<PAGE>

                                                                    EXHIBIT 4(y)

UNSECURED CREDIT AGREEMENT NUMBER 05CS24, EXECUTED: (I) ON ONE PART, BY IXE
BANCO, S.A., INSTITUCION DE BANCA MULTIPLE, IXE GRUPO FINANCIERO (IXE BANCO
CORPORATION, FULL-SERVICE BANK, IXE FINANCIAL GROUP), IN ITS CAPACITY AS LENDER
(HEREINAFTER "IXE BANCO"), AND (II) ON THE OTHER PART, BY THE PERSON INDICATED
IN EXHIBIT "1" TO THIS AGREEMENT UNDER THE CAPTION "BORROWER" (HEREINAFTER,
"BORROWER"), PURSUANT TO THE FOLLOWING REPRESENTATIONS AND CLAUSES:

                                 REPRESENTATIONS

1.    In order to obtain a credit from Ixe Banco, taken out by means of this
      Agreement, Borrower, under oath, and being informed of the terms set forth
      in subsections I and IV of Article 112 of the Credit Institutions Law (Ley
      de Instituciones de Credito), represents that:

(a)   It is a legal entity duly incorporated and validly existing pursuant to
      the laws of the jurisdiction where it was incorporated, with full capacity
      to comply with the obligations assumed under the terms of the Agreement,
      and which Federal Taxpayers' Registry is the registry indicated in Exhibit
      "1" under the caption Federal Taxpayers' Registry.

(b)   No legal action or proceeding exists against Borrower or against its
      assets (or which may encumber them) with judicial or administrative
      authorities.

(c)   That it has enough capacity to execute this Agreement, as inferred from
      Exhibit "1" to this Agreement under the caption Capacity.

II.   Ixe Banco represents to be a corporation duly incorporated and authorized
      to operate as Full-Service Bank.

Once the foregoing is expressed, the parties hereto grant the following:

                                     CLAUSES

FIRST.- DEFINITION OF TERMS.- The terms used in this Agreement and described
hereinbelow shall have the following meanings, and shall apply equally to the
singular or plural forms of such terms:

"Drawdown Period" means the term of time comprised between the date of this
Agreement and the date indicated in Exhibit "1" under the caption "Drawdown
Deadline".

"Drawdown Deadline" means the date indicated in Exhibit "1" under the caption
"Drawdown Deadline", or the date when Borrower is given notice of the
restriction or termination hereunder in its Fifth Clause, whichever comes first.

"Checking Account" means the checking account that Ixe Banco carries for
Borrower.

"Checking Account Number" means the number of the checking account that Ixe
Banco shall carry for Borrower, as indicated in Exhibit "1" under the caption
Checking Account Number.

"Base Rate", the Equilibrium Interbank Interest Rate (E.I.I.R.) to receive 28
days term deposits, as informed by the Bank of Mexico (Banco de Mexico) through
the Official Gazette of the Federation (Diario Oficial de la Federacion) taking
as reference the rate in force on the date when each Interest Period begins, on
the understanding that, in case such EIIR rate disappears, Borrower and Ixe
Banco agree that the rate that substitutes

<PAGE>

                                      - 2 -

such rate shall be applied, and if no such rate exists, the return rate paid by
the Federal Treasury Certificates (Certificados de la Tesoreria de la Federacion
or "CETES") for a 28 day term in its primary placement shall be applied, taking
as reference the rate in force at the beginning of each Interest Period. The
annual rate shall correspond to the interest or gross return offered hereunder.

"Surcharge" is the differential of points that will be added to the Base Rate.

"Ordinary Rate" is the sum of the Base Rate plus the Surcharge.

"Interest Payment Date" means the date when the interest accrued during the
calendar months throughout the course of the Interest Period shall be paid,
which shall be made precisely on the last day of each month, starting as of the
credit Drawdown.

"Interest Period" means the period of one calendar month to estimate the
interest on the unpaid balance of the capital of each credit Drawdown, on the
understanding that the first period begins on the date of the Initial Drawdown,
and ends and includes the nearest Interest Payment Date and, in the case of
subsequent periods, it starts on the 1 (one) calendar day immediately preceding
the Interest Payment Date, and ends and includes the next Interest Payment Date.

"Drawdowns" means the credit drawdowns carried out pursuant to this Agreement,
according to the Fourth Clause hereto.

"Business Day" means all the days of the year on which the credit institutions
are not required to close their doors to the public and to suspend their
operations according to the provisions set forth by the National Banking
Commission (Comision Nacional Bancaria) for this purpose, as well as by other
competent authorities.

SECOND.- OPENING OF AN UNSECURED CREDIT.- Pursuant to the provisions of Article
291 of the Negotiable Instruments and Credit Operations General Law (Ley General
de Titulos y Operaciones de Credito), and subject to the terms and conditions
hereunder, Ixe Banco opens an unsecured credit to Borrower up to the amount
indicated in Exhibit "1" under the caption "Amount of Credit" (hereinafter the
"Amount of Credit"); this amount does not include interest, fees and expenses;
and Borrower binds to pay to Ixe Banco the amounts of the credit it may withdraw
(hereinafter the "Drawdowns"), and the interest, fees and expenses according to
the provisions hereunder.

THIRD.- SUBJECT MATTER OF THE OPENING OF CREDIT.- The parties agree that the
opening of the unsecured credit that Ixe Banco extends hereunder in favor of
Borrower may only be allocated to the subject matter described in Exhibit "1",
under the caption "Subject Matter of the Credit".

FOURTH.- CREDIT DRAWDOWN. Borrower shall withdraw the credit in one or more
Drawdowns, either totally or partially, by giving written notice to Ixe Banco
pursuant to the form "Drawdown Notice" attached hereto as Exhibit "2", and
through the subscription of the promissory notes that shall comply with the
characteristics set forth by Article 170 of the Negotiable Instruments and
Credit Operations General Law, provided however the Drawdowns take place within
the Drawdown Period.

FIFTH.- LIMITATION REGARDING THE CREDIT AND THE DRAWDOWN PERIOD; TERMINATION BY
IXE BANCO. Ixe Banco may, at any time and without the need to comply with any
other prerequisite other than giving written notice to Borrower, limit the
Amount of the Credit or the Drawdown Period, or both at the same time, as well
as to terminate this Agreement. Once the Amount of Credit or the Drawdown Period
is limited, or both at the same time, or once the Agreement is terminated, the
portion of the credit not withdrawn by Borrower up to that moment shall
terminate.

