I can speak only for vodafone + sony erricson.
From the stand by screen go to menu> settings> General tab > Setup Wizard> Settings download.
Then go to
menu> settings> Conectivity tab> internet settings> connect using
Under this you will fing 3-4 connections, depending on your operator.
On vodafone it is Vodafone_live!, Vodafone_MMS, Vodafone_connect, SEMC GPRS. Out of these only SEMC GPRS connects to the web correctly with SE phones. [Although Vodafone live is set as the default]
For airtel you will have to try each combo.
OR
On vodafone you can sms VL to 52586 to have you settings pushed to you. Airtel may have a similar service, you will have to check.