The WM-300L Wall Mount User Station works within the TW (Two-Wire) Intercom System as a private listening headset station. It is designed to fit directly into a standard 4-inch square 2-gang electrical conduit box 2.25-inch deep. The rear section is not enclosed and uses the back-box to provide a housing when installed. The user station is perfect for permanent installations where a wall-mounted station can provide an unobtrusive operating position. Most often it is located where the operator can conveniently attend to on-going operations while wearing a headset. A handset canbe used in place of a headset, if desired. Practical operating features include 2-channel selection, a latching-action microphone on/off switch, a momentary-action microphone on/off switch, and a headphone volume control. The WM-300L uses a 4-pin dynamic mic headset connector. User-oriented features include a microphone limiter circuit for equalizing levels, a powerful headphone amplifier, silent channel-select switching, and well-placed controls for ease of operation. Most any type of headset may be used with the WM-300L; low-Z or high-Z headphones, with dynamic or carbon microphone. The carbon microphone headset port also accepts Plantronics telephone-type headsets. Screw terminals mounted on the circuit board are provided for user station interconnection to the line. A 2-pair shield cable, such as Belden 8723 or equivalent is recommended since it allows each channel to be carried over a separate shielded pair, reducing the possibility of crosstalk between channels.