Document:

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                                                                     EXHIBIT 4.9

                             SUPPLEMENTAL INDENTURE

     SUPPLEMENTAL INDENTURE, effective as of      , 2003, by and between
ALESTRA, S. de R.L. de C.V., a corporation duly organized and existing under the
laws of the United Mexican States (the "Company"), having its principal business
office at Avenida Lazaro Cardenas No. 2321, Piso 9, Col. Residencial San
Agustin, San Pedro Garza Garcia, N.L. 66260, Mexico, and U.S. BANK TRUST
NATIONAL ASSOCIATION, a national banking corporation, as Trustee (the
"Trustee"), having its principal corporate trust office at 100 Wall Street, 16th
Floor, New York, New York 10005.

                              W I T N E S S E T H:

     WHEREAS, the Company and the Trustee previously entered into an Indenture
(the "Indenture"), dated as of May 17, 1999, providing for the issuance of an
aggregate principal amount of $270,000,000 of 12 1/8% Notes due May 15, 2006
(the "Notes");

     WHEREAS, Section 9.02 of the Indenture provides that modifications and
amendments to the Indenture may be made and one or more indentures supplemental
to the Indenture entered into by the Company and the Trustee with the consent of
the holders (the "Holders") of not less than a majority in aggregate principal
amount of the Outstanding Notes (as define in the Indenture), except for certain
specific events which require the consent of all Holders of the Notes;

     WHEREAS, the Company undertook an exchange offer, a cash tender offer and a
consent solicitation (together, the "Offers") pursuant to a prospectus dated
          , 2003 (as amended from time to time, together with any supplement
thereto, the "Prospectus"), offering new securities of the Company or a cash
payment in exchange for the Holder's Notes and requesting, among other things,
that the Holders give their written consent to implement the amendments to the
Indenture set forth in this Supplemental Indenture (the "Amendments");

     WHEREAS, the Company has received through the Offers the valid consents of
the Holders of at least a majority in aggregate principal amount outstanding of
the Notes consenting to the substance of the Amendments set forth in this
Supplemental Indenture;

     WHEREAS, all conditions and requirements necessary to make this
Supplemental Indenture a valid, binding, and legal instrument in accordance with
the terms of the Indenture have been performed and fulfilled and the execution
and delivery hereof have been in all respects duly authorized;

     WHEREAS, the Company has requested that the Trustee execute and deliver
this Supplemental Indenture; and

     WHEREAS, pursuant to Section 9.02 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture;

     NOW, THEREFORE, for and in consideration of the promises and the mutual
covenants contained herein and in the Indenture and for other good and valuable
consideration, the receipt and sufficiency of which are herein acknowledged, the
Company and the Trustee hereby agree for the equal and ratable benefit of all
holders of the Notes as follows:

                                   ARTICLE 1.
                                   Amendments

     Section 1.01 Indenture Amendments. The Indenture is hereby amended as
follows:

            (a)   The table of contents of the Indenture is amended by (i)
     replacing the heading "Corporate Existence" in Section 10.04 with the
     heading "[intentionally omitted]"; (ii) replacing the heading "Payment

                                        1

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     of Taxes and Other Claims" in Section 10.05 with the heading
     "[intentionally omitted]"; (iii) replacing the heading "Maintenance of
     Properties" in Section 10.06 with the heading "[intentionally omitted]";
     (iv) replacing the heading "Insurance" in Section 10.07 with the heading
     "[intentionally omitted]"; (v) replacing the heading "Books and Records" in
     Section 10.08 with the heading "[intentionally omitted]"; (vi) replacing
     the heading "Change of Control" in Section 10.10 with the heading
     "[intentionally omitted]"; (vii) replacing the heading "Limitation on
     Indebtedness" in Section 10.11 with the heading "[intentionally omitted]";
     (viii) replacing the heading "Statement by Officers as to Default" in
     Section 10.12 with the heading "[intentionally omitted]"; (ix) replacing
     the heading "Limitation on Restricted Payments" in Section 10.13 with the
     heading "[intentionally omitted]"; (x) replacing the heading "Limitation on
     Affiliate Transactions" in Section 10.14 with the heading "[intentionally
     omitted]"; (xi) replacing the heading "Limitation on Sales of Assets and
     Subsidiary Stock" in Section 10.15 with the heading "[intentionally
     omitted]"; (xii) replacing the heading "Limitation on Liens" in Section
     10.16 with the heading "[intentionally omitted]"; (xiii) replacing the
     heading "Limitation on Lines of Business" in Section 10.17 with the heading
     "[intentionally omitted]"; (xiv) replacing the heading "Limitation of
     Guarantees by Restricted Subsidiaries" in Section 10.18 with the heading
     "[intentionally omitted]"; (xv) replacing the heading "Limitation on the
     Sales or Issuance of Capital Stock of Restricted Subsidiaries" in Section
     10.19 with the heading "[intentionally omitted]";and (xvi) replacing the
     heading "Limitation on Restrictions on Distributions from Restricted
     Subsidiaries" in Section 10.20 with the heading "[intentionally omitted]".

