( VIVO4; NYSE: VIV) is the largest mobile phone service provider in Brazil and in South America with over 28 million users. It originated from the merger of several Brazilian mobile phone operations under a joint-venture owned equally by Portuguese Portugal Telecom and Spanish Telefónica. Most of its network is IS-95/cdmaOne based, although there are parts of it which are still analog AMPS and parts (resulting from acquisition of other companies) which are TDMA (IS-136) based. The network is being gradually converted to CDMA2000.In 2006, after years being the only CDMA network, Vivo announced a GSM network, and that it would operate in both CDMA and GSM^[1].

The Vivo brand was launched on April 13th 2003. Until 2006, the group was composed of six holding companies which, as announced in November 2005, merged into a single holding company, Vivo Participações S.A.. The operation was concluded on February 22nd 2006.

 Merged companies

The following operators merged to form Vivo:

Portugal Telecom-owned

• Telesp Celular (São Paulo)
• Global Telecom (Paraná, Santa Catarina)

Telefónica-owned

• Telefónica Celular (Rio de Janeiro, Espírito Santo, Rio Grande do Sul)
• Telebahia Celular (Bahia)
• Telergipe Celular (Sergipe)

Acquired by the joint venture

• NBT (Amazonas, Roraima, Pará, Amapá, Maranhão)
• TCO Celular (Goiás, the Brazilian Federal District, Acre, Tocantins, Mato Grosso, Mato Grosso do Sul)