Send the word Airtel to 62407 and you will receive an instant text message that will read as follows:
"Thanks! Dial 1-877-247-4047 and use the Pin: xxxxxxxxxxx to get 30 FREE minutes to India. Acceptance is consent to receive future promotions from Airtel."
They may send you spam sms in future so may not be a good deal for people with pay-per-usage sms. They may call and not send SMS…don’t know.