.  Brown acted as a consultant to the
Company and other telecommunications companies. From 1991 to 1995, he served  as
executive vice president of USA TODAY Sky Radio.
 
    SHEILA  DARLING has been  Vice President, Network  Operations of the Company
since December 1995. From July 1992 to May 1995, Ms. Darling was associated with
Western Wireless  Corporation, where  she was  responsible for  network  design,
engineering  and interconnect facilities for 20  switches. From December 1992 to
May 1993, Ms.  Darling was the  senior technical consultant  at Digital  Systems
International, Inc.
 
    MARK  T.  MARINKOVICH  has served  as  Vice President  and  General Manager,
Western Region of the Company since July 1995. Since April 1994, Mr. Marinkovich
has served as president of Extended, the Company's partner in the ART West Joint
Venture. From  June  1992 to  1995,  Mr. Marinkovich  was  a  telecommunications
consultant with TWG. Prior to 1992, Mr. Marinkovich worked as a certified public
accountant with KPMG Peat Marwick LLP.
 
    CHARLES  D. MENATTI has  served as Vice  President, Corporate Development of
the Company  since  November 1995.  From  1994 to  1995,  Mr. Menatti  was  vice
president for worldwide sales for AccessLine
 
                                       54
<PAGE>
Technologies,  Inc. From 1993 to  1994, Mr. Menatti was  general manager of U.S.
Intelco Networks,  Inc. From  1992 to  1993,  he served  as vice  president  and
managing  director  of Atlas  Telecom.  From 1991  to  1992, he  served  as vice
president of BellSouth Europe in Brussels, Belgium.
 
    RICHARD A. SHIELDS,  JR. has  served as  Vice President,  Technology of  the
Company  since February  1996. From  1992 to  1996, Mr.  Shields served  as vice
president for engineering and design for ClairCom. From 1991 to 1992, he was the
director of product development at TWG.
 
    WILLIAM J. SMILIE has served as Vice President and General Manager,  Midwest
Region  of the Company since April 1996. From 1993 to 1996, Mr. Smilie served as
deputy managing director of NetCom/ Ameritech in Oslo, Norway. Mr. Smilie served
as the  director of  international  wireless for  Ameritech  from June  1992  to
January  1996,  the  director  of  business  development  for  Ameritech  Mobile
Communications, Inc. ("AMC")  from June  1991 to May  1992 and  the director  of
marketing for AMC from January 1982 to June 1991.
 
    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 1981 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 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  has also been a  director of Safety 1st,  Inc.
since  1994 and currently serves  as a director of  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.
 
    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.  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."
 
                                       55
<PAGE>
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  the
Company'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.
 
    All directors  hold office  until  their successors  have been  elected  and
qualified.  Upon consummation of the Offerings, Messrs. J.C. Demetree, Jr., Gove
and Zimmerman will resign as directors and two directors, unaffiliated with  the
Company's  present management  or stockholders,  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). Mr. Comrie and one
of the newly elected independent directors will be elected as Class I  directors
for  an initial one-year term expiring in  1997. Mr. Fotheringham and one of the
newly elected independent directors 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 1999.
 
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  1995 Stock
Option 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.
 
    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
 
                                       56
<PAGE>
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.
 
    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.
 
    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.
 
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         30,000(3)
W. Theodore Pierson, Jr., Executive Vice President        80,000             --              --        218,600(1)(4)
James D. Miller, Senior Vice President, Sales and
 Marketing (2)                                                --             --          50,000             --
Charles D. Menatti, Vice President, Corporate
 Development (2)                                          13,381             --          35,000            800(1)
</TABLE>
 
- ------------------------------
(1)  Automobile reimbursement benefits equal  to $9,600 in  the case of  Messrs.
     Fotheringham and Pierson and $800 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  & Hanley,  of which  Mr. Pierson  is a
     partner, $209,000 for services rendered to the Company through December 31,
     1995.
 
                                       57
<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
                               ----------------------------------------------------  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 (2)               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
Charles D. Menatti                  35,000           3.3%         1.652   12/29/00            --         9,821
</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.
 
(2)  Mr.  Comrie  has  been granted  (i)  incentive stock  options  (the "ISOs")
     expiring June 17,  2002 to  purchase 151,338 shares  of Common  Stock at  a
     price  of  $0.5907  per share  and  (ii) non-qualified  stock  options (the
     "NQSOs") expiring  on  various dates  through  June 17,  2005  to  purchase
     605,353  shares of Common Stock  at a price of  $0.5907 per share. The ISOs
     will be fully vested on  July 17, 1997. Of  the ISOs 115,017 are  currently
     exercisable, and 36,321 will become exercisable on July 17, 1997. The NQSOs
     are  subject to vesting over a five-year  period. Of the NQSOs, 302,676 are
     currently exercisable, and 75,669 will become exercisable on July 17,  1997
     and  up  to an  additional 227,007  shares  (the "Additional  Shares") will
     become exercisable on June 17, 2000. The vesting of NQSOs to purchase up to
     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.
 
     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                                            302,676        454,015     $ 184,420    $    276,631
James D. Miller                                              10,000         40,000            --              --
Charles D. Menatti                                            7,000         28,000            --              --
</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
 
    1995 STOCK OPTION PLAN.  On July 22, 1995, the Company adopted the Company's
1995  Stock Option Plan  (as amended, the  "1995 Stock Option  Plan"). Under the
1995 Stock Option Plan, options to purchase an aggregate of 2,500,000 shares  of
Common  Stock  may be  granted from  time  to time  to key  employees, officers,
directors, advisors and independent consultants to the Company or to any of  its
subsidiaries.  Options granted to employees may be designated as incentive stock
options ("ISOs") or  non-qualified stock options  ("NQSOs"). Options granted  to
directors, independent consultants and
 
                                       58
<PAGE>
other  non-employees  may only  be  designated NQSOs.  As  of the  date  of this
Prospectus, options  to purchase  an  aggregate of  1,537,232 shares  have  been
granted to employees of the Company under the 1995 Stock Option Plan.
 
    The  1995 Stock Option Plan  is administered by the  Option Committee of the
Board of Directors. The Option Committee is generally empowered to interpret the
1995 Stock Option Plan, to prescribe rules and regulations relating thereto,  to
determine  the terms of the option agreements, to amend them with the consent of
the optionee, to determine the employees to whom options are to be granted,  and
to  determine the number of shares subject to each option and the exercise price
thereof. The per share  exercise price of options  granted under the 1995  Stock
Option  Plan may not be less  than 100.0% of the fair  market value per share of
Common Stock on the  date the options  are granted (110.0%  of such fair  market
value  if the grantee owns  more than 10.0% of the  combined voting power of all
classes of the  Company's stock), provided  that for the  two years  immediately
following  the consummation of the  Offerings, the option price  may not be less
than the greater of the fair market value of the Common Stock on the grant  date
or the initial public offering price established by the Common Stock Offering.
 
    Options  are exercisable for a term not greater than ten years from the date
of grant (five years from the date of grant of an ISO if the optionee owns  more
than  10.0% of  the Common  Stock of the  Company). Options  (other than certain
NQSOs designated by the  Option Committee or the  Board of Directors,  including
NQSOs  granted to Mr. Comrie)  may be exercised only  while the original grantee
has a relationship  with the  Company which  confers eligibility  to be  granted
options,  within ninety days after the termination of such relationship with the
Company, or up to  one year after death,  retirement or permanent disability  of
the  optionee. In  the event of  termination for  cause (as defined  in the 1995
Stock Option  Plan), all  options  granted to  that original  grantee  terminate
immediately. Upon a Change of Control (as defined in the 1995 Stock Option Plan)
all  outstanding options become  immediately exercisable, without  regard to any
vesting period, for the full term of  the option. ISOs and NQSOs under the  1995
Stock Option Plan are not transferable other than by will or the laws of descent
and distribution. Options may be exercised during the grantee's lifetime only by
the grantee, his or her guardian or legal representative.
 
    ISOs  granted pursuant to the 1995 Stock Option Plan enjoy the attendant tax
benefits provided under  Sections 421 and  422 of the  Internal Revenue Code  of
1986,  as amended. Accordingly, the 1995  Stock Plan provides that the aggregate
fair market value (determined at the time an ISO is granted) of the Common Stock
subject to  ISOs  exercisable for  the  first time  by  an employee  during  any
calendar  year (under  all plans  of the Company  and its  subsidiaries) may not
exceed $100,000.
 
    The Board  may modify,  suspend or  terminate the  1995 Stock  Option  Plan;
however,  certain material  modifications affecting  the 1995  Stock Option Plan
must be approved by the  stockholders, and any change  in the 1995 Stock  Option
Plan  that may  adversely affect a  grantee's rights under  an option previously
granted under the 1995 Stock Option Plan requires the consent of the grantee.
 
    Mr. Comrie has been granted ISOs expiring June 17, 2002 to purchase  151,338
shares  of Common Stock  at a price of  $0.5907 per share  and NQSOs expiring on
various dates through June 17, 2005  to purchase 605,353 shares of Common  Stock
at a price of $0.5907 per share. The ISOs will be fully vested on July 17, 1997.
Of  the  ISOs,  115,017  are  currently  exercisable,  and  36,321  will  become
exercisable on July 17, 1997. The NQSOs are subject to vesting over a five  year
period.  Of the NQSOs, 302,676 are currently exercisable, and 75,669 will become
exercisable on  July  17, 1997  and  up to  an  additional 227,007  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 March 26,  2001; however, the vesting  of 100,000 of such
 
                                       59
<PAGE>
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 1995 Stock
Option Plan)  and  upon  other  corporate changes  described  in  the  agreement
evidencing his options.
 
    Messrs. Miller and Menatti have been granted ISOs expiring December 29, 2000
to  purchase an aggregate of 85,000 shares of  Common Stock at a price of $1.652
per share. The ISOs vest at a rate  of 20.0% on each anniversary of the date  of
grant.
 
    Mr.  Brown has  been granted  ISOs and NQSOs  expiring February  15, 2001 to
purchase 25,380 and  9,620 shares of  Common Stock, respectively  at a price  of
$3.94  per share. Both the  ISOs and the NQSOs  vest at a rate  of 20.0% on each
anniversary of the date of grant.
 
    THE DIRECTORS  PLAN.   On  April  24, 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  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
 
    Mr. Fotheringham has entered into a three-year employment agreement with the
Company  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 in 1996
is 1,596  equivalent  DS-1  links.  The  goals  for  subsequent  years  will  be
established  each year based  on the operating  budget approved by  the Board of
Directors. The  agreement precludes  Mr. Fotheringham  from competing  with  the
Company  for two years after the cessation  of his employment, regardless of the
reason for such cessation.
 
    Mr. Comrie  has entered  into  a three-year  employment agreement  with  the
Company  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 in 1996 is 1,596  equivalent
DS-1  links. The goals for subsequent years  will be established each year 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
 
                                       60
<PAGE>
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 in 1996 is 1,596  equivalent
DS-1  links. The goals for subsequent years  will be established each year 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 employment agreements with Messrs.  Brown,
Menatti  and Miller, providing for full  time employment at annual base salaries
equal to $125,000, $125,000 and  $150,000, respectively. Each of the  employment
agreements  provides  for  the  payment  by the  Company  of  annual  bonuses in
designated amounts based  upon the achievement  of specified performance  goals.
All  of the agreements have a term  of three years. Each agreement precludes the
executive employee  from competing  with  the Company  for  one year  after  the
cessation  of employment, regardless  of the reason for  such cessation. See "--
Stock Option Plans" regarding stock options granted to certain of the  foregoing
executives  pursuant to their respective  employment agreements. Each employment
agreement may be  terminated at any  time by  the Company or  the executive  and
provides  that,  if the  Company terminates  the executive's  employment without
cause or such person's employment is terminated due to his disability or  death,
such  executive may continue to receive the full amount of their base salary and
any other benefits to which they would have otherwise been entitled for a period
of three months (six months,  in the case of Mr.  Miller) from the date of  such
termination.
 
    Mr.  Pierson entered into a three-year consulting agreement with the Company
on July 17, 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 & Hanley Transactions."
 
                                       61
<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
    The  following table sets  forth certain information, as  of April 22, 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 that the  Series A, B, C,  D, E and F  Preferred Stock have  been
converted  into Common  Stock, the  Merger has  been completed  and the Landover
Partnerships have been dissolved. Prior to the Merger, ART Corp. owns 10,013,055
shares of Common Stock, constituting  33.3% of the Company's outstanding  voting
securities  prior to the Common Stock Offering  and 29.4% after the Common Stock
Offering; these shares will be cancelled on the earlier of (i) completion of the
Merger and (ii) May 13, 1997.
 
<TABLE>
<CAPTION>
                                                                BENEFICIAL OWNERSHIP PRIOR     BENEFICIAL OWNERSHIP AFTER
                                                                       TO OFFERINGS                     OFFERINGS
                                                                ---------------------------  -------------------------------
NAME                                                               NUMBER        PERCENT          NUMBER          PERCENT
- --------------------------------------------------------------  -------------  ------------  -----------------  ------------
<S>                                                             <C>            <C>           <C>                <C>
Vernon L. Fotheringham (1)(2).................................      3,545,074        11.8%       3,545,074                %
W. Theodore Pierson, Jr. (2)(3)...............................      2,455,401         8.2        2,455,401
High Sky Inc. (2)(4)..........................................      1,748,604         5.8        1,748,604
Landover Holdings Corporation (5).............................      8,292,019        27.5        8,292,019
Advent International Corporation (6)..........................      3,186,238        10.5        3,186,238
Ameritech Development Corp. (7)...............................      1,677,745         5.4        1,677,745
Steven D. Comrie (8)..........................................        302,676         1.0          302,676               *
J.C. Demetree, Jr. (9)........................................      1,136,538         3.8        1,136,538
Mark C. Demetree (10).........................................      1,136,538         3.8        1,143,538(11)
Andrew I. Fillat (6)..........................................      3,186,238        10.5        3,193,238(11)
Matthew C. Gove (12)..........................................        441,753         1.5          441,753
Laurence S. Zimmerman (5).....................................      8,292,019        27.5        8,292,019
I. Don Brown (13).............................................          7,000       *                7,000           *
Thomas A. Grina (14)..........................................        100,000       *              100,000           *
Charles D. Menatti (13).......................................          7,000       *                7,000           *
James D. Miller (15)..........................................         10,000       *               10,000           *
All executive officers and directors as a group                    20,620,237        66.7%      10,777,927(16)            %
 (1)(3)(5)(6)(8)(9)(10)(12)(13)(14)(15).......................
</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 3,545,074 shares  of Common Stock issuable  upon completion of  the
    Merger.  Also includes 104,273  shares of Common Stock  subject to an option
    owned by SERP. See "Certain Transactions -- SERP Agreement." Without  giving
    effect  to the Merger, Mr. Fotheringham owns  120 shares of ART Corp. Common
    Stock, constituting 35.3% of the outstanding Common Stock of ART Corp.,  and
    no shares of the Company.
 
(2)  Although Messrs. Fotheringham and Pierson  and High Sky Inc. are directors,
    officers or principal stockholders, as the  case may be, of ART Corp.,  each
    disclaims  beneficial ownership of 10,013,055 shares of Common Stock held by
    ART Corp. except to the extent of his or its respective percentage  interest
    in ART Corp.
 
(3)  Includes 2,455,401 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."  Without giving  effect  to the
    Merger, Mr. Pierson owns 83 shares  of ART Corp. Common Stock,  constituting
    24.4%  of the outstanding  Common Stock of  ART Corp., and  no shares of the
    Company. Mr. Pierson's  address is c/o  Pierson, Burnett &  Hanley, 1667  K.
    Street, N.W., Washington, D.C. 20006.
 
(4)  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  1,398,878  and  349,726  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." Without giving  effect to the Merger,  High Sky owns 48
    shares of  ART Corp.  Common Stock,  constituting 14.1%  of the  outstanding
    Common Stock of ART Corp., and no shares of the Company and High Sky II owns
    12  shares of ART  Corp. Common Stock, constituting  3.5% of the outstanding
    Common Stock of ART  Corp., and no  shares of the  Company. High Sky  Inc.'s
    address  is c/o Frank  S. Phillips Company,  6106 MacArthur Blvd., Bethesda,
    Maryland 20816.
 
                                       62
<PAGE>
(5) Includes 37,500 shares  issuable upon exercise  of Indemnity Warrants.  Does
    not  include 294,487 shares,  1,375,699 shares, 5,276,440  shares and 95,719
    shares 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 15,334,366  shares
    of  Common Stock constituting 50.9%  of the Company's outstanding securities
    prior to the Offerings. LHC is controlled by Laurence S. Zimmerman.  Without
    giving  effect to the Merger,  LHC owns 9 shares  of ART Corp. Common Stock,
    constituting 2.6% of the outstanding Common  Stock of ART Corp., which  will
    convert  into 276,831 shares of Common Stock issuable upon completion of the
    Merger. LHC's address is 667 Madison  Avenue, New York, New York 10021.  See
    "-- Voting Trust Agreement."
 
(6)  Includes 2,882,659  shares, 141,050 shares  and 3,029  shares issuable upon
    conversion of Series E  Preferred Stock 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.
 
(7)  Includes 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."
 
(8)  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."
 
(9)  Includes 81,250 shares  issuable upon exercise  of Indemnity Warrants. Does
    not include  154,000 shares  issuable upon  exercise of  Bridge Warrants  or
    4,221,152  shares held in each case by  members of Mr. Demetree's family, 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 81,250 shares issuable upon  exercise of Indemnity Warrants. Does
    not include  154,000 shares  issuable upon  exercise of  Bridge Warrants  or
    4,221,152  shares held in each case by  members of Mr. Demetree's family, 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 7,000 shares issuable upon  exercise of options anticipated to  be
    granted under the Directors Plan on the date of this Prospectus.
 
(12)   Includes  441,753   shares  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.
 
(13) Includes 7,000 shares currently issuable upon exercise of an option.
 
(14) Includes 100,000 shares currently issuable upon exercise of an option.
 
(15) Includes 10,000 shares currently issuable upon exercise of an option.
 
(16) Reflects the anticipated resignations  of Messrs. J.C. Demetree, Jr.,  Gove
    and  Zimmerman. Does not include 8,292,019  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, Andrew I. Fillat and
    two unaffiliated directors issuable upon  exercise of options to be  granted
    under the Directors Plan on the date of this Prospectus.
 
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  certain  directors  of  the  Company,  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 later to  occur
of  December 31,  1999 and  the payment  in full  in cash  of the  Notes, but is
subject to early termination in the event of (i) a business combination in which
the Notes are repaid in full in cash and ART stockholders own less than 50%, and
ART directors  constitute  less than  50%  of the  board  of directors,  of  the
combined  entity and LHC owns  less than 5% of the  voting power of such entity,
(ii) the death of Laurence S. Zimmerman or (iii) the sale by LHC of such  shares
to  unaffiliated parties. The trustees  of the trust will  be indemnified by the
Company.
 
                                       63
<PAGE>
                              CERTAIN TRANSACTIONS
 
FORMATION OF ART CORP.
 
    The  Company's  business  was  commenced   in  August  1993  by  Vernon   L.
Fotheringham  and  W.  Theodore  Pierson,  Jr.,  who  organized  Advanced  Radio
Technologies Corporation  ("ART Corp.")  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 Corp.  common stock in a  private
placement  which,  net  of certain  subsequent  transfers,  currently constitute
shares of ART Corp. common stock equivalent to an aggregate of 6,000,475  shares
of Common Stock upon completion of the Merger.
 
HIGH SKY PRIVATE PLACEMENTS
 
    In  November  1993 and  March  1994, ART  Corp.  raised $60,000  and $30,000
through the sale of its  common stock (which, net  of sales and acquisitions  of
additional  shares, upon  completion of  the Merger,  will be  converted into an
aggregate of 1,398,878 shares and 349,726 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 June  1994, ART  Corp.
borrowed  $70,000 from High Sky II. The  loan was evidenced by a promissory note
executed by ART Corp. 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 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 ART Corp.  common stock owned by
them. 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
Corp. and Extended. Mark T. Marinkovich, Vice President, Finance 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
Corp.  issued  to  Extended  shares  of  ART  Corp.  common  stock,  which, upon
completion of the Merger will be converted into 368,121 shares of Common  Stock.
Of  these  368,121 shares,  15,678  shares are  subject  to an  option  owned by
Southeast Research Partners. See "-- SERP Agreement."
 
ORGANIZATION OF THE COMPANY
 
    ART Corp. and Landover Holdings Corporation ("LHC") organized Advanced Radio
Telecom Corp. ("ART"  or the  "Company") 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 the Company, respectively, which, after giving effect to
anti-dilution  adjustments  resulting  from  issuances  of  Preferred  Stock  as
described  in "-- LHC Purchase Agreement"  and the transactions described in "--
February 1996  Reorganization"  and "--  Merger,"  currently are  equivalent  to
10,013,855  shares  and  8,320,000,  shares respectively,  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  the  Company's  Class  A  Common  Stock  which,  after   such
adjustments,  transactions and the  Merger, currently are  equivalent to 441,753
shares and 147,251 shares of Common  Stock of the Company, 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.
 
                                       64
<PAGE>
LHC PURCHASE AGREEMENT
 
    GENERAL.  Pursuant to a Purchase  Agreement, dated April 21, 1995 (the  "LHC
Purchase  Agreement") among ART  Corp., LHC and  the Company, LHC,  on behalf of
itself and  its  designees, agreed  to  purchase additional  securities  of  the
Company  (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  Corp. and  the Company entered  into the ART
Corp. Services Agreement with  the Company. See  "Business -- Proposed  Merger."
Moreover,  ART  Corp.  and its  stockholders  agreed  with the  Company  and its
stockholders to  enter into  a  revised stockholders  agreement (the  "May  1995
Stockholders   Agreement"),  a  registration  rights   agreement  and  a  merger
agreement.
 
    Upon the first closing under the LHC Purchase Agreement, on May 8, 1995, the
Company 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 by
the Company. 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 (convertible  into
466,349 shares of Common Stock). 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, the Company, ART Corp. and LHC agreed that the LHC Purchase Agreement  was
substantially completed.
 
    ART  CORP. SERVICES AGREEMENT.  Pursuant  to the LHC Purchase Agreement, ART
Corp. and the Company entered into a Services Agreement, dated May 8, 1995  (the
"ART  Corp.  Services Agreement")  pursuant to  which, for  a 20-year  term, the
Company provides management services  for, and receives 75.0%  of the cash  flow
from  operations  under wireless  licenses held  by ART  Corp. See  "Business --
Agreements Relating  to  Licenses  and  Authorizations  --  ART  Corp.  Services
Agreement."
 
    LANDOVER  PARTNERSHIPS.  Between May 8, 1995  and November 13, 1995, the LHC
Stock was diluted by purchases of series of Company 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 Preferred Stock matching other
investors under the LHC Purchase Agreement, purchased 405,880 shares of Series A
Preferred  Stock  (which  convert into  5,276,440  shares of  Common  Stock upon
consummation of 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 Series  B
Preferred  Stock  (which converts  into 1,375,699  shares  of Common  Stock upon
consummation of the Offerings) for an aggregate of $842,000. E1 purchased 13,797
shares of Series A Preferred Stock (which converts into 179,361 shares of Common
Stock upon consummation of the Offerings) for an aggregate of $60,000 and  8,856
shares of Series B Preferred Stock (which converts into 115,128 shares of Common
Stock  upon consummation  of the  Offerings) for  an aggregate  of $38,300. E2-3
purchased an  aggregate of  7,363  shares of  Series  C Preferred  Stock  (which
converts  into 95,719 shares of Common Stock upon consummation of the Offerings)
for an aggregate of  $112,700. All of the  Landover Partnerships will  liquidate
upon effectiveness of the Merger. See "Principal Stockholders."
 
    ADVENT  PRIVATE PLACEMENT.   On  November 13, 1995,  ART Corp.  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
 
                                       65
<PAGE>
stated  amount of  ART Corp.  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 Corp.,  the Company, 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
Series  E Preferred Stock of the Company (which convert into 3,026,738 shares of
Common Stock upon  completion of the  Offerings). The Series  E Preferred  Stock
provides, among other things, that the holders thereof have a right to designate
a director of 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 the Company 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 the
Company 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
consummation of the Offerings,  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  Corp., 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 Corp.  Under the  SERP
Agreement,  SERP received  options from the  other parties to  such agreement to
purchase, for an aggregate consideration of $210,000, 10.65 shares of ART  Corp.
Common  Stock (equivalent to 313,512 shares  of Common Stock after giving effect
to the Merger) and $245,000 in cash as a fee for introducing LHC to ART Corp.
 
SERIES D PREFERRED STOCK ISSUANCE
 
    On November 9, 1995,  the Company sold 61,640  shares of Series D  Preferred
Stock  (which convert into  801,320 shares of Common  Stock upon consummation of
the  Offerings)  for  $2.0   million  in  a   private  placement.  The   Company
simultaneously  redeemed  807,924  shares  of Common  Stock  from  LHC  for $2.0
million. In connection  with the February  1996 Reorganization described  below,
LHC  granted to the holders  of Series D Preferred  Stock a contingent option to
purchase 400,634 shares of 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,  the  Company,   ART  Corp.  and  their  respective
stockholders agreed 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 the Company, including providing for the conversion  of
Class  A and Class B Common Stock of the Company into Common Stock, the revision
of the  terms  and  conversion  into Common  Stock  (upon  consummation  of  the
Offerings)  of the Series A, B, C, D, E and F Preferred Stock (collectively, the
"Preferred Stock") of the Company and a 13 for 1 stock split, (iii) the exchange
of the Advent/ART Securities for Series  E Preferred Stock of the Company,  (iv)
revision of provisions for
 
                                       66
<PAGE>
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  Escrow Shares  to the  original owners
thereof, (vii) the change of name of the Company to Advanced Radio Telecom Corp.
and (viii)  approval of  a  revised merger  agreement (the  "Merger  Agreement")
providing for the merger of ART Corp. into the Company (the "Merger").
 
MERGER
 
    On  February 2,  1996, the  Company and  ART Corp.  entered into  the Merger
Agreement which provides  for the  Merger of ART  Corp. into  the Company.  Upon
completion  of the Merger, the stockholders of ART Corp. will receive 10,013,855
shares of Common Stock, and the 10,013,855  shares of Common Stock then held  by
ART Corp. will be cancelled. The consummation of the Merger is contingent solely
on  receipt of  FCC approval  therefor. See  "Business --  Proposed Merger." The
Merger Agreement further provides that if the Merger is not approved by the  FCC
by  May  13,  1997, the  shares  of Common  Stock  owned  by ART  Corp.  will be
surrendered to the Company for nominal consideration, and the ART Corp. Services
Agreement will be amended 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 the 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  the  percentage  share  of  the   aggregate
consideration to be paid for ART Corp. and the Company in such transaction.
 
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  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, the
Company 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  five-year  warrant  to  purchase
877,136  shares of Common Stock  of the Company exercisable  at a price of $.001
per share (the "Ameritech Warrant"). On April 29, 1996, the Company entered into
the Ameritech Strategic  Development Agreement. The  Company has a  call on  the
Series  F  Preferred Stock  and  the Ameritech  Warrant  in the  event Ameritech
terminates such agreement in the first two  years of its term. See "Business  --
Strategic Alliances -- Ameritech Strategic Distribution Agreement."
 
BRIDGE FINANCING
 
    On  March  8,  1996,  the  Company entered  into  a  financing  (the "Bridge
Financing") pursuant to which it  issued $5.0 million of  10% notes due in  1998
(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 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 29, 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
 
                                       67
<PAGE>
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 29,
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  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 & HANLEY TRANSACTIONS
 
    W.  Theodore Pierson, Jr.,  Executive Vice President  and General Counsel of
the Company is a principal in the  law firm of Pierson, Burnett & Hanley,  which
regularly  provided legal services to the Company  and ART Corp. During the year
ended December 31, 1995, the Company paid Pierson, Burnett & Hanley $209,000 for
such services. The  Company believes  that the  terms of  its relationship  with
Pierson,  Burnett & Hanley are at least as  favorable to the Company as could be
obtained from an unaffiliated party. 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 &  Hanley. 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 invest, subject to definitive documentation, $700,000
to $1.0  million  for research  and  development. 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.
 
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<PAGE>
                              DESCRIPTION OF UNITS
 
    Each  Unit offered hereby consists of $1,000 principal amount at maturity of
Notes and        Warrants,  each Warrant  initially  representing the  right  to
purchase        shares of Common  Stock. The Notes and  the Warrants will not be
separable until the earliest to occur of (i)               , 1996 and (ii)  such
earlier date as may be determined by the Underwriters (the "Separation Date").
 
                              DESCRIPTION OF NOTES
 
    The  Notes will be  issued under an Indenture  (the "Indenture") between the
Company and             , as trustee (the "Trustee"). A copy of the form of  the
Indenture  has been filed as  an exhibit to the  Registration Statement of which
this Prospectus is a  part. The following summary  of certain provisions of  the
Indenture does not purport to be complete and is subject to, and is qualified in
its  entirety by reference to, the Trust  Indenture Act of 1939, as amended (the
"Trust Indenture Act"), and to all of the provisions of the Indenture, including
the definitions of  certain terms therein  and those  terms made a  part of  the
Indenture  by reference to the Trust Indenture Act,  as in effect on the date of
the Indenture. The definitions  of certain terms used  in the following  summary
are set forth below under "-- Certain Definitions."
 
    As  of the date of the Indenture,  all of the Company's Subsidiaries will be
Restricted Subsidiaries. However, under certain circumstances, the Company  will
be   able  to  designate  future   Subsidiaries  as  Unrestricted  Subsidiaries.
Unrestricted Subsidiaries  will  not  be  subject to  many  of  the  restrictive
covenants set forth in the Indenture.
 
GENERAL
 
    The  Notes will  be general  unsecured obligations  of the  Company, will be
limited to $     million aggregate principal amount at maturity and will  mature
on                 , 2006. The Notes  are being issued at  a discount from their
principal amount to  generate aggregate gross  proceeds of approximately  $125.0
million. The Notes will accrete at a rate of    % compounded semiannually, to an
aggregate principal amount of $     million by             , 2001. Cash interest
will  not  accrue on  the Notes  prior to                    ,  2001. Commencing
            , 2001, cash interest  on the Notes  will be payable,  at a rate  of
   %  per annum, semi-annually in arrears on each              and
(each, an "Interest Payment  Date"), to the  holders of record  of Notes at  the
close  of business on the             and             immediately preceding such
Interest Payment Date.  Cash interest  on the Notes  will accrue  from the  most
recent  Interest Payment Date to  which interest has been  paid or duly provided
for, or, if no interest has been paid or duly provided for,             ,  2001.
Cash  interest will be computed on the basis  of a 360-day year of twelve 30-day
months. If, prior to             , 2001, the Company defaults in any payment  of
principal (including any accreted original issue discount), whether at maturity,
upon  redemption or otherwise, if  the payment of cash  interest on the Notes is
then permitted by law, cash interest will accrue on the amount in default at the
rate of interest borne by the Notes on or after              , 2001 and, if  the
payment  of such cash interest is not  permitted by law, original issue discount
will continue to accrete at the rate then in effect. On or after               ,
2001,  interest on  overdue principal  and, to the  extent permitted  by law, on
overdue installments of interest  will accrue at the  rate of interest borne  by
the Notes.
 
    Principal  of, premium, if any,  and interest on the  Notes will be payable,
and the Notes will be exchangeable and transferable, at the office or agency  of
the  Company  in  The City  of  New  York maintained  for  such  purposes (which
initially will be the office of the Trustee); PROVIDED, HOWEVER, the payment  of
interest  may be  made by  check mailed  to the  address of  the Person entitled
thereto as shown  on the security  register. The  Notes will be  issued only  in
fully  registered form without  coupons and only in  denominations of $1,000 and
any  integral  multiple  thereof.  No  service  charge  will  be  made  for  any
 
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<PAGE>
registration  of transfer, exchange or redemption  of Notes, but the Company may
require payment in certain circumstances of a sum sufficient to cover any tax or
other governmental charge that may be imposed in connection therewith.
 
REDEMPTION
 
    OPTIONAL REDEMPTION
 
    The Notes will be redeemable  at the option of the  Company, in whole or  in
part, at any time on or after             , 2001, upon not less than 30 nor more
than  60 days'  notice, at  the redemption  prices (expressed  as percentages of
principal amount at maturity) set forth below, plus accrued and unpaid interest,
if any, to  the date  of redemption,  if redeemed  during the  12- month  period
beginning on of the years indicated below:
 
<TABLE>
<CAPTION>
                                                             REDEMPTION
                           YEAR                                PRICE
                --------------------------                  ------------
<S>                                                         <C>
2001......................................................            %
2002......................................................            %
2003......................................................            %
2004 and thereafter.......................................     100.000%
</TABLE>
 
    Notwithstanding  the foregoing, in the event of a sale by the Company of its
Common Stock in  one or  more Equity  Offerings or  Investments by  one or  more
Strategic Equity Investors for an aggregate purchase price equal to or exceeding
$70.0  million, on or  prior to                 , 1999, the  Company may, at its
option, use all  or a  portion of the  net proceeds  thereof to redeem  up to  a
maximum  of 33 1/3%  of the initially outstanding  aggregate principal amount at
maturity of the Notes at a redemption price equal to    % of the Accreted  Value
of the Notes (determined as of the redemption date); PROVIDED that not less than
66  2/3% of the initially outstanding  aggregate principal amount at maturity of
the Notes remain outstanding following such redemption. Any such redemption must
be effected upon not less than 30 nor more than 60 days' notice given within  30
days  after any  such Equity  Offering or  sale to  a Strategic  Equity Investor
resulting in such gross proceeds, as the case may be.
 
    MANDATORY REDEMPTION
 
    The Company is not required to  make any mandatory sinking fund payments  in
respect  of the Notes. However, (i) upon  the occurrence of a Change in Control,
the Company is obligated to make an offer to purchase all outstanding Notes at a
price of (A)  101% of  the Accreted  Value thereof  (determined at  the date  of
purchase),  if such purchase is prior to              , 2001, or (B) 101% of the
principal amount at maturity thereof, plus accrued interest thereon, if any,  to
the  date of purchase, if such purchase  is on or after               , 2001 and
(ii) the Company may be  obligated to make an offer  to purchase Notes with  the
Net  Cash Proceeds of certain Asset Sales at a price of (A) 101% of the Accreted
Value thereof (determined at the date of purchase), if such purchase is prior to
            , 2001, or  (B) 101% of  the principal amount  at maturity  thereof,
plus  accrued and  unpaid interest,  if any,  to the  date of  purchase, if such
purchase is on or after             , 2001. See "-- Certain Covenants --  Change
in Control" and "-- Disposition of Proceeds of Asset Sales."
 
    SELECTION; EFFECT OF REDEMPTION NOTICE
 
    In  the case of a partial redemption,  selection of the Notes for redemption
will be made PRO RATA, by lot or by such other method as the Trustee in its sole
discretion deems fair  and appropriate or  in such manner  as complies with  the
requirements of the principal national securities exchange, if any, on which the
Notes being redeemed are listed. Upon giving of a redemption notice, interest on
the  Notes called for  redemption will cease  to accrue from  and after the date
fixed for redemption  (unless the Company  defaults in providing  the funds  for
such  redemption) and, upon redemption on  such redemption date, such Notes will
cease to be outstanding.
 
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<PAGE>
RANKING
 
    The Indebtedness of the Company evidenced by the Notes will rank PARI  PASSU
in  right of  payment with  all existing and  future senior  Indebtedness of the
Company and senior in right of  payment to all existing and future  subordinated
Indebtedness  of the Company. At  December 31, 1995, on  a pro forma basis after
giving effect to indebtedness  incurred after December  31, 1995, the  Offerings
and  the  application of  the net  proceeds  therefrom, the  aggregate principal
amount of senior Indebtedness  of the Company  (excluding trade payables,  other
accrued  liabilities  and  the  Notes)  was  approximately  $4.0  million, which
consisted of notes payable  arising from the acquisition  of the EMI Assets  and
the Equipment Note.
 
CERTAIN COVENANTS
 
    LIMITATION ON INDEBTEDNESS
 
    The  Indenture will provide that  the Company will not,  and will not permit
any of its Subsidiaries  to, Incur any  Indebtedness (including Acquired  Debt);
PROVIDED  that the Company may Incur  Indebtedness (including Acquired Debt) if,
after giving effect to the Incurrence  of such Indebtedness and the receipt  and
application of the proceeds therefrom, the Indebtedness to EBITDA Ratio would be
greater than zero and less than 5 to 1.
 
    The foregoing provisions will not apply to:
 
       (i) Indebtedness  of the Company outstanding at  any time in an aggregate
           principal amount not  to exceed  $100.0 million, less  any amount  of
    Indebtedness  permanently  repaid  as  provided  under  the  "Disposition of
    Proceeds of Asset Sales" covenant described below;
 
       (ii)Indebtedness of any of the Company's Restricted Subsidiaries owing to
           the Company; PROVIDED, HOWEVER, that  (A) any subsequent issuance  or
    transfer  of Capital Stock that results  in any such Indebtedness being held
    by a Person other than the Company and (B) any sale or other transfer of any
    such Indebtedness to a Person  that is not the  Company shall be deemed,  in
    each case, to constitute an Incurrence of such Indebtedness by the Company;
 
       (iii)
           Indebtedness issued in exchange for, or the net proceeds of which are
           used  to refinance  or refund,  then outstanding  Indebtedness, other
    than Indebtedness  Incurred under  clause (i),  (ii), (v)  or (vi)  of  this
    paragraph,  and  any refinancings  thereof in  an amount  not to  exceed the
    amount so refinanced or refunded (plus premiums, accrued interest, fees  and
    expenses);  PROVIDED that  Indebtedness the  proceeds of  which are  used to
    refinance or refund the  Notes or Indebtedness that  is PARI PASSU with,  or
    subordinated in right of payment to, the Notes shall only be permitted under
    this  clause (iii) if  (A) in case the  Notes are refinanced  in part or the
    Indebtedness to  be  refinanced is  PARI  PASSU  with the  Notes,  such  new
    Indebtedness  (by its terms or  by the terms of  any agreement or instrument
    pursuant to which such new Indebtedness is outstanding) is PARI PASSU  with,
    or  is  expressly made  subordinate in  right of  payment to,  the remaining
    Notes, (B) in  case the  Indebtedness to  be refinanced  is subordinated  in
    right of payment to the Notes, such new Indebtedness, by its terms or by the
    terms of any agreement or instrument pursuant to which such new Indebtedness
    is  outstanding, is  expressly made subordinate  in right of  payment to the
    Notes at  least to  the extent  that the  Indebtedness to  be refinanced  is
    subordinated  to the Notes, and (C)  such new Indebtedness, determined as of
    the date of  Incurrence of  such new Indebtedness,  does not  have a  Stated
    Maturity  prior to the Stated Maturity  of the Indebtedness to be refinanced
    or refunded, and the Average Life of such new Indebtedness is at least equal
    to the  remaining Average  Life  of the  Indebtedness  to be  refinanced  or
    refunded;  and PROVIDED  FURTHER that  in no  event may  Indebtedness of the
    Company be  refinanced  by  means  of any  Indebtedness  of  any  Restricted
    Subsidiary of the Company pursuant to this clause (iii);
 
       (iv)Indebtedness  (A) in respect  of performance, surety  or appeal bonds
           provided in the  ordinary course  of business; and  (B) arising  from
    agreements  providing for  indemnification, adjustment of  purchase price or
    similar obligations,  or  from  Guarantees  or  letters  of  credit,  surety
 
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    bonds or performance bonds securing any obligations of the Company or any of
    the  Restricted  Subsidiaries  pursuant  to  such  agreements,  in  any case
    Incurred in  connection with  the  disposition of  any business,  assets  or
    Restricted  Subsidiary of the Company (other than Guarantees of Indebtedness
    Incurred by any Person acquiring all or any portion of such business, assets
    or Restricted Subsidiary of  the Company for the  purpose of financing  such
    acquisition),  in  a  principal  amount not  to  exceed  the  gross proceeds
    actually received by the Company or any Restricted Subsidiary in  connection
    with such disposition;
 
       (v) without  duplication  of clause  (viii)  hereof, Indebtedness  of the
           Company not to  exceed, at  any one  time outstanding,  two TIMES  an
    amount  equal to (A) the aggregate  net proceeds (which proceeds may consist
    of cash, Capital Stock  of an entity  that as a  result of such  transaction
    becomes a Restricted Subsidiary of the Company, or Telecommunications Assets
    which  in connection with such  transaction become held by  the Company or a
    Restricted Subsidiary of the Company, and the value of which proceeds  shall
    be  the fair market value thereof as  determined in good faith by the Board,
    which in  all  events shall  deduct  the  face amount  of  any  Indebtedness
    associated  with such Capital  Stock or Telecommunications  Assets in making
    such determination) received by  the Company from the  issuance and sale  of
    its  Capital Stock  (other than  Redeemable Stock  and Preferred  Stock that
    provides for the  payment of dividends  in cash) MINUS  (B) the fair  market
    value  of any Directed Investments made  with the proceeds of such issuances
    or sales; PROVIDED that such Indebt-
    edness (x) does not have a Stated  Maturity prior to the Stated Maturity  of
    the Notes and has an Average Life longer than the Notes and (y) is unsecured
    and is expressly subordinated in right of payment to the Notes;
 
       (vi)Indebtedness  to  the extent  such Indebtedness  is secured  by Liens
           permitted under clause (xxiv) of the definition of "Permitted Liens;"
 
       (vii)
           Indebtedness of the Company, to  the extent the proceeds thereof  are
           immediately  used to purchase Notes tendered  in an Offer to Purchase
    made as a result of a Change in Control;
 
       (viii)
           without duplication of clause (v) hereof, Indebtedness of the Company
           Incurred in connection with the acquisition of (A) 38 GHz licenses or
    authorizations through auctions conducted by  the FCC or (B) other  licenses
    or  authorizations through other spectrum auctions conducted by the FCC with
    respect  to  other   frequencies  approved   for  microwave   point-to-point
    transmissions,  in an amount not to exceed, at any one time outstanding, the
    greater of (1) $10.0 million and (2) the aggregate net proceeds received  by
    the  Company from  an offering of  its Capital Stock  (other than Redeemable
    Stock and Preferred  Stock that  provides for  the payment  of dividends  in
    cash);  PROVIDED that such Indebtedness (x)  does not have a Stated Maturity
    prior to the Stated  Maturity of the  Notes and has  an Average Life  longer
    than  the Notes and (y)  is unsecured and is PARI  PASSU in right of payment
    with the Notes;
 
       (ix)revolving credit Indebtedness of  any Restricted Subsidiary  Incurred
           pursuant  to a credit facility in  an aggregate amount not to exceed,
    at any  one  time  outstanding,  the  greater  of  62.5%  and  such  greater
    percentage  permitted  pursuant  to  such credit  facility  of  the accounts
    receivable net of reserves and allowances for doubtful accounts,  determined
    in  accordance with GAAP,  of such Restricted  Subsidiary and its Restricted
    Subsidiaries (without duplication); PROVIDED  that such Indebtedness is  not
    Guaranteed by the Company or any of its other Restricted Subsidiaries;
 
       (x) the  Incurrence by the Company or  any of its Restricted Subsidiaries
           of Hedging Obligations that are Incurred for the purpose of fixing or
    hedging interest rate risk with respect to any floating rate Indebtedness of
    the Company  or any  Restricted Subsidiary,  as  the case  may be,  that  is
    permitted by the terms of the Indenture to be outstanding;
 
       (xi)the   Incurrence  by  the   Company's  Unrestricted  Subsidiaries  of
           Non-Recourse Debt, PROVIDED, HOWEVER,  that if any such  Indebtedness
    ceases  to be  Non-Recourse Debt of  an Unrestricted  Subsidiary, such event
    shall be deemed to constitute an incurrence of Indebtedness by a  Restricted
    Subsidiary of the Company;
 
                                       72
<PAGE>
       (xii)
           the  Incurrence by  Unrestricted Subsidiaries of  Indebtedness to the
           Company or any  Restricted Subsidiary  of the Company  to the  extent
    permitted by the "Limitation on Restricted Payments" covenant;
 
       (xiii)
           Indebtedness of the Company existing on the Issue Date; and
 
       (xiv)
           Indebtedness  of  the  Company  represented  by  the  Notes  and  the
           Indenture.
 
    For  purposes   of  determining   compliance   with  this   "Limitation   on
Indebtedness"  covenant, in  the event  that an  item of  Indebtedness meets the
criteria of more than one  of the types of  Indebtedness described in the  above
clauses,  the  Company, in  its  sole discretion,  shall  classify such  item of
Indebtedness and  only  be required  to  include the  amount  and type  of  such
Indebtedness in one of such clauses.
 
