Patent GB-1219416-A (GB)
Title: Improvements in or relating to telephone accounting and traffic analysis equipment
Inventor: FISHER DAVID GEOFFREY
IPC: H04Q3/545
Filed: 1967-11-16
Abstract: 1,219,416. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. 21 Oct., 1968 [16 Nov., 1967], No. 52199/67. Heading H4K. A call accounting and traffic analysis arrangement in an international trunk switching telephone exchange of the register-controlled type, and providing the gateway between a national and an international network, has a data processor which collects from buffer stores on a cyclic basis data relative to the condition of exchange equipment and which collects from a particular buffer store at the time of its production data indicative of dialled and routing information relative to individual connections without interrupting or delaying the establishment of connections in the exchange. As shown in Fig. 1, the international trunk switching centre ITSC may be electronic, semielectronic, or electro-mechanical and is preferably of the 5005 crossbar type described in Specification 1,003,404 in which each first stage router serves 100 outgoing junctions or 50 incoming junction and 50 bothway junction circuits. Each router has a number of registers and has access to one of a pair of router controls. In accordance with dialled information a router control obtains routing data by application to an international coder. To keep accounts the accounting and traffic analysis equipment has access to trunk and junction circuits, registers, router controls, and coders. The equipment employs two general purpose data processors DPA, DPB, of the kind described in Specification 1,192,371. The processors employ bulk storage on tape transports TT1 to TT4 with channellers TTC1, TTC2, and have duplex operated teleprinters TP1 to TP3 with a channeller TPC. The channellers govern connection of the processors with peripheral equipment by way of seven channels CH1 to CH7 for each processor, A and B. Channels CH4 and CH5 serve the tape transport bulk storage while channels CH6 serve the teleprinters. Channels CH1, by way of incoming event recorder control equipment IERC, obtain from incoming event recorders I/CER data from the incoming junction circuits and the incoming side of bothway junctions. There is a separate recorder I/CER for each router in the exchange and as each junction can have seized, call answered, or call cleared states, a 300-wire cable is needed from each router to its recorder I/CER. The processor charged with the function sets up the address of an event recorder it wishes to consult in control IERC arid receives data from the recorder in 13 words of 24 bits each. Each event recorder gives an indication if an event has occurred since the event recorder was last read by the processor. In a manner similar to the collection of data relating to incoming events data relating to outgoing events is collected over channels CH3 by way of outgoing events recorder control OERC and outgoing events recorders O/GER each with connection by a 300-wire cable to outgoing junction circuits of an exchange router. Channels CH2 by way of a scanner channeller SCANCHAN obtain access to any selected group of 24 scan points to determine their state. The data collected in this manner concerns events occurring in a specified period of time such as, for service purposes, the number of first and second attempts to establish a call by a router or a link marker; or for traffic recording, the number of times all circuits have been found busy, or the number of calls and average holding time for each register, sender, and coder.' Channels CH7 are shared between the system control channellers CONT CHAN which take 8 bits and the coder channellers COD CHAN which take 16 bits of the 24 bit channels. The channellers CONT CHAN have five 8 bit outputs corresponding to four general purpose registers and one special priority register. The priority registers PRA, PRB are used in programme interrupts to hold the priority level of the current programme and the priority of the programme for the task next in hand. Fifteen levels are indicated in a 1-out-of-15 code. Group control registers GCRA, GCRB govern the connection of respective data processors DPA, DPB, to channels CH1 to CH6. Comparators CMPRA and CMPRB cross-check the contents of the group control registers to ensure that only one processor has use of a channel at any one time. Channel select code is 1-out-of-6 leavin two bits free for a test for synchronism carried out in a test routine of the processors every 30 seconds. Signal registers SRA, SRB provide input buffers for control signals. Pulse generators PG1, PG2, provide 50 ms. timing pulses; and 30 second exchange control pulses are also supplied. Pulse generation is tested in the processors. These registers are also employed as buffers for operators' key sets for working test routines and data insertion. The message registers MRA1, MRA2, MRB1, MRB2, provide in each channeller a duplicate connection path between the data processors which path is employed in test routines and for a process of processor changeover. The coder channellers COD CHAN A, COD CHAN B, are associated with the coder output circuit COC and circuit address encoder CAE interfacial circuits. These circuits provide the processor with accountancy data relating to a call when a coder is taken into use in the exchange and provides routing information. When such call data is available an information ready signal IRS applied to the coder channellers produces a priority interrupt signal I(CCA) to the priority register of the processor handling this data. In response to the interrupt the processor connects to the channel to obtain the destination of the call, the associated routing information, and the address of the incoming circuit involved, the latter address being encoded at CAE by the address of the junction within the router (on lead CA) and the address of the register serving the call (on lead RA). Magnetic tape bulk storage equipment.-Data is stored in blocks comprising a variable number of storage elements with block headings at each end of a block. Each tape is split into files each storing data blocks of different type. Each tape in a first section holds a complete set of programmes including replicas of programmes stored in core stores of the processors; see Fig. 2. A second section of each tape holds daily accounting totals for all calls through the exchange, tapes 1 and 3 holding accounts of calls originating and terminating in the country of the exchange and tracks 2 and 4 holding accounts for transit calls. A third section of each tape holds 12 hourly records of own country originated international subscriber dialled calls on a route destination basis on tapes 1 and 3, and on tapes 2 and 4 holds 12 hourly records of automatic transit traffic on a per call basis. Tapes 1 and 2 each contain data from the scanner and the event recorders in a section to which fast access is assured by holding the working range of the tape close to the section. Incoming automatic calls.-One of the processors examines the incoming event recorders at one second intervals to determine changes and conducts an interrogation accordingly to make a record in its main core store along with the time of day to the second. Information presented from the coder channeller by way of programme interrupt is routed to the same processor and recorded in its main store. The processor main store has an "all routes busy" file kept up to date in this process. At intervals of one minute, or longer in periods of light traffic, this data is taken out of the main store in the processor and put in the tape bulk store. In updating the event and scan blocks on the tapes 1 and 2 the data is read off one tape and written on the other in alternate cycles. The data held in these blocks is incoming circuit identity, total number of seizures of the circuit, total of effective calls, total call holding time, current state of circuit, time of seizure of circuit for existing call, time of answer for existing call, and route destination of existing call. To settle international accounts the route destination file is kept, completed call information obtained during the updating of incoming junction circuit blocks being added to appropriate cumulative totals in the route destination file in the processor core store. This file records for each route destination the number of seizures, the number of effective calls, total call holding time, and total call duration time. With each updating the totals are lodged in the tape bulk store. With transit calls the data is stored for each call and comprises the call holding time, call duration, and the route to route destination. Outgoing automatic calls.-Outgoing events are recorded, without routing information, in the event blocks of the processor concerned, this data being transferred to bulk tape storage at intervals of one minute. For each outgoing circuit a record is kept of total number of seizures, total of effective calls, total holding time, current circuit state, time of seizure of existing call. Outgoing route performance files are kept for each international route and comprises the number of attempted calls and the number of effective calls, this file being obtainable at any time as a printout using a teleprinter. Processing of scanner data.-Service performance and traffic analysis files are kept from exchange data point scanning at a repetition rate of 50 ms., 200 ms., I sec., or 6 secs, according to equipment. Registers, coders, senders, and exchange routes have individual records of the number of times busy and total time busy for  traffic analysis, while for router controls and line markers the number of first attempt and the number of second attempt seizures is recorded in order to judge service performance. Account data production.-This is effected once every 12 hours, tapes 1 and 2 holding files in production while tapes 3 and 4 hold files for the preceding 12 hours, in alternation. When charging r