<PAGE>

                                                                    EXHIBIT 10.4

                           NTFC CAPITAL CORPORATION
                              $2,000,000 LOAN TO
                    AMERICAN TELESOURCE INTERNATIONAL, INC.

     1.   COMMITMENT TO LEND: (a) Subject to the terms and conditions provided
in this Loan and Security Agreement ("Agreement") and so long as no Event of
Default (as defined in Section 14 hereof) or event or condition which with
notice or passage of time or both would constitute an Event of Default has
occurred and is continuing hereunder, Lender agrees to lend to AMERICAN
TELESOURCE INTERNATIONAL, INC., a Delaware corporation ("ATII"), to the Domestic
Subsidiaries of ATII which are signatories to the Agreement, and to such
additional Domestic Subsidiaries of ATII which hereafter may become a party
hereto pursuant to Section 1(b) hereof (ATII, Domestic Subsidiaries of ATII
which are signatories to this Agreement, and such additional Domestic
Subsidiaries of ATII which may hereafter become a party hereto pursuant to
Section 1(b) of this Agreement are individually referred to as a "Borrower" and
                                                                  --------
collectively as the "Borrowers"), until the Financing Termination Date set forth
                     ---------
above, an amount in the aggregate not to exceed the Commitment Amount set forth
above, which sum shall be used solely for the purchase by a Borrower of
telecommunications equipment and associated software sublicenses from the
Supplier pursuant to one or more Purchase Agreements (individually, a "Purchase
Agreement" and collectively, the "Purchase Agreements") made by and between the
Supplier and such Borrower for installation in the United States, Mexico and
other Latin American jurisdictions. "Subsidiary" means, as to any person, a
                                     ----------
corporation, partnership, limited liability company or other entity of which
shares of stock or other ownership interests having ordinary voting power (other
than stock or other ownership interests having such power only by reason of the
happening of a contingency) to elect a majority of the board of directors or
other managers of such corporation, partnership, limited liability company, or
other entity, are at the time owned, or the management of which is otherwise
controlled, directly or indirectly, through one or more intermediaries, or both,
by such person. "Domestic Subsidiary" means a Subsidiary incorporated under the
                 -------------------
laws of the United States, one of the states of the United States, or the
District of Columbia. Unless otherwise qualified, all references to a
"Subsidiary" or to "Subsidiaries" in this Agreement shall refer to a Subsidiary
or Subsidiaries of ATII.

     (b)  Lender and each Borrower acknowledge and agree that subject to the
terms and conditions of this Agreement, ATII shall cause domestic
Subsidiaries of ATII formed or acquired hereafter to become a Borrower
hereunder (without the consent of any other Borrower) by executing a form
of the annex to this Agreement set forth as Exhibit A and such additional
                                            ---------
Domestic Subsidiaries may thereafter borrow amounts hereunder to finance
the acquisition of equipment which is, or is to be placed, in the United
States, Mexico and other Latin American jurisdictions. ATII and the other
Borrowers agree that, prior to any additional Subsidiary of ATII becoming a
Borrower hereunder, such Subsidiary and ATII shall execute and deliver to
Lender a form of the annex to this Agreement set forth as Exhibit A, and if
required by Lender cause the delivery of an opinion of legal counsel to
ATII and such additional Subsidiary dated the date of the execution of the
form of the annex to this Agreement set forth as Exhibit A in form and
substance satisfactory to lender and such other documents as the Lender may
<PAGE>

request, including but not limited to a certificate of a responsible
officer of such additional Subsidiary as to the authority of such
additional Subsidiary to execute, deliver and perform this Agreement and
the Note and as to the incumbency and signature of the officer or officers
signing Borrowing Certificates and Note.

     (c)  The obligation of each Borrower hereunder and under the Note
evidencing amounts from time to time advanced hereunder to a Borrower shall
be joint and several obligations at ATII and all other Borrowers.

     2.   THE NOTE AND PAYMENT TERMS: All advances of funds to a Borrower (an
"Advance") shall be evidenced by a [sic] one or more promissory notes in the
form of Exhibit B executed by the Borrowers (individually and collectively, the
"Note"), which shall be in a form and substance satisfactory to the Lender and
represent the joint and several obligations of the Borrowers to pay the
aggregate unpaid advances on the base (the "Principal Amount"), plus any accrued
interest thereon, and all extensions, renewals or modifications thereof
including, without limitation, any expenses of Lender or other amounts due to
Lender under the Note or this Agreement. The Note shall be dated the Closing
Date and shall mature on the Maturity Date. Except as otherwise provided herein,
the Note shall bear interest from the borrowing date on the outstanding unpaid
Principal Amount thereof at the Interest Rate stated above (compounded monthly
and computed on the basis of a year of 365 days for the actual days elapsed). In
computing interest on the Note, the borrowing date shall be included and the
date of payment excluded. Each Borrower and Lender understand that the Payment
Schedule is intended to amortize fully the principal amount of the Note and any
other principal and interest amounts outstanding will be added to the final
payment on the Maturity Date. In any event, the entire outstanding principal
amount of the Note and all accrued but unpaid interest and all other outstanding
amounts due thereunder shall be paid on the Maturity Date. If a Payment Date is
not a business day, the Payment Date shall be on the first business day
following the nonbusiness day, and interest thereon shall be payable tat [sic]
the rate in effect during such extension. Each payment shall be credited first
to accrued and unpaid interest and the balance to the Principal Amount (provided
that in any event the entire Principal Amount of the Note then outstanding
together with any accrued and unpaid interest shall be paid on the Maturity
Date). The Lender is authorized to endorse the date and amount of each Advance
and each payment of the Principal Amount and interest with respect to the Note
on the schedule annexed to and constituting a part of the Note, which
endorsement shall constitute prima facie evidence of the accuracy of the
information endorsed.

     All payments shall be made in lawful money of he United States of America
in immediately available funds and without set off or counterclaim to the Lender
or any subsequent assignee of a Note.

     Each Borrower agrees to pay all amounts owing by it under this Agreement,
any Note or the other Loan Documents free and clear of and without deduction for
any present or future taxes (excepting any taxes assessed on Lender's income by
the United States of America) (collectively, the "Taxes") and represents that it
                                                  -----
has paid, and agrees that it shall pay, when due all applicable deductions or
withholdings for or on account of
<PAGE>

any Taxes, levies, duties, fees, deductions or withholdings, restrictions or
conditions of any nature imposed by or on behalf of any jurisdiction (other than
the United States of America) or any taxing authority (other than the United
States of America) whatsoever on the payments by Borrowers to Lender under this
Agreement, any Note or the other Loan Documents and

               (A)  that if it is prevented by operation of law from paying any
          Taxes, then the interest rate or fees required to be paid under this
          Agreement, any Note or the other Loan Documents shall be increased by
          the amount necessary to yield to Lender interest or fees at the rates
          specified in this Agreement, any Note or the other Loan Documents
          after provision for the payment of all such Taxes and without taking
          into account any tax benefits accruing to Lender from such payment;

               (B)  that it shall at the request of Lender execute and deliver
          to Lender such further instruments as may be necessary or desirable to
          effect the increase in the interest or fees as provided for in clause
          (A) immediately above, including a new Note to be issued in exchange
          for any Note theretofore issued;

               (C)  that it shall hold Lender harmless from and against any
          liabilities with respect to any Taxes (whether or not properly or
          legally asserted); and

               (D)  that it shall provide Lender with the original or a
          certified copy of evidence of the payment of any Taxes by it, as
          Lender may reasonably request, or, if no taxes have been paid to
          provide to Lender, at Lender's request, with a certificate from the
          appropriate taxing authority or an opinion of counsel acceptable to
          Lender stating that no Taxes are payable.

     If Lender shall receive a refund of any Taxes paid by Borrower pursuant to
this Section by reason of the fact that such Taxes were not correctly or legally
asserted, Lender shall within sixty (60) days after receipt of such refund pay
to Borrower the amount of such refund, as determined solely by Lender; provided,
                                                                       --------
however, that in no event shall the amount paid by Lender to Borrower pursuant
-------
to this sentence exceed the amount of Taxes originally paid by Borrower;  and
further provided that Lender shall not have any obligation under this Agreement
------- --------
to claim or otherwise seek to obtain any such refund.

