Hey im using airtel sim from day first.And they claim open network fastest network.Let me tell you something honestly its baddest signal I ever experince in my life is airtel.I dont even know whats wrong, know a days but its just so bad. If you are looking for good service ho for Jio or Vodanfone in delhi NCR.But airtel no way guys higly recommend to say no.Thier customer service is very badly poor, they not even have time to listen. And service is very poor.