The nationwide rollout of MNP service, formally inaugurated by Indian Prime Minister Manmohan Singh, would also help subscribers — if the Indian government cancels the license of their operator for delaying its rollout and missing the 2G-rollout obligations — switch over to another operator.

“I think its a great step forward for the consumer, as it enhances choice and brings in more competition, because the more efficient you are as a service provider, the more likely that consumers will choose you,” said Telecom Minister Kapil Sibal.

The portability facility, that was first launched in the Indian state of Haryana in November last year on a pilot basis, would be available to both postpaid and prepaid customers and subscribers of GSM as well as CDMA service. However, consumers will have to remain with the new operator for three months before moving on.

The other restriction is that the portability facility will be available only within a given licensed service area. In other words, subscribers cannot take their Delhi number to an operator in Mumbai. They can only change their operator within Delhi.

Switching from one network to another while keeping the same number is pretty straightforward: All customers have to do is send an SMS with their mobile number to 1900 (SMS PORT 1900) to get their unique porting code. After this, the process is essentially the same as getting a new connection.

The cost of porting a number to a new operator is Rs19, with the maximum porting time capped at 7 working days by Telecom Regulatory Authority of India (TRAI), except in Jammu and Kashmir, Assam and North East service areas, where it will be 15 working days.

Indian authorities have advised the telecom operator to inform the customer through the phone about the exact date and time when the porting will happen.

Network providers are eager to lure customers from rival companies but also fearful of losing their own. Some of them — like Idea Cellular, Tata Docomo, Vodafone and Aircel — started marketing their portability services to subscribers even before MNP services were rolled out.

MTS, yet another telecom player in India, on Thursday rolled out a slew of offers, including subsidizing handsets for migrating GSM and CDMA customers. More operators are expected to undertake similar activities to retain their subscribers.

The mobile number portability service was mooted over two years ago and was planned to be implemented by the end of 2009. However, implementation had to be deferred several times owing to reasons ranging from lack of preparedness of operators to delay in appointment of an agency to oversee MNP execution.