     Notwithstanding the foregoing, if the Borrowers shall fail to pay within
five (5) days after when due any part of the Principal Amount remain, interest
or any amount payable hereunder or under a Note, such amount shall bear interest
at a rate per annum that is three percent (3%) higher than the Interest Rate
from the due date until such overdue Principal Amount, interest, or other
amounts are paid in full (before and after judgment) whether or not any notice
of default in the payment thereof has been delivered.
<PAGE>

     Notwithstanding any provision of this Agreement, it is the intent of the
Lender and the Borrowers that the Lender, or any subsequent holder of a Note,
shall never be entitled to receive, collect, reserve or apply, as interest, any
amount in excess of the maximum non-usurious lawful rate of interest permitted
to be charged by applicable law, as amended or enacted from time to time.  In
the event the Lender, or any subsequent holder of a Note, ever receives,
collects, reserves or applies as interest, interest in excess of the then
maximum lawful rate of interest, such amount which would be excessive interest
shall be deemed a partial prepayment of the Principal Amount and treated
hereunder as such (except that no prepayment premium otherwise applicable shall
be payable thereon), or, if the Principal Amount and all other amounts due are
paid in full, any remaining excess funds shall immediately be paid to the
Borrowers.  In determining whether or not the interest paid or payable, under
any specific contingency, exceeds the maximum lawful rate of interest, the
Borrowers and the Lender shall, to the maximum extent permitted under applicable
law, (a) exclude voluntary prepayments and the effects thereof as it may relate
to any fees charged by the Lender, and (b) amortize, prorate, allocate and
spread, in equal parts, the total amount of interest throughout the entire term
of the Indebtedness; provided that if the Indebtedness is paid in full prior to
the end of the full contemplated term hereof, and if the interest received over
the actual period of existence hereof exceeds the maximum lawful rate of
interest, the Lender or any subsequent holder of a Note shall refund to the
Borrowers the amount of such excess, and in such event shall not be subject to
any penalties provided by any laws for contracting for, charging, reserving,
collecting or receiving interest in excess of the maximum lawful rate of
interest.

     3.   PROCEDURES FOR BORROWING:  ATII (and if a borrower other than ATII is
acquiring the equipment to be financed thereby, such other Borrower) shall
execute and deliver to Lender, at least five (5) business days prior to the date
of the requested Advance, a Borrowing Certificate in the form of Exhibit C-1 (a
"Domestic Advance Borrowing Certificate") to request Advances to finance the
acquisition by ATII or such other borrower of equipment which is, or is to be
placed, in jurisdictions within the United States, and at least thirty (30)
business days prior to the date of the requested Advance, a Borrowing
Certificate in the form of Exhibit C-2 ( a "Foreign Advance Borrowing
Certificate" and together with a Domestic Advance Borrowing Certificate, a
"Borrowing Certificate") to request Advances to finance the acquisition by ATII
or such other Borrower of equipment which is, or is to be placed, in Mexico or
another Latin American jurisdiction.  Each Borrowing Certificate shall be in
form and substance satisfactory to Lender, and shall specify the business day on
which the borrowing is to be made and the amount of the borrowing and have
attached thereto the applicable purchase order issued by such Borrower and
related invoice from the Supplier which is to be paid by Lender with the
proceeds of the loan.  On the borrowing data specified in the Borrowing
Certificate, providing that all conditions precedent have been satisfied, Lender
shall transmit the borrowed funds to an account maintained by and in the name of
Supplier.  The aggregate principal amount of each borrowing shall be not less
than $25,000.  Lender shall not be required to make Advances more than twice per
calendar month.
<PAGE>

     4.   PLACE OF PAYMENT. The Principal Amount, interest and fees, if any,
shall be payable at 501 Corporate Centre Drive, Suite 600, Franklin, Tennessee
37067, or such other place as may be designated, from time to time in writing,
by Lender or any subsequent holder.

     5.   PREPAYMENT.  The Borrowers may, at their option and subject to the
satisfaction of the requirements of the next sentence, at any time and from time
to time, prepay any Advance, in whole or in part, upon at least (30) business
days prior written notice to Lender specifying the date and amount of prepayment
in a minimum amount of $50,000.  Any such prepayment occurring during the first,
second and third years following the date of such Advance shall be subject to a
prepayment premium equal to a percentage of the amount being prepaid as follows:
three percent (3%) if the prepayment is made during the first year following the
date of such Advance; two percent (2%) if the prepayment is made during the
second year following the date of such Advance; and one (1) percent if the
prepayment is made during the third year following the date of such Advance.

     6.   SECURITY INTEREST: OBLIGATIONS SECURED: Each Borrower (as debtor)
hereby assigns as collateral and grants to Lender (as secured party), as
security for all of the Indebtedness, a continuing security interest in and to,
all of such Borrower's right, title and interest in and to the property and the
property rights described in Section 7 hereof, whether now owned or hereafter
acquired or arising, wherever located, together with all substitutions therefor
and all accessions, replacements and renewals thereof, and in all proceeds and
products thereof (collectively, the "Collateral"). "Indebtedness" means all
                                     ----------     ------------
indebtedness, liabilities and obligations to Lender of ATII or any other
Borrower, of any class or nature, whether arising under or in connection with
this Agreement and/or all other documents, instruments, agreements or
certificates evidencing or securing any advance hereunder or any obligation for
the payment or performance thereof and/or executed and delivered in connection
with any of the foregoing (the "Loan Documents") or otherwise whether not
                                --------------
existing or hereafter incurred, direct or indirect, absolute or contingent,
secured or unsecured, matured or unmatured, joint or several whether for
principal, interest, fees, expenses, lease obligations, indemnities or
otherwise, including, without limitation, future advances of any sort, all
future advances made by Lender for taxes, levies, insurance and/or repairs to or
maintenance of the Collateral, the unpaid principal amounts of, and accrued
interest owned by the Borrowers on the Note, and any expenses of collection or
protection of Lender's rights, including reasonable attorneys' fees.

     7.   DESCRIPTION OF COLLATERAL.  The Collateral includes, and each Borrower
hereby grants Lender a security interest in, all such Borrower's presently
existing or hereafter acquired right, title and interest in, and to (i) the
equipment, fixtures, and other property identified in a Borrowing Certificate
pursuant to which Lender advances funds hereunder (Borrowing Certificates are
collectively referred to as the "Collateral Schedule") or otherwise acquired or
financed or refinances with loan proceeds from Lender, including without
limitation, hardware and software, components, wiring, cabling and associated
electronics and any and all replacements, additions, substitutions to or any of
the foregoing, together with all attachments, components, parts,
<PAGE>

accessions, improvements, upgrades, all accessories installed thereon or affixed
thereto and all of the foregoing forming an integral part thereof; and (ii) to
the extent not otherwise included, all proceeds of the foregoing, including
without limitation, (A) any and all proceeds of any insurance, indemnity,
warranty or guaranty payable to Borrower from time to time with respect to any
of the Collateral; (B) any and all payments (in any form whatsoever) made or due
and payable to a Borrower from time to time in connection with any requisition,
confiscation, condemnation, seizure or forfeiture of all or any part of the
collateral by any governmental body, authority, bureau or agency (or any person
action under color of governmental authority); (C) any and all other amounts
from time to time paid or payable under or in connection with any of the
Collateral; and (D) any and all cash proceeds and non-cash proceeds in the form
of equipment, inventory, accounts, general intangibles, chattel paper or other
proceeds (collectively, "Proceeds"), The Collateral Schedule is incorporated in
and made a part of this Agreement.

     8.   REPRESENTATIONS AND WARRANTIES: In order to induce the Lender to enter
into this Agreement and to make the loans contemplated herein, each Borrower
represents and warrants that on the date of the Note's execution and until
payment in full of the indebtedness:

     (a)  Each of ATII and each Subsidiary of ATII (I) is duly organized,
validly existing and in good standing under the laws of the jurisdiction in
which it was formed; (ii) has the power and legal authority to own or lease
and operate it's business as now being conducted; (iii) is properly
licensed, in good standing and duly qualified to do business in every
jurisdiction where necessary; (iv) if a Borrower hereunder, has the power
and authority and the legal right to make, deliver and perform this
Agreement and the Note and to borrow hereunder and has received all
necessary authorization from its directors or partners, as applicable, to
execute, deliver and perform this Agreement, the Note and any related
documents to be delivered pursuant to this Agreement, and (v) the Borrowers
other than ATII are, and will remain Subsidiaries of ATII for so long as
such Subsidiary remains obligated to Lender hereunder.

     (b)  The person executing this Agreement and the Note on behalf of each
Borrower has been given the authority to bind each Borrower, and this
Agreement and the Note constitute legally binding enforceable obligations
of each Borrower.

     (c)  The execution, delivery and performance of this Agreement and the Note
will not violate ATII's or any Subsidiary's charter, bylaws, partnership
agreement or other organizational papers, or any law, agreement or
undertaking to which ATII or any Subsidiary is a party, or by which ATII or
any Subsidiary is bound or affected.

     (d)  All required consents relative to the execution, delivery, and
performance of this Agreement and the Notes have been obtained, including
any required of the Federal Communications Commission, the Commerce
Commission for any state or other jurisdiction in which ATII or any
Subsidiary is operating "PUC") or any other governmental authority.
<PAGE>

     (e)  All information, reports and other papers and data with respect to
ATII and/or each Subsidiary (other than, projections) furnished to the Lender by
a Borrower at any time prior to the date hereof were, to the best knowledge of
each Borrower at the time the same were furnished, true and correct in all
material respects, or have been subsequently supplemented by other information,
reports or other papers or data, to the extent necessary to give the Lender a
true and accurate knowledge of the subject matter thereof in all material
respects; and all projections with respect to ATII and/or each Subsidiary
furnished by a Borrower, as supplemented were prepared or presented in good
faith by such Borrower and had a reasonable basis. No fact is known to any
Borrower which materially and adversely affects the business, operations, assets
(taken as a whole) or financial condition of ATII or any Subsidiary which has
not been set forth in the financial statements provided to Lender in connection
with this Agreement or in such information, reports, papers and data, or
otherwise disclosed in writing to the Lender prior to the first borrowing date
relative to the initial loan made, hereunder. All financial statements have been
prepared in accordance with GAAP applied consistently throughout the period
involved.

