processor units p 1 p n connected thereto a plurality of input output processors iop whereby a plurality of line terminal groups ltg ltg n are connected to at least one of these input output processors iop and a memory system cmy connected to the central system bus and shared in common by all units of the multiprocessor system the fundamental functioning can be set forth in greater detail with reference to a connection between two subscribers a b the two subscribers are thereby respectively connected to one of the line terminal groups ltg 1 ltg n four different status messages m 1 m 4 are required for the call setup call clear down between two subscribers a b as follows m 3 setup call set up in the switching matrix network ringing the b subscriber etc and the status messages are deposited according to the fifo principle in an entry list el situated in the common memory system cmy and are serviced onto the processes callp 1 callp n allocated to the processors p 1 p n what are referred to as channel registers chr 1 chr n are also allocated to a connection parameters about the respective status of a connection are deposited therein for example to which line terminal group ltg x the subscriber is connected or which switching matrix network is involved in the connecting circuit as an example let the subscribers a b be connected to the line terminal group ltg x the subscriber a picks up the receiver of his terminal equipment he thereby informs the communication system of a desired connection to what is still an unknown subscriber b the seizure.