Patent GB-1365156-A (GB)
Title: Telecommunication exchange systems
IPC: H04Q3/42
Filed: 1972-07-27
Abstract: 1365156 Automatic exchange systems PLESSEY CO Ltd 27 July 1972 [22 July 1971] 34411/71 Heading H4K In a register controlled exchange in which subscribers are connected on only one side of a first switching network and local, incoming and outgoing junctors have appearances on the other side of the network, the subscribers are connected to the network via a further switching network including cascaded switching matrices and having additional outlets on the first network side leading to registers and to local call junctors. As described the registers can communicate with the incoming and outgoing trunks over paths excluding the first network. In the cross-bar network shown the first network comprises A and B stages RSA1 to RSA6 and RSBX1 to RSBY5 to which subscriber S can be connected over distributer switch stages DSA1 to DSB2. The verticals of the distributer switch A stages are divided into groups 1 to 3, 4 to 12 and 13 to 16 which give subscribers access to registers 8, to horizontals of network on the subscriber side and to the call originating sides of the local transmission relay groups LTRG 1 to LTRG 40 respectively. The registers are also directly connectible to outgoing relay groups OGRGA1 to OGRGBN over junctor connector JC to enable dialling out to a distant exchange before a speech connection is set up. Own exchange call.-A subscriber lifting his headset is connected via the distributer switch DSB1 to DSB2 to which his line circuit is connected, to a free register REG. After two digits have been dialled the register takes into use either, of two, translators Trans 1(1) or Trans 2(2). The translator indicates to the register that a local call is involved and releases. When six digits have been received one or other of two router controls RCX or RCY is taken into use and this becomes coupled to the register and to a network A switch DSA1 or DSA2. Markings are extended from selected router control by way of both A switch DSA1 and DSA2 and over the links towards the local transmission relay groups. Upon reception at these groups some of the markings are extended to the network switches RSA1 to RSA6 to prime those switches to receive markings from the RSBX (1 to 5) or RSBY (1 to 5) switches associated with the selected router control. A signal is returned from the primed switches to the router control, a line marker LMKR relevant to the 100 subscriber groups of the called subscribers is taken into use and the line circuit of the called subscriber marked. Markings are now extended in accordance with the self-steering principle towards the eight local transmission relay groups connected to the line distribution stage in which the calling subscriber is located. A connection is set-up from the terminating side of one local transmission relay groups to the called subscriber line circuit, the router control tests for path continuity and performs a line loop test to check that the called subscriber is idle, a connection is set up between the calling subscriber and the relay group and on completion of a successful connection momentary continuous ringing (for calls to PBX extensions) followed by interruption ringing is transmitted to the called subscriber and ringing tone is returned to the calling subscriber. The register and router control release and the call is supervised by the relay groups. Outgoing call.-Outgoing calls proceed as for own exchange calls until the translator indicates that an outgoing call is required. The register seizes the junctor connector JC and all free junctions are marked, a free outgoing junctor relay group OGRGA1 to OGRGBN is selected and a connection established thereto from the register. The translator is seized again and meter free information is transferred from the translator to the outgoing relay group. Following receipt of the exchange code digits (2 or 3) a router control (say RCX) is selected and it extends its identity signal through the register and junctor connector to the outgoing relay group, which primes the network stages RSA1 to RSA6. Markings are then extended from the distributer switches DSA1, DSA2 and in accordance with the self steering principle a route is selected. The router control releases and the register transmits the stored digits to the distant exchange. Incoming call.-On detection of an incoming call the incoming junction transmission relay group ITRG1 to ITRG24 transmits a delay sending signal to the distant exchange. When a free register has been selected and connected to this relay group the delay sending signal is terminated and a connection is established generally along the lines of an outgoing call with the path finding operation effected in the same direction through the network.