I have a samsung galaxy S that i am using a Att sim on. I looked under settings and it showed two networks, Att and Tmobile. If i were to put a Tmobile sim card in it would i be able to use it on Tmobile?
The answer is maybe. If the phone is unlocked, then yes, but....... Your data speed will depend on the frequencies the phone is capable of. If the phone has ATT frequencies, then the best you will get on TMO will be edge speed.