Special Features:

Wall-mounted intercom station consisting of a sound powered handset and a battery powered signal, provides reliable communications over distances up to 5 miles using a single pair of wires

Properties:

An item which may provide two-way amplified voice communications when connected to one or more like stations directly or via intermediate control equipment; includes loudspeaker (which may be used as a loudspeaker or microphone), signalling devices, amplifier and station selector switches. May include separate microphone, earphone, handset or headset. See also, telephone connecting station.