Document:

REGISTRATION RIGHTS AGREEMENT

         REGISTRATION RIGHTS AGREEMENT (this "Agreement"),  dated as of December
7,  2000,  by and  among  Teligent,  Inc.,  a  Delaware  corporation,  with  its
headquarters  located at 8065 Leesburg Pike, Suite 400,  Vienna,  Virginia 22182
(the "Company"),  and the undersigned  (together with its respective  affiliates
and any  assignee or  transferee  of all of its rights  hereunder,  the "Initial
Investor").

         WHEREAS:

         A. In connection with the Common Stock Purchase  Agreement by and among
the parties hereto of even date herewith (the "Purchase Agreement"), the Company
has agreed,  upon the terms and subject to the conditions  contained therein, to
issue  and  sell  to  the  Initial  Investor,  from  time  to  time,  (i)  up to
$250,000,000  of its Class A Common Stock,  par value $0.01 per share (the "Draw
Down  Shares") and (ii)  warrants  (the  "Warrants")  to acquire up to 4,972,370
shares of Class A Common Stock,  par value $0.01 per share (the "Common Stock"),
upon the terms and conditions and subject to the  limitations and conditions set
forth in the Warrants dated December 7, 2000; and

         B. To induce the Initial  Investor to execute and deliver the  Purchase
Agreement,  the Company has agreed to provide certain  registration rights under
the  Securities  Act  of  1933,  as  amended,  and  the  rules  and  regulations
thereunder,  or any similar  successor  statute  (collectively,  the "Securities
Act"), and applicable state securities laws;

         NOW,  THEREFORE,  in  consideration  of the  premises  and  the  mutual
covenants  contained  herein  and other  good and  valuable  consideration,  the
receipt and  sufficiency of which are hereby  acknowledged,  the Company and the
Initial Investor hereby agree as follows:

         1.       DEFINITIONS.

                  a. As used in this  Agreement,  the following terms shall have
         the following meanings:

                            (i) "Investors"  means the Initial  Investor and any
         transferee or assignee who agrees to become bound by the  provisions of
         this Agreement in accordance with Section 9 hereof.

                           (ii)  "register,"  "registered,"  and  "registration"
         refer to a registration effected by preparing and filing a Registration
         Statement or  Statements  in  compliance  with the  Securities  Act and
         pursuant to Rule 415 under the  Securities  Act or any  successor  rule
         providing for offering  securities on a continuous  basis ("Rule 415"),
         and the declaration or ordering of effectiveness  of such  Registration
         Statement by the United States Securities and Exchange  Commission (the
         "SEC").

                          (iii)  "Registrable  Securities"  shall  mean the Draw
         Down Shares, the Warrant Shares (as defined in the Purchase  Agreement)
         and any other shares of capital  stock issued or issuable as a dividend
         on or in exchange for or otherwise with respect to the Draw Down Shares
         and the Warrant  Shares until (i) the  Registration  Statement has been
         declared effective by the SEC and all such shares have been disposed of
         pursuant to the Registration Statement,  (ii) all such shares have been
         sold under circumstances  under which all of the applicable  conditions
         of Rule  144  promulgated  under  the  Securities  Act (or any  similar
         provision  then in force)  ("Rule 144") are met,  (iii) all such shares
         have been  otherwise  transferred  to holders who may trade such shares
         without  restriction  under the  Securities  Act,  and the  Company has
         delivered a new  certificate  or other  evidence of ownership  for such
         securities not bearing a restrictive  legend, (iv) such time as, in the
         opinion of counsel to the Investor, all such shares may be sold without
         any time, volume or manner limitations  pursuant to Rule 144(k) (or any
         similar  provision  then in effect) under the Securities Act or (v) any
         combination of the foregoing relating to all such shares.

                           (iv)   "Registration   Statement(s)"   shall  mean  a
         registration  statement  on  Form  S-3  (if  use of  such  form is then
         available to the Company  pursuant to the rules of the SEC and, if not,
         on such other form  promulgated  by the SEC for which the Company  then
         qualifies and which counsel for the Company shall deem  appropriate and
         which  form  shall  be  available  for the  resale  of the  Registrable
         Securities  to  be  registered   thereunder  in  accordance   with  the
         provisions  of  this  Agreement  and  the  Purchase  Agreement,  and in
         accordance   with  the  intended   method  of   distribution   of  such
         securities),  for the registration of the resale by the Investor of the
         Registrable Securities under the Securities Act.

                  b.  Capitalized  terms used herein and not  otherwise  defined
         herein  shall have the  respective  meanings  set forth in the Purchase
         Agreement.

         2.       REGISTRATION.

                  a. Mandatory Registration.  The Company shall prepare, and, on
or prior to the date (the "Filing Date") which is forty-five (45) days after the
Closing  Date  (as  defined  in the  Purchase  Agreement),  file  with the SEC a
Registration Statement covering the resale of the Registrable Securities,  which
Registration Statement, to the extent allowable under the Securities Act and the
rules and regulations  promulgated  thereunder (including Rule 416), shall state
that such  Registration  Statement  also  covers  such  indeterminate  number of
additional shares of Common Stock as may become issuable (i) with respect to the
Draw Down  Shares and  Warrant  Shares and (ii) upon  exercise  of or  otherwise
pursuant to the Warrants to prevent dilution resulting from stock splits,  stock
dividends  or  similar  transactions.  The  number of  shares  of  Common  Stock
initially included in such Registration  Statement shall be no less than the sum
of (x) the  aggregate  number  of Draw  Down  Shares  issuable  pursuant  to the
Purchase  Agreement  (assuming that  $250,000,000 of Draw Down Shares were to be
issued at a price equal to the VWAP (as defined in the  Purchase  Agreement)  on
the Closing  Date) and (y) one hundred  twenty  percent  (120%) of the aggregate
number of Warrant  Shares that are  issuable  upon the  exercise of or otherwise
pursuant to the  Warrants,  without  regard to any  limitation  on the Company's
ability to effect Draw Downs under the Purchase  Agreement or on the  Investor's
ability to exercise the Warrants.  The Company  acknowledges  that the number of
shares initially included in the Registration  Statement represents a good faith
estimate of the maximum number of shares  issuable under the Purchase  Agreement
and upon  exercise of or otherwise  pursuant to the Warrants.  The  Registration
Statement  (and each  amendment  or  supplement  thereto,  and each  request for
acceleration of  effectiveness  thereof) shall be provided to and subject to the
approval of the Initial  Investor  and its counsel  prior to its filing or other
submission.  The Company shall provide the Initial Investor and its counsel with
a copy of the Registration  Statement and any pre- or  post-effective  amendment
thereto not less than seven (7) business days prior to the intended  filing date
and shall provide copies of any  supplements not less than two (2) business days
prior to the intended filing date.

                  b.  Underwritten  Offering.  If  any  offering  pursuant  to a
Registration  Statement pursuant to Section 2(a) hereof involves an underwritten
offering,  the  Investors  who hold a majority in  interest  of the  Registrable
Securities  subject  to  such  underwritten  offering,  with  the  consent  of a
majority-in-interest of the Initial Investor, shall have the right to select one
legal  counsel  and an  investment  banker or bankers and manager or managers to
administer  the  offering,  which  investment  banker or  bankers  or manager or
managers shall be reasonably  satisfactory to the Company. In the event that any
Investors  elect  not  to  participate  in  such  underwritten   offering,   the
Registration  Statement covering all of the Registrable Securities shall contain
appropriate  plans of  distribution  reasonably  satisfactory  to the  Investors
participating in such  underwritten  offering and the Investors  electing not to
participate in such underwritten  offering (including,  without limitation,  the
ability  of  non-participating  Investors  to sell from time to time at any time
during the effectiveness of such Registration Statement).

                  c.  Payments by the  Company.  The Company  shall use its best
efforts  to  obtain  effectiveness  of the  Registration  Statement  as  soon as
practicable. If (i) after the Registration Statement(s) covering the Registrable
Securities  required to be filed by the Company  pursuant to Section 2(a) hereof
is declared  effective by the SEC,  sales of all of the  Registrable  Securities
cannot be made pursuant to the Registration  Statement, or (ii) the Common Stock
is  not  listed  or  included  for  quotation  on  the  Nasdaq  National  Market
("Nasdaq"),  the Nasdaq SmallCap Market ("Nasdaq SmallCap"),  the New York Stock
Exchange (the "NYSE") or the American Stock Exchange (the "AMEX") after being so
listed or included for  quotation,  then the Company  will make  payments to the
Investors in such amounts and at such times as shall be  determined  pursuant to
this Section 2(c) as partial  relief for the damages to the  Investors by reason
of any such  delay in or  reduction  of their  ability  to sell the  Registrable
Securities (which remedy shall not be exclusive of any other remedies  available
at law or in equity).  The Company  shall pay to the  Investors  in  immediately
available funds an amount equal to one percent (1%) of the aggregate  Investment
Amount  represented  by Draw Down Shares  previously  purchased  by the Investor
pursuant  to the  Purchase  Agreement  for each thirty day period (pro rated for
partial  periods)  during the  Registration  Period (as defined  below) (i) that
sales  of all of the  Registrable  Securities  cannot  be made  pursuant  to the
Registration  Statement  after  the  Registration  Statement  has been  declared
effective (including, without limitation, when sales cannot be made by reason of
the Company's  failure to properly  supplement or amend the prospectus  included
therein in accordance with the terms of this Agreement  (including  Section 3(b)
hereof or otherwise), but excluding any days during an Allowed Delay (as defined
in Section  3(h));  and (ii) that the Common Stock is not listed or included for
quotation on the Nasdaq,  Nasdaq SmallCap,  NYSE or AMEX or that trading thereon
is halted  (clauses (i) and (ii) are each referred to herein as an  "Ineffective
Period").  Such payments  pursuant  hereto shall be made within five (5) Trading
Days after the earliest to occur of (i) the expiration of the Commitment Period,
(ii) the expiration of an Ineffective  Period (or if an Ineffective Period shall
last more than thirty (30)  calendar  days,  the  expiration of each thirty (30)
calendar days of an Ineffective Period).

                  d.  Eligibility  for Form  S-3.  The  Company  represents  and
warrants that it meets the registrant  eligibility and transaction  requirements
for the use of Form S-3 for registration of the sale by the Initial Investor and
any other Investors of the Registrable Securities and the Company shall file all
reports  required to be filed by the Company with the SEC in a timely  manner so
as to maintain such eligibility for the use of Form S-3.

         3.       OBLIGATIONS OF THE COMPANY.

         In connection with the registration of the Registrable Securities,  the
Company shall have the following obligations:

                  a. The Company shall prepare  promptly,  and file with the SEC
as soon as  practicable  after the Closing  Date (but in no event later than the
Filing Date), a Registration Statement with respect to the number of Registrable
Securities  provided in Section  2(a),  and  thereafter  use its best efforts to
cause such Registration  Statement relating to Registrable  Securities to become
effective  as soon as  possible  after such  filing,  and keep the  Registration
Statement  effective  pursuant  to Rule 415 at all times until such date as such
shares  are  no  longer  considered   Registrable  Securities  pursuant  to  the
definition of such term set forth in Section  1(a)(ii) hereof (such period being
referred  to  as  the  "Registration  Period"),   which  Registration  Statement
(including  any  amendments or supplements  thereto and  prospectuses  contained
therein)  shall not contain any untrue  statement of a material  fact or omit to
state a material  fact required to be stated  therein,  or necessary to make the
statements therein not misleading.

                  b.  The  Company  shall  prepare  and  file  with the SEC such
amendments  (including   post-effective   amendments)  and  supplements  to  the
Registration   Statements  and  the  prospectus  used  in  connection  with  the
Registration  Statements as may be necessary to keep the Registration Statements
effective at all times during the Registration  Period, and, during such period,
comply with the provisions of the Securities Act with respect to the disposition
of  all  Registrable  Securities  of the  Company  covered  by the  Registration
Statements  until  such  time as all of such  Registrable  Securities  have been
disposed of in accordance with the intended methods of disposition by the seller
or sellers  thereof as set forth in the  Registration  Statements.  In the event
that on any  Trading Day (as defined in the  Purchase  Agreement)  the number of
shares available under a Registration Statement filed pursuant to this Agreement
is insufficient to cover all of the  Registrable  Securities  issued or issuable
under the Purchase  Agreement and upon exercise of or otherwise  pursuant to the
Warrants,  without giving effect to any limitations on the Company's  ability to
effect Draw Downs under the Purchase  Agreement or on the Investors'  ability to
exercise the Warrants (the "Registration Trigger Date"), the Company shall amend
the Registration  Statement,  or file a new Registration Statement (on the short
form available  therefore,  if  applicable),  or both, so as to cover all of the
Registrable  Securities  so issued or  issuable  (without  giving  effect to any
limitations on Draw Downs under the Purchase  Agreement or on exercise contained
in the Warrants,  as  applicable) as of the  Registration  Trigger Date, in each
case, as soon as practicable,  but in any event within twenty (20) business days
after the  necessity  therefor  arises  (based on the market price of the Common
Stock and other  relevant  factors  on which the  Company  reasonably  elects to
rely). The Company shall use its best efforts to cause such amendment and/or new
Registration  Statement to become effective as soon as practicable following the
filing  thereof,  but in any event within  ninety (90) days of the  Registration
Trigger Date.  The  provisions  of Section 2(c) above shall be  applicable  with
respect to the Company's obligations under this Section 3(b).

