Talking about Airtel(in delhi), one of the leading mobile network operator of india, the customer service of them is really awesome. The main drawback of airtel is that their call rates are much higher and almost each service provided from them is very costly when compared to others. The network will be available at many places but BSNL is leading in this regard. The call quality is good and the 3g internet speed is not upto the mark but 2g internet speed is good enough. Totally airtel is very good except that its services are much costlier compared to others. happy with it.