     (f)  There have been no material adverse changes in ATII's consolidated
financial position since the date of the financial statements provided to
Lender in connection with the credit approval of ATII relative to this
Agreement.

     (g)  There is no litigation, investigation or proceeding threatened or
pending against ATII or any Subsidiary or against any of its assets or
revenues which, if decided adversely, would have a material adverse effect
upon ATII's consolidated financial condition or its business, operations or
assets (taken as a whole).

     (h)  The Borrower requesting the Advance is the sole owner of and has good
and marketable title to each item of Collateral acquired with Proceeds of
an Advance (or will have at the time such Borrower acquires rights in the
Collateral hereafter arising), free and clear of all security interests,
claims, liens, and encumbrances except as granted to Lender. Lender has a
fully-perfected first priority lien on, and security interest in, all
right, title and interest of each Borrower in the Perfected Collateral
enforceable against such Borrower and third parties.

     (i)  Neither ATII nor any Subsidiary is in default under any agreement,
     mortgage, note, security agreement or other documents to which it is a
     Party or by which it, or any of its property, is bound in any respect which
     could be materially adverse to the business, operations, assets or
     financial condition of ATII on a consolidated basis, or which could
     materially adversely affect the ability of any Borrower to perform its
     obligations under this Agreement.

     (j)  Each of ATII and each Subsidiary has paid all taxes due, except such
taxes as are being contested in good faith and against which ATII or such
Subsidiary has set up reserves satisfactory to the Lender.

     (k)  No Borrower is engaged nor will any engage principally, or as one of
its important activities, in the business of extending credit for the
purpose of "purchasing" or
<PAGE>

"carrying" any "margin stock" within the respective meaning of each of the
quoted terms under Regulation U of the Board of Governors of the Federal
Reserve System now, and from time to time, hereafter in effect. No part of
the proceeds any loan will be used for "purchasing" or "carrying" "margin
stock" as defined or for any purpose which violates, or which would be
inconsistent with, the provisions of the regulations of such Board of
Governors.

     (l)  No Borrower is an "investment company" or company "controlled" by an
"investment company," within the meaning the Investment Company Act of 1940
as amended.

     (m)  Neither ATII nor any Subsidiary is in violation of a federal or state
law, rule or regulation or determination of an arbitral court or other
governmental authority, in each case applicable or binding upon ATII or any
Subsidiary or any of its properties or to which ATII any such Subsidiary or
any of its properties are subject, in each ca [sic] which individually or in the
aggregate would have a material adverse effect on the rights of the
Subsidiary or the security interest of Lender the Collateral or ATII's
consolidated financial condition or operations assets taken as a whole.

     (n)  There is no event which is, or with notice or lapse time, or both,
would be an Event of Default as defined in Section 14 this Agreement.

     (o)  Purchase Agreement has been duly executed and delivered by the
Borrower and the Supplier with respect to the Collateral which proceeds of
an Advance are being requested by such Borrower and will be in full force
and effect on the date of such Advance.

     (p)  ATII has reviewed its operations and those of its Subsidiaries with a
view to assessing whether its business (together wit [sic] the businesses of its
Subsidiaries on a consolidated basis), will be vulnerable to a Year 2000 Problem
or will be vulnerable to the effects of Year 2000 Problem suffered by any major
commercial customers of ATII or of any of its Subsidiaries, and has a reasonable
basis to believe that no Year 2000 Problem will cause a material adverse effect
to ATII on a consolidated basis. For purposes of this Agreement, "Year 2000
Problem means any significant risk that computer hardware, software or equipment
containing embedded microchips essential to the business or operations of ATII
or any other Borrower will not, in the"case of dates or time periods occurring
after December 31, 1999, function at least at effectively and reliably as in the
case of times or time periods occurring before January 1, 2000, including the
making of leap year calculations.

    (q)  Each Domestic Subsidiary of ATII is a signatory to this Agreement.

     9.   CONDITIONS PRECEDENT:

     (a)  Initial Loan. The obligation of the leader to make the initial loan on
the first borrowing date shall be subject to the fulfillment prior to or
contemporaneously with the making of such loan of the following conditions
precedent:
<PAGE>

          (i)   The Lender shall have received an opinion of legal counsel to
ATII and each other Borrower as of such date, dated the first borrowing
date, in a form and substance satisfactory to Lender.

          (ii)  Lender shall have received a certificate of a responsible
officer of ATII and each other Borrower as of such date, dated the first
borrowing date, as to the authority of such Borrower(s) to execute, deliver
and perform this Agreement and the Note.

          (iii) The Lender shall have received a certificate of a responsible
officer of ATII and each other Borrower as of such date, dated the first
borrowing date, as to the incumbency and signature of the officer or officers
signing the Agreement, the Note and any other certificate or other documents to
be delivered pursuant thereto, together with evidence of the incumbency of each
responsible officer.

          (iv)  The Lender shall have received copies of all consolidated
financial statements of ATII as required by Lender.

          (v)   The Lender shall have received copies, certified by a
responsible officer of ATII to the satisfaction of Lender, of contracts in
effect between one or more Borrowers and Qwest and Primetec containing such
terms as are customary for such business (including but not limited to
pricing) in form and substance satisfactory to Lender.

          (vi)  The Lender shall have received copies, certified by a
responsible officer of ATII to the satisfaction of Lender, of a [illegible]
vendor financing facility in effect between one or more borrowers and
Network Equipment Technologies, Inc. providing at least $1,000,000 of
unrestricted borrowing availability and containing such terms as are
customary (including but not limited to interest rates) in form and
substance satisfactory to Lender.

     (B)  All Loans. The obligation of the Lender to make any loan (including
the initial loan) to be made by it on any borrowing date is subject to the
satisfaction of the following conditions precedent:

          (i)   The Lender shall have received a Note conforming to the
requirements here, and fully executed by each Borrower.

          (ii)  The representations and warranties made by ATII and each other
Borrower in this Agreement and in each Borrowing Certificate and shall be
correct in all material respects on and as of such borrowing date and after
giving effect to the loan to be made on such borrowing date.

          (iii) No event of Default or event or condition which with notice or
passage of time or both would constitute an Event of Default shall have occurred
and be continuing on such borrowing date or after giving effect to the loan to
be made on such borrowing date.
<PAGE>

          (iv)   The Lender shall have received a Borrowing Certificate, dated
such borrowing date for such loan, satisfying the requirements of Section
3.

          (v)    Except where waived by Lender in the exercise of its reasonable
discretion, the Lender shall have received the waiver of liens and consent
of the real estate lessors of the Borrower, and or such other persons as
the Lender shall deem desirable, to facilitate the removal by the Lender,
upon the occurrence of an Event of Default, of all items of US Collateral
which are or were personalty where first located on any real property that
is subject to any real estate leases and/or mortgages, such waivers of
liens and consents to be in form and substance satisfactory to the Lender
and its counsel.

          (vi)   The Borrowers shall have (1) executed and delivered to Lender
all documents (including, without limitation, financing statements)
necessary to create in favor of Lender a first-priority perfected security
interest in, and lien on, Collateral located in the United States ("US
Collateral") with evidence of any necessary filing, registration or
recordation of such documents, the payment of recording, stamp or other
taxes measured by indebtedness or otherwise required as a result of filing,
registration or recordation of such documents and searches confirming the
absence of any other liens or security interests thereon, and (2) with
respect to jurisdictions in the United States for which Lender has not
previously received an opinion of counsel covering its security interests
in the US Collateral, delivered an opinion of counsel to the applicable
Borrower(s), dated the date of such Advance, in form and substance
satisfactory to Lender to the effect that the lien and security interest of
Lender on such US Collateral constitutes a perfected security interest in
favor of Lender.

          (vii)  the applicable Borrower(s) shall have (1) executed and
delivered to Lender all documents necessary to create in favor of Lender a
first-priority perfected security interest in, lien on, or trust or comparable
security ownership interest in, Collateral located in Mexico ("Foreign
Collateral," and together with US Collateral, the "Perfected Collateral"),
together with evidence of (x) any necessary filing, registration or recordation
of such documents, (y) the payment of recording, stamp or other taxes measured
by indebtedness or otherwise required as a result of filing, registration or
recordation of such documents and (z) the absence of any other liens or security
interests on such Foreign Collateral, and (2) delivered an opinion of counsel to
the applicable Borrower(s), dated the date of such advance, in form and
substance satisfactory to Lender to the effect that (y) the documents have been
validly executed and delivered by, and are binding and enforceable upon, the
applicable Borrower(s) and do not conflict with the application of Borrower's
organization documents, material contracts or applicable law, and (z) the
security interest in, lien on, or trust or comparable security ownership
interest of Lender on such Foreign Collateral "perfected" or otherwise
enforceable against such Borrower and the parties in favor of Lender under the
laws of such foreign jurisdiction.

