<PAGE>


                          EX-2.D
                          Long-distance Concession

                                                                   

Concession to install, operate and exploit a public telecommunications network,
granted by the Federal Government and through the Ministry of Communications and
Transport, henceforth named the Ministry, in favor of Iusatel, S.A. of C.V.,
henceforth named the Concessionaire in accordance with the following antecedents
and conditions.

                                   ANTECEDENTS

I.    The Concessionaire submitted request before the Ministry, dated 
      September 8, 1995, to obtain a concession to install, operate and 
      exploit a public telecommunications network, in agreement with the 
      principles established by Article 24 of the Federal Law of 
      Telecommunications.

II.   The Ministry, once having assessed and evaluated the documentation
      corresponding to the Concessionaire's request, resolved that the latter
      satisfactorily complied with the requirements demanded by said Law and
      other applicable dispositions. Thus, according to the principles described
      in Articles 36, Fraction III, of the Organic Law of Federal Public
      Administration; 8th. of the Law of General Means of Communication; 11,
      Fraction II, 12, 24, 25, 26 and other ones relative to the Federal Law of
      Telecommunications, the Ministry grants the Concessionaire the present
      concession to install, operate and exploit a public telecommunications
      network, which will be subject to the following:

                                   CONDITIONS

                                  First Chapter
                              General Dispositions

1.    Definitions and extent of the concession.

1.1.  Definition of terms. In addition to definitions contained in the Federal
      Law of Telecommunications, and for the purposes to this Title, it will be
      understood that

      1.1.1. Concession: The one contained in the present Title to install,
             operate and exploit a public telecommunications network,

      1.1.2. Law: The Federal Law of Telecommunications, and

      1.1.3. Network: The public network of telecommunications, object of the
             present Concession.

1.2.  Services. The Concessionaire is obliged to installing, operating and
      exploit-

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      ing the Network, and to rendering the services referred to in the
      attachment(s) to the present Title, in the terms and conditions pointed
      out there. The Concessionaire will be able to render services additional
      to the ones included in the attachment(s) of this Title, with a previous
      authorization from the Ministry. For such a purpose, the Concessionaire
      will have to submit the request, to the satisfaction of the Ministry, and
      it shall fulfill the requirements to Article 24 of the Law and other
      applicable dispositions, excepting the prejudice that, should more
      concessions of bands of frequencies of the radio electric spectrum be
      required, they will be granted by means of the public bidding procedure,
      provided in Article 14, as well as other applicable ones by the Law.

      In order to obtain the authorization mentioned in the above paragraph, the
      Concessionaire's obligations derived from the present Concession shall be
      fully updated and fulfilled.

      In the terms of Article 33 of the Law, the Concessionaire will be able to
      render added-value services, being enough to previously register them
      before the Ministry.

1.3.  Coverage modification. The Concessionaire, in order to enlarge or reduce
      the Network coverage area, will require previous authorization from the
      Ministry.

      The Ministry will grant authorization to the Concessionaire to enlarge or
      reduce the coverage, in a period no longer than 120 natural days, counted
      from the date of receiving the request, as long as the Concessionaire's
      obligations derived from the present Concession are fully updated and
      fulfilled.

1.4.  Duration. This Concession will be valid for 30 years, counting from the
      date of signature of the present Title, and it will be likely to be
      extended in accordance with the terms provided by Article 27 of the Law.

1.5.  Applicable Legislation. The installation, operation and exploitation of
      the Network and services included in the present concession, will be
      subject to the Law, to the Law of General Means of Telecommunications, and
      to the treaties, laws, regulations, decrees, Mexican official norms,
      agreements, circulars and other administrative dispositions issued by the
      Ministry, as well as the conditions established in this Title.

      The Concessionaire accepts that if the legal regulations and
      administrative dispositions -- referred to in the above paragraph -- this
      Concession is subject to were derogated, modified or added to, the
      Concessionaire will be subject to the new legislation and administrative
      dispositions as their putting 

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      them into effect.

1.6.  Other Concessions. The present Concession does not confer exclusivity
      rights to the Concessionaire. Therefore, the Ministry, within the same
      geographic area, will be entitled to grant other concessions in favor of
      third parties to install, operate or exploit one or more public
      telecommunications networks rendering identical of similar services.

1.7.  Cession of Rights. The Concessionaire will be entitled to transfer its
      Rights and Obligations -- either fully or partially -- established in the
      Concession in the terms of Article 35 of the Law.

