Document:

<PAGE>

                                                                     Exhibit 4.4

                               ESCROW AGREEMENT

         THIS ESCROW AGREEMENT is made and entered into as of June 6, 2000 by
and among American TeleSource International, Inc., a Delaware corporation
("ATSI"), Alfonso Torres Roqueni, an individual residing in Mexico City, Mexico
("Torres") and Laredo National Bank, a national banking association with its
principal offices in Laredo, County, Texas (the "Bank" or "Escrow Agent").

                                   RECITALS

      A.  Torres owns 277,082 shares of the capital stock of Grupo Intelcom de
          Mexico, S.A. de C.V., a Mexican corporation ("Grupo") (the "Grupo
          Stock");

      B.  Torres owns 99.9% of the stock of Telemarketing de Mexico, S.A. de
          C.V., a Mexican corporation ("Telemarketing") (the "Telemarketing
          Stock");

      C.  Rodolfo Torres Roqueni ("RTorres") owns .1% of the stock of
          Telemarketing ("RTorresStock");

      D.  ATSI, Torres, Grupo and Telemarketing have entered into an Agreement
          dated effective June 6, 2000 (the "Agreement") pursuant to which
          Torres has sold 16,300 shares of Grupo, representing 3% of the issued
          and outstanding capital stock of Grupo (the "3% Stock"), to certain
          individuals designated by ATSI.

      E.  The Agreement provides that Torres will transfer control of his
          remaining 260,782 shares of Grupo, representing 48% of the issued and
          outstanding capital stock of Grupo (the "48%Stock") to the persons
          designated by ATSI, and that Torres will perform certain consulting
          services for ATSI.

      F.  The Agreement provides that in consideration for the sale of the
          3%Stock, the transfer of the control of the 48%Stock to the persons
          designated by ATSI, and the performance of the services, ATSI will pay
          and deliver to Torres or the persons designated by Torres 50,000
          shares of ATSI common stock (the "First ATSI Shares"), 350,000 shares
          of ATSI common stock (the "Second ATSI Shares"), a note in the
          original principal amount of $500,000 (the "Note"), and a warrant for
          the purchase of 100,000 shares of ATSI common stock (the "Warrant").

      G.  The Agreement provides that delivery of irrevocable instructions to
          ATSI's transfer agent to issue the First ATSI Shares and the Second
          ATSI Shares shall constitute delivery of the First ATSI Shares and the
          Second ATSI Shares;

      H.  ATSI's transfer agent is ChaseMellon Shareholder Services, LLC or the
          agent that it may subsequently appoint for the purpose of serving as
          transfer agent for ATSI's common stock (the "Transfer Agent");

                                       1
<PAGE>

      I.  The Agreement provides that Torres will transfer control of the
          48%Stock by transfering the 48%Stock to Telemarketing, causing RTorres
          to Transfer the RTorres Stock to the person or person designated by
          ATSI, and agreeing to refrain from exercising his preemptive rights to
          increase the capital of Telemarketing (the "Telemarketing Waiver");
          Pursuant to the Agreement, Torres has granted to the ATSI designees a
          security interest in the Telemarketing Stock to secure his obligation
          not to revoke the Telemarketing Waiver.

      J.  The Agreement provides that if Torres is unable to obtain regulatory
          approval from the appropriate agencies of the Mexican government to
          achieve the transfer of control described in paragraph I above by July
          31, 2000, Torres and ATSI will find an alternative way to achieve
          transfer of control of the 48%Stock, and Torres will grant ATSI's
          designees a Poder General (or general power of administration) so that
          they can manage Grupo until an alternative method to achieve transfer
          of control is obtained.

      K.  The Agreement requires the 3%Stock, the 48%StockTorres, the RTorres
          Stock instructions to the Transfer Agent to deliver the First ATSI
          Shares (the "First ATSI Shares Instruction"), instructions to the
          Transfer Agent to issue the Second ATSI Shares (the "Second ATSI
          Shares Instruction"), the Note, the Warrant, the Telemarketing Waiver,
          the Telemarketing Stock, an assignment of the Telemarketing Stock (the
          "Telemarketing Stock Assignment"), and the Poder General to be held in
          escrow pending the resolution of certain contingencies.

      L.  ATSI and Torres have requested Escrow Agent to act in the capacity of
          escrow agent under this Escrow Agreement, and Escrow Agent, subject to
          the terms and conditions hereof, has agreed to do so.

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

               1.   Appointment of Escrow Agent.  Each of ATSI and Torres hereby
appoints the Bank as the escrow agent under this Escrow Agreement and the Bank
hereby accepts such appointment.

               2.   Deposit.  Upon execution of this Escrow Agreement, ATSI will
deliver to the Escrow Agent the First ATSI Shares Instruction, the Second ATSI
Shares Instruction, the Note, and the Warrant, and Torres will deliver to the
Escrow Agent the Grupo Stock endorsed in blank, the RTorres Stock endorsed in
blank, the Telemarketing Waiver the Poder General, the Telemarketing Stock
endorsed in blank, and the Telemarketing Stock Assignment, all to be held by
Escrow Agent in accordance with the terms of this Agreement (the "Deposit").
Escrow Agent agrees that it shall receive, hold in escrow and release the
Deposit subject to and in accordance with the terms of this Agreement. The
parties agree that ATSI and Grupo will determine if the form and substance of
the items constituting the Deposit are sufficient and acceptable under the terms
of the Agreement and that Escrow Agent shall have no responsibility whatsoever
to determine if the items constituting the Deposit are valid, sufficient, or
otherwise acceptable.