<PAGE>

                                      - 3 -

Ixe Banco is authorized not to extend financing in case its treasury is hindered
to grant credits due to the provisions set forth by the Bank of Mexico or by any
other authority.

SIXTH.- PAYMENT OF CREDIT. Except for the events set forth in this Agreement,
Borrower binds to pay the Drawdowns pursuant to the terms of payment indicated
in Exhibit "1" to this Agreement, under the caption "Terms of Payment", as well
as the promissory note or notes derived thereof.

SEVENTH.- INTEREST.- Borrower binds to pay to Ixe Banco:

(a)   Ordinary Interest. Regarding the Drawdowns made under the Credit, the
      interest on daily unpaid balances accrued throughout each Interest Period
      payable on the Interest Payment Dates, to the rate that results by adding
      to the Base Rate the points in percentage terms indicated in Exhibit "1"
      under the caption Surcharge.

(b)   Default Interest. In case of default to pay any amount owed hereunder, the
      default interest shall accrue on said unpaid amount at the rate of the
      Ordinary Rate in force throughout the course of the default, multiplied by
      the factor of 2 (two) pursuant to the terms hereunder.

The estimate of the interest accrued hereunder shall be estimated on the basis
of 1 (one) year of 360 (three hundred and sixty) calendar days effectively
elapsed.

EIGHTH.- FEES AND EXPENSES.- Hereby Borrower binds to pay Ixe Banco a fee to
open the credit equal to the amount that results of applying the percentage
indicated in Exhibit "1" under the caption "Fee to Open the Credit" to the
Amount of the Credit, payable once the first Drawdown of the credit is made.
Likewise, Borrower binds to pay, on its account, each and every one of the
expenses derived or related to the execution, performance and enforcement of the
Agreement.

NINTH.- TERM. This Agreement shall remain in force up to the date that has been
indicated in Exhibit "1" under the caption "Date of Termination of the
Agreement" (hereinafter the "Date of Termination of the Agreement"), and
Borrower is bound to pay any unpaid or owed amount hereunder precisely on the
Date of Termination of the Agreement", notwithstanding the term for such payment
is not yet due; on the understanding, however, that the rules pertinent to the
payment set forth in the Tenth Clause hereinbelow and the rules pertinent to the
default interest set forth in the Seventh Clause, Subparagraph (b) above, shall
remain in force until all the amounts owed pursuant to this Agreement are paid
in full.

TENTH.- PAYMENTS. All payments that Borrower must make hereunder (upon their due
date or before, pursuant to this Agreement), including but not limited to the
payments of the Drawdowns, interest, fees and expenses, shall be made as
follows:

(a)   Borrower shall make all payments to Ixe Banco at the domicile of Ixe
      Banco, with immediately available funds by means of a deposit in the
      Checking Account of Borrower, and for such reason, Borrower binds to
      maintain the funds required to pay such amounts and, if applicable, to
      deposit (or to credit in any other manner, except with additional credit
      Drawdowns) the additional funds required to pay the amounts owed. In order
      to comply with the provisions of this Subparagraph (a), Borrower hereby
      expresses, and irrevocably instructs and authorizes Ixe Banco, to charge
      in its Checking Account the amounts it may owe to Ixe Banco from time to
      time. Notwithstanding the above, Ixe Banco may give notice to Borrower of
      a different place of payment, in which case Borrower shall make all the
      payments due after the date of the notice at the place of payment
      indicated by Ixe Banco.

<PAGE>

                                     - 4 -

(b)   It is expressly understood that Borrower shall promptly make the payments
      agreed hereunder, without the need for Ixe Banco to request their payment
      thereof.

(c)   At its entire discretion, Ixe Banco shall determine the manner to allocate
      the amounts it receives from Borrower as payment of its obligations
      derived hereunder.

(d)   The parties agree that, if applicable, in the statement of account
      prepared and certified by the accountant of Ixe Banco authorized therefor
      pursuant to the Credit Institutions Law, shall be enough to evidence: (i)
      the amount of the Amount of the Credit that Borrower may withdraw, and
      (ii) the balance of the Amount of the Credit withdrawn on account of
      Borrower, as well as the interest, fees and expenses that borrower shall
      pay to Ixe Banco hereunder.

(e)   Except for the taxes that, if applicable, Ixe Banco shall pay pursuant to
      the applicable legislation, Borrower shall make all the payments under
      this Agreement, free of any tax, retention, assessment or fee (hereinafter
      the "Taxes") established in any jurisdiction, be it federal, state or
      municipal. In the case of such Taxes, the amount of the payments that
      Borrower shall make hereunder shall increase to the amount required to
      insure that, once such Taxes are paid, Ixe Banco receives the amount it
      would receive hereunder if such Taxes would not exist. If, for any reason,
      Ixe Banco pays the amount of such Taxes, Borrower shall reimburse to Ixe
      Banco the amount of the Taxes under the terms indicated or demand the
      payment in any other manner, as required by Ixe Banco. The obligations set
      forth in this Subparagraph (c) shall remain in force as long as the
      payment of such Taxes is enforceable pursuant to the applicable
      legislation, notwithstanding this Agreement has been terminated.

(f)   Any payment that, according to this Agreement, must be made on a
      non-business day shall be made on the immediate following Business Day.

(g)   The receipt by Ixe Banco of any amount of the Amount of the Credit shall
      not limit nor terminate in any manner the right of Ixe Banco to receive
      interest or any other amount payable hereunder.

ELEVENTH.- A TRUST AS AN ALTERNATE SOURCE OF PAYMENT. Concurrently to the
execution of this Agreement, an Irrevocable Trust as Alternate Source of Payment
is executed with BBVA Bancomer Servicios, S.A., Institucion de Banca Multiple,
Grupo Financiero BBVA Bancomer, Direccion Fiduciaria (BBVA Bancomer Servicios
Corporation, Full-service Bank, BBVA Bancomer Financial Group, Fiduciary
Division), in its capacity as Trustee (the Trust), as an alternate source to pay
this credit, where Ixe Banco becomes the Primary Beneficiary regarding the
entire property held in the Trust.

The flows of cash that make up the property held in the Trust shall be applied
as an alternate source to pay this credit, and thus as soon as the Trust makes a
payment to Ixe Banco in its capacity as Primary Beneficiary, it shall apply said
payment to pay the credit up to the amount that corresponds to the interest and
to the capital of the credit.