1.8.  Rendering the Services through subsidiaries or branches. With a previous
      authorization issued by the Ministry, the Concessionaire will be able to
      render the services included in the Concession through subsidiary
      companies or branches. Nevertheless, the Concessionaire -- at all times
      and before the Ministry -- will be responsible for all obligations derived
      from this Concession.

1.9.  Proxies or Warrants. Under no circumstance, whatsoever, will the
      Concessionaire be able to grant proxies or general warrants to exercise
      irrevocable acts of administration or dominion directed towards enabling
      the proxy or warrant to exercise the rights and obligations of the present
      concession.

1.10. Taxes. Whenever the Concessionaire constitutes any tax on the Concession
      or the rights derived from it, the Concessionaire shall carry out the
      registration referred to in Article 64 of the Law, within the 30 natural
      days following the date of its constitution.

      The document where the granted warranty is stated, shall specifically
      establish that the execution of the warranty will, under no circumstance
      whatsoever, grant the character of concessionaire to the creditor.

      In order to have the Concession awarded to a creditor or to a third party,
      it will be necessary that the Ministry authorizes the cession of rights,
      observing the terms stated in Article 35 of the Law or otherwise, to
      obtain the concession in accordance with Article 34 of the same ordinance,
      excluding, in this case, frequency bands of the radio electric spectrum.

1.11. Nationality. The Concessionaire, -- regarding this Concession -- will have
      no more rights than the ones granted to Mexicans. Consequently, the
      partnership and its foreign partners, whenever it is the case, are
      committed to neither requesting nor accepting diplomatic intervention of
      any given foreign country, under the penalty of loosing -- in favor of the
      Mexican Republic -- all the properties and rights acquired to install,
      operate and 

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      exploit the Network.

1.12. Neutral Investment In terms of the Fifth Title of the Law of Foreign
      Investment, neutral investment will not be computed to determine the
      percentage of foreign investment in the subscribed capital of the
      Concessionaire.

1.13. Companies with State participation of foreign countries. It will not be
      considered as shareholding the participation of a government or foreign
      state, the one executed by companies with State participation of foreign
      countries not considered as authorities by the internal legislation of the
      country in question, that have judicial category and patrimony of their
      own.

1.14. Subscription of Shares. The Concessionaire is obliged to present before
      the Ministry, on the 30th of April of every year at the latest, a list of
      its ten main shareholders and their respective participation percentages,
      which will be accompanied with the information determined by the Ministry.

      In the event of any subscription of shares, in an act or succession of
      acts representing ten percent or more of the partnership's working
      capital, the following regulation shall be observed:

      1.14.1. The Concessionaire will notify the Ministry about the intention of
              the interested parties on executing the subscription of shares,
              being necessary to attach the notification to the information
              about the individuals interested in acquiring shares.

      1.14.2. The Ministry will have a period of 90 natural days, counted from
              the date of presentation of the notification, to present its
              objection in a written form and stating the justified cause
              regarding the operation in question, and

      1.14.3. The operation will be considered as approved by the Ministry, if
              said period elapses without objection from the Ministry.

      Only the operations not objected by the Ministry will be able -- if so is
      the case -- to enroll in the registration book of shareholders of partners
      to the moral person, without detriment of the authorizations required from
      other authorities in accordance to applicable dispositions. It will not be
      required to present the notification referred to on the second paragraph
      of this condition, whenever the subscription refers to representative
      shares of neutral investment, or when it is the case of increases of
      capital subscribed by shareholders themselves, as long as the proportion
      of participation of the working capital from each one of them is not
      modified.

      In the event of a party interested in subscribing shares is a moral
      person, in 

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      the notification referred to in condition 1.14.1 above, the necessary
      information will have to be submitted so as to allow the Ministry to know
      the identity of the physical persons having patrimonial interests superior
      to the ten percent of said moral person's capital.

      This condition shall be included within the social statutes, as well as in
      the titles or certificates issued by the Concessionaire.

      1.15. Training and Technological Development. The Concessionaire will
            develop training and instruction programs for its personnel.

            In like manner, the Concessionaire will perform research and
            development activities in the country. For this purpose, it will be
            able to coordinate its activities with the Mexican Institute of
            Communications and with other research and technological development
            institutions.

      1.16. Designation of the technical responsible. The Concessionaire is
            obliged to designate -- before the Ministry -- a person responsible
            for the Network's technical operation, who will count with the
            faculties from the administration, necessary to oblige the
            Concessionaire before the Ministry, regarding the technical
            operation of the same Network.

