ADVANCED RADIO TELECOM CORP
10-K, 1999-04-15
RADIOTELEPHONE COMMUNICATIONS
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<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549
                        ------------------------------

                                   FORM 10-K

|X|  Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange
     Act of 1934

|_|  Transition Report Pursuant to Section 13 or 15(d) of the Securities
     Exchange Act of 1934 for the transition period from ________ to _________

For the Year Ended December 31, 1998            Commission File Number 000-21091
                                     ----------

                         ADVANCED RADIO TELECOM CORP.
            (Exact name of registrant as specified in its charter)


                Delaware                                     52-1869023
      (State or other jurisdiction                        (I.R.S. Employer
   of incorporation or organization)                     Identification No.)

          500 108th Avenue, NE
               Suite 2600
          Bellevue, Washington                                  98004
(Address of principal executive offices)                     (Zip Code)

                                (425) 688-8700
             (Registrant's telephone number, including area code)
                                 -------------

          Securities registered pursuant to Section 12(b) of the Act:


                                                        Name of Each Exchange
  Title of Each Class                                     on Which Registered
  -------------------                                   ---------------------
          None                                                  None

          Securities registered pursuant to Section 12(g) of the Act:

  Title of Each Class:                           Common Stock ($.001 Par Value)
  --------------------                                                         
     Indicate by check mark whether the registrant: (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days: Yes [X] No [_].

     Indicate by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained, to the
best of the registrant's knowledge, in the definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K [_].

     The aggregate market value of the registrant's voting stock held by
non-affiliates was approximately $271 million on April 12, 1999, based on the
closing sales price of the registrant's common stock as reported on the Nasdaq
National Market as of such date.

     The number of shares outstanding of each of the registrant's classes of
common stock as of April 12, 1999 was as follows:

        Common Stock, $.001 par value:  27,142,409

                      DOCUMENTS INCORPORATED BY REFERENCE

     The following documents are incorporated herein by reference: PART III:
Portions of the Registrant's definitive Proxy Statement to be filed with the
Securities and Exchange Commission in connection with the Registrant's 1999
Annual Meeting of Stockholders.

                         Exhibit Index is on page 24.
<PAGE>
 
                                    PART I

ITEM 1.  BUSINESS

     Advanced Radio Telecom Corp. ("ART" or the "Company") intends to become the
leading provider of broadband Internet services to businesses not served by
fiber-optic networks. Utilizing its national footprint of 38 GHz spectrum
licenses, the Company currently serves Seattle, Washington, Portland, Oregon,
and Phoenix, Arizona and plans to serve up to 100 of the top metropolitan
markets over the next five years. With Lucent Technologies, Inc. ("Lucent") as
the Company's technology partner, the Company is building its own fixed
wireless, packet-based broadband data networks utilizing Internet Protocol
("IP") and Asynchronous Transfer Mode ("ATM") technology. As networks are
deployed and interconnected using a leased fiber-optic backbone, ART plans to
provide its customers with end-to-end connectivity on a metropolitan, regional
and national basis. ART offers an integrated package of data solutions including
Internet access, web hosting, web based content, virtual private networks, web
design and Internet portal service and intends to also offer electronic commerce
applications, multimedia services, voice and fax over IP and other value-added
data services.

     The data services market has been the fastest growing segment of the
communications industry over the last five years, expanding at a rate five times
faster than voice. Bandwidth-intensive data applications require high-speed
connectivity that today is generally only available on fiber-optic networks.
However, approximately 95% of U.S. commercial buildings are not currently served
by fiber and receive their data services through the copper telephone networks
provided by the incumbent local exchange carriers ("ILECs"). These copper
networks are limited in their ability to meet the demand for data services,
creating a "bottleneck" in the local connection to end-users. The Company
believes that a significant portion of these off-fiber buildings are not
currently economically attractive to fiber-based providers. For businesses
located in these buildings, access to the fiber backbone networks and as a
result, high-speed connectivity is generally unavailable, or is available only
at significant expense and with significant lead time.

     Recognizing this market opportunity, ART has refocused its business to
offer high-speed data connectivity and products directly to off-fiber
businesses. With its broadband data networks, the Company expects to deliver
services such as high-speed Internet access and private network services to the
customers' premises rapidly and economically.

     The Company is a Delaware corporation organized in 1993 under the name of
Advanced Radio Technologies Corporation. In October 1996, the Company through a
wholly owned subsidiary merged with Advanced Radio Telecom Corp., a corporation
organized by the Company and others in 1995 to acquire licenses and to operate
its business jointly with the Company. Upon the merger, Advanced Radio Telecom
Corp. became a wholly owned subsidiary of the Company and changed its name to
ART Licensing Corp., and the Company changed its name to Advanced Radio Telecom
Corp. In 1997 the Company acquired 129 38 GHz licenses in exchange for 6 million
shares of common stock and acquired the remaining 50% interest in a partnership
jointly owned by the Company for $6 million. The Company's original business
strategy was to sell connectivity to communications providers on a wholesale,
carriers' carrier basis.

ART's Competitive Advantages

     The Company believes that it is well-positioned to compete in offering
broadband Internet services to off-fiber commercial buildings. Advantages of
ART's wireless solution include:

     Focus on Data. ART believes it is currently the only wireless
telecommunications company focusing exclusively on data services rather than
primarily on voice telephony. Focusing on Internet applications allows ART's
networks to be completely packet-based, providing higher capacity, higher speed
data services than a circuit-switched network. ART has and intends to continue
hiring product development, technical, and sales personnel with expertise in
Internet applications and delivery, as opposed to telephony experience. ART is
directing its sales efforts toward information technology managers rather than
business managers in charge of telephony, which the Company believes will be a
sales advantage in selling Internet services.

                                      -2-
<PAGE>
 
     High-Speed, High-Capacity, High-Quality Connectivity. ART's broadband data
services are being engineered to provide high-speed, high-capacity connectivity
with quality superior to copper and comparable to fiber. Currently, ART's
wireless service provides two-way data transfer rates of up to 45 megabits per
second. Technology is available to expand the speed of two-way data transfer
rates to 155 megabits per second.

     Lower Cost Network. The Company expects its networks to cost less than its
competitors' fiber networks. The Company's fixed wireless networks do not
require the same magnitude of installation and maintenance costs as required by
fiber networks. The Company expects this cost differential to increase over time
because the cost of deploying fiber involves substantial labor and right-of-way
costs, which the Company does not expect to decrease, while the cost of ART's
networks involves substantial electronic equipment costs, which have and are
expected to continue to decline. The Company's network will be entirely
packet-based, and therefore the Company will not have to buy more expensive
circuit switches required by voice networks.

     Success-Based Capital Requirements. ART is designing its networks so that
the Company's capital will be spent incrementally as ART attracts customers,
minimizing the deployment of non-revenue generating equipment. ART's networks
are designed to reach customers within its initial clusters of buildings without
having to build out an entire market. ART's sales force initially targets
customers within hub site and other buildings ready to be connected to the ART
network, then customers in new buildings within the range of established radio
hub sites, and then customers in buildings to be connected in new clusters. As
needs change, ART's equipment can be economically and rapidly deployed or
relocated.

     Rapid Market Coverage. Leveraging its 38 GHz licenses which cover 90 of the
top 100 U.S. markets, ART intends to rapidly deploy a nationwide broadband
network dedicated to delivering data services to businesses off the fiber
network. ART believes that this rapid deployment will enable ART to establish
its position as a leading provider of broadband data services by penetrating the
market in advance of many wireline competitors who cannot or will not construct
their networks as quickly.

     Experienced Management. ART has assembled a management team with
substantial telecommunications experience. Henry C. Hirsch, ART's Chairman and
Chief Executive Officer, was formerly Vice Chairman and CEO of Williams
Communications Group and President and Chief Operating Officer of Williams
Telecommunications Systems ("WilTel"). William J. Maxwell, President and Chief
Operating Officer, previously served as Executive Vice President of Strategic
Planning, Sales and Marketing and prior to that as Executive Vice President of
ICG Communications and President of ICG Telecom Group. Robert S. McCambridge,
Executive Vice President and Chief Financial Officer, was formerly Executive
Vice President of OneComm, formerly Cable Plus Holding Company. Thomas P.
Boyhan, Executive Vice President, Sales and Marketing, previously was Senior
Vice President, National Account Sales for William's Communications Solutions, a
national systems integration company, and served as Vice President, Global
Accounts for WilTel. George R. Olexa, Executive Vice President and Chief
Technology Officer, was formerly Executive Vice President of Engineering of Dial
Call Communications Inc. and as Executive Director of Network Engineering and
Technology Applications for PacTel Cellular, was the architect of their cellular
networks in major cities in the U.S. and Europe.

Business Strategy

     ART's goal is to become a leading end-to-end solutions provider for
businesses needing a wide range of Internet based services. The Company is
implementing the following initiatives to achieve this objective:

     Target Off-Fiber Businesses. ART is focusing its primary marketing efforts
on businesses located off the fiber network. The Company identifies building
clusters in high-density off-fiber areas containing customers with high
potential for significant Internet services requirements, such as
high-technology companies that are typically located outside cities' main
business districts. Once ART deploys its network to service these initial
customers, it is able to reach new customers in the surrounding area rapidly
without having to replicate hub site infrastructure.

                                      -3-
<PAGE>
 
     Offer End-Users an Array of Broadband Internet Services. ART offers
business customers an integrated package of high-speed, Internet based services,
including Internet access, web hosting and virtual private networks and intends
to also offer electronic commerce applications, multimedia services, voice and
fax over IP and other enhanced data services. By targeting end-user customers,
ART believes it will maximize revenues and profitability.

     Develop Strategic Business Relationships. ART plans to enter into business
relationships to help the Company penetrate its markets, develop its service
offerings and provide additional distribution channels. ART intends to continue
to forge alliances with property management companies to gain access to
buildings and tenants. ART also intends to develop partnerships with
data-oriented sales agents, including local data network integrators and telecom
resellers that focus primarily on data products. ART also plans to continue to
expand its product offerings by developing relationships with web hosting
providers, electronic commerce software providers, system integrators, streaming
media providers, and other web content providers. ART will continue to seek to
develop relationships with inter-exchange carriers ("IXCs"), Internet service
providers ("ISPs"), utilities, ILECs and competitive local exchange carriers
("CLECs") to connect disparate parts of the Company's network, thereby offering
end-to-end connectivity to its customers.

     Provide Superior Customer Service. ART plans to provides superior customer
service, with service features such as a 24-hour-a-day, seven-day-a-week call
center, a network quality control system and comprehensive customer support
services. The Company plans to continue to differentiate itself from its
competitors and establish brand identity based on high quality service that is
responsive to the customer.

Network Deployment

     ART believes it is the first company to deploy state-of-the-art,
packet-based broadband metropolitan area networks ("BMANs") using IP routing and
ATM switching infrastructure. ART's BMANs are expected to provide broadband
connectivity to buildings and office campuses with significant aggregation
opportunities for a variety of Internet services. The Company will connect
buildings and campuses to the public Internet, IXCs and CLECs in a metropolitan
area.

     Over the next five years, ART intends to build BMANs in up to 100 of the
top U.S. markets. ART has initially built its networks in Seattle, Washington,
Portland, Oregon and Phoenix, Arizona. After deploying the initial hub sites,
the networks will be expanded incrementally in response to demand. Using leased
capacity on long haul fiber networks, ART plans to connect BMANs first in
neighboring markets with communities of interest, such as San Jose, Los Angeles
and San Diego, California, Las Vegas, Nevada, Tucson, Arizona, Salt Lake City,
Utah, Boise, Idaho and Spokane, Washington. Eventually, ART plans to
interconnect its BMANs into a national and global network using long haul fiber
connections. As BMANs are connected, ART will be able to offer customers
end-to-end connectivity, carrying data between two end-users through its local
wireless network in one metropolitan area, over the long haul fiber backbone,
and back through another wireless network in a different metropolitan area. As
ART interconnects its BMANs, ART will create a private inter-city IP and ATM
backbone that will allow ART to sell national intranets to its end users.

Sales & Marketing

     ART is marketing its services primarily through a direct sales force, which
is responsible for initial sales efforts in each new market. ART supports its
direct sales efforts in each market with telemarketing, direct mail and
advertising as well as with research about target markets, buildings and
customers. Lucent has agreed to provide technical support to assist ART's
salespersons with selling the Company's services to prospective customers by
assigning Lucent teams to work with ART personnel during the selling process.
ART also will employ various indirect sales channels.

                                      -4-
<PAGE>
 
     In each new market, ART uses demographic and geographic information systems
to identify those clusters of commercial buildings without access to high-speed
data services that contain tenants with significant demand for data services or
that contain large buildings with attractive opportunities for aggregating data
traffic. ART expects that its best sales opportunities will be in clusters
including office buildings, warehouses, retail buildings, office parks,
hospitals and universities. ART expects to rapidly deploy its network by
initially locating sites in each market to serve those clusters that the Company
believes present the most promising opportunities and then expanding in
secondary clusters in a market.

     In general, before any customer premise equipment is deployed in a cluster,
ART's sales personnel pre-sell its services by focusing on buildings with the
highest concentrations of significant data users. The Company simultaneously
seeks to obtain building access rights necessary to extend its network to these
new customers. Once ART begins services to a cluster, ART continues to sell
services in buildings where equipment has been deployed and will target
additional buildings within the cluster. ART will then expand its network within
the market by deploying additional clusters using the same process.

     ART believes that its data focus provides it with a significant advantage
in selling its services. Sales of data services are technical in nature, and
therefore, the Company has hired and continues to hire sales personnel in each
market who are experienced in selling and implementing data services, rather
than a sales force experienced in voice telephony. ART's data focus enables its
direct sales personnel to tailor their selling efforts to a potential customer's
information technology decision-marker, rather than the voice telephony
decision-maker. ART expects that these information technology decision-makers
will directly drive the demand for high-bandwidth broadband data services by its
target customers.

     In order to increase the scope and speed of its market penetration, ART
intends to supplement its direct sales efforts by utilizing various indirect
sales channels. ART will seek to develop relationships with data-oriented sales
agents, including local data network integrators and telecom resellers focusing
on data. These sales agents could provide ART with access to a greater number of
data-oriented business customers in each market. In addition to these
traditional indirect sales channels. ART plans to continue marketing to
nationally positioned property management companies to gain access to their
tenants and to secure roof rights necessary to deploy ART's networks.

     ART also plans to seek relationships with a variety of telecommunications
carriers to assist the Company in developing its networks, more rapidly
penetrating its markets, reducing its operating costs, and creating additional
revenue opportunities. The Company believes it would be an attractive partner
for a variety of telecommunications carriers which may be willing to jointly
deploy data networks and share capacity and revenue opportunities. For example,
capacity-swaps between ART and domestic and international high-speed data
carriers could be mutually advantageous, helping those carriers build
high-speed, packet data networks using IP technology. Capacity-swaps with
smaller fiber carriers and IXCs could provide the fiber carriers and IXCs with
broadband local access. ART believes its high-speed, high-capacity connectivity
also may be attractive to ISPs, helping them develop markets quickly,
differentiate their service from other ISPs, increase their margins and serve
higher volumes of customers.

Products and Services

     ART provides broadband Internet solutions. The Company is deploying its
networks on an initial basis to support a comprehensive and fully-integrated
product line that is designed to meet the broadband Internet telecommunications
needs of business customers located off the fiber network.

     Internet Access. ART offers business customers an end-to-end Internet
access solution by providing high-speed Internet access over ART's wireless data
networks. ART's Internet Access offering ranges in speed from 64 kilobits per
second to 10 megabits per second. ART is providing Internet service in
conjunction with one or more Internet transit partners. ART intends to partner
with additional Internet transit providers that are utilizing a private network
access point ("PNAP") strategy. It is ART's belief that a PNAP configuration
provides a higher speed Internet experience.

                                      -5-
<PAGE>
 
     Hosting Services. ART currently offers a shared web hosting service. The
service is based on state-of-the-art servers and is located in an
environmentally-controlled equipment room that is staffed 24 hours a day. The
server farm is connected to the network via a redundant DS-3 backbone
connection. ART is planning to offer dedicated web hosting service as well as
collocation service for web hosting customers that require support for a
stand-alone server or need support for a customer-owned server.

     Web Design Services. ART offers web design services for those customers
that require assistance in creating and maintaining a web site.

     Remote Access Service. ART provides remote access services to customers who
wish to access their local area network through the Internet or wish to remotely
access the Internet.

     Internet Portal. ART offers a portal that is used by customers to access
the Internet. The portal can be customized by geographic region and by the
end-user's interests.

     Internet Value-Added Services. ART offers an array of value-added Internet
services, including domain name service, IP Fax, local caching, e-mail service,
web hosting, security services and news services.

     Gateway Services. ART's Gateway Services provide broadband connectivity
between end-users or between a wholesale customer's networks. Gateway Services
connect end-users' private networks, including remote office LAN and client
server interconnectivity, integrated voice, multimedia and data offerings.
Gateway services also enable ART to create virtual private networks ("VPNs") or
intranets, facilitating enterprise-wide communications with local and national
private networking capabilities. Gateway Services also offer end-users extranet
services giving outside customers and clients access to specific elements within
an end user's VPN or intranet. Gateway Services will support ATM, IP, Ethernet
and Frame Relay technologies.

     Future Products and Services. ART plans to offer an array of other services
which are currently under development. ART expects future Internet services will
include security service and security consulting services, distributed network
caching and electronic commerce services, IP voice and IP video conferencing
service, multimedia streaming applications, network consulting and other
value-added services as they are developed.

ART's Network

     ART is deploying a state-of-the-art packet-based broadband network using
wireless facilities interfaced with the fiber backbone in metropolitan areas and
nationally to provide end-to-end, high-bandwidth data services. ART has been
building packet-switched, point-to-point fixed wireless BMANs using ATM,
Ethernet, Frame Relay and IP technologies. ART intends to incorporate
point-to-multipoint equipment as soon as it becomes commercially available.

     The network equipment uses digital wireless technology designed to deliver
high-quality data services that ART believes is comparable in quality to
fiber-based systems. The Company will use radio hubs to transmit to and receive
signals from wireless equipment on customers' premises. The customers' premises
equipment includes two components: (1) an integrated antenna/radio unit
installed on the roof or an exterior wall and (2) the indoor customer interface
equipment installed within the building. The radio/antenna unit will communicate
with the hub via radio signal. The base stations hubs will have an average
line-of-sight service radius of approximately one mile, depending on a number of
factors such as power levels used and local weather environment. A
point-to-multipoint hub will have the capability to support customers within
line-of-sight in every direction within a 360 degree coverage area.

     The Company's point-to-multipoint hardware and network capacity will be
shared among all the customers within the coverage area of a hub sector. A key
feature of the Company's network architecture will be its ability to provide
bandwidth-on-demand, giving customers as much or as little bandwidth as they
need.

                                      -6-
<PAGE>
 
     Traffic between hub sites and the Company's ATM switching centers will be
carried over a backhaul network that will be a combination of wireless links and
fiber-optic transmission facilities, as appropriate. The Company expects to work
with fiber network providers, through leasing arrangements or partnerships.

38 GHz Wireless Broadband Licenses

     The FCC has allocated the 38.6-40.0 GHz (the "38 GHz") band for wireless
broadband transmissions consisting of fourteen 100 MHz channels for the
provision of wireless telecommunications services within a specified geographic
footprint.

     The Company owns 363 38 GHz licenses (excluding certain licenses being
transferred pursuant to the option described below). Taken together, these
licenses allow the Company to provide 38 GHz wireless broadband services in 210
U.S. markets, allowing it to provide between 100 and 500 MHz of transmission
capacity in 90 of the top 100 U.S. markets. An option to acquire from the
Company 12 38 GHz licenses in specified markets in which the Company has more
than one license was exercised in June 1997, with closing subject to FCC
approval. The Company has the right to be a reseller with respect to these
licenses for a term of five years at market rates.

     The Company may selectively utilize other radio frequencies to provide its
services under certain circumstances. The Company may seek to acquire additional
licenses or businesses which hold licenses to expand its geographic footprint or
to enhance its ability to provide service within its current markets.

Foreign Licenses

     Foreign subsidiaries of the Company have been granted broadband wireless
authorizations covering Norway, Denmark and the United Kingdom which allow the
provision of broadband wireless connectivity for communications services with
certain limitations. Other foreign subsidiaries have applied for licenses in
other countries. There can be no assurance that any of these entities will be
able to acquire, retain or exploit licenses, comply with applicable license
restrictions, obtain any other necessary governmental approvals, obtain
financing, implement business plans or operate in any country on a profitable
basis or at all.

Competition

     ART does not believe any other company is currently offering broadband
Internet services to off-fiber businesses. However, ART faces significant
competition from other entities that currently or could in the future deliver
data services over copper wire, fiber and wireless networks, including ISPs, web
hosting and web application providers, ILECs, CLECs, fiber service providers,
cable television operators, wireless service providers and satellite
communications companies. In addition, the consolidation of telecommunications
companies and the formation of strategic alliances and cooperative relationships
in the telecommunications and related industries, as well as the development of
new technologies, could give rise to significant new competitors to the Company.
The Company expects to compete primarily on the basis of responsiveness to
customer needs, features, service, quality, price, high-speed services and
reliability. There can be no assurance that the Company will be able to compete
effectively in any of its market areas with any of its existing and potential
competitors. Many of the Company's competitors have long-standing relationships
with customers and suppliers, greater name recognition and greater financial,
technical and marketing resources than the Company. As a result, these
competitors, among other things, may be able to develop and exploit new or
emerging technologies or adapt to changes in customer requirements more quickly
than the Company or devote greater resources to the marketing and sale of their
services than the Company.

     ISPs. The Company faces significant competition from ISPs which deliver
Internet access services as well as valued-added, web-based services. ART
competes against Tier 1, Tier 2, and Tier 3 ISPs. Tier 1 ISPs generally have
substantial brand recognition and a robust suite of value-added, web-based
services. Tier 2 and Tier 3 ISPs have regional brand recognition and are
expanding rapidly with low-cost services like digital subscriber line ("DSL")
services.

                                      -7-
<PAGE>
 
     Web Hosting and Application Providers. The Company faces significant
competition from web hosting and web application providers. These companies
specialize in niche markets and offer value-added, web-based services that
compete directly with ART's value-added services.

     ILECs' Copper Networks. The Company faces significant competition from
incumbent LECs, which typically deliver data services over copper networks.
Incumbent LECs have long-standing relationships with their customers and
substantial name recognition. In addition, the incumbent LECs have employed or
will likely employ digital subscriber line products such as ADSL (asymmetrical
digital subscriber line), which is currently available. Commercial DSL services
currently are limited to 7 megabits of throughput downstream and 1 megabit of
throughput upstream. ART currently has the capability to provide much higher
bandwidth.

     Fiber Networks. The Company also faces competition from expanding
fiber-optic networks owned by incumbent and competitive LECs, IXCs, electric
utilities and other companies. Many of these companies have greater name
recognition and greater financial, technical and marketing resources than the
Company. Fiber-optic service generally offers broadband connectivity that is
comparable, if not superior to, the company's wireless broadband connections. In
addition, fiber technology may enjoy a greater degree of market acceptance than
wireless broadband technology.

     Coaxial Cable Networks. The Company is likely to face competition from
cable television operators deploying cable modems, which provide high-speed data
capability over installed coaxial cable television networks, and there can be no
assurance that such competition will not be significant. 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
businesses and government users, cable operators will be required to spend
significant time and capital in order to upgrade their existing networks to a
more advanced hybrid fiber coaxial network architecture and to extend these
networks to reach businesses. However, there can be no assurance that cable
modems will not emerge as a significant source of competition.

     Other Fixed Wireless Networks. The Company also faces competition from
other fixed wireless service providers within its market areas including WinStar
Communications, Inc., Teleport Communications Group, Inc. ("TCG") and Teligent,
Inc. ("Teligent"). In many cases, one or all of these service providers hold
licenses to operate in the Company's market areas. WinStar and Teligent have
positioned themselves as wireless CLECs, and therefore will compete with the
Company in offering off-fiber connectivity to businesses and buildings, with the
potential to offer broadband data services. TCG, which AT&T has acquired, also
has the ability to provide wireless broadband services. All three companies have
substantially greater financial resources than the Company.

     Various other entities also have 38 GHz and other wireless broadband
licenses. Due to the relative ease and speed of deployment of fixed wireless
technology, the Company could face intense price competition and competition for
customers from other service providers.

     The Company also faces potential competition from new entrants acquiring
licenses from FCC auctions. The FCC has recently auctioned 28 GHZ LMDS licenses
in all markets for the provision of high-capacity, wide-area fixed wireless
point-to-multipoint systems. LMDS licensees may use the spectrum to offer a
variety of services such as multichannel video programming, telephony, video
communications and data services in competition with the Company. The FCC has
announced an auction of geographical wide area licenses for the operation of
fixed wireless point-to-point and point-to-multipoint communications services in
the 38 GHz band.

     MMDS service, provided at the 2 GHz spectrum band, also known as "wireless
cable," and ISM service also compete for metropolitan wireless broadband
services. At present, wireless cable licenses are used primarily for the
distribution of video programming and have only a limited capability to provide
two-way communications needed for wireless broadband telecommunications
services, but there can be no assurance that this will continue to be the case.

                                      -8-
<PAGE>
 
     In January 1997, the FCC allocated 300 MHz of spectrum in the 5 GHz band
for unlicensed devices to provide short-range, high-speed wireless digital
communications. These frequencies must be shared with incumbent users without
causing interference. The allocation was designed to facilitate the creation of
new wireless local area networks, and thus may compete with the Company's
strategy of providing wireless connections between LANs. It is too early to
predict, however, how and to what extent this particular frequency may be used
in competition with the Company.

     Mobile Wireless Networks. Cellular, personal communications services and
other mobile service providers may also offer data services over their licensed
frequencies. The FCC has also allocated a number of spectrum blocks for use by
wireless devices that do not require site or network licensing. A number of
vendors have developed such devices, which may provide competition to the
Company particularly for certain low-speed data transmission services. However,
ART has positioned itself to provide high-speed Internet services, and mobile
wireless networks generally offer lower transmission speeds.

     Satellite Networks. Many other companies have filed applications with the
FCC to develop global broadband satellite systems which may be used to provide
broadband voice and date services. Satellite is currently a broadcast medium in
which two-way communications are not readily available. However, if the
satellite providers can develop two-way communications, this could represent a
significant competitive threat.

Government Regulation

     The Company's wireless broadband services are subject to regulation by
federal, state and local governmental agencies. At the federal level, the FCC
has jurisdiction over the use of the electromagnetic spectrum (i.e., wireless
services) and has exclusive jurisdiction over all interstate telecommunications
services, that is, those that originate in one state and terminate in another
state. State regulatory commissions have jurisdiction over intrastate
communications, that is, those that originate and terminate in the same state.
Municipalities may regulate limited aspects of the Company's business by, for
example, imposing zoning requirements and requiring installation permits.

Federal Regulation

     FCC Licensing. The Communications Act of 1934, as amended, and the FCC
Rules and Regulations ("Communications Laws") impose requirements on radio
licensees and carriers, including, among other things, regulations on the
ownership, operation, acquisition and sale of the broadband operating radio
systems that are needed to provide the services offered by the Company. On
October 24, 1997, the FCC issued a Report and Order and Second Notice of
Proposed Rulemaking ("Order") that substantially modified the regulations
applied to 38 GHz licensees, such as the Company. The Order allocated new
spectrum at 37.0-38.6 GHz; conformed the rules for operation in the 37.0-38.6
GHz band with the rules for operation in the 38.6-40.0 GHz band; modified
certain operational rules for both bands; adopted a competitive bidding
licensing scheme for authorizing new spectrum in these bands over geographic
areas defined by the Rand-McNally Basic Trading Areas ("BTAs") and, adopted
rules for the protection of incumbent licensees, such as the Company.

     The new operational rules generally expand the flexibility of licensees
operating in the 37.0-40.0 GHz band. For example, licensees are now permitted to
offer point-to-multipoint and point to point services, and will be permitted to
provide mobile services upon adoption of inter-licensee coordination policies.

     All of the 38 GHz licenses owned or to be acquired by the Company are due
to expire in February of 2001. Under the new operational rules, the Company will
be entitled to a "renewal expectancy," a dispositive preference in renewal
proceedings, for a license if the Company can demonstrate that it is providing
"substantial service" within the licensed area when it files its renewal
application. The FCC has not provided definitive guidance on what level of
service is considered "substantial." If the Company were not to receive a
renewal expectancy, the Company's operations could be adversely affected.

                                      -9-
<PAGE>
 
     Under the FCC's rules, the Company is also subject to certain build-out
requirements. The Company must construct facilities to place each licensed
station in operation within 18 months of the date of grant of the license.
Although, under current FCC regulations, the term "in operation" is not defined
beyond the requirement that the station be capable of providing service, the
industry custom is to establish at least one link between two transceivers in
each licensed market area. Failure to meet the construction deadline results in
the automatic cancellation of the license. In addition, if a station does not
transmit operational traffic (not test or maintenance signals) for a consecutive
period of twelve months at any time after construction is complete, or if
removal of equipment or facilities renders the station incapable of providing
service, the license is subject to cancellation or forfeiture, absent a waiver
of the FCC's rules.

     Petitions for reconsideration of various aspects of the Order, including
but not limited to the treatment of pending applications and amendments, have
been filed by a number of parties, including the Company. It is not possible to
determine when the FCC will act on these petitions or what changes, if any, will
be made to the final rules. Thus, there can be no assurance that the final rules
will not have a material adverse effect on the Company's operations.

     The FCC has not yet scheduled an auction for licenses in the 37.0-40.0 GHz
band. The Company has not made a determination as to whether it would seek
additional licenses in the event of an auction.

     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. The Telecommunications Act of 1996 substantially
departs from prior legislation in the telecommunications industry by
establishing local exchange competition as a national policy through the removal
of state regulatory barriers to competition and the preemption of laws
restricting competition in the local exchange market. The provisions of the
Telecommunications Act are designed to ensure that regional Bell operating
companies ("RBOCs") take affirmative steps to level the playing field for their
competitors so that Competitive Access Providers, CLECs and others can compete
effectively. The FCC, with advice from the United States Department of Justice,
and the states are given jurisdiction to enforce these requirements. There can
be no assurance, however, that the states and the FCC will implement the
Telecommunications Act in a manner favorable to the Company.

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. Under
current state regulatory schemes, entities can compete with ILECs 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.

Research and Development

     During 1998, 1997 and 1996, the Company spent $593,595, $421,236 and
$1,269,579, respectively, with respect to research and development.

Employees

     As of March 1, 1999 the Company had a total of 133 employees. None of the
Company's employees is represented by a collective bargaining agreement.


ITEM 2.  PROPERTIES

     The Company leases approximately 57,443 square feet of office, technical
operations and engineering field services depot space in Bellevue, Washington,
under leases expiring in April and May 2002 of which 5,227 square feet has been
subleased. In addition, the Company also leases approximately 31,000 square feet
of office space in 8 cities nationwide of which 12,822 square feet has been
subleased.

                                      -10-
<PAGE>
 
ITEM 3.  LEGAL PROCEEDINGS

     The Company is not a party to any material litigation.

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

     The Company did not submit any matter to a vote of the security holders
during the fourth quarter of the 1998 fiscal year.

ITEM 4A. EXECUTIVE OFFICERS OF THE REGISTRANT

     The executive officers of the Company are as follows:
<TABLE>
<CAPTION>
Name                        Age     Position
- ----                        ---     --------
<S>                         <C>     <C>  
Henry C. Hirsch..............57     Chairman of the Board of Directors and Chief Executive Officer
William J. Maxwell...........56     President and Chief Operating Officer
Thomas P. Boyhan.............54     Executive Vice President, Sales and Marketing
Robert S. McCambridge........40     Executive Vice President, Chief Financial Officer
George R. Olexa..............43     Executive Vice President, Chief Technology Officer
</TABLE>
     Henry C. Hirsch has served as Chairman of the Board of Directors and Chief
Executive Officer of the Company since November 1997. From 1996 to 1997, Mr.
Hirsch was the Vice Chairman and Chief Executive Officer of Williams
Communications Group, a wholly-owned subsidiary of The Williams Companies that
provides businesses with enterprise network solutions, services and advanced
multimedia applications. From 1992 to 1996, Mr. Hirsch served as President and
Chief Operating Officer of WilTel, a nationwide systems integration company.
From 1989 to 1992, he was Executive Vice President of Sales and Marketing as
well as Chief Financial Officer of WilTel.

     William J. Maxwell has served as President and Chief Operating Officer
since October 1998 and previously as Executive Vice President of Strategic
Planning, Sales and Marketing of the Company since December 1997. From 1992 to
1997, Mr. Maxwell was Executive Vice President of ICG Communications Inc. and
the President and Chief Executive Officer of ICG Telecom Group. From 1991 to
1992, Mr. Maxwell was the senior marketing executive with WilTel. From 1989 to
1991, Mr. Maxwell was the President and Chief Executive Officer of MidAmerican
Communications Corporation, a regional long distance company.

     Thomas P. Boyhan has served as Executive Vice President, Sales and
Marketing of the Company since September, 1998. From January 1997 to August
1998, Mr. Boyhan was Senior Vice President, National Account Sales of William's
Communications Solutions, a national $1.3 billion systems integration company,
70 percent owned by William's Communications Group, Inc. From July 1994 to
December 1997, Mr. Boyhan was Vice President, Global Accounts of WilTel. From
February 1991 to June 1994, Mr. Boyhan was Director of Sales, Eastern U.S.
Region of Bell South Communications.

     Robert S. McCambridge has served as Executive Vice President and Chief
Financial Officer of the Company since October 1998. From September 1996 to
October 1998, Mr. McCambridge was Executive Vice President and earlier Vice
President and Chief Financial Officer of One Comm, formerly Cable Plus Holding
Company. From May 1995 to September 1996, Mr. McCambridge was President of the
Robert S. McCambridge Company. From March 1994 to May 1995 Mr. McCambridge was
Senior Vice President and Director of Pacific Northwest Corporate Finance of
Dain Bosworth Inc. From December 1991 to January 1994 Mr. McCambridge was
Treasurer and Vice President of Corporate Development of Cerdian Corporation,
formerly Control Data Corporation.

     George R. Olexa has served as Executive Vice President and Chief Technology
Officer since February 1998. From 1996 to 1997, Mr. Olexa was Chief Operating
Officer at Superconducting Core Technologies, a high-technology 

                                      -11-
<PAGE>
 
equipment manufacturer for the telecommunications industry, supplying
high-performance, superconducting filters and cryoelectronics for wireless
infrastructures. From 1993 to 1996, Mr Olexa served as Executive Vice President
of Engineering of Dial Call. From 1988 to 1993, he was Executive Director of
Network Engineering and Technology Applications for PacTel Cellular.

ITEM 5.  MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS

     ART's common stock is traded in the over-the-counter market and is reported
on the Nasdaq National Market under the symbol "ARTT." The following table sets
forth for the periods indicated the high and low bid information of the common
stock as reported on the Nasdaq National Market. Such transactions reflect
inter-dealer prices, without retail markup, markdown or commission and may not
necessarily represent actual transactions.

                                                            PRICE RANGE     
                                                            -----------     
                                                       High             Low   
                                                       ----             ---   

     1997 First Quarter........................      $14.625           $10.375
          Second Quarter.......................      $11.250            $6.625
          Third Quarter........................      $ 9.500            $6.313
          Fourth Quarter.......................      $10.625            $7.500

     1998 First Quarter........................      $17.000            $7.500
          Second Quarter.......................      $16.375            $9.688
          Third Quarter........................      $10.000            $2.938
          Fourth Quarter.......................       $7.500            $2.125

     On April 12, 1999, the last sale price of common stock as reported on the
Nasdaq National Market was $12.9375 per share. As of April 12, 1999 there were
136 record holders of ART's common stock.

     ART has not paid any cash dividends on its common stock in the past and
does not anticipate paying any cash dividends on its common stock in the
foreseeable future. ART's Board of Directors intends to retain earnings to
finance the expansion of ART's business and fund ongoing operations for the
foreseeable future. In addition, the terms of the indenture relating to the
Company's 14% Senior Notes due 2007 restrict the ability of the Company to pay
dividends on common stock.

