1295491 Automatic exchange systems NORTH ELECTRIC CO 5 March 1970 [12 March 1969] 10638/70 Heading H4K In a toll switching centre, all calls are routed via a toll recording trunk which is instructed by an automatic calling number and calling class identifier as to whether an operator should be called in to obtain data necessary for routing or charging the call. Call details are stored in a memory throughout the call, An operator can amend or add to these details at any time whenever she is called in by the trunk, the existing details all being displayed on a lamp panel at her position. At the end of the call the trunk calls in AMA equipment for printing out call details and charges. The latter may be immediately notified to the calling or called party (e.g. on transfer charge calls). The trunk may call-in an operator at periodic intervals during a call so that she can, for example, demand more fees on a coin box (which may be the calling or called party) call. She may also be called-in periodically during repeated attempts to set up a person-to-person call. The system is distinguished from U.S.A. Specification 3,341,661 in that the same trunks are used irrespective of the type of call. The class of service information incorporates "origin'' and "type" categories of which the former refers to the particular location within the area served by the system from which the call emanates and the latter refers to for example coin calls, non-coin calls, hotel calls, &c. The various types of call possible with the system are enumerated below. Hotel 1 + seven or ten digit call.-A calling line is connected via the finder stages SLA, SLB to a subscriber orginating trunk SOT (path A) and then to a register Reg-O (path B). When sufficient digits have been received Reg-O seizes a translator TNS which causes a sender SDR-O to signal a group selector marker GSM to complete a path (D) between SOT and a free toll-recording-trunk TRT-O in this case a long distance 1 + sent paid call. The trunk then calls in a toll register Reg TT into which the contents of the originating register are written in response to a backward signal transmitted by Reg TT, via a cross-bar type register connector RRL. Thereafter the latter seizes buffer store IBR (path F) so that the numbers and a three digit class of service code (category) of the calling line can be obtained by an automatic identifier ALI which reverts a tone over the connection and through the subscriber's line circuit to a core translator. Once this data is recorded in the buffer ALI releases. The buffer insets the calling line data into a core matrix memory MEM (path J) and commands the register to transmit the called number data to a related compartment of the memory together with the register's own identity and a progress word which indicates that this is a new call. The ferrite core memory can store data for up to 30 TRTs and checks each incoming data item for parity. The memory logic (basically relay type) determines that there is insufficient data for setting up the call with the aid of a class of service evaluator CAT DEC and so notifies the TRT-O that it should release the registers, sender and buffer and should seize a toll position control circuit TPC via, if necessary, a queuer and the toll desk connector (path M- control signals to marker; cross-bar path N- signalling path to toll control). The TPC reverts a signal over by path O to demand that all the data pertinent to the call be transmitted in synchronous pulse fashion from memory to lamp displays in a toll desk TSD attached to the TPC. From the display the operator deduces that the individual number of the hotel guest initiating the call is necessary in order that the call may proceed. She obtains this orally and keys it into memory whereafter all the operator equipment releases. It now merely remains to the toll trunk to retrieve the called number from memory via a code converter CSC and a newly seized outgoing register/sender REG-I, SDR-I in order that the call may proceed over a suitable outgoing trunk (path U). When the called party replies a clock is connected to memory so as to record the start of the call. When the call terminates (both parties) the switch train releases but, prior to its own release, the TRT again calls in the clock whereafter the contents of the memory including a charging-rate (metering rate) word are destructively read-out to AMA equipment (TRO, PP, &c.). It should be noted that before data is transferred between a trunk, the memory and a toll desk, preliminary signalling occurs to indicate the function, i.e. progress of the call, to which the subsequent data relates. Other call sequences.-With reference to the foregoing description of a hotel 1+ call, the operator's panel shown in Fig. 5 and the sequence description set forth hereinafter, the system's operation for other types of calls will become apparent. Non-coin premium call.