This is a self-contained analog Intercom unit typically mounted near an entrance door. A visitor at the door can press the call button like a door bell. The speaker then sends chime tones or ringing to all phones programmed to receive door signals.
	
To answer the chime or ringing, a phone user just lifts the handset. This lets the person talk to the visitor at the door.
	
DSX-80/160:  a door speaker connects to an available Door Box port on a 2PGDAD Module (P/N 0891027). Each module supports up to two door speakers, with the maximum number of speakers installed limited only by the availability of station ports to connect additional 2PGDAD Modules.
	
DSX-40: a door speaker can connect to a 2PGDAD module or to one of the two “built-in” Door Box ports. As in the DSX-80/160, the maximum number of speakers installed is limited only by the availability of station ports to connect additional 2PGDAD Modules.
	
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