<PAGE>   1

                                                    Registration No. 333-_______
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    Form S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            Global TeleSystems, Inc.
             (Exact name of registrant as specified in its charter)

         Delaware                                           94-3068423
  (State or other jurisdiction                           (I.R.S. Employer
       of organization)                                 Identification No.)

                                   ----------

                             4121 Wilson Boulevard
                                   7th Floor
                              Arlington, VA 22203
                                 (703) 258-3401
          (Address and telephone number of principal executive offices)

                                   ----------

          SECOND AMENDED AND RESTATED 2000 STOCK OPTION PLAN OF GLOBAL
                               TELESYSTEMS, INC.
                            (Full title of the plans)

                                   ----------

                             Grier C. Raclin, Esq.
                        4121 Wilson Boulevard, 7th Floor
                              Arlington, VA 22203
                                 (703) 258-3420
           (Name, address and telephone number of agent for service)

                         CALCULATION OF REGISTRATION FEE


<TABLE>
<CAPTION>
                Title of                         Amount           Proposed Maximum         Proposed Maximum        Amount of
            Securities to be                     to be           Offering Price Per           Aggregate           Registration
               Registered                      Registered             Share(1)            Offering Price(1)           Fee
-----------------------------------------  ------------------  ----------------------- ------------------------ ----------------
<S>                                             <C>                   <C>                   <C>                    <C>
Common Stock, par value $0.10 . . . . . .      15,000,000               $0.66                 $9,900,000             $2,475

-----------------------------------------  ------------------  ----------------------- ------------------------ ----------------
<FN>
(1)   The Proposed Maximum Offering Price Per Share and the Proposed Maximum
      Aggregate Offering Price are based on the average of the high and low
      prices of the Common Stock reported in the consolidated reporting system
      on the New York Stock Exchange on May 14, 2001, in accordance with Rule
      457(h) and Rule 457(c) under the Securities Act of 1933, as amended, and
      are being utilized solely for the purpose of calculating the registration
      fee.
</FN>
</TABLE>




<PAGE>   2


                                     Part I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.   Plan Information.*

Item 2.   Registrant Information and Employee Plan Annual Information.*






































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

*    Information required by Part I to be contained in the Section 10(a)
     prospectus is omitted from this Registration Statement in accordance with
     Rule 428 under the Securities Act, and the "Note" to Part I of Form S-8.


                                        2

<PAGE>   3


                                     PART II


               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3. Incorporation of Certain Documents by Reference.

                  The following documents which have been filed by Global
TeleSystems, Inc. (the "Registrant") with the Securities and Exchange Commission
(the "Commission") (or furnished by the Registrant to the Commission) are
incorporated by reference in this Registration Statement:

                  (a) the description of the Registrant's Common Stock, par
         value $0.10 per share, registered under Section 12 of the Securities
         Exchange Act of 1934, as amended (the "Exchange Act"), contained in the
         Form S-3 registration statement (Commission File No. 333-32760) filed
         with the Commission on April 19, 2000; and

                  (b) the Registrant's annual report on Form 10-K for the year
         ended December 31, 2000 filed with the Commission on April 13, 2001
         and the Amendment thereto filed with the Commission on April 30, 2001.

                  All documents subsequently filed by the Registrant pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a
post-effective amendment to this Registration Statement which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
Registration Statement and are a part thereof from the date of filing of such
documents.

                  Any statement contained in a document incorporated or deemed
incorporated by reference in this Registration Statement shall be deemed to be
modified or superseded for purposes of this Registration Statement to the extent
that a statement contained herein or in any other subsequently filed document
which also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed, except as so modified or superseded, to constitute a part of this
Registration Statement.


Item 4. Description of Securities.

                  Not Applicable.


Item 5. Interests of Named Experts and Counsel.

                  Not Applicable.





                                        3

<PAGE>   4


Item 6.           Indemnification of Directors and Officers.

