Telecom operators were supposed to roll out nationwide MNP in May. However, due to the technical challenges faced by telecom operators, the deadline of May 3 was extended by two months by Department of Telecom (DoT). According to COAI, the telecom industry body, telecom operators needed 8 weeks to make some technical changes to their networks due to changes in national numbering plan (NNP), resulting in delay.
Ajai Puri, Director, Market Operations, Bharti Airtel, said
 
With our complete readiness to launch National Mobile Number Portability, we aim to empower customers enabling them to retain this identity as they move across anywhere in the country. To facilitate a seamless transition we will also allow our customers to enjoy free incoming on roaming while their number portability request is being processed.
Now that Airtel and Vodafone have implemented full MNP, subscribers will be able to switch to the same or different network in a different state while retaining the same mobile number. Airtel promises that the porting request will take effect in 24 hours, which is fast when compared to the 8 days it usually takes.
To make the MNP process even more smooth, Airtel customers will enjoy free incoming on roaming while their request is processed and can transfer their prepaid balance & carry forward postpaid unbilled/billed amount. The process for national MNP will be the same as intra-city MNP.