    The  Company will  not, and  will not  permit any  Restricted Subsidiary to,
Incur any Guarantee of Indebtedness of any Unrestricted Subsidiary.
 
    LIMITATION ON RESTRICTED PAYMENTS
 
    The Indenture will provide  that the Company will  not, and will not  permit
any  Restricted Subsidiary  to, directly or  indirectly, (i) declare  or pay any
dividend or make any distribution on its Capital Stock (other than dividends  or
distributions  payable solely in  shares of its  or such Restricted Subsidiary's
Capital Stock (other than Redeemable Stock) held by such holders or in  options,
warrants  or other rights  to acquire such  shares of Capital  Stock) other than
such Capital Stock  held by the  Company or any  of its Restricted  Subsidiaries
(and  other  than  pro  rata  dividends  or  distributions  on  Common  Stock of
Restricted Subsidiaries), (ii) repurchase,  redeem, retire or otherwise  acquire
for  value any  shares of  Capital Stock  (including options,  warrants or other
rights to acquire such shares of Capital  Stock) of the Company (other than  any
such Capital Stock held by the Company or any Wholly Owned Restricted Subsidiary
of  the Company),  (iii) make  any voluntary  or optional  principal payment, or
voluntary or optional redemption,  repurchase, defeasance, or other  acquisition
or  retirement for value, of Indebtedness of the Company that is subordinated in
right of  payment  to the  Notes  or (iv)  make  any Investment,  other  than  a
Permitted  Investment, in  any Person (including  any Affiliate  of the Company)
(such payments or any other actions described in clauses (i) through (iv)  being
collectively  "Restricted Payments") if, at the time of, and after giving effect
to, the proposed Restricted Payment:
 
       (A) a Default or Event of Default shall have occurred and be continuing;
 
       (B) except with  respect  to any  Investment  (other than  an  Investment
           consisting  of  the  designation  of a  Restricted  Subsidiary  as an
    Unrestricted Subsidiary),  the Company  could not  Incur at  least $1.00  of
    Indebtedness  under the first paragraph  of the "Limitation on Indebtedness"
    covenant; and
 
       (C) the aggregate amount expended for all Restricted Payments (the amount
           so expended, if other than in cash, to be determined in good faith by
    the Board,  whose  determination shall  be  conclusive and  evidenced  by  a
    resolution  of the Board) after  the Issue Date shall  exceed the sum of (1)
    50% of the aggregate amount of the Adjusted Consolidated Net Income (or,  if
    the  Adjusted Consolidated Net Income is a  loss, MINUS 100% of such amount)
    (determined by excluding income  resulting from transfers  of assets by  the
    Company or a Restricted Subsidiary to an Unrestricted Subsidiary) accrued on
    a  cumulative  basis  during the  period  (taken as  one  accounting period)
    beginning on the first day of  the fiscal quarter immediately following  the
    Issue  Date and ending on the last  day of the last fiscal quarter preceding
    the date  for  which reports  have  been  filed pursuant  to  the  "Reports"
    covenant,  PLUS (2) the aggregate Net  Cash Proceeds received by the Company
    after the Issue Date from the  issuance and sale permitted by the  Indenture
    of  its Capital Stock (other than Redeemable Stock) to a Person who is not a
    Subsidiary of the Company,  or from the  issuance to a Person  who is not  a
    Subsidiary  of  the Company  of  any options,  warrants  or other  rights to
    acquire Capital  Stock  of the  Company  (in  each case,  exclusive  of  any
    convertible Indebtedness, Redeemable Stock or any options, warrants or other
    rights  that are redeemable at the option  of the holder, or are required to
    be redeemed, prior  to the Stated  Maturity of the  Notes), MINUS an  amount
    equal to the
 
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    lesser  of (x) 50% of  the aggregate net cash  proceeds from the issuance of
    Capital Stock by the Company for the purpose of making Directed  Investments
    and  (y) the actual amount  of cash used to  make such Directed Investments,
    PLUS (3) an  amount equal to  the net reduction  in Investments (other  than
    reductions  in Permitted Investments) in  any Person resulting from payments
    of interest on Indebtedness, dividends, repayments of loans or advances,  or
    other  transfers of assets,  in each case  to the Company  or any Restricted
    Subsidiary (except  to  the extent  any  such  payment is  included  in  the
    calculation  of Adjusted Consolidated Net Income), or from the redesignation
    of Unrestricted Subsidiaries as Restricted Subsidiaries (valued in each case
    as provided in the definition of "Investments"), not to exceed the amount of
    Investments previously made by the  Company and its Restricted  Subsidiaries
    in such Person.
 
        The foregoing provision shall not be violated by reason of:
 
       (i) the  payment  of  any  dividend  within 60  days  after  the  date of
           declaration thereof if,  at said  date of  declaration, such  payment
    would comply with the foregoing paragraph;
 
       (ii)the  redemption,  repurchase,  defeasance  or  other  acquisition  or
           retirement for value of Indebtedness that is subordinated in right of
    payment to the  Notes, including  premium, if  any, and  accrued and  unpaid
    interest,  with the proceeds  of, or in  exchange for, Indebtedness Incurred
    under  clause  (iii)  of  the   second  paragraph  of  the  "Limitation   on
    Indebtedness" covenant;
 
       (iii)
           the  repurchase, redemption or other  acquisition of Capital Stock of
           the Company (or  options, warrants  or other rights  to acquire  such
    Capital  Stock) in exchange for,  or out of the  proceeds of a substantially
    concurrent offering  of, shares  of Capital  Stock or  options, warrants  or
    other  rights  to  acquire  such  Capital Stock  (in  each  case  other than
    Redeemable Stock) of the Company;
 
       (iv)the making  of  any  principal  payment  or  repurchase,  redemption,
           retirement, defeasance or other acquisition for value of Indebtedness
    of  the Company which  is subordinated in  right of payment  to the Notes in
    exchange for, or out of the proceeds of, a substantially concurrent offering
    of, shares  of the  Capital  Stock of  the  Company (other  than  Redeemable
    Stock);
 
       (v) payments   or  distributions,  in  the   nature  of  satisfaction  of
           dissenters'  rights,   pursuant   to   or  in   connection   with   a
    consolidation,   merger  or  transfer  of  assets  that  complies  with  the
    provisions of  the  Indenture  applicable  to  mergers,  consolidations  and
    transfers  of all  or substantially  all of the  property and  assets of the
    Company;
 
       (vi)any purchase or acquisition from, or withholding on issuances to, any
           employee of  the Company's  Capital  Stock in  order to  satisfy  any
    applicable federal, state or local tax payments in respect of the receipt of
    shares of the Company's Capital Stock;
 
       (vii)
           any purchase or acquisition from, or withholding on issuances to, any
           employee  of the Company's Capital Stock in order to pay the purchase
    price of  such Capital  Stock  or similar  instrument  pursuant to  a  stock
    option,  equity incentive or other employee benefit plan or agreement of the
    Company or any of its Restricted Subsidiaries;
 
       (viii)
           the repurchase of shares  of, or options to  purchase shares of,  the
           Company's  Capital Stock from employees  of the Company in connection
    with the termination of  their employment; PROVIDED  that (A) the  aggregate
    price  paid for  all such  repurchased shares of  Capital Stock  made in any
    twelve-month period  shall  not  exceed $250,000  PLUS  the  aggregate  cash
    proceeds  received by the  Company during such  twelve-month period from any
    reissuance of such Capital Stock by the Company to employees of the  Company
    and  its Restricted Subsidiaries and (B)  no Default shall have occurred and
    be continuing immediately after such transaction;
 
       (ix)payments and  distributions pursuant  to  any tax  sharing  agreement
           between the Company and any other Person with which the Company files
    a  consolidated  tax  return  or  with  which  the  Company  is  part  of  a
    consolidated group, in each case, for federal income tax purposes; and
 
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       (x) cash payments in lieu of the issuance of fractional shares of  Common
           Stock  of the Company upon conversion of any class of Preferred Stock
    of the Company;
 
PROVIDED that, except in the case of  clauses (i) and (ii), no Default or  Event
of  Default shall have occurred  and be continuing or  occur as a consequence of
the actions or  payments set forth  herein. Any Investments  made other than  in
cash shall be valued, in good faith, by the Board.
 
    Each Restricted Payment permitted pursuant to the preceding paragraph (other
than the Restricted Payment referred to in clause (ii) thereof) and the Net Cash
Proceeds  from any issuance of Capital Stock referred to in clause (iii) or (iv)
shall be included  in calculating whether  the conditions of  clause (C) of  the
first  paragraph of this "Limitation on  Restricted Payments" covenant have been
met with  respect  to any  subsequent  Restricted  Payments. In  the  event  the
proceeds  of  an issuance  of  Capital Stock  of the  Company  and used  for the
redemption, repurchase or other acquisition of the Notes or Indebtedness that is
PARI PASSU with the Notes, then the Net Cash Proceeds of such issuance shall  be
included  in clause (C) of the first paragraph of this "Limitation on Restricted
Payments" covenant  only to  the extent  such  proceeds are  not used  for  such
redemption, repurchase or other acquisition of Indebtedness.
 
    The  Board may  designate any  Restricted Subsidiary  to be  an Unrestricted
Subsidiary if such designation  would not cause a  Default; PROVIDED that in  no
event  shall the  Telecommunications Assets of  the business  currently owned or
managed by  the Company  on the  Issue  Date be  transferred to  or held  by  an
Unrestricted   Subsidiary.  For  purposes  of  making  such  determination,  all
outstanding Investments by the Company  and its Restricted Subsidiaries  (except
to  the extent repaid in cash) in the Subsidiary so designated will be deemed to
be Restricted  Payments at  the time  of such  designation and  will reduce  the
amount  available  for Restricted  Payments under  the  first paragraph  of this
covenant.  All  such  outstanding  Investments  will  be  deemed  to  constitute
Investments   in  an  amount  valued  in   accordance  with  the  definition  of
"Investment." Such designation will only be permitted if such Restricted Payment
would be permitted  at such  time and  if such  Restricted Subsidiary  otherwise
meets the definition of an Unrestricted Subsidiary.
 
    LIMITATION ON LIENS SECURING CERTAIN INDEBTEDNESS
 
    The  Indenture will provide that  the Company will not,  and will not permit
any Subsidiary to, create, Incur, assume or suffer to exist any Lien, other than
Permitted Liens, on any  of its assets  or properties of  any character, or  any
shares  of  Capital  Stock or  Indebtedness  of any  Subsidiary,  without making
effective provision for all  of the Notes  and all other  amounts due under  the
Indenture to be directly secured equally and ratably with (or, if the obligation
or  liability to be secured by such Lien  is subordinated in right of payment to
the Notes prior to) the obligation or liability secured by such Lien.
 
    LIMITATION ON DIVIDEND AND OTHER PAYMENT RESTRICTIONS AFFECTING RESTRICTED
SUBSIDIARIES
 
    The Indenture will provide  that the Company will  not, and will not  permit
any  Restricted Subsidiary to, create  or otherwise cause or  suffer to exist or
become effective any consensual  encumbrance or restriction of  any kind on  the
ability  of  any  Restricted  Subsidiary  to (i)  pay  dividends  or  make other
distributions  permitted  by  applicable  law  on  any  Capital  Stock  of  such
Restricted  Subsidiary owned by the Company  or any other Restricted Subsidiary,
(ii) pay any Indebtedness owed to the Company or any other Restricted Subsidiary
that owns,  directly  or  indirectly,  any  Capital  Stock  of  such  Restricted
Subsidiary,  (iii) make loans or advances to the Company or any other Restricted
Subsidiary that  owns,  directly  or  indirectly,  any  Capital  Stock  of  such
Restricted  Subsidiary or  (iv) transfer  any of its  property or  assets to the
Company or any other  Restricted Subsidiary that  owns, directly or  indirectly,
any Capital Stock of such Restricted Subsidiary.
 
    The   foregoing   provisions  shall   not   prohibit  any   encumbrances  or
restrictions:
 
       (i) existing on the Issue Date in the Indenture or any other agreement in
           effect on the Issue Date, and any extensions, refinancings,  renewals
    or replacements of such agreements; PROVIDED that
 
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<PAGE>
    the  encumbrances  and restrictions  in  any such  extensions, refinancings,
    renewals or replacements are  no less favorable in  any material respect  to
    the  holders than those encumbrances or restrictions that are then in effect
    and that are being extended, refinanced, renewed or replaced;
 
       (ii)existing under or by reason of applicable law;
 
       (iii)
           existing with respect to any Person or the property or assets of such
           Person acquired by the Company  or any Restricted Subsidiary, at  the
    time  of such acquisition  and not Incurred  in contemplation thereof, which
    encumbrances or  restrictions  are  not  applicable to  any  Person  or  the
    property  or assets of any Person other  than such Person or the property or
    assets of such Person so acquired;
 
       (iv)in the case of clause (iv) of the first paragraph of this "Limitation
           on Dividend  and  Other  Payment  Restrictions  Affecting  Restricted
    Subsidiaries"  covenant,  (A)  that  restrict  in  a  customary  manner  the
    subletting, assignment or transfer of any property or asset that is a lease,
    license, conveyance or contract or  similar property or asset, (B)  existing
    by  virtue of any transfer  of, agreement to transfer,  option or right with
    respect to,  or Lien  on,  any property  or assets  of  the Company  or  any
    Restricted  Subsidiary,  not otherwise  prohibited by  the Indenture  or (C)
    arising or agreed to in the ordinary course of business, not relating to any
    Indebtedness, and that  do not,  individually or in  the aggregate,  detract
    from  the  value of  property or  assets  of the  Company or  any Restricted
    Subsidiary  in  any  manner  material  to  the  Company  or  any  Restricted
    Subsidiary; or
 
       (v) with  respect to a  Restricted Subsidiary and  imposed pursuant to an
           agreement that has been entered into  for the sale or disposition  of
    all or substantially all of the Capital Stock of, or property and assets of,
    such Restricted Subsidiary.
 
    Nothing  contained  in  this  "Limitation  on  Dividend  and  Other  Payment
Restrictions Affecting  Restricted  Subsidiaries"  covenant  shall  prevent  the
Company  or any Restricted Subsidiary from  (a) creating, Incurring, assuming or
suffering to exist  any Liens otherwise  permitted in the  "Limitation on  Liens
Securing  Certain Indebtedness"  covenant or (b)  restricting the  sale or other
disposition of  property or  assets of  the  Company or  any of  its  Restricted
Subsidiaries  that secure Indebtedness  of the Company or  any of its Restricted
Subsidiaries.
 
    LIMITATION ON TRANSACTIONS WITH AFFILIATES
 
    The Indenture will provide  that the Company will  not, and will not  permit
any  of  its  Restricted Subsidiaries  to,  sell, lease,  transfer  or otherwise
dispose of any  of its  properties or  assets to,  or purchase  any property  or
assets from, or enter into or make any contract, agreement, understanding, loan,
advance  or  guarantee with,  or any  contract, agreement,  understanding, loan,
advance or guarantee  for the specific  benefit of, any  Affiliate (each of  the
foregoing, an "Affiliate Transaction"), unless (i) such Affiliate Transaction is
on  terms that are no  less favorable to the  Company or the relevant Restricted
Subsidiary than those that would have been obtained in a comparable  transaction
by  the Company or such Restricted Subsidiary  with an unrelated Person and (ii)
the  Company  delivers  to  the  Trustee  (A)  with  respect  to  any  Affiliate
Transaction  involving  aggregate consideration  in  excess of  $1.0  million, a
resolution of  the Board  of Directors  set forth  in an  Officers'  Certificate
certifying  that such Affiliate  Transaction complies with  clause (A) above and
that such  Affiliate  Transaction  has  been  approved  by  a  majority  of  the
disinterested  members of  the Board  of Directors and  (B) with  respect to any
Affiliate Transaction  involving  aggregate  consideration  in  excess  of  $5.0
million and (1) involving the incurrence of Indebtedness, a written opinion of a
nationally  recognized investment banking or  accounting firm experienced in the
review of similar  types of  transactions, (2)  involving the  transfer of  real
property,  fixed assets or equipment, either directly or by a transfer of 50% or
more of the Capital Stock of a  Restricted Subsidiary which holds any such  real
property,  fixed  assets or  equipment, a  written  appraisal from  a nationally
recognized appraiser experienced in the review of similar types of  transactions
or (3) not otherwise described in (1) or (2) above, a written certification from
a  nationally recognized professional experienced in evaluating similar types of
transactions, in each case, stating that the terms
 
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of such transaction are  fair to the Company  or such Restricted Subsidiary,  as
the  case may be,  from a financial  point of view;  PROVIDED that the following
shall not be deemed to constitute Affiliate Transactions:
 
       (i) the payment of reasonable  fees to directors of  the Company who  are
           not employees of the Company;
 
       (ii)agreements and arrangements existing on the date hereof;
 
       (iii)
           any  employment agreement entered  into by the Company  or any of its
           Restricted Subsidiaries in  the ordinary  course of  business of  the
    Company or such Restricted Subsidiary;
 
       (iv)the  adoption of  employee benefit  plans in  the ordinary  course of
           business and  payments and  other transactions  thereunder;  PROVIDED
    that  any  such  adoption,  payment or  other  transaction  shall  have been
    approved by a majority of the disinterested members of the Board;
 
       (v) transactions between or  among the  Company and/or  its Wholly  Owned
           Restricted Subsidiaries;
 
       (vi)any  contract, agreement,  understanding, loan,  advance or guarantee
           for  the  general  benefit  of  the  Company  and  its  stockholders,
    including stockholders that are Affiliates of the Company; and
 
       (vii)
           transactions  permitted by the provisions  of the Indenture described
           above under the caption "-- Limitation on Restricted Payments."
 
    LIMITATION ON ISSUANCES AND SALES OF CAPITAL STOCK OF WHOLLY OWNED
RESTRICTED SUBSIDIARIES
 
    The Indenture will  provide that  the Company will  not sell,  and will  not
permit  any Restricted Subsidiary, directly or  indirectly, to issue or sell any
shares of Capital Stock of a Restricted Subsidiary (including options,  warrants
or  other rights  to purchase shares  of such  Capital Stock) except  (i) to the
Company or a  Wholly Owned  Restricted Subsidiary,  (ii) issuances  or sales  to
foreign  nationals of shares  of Capital Stock  of foreign Restricted Restricted
Subsidiaries, to the extent  required by applicable  law, (iii) if,  immediately
after  giving effect to such issuance  or sale, such Restricted Subsidiary would
no longer  constitute a  Restricted Subsidiary  or (iv)  issuances or  sales  of
Common  Stock  of Restricted  Subsidiaries, if  within six  months of  each such
issuance or sale, the  Company or such Restricted  Subsidiary applies an  amount
not  less than the Net Cash Proceeds  thereof (if any) in accordance with clause
(A) or (B)  of the  first paragraph  of the  "Disposition of  Proceeds of  Asset
Sales" covenant described below.
 
    BUSINESS ACTIVITIES OF THE COMPANY
 
    The  Company will  not, and  will not  permit any  Restricted Subsidiary to,
engage in (i) any business other  than the Telecommunications Business and  such
business  activities as are incidental or related thereto and (ii) any business,
activities or services in which the Company and its Restricted Subsidiaries were
engaged on the Issue Date.
 
    CHANGE IN CONTROL
 
    In the  event  of  a  Change  in Control,  the  Company  must  commence  and
consummate  an  Offer to  Purchase  for all  the  Notes then  outstanding,  at a
purchase price equal to (i) 101% of  the Accreted Value thereof, in the case  of
any  such purchase prior to               , 2001,  or (ii) 101% of the principal
amount at maturity thereof, together with  accrued and unpaid interest, if  any,
to  the  date  of  purchase, in  the  case  of  any such  purchase  on  or after
            , 2001. Within 20 days following any Change in Control, the  Company
will  mail a  notice to each  holder describing the  transaction or transactions
that constitute the Change in Control and offering to repurchase Notes  pursuant
to  the procedures required by  the Indenture and described  in such notice. The
Company will comply with the requirements  of Rule 14e-1 under the Exchange  Act
and  any  other  securities  laws  and  regulations  thereunder  to  the  extent
 
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such laws and regulations  are applicable in connection  with the repurchase  of
the Notes as a result of a Change in Control. The Company will publicly announce
the  results of  the Offer to  Purchase on or  as soon as  practicable after the
Change in Control payment date.
 
    Except as described above with respect to a Change in Control, the Indenture
does not contain provisions that permit the holders of the Notes to require that
the Company  repurchase  or  redeem  the  Notes in  the  event  of  a  takeover,
recapitalization  or similar restructuring.  There can be  no assurance that the
Company will  have sufficient  funds available  at  the time  of any  Change  in
Control  to make any  debt payment (including repurchases  of Notes) required by
the foregoing covenant (as well as may  be contained in other securities of  the
Company which might be outstanding at the time).
 
    DISPOSITION OF PROCEEDS OF ASSET SALES
 
    The  Indenture will provide that  the Company will not,  and will not permit
any Restricted  Subsidiary  to,  consummate  any  Asset  Sale,  unless  (a)  the
consideration  received by the Company or such Restricted Subsidiary is at least
equal to the  fair market value  of the assets  sold or disposed  of and (b)  at
least  85%  of the  consideration received  consists of  cash or  Temporary Cash
Investments, PROVIDED  that  any notes  or  other obligations  received  by  the
Company or any such Restricted Subsidiary as consideration that are converted by
the  Company or  such Restricted  Subsidiary into cash  within 30  days of their
receipt (to the extent  of the cash  received), shall be deemed  to be cash  for
purposes  of this provision.  In the event and  to the extent  that the Net Cash
Proceeds received by the Company or its Restricted Subsidiaries from one or more
Asset Sales occurring on or after the Issue Date in any period of 12 consecutive
months exceed 10% of Adjusted Consolidated Net Tangible Assets (determined as of
the date  closest  to the  commencement  of such  12-month  period for  which  a
consolidated  balance sheet of  the Company and  its Restricted Subsidiaries has
been prepared), then the  Company shall or shall  cause the relevant  Restricted
Subsidiary to (i) within six months after the date Net Cash Proceeds so received
exceed  10% of  Adjusted Consolidated  Net Tangible  Assets (A)  apply an amount
equal to  such excess  Net  Cash Proceeds  to permanently  repay  unsubordinated
Indebtedness   of  the  Company  or  any  of  its  Restricted  Subsidiaries,  or
Indebtedness of any Restricted Subsidiary, in each case owing to a Person  other
than  the Company or any  of its Restricted Subsidiaries  or (B) invest an equal
amount, or the amount  not so applied  pursuant to clause (A)  (or enter into  a
definitive agreement committing to so invest within six months after the date of
such agreement), in property or assets of a nature or type or that are used in a
business  (or in a  company having property and  assets of a  nature or type, or
engaged in a business) similar or related to the nature or type of the  property
and  assets of, or the business of,  the Company and its Restricted Subsidiaries
existing on the  date of such  Investment (as  determined in good  faith by  the
Board,  whose determination shall be conclusive and evidenced by a resolution of
the Board and (ii) apply (no later than the end of the six-month period referred
to in clause  (i)) such  excess Net  Cash Proceeds  (to the  extent not  applied
pursuant  to  clause  (i))  as  provided  in  the  following  paragraph  of this
"Disposition of Proceeds of Asset Sales" covenant. The amount of such excess Net
Cash Proceeds required to be applied (or  to be committed to be applied)  during
such  six-month period as set forth in  clause (i) of the preceding sentence and
not applied as so required  by the end of  such period shall constitute  "Excess
Proceeds."
 
    If,  as of  the first  day of  any calendar  month, the  aggregate amount of
Excess Proceeds not theretofore subject to an Offer to Purchase pursuant to this
"Limitation on Asset Sales" covenant totals  at least $5.0 million, the  Company
must  commence, not  later than  the fifteenth business  day of  such month, and
consummate an  Offer  to Purchase  from  the holders  on  a pro  rata  basis  an
aggregate  principal amount of Notes equal to  the Excess Proceeds on such date,
at a purchase price equal to (i) 101% of the Accreted Value thereof  (determined
at  the date of purchase), if such purchase is  prior to              , 2001, or
(ii) 101% of the principal amount  at maturity thereof, plus accrued and  unpaid
interest,  if any,  to the  date of purchase,  if such  purchase is  on or after
            , 2001.
 
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<PAGE>
    NO AMENDMENT TO AGREEMENT
 
    The Indenture will provide that the Company will not amend, modify or  alter
the Voting Trust Agreement without having obtained the consent of the holders of
not  less than  a majority  in principal  amount at  maturity of  the Notes then
outstanding.
 
    REPORTS
 
    The Indenture will provide  that, whether or not  required by the rules  and
regulations  of the  Securities and  Exchange Commission  (the "Commission"), so
long as any Notes are  outstanding, the Company will  furnish to the Holders  of
Notes  (i) all quarterly and annual financial information that would be required
to be contained in a  filing with the Commission on  Forms 10-Q and 10-K if  the
Company  were required to file such  Forms, including a "Management's Discussion
and Analysis of Financial Condition and Results of Operations" and, with respect
to the annual  information only,  a report  thereon by  the Company's  certified
independent  accountants and (ii) all current  reports that would be required to
be filed with the Commission on Form 8-  K if the Company were required to  file
such  reports. In addition, whether or not required by the rules and regulations
of the Commission,  the Company will  file a  copy of all  such information  and
reports  with the Commission for public availability (unless the Commission will
not accept such  a filing)  and make  such information  available to  securities
analysts and prospective investors upon request.
 
CONSOLIDATION, MERGER, SALE OF ASSETS, ETC.
 
    The  Indenture will  provide that  the Company  shall not  consolidate with,
merge with or into, or sell, convey, transfer, lease or otherwise dispose of all
or substantially all of its property and assets (as an entirety or substantially
an entirety in  one transaction  or a series  of related  transactions) to,  any
Person  (other  than a  consolidation  or merger  with  or into  a  Wholly Owned
Restricted Subsidiary with a  positive net worth;  PROVIDED that, in  connection
with any such merger or consolidation, no consideration (other than Common Stock
in  the surviving Person, or the Company)  shall be issued or distributed to the
stockholders of the  Company) or permit  any Person  to merge with  or into  the
Company  unless: (i) the Company  shall be the continuing  Person, or the Person
(if other  than the  Company) formed  by such  consolidation or  into which  the
Company  is merged or  that acquired or  leased such property  and assets of the
Company shall be a corporation organized and validly existing under the laws  of
the  United States  of America or  any jurisdiction thereof  and shall expressly
assume, by a supplemental indenture, executed and delivered to the Trustee,  all
of  the obligations of the Company on all  of the Notes and under the Indenture;
(ii) immediately after giving effect to such transaction, no Default or Event of
Default shall have occurred  and be continuing;  (iii) immediately after  giving
effect  to such  transaction on  a pro  forma basis  the Company,  or any Person
becoming the  successor obligor  of the  Notes  could Incur  at least  $1.00  of
Indebtedness  under  the first  paragraph  of the  "Limitation  on Indebtedness"
covenant; PROVIDED that this clause (iii) shall not apply to (A) the merger of a
corporation, the sole material  asset of which consists  of Common Stock of  the
Company  (and  options, warrants  or other  rights to  purchase or  acquire such
Common Stock),  into the  Company, if  (a) the  Chief Executive  Officer of  the
Company  delivers to  the Trustee  a certificate,  in the  form attached  to the
Indenture as Schedule I, to the effect  that to his best knowledge there are  no
liabilities,  contingent  or otherwise,  of such  corporation  and (b)  the only
consideration received by  the stockholders  of such  corporation in  connection
with  such merger consists of Common Stock of the Company (and options, warrants
or other rights to purchase or acquire  such Common Stock), in the aggregate  in
an  amount not to exceed the amount thereof held by such corporation immediately
prior to such merger or (B)  any transaction or series of transactions  effected
solely  for the purpose  of creating a  parent corporation of  which the Company
shall be a Wholly Owned Subsidiary and whose stockholders shall be substantially
identical to those  of the Company  immediately prior to  such transaction;  and
(iv) the Company delivers to the Trustee an Officers' Certificate (attaching the
arithmetic  computations  to demonstrate  compliance with  clause (iii))  and an
Opinion of Counsel,  in each  case stating  that such  consolidation, merger  or
transfer  and such supplemental indenture complies  with this provision and that
all conditions precedent provided for  herein relating to such transaction  have
been  complied  with;  PROVIDED,  HOWEVER,  that  clause  (iii)  above  does not
 
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<PAGE>
apply if, in the  good faith determination  of the Board  of the Company,  whose
determination  shall be  evidenced by a  resolution of the  Board, the principal
purpose of  such transaction  is to  change the  state of  incorporation of  the
Company; and PROVIDED FURTHER that any such transaction shall not have as one of
its purposes the evasion of the foregoing limitations.
 
EVENTS OF DEFAULT AND REMEDIES
 
    The following events are "Events of Default" under the Indenture:
 
       (i) default  in the payment of interest on  the Notes when it becomes due
           and payable, and continuance of such default for a period of 30  days
    or more; or
 
       (ii)default  in the payment of  principal of, or premium,  if any, on the
           Notes when due; or
 
       (iii)
           default in  the performance,  or breach,  of any  covenant  described
           under  "Certain Covenants -- Limitation  on Restricted Payments," "--
    Limitation on  Indebtedness," "--  Change in  Control," "--  Disposition  of
    Proceeds  of Asset Sales" and "Consolidation, Merger, Sale of Assets, Etc.";
    or
 
       (iv)default in  the  performance,  or  breach, of  any  covenant  in  the
           Indenture (other than defaults specified in clause (i), (ii) or (iii)
    above),  and the continuance  of such default  or breach for  a period of 30
    days or more after written  notice to the Company by  the Trustee or to  the
    Company  and  the  Trustee by  the  holders  of at  least  25%  in aggregate
    principal amount at maturity  of the outstanding Notes  (in each case,  when
    such notice is deemed received in accordance with the Indenture); or
 
       (v) default under any mortgage, indenture or instrument under which there
           may  be issued  or by  which there  may be  secured or  evidenced any
    Indebtedness for money  borrowed by  the Company  or any  of its  Restricted
    Subsidiaries (or the payment of which is Guaranteed by the Company or any of
    its  Restricted  Subsidiaries) whether  such  Indebtedness or  Guarantee now
    exists, or is created after the Issue Date, which default (A) is caused by a
    failure to  pay  principal  of or  premium,  if  any, or  interest  on  such
    Indebtedness  prior to the  expiration of the grace  period provided in such
    Indebtedness on  the date  of  such default  (a  "Payment Default")  or  (B)
    results  in  the  acceleration of  such  Indebtedness prior  to  its express
    maturity and, in each case, the  principal amount of any such  Indebtedness,
    together  with the  principal amount  of any  other such  Indebtedness under
    which there has been a Payment Default or the maturity of which has been  so
    accelerated, aggregates $5.0 million or more; or
 
       (vi)any  final  judgment  or order  (not  covered by  insurance)  for the
           payment of money in excess of  $5.0 million in the aggregate for  all
    such  final  judgments  or orders  against  all such  Persons  (treating any
    deductibles, self-insurance  or  retention  as  not  so  covered)  shall  be
    rendered  against the Company or any Significant Subsidiary and shall not be
    paid or discharged,  and there shall  be any period  of 60 consecutive  days
    following  entry of  the final judgment  or order that  causes the aggregate
    amount for all such  final judgments or orders  outstanding and not paid  or
    discharged  against all such  Persons to exceed $5.0  million during which a
    stay of enforcement of such final judgment or order, by reason of a  pending
    appeal or otherwise, shall not be in effect; or
 
       (vii)
           a  court having jurisdiction in the premises enters a decree or order
           for  (A)  relief  in  respect  of  the  Company  or  any  Significant
    Subsidiary   in  an  involuntary  case   under  any  applicable  bankruptcy,
    insolvency or other similar law now or hereafter in effect, (B)  appointment
    of  a receiver,  liquidator, assignee,  custodian, trustee,  sequestrator or
    similar official of the Company or any Significant Subsidiary or for all  or
    substantially  all  of  the  property  and  assets  of  the  Company  or any
    Significant Subsidiary; or (C) the winding up or liquidation of the  affairs
    of  the Company or any Significant Subsidiary and, in each case, such decree
    or order shall remain unstayed and in effect for a period of 60  consecutive
    days; or
 
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<PAGE>
       (viii)
           the  Company or any Significant  Subsidiary (A) commences a voluntary
           case under any applicable bankruptcy, insolvency or other similar law
    now or hereafter in effect, or consents to the entry of an order for  relief
    in  an involuntary case under any such  law, (B) consents to the appointment
    of or  taking possession  by a  receiver, liquidator,  assignee,  custodian,
    trustee,  sequestrator or similar official of the Company or any Significant
    Subsidiary or for all or substantially all of the property and assets of the
    Company or any Significant Subsidiary or (C) effects any general  assignment
    for the benefit of creditors; or
 
       (ix)the  holder  of  any  Indebtedness  of  the  Company  or  any  of its
           Restricted  Subsidiaries  aggregating  at   least  $5.0  million   in
    principal  amount that is secured by a Lien  on assets of the Company or any
    such Restricted Subsidiary (or any agent of such holder of such Indebtedness
    or the Trustee or  other representative then acting  under any indenture  or
    other  instrument  under  which  such  Indebtedness  is  outstanding)  shall
    commence any proceeding, or take any action (including, without  limitation,
    by  way of  set-off) to  retain in satisfaction  of such  Indebtedness or to
    collect on, seize, dispose of or apply in satisfaction of such Indebtedness,
    assets of the Company  or any of its  Restricted Subsidiaries having a  fair
    market value in excess of $5.0 million individually or in the aggregate.
 
    If  any Event of Default (other than an Event of Default specified in clause
(vii) or (viii)  above with respect  to the Company)  occurs and is  continuing,
then  the Trustee or the holders of at least 25% in principal amount at maturity
of outstanding Notes may, by written notice, and the Trustee upon the request of
the holders  of  not less  than  25% in  principal  amount at  maturity  of  the
outstanding  Notes shall,  declare the  Default Amount  of, and  any accrued and
unpaid interest on, all outstanding Notes to be immediately due and payable  and
upon any such declaration such amounts shall become immediately due and payable.
If an Event of Default specified in clause (vii) or (viii) above with respect to
the  Company  occurs and  is continuing,  then  the Default  Amount of,  and any
accrued and unpaid interest  on, all outstanding Notes  shall IPSO FACTO  become
and  be immediately due and payable without  any declaration or other act on the
part of the Trustee or any holder.
 
    After a declaration of acceleration, the holders of a majority in  aggregate
principal amount at maturity of outstanding Notes may, by notice to the Trustee,
rescind  such declaration  of acceleration  if all  existing Events  of Default,
other than  nonpayment of  the Default  Amount of,  and any  accrued and  unpaid
interest  on,  the  Notes  that  has  become due  solely  as  a  result  of such
acceleration, have been cured  or waived and if  the rescission of  acceleration
would  not conflict with  any judgment or  decree. The holders  of a majority in
principal amount at  maturity of the  outstanding Notes also  have the right  to
waive  past defaults under the Indenture, except a default in the payment of the
Default Amount of, or any interest on, any outstanding Note, or in respect of  a
covenant  or a provision that cannot be  modified or amended without the consent
of all holders of Notes.
 
    No holder of any of the Notes has any right to institute any proceeding with
respect to the  Indenture or  any remedy thereunder,  unless the  holders of  at
least  25% in principal  amount at maturity  of the outstanding  Notes have made
written request, and offered reasonable security or indemnity, to the Trustee to
institute such proceeding as Trustee, the  Trustee has failed to institute  such
proceeding  within 60 days after receipt of  such notice and the Trustee has not
within such 60-day  period received  directions inconsistent  with such  written
request  by  holders  of a  majority  in  principal amount  at  maturity  of the
outstanding Notes. Such limitations do not apply, however, to a suit  instituted
by  a holder of a Note for the  enforcement of the payment of the Default Amount
of, or any accrued and unpaid interest on, such Note on or after the  respective
due dates expressed in such Note.
 
    During  the existence  of an  Event of Default,  the Trustee  is required to
exercise such rights and  powers vested in  it under the  Indenture and use  the
same  degree of care and skill in its exercise thereof as a prudent Person would
exercise under the circumstances  in the conduct of  such Person's own  affairs.
Subject  to  the provisions  of  the Indenture  relating  to the  duties  of the
Trustee, if an Event of  Default shall occur and  be continuing, the Trustee  is
not  under any  obligation to  exercise any  of its  rights or  powers under the
Indenture at the request or direction of any of the holders unless such  holders
shall
 
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<PAGE>
have  offered  to  such Trustee  reasonable  security or  indemnity.  Subject to
certain provisions  concerning the  rights  of the  Trustee,  the holders  of  a
majority in principal amount at maturity of the outstanding Notes have the right
to direct the time, method and place of conducting any proceeding for any remedy
available  to the  Trustee or  exercising any  trust or  power conferred  on the
Trustee.
 
    The Indenture  provides that  the Trustee  will, within  45 days  after  the
occurrence  of any  Default, give  to the  holders of  the Notes  notice of such
Default known  to it,  unless such  Default  shall have  been cured  or  waived;
PROVIDED  that the Trustee shall  be protected in withholding  such notice if it
determines in good faith that the withholding of such notice is in the  interest
of such holders.
 
    The Company is required to furnish to the Trustee annually a statement as to
its compliance with all conditions and covenants under the Indenture.
 
DEFEASANCE
 
    The Company may at any time terminate all of its obligations with respect to
the  Notes  ("defeasance"),  except  for  certain  obligations,  including those
regarding any trust established for a defeasance and obligations to register the
transfer or exchange  of the  Notes, to  replace mutilated,  destroyed, lost  or
stolen Notes as required by the Indenture and to maintain agencies in respect of
the  Notes. The Company may at any  time terminate its obligations under certain
covenants set forth in the Indenture, some of which are described under "Certain
Covenants" above, and  any omission to  comply with such  obligations shall  not
constitute  a  Default with  respect to  the  Notes ("covenant  defeasance"). To
exercise either defeasance or covenant defeasance, the Company must  irrevocably
deposit  in trust, for the benefit of the holders of the Notes, with the Trustee
money (in United States dollars) or U.S. government obligations (denominated  in
United  States dollars), or  a combination thereof,  in such amounts  as will be
sufficient to  pay  the principal  of,  premium, if  any,  and interest  on  the
outstanding  Notes  to  redemption or  maturity  and comply  with  certain other
conditions, including the delivery of a legal opinion as to certain tax matters.
 
SATISFACTION AND DISCHARGE
 
    The Indenture will  be discharged  and will cease  to be  of further  effect
(except as to surviving rights or registration of transfer or exchange of Notes)
as  to  all  outstanding  Notes  when  either  (a)  all  such  Notes theretofore
authenticated and delivered (except  lost, stolen or  destroyed Notes that  have
been  replaced or paid  and Notes for  whose payment money  has theretofore been
deposited in trust or segregated and held in trust by the Company and thereafter
repaid to the Company or discharged from such trust) have been delivered to  the
Trustee  for cancellation; or (b)(i) all such Notes not theretofore delivered to
the Trustee for cancellation have become due and payable by their terms or shall
have been called  for redemption and  the Company has  irrevocably deposited  or
caused  to be deposited with the Trustee as trust funds in trust for the purpose
an amount of money  sufficient to pay and  discharge the entire Indebtedness  on
the  Notes  not  theretofore  delivered  to  the  Trustee  for  cancellation  or
redemption, for the principal amount, premium,  if any, and accrued interest  to
the date of such deposit; (ii) the Company has paid all other sums payable by it
under   the  Indenture;  and   (iii)  the  Company   has  delivered  irrevocable
instructions to the Trustee to apply  the deposited money toward the payment  of
the  Notes  at maturity  or  on the  redemption  date, as  the  case amy  be. In
addition, the Company must  deliver an Officers' Certificate  and an Opinion  of
Counsel stating that all conditions precedent to satisfaction and discharge have
been complied with.
 
AMENDMENTS AND WAIVERS
 
    From  time to time the Company, when authorized by resolutions of its Board,
and the Trustee, without  the consent of  the holders of  the Notes, may  amend,
waive  or supplement the Indenture or  the Notes for certain specified purposes,
including, among other things,  curing ambiguities, defects or  inconsistencies,
maintaining  the qualification of the Indenture under the Trust Indenture Act or
making any change that does not adversely affect the rights of any holder. Other
amendments and modifications of the Indenture and  the Notes may be made by  the
Company and the Trustee with the
 
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consent  of the holders of  not less than a  majority of the aggregate principal
amount at  maturity of  the outstanding  Notes (including  consents obtained  in
connection  with a tender offer  or exchange offer for  Notes); PROVIDED that no
such modification or amendment  may, without the consent  of the holder of  each
outstanding  Note affected thereby, (i) reduce  the principal amount at maturity
of, extend the  fixed maturity of,  or alter the  redemption provisions of,  the
Notes  or amend or modify  the calculation of the  Accreted Value or the Default
Amount so as to reduce the amount  of the Accreted Value or the Default  Amount,
(ii)  change  the currency  in which  any Notes  or any  premium or  the accrued
interest thereon is payable, (iii) reduce the percentage in principal amount  at
maturity  outstanding of Notes  who must consent to  an amendment, supplement or
waiver or consent  to take any  action under  the Indenture or  the Notes,  (iv)
impair the right to institute suit for the enforcement of any payment on or with
respect  to the Notes, (v) waive a default in payment with respect to the Notes,
(vi) reduce the rate or extend the time for payment of interest on the Notes  or
(vii)  adversely affect  the ranking  of the  Notes in  a manner  adverse to the
holder of the Notes.
 
    In addition, without the consent of at least 66 2/3% in principal amount  at
maturity   of  the  Notes  then  outstanding  (including  consents  obtained  in
connection with a tender offer or exchange offer for Notes), no amendment to the
Indenture may make any change in, and no waiver may be made with respect to  any
Default in the performance of, the provisions described above under the captions
"Change in Control" and "Disposition of Proceeds of Asset Sales."
 
CONCERNING THE TRUSTEE
 
    The  Indenture provides that,  except during the continuance  of an Event of
Default, the Trustee will perform only such duties as are specifically set forth
in the Indenture. If  an Event of  Default has occurred  and is continuing,  the
Trustee  will exercise such rights  and powers vested in  it under the Indenture
and use the same degree  of care and skill in  its exercise as a prudent  Person
would  exercise  under the  circumstances in  the conduct  of such  Person's own
affairs.
 
    The Indenture and the provisions of the Trust Indenture Act incorporated  by
reference  therein  contain certain  limitations on  the  rights of  the Trustee
thereunder, should it  become a creditor  of the Company,  to obtain payment  of
claims  in certain cases,  or to realize  on certain property  received by it in
respect of any such claims, as  security or otherwise. The Trustee is  permitted
to  engage in  other transactions;  PROVIDED, HOWEVER,  that if  it acquires any
conflicting interest it must eliminate such conflict or resign.
 
GOVERNING LAW
 
    The Indenture and the Notes will be governed by, and construed in accordance
with, the laws of the State of New York without giving effect to the  principals
of conflicts of law thereof.
 
CERTAIN DEFINITIONS
 
    Set  forth below are certain defined  terms used in the Indenture. Reference
is made to the Indenture for any  other capitalized terms used herein for  which
no definition is provided.
 
    "ACCRETED VALUE" as of any Specified Date, means with respect to each $1,000
principal amount at maturity of Notes:
 
                                       83
<PAGE>
       (i) if  the Specified Date occurs on one  of the following dates (each, a
           "Semi-Annual Accrual Date"), the amount set forth below opposite such
    date:
 
<TABLE>
<CAPTION>
                   SEMI-ANNUAL ACCRUAL DATE                      ACCRETED VALUE
- ---------------------------------------------------------------  --------------
<S>                                                              <C>
                , 1996.........................................   $
                , 1997.........................................
                , 1997.........................................
                , 1998.........................................
                , 1998.........................................
                , 1999.........................................
                , 1999.........................................
                , 2000.........................................
                , 2000.........................................
                , 2001.........................................
                , 2001.........................................   $   1,000.00
</TABLE>
 
       (ii)if the Specified  Date occurs  before the  first Semi-Annual  Accrual
           Date, the sum of (A) the original issue price and (B) an amount equal
    to  the product of (1) the Accreted  Value for the first Semi-Annual Accrual
    Date less the original issue price (2) a fraction, the numerator of which is
    the number of days from the issue  date of the Notes to the Specified  Date,
    using  a 360-day year of twelve 30-day  months, and the denominator of which
    is the number of days elapsed from the issue date of the Notes to the  first
    Semi- Annual Accrual Date, using a 360-day year of twelve 30-day months;
 
       (iii)
           if  the Specified Date occurs  between two Semi-Annual Accrual Dates,
           the sum of (A)  the Accreted Value for  the Semi-Annual Accrual  Date
    immediately  preceding the  Specified Date  and (B)  an amount  equal to the
    product of (1) the Accreted Value for the immediately following  Semi-Annual
    Accrual   Date  less  the  Accreted  Value  for  the  immediately  preceding
    Semi-Annual Accrual  Date (2)  a fraction,  the numerator  of which  is  the
    number  of days from  the immediately preceding  Semi-Annual Accrual Date to
    the Specified Date,  using 360-day  year of  twelve 30-day  months, and  the
    denominator of which is 180; or
 
       (iv)if  the Specified  Date occurs  after the  last Semi-  Annual Accrual
           Date, $1,000.
 