          (viii) All proceedings and all other documents and legal matters in
connection with the transactions contemplated in the Agreement shall be
satisfactory in form and in substance to the Lender and its counsel.
<PAGE>

     10.  INTENTIONALLY DELETED.

     11.  AFFIRMATIVE COVENANTS:  Each Borrower with respect to itself and its
business, property and Collateral warrants, covenants and agrees that from the
Agreement date and until performance and payment in  full of the Indebtedness,
it will:

     (a)  Furnish to Lender as soon as available, but in any event within one
hundred and twenty (120) days after the end of each fiscal year of ATII, a
copy of the consolidated balance sheet of ATII as of the end of such year
and the related statements of earnings and changes in financial position
for such year, setting forth in each case in comparative form, the figures
for the previous year audited by independent certified public accountants.
The financial statements shall be complete and correct in all material
respects, and be prepared in reasonable detail and in accordance with GAAP
applied consistently throughout the periods reflected therein (except as
approved by such accountants or a responsible officer, as the case may be,
and disclose therein).

     (b)  Furnish to Lender, concurrently with the delivery of the financial
statements referred to in subsection (a) hereof, a certificate of a
responsible officer of ATII and each other Borrower stating that, to the
best of such officer's knowledge, ATII and each other Borrower during such
period, has observed or performed all of its covenants and other
agreements, and satisfied every condition contained in this Agreement and
in the Note to be observed, performed or satisfied by it and that such
officer has obtained no knowledge of any Event of Default except as
specified in such certificate.

     (c)  Promptly upon receipt thereof, furnish to Lender one copy of each
written financial audit report submitted to ATII by independent accountants
resulting from any annual, interim or special audits made by them of ATII's
books.

     (d)  Furnish to Lender copies of all financial statements and material
reports which ATII or any other Borrower may make to, or file with, the
Securities and Exchange Commission or any successor.

     (e)  Pay promptly when due all taxes, assessments, governmental charges,
claims for labor, supplies, rent and other obligations, which, if unpaid,
might become a lien against the Perfected Collateral or any Borrower's
other assets, except liabilities (I) being contested in good faith and by
appropriate proceedings, which proceedings do not involved any danger of
the sale, forfeiture or loss of the Perfected Collateral or any interest
therein or a material part of ATII's or such Borrower's other assets, and
(ii) against which ATII has set up reserves satisfactory to the Lender.

     (f)  Comply, and cause each Subsidiary to comply, with all applicable laws,
statutes, orders, rules, regulations and directions applicable to ATII
and/or such Subsidiary and the Perfected Collateral or any part thereof or
operation of ATII or any Subsidiary's business, except where the failure to
comply will not have a material adverse effect on the value of the
Perfected Collateral or the operations of ATII on a consolidated basis;
provided that ATII or such Subsidiary may contest any such statutes,
<PAGE>

orders, rules, regulations, and directions in any reasonable manner which
will not, in Lender's option, adversely affect Lender's rights or ATII's or
such Subsidiary's financial condition, business or operations taken as a
whole or the priority of the lien or security interested in the Perfected
Collateral.

     (g)  Maintain and preserve in full force and effect all rights, privileges,
licenses, and franchises applicable to ATII and each Subsidiary necessary
for the orderly and efficient conduct of ATII's and/or each Subsidiary's
business as is now conducted including, without limitation, any licenses or
authorizations required by the FCC or any other public utility commission
or comparable regulatory agency (a "PUC") for the operation and maintenance
of its present systems.

     (h)  Perform and comply in all material respects with all obligations under
the contracts and all other agreements to which it is a party or by which
it is bound relating to the Collateral except where the failure to do so
would not materially and adversely affect the value of the Collateral taken
as a whole.

     (i)  Advise Lender promptly, in reasonable detail (i) of any lien, security
interest, encumbrance or claim made or asserted against any of the
Collateral, (ii) of any material change in the composition of the
Collateral, and (iii) of the occurrence of any other event which would have
a material adverse effect on the aggregate value of the Collateral, the
security interest created hereunder, or on ATII"s or any Subsidiary's
financial condition, business, or operations.

     (j)  (1) Maintain books, records and accounts which, in reasonable detail,
accurately and fairly reflect its transactions and dispositions of its
assets and maintain a system of internal accounting controls sufficient to
provide reasonable assurances that (A) transactions are executed in
accordance with managements' general or specific authorization, (B)
transactions are recorded as necessary (x) to permit preparation of
financial statements in conformity with GAAP and (y)  to maintain
accountability for assets, (C) access to assets is permitted only in
accordance with management's general or specific authorization and (D) the
recorded accountability for assets is compared with the existing assets are
reasonable intervals and appropriate action is taken with respect to any
differences, and (2) prepare all financial statements required hereunder in
accordance with GAAP consistently applied and in compliance with the
regulations of any governmental regulatory body having jurisdiction over
ATII or any Subsidiary or ATII or any Subsidiary's business and keep such
books and records pertaining to its financial affairs and to the Collateral
at ATII's address set forth above.

     (k)  Permit Lender or its representatives, at all reasonable times, to
inspect and copy (at Lender's expense except after the occurrence and
during the continuance of an Event of Default or event or condition which
with the passage of time or the giving of notice or both would constitute
an Event of Default) each Borrower's books and records pertaining to its
financial affairs and to the Collateral;

     (l)  Keep the Collateral at the original location set forth in the
Collateral Schedule and such principal place of business at the address set
forth above and not move
<PAGE>

any of the Collateral from such locations, or change the location of ATII's or
any other Borrower's principal place of business without giving Lender at least
thirty (30) days advance written notice of such change or move, and in
connection with any change in location of Collateral or of the principal place
of business of ATII or any other Borrower, at its cost and expense, from time to
time, at the written request of Lender, executed, deliver, file or record
documents, agreements and instruments (in such manner and form as Lender may
reasonably require) in order to create, preserve, perfect, validate or satisfy
the first priority security interest in, lien on, or trust or comparable
security ownership interest in the Collateral as a result of the move of the
Collateral or of the change in ATII's or such other Borrower's principal place
of business.

     (m)  Keep the Collateral in good repair and operating condition, ordinary
wear and tear excepted, and maintain the Collateral owned or used by that
Borrower in good working order in accordance with established maintenance
procedures such that the Collateral performs to published specifications
and shall maintain the equipment within two of the latest product computing
loads of the Supplier, and permit Lender or its representatives at all
times, upon reasonable notice, to enter into and upon any premises where
any of the Collateral is located for the purpose of inspecting it,
observing its use or otherwise protecting its interest therein.

     (n)  If any Collateral, in whole or in part, shall be lost, stolen or
destroyed or damaged, or is taken in any condemnation or similar proceeding
by a governmental authority (any such Collateral is referred to as the
"Affected Collateral"), promptly and fully notify Lender and (I)
immediately place the Affected Collateral in good condition and working
order, or (ii) replace the Affected Collateral with one of like value which
is in good repair, condition, and working order, and grant a first priority
perfected security interest in, lien on, on trust or comparable security
ownership interest in such substitution to the same extent that Lender had
(or was required to have) in the Affected Collateral, or (iii) prepay
Lender, without prepayment premium, loans in an amount equal to the value
of such Affected Collateral.

     (o)  At its cost and expense, from time to time, at the written request of
Lender, execute, deliver, file or record document agreements and
instruments (in such manner and form as Lender may reasonably require) in
compliance with or to accomplish the covenants and agreements of each
Borrower in this Agreement; in order to create, preserve, perfect, validate
or satisfy the security interest in, lien on, trust or comparable security
ownership interest in the Collateral grant hereunder.  Each Borrower also
hereby authorizes Lender to file any sub-financing statement or amendment
thereto, without the signature of the Borrower, or with a copy or telecopy
of the Borrower's signature, to the extent permitted by applicable law, or
after the occurrence and during the continuance of an Event of Default or
event or condition which with the passage of time or the giving of notice
or both would constitute an Event of Default hereunder to execute any
financing statement or amendment thereof on behalf of each Borrower as each
Borrower's attorney-in-fact Lender will promptly provide such Borrower with
copies of any such financing statements.
<PAGE>

     (p)  ATII shall take all actions necessary and commit adequate resources to
assure that computer-based and other systems of ATII and its Subsidiaries
are able to process dates effectively, including dates before, on and after
January 1, 2000 without experiencing any Year 2000 Problem that could cause
a material adverse effect to ATII.  At the request of Lender, ATII will
provide Lender with assurances and substantiations (including but not
limited to the results of internal and external audit reports prepared in
the ordinary course of business) reasonably acceptable to Lender as to the
capability of ATII and it's Subsidiaries to conduct its and their
businesses and operations before, on and after January 1, 2000, without
experiencing a Year 2000 Problem causing a material, adverse effect.

     (q)  Cause each Domestic Subsidiary of ATII formed or acquired after the
date hereof to become a Borrower hereunder in conformity with the terms and
conditions of Section 1(b).

     (r)  Obtain Lender's prior written consent before using or generating any
press release, advertisement, publicity materials or other publication in
which the name or logo of Lender or any of its affiliates is used or may be
reasonably inferred, and will not distribute any such materials in the
absence of such prior written approval.

     (s)  (i)  Comply with the financial covenants set forth on Exhibit C.