In case Trustee does not make any payment to Ixe Banco in its capacity as
Primary Beneficiary, or either these payments are not enough to pay the unpaid
balance of the credit, Borrower shall continue to be bound to pay the unpaid
balance of the credit plus the interest accrued, and the expenses and court
costs, if applicable.

In case the payments made by the Trustee to Ixe Banco in its capacity as Primary
Beneficiary are not enough to cover the payment in question, said amount shall
be applied, in first place, to pay default interest, if applicable;
subsequently, it shall be applied to pay ordinary interest and, in last place,
it shall be applied to pay the principal sum.

Due to the above, Borrower may not transfer, alienate or assign in any manner
the assets or rights that make up the property held in the Trust without the
prior written consent from Ixe Banco.

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                                      - 5 -

TWELFTH.- EVENTS OF ACCELERATION. If any of the cases indicated hereinbelow
takes place, Ixe Banco may (but shall not be bound to) accelerate the unpaid
amount of the principal sum owed hereunder and the interest accrued up to that
date, as well as all the other amounts owed hereunder, in which case the
principal amount, the interest accrued up to that date, and any other amount
owed hereunder shall be enforceable and payable by Borrower immediately, without
the need of an additional request, notification or notice.

(a)   the default by Borrower to pay the Drawdowns, interest, fees, expenses or
      amounts of any other kind owed hereunder; or

(b)   the determination that any statement made by Borrower is false or
      incorrect, or that any certificate or document delivered by Borrower to
      Ixe Banco is false; or

(c)   the default by Borrower of any obligation, covenant or agreement that must
      be performed pursuant to this Agreement, including but not limited to the
      affirmative covenants and the negative covenants set forth in Exhibit "3"
      to this Agreement; or

(d)   the status of bankruptcy, or the declaration of personal bankruptcy by
      Borrower, or the assignment by Borrower of a significant part of its
      assets in favor of its creditors, or the deprivation of the ownership,
      custody or control of a significant part of the assets or businesses of
      Borrower due to an expropriation, seizure or taking over by any
      governmental authority; or

(e)   the default or imminent default by Borrower of any other covenant or
      agreement by reason of which it receives loans or credits from Ixe Banco
      or from other financial entities.

(f)   if Borrower makes a change in the control of the shares during the life of
      this Agreement without the prior authorization from Ixe Banco; or

(g)   if Borrower carries out acts tending to alienate or encumber its assets
      outside the ordinary course of its operations during the life of this
      Agreement; or

(h)   if it makes the payment of dividends during the life of this Agreement
      without the prior consent in written from Ixe Banco; or

(i)   if the amount of the credit is not used for the purposes indicated in
      Exhibit "1", under the caption Purpose of the Credit; or

(j)   if Borrower ceases to pay its labor or fiscal assessments, and does not
      cure such situation within a term of 15 calendar days, or either if it
      faces labor or tax problems that may endanger the continuity of the
      ordinary operations of Borrower; or

(k)   if Borrower grants guarantees by endorsement, bonds or collaterals outside
      the ordinary course of its operations during the life of this Agreement,
      except with the prior written consent from Ixe Banco; or

(l)   if Borrower takes out financial liabilities without the prior written
      consent from Ixe Banco.

The above notwithstanding, whenever Borrower incurs in any of the aforementioned
events, it shall pay to Ixe Banco an interest at the rate indicated in
subparagraph (b) of the Seventh Clause on the Amount of the Credit as of the
date when it incurred in any of such cases, and up to the date on which Borrower
itself pays it in full to Ixe Banco, notwithstanding the authority of Ixe Banco
to demand the full payment of the credit.

In case Ixe Banco may request in a judicial manner, at any moment, the
performance of any of the obligations on account of Borrower pursuant to this
Agreement, the parties expressly agree that Ixe Banco shall indicate, at its own
discretion, the assets that shall be subject to seizure, without being subject
to the provisions of Articles 536

<PAGE>

                                      - 6 -

and 537, subsection I, of the Code of Civil Procedure for the Federal District
(Codigo de Procedimientos Civiles para el Distrito Federal), and Article 1395 of
the Commerce Code (Codigo de Comercio).

THIRTEENTH. OTHER OBLIGATIONS OF BORROWER; OTHER RIGHTS OF IXE BANCO. Apart from
the obligations on account of Borrower derived hereunder, during the life of
this Agreement, Borrower shall assume the obligations set forth in Exhibit "3"
to this Agreement.

Likewise, the parties agree that Ixe Banco may terminate this Agreement or
either take action pursuant to the terms of the Fifth Clause, without any
liability for Ixe Banco, in the event of problems of liquidity in the financial
system that may hinder it to obtain the financing required to carry out the
opening of the credit foreseen in this Agreement, due to: (i) actions or
measures taken by the competent governmental authorities, or (ii) circumstances
beyond its control which are of public knowledge.

FOURTEENTH.- ASSIGNMENT; DISCOUNT. Ixe Banco shall have at all times the right
to assign or discount its rights and obligations derived hereunder, either
totally or partially. In order to make easier the negotiation of the assignment
or discount of the credit subject matter of this Agreement, prior request from
Ixe Banco, Borrower binds to subscribe one or several promissory notes in favor
of Ixe Banco in the Amount of the Credit, including, if applicable, the ordinary
and default interest accrued pursuant to this Agreement up to the moment of the
assignment or discount in question, as well as the documents required to carry
out such assignment or discount.

Borrower may not alienate, assign, encumber, transfer or dispose of its rights
and obligations hereunder in any other manner without the prior written consent
from Ixe Banco.

Borrower expressly authorizes Ixe Banco to assign, negotiate and discount the
promissory notes subscribed, even before its due date, in which case the
guarantees granted shall survive.

FIFTEENTH.- INCREASE OF COSTS. If, subsequently to the execution of this
Agreement, any law, regulation, circular letter or other provision is amended
(including but not limited to the prerequisites regarding reserves, deposits,
taxes and other conditions) that apply to "Ixe Banco" or to any of its offices
entrusted to manage and to finance the Drawdowns, or if any court with competent
jurisdiction changes the interpretation of any of the above, or if an event
takes place (subject or not to the control of Borrower) and, as consequence
thereof the cost for "Ixe Banco" to make or keep current the Drawdowns
increases, or if the amounts received or to be received by "Ixe Banco" decrease,
Borrower shall pay to "Ixe Banco", at its request and on the last day of the
Interest Period in force at the time, the additional, reasonable and verifiable
additional amounts required to offset to "Ixe Banco" said increase in the cost
or decrease of income pursuant to the request made by "Ixe Banco" mentioned
above; "Ixe Banco" shall indicate the reasons that increased the cost or
decreased the income, as well as its pertinent estimates and, except for a
mistake in such estimates, the determination of "Ixe Banco" shall be conclusive
and mandatory for Borrower. In event that Ixe Banco would require the payment of
additional amounts pursuant to the above, Borrower may, at its choice, pay in
advance the credit Drawdowns within a term of 30 (thirty) days as of the date of
the pertinent request without any penalty, jointly with the interest accrued
since the last Interest Payment Date, and up to the date of the pertinent
advance payment.