    "ACQUIRED  DEBT"  means,   with  respect  to   any  specified  Person,   (i)
Indebtedness  of any  other Person  existing at  the time  such other  Person is
merged with or into or became a Subsidiary of such specified Person,  including,
without   limitation,   Indebtedness  incurred   in   connection  with,   or  in
contemplation of,  such  other  Person  merging  with  or  into  or  becoming  a
Subsidiary  of such  specified Person, and  (ii) Indebtedness secured  by a Lien
encumbering any asset acquired by such specified Person.
 
    "ADJUSTED CONSOLIDATED NET INCOME" means, for any period, the aggregate  net
income  (or loss) of the Company and its Restricted Subsidiaries for such period
determined in conformity with GAAP; PROVIDED  that the following items shall  be
excluded  in computing  Adjusted Consolidated Net  Income (without duplication):
(i) the  net income  of any  Person (other  than net  income attributable  to  a
Restricted Subsidiary) in which any Person (other than the Company or any of its
Restricted  Subsidiaries)  has  a  joint  interest and  the  net  income  of any
Unrestricted Subsidiary, except  to the  extent of  the amount  of dividends  or
other  distributions  actually paid  to  the Company  or  any of  its Restricted
Subsidiaries  by   such  other   Person  (including,   without  limitation,   an
Unrestricted  Subsidiary) during  such period; (ii)  solely for  the purposes of
calculating the  amount of  Restricted Payments  that may  be made  pursuant  to
clause  (C) of  the first paragraph  of the "Limitation  on Restricted Payments"
covenant described above  (and in  such case,  except to  the extent  includable
pursuant  to clause (i) above),  the net income (or  loss) of any Person accrued
prior to  the date  it becomes  a Restricted  Subsidiary or  is merged  into  or
consolidated  with the Company or  any of its Restricted  Subsidiaries or all or
substantially all of the property and assets of such Person are acquired by  the
Company  or any  of its  Restricted Subsidiaries;  (iii) the  net income  of any
Restricted Subsidiary to the extent that the declaration or payment of dividends
or similar distributions by such Restricted Subsidiary of such net income is not
at the time permitted by the operation of
 
                                       84
<PAGE>
the terms of its charter or any agreement, instrument, judgment, decree,  order,
statute,   rule  or  governmental  regulation   applicable  to  such  Restricted
Subsidiary; (iv) any  gains or losses  (on an after-tax  basis) attributable  to
Asset  Sales; (v)  except for purposes  of calculating the  amount of Restricted
Payments that may be made pursuant to  clause (C) of the first paragraph of  the
"Limitation  on Restricted Payments"  covenant described above,  any amount paid
as, or accrued  for, cash dividends  on Preferred  Stock of the  Company or  any
Restricted  Subsidiary owned by  Persons other than  the Company and  any of its
Restricted Subsidiaries; and  (vi) all extraordinary  or nonrecurring gains  and
losses.
 
    "ADJUSTED CONSOLIDATED NET TANGIBLE ASSETS" means the total amount of assets
of  the Company and  its Restricted Subsidiaries  (less applicable depreciation,
amortization and other valuation reserves), except to the extent resulting  from
write-ups  of capital assets (excluding  write-ups in connection with accounting
for acquisitions in  conformity with  GAAP), after deducting  therefrom (i)  all
current  liabilities of the  Company and its  Restricted Subsidiaries (excluding
intercompany items) and  (ii) all  goodwill, trade  names, trademarks,  patents,
unamortized  debt discount  and expense and  other like  intangibles (other than
licenses issued  by the  FCC),  all as  set forth  on  the quarterly  or  annual
consolidated  balance  sheet of  the  Company and  its  Restricted Subsidiaries,
prepared in conformity  with GAAP and  most recently filed  with the  Commission
pursuant  to the  "Reports" covenant;  PROVIDED that  the value  of any licenses
issued by the FCC  shall, in the  event of an auction  for similar licenses,  be
equal  to the fair market value ascribed thereto  in good faith by the Board and
evidenced by a resolution of the Board. As used in the Indenture, references  to
financial  statements of  the Company and  its Restricted  Subsidiaries shall be
adjusted to exclude Unrestricted Subsidiaries if the context requires.
 
    "AFFILIATE" of  any specified  Person  means any  other Person  directly  or
indirectly  controlling  or controlled  by or  under  direct or  indirect common
control with such specified Person.  For purposes of this definition,  "control"
(including,  with correlative meanings, the terms "controlling," "controlled by"
and "under common control with"), as used with respect to any Person, shall mean
the possession, directly  or indirectly,  of the power  to direct  or cause  the
direction  of the  management or  policies of  such Person,  whether through the
ownership of  voting  securities,  by  agreement  or  otherwise;  PROVIDED  that
beneficial  ownership of 10% or more of  the voting securities of a Person shall
be deemed to  be control. For  purposes of the  Indenture, the term  "Affiliate"
shall  at all times include Laurence S. Zimmerman, Landover Holdings Corporation
and their respective Affiliates.
 
    "ART WEST"  means ART  West Joint  Venture, a  Delaware partnership  equally
owned by the Company and Extended Communications, Inc.
 
    "ASSET  ACQUISITION" means (i)  an Investment by  the Company or  any of its
Restricted Subsidiaries in any other Person pursuant to which such Person  shall
become  a  Restricted Subsidiary  of  the Company  or  shall be  merged  into or
consolidated with the Company or any  of its Restricted Subsidiaries or (ii)  an
acquisition by the Company or any of its Restricted Subsidiaries of the property
and  assets  of any  Person  other than  the Company  or  any of  its Restricted
Subsidiaries that constitute substantially all of a division or line of business
of such Person.
 
    "ASSET SALE" means any sale, transfer or other disposition (including by way
of merger, consolidation or sale-leaseback transaction) in one transaction or  a
series  of  related  transactions  by  the  Company  or  any  of  its Restricted
Subsidiaries to  any Person  other than  the Company  or any  of its  Restricted
Subsidiaries  of  (i)  all  or  any  of  the  Capital  Stock  of  any Restricted
Subsidiary, (ii)  all or  substantially all  of the  property and  assets of  an
operating  unit or business of the Company or any of its Restricted Subsidiaries
or (iii) any other property  or assets of the Company  or any of its  Restricted
Subsidiaries  (including Capital Stock of any Unrestricted Subsidiaries) outside
the ordinary course of  business of the Company  or such Restricted  Subsidiary;
PROVIDED  that the following shall not be  included within the meaning of "Asset
Sale": (A)  sales or  other  dispositions of  inventory, receivables  and  other
current  assets; (B)  sales or other  dispositions of equipment  that has become
worn out, obsolete or damaged or otherwise unsuitable for use in connection with
the business of the Company or its Restricted Subsidiaries; (C) Permitted  Asset
Swaps;  (D) sales, transfers or  other dispositions otherwise constituting Asset
Sales in  an  aggregate  amount  not to  exceed  $500,000  during  the  relevant
twelve-month period referred
 
                                       85
<PAGE>
to  in the "Disposition of Proceeds of Asset Sales" covenant; (E) any Restricted
Payment permitted by the "Limitation  on Restricted Payments" covenant; (F)  any
Lien  permitted  to be  Incurred by  the "Limitation  on Liens  Securing Certain
Indebtedness" covenant; (G) any transaction  that is governed by the  provisions
of the "Consolidation, Merger, Sale of Assets, Etc." covenant; and (H) any sale,
transfer   or  other  disposition  of  the  Capital  Stock  of  an  Unrestricted
Subsidiary.
 
    "AVERAGE LIFE" means, at any date of determination with respect to any  debt
security,  the quotient obtained by dividing (i)  the sum of the products of (A)
the number  of years  from  such date  of determination  to  the dates  of  each
successive  scheduled principal payment of such debt security and (B) the amount
such principal payment by (ii) the sum of all such principal payments.
 
    "BOARD" means the Board of the Company.
 
    "CAPITAL STOCK" means  (i) in the  case of a  corporation, corporate  stock,
(ii)  in the  case of  an association  or business  entity, any  and all shares,
interests, participations, rights or  other equivalents (however designated)  of
corporate  stock,  (iii) in  the case  of  a partnership,  partnership interests
(whether general or limited) and (iv)  any other interest or participation  that
confers  on a Person the right to receive  a share of the profits and losses of,
or distributions of assets of, the issuing Person.
 
    "CAPITALIZED LEASE"  means, as  applied  to any  Person,  any lease  of  any
property (whether real, personal or mixed) of which the discounted present value
of  the rental obligations of such Person as lessee, in conformity with GAAP, is
required to be capitalized on the balance sheet of such Person; and "Capitalized
Lease Obligations" means the discounted present value of the rental  obligations
under such lease.
 
    "CHANGE IN 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 Issue Date
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 the Issue Date 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  stockholders of  the
Company  immediately prior to such  transaction hold less than  50% of the total
voting power of all  securities generally entitled to  vote for the election  of
directors,  managers  or  trustees  of  the  Person  surviving  such  merger  or
consolidation.
 
    "COMMON STOCK" means  the common stock,  par value $.001  per share, of  the
Company.
 
    "CONSOLIDATED EBITDA" means, for any period, the sum of the amounts for such
period  of  (i) Adjusted  Consolidated  Net Income,  (ii)  Consolidated Interest
Expense, to  the  extent  such  amount  was  deducted  in  calculating  Adjusted
Consolidated  Net  Income, (iii)  income taxes,  to the  extent such  amount was
deducted in  calculating Adjusted  Consolidated Net  Income (other  than  income
taxes   (either  positive   or  negative)  attributable   to  extraordinary  and
non-recurring gains or losses or sales of assets), (iv) depreciation expense, to
the extent such  amount was  deducted in calculating  Adjusted Consolidated  Net
Income,  (v) amortization  expense, to  the extent  such amount  was deducted in
calculating Adjusted  Consolidated Net  Income, (vi)  all other  non-cash  items
reducing  Adjusted Consolidated Net  Income (other than  items that will require
cash payments and for which an accrual or reserve is, or is required by GAAP  to
be,  made), less all non-cash items  increasing Adjusted Consolidated Net Income
and (vii) all cash dividend payments (and non-cash dividend payments in the case
of a Person that is a Restricted Subsidiary) on any series of preferred stock of
such Person, all as determined on a  consolidated basis for the Company and  its
Restricted   Subsidiaries  in  conformity  with  GAAP;  PROVIDED  that,  if  any
Restricted Subsidiary is not a Wholly Owned Restricted Subsidiary,  Consolidated
EBITDA
 
                                       86
<PAGE>
shall  be reduced (to the extent not  otherwise reduced in accordance with GAAP)
by an amount equal  to (A) the  amount of the  Adjusted Consolidated Net  Income
attributable to such Restricted Subsidiary multiplied by (B) the quotient of (1)
the  number of shares of outstanding  Common Stock of such Restricted Subsidiary
not owned on the last day of such period by the Company or any of its Restricted
Subsidiaries divided by  (2) the total  number of shares  of outstanding  Common
Stock   of  such  Restricted  Subsidiary  on   the  last  day  of  such  period.
Notwithstanding the foregoing, the  provision for taxes based  on the income  or
profits of, and the depreciation and amortization and other non-cash charges of,
a  Restricted Subsidiary of a Person shall be added to Adjusted Consolidated Net
Income to  compute Consolidated  EBITDA only  to  the extent  (and in  the  same
proportion)  that the net  income of such Restricted  Subsidiary was included in
calculating the Adjusted Consolidated  Net Income of such  Person and only if  a
corresponding  amount  would be  permitted at  the date  of determination  to be
dividended to the Company by  such Restricted Subsidiary without prior  approval
(that  has not  been obtained),  pursuant to  the terms  of its  charter and all
agreements,  instruments,  judgments,  decrees,  orders,  statutes,  rules   and
governmental  regulations  applicable  to  that  Restricted  Subsidiary  or  its
stockholders.
 
    "CONSOLIDATED INTEREST EXPENSE" means, for any period, the aggregate  amount
of interest in respect of Indebtedness (including amortization of original issue
discount  on any Indebtedness  and the interest portion  of any deferred payment
obligation, calculated  in  accordance with  the  effective interest  method  of
accounting;  all commissions,  discounts and  other fees  and charges  owed with
respect to letters of credit and bankers' acceptance financing and net  payments
(if any) pursuant to Hedging Obligations; and Indebtedness that is Guaranteed or
secured  by the Company or  any of its Restricted  Subsidiaries) and all but the
principal component of rentals in respect of Capitalized Lease Obligations paid,
accrued or  scheduled to  be  paid or  to  be accrued  by  the Company  and  its
Restricted  Subsidiaries during such period;  EXCLUDING, HOWEVER, (i) any amount
of such  interest  of  any Restricted  Subsidiary  if  the net  income  of  such
Restricted  Subsidiary is excluded from the calculation of Adjusted Consolidated
Net Income pursuant to clause (iii) of  the definition thereof (but only in  the
same proportion as the net income of such Restricted Subsidiary is excluded from
the calculation of Adjusted Consolidated Note Income pursuant to clause (iii) of
the  definition  thereof) and  (ii)  any premiums,  fees  and expenses  (and any
amortization thereof) payable in connection with the offering of the Notes,  all
as  determined on a consolidated basis (without taking into account Unrestricted
Subsidiaries) in conformity with GAAP.
 
    "DEFAULT" means any event that is, or with the passage of time or the giving
of notice or both would be, an Event of Default.
 
    "DEFAULT AMOUNT" means (i) as of any date prior to              , 2001,  the
Accreted  Value of the  Notes (plus any  applicable premium thereon)  as of such
date and (ii) as  of any date  on or after                 ,  2001, 100% of  the
principal amount at maturity of the Notes (plus any applicable premium thereon).
 
    "DIRECTED  INVESTMENT" means any Investment in a Telecommunications Business
that is made  by investing the  net proceeds  of the issuance  of Capital  Stock
(other  than Redeemable  Stock) by  the Company  (or options,  warrants or other
rights to purchase such Capital Stock) after the Issue Date; PROVIDED that  such
Investment  shall be  made with such  net proceeds  in the form  received by the
Company and shall be limited to an amount equal to (A) 50% of such net  proceeds
to  the extent that such net proceeds consist  of cash, and (B) 100% of such net
proceeds to the  extent such  net proceeds  consist of  Capital Stock;  PROVIDED
FURTHER  that such Investment is made within 90 days of such issuance of Capital
Stock.
 
    "EQUITY OFFERING"  means an  underwritten public  offering or  flotation  of
Common  Stock of the Company which has  been registered under the Securities Act
and/or admitted to listing on a national securities exchange.
 
    "FAIR MARKET VALUE" means the  price that would be  paid in an arm's  length
transaction  between an informed and willing  seller under no compulsion to sell
and an informed and willing buyer under  no compulsion to buy, as determined  in
good  faith by the Board (whose determination shall be conclusive) and evidenced
by a resolution of the Board.
 
                                       87
<PAGE>
    "FCC" means  the United  States Federal  Communications Commission  and  any
state  or local  telecommunications authority, department,  commission or agency
(and any successors thereto).
 
    "GAAP" means generally accepted accounting  principles in the United  States
of  America as in effect from time to time, including, without limitation, those
set forth in the opinions and pronouncements of the Accounting Principles  Board
of  the American  Institute of Certified  Public Accountants  and statements and
pronouncements of  the Financial  Accounting Standards  Board or  in such  other
statements  by such  other entity  as approved by  a significant  segment of the
accounting profession. All  ratios and computations  contained in the  Indenture
shall  be computed in conformity with GAAP applied on a consistent basis, except
that calculations made for purposes of determining compliance with the terms  of
the  covenants and with other provisions of  the Indenture shall be made without
giving effect to  (i) the amortization  of any expenses  incurred in  connection
with  the  offering of  the Notes  and  (ii) except  as otherwise  provided, the
amortization of any amounts required or permitted by Accounting Principles Board
Opinion Nos. 16 and 17.
 
    "GUARANTEE" means any  obligation, contingent  or otherwise,  of any  Person
directly  or indirectly guaranteeing any Indebtedness or other obligation of any
other 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, or by agreements 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 purposes of assuring
in any other manner the obligee of such Indebtedness or other obligation of  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.
 
    "HEDGING OBLIGATIONS" means, with respect to any Person, the obligations  of
such  Person  under  (i)  interest  rate  swap  agreements,  interest  rate  cap
agreements and  interest rate  collar agreements  and (ii)  other agreements  or
arrangements  designed to protect  such Person against  fluctuations in interest
rates.
 
    "INCUR" means, with respect  to any Indebtedness,  to incur, create,  issue,
assume,  Guarantee or otherwise become liable for  or with respect to, or become
responsible for, the payment of,  contingently or otherwise, such  Indebtedness,
including,  with  respect to  the Company  and  its Restricted  Subsidiaries, an
"incurrence" of  Indebtedness  by  reason  of a  Person  becoming  a  Restricted
Subsidiary of the Company; PROVIDED that neither the accrual of interest nor the
accretion  of  original  issue discount  shall  be considered  an  Incurrence of
Indebtedness.
 
    "INDEBTEDNESS"  means,  with  respect   to  any  Person   at  any  date   of
determination  (without duplication),  (i) all  indebtedness of  such person for
borrowed money,  (ii)  all  obligations  of  such  Person  evidenced  by  bonds,
debentures,   notes  or   other  similar  instruments   (whether  negotiable  or
non-negotiable), (iii) all obligations of such  Person in respect of letters  of
credit  or other  similar instruments (including  reimbursement obligations with
respect thereto), (iv) all  obligations of such Person  to pay the deferred  and
unpaid  purchase price of property or services, which purchase price is due more
than six months after  the date of  placing such property  in service or  taking
delivery  and title  thereto or  the completion  of such  services, except trade
payables  and  escrows,   holdbacks  and  comparable   arrangements  to   secure
indemnification obligations under acquisition agreements, (v) all obligations of
such  Person as lessee under Capitalized  Leases, (vi) all indebtedness of other
Persons secured by  a Lien  on any  asset of such  Person, whether  or not  such
indebtedness  is  assumed  by such  Person;  PROVIDED  that the  amount  of such
indebtedness shall be the lesser of (A)  the fair market value of such asset  at
such  date of determination and  (B) the amount of  such indebtedness, (vii) the
balance  deferred  and  unpaid  of  the  purchase  price  of  any  property   or
representing  any Hedging Obligations, except  any such balance that constitutes
an accrued  expense or  trade  payable, and  (viii)  all indebtedness  of  other
Persons  Guaranteed by such Person to the extent such indebtedness is Guaranteed
by   such   Person.   The   amount   of   Indebtedness   of   any   Person    at
 
                                       88
<PAGE>
any  date shall  be the  outstanding balance at  such date  of all unconditional
obligations as described above and, with respect to contingent obligations  that
are  included in any of clauses (i)  through (viii) above, the maximum liability
upon the occurrence of the contingency  giving rise to the obligation,  PROVIDED
(A)  that the  amount outstanding  at any time  of any  Indebtedness issued with
original issue discount  is the face  amount of such  Indebtedness and (B)  that
Indebtedness  shall not include any liability for federal, state, local or other
taxes.
 
    "INDEBTEDNESS TO EBITDA RATIO" means, as  at any date of determination,  the
ratio  of  (i) the  aggregate  amount of  Indebtedness  of the  Company  and its
Restricted Subsidiaries on a consolidated basis ("Consolidated Indebtedness") as
at the date of determination (the  "Transaction Date") to (ii) the  Consolidated
EBITDA  of the Company  for the then  most recent four  full fiscal quarters for
which reports have been filed pursuant to the "Reports" covenant described above
(such four full  fiscal quarter  period being referred  to herein  as the  "Four
Quarter  Period"); PROVIDED  that (x)  pro forma  effect shall  be given  to any
Indebtedness Incurred from the beginning of the Four Quarter Period through  the
Transaction  Date (including any Indebtedness Incurred on the Transaction Date),
to the extent  outstanding on  the Transaction Date,  (y) if  during the  period
commencing  on the first day of such Four Quarter Period through the Transaction
Date (the "Reference Period"), the Company or any of the Restricted Subsidiaries
shall have engaged in any Asset Sale, Consolidated EBITDA for such period  shall
be  reduced by an amount  equal to the EBITDA (if  positive), or increased by an
amount equal to the  EBITDA (if negative), directly  attributable to the  assets
which  are the subject of such Asset Sale any related retirement of Indebtedness
as if such Asset Sale and related retirement of Indebtedness had occurred on the
first day of such Reference  Period or (z) if  during such Reference Period  the
Company  or  any  of  the  Restricted Subsidiaries  shall  have  made  any Asset
Acquisition, Consolidated EBITDA  of the Company  shall be calculated  on a  pro
forma  basis as if such Asset Acquisition  and any Incurrence of Indebtedness to
finance such  Asset  Acquisition  had taken  place  on  the first  day  of  such
Reference Period.
 
    "INVESTMENT"  in any  Person means any  direct or indirect  advance, loan or
extension of  credit (including,  without  limitation, by  way of  Guarantee  or
similar  arrangement; but excluding advances to customers in the ordinary course
of business that are, in conformity  with GAAP, recorded as accounts  receivable
on  the balance sheet of the Company  or its Restricted Subsidiaries) or capital
contribution to (by means of any transfer of cash or other property to others or
any payment for property or services for  the account or use of others), or  any
purchase  or acquisition  of Capital  Stock, bonds,  notes, debentures  or other
similar instruments issued by, such Person and shall include (i) the designation
of a  Restricted Subsidiary  as an  Unrestricted Subsidiary  and (ii)  the  fair
market  value  of the  Capital  Stock held  by  the Company  and  the Restricted
Subsidiaries of any  Person that  has ceased to  be a  Restricted Subsidiary  by
reason  of any transaction permitted  by clause (iii) of  the "Limitation on the
Issuance and Sale  of Capital  Stock of Restricted  Subsidiaries" covenant.  For
purposes  of the definition of "Unrestricted  Subsidiary" and the "Limitation on
Restricted Payments" covenant,  (i) "Investment" shall  include the fair  market
value  of the assets  (net of liabilities)  of any Restricted  Subsidiary of the
Company  at  the  time  that   such  Restricted  Subsidiary  is  designated   an
Unrestricted  Subsidiary and shall  exclude the fair market  value of the assets
(net of  liabilities) of  any  Unrestricted Subsidiary  at  the time  that  such
Unrestricted Subsidiary is designated a Restricted Subsidiary of the Company and
(ii)  any property  transferred to or  from an Unrestricted  Subsidiary shall be
valued at its fair market  value at the time of  such transfer, in each case  as
determined by the Board in good faith.
 
    "ISSUE DATE" means the date of original issuance of the Notes.
 
    "LIEN" means, with respect to any asset, any mortgage, lien, pledge, charge,
security  interest or encumbrance of any kind  in respect of such asset, whether
or not filed, recorded  or otherwise perfected  under applicable law  (including
any conditional sale or other title retention agreement, any lease in the nature
thereof,  any option or other  agreement to sell or  give a security interest in
and any filing of or agreement to give any financing statement under the Uniform
Commercial Code (or equivalent statutes) of any jurisdiction).
 
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<PAGE>
    "NET CASH PROCEEDS" means (a) with  respect to any Asset Sale, the  proceeds
of  such Asset Sale in the form  of cash or cash equivalents, including payments
in respect of deferred payment obligations  (to the extent corresponding to  the
principal,  but not  interest, component thereof)  when received in  the form of
cash or cash equivalents (except to the extent such obligations are financed  or
sold  with recourse to the Company or  any Restricted Subsidiary of the Company)
and proceeds from the  conversion of other property  received when converted  to
cash  or cash equivalents, net  of (i) brokerage commissions  and other fees and
expenses (including fees and expenses of counsel and investment bankers) related
to such Asset Sale,  (ii) provisions for  all taxes (whether  or not such  taxes
will  actually be paid  or are payable) as  a result of  such Asset Sale without
regard to  the  consolidated  results  of operations  of  the  Company  and  its
Restricted  Subsidiaries,  taken  as  a  whole,  (iii)  payments  made  to repay
Indebtedness or any other obligation outstanding at the time of such Asset  Sale
that  either (A) is secured by  a Lien on the property  or assets sold or (B) is
required to be paid as a result of such sale and (iv) appropriate amounts to  be
provided by the Company or any Restricted Subsidiary of the Company as a reserve
against  any  liabilities associated  with such  Asset Sale,  including, without
limitation, pension and other  post-employment benefit liabilities,  liabilities
related  to  environmental  matters and  liabilities  under  any indemnification
obligations associated with  such Asset  Sale, all as  determined in  conformity
with  GAAP and (b)  with respect to any  issuance or sale  of Capital Stock, the
proceeds of such  issuance or  sale in  the form  of cash  or cash  equivalents,
including  payments in  respect of deferred  payment obligations  (to the extent
corresponding to  the  principal,  but not  interest,  component  thereof)  when
received  in the  form of cash  or cash  equivalents (except to  the extent such
obligations are financed or sold with recourse to the Company or any  Restricted
Subsidiary  of the Company)  and proceeds from the  conversion of other property
received when converted  to cash or  cash equivalents, net  of attorney's  fees,
underwriters' or placement agents' fees, discounts or commissions and brokerage,
consultant  and other fees incurred in connection with such issuance or sale and
net of taxes paid or payable as a result thereof.
 
    "NON-RECOURSE DEBT" means Indebtedness (a)  as to which neither the  Company
nor  any of its Restricted Subsidiaries (i)  provides credit support of any kind
(including any  undertaking,  agreement  or  instrument  that  would  constitute
Indebtedness)  or  (ii) is  directly  or indirectly  liable  (as a  guarantor or
otherwise); and (b) no default with respect to which (including any rights  that
the  holders thereof may have to take enforcement action against an Unrestricted
Subsidiary) would permit (upon notice, lapse of time or both) any holder of  any
other  Indebtedness  (other  than  the  Notes) of  the  Company  or  any  of its
Restricted Subsidiaries to declare a default on such other Indebtedness or cause
the payment thereof to be accelerated  or payable prior to its stated  maturity;
and  (c) as  to which the  lender of any  indebtedness for borrowed  money in an
aggregate amount in  excess of $5.0  million has been  notified in writing  that
such  lender will not have any recourse to the stock or assets of the Company or
any of its Restricted Subsidiaries.
 
    "OFFER TO PURCHASE" means an offer to purchase Notes by the Company from the
holders that is  required by  the "Disposition of  Proceeds of  Asset Sales"  or
"Change in Control" covenants of the Indenture and which is commenced by mailing
a  notice to the Trustee  and each holder stating:  (i) the covenant pursuant to
which the  offer is  being made  and that  all Notes  validly tendered  will  be
accepted  for payment on a pro rata basis;  (ii) the purchase price and the date
of purchase (which shall  be a business  day no earlier than  30 days nor  later
than  60 days from the  date such notice is  mailed) (the "Payment Date"); (iii)
that any Note  not tendered  will continue to  accrue interest  pursuant to  its
terms;  (iv) that, unless  the Company defaults  in the payment  of the purchase
price, any Note  accepted for payment  pursuant to the  Offer to Purchase  shall
cease  to  accrue interest  on  and after  the  Payment Date;  (v)  that holders
electing to have  a Note purchased  pursuant to  the Offer to  Purchase will  be
required  to surrender the Note  together with the form  entitled "Option of the
Holder to Elect Purchase" on the  reverse side thereof completed, to the  Paying
Agent  at the address specified in the notice  prior to the close of business on
the business day immediately preceding the Payment Date; (vi) that holders  will
be  entitled to withdraw their election if the Payment Agent receives, not later
than the close of business on  the third business day immediately preceding  the
Payment  Date, a  telegram, facsimile transmission  or letter  setting forth the
name of such holder, the principal amount of Notes delivered for purchase and  a
statement  that  such holder  is  withdrawing his  election  to have  such Notes
purchased; and (vii) that
 
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holders whose Notes are being  purchased only in part  will be issued new  Notes
equal in principal amount to the unpurchased portion thereof; PROVIDED that each
Note purchased and each new Note issued shall be in a principal amount of $1,000
or integral multiples thereof. On the Payment Date, the Company shall (i) accept
for  payment on a pro rata basis  Notes or portions thereof tendered pursuant to
an Offer to Purchase, (ii) deposit with the Paying Agent money sufficient to pay
the purchase  price of  all Notes  or  portions thereof  so accepted  and  (iii)
deliver,  or cause to be delivered, to the Trustee all Notes or portions thereof
so accepted  together with  an  Officers' Certificate  specifying the  Notes  or
portions  thereof so accepted for payment by the Company. The Paying Agent shall
promptly mail to the holders of Notes so accepted for payment in an amount equal
to the purchase price, and the  Trustee shall promptly authenticate and mail  to
such  holders a new Note equal in principal amount to any unpurchased portion of
the Note surrendered; PROVIDED that each Note purchased and each new Note issued
shall be in  a principal  amount of $1,000  or integral  multiples thereof.  The
Company  will publicly announce the  results of an Offer  to Purchase as soon as
practicable after the Payment  Date. The Trustee shall  act as the Paying  Agent
for  an Offer  to Purchase. The  Company will  comply with Rule  14e-1 under the
Exchange Act and  any other securities  laws and regulations  thereunder to  the
extent  such laws and regulations are applicable,  in the event that the Company
is required to repurchase Notes pursuant to an Offer to Purchase.
 
    "PERMITTED ASSET SWAP" means  any disposition by the  Company or any of  its
Restricted Subsidiaries of Telecommunications Assets or a majority of the Voting
Stock  of a Restricted Subsidiary  in exchange for comparable Telecommunications
Assets or a majority of the Voting Stock of a comparable Restricted  Subsidiary;
PROVIDED  that the Board  shall have approved such  disposition and exchange and
determined the fair market  value of the assets  subject to such transaction  as
evidenced  by  a resolution  of the  Board or  such fair  market value  has been
determined by  a written  opinion  of an  investment  banking firm  of  national
standing  or other recognized independent  expert with experience appraising the
terms and conditions of the type of transaction contemplated thereby.
 
    "PERMITTED INVESTMENTS" MEANS:
 
       (i) an Investment in a Restricted Subsidiary or a Person which will, upon
           the making of such Investment,  become a Restricted Subsidiary or  be
    merged   or  consolidated  with  or  into  or  transfer  or  convey  all  or
    substantially all its assets to, the Company or a Restricted Subsidiary;
 
       (ii)Temporary Cash Investments;
 
       (iii)
           payroll, travel  and  similar  advances to  cover  matters  that  are
           expected  at the  time of such  advances ultimately to  be treated as
    expenses in accordance with GAAP;
 
       (iv)loans or advances to employees (other than executive officers of  the
           Company)  in an aggregate principal amount not to exceed $1.0 million
    at any one time outstanding;
 
       (v) stock,  obligations  or  securities   received  in  satisfaction   of
           judgments;
 
       (vi)Investments,  to the  extent that  the consideration  provided by the
           Company or  any of  its Restricted  Subsidiaries consists  solely  of
    Capital Stock (other than Redeemable Stock) of the Company;
 
       (vii)
           notes  payable to  the Company  that are  received by  the Company as
           payment  of  the  purchase  price  for  Capital  Stock  (other   than
    Redeemable Stock) of the Company;
 
       (viii)
           an  Investment in ART West in an aggregate amount not to exceed $10.0
           million, PROVIDED that (A) the Company shall make such Investment not
    later than the Issue Date, (B) such Investment shall be represented by notes
    having substantially the same terms as the Notes, which notes shall prohibit
    ART  West  from  (1)  Incurring  any  Indebtedness,  (2)  entering  into  or
    permitting to exist any limitation on dividends or distributions by ART West
    on account of its equity interests, and
 
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<PAGE>
    (3)  using the proceeds of such Investment other than in accordance with the
    covenant described above under "Business Activities of the Company," and (C)
    the Company shall at all times own not less than 50% of ART West;
 
       (ix)Investments in an aggregate amount not to exceed $15.0 million at any
           one time outstanding;
 
        (x) Investments  in entities  (other than  ART West)  that own  licenses
    granted  by the FCC; PROVIDED that (A) such Investments are made pursuant to
    a senior promissory note, in an amount equal to such Investment, that by its
    terms is payable in full at or before any required repayment of principal on
    the Notes, (B) such promissory note is secured equally and ratably with  (or
    prior to) any other secured Indebtedness of such entity, (C) such Investment
    is  made and  used for  the purpose  of effecting,  and does  not exceed the
    amount reasonably required to effect, the minimum build-out with respect  to
    such  licenses that is required by the FCC as a prerequisite to the transfer
    of a majority equity interest  in such entity to the  Company or one of  its
    Restricted  Subsidiaries, as determined  in good faith by  the Board and (D)
    the Company, at the  time such Investment is  made, had a contractual  right
    to,  and intends  (subject in  all cases  to compliance  with applicable FCC
    rules and regulations) to, acquire such majority equity interest;
 
       (xi)existing Investments on the Issue Date;
 
       (xii)
           the acquisition of  all equity  interests of ART  West not  otherwise
           owned by the Company; and
 
       (xiii)
           Directed Investments.
 
    "PERMITTED LIENS" MEANS:
 
       (i) Liens for taxes, assessments, governmental charges or claims that are
           being contested in good faith by appropriate legal proceedings timely
    instituted  and  diligently  conducted  and for  which  a  reserve  or other
    appropriate provision, if any, as shall be required in conformity with  GAAP
    shall have been made;
 
       (ii)statutory   or   common  law   Liens   of  landlords   and  carriers,
           warehousemen, mechanics, suppliers,  materialmen, repairmen or  other
    similar Liens arising in the ordinary course of business and with respect to
    amounts  not yet delinquent or being  contested in good faith by appropriate
    legal proceedings timely instituted and diligently conducted and for which a
    reserve or other  appropriate provision,  if any,  as shall  be required  in
    conformity with GAAP shall have been made;
 
       (iii)
           Liens incurred or deposits made in the ordinary course of business in
           connection  with  workers' compensation,  unemployment  insurance and
    other types of social security;
 
       (iv)Liens incurred or deposits made to secure the performance of tenders,
           bids,  leases,   statutory   or  regulatory   obligations,   bankers'
    acceptances,  surety and appeal bonds, government contracts, performance and
    return- of-money bonds and other obligations of a similar nature incurred in
    the ordinary course of business (exclusive of obligations for the payment of
    borrowed money) and a  bank's unexercised right of  set-off with respect  to
    deposits made in the ordinary course;
 
       (v) easements, rights-of-way, municipal and zoning ordinances and similar
           charges,  encumbrances, title defects or other irregularities that do
    not materially interfere with the ordinary course of business of the Company
    or any of its other irregularities that do not materially interfere with the
    ordinary course of business of the Company or any of its Subsidiaries;
 
       (vi)Liens (including  extensions  and  renewals  thereof)  upon  real  or
           personal  property acquired after  the Issue Date;  PROVIDED that (A)
    such Lien  is  created  solely  for the  purpose  of  securing  Indebtedness
    Incurred  in accordance with the  "Limitation on Indebtedness" covenant, (1)
    to finance the cost (including the  cost of improvement or construction)  of
    the item of property or
 
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<PAGE>
    assets  subject thereto and such Lien is created prior to, at the time of or
    within six months  after the  later of  the acquisition,  the completion  of
    construction  or the commencement of full  operation of such property or (2)
    to refinance  any  Indebtedness previously  so  secured, (B)  the  principal
    amount of the Indebtedness secured by such Lien does not exceed 100% of such
    cost  and (C)  any such Lien  shall not extend  to or cover  any property or
    assets other than such  item of property or  assets and any improvements  on
    such item;
 
       (vii)
           leases  or  subleases  granted  to  others  that  do  not  materially
           interfere with the ordinary course of business of the Company and its
    Restricted Subsidiaries, taken as a whole;
 
       (viii)
           Liens encumbering property or assets under construction arising  from
           progress  or partial  payments by  a customer  of the  Company or its
    Restricted Subsidiaries relating to such property or assets;
 
        (ix) any interest or title  of a lessor in  the property subject to  any
    Capitalized Lease or operating lease;
 
       (x) Liens   arising  from   filing  Uniform   Commercial  Code  financing
           statements regarding leases;
 
       (xi)Liens on property of, or on  shares of stock or Indebtedness of,  any
           corporation existing at the time such corporation becomes, or becomes
    a part of, any Restricted Subsidiary; PROVIDED that such Liens do not extend
    to  or  cover  any property  or  assets  of the  Company  or  any Restricted
    Subsidiary other than the property or assets acquired;
 
       (xii)
           Liens in favor of the Company or any Restricted Subsidiary;
 
       (xiii)
           Liens arising from the rendering of a final judgment or order against
           the Company or any Restricted Subsidiary of the Company that does not
    give rise to an Event of Default;
 
       (xiv)
           Liens securing reimbursement obligations  with respect to letters  of
           credit  that  encumber documents  and the  property relating  to such
    letters of credit and the products and proceeds thereof;
 
       (xv)Liens in favor of customs and revenue authorities arising as a matter
           of law to  secure payment of  customs duties in  connection with  the
    importation of goods;
 
       (xvi)
           Liens  arising out of conditional  sale, title retention, consignment
           or similar arrangements  for the sale  of goods entered  into by  the
    Company  or any  of its  Restricted Subsidiaries  in the  ordinary course of
    business in  accordance with  the  past practices  of  the Company  and  its
    Restricted Subsidiaries prior to the Issue Date;
 
       (xvii)
            Liens on or sales of receivables;
 
       (xviii)
            Liens  securing  other Indebtedness  in an  aggregate amount  not to
            exceed $250,000 at any one time;
 
       (xix)Liens  on   assets   of  Unrestricted   Subsidiaries   that   secure
            Non-Recourse Debt of Unrestricted Subsidiaries;
 
       (xx) Liens existing on the Issue Date;
 
       (xxi)Liens granted after the Issue Date on any assets or Capital Stock of
            the  Company or its Restricted Subsidiaries  created in favor of the
    holders of the Notes;
 
       (xxii)
            Liens with respect to the assets of a Restricted Subsidiary  granted
            by  such  Restricted Subsidiary  to the  Company  or a  Wholly Owned
    Restricted Subsidiary to secure  Indebtedness owing to  the Company or  such
    other Wholly Owned Restricted Subsidiary;
 
       (xxiii)
            Liens  securing Indebtedness which is  Incurred to refinance secured
            Indebtedness which is permitted to be Incurred under clause (iii) of
    the second paragraph of the "Limitation on
 
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<PAGE>
    Indebtedness" covenant; PROVIDED that such Liens  do not extend to or  cover
    any  property or  assets of the  Company or any  Restricted Subsidiary other
    than the property or assets securing the Indebtedness being refinanced; and
 
       (xxiv)
            purchase money Liens upon equipment acquired or held by the  Company
            or  any  of its  Restricted Subsidiaries  taken  or retained  by the
    seller of such  equipment to  secure all  or a  part of  the purchase  price
    therefor; PROVIDED that such Liens do not extend to or cover any property or
    assets  of the Company or any Restricted Subsidiary other than the equipment
    so acquired.
 
    "PERSON" means  any  individual,  corporation,  limited  liability  company,
partnership,   joint   venture,   association,   joint-stock   company,   trust,
unincorporated organization or government or any agency or political subdivision
thereof.
 
    "PREFERRED STOCK" means,  with respect to  any Person, any  and all  shares,
interests,  participations  or other  equivalents  (however designated)  of such
Person's preferred or preference stock, whether now outstanding or issued  after
the  Issue Date,  and including, without  limitation, all classes  and series of
preferred or preference stock of such Person.
 
    "REDEEMABLE STOCK" means any class or series of Capital Stock of any  Person
that  by its  terms or  otherwise is (i)  required to  be redeemed  prior to the
Stated Maturity of the  Notes, (ii) redeemable  at the option  of the holder  of
such  class or series of Capital Stock at  any time prior to the Stated Maturity
of the Notes (unless the redemption  price is, at the Company's option,  without
conditions  precedent,  payable solely  is Common  Stock (other  than Redeemable
Stock) of the  Company) or (iii)  convertible into or  exchangeable for  Capital
Stock referred to in clause (i) or (ii) above or Indebtedness having a scheduled
maturity  prior to the Stated  Maturity of the Notes;  PROVIDED that any Capital
Stock that  would not  constitute Redeemable  Stock but  for provisions  thereof
giving  holders thereof the right to require such Person to repurchase or redeem
such Capital Stock upon the occurrence of an "asset sale" or "change of control"
occurring prior  to  the Stated  Maturity  of  the Notes  shall  not  constitute
Redeemable  Stock  if  the  "asset  sale"  or  "change  of  control"  provisions
applicable to such Capital Stock  are no more favorable  to the holders of  such
Capital Stock than the provisions contained in "Disposition of Proceeds of Asset
Sales"  and "Change in Control" covenants described above and such Capital Stock
specifically provides that such  Person will not repurchase  or redeem any  such
stock pursuant to such provision prior to the Company's repurchase of such Notes
as  are required to be  repurchased pursuant to the  "Disposition of Proceeds of
Asset Sales" and "Change in Control" covenants described above.
 
    "RESTRICTED SUBSIDIARY" of  a Person  means any Subsidiary  of the  referent
Person that is not an Unrestricted Subsidiary.
 
    "SIGNIFICANT SUBSIDIARY" means, at any date of determination, any Restricted
Subsidiary of the Company that, together with its Subsidiaries, (i) for the most
recent  fiscal  year  of  the  Company,  accounted  for  more  than  10%  of the
consolidated revenues of the Company and its Restricted Subsidiaries or (ii)  as
of  the end of such fiscal year, had  assets accounting for more than 10% of the
consolidated assets of the Company and  its Restricted Subsidiaries, all as  set
forth  on the most  recently available consolidated  financial statements of the
Company for such fiscal year.
 
    "SPECIFIED DATE" means any  redemption date, any date  of purchase of  Notes
pursuant  to the "Disposition of Proceeds of Asset Sales" or "Change in Control"
covenants described above, or any  date on which the  Notes are due and  payable
after an Event of Default.
 
    "STATED  MATURITY" means,  (i) with respect  to any debt  security, the date
specified in such debt security as the fixed date on which the final installment
of principal of such debt security is  due and payable and (ii) with respect  to
any  scheduled installment of principal of or interest on any debt security, the
date specified in such debt security as the fixed date on which such installment
is due and payable.
 
    "STRATEGIC EQUITY  INVESTOR" means  any company  which is  (or a  controlled
Affiliate of any company which is or a controlled Affiliate of which is) engaged
principally  in a cable or telecommunications  business which has a total market
capitalization of at least $1.0 billion.
 
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<PAGE>
    "SUBSIDIARY" means,  with  respect  to  any  Person,  (i)  any  corporation,
association  or other business entity of which more than 50% of the total voting
power of shares of Capital Stock  entitled (without regard to the occurrence  of
any  contingency) to  vote in  the election  of directors,  managers or trustees
thereof is at  the time  owned or controlled,  directly or  indirectly, by  such
Person or one or more of the other Subsidiaries of that Person (or a combination
thereof)  and (ii) any partnership (a) the  sole general partner or the managing
general partner of which is  such Person or a Subsidiary  of such Person or  (b)
the  only  general  partners  of  which  are  such  Person  or  of  one  or more
Subsidiaries of such Person (or any combination thereof).
 
    "TELECOMMUNICATIONS ASSETS" means all assets (including, without limitation,
assets  consisting  of  subscribers),  rights  (contractual  or  otherwise)  and
properties,   whether  tangible  or  intangible,   used  in  connection  with  a
Telecommunications Business.
 
    "TELECOMMUNICATIONS BUSINESS" means, when used  in reference to any  Person,
that such Person is engaged primarily in the business of (i) transmitting voice,
video   or  data   communications,  (ii)   creating,  developing   or  marketing
communications related network equipment, software and other devices for use  in
a  wireless  communications capacity  or (iii)  evaluating, participating  in or
pursuing any other activity or opportunity  that is related to those  identified
in clauses (i) or (ii) above.
 
