I've got an unlocked T-mobile 8320 in Nassau, and it works just fine.
If all else fails, you should probably re-visit BTC wireless services and see the blackberry people in the Mall again. They should probabbly re-check the blackberry setup. Although I already had wireless service, they did some programming when I went in - probably setting up BIS, and I was up and running right away.
For service books, go here on your pc:
https://bis.na.blackberry.com/html?b...cell&locale=en
Once you create a new account, you will be able to send the BTC service books to your device.
When you do get service, goto OPTIONS > ADVANCED OPTIONS > TCP on your device and the APN for BTC that you'll need for OTA downloads is:
internet.btcbahamas.com
Leave the username and password blank.
This thread also addresses your issue:
http://www.blackberryforums.com/show...errerid=152637