          (ii) All accounting and financial terms herein shall be deemed to
include references to consolidated and consolidating principles. Covenants,
representations and agreements with respect to ATII and its properties and
activities shall be deemed to refer to ATII and the other Borrowers
collectively. The following words and terms shall have the following
meanings unless the context otherwise clearly requires:

          "Adjusted EBITDA":  for the most recent 4 fiscal quarters of ATII
           ---------------
being measured, ATII's EBITDA, plus (I) beginning period cash, and (ii) new
proceeds from Subordinated Debt, equity and vendor debt.

          "Book Capitalization":  the sum of common stock, preferred stock,
           -------------------
additional paid in capital and Subordinated Debt, in each case [a]s shown on
ATII's balance sheet in accordance with GAAP.

          "Total Debt":  of any person means, without duplication, (a) all items
           ----------
of indebtedness or liability which in accordance with generally accepted
accounting principles, consistently applied, would be included in determining
total liabilities as shown on the liability side of a balance sheet as of the
date as of which indebtedness is to be determined indebtedness or other
liabilities secured by any mortgage, security agreement, pledge, or lien
existing on or encumbering property owned by such person, whether or not the
indebtedness or other liabilities secured thereby shall have been assumed by
such person, (c)  all indebtedness of such person (i) which such person has
directly or indirectly guaranteed, endorsed (otherwise than for collection or
deposit in the ordinary course of business), discounted with recourse, agreed
(contingently or
<PAGE>

otherwise) to purchase or repurchase or otherwise acquire, (ii)
in respect of which such person has agreed to supply or advance funds (whether
by way of loan, purchase of securities or capital contribution, through a
commitment to pay for property or services regardless of the nondelivery of such
property or the nonfurnishing of such services or otherwise), or (iii) in
respect of which such person has otherwise become directly or indirectly liable,
and (d) all obligations of such person under any now or hereafter existing
interest swap or hedge agreements (net of any amounts owed to that person under
any such swap or hedge agreements).

          "Debt Service": for the most recent 4 fiscal quarters of ATII being
           ------------
measured, the sum of (i) all amortized principal and interest payments that ATII
is required to make during such period on account of all of its Total Debt
including, without limitation, (a) amounts due during such period on account of
capitalized leases, (b) the then current portion of any long-term Total Debt of
ATII calculated in accordance with GAAP, (c) amounts due on short-term Total
Debt of ATII, and (d) amounts due under this Loan Agreement and the Note, plus
(ii) capitalized expenditures.

          "EBITDA": for any fiscal period, ATII's actual operating earnings from
           ------
ongoing operations and before interest, taxes, depreciation  and amortization
for such fiscal period.

          "Senior Debt":  Total Debt of ATII and the Borrower, other than
           -----------
Subordinated Debt.

          "Subordinated Debt":  Indebtedness that (i) does not require any
           -----------------
payment of principal until twelve (12) months after the Maturity Date, (ii)  is
issued on market terms prevailing at the time and (iii) is subordinated on terms
reasonably acceptable to Lender to the Indebtedness created hereunder or
pursuant to any other Loan Document.

     (t)  Furnish to Lender such additional information or documents,
certificates, reports and agreements regarding ATII or any other Borrower, its
financial condition or the Collateral, as Lender may reasonably request.

     12.  NEGATIVE COVENANTS: Until payment in full of the indebtedness, each
Borrower covenants that it will not directly or indirectly;

     (a)  Sell, lease, assign, transfer, pledge, create, or permit a security
interest in, or otherwise encumber any of its rights therein, or permit any
levy, lien or encumbrance thereon in favor of anyone other than Lender.

     (b)  Use, or permit the Collateral to be used, for any unlawful purpose or
in violation of any law, statute or ordinance.

     (c)  Permit the Collateral to become part of, or be affixed to, any real
property without first assuring, to the reasonable satisfaction of Lender, that
Lender's security interest will be prior and senior to any interest or lien then
held, or thereafter acquired, by any mortgagee of such real property or the
owner or purchaser of any interest therein
<PAGE>

     (d)  Permit the Collateral to comprise a part of any borrower's inventory.

     (e)  Permit anything to be done that may impair the value of any of the
Perfected Collateral or the security intended to be afforded by this Agreement.

     (f)  Dispose of any part of the Collateral without the express prior
written consent of Lender.

     (g)  Change its name or change its corporate structure in any material way
without giving Lender at least thirty (30) days advance written notice thereof,
and ensuring that any steps that Lender may deem desirable to continue the
perfection and priority of Lender's security interests in the Collateral shall
have been taken.

     (h)  Engage, or permit any Subsidiary to engage, in any business activities
or operations substantially different from or unrelated to the present business
activities or operations substantially different from or unrelated to the
present business activities and operations of ATII and its current Subsidiaries.

     (i)  Enter into, become the subject of or effect any transaction of merger,
acquisition or consolidation or liquidate, wind up or dissolve itself (or suffer
any liquidation or dissolution), or convey, sell lease, transfer or otherwise
dispose of, in one transaction or a series of transactions, all or any
substantial pert of any Borrower's business or assets, whether now owned or
hereafter acquired.

     (j)  Change the fiscal year end of ATII from December 31 except with the
prior written consent of Lender, which consent shall not be unreasonably
withheld.

     (k)  Create otherwise cause or permit to exist or become effective any
encumbrance or restriction on the ability of any Subsidiary to (i) pay dividends
or make any other distributions on or in respect of its capital stock; (ii) make
loans or advances or to pay any indebtedness or other obligation owned to a
Borrower; or (iii) transfer any of its property or assets to a Borrower, except
for encumbrances or restrictions existing under or by reason of: (1) applicable
law; or (2) customary non-assignment provisions of any contract or any lease
governing a leasehold interest or Subsidiary.

     13.  RISK OF LOSS AND INSURANCE: All risk of loss of, damage to, or
destruction of the Collateral shall, at all times, be with each Borrower. Each
Borrower shall procure and maintain with financially sound and reputable
companies, insurance policies (i) insuring the Collateral against loss by fire,
explosion, theft and such other casualties as are usually insured against by
companies engaged in the same or similar business, and (ii) insuring such
Borrower and the Lender against liability for personal injury and property
damage relating to the Collateral. The policies shall be in such form and in
such amounts and coverage as may be reasonably satisfactory to the Lender, with
losses payable to such Borrower and the Lender as their respective interest may
appear. Each Borrower shall, if requested by Lender, deliver to Lender evidence
that such insurance coverage is in effect. All insurance shall (i) contain a
breach of warranty clause in favor of the Lender, (ii) provide that no
cancellation, reduction in amount or change in coverage thereof shall be
effective until at least thirty (30) days after receipt by
<PAGE>

the Lender of written notice thereof, and (iii) be reasonably satisfactory in
all respects to the Lender. If any Borrower fails to furnish such insurance or
fails to pay the premiums therefor, Lender may do so or may obtain insurance of
its interest only and add the amount of any such premium thereof to the other
amounts secured hereby. Lender is under no obligation nor duty, however, to pay
such premiums or obtain such insurances.

     14.  DEFAULT:  The occurrence of any one or more of the following will
constitute an "Event of Default" under this Agreement:

     (a)  The failure of any Borrower to pay when due any Payment Amount or any
other amounts payable under this Agreement or any Note within five (5) days of
the date when due;

     (b)  A breach or failure in the observance or performance by any Borrower
of any other material provision of this Agreement or any other Loan Document
which is not remedied within thirty (30) days after receipt by any Borrower of
notice of such breach or failure;

     (c)  Any material representation, warranty or covenant made herein, or in
any certificate, document, financial or other statement delivered in connection
with this Agreement, or hereafter made by any Borrower proves to have been
incorrect in any material adverse respect when made or given;

     (d)  ATII or any Subsidiary, or any surety or guarantor of the Indebtedness
evidenced by this Agreement or the Note (i) files a petition or has a petition
filed against it under the bankruptcy code, or any proceeding for relief of
insolvent debtors; (ii) generally fails to pay its debts as such debts become
due; (iii) shall admit in writing its inability to pay its debts as they become
due; (iv) has a custodian, trustee or receiver appointed, voluntarily or
otherwise, for t or its assets; (v) benefits from, or is subject to, the entry
of an order for relief by any court of insolvency; (vi) makes an assignment for
the benefit of creditors; (vii) becomes insolvent (however otherwise evidenced);
(viii) liquidates, winds-up, dissolves or suspends business; or (ix) has
commenced against it any case, proceeding or other action seeking the issuance
of a warrant of attachment, execution, distraint or similar process against all
or any substantial part of its assets, which results in the entry of an order
for any such relief which shall not have been vacated, discharged, or stayed or
bonded pending appeal within sixty (60) days from the entry thereof;

     (e)  ATII or any Subsidiary shall (i) default in any payment of any other
instrument or agreement (other than with Lender) with an outstanding principal
amount in excess of $10,000 beyond the period of grace, if any, provided in the
applicable instrument or agreement, or (ii) default in the observance of any
other provision of such other instrument or agreement as to cause, or permit the
holder of such instrument or agreement to cause, the obligations thereunder to
become due prior to its stated maturity;