    "TEMPORARY   CASH  INVESTMENT"  means  any  of  the  following:  (i)  direct
obligations of the United States or any agency thereof or obligations fully  and
unconditionally guaranteed by the United States or any agency thereof; (ii) time
deposit  accounts, certificates  of deposit  and money  market deposits maturing
within six months of the date of  acquisition thereof issued by a bank or  trust
company  which  is organized  under the  laws  of the  United States,  any state
thereof or any foreign country recognized  by the United States, and which  bank
or  trust  company has  capital, surplus  and  undivided profits  aggregating in
excess of $50.0  million (or the  foreign currency equivalent  thereof) and  has
outstanding  debt  which is  rated "A"  (or such  similar equivalent  rating) or
higher by at least one nationally recognized statistical rating organization (as
defined in Rule 436 under the Securities Act) or any money-market fund sponsored
by a  registered broker  dealer  or mutual  fund distributor;  (iii)  repurchase
obligations  with a term of  not more than 30  days for underlying securities of
the types described in  clause (i) above  entered into with  a bank meeting  the
qualifications  described in clause (ii)  above; (iv) commercial paper, maturing
not more than six months after the date of acquisition, issued by a  corporation
other  than an Affiliate  of the Company)  organized and in  existence under the
laws of the United States, any  state thereof or any foreign country  recognized
by  the United States with rating at the time as of which any investment therein
is made of  "P-1" (or higher)  according to Moody's  Investors Service, Inc.  or
"A-1"  (or  higher)  according  to  Standard &  Poor's  Ratings  Group;  and (v)
securities with maturities of  six months or less  from the date of  acquisition
issued  or fully  and unconditionally guaranteed  by any  state, commonwealth or
territory of  the United  States,  or by  any  political subdivision  or  taxing
authority  thereof, and rated at least "A" by Standard & Poor's Ratings Group or
Moody's Investors Service, Inc.;  PROVIDED that, notwithstanding the  foregoing,
the  maturity of  any of the  foregoing that  is applied to  provide security in
favor of the  Indebtedness referred  to in clause  (xxiv) of  the definition  of
"Permitted  Liens" may occur as late as the earliest date that such Indebtedness
may be redeemed at the option of  the obligor with respect to such  Indebtedness
and provided further that the Company shall cause such Liens referred to in such
clause  (xxiv) to be incurred  no later than the  first anniversary of the Issue
Date.
 
    "UNRESTRICTED SUBSIDIARY" means  any Subsidiary  that is  designated by  the
Board  as an Unrestricted Subsidiary pursuant to  a resolution of the Board; but
only to  the extent  that such  Subsidiary (i)  has no  Indebtedness other  than
Non-Recourse  Debt; (ii) is not party to any agreement, contract, arrangement or
understanding with  the Company  or  any Restricted  Subsidiary of  the  Company
unless  the terms of any such  agreement, contract, arrangement or understanding
are no less favorable  to the Company or  such Restricted Subsidiary than  those
that  might be obtained at  the time from Persons who  are not Affiliates of the
Company; (iii) is a Person with respect to which neither the Company nor any  of
its  Restricted  Subsidiaries  has  any direct  or  indirect  obligation  (A) to
subscribe for additional equity  interests or (B) to  maintain or preserve  such
Person's  financial condition or  to cause such Person  to achieve any specified
levels of operating results;  (iv) has not guaranteed  or otherwise directly  or
 
                                       95
<PAGE>
indirectly provided credit support for any Indebtedness of the Company or any of
its  Restricted Subsidiaries; and (v) has, immediately prior to the commencement
of material business operations, at least one director on its board of directors
that is  not a  director or  executive  officer of  the Company  or any  of  its
Restricted  Subsidiaries and has  at least one  executive officer that  is not a
director  or  executive  officer  of  the  Company  or  any  of  its  Restricted
Subsidiaries.  Any  such designation  by  the Board  shall  be evidenced  to the
Trustee by filing with  the Trustee a  certified copy of  the resolution of  the
Board  giving effect to such designation and an Officers' Certificate certifying
that such designation complied with  the foregoing conditions and was  permitted
by  the covenant  described above  under the  caption "Limitation  on Restricted
Payments." If, at any time, any  Unrestricted Subsidiary would fail to meet  the
foregoing  requirements as an Unrestricted Subsidiary, it shall thereafter cease
to be  an  Unrestricted  Subsidiary  for  purposes  of  the  Indenture  and  any
Indebtedness  of such Subsidiary shall be deemed  to be incurred by a Restricted
Subsidiary of the  Company as of  such date  (and, if such  Indebtedness is  not
permitted  to be incurred as of such date under the covenant described under the
caption "Limitation on Indebtedness,"  the Company shall be  in default of  such
covenant). The Board may at any time designate any Unrestricted Subsidiary to be
a Restricted Subsidiary; PROVIDED that such designation shall be deemed to be an
incurrence  of Indebtedness  by a  Restricted Subsidiary  of the  Company of any
outstanding Indebtedness of  such Unrestricted Subsidiary  and such  designation
shall only be permitted if (i) such Indebtedness is permitted under the covenant
described under the caption "Limitation on Indebtedness," and (ii) no Default or
Event of Default would be in existence following such designation.
 
    "VOTING  STOCK" means with respect to any Person, 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.
 
    "VOTING  TRUST AGREEMENT"  means that  certain Voting  Trust and Irrevocable
Proxy Agreement, to be entered into on the date hereof.
 
    "WHOLLY OWNED" means,  with respect to  any Subsidiary of  any Person,  such
Subsidiary  if all  of the outstanding  Capital Stock in  such Subsidiary (other
than any  director's  qualifying  shares or  Investments  by  foreign  nationals
mandated  by applicable law) is owned by such Person or one or more Wholly Owned
Subsidiaries of such Person.
 
                            DESCRIPTION OF WARRANTS
 
    The Warrants will be  issued pursuant to a  warrant agreement (the  "Warrant
Agreement")  by and between the Company and                         , as warrant
agent (the "Warrant Agent"). The following summary of certain provisions of  the
Warrant  Agreement  and the  Warrants does  not  purport to  be complete  and is
qualified in  its  entirety  by  reference to  the  Warrant  Agreement  and  the
Warrants,  including  the  definitions  therein of  certain  terms.  The Warrant
Agreement will be substantially in the form of the Warrant Agreement filed as an
exhibit to the Registration Statement of which this Prospectus is a part.
 
GENERAL
 
    Each Warrant, when  exercised, will  entitle the holder  thereof to  receive
       shares of Common Stock (such shares, the "Warrant Shares") at an exercise
price  of $      per share  (the "Exercise Price").  The Exercise  Price and the
number of Warrant Shares issuable on exercise  of a Warrant are both subject  to
adjustment  in certain cases referred to  below. The Warrants are exercisable at
any time on or  after the Separation Date.  Unless exercised, the Warrants  will
automatically expire on             , 2006 (the "Expiration Date"). The Warrants
will entitle the holders thereof to purchase in the aggregate approximately    %
of  the outstanding Common Stock  of the Company on a  fully diluted basis as of
the date of issuance of the Warrants after giving effect to the consummation  of
the Offerings.
 
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<PAGE>
    The Warrants may be exercised at any time on or after the Separation Date by
surrendering  to the  Company at  the office  of the  Warrant Agent  the Warrant
certificates evidencing such Warrants with the accompanying form of election  to
purchase  properly completed and executed, together with payment of the Exercise
Price. Payment of  the Exercise  Price may  be made  in the  form of  cash or  a
certified  or official  bank check  payable to  the order  of the  Company. Upon
surrender of the  Warrant certificate  and payment  of the  Exercise Price,  the
Warrant  Agent will  deliver or cause  to be  delivered, to or  upon the written
order of  such holder,  a stock  certificate representing  the number  of  whole
Warrant  Shares or other securities or property to which such holder is entitled
under the Warrant Agreement and the Warrants, including, without limitation, any
cash payment to adjust for fractional interests in Warrant Shares issuable  upon
such  exercise.  If  less  than  all of  the  Warrants  evidenced  by  a Warrant
certificate are to be  exercised, a new Warrant  certificate will be issued  for
the  remaining  number of  Warrants. The  Common  Shares to  be issued  upon the
exercise of the Warrants will be registered under the Securities Act.
 
    No fractional Warrant Share will be issued upon exercise of the Warrants. If
any fraction of a  Warrant Share would, except  for the foregoing provision,  be
issuable  on the exercise of any Warrants  (or a specified portion thereof), the
Company shall  pay an  amount in  cash equal  to the  current market  price  per
Warrant  Share,  as determined  on the  day immediately  preceding the  date the
Warrant is presented for exercise, multiplied by such fraction, computed to  the
nearest whole U.S. cent.
 
    Certificates  for Warrants  will be issued  in registered form  only, and no
service charge  will be  made  for registration  of  transfer or  exchange  upon
surrender  of  any  Warrant  certificate  at the  office  of  the  Warrant Agent
maintained for that purpose. The Company may require payment of a sum sufficient
to cover any tax or other governmental charge that may be imposed in  connection
with any registration or transfer or exchange of Warrant certificates.
 
    The  holders of the Warrants  have no right to  vote on matters submitted to
the stockholders of  the Company  and have no  right to  receive dividends.  The
holders  of the  Warrants are  not be  entitled to  share in  the assets  of the
Company in the event of liquidation, dissolution or winding up of the  Company's
affairs.
 
    In  the  event of  taxable  distribution to  holders  of Common  Stock which
results in an adjustment to the number of Warrant Shares or other  consideration
for  which  a Warrant  may be  exercised, the  holders of  the Warrants  may, in
certain circumstances,  be deemed  to have  received a  distribution subject  to
United  States federal income tax as a dividend. See "Certain Federal Income Tax
Considerations".
 
REGISTRATION OF WARRANT SHARES
 
    Holders of  Warrants will  be able  to  exercise their  Warrants only  if  a
registration  statement relating to the Warrant Shares is then in effect, or the
exercise of such Warrants  is exempt from the  registration requirements of  the
Securities  Act,  and such  securities  are qualified  for  sale or  exempt from
qualification under the applicable  securities laws of the  states in which  the
various holders of the Warrants or other persons to whom it is proposed that the
Warrant  Shares be  issued on  exercise of the  Warrants reside.  The Company is
required under the  terms of  the Warrant  Agreement to  file and  use its  best
efforts to make effective, by the earlier of   days from the closing of the Unit
Offering or 45 days after the occurrence of a Change in Control, and (subject to
certain "black-out" periods not to exceed 45 days in any calendar year) maintain
effective  until the expiration or exercise of all Warrants a shelf registration
statement on an appropriate form under the Securities Act covering the  issuance
of  the  Warrant Shares  upon  the exercise  of the  Warrants.  There can  be no
assurance that the Company will be able to file, cause to be declared  effective
or  keep  a  registration  statement continuously  effective  until  all  of the
Warrants have been exercised or have expired.
 
ADJUSTMENTS
 
    The number of shares  of Common Stock purchasable  upon the exercise of  the
Warrants  and the Exercise Price  both will be subject  to adjustment in certain
events (subject to certain exceptions)
 
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<PAGE>
including (i) the payment by the Company of dividends (and other  distributions)
on Common Stock payable in Common Stock or other shares of the Company's capital
stock,  (ii) subdivisions,  combinations and reclassifications  of Common Stock,
(iii) the issuance to all holders of Common Stock of rights, options or warrants
entitling them to subscribe for Common  Stock or of securities convertible  into
or  exchangeable for Common Stock, for a consideration per share of Common Stock
which is less than the current market  price per share of Common Stock and  (iv)
the  distribution to all holders of Common Stock of any of the Company's assets,
debt securities  or any  rights or  warrants to  purchase securities  (excluding
those  rights and warrants referred to in  clause (iii) above and excluding cash
dividends less than a specified amount). In addition, the Exercise Price may  be
reduced  in  the event  of purchases  of Common  Stock pursuant  to a  tender or
exchange offer made by the Company of any subsidiary thereof at a price  greater
than  the sale  price of the  Common Stock at  the time such  tender or exchange
offer expires.
 
    No adjustment in the Exercise Price will be required unless such  adjustment
would  require  an increase  or decrease  of at  least one  percent (1%)  in the
Exercise Price; PROVIDED, HOWEVER, that any adjustment which is not made will be
carried forward and taken into account in any subsequent adjustment.
 
    In the case of certain consolidations or mergers of the Company, or the sale
of all or substantially all of the assets of the Company to another corporation,
each Warrant shall thereafter be exercisable  for the right to receive the  kind
and  amount of  shares of stock  or other  securities or property  to which such
holder would have  been entitled as  a result of  such consolidation, merger  or
sale had the Warrants been exercised immediately prior thereto.
 
AUTHORIZED SHARES
 
    The  Company has  authorized for  issuance such  number of  shares of Common
Stock as shall be  issuable upon the due  exercise of all outstanding  Warrants.
Such  shares of Common Stock, when paid for and issued, will be duly and validly
issued, fully paid and non-assessable, free  of preemptive rights and free  from
all  taxes,  liens, charges  and security  interests with  respect to  the issue
thereof (other than any such tax, lien, charge or security interest imposed upon
or granted by the holder of the Common Stock).
 
AMENDMENT
 
    From time to time, the Company and the Warrant Agent, without the consent of
the holders of the Warrants, may  amend or supplement the Warrant Agreement  for
certain  purposes, including curing defects or inconsistencies or making changes
that do not materially adversely affect the rights of any holder. Any  amendment
or supplement to the Warrant Agreement that has a material adverse effect on the
interests  of the holders of  the Warrants shall require  the written consent of
the holders of a majority of  the then outstanding Warrants (excluding  Warrants
held by the Company or any of its Affiliates). The consent of each holder of the
Warrants  affected shall  be required  for any  amendment pursuant  to which the
Exercise Price would be  increased or the number  of Warrant Shares  purchasable
upon exercise of Warrants would be decreased (other than pursuant to adjustments
provided in the Warrant Agreement).
 
                                       98
<PAGE>
GOVERNING LAW
 
    The Warrant Agreement and the Warrants will be governed by, and construed in
accordance  with,  the laws  of  the State  of New  York  without regard  to the
principles of conflicts of law thereof.
 
REPORTS
 
    Whether or not the Company is  subject to the reporting requirements of  the
Exchange  Act, the  Company shall  cause copies  of the  reports described under
"Description of Notes  -- Certain  Covenants -- Reports"  to be  filed with  the
Commission  (to the extent  permitted) and the  Warrant Agent and  mailed to the
holders at their addresses appearing in  the register of Warrants maintained  by
the  Warrant  Agent to  the same  extent as  such reports  are furnished  to the
holders of Notes in accordance with the Indenture.
 
                                       99
<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
    The authorized capital stock of the Company consists of 60,000,000 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  April  25,  1996,  there  were  18,114,135  shares  of  Common Stock
outstanding held of record  by four stockholders (without  giving effect to  the
Merger,  any  conversion  of  outstanding Preferred  Stock  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 outstanding shares 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  April  25,  1996,  there  were  920,951  shares  of  Preferred Stock
outstanding held of  record by  15 stockholders.  Upon the  consummation of  the
Offerings,  all outstanding shares of Preferred Stock will automatically convert
to shares  of  Common Stock,  and  343,359 shares  of  Preferred Stock  will  be
retired.  See "Principal  Stockholders." 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 Notes -- Certain Covenants."
 
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  Offering,
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 not subject to the provisions of Section 203 of the Delaware
General Corporation Law regulating  corporate takeovers. A Delaware  corporation
may "opt out" of Section 203 by an
 
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<PAGE>
express  provision in  its original certificate  of incorporation  or an express
provision in  its  certificate  of  incorporation or  bylaws  resulting  from  a
stockholders'  amendment  approved by  at least  a  majority of  the outstanding
voting shares. The Company has "opted out" of the application of Section 203.
 
TRANSFER AGENT AND REGISTRAR
 
    The Transfer Agent and Registrar for  the Common Stock is Continental  Stock
Transfer & Trust Company.
 
LISTING
 
    The  Company is  applying for  quotation of the  Common Stock  on the Nasdaq
National Market under the symbol "ARTT."
 
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<PAGE>
                      DESCRIPTION OF CERTAIN INDEBTEDNESS
 
EMI NOTE
 
    In connection  with the  acquisition by  ART Corp.  of the  EMI Assets,  the
Company  issued  to  EMI  a $1.5  million  principal  amount  non-negotiable and
non-transferable 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 July 1996. The  EMI
Note matures on November 14, 1998. ART Corp. has also guaranteed the obligations
of  ART under the EMI Note. See "Business -- Agreements Relating to Licenses and
Acquisitions -- EMI Acquisition."
 
EQUIPMENT FINANCING
 
    On April 29,  1996, CRA,  Inc. ("CRA")  entered into  the secured  Equipment
Financing  with  the  Company  for  the purchase  from  P-Com  of  38  GHz radio
equipment. To evidence its obligations and 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
29, 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  will be  repaid  with proceeds  from the
Offerings. See "Use of Proceeds."
 
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<PAGE>
                   CERTAIN FEDERAL INCOME TAX CONSIDERATIONS
 
    The following discussion is a summary of the material United States  federal
income tax considerations relevant to the purchase, ownership and disposition of
the  Units, Notes and Warrants by holders  acquiring Units on original issue for
cash, but  does not  purport to  be a  complete analysis  of all  potential  tax
effects.  The discussion  is based  upon the Internal  Revenue Code  of 1986, as
amended (the  "Code"), Treasury  regulations, Internal  Revenue Service  ("IRS")
rulings  and pronouncements and judicial decisions all  in effect as of the date
hereof, all of which are subject to change at any time, and any such change  may
be applied retroactively in a manner that could adversely affect a holder of the
Units,  Notes or Warrants.  The discussion does  not address all  of the federal
income tax  consequences that  may be  relevant to  a holder  in light  of  such
holder's  particular circumstances or to holders  subject to special rules, such
as certain financial institutions,  insurance companies, dealers in  securities,
foreign  corporations,  nonresident alien  individuals  and persons  holding the
Units, Notes  or  Warrants as  part  of  a "straddle,"  "hedge"  or  "conversion
transaction." Moreover, the effect of any applicable state, local or foreign tax
laws  is not discussed. The discussion deals only with Units, Notes and Warrants
held as "capital assets" within the meaning of section 1221 of the Code.
 
    The Company has not sought and will  not seek any rulings from the IRS  with
respect  to  the  position of  the  Company  discussed below.  There  can  be no
assurance that the  IRS will not  take a different  position concerning the  tax
consequences  of the purchase,  ownership or disposition of  the Units, Notes or
Warrants or that any such position would not be sustained.
 
    PROSPECTIVE INVESTORS SHOULD CONSULT THEIR  OWN TAX ADVISORS WITH REGARD  TO
THE  APPLICATION OF THE  TAX CONSIDERATIONS DISCUSSED  BELOW TO THEIR PARTICULAR
SITUATIONS AS WELL AS THE APPLICATION OF ANY STATE, LOCAL, FOREIGN OR OTHER  TAX
LAWS.
 
THE UNITS
 
    Because  the original  purchasers of the  Notes also  will acquire Warrants,
each Note is likely to be treated for federal income tax purposes as having been
issued as part  of an "investment  unit" consisting of  the Note and  associated
Warrants.  The issue  price of  an investment  unit consisting  of the  Note and
associated Warrants will  be the first  price at which  a substantial amount  of
Units  are  sold  to the  public  for  money (excluding  sales  to underwriters,
placement agents or wholesalers, etc.). The "issue price" of an investment  unit
is  allocated between  its component parts  based on their  relative fair market
values. A holder of a  Unit must use the  issuer's allocation unless the  holder
discloses  on its federal income  tax return that it  plans to use an allocation
that is inconsistent with the issuer's allocation.
 
    The Company will allocate the issue price of a Unit between the Note and the
associated Warrants in accordance with their relative fair market values on  the
issue date. The Company will use that allocation to determine the issue price of
the  Notes and the  holder's tax basis  in the Warrants.  That allocation is not
binding on the IRS.
 
THE NOTES
 
    The Notes will be issued with  "original issue discount" for federal  income
tax  purposes. A holder generally is required to include original issue discount
in gross income as it accrues,  regardless of the holder's method of  accounting
for  federal income tax  purposes. Accordingly, each holder  will be required to
include amounts in gross income in advance  of the receipt of the cash to  which
such income is attributable.
 
    The amount of original issue discount with respect to each Note is an amount
equal  to the excess of  the "stated redemption price  at maturity" of such Note
over its issue price. The stated redemption price at maturity of each Note  will
include  all cash  payments, including  principal and  interest, required  to be
 
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<PAGE>
made thereunder until maturity. The issue price of a Note will be equal to  that
portion of the issue price of the Unit allocable to the Note as described above.
Accordingly,  each Note  will be  issued with  a substantial  amount of original
issue discount.
 
    TAXATION OF ORIGINAL ISSUE DISCOUNT.  Each holder of a Note will be required
to include in gross income an amount equal to the sum of the "daily portions" of
the original issue discount of the Note for all days during each taxable year in
which the holder holds the Note.  The daily portions of original issue  discount
will  be determined on a constant interest  rate basis by allocating to each day
during the taxable year in which the holder holds the Note a pro rata portion of
the original issue discount thereon that is attributable to the "accrual period"
in which  such  day is  included.  The amount  of  the original  issue  discount
attributable  to each full accrual  period will be the  product of the "adjusted
issue price" of the Note at the beginning of such accrual period and the  "yield
to maturity" of the Note (adjusted to reflect the length of the accrual period).
The  adjusted issue price of a Note at the beginning of an accrual period is the
original issue price  of the Note  plus the aggregate  amount of original  issue
discount  that has accrued in all prior  accrual periods, less any cash payments
on the Note  on or before  the first day  of such accrual  period. The yield  to
maturity  is the discount rate that, when used in computing the present value of
all principal and interest payments to be  made on the Note, produces an  amount
equal to the issue price.
 
    The  accrual period generally is  the six-month period ending  on the day in
each calendar year corresponding to the day before the maturity date of the Note
or the date six months before such date. The initial accrual period of a note is
the short period beginning on  the issue date and ending  on the day before  the
first  day  of the  first  full accrual  period.  The amount  of  original issue
discount attributable to an initial short  accrual period may be computed  under
any reasonable method.
 
    The  Company is required to furnish certain information to the IRS, and will
furnish annually  to record  holders  of a  Note,  information with  respect  to
original issue discount accruing during the calendar year. That information will
be  based upon the  adjusted issue price of  the Note as if  the holder were the
original holder of the Note.
 
    A holder who purchases a  Note for an amount  other than the adjusted  issue
price  and/or on a date other than the end of an accrual period will be required
to determine for himself the  amount of original issue  discount, if any, he  is
required to include in gross income for federal income tax purposes.
 
    SALE OR RETIREMENT OF A NOTE.  In general, a holder of a Note will recognize
gain or loss upon the sale, retirement or other taxable disposition of such Note
in an amount equal to the difference between (a) the amount of cash and the fair
market  value of  property received in  exchange therefor (except  to the extent
attributable to  the payment  of accrued  interest or  original issue  discount,
which  generally will  be taxable to  a holder  as ordinary income)  and (b) the
holder's adjusted tax basis in such Note.
 
    A holder's tax basis in a Note generally will be equal to the price paid for
such Note, increased by the amount of original issue discount, if any,  included
in gross income prior to the date of disposition, and decreased by the amount of
any payment on such Note prior to disposition.
 
    Any  gain  or  loss recognize  on  the  sale, retirement,  or  other taxable
disposition of a Note generally will be capital gain or loss. Such capital  gain
or  loss generally will be  long-term capital gain or loss  if the Note had been
held for more than one year.
 
    Holders should be aware  that the resale  of a Note may  be affected by  the
"market discount" rules of the Code under which a subsequent purchaser of a Note
acquiring  the Note at a market discount  generally would be required to include
as ordinary  income a  portion of  the  gain realized  upon the  disposition  or
retirement  of such Note to  the extent of the  market discount that has accrued
while the debt instrument was held by such holder.
 
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<PAGE>
THE WARRANTS
 
    Upon the sale or  exchange of a  Warrant (including the  receipt of cash  in
lieu  of a fractional interest in a Warrant Share upon exercise of a Warrant), a
holder will recognize gain or loss in an amount equal to the difference  between
the  amount of cash and the fair  market value of property received therefor and
the holder's tax basis in the Warrant. A holder's initial tax basis in a Warrant
acquired in the Unit  Offering will be  that portion of the  issue price of  the
Units allocable to the Warrant, as described above, subject to adjustment in the
events  described below. Such gain  or loss will be capital  gain or loss if the
Warrant Shares to  which the Warrants  relate would  be a capital  asset in  the
hands  of the Warrant  holder. Any such  capital gain or  loss will be long-term
capital gain or loss if the Warrant was held for more than one year.
 
    The exercise of a Warrant for cash will not result in a taxable event to the
holder of the Warrant (except to the extent of cash, if any, received in lieu of
fractional interest in a  Warrant Share). Upon such  exercise, the holder's  tax
basis  in the Warrant Shares obtained will be  equal to the sum of such holder's
tax basis  in  the Warrant  (described  above) and  the  exercise price  of  the
Warrant;  the holder's holding  period with respect to  such Warrant Shares will
commence on the day  after the date  of exercise. If  a Warrant expires  without
being  exercised, the holder will recognize a loss in an amount equal to its tax
basis in the Warrant. Such loss will be a capital loss if the Warrant Shares  to
which  the Warrants relate would  have been a capital asset  in the hands of the
Warrant holder, and such capital  loss will be a  long-term capital loss is  the
Warrant was held for more than one year.
 
    Adjustments  to the conversion ratio of the Warrants, or the failure to make
adjustments, may  in certain  circumstances  result in  the receipt  of  taxable
constructive  dividends by the holder, in which  event the holder's tax basis in
the Warrants would be increased by an amount equal to the constructive dividend.
 
BACKUP WITHHOLDING
 
    A holder of a  Note may be subject  to backup withholding at  a rate of  31%
with respect to interest and original issue discount on, and gross proceeds upon
sale  or retirement of, a Note unless such  holder (i) is a corporation or other
exempt recipient and, when required,  demonstrates that fact, or (ii)  provides,
when  required, a correct taxpayer  identification number, certified that backup
withholding is not in effect and otherwise complies with applicable requirements
of the backup withholding  rules. Backup withholding is  not an additional  tax;
any  amounts so withheld are creditable against the holder's federal income tax,
provided the required information is provided to the IRS.
 
DEDUCTIBILITY OF ORIGINAL ISSUE DISCOUNT AND INTEREST PAYMENTS
 
    The deduction  by the  Company in  respect of  interest (including  original
issue  discount) accrued with respect  to the Notes will  be limited in part and
deferred in part if the Notes are "applicable high yield discount  obligations."
The  Company anticipates that  the Notes will be  applicable high yield discount
obligations because,  among other  things,  it is  expected  that the  yield  to
maturity  of the Notes will  exceed the sum of  the applicable federal long-term
rate (a  rate  published  by the  IRS  each  month for  application  during  the
following  calendar month) in effect  at the time of  issuance of the Notes (the
"AFR") plus  five percentage  points. If  the Notes  are applicable  high  yield
discount obligations, then (i) if the yield to maturity of the Notes exceeds the
sum  of the AFR plus six percentage points (such excess referred to below as the
"Disqualified Yield"),  the deduction  for  interest (including  original  issue
discount) accrued on the Notes will be permanently disallowed to the extent such
interest  or original issue discount is  attributable to the Disqualified Yield,
and such  interest  (including original  issue  discount) would  be  treated  as
dividends  to  corporate holders  of the  Notes for  purposes of  the dividends-
received deduction (to the extent that  such amounts would have been treated  as
dividends  had they been distributions  made by the Company  with respect to its
stock) and (ii) the remainder of the original issue discount on the Notes  would
not be deductible by the Company until paid.
 
                                      105
<PAGE>
                                  UNDERWRITING
 
    Subject to the terms and conditions of the Purchase Agreement (the "Purchase
Agreement"),   among  the  Company,  Merrill   Lynch,  Pierce,  Fenner  &  Smith
Incorporated ("Merrill Lynch"), Montgomery Securities ("Montgomery  Securities")
and  Smith  Barney Inc.  ("Smith Barney"  and, together  with Merrill  Lynch and
Montgomery Securities, the "Underwriters"),  the Company has  agreed to sell  to
the  Underwriters, and each Underwriter has agreed to purchase from the Company,
severally and  not jointly,  the number  of Units  set forth  opposite its  name
below. The Purchase Agreement provides that, subject to the terms and conditions
set  forth therein, the  Underwriters will be  obligated to purchase  all of the
Units if any such Units are purchased.
 
<TABLE>
<CAPTION>
                                                                    NUMBER
              UNDERWRITERS                                         OF UNITS
                                                                   ---------
 
<S>                                                                <C>
Merrill Lynch, Pierce, Fenner & Smith
           Incorporated..........................................
Montgomery Securities............................................
Smith Barney Inc.................................................
                                                                   ---------
           Total.................................................
                                                                   ---------
                                                                   ---------
</TABLE>
 
    The Underwriters propose to  offer the Units directly  to the public at  the
offering  price set forth on  the cover page of this  Prospectus, and in part to
certain selected dealers at such price less a concession not in excess of      %
per  Unit. The several Underwriters  may allow, and such  dealers may reallow, a
discount not in excess of       % per Unit to  certain other dealers. After  the
initial  public offering, the public offering price, concession and discount may
be changed. The Underwriters do not intend to confirm sales to any accounts over
which they exercise discretionary authority.
 
    There is  currently  no  public market  for  the  Units, the  Notes  or  the
Warrants, and the Company does not intend to apply for listing of the Units, the
Notes  or  the  Warrants  on  any securities  exchange  or  on  any inter-dealer
quotation system. The  Company is  applying for  quotation of  the Common  Stock
(including  the Warrant Shares)  on the Nasdaq National  Market. The Company has
been advised by the Company that, following the completion of the initial public
offering of the Notes, the Underwriters presently intend to make a market in the
Units,  the  Notes  and  the  Warrants  as  permitted  by  applicable  laws  and
regulations; however, they are not obligated to do so and any such market-making
may  be discontinued at any  time without notice at  the sole discretion of each
Underwriter. Accordingly, there  can be  no assurance  as to  whether an  active
public  market for the  Units, the Notes or  the Warrants will  develop or, if a
public market does develop, as  to the liquidity of  the trading market for  the
Units,  the Notes or the Warrants. If  an active public market does not develop,
the market price and liquidity for the  Units, the Notes or the Warrants may  be
adversely  affected. See  "Risk Factors  -- Absence  of Public  Market; Possible
Volatility of Stock Price"
 
    The Company  has  agreed  to  indemnify  the  Underwriters  against  certain
liabilities,  including liabilities under the Securities Act of 1933, as amended
(the "Securities  Act"),  and, under  certain  circumstances, to  contribute  to
payments the Underwriters may be required to make in respect thereof.
 
    The  Company has agreed that it will not,  for a period of 180 days from the
date of this Prospectus, without the prior written consent of the  Underwriters,
directly  or indirectly, offer, sell, grant  any option to purchase or otherwise
dispose of, any debt security of the  Company which is publicly offered or  sold
pursuant to Rule 144A under the Securities Act.
 
    Montgomery  Securities is  acting as an  underwriter in  connection with the
Common Stock  Offering and  will receive  customary compensation  in  connection
therewith.
 
                                      106
<PAGE>
                                 LEGAL MATTERS
 
    The validity of the Units, the Notes and the Warrants offered hereby will be
passed  upon for the Company  by Hahn & Hessen LLP,  New York, New York. Certain
legal matters in connection with the Unit  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  Telecom Corp. as of
December 31, 1995 and for the period from March 28, 1995 (date of inception)  to
December  31, 1995 and 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 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  Securities  and Exchange  Commission (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 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.  In addition,  the Indenture and  the Warrant Agreement  provide that the
Company, to the extent that it is not required to file such information pursuant
to the Exchange  Act, shall provide  the Trustee  and holders of  the Notes  and
Warrants  with audited year-end financial statements  of the Company prepared in
accordance with GAAP and substantially in  the form of the Financial  Statements
included in this Prospectus, and unaudited quarterly financial statements of the
Company  prepared in accordance with  GAAP and substantially in  the form of the
Financial Statements included in this Prospectus.
 
                                      107
<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 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.
 
    CAP (COMPETITIVE ACCESS PROVIDER) --  A company that provides its  customers
with  an  alternative to  the  local telephone  company  for local  transport of
private line,  special  access  and  interstate  transport  of  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  among the many  issues related to  the
telecommunication  industry  that  are being  debated  for  federal legislation.
Essentially, customers should be able to have 1+ and 0+ service no matter  which
local or long distance carrier they choose. For example, when MCI first got into
the  long distance business, customers had to dial a ten digit prefix before the
number they  were calling.  This  was considered  unacceptable  to many  in  the
industry who favor "dialing parity."
 
    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.
 
                                      108
<PAGE>
    ESMR  (ENHANCED  SPECIALIZED MOBILE  RADIO)  -- A  mobile  services category
granted certain radio  spectrum rights by  the FCC before  the advent of  modern
cellular networks.
 
    FCC -- Federal Communications Commission.
 
    FIBER  OPTICS  --  Fiber  optic  cable  is  the  medium  of  choice  for the
telecommunications  and  cable  industries.   Fiber  is  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. A strand of fiber optic
cable is as thick as  a human hair yet is  said to have more bandwidth  capacity
than copper cable the size of a telephone pole.
 
    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.
 
    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, as well  as a select few CAPs  that are authorized for IXC
service.
 
    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.
 
    LATAS (LOCAL ACCESS AND TRANSPORT AREAS) -- The geographically defined areas
in  which LECs  are 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.
 
                                      109
<PAGE>
    MARKET  -- The  potential and  actual customers  within the  boundaries of a
wireless license.  For simplicity,  census  or other  definitions may  be  used,
though each application as granted defines its own actual boundaries.
 
    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 created  two distinct  segments of  telecommunications
service:  local  and  long  distance.  This  laid  the  groundwork  for  intense
competition in  the  long  distance  industry,  but  essentially  created  seven
separate  regionally-based local exchange  service monopolies. The  MFJ has been
superseded by the Telecommunications Act of 1996.
 
    MSA (METROPOLITAN STATISTICAL AREA) -- An area erected by Rand McNally based
upon various business demographics  to define a  contiguous urban area,  without
reference to political or similar boundaries.
 
    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
generally refers to frequencies above 2 GHz.
 
    MILLIMETRIC  MICROWAVE OR MILLIMETER WAVE -- Those portions of the microwave
radio spectrum having either  wave length measured in  millimeter lengths, or  a
frequency 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. This is considered  to be anti-competitive because customers
are reluctant to change numbers, since  they may lose business or confuse  those
people  trying to call  them. It is  currently being ascertained  whether or not
number portability is technologically and  economically feasible, and over  what
time frame it can be implemented.
 
    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.
 
    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 long  distance carrier has
installed transmission equipment  in a service  area that serves  as, or  relays
calls to, a network switching center of that long distance carrier.
 
    PSTN  (PUBLIC SWITCHED  TELECOMMUNICATIONS NETWORK)  -- The  traditional LEC
networks.
 
    RBOCS (REGIONAL BELL  OPERATING COMPANIES) --  The holding companies  owning
LEC affiliates of the old AT&T or Bell system.
 
                                      110
<PAGE>
    REPEATER -- An intermediate transceiver between two transceivers established
to circumvent obstacles in the links, 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 or in windows  of tall buildings, on
special towers or even on utility poles or pylons.
 
    WIDEBAND -- Data streams between 64 kilobits and 1.544 megabits per second.
 
                                      111
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                                                              PAGE
                                                                                                            ---------
<S>                                                                                                         <C>
Advanced Radio Telecom Corp.
  Unaudited Pro Forma:
    Unaudited Pro Forma Condensed Balance Sheet as of December 31, 1995...................................     F-3
    Unaudited Pro Forma Condensed Statement of Operations for the year ended December 31, 1995............     F-4
    Notes to Unaudited Pro Forma Condensed Financial Statements...........................................     F-5
 
  Historical:
    Report of Independent Accountants.....................................................................     F-6
    Balance Sheet as of December 31, 1995.................................................................     F-7
    Statement of Operations for the period from March 28, 1995 (date of inception) to December 31, 1995...     F-8
    Statement of Stockholders' Deficit for the period from March 28, 1995 (date of inception) to December
     31, 1995.............................................................................................     F-9
    Statement of Cash Flows for the period from March 28, 1995 (date of inception) to December 31, 1995...    F-10
    Notes to Financial Statements.........................................................................    F-11
 
Advanced Radio Technologies Corporation:
  Historical:
    Report of Independent Accountants.....................................................................    F-23
    Balance Sheets as of December 31, 1995 and 1994.......................................................    F-24
    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-25
    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-26
    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-27
    Notes to Financial Statements.........................................................................    F-28
</TABLE>
 
                                      F-1
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
               UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS
                               DECEMBER 31, 1995
 
    The  following  unaudited  pro  forma  condensed  financial  statements  are
presented as if all of the following transactions had occurred: (i) the exchange
of the Advent/ART Securities, including accrued interest, into 232,826 shares of
ART Preferred Stock (which  convert into 3,026,738 shares  of Common Stock  upon
consummation  of the Offerings) and the related anti-dilution share adjustments;
(ii) the  issuance of  48,893  shares of  Preferred  Stock (which  convert  into
635,609  shares  of Common  Stock upon  consummation of  the Offerings)  and the
Ameritech Warrant to Ameritech in exchange  for $2,350,000 in cash proceeds  and
the Ameritech Strategic Distribution Agreement, after deducting related expenses
of  $150,000, and the recognition of a $1,053,000 market development expense for
the value ascribed to the Ameritech Strategic Distribution Agreement; (iii)  the
receipt of $4,950,000 in cash proceeds from the issuance of the Bridge Notes and
the  Bridge  Warrants, after  deducting related  expenses  of $50,000;  (iv) 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; and  (v) the  effects of  the  Merger,
including  the issuance of  ART Common Stock  to ART Corp.  stockholders and the
cancellation of all outstanding ART Corp. common stock.
 
    The following unaudited pro forma as adjusted condensed financial statements
reflect further adjustments assuming the sale by the Company of (i)       shares
of Common Stock offered in the Common Stock Offering based on an assumed initial
public  offering price of $     per share, the  midpoint of the filing range set
forth on the cover page of the prospectus relating to the Common Stock  Offering
and  (ii)  the Units  offered in  the Unit  Offering, and,  in each  case, after
deducting the estimated underwriting discount  and offering expenses, (iii)  the
receipt and application of the net proceeds therefrom and (iv) the conversion of
all outstanding shares of Preferred Stock into shares of Common Stock.
 
    All such transactions are reflected as if they had occurred as of January 1,
1995  for the unaudited pro forma condensed statement of operations and December
31, 1995 for the unaudited pro forma condensed balance sheet.
 
    These unaudited pro forma condensed  financial statements were derived  from
the  audited financial  statements of ART  and ART  Corp. and should  be read in
conjunction with  the audited  financial  statements of  ART and  related  notes
thereto,  and the  audited financial statements  of ART Corp.  and 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 TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                  UNAUDITED PRO FORMA CONDENSED BALANCE SHEET
<TABLE>
<CAPTION>
                                                               DECEMBER 31, 1995
                         ----------------------------------------------------------------------------------------------
                                                   HISTORICAL
                         ---------------------------------------------------------------
                          ADVANCED RADIO                      ELIMINATIONS   HISTORICAL      PRO FORMA
                         TELECOM CORP.(A)                         (C)         COMBINED    ADJUSTMENTS (D)    PRO FORMA
                         ----------------   ADVANCED RADIO   --------------  -----------  ----------------  -----------
                                             TECHNOLOGIES
                                           CORPORATION (B)
                                           ----------------
                                            (PREDECESSOR)
<S>                      <C>               <C>               <C>             <C>          <C>               <C>
                                                        ASSETS
Current assets:
  Cash and cash
   equivalents.........    $    627,585      $      6,069          --        $   633,654   $  2,350,000(2)
                                                                                              4,950,000(4)
                                                                                              2,220,000(5)  $10,153,654
  Due from ART Corp....         738,680           --         $  (738,680)        --              --             --
  Other current
   assets..............          52,325           --               --             52,325         --              52,325
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
    Total current
     assets............       1,418,590             6,069       (738,680)        685,979      9,520,000      10,205,979
Note receivable from
 ART...................         --              5,000,000     (5,000,000)        --              --             --
Property and equipment,
 net...................       3,579,838             1,723          --          3,581,561         --           3,581,561
Equity investments.....         --                285,000          --            285,000         --             285,000
FCC licenses...........       4,226,821             8,913          --          4,235,734         --           4,235,734
Deferred finance                321,354           457,543          --            778,897       (457,543)(1)
 costs.................                                                                          50,000(4)
                                                                                                175,899(5)      547,253
Equipment and other
 deposits..............         284,012           --               --            284,012         --             284,012
Other assets...........         --                 25,376          --             25,376         --              25,376
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
                           $  9,830,615      $  5,784,624    $(5,738,680)    $ 9,876,559   $  9,288,356     $19,164,915
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
 
                                    LIABILITIES AND STOCKHOLDERS' EQUITY (DEFICIT)
Current liabilities:
  Accounts payable and
   accrued
   liabilities.........    $  3,450,537      $    243,952          --        $ 3,694,489        (66,452)(1) $ 3,628,037
  Due to ART...........         --                738,680    $  (738,680)        --              --             --
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
    Total current
     liabilities.......       3,450,537           982,632       (738,680)      3,694,489        (66,452)      3,628,037
Note payable to ART
 Corp..................       5,000,000                       (5,000,000)
Losses in excess of
 equity investment.....         --                211,543       (211,543)        --              --             --
Convertible notes
 payable...............         --              4,950,000          --          4,950,000   $ (4,950,000)(1)     --
Note payable to EMI....       1,500,000           --               --          1,500,000         --           1,500,000
Bridge notes payable...         --                --               --            --           3,950,000(4)    3,950,000
Equipment financing
 note payable..........         --                --               --            --           1,911,439(5)    1,911,439
Senior discount
 notes.................
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
    Total
     liabilities.......       9,950,537         6,144,175     (5,950,223)     10,144,489        844,987      10,989,476
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
Redeemable preferred
 stock.................         --                 44,930          --             44,930        (44,930)(1)     --
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
Stockholders' equity
 (deficit):
  Preferred stock,
   par.................             488           --               --                488            384(1)
                                                                                                     49(2)          921
  Common stock, par....          15,291                 3          --             15,294          2,823(1)
                                                                                                     (3)(3)      18,114
  Additional paid-in
   capital.............       2,845,372           998,385       (802,002)
                                                                    (340)      3,041,415      4,600,632(1)
                                                                                              3,402,951(2)
                                                                                                      3(3)
                                                                                              1,050,000(4)
                                                                                                484,460(5)
                                                                                              6,795,514 (11  19,374,975
  Accumulated
   deficit.............      (2,981,073)       (1,402,869)     1,013,885      (3,370,057)    (1,053,000)(2)
                                                                                             (6,795,514)(11) (11,218,571)
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
    Total stockholders'
     equity
     (deficit).........        (119,922)         (404,481)       211,543        (312,860)     8,488,299       8,175,439
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
                           $  9,830,615      $  5,784,624    $(5,738,680)    $ 9,876,559   $  9,288,356     $19,164,915
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
                         ----------------  ----------------  --------------  -----------  ----------------  -----------
 
<CAPTION>
 
                             OFFERING         PRO FORMA
                          ADJUSTMENTS (E)    AS ADJUSTED
                         -----------------  -------------
 
<S>                      <C>                <C>
 
Current assets:
  Cash and cash
   equivalents.........      $                $
 
  Due from ART Corp....
  Other current
   assets..............
                                 -----            -----
    Total current
     assets............
Note receivable from
 ART...................
Property and equipment,
 net...................
Equity investments.....
FCC licenses...........
Deferred finance
 costs.................
 
Equipment and other
 deposits..............
Other assets...........
                                 -----            -----
                             $                $
                                 -----            -----
                                 -----            -----
 
Current liabilities:
  Accounts payable and
   accrued
   liabilities.........      $                $
  Due to ART...........
                                 -----            -----
    Total current
     liabilities.......
Note payable to ART
 Corp..................
Losses in excess of
 equity investment.....
Convertible notes
 payable...............
Note payable to EMI....
Bridge notes payable...
Equipment financing
 note payable..........
Senior discount
 notes.................
                                 -----            -----
    Total
     liabilities.......
                                 -----            -----
Redeemable preferred
 stock.................         --               --
                                 -----            -----
Stockholders' equity
 (deficit):
  Preferred stock,
   par.................
 
  Common stock, par....
 
  Additional paid-in
   capital.............
 
  Accumulated
   deficit.............
 
                                 -----            -----
    Total stockholders'
     equity
     (deficit).........
                                 -----            -----
                             $                $
                                 -----            -----
                                 -----            -----
</TABLE>
 
See accompanying notes to pro forma condensed financial statements.
 
