Audit Notification for SIP Decline errors
When a SIP response of 603 Decline is processed, the audit log reports this situation as a [309] Failed to identify a matching message type for {interfaceRefName} event.
Because there may be a large number of expected [309] audit events in a properly configured system, it would be better to have a unique audit event for when the SIP response is declined instead of reporting it as a [309] event.
Case 316855 contains the details.