Oi (IPA: ['oj], Portuguese for "Hi"), formerly known as Telemar, is the largest fixed telephone operator and the fourth mobile
telephone operator in Brazil, being the third largest telecommunication company in Latin America. It is headquartered in
Rio de Janeiro. Oi's major subsidiaries include Telemar and Brasil Telecom.
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.
On June 20, 2016, Oi filed for a US$19 billion (R$65 billion) bankruptcy protection, the largest on record for Brazil.
In March 2017, Oi had 63 million revenue generating units (UGRs), including 40 million for personal mobile service,
16.3 million for landline, 6.5 million for B2B (large corporations and microentrepreneurs).
Nowadays, it has 2 million hotspots to Oi WIFI network around Brazil.
In March 2019, Oi reported a fourth-quarter net loss of 3.359 billion reais ($858 million),
widening 66 percent from its year-earlier loss. Total revenue fell 7.9 percent.