Patent GB-1329054-A (GB)
Title: Centralised metering system for automatic telphone exchanges
IPC: H04M15/04
Filed: 1971-04-19
Abstract: 1329054 Automatic exchange systems INTERNATIONAL STANDARD ELECTRIC CORP 19 April 1971 [26 March 1970] 24511/71 Heading H4K In a metering system for a Pentaconta (R.T.M.) cross-bar switching system, controlled by a stored programme computer, each trunk circuit is provided with a cell in one of a plurality of centralized memories wherein data pertinent to charging a cell extended via the trunk circuit is temporarily stored pending transference to a ticketing centre. The data comprises calling subscriber indentity, metering rate and call duration. Apart from the last mentioned, the data is transferred into the temporary store during the setting up of a connection from the caller to the trunk circuit in response to the reception and processing of dialled digits in a register allocated to the call. Particular description:-A calling line A is connected via primary selector SL to a junctor JE and thence via a not shown register connector to a register wherein all dialled digits are recorded unless the initial digit(s) indicates a toll call. In the latter case, application is immediately made for a toll circuit (like J) and further digits are transmitted on to a toll exchange which sets up the call but reverts metering pulses to the toll circuit for recording locally in a manner akin to that described below. With a local or trunk call, the register obtains a translation from (T) of the initial digits and causes a group selector marker MG to set up a path through group selector SG to a suitable outgoing junctor J. Meanwhile the translator T supplies a control circuit CS seized by the register, with the metering rate appropriate to the call (relay PT), the originating marker MP provides the caller's class of service and thereby the identity of the caller's line identifies IDA (relay IB) and the group selector marker provides the identity and type of the chosen outgoing junctor and thereby the identity of the store 6 (Fig. 4) containing the metering cell pertinent to the call (relay ET). Each of the stores has a scanner EX which sequentially interrogates the control circuits by stepping through a shift register R and then applying +48 volt battery via gate D to a lead FS extending to the control circuit under consideration. Provided the relevant ET and IB relays have operated in CS, the lead FS is connected through to lead FI extending to a line-identifier selection circuit CX. The latter is provided to ensure that an identifier is connected to only one central store at a time (it being remembered that a plurality of control circuits may be trying to access the identifiers simultaneously in view of the multiple provision of central stores). Circuit CX contains a relay contact chain CCXn2 which effectively determines the priority allotted to the stores so that, the +48 potentials appearing on any of leads FI cause the associated CC relays to come up (over their left windings) in series with the FI and FC leads extending to the control circuit. However all CC relays except that pertaining to the store of highest priority fall back thereby locking out all the control circuits handling lower priority stores when selection circuit busy relay P operates. Over the right hand winding of the remaining operated CCN relay, position potential traverses the control circuit and causes the shift register in the scanner of the highest priority store to stop. Negative potential is then put on lead FS by gate I so bringing up AX via rectifier DB. AX brings up BX and causes earth to be extended from lead FI to the C wire of the caller's connection. The earth affects the cores of the tone identifier thereby to operate a set of code relays IDA. Consequently identity of the caller is sent over bus LA while the metering rate and outgoing junctor identity (although this is not stricly necessary due to the one-to-one provision of metering cells in the central stores) are sent over bus LE to store 6. The correct cell in the latter is obtained by virtue of an earth extended forward from the control circuit over the C-wire to the outgoing junctor where it serves to trigger scanner 7 into energizing writein circuit 2 when the scanner reaches the cell associated with the outgoing junctor. Having checked the parity of the received data the store restarts the shift register thereby causing CS, CX and the identifier to release when negative battery is removed from FS. Further supervision of the call is vested in the outgoing junctor which "advises" its cell in the store of the occurrence of toll metering pulses and/or of the end of the call. In either case the charge for the call is determined by a local arithmetic unit and stored in the cell pending transfer to a tape recorder 4 or teleprinter 5 for subsequent billing to the calling subscriber.