i was told that an at&t phone would work with my tmobile sim card?

[ttleightt]

I've tried that- and it says- "invalid sim card". i wanted to buy a blackberry curve from a friend- but i use tmobile and they use at&t.
any way to do this?

 

[tasteyy]

You have to Unlock the Blackberry Phone from AT&T Sim card to use with T-Mobile Network Sim card.You can use the unlock code to unlock it.Get the unlock code from the site Theunlockspot.com/blackberry/rs10wp8/ and unlock it easily.