                  c. On or  before  each  Draw  Down  Date  (as  defined  in the
Purchase  Agreement),  the  Company  shall  prepare  and  file  with  the  SEC a
supplement to the Registration  Statement,  in form and substance agreed upon by
the  parties,  regarding  the Draw  Down  including  the  Draw  Down  Date,  the
Investment  Amount, the number of shares sold to the Investor in connection with
all  previous  Draw Downs,  if not  previously  disclosed in an SEC Document (as
defined in the Purchase Agreement),  and any additional  information required by
SEC rules and regulations, including Item 507 of Regulation S-K.

                  d.  The  Company  shall   furnish  to  each   Investor   whose
Registrable  Securities are included in a  Registration  Statement and its legal
counsel (i) promptly after the same is prepared and publicly distributed,  filed
with  the  SEC,  or  received  by the  Company,  one  copy of each  Registration
Statement and any amendment thereto, each preliminary  prospectus and prospectus
and each amendment or supplement  thereto,  and, in the case of the Registration
Statement  referred to in Section 2(a),  each letter  written by or on behalf of
the Company to the SEC or the staff of the SEC, and each item of  correspondence
from the SEC or the staff of the SEC, in each case relating to such Registration
Statement (other than any portion of any thereof which contains  information for
which the Company has sought  confidential  treatment),  and (ii) such number of
copies of a prospectus,  including a preliminary prospectus,  and all amendments
and supplements thereto and such other documents as such Investor may reasonably
request in order to facilitate  the  disposition of the  Registrable  Securities
owned by such  Investor.  The Company will  immediately  notify each Investor by
facsimile  of  the   effectiveness  of  each   Registration   Statement  or  any
post-effective  amendment.  The  Company  will  promptly  respond to any and all
comments  received from the SEC, with a view towards  causing each  Registration
Statement or any amendment  thereto to be declared  effective by the SEC as soon
as  practicable  and shall file an  acceleration  request as soon as practicable
following  the  resolution  or clearance of all SEC comments or, if  applicable,
following  notification by the SEC that any such  Registration  Statement or any
amendment thereto will not be subject to review.

                  e. The Company  shall use  reasonable  efforts to (i) register
and qualify the Registrable  Securities  covered by the Registration  Statements
under such other  securities  or "blue  sky" laws of such  jurisdictions  in the
United  States  as  the  Investors  who  hold  a  majority  in  interest  of the
Registrable  Securities being offered reasonably request,  (ii) prepare and file
in those jurisdictions such amendments (including post-effective amendments) and
supplements  to such  registrations  and  qualifications  as may be necessary to
maintain the effectiveness  thereof during the Registration  Period,  (iii) take
such other  actions as may be  necessary  to  maintain  such  registrations  and
qualifications in effect at all times during the Registration  Period,  and (iv)
take all  other  actions  reasonably  necessary  or  advisable  to  qualify  the
Registrable Securities for sale in such jurisdictions;  provided,  however, that
the  Company  shall not be required in  connection  therewith  or as a condition
thereto to (a)  qualify to do business  in any  jurisdiction  where it would not
otherwise be required to qualify but for this Section 3(e),  (b) subject  itself
to general  taxation  in any such  jurisdiction,  (c) file a general  consent to
service of process in any such  jurisdiction,  (d) provide any undertakings that
cause the Company undue expense or burden, or (e) make any change in its charter
or bylaws,  which in each case the Board of Directors of the Company  determines
to be contrary to the best interests of the Company and its stockholders.

                  f. In the event Investors who hold a  majority-in-interest  of
the Registrable  Securities  being offered in the offering (with the approval of
the Initial  Investor) select  underwriters for the offering,  the Company shall
enter into and perform its obligations under an underwriting agreement, in usual
and customary form, including, without limitation, customary indemnification and
contribution obligations, with the underwriters of such offering.

                  g. The Company will immediately  notify each Investor upon the
occurrence  of  any of the  following  events  in  respect  of the  Registration
Statement  or related  prospectus  in  respect of the resale of the  Registrable
Securities:  (i) receipt of any request for additional  information from the SEC
or any other  federal  or state  governmental  authority  during  the  period of
effectiveness of the Registration Statement, the response to which would require
any  amendments  or  supplements  to  the  Registration   Statement  or  related
prospectus;  (ii)  the  issuance  by the  SEC  or any  other  federal  or  state
governmental  authority of any stop order  suspending the  effectiveness  of the
Registration  Statement or the initiation of any  proceedings  for that purpose;
(iii)  receipt  of  any  notification  with  respect  to the  suspension  of the
qualification or exemption from  qualification of any of the Securities for sale
in any  jurisdiction or the initiation or threatening of any proceeding for such
purpose;  and (iv) the happening of any event that makes any  statement  made in
the Registration Statement or related prospectus or any document incorporated or
deemed to be incorporated therein by reference untrue in any material respect or
that requires the making of any changes in the Registration  Statement,  related
prospectus or documents so that, in the case of the Registration  Statement,  it
will not contain any untrue  statement  of a material  fact or omit to state any
material fact required to be stated  therein or necessary to make the statements
therein not misleading,  and that in the case of the related prospectus, it will
not  contain  any  untrue  statement  of a  material  fact or omit to state  any
material fact required to be stated  therein or necessary to make the statements
therein,  in the light of the  circumstances  under  which they were  made,  not
misleading; provided, however that prior to the disclosure by the Company of any
material   non-public   information  to  the  Investors  or  their  advisors  or
representatives  pursuant to this Section 3(g) or any other  provisions  of this
Agreement,  the  Company  shall  identify  such  information  as being  material
non-public  information  and shall provide the Investors with the opportunity to
accept or refuse to accept such material non-public information.

                  h. As promptly as practicable after becoming aware of an event
specified in Section 3(g)(iv) of this Agreement,  the Company shall use its best
efforts  promptly  to prepare a  supplement  or  amendment  to any  Registration
Statement to correct such untrue statement or omission,  and deliver such number
of copies of such  supplement or amendment to each Investor as such Investor may
reasonably  request;  provided that,  for not more than twenty (20)  consecutive
Trading  Days (or a total of not more than sixty (60) Trading Days in any twelve
(12) month period),  the Company may delay the disclosure of material non-public
information  concerning  the  Company  (as well as  prospectus  or  Registration
Statement  updating)  the  disclosure  of which at the time is not,  in the good
faith opinion of the Company,  in the best interests of the Company (an "Allowed
Delay");  provided,  further,  that the Company  shall  promptly  (i) notify the
Investors  in writing of the  existence  of (but in no event,  without the prior
written consent of an Investor,  shall the Company disclose to such Investor any
of the facts or circumstances  regarding) material non-public information giving
rise to an Allowed  Delay and (ii) advise the  Investors in writing to cease all
sales under such Registration Statement until the end of the Allowed Delay. Upon
expiration  of the Allowed  Delay,  the Company  shall again be bound by Section
3(g) and the first sentence of this Section 3(h) with respect to the information
giving  rise  thereto.  In the event  that the  Investors  consent to receipt of
material non-public  information pursuant to the second proviso contained in the
first  sentence of this Section 3(h),  the  Investors  hereby agree to keep such
information confidential until the earlier of (i) the date when such information
is publicly  disclosed by the Company and (ii) the date which is twenty-one (21)
Trading Days after the beginning of the period constituting such Allowed Delay.

                  i. The  Company  shall use its best  efforts  to  prevent  the
issuance  of  any  stop  order  or  other  suspension  of  effectiveness  of any
Registration  Statement,  and,  if  such an  order  is  issued,  to  obtain  the
withdrawal  of such order at the  earliest  possible  moment and to notify  each
Investor  who holds  Registrable  Securities  being sold (or, in the event of an
underwritten  offering, the managing underwriters) of the issuance of such order
and the resolution thereof.

                  j.  The  Company   shall  permit  a  single  firm  of  counsel
designated by the Initial Investor to review such Registration Statement and all
amendments and supplements  thereto (as well as all requests for acceleration or
effectiveness  thereof  and any  correspondence  between the Company and the SEC
relating  to the  Registration  Statement)  a  reasonable  period  of  time  (as
specified  in Section  2(c) above)  prior to their  filing with the SEC, and not
file any document (nor send any  correspondence) in a form to which such counsel
reasonably  objects  and  will not  request  acceleration  of such  Registration
Statement   without  prior  notice  to  such  counsel.   The  sections  of  such
Registration  Statement covering information with respect to the Investors,  the
Investor's  beneficial  ownership of  securities of the Company or the Investors
intended  method of disposition of Registrable  Securities  shall conform to the
information provided to the Company by each of the Investors.

                  k. The Company shall make generally  available to its security
holders as soon as  practicable,  but not later than  ninety (90) days after the
close of the period covered  thereby,  an earnings  statement (in form complying
with  the  provisions  of  Rule  158  under  the  Securities   Act)  covering  a
twelve-month  period  beginning  not later  than the first day of the  Company's
fiscal quarter next following the effective date of the Registration Statement.

                  l. On the date that Registrable Securities are delivered to an
underwriter,  if any, for sale in connection with any Registration Statement or,
if  such  securities  are  not  being  sold by an  underwriter,  on the  date of
effectiveness  thereof and on each Draw Down Date, the Company shall have caused
to be delivered to the Investor (and to each underwriter, if any) (i) an opinion
of the  Company's  independent  counsel in the form of Exhibit G to the Purchase
Agreement,  addressed to the underwriters,  if any, and the Investors and (ii) a
Comfort  Letter or Bring Down  Comfort  Letter  (each as defined in the Purchase
Agreement),  as  applicable,  as required  pursuant to the terms of the Purchase
Agreement, addressed to the underwriters, if any, and the Investors.

                  m. Subject to the  provisions of the Purchase  Agreement,  the
Company  shall make  available  for  inspection  by (i) any  Investor,  (ii) any
underwriter   participating  in  any  disposition  pursuant  to  a  Registration
Statement,  (iii) one firm of  attorneys  and one firm of  accountants  or other
agents retained by the Initial Investor, (iv) one firm of attorneys and one firm
of accountants or other agents retained by all other Investors, and (v) one firm
of attorneys retained by all such underwriters (collectively,  the "Inspectors")
all pertinent financial and other records, and pertinent corporate documents and
properties of the Company (collectively,  the "Records"), as shall be reasonably
deemed  necessary by each Inspector to enable each Inspector to exercise its due
diligence  responsibility,  and  cause the  Company's  officers,  directors  and
employees to supply all information  which any Inspector may reasonably  request
for purposes of such due  diligence;  provided,  however,  that,  subject to the
provisions of the Purchase  Agreement,  each Inspector  shall hold in confidence
and shall not make any disclosure (except to an Investor) of any Record or other
information which the Company  determines in good faith to be confidential,  and
of which determination the Inspectors are so notified, unless (a) the release of
such  Records is ordered  pursuant  to a subpoena or other order from a court or
government body of competent jurisdiction or (b) the information in such Records
has been made  generally  available  to the public other than by  disclosure  in
violation  of this or any  other  agreement.  Nothing  herein  (or in any  other
confidentiality  agreement between the Company and any Investor) shall be deemed
to limit the Investor's ability to sell Registrable Securities in a manner which
is otherwise consistent with applicable laws and regulations.

                  n.  The  Company  shall  hold in  confidence  and not make any
disclosure of information  concerning an Investor provided to the Company unless
(i) disclosure of such  information is necessary to comply with federal or state
securities  laws, (ii) the disclosure of such  information is necessary to avoid
or correct a misstatement or omission in any Registration  Statement,  (iii) the
release of such  information  is ordered  pursuant  to a subpoena or other order
from a court  or  governmental  body of  competent  jurisdiction,  or (iv)  such
information  has been made  generally  available  to the  public  other  than by
disclosure in violation of this or any other agreement.  The Company agrees that
it shall,  upon  learning  that  disclosure  of such  information  concerning an
Investor  is  sought  in  or  by a  court  or  governmental  body  of  competent
jurisdiction  or through other means,  give prompt notice to such Investor prior
to making such disclosure,  and allow the Investor, at its expense, to undertake
appropriate  action to prevent  disclosure  of, or to obtain a protective  order
for, such information.

