The voice clarity is awesome in Airtel. I have been using Airtel mobile for last 11 years and I haven't come across any call drops so far. The 4G is good, not bad. I won't give 5 stars to the speed, because I don't find any difference between 3G and 4G at all. Moreover, I don't get 4G signal on my mobile all the time. Most of the times, it is 3G. It displays 'H' or 'H+' on the screen most of the times. But when compared with other mobile service providers, it is far better.