I am a T-Mobile customer who bought an AT&T 8310 online and then unlocked it. I've been using it for a couple of weeks with no problems; I've installed Opera, GTalk, Facebook, etc... I just noticed today that the phone has the Cingular TCP/APN settings, and I never switched it to the T-Mobile settings.
What does this mean? Am I going through AT&T's data network for some things? Is this a big deal? If everything works, do I need to switch it?