     (f)  One or more judgment or decrees shall be entered against ATII or any
Subsidiary involving in the aggregate a liability (not paid or fully covered by
insurance)
<PAGE>

of $10,000 or more, and any of such judgments or decrees shall not have been
vacated, discharged, or stayed or bonded pending appeal within sixty (60) days
after the entry thereof; or

     (g)  Any guaranty or any subordination agreement required or delivered in
connection with this Agreement is breached or becomes ineffective, or any
guarantor, or subordinating creditor disavows its obligation sunder the guaranty
or subordination agreement, as the case may be; or

     (h)  Any Borrower fails to perform any of its obligations under any other
agreement or lease with Lender (subject to any cure rights or notice periods
contained in such other agreement or lease); or

     (i)  At any time a Borrower other than ATII ceases to be a Subsidiary or
ATII; or

     (j)  If any Change in Control should occur without Lender's prior written
consent. A "Change in Control" of ATII shall be deemed to have occurred upon any
change in the direct or indirect control of, or the ability or right to control,
a majority of the voting shares of any class of securities or ownership rights
in any ATII or any other Borrower or in the right and/or the power to control
the election of the board of directors of ATII or any other Borrower; or

     (k)  The occurrence of a material adverse effect on, or material adverse
change in, (i) the business, operations or financial condition of ATII or any
other Borrower, (ii) the ability of ATII or any other Borrower to perform its
obligations under this Agreement, any Note, or the other Loan Documents, or
(iii) the Lender's ability to enforce the right sand remedies granted under this
Agreement or the other Loan Documents, in all cases whether attributable to a
single circumstance or event or an aggregation of circumstances or events.

     15.  RIGHTS AND REMEDIES ON DEFAULT: At Lender's option, upon the
occurrence of any such Event of Default under Section 14, and at any time
thereafter, at Lender's option, Lender's commitment to lend shall terminate
and/or all unmatured Indebtedness evidenced by the Note will immediately become
due and payable without presentation, demand, protest, or notice of any kind
(except as expressly provided for herein), all of which are expressly waived.
Lender may exercise, from time to time, any rights and remedies available to it
under this Agreement, any Note, the Uniform Commercial Code and other applicable
law. Each Borrower agrees that upon the occurrence that during the continuance
of an Event of Default, to the extent permitted by applicable law (i) any
amounts payable under this Agreement or under any Note shall thereafter bear
interest at a rate per annum equal to the Interest Rate plus three percent (3%),
or the maximum rate per annum allowed by law, whichever is less, compounded
monthly and payable on demand (both before and after judgment), until the
Indebtedness is paid in full or the Event of Default is cured, (ii) it will, at
Lenders request assemble the Collateral and make it available to Lender at
places which Lender shall reasonably select, and (iii) Lender, by itself or its
agent may, without notice to any person and without
<PAGE>

judicial process of any kind, enter into any premises or upon any land owned,
leased or otherwise under the real or apparent control of any Borrower, or any
agent of any Borrower, where the Collateral may be, or where Lender believes the
Collateral may be, and disassemble, render unusable, and/or repossess all or any
item of the Collateral, disconnecting and separating the Collateral from any
other property. Each Borrower expressly waives all further rights to possession
of the Collateral after the occurrence and during the continuance of an Event of
Default and all claims for injuries suffered through, or loss caused by, such
entering and/or repossession.

Lender shall have the right to sell, lease or otherwise dispose of the
Collateral (or contract to do so), whether in its then condition or after
further preparation or processing, either at public or private sale, in lots or
in bulk, for cash or for credit, with or without warranties or representations,
and upon such terms and conditions as Lender, in its sole discretion, may deem
advisable.  Lender shall have the right to purchase at any such sale.  Lender
will give the applicable Borrower reasonable notice of the time and place of any
public sale of the collateral or of the time after which any private sale or
other intended disposition of the Collateral is to be made.  Unless otherwise
provided by law, the requirement of reasonable notice shall be met if such
notice is delivered to the address of such Borrower set forth above at least ten
(10) days before the time of the sale or disposition.  Any proceeds of any
disposition by Lender of any of the Collateral may be first applied by Lender to
the payment of expenses, including reasonable attorneys' fees and legal
expenses, incurred in connection with the repossession, care, safekeeping, sale
or otherwise of any or all of the Collateral, or in any way relating to the
rights of Lender hereunder.  Any balance of such proceeds may be applied by
Lender toward the payment of the Indebtedness in such order as Lender, in its
sole discretion, shall determine.  The Borrowers shall be liable for, and shall
pay to Lender on demand, any deficiency which may remain after such sale, lease
or other disposition, and Lender agrees to remit to Borrowers any surplus
resulting therefrom.

If, for the purposes of obtaining judgment in respect of any claim under this
Agreement or any other Loan Document in any court, it is necessary to convert a
sum due hereunder or thereunder to the Lender in any currency (the "Original
Currency") into another currency (the "Other Currency"), the parties hereto
agree, to the fullest extent that they may effectively do so, that the rate of
exchange used shall be that at which in accordance with normal banking
procedures Lender could purchase the Original Currency with the Other Currency
on the Business Day preceding that on which final judgment is paid or satisfied.

The obligations of Borrowers in respect of any sum due in the Original Currency
to the Lender under this Agreement or any other Loan Document shall,
notwithstanding any judgment in any other Currency, be discharged only to the
extent that on the business day following receipt by Lender of any sum adjudged
to be so due in such Other Currency, Lender may in accordance with normal
banking procedures purchase the Original Currency with such Other Currency.  If
the amount of the Original Currency so purchased is less than the sum originally
due to the Lender in the Original Currency, Borrowers shall, as a separate
obligation and notwithstanding any such judgment, jointly and severally,
indemnify Lender against such loss, and if the amount of the Original
<PAGE>

Currency so purchased exceeds the sum originally due to Lender in the Original
Currency, Lender shall remit such excess to Borrowers.

     16.  GENERAL AUTHORITY: Upon the occurrence and during the continuance of
an Event of Default hereunder, Lender shall have the full power to exercise at
any time and from time to time all or any of the following powers with respect
to all or any of the Collateral:

     (a)  To demand, sue for collection, receive and give acquittance for any
and all monies due or to become due upon or by virtue thereof;

     (b)  To receive, take, endorse, assign and deliver any and all checks,
notes, drafts, documents and other property taken or received by Lender in
connection therewith;

     (c)  To settle, compromise, compound, prosecute or defend any action or
proceeding with respect thereof;

     (d)  To sell, transfer, assign or otherwise deal in or with the same or the
proceeds thereof, as fully and effectually as if Lender were the absolute owner
thereof; and

     (e)  In general, to do all things necessary to perform the terms of this
Agreement, including, without limitation, to take any action or proceedings
which Lender deems necessary or appropriate to protect and preserve the security
interest of Lender in the Collateral. In the case of failure of ATII or any
Borrower to comply with any provision of this Agreement, Lender shall have the
right, but shall not be obligated, to so comply in whole or in part, and all
moneys spent, and expenses and obligations incurred or assumed by Lender in
connection with such performance or compliance, shall be payable on demand
together with interest on such amounts equal to the Interest Rate plus three
percent (3%) from the date and amount is expended or advanced by the Lender
until paid. Such sums plus interest shall constitute indebtedness secured
hereby. Lender's effecting such compliance shall not be a waiver of any
Borrower's default. Lender shall be under no obligation or duty to exercise any
of the powers hereby conferred upon it.

     17.  EXPENSES: Each Borrower agrees (a) to pay or reimburse Lender for all
its reasonable costs, fees, charges and expenses incurred or arising in
connection with the negotiation, review, preparation and execution of this
Agreement, the Loan Documents, any commitment or proposal letter, or any
amendment, supplement, waiver, modification to, or restructuring of this
Agreement, the Indebtedness incurred hereunder, or the other Loan Documents,
including, without limitation, reasonable outside counsel legal fees and
disbursements, expenses, document charges and other charges and expenses of
Lender, (b) to pay or reimburse Lender for all its reasonable costs, fees,
charges and expenses incurred in connection with the administration of this
Agreement and the other Loan Documents or the enforcement, protection or
reservation of any rights under or in connection with this Agreement or by other
Loan Documents, including, without limitation, reasonable outside counsel legal
fees and disbursements, audit fees
<PAGE>

and charges, and all out-of-pocket expenses, (c) to pay, indemnify, and to hold
Lender harmless from, any and all recording and filing fees and taxes and any
and all liabilities with respect to, or resulting from any delay in paying,
stamp, excise and other taxes (excluding income and franchise taxes and taxes of
similar nature), if any, which may be payable or determined to be payable in
connection with the execution and delivery or recordation or filing of, or
consummation of any of the transactions contemplated by, or any amendment,
supplement or modification of, or any waiver or consent under or in respect of,
this Agreement and the other Loan Documents. All of the amounts described in
this Section are referred to collectively as the "Lender's Expenses," shall be
                                                  -----------------
payable upon Lender's demand, and shall accrue interest at the Interest Rate in
effect when such demand is made from five (5) days after the date of demand
until paid in full. All Lender's Expenses that are outstanding on any Borrowing
Date shall be paid before or with such Advance. If a Borrower has not paid to
Lender the amount of all Lender's Expenses billed to ATII before such Borrowing
Date, Lender shall be authorized to retain from any Advance on such Borrowing
Date the amount of such Lender's Expenses that remain unpaid. Each Borrower's
obligation to pay Lender's Expenses shall not be limited by any limitation on
the amount of the Commitment that may be designated as available for such
purpose, and any amounts so designated shall be used to pay Lender's Expenses
accrued at the time of any Advance before any of the legal fees or similar
expenses of the Borrowers.

