I am buying a used blackberry bold from a guy off the internet . And having it unlocked so I can use it out of the states using claro . Claro is a sim card provider. Will I need to call at&t to make sure the phone is unlockable. I have never used a phone that used a sim card . I know if I buy Sprint phone that has a bad esn number then I cant connect it.
Is it the same with a tmobile sim phone .