                                      F-3
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
             UNAUDITED PRO FORMA CONDENSED STATEMENT OF OPERATIONS
<TABLE>
<CAPTION>
                                                                   YEAR ENDED DECEMBER 31, 1995
                                ---------------------------------------------------------------------------------------------------
                                                           HISTORICAL
                                ----------------------------------------------------------------
                                ADVANCED RADIO
                                   TELECOM                                                           PRO FORMA
                                  CORP. (A)                       ELIMINATIONS (C)    COMBINED    ADJUSTMENTS (D)      PRO FORMA
                                --------------                    ----------------  ------------  ----------------  ---------------
                                                 ADVANCED RADIO
                                                  TECHNOLOGIES
                                                CORPORATION (B)
                                                ----------------
                                                 (PREDECESSOR)
                                                ----------------
<S>                             <C>             <C>               <C>               <C>           <C>               <C>
Operating revenue.............   $      5,793    $     --         $      --         $      5,793   $     --         $       5,793
                                --------------  ----------------  ----------------  ------------  ----------------  ---------------
Expenses:
  General and
   administrative.............      2,711,642           215,315          --            2,926,957          (802,002  10)   2,124,955
  Market development..........        191,693          --                                191,693         1,053,000(9)     1,244,693
  Interest, net...............         83,531            38,455          --              121,986         1,019,145(6)
                                                                                                           673,534(7)
                                                                                                           (73,568 (8)     1,741,097
                                --------------  ----------------  ----------------  ------------  ----------------  ---------------
    Total expenses............      2,986,866           253,770          --            3,240,636         1,870,109      5,110,745
Equity loss in ART............        --              1,013,885      (1,013,885)         --              --               --
                                --------------  ----------------  ----------------  ------------  ----------------  ---------------
      Net loss................   $  2,981,073    $    1,267,655   $   1,013,885     $  3,234,843   $     1,870,109  $   5,104,952
                                --------------  ----------------  ----------------  ------------  ----------------  ---------------
                                --------------  ----------------  ----------------  ------------  ----------------  ---------------
Net loss per share of common
 stock (F)....................   $        .19    $     4,495.23                                                     $
                                --------------  ----------------                                                    ---------------
                                --------------  ----------------                                                    ---------------
Weighted average number of
 shares of Common Stock
 outstanding (F)..............     15,919,596               282
                                --------------  ----------------                                                    ---------------
                                --------------  ----------------                                                    ---------------
 
<CAPTION>
 
                                   OFFERING         PRO FORMA
                                ADJUSTMENTS (E)    AS ADJUSTED
                                ---------------  ---------------
 
<S>                             <C>              <C>
Operating revenue.............   $               $
                                ---------------  ---------------
Expenses:
  General and
   administrative.............
  Market development..........
  Interest, net...............
 
                                ---------------  ---------------
    Total expenses............
Equity loss in ART............
                                ---------------  ---------------
      Net loss................   $               $
                                ---------------  ---------------
                                ---------------  ---------------
Net loss per share of common
 stock (F)....................                   $
                                                 ---------------
                                                 ---------------
Weighted average number of
 shares of Common Stock
 outstanding (F)..............
                                                 ---------------
                                                 ---------------
</TABLE>
 
See accompanying notes to unaudited pro forma condensed financial statements.
 
                                      F-4
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
          NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS
 
(A) Represents the historical amounts of ART as of December 31, 1995 and for the
    period from March 28, 1995 (date of inception) to December 31, 1995.
 
(B) Represents the historical amounts of ART's predecessor, ART Corp. as of  and
    for the year ended December 31, 1995.
 
(C)  Represents eliminations of inter-entity transactions and balances primarily
    consisting of receivables, payables and ART Corp.'s investment in and equity
    in losses of ART.
 
(D) Pro forma adjustments:
 
    (1) Conversion  of the  Advent/ART Securities,  including accrued  interest,
       into   shares  of  ART  Series  E   Preferred  Stock  and  the  resulting
       anti-dilution adjustments for  certain holders  of ART  Common Stock  and
       Serial Preferred Stock.
 
    (2)  Issuance of shares  of ART Series  F Preferred Stock  and the Ameritech
       Warrants to Ameritech  in exchange  for cash  of $2,350,000,  net of  the
       related   financing  costs  of  $150,000   and  the  Ameritech  Strategic
       Distribution Agreement.  The value  ascribed to  the Ameritech  Strategic
       Distribution Agreement totaled $1,053,000.
 
    (3)  Issuance of ART Common Stock to ART Corp. stockholders and cancellation
       of all outstanding ART Corp. Common Stock in connection with the Merger.
 
    (4) Proceeds  from Bridge  Financing received  from stockholders  of ART  of
       $4,950,000  in cash,  net of the  related financing costs  of $50,000, in
       exchange for the Bridge Notes and Bridge Warrants. The value ascribed  to
       the Bridge Warrants totaled $1,050,000.
 
    (5)  Proceeds of $2,220,000 in cash from 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.
 
    (6)  Interest expense from the Bridge  Financing provided by stockholders of
       ART, at the  effective interest  rate after  giving effect  to the  value
       ascribed to the Bridge Warrants.
 
    (7) Interest expense from the Equipment Financing, at the effective interest
       rate after giving effect to the value ascribed to the Indemnity Warrants.
 
    (8)  Elimination  of  interest  expense  from  the  Advent  Notes  that were
       converted into ART Series E Preferred Stock.
 
    (9) Recognition of market development expense for the value ascribed to  the
       Ameritech Strategic Distribution Agreement.
 
    (10)  The  reversal of  a  non-recurring, non-cash  compensation  expense of
       $802,002 recognized in 1995 associated with the release of Escrow  Shares
       in  1995.  Compensation expense  associated with  the termination  of the
       Escrow Shares  arrangement in  1996, totaling  $6,795,514, has  not  been
       reflected  in the unaudited pro  forma condensed statements of operations
       as it is non-recurring.
 
    (11) The increase in paid-in capital and accumulated deficit to reflect  the
       impact of the 1996 release of the Escrow Shares.
 
(E) Offering adjustments:
 
    (1)  Issuance of        shares of  Common Stock offered  in the Common Stock
       Offering based on an assumed initial public offering  price of $      per
       share,  after  deducting  the  estimated  offering  discount  and related
       expenses.
 
    (2) Issuance  of  the  Units  in the  Unit  Offering,  after  deducting  the
       estimated offering discount and related expenses.
 
    (3)  Repayment  of  the  Bridge  Notes out  of  the  net  proceeds  from the
       Offerings.
 
    (4) Conversion of all shares of Serial Preferred Stock into shares of Common
       Stock.
 
    (5) Interest expense on the Notes from the Unit Offering.
 
(F) Pro forma net loss  per share and the weighted  average number of shares  of
    Common  Stock  reflect  (i) the  Merger  of  ART Corp.  into  ART;  (ii) the
    Ameritech investment;  (iii)  the exchange  of  Advent/ ART  Securities  for
    Preferred  Stock  of  ART;  (iv)  the conversion  of  all  shares  of Serial
    Preferred Stock  to  Common  Stock;  and (v)  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 as if they were outstanding as of January 1, 1995.
 
                                      F-5
<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,  12 and  14, 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
 
                                      F-6
<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 Corp. (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 Corp. (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-7
<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)......................   2,711,642
  Market development expenses..................................................     191,693
  Interest expense, net (Notes 4 and 7)........................................      83,531
                                                                                 ----------
    Total expenses.............................................................   2,986,866
                                                                                 ----------
      Net loss.................................................................  $2,981,073
                                                                                 ----------
                                                                                 ----------
Net loss per share.............................................................  $      .19
                                                                                 ----------
                                                                                 ----------
Pro forma net loss per share (unaudited).......................................  $
                                                                                 ----------
                                                                                 ----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-8
<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
 Corp. 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
 Corp. 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
 Corp. 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
Share issuance costs..............
Redemption of Common Stock from
 Landover.........................                     (808)
Investment by ART Corp. 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
 Corp. 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)
Share issuance costs..............     (229,814)                   (229,814)
Redemption of Common Stock from
 Landover.........................   (1,999,192)                 (2,000,000)
Investment by ART Corp. 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-9
<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 Corp.........................................................     (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 Corp...........................    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-10
<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.  ("ART" or  the  "Company"),  formerly named
Advanced Radio Technology Ltd., was incorporated in Delaware as a subsidiary  of
Advanced  Radio Technologies  Corporation ("ART  Corp.") 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.
 
    The  Company was  organized by ART  Corp. 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  ART Corp.,
Landover and  the  Company dated  April  21, 1995  (the  "Purchase  Agreement"),
Landover  was obligated to purchase $7.0  million of securities of ART. Pursuant
to the Purchase Agreement and a stockholders' agreement between the Company, ART
Corp. and their respective  shareholders dated May  8, 1995 (the  "Stockholders'
Agreement"), the Company and ART Corp. will merge once approval from the Federal
Communications Commission (the "FCC") has been granted. On February 2, 1996, the
Company  and ART Corp.  entered into a definitive  merger agreement (the "Merger
Agreement") whereby ART Corp. is to  be merged into the Company (the  "Merger"),
with the Company as the surviving entity. (See Note 2).
 
INITIAL CAPITALIZATION
 
    As  its initial capitalization, the Company 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 the Company then
outstanding. Concurrently, the Company issued 4,420,000 shares of Class A Common
Stock, representing 34% of the total number  of shares of capital stock, to  ART
Corp.  for $340. The number of shares of Class A and Class B Common Stock issued
at the initial capitalization of the Company  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 the Company  and its affiliates (the "Landover Funding
Commitment"). In consideration  for this  $7.0 million  investment, the  Company
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.  The  Company  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. 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 set forth in Notes 8, 12 and 14. The  Company's
funding of its initial operating expenses, working capital needs and contractual
commitments is dependent upon its ability
 
                                      F-11
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION, CONTINUED:
to  raise  additional  financing.  The Company  has  engaged  various investment
bankers to  assist it  in raising  financing through  a public  equity and  debt
offering.  There can be no assurance that  the Company will be successful in its
effort to raise additional financing  through these offerings or, if  available,
that the Company 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.  REORGANIZATION AND PENDING MERGER WITH ART CORP.:
    Under  the terms of the Purchase Agreement, the Company and ART Corp. 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, the
Company and ART Corp. entered into an exclusive 20-year services agreement  (the
"Services Agreement") for the construction, development and operation of systems
in ART Corp.'s markets (see Note 8).
 
    On   February  2,  1996,  the  Company,   ART  Corp.  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 the Company (see
Note 9); (iii)  the exchange  of the  Advent Notes and  one share  of ART  Corp.
Series  A Redeemable Preferred Stock for Series E Preferred Stock of the Company
(see Note  7);  (iv) revision  of  provisions  for election  of  directors;  (v)
amendment  and restatement of the Company's registration rights agreements; (vi)
release of  shares  escrowed  in  connection  with  the  original  Stockholders'
Agreement  (see Note  9); (vii) the  change of  name of the  Company; and (viii)
approval of the Merger Agreement (the "Reorganization").
 
    Upon  completion  of  the  Merger,  subject  only  to  FCC  approval,   each
outstanding  share of the  Company's Common Stock held  by ART Corp. immediately
before the Merger shall  be canceled and  the stockholders of  ART Corp. are  to
receive  an equal number  of shares of  Common Stock of  the Company. The Merger
Agreement also provides that if the Merger  is not consummated by May 13,  1997,
ART Corp. is to surrender all of its shares of the Company's Common Stock to the
Company  and the  terms of the  Services Agreement  are to be  revised to, among
other changes, extend the term of that  agreement to 40 years and provide for  a
proportionate participation by ART Corp.'s stockholders in any dividends paid by
the Company or in any proceeds from the sale of the Company.
 
3.  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.
 
CASH AND CASH EQUIVALENTS
 
    The Company 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.
 
                                      F-12
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
FCC LICENSES
 
    The  Company 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.
 
    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, 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.
 
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.
 
NET LOSS PER SHARE
 
    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.  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.  Accordingly,  an additional
          shares are  reflected in  the  weighted average  number of  shares  of
Common  Stock  outstanding in  computing the  unaudited pro  forma net  loss per
share.
 
                                      F-13
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
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
 
    The  Company  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  the
Company to potential credit risk include the amount due from ART Corp. (Note 12)
and deposits on equipment (Note 8).
 
4.  ACQUISITION OF ASSETS OF EMI:
    On  April 4, 1995, ART  Corp. entered into an  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
Corp. assigned its rights  and obligations under the  EMI purchase agreement  to
the  Company. The FCC subsequently approved the transfer of the EMI licenses and
the Company  acquired  the  EMI  Assets. 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 the Company, with a guarantee by ART Corp., 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  the Company  to fund  a
portion  of the initial payment to EMI. The Company repaid such advance later in
the same month.
 
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.
 
                                      F-14
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
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 CORP.:
    ART Corp., the Company 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  Corp.,  the  Company  and certain
specified affiliates. Pending  the merger of  these entities (see  Note 2),  ART
Corp.  issued promissory notes (the "Advent  Notes") with an aggregate principal
amount of $4,950,000 and one share of ART Corp.'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 Corp. and the Company. 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 of the Company 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
Corp. from Advent were transferred  to the Company 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 Corp., the  Company and Advent  entered
into  an  exchange agreement  under which  the  Advent Notes,  including accrued
interest, and the one share of  ART Corp.'s Series A Redeemable Preferred  Stock
held  by Advent were exchanged for 232,826 shares of Series E Preferred Stock of
the Company, the note was canceled, and the Company became the owner of the  one
share of ART Corp. Series A Redeemable Preferred Stock.
 
8.  COMMITMENTS:
 
EQUIPMENT PURCHASE AGREEMENT
 
    On  August  11, 1995,  the  Company entered  into  an agreement  to purchase
wireless transmission equipment from a vendor. Under the terms of the agreement,
the Company 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. The  Company's initial  non-cancelable
purchase  order amounts to  $13,260,000. Through December  31, 1995, the Company
has purchased  and  paid for  $522,812  of  equipment under  this  contract.  In
addition,  the Company has made a $280,000 deposit under this agreement which is
to be  applied  against future  purchases  after  the Company  has  purchased  a
specified amount of equipment, which is expected to occur in 1996.
 
    The  Company 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 the  Company until alternative
supply sources are established.  The Company does not  manufacture, nor does  it
have  the capability to manufacture, any  of the wireless transmission equipment
necessary to
 
                                      F-15
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
provide its services. Although there are a limited number of 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 comparable terms or on terms more favorable to those  included
in  its current arrangements. 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.
 
SERVICES AGREEMENTS
 
    Under  the Services Agreement, the Company  has agreed to construct, operate
and manage  the FCC  licenses and  related telecommunications  systems that  are
owned  by ART  Corp. or  for which ART  Corp. has  existing services agreements.
Under 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 25% which is to be paid to
ART  Corp. The Services Agreement  is for a period  of 20 years commencing April
21, 1995.
 
    The Company, through its  Services Agreement with ART  Corp., has two  other
exclusive  services agreements, one with ART West,  a joint venture in which ART
Corp. 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 Corp. and the Company, 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  the  Company is  the President  and  a shareholder  of  the
Company's joint venture partner in ART West.
 
    On  April  24, 1996,  the  Company entered  into  a services  agreement with
Telecom One  on terms  substantially  identical to  the  terms of  the  Services
Agreement  between ART  Corp. and the  Company, except that  compensation to the
Company is  equal to  all revenues  generated by  the systems,  after  deducting
certain expenses, less 10% which is paid to Telecom One.
 
EMPLOYMENT AND CONSULTING AGREEMENTS
 
    On  May 8, 1995, the  Company and ART Corp.  jointly entered into consulting
agreements with two executive officers of  the Company, 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
the Company under these consulting agreements through December 31, 1995 amounted
to $166,750.
 
    On  December  16,  1995,  one  of the  executive  officers  of  the Company,
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,  the Company  entered into  an employment  agreement, as
amended February  2, 1996,  with an  officer of  the Company.  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
 
                                      F-16
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
capital stock of the Company (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.
 
    The  Company 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  Corp. 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 Corp. in exchange for cash  and
options  to purchase capital stock  of ART Corp. Pursuant  to a letter agreement
dated July  12, 1995,  ART Corp.  and the  Company paid  SERP $245,000  and  the
shareholders  of ART Corp. granted SERP options  to purchase 10.65 shares of ART
Corp. Common Stock directly from the shareholders of ART Corp. for an  aggregate
consideration of approximately $210,000
 
    As  of December 31, 1995,  ART Corp. and the  Company 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 the  Company (see Note 9)  and the balance  as
part  of the deferred financing  costs recorded by ART  Corp. in connection with
the issuance of the Advent Notes (See Note 7).
 
LEASES
 
    ART and ART Corp.  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
ART  and no amounts have  been charged to ART  Corp. 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
 
                                      F-17
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
9.  STOCKHOLDERS' DEFICIT, CONTINUED:
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 Corp. were
required to place 175 shares of Common Stock in ART Corp. in escrow (the "Escrow
Shares") to be released upon the completion of the pending EMI Asset acquisition
(see Note 4), the Company'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, 63.6 shares of the
Escrow Shares of ART Corp. 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 Corp. 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  Corp.  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. Upon a public  offering of the Company's  Common Stock, all of  the
then  outstanding Serial Preferred  Stock shall be  converted into Common Stock.
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, the
Company 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, the Company 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 the Company  and ART Corp. 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
 
                                      F-18
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
9.  STOCKHOLDERS' DEFICIT, CONTINUED:
the  then outstanding capital stock of the Company. 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  Company Common Stock  directly from Landover  for $0.001  per
share  in  the  event  the  Company does  not  attain  certain  equity valuation
objectives.
 
    On November  13,  1995, the  Advent  Group executed  a  securities  purchase
agreement  with ART Corp. and the Company. As a result of the exchange agreement
dated February 2,  1996, Advent received  232,826 shares of  Series E  Preferred
Stock of the Company, representing a 10% ownership interest (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,  the Company  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.
 
10. STOCK OPTION PLANS:
    On July  22, 1995,  the Company  adopted  the 1995  Stock Option  Plan  (the
"Plan")  that provides for option grants to employees, directors and independent
consultants of the Company. The Company 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 the Company 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 the Company  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  the Company  under the  Plan at  an
option price of $3.94 per share.
 
    On  April  24, 1996,  the Company  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.
 
                                      F-19
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
10. STOCK OPTION PLANS, CONTINUED:
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
the Company'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.  The Company expects  to continue accounting  for
employee stock compensation awards using current accounting requirements.
 
11. INCOME TAXES:
    As of December 31, 1995, the Company 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.
 
12. RELATED PARTY TRANSACTIONS:
    On May  8,  1995,  the Company  and  ART  Corp. entered  into  a  consulting
agreement  with Landover  as a strategic  and financial  consultant. The Company
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 ART Corp.  entered into a management
consulting agreement  with Landover  to  provide strategic  planning,  corporate
development  and general management.  Under the agreement,  the Company will pay
Landover $35,000  per month  for an  initial  one year  term, renewable  by  the
Company  and ART Corp. 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 the Company,
it will be paid a fee by the Company in accordance with industry standards.
 
    Pursuant to the Purchase Agreement, the Company and ART Corp. 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 the Company and  $250,000
has been capitalized as deferred financing costs by ART Corp.
 
    An  executive and shareholder of ART Corp. is a principal in a law firm that
regularly provides legal services to the  Company. During the period from  March
28,  1995  through December  31, 1995,  the Company  incurred $237,538  for such
services.
 
                                      F-20
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
12.
    RELATED PARTY TRANSACTIONS, CONTINUED:
    The Company  has  funded certain  expenses  and investments  of  ART  Corp.,
including ART Corp.'s investment in ART West and payments of financing and other
operating  costs. The amounts funded by  the Company to date totalling $805,803,
offset by accrued interest of $67,123 related  to the note payable to ART  Corp.
(see Note 7) have been included in the amount due from ART Corp.
 
13. FAIR VALUES OF FINANCIAL INSTRUMENTS:
    The  carrying amount and fair values  of the Company'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 the Company for issuance of
debt with similar terms and maturity.
 
14. SUBSEQUENT EVENTS:
 
AMERITECH FINANCING
 
    On February 2, 1996,  the Company 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, the  Company 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  the  Company at  a  price of  $0.001  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 the Company's services within five midwestern states. The Company
incurred fees of $150,000 in connection with this transaction.
 
    Under  the  terms  of  the  securities  purchase  agreement  with Ameritech,
Ameritech is entitled to a put option  to require the Company 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").  The Company  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, the Company 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.
 
                                      F-21
<PAGE>
                          ADVANCED RADIO TELECOM CORP.
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
14. SUBSEQUENT EVENTS, CONTINUED:
RESEARCH AND DEVELOPMENT ARRANGEMENTS
 
    On  January 26,  1996, the Company  entered into a  preliminary agreement to
invest from $700,000 to $1.0 million in  an entity in which an executive of  the
Company  is a director and a shareholder. The preliminary agreement provides for
the  entity  to  perform  research  and  development  of  wireless  transmission
equipment  in  which  the Company  will  receive  a right  of  first  refusal on
production capacity and a license fee in exchange for its investment.
 
    On March 13, 1996, the Company issued a letter of intent to a third party to
provide the Company 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, the Company  entered into a  software license  agreement
(the  "Software License Agreement"). The terms of the Software License Agreement
provide for licensed software and hardware for the Company'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 made  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, the  Company and ART  Corp. 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 the
Company, ART Corp., ART  Corp.'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-22
<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' equity
(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  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
 
                                      F-23
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                                 BALANCE SHEET
                           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 ART (Note 4)...................................................       5,000,000
Equity investment (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 ART (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 notes 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, 7, 8 and 11)................................
 
Stockholders' deficit (Note 9):
  Common stock, $.01 par value; 2,000 shares authorized; 340 and 200 shares issued
   and outstanding..................................................................               3             2
  Additional paid-in capital........................................................         998,385        96,134
  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-24
<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    PERIOD FROM
                                                                                         AUGUST 23,     AUGUST 23,
                                                                   YEARS ENDED          1993 (DATE OF  1993 (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 (Note 11)...........        215,315      261,734        6,594         483,643
  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 ART (Note 5).................      1,013,885                                 1,013,885
                                                            -------------  -----------  -------------  -------------
      Net loss............................................  $   1,267,655  $   128,620    $   6,594     $ 1,402,869
                                                            -------------  -----------  -------------  -------------
                                                            -------------  -----------  -------------  -------------
Net loss per share........................................  $    4,495.23  $    702.84    $   65.94
                                                            -------------  -----------  -------------
                                                            -------------  -----------  -------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-25
<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
                                                                               PAID-IN      DEVELOPMENT
                                                             COMMON STOCK      CAPITAL         STAGE           TOTAL
                                                             -------------  -------------  --------------  --------------
<S>                                                          <C>            <C>            <C>             <C>
Net issuance of 100 shares of common stock for cash........    $       1    $      61,135                  $       61,136
Net loss...................................................                                $       (6,594)         (6,594)
                                                                      --
                                                                            -------------  --------------  --------------
Balance, December 31, 1993.................................            1           61,135          (6,594)         54,542
Issuance of 100 shares of common stock for cash............            1           34,999                          35,000
Net loss...................................................                                      (128,620)       (128,620)
                                                                      --
                                                                            -------------  --------------  --------------
Balance, December 31, 1994.................................            2           96,134        (135,214)        (39,078)
Issuance of 2.5 shares of common stock to ART West.........                        25,000                          25,000
Issuance of 137.5 shares of common stock to existing
 shareholders..............................................            1               (1)
Conversion of note payable and interest to paid-in
 capital...................................................                        75,250                          75,250
Investment in ART 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.................................    $       3    $     998,385  $   (1,402,869) $     (404,481)
                                                                      --
                                                                      --
                                                                            -------------  --------------  --------------
                                                                            -------------  --------------  --------------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-26
<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:
    Depreciation and amortization.........................          54,754          8,281           688           63,723
    Equity loss on investment in ART......................       1,013,885                                     1,013,885
  Changes in operating assets and liabilities:
    Accounts payable and accrued liabilities..............          62,513         (8,282)       19,971           74,202
                                                            --------------  -------------  -------------  --------------
      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 ART..........................        (255,340)                                     (255,340)
  Note receivable from ART................................      (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
  Share 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 ART..............................................         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 ART.................................................  $      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-27
<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  Corp.") was  organized as a
Delaware corporation on August 23,  1993, to provide broadband wireless  digital
telecommunication  services  to  the  domestic  telecommunications  market.  ART
Corp.'s operations to date include the application 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,  ART  Corp.  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. ("ART") was organized by ART Corp.
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  ART  Corp., Landover,  and  ART dated  April  21, 1995,  ("the Purchase
Agreement") Landover was obligated to purchase $7,000,000 of securities of  ART.
Pursuant  to the Purchase  Agreement and a  stockholders' agreement between ART,
ART  Corp.  and   their  respective   shareholders  dated  May   8,  1995   (the
"Stockholders'  Agreement"), ART and ART Corp. will merge once approval from the
FCC has been  granted. On February  2, 1996, ART  and ART Corp.  entered into  a
definitive  merger agreement (the "Merger Agreement") whereby ART Corp. is to be
merged into ART (the "Merger"), with ART as the surviving entity. (See Note 2).
 
INITIAL CAPITALIZATION
 
    ART Corp.  was formed  on August  23, 1993  by two  of its  executives  (the
"Founding  Stockholders") by issuing 100 shares  of common stock in exchange for
$1,136. During November 1993, ART Corp. redeemed 40 shares of common stock  from
the  Founding Stockholders and  through a private placement  issued 40 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 ART Corp. in exchange for 20 shares of common stock and
a $70,000 Promissory  Note. In connection  with the High  Sky II financing,  ART
Corp.  issued an additional aggregate of  80 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 Corp. 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 ART
Corp., 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.  ART Corp.  has a  substantial
working  capital deficit, has incurred operating losses since inception and does
not expect to recognize  material operating revenues  until the commencement  of
its commercial services,
 
                                      F-28
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
1.  FORMATION OF THE COMPANY AND BASIS OF PRESENTATION, CONTINUED:
which  is anticipated to occur in fiscal 1996. ART Corp. 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  7, 8 and  11. ART Corp.'s continued  funding of its  initial
operating  expenses,  working  capital  needs  and  contractual  commitments  is
dependent upon its ability to raise additional financing. ART Corp. 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 ART Corp.
and ART will be successful in their effort to raise additional financing through
these offerings or, if available, that ART Corp. and ART will be able to  obtain
it  on  acceptable terms.  These conditions  raise  substantial doubt  about ART
Corp.'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:
 
INITIAL CAPITALIZATION OF ART
 
    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
ART 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 ART then outstanding. Concurrently, ART Corp. received 4,420,000 shares
of  Class A  common stock,  representing 34%  of the  total number  of shares of
capital stock of ART  then outstanding in  exchange for $340.  All of the  above
references  to shares of common stock of ART  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   and  its  affiliates   (the  "Landover  Funding
Commitment"). In consideration  for this  $7,000,000 investment,  ART 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,  ART agreed  to issue,  for no
consideration, additional shares of Class A Common Stock in number necessary  to
maintain  the 36%  ownership interest in  ART of  the holders of  Class A Common
Stock.
 
    Under the Purchase Agreement, the individual shareholders of ART Corp.  were
required to place 175 shares of Common Stock in ART Corp. in escrow (the "Escrow
Shares") to be released upon the completion of the pending EMI Asset acquisition
(see Note 8), ART'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, 63.6 of the Escrow Shares of ART  Corp.
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 ART, the  effect
of which has been recognized as additional paid-in capital in ART Corp. 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 Corp. 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.
 
                                      F-29
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
2.  PURCHASE AGREEMENT, CONTINUED:
MERGER AGREEMENT
 
    Under the  terms of  the Purchase  Agreement, ART  Corp. and  ART intend  to
operate  both companies as a single enterprise and are committed to merge if and
when permitted by the FCC. Concurrent with the Purchase Agreement, ART Corp. and
ART  entered  into  an  exclusive  20-year  services  agreement  (the  "Services
Agreement")  for the construction,  development and operation  of systems in ART
Corp.'s markets (see Note 6).
 
    On February 2, 1996, ART, ART Corp. 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 ART; (iii) the exchange  of the Advent Notes and one  share
of ART Corp. Series A Redeemable Preferred Stock for Series E Preferred Stock of
ART  (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;
(vii) the change of  name of ART;  and (viii) approval  of the Merger  Agreement
(the "Reorganization").
 
    Upon  completion of the Merger, each outstanding share of ART's Common Stock
held by  ART Corp.  immediately before  the  Merger shall  be canceled  and  the
stockholders  of ART Corp.  are to receive  an equal number  of shares of Common
Stock of ART.  The Merger  Agreement also  provides that  if the  Merger is  not
consummated  by May  13, 1997, ART  Corp. is to  surrender all of  its shares of
ART's Common Stock  to ART and  the terms of  the Services Agreement  are to  be
revised  to, among other changes, extend the  term of that agreement to 40 years
and provide for a proportionate participation by ART Corp.'s stockholders in any
dividends paid by ART or the proceeds from any sale of ART.
 
3.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
 
DEVELOPMENT STAGE ENTERPRISE
 
    ART Corp.  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 are
computed using the straight-line method over the estimated useful lives of three
years.
 
INVESTMENTS
 
    ART Corp. accounts for its  50% interest in the  ART West joint venture  and
its 34% interest in ART under the equity method.
 
FCC LICENSES
 
    ART  Corp.  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.
 
                                      F-30
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
3.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CONTINUED:
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 marketplaces, 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,  technological,
regulatory or other changes.
 
    ART  Corp.'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, ART  Corp. 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
 
    ART  Corp.  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 is computed based on  the loss for the period divided by
the weighted average number  of shares of Common  Stock outstanding during  each
period.
 
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.
 
                                      F-31
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
4.  NOTE RECEIVABLE FROM ART AND CONVERTIBLE NOTES PAYABLE TO ADVENT:
    ART Corp., ART and several entities affiliated with the 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 ART Corp., ART  and
certain specified affiliates. Pending the merger of these entities (see Note 2),
ART  Corp.  issued  promissory  notes (the  "Advent  Notes")  with  an aggregate
principal amount of $4,950,000 and one share of ART Corp.'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 ART Corp.  and ART. 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, ART Corp. 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 ART Corp.
from Advent were transferred to ART in exchange for a note with terms equivalent
to the terms of the Advent Notes. On February 2, 1996, ART Corp., ART and Advent
entered  into  an exchange  agreement under  which  the Advent  Notes, including
accrued interest, and the one share of ART Corp.'s Series A Redeemable Preferred
Stock held by  Advent were exchanged  for 232,826 shares  of Series E  Preferred
Stock  of ART,  and the note  was canceled. As  a result, the  Advent Notes were
canceled and ART became the  owner of the one share  of the Series A  Redeemable
Preferred Stock.
 
5.  EQUITY INVESTMENTS:
 
INVESTMENT IN ART WEST JOINT VENTURE
 
    On  April 4, 1995, ART Corp. 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.  ART  Corp.'s  initial  capital contribution
consisted of $255,000 in cash, FCC  licenses and related assets with a  carrying
value  of approximately  $5,000, and  2.5 shares  of Common  Stock of  ART Corp.
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 2.5 shares of common stock contributed by ART Corp. to ART West. As a result
of  these contributions and distributions, ART  Corp. and Extended share equally
in the partnership interests of ART  West. ART Corp. recorded its investment  in
ART  West in  the amount  of $285,000. The  excess of  ART Corp.'s  share of the
underlying net assets of ART West  over ART Corp.'s recorded investment will  be
amortized over the life of the ART West Systems.
 
    On  October 1, 1994, ART Corp.  entered into an exclusive services agreement
with Extended, whereby ART Corp. 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  Corp. will incur  all costs and  expenses
related   to  construction,  operation   and  management  of   the  systems.  As
compensation, ART Corp. will receive all revenues
 
                                      F-32
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
5.  EQUITY INVESTMENTS, CONTINUED:
generated by the systems after  deducting certain related direct expenses,  less
45%  which is  to be  paid to  ART West.  ART Corp.'s  interest in  this service
agreement was subsequently assigned to ART (Note 6). An officer of ART Corp.  is
also the President and a shareholder of Extended.
 
INVESTMENT IN ART
 
    ART  Corp. acquired 4,420,000 shares of Class  A common stock of ART, or 34%
of the outstanding and issued shares, for  cash of $340 (see Note 2). ART  Corp.
also  recorded $802,002  as an investment  in ART  based upon the  fair value of
Escrow Shares released in 1995 (see Note 2). The excess of ART Corp.'s share  of
the  underlying net assets of  ART over ART Corp.'s  recorded investment will be
amortized over the estimated useful life of ART's FCC licenses.
 
    ART Corp. recognizes its proportionate share of the losses of ART in  excess
of its investment to the extent of its funding and financial commitments. During
1995,  ART Corp. recognized its proportionate share  of ART's loss in the amount
of $1,013,885. Summarized financial information for ART as of December 31,  1995
and  the period 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 Corp...............................................................       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.  ART SERVICES AGREEMENT:
    ART Corp.  entered  into  an exclusive  services  agreement  (the  "Services
Agreement")  with ART, for the construction, operation and management of the FCC
licenses and related telecommunications systems that  are owned by ART Corp.  or
for  which  ART  Corp.  has existing  services  agreements.  Under  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 25% which is  to be paid to ART  Corp. The Services Agreement is
for a period of 20 years.
 
                                      F-33
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
6.  ART SERVICES AGREEMENT, CONTINUED:
    Through this Services  Agreement, ART  Corp. 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,  ART  Corp.  entered  into  an  agreement  with  DCT
Communications, Inc. ("DCT"), in which ART Corp. obtained the option to purchase
certain  FCC licenses (the  "Systems") from DCT  for $500,000 and  shares of ART
Corp.'s 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 that is three years after the FCC issues DCT's first license.
At any time after December 31, 1995, DCT may require that ART Corp. purchase the
Systems for  $50,000,  plus  reimbursement  of  certain  costs  defined  in  the
agreement.
 
SERVICES AGREEMENT
 
    On September 1, 1994, ART Corp. entered into an exclusive services agreement
with  DCT whereby ART  Corp. 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, ART Corp. will incur all costs and expenses
related   to  construction,  operation   and  management  of   the  systems.  As
compensation, ART Corp. 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,  ART Corp. 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 ART Corp. $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,  ART and ART Corp.  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 ART.
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, ART  Corp. entered into an  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,
ART Corp. assigned its  rights and obligations under  the purchase agreement  to
ART.  The FCC  subsequently approved  the transfer of  the EMI  licenses and ART
acquired the EMI Assets.  ART Corp. has  also issued a guarantee  to EMI of  the
obligations of ART under the promissory note.
 
                                      F-34
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
8.  COMMITMENTS, CONTINUED:
TELECOM ONE OPTION
 
    On  May  25, 1995,  ART Corp.  entered  into an  agreement with  TeleCom One
Incorporated ("TeleCom One") whereby ART Corp.  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, ART  Corp.
acquired options to purchase a 49% interest in each of the FCC licenses obtained
by  TeleCom One. The term of the TeleCom  One Agreement is five years. ART Corp.
has not exercised any of its options.
 
EMPLOYMENT AND CONSULTING AGREEMENTS
 
    On May 8, 1995, ART Corp. and ART jointly entered into consulting agreements
with two executive officers  of ART Corp.  and ART, 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  this contract have
been recorded by ART and no amounts have been charged to ART Corp.
 
    On December 16, 1995, one  of the executive officers  of ART Corp. and  ART,
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 ART and no amounts have been charged to ART Corp.
 
    On July 11, 1995, ART Corp. and ART entered into an employment agreement, as
amended January 8, 1996, with  an officer of ART and  ART Corp. 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 ART Common Stock  were awarded to this  officer equivalent to 2.5% of
the outstanding  capital  stock of  ART.  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 ART
and no amounts have been charged to ART Corp.
 
    ART Corp. has 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, ART  Corp. entered into  an agreement  with Southeast Research
Partners ("SERP"), a subsidiary  of Josephthal, Lyons &  Ross, a Florida  broker
dealer,  to procure additional financing for ART  Corp. in exchange for cash and
options to purchase capital stock of  ART. Pursuant to a letter agreement  dated
July  12, 1995, ART Corp. and ART paid SERP $245,000 and the shareholders of ART
Corp. granted SERP options  to purchase 10.65 shares  of ART Corp. Common  Stock
directly  from  the  Founding  Stockholders for  an  aggregate  consideration of
$210,000.
 
    As of December 31,  1995, ART Corp.  and ART 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 ART.
 
9.  COMMON STOCK:
    ART  Corp. is authorized  to issue 2,000  shares of common  stock, par value
$.01 per share. On April  5, 1994, the Board of  Directors authorized a 5 for  1
stock split. Subsequently, on April 5, 1995, the
 
                                      F-35
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
9.  COMMON STOCK, CONTINUED:
Board  of Directors authorized a 1 for  5 reverse stock split and simultaneously
issued an additional 140 shares of common stock. All references to the number of
shares and  per share  amounts of  ART Corp.  common stock  in the  accompanying
financial  statements  have been  restated to  reflect the  stock split  and the
reverse stock split.
 
10. INCOME TAXES:
    As of  December  31,  1995  and  1994, ART  Corp.  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, ART Corp. and  ART entered into a consulting agreement with
Landover as a strategic and financial consultant. ART paid Landover $70,000  for
services  under  this  agreement  during  1995.  The  consulting  agreement  was
terminated on November 13, 1995.
 
    On November 13, 1995, ART Corp. and ART entered into a management consulting
agreement with Landover to provide strategic planning, corporate development and
general management. Under  the agreement, ART  Corp. and ART  will pay  Landover
$35,000  per month for an initial one year  term, renewable by ART Corp. and ART
for two additional one year terms. The aggregate expense recognized by ART under
this agreement  during  1995  amounted  to $70,000.  These  expenses  have  been
recorded  by ART and no portion of such costs have been charged to ART Corp. The
agreement  also  provides  that  in  the  event  Landover  arranges   financing,
acquisitions  or certain other transactions for ART Corp. and ART, Landover will
be paid a fee in accordance with industry standards.
 
    Pursuant to the Purchase Agreement, ART Corp. and ART 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 ART Corp. and the
balance of $141,750 has been charged to paid-in capital of ART.
 
    ART has funded certain expenses and investments of ART Corp., including  ART
Corp.'s  investment in  ART West and  payments of financing  and other operating
costs. The amounts funded by ART  to date totalling $805,803, offset by  accrued
interest  income of $67,123 related to the note receivable from ART (see Note 4)
have been included in the amount due to ART.
 
    In 1994, ART Corp. shared office space with a law firm in which a  principal
of  the law firm was also one of  the Founding Stockholders. ART Corp. 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 ART Corp.  During 1995 and
1994, ART Corp.  incurred fees  of $34,770  and $74,550,  respectively for  such
services.
 
12. FAIR VALUES OF FINANCIAL INSTRUMENTS
    The carrying amounts and fair values of ART Corp.'s financial instruments at
December 31 were as follows:
 
<TABLE>
<CAPTION>
                                                                          1995                      1994
                                                              ----------------------------  --------------------
                                                                CARRYING                    CARRYING     FAIR
                                                                 AMOUNT       FAIR VALUES    AMOUNT     VALUES
                                                              -------------  -------------  ---------  ---------
<S>                                                           <C>            <C>            <C>        <C>
Note receivable from ART....................................  $   5,000,000  $   5,000,000     --         --
Notes payable...............................................      4,950,000      4,950,000  $  70,000  $  70,000
</TABLE>
 
    Note receivable from ART: The carrying amounts reported in the balance sheet
are a reasonable estimate of fair values.
 
                                      F-36
<PAGE>
                    ADVANCED RADIO TECHNOLOGIES CORPORATION
                         (A DEVELOPMENT STAGE COMPANY)
                    NOTES TO FINANCIAL STATEMENTS, CONTINUED
 
12. FAIR VALUES OF FINANCIAL INSTRUMENTS CONTINUED:
    Notes   payable:  The  carrying  amounts   reported  in  the  balance  sheet
approximate fair values based upon  interest rates that are currently  available
to ART Corp. for issuance of similar debt with similar terms and maturities.
 
                                      F-37
<PAGE>
                              [INSIDE BACK COVER]
 
                     [MAP OF U.S. DISPLAYING ADVANCED RADIO
                     TELECOM CORP.'S 38 GHz SERVICE AREAS.]
<PAGE>
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
 
    NO  DEALER, SALESPERSON,  OR OTHER  PERSON HAS  BEEN AUTHORIZED  TO GIVE ANY
INFORMATION OR  MAKE ANY  REPRESENTATIONS, OTHER  THAN THOSE  CONTAINED IN  THIS
PROSPECTUS.  IF GIVEN OR  MADE, SUCH INFORMATION OR  REPRESENTATIONS MUST NOT BE
RELIED UPON AS HAVING BEEN AUTHORIZED  BY THE COMPANY OR THE UNDERWRITERS.  THIS
PROSPECTUS  DOES NOT CONSTITUTE AN OFFER TO  SELL, OR A SOLICITATION OF AN OFFER
TO BUY,  THE SECURITIES  OFFERED HEREBY  IN ANY  JURISDICTION WHERE,  OR TO  ANY
PERSON  TO WHOM, IT IS UNLAWFUL TO  MAKE SUCH OFFER OR SOLICITATION. NEITHER THE
DELIVERY OF  THIS  PROSPECTUS NOR  ANY  SALE  MADE HEREUNDER  SHALL,  UNDER  ANY
CIRCUMSTANCES,  CREATE AN IMPLICATION  THAT THERE HAS  NOT BEEN A  CHANGE IN THE
FACTS SET FORTH IN THIS  PROSPECTUS OR IN THE AFFAIRS  OF THE COMPANY SINCE  THE
DATE HEREOF.
 
                            ------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                   PAGE
                                                                   ----
<S>                                                                <C>
Prospectus Summary...............................................    3
Risk Factors.....................................................   10
The Company......................................................   21
Use of Proceeds..................................................   21
Capitalization...................................................   22
Selected Historical Combined and Pro Forma Financial Data........   23
Management's Discussion and Analysis of Financial Condition and
 Results of Operations...........................................   26
Business.........................................................   30
Management.......................................................   53
Principal Stockholders...........................................   62
Certain Transactions.............................................   64
Description of Units.............................................   69
Description of Notes.............................................   69
Description of Warrants..........................................   96
Description of Capital Stock.....................................  100
Description of Certain Indebtedness..............................  102
Certain Federal Income Tax Considerations........................  103
Underwriting.....................................................  106
Legal Matters....................................................  107
Experts..........................................................  107
Additional Information...........................................  107
Glossary.........................................................  108
Index to Financial Statements....................................  F-1
</TABLE>
 
                            ------------------------
 
    UNTIL        , 1996 (90 DAYS AFTER THE DATE OF THIS PROSPECTUS), ALL DEALERS
EFFECTING   TRANSACTIONS  IN  THE  UNITS,  NOTES  OR  WARRANTS  WHETHER  OR  NOT
PARTICIPATING IN THIS  DISTRIBUTION, MAY  BE REQUIRED TO  DELIVER A  PROSPECTUS.
THIS  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.
 
                          $125,000,000 GROSS PROCEEDS
 
                                     [LOGO]
 
                          ADVANCED RADIO TELECOM CORP.
 
                              UNITS CONSISTING OF
                             SENIOR DISCOUNT NOTES
                                  DUE 2006 AND
                              WARRANTS TO PURCHASE
                                  COMMON STOCK
 
                               -----------------
 
                                   PROSPECTUS
 
                               -----------------
 
                              MERRILL LYNCH & CO.
 
                             MONTGOMERY SECURITIES
 
                               SMITH BARNEY INC.
 
                                        , 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 and the NASD filing fee, all of the amounts in the table  below
are estimated.
 
<TABLE>
<CAPTION>
Securities and Exchange Commission registration fee...................  $
<S>                                                                     <C>        <C>
NASD filing fee.......................................................
Accounting fees and expenses..........................................      *
Printing..............................................................      *
Blue Sky fees and expenses (including counsel fees)...................      *
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 the State of Delaware provides
for indemnification by a corporation of its officers and directors as follows:
 
    "145.   INDEMNIFICATION  OF  OFFICERS,   DIRECTORS,  EMPLOYEES  AND  AGENTS;
INSURANCE.
 