     18.  NOTICES: Notices, demands and other communications required to be
given hereunder to be effective shall be permitted in writing by telex,
telecopy, or facsimile transmission and confirmed by a similar mailed writing,
by hand delivery, by first class, registered or certified mail, return receipt
requested, or an overnight courier service, addressed to Lender at 501 Corporate
Centre Drive, Suite 600, Franklin, TN 37067 (Attention: Director Operations &
Administration), with a copy to TFS Portfolio Management, 10 Riverview Drive,
Danbury, CT 06810, or to the applicable as the case may be, at the address set
forth above or at such other address as any party may hereinafter substitute by
written notice. Notice shall be effective four (4) days after the date it as
mailed or upon receipt, whichever is earlier.

     19.  INDEMNIFICATION: Each Borrower shall indemnify Lender against and hold
Lender harmless from any and all claims, actions, suits, damages, allegations,
liabilities, and liens and all costs and expenses, including, without
limitation, reasonable attorneys' fees incurred by Lender, arising out of or in
any way related to a Borrower's ownership or use of the Collateral, or in
connection with the transactions contemplated by this Agreement, including
without limitation, the granting and perfection of the security interest and
liens described herein, except to the extent attributable solely to Lender's
gross negligence or willful misconduct.

     20.  FCC AND PUC APPROVALS; NOTIFICATION: The exercise of any rights
hereunder by the Lender that may require FCC or PUC approval shall be subject to
obtaining such approval. Pending obtaining any such FCC or PUC approval, each
Borrower will refrain from taking or permitting any action be taken which is
contrary to the interest of the Lender. In accordance with the requirements of
46 C.F.R. Section 22.917 (1984), or any successor provision, the Lender agrees
to notify the applicable
<PAGE>

Borrower and the FCC (if required) in writing at least ten (10) days prior to
the repossession, in accordance with this Agreement, of all or any part of the
collateral which is subject to the regulation.

     21.  ASSIGNMENT: Lender may, in whole or in part without notice to, or the
consent of any Borrower, sell, assign, grant a security interest in or pledge
its interest in the Collateral and/or a Note and any amounts due or to become
due hereunder to any third party ("Assignee"). Upon receiving written notice
                                   --------
from Lender, a Borrower shall, if so directed, pay the amounts due hereunder,
directly to Assignee. Any Assignee shall be entitled to rely on the agreements,
representations warranties, and covenants of ATII and each Borrower contained
herein, as applicable, and shall be considered a third-party beneficiary
thereof. Each Borrower shall also execute and deliver to Lender, or any
Assignee, any additional documentation as Lender or Assignee may reasonably
request. Without Lender's prior written consent, no Borrower shall assign or
transfer its obligations hereunder. Any attempted transfer by any Borrower shall
be void ab initio.

     22.  MISCELLANEOUS:

     (a)  No failure or delay by the Lender to exercise any right, power or
privilege hereunder shall operate as a waiver of any such right, power or
privilege, nor shall any single or partial exercise of any right, power or
privilege preclude any other or future exercise thereof. The Lender may waiver
any default before or after the same has been declared and restore this
Agreement to full force without impairing any rights hereunder, such right of
waiver being a continuing one. The waiver of any provision hereunder will not be
effective unless in writing signed by the Lender.

     (b)  If any provision of this Agreement or a Note shall be prohibited or
unenforceable, such provision shall be ineffective to the extent of such
prohibition or unenforceability without invalidating the remaining provisions.

     (c)  To the extent that the Indebtedness is now or hereafter secured by
property other than the Collateral, or by the guaranty, endorsement or property
of any other person, corporation or entity, then Lender shall have the right, in
its sole discretion, to determine which rights, security, liens, security
interest or remedies it shall, at any time, pursue, relinquish, subordinate,
modify, or take any other action with respect thereto without, in any way,
modifying or affecting any of them or any of its rights hereunder.

     (d)  Lender's duty of care (as imposed by law) with respect to the
Collateral in its possession shall be deemed fulfilled if Lender exercises
reasonable care in physically safekeeping such Collateral, or in the case of
Collateral in the custody or possession of a bailee or other third person,
exercises reasonable care in the selection of the bailee or other third person,
and Lender need not otherwise preserve, protect, insure, or care for any
Collateral.

     (e)  No right or remedy is exclusive of any other provided under this
Agreement or permitted by law or equity. All such rights and remedies shall be
cumulative and may be exercised singularly or concurrently at Lender's option.
The
<PAGE>

exercise or enforcement of any one such right or remedy shall neither be a
condition to, nor bar the exercise or enforcement of any other.

     (f)  All representations and warranties made herein or in any document,
certificate or statement delivered pursuant thereto, or in connection therewith,
shall survive the execution and delivery of this Agreement and the Note.

     (g)  ATII and each Borrower waive presentment, demand, protest and (except
to the extent expressly provided for herein) notice to the extent permitted by
applicable law.

     (h)  Time is of the essence with regard to each and every provision of this
Agreement and the Note.

     (i)  This Agreement may be executed in more than one counterpart, all of
which taken together, shall constitute one agreement.

     (j)  Except as otherwise provided in this Agreement, all computations and
determinations as to accounting or financial matters and all financial
statements to be delivered pursuant to this Agreement shall be made and prepared
in accordance with GAAP (including principles of consolidation where
appropriate), consistently applied, and all accounting or financial terms shall
have the meanings ascribed to such terms by GAAP. At such time that ATII has any
Subsidiaries, all accounting and financial terms herein shall be deemed to
include references to consolidated and consolidating principles, and covenants,
representations and agreements with respect to ATII and its properties and
activities shall be deemed to refer to ATII and its consolidated Subsidiaries
collectively.

     23.  SUCCESSORS AND ASSIGNS:     This Agreement shall be binding on the
          ----------------------
parties and inure to the benefit of Lender and each Borrower and their
successors and permitted assigns.

     24.  GOVERNING LAW, JURISDICTION AND VENUE:
          -------------------------------------

     (a)  This Agreement and the Note shall be construed in accordance with and
governed by the laws of the State of Tennessee, except to the extent the
internal laws of another jurisdiction are required to be applied in connection
with the exercise of rights pertaining to Collateral in that jurisdiction.

     (b)  EACH BORROWER HEREBY IRREVOCABLY CONSENTS TO THE NONEXCLUSIVE
JURISDICTION OF THE COURTS LOCATED IN WILLIAMSON COUNTY, TENNESSEE AND DAVIDSON
COUNTY, TENNESSEE, INCLUDING WITHOUT LIMITATION FEDERAL COURTS SITTING IN THE
MIDDLE DISTRICT OF TENNESSEE, THE CHANCERY COURT FOR WILLIAMSON COUNTY,
TENNESSEE, AND THE CHANCERY COURT FOR DAVIDSON COUNTY, TENNESSEE, FOR ANY SUIT
BROUGHT OR ACTION COMMENCED IN CONNECTION WITH THIS AGREEMENT, THE NOTE, THE
OTHER LOAN DOCUMENTS, OR THE OBLIGATION, AND AGREES NOT TO CONTEST VENUE OR
JURISDICTION IN ANY SUCH COURTS. The choice of forum set forth herein
<PAGE>

shall not be deemed to preclude the enforcement of any judgment obtained in such
forum or the taking of any action under this Agreement to enforce the same in
any appropriate jurisdiction.

     25.  WAIVERS AND LIMITATIONS OF LIABILITY: (a) EACH BORROWER AND LENDER
HEREBY KNOWINGLY DEMAND A JURY TRIAL IN ANY ACTION OR PROCEEDING INVOLVING THIS
AGREEMENT, THE NOTE, ANY OTHER LOAN DOCUMENT, THE OBLIGATIONS, OR ANY
RELATIONSHIP BETWEEN LENDER AND BORROWER. EACH BORROWER WARRANTS AND REPRESENTS
THAT IT HAS REVIEWED THE FOREGOING WAIVERS WITH ITS LEGAL COUNSEL AND HAS
KNOWINGLY AND VOLUNTARILY WAIVED ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION
WITH LEGAL COUNSEL. IN THE EVENT OF LITIGATION, THIS AGREEMENT MAY BE FILED AS A
WRITTEN CONSENT TO A TRIAL BY THE COURT.

