Hey I am using Airtel for upto 5 years some times before it was known for the good service providers in telecom but before some times they charges little expensive for calls, data and sms than other telecom operators and the worst part of this is after up gradation of sim from 3G to 4G its network become worst lots of problems arises like poor signal and their 4G network is not available in most of the places.
Airtel is known for their internet speed but Airtel 4G does not provide speed even like Airtel 3G.