GB2032226A - A Centrally Controlled Telephone Exchange and Method of Controlling Same - Google Patents

Abstract

Stores associated with the central control unit and/or sub-control units have blocks of storage positions assigned to switching operations which include common sequences and/or switching steps to which are assigned further storage positions to which said blocks have common access to minimise the storage capacity necessary for such common sequences and switching steps.

Description

SPECIFICATION A Centrally Controlled Telephone Exchange and Method of Controlling Same.

This invention relates to a centrally controlled telephone exchange, in partiular in a centrally controlled PBX telephone system, and to a method of controlling such an exchange.

Such a PBX system can have a speech path coupling network via which, for the establishment of connections, takes place the exchange of switching data, address commands and control commands between control devices provided for various functions (for example for the interrogation of dialling sets and/or connection sets) and current state stores which are associated with respective connections and can be modified in respect of each individual connection state. An exchange of the system may also have data transmission line groups which facilitate the exchange of data within exchanges.

Consecutive switching operations, such as connecting, disconnecting, switching-over, dial reception, storage and analysis which are required for the establishment and disestablishment of connections and which are instigated by a central control unit and stores assigned to this central control unit, can each be controlled by means of function flow sections which are at least partially common to similar switching operations.

German specification No. P 26 47 404 discloses such a centrally controlled telephone exchange system, specifically a centrally controlled PBX telephone system. A plurality of different sub-control units are provided, for example a sub control unit for subscriber circuits, a sub control unit for exchange sets, a sub control unit for dialling store sets, a sub control unit for exchange telephones with connection sets, and sub control units for other functions. The logic linking of the data exchange is carried out via the groups of data transmission lines and connections sets which interconnect the central control unit to each group of data transmission lines. Other groups of data transmission lines are provided for the execution of other functions.

According to a first aspect of this invention there is provided a centrally controlled telecommunications exchange having a store assigned to the central control unit or to a subcontrol unit and for use in controlling switching operations which include identical switching steps and/or function flow sequences, said store having blocks of storage positions respectively associated with said switching operations, each said block containing control data which, on operation of the store block, effects the relevant switching operation at least partly by operating further storage positions containing control data for effecting said switching steps and/or function flow sequences and to which said blocks have common access.

According to 'a second aspect of this invention there is provided a speech path switching network, and exchange of switching data, address commands and control commands, transmitted across the speech path switching network for the establishment of connections, between control devices provided for different functions, and data stores which can be modified in respect of each individual connection state and data stores which cannot be modified in respect of each individual connection, with groups of data transmission lines which facilitate the exchange of information.

Embodiments of this invention will now be described by way of example, with reference to the accompanying drawing in which the sole figure is a schematic block diagram of a part of a PBX telephone exchange to which the present invention can be applied.

Referring to the drawing, in a centrally controlled PBX telephone system, subscriber stations N1 to Nn of the PBX system are combined, in accordance with a predetermined grouping, to form groups of subscribers GT1 to GTm (only GT1 and GTm being shown) and each subscriber group GT1/SK (uni) is also assigned a special group of exchange line sets AVSx a group of dialling stores WSx, and one or more than one service telephone BFx in dependence upon the size of the group of subscribers. Of course the line set, dialling stores or switchboards in other groups can also be used. This is dependent upon the grouping and merely indicated in the switching network SK by means of intermediate lines 1 to 6. Each subscriber group can be split into further subscriber groups or sub-groups.By way of example, the drawing shows that the group GT1 could consist of subscriber'sub-groups G (1) to G (n). In the case of subscriber group GTm, the sub-groups have not been shown in order to simplify the drawing.