                  o. The Company shall (i) cause all the Registrable  Securities
covered by the Registration  Statement to be listed on each national  securities
exchange on which  securities  of the same class or series issued by the Company
are then listed,  if any, if the listing of such Registrable  Securities is then
permitted under the rules of such exchange, or (ii) to the extent the securities
of the same  class  or  series  are not then  listed  on a  national  securities
exchange, secure the designation and quotation of all the Registrable Securities
covered by the  Registration  Statement on Nasdaq or, if not eligible for Nasdaq
on the Nasdaq SmallCap and, without limiting the generality of the foregoing, to
arrange for at least two market makers to register with the National Association
of Securities  Dealers,  Inc.  ("NASD") as such with respect to such Registrable
Securities.

                  p. The Company shall provide a transfer  agent and  registrar,
which may be a single entity, for the Registrable  Securities not later than the
effective date of the Registration Statement.

                  q. The Company  shall  cooperate  with the  Investors who hold
Registrable   Securities   being  offered  and  the  managing   underwriter   or
underwriters,  if any, to  facilitate  the timely  preparation  and  delivery of
certificates  (not bearing any  restrictive  legends)  representing  Registrable
Securities to be offered pursuant to such Registration Statement and enable such
certificates to be in such denominations or amounts,  as the case may be, as the
managing  underwriter or  underwriters,  if any, or the Investors may reasonably
request  and   registered  in  such  names  as  the  managing   underwriter   or
underwriters,  if any, or the  Investors  may  request,  and,  within  three (3)
business  days  after  a  Registration   Statement  which  includes  Registrable
Securities is ordered effective by the SEC, the Company shall deliver, and shall
cause legal counsel  selected by the Company to deliver,  to the transfer  agent
for the Registrable  Securities (with copies to the Investors whose  Registrable
Securities  are included in such  Registration  Statement) an instruction in the
form  attached  hereto as Exhibit 1 and an  opinion of such  counsel in the form
attached hereto as Exhibit 2.

                  r. At the request of the holders of a majority-in-interest  of
the Registrable Securities, the Company shall prepare and file with the SEC such
amendments   (including   post-effective   amendments)   and  supplements  to  a
Registration   Statement  and  any  prospectus   used  in  connection  with  the
Registration  Statement  as may be  necessary  in  order to  change  the plan of
distribution set forth in such Registration Statement.

                  s. The Company  shall not,  and shall not agree to,  allow the
holders of any  securities of the Company to include any of their  securities in
any  Registration  Statement  under  Section  2(a)  hereof or any  amendment  or
supplement  thereto under Section 3(b) hereof without the consent of the holders
of a  majority-in-interest  of the  Registrable  Securities.  In  addition,  the
Company  shall not offer any  securities  for its own  account or the account of
others in any Registration  Statement under Section 2(a) hereof or any amendment
or  supplement  thereto  under  Section  3(b) hereof  without the consent of the
holders of a majority-in- interest of the Registrable Securities.

                  t.  The  Company  shall  take  all  other  reasonable  actions
necessary to expedite and facilitate disposition by the Investors of Registrable
Securities pursuant to a Registration Statement.

                  u. The Company shall comply with all  applicable  laws related
to a  Registration  Statement  and  offering  and  sale  of  securities  and all
applicable  rules and  regulations  of  governmental  authorities  in connection
therewith  (including without limitation the Securities Act and the Exchange Act
and the rules and regulations promulgated by the SEC).

         4.       OBLIGATIONS OF THE INVESTORS.

         In connection with the registration of the Registrable Securities,  the
Investors shall have the following obligations:

                  a. It shall be a condition precedent to the obligations of the
Company to complete the registration  pursuant to this Agreement with respect to
the  Registrable  Securities of a particular  Investor that such Investor  shall
furnish to the  Company  such  information  regarding  itself,  the  Registrable
Securities  held by it and the intended method of disposition of the Registrable
Securities held by it as shall be reasonably required to effect the registration
of such  Registrable  Securities  and shall execute such documents in connection
with such registration as the Company may reasonably request. At least seven (7)
business  days prior to the first  anticipated  filing date of the  Registration
Statement, the Company shall notify each Investor of the information the Company
requires from each such Investor.

                  b.  Each  Investor,  by  such  Investor's  acceptance  of  the
Registrable  Securities,  agrees to  cooperate  with the  Company as  reasonably
requested by the Company in connection  with the  preparation  and filing of the
Registration Statements hereunder, unless such Investor has notified the Company
in  writing  of such  Investor's  election  to  exclude  all of such  Investor's
Registrable Securities from the Registration Statements.

                  c. In the event Investors  holding a  majority-in-interest  of
the Registrable  Securities  being  registered (with the approval of the Initial
Investor)  determine to engage the  services of an  underwriter,  each  Investor
agrees  to  enter  into  and  perform  such  Investor's   obligations  under  an
underwriting  agreement,  in  usual  and  customary  form,  including,   without
limitation,  customary  indemnification and contribution  obligations,  with the
managing  underwriter  of such  offering  and take  such  other  actions  as are
reasonably  required in order to expedite or facilitate  the  disposition of the
Registrable Securities, unless such Investor has notified the Company in writing
of such  Investor's  election  to  exclude  all of such  Investor's  Registrable
Securities from such Registration Statement.

                  d. Each Investor  agrees that, upon receipt of any notice from
the Company of the happening of any event of the kind described in Sections 3(g)
or 3(i), such Investor will immediately  discontinue  disposition of Registrable
Securities  pursuant to the  Registration  Statement  covering such  Registrable
Securities  until such Investor's  receipt of the copies of the  supplemented or
amended prospectus  contemplated by Sections 3(g) or 3(i) and, if so directed by
the Company,  such Investor  shall deliver to the Company (at the expense of the
Company) or destroy (and deliver to the Company a  certificate  of  destruction)
all  copies in such  Investor's  possession,  of the  prospectus  covering  such
Registrable Securities current at the time of receipt of such notice.

                  e.  No   Investor   may   participate   in  any   underwritten
registration  hereunder  unless such Investor (i) agrees to sell such Investor's
Registrable Securities on the basis provided in any underwriting arrangements in
usual and  customary  form  entered  into by the  Company,  (ii)  completes  and
executes  all  questionnaires,  powers of  attorney,  indemnities,  underwriting
agreements  and  other  documents  reasonably  required  under the terms of such
underwriting  arrangements,  and (iii)  agrees to pay its pro rata  share of all
underwriting  discounts  and  commissions  and any  expenses  in excess of those
payable by the Company pursuant to Section 5 below.

         5.       EXPENSES OF REGISTRATION.

         All  reasonable  expenses,   other  than  underwriting   discounts  and
commissions,   incurred   in   connection   with   registrations,   filings   or
qualifications pursuant to Sections 2 and 3, including,  without limitation, all
registration,  listing and qualification fees, printers and accounting fees, the
fees and  disbursements of counsel for the Company,  and the reasonable fees and
disbursements  of one  counsel  selected  by the  Initial  Investor  pursuant to
Sections 2(b) and 3(j) hereof shall be borne by the Company; provided,  however,
that such  reasonable  fees and  disbursements  of the  counsel  selected by the
Initial  Investors shall be subject to the limitation on  reimbursable  expenses
set forth in Section 5.6 of the Purchase Agreement.

         6.       INDEMNIFICATION.

         In the event any Registrable  Securities are included in a Registration
Statement under this Agreement:

                  a. To the extent permitted by law, the Company will indemnify,
hold  harmless  and  defend  (i)  each  Investor  who  holds  such   Registrable
Securities, (ii) the directors,  officers, partners,  employees, agents and each
person who controls any Investor within the meaning of the Securities Act or the
Securities  Exchange Act of 1934, as amended (the "Exchange Act"), if any, (iii)
any underwriter  (as defined in the Securities Act) for the Investors,  and (iv)
the directors,  officers,  partners,  employees and each person who controls any
such  underwriter  within the meaning of the Securities Act or the Exchange Act,
if any (each,  an  "Indemnified  Person"),  against any joint or several losses,
claims, damages,  liabilities or expenses (collectively,  together with actions,
proceedings  or inquiries by any  regulatory  or  self-regulatory  organization,
whether commenced or threatened,  in respect thereof,  "Claims") to which any of
them may become  subject  insofar as such Claims arise out of or are based upon:
(i) any untrue  statement or alleged  untrue  statement of a material  fact in a
Registration  Statement or the omission or alleged  omission to state  therein a
material fact required to be stated or necessary to make the statements  therein
not  misleading;  (ii) any untrue  statement  or alleged  untrue  statement of a
material  fact  contained  in any  preliminary  prospectus  if used prior to the
effective  date  of such  Registration  Statement,  or  contained  in the  final
prospectus  (as  amended or  supplemented,  if the Company  files any  amendment
thereof or supplement  thereto with the SEC) or the omission or alleged omission
to state  therein  any  material  fact  necessary  to make the  statements  made
therein,  in light of the circumstances  under which the statements therein were
made, not misleading; or (iii) any violation or alleged violation by the Company
of the  Securities  Act, the Exchange  Act,  any other law,  including,  without
limitation,  any state  securities  law,  or any rule or  regulation  thereunder
relating to the offer or sale of the Registrable  Securities (the matters in the
foregoing clauses (i) through (iii) being, collectively,  "Violations"). Subject
to the  restrictions  set forth in  Section  6(c) with  respect to the number of
legal counsel,  the Company shall reimburse the Indemnified Person,  promptly as
such  expenses are incurred and are due and payable,  for any  reasonable  legal
fees  or  other  reasonable   expenses  incurred  by  them  in  connection  with
investigating  or  defending  any such  Claim.  Notwithstanding  anything to the
contrary  contained  herein,  the  indemnification  agreement  contained in this
Section  6(a):  (i) shall not apply to a Claim  arising  out of or based  upon a
Violation  which  occurs in reliance  upon and in  conformity  with  information
furnished in writing to the Company by any Indemnified Person or underwriter for
such Indemnified  Person expressly for use in connection with the preparation of
such Registration Statement or any such amendment thereof or supplement thereto;
(ii)  shall  not  apply  to  amounts  paid in  settlement  of any  Claim if such
settlement is effected  without the prior written consent of the Company,  which
consent  shall not be  unreasonably  withheld;  and (iii)  with  respect  to any
preliminary prospectus, shall not inure to the benefit of any Indemnified Person
if  the  untrue  statement  or  omission  of  material  fact  contained  in  the
preliminary  prospectus  was corrected on a timely basis in the  prospectus,  as
then  amended  or  supplemented,  such  corrected  prospectus  was  timely  made
available by the Company  pursuant to Section 3(d) hereof,  and the  Indemnified
Person was promptly advised in writing not to use the incorrect prospectus prior
to  the  use  giving  rise  to  a  Violation   and  such   Indemnified   Person,
notwithstanding  such advice, used it. Such indemnity shall remain in full force
and  effect  regardless  of  any  investigation  made  by or on  behalf  of  the
Indemnified Person and shall survive the transfer of the Registrable  Securities
by the Investors pursuant to Section 9.

                  b. In connection with any  Registration  Statement in which an
Investor is  participating,  each such Investor agrees severally and not jointly
to  indemnify,  hold  harmless  and  defend,  to the same extent and in the same
manner set forth in Section 6(a), the Company,  each of its  directors,  each of
its  officers who signs the  Registration  Statement,  each person,  if any, who
controls the Company  within the meaning of the  Securities  Act or the Exchange
Act, any underwriter and any other stockholder  selling  securities  pursuant to
the Registration Statement or any of its directors or officers or any person who
controls such  stockholder or  underwriter  within the meaning of the Securities
Act or the Exchange Act (collectively  and together with an Indemnified  Person,
an  "Indemnified  Party"),  against  any Claim to which  any of them may  become
subject,  under the  Securities  Act, the Exchange Act or otherwise,  insofar as
such Claim  arises out of or is based upon any  Violation by such  Investor,  in
each case to the extent (and only to the extent) that such  Violation  occurs in
reliance  upon and in  conformity  with  written  information  furnished  to the
Company by such Investor  expressly for use in connection with such Registration
Statement; and subject to Section 6(c) such Investor will reimburse any legal or
other expenses  (promptly as such expenses are incurred and are due and payable)
reasonably  incurred by them in connection with  investigating  or defending any
such Claim;  provided,  however,  that the indemnity agreement contained in this
Section 6(b) shall not apply to amounts paid in  settlement of any Claim if such
settlement is effected without the prior written consent of such Investor, which
consent shall not be unreasonably withheld; provided, further, however, that the
Investor shall be liable under this Agreement  (including  this Section 6(b) and
Section  7) for only that  amount as does not exceed  the net  proceeds  to such
Investor  as a result of the sale of  Registrable  Securities  pursuant  to such
Registration  Statement.  Such  indemnity  shall remain in full force and effect
regardless of any  investigation  made by or on behalf of such Indemnified Party
and shall  survive the transfer of the  Registrable  Securities by the Investors
pursuant  to Section  9.  Notwithstanding  anything  to the  contrary  contained
herein,  the  indemnification  agreement  contained  in this  Section  6(b) with
respect  to any  preliminary  prospectus  shall not inure to the  benefit of any
Indemnified Party if the untrue statement or omission of material fact contained
in the preliminary prospectus was corrected on a timely basis in the prospectus,
as then amended or supplemented.

