.Airtel the 2nd largest mobile operator GSM Service Technology In India. .i had personally used airtel. M Using This Operator sim because of strong network service not for Other offer. For other facility I can say that its the worst Mobile Operator I have been use . because The cost of sms, data, and talktime charge is so higher then other mobile operator . if you using Airtel then would You also agree with me .I personally hate Airtel Because They against of JIO who can give us free data sms and free calling . Dam Airtel you Are the worst mobile operator .