New Delhi, Jun 27 (IANS): The total number of subscribers opting for mobile number portability (MNP) has risen to 45.89 million, with Karnataka receiving the maximum number of 5.11 million requests till the end of April, according to official data released Wednesday.

MNP allows users to switch operators while retaining their mobile numbers.

"By the end of April 2012, about 45.89 million 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 Andhra Pradesh and Gujarat where 4.44 million and 4.23 million subscribers opted for the service.

MNP was implemented across the country last January 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.

India currently has over 920 million mobile phone subscribers.