GB1453518A - Centrally controlled telecommunications exchange systems - Google Patents

Abstract

1453518 Automatic exchange systems SIEMENS AG 25 Jan 1974 [30 Jan 1973] 03455/74 Heading H4K In a centrally controlled exchange a scanner, which is used for scanning all the circuits of an exchange which have a network appearance, is additionally used at the end of each exchange operating cycle to determine whether any of a particular group of exchange circuits is idle. The exchange is a PBX of the folded network type in which the exchange circuits such as subscriber line circuits T1, T2, local junctors HV, main exchange junctors (AV) and registers WS are connected to one side of the network. All such circuits are scanned/identified by use of a single scanner S which operates in four distinct modes to identify the number of the multiple switch input (section S1) the number of the multiple switch (section S2), the switching group (section S3) and the switching network section (section S4). The additional use of the scanner is to determine periodically whether there are any free local or main exchange junctors in the exchange and to cause lights to be lit at an operator's position which each indicate that at least one of a respective type of junctor is available. To this end at the end of every other exchange operating cycle the programmed controlled processor P causes all free local junctors to emit a request signal to the scanner which is enacted to use its "network section" searching section S4 to determine whether any section has a free local junctor, the presence of a free junctor in any section causing a lamp to be lit at the operator's position. At the end of each following exchange cycle a similar process is carried out to determine if any free main exchange junctors are available. The Specification also describes the general scanner operation for establishing a connection between a calling subscriber circuit T1 and a free register WS such that the shortest path can be used in the switching network. To this end once a calling subscriber circuit T1 has been identified the scanner first looks for a free register connected to the same switch as the caller and only proceeds to a group search, a section search and finally an all register search if no free register is found at a lower level.