Your best bet is to buy a GSM phone. For a regular iPhone to work on t-mobile requires a bit of handy jailbreaking work as iphones are only supposed to work on AT&T anyway. I'm not sure what is different in the programming in the Thailand version, but I'm sure it's not too much different.

Ok, so I've searched the forums here, but have been unable to find answers to my specific question. I hope I haven't just missed it! But here we go:

I'm currently living in Thailand and, before I go back, would like to buy an unlocked cell phone. However, I don't fully understand how unlocked cell phones work! I'm using T-mobile in the states. If I buy, for example, an iphone here, will it work in the US? I keep reading something about bands, but I don't really follow that. Are there other concerns I should have or things I need to keep in mind while buying a phone here?

Thanks for the help!