This object specifies the forward signal indicating the call originated from an ordinary subscriber's line and carries no priority treatment, for national calls. This classification affects how the call is treated for resource allocation during congestion; non-priority calls are typically the first to be blocked when trunk capacity runs short, so this signal is what marks a call as eligible for that treatment. A routine residential phone call would carry this forward signal, marking it as non-priority so it can be blocked ahead of priority traffic during a congestion event on that national trunk.