MNP allows users to switch operators while retaining their mobile numbers.
"By the end of May 2012, about 50.16 million subscribers have submitted their requests to different service providers for porting their mobile number," a Telecom Regulatory Authority of India (TRAI) report said Wednesday.
Karnataka was followed by Andhra Pradesh and Rajasthan where 4.8 million and 4.6 million subscribers opted for change of service provider while retaining the mobile telephone number.
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 filled with the new service provider mentioning the code for transferring the connection.
India currently has over 929 million mobile phone subscribers.
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