Patent GB-948156-A (GB)
Title: Improvements in or relating to an automatic telephone exchange
Inventor: BRUNBERG KARL GUNNAR
IPC: H04Q3/00
Filed: 1960-07-14
Abstract: 948,156. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. July 14, 1960, No. 24633/60. Heading H4K. Subscribers' directory numbers may be re tained and the location of their exchange equipment may be altered readily over a distribution frame in an exchange in which calling and called subscribers are identified by marking a cross-point particular to a subscriber in a cross-point identifier matrix, the co-ordinate wires of which are associated with relays which operate to signal a marked cross-point, subscribers being arranged in groups, each of which is served by a number of identifiers and the termination of a call being made over a selectormarker arrangement which marks the crosspoint of a wanted subscriber in a group, connections between the selector-marker and the identifiers being arbitrary so that the relationship between directory number and equipment location within the group may be varied easily. With this arrangement subscribers' lines may be readily regrouped without change of numbering and when a subscriber's line is taken out of use its associated equipment may be readily put in service for any other line in the subscriber's group. Moreover, with pbx groups the arrangement permits all the lines of the group to be tested simultaneously over the identifier which selects the first idle line of the group. Furthermore, if applied to a pbx exchange the arrangement enables one extension line to have more than one extension number. As shown in the block diagram of Fig. 1, calling subscribers are identified in the matrix of normally closed line relay contacts comprising the cross-point identifier matrix IDS which in conjunction with a marker SLM seizes an idle originating relay set SNR and connects it over stages SLA, SLB. A free register REG is taken into use over a connector RS and receives the digits sent by the calling subscriber. The register transmits the wanted subscriber's identity forwards in two-out-offive frequency code and by way of identifier IDG, code receiver KMG, and marker GVM sets up a path in the wanted direction over group selectors GVA, GVB, to selectors SLC. From this point four digits are transmitted by way of identifier IDC to code-receiver KMS which marks the location of the wanted subscriber in the appropriate group of identifiers IDS. Such marking is effected over a selectormarker SV which extends a mark on a single wire in response to the code set up in KMS. The mark in IDS seizes the marker SLM together with a free terminating relay set LKR over which the call is completed through stages SLA, SLB and SLC. Detailed drawings, Figs. 4 to 8, not shown, are used to describe the SLA, SLB, SLC, selectors together with the equipment IDS, SLM, KMS, SV, LKR and IDC, necessary to terminate a call. The exchange employs code-bar selectors of the kind described in Specification 832,865 in which each selector has ten bridge inlets with 50 outlets multipled across the bridges to give triple-group working. In the process of establishing a connection, the four digits locating the wanted subscriber amongst the 10,000 inlets to stage SLA are set up on four sets of five relays in code-receiver KMS and contacts of these relays extend markings to the appropriate one of five selectormarkers SV, each of which serves 2000 lines and has as many outlets. Each selectormarker serves two identifiers IDS each catering for 100 lines. A distribution frame is provided between each selector-marker SV and its associated identifiers IDS. The selector-markers comprise twenty sets of ten relays, each set being associated with 100 outlets and each relay of the set connecting up a group of 10 outlets. The appropriate group of 100 outlets is chosen by one of a further set of twenty relays. Having operated two relays, one from a group of ten and one from the group of twenty, the codereceiver KMS extends a units mark to the wanted one of the ten connected outlets. As applied to the identifier IDS this mark has a voltage twice the value of such a mark extended directly from a calling subscriber. A relay in the identifier IDS discriminates between these two voltages to seize an originating relay set SNR or a terminating relay set LKR. Where an outlet of the selector-marker is devoted to a pbx line group, the units mark from codereceiver KMS operates a relay particular to the group so that all the cross-points in the identifier IDS associated with the pbx group are marked simultaneously. The co-ordinate relays of the identifiers IDS are connected in chain so that only one relay in each co-ordinate operates and locks out the remaining relays. Only one line of the pbx group is therefore connected. Specification 640,508 also is referred to.