Problem description
Does CUCM logs calls that are rejected?
Solution
Yes, we can able to log calls that are rejected in the system with the CDR service and capture logs for the calls registered with Zero Duration flag.
CUCM logs all unsuccessful calls which are rejected and failed due to rerouting and failure calls when attempt to go thru the busy trunks.
Log calls with Zero duration flag - This parameter enables/disables the logging of CDRs for calls which were never connected or calls lasted less than 1 sec.
CallManager does not generate CDRs for calls that terminate normally and have a duration of 0 seconds, unless the CDR Log Calls with Zero Duration Flag service parameter is set to True.
Refer the below link for CDR configuration,
Logging calls with Zero Duration
