Sometimes you come across a BB that has the pin registered to another carrier even though the account is no longer in service. Its always a pain to contact customer service to release the PIN. I have read about a few steps to release this PIN yourself, just tried it and I can confirm it works here in the States.
Used ATT BB - tried to register with tmobile BIS - BIS states PIN already registered.
You need an active SIM with BIS already on it. (borrow sim from friend on tmobile)
1. Place the active bis sim in phone, when powered up go to setup email you should be prompted a new device has been detected do you want to change.
Choose yes to change device.
2. Place the active bis sim back in the old phone it came from and do the same steps to change device back.
Once those two steps have been completed the Original ATT BB is now free to be registered on BIS with any carrier.
This worked with ATT and Tmobile, I assume it should work with DIGI, CLARO Etc.