GB1252552A - - Google Patents

Abstract

1,252,552. Automatic exchange systems. SIEMENS A.G. 15 Jan., 1970 [12 March, 1969], No. 2007/70. Heading H4K. In an exchange having a sectionalized switching network in which each section has its own marker/control circuit and at least some of the sections are linked to each other by overflow lines, e.g. R14, a path to a particular destination exchange e.g. 21 is sought initially directly via the calling section, e.g. GRE1, to a firstchoice junction group, e.g. B1, then if all routes to this group are busy, via the same section, an overflow line and a second section having access to the same junctions and thereafter, if necessary, via all the other sections in turn whereafter the same procedure starting with the calling section is repeated in respect of a second-choice junction group, e.g. B2, and so on until a free, accessible junction is found. Preferably some of the outlets, e.g. BT12, of one section GRE1 are multipled to those of another section, GRE2 these outlets being investigated for suitability before taking overflow lines or second choice junctions into account. The second section's control circuit RWMV2 provides the free/busy state of the parallel outlets to the control circuit of the first section, the latter not normally being aware of the state of these outlets. Second and later choice junctions provide routes via intermediate exchangers, e.g. 22, 23, 24 to the required destination exchange.