Airtel — voice breaking during call

I have been using airtel since quite some time and was pretty happy with the speed and call quality that was provided. But since i bought my new 4g phone which is 2weeks ago i am facing high noise in the call. The person on other side is is able to listen to my voice but i barely can figure out what they are saying. The voice comes intermittently and call cuts of all of a sudden without my intervention. If i use whatsapp call then the problem persists and it reconnects again and again. I simply is 4g airtel sim and this network quality issue is greatly affecting my everyday life.