Line appearance indicate users making and answering calls on a specific external trunk.
Line appearance buttons show the use of a trunk line on the system and tracks the activity on the line. Only external calls can be answered or made on line appearances. Line appearances can be used with Analog, E1 PRI, T1 PRI and BRI trunks PSTN trunks. They cannot be used with E1R2, Q.SIG and IP trunks.