               3.   Disbursement of Deposit. Escrow Agent is hereby authorized
to release the Deposit only as follows:

               (a)  Upon Torres' delivery of two replacement certificates for
the certificate for the Grupo Stock (whereby the certificate for 277,082 shares
of Grupo is to be replaced by two

                                       2
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certificates, one for 16,300 shares (representing the 3%Stock) and one for
260,782 shares of Grupo (representing the 48%Stock)) the Escrow Agent will
accept the certificates for the 3%Stock and the 48%Stock as part of the Deposit,
will cancel the stock certificate for the Grupo Stock by writing CANCEL on the
front and back of the certificate and will return the cancelled certificate for
the Grupo Stock to Torres.

               (b)  if the Escrow Agent receives a Release of Escrow in the form
attached as Exhibit A executed by ATSI and Torres (the "First Escrow Release"),
            ---------
the Escrow Agent shall:

               (i)   disburse the 3%Stock (or, if no replacement certificates
                     have been provided pursuant to subparagraph (a) above, the
                     Grupo Stock) to ATSI or the persons or persons designated
                     by ATSI in the First Escrow Release, and

               (ii)  disburse the First ATSI Shares Instruction to the Transfer
                     Agent;

               (c)   if the Escrow Agent receives a Release of Escrow in the
form attached as Exhibit B executed by ATSI and Torres (the "Second Escrow
                 ---------
Release") the Escrow Agent shall:

               (i)   endorse the 48%Stock to "Telemarketing of Mexico, S.A. de
                     C.V.".

               (ii)  disburse the endorsed 48%Stock to Torres,

               (iii) disburse the Telemarketing Waiver and the RTorres Stock to
                     ATSI,

               (iv)  disburse the Second ATSI Shares Instruction to the Transfer
                     Agent,

               (v)   disburse the Note and the Warrant to Torres or to any
                     person or persons designated by Torres in the Second Escrow
                     Release, and

               (vi)  destroy the Telemarketing Assignment and return the
                     Telemarketing Stock to Torres, and

               (vii) destroy the Poder General;

               (d)   if the Escrow Agent receives a Release of Escrow in the
form attached as Exhibit C executed by ATSI and Torres (the "Simultaneous Escrow
                 ---------
Release"), the Escrow Agent shall:distribute all of the items required to be
distributed on a First Escrow Release and a Second Escrow Release as provided in
subparagraphs 3(b) and 3(c) above.

               (e)   if after July 31, 2000 the Escrow Agent receives a Release
of Escrow in the form attached as Exhibit D executed by ATSI (the "Alternative
                                  ---------
Escrow Release"), the Escrow Agent shall disburse the Poder General to ATSI.

               (f)   If the Escrow Agent receives after the Escrow Termination
Date, as defined below, the Termination of Escrow attached as Exhibit E executed
                                                              ---------
by ATSI (the "Termination of Escrow") the Escrow Agent shall:

                                       3
<PAGE>

               (i)   disburse to ATSI the First ATSI Shares Instruction (if not
                     already disbursed to the Transfer Agent pursuant to Section
                     3(a) above) the Second ATSI Shares Instruction, the Note
                     and the Warrant, and

               (ii)  disburse to Torres the 3%Stock (if not already disbursed to
                     ATSI pursuant to Section 3(a) above), the 48%Stock, The
                     RTorres Stock, the Telemarketing Waiver, and the Grupo
                     Waiver;

               The "Escrow Termination Date" shall be August 31, 2000 or such
               later date specified by ATSI and Torres in a joint instruction to
               the Escrow Agent in form and substance satisfactory to Escrow
               Agent.

               (g)   into the registry of the court in accordance with this
Escrow Agreement; and.

               (h)   in such other manner as provided in a written modification
to this Escrow Agreement executed by all parties.

Disbursements by the Escrow Agent shall be made on the day it receives the
original of the fully executed First Release, Second Release, the Simultaneous
Escrow Release, the Alternative Escrow Release or Escrow Termination, as the
case may be, via overnight mail on a "priority" basis, using Federal Express or
UPS. If to ATSI or Torres, disbursements shall be made to the address appearing
for ATSI or Torres in Section 9, below (or such other address given in a notice
by ATSI or Torres in accordance with that Section); if to the Transfer Agent, to
the address stated in the First ATSI Shares Instruction and Second ATSI Shares
Instruction or to such other address provided to the Escrow Agent jointly by
ATSI and Torres; and if to a person or person designated by Torres or ATSI, to
the address stated in the First Escrow Release or Second Escrow Release, the
Simultaneous Escrow Release or the Alternative Escrow Release, as the case may
be.

               4.   Scope of Undertaking. Escrow Agent's duties and
responsibilities in connection with this Escrow Agreement shall be purely
ministerial and shall be limited to those expressly set forth in this Escrow
Agreement. Escrow Agent is not a principal, participant or beneficiary in any
transaction underlying this Escrow Agreement and shall have no duty to inquire
beyond the terms and provisions hereof. Escrow Agent shall not be liable for any
error in judgment, any act or omission, any mistake of law or fact, or for
anything it may do or refrain from doing in good faith in connection herewith,
except for, subject to Section 5 below, its own willful misconduct or
negligence. The Escrow Agent shall never be required to use, advance or risk its
own funds or otherwise incur financial liability in the performance of any of
its duties or the exercise of any of its rights and powers hereunder.