                                      -12-
<PAGE>
 
ITEM 6.  SELECTED FINANCIAL DATA

     The selected financial data presented below as of December 31, 1994, 1995,
1996, 1997 and 1998 and for the years ended December 31, 1994, 1995, 1996, 1997
and 1998 were derived from and should be read in conjunction with the audited
financial statements of the Company.
<TABLE>
<CAPTION>
                                                                              Year ended December 31
                                              ---------------------------------------------------------------------------------
                                                   1994             1995             1996             1997             1998 
                                              -------------    -------------    -------------    -------------    -------------
<S>                                           <C>              <C>              <C>              <C>              <C>           
Statement of Operations Data:
Service revenue ............................  $          --    $       5,793    $     247,116    $     708,883    $     840,822
Equipment sales and construction revenue ...             --               --        2,660,811          396,970               --
Consulting revenue .........................        137,489               --               --               --               --
Technical and network operations expenses ..             --               --        3,402,948        7,252,512        8,603,576
Cost of equipment sales and construction ...             --               --        1,590,779          254,444
Sales and marketing expenses ...............             --          191,693        5,548,584       13,469,898        5,679,222
General and administrative expenses ........        253,453        2,911,273       12,896,134       12,789,866       11,992,874
Research and development expenses ..........             --               --        1,269,579          421,236          593,595
Equipment impairment .......................             --               --               --        7,166,920        2,753,105
Depreciation and amortization ..............          8,281           15,684        1,017,959        6,018,172        7,354,378
Loss from operations .......................       (124,245)      (3,112,857)     (22,818,056)     (46,266,995)     (36,135,928)
Interest and other expenses, net ...........          4,375          121,986        6,512,251       16,817,180       19,978,994
Income tax benefit .........................             --               --               --        1,355,249        9,132,237
Extraordinary loss .........................             --               --        1,339,996               --               --
Net loss ...................................       (128,620)      (3,234,843)     (30,670,303)     (61,728,926)     (46,982,685)
Basic and diluted net loss per share .......          (0.04)           (0.54)           (3.97)           (3.23)           (1.89)
Weighted average number of shares of
     common stock outstanding ..............      3,337,685        5,946,338        7,717,755       19,083,304       24,890,177

Other Financial Data:
EBITDA (1) .................................  $    (115,964)   $  (2,007,568)   $ (14,348,920)   $ (30,811,151)     (25,186,686)
Capital expenditures .......................          5,175        3,585,144       16,631,451       16,685,436       11,049,743
<CAPTION>

                                                                                As of December 31
                                              ---------------------------------------------------------------------------------
                                                    1994            1995             1996             1997             1998 
                                              -------------    -------------    -------------    -------------    -------------
<S>                                           <C>              <C>              <C>              <C>              <C>           
Balance Sheet Data:
Working capital surplus (deficit) ..........  $     (76,556)   $  (3,008,510)   $  (9,623,905)   $  25,608,821    $  (2,930,428)
Property and equipment, net ................          3,448        3,581,561       19,303,849       25,294,946       33,202,310
FCC licenses, net ..........................             --        4,235,734        4,330,906      131,210,102      186,513,591
Total assets ...............................         42,611        9,876,559       36,648,701      232,559,749      265,721,291
Long-term debt .............................             --        6,450,000        4,977,246      108,299,359      118,371,245
Accumulated deficit ........................       (135,214)      (3,370,057)     (34,040,360)     (95,769,286)    (142,751,971)
Total stockholders' equity (deficit) .......        (39,078)        (312,860)      19,949,920       76,257,063       82,354,920
</TABLE>

- ------------
(1)  EBITDA consists of loss before interest and financing expense (net of
     interest income), income tax expense, depreciation and amortization
     expense, non-cash compensation expense, non-cash equipment charges and
     non-cash market development expense. EBITDA is not intended to represent
     cash flows from operating activities, as determined in accordance with
     generally accepted accounting principles. EBITDA should not be considered
     as an alternative to, or more meaningful than, operating income or loss,
     net income or loss or cash flow as an indicator of the Company's
     performance. Not all companies calculate EBITDA in the same fashion and
     therefore EBITDA as presented may not be comparable to other similarly
     titled measures of other companies.

                                      -13-
<PAGE>
 
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS

Restatement of Quarters and Significant Provisions

The Company has restated its interim financial results for the first, second and
third quarters of fiscal 1998 as a result of a change in tax law that was not
previously considered, which increased the net operating loss carryforward
period from 15 to 20 years. As a result of this and an increase in the Company's
tax liability accrual, the 1998 year end results reflected in this report differ
from the unaudited results previously reported by the Company.

The following table presents a summary of unaudited quarterly financial
information for the three quarters of fiscal 1998, as reported and as restated.
<TABLE>
<CAPTION>
                                       Three Months Ended             Three Months Ended             Three Months Ended
                                         March 31, 1998                  June 30, 1998               September 30, 1998  
                                 ----------------------------    ----------------------------    ----------------------------
                                  Previously          As          Previously          As          Previously          As
                                   Reported        Restated        Reported        Restated        Reported        Restated
                                 ------------    ------------    ------------    ------------    ------------    ------------ 
<S>                              <C>             <C>             <C>             <C>             <C>             <C>         
Total revenue ................   $    236,557    $    236,557    $    205,770    $    205,770    $    186,756    $    186,756
Total operating
  costs and expenses .........      7,089,860       7,089,860       7,370,331       7,370,331      10,660,279      10,660,279
                                 ------------    ------------    ------------    ------------    ------------    ------------ 
Operating loss ...............     (6,853,303)     (6,853,303)     (7,164,561)     (7,164,561)    (10,473,523)    (10,473,523)
Total interest and other .....      4,299,281       4,299,281       4,614,100       4,614,100       5,170,632       5,170,632
                                 ------------    ------------    ------------    ------------    ------------    ------------ 
Loss before income taxes .....    (11,152,584)    (11,152,584)    (11,778,661)    (11,778,661)    (15,644,155)    (15,644,155)
Deferred income tax benefit ..        329,170       2,051,789       1,464,053       2,207,090         808,974       1,936,645
                                 ------------    ------------    ------------    ------------    ------------    ------------ 
Net loss .....................   $(10,823,414)   $ (9,100,795)   $(10,314,608)   $ (9,571,571)   $(14,835,181)   $(13,707,510)
                                 ============    ============    ============    ============    ============    ============ 

Basic and diluted net loss
  per common share ...........   $      (0.50)   $      (0.42)   $      (0.42)   $      (0.39)   $      (0.56)   $      (0.51)
                                 ============    ============    ============    ============    ============    ============ 
Weighted average common
  shares .....................     21,736,800      21,736,800      24,332,349      24,332,349      26,701,030      26,701,030
                                 ============    ============    ============    ============    ============    ============ 
</TABLE>

Overview

     From its inception in 1993 to the fourth quarter of 1996, the Company
primarily focused on acquiring licenses, hiring management and other key
personnel, raising capital, acquiring equipment and roof rights and developing
operating and support systems to support its initial business of selling
connectivity to various telecommunications companies as a wholesale carriers'
carrier, which the Company commenced in the fourth quarter of 1996. Following
the establishment of a new core management team, the Company altered its
strategy in the first quarter of 1998 to sell a variety of broadband Internet
services to end-user customers and to deploy a broadband data network. The
results from operations in 1997 reflect a business no longer being pursued by
the Company. During the year ended December 31, 1998, ART began offering its
Internet services in the Seattle, Washington, Portland, Oregon and Phoenix,
Arizona areas and, as such, revenues to date have been limited.

Results of Operations

1998 Compared to 1997

     Revenue for 1998, was approximately $0.8 million compared to approximately
$1.1 million for the same period in 1997. The revenue for 1997 included
approximately $0.4 million of non-recurring equipment sales and construction
revenue associated with radio links installed for a third party.

                                      -14-
<PAGE>
 
     Operating costs and expenses were approximately $37.0 million for 1998,
compared to approximately $47.4 million in 1997. The Company initiated certain
restructuring activities in the third and fourth quarters of 1997 to align the
Company's organization more closely with its marketing and business development
plans and to conserve capital resources. While such restructuring activities
reduced certain expenses, in future periods the Company expects increases in
expenses for network operations and sales and marketing as the Company
implements its business plan. During 1998, the Company recorded approximately
$650,000 of non-recurring severance expenses and non-cash compensation charges
of approximately $657,500 with respect to a deferred stock grant. In 1997, the
Company incurred a charge of approximately $1.2 million with respect to a
deferred stock grant and other compensation expenses. The Company incurred non-
recurring severance and office closure costs of approximately $1.0 million in
the third and fourth quarters of 1997. Cost of equipment sales and construction
of approximately $0.3 million incurred in the 1997 period related to non-
recurring equipment sales and construction revenue. During the fourth quarter of
1998, the Company recorded an additional accrued liability for sales and
property taxes of approximately $3.3 million, of which approximately $2.4
million was charged to operations in the fourth quarter of 1998. Depreciation
and amortization was approximately $7.4 million for 1998, compared to
approximately $6.0 million for 1997. The increase was primarily due to
amortization of additional FCC licenses and equipment placed in service. In
1998, the Company recorded approximately $2.8 million to write down equipment
which is not expected to be utilized in its broadband data network. In 1997, the
Company recorded an equipment charge of approximately $8.1 million, which
included a charge of approximately $7.2 million to write down equipment not
expected to be utilized in its broadband data network. The Company expects to
record an additional charge of approximately $6.4 million in the first quarter
of 1999 to write down the carrying value of additional equipment which the
Company determined, in the first quarter of 1999, will not be used in its
broadband data network build out.

     Net interest and other expenses were approximately $20.0 million for 1998
compared to approximately $16.8 million for 1997. Included in net interest and
other expenses for 1998 was a charge of approximately $448,000 related to an
unsuccessful high yield debt offering and a charge of approximately $1.0 million
related to the amortization of deferred financing costs related to the financing
commitment under the Working Capital Facility (defined below). Included in net
interest and other expenses for 1997 was approximately $2.7 million related to a
financing commitment which was terminated in 1997 upon the sale of the Company's
14% Senior Notes due 2007 (the "Senior Notes"). Interest expense will also
increase in future quarters as a result of borrowings under the Working Capital
Facility and Purchase Money Facility (defined below).

     Deferred income tax benefit was approximately $9.1 million for 1998
compared to approximately $1.4 million in 1997 as a result of a change in tax
law which increased the net operating loss carryforward period from 15 to 20
years.

1997 Compared to 1996

     Revenues for the year ended December 31, 1997 were approximately $1.1
million compared to $2.9 million in 1996. Included in revenues was approximately
$0.4 million in 1997 and $2.7 million in 1996 representing non-recurring sales
and construction revenue associated with radio links installed for a third
party.

     Operating costs and expenses were approximately $47.4 million for the year
ended December 31, 1997 compared to approximately $25.7 million in 1996. The
increase was primarily due to an overall increase in expenses associated with
the commencement of commercial operations. Included in operating costs and
expenses for 1997 and 1996 was approximately $0.3 million and $1.6 million,
respectively, related to non-recurring sales and construction revenue. Sales and
marketing expenses in 1996 included a $1.1 million charge relating to a
distribution agreement. General and administrative expenses in 1996 included
$7.6 million of non-cash compensation charges, including $6.8 million related to
release of escrowed shares to executive officers. In connection with employment
arrangements with its new Chairman and Chief Executive Officer, the Company
incurred a charge of approximately $1.2 million in 1997 with respect to a
deferred stock grant and other expenses. During 1997 the Company recorded $8.1
million of non-cash equipment charges, including approximately $7.2 million to
write down certain radio equipment that is not expected to be an integral part
of the Company's broadband data network. The Company incurred non-recurring
severance and office closure costs of approximately $1.0 million in the third
and fourth quarters of 1997 in connection with management-initiated
restructuring activities intended to align the Company's organization with its
marketing and business 

                                      -15-
<PAGE>
 
development plans and to conserve capital resources. Depreciation and
amortization was approximately $6.0 million for 1997 compared to approximately
$1.0 million in 1996. The increase was due to additional equipment placed in
service and amortization of FCC licenses.

     Net interest and other expenses were approximately $16.8 million for the
year ended December 31, 1997 compared to $6.5 million in 1996. Interest expense
increased in 1997 due to increased borrowings in 1997. Included in interest and
other expenses was approximately $2.7 million in 1997 and $3.7 million in 1996
related to a financing commitment which was terminated in 1997 upon the sale of
the Senior Notes. The issuance of the Senior Notes in February 1997 caused
interest expense to increase substantially and will continue to cause interest
expense to increase in future periods. Interest income increased due to the
purchases of short-term investments and pledged securities. The early repayment
in November 1996 of bridge financings resulted in a non-cash extraordinary loss
of approximately $1.3 million arising from the write-off of associated
unamortized offering discount and deferred financing costs.

Liquidity and Capital Resources

     Through December 31, 1998, funding for the Company's acquisitions, capital
expenditures and net operating losses has been provided from private placements
of equity and bridge financings in 1994 through 1996, the Company's initial
public offering in November 1996, the Company's public offering of units
consisting of its Senior Notes and warrants in February 1997, and the borrowings
from Lucent Technologies Inc. ("Lucent") described below in 1998. Approximately
$51 million of the approximately $130 million net proceeds from the sale of the
units was used to purchase a portfolio of U.S. Treasury securities that will
provide for interest payments on the Senior Notes through February 2000. Because
the Senior Notes have "significant original issue discount" for tax purposes,
the Company will not be able to deduct the interest expense related to the
accretion of this original issue discount for tax purposes.

     During 1998 and 1997, the Company issued approximately 4.5 million and 6
million shares of common stock, respectively to acquire certain FCC licenses. In
addition, as of December 31, 1998, the Company had agreements to acquire certain
additional FCC licenses for cash of approximately $4.3 million and other FCC
licenses for approximately 154,000 shares of common stock, which were
consummated subsequent to December 31, 1998. The Company may continue to acquire
additional licenses in exchange for common stock or cash.

     An option to acquire from the Company 12 38 GHz licenses in specified
markets in which the Company has more than one license was exercised in June
1997, with closing subject to FCC approval. The Company would receive
approximately $7.0 million on closing of such transaction.

     In September 1998, the Company and Lucent entered into a credit facility
(the "Working Capital Facility") for Lucent to provide the Company with up to
$25 million of unsecured revolving loans for working capital purposes. As of
December 31, 1998, the Company had drawn $17.5 million under the Working Capital
Facility and subsequent to December 31, 1998 has drawn the remaining $7.5
million. Loans made pursuant to the Working Capital Facility are due June 30,
1999, unless extended by Lucent to no later than September 17, 1999. The terms
of the Working Capital Facility require ART to apply debt or equity capital
raised by ART in excess of $50 million to permanently repay the Working Capital
Facility.

     In September 1998, the Company and Lucent entered into a purchase money
credit facility (the "Purchase Money Facility") setting forth the terms and
conditions under which Lucent will provide purchase money financing in an
aggregate amount of up to $200 million, to be used to finance the purchase of
the Company's data network from Lucent. The Company has borrowed $10 million in
initial purchase money loans (the "Initial Purchase Money Loans") under the
Purchase Money Facility. No additional amounts are currently available to the
Company under the Purchase Money Facility. Subject to certain conditions,
including ART's raising at least $50 million of certain debt or equity capital
and repayment and termination of the Working Capital Facility, Lucent will make
available purchase money loans equal to 200% of the aggregate capital raised,
not to exceed $200 million (including the $10 million Initial Purchase Money
Loans). There can be no assurance that the funding contemplated by the Purchase
Money Facility will become available to ART.

                                      -16-
<PAGE>
 
     In July 1998, ART and Lucent entered into a definitive purchase agreement
(the "Lucent Purchase Agreement"), which amended and restated the Company's
purchase agreement with Lucent entered into in April 1998, under which Lucent
will design, engineer and construct the Company's wireless broadband data
network. The Company's purchase commitment under the Lucent Purchase Agreement
is initially $240 million upon the availability from Lucent of $200 million of
purchase money loans under the Purchase Money Facility, and increases to $1.2
billion if Lucent agrees to increase the amount of ART's purchase money loans to
$600 million on terms that are acceptable to ART. The Company's commitment is
subject to various other terms and conditions, including the availability of
additional financing on terms that are acceptable to ART. Subsequent to December
31, 1998, the Company issued a purchase order for certain wireless network
equipment in the amount of $5 million under the Lucent Purchase Agreement.

     The Company will require significant additional capital to fully fund its
operations and its long-term broadband data network buildout and business plan.
The Company currently estimates that it will require in excess of $1 billion
over the next several years to fund capital expenditures, working capital and
operations. The Company has limited financial resources, has incurred recurring
losses from operations since inception and does not expect to generate
significant operating revenues in the near term. The Company's ability to
continue as a going concern at least through December 31, 1999, which includes
funding of its operations and business plan, the repayment of the $25 million
Working Capital Facility and funding of its contractual commitments, is
dependent upon its ability to raise additional financing. The Company has
engaged investment bankers to assist it in obtaining financing and is in
negotiations with potential investors to provide equity financing. However,
there can be no assurance that the Company will be successful in its efforts to
obtain such financing, or, if available, that it 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.

Inflation

     Management does not believe that its business is impacted by inflation to a
significantly different extent than is the general economy.

Year 2000 Disclosure

     Many existing computer programs use only two digits, rather than four, to
represent a year. Date-sensitive software or hardware written or developed in
this fashion may not be able to distinguish between 1900 and 2000, and programs
written in this manner that perform arithmetic operations, comparisons or
sorting of date fields may yield incorrect results when processing a Year 2000
date. This Year 2000 problem could potentially cause system failures or
miscalculations that could disrupt operations.

The Company's State of Readiness

     The Company has implemented a survey to identify Year 2000 issues in three
areas: (i) financial and information technology systems (ii) non-IT network
equipment and (iii) third-party vendors and suppliers. The Company believes its
financial and information technology systems and its non-IT equipment will be
Year 2000 compliant by the end of 1999.

     Because the Company's financial and information technology systems are
relatively new, having been purchased in 1996 or thereafter, the Company does
not expect to uncover any material noncompliant systems. The Company completed
its survey of financial and information technology systems in the first quarter
of 1999. As a result of the survey, the Company does not believe there are any
material noncompliant systems. However, the Company is conducting detailed
verification testing to confirm the results of its survey. If Year 2000 issues
are discovered, the Company will evaluate and prioritize the problems. The
Company expects to coordinate any Year 2000 problems with the vendors that
supplied the noncompliant systems. The Company expects that any remediation
efforts would continue through mid-1999. However, there can be no assurance that
the Company's survey will identify all Year 2000 problems in these systems or
that the necessary corrective actions will be completed in a timely manner.

                                      -17-
<PAGE>
 
     The Company has received warranties from its network equipment suppliers
and integrators, including Lucent, that the Company's non-IT network equipment
is Year 2000 compliant. In addition, the tests conducted by the Company before
accepting delivery of such network equipment are designed to confirm whether the
equipment is Year 2000 compliant. Based on these warranties and acceptance
tests, the Company does not plan to take further action to ascertain whether its
network equipment is Year 2000 compliant. However, there can be no assurance
that this equipment will be Year 2000 compliant as warranted or that the
acceptance tests will identify all Year 2000 problems. In addition, the Year
2000 warranties that the Company has received limit the damages that the Company
would be able to recover if such systems were not Year 2000 compliant. The
Company is also reviewing the Year 2000 compatibility of its network management
software. If the Company discovers that this software is not Year 2000
compliant, it expects to coordinate its remediation efforts with the software
provider to remediate the system. The Company expects that these remediation
efforts, if any, will continue through mid-1999.

     The Company's survey is also assessing the Company's vulnerability to the
Year 2000 problems of third-party service suppliers and is communicating with
suppliers regarding the problem. The Company relies on third-party suppliers to
deliver fiber telecommunications links, Internet access, network equipment,
banking services and payroll services. The Company also intends to develop new
relationships with several providers of fiber-optic telecommunications service,
Internet service providers, telecommunications resellers and other companies in
the telecommunications industry. The Company intends to continuously identify
and prioritize critical suppliers and communicate with them about their plans
and progress in addressing the Year 2000 problem.

The Company's Year 2000 Risk

     Based on the efforts described above, the Company currently believes that
its systems will be Year 2000 compliant in a timely manner. The Company
completed its survey of financial and information technology systems and non-IT
systems in the first quarter of 1999 and expects to complete any remediation
efforts by the end of the third quarter 1999. However, there can be no assurance
that all Year 2000 problems will be successfully identified, or that the
necessary corrective actions will be completed in a timely manner. Failure to
successfully identify and remediate such Year 2000 problems in a timely manner
could have a material adverse effect on the Company's results of operations,
financial position or cash flow.

     In addition, the Company believes that there is a risk relating to
significant service suppliers' failure to remediate their Year 2000 issues in a
timely manner. Although the Company is communicating with its suppliers
regarding the Year 2000 problem, the Company does not know whether these
suppliers' systems will be Year 2000 compliant in a timely manner. Like most
telecommunications providers, the Company's ability to provide service is
dependent on key suppliers and equipment vendors. If one or more significant
suppliers are not Year 2000 compliant, this could have a material adverse effect
on the Company's results of operations, financial position or cash flow.

The Company's Contingency Plans

     The Company has not created a formal contingency plan for Year 2000
problems. The Company intends to take appropriate actions to mitigate the
effects of third parties' failures to remediate their Year 2000 issues and for
unexpected failures in its own systems. Such actions may include having
arrangements for alternate suppliers and using manual intervention where
necessary. If it becomes necessary for the Company to take these corrective
actions, it is uncertain whether this would result in significant interruptions
in service or delays in business operations or whether it would have a material
adverse effect on the Company's results of operations, financial position or
cash flow.

Costs of Year 2000 Remediation

     As of December 31, 1998, the Company has not incurred material costs
related to the Year 2000 problem, and does not expect to in the future. The
Company has not deferred other information technology projects due to Year 2000
expenses, and does not expect to defer such projects in the future. However,
there can be no assurance that the costs associated with the Year 2000 problem
will not be greater than anticipated.

                                      -18-
<PAGE>
 
     Readers are cautioned that forward-looking statements contained in the Year
2000 Disclosure should be read in conjunction with the Company's disclosures
under the heading: "Cautionary Statement" below.

Cautionary Statement

     This Item and other Items in this Report include "forward-looking"
information as that term is defined in the Private Securities Litigation Reform
Act of 1995 or by the Securities and Exchange Commission in its rules,
regulations and releases. The Company cautions investors that any such
statements made by the Company are not guarantees of future performance and that
known and unknown risks, uncertainties and other factors including those risk
factors identified in Exhibit 99 to this Report may cause actual results to
differ materially from those in the forward-looking statements. The Company does
not undertake to update or revise its forward-looking statements publicly even
if experience or future changes make it clear that any projected results
expressed or implied herein will not be realized.

                                      -19-
<PAGE>
 
ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

                       REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Directors and Stockholders of
Advanced Radio Telecom Corp.

     In our opinion, the accompanying consolidated balance sheets and the
related consolidated statements of operations and stockholders' equity (deficit)
and of cash flows present fairly, in all material respects, the financial
position of Advanced Radio Telecom Corp. and Subsidiaries at December 31, 1998
and 1997, and the results of their operations and their cash flows for each of
the three years in the period ended December 31, 1998, in conformity with
generally accepted accounting principles. 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 of these statements in accordance with generally accepted auditing
standards which 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, assessing the
accounting principles used and significant estimates made by management, and
evaluating the overall financial statement presentation. We believe that our
audits provide a reasonable basis for the opinion expressed above.

     The accompanying financial statements have been prepared assuming that the
Company will continue as a going concern. As discussed in Note 1 to the
financial statements, the Company has limited financial resources, requires
significant additional capital to fund its operations and business plan and has
incurred recurring losses from operations since inception and does not expect to
generate significant operating revenues in the near term. The Company's
continued funding of its operations and business plan is dependent upon its
ability to raise additional financing. These conditions raise substantial doubt
about the Company's ability to continue as a going concern. Management's plans
in regard to these matters are also described in Note 1. The financial
statements do not include any adjustments that might result from the outcome of
this uncertainty.

PriceWaterhouseCoopers LLP


Seattle, Washington 
March 29, 1999

                                      F-1
<PAGE>
 
                 ADVANCED RADIO TELECOM CORP. AND SUBSIDIARIES

                          CONSOLIDATED BALANCE SHEETS

                          December 31, 1998 and 1997
<TABLE>
<CAPTION>
                                                                                1998             1997 
                                                                            -------------    -------------
<S>                                                                         <C>              <C>
                                     ASSETS
Current assets:
     Cash and cash equivalents ..........................................   $  11,864,218    $   7,135,427
     Short-term investments .............................................                       18,210,220 
     Pledged securities .................................................      18,504,263       18,517,640
     Restricted cash ....................................................          32,060        1,032,060
     Accounts receivable ................................................         125,976          199,316
     Prepaid expenses and other current assets ..........................         681,468          112,825
                                                                            -------------    -------------
                  Total current assets ..................................      31,207,985       45,207,488
Pledged securities ......................................................       8,854,569       25,842,275
Property and equipment, net .............................................      33,202,310       25,294,946
FCC licenses, net .......................................................     186,513,591      131,210,102
Deferred financing costs, net ...........................................       5,503,172        4,502,330
Other assets ............................................................         439,664          502,608
                                                                            -------------    -------------
         Total assets ...................................................   $ 265,721,291    $ 232,559,749
                                                                            =============    =============
                      LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
     Working capital facility ...........................................   $  16,229,121
     Book overdraft .....................................................                    $   3,055,759
     Trade accounts payable .............................................       2,533,612        3,067,984
     Accrued compensation and benefits ..................................       2,936,454        1,775,646
     Other accrued liabilities ..........................................       4,759,689        3,109,631
     Accrued interest payable ...........................................       7,154,224        7,113,391
     Current portion of long-term debt ..................................         525,313        1,476,256
                                                                            -------------    -------------
         Total current liabilities ......................................      34,138,413       19,598,667
Long-term debt, net of current portion ..................................     117,845,932      106,823,103
Deferred income tax liabilities .........................................      31,382,026       29,880,916
                                                                            -------------    -------------
         Total liabilities ..............................................     183,366,371      156,302,686
                                                                            -------------    -------------

Commitments and contingencies (Note 9)

Stockholders' equity:
         Common stock, $.001 par value, 100,000,000 shares authorized,
                  26,707,036 and 21,429,485 shares issued and outstanding          26,707           21,429
     Additional paid-in capital .........................................     225,967,684      172,892,420
     Note receivable from stockholder ...................................        (887,500)        (887,500)
     Accumulated deficit ................................................    (142,751,971)     (95,769,286)
                                                                            -------------    -------------
         Total stockholders' equity .....................................      82,354,920       76,257,063
                                                                            -------------    -------------
              Total liabilities and stockholders' equity ................   $ 265,721,291    $ 232,559,749
                                                                            =============    =============
</TABLE>
The accompanying notes are an integral part of the consolidated financial
statements.

                                      F-2
<PAGE>
 
                 ADVANCED RADIO TELECOM CORP. AND SUBSIDIARIES

                     CONSOLIDATED STATEMENTS OF OPERATIONS

             for the years ended December 31, 1998, 1997 and 1996
<TABLE>
<CAPTION>
                                                                        1998            1997            1996 
                                                                    ------------    ------------    ------------
<S>                                                                 <C>             <C>             <C>
Service revenue .................................................   $    840,822    $    708,883    $    247,116
Equipment sales and construction revenue ........................                        396,970       2,660,811
                                                                    ------------    ------------    ------------
         Total revenue ..........................................        840,822       1,105,853       2,907,927
                                                                    ------------    ------------    ------------
Costs and expenses:
     Technical and network operations ...........................      8,603,576       7,252,512       3,402,948
     Cost of equipment sales and construction ...................                        254,444       1,590,779
     Sales and marketing ........................................      5,679,222      13,469,898       5,548,584
     General and administrative .................................     11,992,874      12,789,866      12,896,134
     Research and development ...................................        593,595         421,236       1,269,579
     Equipment impairment .......................................      2,753,105       7,166,720
     Depreciation and amortization ..............................      7,354,378       6,018,172       1,017,959
                                                                    ------------    ------------    ------------
         Total operating costs and expenses .....................     36,976,750      47,372,848      25,725,983
                                                                    ------------    ------------    ------------
Operating loss ..................................................    (36,135,928)    (46,266,995)    (22,818,056)

Interest and other:
     Interest expense ...........................................     21,173,374      18,931,303       1,695,489
     Financing commitment expense ...............................      1,004,393       2,699,881       3,687,644
     Interest income ............................................     (2,693,257)     (4,814,004)       (118,882)
     Other ......................................................        494,484                       1,248,000
                                                                    ------------    ------------    ------------
         Loss before income taxes and extraordinary item ........    (56,114,922)    (63,084,175)    (29,330,307)

Deferred income tax benefit .....................................      9,132,237       1,355,249
                                                                    ------------    ------------    ------------
         Loss before extraordinary item .........................    (46,982,685)    (61,728,926)    (29,330,307)
Extraordinary loss on early retirement of debt ..................                                     (1,339,996)
                                                                    ------------    ------------    ------------
         Net loss ...............................................   $(46,982,685)   $(61,728,926)   $(30,670,303)
                                                                    ============    ============    ============


Basic and diluted loss per common share before extraordinary item   $      (1.89)   $      (3.23)   $      (3.80)
Basic and diluted extraordinary loss per common share ...........                                          (0.17)
                                                                    ------------    ------------    ------------
Basic and diluted net loss per common share .....................   $      (1.89)   $      (3.23)   $      (3.97)
                                                                    ============    ============    ============

         Weighted average common shares .........................     24,890,177      19,083,304       7,717,755
                                                                    ============    ============    ============
</TABLE>

The accompanying notes are an integral part of the consolidated financial
statements.

                                      F-3
<PAGE>
 
                 ADVANCED RADIO TELECOM CORP. AND SUBSIDIARIES

           CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)

             for the years ended December 31, 1998, 1997 and 1996
<TABLE>
<CAPTION>
                                                                                                        Serial
                                                                    Common Stock                    Preferred Stock
                                                             --------------------------          ------------------------
                                                               Shares       Par Value            Shares       Par Value
                                                             ---------    -------------          -------    -------------
<S>                                                          <C>          <C>                    <C>        <C>
Balance, December 31, 1995 ...........................       6,529,975       $ 6,530               488,492          $ 488 
Issuance of serial preferred stock for cash ..........                                             232,826            233 
Shares issued to reflect anti-dilution adjustments ...          56,984            57               150,740            151 
Issuance of serial preferred stock and warrants
 in exchange for cash and the strategic
 distribution agreement ..............................                                              48,893             49 
Preferred stock issuance costs .......................                                                                    
Increase in additional paid-in capital as a result
 of the release of Escrow Shares .....................                                                                    
Value ascribed to the equipment financing warrants ...                                                                    
Value ascribed to the bridge financing warrants ......                                                                    
Issuance of common stock in an initial public offering       2,300,500         2,301
Initial public offering common stock issuance costs ..                                                                    
Conversion of preferred stock to common stock
 in connection with the initial public offering ......       4,353,587         4,353              (920,951)          (921)
Value ascribed to the CIBC Warrants ..................                                                                    
Accrued stock option compensation ....................                                                                    
Warrants exercised ...................................         318,374           318                                   
Net loss .............................................
                                                            ----------       -------              --------           ----
Balance, December 31, 1996 ...........................      13,559,420        13,559                                   
Common stock issued in connection with the
  acquisition of the CommcoCCC, Inc. licenses ........       6,000,000         6,000                                   
Value ascribed to warrants issued with
  Senior Notes .......................................                                                                    
Warrant issuance costs ...............................                                                                    
Accrued stock option compensation ....................                                                                    
Stock options exercised ..............................         286,100           286                                   
Warrants exercised ...................................       1,583,965         1,584                                   
Common stock issuable for note receivable
 from stockholder ....................................                                                                    
Common stock issuable under employment agreement .....                                                                    
Net loss .............................................
                                                            ----------       -------              --------           ----
Balance December 31, 1997 ............................      21,429,485       $21,429                                   
Common stock issued in connection with the
  acquisition of certain FCC licenses ................       4,529,519         4,530                                   
Common stock issued for note receivable
 from stockholder ....................................         100,000           100                                   
Value ascribed to warrants issued in connection
  with the working capital facility ..................                                                                    
Warrants exercised ...................................         632,314           632                                   
Stock options exercised ..............................          15,718            16                                   
Accrued stock option compensation ....................                                                                    
Common stock issuable under employment
  agreements .........................................                                                                    
Net loss .............................................
                                                            ----------       -------              --------           ----
Balance December 31, 1998 ............................      26,707,036       $26,707
                                                            ==========       =======              ========           ====
<CAPTION>

                                                                               Note
                                                             Additional      Receivable
                                                              Paid-In          from          Accumulated
                                                              Capital       Stockholder        Deficit            Total
                                                           ------------     -----------     ------------       -----------
<S>                                                        <C>              <C>             <C>                <C>
Balance, December 31, 1995 ...........................     $  3,050,179                     $ (3,370,057)      $  (312,860)    
Issuance of serial preferred stock for cash ..........        4,672,953                                          4,673,186     
Shares issued to reflect anti-dilution adjustments ...             (208)
Issuance of serial preferred stock and warrants                                                                                
 in exchange for cash and the strategic                                                                                        
 distribution agreement ..............................        3,552,951                                          3,553,000     
Preferred stock issuance costs .......................         (150,000)                                          (150,000)    
Increase in additional paid-in capital as a result                                                                             
 of the release of Escrow Shares .....................        6,795,514                                          6,795,514     
Value ascribed to the equipment financing warrants ...          484,937                                            484,937     
Value ascribed to the bridge financing warrants ......        1,795,533                                          1,795,533     
Issuance of common stock in an initial public offering       34,505,199                                         34,507,500     
Initial public offering common stock issuance costs ..       (6,081,098)                                        (6,081,098)    
Conversion of preferred stock to common stock                                                                                  
 in connection with the initial public offering ......           (3,432)                                                       
Value ascribed to the CIBC Warrants ..................        4,503,848                                          4,503,848     
Accrued stock option compensation ....................          850,663                                            850,663     
Warrants exercised ...................................             (318)                                                       
Net loss .............................................                                        (30,670,303)     (30,670,303)
                                                            -----------        ----------     -----------      ------------  
Balance, December 31, 1996 ...........................       53,976,721                       (34,040,360)      19,949,920     
Common stock issued in connection with the                                                                                     
  acquisition of the CommcoCCC, Inc. licenses ........       87,744,000                                         87,750,000     
Value ascribed to warrants issued with                                                                                         
  Senior Notes .......................................       29,707,509                                         29,707,509     
Warrant issuance costs ...............................       (1,254,698)                                        (1,254,698)    
Accrued stock option compensation ....................          449,313                                            449,313     
Stock options exercised ..............................          496,159                                            496,445     
Warrants exercised ...................................           (1,584)                                                       
Common stock issuable for note receivable                                                                                      
 from stockholder ....................................          887,500        $(887,500)                                      
Common stock issuable under employment agreement .....          887,500                                            887,500     
Net loss .............................................                                        (61,728,926)     (61,728,926)
                                                            -----------        ----------     -----------      ------------      
Balance December 31, 1997 ............................     $172,892,420        $(887,500)   $ (95,769,286)   $  76,257,063     
Common stock issued in connection with the                                                                                     
  acquisition of certain FCC licenses ................       48,343,268                                         48,347,798     
Common stock issued for note receivable                                                                                        
 from stockholder ....................................             (100)                                                       
Value ascribed to warrants issued in connection                                                                                
  with the working capital facility ..................        3,282,351                                          3,282,351     
Warrants exercised ...................................           19,057                                             19,689     
Stock options exercised ..............................           94,445                                             94,461     
Accrued stock option compensation ....................          678,743                                            678,743     
Common stock issuable under employment                                                                                         
  agreements .........................................          657,500                                            657,500     
Net loss .............................................                                        (46,982,685)     (46,982,685)
                                                            -----------        ----------     -----------      ------------      
Balance December 31, 1998 ............................     $225,967,684        $ (887,500)  $(142,751,971)   $  82,354,920   
                                                            ===========        ==========     ===========      ============
</TABLE>

The accompanying notes are an integral part of the consolidated financial
statements.

                                      F-4
<PAGE>
 
                 ADVANCED RADIO TELECOM CORP. AND SUBSIDIARIES

                     CONSOLIDATED STATEMENTS OF CASH FLOWS

             for the years ended December 31, 1998, 1997 and 1996
<TABLE>
<CAPTION>
                                                                      1998             1997             1996 
                                                                 -------------    -------------    -------------
<S>                                                              <C>              <C>              <C>
Cash Flows from operating activities:
     Net loss ................................................    $(46,982,685)    $(61,728,926)    $(30,670,303)
     Adjustments to reconcile net loss to net cash
         used in operating activities:
       Non-cash compensation expense .........................       1,336,243        1,336,813        7,646,177
       Non-cash equipment charges ............................       2,753,105        8,100,859
       Non-cash marketing expense ............................                                         1,053,000
       Depreciation and amortization .........................       7,354,378        6,018,172        1,017,959
       Non-cash interest expense .............................       1,699,784        1,466,698          772,221
       Non-cash financing commitment expense .................       1,004,393        2,699,881        3,687,644
       Deferred income tax benefit ...........................      (9,132,237)      (1,355,249)
       Extraordinary loss on early debt retirement ...........                                         1,339,996
       Changes in operating assets and liabilities:
         Accrued interest payable ............................          40,833        7,096,232           17,159
         Accounts receivable .................................          73,340        1,620,277       (1,819,593)
         Accrued interest on investments and securities ......      (1,928,243)      (2,194,497)
         Accounts payable and other current liabilities ......       4,164,189        1,098,448        3,615,884
         Prepaid expenses and other current assets ...........        (568,643)          83,966         (144,466)
         Other assets ........................................          62,944         (137,321)
                                                                 -------------    -------------    -------------
              Net cash used in operating activities ..........     (40,122,599)     (35,894,647)     (13,484,322)
                                                                 -------------    -------------    -------------

Cash flows from investing activities:
     Purchases of property and equipment .....................      (5,678,062)     (24,051,854)      (9,439,481)
     Additions to and acquisitions of FCC licenses ...........        (518,278)      (5,747,844)      (3,201,183)
     Purchases of pledged securities .........................                      (51,245,250)
     Purchases of short-term investments .....................      (9,126,454)     (47,065,154)
     Proceeds from sales of short-term investments ...........      27,636,000       29,071,448
     Proceeds from maturities of pledged securities ..........      18,630,000        8,863,315
     Investment in restricted cash ...........................                                        (1,032,060)
     Proceeds from maturities of restricted cash .............       1,000,000
     Proceeds from the disposition of property and equipment .         621,101           88,718
     Additions to other assets ...............................                                        (1,425,032)
                                                                 -------------    -------------    -------------
         Net cash provided by (used in) investing activities .      32,564,307      (90,086,621)     (15,097,756)
                                                                 -------------    -------------    -------------

Cash flows from financing activities:
     Proceeds from issuance of Senior Notes and warrants .....                      135,000,000
     Warrant issuance costs ..................................                       (1,254,698)
     Proceeds from issuance of common stock ..................         114,150          496,445       34,507,500
     Proceeds from issuance of preferred stock ...............                                         2,500,000
     Stock issuance costs ....................................                                        (6,231,098)
     Proceeds from certain loans and debt financings .........      17,500,000                        14,445,000
     Book overdraft ..........................................      (3,055,759)       3,055,759
     Repayments of certain loans and debt financings .........      (1,727,053)      (2,018,743)     (13,131,443)
     Additions to deferred financing costs ...................        (544,255)      (4,136,475)      (2,167,128)
                                                                 -------------    -------------    -------------
         Net cash provided by financing activities ...........      12,287,083      131,142,288       29,922,831
                                                                 -------------    -------------    -------------

Net increase in cash and cash equivalents ....................       4,728,791        5,161,020        1,340,753
Cash and cash equivalents, beginning of period ...............       7,135,427        1,974,407          633,654
                                                                 -------------    -------------    -------------
Cash and cash equivalents, end of period .....................   $  11,864,218    $   7,135,427    $   1,974,407
                                                                 =============    =============    =============
</TABLE>
The accompanying notes are an integral part of the consolidated financial
statements.

