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                                                                     EXHIBIT 4.6

              CERTIFICATE OF DESIGNATION, PREFERENCES AND RIGHTS
                                      OF
              6% SERIES D CUMULATIVE CONVERTIBLE PREFERRED STOCK
                                      OF
                    AMERICAN TELESOURCE INTERNATIONAL, INC.



 Pursuant to Section 151 of the General Corporation Law of the State of Delaware


     American TeleSource International, Inc., a corporation organized and
existing under the General Corporation Law of the State of Delaware (the
"Corporation"), hereby certifies that the Board of Directors of the Corporation
effective as of February 15, 2000 adopted resolutions by Unanimous Written
Consent adopting this Certificate of Designation, Preferences and Rights
designating a new class of its preferred stock called the 6% Series D Cumulative
Convertible Preferred Stock, having the terms set forth herein, and that the
Corporation has caused this Certificate of Amendment to the Certificate of
Incorporation to be executed by a duly authorized officer as of the 18th day of
February, 2000.

              6% Series D Cumulative Convertible Preferred Stock

                                   ARTICLE 1
                                  Definitions

     The terms defined in this Article whenever used in this Certificate of
Designation have the following respective meanings:

     (a) "Additional Capital Shares" has the meaning set forth in Section
6.1(c).

     (b) "Affiliate" has the meaning ascribed to such term in Rule 12b-2 under
the Securities Exchange Act of 1934, as amended.

     (c) "AMEX" means the American Stock Exchange.

     (d) "Business Day" means a day other than Saturday, Sunday or any day on
which banks located in the State of New York are authorized or obligated to
close.

     (e) "Capital Shares" means the Common Shares and any other shares of any
other class or series of common stock, whether now or hereafter authorized and
however designated, which have the right to participate in the distribution of
earnings and assets (upon dissolution, liquidation or winding-up) of the
Corporation.

     (f) "Closing Date" means the Issue Date.

     (g) "Common Shares" or "Common Stock" means shares of common stock, par
value $0.001 per share, of the Corporation.

     (h) "Common Stock Issued at Conversion" when used with reference to the
securities issuable upon conversion of the Series D Preferred Stock, means all
Common Shares now or hereafter Outstanding and securities of any other class or
series into which the Series C Preferred Stock hereafter shall have been changed
or substituted, whether now or hereafter created and however designated.

     (i) "Conversion Date" means any day on which all or any portion of shares
of the Series D Preferred Stock is converted in accordance with the provisions
hereof.

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     (j) "Conversion Notice" has the meaning set forth in Section 6.2.

     (k) "Conversion Price" means on any date of determination the applicable
price for the conversion of shares of Series D Preferred Stock into Common
Shares on such day as set forth in Section 6.1.

     (l) "Conversion Ratio" means on any date of determination the applicable
percentage of the Market Price for conversion of shares of Series D Preferred
Stock into Common Shares on such day as set forth in Section 6.1.

     (m) "Corporation" means American TeleSource International, Inc., a Delaware
corporation, and any successor or resulting corporation by way of merger,
consolidation or otherwise.

     (n) "Current Market Price" means on any date of determination the closing
price of a Common Share on such day as reported on the AMEX; provided, if such
security bid is not listed or admitted to trading on the AMEX, then as reported
on the principal national security exchange or quotation system on which such
security is quoted or listed or admitted to trading, or, if not quoted or listed
or admitted to trading on any national securities exchange or quotation system,
the closing bid price of such security on the over-the-counter market on the day
in question as reported by Bloomberg LP, or a similar generally accepted
reporting service, as the case may be.

     (o) "Default Dividend Rate" shall be equal to the Preferred Stock Dividend
Rate plus an additional 4% per annum.

     (p) "Holder" means The Shaar Fund Ltd., any successor thereto, or any
Person or Persons to whom the Series D Preferred Stock is subsequently
transferred in accordance with the provisions hereof.

     (q) "Issue Date" has the meaning set forth in Section 6.1.

     (r) "Market Disruption Event" means any event that results in a material
suspension or limitation of trading of the Common Shares on the AMEX.

     (s) "Market Price" per Common Share, on any date of determination, means
the arithmetic mean of the lowest closing prices of the Common Shares as
reported on the AMEX five (5) Trading Days during the period of ten (10) Trading
Days immediately preceding such date of determination, it being understood that
such five (5) Trading Days need not be consecutive; provided, if such security
is not listed or admitted to trading on the AMEX, then as reported on the
principal national security exchange or quotation system on which such security
is quoted or listed or admitted to trading, or, if not quoted or listed or
admitted to trading on any national securities exchange or quotation system, the
closing bid price of such security on the over-the-counter market on the day in
question as reported by Bloomberg LP, or a similar generally accepted reporting
service, as the case may be, for five (5) Trading Days during the period of ten
(10) Trading Days immediately preceding such date of determination, it being
understood that such five (5) Trading Days need not be consecutive.

     (t) "Optional Redemption Price" means (i) a sum in cash equal to one
hundred twenty-seven percent (127%) of the Stated Value plus (ii) the Company's
                                                        ----
common stock purchase warrant or warrants to purchase 150,000 shares of Common
Stock, having the same terms and conditions as the Warrant.

     (u) "Outstanding" when used with reference to Common Shares or Capital
Shares (collectively, "Shares"), means, on any date of determination, all issued
and outstanding Shares, and includes all such Shares issuable in respect of
outstanding scrip or any certificates representing fractional interests in such
Shares; provided, however, that any such Shares directly or indirectly owned or
held by or for the account of the Corporation or any Subsidiary of the
Corporation shall not be deemed "Outstanding" for purposes hereof.

     (v) "Person" means an individual, a corporation, a partnership, an
association, a limited liability company, an unincorporated business
organization, a trust or other entity or organization, and any government or
political subdivision or any agency or instrumentality thereof.

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     (w)  "Registration Rights Agreement" means that certain Registration Rights
Agreement dated the Closing Date between the Corporation and The Shaar Fund
Ltd., including any amendments thereto.

     (x)  "SEC" means the United States Securities and Exchange Commission.

     (y)  "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations of the SEC thereunder, all as in effect at the time.