SIXTEENTH.- DOMICILES; NOTICES AND NOTIFICATIONS. The notices and notifications
that the parties shall give pursuant to this Agreement shall be delivered at the
domiciles indicated at the bottom of this Agreement; understanding as such the
last domicile notified to each party hereunder. Ixe Banco may deliver the
notices and notifications it must or desires to send to Borrower in relation to
this Agreement through telefax, at the phone number of Borrower that appears at
the bottom of this Agreement.

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                                      - 7 -

SEVENTEENTH.- ENTIRE AGREEMENT AND AMENDMENTS. This Agreement, and the Exhibits
"1", "2" and "3" hereto, constitute the entire agreement, which can only be
amended by means of a written agreement executed by and between Ixe Banco and
Borrower.

EIGHTEENTH.- EXECUTION RIGHTS. This Agreement and the statement of account
certified by the accountant of Ixe Banco authorized therefor shall represent the
document proving the plaintiff's right of execution, without the need of any
acknowledgment of signatures, nor any other requirement.

NINETEENTH.- ACT OF GOD. Under the terms of Article 2111 of the Civil Code of
the Federal District (Codigo Civil para el Distrito Federal), Borrower shall be
bound to perform each and every one of its obligations as derived hereunder,
even in the case of an act of God.

TWENTIETH.- GOVERNING LAW AND JURISDICTION. This Agreement shall be governed and
construed according to the laws in force for the Federal District, United
Mexican States. The parties expressly submit themselves to the jurisdiction of
the courts with competent jurisdiction of the Federal District, United Mexican
States, and waive any other venue that may correspond to them by reason of their
domicile, or the location of their assets.

TWENTY-FIRST.- TITLES OF CLAUSES. The titles that appear in the clauses of this
instrument are intended solely to facilitate its reading and handling, and thus
are not considered to necessarily define, limit or describe their contents.

This Agreement, and each one of the exhibits hereto, have been signed in four
counterparts on April the 13th of 2005 in Mexico City, Federal District; one
copy of this instrument and the exhibits thereto shall remain in possession of
Borrower, other two counterparts shall remain in possession of Ixe Banco, and
the last counterpart shall remain in possession of the pertinent Notary Public.

BORROWER:                                 IXE BANCO:
Maxcom Telecomunicaciones, S.A. de C.V.   Ixe Banco, S.A., Institucion de Banca
                                          Multiple,
                                          Ixe Grupo Financiero.

<TABLE>
<CAPTION>
          (Two illegible signatures)                               (Blank)
-----------------------------------------------   -----------------------------------------
<S>                                               <C>
Represented by Gonzalo Alarcon Iturbide and       Represented by Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno.                        Armando Jorge Rivero Laing.
Domicile: Guillermo Gonzalez Camarena No. 2000,   Domicile: Av. Periferico Sur No. 314
Col. Centro Ciudad Santa Fe, C.P. 01210,          Col. San Angel Tlacopac.
Mexico, Federal District                          C.P. 01049, Mexico, Federal District.
Phone number: 5147-1111.                          Phone number: 5174-2222.
</TABLE>

<PAGE>

                                    EXHIBIT 1

UNSECURED CREDIT AGREEMENT WHICH NUMBER, DATE OF EXECUTION AND PARTIES ARE
INDICATED HEREINBELOW (HEREINAFTER, THE "AGREEMENT").

AGREEMENT NUMBER:              05cs24

CHECKING ACCOUNT NUMBER:       1154961-0

PARTIES:                       (1) Borrower: Maxcom Telecomunicaciones, S.A. de
                               C.V., represented by Messrs. Gonzalo Alarcon
                               Iturbide and Jorge Lopez Aguado Jimeno, as
                               borrower. It appears in the Agreement as
                               "Borrower".

                               (2) Ixe Banco: Ixe Banco, S.A., Institucion de
                               Banca Multiple, Ixe Grupo Financiero, represented
                               by Patricia Ferro Bertolo and Armando Jorge
                               Rivero Laing, as Lender. It appears in the
                               Agreement as "Ixe Banco".

DATE:                          April the 13th of 2005.

FEDERAL TAXPAYERS' REGISTRY:   MTE-960228-KL0

AMOUNT OF CREDIT:              $100,000,000.00 (One Hundred Million Pesos 00/100
                               Mexican Currency).

SUBJECT MATTER OF THE CREDIT:  Extension of coverage.

DRAWDOWN DEADLINE:             October the 13th of 2005.

TERMS OF PAYMENT:              Through 24 monthly and successive installments
                               of the capital; the payments shall be made on the
                               dates and in the amounts indicated in the
                               Drawdown Notices and in the Promissory Notes
                               derived hereunder.

SURCHARGE:                     3 (three) points in percentage terms.

FEE TO OPEN THE CREDIT:        1% (One Percent) on the Amount of Credit, payable
                               upon the first credit Drawdown.

DATE OF TERMINATION OF
THE AGREEMENT:                 April the 30th of 2007.

CAPACITY:

PATRICIA FERRO BERTOLO AND ARMANDO JORGE RIVERO LAING evidence their capacity as
representatives of Ixe Banco pursuant to the following instruments:

1. Public Instrument number 32,541, dated August the 1st of 1994, executed
before Roberto Courtade Bevilacqua, Notary Public Number 132 for the Federal
District, duly registered in the Public Registry of Commerce for the Federal
District under Commerce Folio number 193,508, dated November the 22nd of 1994,
which evidences the incorporation of Banco Fimsa, S.A.

<PAGE>

                                      - 2 -

2. Public Instrument number 33,450, dated May the 3rd of 1995, executed before
Roberto Courtade Bevilacqua, Notary Public Number 132 for the Federal District,
duly registered in the Public Registry of Commerce for the Federal District
under Commerce Folio number 193,508, dated January the 4th of 1996, which
evidences the change of firm name of Banco Fimsa, S.A., Institucion de Banca
Multiple, Fimsa Grupo Financiero, to the firm name of Ixe Banco, S.A.,
Institucion de Banca Multiple, Ixe Grupo Financiero.