                                      F-5
<PAGE>
 
                 ADVANCED RADIO TELECOM CORP. AND SUBSIDIARIES

                  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS


1.   The Company and Basis of Presentation:

     Advanced Radio Telecom Corp. (collectively with its subsidiaries, "ART" or
the "Company") provides wireless broadband telecommunications services in the 38
GHz band of the radio spectrum. From its inception in 1993 to the fourth quarter
of 1996, the Company primarily focused on the acquisition of spectrum rights,
hiring managements and other key personnel, raising capital, acquiring equipment
and roof rights and developing operating and support systems to support its
initial business of selling connectivity to various telecommunications companies
as a wholesale carriers' carrier, which commenced in the fourth quarter of 1996.
The Company altered its strategy in 1998 to sell a variety of broadband Internet
services to end-user customers and to deploy a broadband data network. The
results from operations in 1997 reflect a business no longer being pursued by
the Company. During the year ended 1998, the Company began offering its Internet
services in the Seattle, Washington, Portland, Oregon and Phoenix, Arizona areas
and, as such, revenues to date have been limited.

     ART, formerly named Advanced Radio Technologies Corporation, was organized
as a Delaware corporation in August 1993. Advanced Radio Technology Ltd.,
renamed Advanced Radio Telecom Corp. ("Telecom"), was organized in March 1995 by
ART and Landover Holdings Corporation ("Landover") for the purpose of acquiring
certain 38 GHz licenses and to facilitate Landover's commitment to invest or
cause to invest $7 million in the Company. Pursuant to the related purchase,
shareholder, and services agreements, ART and Telecom were operated as a single
entity pending approval of their merger from the Federal Communications
Commission ("FCC"). Such approval was received and Telecom became a wholly-owned
subsidiary of ART by merger in October 1996. The merger was accounted for in a
manner consistent with a reorganization of entities under common control which
is similar to that of a pooling of interests, and the financial statements of
prior periods have been restated.

     The Company will require significant additional capital to fully fund its
operations, long-term broadband data network buildout and business plan. The
Company currently estimates that it will require in excess of $1 billion over
the next several years to fund capital expenditures, working capital and
operations. During 1998, the Company and Lucent Technologies Inc. ("Lucent")
entered into a credit facility for Lucent to provide the Company with up to $25
million of unsecured revolving loans for working capital purposes, due June 30,
1999 unless extended by Lucent. During 1998, the Company and Lucent also entered
into a purchase money credit facility ("the "Purchase Money Facility") setting
forth the terms and conditions under which Lucent will provide purchase money
financing of up to $200 million, to be used to finance the purchase of the
Company's broadband data networks from Lucent. Lucent has made available $10
million in initial purchase money loans and the availability of the balance is
subject to other conditions, including the Company's ability to raise at least
$50 million of certain debt or equity capital. There can be no assurance that
the funding will become available to the Company.

     The consolidated financial statements have been prepared assuming that the
Company will continue as a going concern, which contemplates the realization of
assets and liquidation of liabilities in the ordinary course of business. The
Company has limited financial resources, has incurred recurring losses from
operations since inception and does not expect to generate significant operating
revenues in the near term. The Company's ability to continue as a going concern
at least through December 31, 1999, which includes funding of its operations and
business plan, the repayment of the $25 million working capital facility and
funding of its contractual commitments, is dependent upon its ability to raise
additional financing. The Company has engaged investment bankers to assist it
in obtaining financing and is in negotiations with potential investors to
provide equity financing. However, there can be no assurance that the Company
will be successful in its efforts to obtain such financing, or, if available,
that it 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 consolidated financial statements do not include any adjustments that might
result from the outcome of this uncertainty.

                                      F-6
<PAGE>
 
2.       Summary of Significant Accounting Policies:

Consolidation

     The consolidated financial statements include all majority owned
subsidiaries in which the Company has the ability to exercise control. All
intercompany transactions have been eliminated in consolidation.

Development Stage Enterprise

     During 1996, the Company commenced commercial operations, and was no longer
considered to be in the development stage as defined in Statement of Financial
Accounting Standards No. 7, "Accounting and Reporting by Development Stage
Enterprises." Such change in classification of the Company had no impact on the
net loss or stockholders' equity (deficit) for any periods presented.

Cash and Cash Equivalents

     The Company considers all highly liquid investments purchased with
remaining maturities of three months or less to be cash equivalents. The Company
places its temporary cash investments with major financial institutions in
amounts which may exceed Federally insured limits. At December 31, 1998, the
Company's temporary cash investments were principally placed in two entities.
Checks issued but not presented to banks are classified as "Book overdrafts" for
accounting purposes in the consolidated balance sheet.

Short-term Investments and Pledged Securities

     Short-term investments are comprised of commercial paper and other similar
investments purchased with a term to maturity of more than three months.
Short-term investments are held as available for sale and are carried at market
value. Pledged securities consist of U.S. Treasury securities that are held to
maturity and are carried at amortized cost.

Property and Equipment

     Property and equipment are stated at cost. Depreciation and amortization
are computed using the straight-line method over the estimated useful lives,
generally three to five years for wireless network equipment placed in service
and other property and equipment. Subsequent to year end, the Company reduced
the estimated useful lives of certain wireless network equipment not yet placed
in service from five years to two years.

     The costs of normal maintenance and repairs are charged to expense as
incurred. Direct costs of placing assets into service and major improvements are
capitalized. Gains or losses on the disposition of assets are recorded at the
time of disposition.

Capitalized Software

     Purchased software used for internal purposes is capitalized at cost and
amortized over its estimated useful life, which is generally three years.

FCC Licenses

     The direct costs of obtaining 38 GHz radio spectrum licenses by grant from
the FCC or by purchase from others and the cost of perfecting such licenses are
capitalized and amortized on a straight-line basis over a 40 year period.
Accumulated amortization as of December 31, 1998 and 1997 totaled $7,174,629 and
$2,930,798, respectively. All of the Company's licenses expire in 2001 and it is
management's expectation that they will be renewed by the FCC for successive ten
year periods.

                                      F-7
<PAGE>
 
Recoverability of Long-Lived Assets

     The recoverability of property and equipment and capitalized FCC licenses
is dependent on, among other things, the successful deployment of networks in
each of the respective markets, or sale of such assets. Management estimates
that it will recover the carrying amount of those costs from undiscounted cash
flows generated by the networks once they have been deployed. However, it is
reasonably possible that such estimates will change in the near term as a result
of technological, regulatory or other changes. The Company periodically reviews
the carrying value of its capitalized assets for impairment and recoverability.

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 are charged to
additional paid-in capital as the related funds are raised. Deferred costs
associated with unsuccessful financings are charged to expense. The Company
charged approximately $448,000 and $1,248,000 to other expense during the years
ended December 31, 1998 and 1996, respectively, associated with unsuccessful
financings. Direct costs of obtaining commitments for financing are deferred and
charged to expense over the term of the commitments. Accumulated amortization of
deferred financing costs totaled $1,338,248 and $290,756 at December 31, 1998
and 1997, respectively.

Revenue Recognition

     Revenue from telecommunications services is recognized ratably over the
period such services are provided. Equipment sales and construction revenue is
recorded at the time the equipment is delivered and construction is completed.
Cost of equipment sales are based on the average cost method.

     Two customers accounted for approximately thirty-seven and forty-five
percent of the Company's service revenues in 1998 and 1997, respectively, and a
single customer accounted for approximately forty-two percent of the Company's
service revenue in 1996. Additionally, the Company entered into an equipment
sales and construction services agreement with another customer during 1996 to
act as a sub-contractor to provide transmission facilities construction services
and the related wireless transmission equipment. This agreement was
substantially completed during 1996 and total equipment sales and construction
revenues are attributable to this customer. Receivables from five customers
accounted for approximately forty-nine percent and fifty-three percent of trade
accounts receivable at December 31, 1998 and 1997, respectively.

Research and Development

     Research and development costs are charged to expense as incurred.

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

     During 1997 the Company adopted, and applied retroactively, Statement of
Financial Accounting Standards No. 128, "Earnings Per Share" ("SFAS 128"). This
statement specifies the computation, presentation, and disclosure requirements
for earnings per share ("EPS"), simplifies the computational guidelines, and
increases comparability on an international basis. This statement replaced
"primary" EPS with "basic" EPS, the principal difference being the exclusion of
common stock equivalents in the computation of basic EPS. In connection with the
adoption of SFAS 128, the 

                                      F-8
<PAGE>
 
Company also adopted the provisions of SEC Staff Accounting Bulletin No. 98
("SAB 98"), which provides for the inclusion of nominal issuances of potentially
dilative equity instruments in the calculation of net loss per share. The
adoption of SFAS 128 and SAB 98 by the Company had no impact on previously
reported net loss per share.

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 expenses during the reporting period.
Actual results could differ from those estimates. Management of the Company will
continue to evaluate the estimated useful lives of its wireless network
equipment based on changes in industry conditions.

3.   Property and Equipment:

     Property and equipment at December 31, were as follows:
<TABLE>
<CAPTION>
                                                           1998            1997 
                                                       ------------    ------------
<S>                                                    <C>             <C>
Wireless network equipment placed in service .......   $ 14,239,886    $  5,879,673
Wireless network equipment not yet placed in service     17,925,364      16,730,010
Computer hardware ..................................      1,723,871       1,673,288
Computer software ..................................      2,168,867         934,127
Office furniture and equipment .....................      1,681,409       1,601,190
Other equipment and vehicles .......................        489,220         489,220
                                                       ------------    ------------
                                                         38,228,617      27,307,508
Accumulated depreciation ...........................     (5,026,307)     (2,012,562)
                                                       ------------    ------------
                                                       $ 33,202,310    $ 25,294,946
                                                       ============    ============
</TABLE>

     Depreciation expense for the years ended December 31, 1998, 1997 and 1996
was $3,110,503, $3,021,380, and $909,163, respectively.

     During 1998 and 1997, the Company recorded non-cash equipment charges of
approximately $2.8 million and $8.1 million, respectively, primarily related to
the write-down of certain radio equipment that is not expected to be an integral
part of the Company's expanded broadband data network. The Company expects to
record an additional charge of approximately $6.4 million in the first quarter
of 1999 to write down the carrying value of additional equipment which the
Company determined, in the first quarter of 1999, would be disposed of and not
used in its future broadband network build out. The amount of the write-downs
are based on discounted projected future cash flows from such equipment under
current deployment plans or estimated salvage value.

     In 1998, the Company sold certain non-integral radio equipment with
proceeds of approximately $536,000, which approximated the carrying value.
Amounts receivable from this sale are included in other current assets at
December 31, 1998.

4.   Other Accrued Liabilities and Fourth Quarter Adjustments:

     During the fourth quarter of 1998, as a result of a re-evaluation of its
tax posture, the Company changed its estimate of its sales and property tax
liability and recorded an additional accrual of approximately $3.3 million of
which approximately $2.4 million was charged to operations in the fourth quarter
of 1998 and approximately $900,000 was capitalized as part of the cost of
equipment.

                                      F-9
<PAGE>
 
5.   FCC Licenses:

     CommcoCCC Licenses

     In June 1996, the Company agreed to acquire certain 38 GHz licenses from
CommcoCCC, Inc. ("CommcoCCC") in exchange for 6 million shares of the Company's
common stock, which acquisition was consummated in February 1997. The total
acquisition cost was approximately $122.2 million, comprised of the aggregate
market value of the common shares issued to CommcoCCC of approximately $88
million, direct costs of approximately $3.2 million and the related deferred tax
liability of approximately $31.2 million.

     In connection with transaction, the Company gave a stockholder of CommcoCCC
an option to acquire certain 38 GHz FCC licenses in specified markets, in which
the Company has more than one license. This option was exercised in July 1997 at
an exercise price of approximately $6.9 million, determined based on the sales
price of the Company's common stock on the date the option was exercised and the
population covered by the licenses. Final terms under this option were reached
in November 1998 and the exercise price will be paid in cash upon closing of the
sale, which is subject to FCC approval. The Company has the right to be a
reseller with respect to these licenses for a term of five years at market
rates.

     ART West Licenses

     In February 1997, the Company completed its acquisition from Extended
Communications, Inc. ("Extended") of the remaining 50% interest in ART West, a
partnership jointly controlled by Extended and the Company, for $6 million in
cash, of which $3 million was paid in 1996. ART West held certain 38 GHz
licenses that were transferred to the Company upon the completion of the
acquisition.

     Columbia Licenses

     In May 1998, the Company acquired from Columbia Capital Corporation and one
of its affiliates certain 38 GHz licenses for 1,335,750 shares of common stock.
The total acquisition cost was approximately $14.8 million, comprised of the
fair value of the 1,335,750 shares of common stock issued of approximately $12.0
million, direct costs incurred of approximately $92,000 and the related deferred
tax liability of approximately $2.7 million.

     DCT Licenses

     In May 1998, the Company acquired DCT Communications Inc., which held
certain 38 GHz licenses, in exchange for 3,124,875 shares of the Company's
common stock. The total acquisition cost was approximately $43.3 million,
comprised of the fair value of the 3,124,874 shares of common stock issued of
approximately $35.2 million, direct costs incurred of approximately $241,000 and
the related deferred tax liability of approximately $7.9 million.

     Other Licenses

     In March 1998, the Company acquired a certain 38 GHz license in exchange
for 68,895 shares of the Company's common stock. The total acquisition cost was
approximately $1.2 million, which consisted of the aggregate market value of the
shares issued and direct costs.

     In January 1999, the Company consummated acquisitions of certain 38 GHz
Licenses for $4.3 million in cash and certain other licenses for 154,114 shares
of common stock valued at approximately $1.3 million.

                                      F-10
<PAGE>
 
6.   Income Taxes:

A reconciliation of the Company's effective tax rate and the Federal statutory
rate for the years ended December 31, were as follows:
<TABLE>
<CAPTION>
                                                  1998              1997              1996 
                                             -------------     -------------     -------------
<S>                                          <C>               <C>               <C>
Net loss before taxes ....................   $ (56,114,922)    $ (63,084,175)    $ (30,670,303)
                                             =============     =============     =============
Federal income tax at
 statutory rate ..........................            35.0%             35.0%             35.0%
Non-deductible interest ..................            (0.8)             (0.6)
Non-deductible compensation ..............                                                (7.8)
State benefit, net of Federal tax benefit              2.0               2.0               1.6
Other ....................................            (0.1)             (0.1)
Valuation allowance ......................           (19.8)            (34.2)            (28.8)
                                             -------------     -------------     -------------
Effective income tax rate ................            16.3%              2.1%              0.0%
                                             =============     =============     =============
Income tax benefit .......................   $  (9,132,237)    $  (1,355,249)    $           0
                                             =============     =============     =============
</TABLE>
Deferred tax assets and liabilities at December 31, were as follows:
<TABLE>
<CAPTION>
                                                1998            1997 
                                            ------------    ------------
<S>                                         <C>             <C>
Deferred tax assets:
    Net operating loss carryforwards ....   $ 49,283,000    $ 28,385,000
    Equipment depreciation and impairment      1,965,000       3,071,000
    Accrued compensation and benefits ...        906,000         755,000
    Valuation allowance .................    (20,165,026)    (18,833,916)
                                            ------------    ------------
                                              31,988,974      13,377,084

Deferred tax liabilities:
       FCC Licenses .....................    (63,371,000)    (43,258,000)
                                            ------------    ------------
       Net deferred tax liabilities .....   $(31,382,026)   $(29,880,916)
                                            ============    ============
</TABLE>

     Differences between the tax bases of assets and liabilities and their
financial statement amounts are reflected as deferred income taxes based on
enacted tax rates. The net deferred tax assets have been reduced by a valuation
allowance based on management's determination that the recognition criteria for
realization has not been met. In 1998 and 1997, the Company reversed
approximately $10.8 million and $12.8 million, respectively, of its deferred tax
asset valuation allowance as a result of recording deferred taxes arising from
certain FCC license acquisitions.

     During the fourth quarter of 1998, the Company determined that its 1998
deferred income tax benefit was understated by approximately $6 million for a
change in the tax law that was not previously considered, which increased the
net operating loss carryforward period from 15 to 20 years. Accordingly, the
deferred income tax benefit was increased to approximately $9.1 million for the
year ended December 31, 1998. The Company has restated its 1998 quarterly
financial information to reflect the change in the tax law, increasing the
deferred income tax benefit to approximately $2.1 million, $2.2 million and $1.9
million and reducing its net loss to approximately $9.1 million, $9.6 million
and $13.7 million for the three months ended March 31, 1998, June 30, 1998 and
September 30, 1998, respectively.

     At December 31, 1998, the Company has accumulated net operating loss
carryforwards for Federal income tax purposes of approximately $133.2 million
which expire between 2008 and 2018. The Company's ability to use its net
operating losses to offset future income is subject to restrictions in the
Internal Revenue Code which could limit the Company's future use of its net
operating losses if certain stock ownership changes occur.

                                      F-11
<PAGE>
 
7.   Working Capital Facility:

     In September 1998, the Company and Lucent Technologies Inc. ("Lucent")
entered into a credit facility (the "Working Capital Facility") for Lucent to
provide the Company with up to $25 million of unsecured revolving loans for
working capital purposes. As of December 31, 1998, the Company had drawn $17.5
million under the Working Capital Facility. Interest initially accrues at an
annual rate of LIBOR plus 5% (10.7% at December 31, 1998) and increases 0.5%
each month beginning January 1999. The availability of the undrawn balance of
the Working Capital Facility is subject to the achievement of certain milestones
by the Company. Loans made pursuant to the Working Capital Facility, plus
accrued interest, are due June 30, 1999, unless extended by Lucent to no later
than September 17, 1999. The terms of the Working Capital Facility require the
Company to apply debt or equity capital raised by the Company in excess of $50
million to permanently repay the Working Capital Facility.

     ART issued warrants to purchase 277,892 shares of common stock at an
exercise price of $0.01 per share upon the Company obtaining a commitment from
Lucent for the Working Capital Facility and the warrants were valued at
approximately $1,777,000. The Company has recorded the value ascribed to these
warrants as deferred financing costs and as additional paid-in-capital.
Additionally, under the terms of the Working Capital Facility, the Company is
required to issue additional warrants to purchase common stock, at an exercise
price of $3.33 per share, each time a draw is made. In connection with $17.5
million drawn under the Working Capital Facility during 1998, the Company issued
warrants to purchase 447,972 shares of the Company's common stock. The aggregate
value ascribed to these warrants of approximately $1,505,000 was reflected as
both a debt discount and an increase in additional paid-in capital.

     Subsequent to December 31, 1999, the Company has drawn the remaining $7.5
million under the Working Capital Facility and the Company issued warrants to
purchase 191,988 shares of the Company's common stock. The aggregate value
ascribed to the warrants was approximately $1,242,000.

8.   Long-term Debt, Bridge, and Other Financings:

Long-Term Debt

     Long-term debt as of December 31 were as follows:
<TABLE>
<CAPTION>
                                                                       1998             1997 
                                                                  -------------    -------------
<S>                                                               <C>              <C>
Senior Notes, with 14% semi-annual interest, due 2007 .........   $ 135,000,000    $ 135,000,000
Discount on Senior Notes ......................................     (27,536,362)     (28,672,995)
Purchase Money Facility .......................................      10,000,000
Equipment financing note, payable in monthly installments
  of $92,694 including interest at 17.26%, and
  final payment of $642,305 due April 29, 1998 ................                          877,854
Note payable in quarterly installments of principal of $187,500
  plus interest at prime plus 2% (10.5% at December 31, 1997)
  through September 1998 ......................................                          562,500
Other .........................................................         907,607          532,000
                                                                  -------------    -------------
                                                                    118,371,245      108,299,359
Less current portion ..........................................        (525,313)      (1,476,256)
                                                                  -------------    -------------
                                                                  $ 117,845,932    $ 106,823,103
</TABLE>

                                      F-12
<PAGE>
 
     The aggregate amount of the principal payments for long-term debt as of
December 31, 1998 follows:

     Year ended December 31:

         1999..............................................     $    525,313
         2000..............................................          335,193
         2001..............................................           47,101
         2002..............................................
         2003..............................................          250,000
         Thereafter........................................      144,750,000
         Discount on Senior Notes .........................      (27,536,362)
                                                                ------------
                                                                $118,371,245
                                                                ============
Senior Notes

     In February 1997, the Company received $135 million of gross proceeds from
a public offering of $135 million of 14% Senior Notes (the "Senior Notes") and
warrants to purchase an aggregate of 2,731,725 shares of the Company's common
stock for $0.01 per share. Approximately $51 million of such proceeds were used
to purchase a portfolio of U.S. Treasury securities that will provide for
interest payments on the Senior Notes through February 2000. The aggregate value
ascribed to the warrants of approximately $29.7 million, was reflected as both a
debt discount and an increase in additional paid-in capital. The debt discount
is accounted for as a component of interest expense using the effective interest
rate method. The Senior Notes are considered to have "significant original issue
discount" under Federal tax rules and the Company is not able to deduct the
accretion of the debt discount for Federal income tax purposes.

     The Senior Notes are unsecured senior obligations of the Company, due
February 2007, with interest payable on February 15 and August 15 of each year
and are redeemable at the Company's option beginning in February 2002 at
redemption prices declining to par. The Senior Notes were issued under an
indenture which contains covenants limiting the Company's ability to incur
additional debt, pay dividends or make other distributions, incur liens, merge
or sell assets, or enter into certain transactions with related parties, among
other restrictions.

Purchase Money Facility

     In September 1998, the Company and Lucent entered into a purchase money
credit facility (the "Purchase Money Facility") setting forth the terms and
conditions under which Lucent will provide purchase money financing in an
aggregate amount of up to $200 million, to be used to finance the purchase of
the Company's data network from Lucent. Under the Purchase Money Facility,
Lucent made $10 million in initial purchase money loans (the "Initial Purchase
Money Loans") immediately available to ART. As of December 31, 1998, the Company
has drawn the full $10 million of the Initial Purchase Money Loans and has also
incurred additional other equipment and construction related costs of
approximately $1.2 million due to Lucent, which is included in accounts payable.
Interest initially accrues at an annual rate of LIBOR plus 5% (10.7% at December
31, 1998) and increases 0.5% each month beginning January 1999. Payments under
the Initial Purchase Money Loans, plus accrued interest, will be due in
installments beginning 2003 through 2009. Subject to other conditions, upon
ART's raising at least $50 million of certain debt or equity capital and
repayment and termination of the Working Capital Facility, Lucent will make
available purchase money loans equal to 200% of the aggregate capital raised,
not to exceed $200 million, including the Initial Purchase Money Loans.

Equipment Financing Note

     The equipment financing note was repaid in full during 1998 and was
previously collateralized by a portion of the Company's wireless transmission
equipment and a $1 million certificate of deposit, which was also repaid in
1998. In connection with the issuance of the equipment financing note, certain
shareholders of the Company guaranteed 

                                      F-13
<PAGE>
 
payment of the note in exchange for warrants to purchase 118,181 shares of the
Company's common stock for $17.19 per share and $225,000 in fees. In November
1996, the shareholders were released from the guarantee.

Bridge Financings

     During 1996, the Company issued in the aggregate $12 million of bridge
financings in three private placements. Of these notes, approximately $8.1
million principal amount was issued to certain shareholders of the Company and
CommcoCCC. Warrants to purchase in the aggregate 603,637 shares of the Company's
common stock at a price per share ranging from $15.00 to $17.19, were issued in
connection with these bridge financings. In November 1996, the Company repaid
these bridge financings with the proceeds from the initial public offering of
the Company's common stock. The early repayment of these bridge financings
resulted in an extraordinary loss arising from the write-off of the unamortized
note discounts and the related deferred financing costs.

CIBC Financing Commitment

     In November 1996, in connection with Company's initial public offering of
common stock, the Company entered into agreements with certain lenders which
provided for the issuance of up to $50 million of senior collateralized notes
(the "CIBC Financing Commitment"), at any time at the Company's option through
February 1997. In connection with the CIBC Financing Commitment, the Company
paid placement and commitment fees and other expenses of approximately $1.9
million and issued warrants to purchase 300,258 shares of common stock (the
"CIBC Warrants") at an exercise price of $0.01 per share. No amounts were
borrowed under the CIBC Financing Commitment. The CIBC Financing Commitment was
terminated in connection with the issuance of the Senior Notes.

9.       Commitments and Contingencies:

Purchase Commitments

     In July 1998, the Company and Lucent entered into a definitive purchase
agreement (the "Lucent Purchase Agreement") which amended and restated the
Company's purchase agreement with Lucent entered into in April 1998, under which
Lucent will design, engineer and construct the Company's wireless broadband data
networks. The Company's purchase commitment under the Lucent Purchase Agreement
is initially $240 million upon the availability of the $200 million Purchase
Money Facility from Lucent. The Company's commitment is subject to various other
terms and conditions, including the availability of additional financing on
terms that are acceptable to the Company. Subsequent to December 31, 1998, the
Company issued a purchase order for certain wireless network equipment in the
amount of approximately $5 million under Lucent Purchase Agreement. The cost of
the wireless network equipment was based on a volume discount price.

Operating Leases

     The Company has entered into operating leases for office space and antenna
sites which expire between 1999 and 2017. Lease expense amounted to
approximately $2,523,836, $1,753,962 and $618,000 for 1998, 1997 and 1996,
respectively. Future annual minimum lease payments as of December 31, 1998 are
as follows:

       1999 .......................................    $  2,714,843
       2000 .......................................       2,259,412
       2001 .......................................       2,082,947
       2002........................................       1,567,541
       2003........................................         897,854
       Thereafter .................................       6,170,797
                                                      -------------
                                                        $15,693,394
                                                      =============

                                      F-14
<PAGE>
 
Employment Agreements

     The Company has entered into various employment agreements with certain
executives that provide for annual base salaries and cash bonuses based on
achievement of specific performance goals.

Contingencies

     The Company is party to certain claims and makes routine filings with the
FCC and state regulatory authorities. Management believes that the resolution of
any such claims or matters arising from such filings, if any, will not have a
material adverse impact on the consolidated financial position, results of
operations or cash flows of the Company.

10.      Capital Stock:

Preferred Stock

     The Company is authorized to issue 10 million shares of $0.001 par value
serial preferred stock. Each series of the preferred stock issued is a separate
class and, as a class, has a liquidation preference equal to the aggregate
purchase price paid for such class.

     The historical share information regarding the Company's preferred stock
activity follows:
<TABLE>
<CAPTION>
                                                                                 Serial  Preferred Stock
                                                                  ----------------------------------------------------------------
                                                                  Series A  Series B Series C Series D  Series E  Series F  Total
                                                                  --------  -------- -------- --------  --------  --------  -----
<S>                                                               <C>       <C>      <C>      <C>       <C>       <C>       <C>
Balance December 31, 1995 ....................................    334,943    86,507    5,402   61,640                      488,492
Issuance of serial preferred stock for cash ..................                                          232,826   48,893   281,719
Shares issued under anti-dilution provisions .................    120,607    28,172    1,961                               150,740
                                                                  --------  -------- -------- --------  --------  --------  -----
                                                                  455,550   114,679    7,363   61,640   232,826   48,893   920,951

Serial preferred stock converted to common stock in connection
   with initial public offering of common stock ..............   (455,550) (114,679)  (7,363) (61,640) (232,826) (48,893) (920,951)
Balance at December 31, 1996 .................................         --        --       --       --        --       --        --
                                                                  ========  ======== ======== ========  ========  ========  =====
</TABLE>
Common Stock

     Approximately 1.2 million shares of the Company's common stock, previously
held by certain individual shareholders in escrow ("Escrow Shares") as part of
the Landover funding commitment, were released upon attainment of certain
objectives in February 1996 as part of a reorganization of the Company. The
Escrow Shares had an estimated fair value of $6.8 million and were recorded as
compensation expense and as an increase in additional paid-in capital.

     In February 1996, the Company sold 48,893 shares of Series F preferred
stock for an aggregate purchase price of $2.5 million and the Company entered
into a strategic distribution agreement and, as partial consideration, granted
warrants to the preferred stockholder to purchase up to 318,959 shares of common
stock at an exercise price of $0.01 per share. The Company recorded the
estimated value of the strategic distribution agreement of $1.1 million as
marketing expense and additional paid-in capital in 1996. The Company incurred
fees of $150,000 in connection with this transaction. In December 1996, the
preferred stockholder exercised its warrants and was issued 318,374 shares of
common stock by the Company.

     The financial statements and footnotes reflect the effects of various
common stock splits and reverse stock splits, including a 1 for 2.75 reverse
split of the Company's common stock effected in October 1996. All references to
the number of shares, per share amounts and par value amounts have been restated
for all stock splits and reverse stock splits. Such stock splits and reverse
stock splits have no impact on the total amount of stockholders' equity
(deficit).

                                      F-15
<PAGE>
 
     During November 1996, the Company completed an initial public offering of
2,300,500 shares of common stock, raising approximately $34.5 million of gross
proceeds. The Company incurred approximately $6.1 million of expenses in
connection with this offering.

Warrants to Purchase Common Stock

     The Company has issued warrants to purchase common stock in connection with
its financing activities during 1998, 1997 and 1996. The following summarizes
the warrants outstanding related to these financing activities at December 31,
1998:
<TABLE>
<CAPTION>
                                                                                      Exercise        Period of
                                                                       Number of      Price per       Exercise
                                                                        Shares          Share          Through
                                                                       ---------      ---------       --------- 
       <S>                                                            <C>             <C>             <C> 
         Equipment financing warrants ............................     118,181          $17.19          2001
         Bridge financing warrants ...............................     400,000          $17.19          2001
         Bridge financing warrants ...............................     203,637          $15.00          2001
         CIBC Warrants............................................      66,217         $  0.01          2001
         Senior Note Warrants.....................................     749,451         $  0.01          2007
         Lucent Warrants..........................................     277,892         $  0.01          2008
         Lucent Warrants..........................................     447,972         $  3.33          2008
</TABLE>
The warrants contain certain anti-dilution provisions.

  Stock Compensation

     Pursuant to the Restated Equity Incentive Plan (the "Plan"), the Company
may grant incentive and non-qualified options and other equity incentives with
respect to up to 4 million shares to employees and certain other persons or
entities.

     Pursuant to the 1997 Equity Incentive Plan for Non-Employee Directors, non-
employee directors are given annual automatic grants of stock options and may
annually elect to take fees in common stock to be issued covering up to an
aggregate of 500,000 shares.

     The Company applies the accounting provisions of Accounting Principles
Board Opinion No. 25, "Accounting for Stock Issued to Employees," and related
interpretations for its stock-based plans. Accordingly, compensation costs for
employee stock options is measured as the excess, if any, of the fair value of
the Company's stock at the measurement date over the amount an employee must pay
to acquire the stock. Deferred compensation costs charged to operations was
$678,743, $449,313 and $850,663 in 1998, 1997 and 1996, respectively.

     In July 1997, the Company canceled and reissued certain stock options
previously granted to employees under the Company's equity incentive plan to
have exercise prices equal to the then current fair market value of $7.88 per
share of common stock.

     In October 1998, the Company authorized the cancellation and reissuance, at
the election of the recipients, of certain other stock options previously
granted to employees under the Company's equity incentive plan. Approximately
2,099,000 stock options were canceled and reissued. Of these stock options, 50%
were issued with an exercise price equal to the then current market value of
$2.19 per share of common stock. The exercise price of the remaining stock
options were based on the current fair market value upon the occurrence of
certain future events. In February 1999, the exercise prices of the remaining
options were established at the then current fair market value of $8.50 per
share of common stock.

                                      F-16
<PAGE>
 
         A summary of the stock option transactions follows:
<TABLE>
<CAPTION>
                                                                                             Weighted Average
                                                                              Shares          Exercise Price
                                                                              ------         ----------------
        <S>                                                                  <C>             <C>
         Options outstanding, December 31, 1995........................      382,630              $   2.28
              Options granted..........................................      461,112                 16.07
              Options canceled ........................................      (16,363)                12.25

         Options outstanding, December 31, 1996........................      827,379                  9.95
              Options granted..........................................    2,320,263                 10.23
              Options exercised........................................     (286,100)                 1.74
              Options canceled.........................................     (564,210                 15.87
                                                                           ---------

         Options outstanding, December 31, 1997........................    2,297,332                  9.82
              Options granted..........................................    3,381,625                  6.45
              Options exercised........................................      (15,718)                 5.98
              Options canceled.........................................   (2,656,800)                 9.45
                                                                         -----------
         Options outstanding December 31, 1998.........................    3,006,439                  6.15
                                                                         ===========
</TABLE>

     The Company has adopted the disclosure provisions of Statement of Financial
Accounting Standards No. 123, "Accounting for Stock-Based Compensation" ("SFAS
No. 123"). Had the Company elected to recognize compensation costs as provided
for by SFAS No. 123, the Company's net loss and per share amounts on a pro forma
basis for the years ended December 31 would have been as follows:
<TABLE>
<CAPTION>
                                                                          1998              1997               1996
                                                                        Pro Forma         Pro Forma          Pro Forma
                                                                        ---------         ---------          ---------
        <S>                                                          <C>              <C>                  <C>
         Loss before extraordinary item ..........................   $(51,650,666)    $(63,848,637)         $(29,410,915)
         Extraordinary item ......................................                                            (1,339,996)
                                                                     ------------     ------------          ------------
         Net loss ................................................   $(51,650,666)    $(63,848,637)         $(30,750,911)

         Basic and diluted loss per share
           before extraordinary item .............................   $      (2.08)    $      (3.35)         $      (3.81)
         Basic and diluted extraordinary loss per share ..........                                                 (0.17)
                                                                     ------------     ------------          ------------
         Basic and diluted net loss per share ....................   $      (2.08)    $      (3.35)         $      (3.98)
                                                                     ============     ============          ============
</TABLE>
The weighted average fair value and exercise price of options granted during the
years ended December 31, were as follows:
<TABLE>
<CAPTION>
                                                                                  1998         1997        1996
                                                                                  ----         ----        ----
    <S>                                                                          <C>          <C>         <C> 
     The weighted average fair values of options granted with exercise
         prices equal to the market price of stock at the date of grant......     $3.84        $5.78       $ 6.59

     The weighted average exercise price options granted with exercise
         prices equal to the market price of the stock at the date of grant..      6.05         8.69       $14.60
</TABLE>

                                      F-17
<PAGE>
 
<TABLE>
<CAPTION>
                                                                                  1998         1997        1996
                                                                                  ----         ----        ----
    <S>                                                                          <C>          <C>         <C> 
     The weighted average fair values of options granted with exercise
         prices greater than the market price of the stock at the date of grant   0.98         4.80         7.04

     The weighted average exercise price of options granted with exercise
         prices greater than the market price of the stock at the date of grant   9.89        12.89        16.60

     The weighted average fair values of options granted with exercise prices
         less than the market price of the stock at the date of grant........     8.80           --           --

     The weighted average exercise price of options granted with exercise
         prices less than the market price of the stock at the date of grant.     8.75           --           --
</TABLE>

     The assumptions applied in these valuations for periods prior to the
Company becoming a public entity were (i) use of the minimum value method, (ii)
risk free interest rates ranging from 6.1% to 6.5%, (iii) assumed expected lives
of 3 to 5 years, and (iv) no expected dividends. The assumptions applied for
periods subsequent to the Company becoming a public entity were (i) use of the
Black-Scholes option pricing model, (ii) risk free interest rates ranging from
4.6% to 6.0%, (iii) expected volatility rates ranging from approximately 60% to
approximately 85%, (iv) assumed expected lives of 3 to 5 years, and (v) no
expected dividends.

