Did you have OCWA installed prior to the BES installation? If not, and your statement concerning the Communicator desktop client usage holds true, then go back and install support for Windows Messenger (yes, it seems backwards). It's fairly easy to configure. On the device client-side, you should use the following:
Sign-in name: email/sip address
User name: DOMAIN\username (or
RIM suggests using the SIP address only, although I've yet to get that to work. In my environment, I've been able to use US\username and
for the user name field. In another installation (a friend's), I had to use the latter -
Usage over TCP is extremely unstable and you'll notice fairly frequent disconnects, buddy list reloads, etc. I'd highly suggest TLS if you have it configured.