When u send a message for GPRS activation u receive message like GPRS activated successfully, but sometimes you receive message like service not available or else.
This means that airtel server does not update your activation and we can enjoy free mobile office for life.
I am using it from some months. It depends on your luck.
If you are using this type of free GPRS then don’t open airtel live or other pay sites like mauj, indiatimes etc

Update

It is long time I made this post and many people are saying that its not working. So here is the other trick hope it work.

If you know anyone from other state of India ( not where you live ), call them and ask for SIM card from thier state, make sute they activate mobile office in SIM before they send it to you. And as far I know it will work for free.

Discuss about this trick here – Free Airtel Mobile Office GPRS in Rajasthan

How to use Airtel GPRS in Mobile For Free.
To use this you need a GPRS capable Mobile and a Airtel SIM Card.

If you are new to GPRS then Get Airtel Live setting from customer care and edit it.

Setting Name- Airtel
Home Page- http://100.1.201.171:10021/mmsc
Access Point/APN – airtelmms.com
IP Address : 10.2.45.155

From some months people were enjoying free GPRS but its no more available. I am not sure about whole india but in Rajasthan people were using free GPRS. But the setting is no more working.

I am trying to find another setting, I will post here whenever I find it. Airtel live is always free, so enjoy it will anyone find another setting for free GPRS. Its not so good news because many of my friend using Airtel for free GPRS. I will try to get you free Idea GPRS in coming days.