     The following table summarizes information about fixed-price options
outstanding at December 31, 1998 as follows:
<TABLE>
<CAPTION>
                                                 Weighted-
                                 Number           Average          Weighted-         Number           Weighted-
                               Outstanding       Remaining          Average        Exercisable         Average
     Exercise Price            at 12/31/98   Contractual Life   Exercise Price     at 12/31/98     Exercise Price
     --------------            -----------   ----------------   --------------     -----------     --------------
    <S>                        <C>           <C>                 <C>               <C>             <C>
     $1.62 to 4.94...........  1,244,064          9.41               $ 2.29            36,523           $ 3.14
     $6.00 to 8.75...........  1,409,725          8.79               $ 8.29           139,483           $ 7.98
     $9.88 to 12.75..........    342,250          8.63               $11.10            46,287           $10.70
     $14.63 to 15.00.........     10,400          7.94               $14.91             6,069           $14.95
                             -----------          ----               ------             -----           ------

     $1.62 to 15.00..........  3,006,439          9.02               $ 6.15           228,362           $ 7.94
</TABLE>
     During 1997, the Company entered into an employment agreement with its
Chief Executive Officer that provides for, among other things, the issuance of
100,000 shares of common stock deliverable in 2001 that has been reflected as a
non-cash compensation charge of $887,500 in 1997 and the issuance of 100,000
shares of common stock in exchange for a recourse note of $887,500 with interest
at the minimum applicable federal rate due 2001.

     During 1998, the Company entered into agreements with two of its officers
to issue an aggregate 85,000 shares of common stock deliverable in 2001 that has
been reflected as a non-cash compensation charge of approximately $657,500.

11.      Related Party Transactions:

     In 1996, the Company entered into various management consulting agreements
with Landover. Fees paid to Landover under the agreements totaled approximately
$830,000 in 1996. The agreements with Landover terminated in November 1996.
Additionally, the Company paid Landover approximately $390,000 for expenses in
connection with its funding commitment in 1996.

     The Company has paid legal fees to a law firm in which a principal of the
law firm was also a former officer of the Company. Total fees paid to such law
firm were approximately $666,695 and $520,000 in 1997 and 1996, respectively.

                                      F-18
<PAGE>
 
     During 1996, the Company funded approximately $400,000 of research and
development related to development of wireless transmission equipment with an
entity, of which a former executive of the Company was a shareholder and
director.

12.      Fair Values of Financial Instruments:

     The carrying amounts and the estimated fair values of the Company's
financial instruments at December 31 were as follows:
<TABLE>
<CAPTION>
                                                                1998                         1997 
                                                   ----------------------------------------------------------
                                                      Carrying           Fair        Carrying         Fair
                                                       Amount            Value        Amount          Value
                                                       ------            -----        ------          -----
<S>                                               <C>               <C>            <C>              <C>
         Cash and cash equivalents ............    $11,864,218       $11,864,218     $7,135,427       $7,135,427
         Restricted cash.......................         32,060            32,060      1,032,060        1,032,060
         Short-term investments................                                      18,210,220       18,210,220
         Pledged securities....................     27,358,832        27,585,981     44,359,915       44,230,640
         Senior Notes..........................    107,463,638        87,855,469    106,327,005      129,600,000
         Note payable..........................                                         562,500          562,500
         Equipment financing note..............                                         877,854          877,854
         Working Capital Facility..............     16,229,121        16,602,472
         Purchase Money Facility...............     10,000,000        10,000,000
         Other long-term debt..................        907,607           907,607        532,000          532,000
</TABLE>
     Cash, cash equivalents, restricted cash and short-term investments: The
carrying amount reported in the balance sheet approximates fair value. Pledged
securities: the fair values are based on published market values for the
respective investment instruments. Senior Notes: the fair value is based upon
published market value. Note payable, equipment financing note, Working Capital
Facility, Purchase Money Facility and other debt: The fair values are based upon
interest rates currently available to the Company for issuance of similar debt
with similar terms and maturities.

13.      Supplemental Cash Flow Information:

     Supplemental disclosure of cash flow information are summarized below for
the years ended December 31:
<TABLE>
<CAPTION>
                                                                              1998          1997          1996  
                                                                            --------      --------      --------
<S>                                                                      <C>            <C>           <C>
Non-cash financing and investing activities:
     Additions to property and equipment .........................       $10,818,140    $2,181,684    $9,548,102
     Value ascribed to warrants...................................         3,282,351    29,707,509     2,115,388
     Issuance of shares for licenses  ............................        48,347,798    87,750,000
     Accrued deferred financing costs ............................                                       300,405
     Exchange of notes for serial preferred stock,
       net of deferred financing costs ...........................                                     4,673,186
     Termination of software license agreement ...................                       1,774,087
     Common stock issuable in exchange for note receivable........                         887,500
Interest paid.....................................................        19,312,343    10,368,374       926,821
</TABLE>

                                      F-19
<PAGE>
 
ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE

  None.

                                   PART III

ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

         Information relating to the executive officers of the Company is
included in Item 4A of Part I of this Form 10-K.

         Information relating to the directors of the Company is incorporated
herein by reference to the information included under "Election of Directors"
and "Certain Transactions" in the Company's definitive Proxy Statement to be
filed with the Commission in connection with the Company's 1999 Annual Meeting
of Stockholders (the "Proxy Statement").

ITEM 11.  EXECUTIVE COMPENSATION

         The information set forth under "Compensation" in the Proxy Statement
is incorporated herein by reference.

ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

         The information set forth under "Common Stock Ownership" in the Proxy
Statement is incorporated herein by reference.

         For the sole purpose of calculating the aggregate market value of
voting stock held by non-affiliates of the Company as set forth on the cover
page, it was assumed that only directors, executive officers and greater than
five percent stockholders as of the calculation date constituted affiliates; no
acknowledgment by such persons of affiliate status is implied.

ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

         The information set forth under "Certain Transactions" in the Proxy
Statement is incorporated herein by reference.

                                    PART IV

ITEM 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

         (a) The following documents are filed as part of this report:

              (1)  Consolidated Financial Statements:

                   Consolidated Balance Sheets as of December 31, 1998 and 1997.
                   Consolidated Statements of Operations for the years ended
                   December 31, 1998, 1997 and 1996. 
                   Consolidated Statements of Stockholders' Equity (Deficit) for
                   the years ended December 31, 1998, 1997 and 1996.
                   Consolidated Statements of Cash Flows for the years ended
                   December 31, 1998, 1997 and 1996.

              (2)  Financial Statement Schedules:

                  None.

                                      -20-
<PAGE>
 
              (3)  Exhibits:

                           The following Exhibits are, as indicated on the
                  Exhibit Index, either filed herewith or have heretofore been
                  filed with the Securities and Exchange Commission and are
                  referred to and incorporated herein by reference to such
                  filings.


    Exhibit No.                           Title

        3.1       Amended and Restated Certificate of Incorporation.
        3.2       Restated and Amended Bylaws of Registrant.
        4.1       Specimen of Common Stock Certificate.
        4.2       Indenture relating to the Company's 14% Senior Notes due 2007.
        4.3       Specimen of Note (included in Exhibit 4.2).
        4.4       Collateral Pledge and Security Agreement relating to the
                  Notes.
        4.5       Form of Warrant Agreement in connection with offering of
                  Notes.
        4.6       Specimen of Warrant Certificate in connection with offering of
                  Notes (included in Exhibit 4.5).
        4.7       Shareholders Rights Agreement.
        4.8       Form of Rights Certificate.
       10.1       Employment Agreement dated October 17, 1997 between the
                  Company and Henry C. Hirsch.
       10.2       Amended and Restated Change of Control Agreement dated
                  February 3, 1999 between Henry C. Hirsch and the Company.
       10.3       Employment Agreement dated February 1, 1998 between William J.
                  Maxwell and the Company. 
       10.4       Amended and Restated Change of Control Agreement dated
                  February 3, 1999 between William J. Maxwell and the Company.
       10.5       Employment Agreement dated February 1, 1998 between George R.
                  Olexa and the Company.
       10.6       Amended and Restated Change of Control Agreement dated
                  February 3, 1999 between George R. Olexa and the Company.
       10.7       Employment Agreement dated August 31, 1998 between Thomas P.
                  Boyan and the Company.
       10.8       Amended and Restated Change of Control Agreement dated
                  February 3, 1999 between Thomas P. Boyan and the Company.
       10.9       Employment Agreement dated October 16, 1998 between Robert S.
                  McCambridge and the Company. 
       10.10      Amended and Restated Change of Control Agreement dated
                  February 3, 1999 between Robert S. McCambridge and the
                  Company.
       10.11      Form of Director Indemnification Agreement.
       10.12      Company's Restated Equity Incentive Plan, as amended.
       10.13      Company's 1997 Equity Incentive Plan for Non-Employee
                  Directors.
       10.14      Company's 1996 Non-Employee Directors Incentive Stock Option
                  Plan.
       10.15      Second Restated and Amended Registration Rights Agreement
                  dated July 3, 1996 with ART Licensing and the stockholders of
                  each of ART Licensing and the Company.
       10.16      Amendment No. 1 to Registration Rights Agreement dated as of
                  October 16, 1996.
       10.17      Form of Indemnity Warrant.
       10.18      Form of Subscription Agreement dated March 8, 1996, including
                  Forms of Bridge Note and Bridge Warrant.
       10.19      Option Agreement dated July 3, 1996 with Commco, L.L.C.
       10.20      Form of September Bridge Warrant.
       10.21      Form of CIBC Warrants.
       10.22      Agreement and Plan of Merger dated as of January 23, 1998,
                  among the Company, DCT Acquisition, Inc., DCT Communications,
                  Inc.
       10.23      Registration Rights Agreement dated August 26, 1999 between
                  the Company and Lucent.  
       10.24      Amended and Restated Purchase Agreement dated July 24, 1998
                  between the Company and Lucent.
       10.25      Purchase Money Credit Agreement dated as of September 17, 1998
                  between the Company and Lucent.
       10.26      Working Capital Credit Agreement date as of September 17, 1998
                  between the Company and Lucent.
       10.27      Form of Warrants issued to Lucent pursuant to the Working
                  Capital Facility.

                                      -21-
<PAGE>
 
       10.28      Asset Purchase Agreement dated as of August 6, 1998 between
                  the Company and ICG Telecom Group, Inc.
       10.29      Asset Purchase Agreement dated as of July 3, 1998 between the
                  Company and Astrolink Communications, Inc.
       10.30      First Amendment to Asset Purchase Agreement dated as of August
                  25, 1998 between the Company and Astrolink Communications,
                  Inc.
       21         Subsidiaries of the Company.
       23         Consent of Independent Accountants.
       27         Financial Data Schedule.
       99         Risk Factors.

           (4)     Reports on Form 8-K

           The Company did not file any reports on Form 8-K during the fourth
quarter of 1998.

                                      -22-
<PAGE>
 
                                  SIGNATURES

         PURSUANT TO THE REQUIREMENTS OF SECTION 13 OR 15(D) OF THE SECURITIES
EXCHANGE ACT OF 1934, THE REGISTRANT HAS DULY CAUSED THIS REPORT TO BE SIGNED ON
ITS BEHALF BY THE UNDERSIGNED, THEREUNTO DULY AUTHORIZED ON THIS 14TH DAY OF
APRIL 1999.

                                             Advanced Radio Telecom Corp.

                                             /s/ Robert S. McCambridge

                                             By: ______________________________
                                                 EXECUTIVE VICE PRESIDENT AND
                                                 CHIEF FINANCIAL OFFICER


         PURSUANT TO THE REQUIREMENTS OF THE SECURITIES AND EXCHANGE ACT OF
1934, THIS REPORT HAS BEEN SIGNED BELOW BY THE FOLLOWING PERSONS ON BEHALF OF
THE REGISTRANT IN THE CAPACITIES AND ON THE DATES INDICATED:

         SIGNATURE                       TITLE                       DATE

/s/ Henry C. Hirsch             Chairman, Chief Executive     April 14, 1999
- ------------------------------- Officer and Director
HENRY C. HIRSCH                

/s/ James Cook                  Director                      April 14, 1999
- ------------------------------- 
JAMES COOK

/s/ Mark C. Demetree            Director                      April 14, 1999
- ------------------------------- 
MARK C. DEMETREE

/s/ Andrew I. Fillat            Director                      April 14, 1999
- ------------------------------- 
ANDREW I. FILLAT

/s/ James B. Murray, Jr.        Director                      April 14, 1999
- ------------------------------- 
JAMES B. MURRAY, JR.

/s/ Alan Z. Senter              Director                      April 14, 1999
- ------------------------------- 
ALAN Z. SENTER

/s/ Thomas Wynne                Director                      April 14, 1999
- ------------------------------- 
THOMAS WYNNE

/s/ Robert S. McCambridge       Executive Vice President,     April 14, 1999
- ------------------------------- Chief Financial Officer
ROBERT S. McCAMBRIDGE           

                                      -23-
<PAGE>
 
                                  EXHIBIT INDEX



Exhibit No.                      Title                                   Page

    3.1       Amended and Restated Certificate of Incorporation.(7)
    3.2       Restated and Amended Bylaws of Registrant.(12)
    4.1       Specimen of Common Stock Certificate.(3)
    4.2       Indenture relating to the Company's 14% Senior Notes
                due 2007.(6)
    4.3       Specimen of Note (included in Exhibit 4.2).(6)
    4.4       Collateral Pledge and Security Agreement relating to the Notes.(6)
    4.5       Form of Warrant Agreement in connection with offering of Notes.(6)
    4.6       Specimen of Warrant Certificate in connection with offering of 
               Notes (included in Exhibit 4.5).(6)
    4.7       Shareholders Rights Agreement.(8)
    4.8       Form of Rights Certificate.(8)
   10.1       Employment Agreement dated October 17, 1997 between the Company
                and Henry C. Hirsch.(9)
   10.2       Amended and Restated Change of Control Agreement dated February 3,
                1999 between Henry C. Hirsch and the Company.
   10.3       Employment Agreement dated February 1, 1998 between William J. 
                Maxwell and the Company.(11)
   10.4       Amended and Restated Change of Control Agreement dated
                February 3, 1999 between William J. Maxwell and the Company.
   10.5       Employment Agreement dated February 1, 1998 between George R. 
                Olexa and the Company.(11)
   10.6       Amended and Restated Change of Control Agreement dated February 3,
                1999 between George R. Olexa and the Company.
   10.7       Employment Agreement dated August 31, 1998 between Thomas P. Boyan
                and the Company.(17)
   10.8       Amended and Restated Change of Control Agreement dated February 3,
                1999 between Thomas P. Boyan and the Company.
   10.9       Employment Agreement dated October 16, 1998 between Robert S.
                McCambridge and the Company.
   10.10      Amended and Restated Change of Control Agreement dated February 3,
                 1999 between Robert S. McCambridge and the Company.
   10.11      Form of Director Indemnification Agreement.(1)
   10.12      Company's Restated Equity Incentive Plan, as amended.(10)
   10.13      Company's 1997 Equity Incentive Plan for Non-Employee Directors.
                 (10)
   10.14      Company's 1996 Non-Employee Directors Incentive Stock Option 
                 Plan.(1)
   10.15      Second Restated and Amended Registration Rights Agreement dated 
                July 3, 1996 with ART Licensing and the stockholders of each 
                of ART Licensing and the Company.(2)
   10.16      Amendment No. 1 to Registration Rights Agreement dated as of 
                October 16, 1996.(5)
   10.17      Form of Indemnity Warrant.(1)
   10.18      Form of Subscription Agreement dated March 8, 1996, including 
                Forms of Bridge Note and Bridge Warrant.(2)
   10.19      Option Agreement dated July 3, 1996 with Commco, L.L.C.(2)
   10.20      Form of September Bridge Warrant.(5)
<PAGE>
 
   10.21      Form of CIBC Warrants.(4)
   10.22      Agreement and Plan of Merger dated as of January 23, 1998,
                among the Company, DCT Acquisition, Inc., DCT Communications,
                Inc.(11)
   10.23      Registration Rights Agreement dated August 26, 1999 between the
                Company and Lucent.(13)
   10.24      Amended and Restated Purchase Agreement dated July 24, 1998 
                between the Company and Lucent.(13)
   10.25      Purchase Money Credit Agreement dated as of September 17, 1998 
                between the Company and Lucent.(13)
   10.26      Working Capital Credit Agreement date as of September 17, 1998 
                between the Company and Lucent.(13)
   10.27      Form of Warrants issued to Lucent pursuant to the Working Capital
                Facility.(13) 
   10.28      Asset Purchase Agreement dated as of August 6, 1998
                between the Company and ICG Telecom Group, Inc.(13)
   10.29      Asset Purchase Agreement dated as of July 3, 1998 between the 
                Company and Astrolink Communications, Inc.(13)
   10.30      First Amendment to Asset Purchase Agreement dated as of August 
                25, 1998 between the Company and Astrolink Communications, Inc.
                (13)
   21         Subsidiaries of the Company.
   23         Consent of Independent Accountants.
   27         Financial Data Schedule.
   99         Risk Factors.

- --------
(1)    Previously filed with the Company's Registration Statement on Form S-1,
       effective November 5, 1996 (SEC Reg. No. 333-04388) and incorporated by
       reference herein.
(2)    Previously filed with Amendment 1 to the Company's Registration Statement
       on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
       incorporated by reference herein.
(3)    Previously filed with Amendment 2 to the Company's Registration Statement
       on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
       incorporated by reference herein.
(4)    Previously filed with Amendment 8 to the Company's Registration Statement
       on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
       incorporated by reference herein.
(5)    Previously filed with the Company's Registration Statement Form S-1,
       effective February 3, 1997 (SEC Reg. No. 333-19295) and incorporated by
       reference herein.
(6)    Previously filed with Amendment 2 to the company's Registration Statement
       on Form S-1, effective February 3, 1997 (SEC Reg. No. 333-19295) and
       incorporated by reference herein.
(7)    Previously filed with the Company's Annual Report on Form 10-K for the
       fiscal year ended December 31, 1996 and incorporated by reference herein.
(8)    Previously filed with the Company's Registration Statement on Form 8-A,
       filed on July 10, 1997 (SEC Reg. No. 000-21091) and incorporated by
       reference herein.
(9)    Previously filed with the Company's Quarterly Report on Form 10-Q, dated
       November 14, 1997 (SEC Reg. No. 000-21091) and incorporated by reference
       herein.
(10)   Previously filed with the Company's Annual Report on Form 10-K for the
       fiscal year ended December 31, 1997 (SEC Reg. No. 000-21091) and
       Incorporated by reference herein.
(11)   Previously filed with the Company's Quarterly Report on Form 10-Q, dated
       May 14, 1998 (SEC Reg. No. 000-21091) and incorporated by reference
       herein.
(12)   Previously filed with the Company's Quarterly Report on Form 10-Q dated
       August 14, 1998 (SEC Reg. No. 000-21091) and incorporated by reference
       herein.
(13)   Previously filed with the Company's Quarterly Report on Form 10-Q, dated
       November 16, 1998 (SEC Reg. No. 21091) and incorporated by reference
       herein.

<PAGE>
 
                                                                    EXHIBIT 10.2

                         ADVANCED RADIO TELECOM CORP.
               Amended and Restated Change of Control Agreement
               ------------------------------------------------

     AGREEMENT, made this 3/rd/ day of February, 1999 by and between Henry C.
Hirsch ("Executive") and ADVANCED RADIO TELECOM CORP. (the "Company");

RECITALS:

    A.    The Board of Directors of the Company (the "Board") recognizes that
the possibility of a change in control may exist and that such possibility, and
the uncertainty and questions which it may raise among management personnel, may
result in the departure or distraction of management personnel to the detriment
of the Company and its stockholders;

    B.    The Board has determined that appropriate steps should be taken to
reinforce and encourage the continued attention and dedication of members of the
Company's management, including Executive, to their duties, to assisting the
Board in assessing proposals with respect to a change in control and to advising
the Board as to the best interests of the Company and its shareholders with
respect to such potential change in control, without distraction and conflict
arising from the possibility of a change in control;

    C.    The Board wishes to induce Executive to remain in the employ of the
Company and to assure him of fair severance should his employment terminate in
specified circumstances following a change of control of the Company.

    NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the parties hereto agree as follows:

    1.    If within 24 months following a Change of Control (as defined in
Exhibit A) (the "Post Change of Control Period") Executive's employment with the
Company is terminated (i) by the Company for any reason (other than for "Cause"
or "Disability" (as defined paragraph 4 below) or as a result of Executive's
death), or (ii) Executive terminates such employment for Good Reason (as defined
in paragraph 4 below):

        (a) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the sum of (i) Executive's annual base salary ("Base Salary") at
            the time of termination through the date of such termination of
            employment to the extent not theretofore paid, (ii) a prorated
            portion of Executive's maximum incentive compensation for the fiscal
            year in which such termination shall occur, calculated by
            multiplying (A) such incentive compensation times (B) a fraction,
            the numerator of which is the number of days in the fiscal year
            through the date of termination of employment, and the 
<PAGE>
 
            denominator of which is 365, (iii) if Executive has not been paid
            incentive compensation with respect to the fiscal year prior to the
            year in which such termination occurs and during which Executive was
            employed by the Company (except where prior to the Change of Control
            the Board had determined that no such incentive compensation was to
            be paid to Executive with respect to such prior year), Executive's
            maximum incentive bonus for such prior fiscal year prorated for the
            period of his employment by the Company if less than a full year
            (provided that if any target incentive compensation under (ii) or
            (iii) was expressed in shares of common stock rather than cash, the
            Company will pay the cash equivalent of such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition), in the case of the Company's common stock as of
            the date prior to the date of the Change of Control), and (iv) any
            accrued and unpaid vacation pay through the date of termination;

        (b) Any stock, stock option or other awards granted to Executive by the
            Company shall immediately vest and, if applicable, become
            exercisable in full, notwithstanding any provision to the contrary,
            and shall remain exercisable, if applicable, until the earlier of
            the fourth anniversary of such termination of employment or the
            latest date on which such grant could have been exercised, any
            restrictions on any restricted stock, deferred stock or other awards
            shall immediately terminate and all such awards shall immediately be
            vested in full, and any certificates for any deferred stock shall be
            delivered to Executive no later than five business days following
            such termination;

        (c) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the greater of (i) an amount equal to Executive's aggregate Base
            Salary and maximum incentive compensation for the period from the
            date of termination through December 31, 2000 determined as if he
            had been employed through December 31, 2000 (but without duplication
            of amounts paid pursuant to Section 1(a) above) or (ii) an amount
            equal to two times:  (A) the amount of Executive's Base Salary at
            the rate in effect immediately prior to the date of termination or
            at the rate in effect immediately prior to the Change of Control,
            whichever is higher, and (B) the amount of Executive's maximum
            incentive compensation for the fiscal year during which the
            termination of employment occurs or the amount of Executive's
            maximum incentive compensation in effect immediately prior to the
            Change of Control, whichever is higher (provided that if any such
            incentive compensation is expressed or was paid in shares of common
            stock rather than cash, the calculation will be based on, and the
            Company will pay the cash equivalent of, such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition) in the case of a share of the Company's common
            stock determined on the date prior to the date of the Change of
            Control;

                                      -2-
<PAGE>
 
        (d) Executive, together with his dependents, will continue following
            such termination of employment to participate fully in the life and
            medical insurance plans maintained or sponsored by the Company
            immediately prior to the Change of Control on the same basis they
            participated prior to the Change in Control until the earlier of (i)
            the second anniversary of such termination or any longer period as
            may be provided by the terms of such plan or (ii) the date Executive
            becomes re-employed with another employer and is eligible to receive
            substantially equivalent life and medical benefits under another
            employer provided plan, provided that if the continued participation
            of Executive and his dependents is not possible under the terms of
            any of such Company plans, the Company shall instead either arrange
            to provide Executive and his dependents with substantially
            equivalent benefits or pay to Executive (within five days of the
            date of termination) an amount equal to the full value thereof in
            cash;

        (e) the Company will promptly reimburse Executive for any and all legal
            fees and expenses (including, without limitation, stenographer fees
            and printing costs) incurred by him as a result of such termination
            of employment, including without limitation all fees and expenses
            incurred to enforce the provisions of this Agreement or contest or
            dispute that the termination of his employment is for Cause or other
            than for Good Reason (regardless of the outcome thereof); and

        (f) if the fair market value of the shares of the Company's common stock
            pledged to secure the promissory note dated October 17, 1997 given
            by Executive to the Company (the "Note") (calculated on the basis of
            the closing price of a share of the Company's common stock on the
            Nasdaq Stock Market on the day preceding the date of termination) is
            less than the outstanding principal plus accrued interest on such
            Note at the date of termination, Executive may no later than 30 days
            after such termination notify the Company that he elects to return
            such stock to the Company in full satisfaction of outstanding
            indebtedness under the Note and all indebtedness outstanding
            thereunder shall as of the date of such notice be forgiven.

     Notwithstanding anything herein to the contrary, (i) to the extent that any
payment or benefit provided for herein is required to be paid or vested on any
earlier date under the terms of any plan, agreement or arrangement, such plan,
agreement or arrangement shall control; and (ii) if the Company terminates
Executive's employment for a reason other than Cause prior to the date upon
which the Change of Control occurs, and Executive reasonably demonstrates that
such termination of employment (x) was at the request of a third party who has
taken steps reasonably calculated to effect a Change of Control or (y) otherwise
arose in connection with or in anticipation of a Change of Control, then for all
purposes of this Agreement, Executive shall be entitled to the benefits provides
in Section 1 above.

     To avert duplication of benefits, if Executive receives any payment of Base
Salary, incentive compensation or severance other than under this Agreement
("Other Termination 

                                      -3-
<PAGE>
 
Payments") upon the termination of his employment with the Company, the amount
of such payments shall be deducted from the amount paid under this Agreement and
the benefits to be provided hereunder shall be provided only to the extent
additional to the benefits to be provided other than under this Agreement;
provided, however, that neither this paragraph nor the provisions of any other
agreement shall be interpreted to reduce the amount payable to Executive below
the amount that would otherwise have been payable under this Agreement if such
Other Termination Payments had not been made.

     2.   Death, Disability, Cause, Other Than For Good Reason


          (a)  If Executive's employment shall terminate during the Post Change
               of Control Period by reason of Executive's death, this Agreement
               shall terminate without further obligations to Executive's legal
               representatives under this Agreement.

          (b)  If Executive's employment is terminated during the Post Change of
               Control Period by reason of Executive's Disability, this
               Agreement shall terminate without further obligations to
               Executive.  For purposes of this Agreement, "Disability" shall
               have the meaning given in the Company's long-term disability plan
               defining the date and conditions for which Executive is entitled
               to receive long-term disability compensation pursuant to such
               long-term disability plan. If the Company determines in good
               faith that the Disability of Executive has occurred during the
               Post Change of Control Period, it may give Executive written
               notice of its intention to terminate Executive's employment.  In
               such event, Executive's employment with the Company shall
               terminate effective on the 30th day after receipt of such notice
               by Executive, provided that, within the 30 days of such receipt,
               Executive shall not have returned to full-time performance of
               Executive's duties.

          (c)  If Executive's employment shall be terminated for Cause (as
               defined in Section 4 below) during the Post Change of Control
               Period, this Agreement shall terminate without further
               obligations to Executive other than the obligation to pay
               Executive (A) his Base Salary through the date of termination and
               (B) Other Benefits, in each case to the extent theretofore
               unpaid.

          (d)  If Executive voluntarily terminates employment during the Post
               Change of Control Period, excluding a termination for Good
               Reason, this Agreement shall terminate without further
               obligations to Executive.

                                      -4-
<PAGE>
 
     3.   "Cause" means only: (a) commission of a felony or gross neglect of
duty by Executive rising to the level of deliberate dereliction, (b) conviction
of a crime involving moral turpitude, or (c) willful failure by Executive in the
performance of his duties to the Company which failure is deliberate on
Executive's part, results in material injury to the Company, and continues for
more than 30 days after written notice given to Executive pursuant to a two-
thirds vote of all of the members of the Board at a meeting called and held for
such purpose (after reasonable notice to Executive) and at which meeting
Executive and his counsel were given an opportunity to be heard, such vote to
set forth in reasonable detail the nature of the failure.  For purposes of this
definition of Cause, no act or omission shall be considered to have been
"willful" unless it was not in good faith and Executive had knowledge at the
time that the act or omission was not in the best interest of the Company.  Any
act or failure to act based on authority given pursuant to a resolution duly
adopted by the Board or based on the advice of counsel of the Company shall be
conclusively presumed to be done, or omitted to be done, by Executive in good
faith and in the best interest of the Company.  Cause shall not include willful
failure due to incapacity resulting from physical or mental illness or any
actual or anticipated failure after Notice of Termination for Good Reason.

     4.   Executive shall be deemed to have voluntarily terminated his
employment for Good Reason if Executive leaves the employ of the Company for any
reason following:

          (a)  The assignment to Executive of any duties inconsistent in any
               respect with Executive's position (including status, offices,
               titles and reporting requirements), authority, duties or
               responsibilities immediately prior to the Change of Control; or
               the diminution or adverse alteration in any material adverse
               respect of such position, authority, duties or responsibilities,
               excluding for this purpose an isolated, insubstantial and
               inadvertent action not taken in bad faith and which is remedied
               by the Company promptly after receipt of notice thereof given by
               Executive;

          (b)  Any reduction in Executive's rate of Base Salary for any fiscal
               year to less than 100% of the rate of Base Salary payable for the
               fiscal year immediately preceding the Change of Control or of the
               Base Salary provided for such fiscal year in any agreement
               between Executive and the Company, or reduction in Executive's
               total cash and stock compensation opportunities, including Base
               Salary and incentives, for any fiscal year to less than 100% of
               the total cash and stock compensation opportunities made
               available to him immediately preceding the Change of Control for
               the then current fiscal year or of the total cash and stock
               compensation opportunities which were to be made available to him
               for the fiscal year pursuant to any agreement between Executive
               and the Company  (for this purpose, such opportunities shall be
               deemed reduced if the objective standards by which Executive's
               incentive compensation measured becomes more stringent, the
               target or maximum amounts of such incentive compensation are
               reduced, or the 

                                      -5-
<PAGE>
 
               amount of such incentive compensation is reduced on a
               discretionary basis from the amount that would be payable solely
               by reference to the objectives); or

          (c)  Failure of the Company to continue in effect any retirement,
               life, medical, dental, disability accidental death or travel
               insurance plan or other benefit plan or practice, in which
               Executive was participating immediately prior to the Change of
               Control unless the Company provides Executive with a plan or
               plans or practices that provide substantially similar benefits,
               or the taking of any action by the Company that would adversely
               affect Executive's participation in or materially reduce
               Executive's benefits under any of such plans or practices or
               deprive Executive of any material fringe benefit enjoyed by
               Executive immediately prior to the Change of Control other than
               an isolated, insubstantial and inadvertent failure not occurring
               in bad faith and which is remedied by the Company promptly after
               receipt of notice thereof given by Executive; or

          (d)  The Company requires Executive to be based at any office or
               location further than 40 miles from the City of Bellevue, or the
               Company requires Executive to travel on Company business to a
               substantially greater extent than required immediately prior to
               the date of the Change of Control; or

          (e)  Any failure by the Company to comply with and satisfy Section 6
               of this Agreement.

     Executive's right to terminate his employment pursuant to this section
shall not be affected by his incapacity due to physical or mental illness.
Executive's continued employment shall not constitute consent to, or a waiver of
rights with respect to, any circumstances constituting Good Reason hereunder.

     5.   In the case of any dispute under this Agreement, Executive may
initiate binding arbitration in Seattle, Washington before the American
Arbitration Association by serving a notice to arbitrate upon the Company or, at
Executive's election, institute judicial proceedings.  The Company shall not
have the right to initiate binding arbitration, and agrees that upon the
initiation of binding arbitration by Executive pursuant to this paragraph 5 the
Company shall cause to be dismissed any judicial proceedings it has brought
against Executive relating to this Agreement.  The Company authorizes Executive
from time to time to retain counsel of his choice to represent Executive in
connection with any and all actions, proceedings, and/or arbitration, whether by
or against the Company or any director, officer, shareholder, or other person
affiliated with the Company, which may affect Executive's rights under this
Agreement.  Company agrees to (i) pay the fees and expenses of such counsel,
(ii) to pay the cost of such arbitration and/or judicial proceeding, and (iii)
pay interest to Executive on all amounts owed to Executive under this Agreement
during any period of time that such amounts are withheld pending arbitration
and/or judicial proceedings.  Such interest will be at the base rate as
announced from time to time by Canadian Imperial Bank of Commerce.

                                      -6-
<PAGE>
 
     In addition, notwithstanding any existing or prior attorney-client
relationship between the Company and counsel retained by Executive, the Company
irrevocably consents to Executive entering into an attorney-client relationship
with such counsel and agrees that a confidential relationship shall exist
between Executive and such counsel.

     6.   If the Company is at any time before or after a Change of Control
merged or consolidated into or with any other corporation or other entity
(whether or not the Company is the surviving entity), or if substantially all of
the assets thereof are transferred to another corporation or other entity, the
provisions of this Agreement will be binding upon and inure to the benefit of
the corporation or other entity resulting from such merger or consolidation or
the acquirer of such assets (the "Successor Entity"), and this paragraph 6 will
apply in the event of any subsequent merger or consolidation or transfer of
assets.  The Company will require any such Successor Entity to assume expressly
and agree to perform this Agreement in the same manner and to the same extent
that the Company would be required to perform if no such transaction had taken
place.  As used in this Agreement, "Company" shall mean the Company as
hereinbefore defined and any Successor Entity which assumes and agrees to
perform this Agreement by operation of law or otherwise.

     In the event of any merger, consolidation, or sale of assets described
above, nothing contained in this Agreement will detract from or otherwise limit
Executive's right to or privilege of participation in any stock option or
purchase plan or any bonus, profit sharing, pension, group insurance,
hospitalization, or other incentive or benefit plan or arrangement which may be
or become applicable to executives of the corporation resulting from such merger
or consolidation or the corporation acquiring such assets of the Company.

     In the event of any merger, consolidation, or sale of assets described
above, references to the Company in this Agreement shall unless the context
suggests otherwise be deemed to include the entity resulting from such merger or
consolidation or the acquiror of such assets of the Company.

     7.   Any termination by the Company for Cause, or by Executive for Good
Reason, shall be communicated by Notice of Termination to the other party hereto
given in accordance with the last paragraph of Section 12 of this Agreement.
For purposes of this Agreement, a "Notice of Termination" means a written notice
that (i) indicates the specific termination provision in this Agreement relied
upon, (ii) to the extent applicable, sets forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of Executive's
employment under the provision so indicated and (iii) if the Date of Termination
(as defined below) is other than the date of receipt of such notice, specifies
the termination date (which date shall be not more than thirty days after the
giving of such notice).  The failure by Executive or the Company to set forth in
the Notice of Termination any fact or circumstance 

                                      -7-
<PAGE>
 
which contributes to a showing of Good Reason or Cause shall not waive any right
of Executive or the Company, respectively, hereunder or preclude Executive or
the Company, respectively, from asserting such fact or circumstance in enforcing
Executive's or the Company's rights hereunder.

     "Date of Termination" means (i) if Executive's employment is terminated by
the Company for Cause, or by Executive for Good Reason, the date of receipt of
the Notice of Termination or any later date specified therein, as the case may
be, (ii) if Executive's employment is terminated by the Company other than for
Cause or Disability, the Date of Termination shall be the date on which the
Company notifies Executive of such termination and (iii) if Executive's
employment is terminated by reason of death or Disability, the Date of
Termination shall be the date of death of Executive or the effective date of the
Disability, as the case may be.

     8.   All payments required to be made by the Company hereunder to Executive
or his dependents, beneficiaries, or estate will be subject to the withholding
of such amounts relating to tax and/or other payroll deductions as may be
required by law.

     In the event that it is determined that any payment or benefit provided by
the Company to or for the benefit of Executive, either under this Agreement or
otherwise, will be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code or any successor provision(s) ("Section 4999"), the
Company will, prior to the date on which any amount of the excise tax must be
paid or withheld, make an additional lump-sum payment (the "Gross-up Payment")
to Executive in an amount sufficient, after giving effect to all federal, state
and other taxes and charges (including interest and penalties, if any) with
respect to the gross-up payment, to make Executive whole for all taxes
(including withholding taxes) and any associated interest and penalties, imposed
under or as a result of Section 4999.

     Determinations under this Section 8 will be made by Coopers & Lybrand
unless Executive has reasonable objections to the use of that firm, in which
case the determinations will be made by a comparable firm chosen by Executive
after consultation with the Company (the firm making the determinations to be
referred to as the "Firm").  The determinations of the Firm will be binding upon
the Company and Executive except as the determinations are established in
resolution (including by settlement) of a controversy with the Internal Revenue
Service to have been incorrect.  All fees and expenses of the Firm will be paid
by the Company.

     If the Internal Revenue Service asserts a claim that, if successful, would
require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service.  The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy.  The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

                                      -8-
<PAGE>
 
     9.   There shall be no requirement on the part of Executive to seek other
employment or otherwise mitigate damages in order to be entitled to the full
amount of any payments and benefits to which Executive is entitled under this
Agreement, and the amount of such payments and benefits shall not be reduced by
any compensation or benefits received by Executive from other employment other
than with respect to certain welfare benefits as provided in the first proviso
to Section 1(d).

     10.  Nothing contained in this Agreement shall be construed as a contract
of employment between Company and Executive, or as a right of Executive to
continue in the employ of Company, or as a limitation of the right of Company to
discharge Executive with or without Cause; provided that Executive shall have
the right to receive upon termination of his employment the payments and
benefits provided in this Agreement and shall not be deemed to have waived any
rights he may have either at law or in equity in respect of such discharge.

