Is CUCM using IP instead hostname/FQDN supported with collab Edge?

[epicolo]

One customer is using dual domain scenario and is able to login, but the Phone Services do not register. Under Edge and Core logs we can see the Core rejecting the REGISTER attempt due to Unknow Domain and this is because the Jabber for Windows 10.6 is sending its SIP AOR as DN@CUCM_IP and of course the CUCM_IP is not a MRA domain.

The CUCM is using mixed mode 0 (TCP btw Core and CUCM) and the CUCM is configured with IP (instead hostname or FQDN).
This doc inform that to use IP is supported (http://www.cisco.com/c/en/us/support/docs/unified-communications/expressway-series/117811-configure-vcs-00.html), but is not working.

Question:
Does anyone know from which field/place the Jabber for Windows (i´m using  10.6) get its domain to construct its AOR for SIP comunications?

*I taught that it took from servicesdomain or VoiceServicesDomain, but it is not.

Any ideas?

PS: We can´t change the CUCM name from IP to other names at this point because it will affect all phones...

Thanks

[Dennis Mink]

In general, I would not use IP addresses, but only hostnames, if I can avoid it. 

Mainly so  certificates get properly signed based on a hostname as Subject rather than an IP address.