^^^ nahi Airtel 4G te possible hai calls
you would be able to make calls and send/receive sms. as soon as you initiate/receive call there will be automatic network fall-back from 4g to 3g/2g to take the voice calls, once you are done with the call you will automatically latch on to 4g network.
but if u select 4g only option no call is possible. if u keep switching network option. battery consumption will be more. call is made from 3/2g network 4g toon nahin.more