About 258 lakh (25.8 million) mobile phone subscribers opted for mobile number portability (MNP) till November 2011, with Gujarat receiving the maximum number of requests (2.49 million), according to official data released on Monday.
MNP allows users to switch operators while retaining their mobile numbers.
"By the end of November 2011, about 258.37 lakh subscribers submitted their requests to different service providers for porting their mobile number," the Telecom Regulatory Authority of India (Trai) said in a statement.
Gujarat was followed by Karnataka and Andhra Pradesh, where 2.29 million and 2.27 million customers, respectively, requested for the service.
MNP was implemented across the country on January 20, 2011, while the pilot launch of the service took place in Haryana on November 25, 2010.
To opt for MNP, a customer has to pay a maximum of Rs 19 to the new operator for 'porting' the number, the only condition being that the customer will then have to stay with the new operator for at least three months.
The customer has to send an SMS from the existing phone to 1900. A unique porting code is sent by the existing provider. An application then has to be filed with the new service provider mentioning the code for transferring the connection.