Airtel-the bharti airtel who claims to be the best service provider but for me its quite opposite. Facing Call drop or failure prob for long. Like I am talking someone on call and im between call use to get disconnected and error msg display call failed. Or voice cracking prob also there.
Many time my friends and family use to complain me that they are trying to call me but my number not reachable. complained many times but no solution. Every time same reply network upgradation work going on in your area