               5.   Reliance; Liability. Escrow Agent may rely on, and shall not
be liable for acting or refraining from acting in accordance with, any written
notice, instruction or request or other paper furnished to it hereunder or
pursuant hereto and believed by it to have been signed or presented by the
proper party or parties, provided that it verbally confirms the instruction to
with the person at the telephone number provided in Section 9, below. Escrow
Agent shall be responsible for holding and disbursing the Deposit pursuant to
this Escrow Agreement; provided, however, that in no event shall Escrow Agent be
liable for any lost profits, lost savings or other special, exemplary,
consequential or incidental damages in excess of Escrow Agent's fee hereunder

                                       4
<PAGE>

and provided, further, that Escrow Agent shall have no liability for any loss
arising from any cause beyond its control, including, but not limited to, the
following: (a) acts of God, force majeure, including, without limitation, war
(whether or not declared or existing), revolution, insurrection, riot, civil
commotion, accident, fire, explosion, stoppage of labor, strikes and other
differences with employees; (b) the act, failure or neglect of any ATSI or
Torres or any agent or correspondent or any other person selected by Escrow
Agent; (c) any delay, error, omission or default of any mail, courier,
telegraph, cable or wireless agency or operator; or (d) the acts or edicts of
any government or governmental agency or other group or entity exercising
governmental powers. Escrow Agent is not responsible or liable in any manner
whatsoever for the sufficiency, correctness, genuineness or validity of the
subject matter of this Escrow Agreement or any part hereof or for the
transaction or transactions requiring or underlying the execution of this Escrow
Agreement, the form or execution hereof or for the identity or authority of any
person executing this Escrow Agreement or any part hereof or depositing the
Deposit.

               6.   Right of Interpleader. Should any controversy arise
involving the parties hereto or any of them or any other person, firm or entity
with respect to this Escrow Agreement or the Deposit, or should a substitute
escrow agent fail to be designated as provided in Section 12 hereof, or if
Escrow Agent should be in doubt as to what action to take, Escrow Agent shall
have the right, but not the obligation, either to (a) withhold delivery of the
Deposit until the controversy is resolved, the conflicting demands are withdrawn
or its doubt is resolved or (b) institute a petition for interpleader in any
court of competent jurisdiction to determine the rights of the parties hereto.
In the event Escrow Agent is a party to any dispute, Escrow Agent shall have the
additional right to refer such controversy to binding arbitration. Should a
petition for interpleader be instituted, or should Escrow Agent be threatened
with litigation or become involved in litigation or binding arbitration in any
manner whatsoever in connection with this Escrow Agreement or the Deposit, ATSI
and Torres hereby jointly and severally agree to reimburse Escrow Agent for its
attorneys' fees and any and all other expenses, losses, costs and damages
incurred by Escrow Agent in connection with or resulting from such threatened or
actual litigation or arbitration prior to any disbursement hereunder.

               7.   Indemnification. ATSI and Torres hereby jointly and
severally indemnify Escrow Agent, its officers, directors, partners, employees
and agents (each herein called an "Indemnified Party") against, and hold each
Indemnified Party harmless from, any and all expenses, including, without
limitation, attorneys' fees and court costs, losses, costs, damages and claims,
including, but not limited to, costs of investigation, litigation and
arbitration, tax liability and loss on investments suffered or incurred by any
Indemnified Party in connection with or arising from or out of this Escrow
Agreement, except such acts or omissions as may result from the willful
misconduct or gross negligence of such Indemnified Party. IT IS THE EXPRESS
INTENT OF EACH OF ATSI AND TORRES TO INDEMNIFY EACH OF THE INDEMNIFIED PARTIES
FOR, AND HOLD THEM HARMLESS AGAINST, THEIR OWN NEGLIGENT ACTS OR OMISSIONS.

               8.   Compensation and Reimbursement of Expenses. ATSI and Torres
agrees to each pay one half of the Escrow Agent's fees for its services
hereunder in accordance with Escrow Agent's fee schedule as in effect from time
to time and to each pay one half of all expenses incurred by Escrow Agent in
connection with the performance of its duties and enforcement of its rights
hereunder and otherwise in connection with the preparation, operation,
administration and enforcement of this Escrow Agreement, including, without
limitation, attorneys' fees and related expenses incurred by Escrow Agent. The
foregoing notwithstanding, ATSI and Torres shall be jointly and severally liable
to Escrow Agent for the payment of all such fees and expenses.

                                       5
<PAGE>

               9.   Notices. Any notice required or permitted to be given under
this Escrow Agreement must be in writing and shall be sent via facsimile with
the original to deposited with Federal Express or UPS for priority next day
delivery on the same day that the facsimile is sent. Provided the original of
the notice is delivered by Federal Express or UPS on the following day, notices
will be considered given and received on the date sent via facsimile as shown on
a written confirmation generated by the sending facsimile machine. Notices shall
be sent to the following address, or to such other address provided by a party
by a notice in accordance with this section:

               If to Escrow Agent:

                              Laredo National Bank
                              914 Hidalgo Street
                              Laredo, Texas 78040
                              Telefax: (956) 723-1151
                              Telephone: (956) 764-1592

               If to ATSI:           American TeleSource International, Inc.
                                     6000 Northwest Parkway, Suite 110
                                     San Antonio, Texas 78249
                                     Attn: Arthur L. Smith
                                     Telefax: (210)547- ______
                                     Telephone: (210) 547-1000

               If to Torres:         Alfonso Torres Roqueni
                                     Renato Leduc No. 321
                                     Col. Toriello Guerra, 01450
                                     Mexico, Distrito Federal
                                     Telefax: (5) 528-2100
                                     Telephone: (5) 528-2321

               10.  Consultation with Legal Counsel. Escrow Agent may consult
with its counsel or other counsel satisfactory to it concerning any question
relating to its duties or responsibilities hereunder or otherwise in connection
herewith and shall not be liable for any action taken, suffered or omitted by it
in good faith upon the advice of such counsel.

