Just got an email from my contact at RIM who says BIS-B has port 21 blocked and this is the most likely explanation of what you're seeing.

What carriers were you with again?

Also...we just uploaded yet another build of BeFTP 1.0b especially to confirm that it's a blocked port problem and not something else.

Erase your current distributive, go to the above link, request refresh from the browser and download again.

Run BeFTP, enable logging and try to connect again.

This time you should be able to look at the log while waiting for the connection.

Let us know what it says.