I buy my sim in 2010.at that time there was just 2g net signal coverage was good.no call dropout was there.then comes 3g in maybe 2011-12. I use 3g as well at that time airtel was best is service and connection. but there comes 2016 with the 4g.
After this signal and connection become poor. I was traveling murthal from delhi .then I suddenly forget my way. I thought this is a perfect time to use googles maps.
But when I start my net .signals gone .it was written no service. Damn then after 1 hour I find my own way to marshal. So dont prefer airtel. Go for Vodafone its better and fast. and 1 more problem is billing problem.