Sounds to me like there is a process or app running on your phone which is attempting to make a connection frequently. Something that doesn't respect the "International data roaming Off" setting. Might want to look at your running processes, and see if there's anything, cause each time it attempted to connect to the data network, it'd bring up that message.
You can try responding by #ROF# from your dialing screen, that will help you to turn data off. In additon, you might want to turn off Syncronization, and back ground data for those apps in the back group.
From the home screen >> menu >> Settings >> Accounts and Sync >> Unchecked back ground data and Auto sync.
hope this helps!
we can use t mobile in india ? and what is the call chargers ?