Exhibit 8.1

Significant Subsidiaries

The following table sets forth our significant subsidiaries as of the date
of this annual report. Our subsidiary Embratel also owns a 35.3% interest in Net, a provider of cable television, local telephone services and broadband Internet access services in Brazil, which we account for under the equity method.



|                                                           |  |                              |  |                                          |  |                                                                                                                          
|---------------------------------------------------------- |  | ---------------------------- |  | ---------------------------------------- |  | -------------------------------------------------------------------------------------------------------------------------
|Name of Company                                            |  | Jurisdiction ofestablishment |  | Percentageof ownershipand votinginterest |  | Description                                                                                                              
|Controladora de Servicios Telecomunicaciones, S.A. de C.V. |  | Mexico                       |  | 100.0%                                   |  | Intermediate holding company                                                                                             
|                                                           |  |                              | 
|Anuncios en Directorios, S.A. de C.V.                      |  | Mexico                       |  | 100.0                                    |  | Producer of yellow and white pages directories in Mexico                                                                 
|                                                           |  |                              | 
|Sección Amarilla USA, LLC                                  |  | Delaware                     |  | 80.0                                     |  | Producer of Spanish-language yellow pages directories in the United States                                               
|                                                           |  |                              | 
|Embratel Participações S.A.                                |  | Brazil                       |  | 98.0                                     |  | Intermediate holding company of domestic and international long distance, local and data services providers in Brazil    
|                                                           |  |                              | 
|Empresa Brasileira de Telecomunicações S.A.  EMBRATEL     |  | Brazil                       |  | 97.2(1)                                  |  | Provider of domestic and international long distance, local and data services in Brazil                                  
|                                                           |  |                              | 
|Star One S.A.                                              |  | Brazil                       |  | 77.8(1)                                  |  | Provider of satellite services in Brazil                                                                                 
|                                                           |  |                              | 
|PrimeSys Soluções Empresariais S.A.                        |  | Brazil                       |  | 97.2(1)                                  |  | Provider of high level value-added services, such as net integration and outsourcing                                     
|                                                           |  |                              | 
|Telmex do Brasil Ltda.                                     |  | Brazil                       |  | 98.0(1)                                  |  | Provider of telecommunications services to corporate customers in Brazil                                                 
|                                                           |  |                              | 
|Metrored Holdings S.R.L.                                   |  | Argentina                    |  | 95.7                                     |  | Intermediate holding company of providers of telecommunications services in Argentina                                    
|                                                           |  |                              | 
|Telmex Argentina S.A.                                      |  | Argentina                    |  | 96.4                                     |  | Provider of telecommunications services to corporate customers in Argentina                                              
|                                                           |  |                              | 
|Ertach S.A.                                                |  | Argentina                    |  | 96.8                                     |  | Provider of Internet access, and data and voice services in Argentina                                                    
|                                                           |  |                              | 
|Telmex Chile Holding, S.A.                                 |  | Chile                        |  | 100.0                                    |  | Intermediate holding company in Chile                                                                                    
|                                                           |  |                              | 
|Telmex Corp. S.A.                                          |  | Chile                        |  | 99.7                                     |  | Intermediate holding company whose subsidiaries provide long distance, Internet access and data network services in Chile
|                                                           |  |                              | 
|Telmex TV S.A.                                             |  | Chile                        |  | 100.0                                    |  | Provider of satellite television and Internet access services in Chile                                                   
|                                                           |  |                              | 
|Telmex Colombia S.A.                                       |  | Colombia                     |  | 100.0                                    |  | Provider of telecommunications services to corporate customers in Colombia                                               
|                                                           |  |                              | 
|Superview Telecomunicaciones, S.A.                         |  | Colombia                     |  | 99.6                                     |  | Cable television provider in Colombia                                                                                    
|                                                           |  |                              | 
|Telmex Hogar, S.A.                                         |  | Colombia                     |  | 100.0                                    |  | Provider of cable television and Internet services in Colombia                                                           
|                                                           |  |                              | 
|Network and Operation S.A.                                 |  | Colombia                     |  | 100.0                                    |  | Provider of cable television and Internet services in Colombia                                                           
|                                                           |  |                              | 
|The Now Operation S.A.                                     |  | Colombia                     |  | 100.0                                    |  | Editor of cable television programming magazine in Colombia                                                              



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|                          |  |                              |  |                                          |  |                                                                       
|------------------------- |  | ---------------------------- |  | ---------------------------------------- |  | ----------------------------------------------------------------------
|Name of Company           |  | Jurisdiction ofestablishment |  | Percentageof ownershipand votinginterest |  | Description                                                           
|Megacanales S.A.          |  | Colombia                     |  | 100.0                                    |  | Producer of cable television content                                  
|                          |  |                              | 
|Cablecaribe S.A.          |  | Colombia                     |  | 100.0                                    |  | Provider of cable television and Internet services in Colombia        
|                          |  |                              | 
|New Dinamic Company, S.A. |  | Colombia                     |  | 100.0                                    |  | Provider of cable television and Internet services in Colombia        
|                          |  |                              | 
|Telmex Perú S.A.          |  | Peru                         |  | 100.0                                    |  | Provider of telecommunications services to corporate customers in Peru
|                          |  |                              | 
|Ecuadortelecom, S.A.      |  | Ecuador                      |  | 100.0                                    |  | Provider of telecommunications services in Ecuador                    



|(1) | Indirect interest held through Embratel Participações S.A.
|--- | ----------------------------------------------------------



2