Telemar is the largest telephone company in Brazil, considering both lines in service and revenues. It is owned by local investors since its inception, in July 1998.

Telemar was formed by the merger of sixteen state-owned incumbent local exchange carriers (ILECs), during the privatization of Brazilian telecommunications system. Initially, Telemar was allowed to offer only local voice and data services and interstate long distance voice services. Today, Telemar and its subsidiaries offer local, long distance and international voice and data services, besides a growing mobile phone network.

Currently Telemar has 15.2 million land lines in service, 5.7 million wireless costumers (through its subsidiary, Oi), 0.4 million ADSL subscribers, and about 38 thousand employees.

The states that it provides service to include: Rio de Janeiro, Minas Gerais, Espírito Santo, Bahia, Sergipe, Alagoas, Pernambuco, Paraíba, Rio Grande do Norte, Piauí, Ceará, Maranhão, Pará, Amazonas, Amapá e Roraima, corresponding to 65% of Brazilian's territory and 20 million households.