1 pointGuys sorry to say but you are all going about it slightly off direction. Having all supported lte bands unlocked and volte feature enabled in your phone is simply not enough. VOLTE works only and only on devices that the carrier explicitly supports. Your imported handsets are unlocked but model numbers would never match on your Indian carrier. You can benefit from LTE data and jio4gvoice app. Sent from my MI 5 using Tapatalk
1 pointLE2 pro X620 supports cdma voice call as I experienced but could not get full speed data in EVDO.
1 pointI suggest doing iTunes restore to latest version. I checked in two other i devices but it worked for me.