     (z)  "Securities Purchase Agreement" means that certain Securities Purchase
Agreement dated the Closing Date between the Corporation and The Shaar Fund
Ltd., including any amendments thereto.

     (aa)  "Series D Preferred Shares" or "Series D Preferred Stock" means the
shares of 6% Series D Cumulative Convertible Preferred Stock of the Corporation
or such other convertible Preferred Stock exchanged therefor.

     (bb)  "Stated Value" has the meaning set forth in Article 2.

     (cc)  "Subsidiary" means any entity of which securities or other ownership
interests having ordinary voting power to elect a majority of the board of
directors or other persons performing similar functions are owned directly or
indirectly by the Corporation.

     (dd)  "Trading Day" means any day on which purchases and sales of
securities authorized for quotation on the AMEX are reported thereon and on
which no Market Disruption Event has occurred.

     (ee)  "Valuation Event" has the meaning set forth in Section 6.1.

     (ff)  "Valuation Period" means the ten (10) Trading Day period immediately
preceding the Conversion Date.

     (gg)  "Warrant" means the warrant to purchase Common Stock issued by the
Company to the initial Holder pursuant to the Securities Purchase Agreement.

     All references to "cash" or "$" herein means currency of the United States
of America.

                                   ARTICLE 2
                            Designation And Amount

     The designation of this series, which consists of 3,000 shares of Preferred
Stock, is 6% Series D Cumulative Convertible Preferred Stock (the "Series D
Preferred Stock") and the stated value shall be $1,000.00 per share (the "Stated
Value").

                                   ARTICLE 3
                                     Rank

     The Series D Preferred Stock shall rank (i) prior to the Common Stock; (ii)
prior to any class or series of capital stock of the Corporation hereafter
created other than "Pari Passu Securities" (collectively, with the Common Stock,
"Junior Securities") and (iii) pari passu with the 10% Series A Cumulative
Convertible Preferred Stock, the 6% Series B Cumulative Convertible Preferred
Stock, and the 6% Series C Cumulative Convertible Preferred Stock of the
Corporation currently outstanding and any class or series of capital stock of
the Corporation hereafter created specifically ranking on parity with the Series
D Preferred Stock ("Pari Passu Securities").

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                                   ARTICLE 4
                                   Dividends

     (a)  (i)   The Holder shall be entitled to receive, when, as and if
declared by the Board of Directors, out of funds legally available for the
payment of dividends, dividends (subject to Article 4(a)(ii) hereof) at the rate
of six percent (6%) per annum (computed on the basis of a 360-day year) (the
"Dividend Rate") on the Stated Value of each share of Series D Preferred Stock
on and as of the most recent Dividend Payment Due Date (as defined below) with
respect to each Dividend Period (as defined below). Dividends on the Series D
Preferred Stock shall be cumulative from the date of issue, whether or not
declared for any reason, including if such declaration is prohibited under any
outstanding indebtedness or borrowings of the Corporation or any of its
Subsidiaries, or any other contractual provision binding on the Corporation or
any of its Subsidiaries, and whether or not there shall be funds legally
available for the payment thereof.

          (ii)  Each dividend shall be payable in equal quarterly amounts on
each March 31, June 30, September 30 and December 31 of each year or, if any
such date is not a business day, on the next succeeding business day (each, a
"Dividend Payment Due Date"), commencing December 31, 1999, to the holders of
record of shares of the Series D Preferred Stock, as they appear on the stock
records of the Corporation at the close of business on any record date, not more
than 60 days or less than 10 days preceding the payment dates thereof, as shall
be fixed by the Board of Directors. For the purposes hereof, "Dividend Period"
means the period commencing on and including the Issue Date through December 31,
1999 and thereafter each quarterly period commencing on the day after the
immediately preceding Dividend Payment Due Date and ending on and including the
immediately subsequent Dividend Payment Due Date. Accrued and unpaid dividends
for any past Dividend Period may be declared and paid at any time, without
reference to any Dividend Payment Due Date, to holders of record on such date,
not more than 15 days preceding the payment date thereof, as may be fixed by the
Board of Directors.

          (iii) Subject to the next sentence, at the option of the Corporation,
the dividend shall be paid in cash or through the issuance of duly and validly
authorized and issued, fully paid and nonassessable shares of the Common Stock
valued at the Market Price.  The Corporation may exercise such option only if
the Common Stock to be issued in lieu of cash payments shall be registered for
resale in the Registration Statement (as defined in the Registration Rights
Agreement) to be filed by the Corporation to register the Common Stock issuable
upon conversion of the shares of Series D Preferred Stock and exercise of the
Warrants as set forth in the Registration Rights Agreement.  Notwithstanding the
foregoing, until such Registration Statement (as defined in the Registration
Rights Agreement) has been declared effective under the Securities Act by the
SEC, payment of dividends on the Series D Preferred Stock shall be in cash.

     (b)  The Holder shall not be entitled to any dividends in excess of the
cumulative dividends, as herein provided, on the Series D Preferred Stock.
Except as provided in this Article 4, no interest, or sum of money in lieu of
interest, shall be payable in respect of any dividend payment or payments on the
Series D Preferred Stock that may be in arrears.

     (c)  So long as any shares of the Series D Preferred Stock are outstanding,
no dividends, except as described in the next succeeding sentence, shall be
declared or paid or set apart for payment on Pari Passu Securities for any
period unless full cumulative dividends required to be paid in cash have been or
contemporaneously are declared and paid or declared and a sum sufficient for the
payment thereof set apart for such payment on the Series D Preferred Stock for
all Dividend Periods terminating on or prior to the date of payment of the
dividend on such class or series of Pari Passu Securities.  When dividends are
not paid in full or a sum sufficient for such payment is not set apart, as
aforesaid, all dividends declared upon shares of the Series D Preferred Stock
and all dividends declared upon any other class or series of Pari Passu
Securities shall be declared ratably in proportion to the respective amounts of
dividends accumulated and unpaid on the Series D Preferred Stock and accumulated
and unpaid on such Pari Passu Securities.