                  Section 145 of the General Corporation Law of the State of
Delaware (the "DGCL") provides, in summary, that directors and officers of
Delaware corporations such as the Registrant are entitled, under certain
circumstances, to be indemnified against all expenses and liabilities (including
attorneys' fees) incurred by them as a result of suits brought against them in
their capacity as a director or officer if they acted in good faith and in a
manner they reasonably believed to be in or not opposed to the best interests of
the Registrant and, with respect to any criminal action or proceeding, if they
had no reasonable cause to believe their conduct was unlawful; provided that no
indemnification may be made against expenses in respect of any claim, issue or
matter as to which they shall have been adjudged to be liable to the Registrant,
unless and only to the extent that the court in which such action or suit was
brought shall determine upon application that, despite the adjudication of
liability but in view of all the circumstances of the case, they are fairly and
reasonably entitled to indemnity for such expenses which such court shall deem
proper. Any such indemnification may be made by the company only as authorized
in each specific case upon a determination by the stockholders or disinterested
directors that indemnification is proper because the indemnitee has met the
applicable standard of conduct.

                  Section 102(b)(7) of the DGCL permits a corporation to include
in its certificate of incorporation a provision eliminating or limiting the
personal liability of a director to the corporation or its stockholders for
monetary damages for breach of fiduciary duty as a director, provided that such
provision shall not eliminate or limit the liability of a director (i) for any
breach of the director's duty or loyalty to the corporation or its stockholders,
(ii) for acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL
(relating to unlawful payment of dividends and unlawful stock purchase and
redemption) or (iv) for any transaction from which the director derived an
improper personal benefit.

                  The Registrant's Certificate of Incorporation (the
"Certificate") provides that the Registrant's directors shall not be liable to
the Registrant or its stockholders for monetary damages for breach of fiduciary
duty as a director; provided, however, that such exculpation from liabilities is
not permitted with respect to liability arising from items described in clauses
(i) through (iv) in the preceding paragraph. The Certificate and the
Registrant's by-laws further provide that the Registrant shall indemnify its
directors and officers to the fullest extent permitted by the DGCL.

                  The directors and officers of the Registrant are covered under
directors' and officers' liability insurance policies maintained by the
Registrant.


Item 7. Exemption from Registration Claimed.

                  Not Applicable.


Item 8. Exhibits.

                  See Index to Exhibits.


Item 9.           Undertakings.

                  (a) The Registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
         being made, a post-effective amendment to this registration statement:


                                        4

<PAGE>   5


                           (i) to include any prospectus required by Section
                  10(a)(3) of the Securities Act;

                           (ii) to reflect in the prospectus any facts or events
                  arising after the effective date of the registration statement
                  (or the most recent post-effective amendment thereof) which,
                  individually or in aggregate, represent a fundamental change
                  in the information set forth in this registration statement.
                  Notwithstanding the foregoing, any increase or decrease in
                  volume of securities offered (if the total dollar value of
                  securities offered would not exceed that which was registered)
                  and any deviation from the low or high end of the estimated
                  maximum offering range may be reflected in the form of
                  prospectus filed with the Commission pursuant to Rule 424(b)
                  if, in the aggregate, the changes in volume and price
                  represent no more than a 20% change in the maximum aggregate
                  offering price set forth in the "Calculation of Registration
                  Fee" table in the effective registration statement; and

                           (iii) to include any material information with
                  respect to the plan of distribution not previously disclosed
                  in this registration statement or any material change to such
                  information in the registration statement;

         provided, however, that the undertakings set forth in paragraphs (1)(i)
         and (1)(ii) above do not apply if the information required to be
         included in a post-effective amendment by those paragraphs is contained
         in periodic reports filed by the Registrant pursuant to Section 13 or
         Section 15(d) of the Exchange Act that are incorporated by reference in
         this registration statement.

                  (2) That, for the purpose of determining any liability under
         the Securities Act, each such post-effective amendment shall be deemed
         to be a new registration statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

                  (3) To remove from registration by means of a post-effective
         amendment any of the securities being registered which remain unsold at
         the termination of the offering.

                  (b) The Registrant hereby undertakes that, for purposes of
determining liability under the Securities Act, each filing of the Registrant's
annual report on Form 10-K pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and each filing of an employee benefit plan annual report pursuant
to Section 15(d) of the Exchange Act) that is incorporated by reference in this
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

                  (c) Insofar as indemnification for liabilities arising under
the Securities Act may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the SEC such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer, or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.