               11.  Choice of Laws. THIS ESCROW AGREEMENT AND THE RIGHTS AND
OBLIGATIONS OF THE PARTIES SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN
ACCORDANCE WITH THE SUBSTANTIVE LAWS (BUT NOT THE RULES GOVERNING CONFLICTS OF
LAWS) OF THE STATE OF DELAWARE, U.S.A. The parties agree that any action in
connection with this Escrow Agreement may be brought only in a state or federal
court in Delaware, U.S.A., and the parties waive any objection to the venue of
any such suit. The parties irrevocably consent to the service of process of any
such courts in any such action or proceeding by the mailing of copies thereof by
registered or certified mail, postage prepaid, return receipt requested, to the
party at the address set forth in this Escrow Agreement, and agree that such
service shall become effective ten (10) days after such mailing. However,
nothing herein shall affect the right of a party to serve process in any other
manner permitted by law.

                                       6
<PAGE>

               12.  Resignation. Escrow Agent may resign hereunder upon ten (10)
days' prior notice to ATSI and Torres. Upon the effective date of such
resignation, Escrow Agent shall deliver the Deposit to any substitute escrow
agent designated by ATSI and Torres in writing. If ATSI and Torres fail to
designate a substitute escrow agent within ten (10) days after the giving of
such notice, Escrow Agent may institute a petition for interpleader. Escrow
Agent's sole responsibility after such 10-day notice period expires shall be to
hold the Deposit (without any obligation to reinvest the same) and to deliver
the same to a designated substitute escrow agent, if any, or in accordance with
the directions of a final order or judgment of a court of competent
jurisdiction, at which time of delivery Escrow Agent's obligations hereunder
shall cease and terminate.

               13.  Assignment. This Escrow Agreement shall not be assigned by
either of ATSI or Torres without the prior written consent of Escrow Agent (such
assigns of ATSI or Torres to which Escrow Agent consents, if any, and Escrow
Agent's assigns being hereinafter referred to collectively as "Permitted
Assigns").

               14.  Severability. If one or more of the provisions hereof shall
for any reason be held to be invalid, illegal or unenforceable in any respect
under applicable law, such invalidity, illegality or unenforceability shall not
affect any other provisions hereof, and this Escrow Agreement shall be construed
as if such invalid, illegal or unenforceable provision had never been contained
herein, and the remaining provisions hereof shall be given full force and
effect.

               15.  Termination. This Escrow Agreement shall terminate upon the
disbursement, in accordance with Sections 3l; provided, however, that in the
event all fee, expenses, costs and other amounts required to be paid to Escrow
Agent hereunder are not fully and finally paid prior to termination, the
provisions of Section 8 shall survive the termination and, provided further,
that the provisions of Section 9 shall, in any event, survive the termination
hereof.

               16.  General. The section headings contained in this Escrow
Agreement are for reference purposes only and shall not affect in any way the
meaning or interpretation of this Escrow Agreement. This Escrow Agreement and
any affidavit, certificate, instrument, agreement or other document required to
be provided hereunder may be executed in two or more counterparts, each of which
shall be deemed an original, but all of which taken together shall constitute
but one and the same instrument. Unless the context shall otherwise require, the
singular shall include the plural and vice-versa, and each pronoun in any gender
shall include all other genders. The terms and provisions of this Escrow
Agreement constitute the entire agreement among the parties hereto in respect of
the subject matter hereof, and neither ATSI, Torres, nor Escrow Agent has relied
on any representations or agreements of the other, except as specifically set
forth in this Escrow Agreement. This Escrow Agreement or any provision hereof
may be amended, modified, waived or terminated only by written instrument duly
signed by the parties hereto. This Escrow Agreement shall inure to the benefit
of, and be binding upon, the parties hereto and their respective heirs,
devisees, executors, administrators, personal representatives, successors,
trustees, receivers and Permitted Assigns. This Escrow Agreement is for the sole
and exclusive benefit of ATSI, Torres, and the Escrow Agent, and nothing in this
Escrow Agreement, express or implied, is intended to confer or shall be
construed as conferring upon any other person any rights, remedies or any other
type or types of benefits.

                  REMAINDER OF PAGE INTENTIONALLY LEFT BLANK

                                       7
<PAGE>

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

                                   American TeleSource International, Inc.

                                   By: ________________________________________
                                   Name: ______________________________________
                                   Title: _____________________________________
                                                                         "ATSI"

                                   ____________________________________________
                                   Alfonso Torres Roqueni

                                                                       "TORRES"

                                   Laredo National Bank

                                   By: ________________________________________
                                   Name: ______________________________________
                                   Title: _____________________________________
                                                                 "ESCROW AGENT"

                                       8
<PAGE>

                                   EXHIBIT A

                             FIRST ESCROW RELEASE

re:      Escrow Agreement dated effective as of June 6, 2000 between American
         TeleSource International, Inc. ("ATSI"), Alfonso Roqueni Torres
         ("Torres"), and Laredo National Bank (the "Escrow Agreement").