     (d)  So long as any shares of the Series D Preferred Stock are outstanding,
no dividends shall be declared or paid or set apart for payment or other
distribution declared or made upon Junior Securities, nor shall any Junior
Securities be redeemed, purchased or otherwise acquired (other than a
redemption, purchase or other acquisition of shares of Common Stock made for
purposes of an employee incentive or benefit plan (including a

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stock option plan) of the Corporation or any subsidiary or any cashless exercise
of warrants), (all such dividends, distributions, redemptions or purchases being
hereinafter referred to as a "Junior Securities Distribution") for any
consideration (or any moneys be paid to or made available for a sinking fund for
the redemption of any shares of any such stock) by the Corporation, directly or
indirectly, unless in each case (i) the full cumulative dividends required to be
paid in cash on all outstanding shares of the Series D Preferred Stock and any
other Pari Passu Securities shall have been paid or set apart for payment for
all past Dividend Periods with respect to the Series D Preferred Stock and all
past dividend periods with respect to such Pari Passu Securities, and (ii)
sufficient funds shall have been paid or set apart for the payment of the
dividend for the current Dividend Period with respect to the Series D Preferred
Stock and the current dividend period with respect to such Pari Passu
Securities.

                                   ARTICLE 5
                            Liquidation Preference

     (a)  If the Corporation shall commence a voluntary case under the Federal
bankruptcy laws or any other applicable Federal or state bankruptcy, insolvency
or similar law, or consent to the entry of an order for relief in an involuntary
case under any law or to the appointment of a receiver, liquidator, assignee,
custodian, trustee, sequestrator (or other similar official) of the Corporation
or of any substantial part of its property, or make an assignment for the
benefit of its creditors, or admit in writing its inability to pay its debts
generally as they become due, or if a decree or order for relief in respect of
the Corporation shall be entered by a court having jurisdiction in the premises
in an involuntary case under the Federal bankruptcy laws or any other applicable
Federal or state bankruptcy, insolvency or similar law resulting in the
appointment of a receiver, liquidator, assignee, custodian, trustee,
sequestrator (or other similar official) of the Corporation or of any
substantial part of its property, or ordering the winding up or liquidation of
its affairs, and any such decree or order shall be unstayed and in effect for a
period of 30 consecutive days and, on account of any such event, the Corporation
shall liquidate, dissolve or wind up, or if the Corporation shall otherwise
liquidate, dissolve or wind up (each such event being considered a "Liquidation
Event"), no distribution shall be made to the holders of any shares of Common
Stock or Junior Securities of the Corporation upon liquidation, dissolution or
winding-up unless prior thereto, the holders of shares of Series D Preferred
Stock, subject to this Article 5, shall have received the Liquidation Preference
(as defined in Article 5(c)) with respect to each share.  If upon the occurrence
of a Liquidation Event, the assets and funds legally available for distribution
among the holders of the Series D Preferred Stock and holders of Pari Passu
Securities shall be insufficient to permit the payment to such holders of the
preferential amounts payable thereon, then the entire assets and funds of the
Corporation legally available for distribution to the Series D Preferred Stock
and the Pari Passu Securities shall be distributed ratably among such shares in
proportion to the ratio that the liquidation preference payable on each such
share bears to the aggregate liquidation preference payable on all such shares.

     (b)  At the option of each Holder, the sale, conveyance or disposition of
all or substantially all of the assets of the Corporation, the effectuation by
the Corporation of a transaction or series of related transactions in which more
than 50% of the voting power of the Corporation is obtained by any Person or
"group" as defined in or pursuant to Section 13 of the Securities Exchange Act
of 1934, as amended, other than a Person or "group" (as so defined), if any,
having more than 50% of the voting power of the Corporation on the Issue Date,
or the consolidation, merger or other business combination of the Corporation
with or into any other Person or Persons when the Corporation is not the
survivor shall either: (i) be deemed to be a liquidation, dissolution or winding
up of the Corporation pursuant to which the Corporation shall be required to
distribute, upon consummation of and as a condition to, such transaction an
amount equal to 120% of the Liquidation Preference with respect to each
outstanding share of Series D Preferred Stock in accordance with and subject to
the terms of this Article 5 or (ii) be treated pursuant to Section 6.4 hereof;
provided, that all holders of Series D Preferred Stock shall be deemed to elect
the option set forth in clause (i) hereof if at least a majority in interest of
such holders elect such option.

     (c)  For purposes hereof, the "Liquidation Preference" with respect to a
share of the Series D Preferred Stock shall mean an amount equal to the sum of
(i) the Stated Value thereof, plus (ii) an amount equal to 30% of such Stated
Value, plus (iii) the aggregate of all accrued and unpaid dividends on such
share of Series D Preferred Stock until the most recent Dividend Payment Due
Date; provided that, in the event of an actual liquidation, dissolution or
winding up of the Corporation, the amount referred to in clause (iii) above
shall be calculated by including accrued and unpaid dividends to the actual date
of such liquidation, dissolution or winding up, rather than the Dividend Payment
Due Date referred to above.

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                                   ARTICLE 6
                         Conversion of Preferred Stock

     Section 6.1  Conversion; Conversion Price

     At the option of the Holder, the shares of Series D Preferred Stock may be
converted, either in whole or in part (in whole shares of Series D Preferred
Stock), into Common Shares (calculated as to each such conversion to the nearest
1/100th of a share of Common Stock), at any time, and from time to time
following the date of issuance of the Series D Preferred Stock (the "Issue
Date") at a Conversion Price per share of Common Stock equal to the lesser of:
(i) the closing price of the Common Stock on February 16, 2000, being $5.4375,
as the same may be adjusted from time to time for any subdivision or combination
of Outstanding Common Shares after the Issue Date; and (ii) eighty-three percent
(83%) of the Market Price determined as of the Conversion Date; provided that
the Holder may not exercise any right of conversion set forth in this Article 6
during the period of thirty (30) days commencing on and including the first
Trading Day following the Issue Date, if any, on which the Current Market Price
of the Common Stock is $2.50 or less, as the same may be adjusted from time to
time for any subdivision or combination of Outstanding Common Shares after the
Issue Date; and provided, further, that if the Corporation's Common Stock, for
any reason, (a) becomes ineligible for trading on AMEX, (b) is not listed on the
New York Stock Exchange or (c) is not admitted to trading on the NASDAQ National
Market, the NASDAQ SmallCap Market, then any remaining unconverted Series D
Preferred Stock may be converted, at the sole option of the Holder, at a
Conversion Price per share of Common Stock equal to 65% of the Market Price
determined as of the Conversion Date.  At the Corporation's option, the amount
of accrued and unpaid dividends as of the Conversion Date  may be paid in cash
or in Common Stock valued at the Market Price on the Conversion Date.

