VOLTE in XR

Hello there.

Purchased iphone XR around a month back. Everything is fine but I’ve been facing this LTE reception issue. Through out the day,multiple times I get this no signal sign and it reverts to normal the next instant. Thought it to be the carrier problem. Contacted them. Turns out it is not their issue. I am from India and using Jio 4g as e-sim. Is this a software issue with Apple?I really hope it is not a hardware problem. Coughing up 749$ for poor hardware isn’t really affordable for me.