Telecom operator Bharti Airtel has said the National Company Law Tribunal (NCLT) has approved its merger with loss-making telecom firm Tata Teleservices. As part of the agreement, the Sunil Mittal-led company will absorb Tata consumer mobile business operations in 19 telecom circles. It will also assume a small portion of the unpaid spectrum liability of Tata towards the telecom department.