                                 Second Chapter
                             Dispositions Applicable
                                 to the Services

2.1.  Quality of the services. The Concessionaire will be committed to rendering
      the services included in this Concession in a continuous and efficient
      way, in conformity with the applicable legislation and the technical
      features established in the present Title and its attachments.

      Likewise, the Concessionaire is committed to provide the mechanisms
      necessary to perform repairs on the Network and services' failures, within
      the first eight working hours of receiving the report.

      The Concessionaire will endeavor to render the services included in the
      present Concession in the best conditions of price, diversity and quality
      to benefit the users, in order to promote an efficient development of
      telecommunications. For this purpose, the Concessionaire will submit to
      the Ministry -- within the 120 natural days following the signing of this
      Concession -- the minimum quality standards of the services, without
      detriment to the Ministry issuing general regulations regarding this
      matter.

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2.2.  Service Interruption. In case of interrupting the rendering of some of the
      services during a period longer than 72 consecutive hours, starting from
      the date established in the respective report, the Concessionaire will
      grant its users a discount on the fee corresponding to the duration of the
      interruption.

2.3.  System for handling complaints and repairs. The Concessionaire will
      establish a system for receiving service complaints and failure repairs.

      On a monthly basis, the Concessionaire will produce a report that shall
      include the incidence of failures, classified by their type, actions taken
      and applied discounts. Said report shall be available upon the Ministry's
      request.

      The Ministry will be entitled to make said information public, along with
      other Concessionaires' rendering similar services in the country or in the
      same region.

2.4.  Measuring equipment and quality control. The Concessionaire is obliged to
      take the necessary measures to ensure the precision and reliability of the
      devices used to measure quality and billing systems. For these purposes,
      the Concessionaire will have to carry out periodic testing the equipment,
      and furnish the Ministry, when required, with the results of the tests in
      a quarterly way. And if it is the case, the Concessionaire shall submit
      documents certifying that the pertinent adjustments have been performed.

      In like manner, the Concessionaire shall keep records of measuring
      equipment as determined by the Ministry.

2.5.  Commercial Practices Code. The Concessionaire shall integrate -- in
      conformity with general rules regarding the matter issued by the Ministry
      -- a commercial practices code which shall describe, in a clear and
      concise way, the various services it renders, as well as the methodology
      used to apply the corresponding fees. Once having such code integrated,
      the Concessionaire shall make it available for the public in its
      commercial offices and, upon the Ministry's request, it will publish a
      summary of the code in major newspapers at national level.

2.6.  Emergency Services. The Concessionaire shall put at the Ministry's
      disposal -- within the six months following the issuing of the present
      Title -- an action plan aimed at preventing service interruptions, as well
      as a plan for supplying emergency services in case of fortuitous events.

      In the event of an emergency happening within the coverage area, the
      Concessionaire shall furnish the indispensable services indicated by the
      Ministry, in a free way, only for the time and proportion required by the
      emergency.

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      The Concessionaire shall notify the Ministry about any event liable to
      affect, either generally or significantly, the functioning of the Network.

                                  Third Chapter
                                      Fees

3.1.  Undue Charges; Overpayment. Should the Concessionaire charge the users
      nonregistered fees or fees differing from the ones established, in its
      case, and in conformity with Article 63 of the Law, the Concessionaire
      shall reimburse to users the balance regarding registered or established
      fees.

      The mentioned above must be understood as without prejudice to sanctions
      imposed in conformity with the Law and other applicable dispositions.

3.2.  Prohibition of crossed subsidies. The Ministry shall be able -- at all
      times -- to verify that registered fees do not constitute crossed
      subsidies in terms of Article 62 of the Law. For such purpose, the
      Concessionaire shall provide corresponding information within the 60
      natural days following the date of receiving the Ministry's request.

3.3.  Billing. The Concessionaire's billing system must be previously approved
      by the Ministry.

                                 Fourth Chapter
                          Verification and Information

4.1.  With no detriment to the Ministry's faculties to request other information
      from the Concessionaire, in terms of Article 68 of the Law, the latter
      shall furnish the Ministry, within the 150 (One Hundred Fifty) natural
      days following the closing of the corresponding exercise:

      4.1.1.  Its company's audited financial statements, detailing services,
              and if it is the case, by geographic area.

      4.1.2.  A description of the main fixed assets included in the Network, in
              conformity with the formats established by the Ministry, and

      4.1.3.  A report on actions performed regarding training and instruction
              programs for its staff, as well as a report on its research and
              development activities in the country, as stated in condition 1.15
              of this Concession.

4.2.  The Concessionaire shall inform the Ministry, by means of a quarterly
      report, 

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      about the advancement of the Network's expansion program.

