Digital local switching system for integrated service digital network

Abstract

An integrated service network ('ISDN') is structured to connect subscriber lines through a packet switching system to incoming or outgoing packet switching calls without passing them through a circuit switching system. This effectively uses the speech path of the circuit switching section instead of using it for packet switching calls. At the same time, the invention minimizes the influence of the introduction of the ISDN upon the software of the circuit switching section. The ISDN digital switching network applies to circuit switching calls which are switched at a local switch and to packet switching calls which are to be switched at a toll switch. The digital switching system separates calls into circuit switching calls which are transferred through B channels, packet switching calls which are transferred through B channels, and packet switching calls which are transferred through D channels in order to connect the circuit switching calls to a time division switch and the packet switching calls to a packet multiplexer. The packets are concentrated and multiplexed into separated packet switching calls. The circuit switching calls from the time division switch are multiplexed with the packet switching calls from the packed multiplexer and are placed in predetermined time slots in accordance with a band width designated corresponding to respective call traffic.