Hi Adam, I haven't tried with a Blackberry, but I can offer some suggestions.
Have you tried all the formats available? I would suggest trying the mp3 format if you haven't already. Just use broadwave.mp3 in the URL.
Also, it might be a question of bandwidth. As an experiment, I tried to connect via a dial-up connection using a 2G mobile phone's GPRS link, and although it connected it didn't have a fast enough data rate to sustain live audio.