BT's nearly $4 billion investment in fiber optics has started paying off for the British carrier, which reported today that it has added 424,000 branded subscribers in the past year. BT also gained 40,000 pay-TV subscribers in its fiscal fourth quarter. On Thursday, BT said it would launch new sports channels and provide a tier of three sports services free to those who take broadband service. "BT has effectively declared war in the U.K. triple-play market. ... In our view, this is a game-changer," said analyst Barry Zeitoune.