     11.  No amendment, change, or modification of this Agreement may be made
except in writing, signed by both parties.  This agreement amends and restates
in its entirety the Change of Control Agreement between the parties, dated
October 17, 1997.

     12.  This Agreement shall terminate on December 31, 2000, provided,
however, that commencing on December 31, 1999 and on each annual anniversary of
such date (each such date hereinafter referred to as a "Renewal Date"), unless
previously terminated, the term of this Agreement shall be automatically
extended so as to terminate three years from such Renewal Date, unless at least
sixty days prior to the Renewal Date the Company shall give notice to Executive
that the term of this Agreement shall not be so extended.  This Agreement shall
not apply to a Change of Control which takes place after the termination of this
Agreement.
 
     The provisions of this Agreement shall be binding upon and shall inure to
the benefit of Executive, his executors, administrators, legal representatives
and assigns, and the Company and its successors.

     The validity, interpretation, and effect of this Agreement shall be
governed by the laws of the State of Washington.  Any ambiguities in this
Agreement shall be construed in favor of Executive.

     The invalidity or unenforceability of any provisions of this Agreement
shall not affect the validity or enforceability of any other provision of this
Agreement, which shall remain in full force and effect.

     The Company shall have no right of set-off or counterclaims, in respect of
any claim, debt, or obligation, against any payments to Executive, his
dependents, beneficiaries, or estate provided for in this Agreement.

                                      -9-
<PAGE>
 
     No right or interest to or in any payments shall be assignable by
Executive; provided, however, that this provision shall not preclude him from
           --------                                                          
designating one or more beneficiaries to receive any amount that may be payable
after his death and shall not preclude the legal representative of his estate
from assigning any right hereunder to the person or persons entitled thereto
under his will or, in the case of intestacy, to the person or persons entitled
thereto under the laws of intestacy applicable to his estate.  The term
"beneficiaries" as used in this Agreement shall mean a beneficiary or
beneficiaries so designated to receive any such amount, or if no beneficiary has
been so designated, the legal representative of Executive's estate.

     No right, benefit, or interest hereunder, shall be subject to anticipation,
alienation, sale, assignment, encumbrance, charge, pledge, hypothecation or set-
off in respect of any claim, debt or obligation, or to execution, attachment,
levy or similar process, or assignment by operation of law. Any attempt,
voluntary or involuntary, to effect any action specified in the immediately
preceding sentence shall, to the full extent permitted by law, be null, void,
and of no effect.

     All notices and other communications hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

       If to Executive:  Henry C. Hirsch
       ---------------   1220 Second Ave. N. 
                         Seattle, WA  98109   


       If to the Company:  Advanced Radio Telecom Corp.
       -----------------   500 108th Avenue, N.E.    
                           Suite 2600                
                           Bellevue, WA 98004        
                           Attention: General Counsel 

or to such other address as either party shall have furnished to the other in
writing in accordance herewith.  Notice and communications shall be effective
when actually received by the addressee.

                                      -10-
<PAGE>
 
     IN WITNESS WHEREOF, the Company and Executive have each caused this
Agreement to be duly executed and delivered as of the date set forth above.

                                 ADVANCED RADIO TELECOM CORP.


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



                                 ---------------------------------
                                 Henry C. Hirsch

                                      -11-
<PAGE>
 
                                 EXHIBIT A

       Change of Control.  For the purposes of this Agreement, a "Change of
       -----------------                                                   
Control" shall mean:

          (a)  The acquisition by any person, corporation, partnership, limited
               liability company or other entity (a "Person", which term shall
               include a group within the meaning of section 13(d) of the
               Securities Exchange Act of 1934 (the "Exchange Act")) of ultimate
               beneficial ownership (within the meaning of Rule 13d-3
               promulgated under the Exchange Act), directly or indirectly of
               30% or more of either (i) the then outstanding shares of common
               stock of the Company (the "Outstanding Company Common Stock") or
               (ii) the combined voting power of the then outstanding voting
               securities of the Company entitled to vote generally in the
               election of directors (the "Outstanding Company Voting
               Securities"); provided, however, that for purposes of this
               subsection (a), the following acquisitions shall not constitute a
               Change of Control:  (i) any such acquisition directly from the
               Company, except for acquisition of securities upon conversion of
               other securities of the Company (ii) any such acquisition by the
               Company, (iii) any such acquisition by any employee benefit plan
               (or related trust) sponsored or maintained by the Company or any
               corporation controlled by the Company or (iv) any such
               acquisition by any corporation pursuant to a transaction which
               complies with clauses (i), (ii) and (iii) of subsection (c) of
               this Exhibit A; or

          (b)  Individuals who, as of the date hereof, constitute the Board (the
               "Incumbent Board") cease for any reason to constitute at least a
               majority of the Board; provided, however, that any individual
               becoming a director subsequent to the date hereof whose election,
               or nomination for election, by the Company's shareholders, was
               approved by a vote of at least a majority of the directors then
               comprising the Incumbent Board shall be considered as though such
               individual were a member of the Incumbent Board, but excluding,
               for this purpose, any such individual whose initial assumption of
               office occurs as a result of an actual or threatened election
               contest with respect to the election or removal of directors or
               other actual or threatened solicitation of proxies or consents by
               or on behalf of a Person other than the Board; or

          (c)  Consummation of a reorganization, merger or consolidation or sale
               or other disposition of all or substantially all of the assets of
               the Company in one or a series of transactions (a "Business
               Combination"), in each case, unless, following such Business
               Combination, (i) all or substantially all of the individuals and
               entities who were the beneficial owners, respectively, of the

                                      -12-
<PAGE>
 
               Outstanding Company Common Stock and Outstanding Company Voting
               Securities immediately prior to such Business Combination
               beneficially own, directly or indirectly, immediately following
               such Business Combination more than 50% of, respectively, the
               outstanding shares of common stock and the combined voting power
               of the then outstanding voting securities entitled to vote
               generally in the election of directors, as the case may be, of
               the corporation resulting from such Business Combination
               (including, without limitation, a corporation which as a result
               of such transaction owns the Company or all or substantially all
               of the Company's assets either directly or through one or more
               subsidiaries) in substantially the same proportions as their
               ownership, immediately prior to such Business Combination of the
               Outstanding Company Common Stock and outstanding Company Voting
               Securities, as the case may be, (ii) no Person (excluding any
               corporation resulting from such Business Combination or any
               employee benefit plan (or related trust) of the Company or such
               corporation resulting from such Business Combination) ultimately
               beneficially owns, directly or indirectly, 30% or more of,
               respectively, the then outstanding shares of common stock of the
               corporation resulting from such Business Combination or the
               combined voting power of the then outstanding voting securities
               of such corporation except to the extent that such ownership
               existed prior to the Business Combination and (iii) at least a
               majority of the members of the board of directors of the
               corporation resulting from such Business Combination were members
               of the Incumbent Board at the time of the execution of the
               initial agreement, or of the action of the Board, providing for
               such Business Combination; or

          (d)  Approval by the shareholders of the Company of a complete
               liquidation or dissolution of the Company.

                                      -13-

<PAGE>
 
                                                                    EXHIBIT 10.4

                         ADVANCED RADIO TELECOM CORP.
               Amended and Restated Change of Control Agreement
               ------------------------------------------------

     AGREEMENT, made this 3/rd/ day of February, 1999 by and between William J.
Maxwell ("Executive") and ADVANCED RADIO TELECOM CORP. (the "Company");

RECITALS:

    A.    The Board of Directors of the Company (the "Board") recognizes that
the possibility of a change in control may exist and that such possibility, and
the uncertainty and questions which it may raise among management personnel, may
result in the departure or distraction of management personnel to the detriment
of the Company and its stockholders;

    B.    The Board has determined that appropriate steps should be taken to
reinforce and encourage the continued attention and dedication of members of the
Company's management, including Executive, to their duties, to assisting the
Board in assessing proposals with respect to a change in control and to advising
the Board as to the best interests of the Company and its shareholders with
respect to such potential change in control, without distraction and conflict
arising from the possibility of a change in control;

    C.    The Board wishes to induce Executive to remain in the employ of the
Company and to assure him of fair severance should his employment terminate in
specified circumstances following a change of control of the Company.

    NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the parties hereto agree as follows:

    1.    If within 24 months following a Change of Control (as defined in
Exhibit A) (the "Post Change of Control Period") Executive's employment with the
Company is terminated (i) by the Company for any reason (other than for "Cause"
or "Disability" (as defined paragraph 4 below) or as a result of Executive's
death), or (ii) Executive terminates such employment for Good Reason (as defined
in paragraph 4 below):

        (a) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the sum of (i) Executive's annual base salary ("Base Salary") at
            the time of termination through the date of such termination of
            employment to the extent not theretofore paid, (ii) a prorated
            portion of Executive's maximum incentive compensation for the fiscal
            year in which such termination shall occur, calculated by
            multiplying (A) such incentive compensation times (B) a fraction,
            the numerator of which is the number of days in the fiscal year
            through the date of termination of employment, and the 
<PAGE>
 
            denominator of which is 365, (iii) if Executive has not been paid
            incentive compensation with respect to the fiscal year prior to the
            year in which such termination occurs and during which Executive was
            employed by the Company (except where prior to the Change of Control
            the Board had determined that no such incentive compensation was to
            be paid to Executive with respect to such prior year), Executive's
            maximum incentive bonus for such prior fiscal year prorated for the
            period of his employment by the Company if less than a full year
            (provided that if any target incentive compensation under (ii) or
            (iii) was expressed in shares of common stock rather than cash, the
            Company will pay the cash equivalent of such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition), in the case of the Company's common stock as of
            the date prior to the date of the Change of Control), and (iv) any
            accrued and unpaid vacation pay through the date of termination; and

        (b) Any stock, stock option or other awards granted to Executive by the
            Company shall immediately vest and, if applicable, become
            exercisable in full, notwithstanding any provision to the contrary,
            and shall remain exercisable, if applicable, until the earlier of
            the fourth anniversary of such termination of employment or the
            latest date on which such grant could have been exercised, any
            restrictions on any restricted stock, deferred stock or other awards
            shall immediately terminate and all such awards shall immediately be
            vested in full, and any certificates for any deferred stock shall be
            delivered to Executive no later than five business days following
            such termination;

        (c) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the greater of (i) an amount equal to Executive's aggregate Base
            Salary and maximum incentive compensation for the period from the
            date of termination through December 31, 2000 determined as if he
            had been employed through December 31, 2000 (but without duplication
            of amounts paid pursuant to Section 1(a) above) or (ii) an amount
            equal to:  (A) the amount of Executive's Base Salary at the rate in
            effect immediately prior to the date of termination or at the rate
            in effect immediately prior to the Change of Control, whichever is
            higher, and (B) the amount of Executive's maximum incentive
            compensation for the fiscal year during which the termination of
            employment occurs or the amount of Executive's maximum incentive
            compensation in effect immediately prior to the Change of Control,
            whichever is higher (provided that if any such incentive
            compensation is expressed or was paid in shares of common stock
            rather than cash, the calculation will be based on, and the Company
            will pay the cash equivalent of, such compensation based on the
            closing price per share as reported in the Wall Street Journal
            (Eastern Edition) in the case of a share of the Company's common
            stock determined on the date prior to the date of the Change of
            Control.

                                      -2-
<PAGE>
 
        (d) Executive, together with his dependents, will continue following
            such termination of employment to participate fully in the life and
            medical insurance plans maintained or sponsored by the Company
            immediately prior to the Change of Control on the same basis they
            participated prior to the Change in Control until the earlier of (i)
            the second anniversary of such termination or any longer period as
            may be provided by the terms of such plan or (ii) the date Executive
            becomes re-employed with another employer and is eligible to receive
            substantially equivalent life and medical benefits under another
            employer provided plan, provided that if the continued participation
            of Executive and his dependents is not possible under the terms of
            any of such Company plans, the Company shall instead either arrange
            to provide Executive and his dependents with substantially
            equivalent benefits or pay to Executive (within five days of the
            date of termination) an amount equal to the full value thereof in
            cash; and

        (e) the Company will promptly reimburse Executive for any and all legal
            fees and expenses (including, without limitation, stenographer fees
            and printing costs) incurred by him as a result of such termination
            of employment, including without limitation all fees and expenses
            incurred to enforce the provisions of this Agreement or contest or
            dispute that the termination of his employment is for Cause or other
            than for Good Reason (regardless of the outcome thereof).

     Notwithstanding anything herein to the contrary, (i) to the extent that any
payment or benefit provided for herein is required to be paid or vested on any
earlier date under the terms of any plan, agreement or arrangement, such plan,
agreement or arrangement shall control; and (ii) if the Company terminates
Executive's employment for a reason other than Cause prior to the date upon
which the Change of Control occurs, and Executive reasonably demonstrates that
such termination of employment (x) was at the request of a third party who has
taken steps reasonably calculated to effect a Change of Control or (y) otherwise
arose in connection with or in anticipation of a Change of Control, then for all
purposes of this Agreement, Executive shall be entitled to the benefits provides
in Section 1 above.

     To avert duplication of benefits, if Executive receives any payment of Base
Salary, incentive compensation or severance other than under this Agreement
("Other Termination Payments") upon the termination of his employment with the
Company, the amount of such payments shall be deducted from the amount paid
under this Agreement and the benefits to be provided hereunder shall be provided
only to the extent additional to the benefits to be provided other than under
this Agreement; provided, however, that neither this paragraph nor the
provisions of any other agreement shall be interpreted to reduce the amount
payable to Executive below the amount that would otherwise have been payable
under this Agreement if such Other Termination Payments had not been made.

                                      -3-
<PAGE>
 
     2.   Death, Disability, Cause, Other Than For Good Reason

          (a)  If Executive's employment shall terminate during the Post Change
               of Control Period by reason of Executive's death, this Agreement
               shall terminate without further obligations to Executive's legal
               representatives under this Agreement.

          (b)  If Executive's employment is terminated during the Post Change of
               Control Period by reason of Executive's Disability, this
               Agreement shall terminate without further obligations to
               Executive.  For purposes of this Agreement, "Disability" shall
               have the meaning given in the Company's long-term disability plan
               defining the date and conditions for which Executive is entitled
               to receive long-term disability compensation pursuant to such
               long-term disability plan. If the Company determines in good
               faith that the Disability of Executive has occurred during the
               Post Change of Control Period, it may give Executive written
               notice of its intention to terminate Executive's employment.  In
               such event, Executive's employment with the Company shall
               terminate effective on the 30th day after receipt of such notice
               by Executive, provided that, within the 30 days of such receipt,
               Executive shall not have returned to full-time performance of
               Executive's duties.

          (c)  If Executive's employment shall be terminated for Cause (as
               defined in Section 4 below) during the Post Change of Control
               Period, this Agreement shall terminate without further
               obligations to Executive other than the obligation to pay
               Executive (A) his Base Salary through the date of termination and
               (B) Other Benefits, in each case to the extent theretofore
               unpaid.

          (d)  If Executive voluntarily terminates employment during the Post
               Change of Control Period, excluding a termination for Good
               Reason, this Agreement shall terminate without further
               obligations to Executive.


     3.   "Cause" means only: (a) commission of a felony or gross neglect of
duty by Executive rising to the level of deliberate dereliction, (b) conviction
of a crime involving moral turpitude, or (c) willful failure by Executive in the
performance of his duties to the Company which failure is deliberate on
Executive's part, results in material injury to the Company, and continues for
more than 30 days after written notice given to Executive pursuant to a two-
thirds vote of all of the members of the Board at a meeting called and held for
such purpose (after reasonable notice to Executive) and at which meeting
Executive and his counsel were given an opportunity to be heard, such vote to
set forth in reasonable detail the nature of the failure.  For purposes of this
definition of Cause, no act or omission shall be considered to have been
"willful" unless it was not in good faith and Executive had knowledge at the
time that the act or omission was not in the best interest of the Company.  Any
act or failure to act based on authority given 

                                      -4-
<PAGE>
 
pursuant to a resolution duly adopted by the Board or based on the advice of
counsel of the Company shall be conclusively presumed to be done, or omitted to
be done, by Executive in good faith and in the best interest of the Company.
Cause shall not include willful failure due to incapacity resulting from
physical or mental illness or any actual or anticipated failure after Notice of
Termination for Good Reason.

     4.   Executive shall be deemed to have voluntarily terminated his
employment for Good Reason if Executive leaves the employ of the Company for any
reason following:

          (a)  The assignment to Executive of any duties inconsistent in any
               respect with Executive's position (including status, offices,
               titles and reporting requirements), authority, duties or
               responsibilities immediately prior to the Change of Control; or
               the diminution or adverse alteration in any material adverse
               respect of such position, authority, duties or responsibilities,
               excluding for this purpose an isolated, insubstantial and
               inadvertent action not taken in bad faith and which is remedied
               by the Company promptly after receipt of notice thereof given by
               Executive;

          (b)  Any reduction in Executive's rate of Base Salary for any fiscal
               year to less than 100% of the rate of Base Salary payable for the
               fiscal year immediately preceding the Change of Control or of the
               Base Salary provided for such fiscal year in any agreement
               between Executive and the Company, or reduction in Executive's
               total cash and stock compensation opportunities, including Base
               Salary and incentives, for any fiscal year to less than 100% of
               the total cash and stock compensation opportunities made
               available to him immediately preceding the Change of Control for
               the then current fiscal year or of the total cash and stock
               compensation opportunities which were to be made available to him
               for the fiscal year pursuant to any agreement between Executive
               and the Company  (for this purpose, such opportunities shall be
               deemed reduced if the objective standards by which Executive's
               incentive compensation measured becomes more stringent, the
               target or maximum amounts of such incentive compensation are
               reduced, or the amount of such incentive compensation is reduced
               on a discretionary basis from the amount that would be payable
               solely by reference to the objectives); or

          (c)  Failure of the Company to continue in effect any retirement,
               life, medical, dental, disability accidental death or travel
               insurance plan or other benefit plan or practice, in which
               Executive was participating immediately prior to the Change of
               Control unless the Company provides Executive with a plan or
               plans or practices that provide substantially similar benefits,
               or the taking of any action by the Company that would adversely
               affect Executive's participation in or materially reduce
               Executive's benefits under any of such 

                                      -5-
<PAGE>
 
               plans or practices or deprive Executive of any material fringe
               benefit enjoyed by Executive immediately prior to the Change of
               Control other than an isolated, insubstantial and inadvertent
               failure not occurring in bad faith and which is remedied by the
               Company promptly after receipt of notice thereof given by
               Executive; or

          (d)  The Company requires Executive to be based at any office or
               location further than 40 miles from the City of Bellevue, or the
               Company requires Executive to travel on Company business to a
               substantially greater extent than required immediately prior to
               the date of the Change of Control; or

          (e)  Any failure by the Company to comply with and satisfy Section 6
               of this Agreement.

     Executive's right to terminate his employment pursuant to this section
shall not be affected by his incapacity due to physical or mental illness.
Executive's continued employment shall not constitute consent to, or a waiver of
rights with respect to, any circumstances constituting Good Reason hereunder.

     5.   In the case of any dispute under this Agreement, Executive may
initiate binding arbitration in Seattle, Washington before the American
Arbitration Association by serving a notice to arbitrate upon the Company or, at
Executive's election, institute judicial proceedings.  The Company shall not
have the right to initiate binding arbitration, and agrees that upon the
initiation of binding arbitration by Executive pursuant to this paragraph 5 the
Company shall cause to be dismissed any judicial proceedings it has brought
against Executive relating to this Agreement.  The Company authorizes Executive
from time to time to retain counsel of his choice to represent Executive in
connection with any and all actions, proceedings, and/or arbitration, whether by
or against the Company or any director, officer, shareholder, or other person
affiliated with the Company, which may affect Executive's rights under this
Agreement.  Company agrees to (i) pay the fees and expenses of such counsel,
(ii) to pay the cost of such arbitration and/or judicial proceeding, and (iii)
pay interest to Executive on all amounts owed to Executive under this Agreement
during any period of time that such amounts are withheld pending arbitration
and/or judicial proceedings.  Such interest will be at the base rate as
announced from time to time by Canadian Imperial Bank of Commerce.

     In addition, notwithstanding any existing or prior attorney-client
relationship between the Company and counsel retained by Executive, the Company
irrevocably consents to Executive entering into an attorney-client relationship
with such counsel and agrees that a confidential relationship shall exist
between Executive and such counsel.

     6.   If the Company is at any time before or after a Change of Control
merged or consolidated into or with any other corporation or other entity
(whether or not the Company is the surviving entity), or if substantially all of
the assets thereof are transferred to another corporation 

                                      -6-
<PAGE>
 
or other entity, the provisions of this Agreement will be binding upon and inure
to the benefit of the corporation or other entity resulting from such merger or
consolidation or the acquirer of such assets (the "Successor Entity"), and this
paragraph 6 will apply in the event of any subsequent merger or consolidation or
transfer of assets. The Company will require any such Successor Entity to assume
expressly and agree to perform this Agreement in the same manner and to the same
extent that the Company would be required to perform if no such transaction had
taken place. As used in this Agreement, "Company" shall mean the Company as
hereinbefore defined and any Successor Entity which assumes and agrees to
perform this Agreement by operation of law or otherwise.

     In the event of any merger, consolidation, or sale of assets described
above, nothing contained in this Agreement will detract from or otherwise limit
Executive's right to or privilege of participation in any stock option or
purchase plan or any bonus, profit sharing, pension, group insurance,
hospitalization, or other incentive or benefit plan or arrangement which may be
or become applicable to executives of the corporation resulting from such merger
or consolidation or the corporation acquiring such assets of the Company.

     In the event of any merger, consolidation, or sale of assets described
above, references to the Company in this Agreement shall unless the context
suggests otherwise be deemed to include the entity resulting from such merger or
consolidation or the acquiror of such assets of the Company.

     7.   Any termination by the Company for Cause, or by Executive for Good
Reason, shall be communicated by Notice of Termination to the other party hereto
given in accordance with the last paragraph of Section 12 of this Agreement.
For purposes of this Agreement, a "Notice of Termination" means a written notice
that (i) indicates the specific termination provision in this Agreement relied
upon, (ii) to the extent applicable, sets forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of Executive's
employment under the provision so indicated and (iii) if the Date of Termination
(as defined below) is other than the date of receipt of such notice, specifies
the termination date (which date shall be not more than thirty days after the
giving of such notice).  The failure by Executive or the Company to set forth in
the Notice of Termination any fact or circumstance which contributes to a
showing of Good Reason or Cause shall not waive any right of Executive or the
Company, respectively, hereunder or preclude Executive or the Company,
respectively, from asserting such fact or circumstance in enforcing Executive's
or the Company's rights hereunder.

     "Date of Termination" means (i) if Executive's employment is terminated by
the Company for Cause, or by Executive for Good Reason, the date of receipt of
the Notice of Termination or any later date specified therein, as the case may
be, (ii) if Executive's employment is terminated by the Company other than for
Cause or Disability, the Date of Termination shall be the date on which the
Company notifies Executive of such termination and (iii) if Executive's
employment is terminated by reason of death or Disability, the Date of
Termination shall be the date of death of Executive or the effective date of the
Disability, as the case may be.

                                      -7-
<PAGE>
 
     8.   All payments required to be made by the Company hereunder to Executive
or his dependents, beneficiaries, or estate will be subject to the withholding
of such amounts relating to tax and/or other payroll deductions as may be
required by law.

     In the event that it is determined that any payment or benefit provided by
the Company to or for the benefit of Executive, either under this Agreement or
otherwise, will be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code or any successor provision(s) ("Section 4999"), the
Company will, prior to the date on which any amount of the excise tax must be
paid or withheld, make an additional lump-sum payment (the "Gross-up Payment")
to Executive in an amount sufficient, after giving effect to all federal, state
and other taxes and charges (including interest and penalties, if any) with
respect to the gross-up payment, to make Executive whole for all taxes
(including withholding taxes) and any associated interest and penalties, imposed
under or as a result of Section 4999.

     Determinations under this Section 8 will be made by Coopers & Lybrand
unless Executive has reasonable objections to the use of that firm, in which
case the determinations will be made by a comparable firm chosen by Executive
after consultation with the Company (the firm making the determinations to be
referred to as the "Firm").  The determinations of the Firm will be binding upon
the Company and Executive except as the determinations are established in
resolution (including by settlement) of a controversy with the Internal Revenue
Service to have been incorrect.  All fees and expenses of the Firm will be paid
by the Company.

     If the Internal Revenue Service asserts a claim that, if successful, would
require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service.  The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy.  The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

     9.   There shall be no requirement on the part of Executive to seek other
employment or otherwise mitigate damages in order to be entitled to the full
amount of any payments and benefits to which Executive is entitled under this
Agreement, and the amount of such payments and benefits shall not be reduced by
any compensation or benefits received by Executive from other employment other
than with respect to certain welfare benefits as provided in the first proviso
to Section 1(d).

                                      -8-
<PAGE>
 
     10.  Nothing contained in this Agreement shall be construed as a contract
of employment between Company and Executive, or as a right of Executive to
continue in the employ of Company, or as a limitation of the right of Company to
discharge Executive with or without Cause; provided that Executive shall have
the right to receive upon termination of his employment the payments and
benefits provided in this Agreement and shall not be deemed to have waived any
rights he may have either at law or in equity in respect of such discharge.

     11.  No amendment, change, or modification of this Agreement may be made
except in writing, signed by both parties.  This agreement amends and restates
in its entirety the Change of Control Agreement between the parties, dated
December 8, 1997.

     12.  This Agreement shall terminate on December 31, 2000, provided,
however, that commencing on December 31, 1999 and on each annual anniversary of
such date (each such date hereinafter referred to as a "Renewal Date"), unless
previously terminated, the term of this Agreement shall be automatically
extended so as to terminate three years from such Renewal Date, unless at least
sixty days prior to the Renewal Date the Company shall give notice to Executive
that the term of this Agreement shall not be so extended.  This Agreement shall
not apply to a Change of Control which takes place after the termination of this
Agreement.
 
     The provisions of this Agreement shall be binding upon and shall inure to
the benefit of Executive, his executors, administrators, legal representatives
and assigns, and the Company and its successors.

     The validity, interpretation, and effect of this Agreement shall be
governed by the laws of the State of Washington.  Any ambiguities in this
Agreement shall be construed in favor of Executive.

     The invalidity or unenforceability of any provisions of this Agreement
shall not affect the validity or enforceability of any other provision of this
Agreement, which shall remain in full force and effect.

     The Company shall have no right of set-off or counterclaims, in respect of
any claim, debt, or obligation, against any payments to Executive, his
dependents, beneficiaries, or estate provided for in this Agreement.

     No right or interest to or in any payments shall be assignable by
Executive; provided, however, that this provision shall not preclude him from
           --------                                                          
designating one or more beneficiaries to receive any amount that may be payable
after his death and shall not preclude the legal representative of his estate
from assigning any right hereunder to the person or persons entitled thereto
under his will or, in the case of intestacy, to the person or persons entitled
thereto under the laws of intestacy applicable to his estate.  The term
"beneficiaries" as used in this Agreement shall mean a beneficiary or
beneficiaries so designated to receive any such amount, or if no beneficiary has
been so designated, the legal representative of Executive's estate.

                                      -9-
<PAGE>
 
     No right, benefit, or interest hereunder, shall be subject to anticipation,
alienation, sale, assignment, encumbrance, charge, pledge, hypothecation or set-
off in respect of any claim, debt or obligation, or to execution, attachment,
levy or similar process, or assignment by operation of law. Any attempt,
voluntary or involuntary, to effect any action specified in the immediately
preceding sentence shall, to the full extent permitted by law, be null, void,
and of no effect.

     All notices and other communications hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

       If to Executive:  William J. Maxwell
       ---------------   528 Lake Street S. A-302
                         Kirkland, WA  98033      


       If to the Company:  Advanced Radio Telecom Corp.
       -----------------   500 108th Avenue, N.E.    
                           Suite 2600                
                           Bellevue, WA 98004        
                           Attention: General Counsel 

or to such other address as either party shall have furnished to the other in
writing in accordance herewith.  Notice and communications shall be effective
when actually received by the addressee.

     IN WITNESS WHEREOF, the Company and Executive have each caused this
Agreement to be duly executed and delivered as of the date set forth above.

                                 ADVANCED RADIO TELECOM CORP.


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


                                 ----------------------------------
                                 William J. Maxwell

                                      -10-
<PAGE>
 
                                   EXHIBIT A

       Change of Control.  For the purposes of this Agreement, a "Change of
       -----------------                                                   
Control" shall mean:

          (a)  The acquisition by any person, corporation, partnership, limited
               liability company or other entity (a "Person", which term shall
               include a group within the meaning of section 13(d) of the
               Securities Exchange Act of 1934 (the "Exchange Act")) of ultimate
               beneficial ownership (within the meaning of Rule 13d-3
               promulgated under the Exchange Act), directly or indirectly of
               30% or more of either (i) the then outstanding shares of common
               stock of the Company (the "Outstanding Company Common Stock") or
               (ii) the combined voting power of the then outstanding voting
               securities of the Company entitled to vote generally in the
               election of directors (the "Outstanding Company Voting
               Securities"); provided, however, that for purposes of this
               subsection (a), the following acquisitions shall not constitute a
               Change of Control:  (i) any such acquisition directly from the
               Company, except for acquisition of securities upon conversion of
               other securities of the Company (ii) any such acquisition by the
               Company, (iii) any such acquisition by any employee benefit plan
               (or related trust) sponsored or maintained by the Company or any
               corporation controlled by the Company or (iv) any such
               acquisition by any corporation pursuant to a transaction which
               complies with clauses (i), (ii) and (iii) of subsection (c) of
               this Exhibit A; or

          (b)  Individuals who, as of the date hereof, constitute the Board (the
               "Incumbent Board") cease for any reason to constitute at least a
               majority of the Board; provided, however, that any individual
               becoming a director subsequent to the date hereof whose election,
               or nomination for election, by the Company's shareholders, was
               approved by a vote of at least a majority of the directors then
               comprising the Incumbent Board shall be considered as though such
               individual were a member of the Incumbent Board, but excluding,
               for this purpose, any such individual whose initial assumption of
               office occurs as a result of an actual or threatened election
               contest with respect to the election or removal of directors or
               other actual or threatened solicitation of proxies or consents by
               or on behalf of a Person other than the Board; or

          (c)  Consummation of a reorganization, merger or consolidation or sale
               or other disposition of all or substantially all of the assets of
               the Company in one or a series of transactions (a "Business
               Combination"), in each case, unless, following such Business
               Combination, (i) all or substantially all of the individuals and
               entities who were the beneficial owners, respectively, of the

                                      -11-
<PAGE>
 
               Outstanding Company Common Stock and Outstanding Company Voting
               Securities immediately prior to such Business Combination
               beneficially own, directly or indirectly, immediately following
               such Business Combination more than 50% of, respectively, the
               outstanding shares of common stock and the combined voting power
               of the then outstanding voting securities entitled to vote
               generally in the election of directors, as the case may be, of
               the corporation resulting from such Business Combination
               (including, without limitation, a corporation which as a result
               of such transaction owns the Company or all or substantially all
               of the Company's assets either directly or through one or more
               subsidiaries) in substantially the same proportions as their
               ownership, immediately prior to such Business Combination of the
               Outstanding Company Common Stock and outstanding Company Voting
               Securities, as the case may be, (ii) no Person (excluding any
               corporation resulting from such Business Combination or any
               employee benefit plan (or related trust) of the Company or such
               corporation resulting from such Business Combination) ultimately
               beneficially owns, directly or indirectly, 30% or more of,
               respectively, the then outstanding shares of common stock of the
               corporation resulting from such Business Combination or the
               combined voting power of the then outstanding voting securities
               of such corporation except to the extent that such ownership
               existed prior to the Business Combination and (iii) at least a
               majority of the members of the board of directors of the
               corporation resulting from such Business Combination were members
               of the Incumbent Board at the time of the execution of the
               initial agreement, or of the action of the Board, providing for
               such Business Combination; or

          (d)  Approval by the shareholders of the Company of a complete
               liquidation or dissolution of the Company.

                                      -12-

<PAGE>
 
                                                                    EXHIBIT 10.6


                         ADVANCED RADIO TELECOM CORP.
               Amended and Restated Change of Control Agreement
               ------------------------------------------------ 

     AGREEMENT, made this 3rd day of February, 1999 by and between George R.
Olexa ("Executive") and ADVANCED RADIO TELECOM CORP. (the "Company");

RECITALS:

    A.    The Board of Directors of the Company (the "Board") recognizes that
the possibility of a change in control may exist and that such possibility, and
the uncertainty and questions which it may raise among management personnel, may
result in the departure or distraction of management personnel to the detriment
of the Company and its stockholders;

    B.    The Board has determined that appropriate steps should be taken to
reinforce and encourage the continued attention and dedication of members of the
Company's management, including Executive, to their duties, to assisting the
Board in assessing proposals with respect to a change in control and to advising
the Board as to the best interests of the Company and its shareholders with
respect to such potential change in control, without distraction and conflict
arising from the possibility of a change in control;

    C.    The Board wishes to induce Executive to remain in the employ of the
Company and to assure him of fair severance should his employment terminate in
specified circumstances following a change of control of the Company.

    NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the parties hereto agree as follows:

    1.    If within 24 months following a Change of Control (as defined in
Exhibit A) (the "Post Change of Control Period") Executive's employment with the
Company is terminated (i) by the Company for any reason (other than for "Cause"
or "Disability" (as defined paragraph 4 below) or as a result of Executive's
death), or (ii) Executive terminates such employment for Good Reason (as defined
in paragraph 4 below):

        (a) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the sum of (i) Executive's annual base salary ("Base Salary") at
            the time of termination through the date of such termination of
            employment to the extent not theretofore paid, (ii) a prorated
            portion of Executive's maximum incentive compensation for the fiscal
            year in which such termination shall occur, calculated by
            multiplying (A) such incentive compensation times (B) a fraction,
            the numerator of which is the number of days in the fiscal year
            through the date of termination of employment, and the 
<PAGE>
 
            denominator of which is 365, (iii) if Executive has not been paid
            incentive compensation with respect to the fiscal year prior to the
            year in which such termination occurs and during which Executive was
            employed by the Company (except where prior to the Change of Control
            the Board had determined that no such incentive compensation was to
            be paid to Executive with respect to such prior year), Executive's
            maximum incentive bonus for such prior fiscal year prorated for the
            period of his employment by the Company if less than a full year
            (provided that if any target incentive compensation under (ii) or
            (iii) was expressed in shares of common stock rather than cash, the
            Company will pay the cash equivalent of such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition), in the case of the Company's common stock as of
            the date prior to the date of the Change of Control), and (iv) any
            accrued and unpaid vacation pay through the date of termination; and

        (b) Any stock, stock option or other awards granted to Executive by the
            Company shall immediately vest and, if applicable, become
            exercisable in full, notwithstanding any provision to the contrary,
            and shall remain exercisable, if applicable, until the earlier of
            the fourth anniversary of such termination of employment or the
            latest date on which such grant could have been exercised, any
            restrictions on any restricted stock, deferred stock or other awards
            shall immediately terminate and all such awards shall immediately be
            vested in full, and any certificates for any deferred stock shall be
            delivered to Executive no later than five business days following
            such termination;

        (c) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the greater of (i) an amount equal to Executive's aggregate Base
            Salary and maximum incentive compensation for the period from the
            date of termination through December 31, 2000 determined as if he
            had been employed through December 31, 2000 (but without duplication
            of amounts paid pursuant to Section 1(a) above) or (ii) an amount
            equal to:  (A) the amount of Executive's Base Salary at the rate in
            effect immediately prior to the date of termination or at the rate
            in effect immediately prior to the Change of Control, whichever is
            higher, and (B) the amount of Executive's maximum incentive
            compensation for the fiscal year during which the termination of
            employment occurs or the amount of Executive's maximum incentive
            compensation in effect immediately prior to the Change of Control,
            whichever is higher (provided that if any such incentive
            compensation is expressed or was paid in shares of common stock
            rather than cash, the calculation will be based on, and the Company
            will pay the cash equivalent of, such compensation based on the
            closing price per share as reported in the Wall Street Journal
            (Eastern Edition) in the case of a share of the Company's common
            stock determined on the date prior to the date of the Change of
            Control.

                                      -2-
<PAGE>
 
        (d) Executive, together with his dependents, will continue following
            such termination of employment to participate fully in the life and
            medical insurance plans maintained or sponsored by the Company
            immediately prior to the Change of Control on the same basis they
            participated prior to the Change in Control until the earlier of (i)
            the second anniversary of such termination or any longer period as
            may be provided by the terms of such plan or (ii) the date Executive
            becomes re-employed with another employer and is eligible to receive
            substantially equivalent life and medical benefits under another
            employer provided plan, provided that if the continued participation
            of Executive and his dependents is not possible under the terms of
            any of such Company plans, the Company shall instead either arrange
            to provide Executive and his dependents with substantially
            equivalent benefits or pay to Executive (within five days of the
            date of termination) an amount equal to the full value thereof in
            cash; and

        (e) the Company will promptly reimburse Executive for any and all legal
            fees and expenses (including, without limitation, stenographer fees
            and printing costs) incurred by him as a result of such termination
            of employment, including without limitation all fees and expenses
            incurred to enforce the provisions of this Agreement or contest or
            dispute that the termination of his employment is for Cause or other
            than for Good Reason (regardless of the outcome thereof).