    (a) A corporation  may indemnify  any person  who was or  is a  party or  is
threatened  to be made a  party to any threatened,  pending or completed action,
suit or  proceeding, whether  civil, criminal,  administrative or  investigative
(other  than an action by or  in the right of the  corporation) by reason of the
fact that  he  is  or  was  a  director,  officer,  employee  or  agent  of  the
corporation,  or  is or  was  serving at  the request  of  the corporation  as a
director, officer, employee or agent of another corporation, partnership,  joint
venture,  trust  or  other enterprise,  against  expenses  (including attorneys'
fees), judgments, fines and amounts  paid in settlement actually and  reasonably
incurred  by him in connection with such  action, suit or proceeding if he acted
in good faith and in a manner he reasonably believed to be in or not opposed  to
the  best interests of the corporation, and, with respect to any criminal action
or proceeding, had no reasonable cause to believe his conduct was unlawful.  The
termination  of any action,  suit or proceeding  by judgment, order, settlement,
conviction, or upon a plea of nolo  contendere or its equivalent, shall not,  of
itself,  create a presumption that the person did not act in good faith and in a
manner which  he  reasonably believed  to  be in  or  not opposed  to  the  best
interests  of  the  corporation, and  with  respect  to any  criminal  action or
proceeding, had reasonable cause to believe that his conduct was unlawful.
 
    (b) A corporation  may indemnify  any person  who was or  is a  party or  is
threatened  to be made a party to any threatened, pending or completed action or
suit by or in the right of the corporation to procure a judgment in its favor by
reason of the fact that he is or  was a director, officer, employee or agent  of
the  corporation, or is  or was serving at  the request of  the corporation as a
director, officer, employee or agent of another corporation, partnership,  joint
venture,  trust or other enterprise against expenses (including attorneys' fees)
actually and  reasonably incurred  by  him in  connection  with the  defense  or
settlement  of such action or suit if he acted  in good faith and in a manner he
reasonably believed  to be  in  or not  opposed to  the  best interests  of  the
corporation  and except that no indemnification shall  be made in respect of any
claim, issue or matter as  to which such person shall  have been adjudged to  be
liable  to  the corporation  unless and  only to  the extent  that the  Court of
Chancery or the court in which such  action or suit was brought shall  determine
upon  application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled  to
indemnity  for such  expenses which  the Court of  Chancery or  such other court
shall deem proper.
 
    (c) To  the  extent  that  a  director, officer,  employee  or  agent  of  a
corporation  has been successful  on the merits  or otherwise in  defense of any
action, suit  or proceeding  referred to  in  subsections (a)  and (b)  of  this
section,  or  in defense  of  any claim,  issue or  matter  herein, he  shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by him in connection therewith.
 
    (d) Any  indemnification  under subsections  (a)  and (b)  of  this  section
(unless  ordered by a court) shall be made by the corporation only as authorized
in the specific case upon a determination that indemnification of the  director,
officer, employee or agent is proper in the circumstances because he has met the
applicable  standard of  conduct set  forth in subsections  (a) and  (b) of this
section. Such determination shall  be made (1)  by the board  of directors by  a
majority  vote of a quorum consisting of  directors who were not parties to such
action, suit or proceeding, or (2) if  such a quorum is not obtainable, or  even
if  obtainable, a quorum  of disinterested directors  so directs, by independent
legal counsel in a written opinion, or (3) by the stockholders.
 
    (e) Expenses (including attorneys' fees) incurred by an officer or  director
in  defending any civil, criminal,  administrative or investigative action, suit
or proceeding may be paid by the corporation in advance of the final disposition
of such action,  suit or  proceeding upon  receipt of  an undertaking  by or  on
behalf  of such director or officer to  repay such amount if it shall ultimately
be determined that he is
 
                                      II-2
<PAGE>
not entitled to be indemnified by the corporation as authorized in this section.
Such expenses (including attorneys' fees) incurred by other employees and agents
may be so paid upon such terms and conditions, if any, as the board of directors
deems appropriate.
 
    (f)  The indemnification and advancement of expenses provided by, or granted
pursuant to, the other subsections of this section shall not be deemed exclusive
of any other  rights to which  those seeking indemnification  or advancement  of
expenses  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.
 
    (g) A corporation  shall have power  to purchase and  maintain insurance  on
behalf of any person who is or was a director, officer, employee or agent of the
corporation,  or  is or  was  serving at  the request  of  the corporation  as a
director, officer, employee or agent of another corporation, partnership,  joint
venture,  trust or other  enterprise against any  liability asserted against him
and incurred by him in any such capacity, or arising out of his status as  such,
whether  or not the  corporation would have  the power to  indemnify him against
such liability under this section.
 
    [paragraphs (h), (i), and (j) not included ]"
 
    Reference is made to Paragraph 9 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.
 
    CLASS A AND B COMMON STOCK PRIVATE PLACEMENT
 
    In   April  1995,  ART  Corp.  and  Landover  Holdings  Corporation  ("LHC")
subscribed 340,000 shares of Class A Common Stock and 640,000 shares of Class  B
Common  Stock of the  Company, respectively, for $0.001  per share, which, after
giving effect to anti-dilution adjustments and the February 1996 Reorganization,
currently  are   equivalent  to   10,013,855   shares  and   7,788,170   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 Class A Common Stock of the Company at the price
of $0.001 per share, which, after giving effect to anti-dilution adjustments and
the February 1996 Reorganization currently are equivalent 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.
 
                                      II-3
<PAGE>
    PREFERRED STOCK PRIVATE PLACEMENTS
 
    Between May 8,  1995 and November  13, 1995,  the LHC Stock  was diluted  by
purchases  of series of  Company 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 $3,500,000 of Preferred Stock matching other investors under the
LHC Purchase Agreement,  purchased 405,880  shares of 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
Series  A Preferred  Stock from  E2-2 for $1,050,000  pursuant to  an option. E2
purchased an aggregate  of 105,823  shares of  Series B  Preferred Stock  (which
converts into 1,375,699 shares of Common Stock upon completion of this offering)
for  an aggregate of $842,000. E1 purchased  13,797 shares of 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  Series B
Preferred Stock  (which  converts  into  115,128 shares  of  Common  Stock  upon
completion  of this offering) for an aggregate of $          . E2-3 purchased an
aggregate of  7,363 shares  of 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,  the Company sold 61,640  shares of 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. The  Company simultaneously
redeemed 801,320 shares of Common Stock  from LHC for $2,000,000. In  connection
with  the  February  1996 Reorganization  described  below, LHC  granted  to the
holders of Series  D Preferred  Stock a  contingent option  to purchase  400,634
shares  of 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 Corp's
Series A Redeemable Preferred Stock for a purchase price of $50,000 and (ii) ART
Corp.'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 Series E Preferred Stock, $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 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, the Company  entered
into  the Ameritech Strategic Distribution Agreement and in connection therewith
granted to Ameritech a  five-year warrant to purchase  877,136 shares of  Common
Stock  of the Company exercisable at a  price of $.001 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,  the Company  issued in  a private  placement  $5,000,000
principal  amount 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  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-4
<PAGE>
EQUIPMENT FINANCING
 
    On  April  29, 1996,  CRA,  Inc. ("CRA")  entered  into a  secured equipment
financing with the  Company (the  "Equipment Financing") for  the purchase  from
P-Com  of 38 GHz radio equipment. To  evidence its obligations and the Equipment
Financing, the Company  issued in  favor of  CRA a  $2,445,000 promissory  note,
payable  in twenty  four monthly  installments of  $92,694 with  a final payment
equal to $642,305  due April 29,  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.
 
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>
<CAPTION>
      1-1  Underwriting Agreement (to be filed by amendment).
<C>        <S>                                                                              <C>
      2-1  Second Amended and Restated Certificate of Incorporation and Restated and
            Amended By-laws of Registrant.(1)
      4-1  Specimen of Common Stock Certificate (to be filed by amendment).
      4-2  (a) Indenture (to be filed by amendment).
           (b) Specimen of Senior Discount Note (See Exhibit 4-2(a)).
      5-1  Opinion and Consent of Hahn & Hessen LLP, counsel for the Registrant, with
            respect to the Registrant's Common Stock and the Notes (to be filed by
            amendment).
      9-1  (a) Voting Trust Agreement (to be filed by amendment).
           (b) Form of Trustee Indemnification Agreement (to be filed by amendment).
     10-1  Employment and Consulting Agreements.
           (a) Vernon L. Fotheringham, dated December 16, 1995.(1)
           (b) Steven D. Comrie, dated February 2, 1996.(1)
           (c) W. Theodore Pierson Jr., dated May 8, 1995 and effective January 1,
            1995.(1)
           (d) I. Don Brown, dated February 16, 1996.(1)
           (e) Charles Menatti, dated March 8, 1996.(1)
           (f) James D. Miller, dated February 1, 1996.(1)
           (g) Thomas A. Grina, dated April 26, 1996.
     10-2  Amended and Restated Certificate of Incorporation and By-laws of ART Corp.(1)
     10-3  Form of Director Indemnification Agreement.(1)
     10-4  (a) Registrant's 1995 Stock Option Plan, as amended.(1)
           (b) Form of Stock Option Agreement.(1)
     10-5  (a) Registrant's 1996 Non-Employee Directors Automatic Stock Option Plan.
           (b) Form of Stock Option Agreement.
     10-6  Stock Option Agreements.
           (a) Comrie Non-Qualified Stock Option Agreement.(1)
           (b) Comrie Incentive Stock Option Agreement.(1)
     10-7  Management Consulting Agreement with Landover Holdings Corporation, dated
            November 13, 1995.(1)
     10-8  (a) ART West Joint Venture Agreement dated April 4, 1995, with Extended
               Communications, Inc.(1)
           (b) Put/Call Agreement dated October 1, 1994, with Extended Communications,
               Inc.(1)
           (c) Services Agreement dated October 1, 1994, with Extended Communications,
               Inc.(1)
</TABLE>
 
                                      II-5
<PAGE>
<TABLE>
<C>        <S>                                                                              <C>
           (d) Amendment dated April 4, 1995 to the Put/Call Agreement dated October 1,
               1994, with Extended Communications, Inc.(1)
     10-9  (a) Put/Call Agreement dated September 1, 1994 with DCT Communications, Inc.(1)
           (b) Services Agreement dated September 1, 1994 with DCT Communications, Inc.(1)
           (c) Terms Sheet dated April 26, 1996 with DCT.(1)
    10-10  (a) Asset Purchase Agreement dated April 4, 1995 with EMI Communications
               Corporation.(1)
           (b) $1,500,000 Nonnegotiable and Nontransferable Promissory Note(1)
           (c) Maintenance Agreement dated November 14, 1995 with EMI Communications
               Corporation.(1)
           (d) Agreement dated November 14, 1995 with EMI Communications Corporations.(1)
    10-11  38 GHz Radio Links Purchase Agreement dated August 11, 1995 with P-Com, Inc.
            (Confidential treatment requested for certain terms).(1)
    10-12  (a) Agreement dated May 25, 1995 with Telecom One (Confidential treatment
               requested for certain terms).(1)
           (b) Services Agreement dated April 24, 1996 with Telecom One.(1)
    10-13  Letter of Intent dated November 20, 1995 with GTE.(1)
    10-14  Software License Agreement dated March 29, 1996 with GTE.(1)
    10-15  Agreement dated July 12, 1995 with Southeast Research Partners, Inc.(1)
    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.(1)
    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.(1)
    10-18  (a) Purchase Agreement dated April 21, 1995 with Landover Holdings
               Corporation.(1)
           (b) Letter Agreement dated May 8, 1995 with the Demetrees, ART Corp., and
               Landover Holdings Corporation.(1)
           (c) Letter Agreement dated November 13, 1995 with ART Corp., E2-2 Holdings,
            L.P. and the Demetrees.(1)
    10-19  Restated and Amended Stockholders' Agreement dated February 2, 1996 with ART
            Corp. and the stockholders of each of ART Corp. and the Company.(1)
    10-20  Restated and Amended Registration Rights Agreement dated February 2, 1996 with
            ART Corp. and the stockholders of each of ART Corp. and the Company.(1)
    10-21  Services Agreement dated May 8, 1995 with ART Corp.(1)
    10-22  Option Agreement dated February 2, 1996 with ART Corp.(1)
    10-23  (a) Securities Purchase Agreement dated November 13, 1995 with ART Corp.,
               Vernon Fotheringham, W. Theodore Pierson, Jr., the stockholders of the
               Company named therein and the Advent Partnerships.(1)
           (b) Exchange Agreement dated February 2, 1996 with ART Corp. and the Advent
               Partnerships.(1)
    10-24  (a) Securities Purchase Agreement dated February 2, 1996 with ART Corp. and
               Ameritech Development Corporation ("Ameritech"), including letter of
               intent.(1)
           (b) Warrant issued on February 2, 1996 to Ameritech.(1)
           (c) Put/Call Agreement dated February 2, 1996 with Ameritech.(1)
    10-25  Strategic Distribution Agreement dated April 29, 1996 with Ameritech.(1)
    10-26  Merger Agreement and Plan of Reorganization dated February 2, 1996 between the
            Company and ART Corp.(1)
    10-27  (a) $2,445,000 Promissory Note in favor of CRA, Inc. ("CRA")(1)
           (b) Security Agreement with CRA(1)
           (c) Indemnity Agreement(1)
</TABLE>
 
                                      II-6
<PAGE>
<TABLE>
<C>        <S>                                                                              <C>
           (d) Form of Indemnity Warrant.(1)
    10-28  Memorandum of Terms of Development and Procurement Agreement with American
            Wireless with Extension Agreement dated April 25, 1996.(1)
    10-29  (a) Purchase Agreement dated April 26, 1996 with Harris Corporation Farinon
            Division ("Harris") (confidential treatment requested for certain terms).
           (b) PCS Marketing Agreement dated April 26, 1996 with Harris (confidential
            treatment requested for certain terms).
       11  Computation of Net Loss Per Share of Common Stock.
       12  Computation of Ratio of Earnings to Fixed Charges.
       21  Subsidiaries of the Registrant.(1)
    23(a)  Consent of the Registrant's Independent Accountant.
    23(b)  Consent of the Registrant's Counsel will be contained in the Opinion of Counsel
            (to be filed by amendment).
</TABLE>
 
- ------------------------
(1)  Filed with the Registration Statement on  Form S-1 of the Company dated May
2, 1996 (SEC Reg. No. 333-4388).
 
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;
 
                                      II-7
<PAGE>
           (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-8
<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 May 14, 1996.
 
                                          Advanced Radio Telecom Corp.
 
                                          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              May 14, 1996
                Vernon L. Fotheringham                   Officer and Director
 
                      /s/ STEVEN D. COMRIE
     -------------------------------------------        President, Chief Operating             May 14, 1996
                   Steven D. Comrie                      Officer and Director
 
                    /s/ MARK T. MARINKOVICH
     -------------------------------------------        Vice President                         May 14, 1996
                 Mark T. Marinkovich
 
                       /s/ THOMAS A. GRINA
     -------------------------------------------        Executive Vice President               May 14, 1996
                   Thomas A. Grina                       and Chief Financial Officer
 
                     /s/ J. C. DEMETREE, JR.
     -------------------------------------------        Director                               May 14, 1996
                 J. C. Demetree, Jr.
 
                      /s/ MARK C. DEMETREE
     -------------------------------------------        Director                               May 14, 1996
                   Mark C. Demetree
 
                       /s/ MATTHEW C. GOVE
     -------------------------------------------        Director                               May 14, 1996
                   Matthew C. Gove
 
                      /s/ ANDREW I. FILLAT
     -------------------------------------------        Director                               May 14, 1996
                   Andrew I. Fillat
 
                  /s/ LAURENCE S. ZIMMERMAN
     -------------------------------------------        Director                               May 14, 1996
                Laurence S. Zimmerman
</TABLE>
 
                                      II-9
<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
Steven D. Comrie, 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              May 14, 1996
                Vernon L. Fotheringham                   Officer and Director
 
                      /s/ STEVEN D. COMRIE
     -------------------------------------------        President, Chief Operating             May 14, 1996
                   Steven D. Comrie                      Officer and Director
 
                  /s/ LAURENCE S. ZIMMERMAN
     -------------------------------------------        Director                               May 14, 1996
                Laurence S. Zimmerman
 
                     /s/ J. C. DEMETREE, JR.
     -------------------------------------------        Director                               May 14, 1996
                 J. C. Demetree, Jr.
 
                      /s/ MARK C. DEMETREE
     -------------------------------------------        Director                               May 14, 1996
                   Mark C. Demetree
 
                       /s/ MATTHEW C. GOVE
     -------------------------------------------        Director                               May 14, 1996
                   Matthew C. Gove
 
                      /s/ ANDREW I. FILLAT
     -------------------------------------------        Director                               May 14, 1996
                   Andrew I. Fillat
</TABLE>
 
                                     II-10
<PAGE>
                                                                      EXHIBIT 11
 
                          ADVANCED RADIO TELECOM CORP.
               COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
 
<TABLE>
<CAPTION>
                                                            MARCH 28, 1995
                                                               (DATE OF              YEAR ENDED DECEMBER 31, 1995
                                                              INCEPTION)      ------------------------------------------
                                                                  TO           HISTORICAL                    PRO FORMA
                                                          DECEMBER 31, 1995     COMBINED       PRO FORMA    AS ADJUSTED
                                                          ------------------  -------------  -------------  ------------
<S>                                                       <C>                 <C>            <C>            <C>
Net loss before fixed charges...........................    $    2,893,238    $   3,041,430  $   3,292,428   $
 
Deduct:
  Interest expense......................................            87,835          186,297      1,674,002
  Amortization of deferred financing charges............          --                  7,116        138,522
                                                          ------------------  -------------  -------------  ------------
 
Net loss................................................    $    2,981,073    $   3,234,843  $   5,104,952   $
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
 
Fixed charges:
  Interest expense......................................    $       87,835    $     186,297  $   1,674,002
  Amortization of deferred financing charges............          --                  7,116        138,522
                                                          ------------------  -------------  -------------  ------------
Fixed charges...........................................    $       87,835    $     193,413  $   1,812,524   $
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
 
Deficiency of net losses to cover fixed charges.........    $    2,981,073    $   3,234,843  $   5,104,952
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
</TABLE>
 
                       ADVANCED RADIO TECHNOLOGIES CORP.
                COMPUTATION OF RATIO OF LOSSES TO FIXED CHARGES
 
<TABLE>
<CAPTION>
                                                             AUGUST 23, 1993
                                                           (DATE OF INCEPTION)
                                                                   TO               YEAR ENDED          YEAR ENDED
                                                            DECEMBER 31, 1993   DECEMBER 31, 1994   DECEMBER 31, 1995
                                                           -------------------  ------------------  ------------------
<S>                                                        <C>                  <C>                 <C>
Net loss before fixed charges............................       $   6,594          $    124,245       $    1,162,077
 
Deduct:
  Interest expense.......................................          --                     4,375               98,462
  Amortization of deferred financing charges.............          --                   --                     7,116
                                                                  -------            ----------     ------------------
 
Net loss.................................................       $   6,594          $    128,620       $    1,267,655
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
 
Fixed charges:
  Interest expense.......................................       $  --              $      4,375       $       98,462
  Amortization of deferred financing charges.............                                                      7,116
                                                                  -------            ----------     ------------------
Total fixed charges......................................       $  --              $      4,375       $      105,578
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
 
Deficiency of loss to cover fixed charges................       $   6,594          $    128,620       $    1,267,655
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
</TABLE>
 
<PAGE>
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
<C>            <S>                                                                                        <C>
        1-1    Underwriting Agreement (to be filed by amendment)........................................
        2-1    Second Amended and Restated Certificate of Incorporation and Restated and Amended By-laws
                of Registrant.(1).......................................................................
        4-1    Specimen of Common Stock Certificate (to be filed by amendment)..........................
        4-2    (a) Indenture (to be filed by amendment).................................................
               (b) Specimen of Senior Discount Note (See Exhibit 4-2(a))................................
        5-1    Opinion and Consent of Hahn & Hessen LLP, counsel for the Registrant, with respect to the
                Registrant's Common Stock and the Notes (to be filed by amendment)......................
        9-1    (a) Voting Trust Agreement (to be filed by amendment)....................................
               (b) Form of Trustee Indemnification Agreement (to be filed by amendment).................
       10-1    Employment and Consulting Agreements.....................................................
               (a) Vernon L. Fotheringham, dated December 16, 1995.(1)..................................
               (b) Steven D. Comrie, dated February 2, 1996.(1).........................................
               (c) W. Theodore Pierson Jr., dated May 8, 1995 and effective January 1, 1995.(1).........
               (d) I. Don Brown, dated February 16, 1996.(1)............................................
               (e) Charles Menatti, dated March 8, 1996.(1).............................................
               (f) James D. Miller, dated February 1, 1996.(1)..........................................
               (g) Thomas A. Grina, dated April 26, 1996................................................
       10-2    Amended and Restated Certificate of Incorporation and By-laws of ART Corp.(1)............
       10-3    Form of Director Indemnification Agreement.(1)...........................................
       10-4    (a) Registrant's 1995 Stock Option Plan, as amended.(1)..................................
               (b) Form of Stock Option Agreement.(1)...................................................
       10-5    (a) Registrant's 1996 Non-Employee Directors Automatic Stock Option Plan.................
               (b) Form of Stock Option Agreement.......................................................
       10-6    Stock Option Agreements..................................................................
               (a) Comrie Non-Qualified Stock Option Agreement.(1)......................................
               (b) Comrie Incentive Stock Option Agreement.(1)..........................................
       10-7    Management Consulting Agreement with Landover Holdings Corporation, dated November 13,
                1995.(1)................................................................................
       10-8    (a) ART West Joint Venture Agreement dated April 4, 1995, with Extended Communications,
                   Inc.(1)..............................................................................
               (b) Put/Call Agreement dated October 1, 1994, with Extended Communications, Inc.(1)......
               (c) Services Agreement dated October 1, 1994, with Extended Communications, Inc.(1)......
               (d) Amendment dated April 4, 1995 to the Put/Call Agreement dated October 1, 1994, with
                   Extended Communications, Inc.(1).....................................................
       10-9    (a) Put/Call Agreement dated September 1, 1994 with DCT Communications, Inc.(1)..........
               (b) Services Agreement dated September 1, 1994 with DCT Communications, Inc.(1)..........
               (c) Terms Sheet dated April 26, 1996 with DCT.(1)........................................
      10-10    (a) Asset Purchase Agreement dated April 4, 1995 with EMI Communications
                   Corporation.(1)......................................................................
               (b) $1,500,000 Nonnegotiable and Nontransferable Promissory Note(1)......................
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
               (c) Maintenance Agreement dated November 14, 1995 with EMI Communications
                   Corporation.(1)......................................................................
<C>            <S>                                                                                        <C>
               (d) Agreement dated November 14, 1995 with EMI Communications Corporations.(1)...........
      10-11    38 GHz Radio Links Purchase Agreement dated August 11, 1995 with P-Com, Inc.
                (Confidential treatment requested for certain terms).(1)................................
      10-12    (a) Agreement dated May 25, 1995 with Telecom One (Confidential treatment requested for
                   certain terms).(1)...................................................................
               (b) Services Agreement dated April 24, 1996 with Telecom One.(1).........................
      10-13    Letter of Intent dated November 20, 1995 with GTE.(1)....................................
      10-14    Software License Agreement dated March 29, 1996 with GTE.(1).............................
      10-15    Agreement dated July 12, 1995 with Southeast Research Partners, Inc.(1)..................
      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.(1)..............................................................................
      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.(1)........................................................
      10-18    (a) Purchase Agreement dated April 21, 1995 with Landover Holdings Corporation.(1).......
               (b) Letter Agreement dated May 8, 1995 with the Demetrees, ART Corp., and Landover
                   Holdings Corporation.(1).............................................................
               (c) Letter Agreement dated November 13, 1995 with ART Corp., E2-2 Holdings, L.P. and the
                   Demetrees.(1)........................................................................
      10-19    Restated and Amended Stockholders' Agreement dated February 2, 1996 with ART Corp. and
                the stockholders of each of ART Corp. and the Company.(1)...............................
      10-20    Restated and Amended Registration Rights Agreement dated February 2, 1996 with ART Corp.
                and the stockholders of each of ART Corp. and the Company.(1)...........................
      10-21    Services Agreement dated May 8, 1995 with ART Corp.(1)...................................
      10-22    Option Agreement dated February 2, 1996 with ART Corp.(1)................................
      10-23    (a) Securities Purchase Agreement dated November 13, 1995 with ART Corp., Vernon
                   Fotheringham, W. Theodore Pierson, Jr., the stockholders of the Company named therein
                   and the Advent Partnerships.(1)......................................................
               (b) Exchange Agreement dated February 2, 1996 with ART Corp. and the Advent
                   Partnerships.(1).....................................................................
      10-24    (a) Securities Purchase Agreement dated February 2, 1996 with ART Corp. and Ameritech
                   Development Corporation ("Ameritech"), including letter of intent.(1)................
               (b) Warrant issued on February 2, 1996 to Ameritech.(1)..................................
               (c) Put/Call Agreement dated February 2, 1996 with Ameritech.(1).........................
      10-25    Strategic Distribution Agreement dated April 29, 1996 with Ameritech.(1).................
      10-26    Merger Agreement and Plan of Reorganization dated February 2, 1996 between the Company
                and ART Corp.(1)........................................................................
      10-27    (a) $2,445,000 Promissory Note in favor of CRA, Inc. ("CRA")(1)..........................
               (b) Security Agreement with CRA(1).......................................................
               (c) Indemnity Agreement(1)...............................................................
               (d) Form of Indemnity Warrant.(1)........................................................
      10-28    Memorandum of Terms of Development and Procurement Agreement with American Wireless with
                Extension Agreement dated April 25, 1996.(1)............................................
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
      10-29    (a) Purchase Agreement dated April 26, 1996 with Harris Corporation Farinon Division
                ("Harris") (confidential treatment requested for certain terms).........................
<C>            <S>                                                                                        <C>
               (b) PCS Marketing Agreement dated April 26, 1996 with Harris (confidential treatment
                requested for certain terms)............................................................
         11    Computation of Net Loss Per Share of Common Stock........................................
         12    Computation of Ratio of Earnings to Fixed Charges........................................
         21    Subsidiaries of the Registrant.(1).......................................................
       23(a)   Consent of the Registrant's Independent Accountant.......................................
       23(b)   Consent of the Registrant's Counsel will be contained in the Opinion of Counsel (to be
                filed by amendment).....................................................................
</TABLE>
 
- ------------------------
(1)  Filed with the Registration Statement on  Form S-1 of the Company dated May
2, 1996 (SEC Reg. No. 333-4388).
<PAGE>
                                                                      EXHIBIT 12
 
                          ADVANCED RADIO TELECOM CORP.
               COMPUTATION OF NET LOSS PER SHARE OF COMMON STOCK
  FOR THE PERIOD FROM MARCH 28, 1995 (DATE OF INCEPTION) TO DECEMBER 31, 1995
                                  (UNAUDITED)
 
<TABLE>
<S>                                                                           <C>
Net loss applicable to Common Stock.........................................  $  2,981,073
                                                                              --------------
                                                                              --------------
  Shares:
    Weighted average number of shares of Common Stock outstanding at
     December 31, 1995......................................................    15,919,596(1)
                                                                              --------------
                                                                              --------------
Net loss per share of Common Stock..........................................  $        .19
                                                                              --------------
                                                                              --------------
 
Pro Forma:
  Shares:
    Weighted average number of shares of Common Stock outstanding at
     December 31, 1995 for primary computation..............................
    Issuances of shares of Serial Preferred Stock, including anti-dilutive
     shares, subsequent to December 31, 1995 as converted into shares of
     Common Stock...........................................................
    Issuance of anti-dilutive shares of Common Stock subsequent to December
     31, 1995...............................................................
    Conversion of shares of Serial Preferred Stock outstanding at December
     31, 1995 into shares of Common Stock...................................
    Options and warrants issued and outstanding at December 31, 1995 and
     issued subsequent to December 31, 1995.................................
  Pro forma weighted average number of shares of Common Stock...............              (2)
                                                                              --------------
                                                                              --------------
Pro forma net loss per share of Common Stock................................  $
                                                                              --------------
                                                                              --------------
 
Pro Forma As Adjusted
  Shares:
    Pro forma weighted average number of shares of Common Stock.............
    Common Stock and warrants issued in connection with the Offerings.......
  Pro forma as adjusted weighted average number of shares of Common Stock...              (2)
                                                                              --------------
                                                                              --------------
Pro forma as adjusted net loss per share of Common Stock....................  $
                                                                              --------------
                                                                              --------------
</TABLE>
 
(1)  The weighted average  number of shares  of Common Stock  exclude all common
    stock equivalents which are anti-dilutive.
 
(2) 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
    must 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 $     per share.
<PAGE>
                                                                   EXHIBIT 23(A)
 
                       CONSENT OF INDEPENDENT ACCOUNTANTS
 
    We  consent to the inclusion  in this registration statement  on Form S-1 of
our reports dated April 26, 1996, on  our audits 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 and 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.  We also  consent  to the  reference to  our  firm under  the caption
"Experts."
 
                                          COOPERS & LYBRAND L.L.P.
 
New York, New York
May 13, 1996
<PAGE>
                                                      REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
 
                             WASHINGTON, D.C. 20549
 
                            ------------------------
 
                                    EXHIBITS
                                   FILED WITH
 
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                            ------------------------
 
                          ADVANCED RADIO TELECOM CORP.
 
               (Exact name of issuer as specified in its charter)
 
                                    VOLUME 1
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                                      REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
 
                             WASHINGTON, D.C. 20549
 
                            ------------------------
 
                                    EXHIBITS
                                   FILED WITH
 
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                            ------------------------
 
                          ADVANCED RADIO TELECOM CORP.
 
               (Exact name of issuer as specified in its charter)
 
                                    VOLUME 2
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                                      REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
 
                             WASHINGTON, D.C. 20549
 
                            ------------------------
 
                                  CONFIDENTIAL
                                    EXHIBITS
 
                                   FILED WITH
 
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                            ------------------------
 
                          ADVANCED RADIO TELECOM CORP.
 
               (Exact name of issuer as specified in its charter)
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                          SELECTED DATA TRANSFER RATES
 
<TABLE>
<S>                <C>        <C>
Dial Up Line            28.8  Kbps (v.34 modem)
ISDN                     128  Kbps
DS-1                   1.544  Mbps
DS-3                      45  Mbps
</TABLE>
 
<PAGE>
        38 GHZ TECHNOLOGY PROVIDES SUPERIOR BANDWIDTH PER CHANNEL WHICH
                ALLOWS SIGNIFICANTLY FASTER DATA TRANSFER RATES
<PAGE>

HARRIS CORPORATION
FARINON DIVISION

PURCHASE AGREEMENT



This Agreement is entered into this 26th day of April, 1996, by and
between  Advanced Radio Telecom Corporation, a Delaware corporation with offices
located at 500 108th Avenue NE, Suite 2600, Bellevue, WA 98006 ("ART" or
"Customer"), and Harris Corporation, Farinon Division, a Delaware corporation,
with offices located at 330 Twin Dolphin Drive, Redwood Shores, CA 94065
("Harris").

Whereas, Customer desires to purchase microwave transmission equipment, software
and services ("Products") , and

Whereas, Harris is willing to sell such Products to Customer upon the terms and
conditions as set forth herein and the various annexes attached hereto and
incorporated into this document.

Now, Therefore, in consideration of the mutual
covenants set forth below, ART and Harris, intending to be legally bound, 
hereby agree as follows:

1.  EFFECTIVE DATE; RELATED PCS MARKETING AGREEMENT; FINANCING COMMITMENT.

The Effective Date of this Agreement shall be the date of execution by the
parties, provided, however, that the rights and obligations of the parties
hereunder shall not become effective unless and until the parties have executed
a definitive marketing agreement ("PCS Marketing Agreement") for 38 GHz services
as contemplated by Version 5 of a Letter of Intent executed by ART and Harris
and dated February 22, 1996.

2.  SCOPE

Harris will furnish Products for Customer in accordance with the individual
Purchase Orders issued by Customer from time to time during the Term of this
Agreement based upon the prices provided in Annex A hereto.  The Products will
be provided in conformity with the terms, conditions, specifications and other
requirements of this Agreement and each Purchase Order will be governed by the
terms and conditions stated herein. 

3.  PRICES/TAXES

All prices are exclusive of shipping and insurance charges which shall be billed
separately. All prices are exclusive of all sales, use, excise, and other taxes,
duties or charges.  Unless evidence of tax exempt status is provided by
Customer, Customer shall pay, or upon receipt of invoice from Harris, shall
reimburse Harris for all such taxes or charges levied or imposed on Customer, or
required to be collected by Harris, resulting from this transaction or any part
thereof.

All prices are FOB Harris' Factory. Unless instructed otherwise, Harris will
arrange for insurance and standard commercial shipping, the costs of which will
be invoiced to the Customer.


                                                                             1
<PAGE>

Responsibilities regarding the export of items delivered under this Agreement 
are detailed in Articles 8.  Prior to delivery, Harris reserves the right to 
make substitutions, modifications and improvements to the equipment and/or 
software ordered, provided that such substitutions, modifications or 
improvements shall not materially affect performance in the application 
originally agreed to with Customer.

4.   PURCHASE FORECAST GOALS.  

ART shall provide Harris with MicroStar and MicroStar Plus purchase forecasts,
which shall serve as a baseline  to establish pricing levels outlined in Annex
A.  ART's initial forecast is attached hereto as ANNEX B. Unless otherwise
agreed by the parties, future forecasts shall be provided by ART on  a quarterly
basis.

5.   PAYMENT/FINANCING

Payment terms shall be determined on a per order basis and are subject to credit
review by Harris.  

Late payments shall result in the assessment of a late charge equal to one and
one-half (1 1/2%) percent per month on any outstanding balance, or the maximum
amount of interest chargeable by law, whichever is less.

Customer shall remain liable for all payments regardless of the method of
payment or financing of this Agreement, unless otherwise agreed to in writing by
Harris. 

Customer's payment obligations are particular hereto, and Customer has no right
of set-off against other Purchase Orders or other transactions between the
parties. 

6.  WARRANTIES AND LICENSE

    A)   EQUIPMENT WARRANTY

Refer to Annex C for terms and conditions related to customer service and
equipment warranty.

Harris warrants that each product of its own manufacture shall, at the time 
of delivery and for a period of twenty-four (24) months thereafter, be free 
from defects in materials and workmanship and to conform to Harris' published 
specifications.  Such warranty shall not include any consumable components to 
which a specific manufacturer's guarantee applies.  If any Harris product 
shall prove to be defective in materials or workmanship under normal intended 
usage, operation and maintenance during the  applicable warranty period as 
determined by Harris after examination of the  product claimed to be 
defective, then Harris  shall repair, replace or refund the purchase price 
of, at Harris' sole option, such defective product, in accordance with 
procedures specified below, at its own expense, exclusive, however, of the 
cost of labor by the Customer's own employees, agents or contractors in 
identifying, removing or replacing the defective part(s) of the product.  
Replacement products may be new, refurbished or remanufactured. Returned 
replaced products shall become the property of Harris.  Replacement products 
shall be warranted for the balance of  the unexpired portion of the returned 
products warranty. 

In composite equipment assemblies and systems, which include equipment of such
other than Harris  manufacture, Harris' responsibility under this warranty
provision for the non-Harris manufactured portion of the equipment shall be
limited to the other equipment  manufacturer's standard warranty.  Provided,
however, that if the other manufacturer's standard warranty period

                                                                             2
<PAGE>

is of a shorter duration than the warranty period applicable to Harris' 
manufactured equipment, then Harris shall extend additional coverage to such 
other equipment manufacturer's warranty equal to the differential in time 
between the expiration of the other manufacturer's warranty and the duration 
of Harris' manufactured equipment  warranty  applicable to such order. Harris 
shall repair,  replace or refund the purchase price of, at Harris'
sole option, such other manufacturer's defective part(s) within sixty (60) days
after receipt of such parts by Harris in accordance with the below specified
procedures, at Harris' own expense, exclusive, however, of cost of labor by the
Customer's own employees, agents or contractors in identifying, removing or
replacing the defective part(s) of the product.

A written authorization to return products to Harris under this warranty must 
be obtained from a Harris representative prior to making shipment to Harris' 
plant, and all returns shall be shipped freight prepaid.  Collect shipments 
will not be accepted, but Harris will prepay return freight charges on 
repaired and replaced products found to be actually defective.

The warranty provided herein does not cover damage, defects, malfunctions or 
service failures caused by:

 (1) Customer's failure to follow Harris' environmental, installation, operation
or maintenance specifications or instructions; 

 (2) Modifications, alterations or repairs made other than by Harris;

 (3) Customer's mishandling, abuse, misuse, negligence, or improper storage,
servicing or operation of the Equipment (including without limitation use with
incompatible equipment); or

(4)  Power failures, surges, fire, flood, accident, actions of third parties or
     other like events outside Harris' control.  Repairs necessitated during the
     warranty period  by any of the foregoing causes may be made by Harris, and
     the Customer shall pay Harris' standard charges for time and materials,
     together with all shipping  and handling charges arising from such repairs.
     

     B)       SOFTWARE WARRANTY AND LICENSE

     (1)  LICENSE.  Harris grants to Customer a non-exclusive, non-transferable
license to use the software and related documentation ("Software") provided
hereunder.  The Software may include software and documentation that are owned
by third parties and distributed by Harris under license from the owner.  If
Customer is a reseller of the software purchased under this agreement, this
license is assignable only to Customer's customer, subject to Harris' written
authorization and only if the end customer is bound in writing to the Terms and
Conditions of this license.  Customer shall retain a copy of such end Customer
Agreement for Harris' inspection.

   (2)  COPIES.  Customer shall not make any copies of the Software, except for
a single archival copy solely for internal purposes.

   (3)  CONFIDENTIALITY.  Customer shall maintain the confidentiality of the
Software and shall not sub-license, sell, rent, disclose, make available, or
otherwise communicate the Software to any other person, or use the Software
except as expressly authorized in writing by Harris.

   (4)  TITLE.  The Software and all copies thereof will at all times remain
the sole and exclusive property of Harris or its licensor, as applicable, and
Customer shall obtain no title to the Software.

   (5)  COPYRIGHT.  Customer shall reproduce all copyright notices and any
other

                                                                             3
<PAGE>

proprietary legends on any copy of the Software made by Customer.

   (6)  ALTERATION.  Customer shall not modify, disassemble, or decompile the
Software.

   (7)  MEDIA.  If Customer sells or otherwise disposes of Customer owned
media on which the software is fixed, such media must be erased before any sale
or disposal.

   (8)  WARRANTY.  Harris does not warrant that the operation of the Software
will be error free.  Harris will use reasonable efforts to correct any defects
reported to Harris in writing within twenty-four (24) months of the date of
shipment, exclusive of defects caused by physical defects in Software disks due
to mishandling, operator error or interfacing other systems not approved by
Harris.

    c)   LIMITATIONS

LIABILITY OF HARRIS FOR BREACH OF ANY AND ALL WARRANTIES HEREUNDER IS EXPRESSLY
LIMITED TO THE REPAIR, REPLACEMENT OR REFUND OF THE PURCHASE PRICE OF DEFECTIVE
PRODUCTS AS SET FORTH IN THIS SECTION, AND IN NO EVENT SHALL HARRIS BE LIABLE
FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES BY REASON OF ANY BREACH OF
WARRANTY OR DEFECT IN MATERIALS OR  WORKMANSHIP.  HARRIS SHALL NOT BE
RESPONSIBLE FOR REPAIR, REPLACEMENT  REFUND OF PURCHASE PRICE OF PRODUCTS WHICH
HAVE BEEN SUBJECTED TO NEGLECT, ACCIDENT OR  IMPROPER USE,  OR WHICH HAVE BEEN
ALTERED BY OTHER THAN AUTHORIZED HARRIS PERSONNEL.  THE FOREGOING WARRANTIES ARE
IN LIEU OF ALL OTHER WARRANTIES WHETHER ORAL, WRITTEN, EXPRESSED, IMPLIED, OR
STATUTORY.  IN PARTICULAR, THE IMPLIED WARRANTIES OF FITNESS FOR PARTICULAR
PURPOSE AND MERCHANTABILITY ARE HEREBY DISCLAIMED AND SHALL NOT BE APPLICABLE 
EITHER FROM HARRIS OR ANY OTHER EQUIPMENT OR SOFTWARE MANUFACTURER. HARRIS'
WARRANTY OBLIGATIONS AND CUSTOMER'S REMEDIES THEREUNDER ARE SOLELY AND
EXCLUSIVELY AS STATED HEREIN. IN NO CASE SHALL HARRIS BE LIABLE FOR INDIRECT
KINDS OF DAMAGES, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL, AND 
CONSEQUENTIAL DAMAGES, OR LOSS OF CAPITAL, REVENUE, OR PROFITS. IN NO EVENT
SHALL HARRIS' LIABILITY TO CUSTOMER, OR ANY PARTY CLAIMING THROUGH CUSTOMER, BE
IN EXCESS OF THE ACTUAL SALES PRICE PAID BY CUSTOMER FOR ANY ITEMS SUPPLIED
HEREUNDER.

7.   TITLE AND RISK OF LOSS

Risk of loss for all Equipment sold under this Agreement shall pass to Customer
at time of delivery as defined herein.  Customer grants to Harris a security
interest in the Equipment covered by this Agreement in the amount of the unpaid
balance of the purchase price until payment in full of the purchase price at
which time title in the Equipment will pass in accordance with the terms and
conditions set forth herein.   A financing statement may be filed with the
appropriate public authorities and Customer agrees to sign any such financing
statements or other documents tendered to it by Harris from time to time to
protect Harris' security interest. 

8.   EXPORT AND RE-EXPORT RESTRICTIONS

Performance and delivery of the equipment, documents, services and Software sold
or delivered hereunder are subject to export control laws and regulations of the
United States and/or Canada, as applicable, and conditioned upon receipt of
required U.S. and/or Canadian Government licenses and approvals by Harris. 
Customers shall not export products or technical data delivered hereunder from
the United States or Canada without complying with regulations of the Bureau of
Export Administration of the United States Department of Commerce and/or the
Export Controls Division of the Canadian Department of Foreign Affairs and
International Trade, as applicable.  Customers shall not re-export the products
and technical data delivered hereunder from the country of delivery or to any
facility engaged in the design, development, stockpiling,

                                                                             4
<PAGE>

manufacturing or use of missile, chemical or biological weapons without fully 
complying with the regulations of the above United States and/or Canadian 
government agencies.

9.  EXCUSABLE DELAY

Harris shall be excused from performance under the Purchase Order and not be
liable to Customer for delay in performance attributable in whole or in part to
any cause beyond its reasonable control, including but not limited to, actions
or inactions of government whether in its sovereign or contractual capacity,
judicial action, war, civil disturbance, insurrection, sabotage, act of a public
enemy, labor difficulties or disputes, failure or delay in delivery by Harris'
suppliers or subcontractors, transportation difficulties, shortage of energy,
materials, labor or equipment, accident, fire, flood, storm or other act of God,
or Customer's fault or negligence.

In the event of an excusable delay, Harris shall make reasonable efforts to
notify Customer of the nature and extent of such a delay and Harris (i) will be
entitled to a schedule extension on at least a day-for-day basis, (ii) in the
event of Customer's fault or negligence, will be also entitled to an equitable
adjustment in the price of this contract.  Notwithstanding any other term
contained herein, in the event an excusable delay occurs and continues for a
period of ninety (90) days or longer, ART shall have the right to immediately
terminate this Agreement or any Purchase Order given pursuant to the Agreement
without further liability to Harris.

10.  TERM AND TERMINATION

This Agreement shall continue in effect for one (1) year from the date hereof at
which time it will terminate, unless terminated earlier pursuant to this Article
12.  Renewal is subject to mutual written agreement signed by both parties.

Cancellation of any Purchase Order hereunder will be accepted only upon the
specific written approval of Harris and is subject to standard Harris
cancellation charges of 25 % if cancellations is received 30 days after receipt
of order from ART,  provided however, that ART may cancel any Purchase Order
without the approval of Harris and without incurring cancellation charges if the
delivery of Products under such Purchase Order is delayed, or expected to be
delayed, by ninety (90) days or more from the original delivery date. 

In the event that Customer shall become liquidated, dissolved, bankrupt or
insolvent, or shall take any action to be so declared, or shall suffer any such
action brought by another, Harris shall have the right to terminate this
Agreement and all Purchase Orders immediately and may stop shipment of any
Products in transit.
        
Either party may terminate this Agreement immediately upon notice in writing to
the other party: 

     a)  if the other party shall breach any provision of this Agreement in any
material respect and such breach remains unremedied thirty (30) days after 
notice thereof from the non-breaching party; 

     b) in the event that the other party breaches any material term, condition
or covenant of the PCS Marketing Agreement referenced in Section 1 above and the
other party fails to cure any default or breach within thirty (30) days of
receipt of written notice of such breach from the non-breaching party; or 

     c)  in the event that the other party has caused the PCS Marketing
Agreement referenced in Section 1 above to be terminated.

                                                                             5
<PAGE>

         The right of termination provided herein is absolute and neither party
shall be liable to the other for damages or otherwise by reason of such
termination.