Date:    ______________

         Capitalized terms shall have the meanings given in the Escrow
Agreement.

         The undersigned parties to the Escrow Agreement hereby direct the
Escrow Agent to:

         (i)   disburse the 3%Stock to ATSI or the persons or persons designated
               by ATSI below, and

         (ii)  disburse the First ATSI Shares Instruction to the Transfer Agent.

         3%Stock to:        ________________________ (Name)
                            ________________________ (Address)
                            ________________________
                            ________________________ (Telephone)

         American TeleSource International, Inc.

         By:      _________________________
                  Arthur L. Smith,
                  Chief Executive Officer

                  _____________________________
                  Alfonso Roqueni Torres

                                       9
<PAGE>

                                    EXHIBIT B

                              SECOND ESCROW RELEASE

re:      Escrow Agreement dated effective as of June 6, 2000 between American
         TeleSource International, Inc. ("ATSI"), Alfonso Roqueni Torres
         ("Torres"), and Laredo National Bank (the "Escrow Agreement").

Date:    ______________

         Capitalized terms shall have the meanings given in the Escrow
Agreement.

         The undersigned parties to the Escrow Agreement hereby direct the
Escrow Agent to:

         (i)     endorse the 48%Stock to "Telemarketing of Mexico, S.A. de
                 C.V.".

         (ii)    disburse the endorsed 48%Stock to Torres,

         (iii)   disburse the Telemarketing Waiver and the RTorres Stock to
                 ATSI,

         (iv)    disburse the Second ATSI Shares Instruction to the Transfer
                 Agent,

         (v)     disburse the Note and the Warrant to Torres or to the person or
                 persons designated by Torres below, and

         (i)     destroy the Grupo Waiver.

         Note and Warrant to:        ________________________ (Name)
                                     ________________________ (Address)
                                     ________________________
                                     ________________________ (Telephone)

         American TeleSource International, Inc.

         By:  ____________________________
              Arthur L. Smith,
              Chief Executive Officer

              ________________________________
              Alfonso Roqueni Torres

                                       10
<PAGE>

                                   EXHIBIT C

                          SIMULTANEOUS ESCROW RELEASE

re:      Escrow Agreement dated effective as of June 6, 2000 between American
         TeleSource International, Inc. ("ATSI"), Alfonso Roqueni Torres
         ("Torres"), and Laredo National Bank (the "Escrow Agreement").

Date:    ______________

         Capitalized terms shall have the meanings given in the Escrow
Agreement.

         The undersigned parties to the Escrow Agreement hereby direct the
Escrow Agent to:

         (i)     disburse the 3%Stock to ATSI or the persons or persons
                 designated by ATSI below,

         (ii)    disburse the First ATSI Shares Instruction to the Transfer
                 Agent,

         (iii)   endorse the 48%Stock to "Telemarketing of Mexico, S.A. de
                 C.V.".

         (iv)     disburse the endorsed 48%Stock to Torres,

         (v)     disburse the Telemarketing Waiver and the RTorres Stock to
                 ATSI,

         (vi)    disburse the Second ATSI Shares Instruction to the Transfer
                 Agent,

         (vi)    disburse the Note and the Warrant to Torres or to the person or
                 persons designated by Torres below,

         (vii)   destroy the Telemarketing Assignment and return the
                 Telemarketing Stock to Torres, and

         (iv)    destroy the Poder General..

         3%Stock to:               ________________________ (Name)
                                   ________________________ (Address)
                                   ________________________
                                   ________________________ (Telephone)

         Note and Warrant to:      ________________________ (Name)
                                   ________________________ (Address)
                                   ________________________
                                   ________________________ (Telephone)

                                       11
<PAGE>

         American TeleSource International, Inc.

         By:   __________________________
               Arthur L. Smith,
               Chief Executive Officer

               _____________________________
               Alfonso Roqueni Torres

                                       12
<PAGE>

                                   EXHIBIT D

                          ALTERNATIVE ESCROW RELEASE

re:      Escrow Agreement dated effective as of June 6, 2000 between American
         TeleSource International, Inc. ("ATSI"), Alfonso Roqueni Torres
         ("Torres"), and Laredo National Bank (the "Escrow Agreement").

Date:    ______________

         Capitalized terms shall have the meanings given in the Escrow
Agreement.

         ATSI hereby direct the Escrow Agent to release the Poder General to
ATSI..

         American TeleSource International, Inc.

         By:   _________________________
               Arthur L. Smith,
               Chief Executive Officer

               _____________________________
               Alfonso Roqueni Torres

                                       13
<PAGE>

                                   EXHIBIT E

                             TERMINATION OF ESCROW

re:      Escrow Agreement dated effective as of June 6, 2000 between American
         TeleSource International, Inc. ("ATSI"), Alfonso Roqueni Torres
         ("Torres"), and Laredo National Bank (the "Escrow Agreement").

Date:    ______________

         Capitalized terms shall have the meanings given in the Escrow
Agreement.

