About 292.4 lakh (29.24 million) mobile phone subscribers have opted for mobile number portability (MNP) with Karnataka receiving the maximum number of 2.83 million requests till the end of December, according to official data released on Monday.
MNP allows users to switch operators while retaining their mobile numbers.
"By the end of December 2011 about 292.40 lakh subscribers have submitted their requests to different service providers for porting their mobile number," the Telecom Regulatory Authority of India (TRAI) said in a statement.
Karnataka was followed by Gujarat and Andhra Pradesh where 2.77 million and 2.69 million customers, respectively, requested for the service.
MNP was implemented across the country in Jan 20 last year while the pilot launch of the service took place in Haryana Nov 25, 2010.
To opt for MNP, a customer has to pay a maximum of Rs.19 to the new operator for 'porting' the number and remain 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.