This value holds the called party's number for this failed call, per the description, identifying the intended destination of the SVC that failed. This is the field to check when trying to determine whether failures on this port are concentrated on calls to a specific destination (suggesting a problem reaching that particular endpoint or network) versus spread across many different called numbers (suggesting a more general local or link-level problem). Seeing the same called-party number recur across many entries would justify testing reachability to that destination specifically rather than assuming a generic port fault.