         ATSI hereby directs the Escrow Agent to:

         (i)   disburse to ATSI the First ATSI Shares Instruction (if not
               already disbursed to the Transfer Agent pursuant to Section 3(b)
               of the Escrow Agreement) the Second ATSI Shares Instruction, the
               Note and the Warrant, and

         (ii)  disburse to Torres the 3%Stock (if not already disbursed to ATSI
               pursuant to Section 3(b) of the Escrow Agreement), the 48%Stock,
               the Telemarketing Waiver, and the Grupo Waiver.

         American TeleSource International, Inc.

         By:   __________________________
               Arthur L. Smith,
               Chief Executive Officer

                                       14<PAGE>

                                                                     EXHIBIT 4.5

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY STATE SECURITIES LAW, AND MAY NOT BE OFFERED FOR SALE, SOLD OR
TRANSFERRED UNLESS A REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE
SECURITIES LAWS SHALL BE EFFECTIVE WITH RESPECT THERETO, OR AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS IS
AVAILABLE IN CONNECTION WITH SUCH OFFER, SALE OR TRANSFER.

Warrant to Purchase                           Issue Date:  June 7, 2000
100,000 Shares

                       WARRANT TO PURCHASE COMMON STOCK

                                      of

                    AMERICAN TELESOURCE INTERNATIONAL, INC.

     THIS CERTIFIES that Alfonso Torres Roqueni (the "Initial Holder") or any
subsequent holder hereof (the Initial Holder and any subsequent holder referred
to herein as the "Holder"), has the right to purchase from AMERICAN TELESOURCE
                  ------
INTERNATIONAL, INC., a Delaware corporation (the "Company"), up to One Hundred
                                                  -------
Thousand (100,000) fully paid and nonassessable shares of the Company's common
stock, par value $.001 per share (the "Common Stock"), subject to adjustment as
                                       ------------
provided herein, at a price equal to the Exercise Price (as defined below), at
any time beginning on the date on which this Warrant is issued (the "Issue
                                                                     -----
Date") and ending at 3:00 p.m., central time, on the date that is the third
----
(3rd) anniversary of the Issue Date (the "Expiration Date"). This Warrant is
                                          ---------------
issued, and all rights hereunder shall be, subject to all of the conditions,
limitations and provisions set forth herein and in the Agreement of even date
herewith by and among the Company, Alfonso Torres Roqueni, Grupo Intelcom de
Mexico, S.A. de C.V., and Telemarketing de Mexico, S.A. de C.V. (the
"Agreement").
 ---------
<PAGE>

The following capitalized terms shall have the following meanings when used in
this Warrant:

     "Business Day" shall mean any day on which The American Stock Exchange is
      ------------
open for business.

     "Closing Sale Price" on any day means the closing sale price of the Common
      ------------------
Stock on The American Stock Exchange, or the principal national security
exchange or quotation system on which the Common Stock is listed or quoted if
other than The American Stock Exchange (closing bid price in the case of a
quotation system), or if not quoted or listed or admitted to trading on any
national securities exchange or quotation system, the closing bid price of the
Common Stock on the over-the-counter market as reported by Bloomberg LP, or a
similar generally accepted reporting service, as the case may be.

     "Market Price" on any day means the average Closing Sale Price for the
      ------------
twenty (20) consecutive trading days immediately preceding such day.

     1.   Exercise.
          --------

     (a)  Right to Exercise; Exercise Price. The Holder shall have the right to
exercise this Warrant at any time and from time to time during the period
beginning on the Issue Date and ending on the Expiration Date as to all or any
part of the shares of Common Stock covered hereby (the "Warrant Shares"). The
                                                        --------------
"Exercise Price" payable by the Holder in connection with the exercise of this
 --------------
Warrant shall be equal to six U.S. dollars ($6.00) per share of Common Stock;
provided, however, that on the one-year anniversary of the Issue Date, the
--------  -------
Exercise Price shall be reset to seventy-five (75%) of the Market Price. If the
Market Price on that date is less than eight U.S. dollars ($8.00).

     (b)  Exercise Notice.  In order to exercise this Warrant, the Holder shall
send by facsimile transmission, at any time prior to 3:00 p.m., central time, on
the Business Day on which the Holder wishes to effect such exercise (the
"Exercise Date"), to the Company a copy of the notice of exercise in the form
 -------------
attached hereto as Exhibit A (the "Exercise Notice") stating the number of
                                   ---------------
Warrant Shares as to which such exercise applies. The Holder shall thereafter
deliver to the Company the original Exercise Notice, the original Warrant and
the Exercise Price.

     (c)  Cancellation of Warrant.  This Warrant shall be canceled upon its
exercise and, if this Warrant is exercised in part, the Company shall, at the
time that it delivers Warrant Shares to the Holder pursuant to such exercise as
provided herein, issue a new warrant, and deliver to the Holder a certificate
representing such new warrant, with terms identical in all respects to this
Warrant (except that such new warrant shall be exercisable into the number of
shares of Common Stock with respect to which this Warrant shall remain
unexercised); provided, however, that the Holder shall be entitled to exercise
              --------  -------
all or any portion of such new warrant at any time following the time at which
this Warrant is exercised, regardless of whether the Company has actually issued
such new warrant or delivered to the Holder a certificate therefor.

