Multipoint Conferencing Server. A hardware or software H.323 device that allows multiple video conferencing (or audio or data) users to connect together. Without an MCS typically only point to point conferences can take place. Commonly supports voice activated switching, where whoever is talking is broadcast to all users, but new systems suppport "Hollywood squares", where multiple windows show each participant. ITU-T standard H.231 describes the standard way of doing this. Many current systems only support H.320 (ISDN) but many vendors are working to upgrade their products to support H.323 (LAN, Internet) as well. In the H.320 space, this functionality is referred to as a multipoint control unit (MCU). Sometimes these terms are used interchangeably, although they refer to somewhat different implementations.