Actor and brand ambassador of Idea Cellular Abhishek Bachchan addresses a press conference at the launch of the company's Global System for Mobile service in Kolkata, West Bengal, on Tuesday. Aditya Birla telecom firm Idea Cellular has launched its GSM mobile services in Kolkata Metro and West Bengal from today, becoming a pan-India operator with 98 per cent coverage of the telephony potential of the country. AP