                                        5

<PAGE>   6


                                   SIGNATURES


    Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has duly caused this Registration Statement to be
signed on its behalf by the undersigned, thereunto duly authorized, in the
County of Arlington, Commonwealth of Virginia, on this 15th day of May 2001.


                                        GLOBAL TELESYSTEMS, INC.

                                        By: /s/ ROBERT J. AMMAN
                                            ----------------------------
                                        Name: Robert J. Amman
                                        Title: Chairman
                                        and Chief Executive Officer


                                POWER OF ATTORNEY

    We, the undersigned officers and directors of Global TeleSystems, Inc.
hereby severally constitute and appoint, Grier C. Raclin, Robert A. Schriesheim
and Arnold Y. Dean, and each of them, with full power of substitution, our true
and lawful attorney with full power to him singly to sign for us and in our
names in the capacities indicated below the Registration Statement on Form S-8
filed herewith and any and all pre-effective and post-effective amendments to
said Registration Statement, and, in connection with any registration of
additional securities pursuant to Rule 462(b) under the Securities Act of 1933,
as amended, to sign any abbreviated registration statement and any and all
amendments thereto, and to file the same, with all exhibits thereto and other
documents in connection therewith, in each case, with the Securities and
Exchange Commission, and generally to do all such things in our names and on our
behalf in our capacities as officers and directors to enable Global TeleSystems
Group, Inc. to comply with the provisions of the Securities Act of 1933, as
amended, and all requirements of the Securities and Exchange Commission, hereby
ratifying and confirming our signatures as they may be signed by our said
attorney to said Registration Statement and any and all amendments thereto.

    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities indicated on the 15th day of May 2001.


                 Signature                                    Title
                 ---------                                    -----

     /s/ Robert J. Amman                      Chairman and Chief Executive
     ------------------------------             Officer (principal executive
               Robert J. Amman                  officer)

     /s/ Robert A. Schriesheim                Executive Vice President --
     ------------------------------             Corporate Development
         Robert A. Schriesheim                  Finance and Chief Financial
                                                Officer (principal financial
                                                officer)


                                        6

<PAGE>   7


                Signature                                     Title



     /s/ Jeffrey H. Von Deylen                Senior Vice President -- Finance
     ------------------------------             (Principal Accounting Officer)
         Jeffrey H. Von Deylen

     /s/ Alan B. Slifka                       Vice Chairman of the
     ------------------------------             Board of Directors
             Alan B. Slifka

     /s/ David Dey                            Director
     ------------------------------
                David Dey

     /s/ Bernard McFadden                     Director
     ------------------------------
            Bernard McFadden


                                              Director
     ------------------------------
           Stewart J. Paperin


     /s/ W. James Peet                        Director
     ------------------------------
              W. James Peet

     /s/ Jean Salmona                         Director
     ------------------------------
              Jean Salmona

                                              Director
     ------------------------------
              Frank V. Sica

     /s/ Adam Solomon                         Director
     ------------------------------
              Adam Solomon

     /s/ Gerald W. Thames                     Director
     ------------------------------
            Gerald W. Thames





                                        7

<PAGE>   8


                                  Exhibit Index

Exhibit No.           Description of Document

4.1                 Second Amended and Restated 2000 Stock Option Plan of
                    Global TeleSystems, Inc. (incorporated by reference to
                    Exhibit 10.11 of the Company's Annual Report on Form 10-K
                    for the year ended December 31, 2000).

5                   Opinion of the Registrant's In-house legal counsel as to the
                    legality of the securities registered hereby.