     Notwithstanding anything herein to the contrary, (i) to the extent that any
payment or benefit provided for herein is required to be paid or vested on any
earlier date under the terms of any plan, agreement or arrangement, such plan,
agreement or arrangement shall control; and (ii) if the Company terminates
Executive's employment for a reason other than Cause prior to the date upon
which the Change of Control occurs, and Executive reasonably demonstrates that
such termination of employment (x) was at the request of a third party who has
taken steps reasonably calculated to effect a Change of Control or (y) otherwise
arose in connection with or in anticipation of a Change of Control, then for all
purposes of this Agreement, Executive shall be entitled to the benefits provides
in Section 1 above.

     To avert duplication of benefits, if Executive receives any payment of Base
Salary, incentive compensation or severance other than under this Agreement
("Other Termination Payments") upon the termination of his employment with the
Company, the amount of such payments shall be deducted from the amount paid
under this Agreement and the benefits to be provided hereunder shall be provided
only to the extent additional to the benefits to be provided other than under
this Agreement; provided, however, that neither this paragraph nor the
provisions of any other agreement shall be interpreted to reduce the amount
payable to Executive below the amount that would otherwise have been payable
under this Agreement if such Other Termination Payments had not been made.

                                      -3-
<PAGE>
 
     2.   Death, Disability, Cause, Other Than For Good Reason


          (a)  If Executive's employment shall terminate during the Post Change
               of Control Period by reason of Executive's death, this Agreement
               shall terminate without further obligations to Executive's legal
               representatives under this Agreement.

          (b)  If Executive's employment is terminated during the Post Change of
               Control Period by reason of Executive's Disability, this
               Agreement shall terminate without further obligations to
               Executive.  For purposes of this Agreement, "Disability" shall
               have the meaning given in the Company's long-term disability plan
               defining the date and conditions for which Executive is entitled
               to receive long-term disability compensation pursuant to such
               long-term disability plan. If the Company determines in good
               faith that the Disability of Executive has occurred during the
               Post Change of Control Period, it may give Executive written
               notice of its intention to terminate Executive's employment.  In
               such event, Executive's employment with the Company shall
               terminate effective on the 30th day after receipt of such notice
               by Executive, provided that, within the 30 days of such receipt,
               Executive shall not have returned to full-time performance of
               Executive's duties.

          (c)  If Executive's employment shall be terminated for Cause (as
               defined in Section 4 below) during the Post Change of Control
               Period, this Agreement shall terminate without further
               obligations to Executive other than the obligation to pay
               Executive (A) his Base Salary through the date of termination and
               (B) Other Benefits, in each case to the extent theretofore
               unpaid.

          (d)  If Executive voluntarily terminates employment during the Post
               Change of Control Period, excluding a termination for Good
               Reason, this Agreement shall terminate without further
               obligations to Executive.


     3.   "Cause" means only: (a) commission of a felony or gross neglect of
duty by Executive rising to the level of deliberate dereliction, (b) conviction
of a crime involving moral turpitude, or (c) willful failure by Executive in the
performance of his duties to the Company which failure is deliberate on
Executive's part, results in material injury to the Company, and continues for
more than 30 days after written notice given to Executive pursuant to a two-
thirds vote of all of the members of the Board at a meeting called and held for
such purpose (after reasonable notice to Executive) and at which meeting
Executive and his counsel were given an opportunity to be heard, such vote to
set forth in reasonable detail the nature of the failure.  For purposes of this
definition of Cause, no act or omission shall be considered to have been
"willful" unless it was not in good faith and Executive had knowledge at the
time that the act or omission was not in the best interest of the Company.  Any
act or failure to act based on authority given 

                                      -4-
<PAGE>
 
pursuant to a resolution duly adopted by the Board or based on the advice of
counsel of the Company shall be conclusively presumed to be done, or omitted to
be done, by Executive in good faith and in the best interest of the Company.
Cause shall not include willful failure due to incapacity resulting from
physical or mental illness or any actual or anticipated failure after Notice of
Termination for Good Reason.

     4.   Executive shall be deemed to have voluntarily terminated his
employment for Good Reason if Executive leaves the employ of the Company for any
reason following:

          (a)  The assignment to Executive of any duties inconsistent in any
               respect with Executive's position (including status, offices,
               titles and reporting requirements), authority, duties or
               responsibilities immediately prior to the Change of Control; or
               the diminution or adverse alteration in any material adverse
               respect of such position, authority, duties or responsibilities,
               excluding for this purpose an isolated, insubstantial and
               inadvertent action not taken in bad faith and which is remedied
               by the Company promptly after receipt of notice thereof given by
               Executive;

          (b)  Any reduction in Executive's rate of Base Salary for any fiscal
               year to less than 100% of the rate of Base Salary payable for the
               fiscal year immediately preceding the Change of Control or of the
               Base Salary provided for such fiscal year in any agreement
               between Executive and the Company, or reduction in Executive's
               total cash and stock compensation opportunities, including Base
               Salary and incentives, for any fiscal year to less than 100% of
               the total cash and stock compensation opportunities made
               available to him immediately preceding the Change of Control for
               the then current fiscal year or of the total cash and stock
               compensation opportunities which were to be made available to him
               for the fiscal year pursuant to any agreement between Executive
               and the Company  (for this purpose, such opportunities shall be
               deemed reduced if the objective standards by which Executive's
               incentive compensation measured becomes more stringent, the
               target or maximum amounts of such incentive compensation are
               reduced, or the amount of such incentive compensation is reduced
               on a discretionary basis from the amount that would be payable
               solely by reference to the objectives); or

          (c)  Failure of the Company to continue in effect any retirement,
               life, medical, dental, disability accidental death or travel
               insurance plan or other benefit plan or practice, in which
               Executive was participating immediately prior to the Change of
               Control unless the Company provides Executive with a plan or
               plans or practices that provide substantially similar benefits,
               or the taking of any action by the Company that would adversely
               affect Executive's participation in or materially reduce
               Executive's benefits under any of such 

                                      -5-
<PAGE>
 
               plans or practices or deprive Executive of any material fringe
               benefit enjoyed by Executive immediately prior to the Change of
               Control other than an isolated, insubstantial and inadvertent
               failure not occurring in bad faith and which is remedied by the
               Company promptly after receipt of notice thereof given by
               Executive; or

          (d)  The Company requires Executive to be based at any office or
               location further than 40 miles from the City of Bellevue, or the
               Company requires Executive to travel on Company business to a
               substantially greater extent than required immediately prior to
               the date of the Change of Control; or

          (e)  Any failure by the Company to comply with and satisfy Section 6
               of this Agreement.

     Executive's right to terminate his employment pursuant to this section
shall not be affected by his incapacity due to physical or mental illness.
Executive's continued employment shall not constitute consent to, or a waiver of
rights with respect to, any circumstances constituting Good Reason hereunder.

     5.   In the case of any dispute under this Agreement, Executive may
initiate binding arbitration in Seattle, Washington before the American
Arbitration Association by serving a notice to arbitrate upon the Company or, at
Executive's election, institute judicial proceedings.  The Company shall not
have the right to initiate binding arbitration, and agrees that upon the
initiation of binding arbitration by Executive pursuant to this paragraph 5 the
Company shall cause to be dismissed any judicial proceedings it has brought
against Executive relating to this Agreement.  The Company authorizes Executive
from time to time to retain counsel of his choice to represent Executive in
connection with any and all actions, proceedings, and/or arbitration, whether by
or against the Company or any director, officer, shareholder, or other person
affiliated with the Company, which may affect Executive's rights under this
Agreement.  Company agrees to (i) pay the fees and expenses of such counsel,
(ii) to pay the cost of such arbitration and/or judicial proceeding, and (iii)
pay interest to Executive on all amounts owed to Executive under this Agreement
during any period of time that such amounts are withheld pending arbitration
and/or judicial proceedings.  Such interest will be at the base rate as
announced from time to time by Canadian Imperial Bank of Commerce.

     In addition, notwithstanding any existing or prior attorney-client
relationship between the Company and counsel retained by Executive, the Company
irrevocably consents to Executive entering into an attorney-client relationship
with such counsel and agrees that a confidential relationship shall exist
between Executive and such counsel.

     6.   If the Company is at any time before or after a Change of Control
merged or consolidated into or with any other corporation or other entity
(whether or not the Company is the surviving entity), or if substantially all of
the assets thereof are transferred to another corporation 

                                      -6-
<PAGE>
 
or other entity, the provisions of this Agreement will be binding upon and inure
to the benefit of the corporation or other entity resulting from such merger or
consolidation or the acquirer of such assets (the "Successor Entity"), and this
paragraph 6 will apply in the event of any subsequent merger or consolidation or
transfer of assets. The Company will require any such Successor Entity to assume
expressly and agree to perform this Agreement in the same manner and to the same
extent that the Company would be required to perform if no such transaction had
taken place. As used in this Agreement, "Company" shall mean the Company as
hereinbefore defined and any Successor Entity which assumes and agrees to
perform this Agreement by operation of law or otherwise.

     In the event of any merger, consolidation, or sale of assets described
above, nothing contained in this Agreement will detract from or otherwise limit
Executive's right to or privilege of participation in any stock option or
purchase plan or any bonus, profit sharing, pension, group insurance,
hospitalization, or other incentive or benefit plan or arrangement which may be
or become applicable to executives of the corporation resulting from such merger
or consolidation or the corporation acquiring such assets of the Company.

     In the event of any merger, consolidation, or sale of assets described
above, references to the Company in this Agreement shall unless the context
suggests otherwise be deemed to include the entity resulting from such merger or
consolidation or the acquiror of such assets of the Company.

     7.   Any termination by the Company for Cause, or by Executive for Good
Reason, shall be communicated by Notice of Termination to the other party hereto
given in accordance with the last paragraph of Section 12 of this Agreement.
For purposes of this Agreement, a "Notice of Termination" means a written notice
that (i) indicates the specific termination provision in this Agreement relied
upon, (ii) to the extent applicable, sets forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of Executive's
employment under the provision so indicated and (iii) if the Date of Termination
(as defined below) is other than the date of receipt of such notice, specifies
the termination date (which date shall be not more than thirty days after the
giving of such notice).  The failure by Executive or the Company to set forth in
the Notice of Termination any fact or circumstance which contributes to a
showing of Good Reason or Cause shall not waive any right of Executive or the
Company, respectively, hereunder or preclude Executive or the Company,
respectively, from asserting such fact or circumstance in enforcing Executive's
or the Company's rights hereunder.

     "Date of Termination" means (i) if Executive's employment is terminated by
the Company for Cause, or by Executive for Good Reason, the date of receipt of
the Notice of Termination or any later date specified therein, as the case may
be, (ii) if Executive's employment is terminated by the Company other than for
Cause or Disability, the Date of Termination shall be the date on which the
Company notifies Executive of such termination and (iii) if Executive's
employment is terminated by reason of death or Disability, the Date of
Termination shall be the date of death of Executive or the effective date of the
Disability, as the case may be.

                                      -7-
<PAGE>
 
     8.   All payments required to be made by the Company hereunder to Executive
or his dependents, beneficiaries, or estate will be subject to the withholding
of such amounts relating to tax and/or other payroll deductions as may be
required by law.

     In the event that it is determined that any payment or benefit provided by
the Company to or for the benefit of Executive, either under this Agreement or
otherwise, will be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code or any successor provision(s) ("Section 4999"), the
Company will, prior to the date on which any amount of the excise tax must be
paid or withheld, make an additional lump-sum payment (the "Gross-up Payment")
to Executive in an amount sufficient, after giving effect to all federal, state
and other taxes and charges (including interest and penalties, if any) with
respect to the gross-up payment, to make Executive whole for all taxes
(including withholding taxes) and any associated interest and penalties, imposed
under or as a result of Section 4999.

     Determinations under this Section 8 will be made by Coopers & Lybrand
unless Executive has reasonable objections to the use of that firm, in which
case the determinations will be made by a comparable firm chosen by Executive
after consultation with the Company (the firm making the determinations to be
referred to as the "Firm").  The determinations of the Firm will be binding upon
the Company and Executive except as the determinations are established in
resolution (including by settlement) of a controversy with the Internal Revenue
Service to have been incorrect.  All fees and expenses of the Firm will be paid
by the Company.

     If the Internal Revenue Service asserts a claim that, if successful, would
require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service.  The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy.  The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

     9.   There shall be no requirement on the part of Executive to seek other
employment or otherwise mitigate damages in order to be entitled to the full
amount of any payments and benefits to which Executive is entitled under this
Agreement, and the amount of such payments and benefits shall not be reduced by
any compensation or benefits received by Executive from other employment other
than with respect to certain welfare benefits as provided in the first proviso
to Section 1(d).

                                      -8-
<PAGE>
 
     10.  Nothing contained in this Agreement shall be construed as a contract
of employment between Company and Executive, or as a right of Executive to
continue in the employ of Company, or as a limitation of the right of Company to
discharge Executive with or without Cause; provided that Executive shall have
the right to receive upon termination of his employment the payments and
benefits provided in this Agreement and shall not be deemed to have waived any
rights he may have either at law or in equity in respect of such discharge.

     11.  No amendment, change, or modification of this Agreement may be made
except in writing, signed by both parties.  This agreement amends and restates
in its entirety the Change of Control Agreement between the parties, dated
February 1, 1998.

     12.  This Agreement shall terminate on December 31, 2000, provided,
however, that commencing on December 31, 1999 and on each annual anniversary of
such date (each such date hereinafter referred to as a "Renewal Date"), unless
previously terminated, the term of this Agreement shall be automatically
extended so as to terminate three years from such Renewal Date, unless at least
sixty days prior to the Renewal Date the Company shall give notice to Executive
that the term of this Agreement shall not be so extended.  This Agreement shall
not apply to a Change of Control which takes place after the termination of this
Agreement.
 
     The provisions of this Agreement shall be binding upon and shall inure to
the benefit of Executive, his executors, administrators, legal representatives
and assigns, and the Company and its successors.

     The validity, interpretation, and effect of this Agreement shall be
governed by the laws of the State of Washington.  Any ambiguities in this
Agreement shall be construed in favor of Executive.

     The invalidity or unenforceability of any provisions of this Agreement
shall not affect the validity or enforceability of any other provision of this
Agreement, which shall remain in full force and effect.

     The Company shall have no right of set-off or counterclaims, in respect of
any claim, debt, or obligation, against any payments to Executive, his
dependents, beneficiaries, or estate provided for in this Agreement.

     No right or interest to or in any payments shall be assignable by
Executive; provided, however, that this provision shall not preclude him from
           --------                                                          
designating one or more beneficiaries to receive any amount that may be payable
after his death and shall not preclude the legal representative of his estate
from assigning any right hereunder to the person or persons entitled thereto
under his will or, in the case of intestacy, to the person or persons entitled
thereto under the laws of intestacy applicable to his estate.  The term
"beneficiaries" as used in this Agreement shall mean a beneficiary or
beneficiaries so designated to receive any such amount, or if no beneficiary has
been so designated, the legal representative of Executive's estate.

                                      -9-
<PAGE>
 
     No right, benefit, or interest hereunder, shall be subject to anticipation,
alienation, sale, assignment, encumbrance, charge, pledge, hypothecation or set-
off in respect of any claim, debt or obligation, or to execution, attachment,
levy or similar process, or assignment by operation of law. Any attempt,
voluntary or involuntary, to effect any action specified in the immediately
preceding sentence shall, to the full extent permitted by law, be null, void,
and of no effect.

     All notices and other communications hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

       If to Executive:  George R. Olexa
       ---------------   17756 NE 90th Street
                         Apt. N372
                         Redmond, WA  98052

       If to the Company:  Advanced Radio Telecom Corp.
       -----------------   500 108th Avenue, N.E.
                           Suite 2600
                           Bellevue, WA 98004
                           Attention: General Counsel

or to such other address as either party shall have furnished to the other in
writing in accordance herewith.  Notice and communications shall be effective
when actually received by the addressee.

     IN WITNESS WHEREOF, the Company and Executive have each caused this
Agreement to be duly executed and delivered as of the date set forth above.

                                 ADVANCED RADIO TELECOM CORP.


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


                                 ---------------------------------
                                 George R. Olexa

                                      -10-
<PAGE>
 
                                 EXHIBIT A

       Change of Control.  For the purposes of this Agreement, a "Change of
       -----------------                                                   
Control" shall mean:

          (a)  The acquisition by any person, corporation, partnership, limited
               liability company or other entity (a "Person", which term shall
               include a group within the meaning of section 13(d) of the
               Securities Exchange Act of 1934 (the "Exchange Act")) of ultimate
               beneficial ownership (within the meaning of Rule 13d-3
               promulgated under the Exchange Act), directly or indirectly of
               30% or more of either (i) the then outstanding shares of common
               stock of the Company (the "Outstanding Company Common Stock") or
               (ii) the combined voting power of the then outstanding voting
               securities of the Company entitled to vote generally in the
               election of directors (the "Outstanding Company Voting
               Securities"); provided, however, that for purposes of this
               subsection (a), the following acquisitions shall not constitute a
               Change of Control:  (i) any such acquisition directly from the
               Company, except for acquisition of securities upon conversion of
               other securities of the Company (ii) any such acquisition by the
               Company, (iii) any such acquisition by any employee benefit plan
               (or related trust) sponsored or maintained by the Company or any
               corporation controlled by the Company or (iv) any such
               acquisition by any corporation pursuant to a transaction which
               complies with clauses (i), (ii) and (iii) of subsection (c) of
               this Exhibit A; or

          (b)  Individuals who, as of the date hereof, constitute the Board (the
               "Incumbent Board") cease for any reason to constitute at least a
               majority of the Board; provided, however, that any individual
               becoming a director subsequent to the date hereof whose election,
               or nomination for election, by the Company's shareholders, was
               approved by a vote of at least a majority of the directors then
               comprising the Incumbent Board shall be considered as though such
               individual were a member of the Incumbent Board, but excluding,
               for this purpose, any such individual whose initial assumption of
               office occurs as a result of an actual or threatened election
               contest with respect to the election or removal of directors or
               other actual or threatened solicitation of proxies or consents by
               or on behalf of a Person other than the Board; or

          (c)  Consummation of a reorganization, merger or consolidation or sale
               or other disposition of all or substantially all of the assets of
               the Company in one or a series of transactions (a "Business
               Combination"), in each case, unless, following such Business
               Combination, (i) all or substantially all of the individuals and
               entities who were the beneficial owners, respectively, of the

                                      -11-
<PAGE>
 
               Outstanding Company Common Stock and Outstanding Company Voting
               Securities immediately prior to such Business Combination
               beneficially own, directly or indirectly, immediately following
               such Business Combination more than 50% of, respectively, the
               outstanding shares of common stock and the combined voting power
               of the then outstanding voting securities entitled to vote
               generally in the election of directors, as the case may be, of
               the corporation resulting from such Business Combination
               (including, without limitation, a corporation which as a result
               of such transaction owns the Company or all or substantially all
               of the Company's assets either directly or through one or more
               subsidiaries) in substantially the same proportions as their
               ownership, immediately prior to such Business Combination of the
               Outstanding Company Common Stock and outstanding Company Voting
               Securities, as the case may be, (ii) no Person (excluding any
               corporation resulting from such Business Combination or any
               employee benefit plan (or related trust) of the Company or such
               corporation resulting from such Business Combination) ultimately
               beneficially owns, directly or indirectly, 30% or more of,
               respectively, the then outstanding shares of common stock of the
               corporation resulting from such Business Combination or the
               combined voting power of the then outstanding voting securities
               of such corporation except to the extent that such ownership
               existed prior to the Business Combination and (iii) at least a
               majority of the members of the board of directors of the
               corporation resulting from such Business Combination were members
               of the Incumbent Board at the time of the execution of the
               initial agreement, or of the action of the Board, providing for
               such Business Combination; or

          (d)  Approval by the shareholders of the Company of a complete
               liquidation or dissolution of the Company.

                                      -12-

<PAGE>
 
                                                                    EXHIBIT 10.8

                         ADVANCED RADIO TELECOM CORP.
               Amended and Restated Change of Control Agreement
               ------------------------------------------------

     AGREEMENT, made this 3rd day of February, 1999 by and between Thomas Boyhan
("Executive") and ADVANCED RADIO TELECOM CORP. (the "Company");

RECITALS:

    A.    The Board of Directors of the Company (the "Board") recognizes that
the possibility of a change in control may exist and that such possibility, and
the uncertainty and questions which it may raise among management personnel, may
result in the departure or distraction of management personnel to the detriment
of the Company and its stockholders;

    B.    The Board has determined that appropriate steps should be taken to
reinforce and encourage the continued attention and dedication of members of the
Company's management, including Executive, to their duties, to assisting the
Board in assessing proposals with respect to a change in control and to advising
the Board as to the best interests of the Company and its shareholders with
respect to such potential change in control, without distraction and conflict
arising from the possibility of a change in control;

    C.    The Board wishes to induce Executive to remain in the employ of the
Company and to assure him of fair severance should his employment terminate in
specified circumstances following a change of control of the Company.

    NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the parties hereto agree as follows:

    1.    If within 24 months following a Change of Control (as defined in
Exhibit A) (the "Post Change of Control Period") Executive's employment with the
Company is terminated (i) by the Company for any reason (other than for "Cause"
or "Disability" (as defined paragraph 4 below) or as a result of Executive's
death), or (ii) Executive terminates such employment for Good Reason (as defined
in paragraph 4 below):

        (a) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the sum of (i) Executive's annual base salary ("Base Salary") at
            the time of termination through the date of such termination of
            employment to the extent not theretofore paid, (ii) a prorated
            portion of Executive's maximum incentive compensation for the fiscal
            year in which such termination shall occur, calculated by
            multiplying (A) such incentive compensation times (B) a fraction,
            the numerator of which is the number of days in the fiscal year
            through the date of termination of employment, and the 
<PAGE>
 
            denominator of which is 365, (iii) if Executive has not been paid
            incentive compensation with respect to the fiscal year prior to the
            year in which such termination occurs and during which Executive was
            employed by the Company (except where prior to the Change of Control
            the Board had determined that no such incentive compensation was to
            be paid to Executive with respect to such prior year), Executive's
            maximum incentive bonus for such prior fiscal year prorated for the
            period of his employment by the Company if less than a full year
            (provided that if any target incentive compensation under (ii) or
            (iii) was expressed in shares of common stock rather than cash, the
            Company will pay the cash equivalent of such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition), in the case of the Company's common stock as of
            the date prior to the date of the Change of Control), and (iv) any
            accrued and unpaid vacation pay through the date of termination; and

        (b) Any stock, stock option or other awards granted to Executive by the
            Company shall immediately vest and, if applicable, become
            exercisable in full, notwithstanding any provision to the contrary,
            and shall remain exercisable, if applicable, until the earlier of
            the fourth anniversary of such termination of employment or the
            latest date on which such grant could have been exercised, any
            restrictions on any restricted stock, deferred stock or other awards
            shall immediately terminate and all such awards shall immediately be
            vested in full, and any certificates for any deferred stock shall be
            delivered to Executive no later than five business days following
            such termination;

        (c) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the greater of (i) an amount equal to Executive's aggregate Base
            Salary and maximum incentive compensation for the period from the
            date of termination through December 31, 2000 determined as if he
            had been employed through December 31, 2000 (but without duplication
            of amounts paid pursuant to Section 1(a) above) or (ii) an amount
            equal to:  (A) the amount of Executive's Base Salary at the rate in
            effect immediately prior to the date of termination or at the rate
            in effect immediately prior to the Change of Control, whichever is
            higher, and (B) the amount of Executive's maximum incentive
            compensation for the fiscal year during which the termination of
            employment occurs or the amount of Executive's maximum incentive
            compensation in effect immediately prior to the Change of Control,
            whichever is higher (provided that if any such incentive
            compensation is expressed or was paid in shares of common stock
            rather than cash, the calculation will be based on, and the Company
            will pay the cash equivalent of, such compensation based on the
            closing price per share as reported in the Wall Street Journal
            (Eastern Edition) in the case of a share of the Company's common
            stock determined on the date prior to the date of the Change of
            Control.

                                      -2-
<PAGE>
 
        (d) Executive, together with his dependents, will continue following
            such termination of employment to participate fully in the life and
            medical insurance plans maintained or sponsored by the Company
            immediately prior to the Change of Control on the same basis they
            participated prior to the Change in Control until the earlier of (i)
            the second anniversary of such termination or any longer period as
            may be provided by the terms of such plan or (ii) the date Executive
            becomes re-employed with another employer and is eligible to receive
            substantially equivalent life and medical benefits under another
            employer provided plan, provided that if the continued participation
            of Executive and his dependents is not possible under the terms of
            any of such Company plans, the Company shall instead either arrange
            to provide Executive and his dependents with substantially
            equivalent benefits or pay to Executive (within five days of the
            date of termination) an amount equal to the full value thereof in
            cash; and

        (e) the Company will promptly reimburse Executive for any and all legal
            fees and expenses (including, without limitation, stenographer fees
            and printing costs) incurred by him as a result of such termination
            of employment, including without limitation all fees and expenses
            incurred to enforce the provisions of this Agreement or contest or
            dispute that the termination of his employment is for Cause or other
            than for Good Reason (regardless of the outcome thereof).

     Notwithstanding anything herein to the contrary, (i) to the extent that any
payment or benefit provided for herein is required to be paid or vested on any
earlier date under the terms of any plan, agreement or arrangement, such plan,
agreement or arrangement shall control; and (ii) if the Company terminates
Executive's employment for a reason other than Cause prior to the date upon
which the Change of Control occurs, and Executive reasonably demonstrates that
such termination of employment (x) was at the request of a third party who has
taken steps reasonably calculated to effect a Change of Control or (y) otherwise
arose in connection with or in anticipation of a Change of Control, then for all
purposes of this Agreement, Executive shall be entitled to the benefits provides
in Section 1 above.

     To avert duplication of benefits, if Executive receives any payment of Base
Salary, incentive compensation or severance other than under this Agreement
("Other Termination Payments") upon the termination of his employment with the
Company, the amount of such payments shall be deducted from the amount paid
under this Agreement and the benefits to be provided hereunder shall be provided
only to the extent additional to the benefits to be provided other than under
this Agreement; provided, however, that neither this paragraph nor the
provisions of any other agreement shall be interpreted to reduce the amount
payable to Executive below the amount that would otherwise have been payable
under this Agreement if such Other Termination Payments had not been made.

                                      -3-
<PAGE>
 
     2.   Death, Disability, Cause, Other Than For Good Reason

          (a)  If Executive's employment shall terminate during the Post Change
               of Control Period by reason of Executive's death, this Agreement
               shall terminate without further obligations to Executive's legal
               representatives under this Agreement.

          (b)  If Executive's employment is terminated during the Post Change of
               Control Period by reason of Executive's Disability, this
               Agreement shall terminate without further obligations to
               Executive.  For purposes of this Agreement, "Disability" shall
               have the meaning given in the Company's long-term disability plan
               defining the date and conditions for which Executive is entitled
               to receive long-term disability compensation pursuant to such
               long-term disability plan. If the Company determines in good
               faith that the Disability of Executive has occurred during the
               Post Change of Control Period, it may give Executive written
               notice of its intention to terminate Executive's employment.  In
               such event, Executive's employment with the Company shall
               terminate effective on the 30th day after receipt of such notice
               by Executive, provided that, within the 30 days of such receipt,
               Executive shall not have returned to full-time performance of
               Executive's duties.

          (c)  If Executive's employment shall be terminated for Cause (as
               defined in Section 4 below) during the Post Change of Control
               Period, this Agreement shall terminate without further
               obligations to Executive other than the obligation to pay
               Executive (A) his Base Salary through the date of termination and
               (B) Other Benefits, in each case to the extent theretofore
               unpaid.

          (d)  If Executive voluntarily terminates employment during the Post
               Change of Control Period, excluding a termination for Good
               Reason, this Agreement shall terminate without further
               obligations to Executive.


     3.   "Cause" means only: (a) commission of a felony or gross neglect of
duty by Executive rising to the level of deliberate dereliction, (b) conviction
of a crime involving moral turpitude, or (c) willful failure by Executive in the
performance of his duties to the Company which failure is deliberate on
Executive's part, results in material injury to the Company, and continues for
more than 30 days after written notice given to Executive pursuant to a two-
thirds vote of all of the members of the Board at a meeting called and held for
such purpose (after reasonable notice to Executive) and at which meeting
Executive and his counsel were given an opportunity to be heard, such vote to
set forth in reasonable detail the nature of the failure.  For purposes of this
definition of Cause, no act or omission shall be considered to have been
"willful" unless it was not in good faith and Executive had knowledge at the
time that the act or omission was not in the best interest of the Company.  Any
act or failure to act based on authority given 

                                      -4-
<PAGE>
 
pursuant to a resolution duly adopted by the Board or based on the advice of
counsel of the Company shall be conclusively presumed to be done, or omitted to
be done, by Executive in good faith and in the best interest of the Company.
Cause shall not include willful failure due to incapacity resulting from
physical or mental illness or any actual or anticipated failure after Notice of
Termination for Good Reason.

     4.   Executive shall be deemed to have voluntarily terminated his
employment for Good Reason if Executive leaves the employ of the Company for any
reason following:

          (a)  The assignment to Executive of any duties inconsistent in any
               respect with Executive's position (including status, offices,
               titles and reporting requirements), authority, duties or
               responsibilities immediately prior to the Change of Control; or
               the diminution or adverse alteration in any material adverse
               respect of such position, authority, duties or responsibilities,
               excluding for this purpose an isolated, insubstantial and
               inadvertent action not taken in bad faith and which is remedied
               by the Company promptly after receipt of notice thereof given by
               Executive;

          (b)  Any reduction in Executive's rate of Base Salary for any fiscal
               year to less than 100% of the rate of Base Salary payable for the
               fiscal year immediately preceding the Change of Control or of the
               Base Salary provided for such fiscal year in any agreement
               between Executive and the Company, or reduction in Executive's
               total cash and stock compensation opportunities, including Base
               Salary and incentives, for any fiscal year to less than 100% of
               the total cash and stock compensation opportunities made
               available to him immediately preceding the Change of Control for
               the then current fiscal year or of the total cash and stock
               compensation opportunities which were to be made available to him
               for the fiscal year pursuant to any agreement between Executive
               and the Company  (for this purpose, such opportunities shall be
               deemed reduced if the objective standards by which Executive's
               incentive compensation measured becomes more stringent, the
               target or maximum amounts of such incentive compensation are
               reduced, or the amount of such incentive compensation is reduced
               on a discretionary basis from the amount that would be payable
               solely by reference to the objectives); or

          (c)  Failure of the Company to continue in effect any retirement,
               life, medical, dental, disability accidental death or travel
               insurance plan or other benefit plan or practice, in which
               Executive was participating immediately prior to the Change of
               Control unless the Company provides Executive with a plan or
               plans or practices that provide substantially similar benefits,
               or the taking of any action by the Company that would adversely
               affect Executive's participation in or materially reduce
               Executive's benefits under any of such 

                                      -5-
<PAGE>
 
               plans or practices or deprive Executive of any material fringe
               benefit enjoyed by Executive immediately prior to the Change of
               Control other than an isolated, insubstantial and inadvertent
               failure not occurring in bad faith and which is remedied by the
               Company promptly after receipt of notice thereof given by
               Executive; or

          (d)  The Company requires Executive to be based at any office or
               location further than 40 miles from the City of Bellevue, or the
               Company requires Executive to travel on Company business to a
               substantially greater extent than required immediately prior to
               the date of the Change of Control; or

          (e)  Any failure by the Company to comply with and satisfy Section 6
               of this Agreement.

     Executive's right to terminate his employment pursuant to this section
shall not be affected by his incapacity due to physical or mental illness.
Executive's continued employment shall not constitute consent to, or a waiver of
rights with respect to, any circumstances constituting Good Reason hereunder.

     5.   In the case of any dispute under this Agreement, Executive may
initiate binding arbitration in Seattle, Washington before the American
Arbitration Association by serving a notice to arbitrate upon the Company or, at
Executive's election, institute judicial proceedings.  The Company shall not
have the right to initiate binding arbitration, and agrees that upon the
initiation of binding arbitration by Executive pursuant to this paragraph 5 the
Company shall cause to be dismissed any judicial proceedings it has brought
against Executive relating to this Agreement.  The Company authorizes Executive
from time to time to retain counsel of his choice to represent Executive in
connection with any and all actions, proceedings, and/or arbitration, whether by
or against the Company or any director, officer, shareholder, or other person
affiliated with the Company, which may affect Executive's rights under this
Agreement.  Company agrees to (i) pay the fees and expenses of such counsel,
(ii) to pay the cost of such arbitration and/or judicial proceeding, and (iii)
pay interest to Executive on all amounts owed to Executive under this Agreement
during any period of time that such amounts are withheld pending arbitration
and/or judicial proceedings.  Such interest will be at the base rate as
announced from time to time by Canadian Imperial Bank of Commerce.

     In addition, notwithstanding any existing or prior attorney-client
relationship between the Company and counsel retained by Executive, the Company
irrevocably consents to Executive entering into an attorney-client relationship
with such counsel and agrees that a confidential relationship shall exist
between Executive and such counsel.

     6.   If the Company is at any time before or after a Change of Control
merged or consolidated into or with any other corporation or other entity
(whether or not the Company is the surviving entity), or if substantially all of
the assets thereof are transferred to another corporation 

                                      -6-
<PAGE>
 
or other entity, the provisions of this Agreement will be binding upon and inure
to the benefit of the corporation or other entity resulting from such merger or
consolidation or the acquirer of such assets (the "Successor Entity"), and this
paragraph 6 will apply in the event of any subsequent merger or consolidation or
transfer of assets. The Company will require any such Successor Entity to assume
expressly and agree to perform this Agreement in the same manner and to the same
extent that the Company would be required to perform if no such transaction had
taken place. As used in this Agreement, "Company" shall mean the Company as
hereinbefore defined and any Successor Entity which assumes and agrees to
perform this Agreement by operation of law or otherwise.

     In the event of any merger, consolidation, or sale of assets described
above, nothing contained in this Agreement will detract from or otherwise limit
Executive's right to or privilege of participation in any stock option or
purchase plan or any bonus, profit sharing, pension, group insurance,
hospitalization, or other incentive or benefit plan or arrangement which may be
or become applicable to executives of the corporation resulting from such merger
or consolidation or the corporation acquiring such assets of the Company.

     In the event of any merger, consolidation, or sale of assets described
above, references to the Company in this Agreement shall unless the context
suggests otherwise be deemed to include the entity resulting from such merger or
consolidation or the acquiror of such assets of the Company.

     7.   Any termination by the Company for Cause, or by Executive for Good
Reason, shall be communicated by Notice of Termination to the other party hereto
given in accordance with the last paragraph of Section 12 of this Agreement.
For purposes of this Agreement, a "Notice of Termination" means a written notice
that (i) indicates the specific termination provision in this Agreement relied
upon, (ii) to the extent applicable, sets forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of Executive's
employment under the provision so indicated and (iii) if the Date of Termination
(as defined below) is other than the date of receipt of such notice, specifies
the termination date (which date shall be not more than thirty days after the
giving of such notice).  The failure by Executive or the Company to set forth in
the Notice of Termination any fact or circumstance which contributes to a
showing of Good Reason or Cause shall not waive any right of Executive or the
Company, respectively, hereunder or preclude Executive or the Company,
respectively, from asserting such fact or circumstance in enforcing Executive's
or the Company's rights hereunder.

     "Date of Termination" means (i) if Executive's employment is terminated by
the Company for Cause, or by Executive for Good Reason, the date of receipt of
the Notice of Termination or any later date specified therein, as the case may
be, (ii) if Executive's employment is terminated by the Company other than for
Cause or Disability, the Date of Termination shall be the date on which the
Company notifies Executive of such termination and (iii) if Executive's
employment is 

                                      -7-
<PAGE>
 
terminated by reason of death or Disability, the Date of Termination shall be
the date of death of Executive or the effective date of the Disability, as the
case may be.

     8.   All payments required to be made by the Company hereunder to Executive
or his dependents, beneficiaries, or estate will be subject to the withholding
of such amounts relating to tax and/or other payroll deductions as may be
required by law.

     In the event that it is determined that any payment or benefit provided by
the Company to or for the benefit of Executive, either under this Agreement or
otherwise, will be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code or any successor provision(s) ("Section 4999"), the
Company will, prior to the date on which any amount of the excise tax must be
paid or withheld, make an additional lump-sum payment (the "Gross-up Payment")
to Executive in an amount sufficient, after giving effect to all federal, state
and other taxes and charges (including interest and penalties, if any) with
respect to the gross-up payment, to make Executive whole for all taxes
(including withholding taxes) and any associated interest and penalties, imposed
under or as a result of Section 4999.

     Determinations under this Section 8 will be made by Coopers & Lybrand
unless Executive has reasonable objections to the use of that firm, in which
case the determinations will be made by a comparable firm chosen by Executive
after consultation with the Company (the firm making the determinations to be
referred to as the "Firm").  The determinations of the Firm will be binding upon
the Company and Executive except as the determinations are established in
resolution (including by settlement) of a controversy with the Internal Revenue
Service to have been incorrect.  All fees and expenses of the Firm will be paid
by the Company.

     If the Internal Revenue Service asserts a claim that, if successful, would
require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service.  The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy.  The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

     9.   There shall be no requirement on the part of Executive to seek other
employment or otherwise mitigate damages in order to be entitled to the full
amount of any payments and benefits to which Executive is entitled under this
Agreement, and the amount of such payments and benefits shall not be reduced by
any compensation or benefits received by Executive from other employment other
than with respect to certain welfare benefits as provided in the first proviso
to Section 1(d).