     The number of shares of Common Stock due upon conversion of Series D
Preferred Stock shall be (i) the number of shares of Series D Preferred Stock to
be converted, multiplied by (ii) the Stated Value and divided by (iii) the
applicable Conversion Price.  Notwithstanding any other provision herein, the
Conversion Price shall not be less than the par value of the Common Stock

     Within two Business Days of the occurrence of a Valuation Event, the
Corporation shall send notice (the "Valuation Event Notice") of such occurrence
to the Holder.  Notwithstanding anything to the contrary contained herein, if a
Valuation Event occurs during the period of ten (10) Trading Days immediately
preceding a Conversion Date, the Market Price with respect to such Conversion
Date shall be (a) the arithmetic mean of the lowest closing prices of the Common
Shares (reported as provided in the definition of "Market Price") for five (5)
Trading Days (it being understood that such five (5) Trading Days need not be
consecutive) during the period beginning on the Trading Day immediately
following the occurrence of such Valuation Event and ending on the Conversion
Date (the "New Valuation Period"), if such New Valuation Period includes five
(5) Trading Days or more, or (b) the arithmetic mean of the lowest closing
prices of the Common Shares (reported as provided in the definition of "Market
Price") for all Trading Days in the New Valuation Period, if such New Valuation
Period includes four (4) Trading Days or less; provided that, if the Valuation
Event occurs on the Trading Day immediately preceding such Conversion Date, then
the Conversion Price shall be the lesser of (x) the closing price of the Common
Stock on February 16, 2000, being $5.4375, as the same may be adjusted from time
to time for any subdivision or combination of Outstanding Common Shares after
the Issue Date, and (y) eighty-three percent (83%) of the Current Market Price
of the Common Shares on the Trading Day immediately preceding the Conversion
Date; and provided, further, that the Holder may, in its discretion, postpone
such Conversion Date to a Trading Day which is no more than ten (10) Trading
Days after the occurrence of the latest Valuation Event by delivering a
notification to the Corporation within two Business Days of the receipt of the
Valuation Event Notice.  In the event that the Holder deems the Market Price is
to be calculated with reference to a period other than the ten (10) Trading Days
immediately prior to the Conversion Date, the Holder shall give written notice
of such fact to the Corporation in the related Conversion Notice at the time of
conversion.

     For purposes of this Section 6.1, a "Valuation Event" shall mean an event
in which the Corporation at any time takes any of the following actions:

     (a)  subdivides or combines its Capital Shares;

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     (b)  makes any distribution on its Capital Shares;

     (c)  issues any additional Capital Shares (the "Additional Capital
          Shares"), otherwise than as provided in the foregoing Sections 6.1(a)
          and 6.1(b) above, at a price per share less, or for other
          consideration lower, than the Current Market Price in effect
          immediately prior to such issuances, or without consideration, except
          for issuances under stock option plans presently in effect and
          issuances under presently outstanding warrants, options or convertible
          securities (and except for issuances upon exercise, conversion or
          exchange of securities described in Section 6.1(d) and 6.1(e) below);

     (d)  issues any warrants, options or other rights to subscribe for or
          purchase any Additional Capital Shares and the price per share for
          which Additional Capital Shares may at any time thereafter be issuable
          pursuant to such warrants, options or other rights shall be less than
          the Current Market Price in effect immediately prior to such issuance
          of the warrants, options or other rights;

     (e)  issues any securities convertible into or exchangeable or exercisable
          for Additional Capital Shares and the consideration per share for
          which Additional Capital Shares may at any time thereafter be issuable
          pursuant to the terms of such convertible, exchangeable or exercisable
          securities shall be less than the Current Market Price in effect
          immediately prior to such issuance of such convertible or exchangeable
          securities;

     (f)  makes a distribution of its assets or evidences of indebtedness to the
          holders of its Capital Shares as a dividend in liquidation or by way
          of return of capital or other than as a dividend payable out of
          earnings or surplus legally available for the payment of dividends
          under applicable law or any distribution to such holders made in
          respect of the sale of all or substantially all of the Corporation's
          assets (other than under the circumstances provided for in the
          foregoing Sections 6.1(a) through 6.1(e)); or

     (g)  takes any action affecting the number of Outstanding Capital Shares,
          other than an action described in any of the foregoing Sections 6.1(a)
          through 6.1(f) hereof, inclusive, which in the opinion of the
          Corporation's Board of Directors, determined in good faith, would have
          a material adverse effect upon the rights of the Holder at the time of
          a conversion of the Preferred Stock.

     Section 6.2  Exercise of Conversion Privilege

     (a)  Conversion of the Series D Preferred Stock may be exercised, in whole
or in part, by the Holder by telecopying an executed and completed notice of
conversion in the form annexed hereto as Annex I (the "Conversion Notice") to
the Corporation.  Each date on which a Conversion Notice is telecopied to the
Corporation in accordance with the provisions of this Section 6.2 shall
constitute a Conversion Date.  The Corporation shall convert the Series D
Preferred Stock and issue the Common Stock Issued at Conversion to be issued
upon conversion thereof, and all voting and other rights associated with the
beneficial ownership of  such Common Stock Issued at Conversion to be issued
upon conversion thereof shall vest with the Holder, effective as of the
Conversion Date at the time specified in the Conversion Notice.  The Conversion
Notice also shall state the name or names (with addresses) of the Persons who
are to become the holders of the Common Stock Issued at Conversion in connection
with such conversion.  The Holder shall deliver the shares of Series D Preferred
Stock to the Corporation by express courier within 30 days following the date on
which the telecopied Conversion Notice has been transmitted to the Corporation.
Upon surrender for conversion, the Preferred Stock shall be accompanied by a
proper assignment thereof to the Corporation or be endorsed in blank.  As
promptly as practicable after the receipt of the Conversion Notice as aforesaid,
but in any event not more than five (5) Business Days after the Corporation's
receipt of such Conversion Notice and the Series D Preferred Stock being
converted, the Corporation shall (i) issue the Common Stock Issued at Conversion
in accordance with the provisions of this Article 6 (including, without
limitation, any shares of Common Stock issued pursuant to Section 4(a)(iii), at
the option of the Corporation, in payment of dividends on the Series D Preferred
Stock), (ii) cause to be mailed for delivery by overnight courier to the Holder
a certificate or certificate(s) representing the number of Common Shares to
which the Holder is entitled by virtue of

