On Win7 (64bit) Jitsi 2.0.4506.10553
Jitsi can't register new account on the server, if the jabber server running
on non-standart port (for example, 4432),
As far as I see, Jitsi always attempts to register new account on the port
5222 even if different server port specified in the form.
It seems like Jitsi overrides the custom port to 5222 in procedure of
account registration. But if the account already exists and you add it -
it'll work fine.
To catch the issue - I installed port-mapping service on the server (to map
port from 5222 to our custom 4432) - and if it's running - Jitsi can
register successfully. If not - there are no chance to do it.