Cincinnati Bell has UMA. They were actually the first to launch UMA in the US. Cincinnati Bell Wireless - Home Run - WiFi
The question is how does the blackberry know what UMA "server" to connect to?
If it is in a service book then I would guess I'm out of luck. Cincinnati Bell doesn't currently have any UMA blackberries so they wouldn't have the correct service book to point the BB at the right address.
If it is a configuration somewhere else on the device then there is a chance I could just change it from the TMobile UMA server to the Cincinnati Bell UMA server.
By reading the other threads it sounds like it might be part of the "Blackberry Feature Enabler" service book.