                  c.  Promptly  after  receipt  by  an  Indemnified   Person  or
Indemnified  Party  under this  Section 6 of notice of the  commencement  of any
action  (including  any  governmental   action),   such  Indemnified  Person  or
Indemnified Party shall, if a Claim in respect thereof is to be made against any
indemnifying  party under this  Section 6, deliver to the  indemnifying  party a
written notice of the commencement  thereof,  and the  indemnifying  party shall
have the right to participate in, and, to the extent the  indemnifying  party so
desires,  jointly with any other indemnifying party similarly noticed, to assume
control  of the  defense  thereof  with  counsel  mutually  satisfactory  to the
indemnifying  party and the Indemnified  Person or the Indemnified Party, as the
case may be; provided,  however, that an Indemnified Person or Indemnified Party
shall have the right to retain its own counsel  with the fees and expenses to be
paid by the  indemnifying  party,  if,  in the  reasonable  opinion  of  counsel
retained by the indemnifying  party, the  representation  by such counsel of the
Indemnified  Person or  Indemnified  Party and the  indemnifying  party would be
inappropriate  due to actual  or  potential  differing  interests  between  such
Indemnified  Person or Indemnified Party and any other party represented by such
counsel  in such  proceeding.  The  indemnifying  party  shall  pay for only one
separate legal counsel for the Indemnified  Persons or the Indemnified  Parties,
as applicable,  and such legal counsel shall be selected by Investors  holding a
majority-in-interest  of the Registrable Securities included in the Registration
Statement   to   which   the   Claim   relates   (with   the   approval   of   a
majority-in-interest  of the Initial Investor), if the Investors are entitled to
indemnification  hereunder,  or the  Company,  if the  Company  is  entitled  to
indemnification  hereunder, as applicable. The failure to deliver written notice
to the  indemnifying  party within a reasonable time of the  commencement of any
such action shall not relieve such  indemnifying  party of any  liability to the
Indemnified  Person or  Indemnified  Party  under this  Section 6, except to the
extent  that the  indemnifying  party is actually  prejudiced  in its ability to
defend such action. The indemnification required by this Section 6 shall be made
by  periodic   payments  of  the  amount   thereof  during  the  course  of  the
investigation or defense, as such expense, loss, damage or liability is incurred
and is due and payable.

         7.       CONTRIBUTION.

         To  the  extent  any   indemnification  by  an  indemnifying  party  is
prohibited or limited by law, the indemnifying  party agrees to make the maximum
contribution  with respect to any amounts for which it would otherwise be liable
under Section 6 to the fullest extent permitted by law; provided,  however, that
(i) no contribution shall be made under  circumstances where the maker would not
have been  liable for  indemnification  under the fault  standards  set forth in
Section  6, (ii) no  seller  of  Registrable  Securities  guilty  of  fraudulent
misrepresentation  (within the meaning of Section 11(f) of the  Securities  Act)
shall be entitled to contribution from any seller of Registrable  Securities who
was not  guilty of such  fraudulent  misrepresentation,  and (iii)  contribution
(together with any indemnification or other obligations under this Agreement) by
any  seller of  Registrable  Securities  shall be  limited  in amount to the net
amount of proceeds  received  by such  seller from the sale of such  Registrable
Securities.

         8.       REPORTS UNDER THE EXCHANGE ACT.

         With a view to making  available to the  Investors the benefits of Rule
144 or any  other  similar  rule or  regulation  of the SEC that may at any time
permit the  investors to sell  securities  of the Company to the public  without
registration, the Company agrees to:

                  a. make and keep public information  available, as those terms
are understood and defined in Rule 144;

                  b. file with the SEC in a timely  manner all reports and other
documents  required of the Company under the Securities Act and the Exchange Act
so long as the Company remains subject to such requirements (it being understood
that nothing herein shall limit the Company's  obligations  under Section 5.3 of
the Purchase  Agreement)  and the filing of such reports and other  documents is
required for the applicable provisions of Rule 144; and

                  c.  furnish to each  Investor  so long as such  Investor  owns
Registrable  Securities,  promptly upon request,  (i) a written statement by the
Company that it has complied  with the reporting  requirements  of Rule 144, the
Securities  Act and the Exchange  Act,  (ii) a copy of the most recent annual or
quarterly report of the Company and such other reports and documents so filed by
the Company,  and (iii) such other information as may be reasonably requested to
permit  the  Investors  to sell such  securities  pursuant  to Rule 144  without
registration.

         9.       ASSIGNMENT OF REGISTRATION RIGHTS.

         The rights under this Agreement  shall be  automatically  assignable by
the Investors to any transferee of all or any portion of Registrable  Securities
if: (i) the Investor agrees in writing with the transferee or assignee to assign
such rights,  and a copy of such  agreement is furnished to the Company within a
reasonable time after such assignment,  (ii) the Company is, within a reasonable
time after such transfer or assignment, furnished with written notice of (a) the
name and address of such  transferee or assignee,  and (b) the  securities  with
respect to which such  registration  rights are being  transferred  or assigned,
(iii)  following  such transfer or assignment,  the further  disposition of such
securities by the transferee or assignee is restricted  under the Securities Act
and applicable  state  securities  laws,  (iv) at or before the time the Company
receives the written notice  contemplated  by clause (ii) of this sentence,  the
transferee or assignee  agrees in writing with the Company to be bound by all of
the  provisions  contained  herein,  (v) such  transfer  shall have been made in
accordance with the applicable requirements of the Purchase Agreement,  and (vi)
such transferee  shall be an "accredited  investor" as that term defined in Rule
501 of Regulation D promulgated under the Securities Act.

         10.      AMENDMENT OF REGISTRATION RIGHTS.

         Provisions of this Agreement may be amended and the observance  thereof
may  be  waived  (either  generally  or  in a  particular  instance  and  either
retroactively or prospectively),  only with written consent of the Company,  the
Initial  Investor (to the extent such Initial  Investor  still owns  Registrable
Securities)  and  Investors  who hold a  majority  interest  of the  Registrable
Securities.  Any amendment or waiver effected in accordance with this Section 10
shall be binding upon each Investor and the Company.

         11.      MISCELLANEOUS.

                  a. A person or entity is deemed to be a holder of  Registrable
Securities  whenever  such  person or entity  owns of  record  such  Registrable
Securities.  If  the  Company  receives  conflicting  instructions,  notices  or
elections  from  two or more  persons  or  entities  with  respect  to the  same
Registrable  Securities,  the Company shall act upon the basis of  instructions,
notice  or  election  received  from the  registered  owner of such  Registrable
Securities.

                  b. Any  notices  required or  permitted  to be given under the
terms  hereof  shall be sent by certified  or  registered  mail (return  receipt
requested)  or  delivered  personally  or by  courier  (including  a  recognized
overnight  delivery  service) or by facsimile  and shall be effective  five days
after being placed in the mail, if mailed by regular United States mail, or upon
receipt, if delivered personally or by courier (including a recognized overnight
delivery  service)  or by  facsimile,  in each case  addressed  to a party.  The
addresses for such communications shall be:

                           If to the Company:

                           Teligent, Inc.
                           8065 Leesburg Pike, Suite 400
                           Vienna, Virginia   22182
                           Attention: General Counsel
                           Facsimile: (703) 762-5177

                           With copy to:

                           Cravath, Swaine & Moore
                           825 Eighth Avenue
                           New York, New York 10019
                           Attention:  Scott A. Barshay, Esq.
                           Facsimile: (212) 474-3700

If  to  an Investor: to the address set forth immediately below such  Investor's
name on the signature pages to the Purchase Agreement.

                           With copy to:

                           Bradley D. Houser, Esq.
                           Akerman, Senterfitt & Eidson, P.A.
                           One Southeast Third Avenue, 28th Floor
                           Miami, Florida 33131
                           Facsimile:  (305) 374-5095

                  c.  Failure of any party to exercise any right or remedy under
this  Agreement or otherwise,  or delay by a party in  exercising  such right or
remedy, shall not operate as a waiver thereof.

                  d.  This  Agreement  shall be  governed  by and  construed  in
accordance with the laws of the State of Delaware  applicable to agreements made
and to be performed in the State of Delaware  (without  regard to  principles of
conflict  of  laws).   Both  parties   irrevocably   consent  to  the  exclusive
jurisdiction of the United States federal courts and the state courts located in
Delaware with respect to any suit or  proceeding  based on or arising under this
Agreement,   the  agreements   entered  into  in  connection   herewith  or  the
transactions  contemplated  hereby or  thereby  and  irrevocably  agree that all
claims in respect of such suit or  proceeding  may be determined in such courts.
Both  parties  irrevocably  waive the  defense of an  inconvenient  forum to the
maintenance of such suit or proceeding.  Both parties further agree that service
of  process  upon a party  mailed by first  class  mail shall be deemed in every
respect  effective  service  of  process  upon the  party  in any  such  suit or
proceeding. Nothing herein shall affect either party's right to serve process in
any  other  manner   permitted  by  law.   Both  parties   agree  that  a  final
non-appealable  judgment in any such suit or proceeding  shall be conclusive and
may be enforced in other  jurisdictions by suit on such judgment or in any other
lawful manner.

                  e. This  Agreement,  the Purchase  Agreement  and the Warrants
(including all schedules and exhibits  hereto or thereto)  constitute the entire
agreement among the parties hereto with respect to the subject matter hereof and
thereof. There are no restrictions,  promises, warranties or undertakings, other
than those set forth or  referred to herein and  therein.  This  Agreement,  the
Purchase   Agreement  and  the  Warrants  supersede  all  prior  agreements  and
understandings  among the  parties  hereto with  respect to the  subject  matter
hereof and thereof.

                  f.  Subject  to the  requirements  of  Section 9 hereof,  this
Agreement  shall inure to the benefit of and be binding upon the  successors and
assigns of each of the parties hereto.

                  g. The  headings  in this  Agreement  are for  convenience  of
reference only and shall not limit or otherwise affect the meaning hereof.

                  h. This Agreement may be executed in two or more counterparts,
each of which shall be deemed an original but all of which shall  constitute one
and the same  agreement.  This  Agreement,  once  executed  by a  party,  may be
delivered to the other party hereto by facsimile  transmission of a copy of this
Agreement bearing the signature of the party so delivering this Agreement.

                  i. Each party  shall do and  perform,  or cause to be done and
performed,  all such further acts and things,  and shall execute and deliver all
such other  agreements,  certificates,  instruments and documents,  as the other
party may reasonably request in order to carry out the intent and accomplish the
purposes of this Agreement and the consummation of the transactions contemplated
hereby.

                  j. Except as otherwise provided herein, all consents and other
determinations  to be made by the Investors  pursuant to this Agreement shall be
made by Investors holding a majority of the Registrable Securities.

                  k.  The  Company  acknowledges  that  a  breach  by it of  its
obligations  hereunder will cause irreparable harm to each Investor by vitiating
the intent and purpose of the transactions contemplated hereby. Accordingly, the
Company  acknowledges  that the  remedy  at law for  breach  of its  obligations
hereunder will be inadequate and agrees,  in the event of a breach or threatened
breach by the Company of any of the  provisions  hereunder,  that each  Investor
shall be  entitled,  in  addition to all other  available  remedies in law or in
equity,  to an  injunction  or  injunctions  to prevent or cure  breaches of the
provisions  of  this  Agreement  and  to  enforce  specifically  the  terms  and
provisions  hereof,  without the necessity of showing  economic loss and without
any bond or other security being required.

                  l. The language  used in this  Agreement  will be deemed to be
the language chosen by the parties to express their mutual intent,  and no rules
of strict construction will be applied against any party.

                  m. In the  event  that  any  provision  of this  Agreement  is
invalid or unenforceable  under any applicable statute or rule of law, then such
provision  shall  be  deemed  inoperative  to the  extent  that it may  conflict
therewith  and shall be deemed  modified to conform with such statute or rule of
law. Any provision hereof which may prove invalid or unenforceable under any law
shall not affect the validity or enforceability of any other provision hereof.

                  n. The initial  number of Registrable  Securities  included in
any  Registration  Statement  and each  increase  to the  number of  Registrable
Securities  included  therein  shall be allocated  pro rata among the  Investors
based on the number of Registrable  Securities held by each Investor at the time
of such establishment or increase,  as the case may be. In the event an Investor
shall sell or otherwise  transfer any of such holder's  Registrable  Securities,
each  transferee  shall  be  allocated  a pro  rata  portion  of the  number  of
Registrable Securities included in a Registration Statement for such transferor.
Any shares of Common Stock included on a Registration Statement and which remain
allocated to any person or entity which does not hold any Registrable Securities
shall be allocated to the remaining  Investors,  pro rata based on the number of
shares of Registrable Securities then held by such Investors.

