Abstract: A broadband private automatic branch exchange is to be implemented in which all broadband user stations can be switched like normal telephone terminals with all features of a conventional telephone private automatic branch exchange and without each broadband terminal requiring its own operator position. To achieve this, in accordance with the invention, all the broadband terminals (BB-E1, BB-E24) which are connectable via a broadband switching array (BB-V) to the subscriber line unit (TAE) of the public broadband network (VBN) are also connected like ordinary telephone user stations to a narrow band telephone private automatic branch exchange system (SB-PABX) which is connected via a signaling conversion module (VBNA) to the line unit (TAE) and which initiates the narrow band call setup and controls the broadband switching array for switching broadband calls.