                                      -8-
<PAGE>
 
     10.  Nothing contained in this Agreement shall be construed as a contract
of employment between Company and Executive, or as a right of Executive to
continue in the employ of Company, or as a limitation of the right of Company to
discharge Executive with or without Cause; provided that Executive shall have
the right to receive upon termination of his employment the payments and
benefits provided in this Agreement and shall not be deemed to have waived any
rights he may have either at law or in equity in respect of such discharge.

     11.  No amendment, change, or modification of this Agreement may be made
except in writing, signed by both parties.  This agreement amends and restates
in its entirety the Change of Control Agreement between the parties, dated
August 31, 1998.

     12.  This Agreement shall terminate on December 31, 2000, provided,
however, that commencing on December 31, 1999 and on each annual anniversary of
such date (each such date hereinafter referred to as a "Renewal Date"), unless
previously terminated, the term of this Agreement shall be automatically
extended so as to terminate three years from such Renewal Date, unless at least
sixty days prior to the Renewal Date the Company shall give notice to Executive
that the term of this Agreement shall not be so extended.  This Agreement shall
not apply to a Change of Control which takes place after the termination of this
Agreement.
 
     The provisions of this Agreement shall be binding upon and shall inure to
the benefit of Executive, his executors, administrators, legal representatives
and assigns, and the Company and its successors.

     The validity, interpretation, and effect of this Agreement shall be
governed by the laws of the State of Washington.  Any ambiguities in this
Agreement shall be construed in favor of Executive.

     The invalidity or unenforceability of any provisions of this Agreement
shall not affect the validity or enforceability of any other provision of this
Agreement, which shall remain in full force and effect.

     The Company shall have no right of set-off or counterclaims, in respect of
any claim, debt, or obligation, against any payments to Executive, his
dependents, beneficiaries, or estate provided for in this Agreement.

     No right or interest to or in any payments shall be assignable by
Executive; provided, however, that this provision shall not preclude him from
           --------                                                          
designating one or more beneficiaries to receive any amount that may be payable
after his death and shall not preclude the legal representative of his estate
from assigning any right hereunder to the person or persons entitled thereto
under his will or, in the case of intestacy, to the person or persons entitled
thereto under the laws of intestacy applicable to his estate.  The term
"beneficiaries" as used in this Agreement shall mean a beneficiary or
beneficiaries so designated to receive any such amount, or if no beneficiary has
been so designated, the legal representative of Executive's estate.

                                      -9-
<PAGE>
 
     No right, benefit, or interest hereunder, shall be subject to anticipation,
alienation, sale, assignment, encumbrance, charge, pledge, hypothecation or set-
off in respect of any claim, debt or obligation, or to execution, attachment,
levy or similar process, or assignment by operation of law. Any attempt,
voluntary or involuntary, to effect any action specified in the immediately
preceding sentence shall, to the full extent permitted by law, be null, void,
and of no effect.

     All notices and other communications hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

       If to Executive:  Thomas Boyhan
       ---------------   4003 South Oak Circle
                         Sugar Land, TX 77479

       If to the Company:  Advanced Radio Telecom Corp.
       -----------------   500 108th Avenue, N.E.
                           Suite 2600
                           Bellevue, WA 98004
                           Attention: General Counsel

or to such other address as either party shall have furnished to the other in
writing in accordance herewith.  Notice and communications shall be effective
when actually received by the addressee.

     IN WITNESS WHEREOF, the Company and Executive have each caused this
Agreement to be duly executed and delivered as of the date set forth above.

                                 ADVANCED RADIO TELECOM CORP.


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


                                 ----------------------------------
                                 Thomas Boyhan

                                      -10-
<PAGE>
 
                                 EXHIBIT A

       Change of Control.  For the purposes of this Agreement, a "Change of
       -----------------                                                   
Control" shall mean:

          (a)  The acquisition by any person, corporation, partnership, limited
               liability company or other entity (a "Person", which term shall
               include a group within the meaning of section 13(d) of the
               Securities Exchange Act of 1934 (the "Exchange Act")) of ultimate
               beneficial ownership (within the meaning of Rule 13d-3
               promulgated under the Exchange Act), directly or indirectly of
               30% or more of either (i) the then outstanding shares of common
               stock of the Company (the "Outstanding Company Common Stock") or
               (ii) the combined voting power of the then outstanding voting
               securities of the Company entitled to vote generally in the
               election of directors (the "Outstanding Company Voting
               Securities"); provided, however, that for purposes of this
               subsection (a), the following acquisitions shall not constitute a
               Change of Control:  (i) any such acquisition directly from the
               Company, except for acquisition of securities upon conversion of
               other securities of the Company (ii) any such acquisition by the
               Company, (iii) any such acquisition by any employee benefit plan
               (or related trust) sponsored or maintained by the Company or any
               corporation controlled by the Company or (iv) any such
               acquisition by any corporation pursuant to a transaction which
               complies with clauses (i), (ii) and (iii) of subsection (c) of
               this Exhibit A; or

          (b)  Individuals who, as of the date hereof, constitute the Board (the
               "Incumbent Board") cease for any reason to constitute at least a
               majority of the Board; provided, however, that any individual
               becoming a director subsequent to the date hereof whose election,
               or nomination for election, by the Company's shareholders, was
               approved by a vote of at least a majority of the directors then
               comprising the Incumbent Board shall be considered as though such
               individual were a member of the Incumbent Board, but excluding,
               for this purpose, any such individual whose initial assumption of
               office occurs as a result of an actual or threatened election
               contest with respect to the election or removal of directors or
               other actual or threatened solicitation of proxies or consents by
               or on behalf of a Person other than the Board; or

          (c)  Consummation of a reorganization, merger or consolidation or sale
               or other disposition of all or substantially all of the assets of
               the Company in one or a series of transactions (a "Business
               Combination"), in each case, unless, following such Business
               Combination, (i) all or substantially all of the individuals and
               entities who were the beneficial owners, respectively, of the

                                      -11-
<PAGE>
 
               Outstanding Company Common Stock and Outstanding Company Voting
               Securities immediately prior to such Business Combination
               beneficially own, directly or indirectly, immediately following
               such Business Combination more than 50% of, respectively, the
               outstanding shares of common stock and the combined voting power
               of the then outstanding voting securities entitled to vote
               generally in the election of directors, as the case may be, of
               the corporation resulting from such Business Combination
               (including, without limitation, a corporation which as a result
               of such transaction owns the Company or all or substantially all
               of the Company's assets either directly or through one or more
               subsidiaries) in substantially the same proportions as their
               ownership, immediately prior to such Business Combination of the
               Outstanding Company Common Stock and outstanding Company Voting
               Securities, as the case may be, (ii) no Person (excluding any
               corporation resulting from such Business Combination or any
               employee benefit plan (or related trust) of the Company or such
               corporation resulting from such Business Combination) ultimately
               beneficially owns, directly or indirectly, 30% or more of,
               respectively, the then outstanding shares of common stock of the
               corporation resulting from such Business Combination or the
               combined voting power of the then outstanding voting securities
               of such corporation except to the extent that such ownership
               existed prior to the Business Combination and (iii) at least a
               majority of the members of the board of directors of the
               corporation resulting from such Business Combination were members
               of the Incumbent Board at the time of the execution of the
               initial agreement, or of the action of the Board, providing for
               such Business Combination; or

          (d)  Approval by the shareholders of the Company of a complete
               liquidation or dissolution of the Company.

                                      -12-

<PAGE>
 
                                                                    EXHIBIT 10.9

                             EMPLOYMENT AGREEMENT

     AGREEMENT dated as of October 16, 1998 between Robert S. McCambridge
("Executive") and Advanced Radio Telecom Corp. (the "Company"), a Delaware
corporation located at 500 108th Ave NE, Suite 2600, Bellevue, WA 98004.

                                   RECITALS
                                   --------

     Executive seeks to be employed by the Company, and the Company seeks to
employ Executive as its Executive Vice President, Chief Financial Officer.  The
Company and Executive intend that Executive shall serve the Company on the terms
set forth below and, to that end, deem it desirable and appropriate to enter
into this Agreement.

                                   AGREEMENT
                                   ---------

     The parties hereto, in consideration of the mutual agreements hereinafter
contained, agree as follows:

1.   EFFECTIVE DATE; TERM OF AGREEMENT.  This Agreement shall become effective
     ---------------------------------                                        
as of October 27, 1998 (the "Effective Date").  Executive's employment shall
continue on the terms provided herein until December 31, 2000, subject to
earlier termination as provided herein (such period of employment hereinafter
called the "Employment Period").

2.   SCOPE OF EMPLOYMENT.
     ------------------- 

     a.   Nature of Services.  During the Employment Period, Executive shall be
          ------------------                                                   
elected and serve as  Executive Vice President, Chief Financial Officer or as
such other executive vice president designated by the Chief Executive Officer or
the Board of Directors ("Board") of the Company and shall have and diligently
perform the duties and the responsibilities of such office and such additional
executive duties and responsibilities consistent with such office as shall from
time to time be assigned to him.

     b.   Extent of Services.  Except for illnesses and vacation periods,
          ------------------                                             
Executive shall devote substantially all his working time and attention and his
best efforts to the performance of his duties and responsibilities under this
Agreement. However, Executive may (i) make any passive investments where he is
not obligated or required to, and shall not in fact, devote any managerial
efforts, (ii) participate in charitable or community activities or in trade or
professional
<PAGE>
 
organizations, or (iii) subject to Board approval (which approval shall not be
unreasonably withheld or withdrawn), hold directorships in public companies,
provided that the Board shall have the right to limit such investments,
participation and services whenever the Board shall reasonably believe that the
time spent on such activities infringes in any material respect upon the time
required by Executive for the performance of his duties under this Agreement or
is otherwise incompatible in any material regard with those duties.

3.   COMPENSATION AND BENEFITS.
     ------------------------- 

     a.   Base Salary.   Executive shall be paid a base salary at the annualized
          -----------                                                           
rate of One Hundred Seventy Five Thousand and No/100 ($175,000) or such higher
annualized rate  as the Board may determine ("Base Salary"), such Base Salary to
be paid in the same manner and at the same times as the Company shall pay base
salary to other executive employees.

     b.   Bonus Compensation.   Executive will be eligible for an incentive
          ------------------                                               
bonus with respect to each fiscal year or portion thereof during the Employment
Period pursuant to such bonus or incentive compensation plan as is then
available to executives of the Company generally, or if there is no such plan,
as the Board may determine based on performance criteria set annually.  The
maximum incentive bonus for each fiscal year shall be 100% of his Base Salary in
effect with respect to such fiscal year.  For each fiscal year or portion
thereof, the determination of the target incentive bonus and whether Executive
has earned any incentive bonus and the amount thereof shall be made by the Board
in its judgment.

     c.   Policies and Fringe Benefits.  Executive shall be subject to Company
          ----------------------------                                        
policies applicable to its executives generally and shall be entitled to receive
all such fringe benefits as the Company shall from time to time make available
to other executives generally (subject to the terms of any applicable fringe
benefit plan), including vacation of three weeks per year, in accordance with
and subject to prevailing Company policies.


4.   TERMINATION OF EMPLOYMENT.
     ------------------------- 

     a.   The Company shall have the right to terminate Executive's employment
at any time and for any reason, with or without Cause.  Executive may resign for
any reason on thirty (30) days notice and upon Constructive Termination (as
defined below).

                                      -2-
<PAGE>
 
     b.   The Employment Period shall terminate when Executive dies or becomes
Disabled.  In addition, if by reason of Incapacity Executive is unable to
perform his duties for at least six continuous months, the Employment Period may
be terminated by the Company for Incapacity upon written notice by the Company
to Executive.  "Disability" and "Disabled" shall have the meaning given in the
Company's long-term disability plan.  Executive's employment shall be deemed to
be terminated for Disability on the date on which Executive is entitled to
receive long-term disability compensation pursuant to such long-term disability
plan. "Incapacity" shall mean a disability (other than Disability) or other
impairment of health that renders Executive unable to perform his duties to the
reasonable satisfaction of the Board.

     c.   Whenever the Employment Period shall terminate, Executive shall resign
all offices or other positions he holds with the Company and any affiliated
entities.

5.   BENEFITS UPON TERMINATION OF EMPLOYMENT OR UPON EXPIRATION OF THE
     -----------------------------------------------------------------
          AGREEMENT.
          --------- 

     a.   Certain Terminations Prior to December 31, 2000.  If the Employment
          -----------------------------------------------                    
Period shall terminate prior to December 31, 2000 by reason of (i) death,
Disability or Incapacity of Executive, (ii) termination by the Company for any
reason other than Cause or (iii) termination by Executive in the event that
either (A) Executive shall be removed from or fail to be reelected as an
executive vice president (B) Executive is relocated more than 40 miles from the
current corporate headquarters of the Company, in the case without his prior
written consent (each a "Constructive Termination") and subject to Section 6
hereof, Executive shall be entitled to the following severance benefits:

          (i)  The Company shall continue to pay to Executive or his legal
     representative his Base Salary for twelve (12) months following such
     termination and, at the termination of such twelve-month period, shall pay
     Executive an incentive bonus at the target amount at the time of his
     termination; provided that if Executive is eligible for long-term
     disability compensation benefits under any Company long-term disability
     plan, the amount payable under this clause shall be reduced by the long-
     term disability compensation benefits under such plan for which Executive
     is eligible with respect to the period following termination.

               (ii)  For twelve (12) months following termination, and subject
     to such minimum coverage-continuation requirements as may be required by
     law, the Company will provide (except to the extent that Executive shall
     obtain or be eligible to obtain such insurance from another employer) such
     medical and

                                      -3-
<PAGE>
 
     hospital insurance and term life insurance for Executive and his family,
     comparable to the insurance provided for executives generally, as the
     Company shall determine, and upon the same terms and conditions as the same
     shall be provided for other Company executives generally; provided,
     however, that in no event shall such insurance benefits supplied by the
     Company or the terms and conditions thereof be less favorable to Executive
     than those afforded to him as of the date of termination. To the extent it
     is impossible or impracticable to provide any such benefits to Executive
     under the Company's then existing employee benefit plans or arrangements,
     the Company shall arrange for alternative comparable coverage or, if such
     alternative coverage is not available, shall pay to Executive the cost of
     such coverage, as reasonably determined by the Company.

          (iii)  All of Executive's previously granted stock options ("Options")
     then outstanding, to the extent not already vested, shall be immediately
     vested and shall remain exercisable for a period of one year or, if less,
     the remainder of the original option term, and shall then terminate.

          (iv)  It is agreed and understood that all payments and benefits
     provided to Executive hereunder shall be expressly conditioned on the
     execution by Executive or his legal representative of a general release and
     waiver of claims in favor of the Company and its directors, officers,
     affiliates, and representatives.

     b.   Voluntary Termination of Employment.  If Executive terminates his
          -----------------------------------                              
employment voluntarily (other than a Constructive Termination), Executive or his
legal representative shall not be entitled to any severance or other benefits
under this Agreement.

     c.   Termination for Cause.  If the Company should terminate Executive's
          ---------------------                                              
employment for Cause, Executive or his legal representative shall not be
entitled to any severance or other benefits under this Agreement, all Options
shall immediately terminate and the Company shall not waive any rights it may
have for damages or for injunctive relief.  "Cause" shall mean dishonesty by
Executive in the performance of his duties, conviction of a felony (other than a
conviction arising solely under a statutory provision imposing criminal
liability upon Executive on a per se basis due to the Company offices held by
Executive, so long as any act or omission of Executive with respect to such
matter was not taken or omitted in contravention of any applicable policy or
directive of the Board), gross neglect of duties (other than as a result of
Disability, Incapacity or death)  rising to the level of deliberate dereliction,
conflict of interest, which conflict shall continue for 30 days after the
Company gives written notice to Executive requesting the cessation of such
conflict, or material breach by Executive of any of the restrictive covenants
contained in Sections 6(a) and 6(b) hereof.

                                      -4-
<PAGE>
 
6.   AGREEMENT NOT TO SOLICIT OR COMPETE; CONFIDENTIALITY.
     ---------------------------------------------------- 

     a.   Nonsolicitation.  For a period of one year after the termination of
          ---------------                                                    
his employment, Executive shall not under any circumstances employ, solicit the
employment of, accept unsolicited the services of or assist any other entity in
employing or soliciting the employment of, any Protected Person (as defined
below), recommend the employment of any Protected Person to any other business
or encourage any Protected Person to terminate his or her employment
relationship with the Company.  A "Protected Person" shall mean any person who
was employed by the Company or its subsidiaries prior to the termination of
Executive's employment and is, or during the three months prior to the
commencement of conversations with Executive with respect to employment was,
employed by the Company or its subsidiaries.

     b.   Noncompetition.  During the course of his employment, Executive will
          --------------                                                      
learn trade secrets of the Company and will have access to Confidential
Information (as hereinafter defined) and business plans of the Company.
Therefore, (i) during the Employment Period, (ii) upon automatic termination of
the Employment Period on December 31, 2000, if Executive should terminate his
employment voluntarily at any time, or if Executive's employment is terminated
for Disability or Incapacity, then for a period of one year after the
termination of his employment, or Executive will not, directly or indirectly,
engage in, become associated in any manner with, lend his name to or have any
financial interest in any Competitive Business (as defined below) anywhere in
the world, whether as a contractor, consultant, agent, partner, principal,
investor, employee, owner, manager or otherwise.  Without limiting the
generality of the foregoing, Executive agrees during such period that he shall
not, directly or indirectly, solicit or encourage any customer or vendor of the
Company to terminate or diminish its relationship with the Company or to conduct
with himself or with any other person, organization or other entity any business
or activity which such customer or vendor conducts or could conduct with the
Company.  "Competitive Business" shall mean any line of business in which the
Company is at the time engaged or for which the management or the Board of
Directors of the Company is at the time actively planning to become engaged.
Nothing herein shall prevent Executive from owning not in excess of one percent
of any security issued and outstanding listed on a national securities exchange
or traded on the Nasdaq National Market.  It is agreed and understood that the
post-employment Noncompetition period prescribed herein shall be tolled, and
shall not run, during any period of time in which Executive is in breach of the
provisions of this Section 6(b).

                                      -5-
<PAGE>
 
     c.   Confidentiality.  Executive acknowledges that during his employment,
          ---------------                                                     
he may develop Confidential Information for the Company and may learn
Confidential Information developed or owned by the Company or entrusted to it by
others.  Executive agrees that he will not, during the term of this Agreement or
at any time thereafter, other than as required in furthering the best interests
of the Company, use or disclose any Confidential Information.  "Confidential
Information" means any and all information of the Company that is not generally
available to the public.  Confidential Information includes but is not limited
to (i) the Company's development, research and marketing activities, (ii) the
Company's products and services, (iii) the Company's costs, sources of supply
and strategic plans, (iv) the identity and requirements of  the Company's
customers, prices charged and services provided and (v) the people and
organizations with whom the Company has business relationships and those
relationships.  Confidential Information also includes such information as the
Company may receive or has received belonging to customers or others who do
business with it, but shall not include information which is either generally
known to the public and/or is required to be disclosed publicly by operation of
law or regulation.

     d.   Return of Confidential Information.  All Confidential Information
          ----------------------------------                               
created by Executive or to which Executive has access and all documents, records
and files, in any media of whatever kind and description, relating to the
business, present or otherwise, of the Company or containing, based on or
reflecting Confidential Information (the "Documents"), whether or not prepared
by Executive, shall be the sole and exclusive property of the Company.
Executive shall return to the Company immediately after the termination of this
Agreement, and at such other times as may be specified by the Company, all
Documents and all other property of the Company then in his possession or
control.

                                      -6-
<PAGE>
 
7.   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 laws of any jurisdiction where this
Agreement may be subject to review and interpretation, and in the event that any
restriction shall be determined by any court of competent jurisdiction to be
unenforceable by reason of its being extended over too great a time, too large a
geographic area or too great a range of activities, 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.

8.   REMEDIES.   Executive acknowledges that he has carefully read and
     --------                                                         
considered all the terms and conditions of this Agreement, including the
restraints imposed upon him pursuant to Section 6 hereof.  Executive agrees that
said restraints are necessary for the reasonable and proper protection of the
Company and that each and every one of the restraints is reasonable in respect
to its core subject matter, length of time and geographic area.  Executive
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 that, were he to breach any of the covenants contained in
Section 6 hereof, the damage to the Company would be irreparable.  The Executive
therefore agrees that the Company, in addition to any other remedies available
to it, shall be entitled to preliminary and permanent injunctive relief against
any breach or threatened breach by the Executive of any of said covenants,
without having to post bond, and shall be further entitled to recover from
Executive its reasonable attorney's fees and expenses incurred in connection
with the enforcement of its rights hereunder should the Company prevail.

                                      -7-
<PAGE>
 
9.   ASSIGNMENT.  The rights and obligations of the Company shall inure to the
     ----------                                                               
benefit of and shall be binding upon the successors and assigns of the Company.
The rights and obligations of Executive are not assignable except only that
payments payable to him after his death shall be made by devise or descent.

10.  NOTICES.  All notices and other communications required hereunder shall be
     -------                                                                   
in writing and shall be given by mailing the same by certified or registered
mail, return receipt requested, postage prepaid.  If sent to the Company, the
same shall be mailed to the Company at 500 108th Avenue, N.E., Suite 2600,
Bellevue, WA 98004, Attention: General Counsel, or other such address as the
Company may hereafter designate by notice to Executive; and if sent to
Executive, the same shall be mailed to Executive c/o the Company at 500 108th
Avenue, N.E., Suite 2600, Bellevue, WA 98004 with a copy to 5700 64/th/ Avenue
NE, Seattle, WA  98105, or such other address as Executive may hereafter
designate by notice to the Company.

11.  WITHHOLDING.  Anything to the contrary notwithstanding, all payments
     -----------                                                         
required to be made by the Company hereunder to Executive shall be subject to
the withholding of such amounts, if any, relating to tax and other payroll
deductions as the Company may reasonably determine it should withhold pursuant
to any applicable law or regulation.

12.  GOVERNING LAW.  This Agreement and the rights and obligations of the
     -------------                                                       
parties hereunder shall be governed by the laws of the State of Washington.

13.  CONFLICTING AGREEMENTS.  Executive hereby represents and warrants that the
     ----------------------                                                    
execution of this Agreement and the performance of his obligations hereunder
will not breach or be in conflict with any other agreement to which Executive is
a party or is bound and that the Executive is not now subject to any covenants
against competition or similar covenants that would affect the performance of
his obligations hereunder.  Executive will not disclose to or use on behalf of
the Company any proprietary information of a third party without such party's
consent.

14.  SEVERABILITY.  If any portion or provision of this Agreement shall to any
     ------------                                                             
extent be declared illegal or unenforceable by a court of competent
jurisdiction, then the remainder of this Agreement, or the application of such
portion or provision in circumstances other than those as to which it is so
declared illegal or unenforceable, shall not be affected thereby, and each
portion and provision of this Agreement shall be valid and enforceable to the
fullest extent permitted by law.  The parties agree to substitute a provision
that effects the intent of the invalidated provision as nearly as possible.

                                      -8-
<PAGE>
 
15.  WAIVER; AMENDMENT.  No waiver of any provision hereof shall be effective
     -----------------                                                       
unless made in writing and signed by the waiving party.  The failure of either
party to require the performance of any term or obligation of this Agreement, or
the waiver by either party of any breach of this Agreement, shall not prevent
any subsequent enforcement of such term or obligation or be deemed a waiver of
any subsequent breach.  This Agreement may be amended or modified only by a
written instrument signed by the Executive and by a duly or authorized
representative of the Company.

16.  HEADINGS; COUNTERPARTS.  The headings and captions in this Agreement are
     ----------------------                                                  
for convenience only and in no way define or describe the scope or content of
any provision of this Agreement.
 

                                      -9-
<PAGE>
 
17.  ENTIRE AGREEMENT.  This Agreement represents the entire agreement between
     ----------------                                                         
the parties relating to the terms of Executive's employment by the Company and
supersedes all prior written or oral agreements between them.



                         -------------------------------------
                           Robert S. McCambridge



                         ADVANCED RADIO TELECOM CORP.



                         By:
                            ----------------------------------
                              Henry C. Hirsch
                              Chairman, CEO & President

                                      -10-

<PAGE>
 
                                                                   EXHIBIT 10.10

                         ADVANCED RADIO TELECOM CORP.
               Amended and Restated Change of Control Agreement
               ------------------------------------------------

     AGREEMENT, made this 3rd day of February, 1999 by and between Robert S.
McCambridge ("Executive") and ADVANCED RADIO TELECOM CORP. (the "Company");

RECITALS:

    A.    The Board of Directors of the Company (the "Board") recognizes that
the possibility of a change in control may exist and that such possibility, and
the uncertainty and questions which it may raise among management personnel, may
result in the departure or distraction of management personnel to the detriment
of the Company and its stockholders;

    B.    The Board has determined that appropriate steps should be taken to
reinforce and encourage the continued attention and dedication of members of the
Company's management, including Executive, to their duties, to assisting the
Board in assessing proposals with respect to a change in control and to advising
the Board as to the best interests of the Company and its shareholders with
respect to such potential change in control, without distraction and conflict
arising from the possibility of a change in control;

    C.    The Board wishes to induce Executive to remain in the employ of the
Company and to assure him of fair severance should his employment terminate in
specified circumstances following a change of control of the Company.

    NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the parties hereto agree as follows:

    1.    If within 24 months following a Change of Control (as defined in
Exhibit A) (the "Post Change of Control Period") Executive's employment with the
Company is terminated (i) by the Company for any reason (other than for "Cause"
or "Disability" (as defined paragraph 4 below) or as a result of Executive's
death), or (ii) Executive terminates such employment for Good Reason (as defined
in paragraph 4 below):

        (a) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the sum of (i) Executive's annual base salary ("Base Salary") at
            the time of termination through the date of such termination of
            employment to the extent not theretofore paid, (ii) a prorated
            portion of Executive's maximum incentive compensation for the fiscal
            year in which such termination shall occur, calculated by
            multiplying (A) such incentive compensation times (B) a fraction,
            the numerator of which is the number of days in the fiscal year
            through the date of termination of employment, and the 
<PAGE>
 
            denominator of which is 365, (iii) if Executive has not been paid
            incentive compensation with respect to the fiscal year prior to the
            year in which such termination occurs and during which Executive was
            employed by the Company (except where prior to the Change of Control
            the Board had determined that no such incentive compensation was to
            be paid to Executive with respect to such prior year), Executive's
            maximum incentive bonus for such prior fiscal year prorated for the
            period of his employment by the Company if less than a full year
            (provided that if any target incentive compensation under (ii) or
            (iii) was expressed in shares of common stock rather than cash, the
            Company will pay the cash equivalent of such compensation based on
            the closing price per share as reported in the Wall Street Journal
            (Eastern Edition), in the case of the Company's common stock as of
            the date prior to the date of the Change of Control), and (iv) any
            accrued and unpaid vacation pay through the date of termination; and

        (b) Any stock, stock option or other awards granted to Executive by the
            Company shall immediately vest and, if applicable, become
            exercisable in full, notwithstanding any provision to the contrary,
            and shall remain exercisable, if applicable, until the earlier of
            the fourth anniversary of such termination of employment or the
            latest date on which such grant could have been exercised, any
            restrictions on any restricted stock, deferred stock or other awards
            shall immediately terminate and all such awards shall immediately be
            vested in full, and any certificates for any deferred stock shall be
            delivered to Executive no later than five business days following
            such termination;

        (c) The Company will pay to Executive within five business days of such
            termination of employment a lump-sum cash payment in an amount equal
            to the greater of (i) an amount equal to Executive's aggregate Base
            Salary and maximum incentive compensation for the period from the
            date of termination through December 31, 2000 determined as if he
            had been employed through December 31, 2000 (but without duplication
            of amounts paid pursuant to Section 1(a) above) or (ii) an amount
            equal to:  (A) the amount of Executive's Base Salary at the rate in
            effect immediately prior to the date of termination or at the rate
            in effect immediately prior to the Change of Control, whichever is
            higher, and (B) the amount of Executive's maximum incentive
            compensation for the fiscal year during which the termination of
            employment occurs or the amount of Executive's maximum incentive
            compensation in effect immediately prior to the Change of Control,
            whichever is higher (provided that if any such incentive
            compensation is expressed or was paid in shares of common stock
            rather than cash, the calculation will be based on, and the Company
            will pay the cash equivalent of, such compensation based on the
            closing price per share as reported in the Wall Street Journal
            (Eastern Edition) in the case of a share of the Company's common
            stock determined on the date prior to the date of the Change of
            Control.

                                      -2-
<PAGE>
 
        (d) Executive, together with his dependents, will continue following
            such termination of employment to participate fully in the life and
            medical insurance plans maintained or sponsored by the Company
            immediately prior to the Change of Control on the same basis they
            participated prior to the Change in Control until the earlier of (i)
            the second anniversary of such termination or any longer period as
            may be provided by the terms of such plan or (ii) the date Executive
            becomes re-employed with another employer and is eligible to receive
            substantially equivalent life and medical benefits under another
            employer provided plan, provided that if the continued participation
            of Executive and his dependents is not possible under the terms of
            any of such Company plans, the Company shall instead either arrange
            to provide Executive and his dependents with substantially
            equivalent benefits or pay to Executive (within five days of the
            date of termination) an amount equal to the full value thereof in
            cash; and

        (e) the Company will promptly reimburse Executive for any and all legal
            fees and expenses (including, without limitation, stenographer fees
            and printing costs) incurred by him as a result of such termination
            of employment, including without limitation all fees and expenses
            incurred to enforce the provisions of this Agreement or contest or
            dispute that the termination of his employment is for Cause or other
            than for Good Reason (regardless of the outcome thereof).

     Notwithstanding anything herein to the contrary, (i) to the extent that any
payment or benefit provided for herein is required to be paid or vested on any
earlier date under the terms of any plan, agreement or arrangement, such plan,
agreement or arrangement shall control; and (ii) if the Company terminates
Executive's employment for a reason other than Cause prior to the date upon
which the Change of Control occurs, and Executive reasonably demonstrates that
such termination of employment (x) was at the request of a third party who has
taken steps reasonably calculated to effect a Change of Control or (y) otherwise
arose in connection with or in anticipation of a Change of Control, then for all
purposes of this Agreement, Executive shall be entitled to the benefits provides
in Section 1 above.

     To avert duplication of benefits, if Executive receives any payment of Base
Salary, incentive compensation or severance other than under this Agreement
("Other Termination Payments") upon the termination of his employment with the
Company, the amount of such payments shall be deducted from the amount paid
under this Agreement and the benefits to be provided hereunder shall be provided
only to the extent additional to the benefits to be provided other than under
this Agreement; provided, however, that neither this paragraph nor the
provisions of any other agreement shall be interpreted to reduce the amount
payable to Executive below the amount that would otherwise have been payable
under this Agreement if such Other Termination Payments had not been made.

                                      -3-
<PAGE>
 
     2.   Death, Disability, Cause, Other Than For Good Reason


          (a)  If Executive's employment shall terminate during the Post Change
               of Control Period by reason of Executive's death, this Agreement
               shall terminate without further obligations to Executive's legal
               representatives under this Agreement.

          (b)  If Executive's employment is terminated during the Post Change of
               Control Period by reason of Executive's Disability, this
               Agreement shall terminate without further obligations to
               Executive.  For purposes of this Agreement, "Disability" shall
               have the meaning given in the Company's long-term disability plan
               defining the date and conditions for which Executive is entitled
               to receive long-term disability compensation pursuant to such
               long-term disability plan. If the Company determines in good
               faith that the Disability of Executive has occurred during the
               Post Change of Control Period, it may give Executive written
               notice of its intention to terminate Executive's employment.  In
               such event, Executive's employment with the Company shall
               terminate effective on the 30th day after receipt of such notice
               by Executive, provided that, within the 30 days of such receipt,
               Executive shall not have returned to full-time performance of
               Executive's duties.

          (c)  If Executive's employment shall be terminated for Cause (as
               defined in Section 4 below) during the Post Change of Control
               Period, this Agreement shall terminate without further
               obligations to Executive other than the obligation to pay
               Executive (A) his Base Salary through the date of termination and
               (B) Other Benefits, in each case to the extent theretofore
               unpaid.

          (d)  If Executive voluntarily terminates employment during the Post
               Change of Control Period, excluding a termination for Good
               Reason, this Agreement shall terminate without further
               obligations to Executive.


     3.   "Cause" means only: (a) commission of a felony or gross neglect of
duty by Executive rising to the level of deliberate dereliction, (b) conviction
of a crime involving moral turpitude, or (c) willful failure by Executive in the
performance of his duties to the Company which failure is deliberate on
Executive's part, results in material injury to the Company, and continues for
more than 30 days after written notice given to Executive pursuant to a two-
thirds vote of all of the members of the Board at a meeting called and held for
such purpose (after reasonable notice to Executive) and at which meeting
Executive and his counsel were given an opportunity to be heard, such vote to
set forth in reasonable detail the nature of the failure.  For purposes of this
definition of Cause, no act or omission shall be considered to have been
"willful" unless it was not in good faith and Executive had knowledge at the
time that the act or omission was not in the best interest of the Company.  Any
act or failure to act based on authority given 

                                      -4-
<PAGE>
 
pursuant to a resolution duly adopted by the Board or based on the advice of
counsel of the Company shall be conclusively presumed to be done, or omitted to
be done, by Executive in good faith and in the best interest of the Company.
Cause shall not include willful failure due to incapacity resulting from
physical or mental illness or any actual or anticipated failure after Notice of
Termination for Good Reason.

     4.   Executive shall be deemed to have voluntarily terminated his
employment for Good Reason if Executive leaves the employ of the Company for any
reason following:

          (a)  The assignment to Executive of any duties inconsistent in any
               respect with Executive's position (including status, offices,
               titles and reporting requirements), authority, duties or
               responsibilities immediately prior to the Change of Control; or
               the diminution or adverse alteration in any material adverse
               respect of such position, authority, duties or responsibilities,
               excluding for this purpose an isolated, insubstantial and
               inadvertent action not taken in bad faith and which is remedied
               by the Company promptly after receipt of notice thereof given by
               Executive;

          (b)  Any reduction in Executive's rate of Base Salary for any fiscal
               year to less than 100% of the rate of Base Salary payable for the
               fiscal year immediately preceding the Change of Control or of the
               Base Salary provided for such fiscal year in any agreement
               between Executive and the Company, or reduction in Executive's
               total cash and stock compensation opportunities, including Base
               Salary and incentives, for any fiscal year to less than 100% of
               the total cash and stock compensation opportunities made
               available to him immediately preceding the Change of Control for
               the then current fiscal year or of the total cash and stock
               compensation opportunities which were to be made available to him
               for the fiscal year pursuant to any agreement between Executive
               and the Company  (for this purpose, such opportunities shall be
               deemed reduced if the objective standards by which Executive's
               incentive compensation measured becomes more stringent, the
               target or maximum amounts of such incentive compensation are
               reduced, or the amount of such incentive compensation is reduced
               on a discretionary basis from the amount that would be payable
               solely by reference to the objectives); or

          (c)  Failure of the Company to continue in effect any retirement,
               life, medical, dental, disability accidental death or travel
               insurance plan or other benefit plan or practice, in which
               Executive was participating immediately prior to the Change of
               Control unless the Company provides Executive with a plan or
               plans or practices that provide substantially similar benefits,
               or the taking of any action by the Company that would adversely
               affect Executive's participation in or materially reduce
               Executive's benefits under any of such 

                                      -5-
<PAGE>
 
               plans or practices or deprive Executive of any material fringe
               benefit enjoyed by Executive immediately prior to the Change of
               Control other than an isolated, insubstantial and inadvertent
               failure not occurring in bad faith and which is remedied by the
               Company promptly after receipt of notice thereof given by
               Executive; or

          (d)  The Company requires Executive to be based at any office or
               location further than 40 miles from the City of Bellevue, or the
               Company requires Executive to travel on Company business to a
               substantially greater extent than required immediately prior to
               the date of the Change of Control; or

          (e)  Any failure by the Company to comply with and satisfy Section 6
               of this Agreement.

     Executive's right to terminate his employment pursuant to this section
shall not be affected by his incapacity due to physical or mental illness.
Executive's continued employment shall not constitute consent to, or a waiver of
rights with respect to, any circumstances constituting Good Reason hereunder.

     5.   In the case of any dispute under this Agreement, Executive may
initiate binding arbitration in Seattle, Washington before the American
Arbitration Association by serving a notice to arbitrate upon the Company or, at
Executive's election, institute judicial proceedings.  The Company shall not
have the right to initiate binding arbitration, and agrees that upon the
initiation of binding arbitration by Executive pursuant to this paragraph 5 the
Company shall cause to be dismissed any judicial proceedings it has brought
against Executive relating to this Agreement.  The Company authorizes Executive
from time to time to retain counsel of his choice to represent Executive in
connection with any and all actions, proceedings, and/or arbitration, whether by
or against the Company or any director, officer, shareholder, or other person
affiliated with the Company, which may affect Executive's rights under this
Agreement.  Company agrees to (i) pay the fees and expenses of such counsel,
(ii) to pay the cost of such arbitration and/or judicial proceeding, and (iii)
pay interest to Executive on all amounts owed to Executive under this Agreement
during any period of time that such amounts are withheld pending arbitration
and/or judicial proceedings.  Such interest will be at the base rate as
announced from time to time by Canadian Imperial Bank of Commerce.