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]
<PAGE>
                  IN WITNESS  WHEREOF,  the Company and the undersigned  Initial
Investor  have caused this  Agreement  to be duly  executed as of the date first
above written.

TELIGENT, INC.

By: /s/ Alex J. Mandl
    ----------------------------------
         Alex J. Mandl,
         Chief Executive Officer

RGC INTERNATIONAL INVESTORS, LDC

By:      Rose Glen Capital Management, L.P., Investment Manager
         By:      RGC General Partner Corp., as General Partner

By: /s/ Wayne D. Bloch
    ----------------------------------
         Wayne D. Bloch
         Managing DirectorTHIS WARRANT AND THE SHARES  ISSUABLE UPON THE EXERCISE OF THIS WARRANT
         HAVE NOT BEEN REGISTERED  UNDER THE SECURITIES ACT OF 1933, AS AMENDED.
         EXCEPT AS  OTHERWISE  SET FORTH  HEREIN OR IN A COMMON  STOCK  PURCHASE
         AGREEMENT DATED AS OF DECEMBER 7, 2000, NEITHER THIS WARRANT NOR ANY OF
         SUCH SHARES MAY BE SOLD,  TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN
         EFFECTIVE  REGISTRATION STATEMENT FOR SUCH SECURITIES UNDER SAID ACT OR
         AN  OPINION  OF  COUNSEL,  IN  FORM,  SUBSTANCE  AND  SCOPE  REASONABLY
         ACCEPTABLE TO THE COMPANY, THAT REGISTRATION IS NOT REQUIRED UNDER SUCH
         ACT OR UNLESS SOLD PURSUANT TO RULE 144 UNDER SUCH ACT.

                                    Right to

                                    Purchase

                                    4,972,370
                                Shares of Class A
                                  Common Stock,
                                 par value $.01
                                    per share

                             STOCK PURCHASE WARRANT

         THIS CERTIFIES THAT, for value received,  RGC International  Investors,
LDC ("RGC") or its permitted  assigns,  is entitled to purchase  from  Teligent,
Inc., a Delaware  corporation (the "Company"),  at any time or from time to time
as  prescribed  herein  during the period  specified  in Section 2 hereof,  Four
Million Nine Hundred  Seventy-Two  Thousand  Three Hundred  Seventy  (4,972,370)
fully paid and  nonassessable  shares of the Company's Class A Common Stock, par
value $.01 per share (the  "Common  Stock"),  at an exercise  price of $3.62 per
share (the "Exercise Price"). The term "Warrant Shares," as used herein,  refers
to the shares of Common Stock purchasable hereunder.  The Warrant Shares and the
Exercise  Price are subject to adjustment  as provided in Section 4 hereof.  The
term Warrants means this Warrant and the other warrants  issued pursuant to that
certain  Common Stock Purchase  Agreement,  dated December 7, 2000, by and among
the Company and RGC (the "Stock  Purchase  Agreement").  Capitalized  terms used
herein and not otherwise  defined herein shall have the respective  meanings set
forth in the Stock Purchase Agreement.

         This  Warrant  is  subject  to the  following  terms,  provisions,  and
conditions:

         1. Manner of Exercise;  Issuance of  Certificates;  Payment for Shares.
Subject to the  provisions  hereof,  this Warrant may be exercised by the holder
hereof,  in whole or in part, by the surrender of this Warrant,  together with a
completed  exercise  agreement  in  the  form  attached  hereto  (the  "Exercise
Agreement"),  to the Company during normal business hours on any business day at
the Company's principal executive offices (or such other office or agency of the
Company  as it may  designate  by notice  to the  holder  hereof),  and upon (i)
payment to the Company in cash,  by certified or official  bank check or by wire
transfer  for the account of the Company of the  Exercise  Price for the Warrant
Shares specified in the Exercise  Agreement or (ii) if the resale of the Warrant
Shares  by  the  holder  is  not  then  registered   pursuant  to  an  effective
registration  statement  under  the  Securities  Act of 1933,  as  amended  (the
"Securities Act") (or, if after the registration  statement covering the Warrant
Shares  is  declared  effective,  sales of the  Warrant  Shares  may not be made
thereunder  for any reason),  delivery to the Company of a written  notice of an
election to effect a "Cashless Exercise" (as defined in Section 12(c) below) for
the Warrant Shares  specified in the Exercise  Agreement.  The Warrant Shares so
purchased  shall be deemed to be issued to the  holder  hereof or such  holder's
designee, as the record owner of such shares, as of the close of business on the
date on which this Warrant shall have been surrendered,  the completed  Exercise
Agreement shall have been  delivered,  and payment shall have been made for such
shares (or an election to effect a Cashless Exercise has been made) as set forth
above.  Certificates  for the  Warrant  Shares so  purchased,  representing  the
aggregate  number  of  shares  specified  in the  Exercise  Agreement,  shall be
delivered to the holder hereof within a reasonable time, not exceeding three (3)
business days, after this Warrant shall have been so exercised. The certificates
so delivered  shall be in such  denominations  as may be requested by the holder
hereof and shall be  registered in the name of such holder or such other name as
shall be  designated by such holder.  If this Warrant shall have been  exercised
only in part, then,  unless this Warrant has expired,  the Company shall, at its
expense,  at the time of delivery of such certificates,  deliver to the holder a
new Warrant representing the number of shares with respect to which this Warrant
shall not then have been exercised.

                  Notwithstanding  anything in this Warrant to the contrary,  in
no event  shall the holder of this  Warrant be  entitled to exercise a number of
Warrants (or portions  thereof) in excess of the number of Warrants (or portions
thereof)  upon  exercise  of which the sum of (i) the number of shares of Common
Stock  beneficially owned by the holder and its affiliates (other than shares of
Common Stock which may be deemed beneficially owned through the ownership of the
unexercised  Warrants and the  unexercised or  unconverted  portion of any other
securities of the Company  (including  the rights or obligations of the Buyer to
purchase securities from the Company under the Stock Purchase Agreement) subject
to a limitation on conversion or exercise analogous to the limitation  contained
herein) and (ii) the number of shares of Common Stock  issuable upon exercise of
the  Warrants  (or portions  thereof)  with  respect to which the  determination
described  herein is being made,  would  result in  beneficial  ownership by the
holder and its affiliates of more than 9.9% of the then  Outstanding  Shares (as
defined  in the Stock  Purchase  Agreement).  For  purposes  of the  immediately
preceding sentence,  beneficial ownership shall be determined in accordance with
Section 13(d) of the Securities Exchange Act of 1934, as amended, and Regulation
13D-G   thereunder,   except  as  otherwise   provided  in  clause  (i)  hereof.
Notwithstanding  anything in this Warrant to the  contrary,  the  limitation  on
exercise  of this  Warrant  set forth in this  paragraph  shall  not be  amended
without (a) the written consent of the holder hereof and the Company and (b) the
approval of the holders of a majority of the Company's Common Stock present,  or
represented by proxy,  and voting at any meeting called to vote on the amendment
of such restriction.

         2.  Period of  Exercise;  Vesting.  Subject to the  vesting  provisions
contained below, this Warrant is exercisable at any time or from time to time on
or after the date on which this Warrant is issued and delivered  pursuant to the
terms of the Stock  Purchase  Agreement (the "Issue Date") and before 5:00 p.m.,
New York  City  time,  on the fifth  (5th)  anniversary  of the Issue  Date (the
"Exercise  Period").  In no event  shall the holder be  entitled  to  purchase a
number of shares upon exercise of the Warrant which,  when  aggregated  with all
prior purchases of shares upon exercise of this Warrant, exceeds the then vested
portion of this Warrant hereunder.  This Warrant shall vest as to (i) 75% of the
aggregate  number of  shares of Common  Stock  issuable  upon  exercise  of this
Warrant  immediately  on the Issue Date and (ii) after the holder has  purchased
from the Company  Common Stock with an aggregate  Purchase  Price (as defined in
the  Stock   Purchase   Agreement)  of  One  Hundred   Fifty   Million   Dollars
($150,000,000)   pursuant  to  the  Stock  Purchase  Agreement,   an  additional
percentage of the shares of Common Stock  issuable upon exercise of this Warrant
shall vest  simultaneously  with each  additional  Draw Down (as  defined in the
Stock  Purchase  Agreement)  of Common  Stock  pursuant  to the  Stock  Purchase
Agreement. The additional percentage of the aggregate number of shares of Common
Stock issuable upon exercise of this Warrant which shall vest in accordance with
clause (ii) of the preceding  sentence shall equal (x) the Investment Amount (as
defined in the Stock Purchase  Agreement)  relating to each such additional Draw
Down, divided by (y) Two Hundred Fifty Million Dollars ($250,000,000).

         3.  Certain Agreements of the Company. The Company hereby covenants and
agrees as follows:

                  (a) Shares to be Fully Paid.  All Warrant  Shares  will,  upon
issuance in accordance with the terms of this Warrant, be validly issued,  fully
paid, and nonassessable and free from all taxes, liens, and charges with respect
to the issue thereof.

                  (b)  Reservation of Shares.  During the Exercise  Period,  the
Company  shall at all times have  authorized,  and  reserved  for the purpose of
issuance upon exercise of this Warrant,  a sufficient number of shares of Common
Stock to provide for the exercise of this Warrant.

                  (c) Listing.  The Company shall promptly secure the listing of
the shares of Common  Stock  issuable  upon  exercise of the  Warrant  upon each
national  securities  exchange or automated quotation system, if any, upon which
shares of Common Stock are then listed  (subject to official  notice of issuance
upon exercise of this Warrant) and shall  maintain,  so long as any other shares
of Common  Stock shall be so listed,  such listing of all shares of Common Stock
from time to time issuable  upon the exercise of this  Warrant;  and the Company
shall  so list on each  national  securities  exchange  or  automated  quotation
system, as the case may be, and shall maintain such listing of, any other shares
of capital  stock of the Company  issuable  upon the exercise of this Warrant if
and so long as any  shares of the same  class  shall be listed on such  national
securities exchange or automated quotation system.

                  (d)  Certain  Actions  Prohibited.  The  Company  will not, by
amendment  of its  charter or through  any  reorganization,  transfer of assets,
consolidation,  merger,  dissolution,  issue or sale of securities, or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed by it hereunder,  but will at all times in
good faith assist in the carrying out of all the  provisions of this Warrant and
in the taking of all such action as may reasonably be requested by the holder of
this  Warrant in order to protect the  exercise  privilege of the holder of this
Warrant  against  dilution or other  impairment,  consistent  with the tenor and
purpose of this Warrant.  Without limiting the generality of the foregoing,  the
Company  (i) will not  increase  the par value of any  shares  of  Common  Stock
receivable  upon the exercise of this Warrant  above the Exercise  Price then in
effect,  and (ii) will take all such actions as may be necessary or  appropriate
in  order  that the  Company  may  validly  and  legally  issue  fully  paid and
nonassessable shares of Common Stock upon the exercise of this Warrant.

                  (e) Successors and Assigns.  This Warrant will be binding upon
any entity succeeding to the Company by merger, consolidation, or acquisition of
all or substantially all the Company's assets.

         4. Antidilution  Provisions.  During the Exercise Period,  the Exercise
Price and the number of Warrant Shares shall be subject to adjustment  from time
to time as provided in this Section 4.

         In the event that any  adjustment  of the  Exercise  Price as  required
herein results in a fraction of a cent,  such Exercise Price shall be rounded up
to the nearest cent.

                  (a)  Adjustment  of  Exercise  Price and Number of Shares upon
Issuance of Common Stock. Except as otherwise provided in Sections 4(c) and 4(e)
hereof, if and whenever on or after the Issue Date of this Warrant,  the Company
issues or sells,  or in  accordance  with  Section 4(b) hereof is deemed to have
issued  or sold,  any  shares  of Common  Stock  for no  consideration  or for a
consideration per share (before deduction of reasonable  expenses or commissions
or underwriting  discounts or allowances in connection  therewith) less than the
Market  Price (as  hereinafter  defined) in effect on the date of  issuance  (or
deemed issuance) of such Common Stock (a "Dilutive Issuance"),  then immediately
upon the  Dilutive  Issuance,  the  Exercise  Price  will be  reduced to a price
determined by multiplying the Exercise Price in effect  immediately prior to the
Dilutive  Issuance by a fraction,  (i) the numerator of which is an amount equal
to the sum of (x) the  number of shares of  Common  Stock  actually  outstanding
immediately  prior  to the  Dilutive  Issuance,  plus  (y) the  quotient  of the
aggregate  consideration,  calculated  as set  forth  in  Section  4(b)  hereof,
received by the Company upon such Dilutive  Issuance divided by the Market Price
in effect immediately prior to the Dilutive  Issuance,  and (ii) the denominator
of which is the total number of shares of Common Stock  Deemed  Outstanding  (as
defined below) immediately after the Dilutive Issuance.

