A/A. If your SIM has been blocked by the Airtel for Using Internet, Just follow the below steps to Unblock your SIM Card and Enjoy the High Speed Internet:
If your Airtel SIM is Blocked (from using free GPRS) 1st Deactivate all the Data plans (2G, 3G, 4G, MCA, etc.) by sending 3G/4G to 121 or Call 198 (Customer Care) or *121*5# to deactivate all the Services.