Tricks To get Free 3G/4G data : 

1. First you will download the app - DroidVPN from play store.
2. After Download go to This DroidVPN Link and signUP For new account. signup link -                              http://droidvpn.com/signup.php
3. If you Have Already An Account on the DroidVPN. Then You Can here for airtel tricks.
4. Now Open Droid VPN App and now click on Setting in Droid VPN.
5. Now select Connection Protocol >>Select Tcp
6. Select Proxy Setting>> Enable
7. Select Proxy Server >> 195.189.123.135
8. And Proxy as >> 3128
9. Now click on HTTP Headers and put HTTP Headers.
         Host - 180.179.103.247
         x-online host - 180.179.103.247
or if above host is not working then there is another host you can try also that host.
       Host - 180.179.207.111
       X-online host - 180.179.207.111
10. Now open the setting and select any one free server from the list.
and after that you enjoyed the free Internet.