                  (b) Effect on Exercise Price of Certain  Events.  For purposes
of  determining  the adjusted  Exercise  Price under  Section  4(a) hereof,  the
following will be applicable:

                            (i) Issuance of Rights or Options. If the Company in
         any manner issues or grants any warrants, rights or options, whether or
         not  immediately  exercisable,  to subscribe for or to purchase  Common
         Stock, or other securities  convertible into or exchangeable for Common
         Stock ("Convertible  Securities") (such warrants, rights and options to
         purchase  Common  Stock  or  Convertible   Securities  are  hereinafter
         referred  to as  "Options")  and the price  per share for which  Common
         Stock is issuable  upon the  exercise of such  Options is less than the
         Market  Price  in  effect  on the  date of  issuance  or  grant of such
         Options,  then the  maximum  total  number of  shares  of Common  Stock
         issuable  upon the exercise of all such Options will, as of the date of
         the issuance or grant of such Options,  be deemed to be outstanding and
         to have been  issued and sold by the  Company for such price per share.
         For purposes of the preceding sentence,  the "price per share for which
         Common  Stock  is  issuable  upon  the  exercise  of such  Options"  is
         determined  by  dividing  (i) the total  amount,  if any,  received  or
         receivable by the Company as consideration for the issuance or granting
         of all such Options,  plus the minimum  aggregate  amount of additional
         consideration,  if any, payable to the Company upon the exercise of all
         such Options, plus, in the case of Convertible Securities issuable upon
         the  exercise  of  such  Options,   the  minimum  aggregate  amount  of
         additional  consideration  payable  upon  the  conversion  or  exchange
         thereof  at  the  time  such   Convertible   Securities   first  become
         convertible or exchangeable, by (ii) the maximum total number of shares
         of  Common  Stock  issuable  upon  the  exercise  of all  such  Options
         (assuming full conversion of Convertible Securities, if applicable). No
         further  adjustment to the Exercise  Price will be made upon the actual
         issuance of such Common Stock upon the exercise of such Options or upon
         the  conversion  or exchange of  Convertible  Securities  issuable upon
         exercise of such Options.

                           (ii)  Issuance  of  Convertible  Securities.  If  the
         Company  in any  manner  issues  or sells any  Convertible  Securities,
         whether or not immediately  convertible  (other than where the same are
         issuable  upon the  exercise  of  Options)  and the price per share for
         which Common Stock is issuable upon such conversion or exchange is less
         than  the  Market  Price in  effect  on the  date of  issuance  of such
         Convertible  Securities,  then the  maximum  total  number of shares of
         Common  Stock  issuable  upon the  conversion  or  exchange of all such
         Convertible  Securities  will,  as of the date of the  issuance of such
         Convertible  Securities,  be deemed to be outstanding  and to have been
         issued  and sold by the  Company  for such  price  per  share.  For the
         purposes  of the  preceding  sentence,  the  "price per share for which
         Common  Stock  is  issuable  upon  such   conversion  or  exchange"  is
         determined  by  dividing  (i) the total  amount,  if any,  received  or
         receivable by the Company as consideration  for the issuance or sale of
         all such Convertible  Securities,  plus the minimum aggregate amount of
         additional  consideration,  if any,  payable  to the  Company  upon the
         conversion or exchange thereof at the time such Convertible  Securities
         first become  convertible  or  exchangeable,  by (ii) the maximum total
         number of  shares  of Common  Stock  issuable  upon the  conversion  or
         exchange of all such Convertible  Securities.  No further adjustment to
         the Exercise Price will be made upon the actual issuance of such Common
         Stock upon conversion or exchange of such Convertible Securities.

                          (iii) Change in Option Price or  Conversion  Rate.  If
         there  is a  change  at  any  time  in (i)  the  amount  of  additional
         consideration  payable to the Company upon the exercise of any Options;
         (ii) the amount of  additional  consideration,  if any,  payable to the
         Company upon the conversion or exchange of any Convertible  Securities;
         or (iii) the rate at which any  Convertible  Securities are convertible
         into or exchangeable for Common Stock (other than under or by reason of
         provisions designed to protect against dilution), the Exercise Price in
         effect at the time of such change will be  readjusted  to the  Exercise
         Price which would have been in effect at such time had such  Options or
         Convertible  Securities  still  outstanding  provided  for such changed
         additional  consideration  or changed  conversion rate, as the case may
         be, at the time initially granted, issued or sold.

                           (iv)  Treatment  of Expired  Options and  Unexercised
         Convertible Securities.  If, in any case, the total number of shares of
         Common Stock issuable upon exercise of any Option or upon conversion or
         exchange of any Convertible  Securities is not, in fact, issued and the
         rights  to  exercise  such  Option  or  to  convert  or  exchange  such
         Convertible  Securities shall have expired or terminated,  the Exercise
         Price then in effect will be  readjusted  to the  Exercise  Price which
         would have been in effect at the time of such expiration or termination
         had such Option or Convertible  Securities,  to the extent  outstanding
         immediately  prior to such  expiration  or  termination  (other than in
         respect  of the actual  number of shares of Common  Stock  issued  upon
         exercise or conversion thereof), never been issued.

                            (v) Calculation of  Consideration  Received.  If any
         Common Stock, Options or Convertible  Securities are issued, granted or
         sold for cash, the consideration received therefor for purposes of this
         Warrant  will be the amount  received by the Company  therefor,  before
         deduction  of  reasonable   commissions,   underwriting   discounts  or
         allowances or other reasonable expenses paid or incurred by the Company
         in  connection  with such  issuance,  grant or sale. In case any Common
         Stock,  Options  or  Convertible  Securities  are  issued or sold for a
         consideration part or all of which shall be other than cash, the amount
         of the  consideration  other than cash  received by the Company will be
         the fair value of such  consideration,  except where such consideration
         consists  of  securities,  in which  case the  amount of  consideration
         received by the Company will be the Market Price thereof as of the date
         of receipt. In case any Common Stock, Options or Convertible Securities
         are issued in connection with any acquisition,  merger or consolidation
         in which  the  Company  is the  surviving  corporation,  the  amount of
         consideration  therefor  will be  deemed  to be the fair  value of such
         portion of the net assets and business of the non-surviving corporation
         as is  attributable  to  such  Common  Stock,  Options  or  Convertible
         Securities,  as the case may be.  The fair  value of any  consideration
         other than cash or  securities  will be determined in good faith by (a)
         the mutual  agreement  of the Board of  Directors  of the Company and a
         majority-in-interest  of the holders of the outstanding Warrants or (b)
         if the Board of Directors of the Company and a majority-in-interest  of
         the holders of the outstanding Warrants are unable to agree pursuant to
         the  preceding  clause (a), an  independent  investment  bank or a "Big
         Five" independent public accounting firm, in either case, of nationally
         recognized  standing  in the  valuation  of  businesses  similar to the
         business   of   the   Company,    and   mutually    acceptable   to   a
         majority-in-interest of the holders of the outstanding Warrants and the
         Company.

                           (vi)  Exceptions to Adjustment of Exercise  Price. No
         adjustment to the Exercise  Price will be made (i) upon the exercise of
         any warrants,  options or convertible  securities  granted,  issued and
         outstanding  on the date of  issuance  of this  Warrant;  (ii) upon the
         grant or  exercise  of any  stock or  options  which may  hereafter  be
         granted or exercised under any employee benefit plan of the Company now
         existing or to be implemented in the future, so long as the issuance of
         such stock or  options is  approved  by a majority  of the  independent
         members of the Board of  Directors  of the Company or a majority of the
         members of a committee of independent  directors  established  for such
         purpose;  (iii)  upon  the  exercise  of the  Warrants;  (iv)  upon the
         issuance  of  Draw  Down  Shares  (as  defined  in the  Stock  Purchase
         Agreement)  pursuant  to the  Stock  Purchase  Agreement;  or (v)  upon
         issuance of shares of Common  Stock in a firm  commitment  underwritten
         public offering  (excluding a continuous  offering pursuant to Rule 415
         under the Securities Act).

                  (c) Subdivision or Combination of Common Stock. If the Company
at any time subdivides (by any stock split,  stock  dividend,  recapitalization,
reorganization,  reclassification  or  otherwise)  the  shares of  Common  Stock
acquirable  hereunder into a greater number of shares,  then,  after the date of
record for effecting such subdivision,  the Exercise Price in effect immediately
prior to such subdivision will be proportionately reduced. If the Company at any
time  combines  (by  reverse  stock  split,  recapitalization,   reorganization,
reclassification  or otherwise) the shares of Common Stock acquirable  hereunder
into a smaller  number of shares,  then,  after the date of record for effecting
such  combination,  the  Exercise  Price  in  effect  immediately  prior to such
combination will be proportionately increased.

                  (d)  Adjustment in Number of Shares.  Upon each  adjustment of
the Exercise  Price  pursuant to the provisions of this Section 4, the number of
shares of Common Stock  issuable upon exercise of this Warrant shall be adjusted
by multiplying a number equal to the Exercise Price in effect  immediately prior
to such  adjustment  by the  number  of shares of  Common  Stock  issuable  upon
exercise of this Warrant  immediately  prior to such adjustment and dividing the
product so obtained by the adjusted Exercise Price.

                  (e)   Consolidation,   Merger   or   Sale.   In  case  of  any
consolidation  of the  Company  with,  or merger of the  Company  into any other
corporation, or in case of any sale or conveyance of all or substantially all of
the assets of the  Company  other  than in  connection  with a plan of  complete
liquidation of the Company, then as a condition of such consolidation, merger or
sale or conveyance,  adequate  provision will be made whereby the holder of this
Warrant will have the right to acquire and receive upon exercise of this Warrant
in lieu of the shares of Common Stock  immediately  theretofore  acquirable upon
the exercise of this Warrant, such shares of stock,  securities or assets as may
be issued or payable  with respect to or in exchange for the number of shares of
Common Stock immediately  theretofore acquirable and receivable upon exercise of
this  Warrant had such  consolidation,  merger or sale or  conveyance  not taken
place. In any such case, the Company will make  appropriate  provision to insure
that the  provisions  of this Section 4 hereof will  thereafter be applicable as
nearly as may be in  relation  to any shares of stock or  securities  thereafter
deliverable  upon the exercise of this Warrant.  The Company will not effect any
consolidation, merger or sale or conveyance unless (i) prior to the consummation
thereof,  the successor or acquiring  entity (if other than the Company) and, if
an entity  different  from the successor or acquiring  entity,  the entity whose
capital  stock or assets  the  holders of the Common  Stock of the  Company  are
entitled  to  receive  as a  result  of such  consolidation,  merger  or sale or
conveyance  assumes by written  instrument  the  obligations  under this Warrant
(including under this Section 4) and the obligations to deliver to the holder of
this Warrant such shares of stock,  securities or assets as, in accordance  with
the  foregoing  provisions,  the holder may be  entitled to acquire and (ii) the
entity  whose  capital  stock or assets the  holders of the Common  Stock of the
Company are  entitled to receive as a result of such  transaction  is a publicly
traded  corporation  whose  common  stock is listed for  trading on a  Principal
Market (as defined in the Stock Purchase Agreement).

                  (f) Distribution of Assets.  In case the Company shall declare
or make any  distribution  of its assets  (including  cash) to holders of Common
Stock  as a  partial  liquidating  dividend,  by way of  return  of  capital  or
otherwise,  then, after the date of record for determining stockholders entitled
to such distribution,  but prior to the date of distribution, the holder of this
Warrant  shall be entitled upon exercise of this Warrant for the purchase of any
or all of the shares of Common Stock  subject  hereto,  to receive the amount of
such assets which would have been payable to the holder had such holder been the
holder of such shares of Common  Stock on the record date for the  determination
of stockholders entitled to such distribution.

                  (g) Notice of  Adjustment.  Upon the  occurrence  of any event
which  requires any  adjustment of the Exercise  Price,  then,  and in each such
case, the Company shall give notice thereof to the holder of this Warrant, which
notice shall state the Exercise  Price  resulting  from such  adjustment and the
increase or decrease in the number of Warrant  Shares  purchasable at such price
upon exercise,  setting forth in reasonable detail the method of calculation and
the facts  upon which  such  calculation  is based.  Such  calculation  shall be
certified by the chief financial officer of the Company.

                  (h) Minimum Adjustment of Exercise Price. No adjustment of the
Exercise  Price shall be made in an amount of less than 1% of the Exercise Price
in effect at the time such adjustment is otherwise  required to be made, but any
such lesser  adjustment  shall be carried  forward and shall be made at the time
and  together  with the next  subsequent  adjustment  which,  together  with any
adjustments  so  carried  forward,  shall  amount  to not  less  than 1% of such
Exercise Price.

