Telecoms group Altice's plan to buy the Portuguese operations of Brazil's Oi for 7.4 billion euros depends on winning the backing of shareholders in Portugal Telecom SGPS, the holding company which owns 25.6 percent of Oi, a spokesman for Portugal Telecom said. Lisbon-listed Portugal Telecom SGPS is the target of a 1.2 billion-euro takeover offer by Angolan billionaire businesswoman and opponent of the Oi sale, Isabel dos Santos.