India’s mobile operators today have launched national mobile number portability (MNP) to meet the government’s deadline for offering the service, which allows customers to keep their existing mobile numbers when they move to another region.

The country has had MNP within regions since 2011.

India is divided into 22 telecoms service areas or circles, which generally match its state borders. Rajan Mathews, director general of the Cellular Operators Association of India, told the Economic Times that putting everything together has involved a major effort.

“It has been a very complex exercise with 500,000 towers and switches, two MNP providers and mobile operators, but we’re ready now,” he said.

Last November the Department of Telecommunications approved the recommendation by the Telecom Regulatory Authority of India (TRAI) for national MNP to be rolled out by 3 May. But the deadline was extended two months to allow time for changes in the national numbering plan.

TRAI said more than 157 million subscribers have ported to other operators within the same region as of April.

Market leader Airtel said it can process requests to port numbers within its network within 24 hours, while Idea Cellular has started a toll free call service to facilitate seamless porting to its network.

Sistema Shyam TeleServices (MTS) said in a statement that it is fully geared up to comply with the deadline. “The move will enable MTS India to quickly and efficiently process all number portability requests.”