The switching network SK is divided into sections in accordance with the division into subscriber groups GT1 to GTm, although in the drawing this division has been specifically shown only for the subscriber group GT1 and the corresponding section of the switching network SK is referenced Ni. The other sections of the switching network SK for the other subscriber groups and for devices which have not yet been specified here has not been shown, for the sake of clarity in the drawing, and the remaining portion of the network SK is simply referenced N.In accordance with the division into subscriber subgroups, the network section N1 has been further divided into a plurality of switching network sections N1 (1) to N (n). In this respect attention is drawn to the German Specification No. P 26 02 159.0. It is clear that the switching network portion N likewise possesses or can possess a plurality of parallel switching network sections respectively associated with subscriber subgroups.

Each subscriber group, e.g. the subscriber group GT1, which can consist of a plurality of subscriber subgroups, is assigned specific central devices such as for example a group of line sets (only one of which, AVSx, has been shown), a plurality of dialling store sets (only one of which, WSx, has been shown) and a plurality of service telephones (only one of which, BFx, and its associated connection set VMSx being shown).

Each other subscriber group likewise possesses a number of line sets, dialling store sets, and service telephones with connection sets, the number being dependent upon the anticipated traffic.

In dependence on the traffic and other requirements, it may be unnecessary to assign at least one separate service telephone to each subscriber group, as the service telephones assigned to one subscriber group can be arranged so as to be used for other subscriber groups. The subscriber circuits within a subscriber group, such as GT1, can be connected via respective connection lines to a sub-control unit TSt for subscriber circuits. This subscriber control unit TSt is assigned switching means which, as will be described below, determine by cyclic scanning by this sub-control unit TSt, whether the switching state of the subscriber circuit which is currently being interrogated has changed or not.If a change has occurred and a switching process needs to be carried out, an exchange of information with central control unit ZS1 is carried out via data transmission line group B1 assigned to the subscriber group. The data transmission line group is provided for the coded transmission of information of any type and might use PCM transmission as in a PCM-ring line system.

In this respect it should be noted that a second central control unit ZS2 shown is merely intended to act as a substitute control unit in the event of a fault occurring in the central control unit ZS1, so that in the following description relating to only one of the two central control units, it is the central control unit ZS 1 that is being considered.

The determination of whether the data transmission line group B1 is connected to the central control unit ZS1 for the purpose of information and command transmission between the sub-control unitTSt and the central control unit ZS 1 is dependent upon the nature of the switching process which is to be carried out and its priority within the hierarchy of switching processes. The transmissions via line group B1 between units TSt and ZS1 are effected by the activation of appropriate wires of the data transmission group B1 during a scanning cycle by the central control unit ZS1 via allocation and connection device Anl and data transmission lines DS.

For the same subscriber group GT1, all the line sets AVSx are assigned a common sub-control unit ASt. In the case of this sub-control unit, when changes in state occur which can be determined by a last-look process, (the line sets are consecutively scanned by the central control unit ZS1) an exchange of information takes place with the central control unit ZS1. If a line set associated with the group GT1 is used for the establishement of a connection to another subscriber in another subscriber group, it may be necessary to carry out an additional exchange of information with the sub-control unit (TStm) for the subscriber circuits of the other subscriber group to which this other subscriber belongs.This is carried out, for example, by coupling the data transmission line group B1 via the allocation and connection device Anl and the allocation and connection device Anm and via the data transmission line group Bm to the sub-control unit TStm (which has not been specifically illustrated but merely indicated generally by its reference letters) under the control of the central control unitZSl.

The drawing also shows that, for the establishment of incoming and outgoing exchange connections, the line set AVSx provides access to exchange lines, e.g. ALx. Via the switching network section N1 (1), which has been shown as consisting of only two stages in the present example, but can consist of three or more stages, this line set AVSx can be connected to any entitled subscriber in the system and possibly also to a cross-connection set QV which leads to a subsidiary system.

In order to receive dialled information, the illustrated dialling store set WSx for the subscriber group GT1 can be connected via the switching network SK to a subscriber circuit or line set or cross-connection set. In dependence upon the nature of the connection to be established, connection establishment consists merely of connection via either the output 7 of the dialling store set WSx or a looping-in of the dialling store set WSx, as is known for systems with inverse grouping. The dialling store set WSx is for this purpose provided with two outputs 7 and 8 which are connected to the switching network.

