its not true... back in the days u could.. but now tmobile wont allow it... you have to get your phone unlocked to be able to switch sim cards now... easiest way to do that is call your phone provider (cingular/tmobile) tell them your goin on a trip overseas and your gonna need your phone unlocked..... they will ask you for your email address and the phones imei number which is found on the fone under the battery.... and then within a few hours they will send u the unlock code for your specific fone along with the instructions.... total time after u have the code and instructions to unlock your fone is about 2 minutes...