4.3.  The Concessionaire shall put at the disposal of the Ministry, statistic
      information concerning traffic, routing, occupation, performance and other
      operation parameters generated by the Network, in conformity with general
      dispositions issued by the Ministry for this purpose.

                                  Fifth Chapter
                              Warranty of Formality

5.    Guaranty. The Concessionaire shall establish a guaranty within a period no
      longer than 30 natural days counted as of the date of signature of the
      present Concession, with an institution authorized for the amount of
      N$5,000,000.00 New Mexican Pesos (Five Million New Mexican Pesos) issued
      in favor of the "Tesoreria de la Federacion" (Federation's Treasure
      Department), which will be effective if: a) In case of revocation of the
      Concession, and b) It will guarantee the payment of pecuniary sanctions
      imposed by the Ministry. The guaranty will be valid during the period of
      the Concession.

      The amount of the guaranty shall be annually updated, in conformity with
      the "Indice Nacional de Precios al Consumidor" (National Index of Prices
      to the Consumer), or the substituting Index.

      The policy issuing the guaranty shall clearly state that the institution
      issuing the guaranty accepts the concepts contained in Articles 95 and 118
      of the Federal Law of Guaranty Institutions in effect, and the renounce to
      benefit of order and excuse.

                                  Sixth Chapter
                          Jurisdiction and Competition

6.    For all matters relative to the interpretation and complying with the
      present Title of Concession, except for the administrative matters having
      to be solved by the Ministry, the Concessionaire agrees to be submitted to
      the jurisdiction of the federal tribunals of Mexico City, Distrito
      Federal, renouncing to the Law that could correspond to it in function of
      its present or future domicile.

      Mexico, Distrito Federal, October 16, 1995.


                    MINISTRY OF COMMUNICATIONS AND TRANSPORT
                                  THE SECRETARY

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                              CARLOS RUIZ SACRISTAN

                              IUSATEL, S.A. DE C.V.

                                 GUILLERMO AMORE
                              LEGAL REPRESENTATIVE


Attachment A of the Title of Concession to install, operate and exploit a public
telecommunications Network granted by the Federal Government, through the
Ministry of Communications and Transport, in favor of Iusatel, S.A. of C.V.,
dated October 16, 1995.

A.1. Included Services. In the present attachment, the following services are
included:

      A.1.1.  The rendering of any service involving emission, transmission or
              reception of signs, signals, written documents, images, voice,
              sound of information of any kind through its Network.

      A.1.2.  The sale or leasing of Network's capacity for emission,
              transmission, or reception of signs, signals, written documents,
              voice, images, sounds or information of any type.

      A.1.3.  The commercialization of the acquired capacity of other
              concessionaires of public telecommunication networks, with whom
              the Concessionaire might have made the corresponding deals.

      A.1.4.  Rendering the public service of basic long distance telephony,
              either domestic or international. In conformity with the Seventh
              Transitory Article of the Law, the Concessionaire shall be able to
              render the public service of basic long distance telephony,
              starting as of August 11, 1996.

A.2. Services not included. The services not included in this attachment are:

      A.2.1.  The ones that require a concession on frequency bands of radio
              electric spectrum for determined usage.

      A.2.2.  The ones requiring a concession to occupy and exploit orbital
              geo-stationary positions and satellite orbits assigned to the
              country.

      A.2.3.  The ones requiring a concession to operate a radio system or open
              T.V., and

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      A.2.4.  The cable television service.


      In order to be able to render these services, the Concessionaire must
      obtain the concession or the respective authorization.

A.3.  Time limit to initiate the Network's exploitation. The Concessionaire
      shall initiate said exploitation, at the latest, in April 1997.

A.4.  Network's Coverage Commitments. The Concessionaire is obliged to link,
      with its own infrastructure, the following cities, at the latest, the 31st
      of May, 1998:

      Aguascalientes, Aguascalientes 
      Saltillo, Coahuila 
      Torreon, Coahuila
      Durango, Durango 
      Distrito Federal 
      Celaya, Guanajuato 
      Irapuato, Guanajuato 
      Leon, Guanajuato 
      Guadalajara, Jalisco 
      Toluca, Mexico
      Cuernavaca, Morelos 
      Tepic, Nayarit 
      Monterrey, Nuevo Leon 
      Puebla, Puebla 
      Queretaro, Queretaro 
      Mazatlan, Sinaloa 
      Reynosa, Tamaulipas

      In like manner, the Concessionaire is obliged to cover, through its own
      land exchange stations, and using national satellite systems, the
      following cities, at the latest on the 31st of May, 1998:

