For this you need android phone:
1.Recharge with a Data pack  example-103
2.Open your android mobile Default Browser .
3.In the address bar type live.airtelworld.com
4.Dont close the page till 510 seconds.
5.Now your net will be disconnected and you will se a ussd massage with 0.00 mb deducted from your main account balance.
6.Now open any web browser application or any application and use net.
7. Note Before disconnecting your internet
run the steps 2,3,4,5 again.
8.Now Check Your data balance. It will not deduct.

I know this one is old but many of us don't know about this free offer.
Aircel is providing free unlimited 3g for one month. No trick its just a free offer by aircel.
But since it is free there is a limitation that is you can use unlimited 3g between 6.00 a.m to 9.00 a.m.
Check if aircel 3g is available in your area. To activate the plan you need to dial
*122*5*1# or *122*456#
After dialing the ussd code you will recieve confirmation message from aircel that your pack is activated for one month.
You don't wake up early in the morning? Don't worry just use your brain. Schedule your downloading with IDM(internet download manager) and use a software called "Reconnect" which will automatically connect your internet and you can shcedule it.
Enjoy your sleep with automatic downloading. :D

• Recharge with Rs. 303 blackberry plan
• APN : blackberry.net

Steps:

• Recharge with rs 123(1gb 3g for 30 days)
• then recharge with rs 16(unlimited whatsapp and facebook for 30 days)
• Download nmdvpn and paste this config.

•  Deactivate 3g
• Dial *567*11# to activate mobile office(mo)
• After few minutes deactivate mo by dialling *567*2#
• switch off your mobile and take out sim and place it somewhere for a week.
• Now activate mo by dialling *567*11#

Instructions for mobile use :

• download opera handler
• use the settings mentioned below :

• Recharge with rs.9 3g pack(25mb/day)
• Use default internet settings(apn : airtelgprs.com)
• Now configure your web browser as follows : 

Web Browser Settings:
For Firefox
Navigate to Options>Advance>Network & Settings>
Manual Proxy Settings.
Put Proxy = 199.115.229.205 (You can use other proxies which are working in your area)
Put port = 80
NOTE: Don't Download Large Files More than 50MB.
Save Settings
Now Navigate to Options>General>Homepage>
Put Homepage : http://airtellive.com
South area people use this homepage if the above homepage not works for you : ic.bsbportal.com
Save and Click Homepage Icon.
Done.
Disconnect internet till 50 MB is reached otherwise your sim will be blocked. Use networx software to check how much MB you have used. If you have blocked your sim don't wory , i will post next tutorial on how to unblock your sim.
Enjoy fast free internet.

Here is reliance unlimited proxy trick 2013. Just configure these settings in your web browser and enjoy unlimited free net.

Proxy : 10.239.221.22 or 10.239.221.5 or 91.201.21.170
Access Point : rcomwap or rcomnet
Port : 8080
HomePage : www.google.com 


high speed proxy of reliance:
Proxy : 196.200.140.19
Port : 3128
Acess Point : rcomnet
HomePage : http://www.google.com

for android:
Proxy : 97.253.29.199
Port : 8080
Acess Point : SMARTWAP
HomePage : http://www.google.com or wap.rworld.com

• First of all download pd-proxy. Just google it.
• Sign up at pd-proxy website because you need to enter username and password to use pd-proxy software.
• open pd-proxy.
• Follow the screenshots.