How to Activate Airtel 4G For Free:br Hiii this is JAYA from TELUGU TECH.br In this video how to activate airtel 4g sim from 3g2g(already existing sim only).br STEP-1:br SEND AN TEXT MESG TO 121 LIKE THIS [SIM 20 digit number]br STEP-2:br SEND 1 TO ACTIVATE AIRTEL-4G SIM.br FOLLWS ON FACEBOOK- SUBSCRIBE FOR MORE VIDEOS.