GSM phones run certain frequencies...overseas they use mostly 900-1800mhz where as here in the states at&t runs 850mhz and 1900. If the phone has all frequencies, it would work here, otherwise it is not compatible with our GSM networks. (I believe T-mo runs 850 and 1700?)

A friend of mine just came back from Thailand with a "TCL 650" phone, assuming that it would work in North America. After fiddling with it for a while - surprise - it doesn't work. I don't know much about why it wouldn't work - something about 900 MHz vs 1900? Can anyone shed some light on why this won't work or whether there is any way to make it work?

Thanks in advance!