Here is the latest Airtel unlimited 3g/4g trick confirmed working in Many States
Airtel SIM (3G enabled)
No need of balance. This trick can be worked with 0 balances.
Small 3G data pack required (This will help to prevent 3G speed capping)
SPEED: Up to 500 KBps i.e. 7.2 Mbps
Download config file from here
How to use it in PC :
1.Connect your system with modem/Mobile with APN airtelgprs.com
2.Download The Attachment of Trick (if downloaded all ready then go to next step).
2.Install Nmdvpn and Put configs(or exact) Here (C:program FilesNMDVPNconfig) in your system location
3.Windows 7 and Windows 8 Users RUN NMD VPN as the Administrator.
4.Just Connect and Enjoy.
How to use in Android Phone :
Download and extract config in SD card.
Go to Google Play Store Search for open vpn for android.
Install Open Vpn in you android device.
Add airtel tcp 3G Vpn Config to open Vpn folder.
when it ask user name password (see tp txt file in attachment) enter it.
Run and Enjoy