WE 543 DBMW - without Bell System markings. 8-78.
NOS in box.
Control buttons, exclusion key and "A-leads" (control leads) tell the switching equipment what kind of line to connect to the set (switching done within the PBX). Buttons marked:
"Message waiting" (the front desk could illuminate it to alert you to a message),
"Desk" (connected you to the front desk),
"Local" (connected you to a CO trunk for a local call), and
"Long distance" (gave you a direct path to a toll operator).
The last three buttons are momentary contact.
These button features relieved the attendant of having to route much of the guest traffic.
Outwardly, these sets look like a 544 or 545 set but have fewer line cord conductors (12).
543DB – 641A line key, C4B ringer
543DBC – 588B line key, C4A ringer – field/distributor converted from 544BB or 545BB.
