I mentioned it looks like it's trying to connect to Unity rather than Unity Connection because the display string in the server window is printing out "Unity Address" rather than "Unity Con Address". But if the client has never been able to establish a connection, I believe it will always default to "Unity"; then change to "Unity Con" when/if it's able to validate it's a Unity Connection server.
Your configuration on CUPS seems correct. The only other thing I'd check in CUPS is if the end-user is associated with the Voicemail Profile that is using those two configurations. You can also verify the Mailstore settings for the Inbox Folder, etc. It that all looks correct, you may want to check if UC is listening on port 7993.
Other than that, you may want to verify the end-user credentials in the Accounts settings on the Jabber Mac client. You could also try changing the Server Settings to Manual and type in your Unity Connection server there to see if that has any difference. Otherwise, we'd probably need to get a PRT from the client experiencing this problem to see what the diagnostics are attempting to do when it's attempting a connection to the server after a fresh login.
