METHOD 1
Just insert blocked sim inside a phone, then switch off phone and Remove sim from phone. Insert blocked sim in The phone again and switch on phone. Then press this code : *22233421#
Now Your Sim Will UnblockedMETHOD 2
First recharge your airtel mobile number with whatsapp pack and use the whatsapp until only 5-10 mb remains. now try to open one.airtel.in it will be opened And your sim Will unblocked now
METHOD 3
simple way..if Any Method Not Work For You Then Just Remove Your sim for 3 day's Then when You insert Your sim will be auto unblock...dont forgot to deactivate all gprs services
Enjoy