      Tijuana, Baja California Norte
      Cd.  Juarez, Chihuahua
      Monclova, Coahuila
      Zihuatanejo, Guerrero
      Cancun, Quintana Roo
      Villahermosa, Tabasco
      Nuevo Laredo, Tamaulipas
      Merida, Yucatan

      The Concessionaire is obliged to link -- with its own infrastructure --
      the following cities, at the latest, on the 31st of December, 2000:

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      Matamoros, Tamaulipas
      Cd.  Victoria, Tamaulipas
      Tampico, Tamaulipas
      Poza Rica, Veracruz
      Jalapa, Veracruz
      Veracruz, Veracruz
      Cordoba, Veracruz

      In like manner, the Concessionaire is obliged to cover, through its own
      land exchange stations and utilizing the national satellite systems, the
      following cities, at the latest on the 31st of December, 2000:

      La Paz, Baja California Sur 
      Los Cabos, Baja California Sur 
      Piedras Negras, Coahuila 
      Delicias, Chihuahua 
      Chihuahua, Chihuahua
      Manzanillo, Colima 
      Colima, Colima 
      Lazaro Cardenas, Michoacan 
      Los Mochis, Sinaloa 
      Culiacan, Sinaloa 
      Cd.Obregon, Sonora 
      Hermosillo, Sonora 
      Guaymas, Sonora 
      Coatzacoalcos, Veracruz

A.5.  Network's Technical Specifications. The Concessionaire is obliged to
      install the Network with at least the technical specifications indicated
      in numeral 4.3 of its concession application, which is added to the
      present attachment and is an integral part of this Concession.

A.6.  Coverage of Services. The Concessionaire shall be able to render the
      services included in this Concession, in the locations where the coverage
      has been authorized, with its own infrastructure and at national level,
      using the capacity of other public telecommunication networks. The
      Concessionaire will be able to render services interconnecting its Network
      to foreign networks in terms of Article 47 of the Law.

A.7.  Urban Wiring. In the event that the Concessionaire tried to install wiring
      in urban zones in order to render services included in the present
      attachment to final users, it shall submit the corresponding application
      in terms of condition 1.3 of the present Title, understanding that,
      whenever it comes to direct linkages that do not require bands of
      frequency from the radio electric spectrum, the Ministry will grant a
      convenient resolution, in a time limit of 

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      twenty natural days, counting from the date of receiving said application.

                 Technical Specifications of the Application for
                a Concession on Public Telecommunications Network
                       Submitted by Iusatel, S.A. de C.V.

4.3   Technical Description of "Network's" Project for the first five years.

4.3.1 Transmission

      Transmission systems of "Iusatel's" transport network are based on "SDH".
      The essential architecture of this equipment's operation is distributed in
      the form of physical rings and virtual rings, using topologies of maximum
      reliability and using the different modules defined for said standard.

      The physical rings will be equipped with the highest transmission
      velocities technically available and economically permissible (presently
      622 Mb/s and 2.5 Gigabits per second "Gb/s"), according to the traffic
      requirements of each one of the nodes included in said ring. Virtual
      rings' configurations will allow to avoid conflicts generated by
      limitations defined in the norms, in addition to providing the
      recollection facilities (insertion and extraction) of traffic in low
      capacity nodes not included in the physical ring.

      Redundancy protection, by definition present in an optic fiber ring, will
      be applied in a different way in both rings. Physical rings will use
      shared protection -- "Proteccion Compartida" -- which will permit the
      elevation of total capacity of the ring's transportation. For the case of
      virtual rings, protection will be dedicated -- "Dedicated Protection" --
      if which will facilitate to diminish the configuration costs of
      recollection in low traffic nodes. The redundancy in virtual rings carried
      out through the physical ring's capacity, thus achieving a minimum-cost
      configuration and maximum reliability, taking advantage of the benefits of
      international norms.

      The design basis used for the "Network" are the following:

      o     Synchronous Transport Module-6 ("STM") multiplexors are used for the
            equipping of the high-velocity physical ring.

      o     Virtual rings with "STM" equipment units. Four of them were
            considered in the architecture of the recollecting ring, covering
            areas geographically grouped and entering in the end to the
            high-capacity ring as a back-up mechanism and to close the rings in
            a virtual way.

      o     In the dimensioning of linkages, the commuted and dedicated
            circuits' capacity is included, performing the consolidation
            (Grooming) taking 

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            advantage of the capacities that the "SDH" technology offers in
            insertion and extraction points at the level of "E1" linkages.

      o     The distance between relays for optic fibers was fixed between 70
            and 120 kilometers. and for the cases where optical amplifiers are
            used, distances over 120 kilometers are achieved.

      o     The type of optic fibers to be used, utilizes the latest available
            technologies, among them, the one of Modified Dispersion-Shifted
            Fiber, which involves a higher starting investment, but it creates a
            window of opportunity that prevents technological obsolescence and 
            that will allow, in the future, to increase velocity of transmission
            in the rings, only changing the electronics associated to it.