        (b) Section 1.01 of the Indenture is amended to delete the following
     definitions:

        "Additional Assets"
        "Adjusted Consolidated Net Tangible Assets"
        "Asset Disposition"
        "Average Life"
        "Consolidated Interest Expense"
        "Consolidated Leverage Ratio"
        "Consolidated Net Income"
        "Cumulative Interest Expense"
        "EBITDA"
        "Fair Market Value"
        "Incur"
        "Investment"
        "Net Available Cash"
        "Net Cash Proceeds"
        "Permitted Investment"
        "Permitted Liens"
        "Purchase Money Note"
        "Qualified Receivables Transaction"
        "Receivables Subsidiary"
        "Refinance"
        "Refinancing Indebtedness"
        "Restricted Payment"
        "Restricted Subsidiary"
        "Standard Securitization Undertakings"
        "Strategic Subordinated Indebtedness"
        "Subordinated Obligation"
        "Temporary Cash Investments"
        "Unrestricted Subsidiary"
        "Wholly-Owned Subsidiary"

        (c) The definition of "Indebtedness" set forth in Section 1.01 of the
     Indenture is amended by deleting the last sentence of such definition.

        (d) Section 1.02 of the Indenture is amended to delete the following
     terms and the corresponding section numbers:

                                        2

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     "Affiliate Transaction"
     "Asset Sale Offer"
     "Change of Control Date"
     "Change of Control Offer"
     "Offer Excess Proceeds"

     (e) Section 5.01 of the Indenture is amended by deleting the text of
subsections (iii), (iv), (v), (vi), (vii) in their entirety and inserting in
lieu thereof "[intentionally omitted]".

     (f) Section 5.02 of the Indenture is amended by deleting the text of
Section 5.02 in its entirety and inserting in lieu thereof:

     "If an Event of Default (other than an Event of Default specified in clause
(viii), (ix) or (x) of Section 5.01 hereof with respect to the Company) occurs
and is continuing, then the holders of at least 51% in principal amount of the
Outstanding Notes may, by written notice, and the Trustee upon the request of
the holders of not less than 51% in principal amount of the outstanding Notes
shall, declare the Default Amount of all Outstanding Notes to be immediately due
and payable by notice to the Company and upon any such declaration and notice
such amounts shall become immediately due and payable. If an Event of Default
specified in clause (viii), (ix) or (x) above with respect to the Company occurs
and is continuing, then the Default Amount of all Outstanding Notes shall ipso
facto become and be immediately due and payable without any declaration or other
act on the part of the Trustee or any Holder.

     After a declaration of acceleration or any ipso facto acceleration as
related to clause (viii), (ix) or (x) of Section 5.01, the holders of a majority
in aggregate principal amount of Outstanding Notes may, by notice to the
Trustee, rescind such declaration of acceleration and its consequences if all
existing Events of Default, other than nonpayment of the principal of, and
accrued and unpaid interest on, the Notes that has become due solely as a result
of such acceleration, have been cured or waived and if the rescission of
acceleration would not conflict with any judgment or decree."

     (g) Article 8 of the Indenture is amended by deleting the text of Section
8.01 in its entirety and inserting in lieu thereof:

     "Section 8.01. Company May Consolidate, etc., Only on Certain Terms.

     The Company will not consolidate or merge with or into or convey, lease or
transfer all or substantially all of its assets to, any Person in a single
transaction or through a series of transactions, unless: the Successor Company
(if not the Company) shall expressly assume all of the obligations of the
Company under the Notes and this Indenture, and shall execute a supplemental
indenture to effect such assumption which supplemental indenture shall be
delivered to the Trustee and shall be in form and substance reasonably
satisfactory to the Trustee;"

     (h) Article 8 of the Indenture is amended by adding the following text as a
new Section 8.03:

     "Section 8.03. Consent and Approval of Merger or Consolidation.

