The WMI20 is a wall-mounted microphone input unit that can be used in conjunction with AUDAC MTX series multi-zone audio matrix systems, the RM523 and AMP523 web-based input control units, and the APG20 receiver gateway. It provides the ability to transfer an audio signal from a microphone-level audio source over a long distance using a standard CAT5e (or better) UTP cable. Connection must be made via an RJ45 connector on the rear of the unit.

 The depth of the RJ45 connector will not allow the WMI20 to be installed in surface-mount boxes. A jumper on the back of the panel enables 12V phantom power to power condenser microphones, and audio transfer is performed differentially with increased voltage levels, making the transferred signal insensitive to interference and noise generated by external devices. This allows distances of up to 500 meters to be bridged between the input unit and the receiver end.