Do you mean the system ID like in the picture attached? Or the MARCS Zone ID? The system ID can be searched in the RR DB to get a name, but I'm not familiar with how unitrunker does search if that's what you mean.
The system search is a premium feature,
RRDB | Trunking Data | Query and if you enter the 3 digit System ID, it will find any systems with that ID regardless of WACN.