An ISDN remote switching unit for accommodating analogue telephone subscriber lines and ISDN digital subscriber lines comprises at least one signal converter for each of the conventional analogue subscriber so that a line signal, an address signal and tone signal of each conventional analogue subscriber are converted into a signaling system of the ISDN digital subscribers line, and a traffic concentrator connected to the signal converter and disposed remote from a host exchange station, whereby the signaling system between the remote station and the host station is unified for both the analogue telephone subscriber and the ISDN digital subscriber.