3. Public Instrument number 7,320, dated October the 31st of the year 2000,
executed before Mario Evaristo Vivanco Paredes, Notary Public Number 67 for the
Federal District, duly registered in the Public Registry of Commerce for the
Federal District under Commerce Folio number 193508, dated March the 16th of
2001, which evidences, amongst other things, the granting of the power of
attorney for acts of administration in favor of Mr. Armando Jorge Rivero Laing,
to be exercised jointly with any other legal representative authorized for such
purposes.

4. Public Instrument number 107,346, dated March the 4th of the year 2005,
executed before Cecilio Gonzalez Marquez, Notary Public Number 151 for the
Federal District, pending to be registered in the Public Registry of Commerce
for the Federal District since it was recently granted, which evidence, amongst
other things, the granting of the power of attorney for acts of administration
in favor of Patricia Ferro Bertolo, to be exercised jointly with any other legal
representative authorized for such purposes.

GONZALO ALARCON ITURBIDE AND JORGE LOPEZ AGUADO JIMENO evidence their capacity
as representatives of MAXCOM TELECOMUNICACIONES, S.A. DE C.V. pursuant to the
following instruments:

1. Public Instrument number 86,115, dated February the 28th of 1996, executed
before Ignacio Soto Borja, Notary Public Number 129 for the Federal District,
duly registered in the Public Registry of Commerce for the Federal District
under Commerce Folio number 210585, dated June the 11th of 1996, which evidence
the incorporation of the Corporation under the firm name of Amaritel, S.A. de
C.V.

2. Public Instrument number 2,967, dated May the 21st of 1998, executed before
Alberto T. Sanchez, Notary Public Number 83 for the Federal District, duly
registered in the Public Registry of Commerce for the Federal District under
Commerce Folio number 210585, which evidences the full amendment to the
Corporate Bylaws of the Corporation.

3. Public Instrument number 55,145, dated February the 9th of 1999, executed
before Miguel Alessio Robles, Notary Public Number 19 for the Federal District,
duly registered in the Public Registry of Commerce for the Federal District
under Commerce Folio number 210585, dated March the 16th of 1999, which
evidences the change of firm name of the Corporation to that of Maxcom
Telecomunicaciones, S.A. de C.V.

4. Public Instrument number 56,631, dated October the 11th of 2002, executed
before Carlos Catano Muro Sandoval, Notary Public Number 51 for the Federal
District, pending to be registered in the Public Registry of Commerce for the
Federal District under Commerce Folio number 210585, dated December the 2nd of
2002, which evidences the granting of the power of attorney in favor of Messrs.
Gonzalo Alarcon Iturbide and Jorge Lopez Aguado Jimeno, granted with individual
authorities for acts of administration, and for lawsuits and collections.

GENERAL INFORMATION:

PATRICIA FERRO BERTOLO, Mexican by birth, born in Mexico City, Federal District,
on February the 11th of 1967, working as a Bank Officer, domiciled in Periferico
Sur number 314, Colonia San Angel Tlacopac, C.P. 01049, in Mexico City, Federal
District.

<PAGE>

                                      - 3 -

ARMANDO JORGE RIVERO LAING, Mexican by birth, born in Mexico City, Federal
District, on September the 3rd of 1963, married, an Attorney at Law, domiciled
in Periferico Sur number 314, Colonia San Angel Tlacopac, C.P. 01049, in Mexico
City, Federal District.

GONZALO ALARCON ITURBIDE, Mexican by birth, born in Mexico City, Federal
District, on June the 20th of 1969, married, an Attorney at Law, domiciled in
Guillermo Gonzalez Camarena number 2000, Col. Centro Ciudad Santa Fe, C.P.
01210, in Mexico City, Federal District, with Federal Taxpayers' Registry
AAIG-690620-AK8.

JORGE LOPEZ AGUADO JIMENO, Mexican by birth, born in Mexico City, Federal
District, on March the 21st of 1959, married, a Public Accountant, domiciled in
Guillermo Gonzalez Camarena number 2000, Col. Centro Ciudad Santa Fe, C.P.
01210, in Mexico City, Federal District, with Federal Taxpayers' Registry
LOJJ-590321-IU6.

The parties hereto sign this EXHIBIT "1" to the Agreement to acknowledge their
acceptance, and agreed to the terms and conditions contained herein on April the
13th of 2005.

BORROWER:                                 IXE BANCO:
Maxcom Telecomunicaciones, S.A. de C.V.   Ixe Banco, S.A., Institucion de Banca
                                          Multiple,
                                          Ixe Grupo Financiero.

  (Two illegible signatures)                         (Blank)
----------------------------------        ------------------------
Represented by Messrs.                    Represented by:
Gonzalo Alarcon Iturbide and              Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno.                Armando Jorge Rivero Laing.

<PAGE>


                                   EXHIBIT "2"

DRAWDOWN NOTICE REGARDING UNSECURED CREDIT AGREEMENT NUMBER O5CS24, WHICH
EXECUTION DATE AND PARTIES ARE INDICATED HEREINBELOW:

                                 DRAWDOWN NOTICE

                                             ______ to _____ of ____  of 20_____
IXE BANCO, S.A., INSTITUCION DE BANCA MULTIPLE
IXE GRUPO FINANCIERO

Dear Sirs:

Pursuant to the Fourth Clause of the Unsecured Credit Agreement Number 05cs24,
executed on April the 13th of 2005, by and between Maxcom Telecomunicaciones,
S.A. de C.V. and Ixe Banco, S.A., Institucion de Banca Multiple, Ixe Grupo
Financiero (hereinafter the "Credit Agreement"), through this document I inform
you of my desire to withdraw the amount of $__________ M.C. __________ (Mexican
Currency), charged to the Amount of Credit. Therefore, I hereby instruct Ixe
Banco to deposit such amount in checking account number [1154961-D], carried in
such Institution, pursuant to the Credit Agreement.

The amount of the Credit Amount I hereby instruct to be deposited in the
aforesaid checking account shall be destined to _______________.

The Surcharge and the Terms of Payment of this Drawdown shall be as follows:

SURCHARGE: ________________________ TERMS OF PAYMENT: ____________________

The reception of this notice, jointly with the deposit made by Ixe Banco of the
amount to be withdrawn in the checking account cited herein, shall represent
conclusive evidence of the drawdown of the funds under the Credit Agreement, and
thus the terms and conditions set forth in the Credit Agreement regarding the
credit drawdown requested herein shall apply.