-Calling party dials "0-419-468-2420". Digits received and stored by Reg-O, which connects to SDR-O and TNS. SDR-O establishes connection to TRT and Reg TT and marks for a "premium" call. (TNS releases.) Reg TT receives and stores called number from SDR-O. Reg TT calls buffer register and ALI and passes first category digit indicating "0+" call. ALI gives buffer the calling number and second and third category digits indicating local, non-coin sub-station. (ALI releases.) Buffer register sends category code and calling number to memory. Reg TT sends called number to memory. (Buffer and Reg TT release.) (Reg O and SDR-O release.) TRT generates "new call" signal to TSD link marker. TSD link marker identifies calling TRT-O and gets queue "class" from memory category decoder. TSD link marker establishes connection to TSD. TRT-O scans MEM and passes signals to TSD to indicate kind and status of call. "ACS" access lamp on. "CLD" lamp on to display 7 or 10 digit called number. "Release FWD" lamp on. "Time ST" lamp on (red, to denote that timing has not yet started). "Non-coin PPCS" lamp on to denote person to person, collect or special information with a 0+ call. Home area code lamp on (216). (TSD link marker releases.) Operator obtains details of call and marks "class-change." Operator presses "Person Paid" key. "Person. Paid" lamp goes red, then green. MEM scan signals "Class-charge" stored. Operator starts forward connection. Operator presses "ST" "start" key. "Release FWD" lamp goes dark. CSC sends called number to Reg 1, which connects to SDR-I and TNS. SDR-I establishes connection to OG trunk and out-pulses required digits. (Reg 1, SDR-I and TNS release.) "Offhook" signal sent from called office. "CLD" lamp goes dark. Operator obtains called party and starts timing. Operator presses "Time ST" key to start timing the call. MEM scan signals "Answer Time" stored. "Time ST" lamp goes green. Operator releases TSD and ASW, BSW and CSW switches. Operator presses "Pos Rls" position release key. All lamps go dark. On completion of call, TRT causes "disconnect time" to be stored in memory. TRO is connected and all billing information is sent to the tape punch. Coin station call.-Coin customer dials "1-419-468-2420". Coin "class" mark and digits received and stored by Reg- O, which connects to SDR-O and TNS. SDR-O establishes connection to TRT-O. Reg TT is seized. Reg TT receives "Coin" mark and called number from SDR-O. (REG-O. SDR-O and TNS release.) Reg TT calls buffer register and ALI, and passes first category digit indicating "1+" call. ALI gives buffer the calling number and second and third category digits indicating local coin substation. (ALI releases.) Buffer register sends memory the category code (3 digits), calling number (7 digits), and class of call type code (2 digits), indicating coin, station-to station, sent-paid call. Reg TT sends called number to memory. (Reg TT and buffer release. ) SDR-O causes initial coin to be refunded and releases. Memory category decoder signals TRT-O to link to call timer and conditions TRT-O for rate finder scan. TRT-O generates "new Call" signal to TSD link marker. TSD link marker identifie calling TRT-O and gets queue "calls" from category decoder. Rate finder receives calling office code and called area and office codes from memory and causes rate code to be stored in momory. (Rate finder releases.) TSD link marker establishes connection to TSD. TRT-O scans MEM and passes signals to TSD to indicate kind and status of call. "ACS", "CLD", "Station Paid" (green), "Release FWD", "Time ST" (red), "Coin STA" and home area code lamps on (216). Initial charge and period display. "Time" lamp on. Rate decoder receives rate code and one indication from MEM and sends signals to TSD for display of initial period charge and minutes. (TSD link marker and RDC release.) Operator obtains coin deposit for initial period and starts forward connection. Operator presses "ST" key. "Rls FWD" lamp goes dark. REG-1 is seized. CSC sends called number to REG-I, which connects to SDR-I and TNS. SDR-I establishes connection to OG trunk and out-pulses required digits. (REG-I, SDR-I and TNS release.) Operator listens for first ring-back-tone and releases the TSD, ASW, BSW and CSW switches. Operator presses time start key and "Pos Rls" key. All lamps go dark. "Off-hook" signal from called office causes "answer time" to be stored in memory and starts timer. Disconnect before the end of the initial period causes coins to be collected, and "disconnect time" to be stored in the memory. TRO is connected and all billing information is sent to the tape punch. Coin recall-notify.-18 seconds before the end of the initial period, a timer (which is actuated by 6 second pulses) sends a coin collect in-band signal to the coin telephone. 6 seconds before the end of the initial period, timer causes TRT-O to generate "recall" signal to the TSD link marker. TSD link marker identifies calling TRT-O and tests idle positions. TSD link marker establishes connecti