     (b)  LENDER SHALL HAVE NO LIABILITY UNDER OR IN CONNECTION WITH THIS
AGREEMENT, THE NOTE OR ANY OF THE OTHER LOAN DOCUMENTS FOR SPECIAL, EXEMPLARY,
PUNITIVE, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY SORT IN ANY SUIT
BROUGHT OR ACTION COMMENCED IN CONNECTION WITH THIS AGREEMENT, THE NOTE, THE
OTHER LOAN DOCUMENTS, OR THE OBLIGATIONS AND, EXCEPT TO THE EXTENT PROHIBITED BY
LAW, EACH PARTY WAIVES ANY RIGHT IT MAY HAVE TO CLAIM OR RECOVER IN ANY SUCH
ACTION ANY SPECIAL, EXEMPLARY, PUNITIVE, INCIDENTAL, INDIRECT OR CONSEQUENTIAL
DAMAGES OF ANY SORT OTHER THAN ACTUAL DAMAGES.

     (c)  To the fullest extent permitted by law, except as otherwise expressly
provided herein, each Borrower hereby waives (i) presentment, demand and protest
and notice of presentment, protest, default, non-payment, maturity, release,
compromise, settlement, extension or renewal of any or all commercial paper,
accounts, contract rights, documents, instruments, chattel paper and guaranties
at any time held by Lender on which any Borrower may in any way be liable and
hereby ratifies and confirms whatever Lender may do in this regard; (ii) notice
prior to taking possession or control of the Collateral or any bond or security
which might be required by any court prior to allowing Lender to exercise any of
Lender's remedies, including the issuance of an immediate writ of possession,
except as expressly required in any of the Loan Documents; (iii) any marshalling
of assets, or any right to compel Lender to resort first to any Collateral or
other persons before pursuing any Borrower for payment of the Indebtedness and
any defenses based on suretyship or impairment of Collateral; (iv) the benefit
of all valuation, appraisement and exemption laws; (v) any right to require
Lender to terminate its security interest in the Collateral or in any other
property of any Borrower until termination of this Agreement and the execution
by each Borrower and by any person whose loans to a Borrower are used in whole
or in part to satisfy the Obligations, of an agreement indemnifying Lender from
any loss or damage Lender may incur as the result of dishonored or unsatisfied
items of any account debtor applied to the Indebtedness; and (vi) notice of
acceptance hereof. Each Borrower acknowledges that the foregoing
<PAGE>

waivers are a material inducement to Lender's entering into this Agreement and
that Lender is relying upon the foregoing waivers in its future dealings with
each Borrower.

     26.  ENTIRE AGREEMENT. This Agreement constitutes the entire agreement
          ----------------
between Lender and each Borrower with respect to the subject matter hereof and
supersedes all previous negotiations, proposals, commitments, writings, and
understandings of any nature whatsoever.

     IN WITNESS WHEREOF, the parties have executed this Loan and Security
Agreement by their duly authorized representatives:
<PAGE>

                         BORROWERS:
                         ---------


                         AMERICAN TELESOURCE INTERNATIONAL, INC. (Delaware)


                         BY:              /s/ Arthur L. Smith
                            ------------------------------------------------
                                 Arthur L. Smith, Chief Executive Officer



                         AMERICAN TELESOURCE INTERNATIONAL, INC. (Texas)


                         BY:              /s/ Arthur L. Smith
                            ------------------------------------------------
                                 Arthur L. Smith, President


                         TELESPAN, INC.


                         BY:              /s/ Charles R. Poole
                            ------------------------------------------------
                                 Arthur L. Smith, President


                         GLOBALSCAPE, INC.


                         BY:              /s/ Arthur L. Smith
                            ------------------------------------------------
                                 Arthur L. Smith, Chairman


                         LENDER:
                         ------

                         NTFC CAPITAL CORPORATION


                         BY:_________________________________________________
                         TITLE:______________________________________________
<PAGE>

                                   EXHIBIT A
                                   ---------

                 FORM OF ANNEX TO LOAN AND SECURITY AGREEMENT
                 --------------------------------------------

     By executing this Annex to Loan and Security Agreement attached to and
forming a part of the Loan and Security Agreement dated as of _________, 1999,
(the "Loan Agreement"), between and among AMERICAN TELESOURCE INTERNATIONAL,
INC., a ________ corporation ("ATII"), NTFC Capital Corporation (the "Lender"),
Domestic Subsidiaries of ATII which are signatories to the Loan Agreement, and
such additional Domestic Subsidiaries of ATII which may become a party to the
Loan Agreement pursuant to Section 1(b) thereof, ________ represents and
warrants that Domestic Subsidiary of ATII, joins as a party to the Loan
Agreement, assumes the obligations of a Borrower under the Loan Agreement, and
confirms it is bound by the terms and conditions of the Loan Agreement,
including but not limited to the grant to Lender of a security interest in all
its right, title, interest in and to the Collateral as provided in the Loan
Agreement. _____ acknowledges and agrees that one or more other Subsidiary ATII
may become additional Borrowers under the Loan Agreement without the consent of
any other Borrower by execution of a form of the Annex to the Agreement by ATII,
the Subsidiary and the Lender. ________ acknowledges and agrees that (i) other
Subsidiaries of ATII may become additional Borrowers under the Loan Agreement
without the consent of any other Borrower by execution of a form of the Annex to
the Loan Agreement by ATII Subsidiary and Lender; (ii) the Lender is willing to
extend certain credit to the Borrowers, subject to the terms and conditions set
forth in the Agreement, including the condition that all Borrowers will be
jointly and severally liable for all amounts owed by any Borrower under the Loan
Agreement, Lender(iii) without this joint and several liability for all
Indebtedness owed by any Borrower to Lender under the Loan Agreement, Lender
would _____ willing to extend credit to any Borrower, and (iv) ____________ the
existing Borrowers and other Subsidiaries of ATII which may be additional
Borrowers under the Loan Agreement are related entities, and ________ expects to
increase its business, and to benefit directly or indirectly, through the use of
the equipment to be acquired by it and the other Borrowers with the proceeds of
the loans to be made pursuant to the Agreement.

____________ authorizes the Lender to attach this Annex to the Loan and Security
Agreement, which shall be deemed a part of, and incorporated by reference in,
the Loan Agreement.  This Annex to the Loan and Security  shall be construed in
accordance with and governed by the laws of the State of Tennessee, except to
the extent the internal laws of another jurisdiction are required to be applied
in connection with the exercise of rights pertaining to Collateral in that
jurisdiction.  Capitalized terms used in this Annex to the Loan Agreement
without definition shall have the meanings set forth in the Loan Agreement to
which this Annex is attached and form a part.

     This Annex may be executed in any number of counterparts (by facsimile
transmission or otherwise) and by the different parties hereto as separate
counterparts, each of which, when so executed, shall be deemed an original, but
all such counterparts shall constitute but one and the same document.
<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Annex to Loan and
Security Agreement by their duly authorized representatives:

                         ATII:
                         ----

                         AMERICAN TELESOURCE
                         INTERNATIONAL, INC.


                         BY:_________________________________________________
                         TITLE:______________________________________________


                         BORROWER:
                         --------


                         BY:_________________________________________________
                         TITLE:______________________________________________


                         LENDER:
                         ------


                         BY:_________________________________________________
                         TITLE:______________________________________________
<PAGE>

                                   EXHIBIT C
                                   ---------

                    AMERICAN TELESOURCE INTERNATIONAL, INC.
                    ---------------------------------------

<TABLE>
<CAPTION>
             ---------------------------------------------------------------------------------------------------
                                                       COVENANTS (FYE 7/31)
             ---------------------------------------------------------------------------------------------------
                         1                   2                  3                  4                  5
----------------------------------------------------------------------------------------------------------------
                    Senior Debt/       Adjusted              Minimum            Minimum            Minimum
                                       EBITDA/
Period:
                        Book         Debt Service/             Revenue         Gross Margin          EBITDA
                   Capitalization        Capx
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
<S>                <C>               <C>                     <C>              <C>                  <C>
FY2000
Quarter 1            50.00%            1.1X                   $ 8,699,800          2,817,800           ($92,900)
Quarter 2            50.00%            1.1X                   $11,177,200          4,172,200         $  720,900
Quarter 3            50.00%            1.1X                   $15,981,500          5,911,900         $2,295,800
Quarter 4            50.00%            1.1X                   $19,559,200          7,434,600         $3,705,200
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
FY2001
Quarter 1            50.00%            1.2X                   $27,855,000         10,592,000         $5,089,500
Quarter 2            50.00%            1.2X                   $27,855,000         10,592,000         $5,089,500
Quarter 3            50.00%            1.2X                   $27,855,000         10,592,000         $5,089,500
Quarter 4            50.00%            1.2X                   $27,855,000         10,592,000         $5,089,500
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
FY2002
Quarter 1            50.00%            1.4X                   N/A                 N/A                $6,491,900
Quarter 2            50.00%            1.4X                   N/A                 N/A                $6,491,900
Quarter 3            50.00%            1.4X                   N/A                 N/A                $6,491,900
Quarter 4            50.00%            1.4X                   N/A                 N/A                $6,491,900
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
FY2003
Quarter 1            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 2            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 3            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 4            50.00%            2.0X                   N/A                 N/A                $7,840,500
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
FY2004
Quarter 1            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 2            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 3            50.00%            2.0X                   N/A                 N/A                $7,840,500
Quarter 4            50.00%            2.0X                   N/A                 N/A                $7,840,500
----------------------------------------------------------------------------------------------------------------
</TABLE>