The trick is..
type *234# in your aircel mobile..
A menu Appear with the following..
- Aircel Live -
1.Dialer Tunes
2. Pocket Internet.
3.
4. and so...
Choose 2nd Option (pocket internet)
Then it will display more choices like
Pocket Internet
1. PI14 - Unlimited Browsing 3 days
2. PI98 - Unlimited Browsing for 30 Days
0 For more..
Now select 0
In more options window
3. Free PI - Free Browsing for 1 day
4. Back
Now select 3.
That's all your free unlimited gprs for one day is activated.
Now you can surf any sites..
But it is limited to one day. After that you can use the same trick to browse for unlimited number of days.