Circuit arrangement for a microprocessor-controlled telephone PABX system, in particular an intercom system with external stations

The invention relates to a circuit arrangement for a microprocessor-controlled intercom system with external stations, where the external stations are connected via a two-wire link to a matching device which converts the analog information arriving from the external station into an information form which can be used for the central controller (Fig. 2). The object of the invention is to reduce the cost in terms of system units, in particular to reduce the number of sending and receiving modules required. This is achieved by disposing the respective connecting device within the central controller in the vicinity of the signal and connection processor, where the outputs and inputs of the signal and connection processor and the microcomputer of the connecting device which are required for information transmission are connected directly to one another and where furthermore, also for transmission purposes, control timing signals required for the program routine in the connecting device are supplied directly from the signal and connection processor to the microcomputer of the connecting device. The subject matter of the invention can be used in microprocessor-controlled intercom systems.