Accelerating the adoption of Voice over LTE or VoLTE networks in the country, Airtel announced the launch of its VoLTE services across the rest of Maharashtra and Goa. The fast network support will be available only through Airtel 4G SIM.
The company announced that Airtel customers using 4G SIM in the said regions will be able to make calls using Airtel VoLTE and there will be no additional charges for VoLTE. Calls will be billed as per your existing plan or recharge packs.
Although Airtel VoLTE uses 4G network, in case there is non-availability, it automatically switches back to 3G or 2G network. The new network compatibility will also allow customers to continue with their data sessions at 4G speeds while the call is in progress.
If you are an Airtel user, you can upgrade to VoLTE by first checking if your smartphone is compatible with the newer network. You can visit www.airtel.in/volte and check if your phone is listed under supported devices. Airtel has tested and certified particular device models for VoLTE compatibility. 
If your device is compatible, you will further need to update it to the latest operating system to ensure the latest version supports VoLTE. To update the device software, head to settings and check for software update. Lastly, ensure you have an Airtel 4G SIM.
If you are not using a 4G SIM, you can visit an Airtel store and upgrade it. You can then enable VoLTE by following the instructions provided on Airtel’s website. It is to be noted that dual-SIM handset users will have to inset their 4G SIM in the data SIM slot or slot 1, and set the network mode to ’4G/3G/2G (Auto)’.
Compatible Airtel VoLTE phones include iPhone SE, iPhone 6 and later, Samsung Galaxy A5, A7, A8, A9 Pro, J2 2016, J2 Pro, J7 2015, J7 2016, J7 Prime, J7 Nxt, On 8, On Nxt, Oppo F3, F3 plus and A71, Gionee A1, A1 Lite, X1, X1S, Lava Z series, and Vivo Y55L and Y66. 
The announcement comes on the heels of Airtel’s merger with Tata. Under the merger, Airtel is also said to assume a small portion of spectrum in 1800, 2100 and 850 MHz bands that are suited for 4G connectivity. Although the two companies have entered into an understanding, the acquisition of the mobile businesses by Airtel is pending regulatory approvals.