Patent GB-498560-A (GB)
Title: Improvements in or relating to telephone or like exchange systems
IPC: H04M15/08
Filed: 1938-01-18
Abstract: 498,560. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. Jan. 18, 1938, No. 1670. Convention date, Feb. 22, 1937. [Class 40 (iv)] In a system comprising a number of different equipments which require information as to the identity of a substation taking part in a connection, automatic substation identifying equipment is provided and, in response to a call from equipment requiring the information, identifies the substation and transmits the information. The various equipments requiringinformation may be automatic ticketing machines, toll operators' number checking equipment and false ormalicious call indicator equipment. In the system shown in Fig. 1, calls are set up over 1LF, 2LF and 1GS under control of a register - controller RG (1) to a local subscriber over 2GS, FS, (2) to a toll operator OC over junction circuit OJC1, and (3) over OJC2 to an exchange provided with automatic ticketing equipment ATC. After recording the called number and other information, the ticketing equipment sends back a signal via repeater SRP to equipment 1CC which by means of switches 1FF, 1CF, as described in Specifications 440,348 and 484,568, identifies the calling line and transmits the number to the ticketing equipment. If the toll operator requires the information, she presses a key to connect up an indicator TCT which sends back a request signal to ICC. In a similar manner, a false or malicious call indicator FCI on a false call or on a signal from a called party subjected to annoyance, sends a signal to the identifying equipment and receives the calling number. Different calling signals may be sent bv the various equipments. French Specifications 43765 and 722,379 are referred to in connection with false or malicious calls and toll operators' numberchecking arrangements are described in detail below. Seizure of incoming junction circuit and response by tolloperator. Relay] pulls up over the c wire followed by D and K, whereupon ringing tone from RTL is sent back over the calling line and calling lamps CL are lit. When a jack OJ is plugged, sleeve relay S1 operates C and G, relay K falls back and ringing tone is removed. Supervisory relay S is connected across the junction. If response is delayed, relays A and B are operated in succession over timing cam 14 and complete an interrupted circuit for F which flashes the calling lamps and a supervisor's lamp CPL. Identifying the calling party. The operator throws key IK operating start relay Fs of switch SM1 which hunts for the junction. Test relay T stops the switch and relays Ts and Cn pulls up, whereupon 50 # A.C. from leads ACS is connected to transformer TR1 in the junction circuit for a period determined by the slow operation of Gt and slow release of Ts which follows the release of T by Gt. The A.C. signal is sent over a simplex circuit from grounded bridge BC and causes the transmission of the calling subscriber's number as voice frequency trains from identification equipment in the originating exchange, as described in Specifications 440,348 and 484,568. When Ts has released, the secondary of transformer TR1 is connected over rectifier RC to relay S2. The indicator comprises lamps selected by digit registers Aa ... Ad, Ba ... Bd and so on connected up in turn by a back-stroke distributer SM2 stepped by relay Ln operated by Lm energized throughout each train. On operation of S2 by the 1st impulse, Ar pulls up and operates the 1st relay Dr of a counting chain and on relapse of S2 which is shortcircuiting Br, this relay pulls up. On the 2nd operation of S2, Cr pulls up and Ar, Br relapse, whereupon the 2nd chain relay Er, hitherto shunted by Ar, pulls up, Cr relapsing at the end of the 2nd impulse. The cycle of operation of Ar-Cr is repeated for each pair of impulses, chain relays Fr, Gr being operated on the 3rd and 4th impulses and relays Hr, Ir on the 5th and 6th. Relay Hr releases relays Dr, Er and Ir releases Fr, Gr so that Dr ... Gr may be used for impulses 7 ... 0. When Lm relapses at the end of the train, a circuit is completed for one or two relays of the first register according to the condition of the chain, and Ln releases slowly to release the chain and step the distributer. When the units digit has been registered, Es pulls up in the locking circuit of the register and completes the lamp circuits of all the digits. When the operator releases key IK, relays Cn, Gt fall back and the registers release. Release. When the calling party hangs up. relay S in the junction circuit falls back and M pulls up in series with the low resistance winding of S1 and the cord circuit supervisory lamp which thereupon glows. Relays H, Rc. Rf pull up in turn and I connected to slow interrupter 12 flashes the supervisory lamp. Release is under control of the operator so that she may identify the calling party even after he has hung up. Recall by calling party before clearance by operator. Relay S re-energizes and on the release of Rf, relay R replaces interrupter I2 by a quick one 13 so that relay I rapidly flashes the cord-circuit lamp.