NOTES: (1) Some photos are symbolic, not exact. (2) AbleComm generally uses "line" to mean a circuit between a phone system and the phone company's central office that carries a conversation. NEC generally uses "trunk" to mean the same thing. (3) In this section, "control unit," "KSU" and "cabinet" mean the same thing. (4) In general, a "card" fits on a "board." (5) In general, a "station" is a phone, or a phone-like device such as a fax machine or credit card terminal.