                                  Respectfully,
                                    BORROWER:
                     Maxcom Telecomunicaciones, S.A. de C.V.

             ------------------------------------------------------
           By: Gonzalo Alarcon Iturbide and Jorge Lopez Aguado Jimeno.

The parties hereto sign Exhibit "2" to the Agreement to acknowledge their
acceptance, and agreed to the terms and conditions contained herein on April the
13th of 2005.

BORROWER:                                 IXE BANCO:

Maxcom Telecomunicaciones, S.A. de C.V.   Ixe Banco, S.A., Institucion de Banca
                                          Multiple,
                                          Ixe Grupo Financiero.

   (Two illegible signatures)                      (Blank)
---------------------------------         ---------------------------
Represented by Messrs.                    Represented by:
Gonzalo Alarcon Iturbide and              Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno.                Armando Jorge Rivero Laing.

<PAGE>

                                      - 1 -

                                    EXHIBIT 3

EXHIBIT "3" THAT SETS FORTH THE AFFIRMATIVE AND NEGATIVE COVENANTS OF BORROWER
UNDER THE UNSECURED CREDIT AGREEMENT WHICH NUMBER, DATE OF EXECUTION AND PARTIES
THERETO ARE INDICATED HEREINBELOW (HEREINAFTER "THE AGREEMENT").

AGREEMENT NUMBER:              05cs24

CHECKING ACCOUNT NUMBER:       1154961-D

PARTIES:                       (1) Borrower: Maxcom Telecomunicaciones, S.A. de
                               C.V., represented by Messrs. Gonzalo Alarcon
                               Iturbide and Jorge Lopez Aguado Jimeno, as
                               borrower. In appears in the Agreement as
                               "Borrower".

                               (2) Ixe Banco: Ixe Banco, S.A., Institucion de
                               Banca Multiple, Ixe Grupo Financiero, represented
                               by Patricia Ferro Bertolo and Armando Jorge
                               Rivero Laing, as Lender. In appears in the
                               Agreement as "Ixe Banco".

DATE:                          April the 13th of 2005.

I.- BORROWER'S AFFIRMATIVE COVENANTS. During the life of the Agreement, and
until the Drawdowns, interest, fees, expenses and any other amount owed by
Borrower pursuant to the Agreement are paid in full, Borrower agrees to comply
with the following affirmative covenants:

a)    To deliver to Ixe Banco within 30 (thirty) calendar days following the
      close of each quarter, the internal financial statements of the
      immediately preceding quarter duly signed by the General Manager or the
      person responsible for the financial division or the person who holds a
      similar position, jointly with a report stating if whether on the date of
      such financial statements any of the events of default under the Agreement
      has taken place, and in the event of a default, to specify its nature and,
      if applicable, the measures taken and that will be taken to cure such
      event.

b)    To deliver to Ixe Banco within 120 (one hundred and twenty) calendar days
      following the close of its fiscal year, the annual financial statements
      (balance sheets, income statement, cash flow) audited and certified by the
      firm of public accountants accepted by Ixe Banco, jointly with a letter
      signed by the General Manager and the person responsible for the financial
      division or the person who holds a similar position which certifies that
      none of the events of default has taken place and, otherwise, which
      specifies its nature and, if applicable, the measures taken and that will
      be taken to cure such event.

c)    To give notice to Ixe Banco of any event that constitutes an event of
      default, or that may become an event of default throughout the course of
      time, within 15 (fifteen) calendar days after such event is known, jointly
      with a statement which describes the details of such event, as well as the
      measures taken and that will be taken to cure such event.

d)    To give notice to Ixe Banco of the existence of (i) any claim, action,
      litigation, proceeding, remedy or arbitration brought with any
      administrative or judicial authority or arbitration board, either national
      or foreign, within the 15 (fifteen) calendar days after such circumstance
      is known, provided it adversely affects, or that it may be foreseen that
      it will adversely affect the businesses, operations and properties of
      Borrower in a significant manner, (ii) any labor dispute provided it
      adversely affects, or which may be

<PAGE>

                                      - 2 -

      foreseen that it will adversely affect the businesses, operations and
      properties of Borrower in a significant manner, and (iii) any other
      contingent liability or responsibility on account of Borrower that
      adversely affects, or which may be foreseen that it will adversely affect
      the businesses, operations and properties of Borrower in a significant
      manner.

e)    To observe all laws, regulations, decrees, rules and orders of any nature
      that apply to it, including, without any limit whatsoever, the prompt
      payment of all taxes, assessments and duties imposed on Borrower and its
      properties.

f)    To maintain in full force and effect the licenses, authorizations,
      concessions or registrations it may hold on the date when the Agreement is
      executed, and to obtain the licenses, authorizations, concessions or
      registrations that are subsequently required for the ordinary course of
      its businesses and to comply with its obligations pursuant to the
      Agreement.

g)    To keep the accounting in accordance to the accounting principles
      generally accepted and applied in Mexico that adequately reflect its
      operations, properties and financial situation.

h)    To keep all the assets required to operate in good conditions and to carry
      out all the repairs, replacements, additions and improvements as
      necessary.

i)    To allow Ixe Banco to visit its offices and facilities, as well as to
      inspect the accounting records, and also to provide to Ixe Banco the
      clarifications it may reasonably request regarding the accounting records,
      provided they are requested with 15 calendar days in advance.

j)    To maintain the same control of the shares throughout the life of this
      Agreement, except with the prior written consent from Ixe Banco.

k)    To comply with its obligations to make payments derived from any credit
      taken out with Ixe Banco or any other financial entity.

l)    To maintain itself as an ongoing business, without changing its corporate
      purpose and legal nature.

II. BORROWER'S NEGATIVE COVENANTS. During the life of the Agreement and until
the Drawdowns, interest, fees and any other amount owed by Borrower pursuant to
the Agreement are paid in full, Borrower agrees to comply with the following:

a)    That it shall not to carry out acts that tend to its dissolution,
      liquidation, changing its corporate form, merging or spinning-off, nor to
      decrease its minimum capital stock without the prior written consent from
      Ixe Banco.

b)    That it shall not sell or encumber the assets of the company outside the
      ordinary course of its operations, as long as the Agreement remains in
      force, without the prior written consent from Ixe Banco.

c)    That it shall not pay dividends during the life of this Agreement without
      the prior written consent from Ixe Banco.

d)    That it shall not take out financial liabilities without the prior written
      consent from Ixe Banco.

