Patent GB-1410323-A (GB)
Title: Telephone service observation appliance
IPC: H04M15/04
Filed: 1971-06-09
Abstract: 1410323 Automatic exchange systems DIRECTIA DE TELECOMMUNICATII A MUNICIPIULUI BUCURESTI 8 Sept 1972 [9 June 1971] 19756/71 Heading H4K A telephone service appliance adapted to be connected to each of a group of telephone lines which are to be monitored can adapt itself to suit the type of exchange (e.g. crossbar or rotary) and is arranged to be supplied with power from the exchange battery, to select a line to be monitored, to identify the subscriber to determine his type of service, e.g. his exchange type, to determine the time and duration of a call to verify the tariff for that call in accordance with its distance and duration and to print call data relating to the above. In this abridgment a number in brackets following a reference numeral gives the number of a figure (not shown) showing details of the block denoted by that reference numeral. The applicance shown includes 100 subscriber circuits 1(2) arranged in ten groups CL1-CL10 of ten. Each group is served by a group connection circuit CCC1-CCC10 which includes a line selection and connection circuit 2(3) which includes a relay allotting chain for selecting a line of the group in response to selection of a group by a group selection and connection circuit 5(6), a circuit 3(4) which sounds an alarm if metering pulses arrive while the handset is on hook and counts those pulses and which by an array of strapped terminals determines whether the subscriber is an ordinary subscriber or a special subscriber, e.g. the auxiliary party of a party line or a subscriber connected to a different type of exchange and transmits line state signals relating to the selected line, and a line priority and group connection circuit 4(5) by means of which lines of the group can be set to higher priority. A selected line is connected to an automatic monitoring and recording unit Rg including a common control 13(11), a printer 12(14), a counter 7(8) arranged to count the pulses of the first digit and the digits or in the case of special service calls the pulses of each digit, a store 8(9) in which the digits are stored and which also receives the indentity of the caller and his class a service from an identifier, a circuit 10(12) for selecting periodic charging pulses during local fixed charge calls and initiating an alarm and a special service signal and metering pulse detector 11(13). The identifier 6(7) includes two stepping switches each driven by a pulse generator and arranged to step round to a marked group or line wire respectively. Each subscriber circuit 1(2) includes two counters which receive via diodes positive and negative metering pulses respectively relating to outgoing and incoming calls and accumulate those pulses if the automatic unit Rg is busy. Various checks, &c. are performed in the control 13(11), e.g. to check that metering pulses exist, to check that they are being debited to the correct subscriber, to check that clock signals are arriving at the printer and to check that various relays do not remain set for an abnormally long period. If faults are detected sound and visual alarms with appropriate indications are triggered. The appliance is during normal working connected to each subscriber line and off-hook signals are not forwarded to the exchange until the appliance has prepared itself to receive dial signals.