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such conversion and (iii) remit, in immediately available funds, payment as
provided in Section 6.3 in respect of any fraction of a Common Share issuable
upon such conversion and payment in the amount of accrued and unpaid dividends
as of the Conversion Date. Such conversion shall be deemed to have been effected
at the time at which the Conversion Notice indicates so long as the Series D
Preferred Stock shall have been surrendered as aforesaid at such time, and at
such time the rights of the Holder of the Series D Preferred Stock, as such,
shall cease and the Person or Persons in whose name or names the Common Stock
Issued at Conversion shall be issuable shall be deemed to have become the holder
or holders of record of the Common Shares represented thereby and all voting and
other rights associated with the beneficial ownership of such Common Shares
shall at such time vest with such Person or Persons. The Conversion Notice shall
constitute a contract between the Holder and the Corporation, whereby the Holder
shall be deemed to subscribe for the number of Common Shares which it will be
entitled to receive upon such conversion and, in payment and satisfaction of
such subscription (and for any cash adjustment to which it is entitled pursuant
to Section 6.4), to surrender the Series D Preferred Stock and to release the
Corporation from all liability thereon. No cash payment aggregating less than
$1.00 shall be required to be given unless specifically requested by the Holder.

     (b)  If, at any time (i) the Corporation challenges, disputes or denies the
right of the Holder hereof to effect the conversion of the Series D Preferred
Stock into Common Shares or otherwise dishonors or rejects any Conversion Notice
delivered in accordance with this Section 6.2 or (ii) any third party who is not
and has never been an Affiliate of the Holder commences any lawsuit or
proceeding or otherwise asserts any claim before any court or public or
governmental authority which seeks to challenge, deny, enjoin, limit, modify,
delay or dispute the right of the Holder hereof to effect the conversion of the
Series D Preferred Stock into Common Shares, then the Holder shall have the
right, by written notice to the Corporation, to require the Corporation to
promptly redeem, to the extent permitted by law, the Series D Preferred Stock
for cash at a redemption price equal to 127% of the Stated Value thereof
together with all accrued and unpaid dividends thereon (the "Mandatory Purchase
Amount").  Under any of the circumstances set forth above, the Corporation shall
be responsible for the payment of all costs and expenses of the Holder,
including reasonable legal fees and expenses, as and when incurred in disputing
any such action or pursuing its rights hereunder (in addition to any other
rights of the Holder).

     (c)  The Holder shall be entitled to exercise its conversion privilege
notwithstanding the commencement of any case under 11 U.S.C. (S) 101 et seq.
(the "Bankruptcy Code").  In the event the Corporation is a debtor under the
Bankruptcy Code, the Corporation hereby waives to the fullest extent permitted
any rights to relief it may have under 11 U.S.C. (S) 362 in respect of the
Holder's conversion privilege.  The Corporation hereby waives to the fullest
extent permitted any rights to relief it may have under 11 U.S.C. (S) 362 in
respect of the conversion of the Series D Preferred Stock.  The Corporation
agrees, without cost or expense to the Holder, to take or consent to any and all
action necessary to effectuate relief under 11 U.S.C. (S) 362.

     Section 6.3  Fractional Shares

     No fractional Common Shares or scrip representing fractional Common Shares
shall be issued upon conversion of the Series D Preferred Stock.  Instead of any
fractional Common Shares which otherwise would be issuable upon conversion of
the Series D Preferred Stock, the Corporation shall pay a cash adjustment in
respect of such fraction in an amount equal to the same fraction.  No cash
payment of less than $1.00 shall be required to be given unless specifically
requested by the Holder.

     Section 6.4   Reclassification, Consolidation, Merger or Mandatory Share
Exchange

     At any time while the Series D Preferred Stock remains outstanding and any
shares thereof have not been converted, in case of any reclassification or
change of Outstanding Common Shares issuable upon conversion of the Series D
Preferred Stock (other than a change in par value, or from par value to no par
value per share, or from no par value per share to par value or as a result of a
subdivision or combination of outstanding securities issuable upon conversion of
the Series D Preferred Stock) or in case of any consolidation, merger or
mandatory share exchange of the Corporation with or into another corporation
(other than a merger or mandatory share exchange with another corporation in
which the Corporation is a continuing corporation and which does not result in
any reclassification or change, other than a change in par value, or from par
value to no par value per share, or from no par value per share to par value, or
as a result of a subdivision or combination of Outstanding Common Shares upon
conversion of the

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Series D Preferred Stock), or in the case of any sale or transfer to another
corporation of the property of the Corporation as an entirety or substantially
as an entirety, the Corporation will not effect any such action unless the
Corporation, or such successor, resulting or purchasing corporation, as the case
may be, shall, without benefit of any additional consideration therefor, issues
a new preferred stock providing that the Holder shall have the right to convert
such new preferred stock (upon terms and conditions not less favorable to the
Holder than those in effect pursuant to the Series D Preferred Stock) and to
receive upon such exercise, in lieu of each Common Share theretofore issuable
upon conversion of the Series D Preferred Stock, the kind and amount of shares
of stock, other securities, money or property receivable upon such
reclassification, change, consolidation, merger, mandatory share exchange, sale
or transfer by the holder of one Common Share issuable upon conversion of the
Series D Preferred Stock had the Series D Preferred Stock been converted
immediately prior to such reclassification, change, consolidation, merger,
mandatory share exchange or sale or transfer. The provisions of this Section 6.4
shall similarly apply to successive reclassifications, changes, consolidations,
mergers, mandatory share exchanges and sales and transfers.