                  (i) No Fractional Shares. No fractional shares of Common Stock
are to be issued upon the  exercise  of this  Warrant.  If the  exercise of this
Warrant  would result in a fractional  share of Common  Stock,  such  fractional
share shall be  disregarded  and the number of shares of Common  Stock  issuable
upon  exercise of the Warrant  shall be rounded up to the next higher  number of
shares.

                  (j)      Other Notices.  In case at any time:
                           -------------

                            (i) the Company  shall declare any dividend upon the
         Common Stock  payable in shares of stock of any class or make any other
         distribution  (including dividends or distributions payable in cash out
         of retained earnings) to the holders of the Common Stock;

                           (ii) the Company  shall offer  for  subscription  pro
         rata  to  the  holders  of the  Common  Stock  any additional shares of
         stock of any class or other rights;

                          (iii) there shall be any capital reorganization of the
         Company,  or  reclassification of the Common Stock, or consolidation or
         merger of the Company with or into, or sale of all or substantially all
         its assets to, another corporation or entity; or

                           (iv)  there shall be a voluntary or involuntary
dissolution, liquidation or winding-up of the Company;

then,  in each such case,  the Company  shall give to the holder of this Warrant
(a) notice of the date on which the books of the Company shall close or a record
shall be taken for  determining  the holders of Common Stock entitled to receive
any such dividend,  distribution,  or subscription rights or for determining the
holders of Common Stock entitled to vote in respect of any such  reorganization,
reclassification,  consolidation,  merger,  sale,  dissolution,  liquidation  or
winding-up  and (b) in the  case of any such  reorganization,  reclassification,
consolidation,  merger, sale, dissolution,  liquidation or winding-up, notice of
the date (or,  if not then  known,  a  reasonable  approximation  thereof by the
Company) when the same shall take place. Such notice shall also specify the date
on which the holders of Common Stock shall be entitled to receive such dividend,
distribution, or subscription rights or to exchange their Common Stock for stock
or  other  securities  or  property   deliverable   upon  such   reorganization,
reclassification,  consolidation,  merger, sale,  dissolution,  liquidation,  or
winding-up,  as the case  may be.  Such  notice  shall be given at least 30 days
prior to the record date or the date on which the Company's  books are closed in
respect thereto. Failure to give any such notice or any defect therein shall not
affect the validity of the proceedings  referred to in clauses (i), (ii),  (iii)
and (iv) above.

                  (k)  Certain   Events.   If  any  event  occurs  of  the  type
contemplated  by the  adjustment  provisions of this Section 4 but not expressly
provided for by such  provisions,  the Company will give notice of such event as
provided in Section 4(g) hereof,  and the Company's Board of Directors will make
an  appropriate  adjustment  in the  Exercise  Price and the number of shares of
Common Stock  acquirable upon exercise of this Warrant so that the rights of the
holder shall be neither enhanced nor diminished by such event.

                  (l)      Certain Definitions.

                            (i) "Common Stock Deemed Outstanding" shall mean the
         number of shares of Common Stock  actually  outstanding  (not including
         shares of Common Stock held in the treasury of the  Company),  plus (x)
         pursuant to Section 4(b)(i) hereof,  the maximum total number of shares
         of Common Stock  issuable upon the exercise of Options,  as of the date
         of such issuance or grant of such Options,  if any, and (y) pursuant to
         Section 4(b)(ii)  hereof,  the maximum total number of shares of Common
         Stock issuable upon  conversion or exchange of Convertible  Securities,
         as of the date of issuance of such Convertible Securities, if any.

                           (ii)  "Market  Price," as of any date,  (i) means the
         average of the last reported sale prices for the shares of Common Stock
         on the Nasdaq National Market  ("Nasdaq") for the five (5) trading days
         immediately  preceding  such date as  reported by  Bloomberg  Financial
         Markets or an equivalent reliable reporting service mutually acceptable
         to and  hereafter  designated  by the  holder of this  Warrant  and the
         Company  ("Bloomberg"),  or (ii) if Nasdaq is not the principal trading
         market for the shares of Common Stock, the average of the last reported
         sale prices on the principal trading market for the Common Stock during
         the same  period as  reported by  Bloomberg,  or (iii) if market  value
         cannot be calculated as of such date on any of the foregoing bases, the
         Market Price shall be the fair market value as reasonably determined in
         good faith by (a) the mutual agreement of the Board of Directors of the
         Company and a  majority-in-interest  of the holders of the  outstanding
         Warrants  or  (b) if the  Board  of  Directors  of  the  Company  and a
         majority-in-interest  of the holders of the  outstanding  Warrants  are
         unable to agree  pursuant to the preceding  clause (a), an  independent
         investment bank or a "Big Five" independent  public accounting firm, in
         either case,  of  nationally  recognized  standing in the  valuation of
         businesses  similar  to the  business  of  the  Company,  and  mutually
         acceptable to a majority-in-interest  of the holders of the outstanding
         Warrants and the Company. The manner of determining the Market Price of
         the Common Stock set forth in the foregoing definition shall apply with
         respect to any other security in respect of which a determination as to
         market value must be made hereunder.

                          (iii) "Common  Stock," for purposes of this Section 4,
         includes  the  Common  Stock and any  additional  class of stock of the
         Company  having no  preference  as to  dividends  or  distributions  on
         liquidation,  provided  that the shares  purchasable  pursuant  to this
         Warrant  shall  include only shares of Common Stock in respect of which
         this Warrant is exercisable,  or shares  resulting from any subdivision
         or  combination   of  such  Common  Stock,   or  in  the  case  of  any
         reorganization, reclassification, consolidation, merger, or sale of the
         character  referred  to in  Section  4(e)  hereof,  the  stock or other
         securities or property provided for in such Section.

         5. Issue Tax. The issuance of certificates  for Warrant Shares upon the
exercise  of this  Warrant  shall be made  without  charge to the holder of this
Warrant or such shares for any issuance  tax or other costs in respect  thereof,
provided  that the  Company  shall not be  required  to pay any tax which may be
payable in respect of any transfer  involved in the issuance and delivery of any
certificate in a name other than the holder of this Warrant.

         6. No Rights or Liabilities  as a  Shareholder.  This Warrant shall not
entitle the holder  hereof to any voting rights or other rights as a shareholder
of the  Company.  No provision of this  Warrant,  in the absence of  affirmative
action by the holder hereof to purchase Warrant Shares,  and no mere enumeration
herein of the rights or privileges of the holder hereof,  shall give rise to any
liability  of such  holder for the  Exercise  Price or as a  shareholder  of the
Company,  whether  such  liability is asserted by the Company or by creditors of
the Company.

         7.  Transfer, Exchange, and Replacement of Warrant; Issuance of Warrant
Shares.

                  (a)  Restriction  on  Transfer.  This  Warrant  and the rights
granted  to the  holder  hereof  are  transferable,  in whole  or in part,  upon
surrender of this Warrant,  together with a properly executed  assignment in the
form  attached  hereto,  at the office or agency of the  Company  referred to in
Section 7(e) below, provided,  however, that any transfer or assignment shall be
subject to the  conditions set forth in Sections 7(f) and 7(g) hereof and to the
applicable provisions of the Stock Purchase Agreement. Until due presentment for
registration of transfer on the books of the Company,  the Company may treat the
registered  holder hereof as the owner and holder  hereof for all purposes,  and
the Company shall not be affected by any notice to the contrary. Notwithstanding
anything to the contrary contained herein, the registration  rights described in
Section 8 are assignable  only in accordance with the provisions of that certain
Registration  Rights  Agreement,  dated as of December 7, 2000, by and among the
Company and RGC (the "Registration Rights Agreement").

                  (b) Warrant  Exchangeable  for Different  Denominations.  This
Warrant is  exchangeable,  upon the surrender hereof by the holder hereof at the
office or agency of the  Company  referred  to in Section  7(e)  below,  for new
Warrants of like tenor  representing  in the aggregate the right to purchase the
number of shares of Common Stock which may be purchased hereunder,  each of such
new Warrants to represent  the right to purchase  such number of shares as shall
be designated by the holder hereof at the time of such surrender.

                  (c)   Replacement   of  Warrant.   Upon  receipt  of  evidence
reasonably  satisfactory  to the  Company of the loss,  theft,  destruction,  or
mutilation  of this  Warrant  and,  in the  case of any  such  loss,  theft,  or
destruction,  upon delivery of an indemnity agreement reasonably satisfactory in
form and amount to the  Company,  or, in the case of any such  mutilation,  upon
surrender and cancellation of this Warrant,  the Company,  at its expense,  will
execute and deliver, in lieu thereof, a new Warrant of like tenor.

                  (d) Cancellation;  Payment of Expenses.  Upon the surrender of
this Warrant in  connection  with any  transfer,  exchange,  or  replacement  as
provided  in this  Section 7, this  Warrant  shall be  promptly  canceled by the
Company.  The Company shall pay all taxes (other than securities transfer taxes)
and all other  expenses  (other  than legal  expenses,  if any,  incurred by the
holder or transferees)  and charges payable in connection with the  preparation,
execution, and delivery of Warrants pursuant to this Section 7.

                  (e)  Register.  The Company shall  maintain,  at its principal
executive  offices  (or such  other  office or agency of the  Company  as it may
designate by notice to the holder hereof), a register for this Warrant, in which
the Company  shall  record the name and address of the person in whose name this
Warrant has been issued,  as well as the name and address of each transferee and
each prior owner of this Warrant.

                  (f) Exercise or Transfer Without Registration. If, at the time
of the surrender of this Warrant in connection with any exercise,  transfer,  or
exchange of this  Warrant,  this Warrant (or, in the case of any  exercise,  the
Warrant Shares issuable hereunder), shall not be registered under the Securities
Act and under  applicable  state  securities  or blue sky laws,  the Company may
require, as a condition of allowing such exercise,  transfer,  or exchange,  (i)
that the holder or transferee of this  Warrant,  as the case may be,  furnish to
the  Company a written  opinion  of  counsel,  which  opinion  and  counsel  are
acceptable  to the  Company,  to the effect  that such  exercise,  transfer,  or
exchange may be made without  registration  under said Act and under  applicable
state  securities or blue sky laws,  (ii) that the holder or transferee  execute
and deliver to the Company an investment letter in form and substance acceptable
to the Company and (iii) that the  transferee  be an  "accredited  investor"  as
defined in Rule 501(a)  promulgated  under the Securities Act;  provided that no
such opinion,  letter or status as an "accredited investor" shall be required in
connection  with a transfer  pursuant to Rule 144 under the Securities  Act. The
first holder of this Warrant, by taking and holding the same,  represents to the
Company that such holder is acquiring this Warrant for investment and not with a
present view to the distribution thereof.

                  (g) Restrictive Legend.  Until such time as the Warrant Shares
have been  registered  for  resale by the  holder  under the  Securities  Act as
contemplated  by the  Registration  Rights  Agreement or  otherwise  may be sold
pursuant to Rule 144 without any  restriction  as to the number of securities as
of a  particular  date  that  can then be  immediately  sold,  the  certificates
representing the Warrant Shares shall bear a restrictive legend in substantially
the following form (and a stop transfer order may be placed against  transfer of
the certificates for such Warrant Shares):

                  "The securities  represented by this certificate have not been
                  registered  under the Securities Act of 1933, as amended.  The
                  securities  may not be sold,  transferred  or  assigned in the
                  absence  of  an  effective   registration  statement  for  the
                  securities  under said Act,  or an opinion of counsel in form,
                  substance and scope reasonably acceptable to the Company, that
                  registration  is not  required  under said Act or unless  sold
                  pursuant  to Rule 144 under  said  Act."

                  The legend set forth  above  shall be removed  and the Company
shall  issue a  certificate  without  such  legend to the holder of any  Warrant
Shares upon which it is stamped,  if,  unless  otherwise  required by applicable
state  securities laws, (a) such Warrant Shares are registered for resale by the
holder under an effective  registration statement filed under the Securities Act
or otherwise may be sold pursuant to Rule 144 without any  restriction as to the
number of securities as of a particular date that can then be immediately  sold,
or (b) such holder  provides  the Company  with an opinion of counsel,  in form,
substance and scope reasonably  acceptable to the Company,  to the effect that a
public sale or transfer of such Warrant Shares may be made without  registration
under the  Securities  Act and such sale or  transfer is  effected,  or (c) such
holder provides the Company with reasonable  assurances that such Warrant Shares
can be sold pursuant to Rule 144. The holder  agrees to sell all Warrant  Shares
(including those represented by a certificate(s)  from which the legend has been
removed) in compliance with applicable prospectus delivery requirements, if any.

         8. Registration Rights. The initial holder of this Warrant (and certain
assignees  thereof) is entitled  to the benefit of such  registration  rights in
respect of the Warrant Shares as are set forth in Section 2 of the  Registration
Rights Agreement.