23.1                Consent of Ernst & Young LLP, Independent Auditors

23.2                Consent of PricewaterhouseCoopers, Independent Accountants

23.3                Consent of Registrant's in-house counsel (included in
                    Exhibit 5)

24                  Powers of Attorney (included on signature page).










                                        8
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{"company-data": {"conformed-name": "GLOBAL TELESYSTEMS INC", "cik": "0000946392", "assigned-sic": "4813", "irs-number": "943068423", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-60932", "film-number": "1637750"}, "business-address": {"street1": "4121 WILSON BLVD", "street2": "8TH FLOOR", "city": "ARLINGTON", "state": "VA", "zip": "22203", "phone": "7032363100"}, "former-company": {"former-conformed-name": "GLOBAL TELESYSTEMS GROUP INC", "date-changed": "19970912"}}
1

                                                    Registration No. 333-_______
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    Form S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            Global TeleSystems, Inc.
             (Exact name of registrant as specified in its charter)

         Delaware                                           94-3068423
  (State or other jurisdiction                           (I.R.S. Employer
       of organization)                                 Identification No.)

                                   ----------

                             4121 Wilson Boulevard
                                   7th Floor
                              Arlington, VA 22203
                                 (703) 258-3401
          (Address and telephone number of principal executive offices)

                                   ----------

          SECOND AMENDED AND RESTATED 2000 STOCK OPTION PLAN OF GLOBAL
                               TELESYSTEMS, INC.
                            (Full title of the plans)

                                   ----------

                             Grier C. Raclin, Esq.
                        4121 Wilson Boulevard, 7th Floor
                              Arlington, VA 22203
                                 (703) 258-3420
           (Name, address and telephone number of agent for service)

                         CALCULATION OF REGISTRATION FEE
Title of                         Amount           Proposed Maximum         Proposed Maximum        Amount of
            Securities to be                     to be           Offering Price Per           Aggregate           Registration
               Registered                      Registered             Share(1)            Offering Price(1)           Fee
-----------------------------------------  ------------------  ----------------------- ------------------------ ----------------
Common Stock, par value $0.10 . . . . . .      15,000,000               $0.66                 $9,900,000             $2,475

-----------------------------------------  ------------------  ----------------------- ------------------------ ----------------
(1)   The Proposed Maximum Offering Price Per Share and the Proposed Maximum
      Aggregate Offering Price are based on the average of the high and low
      prices of the Common Stock reported in the consolidated reporting system
      on the New York Stock Exchange on May 14, 2001, in accordance with Rule
      457(h) and Rule 457(c) under the Securities Act of 1933, as amended, and
      are being utilized solely for the purpose of calculating the registration
      fee.
2

                                     Part I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.   Plan Information.*

Item 2.   Registrant Information and Employee Plan Annual Information.*

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

*    Information required by Part I to be contained in the Section 10(a)
     prospectus is omitted from this Registration Statement in accordance with
     Rule 428 under the Securities Act, and the "Note" to Part I of Form S-8.

                                        2
3

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Certain Documents by Reference.

                  The following documents which have been filed by Global
TeleSystems, Inc. (the "Registrant") with the Securities and Exchange Commission
(the "Commission") (or furnished by the Registrant to the Commission) are
incorporated by reference in this Registration Statement:

                  (a) the description of the Registrant's Common Stock, par
         value $0.10 per share, registered under Section 12 of the Securities
         Exchange Act of 1934, as amended (the "Exchange Act"), contained in the
         Form S-3 registration statement (Commission File No. 333-32760) filed
         with the Commission on April 19, 2000; and

                  (b) the Registrant's annual report on Form 10-K for the year
         ended December 31, 2000 filed with the Commission on April 13, 2001
         and the Amendment thereto filed with the Commission on April 30, 2001.

                  All documents subsequently filed by the Registrant pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a
post-effective amendment to this Registration Statement which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
Registration Statement and are a part thereof from the date of filing of such
documents.

                  Any statement contained in a document incorporated or deemed
incorporated by reference in this Registration Statement shall be deemed to be
modified or superseded for purposes of this Registration Statement to the extent
that a statement contained herein or in any other subsequently filed document
which also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed, except as so modified or superseded, to constitute a part of this
Registration Statement.

Item 4. Description of Securities.

                  Not Applicable.

Item 5. Interests of Named Experts and Counsel.

                  Not Applicable.

                                        3
4

Item 6.           Indemnification of Directors and Officers.