The parties hereto sign Exhibit "3" to the Agreement to acknowledge their
acceptance, and agreed to the terms and conditions contained herein on April the
13th of 2005.

<PAGE>

                                     - 3 -

BORROWER:                                 IXE BANCO:

Maxcom Telecomunicaciones, S.A. de C.V.   Ixe Banco, S.A., Institucion de Banca
                                          Multiple,
                                          Ixe Grupo Financiero.

   (Two illegible signatures)                      (Blank)
-----------------------------------       ------------------------
Represented by Messrs.                    Represented by:
Gonzalo Alarcon Iturbide and              Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno.                Armando Jorge Rivero Laing.

<PAGE>

Certificate Number:

In Mexico City, Federal District, on the thirteenth day of the month of April of
the year two thousand and five, I, Maria Esther Garcia Alvarez, head of the
Office of Commercial Notary Public number Four for the Federal District, do
certify:

That Messrs. Patricia Ferro Bertolo and Armando Jorge Rivero Laing appeared on
this date and before me under their capacities as legal representatives of "Ixe
Banco", Sociedad Anonima, Institucion de Banca Multiple, Ixe Grupo Financiero;
as well as Messrs. Gonzalo Alarcon Iturbide and Jorge Lopez Aguado Jimeno under
their capacities as legal representatives of MAXCOM TELECOMUNICACIONES, SOCIEDAD
ANONIMA DE CAPITAL VARIABLE, who appear respectively as "Ixe Banco" and
"Borrower" regarding the Unsecured Credit Agreement Number 05cs24 that precedes
this instrument, in order to ratify each and every one of the provisions
thereto, and who state that the insertions made truly express their wills, and
that the signatures that appear therein are authentic since they are of their
own hands, and that these signatures are the same signatures they use in all
their acts and businesses; that they render this statement under oath and who,
in witness whereof, sign this certificate in my presence and in a joint manner.

BORROWER:                                 IXE BANCO:

Maxcom Telecomunicaciones, S.A. de C.V.   Ixe Banco, S.A., Institucion de Banca
                                          Multiple,
                                          Ixe Grupo Financiero.

  (Two illegible signatures)                      (Blank)
-------------------------------           ------------------------
Represented by Messrs.                    Represented by:
Gonzalo Alarcon Iturbide and              Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno.                Armando Jorge Rivero Laing.

<PAGE>

                                 PROMISSORY NOTE

<TABLE>
<S>          <C>                                         <C>                           <C>
SUBSCRIBER:  MAXCOM TELECOMUNICACIONES, S.A. DE C.V.     AMOUNT:                       $100,000,000.00

DOMICILE:    GUILLERMO GONZALEZ CAMARENA NO. 2000,       FEDERAL TAXPAYERS' REGISTRY:  MTE-960228-KL0.
             COL. CENTRO, CIUDAD SANTA FE,
             C.P. 01210, MEXICO CITY, FEDERAL DISTRICT.
</TABLE>

PURSUANT TO THIS PROMISSORY NOTE, WE AGREE AND BIND OURSELVES TO UNCONDITIONALLY
PAY, AT THE ORDER OF IXE BANCO, SOCIEDAD ANONIMA, INSTITUCION DE BANCA MULTIPLE,
IXE GRUPO FINANCIERO (THE "BENEFICIARY"), THE AMOUNT OF $100,000,000.00 (ONE
HUNDRED MILLION PESOS 00/100 MEXICAN CURRENCY) WITHIN THE TERM THAT SHALL MATURE
ON APRIL THE 30TH OF THE YEAR 2007, BY MEANS OF 24 MONTHLY AND SUCCESSIVE
AMORTIZATIONS, PURSUANT TO THE FOLLOWING SCHEDULE OF AMORTIZATION:

<TABLE>
<CAPTION>
<S>   <C>                         <C>
      PAYMENT DATE:               AMOUNT TO BE PAID.
1.-   May the 31st of 2005        $4,166,666.67
2.-   June the 30th of 2005       $4,166,666.67
3.-   July the 31st of 2005       $4,166,666.67
4.-   August the 31st of 2005     $4,166,666.67
5.-   September the 30th of 2005  $4,166,666.67
6.-   October the 31st of 2005    $4,166,666.67
7.-   November the 30th of 2005   $4,166,666.67
8.-   December the 31st of 2005   $4,166,666.67
9.-   January the 31st of 2006    $4,166,666.67
10.-  February the 28th of 2006   $4,166,666.67
11.-  March the 31st of 2006      $4,166,666.67
12.-  April the 30th of 2006      $4,166,666.67
13.-  May the 31st of 2006        $4,166,666.67
14.-  June the 30th of 2006       $4,166,666.67
15.-  July the 31st of 2006       $4,166,666.67
16.-  August the 31st of 2006     $4,166,666.67
17.-  September the 30th of 2006  $4,166,666.67
18.-  October the 31st of 2006    $4,166,666.67
19.-  November the 30th of 2006   $4,166,666.67
20.-  December the 31st of 2006   $4,166,666.67
21.-  January the 31st of 2007    $4,166,666.67
22.-  February the 28th of 2007   $4,166,666.67
23.-  March the 31st of 2007      $4,166,666.67
24.-  April the 30th of 2007      $4,166,666.59
</TABLE>

"SUBSCRIBER" BINDS TO PAY TO "BENEFICIARY", WITHOUT THE NEED OF A PRIOR REQUEST,
AT THE OFFICES OF THE BENEFICIARY LOCATED IN PERIFERICO SUR NUMBER 314, COLONIA
SAN ANGEL TLACOPAC, DEL. ALVARO OBREGON, MEXICO CITY, FEDERAL DISTRICT, A DAILY
INTEREST ON THE UNPAID BALANCES, PAYABLE ON A MONTHLY BASIS ON THE LAST DAY OF
EACH MONTH (INTEREST PERIOD), ACCRUING AS OF THE DATE WHEN THIS INSTRUMENT IS
EXECUTED, TO THE RATE THAT RESULTS FROM ADDING 3.0 (THREE POINTS) TO THE
EQUILIBRIUM INTERBANK INTEREST RATE (E.I.I.R.) TO RECEIVE DEPOSITS, AS INFORMED
BY THE BANK OF MEXICO THROUGH THE DAILY GAZETTE OF THE FEDERATION, TAKING AS
REFERENCE THE RATE IN FORCE ON THE DATE WHEN EACH INTEREST PERIOD BEGINS.

