About 180.59 lakh (18.1 million) mobile phone subscribers have opted for mobile number portability (MNP) with Gujarat receiving the maximum number of 17.63 lakh requests till the end of August, according to official data released on Thursday.
MNP allows users to switch operators while retaining their mobile numbers.
"Mobile Number Portability requests increased from 155.48 lakh subscribers at the end of July 2011 to 180.59 lakh subscribers at the end of August 2011," the Telecom Regulatory Authority of India (TRAI) said in a statement.
"In the month of August 2011 alone, 25.12 lakh requests have been made for MNP," it added.
Gujarat was followed by Maharashtra and Karnataka where 14.77 lakh and 14 lakh customers, respectively, requested for the service.
MNP was implemented across the country in January 20 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.