Patent GB-1152579-A (GB)
Title: Improvements in or relating to Automatic Telecommunication Systems.
Inventor: MURRAY LAWRENCE JOHN
IPC: H04Q3/54
Filed: 1966-08-03
Abstract: 1,152,579. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. 10 July, 1967 [3 Aug., 1966], No. 34869/66. Heading H4K. In a multi-exchange system wherein each exchange is of the non-director type (i.e. translators for providing routing digits are not provided) and includes a reed relay switching network whose stages each include groups of primary and secondary matrices having individual control circuits, incoming terminating calls are served by a special set of registers which are responsive only to the numerical digits of the wanted party's number and which transmit these digits direct to the control circuits of the numerical selectors. For locally originated calls and incoming tandem calls another set of registers associable with one or two stages of code selectors are utilized. The switching network details are more particularly described in Specification 1,131,367. A directortype exchange for a large (800) exchange network as opposed to the present non- director exchange for a small (80) exchange network is described in Specification 1,149,187. A network of exchanges is depicted in Fig. 1, where the references 25, 22, 49 represent tandem exchanges having local subscribers and local exchanges, e.g. 27, 36, 42, 88 attached to exchange 25, connected thereto. Exchange trunking (Figs. 2, 3). Taking exchange 22 (Fig. 2) as an example it can be seen that local subscribers SUB and incoming tandem junctions TJB are connectible via register access circuits SRAB, TRAB and register connectors RC1B, RC2B to a common register pool R1B, whereas direct incoming junctions DJB are connectible via access circuit DRAB and connector RC3B to another pool of registers R2B. After receipt of the numerical digits from the junction the latter forward the digits in multipotential form over the speech wires to the control circuit of a first numerical selector 1NSB whose outlets OSB give access to local subscribers. (It should be noted that the conventional symbol for 10-level, two-motion switches has been used on the drawings but this is merely for convenience, the actual switches being of the coordinate reed relay type. Further, the outlet levels, 1-0 reading upwardly, need not have any numerical significance so far as dialled digits are concerned since the switch control circuits are provided with rudimentary translation fields). The registers in the R1B pool however direct the received exchange code digits in multipotential form to the control circuit of a first code selector 1CSB. Depending on the value of the digits, a direct or tandem outgoing junction level is chosen or a trunk in the levels leading to the second code selectors 2CSB or the numerical selectors 1NSB is selected. Operation. Locally originated calls. STD call.-In response to the digit 0 from a local subscriber of exchange, e.g. 22, the register R1B immediately seizes the first code selector's control circuit and transmits the digit " 0 " to it after receiving a proceed-tosend signal. After a connection through to the " 0 " or STD level of the selector has been made, a metallic path is cut through in the access circuit SRAB so that succeeding digits are sent direct to the STD equipment and the register releases Own exchange call.-In this case, but after the receipt of the first two digits (i.e. the exchange code), the register R1B again seizes the first code selector's control circuit and on instruction from the latter forwards the two digits in multipotential form. The control circuit on recognizing the digits 22 as being indicative of an own-exchange call selects an outlet in the level 2 leading to the numerical selectors. When the latter's control circuit is ready, a proceed-to-send signal is reverted and the register repeats the numerical digits as and when it receives them. Outgoing call, direct junction.-In response to the digits 25, 58, 24 or 49, the first selector's control circuit chooses an outlet in levels 5, 6, 7 or 8 and when the registers at the incoming ends of the junctions connected to these outlets are ready, the originating register R1B repeats the numerical digits only, in 10 i.p.s. form thereto. As an alternative here, the numerical digits may be transmitted direct from the caller as in an STD call. In the case that the digits 33, 56, 70 or 63 are dialled, a second code selector 2CSB is seized from level 3 of the first code selector and the exchange code is repeated from the register R1B to the second selector's control circuit whereafter the numerical digits are repeated to the selected outgoing direct junction. Outgoing call, tandem junction.-The selection of a suitable tandem junction in the appropriate level is effected as per any other type of call but in this case the originating register repeats the full number (exchange code plus numerical digits) to the junction in response to a proceedto-send signal from the incoming register at the tandem exchange. Incoming call, tandem junction.-The same register pool as for a local call, viz. R1B is utilized, the further setting-up of a connection being accomplished in a similar manner to locally originated calls. In this case of course the local numerical selectors will not be utilized at all. Incoming call, direct junction.-Here the special register pool R2B which is responsive only to numerical digits is involved, the connection being set-up directly via the numerical selector 1NSB.