IN CASE THAT, DUE FOR ANY REASON, THE EQUILIBRIUM INTERBANK INTEREST RATE
(EIIR.) IS CEASED TO BE PUBLISHED IN ORDER TO ESTIMATE THE AFOREMENTIONED
INTEREST, THE RATE THAT SUBSTITUTES SUCH RATE SHALL BE APPLIED AND, IF NO SUCH
RATE EXISTS, THEN IT SHALL BE APPLIED RETURN RATE PAID BY THE FEDERAL TREASURY
CERTIFICATES ("CETES") FOR A 28 DAY TERM OFFERED IN A PUBLIC OFFERING BY THE
BANK OF MEXICO IN THE OFFICIAL GAZETTE OF THE FEDERATION AND INFORMED AT THE
BEGINNING OF EACH INTEREST PERIOD. THE ANNUAL RATE SHALL CORRESPOND TO THE
INTEREST OR GROSS RETURN OFFERED HEREUNDER.

THE RATE MAY BE REVIEWED AND ADJUSTED PURSUANT TO THE VARIATIONS THAT THE
ABOVEMENTIONED RATE MAY EXPERIENCE.

IN CASE OF DEFAULT, THE INTEREST RATE SHALL BE THE RATE THAT RESULTS BY
MULTIPLYING THE ORDINARY INTEREST RATE BY 2 (TWO), TAKING AS REFERENCE THE RATE
THAT IS GREATER BETWEEN THE RATE IN FORCE ON THE DATE WHEN THE DEFAULT TAKES
PLACE, AND THE RATE IN FORCE ON THE DATE WHEN THE PERTINENT PAYMENT IS MADE.

THE LACK OF PROMPT PAYMENT OF ANY INSTALLMENT OF INTEREST OR CAPITAL SHALL GIVE
RISE TO THE ACCELERATION OF THIS NEGOTIABLE INSTRUMENT, AND THUS THE BENEFICIARY
MAY IMMEDIATELY DEMAND THE FULL BALANCE OWED PLUS THE ANCILLARY CHARGES.

THIS PROMISSORY NOTE IS DERIVED FROM UNSECURED CREDIT AGREEMENT NUMBER 05CS24,
EXECUTED ON APRIL THE 13TH OF 2005, AND RATIFIED WITH MARIA ESTHER GARCIA
ALVAREZ, COMMERCIAL NOTARY PUBLIC NUMBER 4 FOR THE FEDERAL DISTRICT, AND ITS
CONSTRUCTION AND ENFORCEMENT SHALL BE SUBJECT TO THE LAWS AND TO COURTS WITH
COMPETENT JURISDICTION OF MEXICO CITY, FEDERAL DISTRICT; THE PARTIES EXPRESSLY
WAIVE ANY JURISDICTION THAT MAY CORRESPOND TO THEM PURSUANT TO LAW DUE TO THEIR
TERRITORIAL JURISDICTION.

        MEXICO, FEDERAL DISTRICT, ______________________________________________

                                   SUBSCRIBER
                     MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

                           (Two illegible signatures)
                    ----------------------------------------
                                 REPRESENTED BY:

<PAGE>

                                 DRAWDOWN NOTICE

                  Mexico City, Federal District, on _____________ of
_____________ of 2005.

IXE BANCO, S.A. INSTITUCION DE BANCA MULTIPLE
IXE GRUPO FINANCIERO

DEAR SIRS:

Pursuant to the terms of the Fourth Clause of Unsecured Credit Agreement Number
05cs24, executed on April the 13th of 2005 by and between the undersigned Maxcom
Telecomunicaciones, S.A. de C.V. and Ixe Banco, S.A., Institucion de Banca
Multiple, Ixe Grupo Financiero (hereinafter the "Credit Agreement"), I hereby
inform you of my desire to withdraw the amount of $100,000,000.00 (One Hundred
Million Pesos 00/100 Mexican currency), charged to the Amount of Credit.
Therefore, pursuant to such Credit Agreement, I hereby instruct Ixe Banco to
deposit such amount in checking account number 1154961-0, which I carry in that
Institution.

The amount of the Amount of Credit I hereby instruct to be deposited in the
aforesaid checking account shall be allocated to the Extension of Coverage.

The Surcharge and the Terms of Payment of this drawdown shall be made as
follows:

SURCHARGE: 3.0 (Three Points in Percentage Terms)
TERMS OF PAYMENT: Pursuant to the following payment schedule:

<TABLE>
<S>   <C>                          <C>
1.-   May the 31st of 2005         $4,166,666.67
2.-   June the 30th of 2005        $4,166,666.67
3.-   July the 31st of 2005        $4,166,666.67
4.-   August the 31st of 2005      $4,166,666.67
5.-   September the 30th of 2005   $4,166,666.67
6.-   October the 31st of 2005     $4,166,666.67
7.-   November the 30th of 2005    $4,166,666.67
8.-   December the 31st of 2005    $4,166,666.67
9.-   January the 31st of 2006     $4,166,666.67
10.-  February the 28th of 2006    $4,166,666.67
11.-  March the 31st of 2006       $4,166,666.67
12.-  April the 30th of 2006       $4,166,666.67
13.-  May the 31st of 2006         $4,166,666.67
14.-  June the 30th of 2006        $4,166,666.67
15.-  July the 31st of 2006        $4,166,666.67
16.-  August the 31st of 2006      $4,166,666.67
17.-  September the 30th of 2006   $4,166,666.67
18.-  October the 31st of 2006     $4,166,666.67
19.-  November the 30th of 2006    $4,166,666.67
20.-  December the 31st of 2006    $4,166,666.67
21.-  January the 31st of 2007     $4,166,666.67
22.-  February the 28th of 2007    $4,166,666.67
23.-  March the 31st of 2007       $4,166,666.67
24.-  April the 30th of 2007       $4,166,666.59
</TABLE>

The reception of this notice, jointly with the deposit made by Ixe Banco of the
amount put at the disposition in the aforesaid checking account, shall represent
conclusive evidence of the drawdown of funds under the Credit Agreement, and the
terms and conditions of the Credit Agreement shall apply to the credit drawdown
requested herein.

                                  Respectfully,

                                    BORROWER:
                     Maxcom Telecomunicaciones, S.A. de C.V.

                           (Two illegible signatures)
           -----------------------------------------------------------
           By: Gonzalo Alarcon Iturbide and Jorge Lopez Aguado Jimeno.