line(circuit between subscriber's telephone and exchange, the transmission medium between line terminations - ITU-T (CCITT) I.430.E); circuit(ITU-T (CCITT) G.701, I.112); trunk(one communication channel between 2 ranks of switching equipment in the same exchange, or between two exchanges); bus(one or more conductors used as common link between two or more circuits, IEEE); highway(PCM); pipe(virtual connection, ATM)
line(In communications, a connection, usually a physical wire or other cable, between sending and receiving (or calling and called) devices, including telephones, computers, and terminals); line appearance(In telephony systems, the instance of an extension or phone number on a phone. For example, if a user's desk phone is provisioned with his extension, then you can say that his phone has his line appearance. Business phones may have more than one line appearance)