I have setup this trunk and currently have it working from Avaya to UCM, but not the other way around. I found the error message that I am getting from the Avaya.
"SIP/2.0 403 Forbidden(Invalid domain in From: header)" Seems that Cisco is send the Extension dialed @ UCM ip address (ex. email@example.com) where the Avaya is looking for firstname.lastname@example.org, is there a way that I can tell the Cisco to do this? I currently have the domain specified under the ENTERPRISE PARAMETERS-->Domain Settings, but that doesn't seen to do anything.