     For the purposes of Mexican Law, the Holders hereby expressly consent to
and approve of any consolidation with, or merger with or into, or conveyance,
transfer or lease by, Alestra of all of its assets to any Person."

     (i) Article 10 of the Indenture is amended by deleting the text of Sections
10.04, 10.05, 10.06, 10.07, 10.08, 10.10, 10.11, 10.12, 10.13, 10.14, 10.15,
10.16, 10.17, 10.18, 10.19 and 10.20 in their entirety and inserting in lieu
thereof "[intentionally omitted]".

                                        3

<PAGE>

     Section 1.02 Mutatis Mutandi Effect. The Indenture, as supplemented, is
hereby amended mutatis mutandi to reflect the addition, deletion or amendment of
each of the defined terms incorporated in the Indenture pursuant to Section 1.01
above.

                                   ARTICLE 2.
                                  Miscellaneous

     Section 2.01 Effect of the Supplemental Indenture. This Supplemental
Indenture supplements the Indenture and shall be a part, and subject to all the
terms, thereof. Except as expressly supplemented hereby, the Indenture and the
Notes issued thereunder shall continue in full force and effect.

     Section 2.02 Governing Law. This Supplemental Indenture shall be governed
by, and construed in accordance with, the laws of the State of New York, but
without giving effect to applicable principles of conflicts of law to the extent
that the application of the laws of another jurisdiction would be required
thereby.

     Section 2.03 Trustee Makes No Representation. The Trustee makes no
representation as to the validity or sufficiency of this Supplemental Indenture.

     Section 2.04 Effect of Headings. The section headings herein are for
convenience only and shall not affect the construction thereof.

     Section 2.05 Counterparts. The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them shall represent the same agreement.

                     [SIGNATURE PAGE TO IMMEDIATELY FOLLOW]

                                        4

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first stated above.

                                           ALESTRA, S. DE R.L. DE C.V.

                                      By:  _____________________________________
                                           Name:
                                           Title:

                                           U.S. BANK TRUST NATIONAL ASSOCIATION,
                                           as Trustee,

                                      By:  _____________________________________
                                           Name:
                                           Title:

                                        5<PAGE>

                                                                    EXHIBIT 4.10

                             SUPPLEMENTAL INDENTURE

     SUPPLEMENTAL INDENTURE, effective as of      , 2003, by and between
ALESTRA, S. de R.L. de C.V., a corporation duly organized and existing under the
laws of the United Mexican States (the "Company"), having its principal business
office at Avenida Lazaro Cardenas No. 2321, Piso 9, Col. Residencial San
Agustin, San Pedro Garza Garcia, N.L. 66260, Mexico, and U.S. BANK TRUST
NATIONAL ASSOCIATION, a national banking corporation, as Trustee (the
"Trustee"), having its principal corporate trust office at 100 Wall Street, 16th
Floor, New York, New York 10005.

                              W I T N E S S E T H:

     WHEREAS, the Company and the Trustee previously entered into an Indenture
(the "Indenture"), dated as of May 17, 1999, providing for the issuance of an
aggregate principal amount of $300,000,000 of 12 5/8% Notes due May 15, 2009
(the "Notes");

     WHEREAS, Section 9.02 of the Indenture provides that modifications and
amendments to the Indenture may be made and one or more indentures supplemental
to the Indenture entered into by the Company and the Trustee with the consent of
the holders (the "Holders") of not less than a majority in aggregate principal
amount of the Outstanding Notes (as define in the Indenture), except for certain
specific events which require the consent of all Holders of the Notes;

     WHEREAS, the Company undertook an exchange offer, a cash tender offer and a
consent solicitation (together, the "Offers") pursuant to a prospectus dated
 , 2003 (as amended from time to time, together with any supplement thereto, the
"Prospectus"), offering new securities of the Company or a cash payment in
exchange for the Holder's Notes and requesting, among other things, that the
Holders give their written consent to implement the amendments to the Indenture
set forth in this Supplemental Indenture (the "Amendments");

     WHEREAS, the Company has received through the Offers the valid consents of
the Holders of at least a majority in aggregate principal amount outstanding of
the Notes consenting to the substance of the Amendments set forth in this
Supplemental Indenture;

     WHEREAS, all conditions and requirements necessary to make this
Supplemental Indenture a valid, binding, and legal instrument in accordance with
the terms of the Indenture have been performed and fulfilled and the execution
and delivery hereof have been in all respects duly authorized;

