Hi friends I am using airtel for last 4years .it is one of the best service I used.signal coverage and signal quality is very good.were ever you go airtel signal is there.it is mostly useful for village people in which most of the other operators fails to give signal.airtel is providing 2g, 3g, 4g services which are quite good.but the airtel 4g is not reached the expected 4g speed.but main disadvantage of this is call and data costs are very high.as they are providing quality service they are also charging high.but it is a trust-able service operator.