If you're looking for a magic number like 1800... there isn't any for any telecom operator. All numbers are circle wise. There are no single point toll free number for India.

But yes, Airtel does provide 3 digit toll free numbers callable only from Airtel mobiles/phones.

Checkout all Airtel Customer Care & Contact Numbers & this includes toll free numbers callable from your Airtel phones.

If you don't have Airtel mobile/phone connection then none of numbers mentioned below will work for you. Then look for the numbers from Airtel Customer Care & Contact Numbers.

In short:

For Airtel fixed line: call 121 toll free from your fixed line phone

For Airtel broadband: call 121 toll free from your landline

For Airtel Digital TV: call 12150  from Airtel mobile. You can also call Airtel toll free number: 1800-102-8080

For Airtel IPTV: call 121 toll free from any Airtel mobile

For Airtel mobile(including prepaid & postpaid): call 121 toll free from any Airtel mobile

In case you want to buy an Airtel toll free number for your company please visit this page.