Patent GB-999292-A (GB)
Title: Telephone systems including line identifying apparatus
IPC: H04M15/34
Filed: 1961-12-14
Abstract: 999,292. Automatic exchange systems. WESTERN ELECTRIC CO. Inc. Dec. 14, 1961 [Dec. 16, I960], No. 44747/61. Heading H4K. In a system in which all calls are recorded at a central exchange and at least one PBX is connected to this exchange, provision is made whereby when calls of a certain class originate at an extension of the PBX, identifying means are associated with the connection so that the directory number of the particular extension is recorded instead of the PBX directory number. This arrangement is of particular advantage in an S.T.D. system having automatic branch exchanges connected therein. In the system shown, each PBX (Fig. 1) is connected over a 100 trunks to line link frames LLF at a central office (Fig. 2) and each PBX is also connected to a central-office identification-circuit over a separate signalling channel, i.e. 17-0 (Fig. 3). A calling extension in the PBX is connected over a free trunk to an LLF and the dialled digits are stored in a register thereat. If the call is one which only requires PBXidentification, relays RP and SH followed by RPP come up and the identity of the calling trunk as indicated by its appearance in an LLF is signalled via a marker over wires f (TN, U), vg, vf and hg to a transverter. In response to an operating ground on f (TN, U), relays F(U) and F(TN) corresponding to the LLF concerned will pull up as also will appropriate relays VG, CL corresponding to a particular vertical group (defined as, five adjacent vertical files in a frame). Party line calls.-For an incoming call from a ring party ground is applied to rp and RPI pulls up thereto. Consequently one of the relays RFo-RFn operates and ground is thus extended over contacts of relays VG, CL, RF and jumpers, JR1 say, to a " translator " start relay A. The latter brings up " translator " connector 7a so that the horizontal group and vertical file information on leads hgl and vf1 can be applied to " translator " 7. The " translated " information comprising the office code and the thousands, hundreds, tens and units digits of the calling line is then applied over wires 7-3 to a directory number register 9 of the automatic message accounting (AMA) equipment. If the call is from a tip party, however, relay TP (marker), relay tree T (transverter) and a relay B are operated and a different " translator " is thereby brought into use. For a PBX call which requires extension identification, class of service relay CID (marker) and an auxiliary route relay LH operate in addition to RP and consequently TP followed by TP<SP>1</SP> come up. Hence one of relays TFo-TFn operates in addition to VG, CL and a relay C pulls up to associate " translator connector 8a with the transverter. Ground on four of the output wires of cable 8-3 indicates the number of the calling PBX (TH and H " digits ") and the number of the calling trunk from that PBX (T and U " digits "). The former " digits " cause two of relays HD and THD to come up with subsequent energization of a connector relay PPC, e.g. in 16-0, whereby the signalling channel 17-0 to PBX00 is connected to a sender 14a. The calling trunk number " digits " are entered into register 12 and then transmitted over channel 17-0 to cause the operation of two of relays UD, TD in a trunk selector 19. Positive battery 19p (decoupled from holding earth by rectifier D) is thereby reverted over the sleeve connection of the selector/line finder banks connected to the selected trunk circuit and a line identifying relay ID will go up to apply an earth marking to appropriate wires in a marking multiple 22. Common encoder 24 in response to the marking on a Tn or Un wire encodes and registers the four digit extension number in sender 25 which then outpulses the number over channel 17-0 to a receiver 14b (Fig. 3). This number together with the office code portion of the extension directory number as indicated by an earth (contact 3) in connector 16-0 is sent over cable 8 - 3<SP>1</SP> to AMA register 9. If the extension number is not received by the central office within a given interval, timer 26 operates and brings up relay A<SP>1</SP>. The latter " releases " relay tree T and transfers the call recording operation to relay tree R as described in the previous paragraph.