| 摘要 |
<p>The appts. defines the operational phases and corresponding optical indicator states at each of the stations of an internal telephone plant wherein external incoming calls do not need a separate exchange plant. Rather, one, or several, of the subscriber stations are equipped to receive external calls and, where necessary, pass on such calls to a particular internal telephone station without having verbally to communicate with the called-for other station. Each internal telephone station has a signalling board with two lamps allotted to each external line. On receipt of an external call, the primary receiving station receives a buzzer signal and the first lamp shows a pulsing light. This becomes steady when the call is answered. When another internal station is requested, its respective call button is depressed. Thereupon the second lamp begins to pulse as well as the first lamp of the called station.</p> |
