The CS3 BU is the base unit for the CS3 conference system and provides all the necessary inputs and outputs to manage a conference for up to 60 microphone stations. It is the interface to all audio devices in a meeting room and offers a RS232 interface to connect an optional camera control system.

The CS3 BU can even work in a stand-alone mode in four selectable operating modes offering maximum flexibility in conference management. With the NOM limitation function, the maximum number of active stations can be programmed to 1, 2, 4 or 6 simultaneous open microphones.