SIM cards...?

I have a t-mobile phone and a t-mobile sim card. I have heard that you can use t-mobile sim cards in cingular phones because they are compatable. Is this true and have you tried it?

SIM cards...?
while they are the same shape, unless the phone is unlocked, the tmobile sim wont work in a cingular locked phone and vice versa.





If you pop a tmobile sim into a phone locked to cingular, you run the risk of locking the phone...and not even a cingular sim will work in it.





I learned that one the hard way.
Reply:both r GSM phone companies but u need unlocked (phoens not locked to a certain carriers) phones to use from one carrier to another...search up more on google
Reply:it's ture.


but you need to make sure your Cingular phone is unlocked first.


otherwise, the phone will not recognize the sim card.