     Section 6.5   Adjustments to Conversion Price

     For so long as any shares of the Series D Preferred Stock are outstanding,
if the Corporation:  (i) issues and sells pursuant to an exemption from
registration under the Securities Act (A) Common Shares at a purchase price on
the date of issuance thereof that is lower than the Conversion Price (other than
Common Shares issuable upon exercise, conversion or exchange of securities
described in the following clause (B) or (C), (B) warrants or options with an
exercise price representing a percentage of the Current Market Price on the date
of issuance of the warrants or options that is lower than the Conversion Price,
except for employee stock option agreements or stock incentive agreements of the
Corporation, or (C) convertible, exchangeable or exercisable securities with a
right to exchange at lower than the Current Market Price on the date of issuance
or conversion, as applicable, of such convertible, exchangeable or exercisable
securities, except for stock option agreements or stock incentive agreements;
and (ii) grants the right to the purchaser(s) thereof to demand that the
Corporation register under the Securities Act prior to two years from the Issue
Date such Common Shares issued or the Common Shares for which such warrants or
options may be exercised or such convertible, exchangeable or exercisable
securities may be converted, exchanged or exercised, then the Conversion Price
shall be reduced to equal the lowest of any such lower prices.

     Section 6.6   Optional Redemption and Optional Conversion

     At any time after the date of issuance of the Series D Preferred Stock
until the Mandatory Conversion Date (as defined below), to the extent permitted
by law, the Corporation, upon notice delivered to the Holder as provided in
Section 6.7, may redeem all (but not less than all) of the Series D Preferred
Stock (but only with respect to such shares as to which the Holder has not
theretofore furnished a Conversion Notice in compliance with Section 6.2), at
the Optional Redemption Price, together with all accrued and unpaid dividends
thereon to the date of redemption (the "Redemption Date"); provided, however,
that the Corporation may only redeem the Series B Preferred Stock under this
Section 6.6 if the Current Market Price is less than the Current Market Price on
the Issue Date.  Except as set forth in this Section 6.6, the Corporation shall
not have the right to prepay or redeem the Series D Preferred Stock.

     Section 6.7  Notice of Redemption

     Notice of redemption pursuant to Section 6.6 shall be provided by the
Corporation to the Holder in writing (by registered mail or overnight courier at
the Holder's last address appearing in the Corporation's security registry) not
less than 10 nor more than 15 days prior to the Redemption Date, which notice
shall specify the Redemption Date and refer to Section 6.6 (including a
statement of the Market Price per Common Share) and this Section 6.7.

     Section 6.8  Surrender of Preferred Stock

     Upon any redemption of the Series D Preferred Stock pursuant to Sections
6.6 or 6.7 the Holder shall either deliver the Series D Preferred Stock by hand
to the Corporation at its principal executive offices or surrender the same to
the Corporation at such address by express courier.  Payment of the optional
Redemption Price specified in Section 6.6 shall be made by the Corporation to
the Holder against receipt of the Series D Preferred Stock (as

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<PAGE>

provided in this Section 6.8) by wire transfer of immediately available funds to
such account(s) as the Holder shall specify to the Corporation. If payment of
such redemption price is not made in full by the or the Redemption Date the
Holder shall again have the right to convert the Series D Preferred Stock as
provided in Article 6 hereof.

     Section 6.9   Mandatory Conversion

     On the second (2/nd/) anniversary of the Issue Date subject to 6.10(a) (the
"Mandatory Conversion Date"), the Corporation shall convert all Series D
Preferred Stock outstanding at the Conversion Price.

     Section 6.10  Certain Conversion Limitations

          (a)  Notwithstanding anything herein to the contrary, the Holder shall
not have the right, and the Corporation shall not have the obligation, to
convert all or any portion of the Series D Preferred Stock (and the Corporation
shall not have the right to pay dividends on the Series D Preferred Stock in
shares of Common Stock) if and to the extent that the issuance to the Holder of
shares of Common Stock upon such conversion (or payment of dividends) would
result in the Holder being deemed the "beneficial owner" of more than 5% of the
then outstanding shares of Common Stock within the meaning of Section 13(d) of
the Securities Exchange Act of 1934, as amended, and the rules promulgated
thereunder.  If any court of competent jurisdiction shall determine that the
foregoing limitation is ineffective to prevent a Holder from being deemed the
beneficial owner of more than 5% of the then outstanding shares of Common Stock,
then the Corporation shall redeem, to the extent permitted by law, so many of
such Holder's shares (the "Redemption Shares") of Series D Preferred Stock as
are necessary to cause such Holder to be deemed the beneficial owner of not more
than 5% of the then outstanding shares of Common Stock.  Upon such determination
by a court of competent jurisdiction, the Redemption Shares shall immediately
and without further action be deemed returned to the status of authorized but
unissued shares of Series D Preferred Stock, and the Holder shall have no
interest in or rights under such Redemption Shares.  Any and all dividends paid
on or prior to the date of such determination shall be deemed dividends paid on
the remaining shares of Series D Preferred Stock held by the Holder.  Such
redemption shall be for cash at a redemption price equal to the sum of (i) the
Stated Value of the Redemption Shares and (ii) any accrued and unpaid dividends
to the date of such redemption; provided, however, if the redemption is a result
of the mandatory conversion pursuant to Section 6.9, the Corporation may either
(i) make such redemption in cash at a redemption price equal to the sum of (x)
127% of the Stated Value of such shares and (y) any accrued and unpaid dividends
to the date of such redemption or (ii) extend the Mandatory Conversion Date for
a period of one year.

