Every county assigns the standardized IDs differently- some just don't assign them at all. Morris County does it one way, Middlesex County does it another way, and then Somerset County does it a third way. As GTR8000 said, seeing the aliases will help. But, you'll notice a pattern regardless of the county evaluated- each service has been assigned a block for their radios within the municipality/recognized agency number. NJICS, on the other hand, is sequential unless a request is made to mirror the existing standardized ID generated by that agency's county for their system.