Switching configuration for PCM time division multiplex telephone exchange having a central switching network and individual sub-switching networks

Claim 1

A switching system for a centrally controlled PCM time division multiplex telephone exchange, in which a central switching network provides connections and a central processor provides control and switching signal processing, and including a plurality of individual line groups having a sub-switching network for external connection of interexchange trunks or subscriber lines and having an individual control unit for receiving switching signals from said lines, for switching signal preprocessing and for switching signal transfer to the central processor and for switching signal transmission to said lines, and in which said plurality of individual line groups of the sub-switching networks are connected internally via groups of link lines groupwise separated to switching network connections of the central switching network, and in which the line groups are assigned pairwise to each other, and within each of said line groups line units provide external connection of said subscriber lines and/or said interexchange trunks; and wherein a particular line group is connected via internal lines to the sub-switching network of a first of two groups is additionally connectable to the sub-switching network of the other of said two groups, a partner line group, whereupon for connections, via a line unit of the first line group the corresponding switching signal processing and sub-switching network setting is controlled by the individual control unit of the second line group, the improvement comprising: means for switching over said internal lines within the line group leading from a line system within one of said pairwise assigned line groups to its sub-switching network within a diversion phase individual to the connection to the sub-switching network of the other said line group, such that within said diversion phase, changeover switching is limited to internal lines which are not busy through release of said connection, to said internal lines via which said connections are through-connected to subscribers where a called party has answered internal lines seized by said connections, in which the process of establishing one of said connecting are completed, but wherein the called party has not yet answered, and such that with t he completion of the diversion phase, the connections in the process of being set up are released.