The Aiphone AX-084C central exchange unit controls all audio and video communication as well as any connecting output such as video and door release for up to four master stations and eight door or sub-master stations (sold separately). The included software works with a PC to program the system functionality and record data from the system. The priority of each station can be ranked and programmed into the unit so that when multiple calls are received, the unit places them in a queue based on a combination of the station’s registered priority and time the call was placed. CCTV and electronic access control can be integrated using a customized third-party program (not included). The unit has a black metal housing and mounts to a desk, wall, or 19: EIA rack (sold separately) using the included brackets. Requires one Aiphone PS-2420UL power supply (sold separately) for an audio-only system, or two PS-2420UL power supplies for an audio/video system.