It's hard to tell the root cause to a problem such as this from the description alone. If the problem is reproducable, i would suggest pulling an information capture for the problem and opening a TAC case for analysis.
To pull an infocap:
Log in to the Administration Center.
Click Services > Logs > System Information Capture.
Enter or change the values on the System Information Capture Page.
Click Capture Logs.
Obtain the data by taking the following actions:
Navigate to the zip file specified on the page. The name of the zip file is based on the date and time parameters that you entered on the System Information Capture Page.
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...
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 discusses the bas...