         9.  Major  Transaction  Redemption.  If at all times  during the period
beginning  thirty (30) Trading  Days prior to the date of the Major  Transaction
Redemption  Notice  (as  defined  below)  and  ending on the  Major  Transaction
Redemption  Date (as defined  below) all of the shares of Common Stock  issuable
upon exercise of this Warrant are then (x) authorized and reserved for issuance,
(y)  registered  for resale under the  Securities Act by the holder and sales of
such  shares may be made  thereunder  (or such  shares may  otherwise  be resold
publicly without restriction (including,  without limitation, as to volume)) and
(z)  eligible  to be traded  on a  Principal  Market  (as  defined  in the Stock
Purchase  Agreement),  then,  in the event the Company  publicly  announces  its
intention to  consummate a Major  Transaction  (as defined  below),  the Company
shall have the right to deliver written notice to the holder of its intention to
redeem this  Warrant in  accordance  with this Section 9. Any notice (the "Major
Transaction  Redemption  Notice") of redemption  hereunder (a "Major Transaction
Redemption")  shall  be  delivered  to  the  holder  at its  registered  address
appearing  on the books and  records of the Company and shall state (1) that the
Company  is  exercising  its right to redeem  this  Warrant  and (2) the date of
redemption (the "Major Transaction Redemption Date"), which date shall be (A) at
least  sixty  (60)  Trading  Days  after  the  date  of  delivery  of the  Major
Transaction  Redemption  Notice  and (B) the date of  consummation  of the Major
Transaction.  In the event that the Major Transaction Notice is delivered to the
holder  but the Major  Transaction  is not  consummated,  the Major  Transaction
Notice  shall  be  deemed  to be  withdrawn  as to  such  holder.  On the  Major
Transaction  Redemption  Date,  the  Company  shall  make  payment  of the Major
Transaction  Redemption  Amount (as  defined  below) to or upon the order of the
holder as  specified  by the holder in  writing to the  Company at least one (1)
business  day prior to the Major  Transaction  Redemption  Date.  If the Company
exercises  its right to redeem  this  Warrant  pursuant  to this  Section 9, the
Company  shall  make  payment  to the  holder of an  amount in cash (the  "Major
Transaction Redemption Amount") equal to the aggregate  Black-Scholes Amount (as
defined below) for the number of shares of Common Stock subject to this Warrant.
Notwithstanding  notice of a Major Transaction  Redemption,  the holder shall at
all times prior to the Major  Transaction  Redemption Date maintain the right to
exercise  this  Warrant  at the  Exercise  Price then in effect  (including  any
adjustments  pursuant to Section 4) and any portion of this Warrant so exercised
after receipt of a Major  Transaction  Redemption  Notice and prior to the Major
Transaction  Redemption  Date  set  forth  in such  notice  and  payment  of the
aggregate Major Transaction  Redemption Amount shall be deducted from the number
of Warrants which are otherwise  subject to redemption  pursuant to such notice.
"Major  Transaction" means a consolidation or merger of the Company with or into
any other corporation or entity (other than a merger in which the Company is the
surviving or continuing  corporation  and its capital stock is unchanged) or the
sale or transfer of all or  substantially  all of the assets of the Company,  in
each case where the consideration for such transaction consists entirely of cash
or in which the entity whose capital stock or assets the holders of Common Stock
are entitled to receive as a result of such Major  Transaction is not a publicly
traded  corporation (i.e., the common stock of such corporation is not traded on
a Principal Market (as defined in the Stock Purchase Agreement)). "Black-Scholes
Amount,"  as of any  date,  means  the  amount  determined  by  calculating  the
"Black-Scholes"  value of an option to purchase one share of Common Stock on the
applicable  page on the  Bloomberg  online page,  using the  following  variable
values:  (i) the current  market  price of the Common Stock equal to the closing
trade  price on the last  trading  day before the Major  Transaction  Redemption
Date;  (ii) volatility of the Common Stock equal to the volatility of the Common
Stock  during  the  100-Trading  Day  period  preceding  the  Major  Transaction
Redemption  Date; (iii) a risk free rate equal to the yield of the United States
treasury  bill or treasury note with a maturity  corresponding  to the remaining
term of the  Warrants  on the Major  Transaction  Redemption  Date;  and (iv) an
exercise price equal to the Exercise Price on the Major  Transaction  Redemption
Date. In the event such calculation  function is no longer  available  utilizing
the Bloomberg  online page,  such  calculations  shall be made using the closest
available  alternative mechanism and variable value to those available utilizing
the Bloomberg online page for such calculation function.

         10. Notices. All notices,  requests, and other communications  required
or permitted  to be given or  delivered  hereunder to the holder of this Warrant
shall be in  writing,  and shall be  personally  delivered,  or shall be sent by
certified or registered  mail or by recognized  overnight mail courier,  postage
prepaid and  addressed,  to such holder at the address  shown for such holder on
the books of the Company,  or at such other address as shall have been furnished
to the Company by notice from such  holder.  All  notices,  requests,  and other
communications  required or permitted to be given or delivered  hereunder to the
Company shall be in writing, and shall be personally delivered, or shall be sent
by certified or registered mail or by recognized overnight mail courier, postage
prepaid and addressed, to the office of the Company at 8065 Leesburg Pike, Suite
400,  Vienna,  Virginia  22182,  Attention:  General  Counsel,  or at such other
address as shall  have been  furnished  to the holder of this  Warrant by notice
from the Company.  Any such notice,  request, or other communication may be sent
by  facsimile,  but shall in such case be  subsequently  confirmed  by a writing
personally  delivered or sent by certified or  registered  mail or by recognized
overnight  mail  courier as provided  above.  All notices,  requests,  and other
communications  shall be  deemed to have  been  given  either at the time of the
receipt  thereof by the person entitled to receive such notice at the address of
such person for  purposes of this  Section  10, or, if mailed by  registered  or
certified mail or with a recognized overnight mail courier upon deposit with the
United States Post Office or such overnight mail courier,  if postage is prepaid
and the mailing is properly addressed, as the case may be.

         11.  Governing  Law. THIS WARRANT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF DELAWARE  APPLICABLE TO AGREEMENTS MADE
AND TO BE PERFORMED IN THE STATE OF DELAWARE  (WITHOUT  REGARD TO  PRINCIPLES OF
CONFLICT  OF  LAWS).   BOTH  PARTIES   IRREVOCABLY   CONSENT  TO  THE  EXCLUSIVE
JURISDICTION OF THE UNITED STATES FEDERAL COURTS AND THE STATE COURTS LOCATED IN
DELAWARE WITH RESPECT TO ANY SUIT OR  PROCEEDING  BASED ON OR ARISING UNDER THIS
AGREEMENT,   THE  AGREEMENTS   ENTERED  INTO  IN  CONNECTION   HEREWITH  OR  THE
TRANSACTIONS  CONTEMPLATED  HEREBY OR  THEREBY  AND  IRREVOCABLY  AGREE THAT ALL
CLAIMS IN RESPECT OF SUCH SUIT OR  PROCEEDING  MAY BE DETERMINED IN SUCH COURTS.
BOTH  PARTIES  IRREVOCABLY  WAIVE THE  DEFENSE OF AN  INCONVENIENT  FORUM TO THE
MAINTENANCE OF SUCH SUIT OR PROCEEDING.  BOTH PARTIES FURTHER AGREE THAT SERVICE
OF  PROCESS  UPON A PARTY  MAILED BY FIRST  CLASS  MAIL SHALL BE DEEMED IN EVERY
RESPECT  EFFECTIVE  SERVICE  OF  PROCESS  UPON THE  PARTY  IN ANY  SUCH  SUIT OR
PROCEEDING. NOTHING HEREIN SHALL AFFECT EITHER PARTY'S RIGHT TO SERVE PROCESS IN
ANY  OTHER  MANNER   PERMITTED  BY  LAW.   BOTH  PARTIES   AGREE  THAT  A  FINAL
NON-APPEALABLE  JUDGMENT IN ANY SUCH SUIT OR PROCEEDING  SHALL BE CONCLUSIVE AND
MAY BE ENFORCED IN OTHER  JURISDICTIONS BY SUIT ON SUCH JUDGMENT OR IN ANY OTHER
LAWFUL MANNER.

         12.      Miscellaneous.

                  (a) Amendments. This Warrant and any provision hereof may only
be amended by an  instrument  in writing  signed by the  Company  and the holder
hereof.

                  (b)  Descriptive  Headings.  The  descriptive  headings of the
several  paragraphs of this Warrant are inserted for purposes of reference only,
and shall not  affect  the  meaning  or  construction  of any of the  provisions
hereof.

                  (c)  Cashless  Exercise.   Notwithstanding   anything  to  the
contrary  contained in this Warrant,  if the resale of the Warrant Shares by the
holder is not then registered  pursuant to an effective  registration  statement
under the  Securities  Act,  this Warrant may be exercised by  presentation  and
surrender of this Warrant to the Company at its principal executive offices with
a written  notice of the  holder's  intention  to  effect a  cashless  exercise,
including  a  calculation  of the number of shares of Common  Stock to be issued
upon such exercise in accordance with the terms hereof (a "Cashless  Exercise").
In the event of a Cashless  Exercise,  in lieu of paying the  Exercise  Price in
cash,  the holder  shall  surrender  this  Warrant  for that number of shares of
Common Stock  determined by multiplying the number of Warrant Shares to which it
would  otherwise be entitled by a fraction,  the numerator of which shall be the
difference  between the then current  Market Price per share of the Common Stock
and the Exercise  Price,  and the denominator of which shall be the then current
Market Price per share of Common Stock.

                  (d) Remedies.  The Company acknowledges that a breach by it of
its  obligations  hereunder  will cause  irreparable  harm to the holder of this
Warrant by  vitiating  the intent and purpose of the  transactions  contemplated
hereby.  Accordingly,  the  Company  acknowledges  that the  remedy at law for a
breach of its obligations  under this Warrant will be inadequate and agrees,  in
the event of a breach or threatened  breach by the Company of the  provisions of
this Warrant,  that the holder of this Warrant shall be entitled, in addition to
all  other  available  remedies  in  law  or  in  equity,  to an  injunction  or
injunctions  to prevent or cure any breaches of the provisions of this Agreement
and to enforce  specifically  the terms and provisions of this Warrant,  without
the necessity of showing  economic  loss and without any bond or other  security
being required.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
<PAGE>
         IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by
its duly authorized officer.

                                            TELIGENT, INC.

                                            By: /s/ Alex J. Mandl
                                            ____________________________________
                                                    Alex J. Mandl,
                                                    Chief Executive Officer

                                                    Dated as of December 7, 2000
<PAGE>

                           FORM OF EXERCISE AGREEMENT

                                                       Dated:  ___________, 2000

To: Teligent, Inc.

         The  undersigned,  pursuant to the  provisions  set forth in the within
Warrant,  hereby agrees to purchase  ________  shares of Common Stock covered by
such Warrant, and makes payment herewith in full therefor at the price per share
provided by such Warrant in cash or by  certified or official  bank check in the
amount of,  or, if the resale of such  Common  Stock by the  undersigned  is not
currently registered pursuant to an effective  registration  statement under the
Securities  Act of 1933, as amended,  by surrender of  securities  issued by the
Company  (including a portion of the Warrant) having a market value (in the case
of a portion of this Warrant, determined in accordance with Section 11(c) of the
Warrant) equal to $_________.  Please issue a certificate  or  certificates  for
such shares of Common  Stock in the name of and pay any cash for any  fractional
share to:

                                           Name:      __________________________

                                           Signature: __________________________
                                           Address:   __________________________
                                                      __________________________
                                                      __________________________

                                           Note:  The above signature should
                                                  correspond exactly with the
                                                  name on the face of the within
                                                  Warrant.

and,  if said  number  of shares of  Common  Stock  shall not be all the  shares
purchasable under the within Warrant,  a new Warrant is to be issued in the name
of said undersigned  covering the balance of the shares  purchasable  thereunder
less any fraction of a share paid in cash.
<PAGE>
                               FORM OF ASSIGNMENT

         FOR  VALUE  RECEIVED,   the  undersigned  hereby  sells,  assigns,  and
transfers  all the  rights of the  undersigned  under the within  Warrant,  with
respect  to the  number  of shares of Common  Stock  covered  thereby  set forth
hereinbelow, to:

Name of Assignee                     Address                    No of Shares
----------------                     -------                    ------------

,   and   hereby   irrevocably    constitutes   and   appoints    ______________
________________________  as agent and attorney-in-fact to transfer said Warrant
on the books of the within-named corporation, with full power of substitution in
the premises.

Dated:  ________ __, 200_

In the presence of:

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

                                          Name:       __________________________

                                          Signature:  __________________________

                                          Title of Signing Officer or Agent (if
                                             any):

                                          Address:    __________________________
                                                      __________________________
                                                      __________________________

                                           Note:  The above signature should
                                                  correspond exactly with the
                                                  name on the face of the within
                                                  Warrant.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00018-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00018-of-00352.parquet"}]]