An ISDN Communication System

An ISDN communication system (1) comprising an ISDN line (2,3), connection means including at least one analogue port (5,6) and a data port (7), at least one non-ISDN piece of equipment connected to the data port (7) for connecting the non-ISDN piece(s) of equipment to the ISDN line via the connection means, a non-ISDN analogue control unit (8) connected to the analogue port(s) (5,6) for receiving analogue information transmitted over the ISDN line (2,3), and a plurality of analogue extension devices connected to the analogue control unit (8). The analogue control unit (8) is also connected to the data port (7) for controlling the supply of analogue information, received at the control unit from the ISDN line, to the analogue extension devices. The invention also relates to an analogue control unit.