                  Section 145 of the General Corporation Law of the State of
Delaware (the "DGCL") provides, in summary, that directors and officers of
Delaware corporations such as the Registrant are entitled, under certain
circumstances, to be indemnified against all expenses and liabilities (including
attorneys' fees) incurred by them as a result of suits brought against them in
their capacity as a director or officer if they acted in good faith and in a
manner they reasonably believed to be in or not opposed to the best interests of
the Registrant and, with respect to any criminal action or proceeding, if they
had no reasonable cause to believe their conduct was unlawful; provided that no
indemnification may be made against expenses in respect of any claim, issue or
matter as to which they shall have been adjudged to be liable to the Registrant,
unless and only to the extent that the court in which such action or suit was
brought shall determine upon application that, despite the adjudication of
liability but in view of all the circumstances of the case, they are fairly and
reasonably entitled to indemnity for such expenses which such court shall deem
proper. Any such indemnification may be made by the company only as authorized
in each specific case upon a determination by the stockholders or disinterested
directors that indemnification is proper because the indemnitee has met the
applicable standard of conduct.

                  Section 102(b)(7) of the DGCL permits a corporation to include
in its certificate of incorporation a provision eliminating or limiting the
personal liability of a director to the corporation or its stockholders for
monetary damages for breach of fiduciary duty as a director, provided that such
provision shall not eliminate or limit the liability of a director (i) for any
breach of the director's duty or loyalty to the corporation or its stockholders,
(ii) for acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL
(relating to unlawful payment of dividends and unlawful stock purchase and
redemption) or (iv) for any transaction from which the director derived an
improper personal benefit.

                  The Registrant's Certificate of Incorporation (the
"Certificate") provides that the Registrant's directors shall not be liable to
the Registrant or its stockholders for monetary damages for breach of fiduciary
duty as a director; provided, however, that such exculpation from liabilities is
not permitted with respect to liability arising from items described in clauses
(i) through (iv) in the preceding paragraph. The Certificate and the
Registrant's by-laws further provide that the Registrant shall indemnify its
directors and officers to the fullest extent permitted by the DGCL.

                  The directors and officers of the Registrant are covered under
directors' and officers' liability insurance policies maintained by the
Registrant.

Item 7. Exemption from Registration Claimed.

                  Not Applicable.

Item 8. Exhibits.

                  See Index to Exhibits.

Item 9.           Undertakings.

                  (a) The Registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
         being made, a post-effective amendment to this registration statement:

                                        4
5

                           (i) to include any prospectus required by Section
                  10(a)(3) of the Securities Act;

                           (ii) to reflect in the prospectus any facts or events
                  arising after the effective date of the registration statement
                  (or the most recent post-effective amendment thereof) which,
                  individually or in aggregate, represent a fundamental change
                  in the information set forth in this registration statement.
                  Notwithstanding the foregoing, any increase or decrease in
                  volume of securities offered (if the total dollar value of
                  securities offered would not exceed that which was registered)
                  and any deviation from the low or high end of the estimated
                  maximum offering range may be reflected in the form of
                  prospectus filed with the Commission pursuant to Rule 424(b)
                  if, in the aggregate, the changes in volume and price
                  represent no more than a 20% change in the maximum aggregate
                  offering price set forth in the "Calculation of Registration
                  Fee" table in the effective registration statement; and

                           (iii) to include any material information with
                  respect to the plan of distribution not previously disclosed
                  in this registration statement or any material change to such
                  information in the registration statement;

         provided, however, that the undertakings set forth in paragraphs (1)(i)
         and (1)(ii) above do not apply if the information required to be
         included in a post-effective amendment by those paragraphs is contained
         in periodic reports filed by the Registrant pursuant to Section 13 or
         Section 15(d) of the Exchange Act that are incorporated by reference in
         this registration statement.

                  (2) That, for the purpose of determining any liability under
         the Securities Act, each such post-effective amendment shall be deemed
         to be a new registration statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

                  (3) To remove from registration by means of a post-effective
         amendment any of the securities being registered which remain unsold at
         the termination of the offering.

