https://www.airtel.in/volte/ to check VOLTE Compatible Handsets.Airtel : We would like to inform you that, your handset (Asus I001DE) is not enrolled for VOLTE service.Firmware version of ASUS ROG Phone II (ZS660KL) is WW-16.0631.1910.44_0
Thanks Shubhojit.Thanks Put your sim in one of the supported handsets from airtel.in/volte then call customer care about volte not available once you see volte in the supported device remove it from that device and put that in your device .Tried wit...