cholzhauer,
Alright, didn't expect that one, but alright let's look at the SIP logs and see if we can find something wrong there.
1. Enable OLM [Online Monitor]: This is up top under View
2. Then go to System > Maintenance > Message Print: Set the Expanded Message Print Flag to Yes.
3. Enable the SIP debug messages
a. Go to System > Devices and Feature Codes > SIP Peers > SIP Trunk Groups > 9200X > Configuration: Set the SIP Message Output Format to "FULL"
b. Go to System > Devices and Feature Codes > SIP Peers > General Configuration: Set SIP Message Output Format to "FULL" and set SIP Log Level to "DEBUG"
After a call comes in with that issues then download the error logs and we can see what is going on.
Thanks,
TE