Optic Fiber

      The means of transportation proposed for the "Network," is essentially
      Optic Fiber. Several types of fiber were considered, according to the
      growth plan and the technical features of the various linkages for the
      integration of the "Network."

      Optic Fibers allow the improvement of communication characteristics,
      reducing times of delay, increasing the capacity of transmission and
      elevating the reliability and altogether, to improve the quality of
      performance of the "Network" itself.

      According to worldwide operation statistics, it is reasonable to consider
      a possibility of breakage per year for every 4000 kilometers in an optic
      fiber cable. Once stated the above, it is possible to anticipate that,
      under normal conditions, the "Iusatel" "Network" will have cuts in its
      fiber cables, which will not affect the service to the user, thanks to the
      mechanism of intrinsic protection in the transmission equipment units
      associated to the ring's architecture.

      A detailed design of linkages of optic fiber was performed considering the
      possibility of migrating transmission equipment units to the next
      transmission hierarchy "STM"-64 and/or using the multiplexing systems of
      wavelength.

      For the design of the "Network," the following requirements and
      engineering norms were established:

      o     The average length of optic fiber's cable coil used in the
            construction of the "Network" is of four kilometers.

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      o     The defined route for the creation of the "Network" considers
            covering as many cities as possible and target markets of higher
            population density.

      o     Since the beginning, there are international linkages of high
            capacity and reliability, in order to offer users an efficient and
            modern telecommunication service in the current environment of
            global markets, particularly for corporate users who require
            flexibility and ubiquity when handling information.

      o     The installation of fiber is based on rings' topologies, as to offer
            as much quality, reliability and redundancy as possible.

      o     Several rights of means are used, such as: electric lines, highways
            and submarine linkages, performing an estimated combination of
            construction time, distance, availability, efficiency and
            reliability regarding linkages.

      It has been considered that rings' growth will evolve simultaneously
      expanding and dividing the existing rings, being able to adapt in a
      flexible way to market's evolution and technology.

      The use of optic fiber, as well as new types of optic fibers of modified
      straight dispersion, that allow growth of capacity and reach by means of
      increasing transmission velocity, the use of multiple wavelengths and
      optic amplification, will be supported on characteristics recommended by
      the "UIT-T" listed as follows:

Straight Dispersion

Optic Characteristics

            Window Operation              1,550 nm.
            Wavelength             1,120 nm.  To 1,350 nm.
            Attenuation            at 1,300 nm. < = 1.0 dB/km.
                                   at 1,550 nm. < = 0.5 dB/km.

                                   at 1,550 nm. 3.5 ps/(nm.-km.)

Chromatic Dispersion

Physical Characteristics

            Modal Camp Diameter    7-8.3 (mu)m + 10%
            Concentricity error    < m1 (mu)m

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            Tolerance of circularity of
              the nucleus and sheathing          < 2%

Environmental Characteristics

            Temperature           -60 at +85(degree)C. ((DELTA)(alpha) 
                                  < = 0.03 dB/km.)

            Humidity              < = 98% ((DELTA)(alpha) < = 1.10 dB/km.)


Modified Straight Dispersion ("MSD-LS")

Optic Characteristic

            Window Operation       1,550 nm.
            Wavelength             (lambda)< = 1,260 nm.
            Attenuation            at 1,310 nm. < = 0.5 dB/km. at 1,550 nm. < =
                                   0.25 dB/km
            Chromatic Dispersion   at 1,545 nm. 1.5 ps/(nm.-km.)

Physical Characteristics

            Modal Camp Diameter    8.4 (mu)m +/- 0.5 (mu)m
            Sheathing (coating) 
            Diameter               125 (mu)m +/- 1.0%
            Concentricity Error                 < = 1 (mu)m
            Tolerance of Circularity of the
              nucleus and sheathing (coating)   < = 1.0%

Environmental Characteristics

            Temperature       -60 at +85(degree)C ((DELTA)(alpha) 
                              < = 0.05 dB/km)

            Humidity          < = 98% ((DELTA)(alpha) < = 0.05 dB/km).