                                      -2-
<PAGE>

     2.   Delivery of Warrant Shares Upon Exercise. Upon receipt of a Exercise
          ----------------------------------------
Notice pursuant to paragraph 1 above, the Company shall no later than the close
of business on the later to occur of (i) the fifth (5th) Business Day following
the Exercise Date set forth in such Exercise Notice and (ii) such later date on
which the Company shall have received payment of the Exercise Price (the
"Delivery Date"), issue and deliver or caused to be delivered to the Holder the
 -------------
number of Warrant Shares as shall be determined as provided herein. The Company
shall effect delivery of Warrant Shares by delivering to the Holder or its
nominee physical certificates representing such Warrant Shares, no later than
the close of business on such Delivery Date. The Warrant Shares delivered to the
Holder shall bear a restrictive legend identical to the legend appearing at the
top of this Warrant.

     3.   Failure to Deliver Warrant Shares.
          ---------------------------------

          (a)  Exercise Default.  In the event that, as a result of any action
or failure to act on the part of the Company (including without limitation a
failure by the Company to have a sufficient number of shares of Common Stock
authorized and reserved for issuance pursuant to exercise of the Warrants), the
Company does not deliver to a Holder certificates representing the number of
Warrant Shares specified in the applicable Exercise Notice on or before the
Delivery Date therefor and such failure continues for ten (10) Business Days,
the Company shall pay to the Holder an amount equal to the highest Closing Sale
Price for the Common Stock during the period from the Delivery Date until the
date delivery occurs, less the Closing Sale Price on the Delivery Date, times
the number of Warrant Shares that are not delivered on the Delivery Date.
Amounts payable under this subparagraph 3(a) shall be paid to the Holder in
immediately available funds on or before the fifth (5th) Business Day of the
calendar month immediately following the calendar month in which such amount has
accrued. THE PAYMENTS DESCRIBED IN THIS SECTION ARE THE SOLE AND EXCLUSIVE
REMEDY THE HOLDER HAS AGAINST THE COMPANY FOR FAILURE TO DELIVER WARRANT SHARES
ON A DELIVERY DATE.

          (b)  Holder of Record.  Each Holder shall, for all purposes, be deemed
to have become the holder of record of Warrant Shares on the Exercise Date of
this Warrant, irrespective of the date of delivery of such Warrant Shares.
Nothing in this Warrant shall be construed as conferring upon the Holder hereof
any rights as a stockholder of the Company prior to the Exercise Date.

     4.   Payment of the Exercise Price.  The Holder shall pay the Exercise
          -----------------------------
Price in by delivery of immediately available funds.

     5.   Anti-Dilution Adjustments; Distributions; Other Events. The Exercise
          ------------------------------------------------------
Price and the number of Warrant Shares issuable hereunder shall be subject to
adjustment from time to time as provided in this Section 5. In the event that
any adjustment of the Exercise Price or number of Warrant Shares as required
herein results in a fraction of a cent or fraction of a share, as applicable,
such exercise Price or number of Warrant Shares shall be rounded up or down to
the nearest cent or share, as applicable.

                                      -3-
<PAGE>

     (a)  Subdivision or Combination of Common Stock.  If the Company, at any
          ------------------------------------------
time after the initial issuance of this Warrant, subdivides (by any stock split,
stock dividend, recapitalization, reorganization, reclassification or otherwise)
its shares of Common Stock 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 after the initial issuance of this Warrant, combines (by
reverse stock split, recapitalization, reorganization, reclassification or
otherwise) its shares of Common Stock 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 proportionally increased.
In the event of any adjustment to the Exercise Price arising from an event
specified in this subparagraph (a), the number of shares of Common Stock into
which this Warrant is exercisable will be proportionately increased or reduced,
as the case may be.

     (b)  Distributions. If the Company or any of its subsidiaries shall at any
          -------------
time distribute to holders of Common Stock cash, evidences of indebtedness or
other securities or assets (other than cash dividends or distributions payable
out of earned surplus or net profits for the current or the immediately
preceding year) including any dividend or distribution in shares of capital
stock of a subsidiary of the Company (collectively, a "Distribution") then the
                                                       ------------
Company shall reserve or cause to be reserved an amount of the Distribution
equal to the amount that would have been issued to the Holder had all of the
unexercised portion of this Warrant (the "Unexercised Portion") been exercised
on the Business Day prior to record date for determining the amount of assets to
be issued to Common Stock holders (the "Record Date"), and to be issued to the
Holder on the exercise of the Warrant following the Record Date the percentage
of the reserved assets equal to the percentage of Unexercised Portion then being
exercised.

     (c)  Consolidation or Merger.  In the event of a merger, business
          -----------------------
combination, tender offer, exchange of shares, or other similar event, as a
result of which shares of Common Stock of the Company shall be changed into the
same or a different number of shares of another entity or there is a sale of all
or substantially all the Company's assets (a "Corporate Change"), then this
                                              ----------------
Warrant shall be exercisable into such class and type of securities or other
assets as the Holder would have received had the Holder exercised this Warrant
immediately prior to such Corporate Change.

     (d)  Adjustments; Additional Shares, Securities or Assets. In the event
          ----------------------------------------------------
that at any time, as a result of an adjustment made pursuant to this paragraph
5, the Holder of this Warrant shall, upon exercise of this Warrant, become
entitled to receive securities or assets (other than Common Stock) then,
wherever appropriate, all references herein to shares of Common Stock shall be
deemed to refer to and include such shares and/or other securities or assets;
and thereafter the number of such shares and/or other securities or assets shall
be subject to adjustment from time to time in a manner and upon terms as nearly
equivalent as practicable to the provisions of this paragraph 5. Any adjustment
made herein that results in a decrease in the Exercise Price shall also effect a
proportional increase in the number of shares of Common Stock into which this
Warrant is exercisable.