     In addition, notwithstanding any existing or prior attorney-client
relationship between the Company and counsel retained by Executive, the Company
irrevocably consents to Executive entering into an attorney-client relationship
with such counsel and agrees that a confidential relationship shall exist
between Executive and such counsel.

     6.   If the Company is at any time before or after a Change of Control
merged or consolidated into or with any other corporation or other entity
(whether or not the Company is the surviving entity), or if substantially all of
the assets thereof are transferred to another corporation 

                                      -6-
<PAGE>
 
or other entity, the provisions of this Agreement will be binding upon and inure
to the benefit of the corporation or other entity resulting from such merger or
consolidation or the acquirer of such assets (the "Successor Entity"), and this
paragraph 6 will apply in the event of any subsequent merger or consolidation or
transfer of assets. The Company will require any such Successor Entity to assume
expressly and agree to perform this Agreement in the same manner and to the same
extent that the Company would be required to perform if no such transaction had
taken place. As used in this Agreement, "Company" shall mean the Company as
hereinbefore defined and any Successor Entity which assumes and agrees to
perform this Agreement by operation of law or otherwise.

     In the event of any merger, consolidation, or sale of assets described
above, nothing contained in this Agreement will detract from or otherwise limit
Executive's right to or privilege of participation in any stock option or
purchase plan or any bonus, profit sharing, pension, group insurance,
hospitalization, or other incentive or benefit plan or arrangement which may be
or become applicable to executives of the corporation resulting from such merger
or consolidation or the corporation acquiring such assets of the Company.

     In the event of any merger, consolidation, or sale of assets described
above, references to the Company in this Agreement shall unless the context
suggests otherwise be deemed to include the entity resulting from such merger or
consolidation or the acquiror of such assets of the Company.

     7.   Any termination by the Company for Cause, or by Executive for Good
Reason, shall be communicated by Notice of Termination to the other party hereto
given in accordance with the last paragraph of Section 12 of this Agreement.
For purposes of this Agreement, a "Notice of Termination" means a written notice
that (i) indicates the specific termination provision in this Agreement relied
upon, (ii) to the extent applicable, sets forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of Executive's
employment under the provision so indicated and (iii) if the Date of Termination
(as defined below) is other than the date of receipt of such notice, specifies
the termination date (which date shall be not more than thirty days after the
giving of such notice).  The failure by Executive or the Company to set forth in
the Notice of Termination any fact or circumstance which contributes to a
showing of Good Reason or Cause shall not waive any right of Executive or the
Company, respectively, hereunder or preclude Executive or the Company,
respectively, from asserting such fact or circumstance in enforcing Executive's
or the Company's rights hereunder.

     "Date of Termination" means (i) if Executive's employment is terminated by
the Company for Cause, or by Executive for Good Reason, the date of receipt of
the Notice of Termination or any later date specified therein, as the case may
be, (ii) if Executive's employment is terminated by the Company other than for
Cause or Disability, the Date of Termination shall be the date on which the
Company notifies Executive of such termination and (iii) if Executive's
employment is terminated by reason of death or Disability, the Date of
Termination shall be the date of death of Executive or the effective date of the
Disability, as the case may be.

                                      -7-
<PAGE>
 
     8.   All payments required to be made by the Company hereunder to Executive
or his dependents, beneficiaries, or estate will be subject to the withholding
of such amounts relating to tax and/or other payroll deductions as may be
required by law.

     In the event that it is determined that any payment or benefit provided by
the Company to or for the benefit of Executive, either under this Agreement or
otherwise, will be subject to the excise tax imposed by Section 4999 of the
Internal Revenue Code or any successor provision(s) ("Section 4999"), the
Company will, prior to the date on which any amount of the excise tax must be
paid or withheld, make an additional lump-sum payment (the "Gross-up Payment")
to Executive in an amount sufficient, after giving effect to all federal, state
and other taxes and charges (including interest and penalties, if any) with
respect to the gross-up payment, to make Executive whole for all taxes
(including withholding taxes) and any associated interest and penalties, imposed
under or as a result of Section 4999.

     Determinations under this Section 8 will be made by Coopers & Lybrand
unless Executive has reasonable objections to the use of that firm, in which
case the determinations will be made by a comparable firm chosen by Executive
after consultation with the Company (the firm making the determinations to be
referred to as the "Firm").  The determinations of the Firm will be binding upon
the Company and Executive except as the determinations are established in
resolution (including by settlement) of a controversy with the Internal Revenue
Service to have been incorrect.  All fees and expenses of the Firm will be paid
by the Company.

     If the Internal Revenue Service asserts a claim that, if successful, would
require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service.  The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy.  The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

     9.   There shall be no requirement on the part of Executive to seek other
employment or otherwise mitigate damages in order to be entitled to the full
amount of any payments and benefits to which Executive is entitled under this
Agreement, and the amount of such payments and benefits shall not be reduced by
any compensation or benefits received by Executive from other employment other
than with respect to certain welfare benefits as provided in the first proviso
to Section 1(d).

                                      -8-
<PAGE>
 
     10.  Nothing contained in this Agreement shall be construed as a contract
of employment between Company and Executive, or as a right of Executive to
continue in the employ of Company, or as a limitation of the right of Company to
discharge Executive with or without Cause; provided that Executive shall have
the right to receive upon termination of his employment the payments and
benefits provided in this Agreement and shall not be deemed to have waived any
rights he may have either at law or in equity in respect of such discharge.

     11.  No amendment, change, or modification of this Agreement may be made
except in writing, signed by both parties.  This agreement amends and restates
in its entirety the Change of Control Agreement between the parties, dated
October 16, 1998.

     12.  This Agreement shall terminate on December 31, 2000, provided,
however, that commencing on December 31, 1999 and on each annual anniversary of
such date (each such date hereinafter referred to as a "Renewal Date"), unless
previously terminated, the term of this Agreement shall be automatically
extended so as to terminate three years from such Renewal Date, unless at least
sixty days prior to the Renewal Date the Company shall give notice to Executive
that the term of this Agreement shall not be so extended.  This Agreement shall
not apply to a Change of Control which takes place after the termination of this
Agreement.
 
     The provisions of this Agreement shall be binding upon and shall inure to
the benefit of Executive, his executors, administrators, legal representatives
and assigns, and the Company and its successors.

     The validity, interpretation, and effect of this Agreement shall be
governed by the laws of the State of Washington.  Any ambiguities in this
Agreement shall be construed in favor of Executive.

     The invalidity or unenforceability of any provisions of this Agreement
shall not affect the validity or enforceability of any other provision of this
Agreement, which shall remain in full force and effect.

     The Company shall have no right of set-off or counterclaims, in respect of
any claim, debt, or obligation, against any payments to Executive, his
dependents, beneficiaries, or estate provided for in this Agreement.

     No right or interest to or in any payments shall be assignable by
Executive; provided, however, that this provision shall not preclude him from
           --------                                                          
designating one or more beneficiaries to receive any amount that may be payable
after his death and shall not preclude the legal representative of his estate
from assigning any right hereunder to the person or persons entitled thereto
under his will or, in the case of intestacy, to the person or persons entitled
thereto under the laws of intestacy applicable to his estate.  The term
"beneficiaries" as used in this Agreement shall mean a beneficiary or
beneficiaries so designated to receive any such amount, or if no beneficiary has
been so designated, the legal representative of Executive's estate.

                                      -9-
<PAGE>
 
     No right, benefit, or interest hereunder, shall be subject to anticipation,
alienation, sale, assignment, encumbrance, charge, pledge, hypothecation or set-
off in respect of any claim, debt or obligation, or to execution, attachment,
levy or similar process, or assignment by operation of law. Any attempt,
voluntary or involuntary, to effect any action specified in the immediately
preceding sentence shall, to the full extent permitted by law, be null, void,
and of no effect.

     All notices and other communications hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

       If to Executive:  Robert S. McCambridge
       ---------------   5700 64/th/ Avenue N.E.
                         Seattle, WA 98105

       If to the Company:  Advanced Radio Telecom Corp.
       -----------------   500 108th Avenue, N.E.
                           Suite 2600
                           Bellevue, WA 98004
                           Attention: General Counsel

or to such other address as either party shall have furnished to the other in
writing in accordance herewith.  Notice and communications shall be effective
when actually received by the addressee.

     IN WITNESS WHEREOF, the Company and Executive have each caused this
Agreement to be duly executed and delivered as of the date set forth above.

                                 ADVANCED RADIO TELECOM CORP.


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


                                    ------------------------------
                                    Robert S. McCambridge

                                      -10-
<PAGE>
 
                                   EXHIBIT A

       Change of Control.  For the purposes of this Agreement, a "Change of
       -----------------                                                   
Control" shall mean:

          (a)  The acquisition by any person, corporation, partnership, limited
               liability company or other entity (a "Person", which term shall
               include a group within the meaning of section 13(d) of the
               Securities Exchange Act of 1934 (the "Exchange Act")) of ultimate
               beneficial ownership (within the meaning of Rule 13d-3
               promulgated under the Exchange Act), directly or indirectly of
               30% or more of either (i) the then outstanding shares of common
               stock of the Company (the "Outstanding Company Common Stock") or
               (ii) the combined voting power of the then outstanding voting
               securities of the Company entitled to vote generally in the
               election of directors (the "Outstanding Company Voting
               Securities"); provided, however, that for purposes of this
               subsection (a), the following acquisitions shall not constitute a
               Change of Control:  (i) any such acquisition directly from the
               Company, except for acquisition of securities upon conversion of
               other securities of the Company (ii) any such acquisition by the
               Company, (iii) any such acquisition by any employee benefit plan
               (or related trust) sponsored or maintained by the Company or any
               corporation controlled by the Company or (iv) any such
               acquisition by any corporation pursuant to a transaction which
               complies with clauses (i), (ii) and (iii) of subsection (c) of
               this Exhibit A; or

          (b)  Individuals who, as of the date hereof, constitute the Board (the
               "Incumbent Board") cease for any reason to constitute at least a
               majority of the Board; provided, however, that any individual
               becoming a director subsequent to the date hereof whose election,
               or nomination for election, by the Company's shareholders, was
               approved by a vote of at least a majority of the directors then
               comprising the Incumbent Board shall be considered as though such
               individual were a member of the Incumbent Board, but excluding,
               for this purpose, any such individual whose initial assumption of
               office occurs as a result of an actual or threatened election
               contest with respect to the election or removal of directors or
               other actual or threatened solicitation of proxies or consents by
               or on behalf of a Person other than the Board; or

          (c)  Consummation of a reorganization, merger or consolidation or sale
               or other disposition of all or substantially all of the assets of
               the Company in one or a series of transactions (a "Business
               Combination"), in each case, unless, following such Business
               Combination, (i) all or substantially all of the individuals and
               entities who were the beneficial owners, respectively, of the

                                      -11-
<PAGE>
 
               Outstanding Company Common Stock and Outstanding Company Voting
               Securities immediately prior to such Business Combination
               beneficially own, directly or indirectly, immediately following
               such Business Combination more than 50% of, respectively, the
               outstanding shares of common stock and the combined voting power
               of the then outstanding voting securities entitled to vote
               generally in the election of directors, as the case may be, of
               the corporation resulting from such Business Combination
               (including, without limitation, a corporation which as a result
               of such transaction owns the Company or all or substantially all
               of the Company's assets either directly or through one or more
               subsidiaries) in substantially the same proportions as their
               ownership, immediately prior to such Business Combination of the
               Outstanding Company Common Stock and outstanding Company Voting
               Securities, as the case may be, (ii) no Person (excluding any
               corporation resulting from such Business Combination or any
               employee benefit plan (or related trust) of the Company or such
               corporation resulting from such Business Combination) ultimately
               beneficially owns, directly or indirectly, 30% or more of,
               respectively, the then outstanding shares of common stock of the
               corporation resulting from such Business Combination or the
               combined voting power of the then outstanding voting securities
               of such corporation except to the extent that such ownership
               existed prior to the Business Combination and (iii) at least a
               majority of the members of the board of directors of the
               corporation resulting from such Business Combination were members
               of the Incumbent Board at the time of the execution of the
               initial agreement, or of the action of the Board, providing for
               such Business Combination; or

          (d)  Approval by the shareholders of the Company of a complete
               liquidation or dissolution of the Company.

                                      -12-

<PAGE>
 
                                                                      EXHIBIT 21

                  Subsidiaries of Advanced Radio Telecom Corp.
                  --------------------------------------------
<TABLE>
<CAPTION>
 
 
Name                                          Jurisdiction  Percent Ownership
- ----                                          ------------  ------------------
<S>                                           <C>           <C>
 
ART Leasing, Inc.                             Delaware             100%
                                                             
ART Licensing Corp.                           Delaware             100%
                                                             
DCT Communications, Inc.                      California           100%
                                                             
Advanced Radio Telecom International, B.V.    Netherlands          100%
                                                             
Advanced Radio Telecom Ltd.                   U.K.                 100%*
                                                             
Advanced Radio Telcom Nordic A.B.             Sweden               100%*
                                                             
ART Italia s.r.l.                             Italy                 95%
                                                             
Advanced Radio Telecom (Ireland) Limited      Ireland              100%**
 
</TABLE>
- ------------
*    Advanced Radio Telecom Ltd. and Advanced Radio Telecom Nordic A.B. are both
     wholly-owned subsidiaries of Advanced Radio Telecom International, B.V.

**   Advanced Radio Telecom (Ireland) Limited is a wholly-owned subsidiary of
     Advanced Radio Telecom Limited.

<PAGE>
 
                                                                      EXHIBIT 23


                      CONSENT OF INDEPENDENT ACCOUNTANTS

     We consent to the incorporation by reference in the registration statements
of Advanced Radio Telecom Corp. on Form S-8 (File No. 333-21875), Form S-4 (File
No. 333-33689), Form S-4 (File No. 333-50083), and Form S-3 (File No. 333-31453)
of our report dated March 29, 1999, on our audits of the consolidated financial
statements of Advanced Radio Telecom Corp. and Subsidiaries as of December 31,
1998 and 1997, and for the three years ended December 31, 1998, which report is
included in this Annual Report on Form 10-K.

PricewaterhouseCoopers LLP

Seattle, Washington
April 14, 1999

<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
       
<S>                             <C>
<PERIOD-TYPE>                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               DEC-31-1998
<CASH>                                      11,864,218
<SECURITIES>                                18,504,263
<RECEIVABLES>                                  125,976
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                            31,207,985
<PP&E>                                      31,852,621
<DEPRECIATION>                               5,026,307
<TOTAL-ASSETS>                             259,345,295
<CURRENT-LIABILITIES>                       34,138,413
<BONDS>                                    107,463,638
                                0
                                          0
<COMMON>                                        26,707
<OTHER-SE>                                  75,952,217
<TOTAL-LIABILITY-AND-EQUITY>               259,345,295
<SALES>                                        840,822
<TOTAL-REVENUES>                               840,822
<CGS>                                                0
<TOTAL-COSTS>                               43,352,746
<OTHER-EXPENSES>                             1,498,877
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                          18,480,117<F1>
<INCOME-PRETAX>                           (62,490,918)
<INCOME-TAX>                                 9,132,237
<INCOME-CONTINUING>                       (53,358,681)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                              (53,358,681)
<EPS-PRIMARY>                                   (2.14)
<EPS-DILUTED>                                   (2.14)
<FN>
<F1>NET OF INTEREST INCOME OF $2,693,257
</FN>
        

</TABLE>

<PAGE>
 
                                                                      EXHIBIT 99

                                  RISK FACTORS

         From time to time the Company has made, and may in the future make,
forward-looking statements, based on its then-current expectations, including
statements made in Securities and Exchange Commission filings, in press releases
and oral statements. These forward-looking statements are made pursuant to the
safe harbor provisions of the Private Securities Litigation Reform Act of 1995.
All forward-looking statements involve risks and uncertainties, and actual
results could differ materially from those expressed or implied in the
forward-looking statements for a variety of reasons. These reasons include, but
are not limited to, factors outlined below. The Company does not undertake to
update or revise its forward-looking statements publicly even if experience or
future changes make it clear that any projected results expressed or implied
therein will not be realized.

         Limited Operations; History of Net Losses. The Company has a limited
operating history. It commenced commercial operations in November 1996 as a
provider of wireless broadband capacity to communications providers on a
wholesale "carriers'-carrier" basis. In March 1998, ART adopted a new business
strategy of providing wireless broadband Internet services to business customers
without fiber connectivity. The Company has generated only nominal revenues from
operations to date, has generated operating and net losses since its inception
and expects to generate significant operating and net losses for at least the
next several years. The Company had net losses of $47.0 million in 1998 and an
accumulated deficit of $142.8 million at the end of 1998.

         In light of the Company's brief operating history and change of
strategy, there is limited data about the Company upon which to evaluate its
future performance. There can be no assurance that the Company will develop a
successful business or achieve or sustain profitability in the future. 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, raise adequate additional capital when required, attract and retain an
adequate customer base, acquire adequate access rights for its network, deploy
and commercialize its network, attract and retain experienced and talented
personnel and establish strategic business relationships.

         Significant Capital Requirements; Need to Refinance Indebtedness; Need
for Additional Financings. The Company will be required to seek significant
additional capital in the second quarter of 1999 to fund its operations and
business plan. The Company has limited financial resources, has incurred
recurring losses from operations since inception and does not expect to generate
significant operating revenues in the near term. The Company's ability to
continue as a going concern at least through December 31, 1999, which includes
funding of its operations and business plan, the repayment of the $25 million
working capital facility and funding of its contractual commitments, is
dependent upon its ability to raise additional financing. The Company has
engaged investment bankers to assist it in obtaining financing and is in
negotiations with potential investors to provide equity financing. However,
there can be no assurance that the Company will be successful in its efforts to
obtain such financing, or, if it obtains such financing, that such financing
will be on acceptable terms. These conditions raise substantial doubt about the
Company's ability to continue as a going concern.

         The Company and Lucent have entered into a credit facility (the
"Working Capital Facility") for Lucent Technologies, Inc. ("Lucent") to provide
the Company with up to $25 million of unsecured revolving loans for working
capital purposes. As of December 31, 1998, the Company had drawn $17.5 million
under the Working Capital Facility and subsequent to December 31, 1998 has drawn
the remaining $7.5. Loans made pursuant to the Working Capital Facility are due
June 30, 1999, unless extended by Lucent to no later than September 17, 1999.
There can be no assurance that Lucent will extend such loans beyond June 30,
1999, or that the Company will be able to obtain debt or equity financing to
refinance such indebtedness, or, if it obtains such financing, that such
financing will be on acceptable terms.

         In addition, the Company currently estimates that it will require in
excess of $1 billion over the next several years for capital expenditures,
working capital and funding operating losses. Failure to access capital on
<PAGE>
 
acceptable terms or delays in obtaining such financing could result in the
modification, delay or abandonment of some or all of the Company's business
plan. Any such modification, delay or abandonment could have a material adverse
effect on the Company.

         The Company has entered into a purchase money credit facility (the
"Purchase Money Facility") with Lucent setting forth terms and conditions under
which Lucent will provide purchase money financing in an aggregate amount of up
to $200 million, to be used to finance the purchase of the Company's data
network from Lucent. Availability of all but $10 million on these loans is
subject to the Company's raising at least $50 million of certain debt or equity
capital and repayment of the $25 million Working Capital Facility. Under the
Purchase Money Facility, Lucent will make available purchase money loans equal
to up to 200% of the aggregate capital raised, not to exceed $200 million. There
can be no assurance that the Company will be able to obtain the financing
contemplated by the Purchase Money Facility.

         Risks Related to Strategy. The Company is pursuing a strategy to become
the leading provider of broadband Internet services to business customers
without fiber connectivity. The Company has limited experience in providing
these services, and there can be no assurance that it will successfully
implement its strategy. The Company has limited experience in deploying,
operating and maintaining a broadband data network. There can be no assurance
that the Company will effectively deploy, operate or maintain such facilities.
Further, there can be no assurance that the broadband data network deployed by
the Company will provide the expected functionality. Furthermore, the Company's
strategy is subject to risks relating to the negotiation and implementation of
necessary strategic business relationships with third parties, the development
of value-added products and services, the ability of Lucent and the Company to
design, provision and deploy the Company's network on schedule, the recruitment
of experienced and talented personnel in a timely manner, the Company's ability
to attract and retain customers, and the Company's ability to manage the rapid
implementation of its plan in multiple markets. In addition, the Company is
subject to the risk or unforseen problems inherent in being a new entrant in a
rapidly evolving industry.

         There is significant risk relating to the market's acceptance of the
Company's wireless broadband Internet services. The Company and other providers
have only recently begun to market fixed wireless services, and the Company
believes it is currently the only fixed wireless broadband provider focusing on
providing Internet services rather than voice telephony. The provision of such
services represents an emerging sector of the telecommunications industry, and
the demand for such services is uncertain. Demand may be adversely affected by
various factors including historical perceptions of the unreliability of
previous wireless technologies, concerns about the security of transmissions
over wireless networks, the lack of market history of operational fixed wireless
services and the possible desire of customers to acquire telecommunications
services from a single provider. The Company anticipates that a substantial
investment in sales and marketing will be required to reach its target customers
and to create demand for the Company's wireless broadband date services. There
can be no assurance that a substantial market will develop for fixed wireless
broadband Internet services, that sufficient customers will be willing to
purchase such services, or if such market were to develop, that the Company will
be able to attract and maintain a sufficient revenue-generating customer base,
generate sufficient cash flow to service its indebtedness, or operate
profitably.

         Furthermore, acceptance of the Company's services may be affected by
various factors beyond the Company's control, including the availability and
pricing of alternative broadband and narrowband Internet services, general and
local economic conditions, changes in products and technology, and the potential
impact of government regulation on the Company's services. The extent of the
potential demand for the Company's broadband wireless Internet services cannot
be estimated with certainty. Insufficient acceptance of the Company's services
due to one or more of these factors or from other factors, would have a negative
impact on the Company's results of operations and its financial condition.

         Substantial Leverage; Ability to Service Indebtedness. The Company is
highly leveraged. The Company expects to incur substantial additional debt to
finance its business plan. Accordingly, (i) a substantial portion of the

                                      -2-
<PAGE>
 
Company's cash flow from operations will be required to pay interest with
respect to its outstanding 14% Senior Notes due 2007 (the "Senior Notes")
commencing in August 2000, with respect to the anticipated Lucent Financing
commencing in June 2003 and with respect to any additional indebtedness incurred
by the Company, (ii) the Company's flexibility may be limited in responding to
changes in the industry and economic conditions generally; (iii) the failure to
comply with the numerous financial and other restrictive covenants of such debt
may result in an event of default, which, if not cured or waived, could have a
material adverse effect on the Company; (iv) the ability of the Company to
satisfy its obligations pursuant to such indebtedness is dependent upon its
future performance which, in turn, is subject to management, financial, business
and other factors affecting the business and operations of the Company; (v) the
Company's ability to obtain any necessary financing in the future may be
limited; (vi) the Company may be more highly leveraged than many of its
competitors, which may put it at a competitive disadvantage; and (vii) the
Company's leverage may make it more vulnerable in the event of an economic
downturn. The Company's ability to make principal and interest payments on its
indebtedness will be dependent upon, among other things, the Company's future
operating performance and anticipated cash flow and its ability to obtain
additional debt or equity financing on acceptable terms, which are themselves
dependent on a number of factors, many of which are out of the Company's
control. These factors include prevailing economic, financial, competitive and
regulatory conditions and other factors affecting the Company's business and
operations including the ability of the Company to implement its network on a
timely and cost effective basis. There can be no assurance that these factors
will not have a material adverse effect on the Company or that the Company will
be able to generate sufficient cash flow to meet required interest and principal
payments associated with its indebtedness. If the Company is unable to generate
sufficient cash flow to meet its debt obligations, the Company may be required
to renegotiate the payment terms or to refinance all or a portion of its
indebtedness, to sell assets or to obtain additional financing. There is no
assurance that the Company would be able to do so. Any failure to meet required
interest and principal payments would materially and adversely affect the
Company's business and results of operations.

         Reliance on Lucent; Lucent Agreements. The Company and Lucent have
entered into an Amended and Restated Purchase Agreement (the "Lucent Purchase
Agreement") under which Lucent will provide a nationwide integrated network and
will deploy its personnel to deploy and maintain ART's network. Pursuant to the
Lucent Agreements, the Company has engaged Lucent to design, engineer, equip,
install, construct, test and service the Company's nationwide network. Any
failure or inability by Lucent to perform these functions could cause delays or
additional costs in providing services to customers and building out the
Company's network in specific markets. Any such failure could materially and
adversely affect the Company's business and results of operations.

         Competition. The industry and markets in which the Company plans to
provide services are highly competitive. The Company competes with other
providers of telecommunications services using a variety of telecommunications
technologies, now existing and under development, including copper, fiber,
cable, mobile and fixed wireless and satellite networks, and the Company expects
to compete with technologies not yet introduced. These other technologies may
offer advantages over the Company's services. In addition, many of the other
wireline and wireless services providers have longer operating histories, longer
standing relationships with customers, and suppliers, greater name recognition,
better geographic footprints and greater financial, technical and marketing
resources than the Company. As a result, these competitors, among other things,
may be able to develop and exploit new technologies, adapt to changes in
customer requirements more quickly, devote greater resources to the marketing
and sale of their services or more rapidly deploy and build-out a network than
the Company.

         While the Company does not believe that any other competitor is
focusing exclusively on offering broadband Internet services to business
customers without fiber connectivity, ART faces significant competition from
other entities and technologies that currently, or could in the future, deliver
data services to ART's potential customers over copper wire, fiber, wireless or
other technologies. These current or potential competitors include local
exchange carriers ("LECs"), fiber and wireless service providers and cable
television operators. The Company's competitors also include providers of
services which are in competition with the Company's product offerings, such as
Internet service providers ("ISPs"). Moreover, the recent and pending auctions
of spectrum capable of supporting comparable services may facilitate the
introduction or expansion of competition from other 

                                      -3-
<PAGE>
 
competitors. In addition, many other companies have filed applications with the
FCC to develop global broadband satellite systems which may be used to provide
broadband voice and data services. There can be no assurance that the Company
will be able to compete effectively with these other technologies and service
providers in any of its markets.

         The Company has only recently begun to introduce its broadband Internet
services and has only recently begun to pursue customers with the goal of
becoming the leading provider of broadband Internet services to businesses
without fiber connectivity. To date, the Company does not have significant
market share in any of the markets in which it is operating. Given the intense
competition in the market for broadband data services, there can be no assurance
that the Company will achieve significant market share in any market.

         Need for Technological Development. Although the Company is initially
deploying its network utilizing fixed wireless point-to-point technology which
has been commercially deployed for a period of time, the Company plans to
utilize point-to-multipoint technology in its networks as soon as it becomes
commercially available. The expected principal advantages of point-to-multipoint
architecture over traditional point-to-point installation include lower costs
per customer installation and higher flexibility in how bandwidth is allocated.
Point-to-multipoint also should make it possible to support many more
subscribers than otherwise would be possible in a point-to-point environment.
This technology has not been deployed on a commercial basis, and it is unclear
whether the technology will perform as expected, integrate as expected with the
Asynchronous Transfer Mode ("ATM") switching gear and other components of the
Company's network, or provide the advantages expected by the Company.
Unanticipated difficulties or delays in deploying point-to-multipoint technology
or failure of point-to-multipoint technology to yield the expected benefits
could adversely affect the Company's network costs, profitability and results of
operations.

         Changes in Technology, Services and Industry Standards. The
telecommunications industry and market for data services has been characterized
by rapid technological advances, changes in end-user requirements, frequent new
service introductions, evolving industry standards and decreases in the cost of
equipment. The Company expects these changes to continue, and believes that its
long-term success will increasingly depend on its ability to offer value-added
broadband Internet services that exploit advanced technologies and anticipate or
adapt to evolving industry standards. The Company believes that to remain
competitive, retain the customer base it establishes and maintain the margins of
the retail market it is pursuing, its integrated package of high-speed,
broadband Internet services must continue to evolve to keep pace with
developments in the market. There can be no assurance that (i) the Company will
be able to arrange to offer the new services required by its customers, (ii) the
Company's services will not be economically or technically outmoded by current
or future technologies with which it may compete, (iii) the Company will have
sufficient resources to develop or acquire new technologies or introduce new
services capable of competing with future technologies or service offerings (iv)
the Company's inventory of equipment will not be rendered obsolete, or (v) the
cost of the Company's equipment and network will decline as rapidly as that of
competitive alternatives. Moreover, there can be no assurance that the Company's
ability to offer the broadband wireless Internet access with which it will
deliver its value-added services will not become technically or economically
outmoded as new equipment, technologies and advances in competing alternatives
become available.

         Fixed Wireless Limitations. The Company's wireless broadband services
require a direct line of sight between two transceivers and are subject to
distance and rain attenuation. In certain markets which experience heavy
rainfall, transmission links must be engineered for shorter distances and
greater power to maintain transmission quality. Such engineering changes may
increase the cost of providing service.

         The Company primarily installs its transceivers and antennas on
rooftops of building and on other tall structures. The Company generally must
secure building access rights, access to conduits and wiring from building
owners, and may require construction, zoning, franchises or other governmental
permits. There can be no assurance that the Company will succeed in obtaining
roof access and other rights necessary to provide wireless broadband 

                                      -4-
<PAGE>
 
services to 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. Moreover, there
may be a limited number of available buildings which provide a clear line of
sight to targeted buildings, and therefore there may be some circumstances where
installation is impracticable or uneconomical. In such cases, the Company may
decide to provide services that are uneconomical in the short term and seek
alternative methods of transmission to provide services on a more economical
basis, or decide not to provide services to potential customers in locations
with such limitations. There can be no assurance that line of sight limitations
will not have a material adverse effect on the Company's future development and
results of operations.

         Importance of Third-Party Relationships. In addition to its
relationship with Lucent, the Company intends to enter into relationships with
third-parties to assist it in providing services, extending its network and
penetrating markets. There can be no assurance that the Company will be able to
enter into such relationships on a time line that is consistent with the
Company's strategy, if at all. Failure to enter into such relationships, the
failure of third parties to perform once such relationships are entered into, or
the loss of third-party relationships once entered into could cause delays in
providing services, limit the Company's reach in marketing its product, increase
costs for the Company to extend its reach and penetrate markets, and/or impede
the Company's ability to offer certain service packages to certain customers.
Such failures could have a material adverse effect on the Company's development
and results of operations.

         Management of Growth. The Company is pursuing a business plan that, if
successfully implemented, will result in rapid growth, expansion of operations
and provision of broadband data services on a widespread basis over the next two
to five years. Rapid expansion of the Company's operations may place a
significant strain on the Company's management financial and other resources. If
this growth is achieved, the Company's success will depend on its ability to
manage this growth effectively, enhance its operational and financial controls
and information systems, and attract, assimilate and retain qualified and key
personnel. In addition, if the Company expands its business, it will require
additional facilities for its growing operation. There can be no assurance that
the Company will successfully implement and maintain such operational and
financial systems or successfully obtain, integrate and utilize the employees
and management, operational and financial resources necessary to manage a
developing and expanding business in the evolving, increasingly competitive
broadband data communications market. Failure to successfully manage expansion
could materially adversely affect the Company's business, financial condition
and results of operations.

         The billing, provisioning, customer service, network management and
other "back office" systems with the functionality that the Company plans to
offer do not currently exist in a form which can be readily adopted by the
Company. Significant development work by the Company or a third-party provider
will be required to develop such systems for the Company. Delays in developing
and implementing such systems may have a negative impact on the Company's
ability to offer the efficiency and functionality expected to be provided by
these systems and accordingly on the implementation of the Company's business
plan.

         Dependence on Key Employees; Need to Attract and Retain Qualified
Personnel. The success of the Company will be dependent, in large part, on its
ability to attract and retain qualified technical, marketing, sales and
management personnel. The loss of the services of key personnel could have a
material adverse effect upon the business, financial condition and results of
operations of the Company. The Company's ability to implement its business plan
will require the addition of a significant number of qualified personnel.
Competition for such personnel is intense, particularly those experienced in
information technology, and there can be no assurance of the Company's ability
to attract and retain additional key employees and retain its current key
employees at a reasonable cost, if at all. The failure to attract and retain
such personnel at reasonable costs could have a material adverse effect on the
business.

         Equipment Failure and Interruption of Service. The Company's operations
will require that its network, including leased fiber-optic connections,
operates on a continuous basis. It is not unusual for networks including

                                      -5-
<PAGE>
 
switching facilities to experience periodic service interruption and equipment
failures. It is therefore possible that the network and facilities utilized by
the Company may from time to time experience service interruptions or equipment
failures, which would adversely affect consumer confidence as well as the
Company's business operations and reputation.

         Government Regulation. The telecommunications services offered by the
Company are subject to regulation by federal, state and local government
agencies. Changes in existing laws and regulations applicable to the provisions
of wireless data services via the Company's licenses or to the regulations
governing competitive or potentially competitive providers, or any failure or
significant delay in obtaining or maintaining any regulatory approvals which may
be required, could have a material adverse effect on the Company.

         Risk of Forfeiture, Non-Renewal and Fluctuation in Value of FCC
Licenses. The Company must comply with FCC rules relating, among other things,
to its licenses. Failure to comply with FCC rules could subject the Company's
licenses to automatic forfeiture or, depending on the violation, to other FCC
sanctions.

         The Company's FCC licenses are due to expire in February of 2001. To
renew its FCC licenses, the Company is required to demonstrate that it is
providing substantial service within the authorized area covered by that
license. There can be no assurance that the Company will be able to make this
showing for any or all of its licenses. In the event that the FCC does not renew
one or more of the licenses, the Company's business and results of operations
could be materially adversely affected.

         Under the FCC's rules, the Company is also subject to certain build-out
requirements. The Company must construct facilities to place each licensed
station in operation within 18 months of the date of grant of the license.
Although, under current FCC regulations, the term "in operation" is not defined
beyond the requirement that the station be capable of providing service, the
industry custom is to establish at least one link between two transceivers in
each licensed market area. Failure to meet the construction deadline results in
the automatic cancellation of the license. In addition, if a station does not
transmit operational traffic (as opposed to test or maintenance signals) for a
consecutive period of twelve months at any time after construction is complete,
or if removal of equipment or facilities renders the station incapable of
providing service, the license is subject to cancellation or forfeiture, absent
a waiver of the FCC's rules.

         The Company's wireless licenses are integral assets of the Company, the
value of which will depend significantly upon the success of the Company's
wireless data services operations and the future direction of the wireless
segment of the telecommunications industry. The value of licenses to provide
wireless services also may be affected by fluctuations in supply and demand for
such licenses and by valuations placed on such licenses in any current or future
auctions of spectrum, such as the FCC's recently-completed auction of spectrum
in the 28 GHz band. In addition, federal and state regulations may limit the
ability of licensees to sell their licenses. Assignment of licenses and changes
of control involving entities holding licenses require prior consent of the FCC
and, in some instances, state and municipal regulatory approval, and are subject
to restrictions and limitations on the identity, background, legal and financial
qualification, among other things, of the assignee or successor. These
regulatory restrictions on transfer of licenses may adversely affect the ability
of the Company to acquire or dispose of further licenses or the value of the
Company's licenses.

         Acquisition of Additional Bandwidth in Selected Areas. The Company
believes the licenses it owns, manages, or has the right to acquire or use are
sufficient to fully implement its business plan. However, the Company may seek
to acquire or manage additional licenses to expand its geographic footprint or
to enhance its ability to provide service to its current target market or
customers it may target in the future. There can be no assurance that the
Company will be able to acquire additional radio spectrum on favorable terms or
at all.

         Foreign Licenses. Entities owned by the Company have obtained licenses
to provide broadband services in certain Western European countries and entities
owned by the Company or in which the Company has substantial 

                                      -6-
<PAGE>
 
interest have applied or may apply for such licenses in various other countries.
There can be no assurance that such licenses will be granted or exploited in any
way.

         Year 2000 Risk. Many existing computer programs use only two digits,
rather than four, to represent a year. Date-sensitive software or hardware
written or developed in this fashion may not be able to distinguish between 1900
and 2000, and programs written in this manner that perform arithmetic
operations, comparisons or sorting of date fields may yield incorrect results
when processing a Year 2000 date. This Year 2000 problem could potentially cause
system failures or miscalculations that could disrupt operations.

         Although the Company has completed a survey of financial and
information technology systems and non-IT systems in the first quarter of 1999
and expects to complete all remediation efforts by the end of the third quarter
1999, there can be no assurance that all Year 2000 problems have been
successfully identified, or that the necessary corrective actions will be
completed in a timely manner. Failure to successfully identify and remediate
such Year 2000 problems in a timely manner could have a material adverse effect
on the Company's results of operations, financial position or cash flow.

         In addition, the Company believes that there is a risk relating to
significant service suppliers' failure to remediate their Year 2000 issues in a
timely manner. The Company relies on third-party suppliers to deliver fiber
telecommunications links, Internet access, network equipment, banking services
and payroll services. Although the Company is communicating with its suppliers
regarding the Year 2000 problem, the Company does not know whether these
suppliers' systems will be Year 2000 compliant in a timely manner. Like most
telecommunications providers, the Company's ability to provide service is
dependent on key suppliers and equipment vendors. If one or more significant
supplier is not Year 2000 compliant, this could have a material adverse effect
on the Company's results of operations, financial position or cash flow.

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