Modified Straight Dispersion ("True Wave")

Optical Characteristics

            Operation Window              1,550 nm.
            Wavelength             (lambda)< = 1,260 nm.
            Attenuation            at 1,550 nm. < = 0.22 - 0.25 dB/km.
            Chromatic Dispersion   at 1,545 nm. 1.5 ps/(nm.-km.)

Physical Characteristics

            Modal Camp Diameter    8.4 (mu)m. +/- 0.5 (mu)m.

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            Sheathing (coating) Diameter        125 (mu)m. +/- 1.0%
            Concentricity Error                         < = 1 (mu)m.
            Tolerance of Circularity of the
              nucleus and sheathing (coating)           < 1.0%

Environmental Characteristics

            Temperature      -60 at +85(degree)C ((DELTA)(alpha)  
                              < = 0.05 dB/km.)

            Humidity         < = 98% ((DELTA)(alpha) < = 0.05 dB/km.).

Normal Dispersion.

Optical Characteristic.

            Operation Window              1,300 nm.
            Wavelength             1,270 nm. < = (lambda),
            Attenuation            at 1,300 nm. < = 1.0 dB/km.
                                    at 1,550 nm. < = dB/km.
            Chromatic Dispersion   at 1,300 nm. 3.2 ps/(nm.-km.)
                                     at 1,550 nm. 19 ps/(nm.-km.)

Physical Characteristic.

            Modal Camp Diameter                 9.10 (mu)m. +/- 10%
            Sheathing Diameter (coating)        125 (mu)m +/- 2.4%
            Concentricity Error                             < = 1 (mu)m
            Tolerance of Circularity in
            nucleus and sheathing (coating)                 < 2%

            4.3.2 Commuting and signaling

            The "Iusatel" "Network" will count with an intelligent and open
            architecture ("UIT-T", Q. 1200 and associated ones) and will supply
            in an efficient, simple and fast manner, the design, implantation
            and operation startup of new services demanded by the market. The
            intelligent network "Iusatel" will by constituted by the following
            functional groups:

                  "SPP"       Point of Service Commuting
                  "STP"       Point of Signaling Transference
                  "SCP"       Point of Service Control
                  "IP"        Intelligent Peripheral

            Every Long Distance Exchange Station inside the "Network" will have
            the 

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            "SPP" functionality. This means each exchange station will have the
            capacity for commuting services by means of different types of
            procedures in a way that enables the rendering of the necessary
            resources needed to complete the user's service. The "SPP" will have
            the capacity of interoperating with other functional groups like the
            "STP" and "IP." The interaction of said functional groups will be
            carried out by means of the signaling protocols "SS7," specified in
            Mexican Norms in progress in the "Part of Messages' Transference"
            ("PTM"), "PUSI," Part of Control of the Signaling Connection"
            ("PCCS") and Part of Application of Transactional Capacities
            ("PACT").

            The "Iusatel" "Network" will have two "STP" supply the routing of
            signaling messages among the various functional groups from the
            "Network" itself and other networks. Two "STP" were considered to
            provide redundancy in the signaling paths, in order to be able to
            have a better degree of availability in the "Network."

            Information about our users and associated services is found
            included in the "SCP" functional group. The "SPP" will request "SCP"
            for information related to the service, the "SCP" will reply with
            the relevant information to "SCP," using the signaling network.

            The "Iusatel" "Network" will initiate with two exchange stations;
            one in Mexico City and the other one in Monterrey. Capacities of
            nominal commuting of exchange stations will be of 800,000 attempts
            of calls in peak hours, and a handling of 60,000 ports. Commuting
            equipment units will have redundancy in a great part of their
            subsystems, as well as commuting matrix without block. In these
            exchange stations, there will be detailed registration functionality
            of calls that include information about the user, origin,
            subscribers who pay, operator attention, etc.

            Exchange stations will have the capacity of rendering information
            for networks' administration according to international standards.
            In addition, every station will have an operation, maintenance and
            administration center which will work nonstop, 24 hours a day,
            year-round.

            Commuting equipment units will have the capacity to operate with the
            user's signaling norms: R2 Mexican and Q.931 of the "UIT-T" (for
            Primary Access to the Digital Network of Integrated Services
            ("RDSI"), "PUSI," "PACT," "PCCS" and "PTM" to be interconnected with
            other elements inside and outside of the "Network" according to
            Official Mexican Norms.

            The "Iusatel" "Network" will have a central of operators in Mexico
            City, to be able to route traffic of calls requiring this service.