                  (b) The Registrant hereby undertakes that, for purposes of
determining liability under the Securities Act, each filing of the Registrant's
annual report on Form 10-K pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and each filing of an employee benefit plan annual report pursuant
to Section 15(d) of the Exchange Act) that is incorporated by reference in this
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

                  (c) Insofar as indemnification for liabilities arising under
the Securities Act may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the SEC such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer, or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                        5
6

                                   SIGNATURES

    Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has duly caused this Registration Statement to be
signed on its behalf by the undersigned, thereunto duly authorized, in the
County of Arlington, Commonwealth of Virginia, on this 15th day of May 2001.

                                        GLOBAL TELESYSTEMS, INC.

                                        By: /s/ ROBERT J. AMMAN
                                            ----------------------------
                                        Name: Robert J. Amman
                                        Title: Chairman
                                        and Chief Executive Officer

                                POWER OF ATTORNEY

    We, the undersigned officers and directors of Global TeleSystems, Inc.
hereby severally constitute and appoint, Grier C. Raclin, Robert A. Schriesheim
and Arnold Y. Dean, and each of them, with full power of substitution, our true
and lawful attorney with full power to him singly to sign for us and in our
names in the capacities indicated below the Registration Statement on Form S-8
filed herewith and any and all pre-effective and post-effective amendments to
said Registration Statement, and, in connection with any registration of
additional securities pursuant to Rule 462(b) under the Securities Act of 1933,
as amended, to sign any abbreviated registration statement and any and all
amendments thereto, and to file the same, with all exhibits thereto and other
documents in connection therewith, in each case, with the Securities and
Exchange Commission, and generally to do all such things in our names and on our
behalf in our capacities as officers and directors to enable Global TeleSystems
Group, Inc. to comply with the provisions of the Securities Act of 1933, as
amended, and all requirements of the Securities and Exchange Commission, hereby
ratifying and confirming our signatures as they may be signed by our said
attorney to said Registration Statement and any and all amendments thereto.

    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities indicated on the 15th day of May 2001.

                 Signature                                    Title
                 ---------                                    -----

     /s/ Robert J. Amman                      Chairman and Chief Executive
     ------------------------------             Officer (principal executive
               Robert J. Amman                  officer)

     /s/ Robert A. Schriesheim                Executive Vice President --
     ------------------------------             Corporate Development
         Robert A. Schriesheim                  Finance and Chief Financial
                                                Officer (principal financial
                                                officer)

                                        6
7

                Signature                                     Title

     /s/ Jeffrey H. Von Deylen                Senior Vice President -- Finance
     ------------------------------             (Principal Accounting Officer)
         Jeffrey H. Von Deylen

     /s/ Alan B. Slifka                       Vice Chairman of the
     ------------------------------             Board of Directors
             Alan B. Slifka

     /s/ David Dey                            Director
     ------------------------------
                David Dey

     /s/ Bernard McFadden                     Director
     ------------------------------
            Bernard McFadden

                                              Director
     ------------------------------
           Stewart J. Paperin

     /s/ W. James Peet                        Director
     ------------------------------
              W. James Peet

     /s/ Jean Salmona                         Director
     ------------------------------
              Jean Salmona

                                              Director
     ------------------------------
              Frank V. Sica

     /s/ Adam Solomon                         Director
     ------------------------------
              Adam Solomon

     /s/ Gerald W. Thames                     Director
     ------------------------------
            Gerald W. Thames

                                        7
8

                                  Exhibit Index

Exhibit No.           Description of Document

4.1                 Second Amended and Restated 2000 Stock Option Plan of
                    Global TeleSystems, Inc. (incorporated by reference to
                    Exhibit 10.11 of the Company's Annual Report on Form 10-K
                    for the year ended December 31, 2000).

5                   Opinion of the Registrant's In-house legal counsel as to the
                    legality of the securities registered hereby.

23.1                Consent of Ernst & Young LLP, Independent Auditors

23.2                Consent of PricewaterhouseCoopers, Independent Accountants

23.3                Consent of Registrant's in-house counsel (included in
                    Exhibit 5)

24                  Powers of Attorney (included on signature page).

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