G1 is a android phone so it should be know problem, same with the Mytouch and Cliq...If you get one of those download Handcent SMS app...it works great!
If the phone is unlocked...Think of it like this...If you buy it off ebay and its a T-Mobile G1 unlocked then it will work but if you go to the store and buy a T-Mobile G1 then no it will not work
