Patent GB-840939-A (GB)
Title: Improved automatic telephone system with paging equipment
IPC: H04M11/02
Filed: 1957-10-28
Abstract: 840,939. Paging systems. SVENSKA RELAFABRIKEN A.B. Oct. 28, 1957 [Oct. 30, 1956], No. 33608/57. Class 40 (4). An automatic system providing normal connection between subscribers has a paging system which can be taken into use by a subscriber sending a predetermined digit. The paging system remains operated until the call is answered or abandoned. If the call is answered the connecting link used by the answering station is released and a marker connected from the answering station to the calling station over the connecting-link first seized by the calling station. A calling subscriber at station A of the type described in Specification 835,965, depresses keys 0-1 according to the number of the wanted station, the first digit seizing a free connecting-link, according to which of relays M9-M13 is operated, by operating the relevant select magnet N1-N5. One of the two registers is also seized by operation of SN1 or SN2. The hold magnet BO corresponding to the calling station 100 also operates to complete the connection to the register. The digits are entered in relay chain R6-R9 in the manner described in Specification 823,655 and transferred to chains R11-R14, R16-R19 and R21-R24. The register then seizes the marker if free to energize hundreds, tens and units relays such as H1, T0, and E9 according to the number of the wanted party and a path is established through the cross-bar switch in known manner to the wanted station. All relays release other than the two hold magnets, say B0 and B9, and a holding relay SN5 in the connecting link relay set. Release is effected by the calling subscriber operating restoring key B. Paging equipment. The calling party depresses key 0. This digit is stored in relay chain R11-R14 and causes operation of special code relay R4. R4 energizes R25 and restores relay chain R11-R14. The number of the wanted subscriber is then sent to the register and stored as before. Relay R5 then pulls up to energize the appropriate hundreds relay P7, Fig. 3, in the paging equipment. The units and tens digits set the select and hold bars, PS, PB, respectively, of a cross-bar switch to light the paging lamps. R5 energizes one of relays P1-P5 according to which connecting link has been taken into use. R5 also energizes P6 which busies the paging equipment until the call is answered or abandoned. R5 also releases the register and marker as if the call were completed. The paged person answers by depressing a key 9 at any station. This digit is received by the register to energize code relay R2 which shunts the hold magnet of the answering station to release the connecting link seized by the answering station. However, R2 operates M5 in the marker so that the identity of the answering station is retained. Relay R1 releases slowly to operate select magnet N1-N5, Fig. 1, in the line finder-final selector, corresponding to the connecting-link indicating relay P1-P5 operated in the paging equipment. Connection is then established by the marker to the answering station, P6 restoring to release the paging equipment.