11.  INFRINGEMENT INDEMNIFICATION

Customer agrees to promptly notify Harris in writing of any notice, suit, or any
action against Customer based upon a claim that the Product infringes a U.S.
patent, copyright, trademark, or trade secret of a third party.  Harris will
defend at its expense any such action, except as excluded below, and shall have
full control of such defense including all appeals and negotiations, and will
pay all settlement costs, or damages awarded against Customer, but Harris shall
not be liable to Customer for special, incidental, indirect or consequential
damages.  In the event of such notice, suit or action, Harris will at its
expense procure for the Customer the right to continue using the product, or
modify the Product to render such non-infringing, or accept return and replace
such with substantially equivalent non-infringing equipment, or accept return of
the Product and refund or credit to Customer the amount of the original purchase
price, less a reasonable charge for depreciation and damage.

The preceding agreements by Harris in this section shall not apply to any
Product or portion thereof manufactured to specifications furnished by or on
behalf of Customer, or to any infringement arising out of the use of the Product
in combination with other equipment or software not furnished by Harris, or to
use in a manner not normally intended, or to any patent, copyright, trademark or
trade secret in which Customer, or subsidiary or affiliate thereof, has a direct
or indirect interest, or if customer has not provided Harris with prompt notice,
authority, information and assistance necessary to defend the action.  The
foregoing states the entire liability of Harris for patent, copyright, trademark
and trade secret infringements by the Product or portion thereof.

The rights and obligations of the parties under this Section shall survive
termination of this Agreement.

12.       TECHNICAL DATA AND INVENTION

Unless specifically agreed to by Harris and identified and priced in this
contract as a separate item or items to be delivered by Harris (and in that
event, except to the extent so identified and priced), the sale of goods
hereunder confers on Customer no right in, license under, access to, or
entitlement of any kind to any of Harris' technical data including but not
limited to design, process technology, software and drawings, or to Harris'
inventions (whether or not patentable) irrespective of whether any such
technical data or invention or any portion thereof arose out of work performed
under or in the course of this contract, and irrespective of whether Customer
has paid or is obligated to pay Harris for any part of the design and/or
development of the goods.

Harris shall not be obliged to safeguard or hold confidential any data whether
technical or otherwise, furnished by Customer for Harris' performance of this
contract unless (and only to the extent that) Customer and Harris have entered
into a separate written confidential agreement. 

Customer shall not violate Harris' copyright of documents or software or
disclose Harris' confidential or proprietary data to others without Harris
written permission.

13.  ASSIGNMENT

Neither party may assign this agreement in whole or in part without the prior
written consent signed by an officer of the other party.  Such consent shall not
be unreasonably withheld.

                                                                             6
<PAGE>


14.  GOVERNING LAW, VENUE, AND JURISDICTION

This Agreement will be governed by and construed in accordance with the laws of
the State of California.  The parties agree that any action to enforce any
provision of this Agreement or arising out of or based upon this Agreement or
the business relationship between Harris and Customer will be brought in a local
or Federal court of competent jurisdiction in the State of California.

15.  ENFORCEABILITY

If any provision of this Agreement shall be held to be invalid, illegal or
unenforceable, the validity, legality or enforceability of the remaining
provisions shall in no way be affected or impaired.

16.  NOTICES

All notices shall be in writing and shall be delivered or sent by registered,
certified or express mail, return receipt requested, to the addresses indicated
in this Agreement or to such other addresses as the parties shall specify by
giving notice pursuant hereto.  A copy of all notices shall be sent to Harris
Corporation, Farinon Division, 330 Twin Dolphin Drive, Redwood Shores, CA 94065,
Attention:  Manager of Contracts, and to W. Theodore Pierson, Jr. Executive Vice
President and General Counsel, 1667 K Street, NW, Suite 801 Washington, DC
20006.

17.  INDEMNIFICATION

     a)   INDEMNIFICATION OF ART BY HARRIS  

Harris shall indemnify ART against, and hold ART harmless from all liabilities,
demands, claims, damages, losses, demands, costs,  judgments and expenses
(including reasonable attorneys' fees) arising out of or in connection with
arising out of or relating to the installation, operation, or use of the
Products for personal injury or damage to tangible property, caused by the
negligent acts or omissions of Harris or Harris's employees, agents or invitees.
In no event shall ART's employees, agents or invitees be deemed to be employees,
agents or invitees of Harris.

     b)   INDEMNIFICATION OF HARRIS BY ART  

ART shall indemnify Harris against, and hold Harris harmless from all
liabilities, demands, claims, damages, losses, demands, costs,  judgments and
expenses (including reasonable attorneys' fees) to the extent they arise out of
or are in connection with or relate to the installation, operation, or use of
the Products for personal injury or damage to tangible property, caused by the
negligent acts or omissions of ART or ART's employees, agents or invitees.  In
no event shall Harris's employees, agents or invitees be deemed to be employees,
agents or invitees of ART.
 
     c)   DUTY TO NOTIFY AND ASSIST  

If any claim arises to which the provisions of this Section may be applicable,
the party against whom such claim is made shall notify the other party
immediately upon learning of the claim.  If it appears that the other party may
be obligated to provide indemnification as a result of such claim, the other
party, in its discretion, may settle or compromise the claim

                                                                             7
<PAGE>

or retain counsel of its own choosing and control and prosecute the defense 
against such claim. In no event shall the party against whom the claim is 
asserted have the right to pay, settle or compromise such claim without the 
prior written consent of the party who may be obligated to indemnify under 
this Section and the parties hereto agree that they will not unreasonably 
withhold consent to such consent to payment, settlement or compromise.  The 
party against whom the claim is asserted shall provide the other party such 
assistance as may be reasonable in the defense and disposition of such claim. 

The rights and obligations of the parties under this Section shall survive
termination of this Agreement.

18.  LIMITATION OF LIABILITY

NOTWITHSTANDING ANY OTHER PROVISIONS OF THIS CONTRACT, UNDER NO CIRCUMSTANCES
SHALL HARRIS BE LIABLE TO CUSTOMER OR ANY THIRD PARTY CLAIMING UNDER CUSTOMER
FOR SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES, AS A RESULT OF A
BREACH OF ANY PROVISION OF THIS CONTRACT.  

19.  ENTIRE AGREEMENT

This Agreement supersedes all previous communications, transactions, and
understandings, whether oral, or written, and constitutes the sole and entire
agreement between the parties pertaining to the subject matter hereof.  No
modification or deletion of, or addition to these terms shall be binding on
either party unless made in writing and signed by a duly authorized
representative of both parties.

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


ADVANCED RADIO TELECOM CORPORATION

BY: /s/ Charles H. Menatti
   ______________________________

NAME:  /s/ Charles Menatti
       ___________________________

TITLE: V.P. Bus. Development
       ___________________________


HARRIS CORPORATION
FARINON DIVISION

BY:  /s/ J. Michael Slattery
    ______________________________

NAME: /s/ J. Michael Slattery
     ___________________________ 

TITLE: Division Controller
      ___________________________



                                            8 


<PAGE>
 






        [Annexes A, B and C omitted due to confidential treatement]


<PAGE>

                              EMPLOYMENT AGREEMENT


     THIS EMPLOYMENT AGREEMENT is entered into and made effective the 26th day
of April, 1996 ("Effective Date"), by and between Advanced Radio Telecom Corp.,
a Delaware Corporation with principal offices located at 500 - 108th Avenue
N.E., Suite 1910, Bellevue, WA  98004 (the "Employer"), and Thomas A. Grina,
presently residing at the address listed in Section 20 hereof (the "Employee").

     The Employer is in the business of providing local wireless communications
using 38 GHz radio signals including provision of high speed data links for
business, integrated data and voice services extending fiber optic rings and
interconnections between mobile radio base stations and switches.  The Employer
desires to engage the services of the Employee and the Employee desires to
accept such engagement, on the terms and subject to the conditions hereinafter
set forth.

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
herein set forth, the parties, intending to be legally bound, hereby agree as
follows:

     1.   EMPLOYMENT.  The Employer engages the Employee, and the Employee
accepts engagement by the Employer, upon the terms and subject to the conditions
set forth in this Agreement, and subject to the terms and conditions of the ART
Employee Handbook which the Employee has read and with which the Employee is
familiar.  

     2.   TERM/SURVIVABILITY.  Subject to the provisions hereof, the Employee's
employment by the Employer under this Agreement shall be at will.  All
provisions of this Agreement, including, but not limited to those contained in
Sections 7, 10, 11, 12, 13 and 14, that by their nature are intended to survive
the termination of this Agreement shall so survive, continue in full force and
effect and be fully enforceable according to their provisions.  The term of the
Employee's employment hereunder is hereinafter referred to as the "Employment
Period."

     3.   POSITION, TITLE AND DUTIES.  The Employee's title shall be Executive
Vice President, Chief Financial Officer.  During the Employment Period, the
Employee shall perform such assignments and have such powers and duties as are
assigned or delegated to him by the Employer.  Such assignments, powers  and
duties, may, from time to time, be modified by the Employer as Employer's needs
may require.  The Employee's initial duties will include, but not be limited to
those customarily associated with the position of Executive Vice President,
Chief Financial Officer.

     At the request of the Employer, the Employee shall also perform similar
services for any Affiliate (as hereinafter defined) of the Employer without
additional compensation as long as the requests are reasonable (giving due
regard to the Employee's time commitments as an executive of the Employer),
legitimate and lawful.  The Employee agrees to devote substantially all of his
business time, skill, attention and best 

<PAGE>

efforts to the business of the Employer and Affiliates in the advancement of 
the best interests of the Employer and Affiliates, except that the Employee 
shall be permitted to devote a reasonable amount of time to charitable 
endeavors, investments and to personal affairs to the extent that such 
additional endeavors do not interfere with the employee's duties with the 
Employer.  As used in this Agreement, the term "Affiliate" of the Employer 
means any person or corporation that, directly or indirectly, through one or 
more intermediaries, controls or is controlled by or is under common control 
with the Employer or its stockholders.  The Employer and its Affiliates 
assume all responsibility related to the proper reporting as Employer, for 
services performed by the Employee, to the relevant taxing authorities.  The 
Employee shall render his services in the Seattle, Washington metropolitan 
area, provided that the Employer or Affiliates may require the Employee to 
render his services in another community within the United States for periods 
of limited duration.

     4.   COMPENSATION.

          4.1. SALARY.

               4.1.1.    BASE SALARY.  For all services rendered by the Employee
to the Employer through April 30, 1997, the Employer (or at the Employer's
option, any Affiliate of the Employer) shall pay the Employee an annualized Base
Salary of One Hundred Ninety Thousand Dollars ($190,000.00), to be paid in equal
semi-monthly installments.  The Employer shall review the Base Salary at least
once per year, no later than the fourth calendar quarter, with any increase to
be effective January 1 of the following calendar year.  

               4.1.2     BONUS.  A cash bonus of $50,000 shall be paid within 45
days following the end of each fiscal year beginning with the 1996 fiscal year
for achievement of annual link installation goals.  The goal for fiscal year
1996 is 1596 equivalent DSI links.  For subsequent years the bonus will be based
on achieving link goals to be established in succeeding years' annual operating
budgets as presented by the President and approved by the  Employer's Board of
Directors.  The amount of the bonus may increase or decrease depending on
achievement of these goals and will be calculated according to the Bonus
Achievement Scale immediately below:

                    Bonus Achievement Scale
                    -----------------------

     Goal Achievement Level             Percent of Bonus Paid
     ----------------------             ---------------------
          200% or more                          200%
          175-199%                              175%
          150-174%                              150%
          125-149%                              125%
          100-124%                              100%
          75-99%                                 75%

                                      2

<PAGE>

          50-74%                                 50%
          less than 50%                           0%
          
     To the extent that the Board of Directors deems it advisable, in its sole
discretion, the Employee may use amounts awarded as bonuses under this Section,
in whole or in part, to purchase shares of common stock of Advanced Radio
Technology, Limited.  The class of common stock will be prescribed by the Board
of Directors.  The price of such shares shall be their fair market value
("FMV").  For purposes of this Section 4.1.2, "FMV" shall mean:  (a) the closing
price per share on the day prior to the date of purchase, if shares of the class
of stock to be purchased are publicly-traded; or (b) if shares of the class of
stock to be purchased are not publicly-traded, the last price at which shares of
such class were sold by the Employer in an arms-length transaction to a party
other than the Employee, and other than in a sale involving the exercise of an
option to purchase shares of such class.  The Employee agrees to deliver to the
Employer, at the time of any purchase made pursuant to this Section, an executed
Stock Purchase Agreement in such form as prescribed by the Employer.

     4.2. ADDITIONAL INCENTIVES.

          4.2.1.    [Reserved]

          4.2.2.    RELOCATION EXPENSES.  Employer will pay the costs of
Employee's relocation from Greer, South Carolina, to the Seattle, Washington
area, including all reasonable cartage, realtor fees (on the sale of Employee's
present residence), financing fees ("points") on Employee's new residence and
other relocation assistance subject to the President's approval.

          4.2.3.    TEMPORARY LIVING EXPENSES.   Employer will pay reasonable
expenses while Employee is in transition, subject to President's approval.

          4.2.4.    AUTOMOBILE ALLOWANCE.  During the Employment Period, the
Employee will receive from the Employer an allowance of Eight Hundred Dollars
($800.00) per month to cover expenses associated with operating and maintaining
an automobile to be used in furtherance of the business interests of the
Employer.

     4.3  STOCK OPTIONS:

          4.3.1.  GRANT OF OPTIONS.  Upon the Effective Date of this Agreement,
the Employer will grant to the Employee options to purchase Three Hundred
Thousand (300,000) shares of common stock of  the Employer (or any successor
thereto) set forth in Exhibit A, attached hereto, and incorporated herein by
reference.  All of the options shall be  Nonqualified Stock Options. With the
exception of the options that vest immediately all options will be subject to
certain financial performance requirements to be developed jointly with the
Employee and approved by the Employer's Board or appointed 

                                      3

<PAGE>

committee(s).  All options are subject to the Employer's "1995 Employee Stock 
Option Plan," regulatory rules and underwriter's approval.  

          4.3.2.  VESTING. The stock options granted pursuant to Section 4.3.1.
of this Agreement will vest according to the schedule set forth in Exhibit A,
attached hereto, and incorporated by reference herein, provided that the
financial performance requirements, if any, contemplated by Section 4.3.1. have
been satisfied. In any event, all of the stock options granted pursuant to
Section 4.3.1. shall vest on April 26, 1999, even if the financial performance
requirements have not been satisfied  Further, all such options shall vest
immediately upon the merger of the Employer with other than an affiliated
corporation, the sale of a controlling interest of the Employer in other than a
public offering, the sale of substantially all of the assets of the Employer, or
a Change of Control of the Employer as defined in the 1995 Employee Stock Option
Plan, as amended from time to time.

          4.3.3.  EXERCISE AND PAYMENT. Except as otherwise provided in the 1995
Employee Stock Option Plan or the Stock Option Agreements issued pursuant
thereto, each option shall be exercisable for a period of five (5) years from
the date of vesting of each such option at the exercise price of Six and Twenty
Five One Hundredths Dollars ($6.25) per share.  In connection with the exercise
of any stock option granted pursuant to this Agreement, the Employee agrees to
deliver to the Employer, at the time of exercise, an executed Stock Option
Agreement in such form as prescribed by the Employer.

     5.   [Reserved]

     6.   EMPLOYEE BENEFITS.  During the Employment Period, the Employee shall
be entitled to participate in the Employer's benefit plans, pension plans and
retirement plans, life insurance, long-term disability insurance,
hospitalization, surgical and major medical coverage, and other fringe benefits
enjoyed by executive employees of the Employer, including a 401(k) plan and an
Employee Stock Purchase Plan,  if and when adopted, and the 1995 Employee Stock
Option Plan to the extent provided in Exhibit A hereto.  The Employee will also
be entitled to paid annual vacation time (not to exceed three weeks), sick
leave, and holidays.

     7.   INDEMNIFICATION; LIABILITY INSURANCE.  The Employer 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 the Employee from and against any and all of the
expenses, liabilities, or other matters referred to in or covered by said
Section.  Such indemnification shall be provided with respect to actions taken
in the Employee's official capacity and as to actions taken in another capacity
while holding such office.  The indemnification coverage provided in this
Section 7 shall continue after the Employee's termination with respect to such
actions during the Employment Period.  The Employer also agrees to use its best
efforts to obtain and maintain an insurance policy or policies providing
liability coverage to the 

                                      4

<PAGE>

Employer's executive officers and directors for acts or omissions in 
connection with their duties as executive  officers and directors of the 
Employer.

     8.   EXPENSE REIMBURSEMENT.  Subject to such policies regarding expenses
and expense reimbursement as may be adopted from time to time by the Employer
and compliance therewith by the Employee, the Employee is authorized to incur
reasonable expenses in the performance of his duties hereunder, and the Employer
shall reimburse the Employee for such reasonable out-of-pocket expenses, upon
the presentation by the Employee of an itemized account of such expenses and
receipts satisfactory to the Employer.  The Employer shall have the right to
request reasonable additional documentation of such requests.

     9.   TERMINATION.

          9.1. INVOLUNTARY TERMINATION.  Termination by the Employer of the
Employee under this Agreement as a result of incapacity or disability by
accident, sickness or other cause so as to render the Employee mentally or
physically incapable of performing those services required to be performed by
him under this Agreement for a period of 180 consecutive days or longer, or for
180 days during any twelve month period (such condition being called a
"Disability"), is referred to herein as an "Involuntary Termination."  If the
Employee dies during the Employment Period, his engagement hereunder shall be
deemed to cease as of the date of his death, and the termination of his
engagement occasioned thereby also shall be deemed an Involuntary Termination.

          9.2. TERMINATION FOR CAUSE.  The Employer may terminate the Employee's
engagement for cause ("Termination for Cause").  For purposes of this Agreement,
"Cause" is limited to the following:

     (a)  the willful and continued failure by the Employee substantially to
     perform the duties described in Section 3 (other than a failure resulting
     from an illness or similar incapacity or disability) for 10 days after a
     written demand for performance is provided to the Employee by or on behalf
     of the Board of Directors which specifically identifies the manner in which
     it is alleged that the Employee has failed to perform his duties;

     (b)  the engaging of the Employee in the misappropriation of funds,
     properties or assets of the Employer or any Affiliate or an intentional
     tort or other conduct relating to his office or engagement with the
     Employer which has, or may be reasonably anticipated to have, a material
     adverse effect on the Employer or any Affiliate;

     (c)  the Employee's conviction of a crime constituting a felony, including
     the entry of a plea of guilty or no contest by the Employee to a charge of
     a crime constituting a felony.

                                      5

<PAGE>

          9.3  TERMINATION WITHOUT CAUSE.  The termination of the Employee's
engagement by the Employer at any time during the Employment Period without
"Cause," other than an Involuntary Termination, is referred to herein as a
"Termination Without Cause."

          9.4  VOLUNTARY TERMINATION.  Any termination of the Employee's
engagement that is not an Involuntary Termination, a Termination for Cause, or a
Termination Without Cause, including the Employee's giving notice of termination
prior to the end of the Employment Period, is referred to herein as a "Voluntary
Termination."

          9.5. EFFECT OF TERMINATION - VOLUNTARY TERMINATION OR TERMINATION FOR
CAUSE.  Upon the termination of the Employee's engagement pursuant to a
Voluntary Termination or a Termination for Cause, neither the Employee nor his
beneficiary or estate shall have any further rights or claims against the
Company or any Affiliate under this Agreement except:

     (a)  the right to receive any unpaid portion of the Employee's Base Salary
     provided for in Section 4.1.1 and Bonus provided for in Section 4.1.2,
     computed on a PRO RATA basis to the date of termination; and

     (b)  reimbursement for any expenses for which the Employee has not yet been
     reimbursed as provided in Section 8.

          9.6  EFFECT OF TERMINATION - INVOLUNTARY TERMINATION OR TERMINATION
WITHOUT CAUSE.  Upon the termination of the Employee's engagement pursuant to an
Involuntary Termination or a Termination Without Cause, the Employee shall be
entitled to the following:

     (a)  any unpaid portion of the Employee's Base Salary provided for in
     Section 4.1.1. and Bonus, if any,  provided for in Section 4.1.2, computed
     on a PRO RATA basis to the date of termination;

     (b)  reimbursement for any expenses for which the Employee has not yet been
     reimbursed as provided in Section 8;

     (c)  a payment equivalent to six (6) months of the employee's Base Salary
     and Bonus in effect at the time of such termination;

     (d)  continuance of the Employee's automobile allowance, as described in
     Section 4.2.4 hereof, for a period of six (6) months following the date of
     termination;

     (e)  continuance of the Employee's long-term disability insurance,
     hospitalization, surgical and major medical coverage for a period of six
     (6) months following the date of termination;

                                      6

<PAGE>

     10.  COVENANT NOT TO COMPETE.  The Employee expressly recognizes the highly
competitive nature of the business conducted and planned to be conducted by the
Employer and its Affiliates.  The Employee, therefore, covenants and agrees that
during the term of this Agreement and for a period of one (1) year thereafter,
he will not, within the United States or in any market in which the Employer is
conducting business:

     (a)  directly or indirectly engage in any Competitive Business, whether as
     an employer, employee, officer, director, owner, partner, consultant or
     other participant;

     (b)  assist others in engaging in any Competitive Business in the manner
     described in above in clause (a); or

     (c)  induce employees of the Employer or its Affiliates to terminate their
     employment with the Employer or Affiliates or engage in any Competitive
     Business.

     The Term "Competitive Business" means the provision of 38 GHz services. 
Employee acknowledges that he has read and understood this Section 10; that he
understands that it may operate to restrain his ability to obtain employment
elsewhere after his termination by Employer; that this employment agreement is
adequate consideration for his agreeing to be bound by the covenant in this
Section 10; and that he agrees that breach of this Section by him would
irreparably damage Employer or its Affiliates, and he hereby consents to entry
of injunctive relief to enforce compliance with this Section 10, which relief
shall be in addition to all other forms of relief available at law or equity.

     11.  COVENANT NOT TO DISCLOSE OR USE.  The Employee covenants and agrees
that he will not disclose, at any time during or after the Employment Period, to
any person or entity except as required by law, any secret or confidential
information concerning the business, clients or affairs of the Employer or its
Affiliates other than in furtherance of his work for the Employer or Affiliates.
The Employee also covenants and agrees that he will not, at any time during or
after the Employment Period, use for his own account or profit any secret or
confidential information concerning the business, clients or affairs of the
Employer or its Affiliates.  For purposes of this Section, the term "secret or
confidential information" shall include, but not be limited to, information
concerning any inventions, processes, operations, administrative procedures,
databases, programs, systems, flow charts, software, firmware or equipment used
in the Employer's or the Affiliates' business, customers lists, customer
information, or trade secrets.  Employee acknowledges that he has read and
understood this Section 11; that he understands that it may operate to restrain
his ability to obtain employment elsewhere after his termination by Employer;
that this employment agreement is adequate consideration for his agreeing to be
bound by the covenant in this Section 11; and that he 

                                      7

<PAGE>

agrees that breach of this Section by him would irreparably damage Employer 
or its Affiliates, and he hereby consents to entry of injunctive relief to 
enforce compliance with this Section 11, which relief shall be in addition to 
all other forms of relief available at law or equity.

     12.  COVENANT NOT TO SOLICIT.  The Employee expressly recognizes that the
Employer's or Affiliates' customers and employees are important and critical
aspects of their ability to operate profitably.  The Employee, therefore,
covenants and agrees that during the term of this Agreement and for a period of
one (1) year thereafter, he will not solicit, or cause or assist in any way in
causing another person or entity to solicit, the then-existing customers or
employees of the Employer or its Affiliates to become customers or employees of
any other entity in a Competitive Business.  For purposes of this Section, the
term "Competitive Business" means the provision of 38 GHz services.  Employee
acknowledges that he has read and understood this Section 12; that he
understands that it may operate to restrain his ability to obtain employment
elsewhere after his termination by the Employer; that this employment agreement
is adequate consideration for his agreeing to be bound by the covenant in this
Section 12; and that he agrees that breach of this Section by him would
irreparably damage the Employer or its Affiliates, and he hereby consents to
entry of injunctive relief to enforce compliance with this Section 12, which
relief shall be in addition to all other forms of relief available at law or
equity.

     13.  SEVERABILITY.  Wherever possible, each provision of this Agreement
shall be interpreted in such manner as to be effective and valid under
applicable law, but, if any provision hereof shall be prohibited by or held
invalid or unenforceable under any such law, such provision shall be ineffective
to the extent of such prohibition, invalidity or unenforceability, without
invalidating or nullifying the remainder of such provision or any other
provision of this Agreement.  The parties further agree to substitute a
provision that effects the intent of the invalidated provision as nearly as
possible.

     14.  BINDING EFFECT; ASSIGNMENT.  This Agreement is personal in its nature,
and neither the Agreement nor any rights or obligations thereunder may be
assigned or transferred without the written consent of the parties hereto;
PROVIDED, HOWEVER, that the provisions hereof shall inure to the benefit of, and
be binding upon, each successor of the Employer, whether by merger,
consolidation, transfer of all or substantially all assets, or otherwise.

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

     16.  ENFORCEMENT.  The parties desire that the provisions of this Agreement
shall be enforced to the fullest extent permissible under the laws and public
policies applied to the jurisdiction whose laws govern this Agreement. 
Accordingly, to the extent that a restriction contained in this Agreement is
more restrictive than permitted by the 

                                      8

<PAGE>

laws of any jurisdiction where this Agreement may be subject to review and 
interpretation, the terms of such restriction, for the purpose only of the 
operation of such restriction in such jurisdiction, shall be the maximum 
restriction allowed by the laws of such jurisdiction and such restriction 
shall be deemed to have been revised accordingly herein.

     17.  REMEDIES.  The Employee acknowledges that the provisions of this
Agreement are of a special and unique nature, the loss of which cannot be
accurately compensated for in damages by an action at law, and in the event of a
breach of Section 10, 11, or 12, the Employer shall be entitled to an injunction
restraining him from such breach, in addition to any other remedies available to
the Employer.

     18.  GOVERNING LAW.  The parties agree that this Agreement shall be
interpreted and construed both as to performance and validity in accordance with
and governed by the laws of the State of Washington even if its choice of law
provisions are in conflict with this requirement.

     19.  WAIVER OF BREACH.  The waiver by either part of a breach of any
provision of this Agreement by the other part must be in writing and shall not
operate or be construed as a waiver of any subsequent breach by such other
party.

     20.  NOTICES.  All notices and other communications which are required or
may be given under this Agreement shall be in writing and shall be delivered
personally or by overnight air courier or first class certified or registered
mail, return receipt requested and postage prepaid to the persons and addresses
listed below, or to such other address as the party to whom notice is to be
given has furnished to the other party.  Each such notice shall, simultaneously
with its being delivered to the courier or messenger for delivery or placed in
the mail, be sent by facsimile or comparable electronic means.  All notices and
other communications hereunder shall be deemed to have been given:  (i) on the
date of delivery if personally delivered or, if not delivered on a business day,
the first business day thereafter; (ii) on the first business day after the date
sent if sent by overnight air courier; or (iii) on the fifth business day after
the date sent if sent by mail.

If to the Employer:

Tom Walker, Esq.         
Advanced Radio Telecom Corp.
500 - 108th Ave. N.E., Suite 2600
Bellevue, WA  98004

If to the Employee:

Thomas A. Grina
307 Sugar Mill Road
Greer, South Carolina 29650

                                      9

<PAGE>

     21.  ENTIRE AGREEMENT/MODIFICATION.  This Agreement constitutes the entire
agreement between the parties hereto and supersedes all prior representations,
agreements, understandings and arrangements, oral or written, between the
parties hereto with respect to the subject matter hereof.  This Agreement may
not be modified except by a writing that expressly refers to this Agreement and
is executed by all parties hereto.

     22.  HEADINGS.  The section and sub-section headings contained herein are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.

IN WITNESS WHEREOF, the parties have duly executed this Agreement on the date
first above written.

Employee


/s/ Thomas A. Grina
______________________
Thomas A. Grina

Advanced Radio Telecom Corp.

By: /s/ Steven D. Comrie
   _______________________
     Steven D. Comrie
     President & COO

                                      10

<PAGE>

HARRIS CORPORATION
FARINON DIVISION

PURCHASE AGREEMENT



This Agreement is entered into this 26th day of April, 1996, by and
between  Advanced Radio Telecom Corporation, a Delaware corporation with offices
located at 500 108th Avenue NE, Suite 2600, Bellevue, WA 98006 ("ART" or
"Customer"), and Harris Corporation, Farinon Division, a Delaware corporation,
with offices located at 330 Twin Dolphin Drive, Redwood Shores, CA 94065
("Harris").

Whereas, Customer desires to purchase microwave transmission equipment, software
and services ("Products") , and

Whereas, Harris is willing to sell such Products to Customer upon the terms and
conditions as set forth herein and the various annexes attached hereto and
incorporated into this document.

Now, Therefore, in consideration of the mutual
covenants set forth below, ART and Harris, intending to be legally bound, 
hereby agree as follows:

1.  EFFECTIVE DATE; RELATED PCS MARKETING AGREEMENT; FINANCING COMMITMENT.

The Effective Date of this Agreement shall be the date of execution by the
parties, provided, however, that the rights and obligations of the parties
hereunder shall not become effective unless and until the parties have executed
a definitive marketing agreement ("PCS Marketing Agreement") for 38 GHz services
as contemplated by Version 5 of a Letter of Intent executed by ART and Harris
and dated February 22, 1996.

2.  SCOPE

Harris will furnish Products for Customer in accordance with the individual
Purchase Orders issued by Customer from time to time during the Term of this
Agreement based upon the prices provided in Annex A hereto.  The Products will
be provided in conformity with the terms, conditions, specifications and other
requirements of this Agreement and each Purchase Order will be governed by the
terms and conditions stated herein. 

3.  PRICES/TAXES

All prices are exclusive of shipping and insurance charges which shall be billed
separately. All prices are exclusive of all sales, use, excise, and other taxes,
duties or charges.  Unless evidence of tax exempt status is provided by
Customer, Customer shall pay, or upon receipt of invoice from Harris, shall
reimburse Harris for all such taxes or charges levied or imposed on Customer, or
required to be collected by Harris, resulting from this transaction or any part
thereof.

All prices are FOB Harris' Factory. Unless instructed otherwise, Harris will
arrange for insurance and standard commercial shipping, the costs of which will
be invoiced to the Customer.


                                                                             1
<PAGE>

Responsibilities regarding the export of items delivered under this Agreement 
are detailed in Articles 8.  Prior to delivery, Harris reserves the right to 
make substitutions, modifications and improvements to the equipment and/or 
software ordered, provided that such substitutions, modifications or 
improvements shall not materially affect performance in the application 
originally agreed to with Customer.

4.   PURCHASE FORECAST GOALS.  

ART shall provide Harris with MicroStar and MicroStar Plus purchase forecasts,
which shall serve as a baseline  to establish pricing levels outlined in Annex
A.  ART's initial forecast is attached hereto as ANNEX B. Unless otherwise
agreed by the parties, future forecasts shall be provided by ART on  a quarterly
basis.

5.   PAYMENT/FINANCING

Payment terms shall be determined on a per order basis and are subject to credit
review by Harris.  

Late payments shall result in the assessment of a late charge equal to one and
one-half (1 1/2%) percent per month on any outstanding balance, or the maximum
amount of interest chargeable by law, whichever is less.

Customer shall remain liable for all payments regardless of the method of
payment or financing of this Agreement, unless otherwise agreed to in writing by
Harris. 

Customer's payment obligations are particular hereto, and Customer has no right
of set-off against other Purchase Orders or other transactions between the
parties. 

6.  WARRANTIES AND LICENSE

    A)   EQUIPMENT WARRANTY

Refer to Annex C for terms and conditions related to customer service and
equipment warranty.

Harris warrants that each product of its own manufacture shall, at the time 
of delivery and for a period of twenty-four (24) months thereafter, be free 
from defects in materials and workmanship and to conform to Harris' published 
specifications.  Such warranty shall not include any consumable components to 
which a specific manufacturer's guarantee applies.  If any Harris product 
shall prove to be defective in materials or workmanship under normal intended 
usage, operation and maintenance during the  applicable warranty period as 
determined by Harris after examination of the  product claimed to be 
defective, then Harris  shall repair, replace or refund the purchase price 
of, at Harris' sole option, such defective product, in accordance with 
procedures specified below, at its own expense, exclusive, however, of the 
cost of labor by the Customer's own employees, agents or contractors in 
identifying, removing or replacing the defective part(s) of the product.  
Replacement products may be new, refurbished or remanufactured. Returned 
replaced products shall become the property of Harris.  Replacement products 
shall be warranted for the balance of  the unexpired portion of the returned 
products warranty. 

In composite equipment assemblies and systems, which include equipment of such
other than Harris  manufacture, Harris' responsibility under this warranty
provision for the non-Harris manufactured portion of the equipment shall be
limited to the other equipment  manufacturer's standard warranty.  Provided,
however, that if the other manufacturer's standard warranty period

                                                                             2
<PAGE>

is of a shorter duration than the warranty period applicable to Harris' 
manufactured equipment, then Harris shall extend additional coverage to such 
other equipment manufacturer's warranty equal to the differential in time 
between the expiration of the other manufacturer's warranty and the duration 
of Harris' manufactured equipment  warranty  applicable to such order. Harris 
shall repair,  replace or refund the purchase price of, at Harris'
sole option, such other manufacturer's defective part(s) within sixty (60) days
after receipt of such parts by Harris in accordance with the below specified
procedures, at Harris' own expense, exclusive, however, of cost of labor by the
Customer's own employees, agents or contractors in identifying, removing or
replacing the defective part(s) of the product.

A written authorization to return products to Harris under this warranty must 
be obtained from a Harris representative prior to making shipment to Harris' 
plant, and all returns shall be shipped freight prepaid.  Collect shipments 
will not be accepted, but Harris will prepay return freight charges on 
repaired and replaced products found to be actually defective.

The warranty provided herein does not cover damage, defects, malfunctions or 
service failures caused by:

 (1) Customer's failure to follow Harris' environmental, installation, operation
or maintenance specifications or instructions; 

 (2) Modifications, alterations or repairs made other than by Harris;

 (3) Customer's mishandling, abuse, misuse, negligence, or improper storage,
servicing or operation of the Equipment (including without limitation use with
incompatible equipment); or

(4)  Power failures, surges, fire, flood, accident, actions of third parties or
     other like events outside Harris' control.  Repairs necessitated during the
     warranty period  by any of the foregoing causes may be made by Harris, and
     the Customer shall pay Harris' standard charges for time and materials,
     together with all shipping  and handling charges arising from such repairs.
     

     B)       SOFTWARE WARRANTY AND LICENSE

     (1)  LICENSE.  Harris grants to Customer a non-exclusive, non-transferable
license to use the software and related documentation ("Software") provided
hereunder.  The Software may include software and documentation that are owned
by third parties and distributed by Harris under license from the owner.  If
Customer is a reseller of the software purchased under this agreement, this
license is assignable only to Customer's customer, subject to Harris' written
authorization and only if the end customer is bound in writing to the Terms and
Conditions of this license.  Customer shall retain a copy of such end Customer
Agreement for Harris' inspection.

   (2)  COPIES.  Customer shall not make any copies of the Software, except for
a single archival copy solely for internal purposes.

   (3)  CONFIDENTIALITY.  Customer shall maintain the confidentiality of the
Software and shall not sub-license, sell, rent, disclose, make available, or
otherwise communicate the Software to any other person, or use the Software
except as expressly authorized in writing by Harris.

   (4)  TITLE.  The Software and all copies thereof will at all times remain
the sole and exclusive property of Harris or its licensor, as applicable, and
Customer shall obtain no title to the Software.

   (5)  COPYRIGHT.  Customer shall reproduce all copyright notices and any
other

                                                                             3
<PAGE>

proprietary legends on any copy of the Software made by Customer.

   (6)  ALTERATION.  Customer shall not modify, disassemble, or decompile the
Software.

   (7)  MEDIA.  If Customer sells or otherwise disposes of Customer owned
media on which the software is fixed, such media must be erased before any sale
or disposal.

   (8)  WARRANTY.  Harris does not warrant that the operation of the Software
will be error free.  Harris will use reasonable efforts to correct any defects
reported to Harris in writing within twenty-four (24) months of the date of
shipment, exclusive of defects caused by physical defects in Software disks due
to mishandling, operator error or interfacing other systems not approved by
Harris.

    c)   LIMITATIONS

LIABILITY OF HARRIS FOR BREACH OF ANY AND ALL WARRANTIES HEREUNDER IS EXPRESSLY
LIMITED TO THE REPAIR, REPLACEMENT OR REFUND OF THE PURCHASE PRICE OF DEFECTIVE
PRODUCTS AS SET FORTH IN THIS SECTION, AND IN NO EVENT SHALL HARRIS BE LIABLE
FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES BY REASON OF ANY BREACH OF
WARRANTY OR DEFECT IN MATERIALS OR  WORKMANSHIP.  HARRIS SHALL NOT BE
RESPONSIBLE FOR REPAIR, REPLACEMENT  REFUND OF PURCHASE PRICE OF PRODUCTS WHICH
HAVE BEEN SUBJECTED TO NEGLECT, ACCIDENT OR  IMPROPER USE,  OR WHICH HAVE BEEN
ALTERED BY OTHER THAN AUTHORIZED HARRIS PERSONNEL.  THE FOREGOING WARRANTIES ARE
IN LIEU OF ALL OTHER WARRANTIES WHETHER ORAL, WRITTEN, EXPRESSED, IMPLIED, OR
STATUTORY.  IN PARTICULAR, THE IMPLIED WARRANTIES OF FITNESS FOR PARTICULAR
PURPOSE AND MERCHANTABILITY ARE HEREBY DISCLAIMED AND SHALL NOT BE APPLICABLE 
EITHER FROM HARRIS OR ANY OTHER EQUIPMENT OR SOFTWARE MANUFACTURER. HARRIS'
WARRANTY OBLIGATIONS AND CUSTOMER'S REMEDIES THEREUNDER ARE SOLELY AND
EXCLUSIVELY AS STATED HEREIN. IN NO CASE SHALL HARRIS BE LIABLE FOR INDIRECT
KINDS OF DAMAGES, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL, AND 
CONSEQUENTIAL DAMAGES, OR LOSS OF CAPITAL, REVENUE, OR PROFITS. IN NO EVENT
SHALL HARRIS' LIABILITY TO CUSTOMER, OR ANY PARTY CLAIMING THROUGH CUSTOMER, BE
IN EXCESS OF THE ACTUAL SALES PRICE PAID BY CUSTOMER FOR ANY ITEMS SUPPLIED
HEREUNDER.

7.   TITLE AND RISK OF LOSS

Risk of loss for all Equipment sold under this Agreement shall pass to Customer
at time of delivery as defined herein.  Customer grants to Harris a security
interest in the Equipment covered by this Agreement in the amount of the unpaid
balance of the purchase price until payment in full of the purchase price at
which time title in the Equipment will pass in accordance with the terms and
conditions set forth herein.   A financing statement may be filed with the
appropriate public authorities and Customer agrees to sign any such financing
statements or other documents tendered to it by Harris from time to time to
protect Harris' security interest. 

8.   EXPORT AND RE-EXPORT RESTRICTIONS

Performance and delivery of the equipment, documents, services and Software sold
or delivered hereunder are subject to export control laws and regulations of the
United States and/or Canada, as applicable, and conditioned upon receipt of
required U.S. and/or Canadian Government licenses and approvals by Harris. 
Customers shall not export products or technical data delivered hereunder from
the United States or Canada without complying with regulations of the Bureau of
Export Administration of the United States Department of Commerce and/or the
Export Controls Division of the Canadian Department of Foreign Affairs and
International Trade, as applicable.  Customers shall not re-export the products
and technical data delivered hereunder from the country of delivery or to any
facility engaged in the design, development, stockpiling,

                                                                             4
<PAGE>

manufacturing or use of missile, chemical or biological weapons without fully 
complying with the regulations of the above United States and/or Canadian 
government agencies.

9.  EXCUSABLE DELAY

Harris shall be excused from performance under the Purchase Order and not be
liable to Customer for delay in performance attributable in whole or in part to
any cause beyond its reasonable control, including but not limited to, actions
or inactions of government whether in its sovereign or contractual capacity,
judicial action, war, civil disturbance, insurrection, sabotage, act of a public
enemy, labor difficulties or disputes, failure or delay in delivery by Harris'
suppliers or subcontractors, transportation difficulties, shortage of energy,
materials, labor or equipment, accident, fire, flood, storm or other act of God,
or Customer's fault or negligence.

In the event of an excusable delay, Harris shall make reasonable efforts to
notify Customer of the nature and extent of such a delay and Harris (i) will be
entitled to a schedule extension on at least a day-for-day basis, (ii) in the
event of Customer's fault or negligence, will be also entitled to an equitable
adjustment in the price of this contract.  Notwithstanding any other term
contained herein, in the event an excusable delay occurs and continues for a
period of ninety (90) days or longer, ART shall have the right to immediately
terminate this Agreement or any Purchase Order given pursuant to the Agreement
without further liability to Harris.

10.  TERM AND TERMINATION

This Agreement shall continue in effect for one (1) year from the date hereof at
which time it will terminate, unless terminated earlier pursuant to this Article
12.  Renewal is subject to mutual written agreement signed by both parties.

Cancellation of any Purchase Order hereunder will be accepted only upon the
specific written approval of Harris and is subject to standard Harris
cancellation charges of 25 % if cancellations is received 30 days after receipt
of order from ART,  provided however, that ART may cancel any Purchase Order
without the approval of Harris and without incurring cancellation charges if the
delivery of Products under such Purchase Order is delayed, or expected to be
delayed, by ninety (90) days or more from the original delivery date. 

In the event that Customer shall become liquidated, dissolved, bankrupt or
insolvent, or shall take any action to be so declared, or shall suffer any such
action brought by another, Harris shall have the right to terminate this
Agreement and all Purchase Orders immediately and may stop shipment of any
Products in transit.
        
Either party may terminate this Agreement immediately upon notice in writing to
the other party: 

     a)  if the other party shall breach any provision of this Agreement in any
material respect and such breach remains unremedied thirty (30) days after 
notice thereof from the non-breaching party; 

     b) in the event that the other party breaches any material term, condition
or covenant of the PCS Marketing Agreement referenced in Section 1 above and the
other party fails to cure any default or breach within thirty (30) days of
receipt of written notice of such breach from the non-breaching party; or 

     c)  in the event that the other party has caused the PCS Marketing
Agreement referenced in Section 1 above to be terminated.

                                                                             5
<PAGE>

         The right of termination provided herein is absolute and neither party
shall be liable to the other for damages or otherwise by reason of such
termination.

11.  INFRINGEMENT INDEMNIFICATION

Customer agrees to promptly notify Harris in writing of any notice, suit, or any
action against Customer based upon a claim that the Product infringes a U.S.
patent, copyright, trademark, or trade secret of a third party.  Harris will
defend at its expense any such action, except as excluded below, and shall have
full control of such defense including all appeals and negotiations, and will
pay all settlement costs, or damages awarded against Customer, but Harris shall
not be liable to Customer for special, incidental, indirect or consequential
damages.  In the event of such notice, suit or action, Harris will at its
expense procure for the Customer the right to continue using the product, or
modify the Product to render such non-infringing, or accept return and replace
such with substantially equivalent non-infringing equipment, or accept return of
the Product and refund or credit to Customer the amount of the original purchase
price, less a reasonable charge for depreciation and damage.

The preceding agreements by Harris in this section shall not apply to any
Product or portion thereof manufactured to specifications furnished by or on
behalf of Customer, or to any infringement arising out of the use of the Product
in combination with other equipment or software not furnished by Harris, or to
use in a manner not normally intended, or to any patent, copyright, trademark or
trade secret in which Customer, or subsidiary or affiliate thereof, has a direct
or indirect interest, or if customer has not provided Harris with prompt notice,
authority, information and assistance necessary to defend the action.  The
foregoing states the entire liability of Harris for patent, copyright, trademark
and trade secret infringements by the Product or portion thereof.

The rights and obligations of the parties under this Section shall survive
termination of this Agreement.

12.       TECHNICAL DATA AND INVENTION

Unless specifically agreed to by Harris and identified and priced in this
contract as a separate item or items to be delivered by Harris (and in that
event, except to the extent so identified and priced), the sale of goods
hereunder confers on Customer no right in, license under, access to, or
entitlement of any kind to any of Harris' technical data including but not
limited to design, process technology, software and drawings, or to Harris'
inventions (whether or not patentable) irrespective of whether any such
technical data or invention or any portion thereof arose out of work performed
under or in the course of this contract, and irrespective of whether Customer
has paid or is obligated to pay Harris for any part of the design and/or
development of the goods.

