is it possible for me to use my t-mobile sim card in an AT&T blackberry curve phone?

[Bunmi A]

is it possible for me to use my t-mobile sim card in an AT&T blackberry curve phone?

The phone is already unlocked. When i put in my t-mobile sim card into the AT&T blackberry, it said invalid sim card.

 

[michael g]

Yes, you just have to have the phone unlocked. If your currently an ATT customer and have been for 90 days you can call customer service and they will walk you through it. Then you can place any sim card in the phone.

 

[tasteyy]

It is still locked

The phone is already unlocked. When i put in my t-mobile sim card into the AT&T blackberry, it said invalid sim card.

While inserting USA T-Mobile sim card or any country Tmobile sim card,if the Blackberry Curve (8300 Curve) displays "Invalid Sim" or "Sim not valid" or enter "unlock code" message it is not an unlocked phone.It's 100% locked phone.So you need to unlock it fully.Visit the site Simpleunlocking.com get unlock code and get free unlocking instructions from the site Mobileunlockguide.com and unlock it easily from USA AT&T network lock.After unlock it you can use any GSM sim card in the phone sure it will accept that and continues to work.