For some odd reason customer support of most mobile operators hesitate to give the GPRS settings for your mobile phone. They always ask you to send an SMS with a code that with reply with the settings file. This solution does not work on many mobile phones that are not supported by the network. GPRS will still work on these phones,you just need to enter the settings manually. Here is a list of GPRS settings for most Indian mobile operators.

Airtel GRPS settings

Airtel Live settings

Account Name Airtel live
Access Point Name airtelfun.com
Username
Password
Proxy server Address 100.001.200.099
Proxy Port 8080
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

Airtel Mobile Office settings

Account Name Mobile Office
Access Point Name airtelgprs.com
Username
Password
Proxy server Address
Proxy Port
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

Vodafone Live GPRS settings

Account Name Vodafone Live live
Access Point Name portalnmms
Username
Password
Proxy server Address 10.10.1.100
Proxy Port 9401
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

For Windows mobile users we have a guide on Vodafone Live GPRS settings

Aircel GPRS settings

Account Name Aircel
Access Point Name aircelgprs.pr (postpaid customers use aircelgprs.po)
Username
Password
Proxy server Address 192.168.35.201
Proxy Port 8081
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

Idea GPRS settings

Account Name idea_gprs
Access Point Name imis
Username
Password
Proxy server Address 10.4.42.15
Proxy Port 8080
Data bearer GPRS
Authentication Type Normal
Homepage http://wap.ideafresh.com

Idea Internet Settings

Account Name idea_internet
Access Point Name internet
Username
Password
Proxy server Address
Proxy Port
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

Tata Docomo GPRS settings

Account Name tata docomo internet
Access Point Name tata.docomo.internet
Username
Password
Proxy server Address
Proxy Port
Data bearer GPRS
Authentication Type Off
Homepage http://internet.tatadocomo.com

Tata Docomo Dive In Settings

Account Name tata docomo dive in
Access Point Name tata.docomo.dive.in
Username
Password
Proxy server Address 10.124.94.7
Proxy Port 8080
Data bearer GPRS
Authentication Type Off
Homepage http://divein.tatadocomo.com

Reliance GPRS settings

Account Name smartnet (smartwap for wap users)
Access Point Name smartnet (smartwap for wap users)
Username
Password
Proxy server Address 97.253.29.199
Proxy Port 8080
Data bearer GPRS
Authentication Type Normal
Homepage http://www.(anyWebsiteUwant).com

BSNL GRPS settings change depending on the area you are from, hence I will not be listing it here. You can send yournumber to 58355 to get the GPRS settings.