I would get back to THUS and ask them why they are sending you an Alerting back. They should be sending a Release\Disconnect with a Disconnect cause of 17(User Busy). The codes they are sending in the Display field would only be relevant if they were interworking with another PBX so you extend some features like camp on etc.
I have a similar problem and from my investigations on CCM 4.2.3 by default it is set to ignore Progress Indicators attached to Alerting messages. Therefore CM applies ringing when it recieves an alerting message rather than connecting the speech path to and allowing the user to hear the inband audio.
SIP traces provide key information in troubleshooting SIP Trunks, SIP
endpoints and other SIP related issues. Even though these traces are in
clear text, these texts can be gibberish unless you understand fully
what they mean. This document attempts to br...
Please find the attached HTML document, download and open it on your PC.
This provides an easy to use form where you simply answer a few
questions and it will render the proper jabber-config.xml file for you
to copy/paste. There is built in logic to verif...
[toc:faq]CUCM Database Replication is an area in which Cisco customers
and partners have asked for more in-depth training in being able to
properly assess a replication problem and potentially resolve an issue
without involving TAC. This document discusse...