Switching systems for ISDN

Each individual communication system is essentially characterized by its access network. The author shows that, for integrated services digital network (ISDN) exchanges, the basic access and the primary rate access mainly determine the functions to be performed. In addition, he demonstrates the possibility of introducing concentrators, multiplexers, and new signaling functions between exchanges. Also, a forecast is given of how today´s ISDN will evolve in the foreseeable future. The next development steps, to broadband and more intelligent networks, have already started. More complex VLSI and a higher operating speed will be the prerequisites for this continuous evolution