                                      -4-
<PAGE>

     6.   Transfer of this Warrant. The Holder may sell, transfer, assign,
          ------------------------
pledge or otherwise dispose of this Warrant, in whole or in part, as long as
such sale or other disposition is made pursuant to an effective registration
statement or an exemption to the registration requirements of the Securities Act
of 1933, as amended, and applicable state laws. Upon such transfer or other
disposition, the Holder shall deliver a written notice to Company, substantially
in the form of the Transfer Notice attached hereto as Exhibit B (the "Transfer
                                                                      --------
Notice"), indicating the person or persons to whom this Warrant shall be
------
transferred and, if less than all of this Warrant is transferred or this Warrant
is transferred in parts, the number of Warrant Shares to be covered by the part
of this Warrant to be transferred to each such person and an opinion of counsel
that the transfer is made pursuant to an exemption to the registration
requirements of the Securities Act of 1933. Within three (3) Business Days of
receiving a Transfer Notice and the original of this Warrant, and provided the
opinion of counsel is satisfactory to the Company in the Company's reasonable
judgement, the Company shall deliver to the each transferee designated by the
Holder a Warrant or Warrants of like tenor and terms for the appropriate number
of Warrant Shares. Notwithstanding the foregoing, no Holder may knowingly and
voluntarily sell this Warrant (or any portion thereof) to an entity that is a
competitor of the Company. The transfer of the Warrant shall be effective as of
the time of delivery of the Transfer Notice to the Company.

     7.   Benefits of this Warrant.
          ------------------------

          Nothing in this Warrant shall be construed to confer upon any person
other than the Holder of this Warrant any legal or equitable right, remedy or
claim under this Warrant and this Warrant shall be for the sole and exclusive
benefit of the Holder of this Warrant.

     8.   Loss, theft, destruction or mutilation  of Warrant.
          --------------------------------------------------

          Upon receipt by the Company of evidence of the loss, theft,
destruction or mutilation of this Warrant, and (in the case of loss, theft or
destruction) of indemnity or security reasonably satisfactory to the Company,
and upon surrender of this Warrant, if mutilated, the Company shall execute and
deliver a new Warrant of like tenor and date.

     9.   Notice or Demands.
          -----------------

          Except as otherwise provided herein, any notice, demand or request
required or permitted to be given pursuant to the terms of this Warrant shall be
in writing and shall be deemed given (i) when delivered personally or by
verifiable facsimile transmission (with an original to follow) on or before 3:00
p.m., central time, on a Business Day or, if such day is not a Business Day, on
the next succeeding Business Day, (ii) on the next Business Day after timely
delivery to a nationally-recognized overnight courier and (iii) on the Business
Day actually received if deposited in the U.S. mail (certified or registered
mail, return receipt requested, postage prepaid), addressed as follows:

                                      -5-
<PAGE>

          If to the Company:

          American TeleSource International, Inc.
          6000 Northwest Parkway, Suite 11o
          San Antonio, TX 78249
          Attn: H. Douglas Saathoff, Chief Financial Officer
          Tel: (210) 547-1000
          Fax: (210) 547-1001

          If to the Initial Holder:

          Alfonso Torres Roqueni
          Blvd. M. Avila Camacho 184 16o. Piso,
          Col. Lomas de San Isidro, C.P. 11620,
                 Mexico, D.F.
          Tel: (525)281-1214
          Fax: (525) 280-5860

If to a subsequent Holder, to such address as shall be designated on the
Transfer Notice, or to such other address designated by the Holder or the
Company in a written notice.

     10.  Applicable Law.
          --------------

          This Warrant is issued under and shall for all purposes be governed by
and construed in accordance with the laws of the state of Delaware, without
giving effect to conflict of law provisions thereof.

     IN WITNESS WHEREOF, the undersigned has executed this Warrant as of the
Issue Date.

                         AMERICAN TELESOURCE INTERNATIONAL, INC.

                         By:    _____________________________________________
                         Name:  Arthur L. Smith
                         Title: Chief Executive Officer

                                      -6-
<PAGE>

                             EXHIBIT A to WARRANT
                             --------------------

                                EXERCISE NOTICE
                                ---------------

     The undersigned Holder hereby irrevocably exercises the right to purchase
_______ shares of Common Stock ("Warrant Shares") of AMERICAN TELESOURCE
                                 --------------
INTERNATIONAL, INC. evidenced by the attached Warrant (the "Warrant"). Payment
                                                            -------
of Exercise Price. The Holder shall pay the sum of $________________ to the
Company in accordance with the terms of the Warrant.

                         ____________________________________
                         Name of Registered Holder

                         By:  _______________________________
                         Name:
                         Title:
                         Date: ______________________

                                      -7-
<PAGE>

                             EXHIBIT B to WARRANT
                             --------------------

                                TRANSFER NOTICE
                                ---------------

FOR VALUE RECEIVED, the undersigned Holder of the attached Warrant hereby sells,
assigns and transfers unto the person or persons named below the right to
purchase ________ shares of the Common Stock of AMERICAN TELESOURCE
INTERNATIONAL, INC. evidenced by the attached Warrant.

                         ____________________________________
                         Name of Registered Holder

                         By:  _______________________________
                         Name:
                         Title:
                         Date: ______________________

Transferee Name and Address:

___________________________________________

___________________________________________

___________________________________________

                                      -8-

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