The connection set VMSx of the service telephone BFx is likewise connected by two outputs 9 and 10 to the switching network N1 (1). In this way the connection set VMSx of the service telephone BFx can be connected to a line set or dialling set and can also be looped into a connection.

The dialling store sets WSxfor each subscriber group-here the subscriber group GTi-can be assigned a sub-control unit WSt, and the connection sets, e.g. VMSx can be assigned a sub-control unit VSt. These sub-control units can be connected via the data transmission line group B1 and the allocation and connection device Ani to the central control unit ZS1 and, via further allocation and connection devices, to other data transmission line groups and sub-control units.

If the switching network SK consists of mechanically operable crosspoints, house sets HSx are provided, which, for each subscriber group, are likewise assigned a sub-control unit HSt, as indicated in broken line. If, as is assumed to be the case in the present example, the switching network SK is provided with electronic crosspoints, for example thyristors, holding sets such as HS 1, HS2 are provided for the switching network sections N1 (1) to N1 (n) and holding sets such as HSn, HSS, HSx, HSy for the switching network portion N and switching network BK, and also undertake the functions of house sets. The difference in use as a house set consists in the different manner of connection to the switching network.

The holding sets are divided into groups. The holding sets HS1, HS2 of the switching networks N1 (1), N1 (n) are assigned a sub-control unit HStl via which these holding sets canbe connected via the data transmission tine group B1 and the allocation and connection device Anl to the central control unit ZS1 and, via the data busbar DS and one of the further allocation and connection devices, e.g. Anm, to other data transmission line groups, e.g. Bm, for the exchange of information with other sub-control units. The exchange of the information is dependent upon the scanning cycle and upon the values and priorities of the handling of processes.

In the above we have discussed only the subscriber groups and their associated line sets, dialling store sets, connection sets, and holding sets, and the data transmission line groups B1 to Bm associated with the subcriber groups. In addition to these data transmission line groups B1 to Bm for subscriber groups, data transmission line groups BSo and Bb are also provided for other groups of additional devices and line sets which will be described below.

Thus the group of additional devices and line sets associated with the data transmission line group BSo contains a plurality of conference connectors such as KV which are assigned a subcontrol unit KVSt which, via the data transmission line group BSo and allocation and connection device AnS, exchanges information with the central control unit ZS 1 and, via the data busbar DS and one of the further allocation and connection devices can exchange information with another sub-control unit.

In addition the group has a plurality of monitoring devices such as BD for traffic monitoring and testing during connection establishment, and which are assigned the common sub-control unit BDSt which also exchanges information and commands via the data transmission line group BSo. Moreover the group includes devices So, which are allocated a common sub-control unit SoSt, and also dialling store sets MS for a multi-frequency code (only necessary if the system is to be set up both for pulse dialling and for multi-frequency code dialling), which are assigned sub-control unit MSt.

It has been assumed that the dialling store sets WSx are provided for pulse dialling and the dialling store sets MS are provided for multifrequency code dialling. If only multi-frequency code dialling is provided in the system, the dialling sets, e.g. WSx, are arranged only for multi-frequency code dialling and the sets MS are dispensed with. In dependence upon requirements, the sets MS can be connected to subscriber circuits, line sets, cross-connection sets and the like for dialling reception and possibly code conversion of dialled characteristics.

The transmission line group BSo can be assigned a group of cross-connection sets CV or a plurality of groups of cross-connection sets, e.g.

for various direction line groups, in which case each cross-connection set group is assigned a respective sub-control unit. The cross-connection sets QV are assigned the sub-control unit QSt.

Furthermore a plurality of data sets D can be provided for data dialogue across the switching network portion N. Data sets of this kind can be looped into a connection. These data sets D are assigned a sub-control unit DSt.

