The finance ministry has asked the Department of Telecom (DoT) to submit a roadmap and timeline for implementation of 'one nation-free roaming', which allows mobile phone subscribers to use same number across country without having to pay extra charges.

"DoT has been requested to indicate the roadmap and timeline for implementation of the decision regarding 'one nation-free roaming' to this department at the earliest," a source said.

The finance ministry had asked for the details last month only but DoT has still not replied.

However, DoT secretary R Chandrashekhar told PTI that the process for free roaming across the country has already been started and it may be implemented by next year.

He said the department is right now working on the unified licence (UL) guidelines which was also a part of the NTP 2012. After the finalisation of UL and the auction process gets over, the 'one nation-free roaming' will also be implemented in due time.

"All these things are inter-related. We have initiated the process and its implementation is likely next year," Chandrashekhar said.

While releasing the National Telecom Policy (NTP) 2012, telecom minister Kapil Sibal had said, "Target is one nation full mobile number portability and work towards one nation free roaming".

After NTP 2012 was notified, DoT was to start the process to implement full mobile number portability allowing users to retain their existing number at the time of changing their service providers across any state in the country.