     WHEREAS, the Company has requested that the Trustee execute and deliver
this Supplemental Indenture; and

     WHEREAS, pursuant to Section 9.02 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture;

     NOW, THEREFORE, for and in consideration of the promises and the mutual
covenants contained herein and in the Indenture and for other good and valuable
consideration, the receipt and sufficiency of which are herein acknowledged, the
Company and the Trustee hereby agree for the equal and ratable benefit of all
holders of the Notes as follows:

                                   ARTICLE 1.
                                   Amendments

     Section 1.01 Indenture Amendments. The Indenture is hereby amended as
follows:

            (a) The table of contents of the Indenture is amended by (i)
     replacing the heading "Corporate Existence" in Section 10.04 with the
     heading "[intentionally omitted]"; (ii) replacing the heading "Payment

                                        1

<PAGE>

     of Taxes and Other Claims" in Section 10.05 with the heading
     "[intentionally omitted]"; (iii) replacing the heading "Maintenance of
     Properties" in Section 10.06 with the heading "[intentionally omitted]";
     (iv) replacing the heading "Insurance" in Section 10.07 with the heading
     "[intentionally omitted]"; (v) replacing the heading "Books and Records" in
     Section 10.08 with the heading "[intentionally omitted]"; (vi) replacing
     the heading "Change of Control" in Section 10.10 with the heading
     "[intentionally omitted]"; (vii) replacing the heading "Limitation on
     Indebtedness" in Section 10.11 with the heading "[intentionally omitted]";
     (viii) replacing the heading "Statement by Officers as to Default" in
     Section 10.12 with the heading "[intentionally omitted]"; (ix) replacing
     the heading "Limitation on Restricted Payments" in Section 10.13 with the
     heading "[intentionally omitted]"; (x) replacing the heading "Limitation on
     Affiliate Transactions" in Section 10.14 with the heading "[intentionally
     omitted]"; (xi) replacing the heading "Limitation on Sales of Assets and
     Subsidiary Stock" in Section 10.15 with the heading "[intentionally
     omitted]"; (xii) replacing the heading "Limitation on Liens" in Section
     10.16 with the heading "[intentionally omitted]"; (xiii) replacing the
     heading "Limitation on Lines of Business" in Section 10.17 with the heading
     "[intentionally omitted]"; (xiv) replacing the heading "Limitation of
     Guarantees by Restricted Subsidiaries" in Section 10.18 with the heading
     "[intentionally omitted]"; (xv) replacing the heading "Limitation on the
     Sales or Issuance of Capital Stock of Restricted Subsidiaries" in Section
     10.19 with the heading "[intentionally omitted]";and (xvi) replacing the
     heading "Limitation on Restrictions on Distributions from Restricted
     Subsidiaries" in Section 10.20 with the heading "[intentionally omitted]".

        (b) Section 1.01 of the Indenture is amended to delete the following
            definitions:

        "Additional Assets"
        "Adjusted Consolidated Net Tangible Assets"
        "Asset Disposition"
        "Average Life"
        "Consolidated Interest Expense"
        "Consolidated Leverage Ratio"
        "Consolidated Net Income"
        "Cumulative Interest Expense"
        "EBITDA"
        "Fair Market Value"
        "Incur"
        "Investment"
        "Net Available Cash"
        "Net Cash Proceeds"
        "Permitted Investment"
        "Permitted Liens"
        "Purchase Money Note"
        "Qualified Receivables Transaction"
        "Receivables Subsidiary"
        "Refinance"
        "Refinancing Indebtedness"
        "Restricted Payment"
        "Restricted Subsidiary"
        "Standard Securitization Undertakings"
        "Strategic Subordinated Indebtedness"
        "Subordinated Obligation"
        "Temporary Cash Investments"
        "Unrestricted Subsidiary"
        "Wholly-Owned Subsidiary"

        (c) The definition of "Indebtedness" set forth in Section 1.01 of the
     Indenture is amended by deleting the last sentence of such definition.

        (d) Section 1.02 of the Indenture is amended to delete the following
     terms and the corresponding section numbers:

                                        2

<PAGE>

     "Affiliate Transaction"
     "Asset Sale Offer"
     "Change of Control Date"
     "Change of Control Offer"
     "Offer Excess Proceeds"

     (e) Section 5.01 of the Indenture is amended by deleting the text of
subsections (iii), (iv), (v), (vi), (vii) in their entirety and inserting in
lieu thereof "[intentionally omitted]".

