In a move that could trigger another tariff war among mobile operators, Anil Ambani-led Reliance Communication on Sunday launched GSM services in Mumbai and offered free talk-time worth Rs 900 spread over three months. "New subscribers would get Rs 10 talk-time every day for the first 90 days and has offered tariffs of Re one a minute for local calls and STD would cost Rs 1.50 per minute on any network," Dinesh Gulati, head of Western region, said.