          (b)  Unless the Corporation shall have obtained the approval of its
voting stockholders to such issuance in accordance with the rules of the AMEX or
such stock market with which the Corporation shall be required to comply, but
only to the extent required thereby, the Corporation shall not issue shares of
Common Stock (i) upon conversion of any shares of Series D Preferred Stock or
(ii) as a dividend on the Series D Preferred Stock, if such issuance of Common
Stock, when added to the number of shares of Common Stock previously issued by
the Corporation (i) upon conversion of shares of the Series D Preferred Stock,
(ii) upon exercise of the Warrants issued pursuant to the terms of the
Securities Purchase Agreement and (iii) in payment of dividends on the Series D
Preferred Stock, would equal or exceed 20% of the number of shares of the
Corporation's Common Stock which were issued and outstanding on the Issue Date
(the "Maximum Issuance Amount").  In the event that a properly executed
Conversion Notice is received by the Corporation which would require the
Corporation to issue shares of Common Stock equal to or in excess of the Maximum
Issuance Amount, the Corporation shall honor such conversion request by (i)
converting the number of shares of Series D Preferred Stock stated in the
Conversion Notice not in excess of the Maximum Issuance Amount and (ii)
redeeming, to the extent permitted by law, the number of shares of Series D
Preferred Stock stated in the Conversion Notice equal to or in excess of the
Maximum Issuance Amount in cash at a price equal to 127% of the Stated Value of
the shares of Series D Preferred Stock to be so redeemed, together with all
accrued and unpaid dividends thereon.  In the event that the Corporation shall
elect to pay a dividend in shares of Common Stock which would require the
Corporation to issue shares of Common Stock equal to or in excess of the Maximum
Issuance Amount, the Corporation shall pay (i) a dividend in shares of Common
Stock equal to one less than an amount which would result in the Corporation
issuing shares equal to the Maximum Issuance Amount and (ii) the balance of the
dividend in cash.

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<PAGE>

                                   ARTICLE 7
                                 Voting Rights

     The holders of the Series D Preferred Stock have no voting power, except as
otherwise provided by the General Corporation Law of the State of Delaware
("DGCL"), in this Article 7, and in Article 8 below.

     Notwithstanding the above, the Corporation shall provide each Holder of
Series D Preferred Stock with prior notification of any meeting of the
shareholders (and copies of proxy materials and other information sent to
shareholders).  In the event of any taking by the Corporation of a record of its
shareholders for the purpose of determining shareholders who are entitled to
receive payment of any dividend or other distribution, any right to subscribe
for, purchase or otherwise acquire (including by way of merger, consolidation or
recapitalization) any share of any class or any other securities or property, or
to receive any other right, or for the purpose of determining shareholders who
are entitled to vote in connection with any proposed liquidation, dissolution or
winding up of the Corporation, the Corporation shall mail a notice to each
Holder, at least 30 days prior to the consummation of the transaction or event,
whichever is earlier), of the date on which any such action is to be taken for
the purpose of such dividend, distribution, right or other event, and a brief
statement regarding, the amount and character of such dividend, distribution,
right or other event to the extent known at such time.

     To the extent that under the DGCL the vote of the Holders of the Series D
Preferred Stock, voting separately as a class or series as applicable, is
required to authorize a given action of the Corporation, the affirmative vote or
consent of the Holders of at least a majority of the outstanding shares of
Series D Preferred Stock represented at a duly held meeting at which a quorum is
present or by written consent of a majority of the outstanding shares of Series
D Preferred Stock (except as otherwise may be required under the DGCL) shall
constitute the approval of such action by the class.  To the extent that under
the DGCL holders of the Series D Preferred Stock are entitled to vote on a
matter with holders of Common Stock, voting together as one class, each share of
Series D Preferred Stock shall be entitled to a number of votes equal to the
number of shares of Common Stock into which it is then convertible using the
record date for the taking of such vote of shareholders as the date as of which
the Conversion Price is calculated.  Holders of the Series D Preferred Stock
shall be entitled to notice of all shareholder meetings or written consents (and
copies of proxy materials and other information sent to shareholders) with
respect to which they would be entitled to vote, which notice would be provided
pursuant to the Corporation's bylaws and the DGCL.

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<PAGE>

     Except as otherwise required by applicable law, subject to receipt of the
approval of the Holders of the Series D Preferred Stock as required herein, the
Corporation may alter or change the rights, preferences or privileges of the
Series D Preferred Stock without the approval of any other class or series of
capital stock of the Corporation.

                                   ARTICLE 8
                             Protective Provisions

     So long as shares of Series D Preferred Stock are outstanding, the
Corporation shall not, without first obtaining the approval (by vote or written
consent, as provided by the DGCL) of the Holders of at least a majority of the
then outstanding shares of Series D Preferred Stock:

     (a)  alter or change the rights, preferences or privileges of the Series D
          Preferred Stock;

     (b)  create any new class or series of capital stock having a preference
          over the Series D Preferred Stock as to distribution of assets upon
          liquidation, dissolution or winding up of the Corporation ("Senior
          Securities") or alter or change the rights, preferences or privileges
          of any Senior Securities so as to affect adversely the Series D
          Preferred Stock;

     (c)  increase the authorized number of shares of Series D Preferred Stock;
          or

     (d)  do any act or thing not authorized or contemplated by this Certificate
          of Designation which would result in taxation of the holders of shares
          of the Series D Preferred Stock under Section 305 of the Internal
          Revenue Code of 1986, as amended (or any comparable provision of the
          Internal Revenue Code as hereafter from time to time amended).

     In the event Holders of least a majority of the then outstanding shares of
Series D Preferred Stock give their approval to allow the Corporation to alter
or change the rights, preferences or privileges of the shares of Series D
Preferred Stock, pursuant to subsection (a) above, so as to affect the Series D
Preferred Stock, then the Corporation will deliver notice of such approved
change to the Holders of the Series D Preferred Stock that did not approve such
alteration or change (the "Dissenting Holders") and Dissenting Holders shall
have the right for a period of 30 days to convert pursuant to the terms of this
Certificate of Designation as they exist prior to such alteration or change or
continue to hold their shares of Series D Preferred Stock.