Harris shall not be obliged to safeguard or hold confidential any data whether
technical or otherwise, furnished by Customer for Harris' performance of this
contract unless (and only to the extent that) Customer and Harris have entered
into a separate written confidential agreement. 

Customer shall not violate Harris' copyright of documents or software or
disclose Harris' confidential or proprietary data to others without Harris
written permission.

13.  ASSIGNMENT

Neither party may assign this agreement in whole or in part without the prior
written consent signed by an officer of the other party.  Such consent shall not
be unreasonably withheld.

                                                                             6
<PAGE>


14.  GOVERNING LAW, VENUE, AND JURISDICTION

This Agreement will be governed by and construed in accordance with the laws of
the State of California.  The parties agree that any action to enforce any
provision of this Agreement or arising out of or based upon this Agreement or
the business relationship between Harris and Customer will be brought in a local
or Federal court of competent jurisdiction in the State of California.

15.  ENFORCEABILITY

If any provision of this Agreement shall be held to be invalid, illegal or
unenforceable, the validity, legality or enforceability of the remaining
provisions shall in no way be affected or impaired.

16.  NOTICES

All notices shall be in writing and shall be delivered or sent by registered,
certified or express mail, return receipt requested, to the addresses indicated
in this Agreement or to such other addresses as the parties shall specify by
giving notice pursuant hereto.  A copy of all notices shall be sent to Harris
Corporation, Farinon Division, 330 Twin Dolphin Drive, Redwood Shores, CA 94065,
Attention:  Manager of Contracts, and to W. Theodore Pierson, Jr. Executive Vice
President and General Counsel, 1667 K Street, NW, Suite 801 Washington, DC
20006.

17.  INDEMNIFICATION

     a)   INDEMNIFICATION OF ART BY HARRIS  

Harris shall indemnify ART against, and hold ART harmless from all liabilities,
demands, claims, damages, losses, demands, costs,  judgments and expenses
(including reasonable attorneys' fees) arising out of or in connection with
arising out of or relating to the installation, operation, or use of the
Products for personal injury or damage to tangible property, caused by the
negligent acts or omissions of Harris or Harris's employees, agents or invitees.
In no event shall ART's employees, agents or invitees be deemed to be employees,
agents or invitees of Harris.

     b)   INDEMNIFICATION OF HARRIS BY ART  

ART shall indemnify Harris against, and hold Harris harmless from all
liabilities, demands, claims, damages, losses, demands, costs,  judgments and
expenses (including reasonable attorneys' fees) to the extent they arise out of
or are in connection with or relate to the installation, operation, or use of
the Products for personal injury or damage to tangible property, caused by the
negligent acts or omissions of ART or ART's employees, agents or invitees.  In
no event shall Harris's employees, agents or invitees be deemed to be employees,
agents or invitees of ART.
 
     c)   DUTY TO NOTIFY AND ASSIST  

If any claim arises to which the provisions of this Section may be applicable,
the party against whom such claim is made shall notify the other party
immediately upon learning of the claim.  If it appears that the other party may
be obligated to provide indemnification as a result of such claim, the other
party, in its discretion, may settle or compromise the claim

                                                                             7
<PAGE>

or retain counsel of its own choosing and control and prosecute the defense 
against such claim. In no event shall the party against whom the claim is 
asserted have the right to pay, settle or compromise such claim without the 
prior written consent of the party who may be obligated to indemnify under 
this Section and the parties hereto agree that they will not unreasonably 
withhold consent to such consent to payment, settlement or compromise.  The 
party against whom the claim is asserted shall provide the other party such 
assistance as may be reasonable in the defense and disposition of such claim. 

The rights and obligations of the parties under this Section shall survive
termination of this Agreement.

18.  LIMITATION OF LIABILITY

NOTWITHSTANDING ANY OTHER PROVISIONS OF THIS CONTRACT, UNDER NO CIRCUMSTANCES
SHALL HARRIS BE LIABLE TO CUSTOMER OR ANY THIRD PARTY CLAIMING UNDER CUSTOMER
FOR SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES, AS A RESULT OF A
BREACH OF ANY PROVISION OF THIS CONTRACT.  

19.  ENTIRE AGREEMENT

This Agreement supersedes all previous communications, transactions, and
understandings, whether oral, or written, and constitutes the sole and entire
agreement between the parties pertaining to the subject matter hereof.  No
modification or deletion of, or addition to these terms shall be binding on
either party unless made in writing and signed by a duly authorized
representative of both parties.

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


ADVANCED RADIO TELECOM CORPORATION

BY: /s/ Charles H. Menatti
   ______________________________

NAME:  /s/ Charles Menatti
       ___________________________

TITLE: V.P. Bus. Development
       ___________________________


HARRIS CORPORATION
FARINON DIVISION

BY:  /s/ J. Michael Slattery
    ______________________________

NAME: /s/ J. Michael Slattery
     ___________________________ 

TITLE: Division Controller
      ___________________________



                                            8 


<PAGE>
 






        [Annexes A, B and C omitted due to confidential treatement]



<PAGE>

                            PCS MARKETING AGREEMENT

THIS PCS MARKETING AGREEMENT ("Agreement") is entered into as of the 26th day 
of April, 1996 by and between Advanced Radio Telecom Corporation, a Delaware
corporation with offices located at 500 108th Avenue NE, Suite 2600, Bellevue,
WA 98006 ("ART"), and Harris Corporation, Farinon Division, a Delaware
corporation, with offices located at 330 Twin Dolphin Drive, Redwood Shores, CA
94065 ("Harris").
 
WHEREAS ART and Harris wish to develop new business opportunities in the
emerging Personal Communications Services ("PCS") marketplace for the provision
of both 38 GHz services and equipment; and  

WHEREAS ART has acquired authorizations at 38 GHz in certain markets in the
United States; and 

WHEREAS Harris desires to include ART's 38 GHz services   Right-of -Use of its
38 Ghz frequencies and associated coordination services as well as installation
and network monitoring, field services in conjunction with its sales of 38 GHz
equipment to the PCS marketplace;

WHEREAS Harris desires, as a secondary approach to direct sales of it's
microwave radio , to promote ART's leased services to the PCS market.  
  
NOW THEREFORE, in consideration of the premises and the mutual representations,
warranties, covenants and agreements hereinafter set forth, ART and Harris,
intending to be legally bound, hereby agree as follows:

1.0     EFFECTIVE DATE; RELATED SUPPLY AGREEMENT.  The Effective Date of this
Agreement shall be the date of execution by the parties, provided, however, that
the rights and obligations of the parties hereunder shall not become effective
unless and until the parties have executed a definitive supply agreement
("Purchase Agreement") for 38 GHz equipment as contemplated by Version 2 of a
Letter of Intent executed by ART and Harris and dated February 22, 1996. 

2.0    TERM OF AGREEMENT, RENEWAL AND TERMINATION.  Subject to the provisions of
Section 1.0 hereof, the term of this Agreement begins on the Effective Date and
shall continue in effect for one (1) year from the Effective Date ("Initial
Term").  The Agreement shall automatically renew after the Initial Term for
successive periods of one (1) year (each successive period a "Renewal Term")
unless one of the parties gives written notice not to renew no later than sixty
(60) days prior to the scheduled date of expiration of the Initial Term or any
subsequent Renewal Term. The parties acknowledge and agree that failure of
either party to give notice of termination shall give rise to a conclusive
presumption that the Agreement is to be renewed pursuant to this Section 2.0.  A
party may terminate this Agreement: 

       (a) upon notice in writing delivered to the other party, in the event
that the other party breaches any material term, condition or covenant hereof if
the other party fails to cure any default or breach within thirty (30) days of
receipt of written notice of such breach from the non-breaching party;

                                      1

<PAGE>

     (b) upon notice in writing delivered to the other party, in the event that
the other party breaches any material term, condition or covenant of the
Purchase Agreement referenced in Section 1.0 above and the other party fails to
cure any default or breach within thirty (30) days of receipt of written notice
of such breach from the non-breaching party; or 

       (c)  upon notice in writing delivered to the other party in the event
that the other party has caused the Purchase Agreement referenced in Section 1.0
above to be terminated; or  

       (d) at any time by providing ninety (90) days written notice to the other
party.

      2.1 PROVISIONS OF TERMINATION FOR OPERATING FREQUENCIES:  In the event of
termination of this agreement under the terms and conditions outlined in section
2.0, all Right of Use of ART's frequencies purchased from Harris prior the
effective date of the termination shall remain in effect for the time period
agreed in section 3.0. Harris agrees, for the remaining period that the Right of
Use is in effect, to pay to ART the annual coordination fees specified in
section 5.2. 

3.0    RIGHTS GRANTED TO HARRIS.  During the Initial Term and any Renewal Term
of this Agreement, and subject to the terms and conditions of this Agreement,
ART hereby grants to Harris a non-transferable non-exclusive right to use
("Right of Use") 38 GHz authorizations which ART owns or otherwise controls for
a period not exceeding 10 years. (as shown in Exhibit A attached hereto).  Not
withstanding the forgoing, Harris may transfers to the PCS End User the rights
contained in this paragraph, provided that the PCS End User agrees in writing to
the terms and conditions of this agreement that are applicable to it.  The Right
of Use granted to Harris hereunder shall be limited to Harris's 38 GHz equipment
sales to the PCS market.  Harris covenants and agrees that,  during the term of
this Agreement, it will not offer or promote alternate 38 GHz T1 leased services
from any other provider of 38 GHz service to any PCS accounts identified in
Exhibit B hereto.  In consideration for the grant of the Right of Use, Harris
shall pay ART the fees identified in Section 5.1 hereof. 

        3.1  COVENANT WITH RESPECT TO RIGHT OF USE.  ART covenants and agrees to
take all necessary action to comply with FCC rules and regulations governing the
Right of Use granted to Harris hereunder.  ART shall be responsible for
resolving all regulatory and channel conflict issues concerning the Right of
Use.

4.0    SERVICES PROVIDED BY ART.  

       4.1  FREQUENCY COORDINATION.   In addition to the Rights of Use granted
to Harris under Section 3.0 hereof, ART shall also provide Harris with channel
conflict assessment services ("Frequency Coordination") for links sold by Harris
to the PCS market.  Harris shall notify ART at least 15 working days prior to
each shipment made under this agreement, and ART shall be solely responsible for
Frequency Coordination and provide to Harris the frequency assignment within 5
business days of Harris notification to ART, including the assignment of the
frequency to be used by the end-user and avoidance of channel conflicts.  In
consideration for these services, Harris shall pay ART the fees identified in
Section 5.2 hereof.

       4.2  INSTALLATION AND NETWORKING MONITORING, FIELD SERVICE/RESTORAL   In
addition to the Rights of Use granted to Harris under Section 3.0 hereof, ART
shall also provide Harris installation and network monitoring, field
service/restoral  services as defined in EXHIBIT E and EXHIBIT F, respectively
hereto.  In connection with the provision of such network monitoring, field
service/restoral  and installation services, Harris shall provide ART with
installation and  workmanship standards training, as identified in EXHIBIT D
hereto, at no charge to ART.

                                      2


<PAGE>

       4.3  LIMITED WARRANTY:  ART warrants that the installation, Network 
Monitoring and Field Service/Restoral services to be provided by ART pursuant 
to this Agreement will be performed in a good and substantial workmanlike 
manner in accordance with the performance requirements hereunder, generally 
prescribed industry standards and, when applicable, in accordance with 
manufacturers instructions and specifications.  The warranty granted under 
Section 4.3 with respect to ART's Installation services shall be for a period 
of one (1) year from the date of Installation of any equipment.

       4.4  LIMITATION OF LIABILITY:  OTHER THAN AS SET FORTH IN SECTION 4.3 
HEREIN, ART MAKES NO WARRANTIES OF ANY KIND WITH RESPECT TO THIS AGREEMENT 
WHETHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES 
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR CONFORMITY TO ANY 
REPRESENTATION OR DESCRIPTION.  EXCEPT FOR CREDITS FOR OUTAGES AS DESCRIBED 
IN SECTION 11, ART SHALL NOT BE LIABLE FOR ANY CLAIM OF ANY KIND, INCLUDING, 
BUT NOT LIMITED TO, ACTIONS, DAMAGES, DEMANDS, JUDGMENTS, LOSSES, COSTS, 
EXPENSES, LIABILITIES, AND LOSS OF MONIES ARISING OUT OF THIS AGREEMENT OR 
THE PERFORMANCE THEREOF, WHETHER BASED ON CONTRACT, WARRANTY, TORT INCLUDING 
NEGLIGENCE, MISTAKE, ERROR, MISCONDUCT, INTERRUPTION, DELAY, DEFECT OR 
OTHERWISE OF ART, ITS EMPLOYEES, AGENTS, CONTRACTORS, OR SUB-CONTRACTORS, OR 
AFFILIATED COMPANIES, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL, 
CONSEQUENTIAL, INDIRECT, EXEMPLARY OR PUNITIVE DAMAGES, LOSS OF REVENUE OR 
PROFIT, LOSS OF USE OF ANY PROPERTY, COST OF SUBSTITUTE PERFORMANCE, 
EQUIPMENT OR SERVICES, COST OF CAPITAL DOWNTIME COSTS AND CLAIMS OF THE 
CUSTOMER FOR DAMAGES. 

       4.5  EFFECT OF TARIFFS:  SERVICES SHALL BE PROVIDED BY ART TO HARRIS
PURSUANT TO THE TERMS AND CONDITIONS SET FORTH HEREIN, AND IN THE APPLICABLE
TARIFFS ON FILE WITH THE FEDERAL COMMUNICATIONS COMMISSION AND RELEVANT STATE
UTILITY COMMISSIONS.  THE TERMS AND CONDITIONS OF THOSE TARIFFS, AS AMENDED FROM
TIME TO TIME, CONTROL THE PARTIES' OBLIGATIONS NOTWITHSTANDING ANYTHING TO THE
CONTRARY HEREIN.

                                      3


            [Section 5 omitted due to confidential treatement]

<PAGE>

6.0    BETA TRIALS.  ART shall provide Harris Rights of Use and Frequency
Coordination Services for a period of sixty (60) days without any obligation of
Harris to pay a Rights of Use fee for the frequency channels solely for the
purpose of conducting two (2) BETA trials, with each trial consisting of one
Harris client and one link .  The specific location of these trials shall be
subject to the mutual agreement of ART and Harris.  All costs associated with
installation, including, but not limited to, site specific equipment and
materials and field service during the BETA trial period shall be borne by
Harris.  ART shall bear its own personnel and travel-related costs associated
with the site survey and installation in connection with the two BETA trials.

7.0    SALES FORECAST:  Harris shall provide ART with 38 GHz radio link sales
forecasts, which shall serve as a basis to establish pricing levels outlined in
section 5.1.  Harris' initial forecast is attached hereto as EXHIBIT C.  Unless
otherwise agreed by the parties, future  forecasts shall be provided by Harris
on a quarterly basis.

8.0    RELATIONSHIP OF THE PARTIES; NO AGENCY OR PARTNERSHIP.  Each party is an
independent business entity and will perform its obligations hereunder as an
independent contractor.  It is agreed and understood that neither party is an
agent, employee or legal representative of the other, and has no authority to
bind the other in any way.  Nothing in this Agreement shall be deemed to
constitute ART and Harris as partners, joint ventures, or otherwise associated
in or with the business of the other, and neither party shall be liable for the
debts, accounts, obligations or other liabilities of the other party, its agents
or employees.  Neither party is authorized to incur debts or other obligations
of any kind on the part of or as agent for the other except as may be
specifically authorized herein. 

9.0   INTELLECTUAL PROPERTY.  Except as may be expressly authorized by this
Agreement or by separate written agreement between the parties, nothing herein
shall grant  either party a license to use the trademarks, service marks or
trade names of the other party, its affiliates and/or suppliers or licensers. 
All intellectual property shall remain the exclusive property of the party
owning or controlling such intellectual property.

                                      4


<PAGE>

10.0   CONFIDENTIALITY AND NON-DISCLOSURE.  In connection with this Agreement,
each party may disclose or otherwise make available certain data or information
to the other party, which data or information the disclosing party considers to
be confidential and proprietary.  As used herein, "Confidential Information,"
means any non-public information, including customer and vendor lists, business
plans and proposals, financial information, marketing information, problem
solving methods, implementation steps, know-how, technology, trade secrets and
drawings and renderings related to each party's ongoing and proposed businesses,
products and services (including installation and training services) which is
being provided or which has been provided to the receiving party by the
disclosing party, or which is obtained by the receiving party from its meetings
and contacts with the disclosing party, or any information derived by receiving
party from information so provided or obtained.  Confidential Information
includes all written or electronically recorded materials identified and marked
as confidential or proprietary or which on their face appear to be confidential
or proprietary, and oral disclosures of Confidential Information by the 
 
disclosing party which are identified as confidential or proprietary at the time
of such oral disclosure.  Confidential Information does not include any of the
following:  (a) information that is in or becomes part of the public domain
without violation of this Agreement by the receiving party; (b)  information
that was known to or in the possession of  the receiving party on a non-
confidential basis prior to the disclosure thereof to the receiving party by the
disclosing party; (c)  information that was developed independently by the
receiving party's employees, which employees have had no access to the
Confidential Information;   (d) information that is disclosed to the receiving
party by a third party under no obligation of confidentiality to the disclosing
party and without violation of this Agreement by the receiving party; or (e)  is
authorized by the disclosing party in writing for disclosure or release by the
receiving party. The parties agree: (a) to treat and keep as confidential and
proprietary all Confidential Information disclosed by the other party; (b) to
advise each employee to whom any Confidential Information is to be made
available of the confidential nature of such Confidential Information and of the
terms of this Agreement; (c) to promptly return to the disclosing party (or its
designees), upon the disclosing party's request, all Confidential Information
and all copies thereof. The receiving party shall have discharged its obligation
to safeguard the Confidential Information received hereunder only if it has
exercised the same degree of care as it uses to protect its own proprietary
information of like importance. 

11.0   INDEMNIFICATION.

       11.1 INDEMNIFICATION OF ART BY HARRIS.  Harris shall indemnify ART
against, and hold ART harmless from all liabilities, demands, claims, damages,
losses, demands, costs, judgments and expenses (including reasonable attorneys'
fees) arising out of or in connection with this Agreement for personal injury or
damage to tangible property, or in connection with the use or exercise by Harris
of the Right of Use, caused by the negligent acts or willful omissions of Harris
or Harris's employees, agents or invitees.  In no event shall ART's employees,
agents or invitees be deemed to be employees, agents or invitees of Harris.

       11.2   INDEMNIFICATION OF HARRIS BY ART.  ART shall indemnify Harris
against, and hold Harris harmless from all liabilities, demands, claims,
damages, losses, demands, costs, judgments and expenses (including reasonable
attorneys' fees) arising out of or in connection with this Agreement for
personal injury or damage to tangible property, or in connection with the use or
exercise by Harris of the Right of Use, caused by the negligent acts or willful
omissions of ART or ART's employees, agents or invitees.  In no event shall
Harris's employees, agents or invitees be deemed to be employees, agents or
invitees of ART.

                                      5

<PAGE>

       11.3 DUTY TO NOTIFY AND ASSIST.  If any claim arises to which the
provisions of this Section may be applicable, the party against whom such claim
is made shall notify the other party immediately upon learning of the claim.  If
it appears that the other party may be obligated to provide indemnification as a
result of such claim, the other party, in its discretion, may settle or
compromise the claim or retain counsel of its own choosing and control and
prosecute the defense against such claim.  In no event shall the party against
whom the claim is asserted have the right to pay, settle or compromise such
claim without the prior written consent of the party who may be obligated to
indemnify under this Section, and the parties hereto agree that they will not
unreasonably withhold consent to such consent to payment, settlement or
compromise.  The party against whom the claim is asserted shall provide the
other party such assistance as may be reasonable in the defense and disposition
of such claim.
  
NOTICES.  All notices, demands or other communications which are required or may
be given under this Agreement shall be given or made in writing, and shall  be
delivered personally or by overnight air courier or first class certified or
registered mail, return receipt requested and postage prepaid to the persons and
addresses listed below, or to such other persons and/or address as the party to
whom notice is to be given has furnished to the other party. Each such notice,
demand or other communication shall, simultaneously with its being delivered to
the courier or messenger for delivery or placed in the mail, be sent by
facsimile or comparable electronic means.  All notices and other communications
hereunder shall  be deemed to have been given: (a) on the date of delivery if
personally delivered or, if not delivered on a business day, the first business
day thereafter; (b)  on the first business day after the date sent if sent by
overnight air courier; or (c) on the fifth business day after the date sent if
sent by mail.

If to ART:                                        If to Harris: 
Steven D. Comrie                                  Don Fenn
President                                         Contracts Manager
500-108th Ave NE, Ste 2600                        330 Twin Dolphin Drive
Bellevue, WA 98004                                Redwood Shores CA, 94065
206-688-8700                                      415-594-3000

Copy to:
W. Theodore Pierson, Jr.
Executive Vice President and General Counsel
1667 K Street, NW, Ste 801
Washington, DC 20006
202-466-5278

13.0   SURVIVAL.  It is expressly agreed that the provisions of Sections 5, 10,
11, 12, 17 and 18 shall survive any termination of this Agreement and shall be
and remain valid, binding and enforceable after any such termination according
to their terms. 

14.0   ASSIGNMENT; BINDING EFFECT.  Neither party shall assign or transfer any
of its rights or obligations hereunder without the prior written consent of the
other party hereto.  Any attempted assignment without written consent will be
void.  This Agreement shall inure to the benefit of and shall be binding upon
the successors and assigns of the parties.

15.0   SEVERABILITY.  If any portion of this Agreement is held to be invalid by
a court of competent jurisdiction, that provision shall become ineffective and
unenforceable.  The parties agree that such invalidity shall not affect the
validity of the remaining portions of this Agreement, and further agree to
substitute for the invalid provision a valid provision that most closely
approximates the effect and intent of the invalid provision.

                                      6

<PAGE>

16.0   FORCE MAJEURE:  NEITHER PARTY SHALL BE LIABLE FOR DELAYS IN PERFORMANCE,
OR FAILURE TO PERFORM, THIS AGREEMENT OR ANY OBLIGATIONS HEREUNDER, WHICH ARE
ATTRIBUTABLE TO CAUSES BEYOND ITS REASONABLE CONTROL, INCLUDING BUT NOT LIMITED
TO FIRE, FLOOD, EPIDEMIC, EARTHQUAKE, ENVIRONMENTAL DAMAGE, ACT OF GOD,
LIGHTNING, PUBLLIC POWER FAILURE OR SURGE, EXPLOSION, STRIKE OR OTHER LABOR
DISPUTE, RIOT OR CIVIL DISTURBANCE, WAR OR ARMED CONFLICT, OR OTHER GOVERNMENTAL
ORDER OR REGULATION, OR ORDER OF ANY COURT OF COMPETENT JURISDICTION, OR ANY
OTHER SIMILAR OCCURRENCE NOT WITHIN ITS CONTROL.

17.0.   GOVERNING LAW.  The parties agree that this Agreement shall be
interpreted and construed both as to performance and validity in accordance with
and governed by the laws of the domestic laws of the State of Washington even if
its choice of law provisions are in conflict with this requirement. 

18.0.   DISPUTE RESOLUTION; ARBITRATION.  The parties agree that all 
disputes, claims or controversies between them arising out of or relating to 
this Agreement, and only if good faith attempt at resolution between parties 
fails, shall be settled by arbitration in accordance with the rules of the 
American Arbitration Association.  Decisions of the arbitration panel shall 
be based upon Washington State law, and the site of such arbitration shall be 
in King County, Washington. The arbitration panel shall consist of three 
arbitrators, one arbitrator to be selected by each party and the third 
arbitrator to be selected by the other two arbitrators.  Any decision 
rendered by the arbitration panel pursuant to this provision shall be 
concurred in by a majority of the members of the panel. Judgment may be 
entered by any court of competent jurisdiction.  Arbitration pursuant to this 
section shall be the exclusive means of resolving any dispute, claim or 
controversy arising hereunder.  Each party shall bear its own costs, 
including attorneys' fees, in connection with any proceeding brought under 
this Section.

19.0   REGULATORY APPROVAL.  The rights and obligations of the parties hereunder
are subject to any regulatory approvals which may be required, and this
Agreement may be terminated by either party if any governmental or regulatory
agency imposes rules or regulations affecting the relationship between the
parties in a material way. 

20.0    WAIVER OF BREACH.  The failure to enforce or to require the performance
at any time of any of the provisions of this Agreement by a party shall not be
construed to be a waiver of any other provisions by that party and shall not
affect either the validity of this Agreement or any part hereof or the right of
any party thereafter to enforce each and every provision of this Agreement.

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

22.0   PUBLICITY.  Each party shall consult with the other before issuing any
press release or otherwise making any statements to third parties with respect
to this Agreement or the transactions and relationships contemplated hereby and
shall not issue any press release or make any such statements prior to obtaining
the written consent of the other party, which consent shall not be unreasonably
withheld.
 
23.0   SECTION HEADINGS.  The section and sub-section headings contained herein
are for reference purposes only and shall not affect in any way the meaning or
interpretation of  any provision of this Agreement.

                                      7

<PAGE>

24.0   AUTHORITY.  Each party represents and warrants that it has full power and
authority to enter into and perform under this Agreement and that its delivery
of this Agreement has been duly authorized by all necessary corporate or other
action and that the person signing the Agreement on its behalf is duly
authorized to do so.   Each party further acknowledges that it has read and
understands this Agreement and agrees to be bound by all of its terms,
conditions and provisions.

25.0   ENTIRE AGREEMENT; MODIFICATION.   This Agreement and all Exhibits,
Appendices and Attachments hereto constitutes the entire agreement between the
parties and supersedes all prior representations, agreements, understandings and
arrangements, oral or written, between the parties with respect to the subject
matter hereof.  All Recitals, Background and Statements of Purpose are expressly
excluded from this Agreement.  This Agreement allocates the risks of loss among
the parties, which allocation is reflected in the charges and terms and
conditions set forth herein.  This Agreement may not be released, discharged,
amended, or modified in any way except by a writing that expressly refers to
this Agreement and is executed by all parties hereto IN WITNESS WHEREOF,  the
parties have duly executed this Agreement as of the date first above written.

ADVANCE RADIO TELECOM CORPORATION          HARRIS CORPORATION


By: /s/ Charles H. Menatti               By: /s/ J. Michael Slattery
   ________________________                 _________________________

Print                                    Print
Name:  Charles Menatti                   Name:  J. Michael Slattery
      _______________________                  _______________________

Title: V.P. Bus. Development             Title: Division Controller
      ______________________                   ______________________

                                      8

<PAGE>

                            PCS MARKETING AGREEMENT

                             BETWEEN ART AND HARRIS

                               LIST OF EXHIBITS



EXHIBIT A      LIST OF AUTHORIZATIONS UNDER ART'S CONTROL AT 38 GHZ.


EXHIBIT B      LIST OF HARRIS PCS TARGET ACCOUNTS.


EXHIBIT C      HARRIS SALES FORECAST.


EXHIBIT D      OUTLINE OF HARRIS TRAINING ON INSTALLATION AND WORKMANSHIP
               STANDARDS.


EXHIBIT E      DEFINITION OF ART'S INSTALLATION SERVICES, PROCEDURES AND
               SCHEDULE.


EXHIBIT F      DEFINITION OF ART'S NETWORK MONITORING SERVICES AND PROCEDURES.

                                      9

<PAGE>


                                 EXHIBIT A

               LIST OF AUTHORIZATION UNDER ART'S CONTROL AT 38GHZ


MARKET                            CHANNELS
- ------                            --------

1    Albany                       13       NY 
2    Albany                       1,14     NY 
3    Albuquerque                  2        NM 
4    Allentown                    1,14     PA 
5    Altoona                      1,14     PA 
6    Anchorage                    2        AK 
7    Atlanta                      1        GA 
8    Austin                       2        TX 
9    Baltimore                    6        MD 
10   Baltimore                    1,14     MD 
11   Baton Rouge                  2        LA 
12   Billings                     1        MT 
13   Binghamton                   1,14     NY 
14   Birmingham                   4        AL 
15   Boston (No.)                 1,14     MA 
16   Boston (So.)                 1,14     MA 
17   Bridgeport                   1,14     NH 
18   Buffalo                      10       NY 
19   Buffalo                      1,14     NY 
20   Canton                       2        OH 
21   Charleston                   4        SC 
22   Charleston                   1        WV 
23   Chicago                      1        IL 
24   Cincinnati                   6        OH 
25   Cleveland                    1        OH 
26   Columbus                     6        OH 
27   Corning                      1,14     NY 
28   Dallas                       1        TX 
29   Dayton                       6        OH 
30   Denver                       1        CO 
31   Des Moines                   5        IA 
32   Eugene                       3        OR 
33   Eureka                       4        CA 
34   Fairbanks                    4        AK 
35   Grand Rapids                 7        MI 
36   Greensboro                   14       NC 
37   Harris                       1,14     PA 
38   Hartford                     2        CT 
39   Hartford                     1,14     CT 

                                         10

<PAGE>

                                      EXHIBIT A
                                       Page 2


40   Honolulu                     4        HI 
41   Houston                      1        TX 
42   Huntington                   2        WV 
43   Indianapolis                 2        IN 
44   Jackson                      4        MS 
45   Jackson                      14       MS 
46   Juneau                       6        AK 
47   Kansas City                  1        MO 
48   Kingston                     1,14     NY 
49   Knoxville                    8        TN 
50   Las Vegas                    4        NV 
51   Lincoln                      4        NE 
52   Lorain                       1        OH 
53   Louisville                   6        KY 
54   Madison                      2        WI 
55   Memphis                      2        TN 
56   Miami                        1        FL 
57   Minneapolis                  6        MN 
58   Mobile                       8        AL 
59   Nashville                    12       TN 
60   New Orleans                  1        LA 
61   New York  - Long Island      1,14     NY 
62   New York (Manhattan)         13       NY 
63   New York (North)             1,14     NY 
64   New York (South)             1,14     NY 
65   Newark North                 1,14     NJ 
66   Newark South                 1,14     NJ 
67   Norfolk                      4        VA 
68   Oklahoma City                1        OK 
69   Ogden                        4        UT 
70   Pensacola                    3        FL 
71   Philadelphia                 1,14     PA 
72   Phoenix                      1        AZ 
73   Pittsburgh                   1,14     PA 
74   Portland                     2        OR 
75   Providence                   1,14     RI 
76   Reno                         1        NV 
77   Richmond                     4        VA 
78   Rochester                    2        NY 
79   Rochester                    1,14     NY 

                                         11

<PAGE>

                                      EXHIBIT A
                                       Page 3

80   Sacramento                   9        CA 
81   Salt Lake City               1        UT 
82   San Antonio                  11       TX 
83   San Diego                    6        CA 
84   San Jose                     9        CA 
85   Scranton                     3        PA 
86   Scranton                     1,14     PA 
87   Seattle                      1        WA 
88   Shreveport                   1        LA 
89   Spokane                      4        WA 
90   Springfield                  1,14     MA 
91   St. Louis                    1        MO 
92   Stamford                     1,14     CT 
93   Syracuse                     1,14     NY 
94   Tacoma                       1        WA 
95   Trenton                      1,14     NJ 
96   Tucson                       1        AZ 
97   Utica-Rome                   1,14     NY 
98   Washington                   6        DC 
99   Washington                   1,14     DC 
100  White                        1,14     NY 
101  Wichita                      3        KS 
102  Wilmington                   3        DE 
103  Wilmington                   1,14     DE 
104  Worcester                    1,14     MA 
105  York                         1        PA

                                         12


<PAGE>

                                    EXHIBIT A

                         STOCK OPTION VESTING SCHEDULE


                Shares Covered                        Date of
                   by Option                          Vesting
                --------------                        -------

                    100,000                        April 26, 1996

                    100,000                        April 26, 1997

                    100,000                        April 26, 1998



<PAGE>







               [Exhibits B, C, D, E and F omitted due to
                     to confidential treatement]

<PAGE>
                                                                      EXHIBIT 11
 
                          ADVANCED RADIO TELECOM CORP.
               COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
 
<TABLE>
<CAPTION>
                                                            MARCH 28, 1995
                                                               (DATE OF              YEAR ENDED DECEMBER 31, 1995
                                                              INCEPTION)      ------------------------------------------
                                                                  TO           HISTORICAL                    PRO FORMA
                                                          DECEMBER 31, 1995     COMBINED       PRO FORMA    AS ADJUSTED
                                                          ------------------  -------------  -------------  ------------
<S>                                                       <C>                 <C>            <C>            <C>
Net loss before fixed charges...........................    $    2,893,238    $   3,041,430  $   3,292,428   $
 
Deduct:
  Interest expense......................................            87,835          186,297      1,674,002
  Amortization of deferred financing charges............          --                  7,116        138,522
                                                          ------------------  -------------  -------------  ------------
 
Net loss................................................    $    2,981,073    $   3,234,843  $   5,104,952   $
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
 
Fixed charges:
  Interest expense......................................    $       87,835    $     186,297  $   1,674,002
  Amortization of deferred financing charges............          --                  7,116        138,522
                                                          ------------------  -------------  -------------  ------------
Fixed charges...........................................    $       87,835    $     193,413  $   1,812,524   $
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
 
Deficiency of net losses to cover fixed charges.........    $    2,981,073    $   3,234,843  $   5,104,952
                                                          ------------------  -------------  -------------  ------------
                                                          ------------------  -------------  -------------  ------------
</TABLE>
 
                       ADVANCED RADIO TECHNOLOGIES CORP.
                COMPUTATION OF RATIO OF LOSSES TO FIXED CHARGES
 
<TABLE>
<CAPTION>
                                                             AUGUST 23, 1993
                                                           (DATE OF INCEPTION)
                                                                   TO               YEAR ENDED          YEAR ENDED
                                                            DECEMBER 31, 1993   DECEMBER 31, 1994   DECEMBER 31, 1995
                                                           -------------------  ------------------  ------------------
<S>                                                        <C>                  <C>                 <C>
Net loss before fixed charges............................       $   6,594          $    124,245       $    1,162,077
 
Deduct:
  Interest expense.......................................          --                     4,375               98,462
  Amortization of deferred financing charges.............          --                   --                     7,116
                                                                  -------            ----------     ------------------
 
Net loss.................................................       $   6,594          $    128,620       $    1,267,655
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
 
Fixed charges:
  Interest expense.......................................       $  --              $      4,375       $       98,462
  Amortization of deferred financing charges.............                                                      7,116
                                                                  -------            ----------     ------------------
Total fixed charges......................................       $  --              $      4,375       $      105,578
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
 
Deficiency of loss to cover fixed charges................       $   6,594          $    128,620       $    1,267,655
                                                                  -------            ----------     ------------------
                                                                  -------            ----------     ------------------
</TABLE>
 
<PAGE>
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
<C>            <S>                                                                                        <C>
        1-1    Underwriting Agreement (to be filed by amendment)........................................
        2-1    Second Amended and Restated Certificate of Incorporation and Restated and Amended By-laws
                of Registrant.(1).......................................................................
        4-1    Specimen of Common Stock Certificate (to be filed by amendment)..........................
        4-2    (a) Indenture (to be filed by amendment).................................................
               (b) Specimen of Senior Discount Note (See Exhibit 4-2(a))................................
        5-1    Opinion and Consent of Hahn & Hessen LLP, counsel for the Registrant, with respect to the
                Registrant's Common Stock and the Notes (to be filed by amendment)......................
        9-1    (a) Voting Trust Agreement (to be filed by amendment)....................................
               (b) Form of Trustee Indemnification Agreement (to be filed by amendment).................
       10-1    Employment and Consulting Agreements.....................................................
               (a) Vernon L. Fotheringham, dated December 16, 1995.(1)..................................
               (b) Steven D. Comrie, dated February 2, 1996.(1).........................................
               (c) W. Theodore Pierson Jr., dated May 8, 1995 and effective January 1, 1995.(1).........
               (d) I. Don Brown, dated February 16, 1996.(1)............................................
               (e) Charles Menatti, dated March 8, 1996.(1).............................................
               (f) James D. Miller, dated February 1, 1996.(1)..........................................
               (g) Thomas A. Grina, dated April 26, 1996................................................
       10-2    Amended and Restated Certificate of Incorporation and By-laws of ART Corp.(1)............
       10-3    Form of Director Indemnification Agreement.(1)...........................................
       10-4    (a) Registrant's 1995 Stock Option Plan, as amended.(1)..................................
               (b) Form of Stock Option Agreement.(1)...................................................
       10-5    (a) Registrant's 1996 Non-Employee Directors Automatic Stock Option Plan.................
               (b) Form of Stock Option Agreement.......................................................
       10-6    Stock Option Agreements..................................................................
               (a) Comrie Non-Qualified Stock Option Agreement.(1)......................................
               (b) Comrie Incentive Stock Option Agreement.(1)..........................................
       10-7    Management Consulting Agreement with Landover Holdings Corporation, dated November 13,
                1995.(1)................................................................................
       10-8    (a) ART West Joint Venture Agreement dated April 4, 1995, with Extended Communications,
                   Inc.(1)..............................................................................
               (b) Put/Call Agreement dated October 1, 1994, with Extended Communications, Inc.(1)......
               (c) Services Agreement dated October 1, 1994, with Extended Communications, Inc.(1)......
               (d) Amendment dated April 4, 1995 to the Put/Call Agreement dated October 1, 1994, with
                   Extended Communications, Inc.(1).....................................................
       10-9    (a) Put/Call Agreement dated September 1, 1994 with DCT Communications, Inc.(1)..........
               (b) Services Agreement dated September 1, 1994 with DCT Communications, Inc.(1)..........
               (c) Terms Sheet dated April 26, 1996 with DCT.(1)........................................
      10-10    (a) Asset Purchase Agreement dated April 4, 1995 with EMI Communications
                   Corporation.(1)......................................................................
               (b) $1,500,000 Nonnegotiable and Nontransferable Promissory Note(1)......................
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
               (c) Maintenance Agreement dated November 14, 1995 with EMI Communications
                   Corporation.(1)......................................................................
<C>            <S>                                                                                        <C>
               (d) Agreement dated November 14, 1995 with EMI Communications Corporations.(1)...........
      10-11    38 GHz Radio Links Purchase Agreement dated August 11, 1995 with P-Com, Inc.
                (Confidential treatment requested for certain terms).(1)................................
      10-12    (a) Agreement dated May 25, 1995 with Telecom One (Confidential treatment requested for
                   certain terms).(1)...................................................................
               (b) Services Agreement dated April 24, 1996 with Telecom One.(1).........................
      10-13    Letter of Intent dated November 20, 1995 with GTE.(1)....................................
      10-14    Software License Agreement dated March 29, 1996 with GTE.(1).............................
      10-15    Agreement dated July 12, 1995 with Southeast Research Partners, Inc.(1)..................
      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.(1)..............................................................................
      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.(1)........................................................
      10-18    (a) Purchase Agreement dated April 21, 1995 with Landover Holdings Corporation.(1).......
               (b) Letter Agreement dated May 8, 1995 with the Demetrees, ART Corp., and Landover
                   Holdings Corporation.(1).............................................................
               (c) Letter Agreement dated November 13, 1995 with ART Corp., E2-2 Holdings, L.P. and the
                   Demetrees.(1)........................................................................
      10-19    Restated and Amended Stockholders' Agreement dated February 2, 1996 with ART Corp. and
                the stockholders of each of ART Corp. and the Company.(1)...............................
      10-20    Restated and Amended Registration Rights Agreement dated February 2, 1996 with ART Corp.
                and the stockholders of each of ART Corp. and the Company.(1)...........................
      10-21    Services Agreement dated May 8, 1995 with ART Corp.(1)...................................
      10-22    Option Agreement dated February 2, 1996 with ART Corp.(1)................................
      10-23    (a) Securities Purchase Agreement dated November 13, 1995 with ART Corp., Vernon
                   Fotheringham, W. Theodore Pierson, Jr., the stockholders of the Company named therein
                   and the Advent Partnerships.(1)......................................................
               (b) Exchange Agreement dated February 2, 1996 with ART Corp. and the Advent
                   Partnerships.(1).....................................................................
      10-24    (a) Securities Purchase Agreement dated February 2, 1996 with ART Corp. and Ameritech
                   Development Corporation ("Ameritech"), including letter of intent.(1)................
               (b) Warrant issued on February 2, 1996 to Ameritech.(1)..................................
               (c) Put/Call Agreement dated February 2, 1996 with Ameritech.(1).........................
      10-25    Strategic Distribution Agreement dated April 29, 1996 with Ameritech.(1).................
      10-26    Merger Agreement and Plan of Reorganization dated February 2, 1996 between the Company
                and ART Corp.(1)........................................................................
      10-27    (a) $2,445,000 Promissory Note in favor of CRA, Inc. ("CRA")(1)..........................
               (b) Security Agreement with CRA(1).......................................................
               (c) Indemnity Agreement(1)...............................................................
               (d) Form of Indemnity Warrant.(1)........................................................
      10-28    Memorandum of Terms of Development and Procurement Agreement with American Wireless with
                Extension Agreement dated April 25, 1996.(1)............................................
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
 EXHIBIT NO.                                          DESCRIPTION                                             PAGE
- -------------  -----------------------------------------------------------------------------------------  -------------
      10-29    (a) Purchase Agreement dated April 26, 1996 with Harris Corporation Farinon Division
                ("Harris") (confidential treatment requested for certain terms).........................
<C>            <S>                                                                                        <C>
               (b) PCS Marketing Agreement dated April 26, 1996 with Harris (confidential treatment
                requested for certain terms)............................................................
         11    Computation of Net Loss Per Share of Common Stock........................................
         12    Computation of Ratio of Earnings to Fixed Charges........................................
         21    Subsidiaries of the Registrant.(1).......................................................
       23(a)   Consent of the Registrant's Independent Accountant.......................................
       23(b)   Consent of the Registrant's Counsel will be contained in the Opinion of Counsel (to be
                filed by amendment).....................................................................
</TABLE>
 
- ------------------------
(1)  Filed with the Registration Statement on  Form S-1 of the Company dated May
2, 1996 (SEC Reg. No. 333-4388).

<PAGE>
                                                                      EXHIBIT 12
 
                          ADVANCED RADIO TELECOM CORP.
               COMPUTATION OF NET LOSS PER SHARE OF COMMON STOCK
  FOR THE PERIOD FROM MARCH 28, 1995 (DATE OF INCEPTION) TO DECEMBER 31, 1995
                                  (UNAUDITED)
 
<TABLE>
<S>                                                                           <C>
Net loss applicable to Common Stock.........................................  $  2,981,073
                                                                              --------------
                                                                              --------------
  Shares:
    Weighted average number of shares of Common Stock outstanding at
     December 31, 1995......................................................    15,919,596(1)
                                                                              --------------
                                                                              --------------
Net loss per share of Common Stock..........................................  $        .19
                                                                              --------------
                                                                              --------------
 
Pro Forma:
  Shares:
    Weighted average number of shares of Common Stock outstanding at
     December 31, 1995 for primary computation..............................
    Issuances of shares of Serial Preferred Stock, including anti-dilutive
     shares, subsequent to December 31, 1995 as converted into shares of
     Common Stock...........................................................
    Issuance of anti-dilutive shares of Common Stock subsequent to December
     31, 1995...............................................................
    Conversion of shares of Serial Preferred Stock outstanding at December
     31, 1995 into shares of Common Stock...................................
    Options and warrants issued and outstanding at December 31, 1995 and
     issued subsequent to December 31, 1995.................................
  Pro forma weighted average number of shares of Common Stock...............              (2)
                                                                              --------------
                                                                              --------------
Pro forma net loss per share of Common Stock................................  $
                                                                              --------------
                                                                              --------------
 
Pro Forma As Adjusted
  Shares:
    Pro forma weighted average number of shares of Common Stock.............
    Common Stock and warrants issued in connection with the Offerings.......
  Pro forma as adjusted weighted average number of shares of Common Stock...              (2)
                                                                              --------------
                                                                              --------------
Pro forma as adjusted net loss per share of Common Stock....................  $
                                                                              --------------
                                                                              --------------
</TABLE>
 
(1)  The weighted average  number of shares  of Common Stock  exclude all common
    stock equivalents which are anti-dilutive.
 
(2) 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
    must 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 $     per share.

<PAGE>
                                                                   EXHIBIT 23(A)
 
                       CONSENT OF INDEPENDENT ACCOUNTANTS
 
    We  consent to the inclusion  in this registration statement  on Form S-1 of
our reports dated April 26, 1996, on  our audits 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 and 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.  We also  consent  to the  reference to  our  firm under  the caption
"Experts."
 
                                          COOPERS & LYBRAND L.L.P.
 
New York, New York
May 13, 1996


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