Oi, formerly known as Telemar, is the largest telecommunications company in Brazil and South America, both in terms of subscribers and revenues. It is headquartered in Rio de Janeiro. Oi's major subsidiaries include Telemar and Brasil Telecom.At the end of 2013 Oi had 74.5 million subscribers, including 16.9 million for landline, 50.3 million for wireless, 5.3 million for ADSL, and 1 million for other services.In 2013, Oi announced its merger with Portugal Telecom, the largest telecommunication company in Portugal, in order to strengthen the Brazilian firm and simplify its ownership structure. In June 2015 Portugal Telecom was acquired by Altice Group.Corporate governanceOi's chief executive officer (as of October 2014) is Bayard Gontijo, who also serves as the company's chief financial officer and director of investor relations.HistoryOi was formed as Tele Norte Leste to merge sixteen state-owned incumbent local exchange carriers, during the privatization of Brazilian telecommunications system. Each carrier served a particular Brazilian state in the northern, northeastern and southeastern part of the country. In the break-up of Telebras in 1998 it was sold to a consortium led by the Brazilian construction firm Andrade Gutierrez and Inepar Holdings as well as other Brazilian corporate and individual investors. The consortium paid 3.434 billion reais.