            All of the above, according to design standards mentioned as
            follows:

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            o     The point of concentration of traffic to be commuted coming
                  from every city or interconnection point, is based in a
                  minimum distance algorithm.

            o     Commuting capacities were calculated considering 50% of
                  answered calls (due to several causes attributed to networks
                  of destination of calls as: users of destination occupied,
                  user of destination who does not answer, abandoned dialing,
                  etc.).

            o     The average time of a domestic Long Distance Call is four
                  minutes and international ones of six minutes, according to
                  current behavior of telephone users in Mexico.

            o     The Degree of Service in the internal transmission network
                  will have a blocking of less than 1% in the average of the
                  thirty most used peak hours of the year, superior to
                  requirements of applicable "UIT-T" international norms.

            The operators' center has been designed to handle 95% of all calls
            in less than ten seconds.

            4.3.3 Synchronization

            The "Network" will have primary reference clocks in the D.F.
            (Federal District, Mexico City) and Monterrey, with reference of
            Global Position System ("GSP"), which complies with recommendation
            G.811 of the "UIT-T."

            Transit clocks comply with Recommendation G.812 of the "UIT-T,"
            requirements of temporization in the outlets of subordinated clocks
            adequate for the plesiochronal exploitation of international digital
            linkages.

            The synchronization network will use facilities of the "SDH"
            network, which complies with recommendation G.803 of the "UIT-T,"
            that offers the capacity of transport of reference signals of the
            high quality clock through the "Network," also counting with
            improvements for tracing, recuperation of failures and delivering of
            synchrony signal.

            The "Network" complies with the objectives in matter of slipping of
            an international connection of the "RDSI," as pointed out in
            Recommendation G.821.

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                 Summary of Annexes to Long Distance Concession

A.    Annex A

Services Required to be Provided By Iusatel:

Services involving the emission, transmission or reception of signs, signals,
written documents, images, voice, sound or information of any kind through its
network, the sale or leasing of the network capacity therefor, the
commercialization of acquired capacity of other concessionaires, and the
provision of public long distance telephony.

Iusatel shall have the right to render such services in the locations where its
coverage has been authorized with its own infrastructure and on a national level
using the capacity of other public telecommunications networks.

Time Limit to Initiate Network Exploitation:  No later than April 1997.

Coverage Commitments:

Iusatel must link with its own infrastructure the following 17 cities no later
than May 31, 1998: Aguascalientes, Saltillo, Torreon, Durango, Distrito Federal,
Celaya, Irapuato, Leon, Guadalajara, Toluca, Cuernavaca, Tepic, Monterrey,
Puebla, Queretaro, Mazatlan and Reynosa.

Iusatel must cover via its own earth stations and using national satelite 
systems the following 8 cities no later than May 31, 1998: Tijuana, Ciudad 
Juarez, Monclova, Zihuatenejo, Cancun, Villahermosa, Nuevo Laredo and Merida.

Iusatel must link with its own infrastructure the following 7 cities no later
than December 31, 2000: Matamoros, Ciudad Victoria, Tampico, Poza Rica, Jalapa,
Veracruz, Cordoba.

Iusatel must cover via its own earth stations and using national satelite 
systems the following 15 cities no later than December 31, 2000: La Paz, 
Los Cabos, Piedras Negras, Delicias, Chihuahua, Manzanillo, Colima, Lazaro 
Cardenas Los Mochis, Culiacan, Ciudad Obregon, Hermosillo, Guaymas, Nogales and
Coatzacoalcos.

B.    Technical Specifications:

Transmission. The transmission systems should be based on "SDH". The fundamental
operational architecture of this equipment will be distributed in the form of
physical and virtual rings. The physical rings will be equipped with the highest
transmission velocities technically available and economically justifiable. The

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virtual rings will be configured to permit the avoidance of conflicts, provide
the facilities of recollection (insertion and extraction) of traffic in the low
capacity nodes not included in the physical ring and provide redundancy
protection.

Transport/Fiber Optics. The means of transport for the network is fundamentally
fiber optic.

Switching and Signaling. Iusatel's network should have an open and intelligent
architecture. Every long distance central office within the Network shall have
SSP functionality, which should have the capacity to interoperate with other
functional groups. The interaction of these functional groups will be
accomplished through signaling protocol SS7. The network will begin with two
central offices, one in Mexico City and one in Monterrey.

Switching equipment will have the capacity to operate with signaling norms of
the user. The point of concentration of switched traffic for each city or point
of interconnection will be based on an algorithm of minimum distance.

Synchronization. The Network will count on reference clocks primarily in Mexico
City and Monterrey with reference to the Global Positioning System.