                                   ARTICLE 9
                                 Miscellaneous

     Section 9.1   Loss, Theft, Destruction of Preferred Stock Certificates

     Upon receipt of evidence satisfactory to the Corporation of the loss,
theft, destruction or mutilation of shares of Series D Preferred Stock and, in
the case of any such loss, theft or destruction, upon receipt of indemnity or
security reasonably satisfactory to the Corporation, or, in the case of any such
mutilation, upon surrender and cancellation of the Series D Preferred Stock, the
Corporation shall make, issue and deliver, in lieu of such lost, stolen,
destroyed or mutilated shares of Series D Preferred Stock, new shares of Series
D Preferred Stock of like tenor.  The Series D Preferred Stock shall be held and
owned upon the express condition that the provisions of this Section 9.1 are
exclusive with respect to the replacement of mutilated, destroyed, lost or
stolen shares of Series D Preferred Stock and shall preclude any and all other
rights and remedies notwithstanding any law or statute existing or hereafter
enacted to the contrary with respect to the replacement of negotiable
instruments or other securities without the surrender thereof.

     Section 9.2  Who Deemed Absolute Owner

     The Corporation may deem the Person in whose name the Series D Preferred
Stock shall be registered upon the registry books of the Corporation to be, and
may treat it as, the absolute owner of the Series D Preferred Stock for the
purpose of receiving payment of dividends on the Series D Preferred Stock, for
the conversion of the Series D Preferred Stock and for all other purposes, and
the Corporation shall not be affected by any notice to the contrary.

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<PAGE>

All such payments and such conversion shall be valid and effectual to satisfy
and discharge the liability upon the Series D Preferred Stock to the extent of
the sum or sums so paid or the conversion so made.

     Section 9.3  Notice of Certain Events

     In the case of the occurrence of any Valuation Event described in Sections
6.1, or 6.6 of this Certificate of Designation, the Corporation shall cause to
be mailed to the Holder of the Series D Preferred Stock at its last address as
it appears in the Corporation's security registry, at least 20 days prior to the
applicable record, effective or expiration date hereinafter specified (or, if
such 20 days notice is not possible, at the earliest possible date prior to any
such record, effective or expiration date), a notice stating (x) the date on
which a record is to be taken for the purpose of such dividend, distribution,
issuance or granting of rights, options or warrants, or if a record is not to be
taken, the date as of which the Holders of record of Series D Preferred Stock to
be entitled to such dividend, distribution, issuance or granting of rights,
options or warrants are to be determination or the date on which such
reclassification, consolidation, merger, sale, transfer, dissolution,
liquidation or winding-up is expected to become effective, and (y) the date as
of which it is expected that Holders of record of Series D Preferred Stock will
be entitled to exchange their shares for securities, cash or other property
deliverable upon such reclassification, consolidation, merger, sale transfer,
dissolution, liquidation or winding-up.

     Section 9.4  Register

     The Corporation shall keep at its principal office a register in which the
Corporation shall provide for the registration of the Series D Preferred Stock.
Upon any transfer of the Series D Preferred Stock in accordance with the
provisions hereof, the Corporation shall register such transfer on the Series D
Preferred Stock register.

     The Corporation may deem the person in whose name the Series D Preferred
Stock shall be registered upon the registry books of the Corporation to be, and
may treat it as, the absolute owner of the Series D Preferred Stock for the
purpose of receiving payment of dividends on the Series D Preferred Stock, for
the conversion of the Series D Preferred Stock and for all other purposes, and
the Corporation shall not be affected by any notice to the contrary.  All such
payments and such conversions shall be valid and effective to satisfy and
discharge the liability upon the Series D Preferred Stock to the extent of the
sum or sums so paid or the conversion or conversions so made.

     Section 9.5  Withholding

     To the extent required by applicable law, the Corporation may withhold
amounts for or on account of any taxes imposed or levied by or on behalf of any
taxing authority in the United States having jurisdiction over the Corporation
from any payments made pursuant to the Series D Preferred Stock.

     Section 9.6  Headings

     The headings of the Articles and Sections of this Certificate of
Designation are inserted for convenience only and do not constitute a part of
this Certificate of Designation.


     In Witness Whereof, the Corporation has caused this Certificate of
Designation, Preferences and Rights to be signed by its duly authorized officers
on ___________________, 2000.


                              AMERICAN TELESOURCE INTERNATIONAL, INC.

                              By:  /s/ H. Douglas Saathoff
                                   -----------------------
                                   H. Douglas Saathoff
                                   Title:  Senior Vice President

                              By:  /s/ Charles R. Poole
                                   --------------------
                                   Name: Charles R. Poole
                                   Title: President

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<PAGE>

                                                                         ANNEX I

                           FORM OF CONVERSION NOTICE


To:  American TeleSource International, Inc.
     12500 Network Boulevard, Suite 407
     San Antonio, Texas 78249

     The undersigned owner of this Series D 6% Convertible Preferred Stock (the
"Series D Preferred Stock") issued by American TeleSource International, Inc.
(the "Corporation") hereby irrevocably exercises its option to convert
__________ shares of the Series D Preferred Stock into shares of the common
stock, par value $0.001 per share ("Common Stock"), of the Corporation in
accordance with the terms of the Certificate of Designation.  The undersigned
hereby instructs the Corporation to convert the number of shares of the Series D
Preferred Stock specified above into Shares of Common Stock Issued at Conversion
in accordance with the provisions of Article 6 of the Certificate of
Designation.  The undersigned directs that the Common Stock issuable and
certificates therefor deliverable upon conversion, the Series D Preferred Stock
re-certificated, if any, not being surrendered for conversion hereby, together
with any check in payment for fractional Common Stock, be issued in the name of
and delivered to the undersigned unless a different name has been indicated
below.  All capitalized terms used and not defined herein have the respective
meanings assigned to them in the Certificate of Designation.  So long as the
Series D Preferred Stock shall have been surrendered for conversion hereby, the
conversion pursuant hereto shall be deemed to have been effected at the date and
time specified below, and at such time the rights of the undersigned as a Holder
of the Series D Preferred Stock shall cease and the Person or Persons in whose
name or names the Common Stock Issued at Conversion shall be issuable shall be
deemed to have become the holder or holders of record of the Common Shares
represented thereby and all voting and other rights associated with the
beneficial ownership of such Common Shares shall at such time vest with such
Person or Persons.

Date and time:_____________________


                                        ________________________________________
                                        Signature

Fill in for registration of Series D Preferred Stock:


________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
Please print name and address (including zip code number)

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