     (f) Section 5.02 of the Indenture is amended by deleting the text of
Section 5.02 in its entirety and inserting in lieu thereof:

     "If an Event of Default (other than an Event of Default specified in clause
(viii), (ix) or (x) of Section 5.01 hereof with respect to the Company) occurs
and is continuing, then the holders of at least 51% in principal amount of the
Outstanding Notes may, by written notice, and the Trustee upon the request of
the holders of not less than 51% in principal amount of the outstanding Notes
shall, declare the Default Amount of all Outstanding Notes to be immediately due
and payable by notice to the Company and upon any such declaration and notice
such amounts shall become immediately due and payable. If an Event of Default
specified in clause (viii), (ix) or (x) above with respect to the Company occurs
and is continuing, then the Default Amount of all Outstanding Notes shall ipso
facto become and be immediately due and payable without any declaration or other
act on the part of the Trustee or any Holder.

     After a declaration of acceleration or any ipso facto acceleration as
related to clause (viii), (ix) or (x) of Section 5.01, the holders of a majority
in aggregate principal amount of Outstanding Notes may, by notice to the
Trustee, rescind such declaration of acceleration and its consequences if all
existing Events of Default, other than nonpayment of the principal of, and
accrued and unpaid interest on, the Notes that has become due solely as a result
of such acceleration, have been cured or waived and if the rescission of
acceleration would not conflict with any judgment or decree."

     (g) Article 8 of the Indenture is amended by deleting the text of Section
8.01 in its entirety and inserting in lieu thereof:

     "Section 8.01. Company May Consolidate, etc., Only on Certain Terms.

     The Company will not consolidate or merge with or into or convey, lease or
transfer all or substantially all of its assets to, any Person in a single
transaction or through a series of transactions, unless: the Successor Company
(if not the Company) shall expressly assume all of the obligations of the
Company under the Notes and this Indenture, and shall execute a supplemental
indenture to effect such assumption which supplemental indenture shall be
delivered to the Trustee and shall be in form and substance reasonably
satisfactory to the Trustee;"

     (h) Article 8 of the Indenture is amended by adding the following text as a
new Section 8.03:

     "Section 8.03. Consent and Approval of Merger or Consolidation.

     For the purposes of Mexican Law, the Holders hereby expressly consent to
and approve of any consolidation with, or merger with or into, or conveyance,
transfer or lease by, Alestra of all of its assets to any Person."

     (i) Article 10 of the Indenture is amended by deleting the text of Sections
10.04, 10.05, 10.06, 10.07, 10.08, 10.10, 10.11, 10.12, 10.13, 10.14, 10.15,
10.16, 10.17, 10.18, 10.19 and 10.20 in their entirety and inserting in lieu
thereof "[intentionally omitted]".

                                        3

<PAGE>

     Section 1.02 Mutatis Mutandi Effect. The Indenture, as supplemented, is
hereby amended mutatis mutandi to reflect the addition, deletion or amendment of
each of the defined terms incorporated in the Indenture pursuant to Section 1.01
above.

                                   ARTICLE 2.
                                  Miscellaneous

     Section 2.01 Effect of the Supplemental Indenture. This Supplemental
Indenture supplements the Indenture and shall be a part, and subject to all the
terms, thereof. Except as expressly supplemented hereby, the Indenture and the
Notes issued thereunder shall continue in full force and effect.

     Section 2.02 Governing Law. This Supplemental Indenture shall be governed
by, and construed in accordance with, the laws of the State of New York, but
without giving effect to applicable principles of conflicts of law to the extent
that the application of the laws of another jurisdiction would be required
thereby.

     Section 2.03 Trustee Makes No Representation. The Trustee makes no
representation as to the validity or sufficiency of this Supplemental Indenture.

     Section 2.04 Effect of Headings. The section headings herein are for
convenience only and shall not affect the construction thereof.

     Section 2.05 Counterparts. The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them shall represent the same agreement.

                     [SIGNATURE PAGE TO IMMEDIATELY FOLLOW]

                                        4

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first stated above.

                                           ALESTRA, S. DE R.L. DE C.V.

                                       By: _____________________________________
                                           Name:
                                           Title:

                                           U.S. BANK TRUST NATIONAL ASSOCIATION,
                                           as Trustee,

                                       By: _____________________________________
                                           Name:
                                           Title:

                                        5

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