Voice terminals work like special input/output (I/O) devices. The control unit performs all the decision making for the system while voice terminals act as the system’s sensors. Voice terminals inform the control unit of button depressions and feature status. They also inform the user of specific conditions by flashing lights or generating tones.
Voice terminals are connected to the control unit by a
●Voice 1 pair. The control unit uses this pair of wires for the primary audio path to and from the voice terminal. The control unit selects this pair to complete the path for outgoing, incoming, and intercom calls.
●Control pair. The control unit receives information on voice terminal status and user input on this pair of wires. It also uses this path to send ringing and lighting instructions to the voice terminal.
●Power pair. This pair provides power to the voice terminal.
●Voice 2 pair. The control unit uses this pair of wires for the secondary audio path to and from the voice terminals. This pair is used with the analog voice terminal to provide the Voice Announcement to Busy Voice Terminal and the Simultaneous Voice and Data features.
Voice terminals used with the MERLIN II system are listed here. Refer to Figure