If the data exchange requires a connection to the data system, data sets DM are required which each possess an output for direct connection to the appropriate data processing devices DVA. In this way the devices provided for exchanging data across the additional switching network BK can be connected not only via the corresponding data transmission line groups but also directly to devices and/or sub-control devices of the subscriber groups in order to simplify information exchange and/or synchronisation in parallel connections.

The data transmission line group BSo can be connected via a corresponding allocation and connection device Ans both to the central control unit ZS1 and, via the data busbar DS and one of the other allocation and connection devices, to other sub-control units for the exchange of information and commands. Division of the switching network portion N has not 6een shown in order to simplify the drawing but it is clear that the switching network portion N can be divided up for this group of additional devices in a similar way to the switching network section N1 (1).

The drawing does not illustrate the store distribution and an advantageous store distribution which leads to a reduction in store positions compared with conventional systems will be described below by referring to a few examples. Here it has been assumed that for various situations in the course of connection establishment and in the course of connection disestablishment, specific function flows and specific switching operations will be identical in parts. As a simple example we will consider the situation in which a dialling tone is to be connected using identical switching steps commencing from various switching states.

Now each relevant store is divided up in such manner that for each possible different situation, i.e. for each possible (primary) switching state it acquires a plurality of store bits. At a store position for a specific switching state (the primary state) the commands which are required on the basis of this primary state must be stored in association with this state. The number of commands should be kept to a minimum, for example two to three. The execution of these commands leads to resultant states which are likewise stored in association with the primary state. The resultant states which are to be stored thus are to include all possible states which can arise as a result of the executed commands. each resultant state stored comprises the address of a new store position for another state.Thus it follows that by giving the parameter address of the store position assigned to the primary state, common switching steps each enable the operation of this store position. Thus a switching operation consists of a linking of different function flow sections, each section being determined by the operation of the appropriate store position. If the store division is optimal and the number of commands to be triggered in respect of each state is made as small as possible, the best possible exploitation of common function flow sequences is achieved.

It will be clear from the above that the addition of new facilities is simplified by the fact that already existing function flow sections can be further employed. Basically it is only necessary to jump into existing switching sequences by the incorporation of appropriate parameter addresses.

In the following a number of states are listed, each of which is assigned a store position which can be operated by means of a respective parameter address. The commands necessary on the basis of each state and the resultant states are referenced with small letters as follows:- a) first command, b) second command, c) first possible following state, d) second possible following state, e) third possible following state, f) continuation address, g) parameter address.

I. Callback is initiated from the calling speech station, and the originally called subscriber must be brought into the waiting state.

a) disestablish connection path b) release connection path c) establish callback connection path f) continuation address for resultant dialling operation g) parameter address for establishing readiness for dialling, dialling evaluation etc.

II. Continuation with the given parameter address (g). In association with this address are stored: starting state, command for reconnection of starting tone, address for establishment of readiness for dialling, address for dialling evaluation, address for the commands associated with the replacement of the receiver during dialling, address for a timer. The programme then continues with the continuation address (f).

Another example relates to a store position for input seizure, with connection of the dialling tone where a) connection of feed b) connection of dialling tone c) the address for continuation in the case of positive outcome d) the address for continuation in the case of a negative outcome f) the parameter addresses for the other possible operations dependent upon the executed commands and which can correspond to those referred to above under (g). As an alternative, however, another store position may have to be operated, namely when interception is required because the time limit has expired. A command for path disconnection, subscriber relay connection, and subscriber interception and a command for path release would be stored under this store position. A continuation address and a parameter address would also be given.

The difference between the continuation addresses and parameter addresses consists in that the parameter addresses are addresses with which store positions are operated which are assigned to states (primary), whereas the continuation addresses relate to addresses for operating store positions which relate to function flow sequences to be executed in parallel to (as a Dranch of) the primary states. Appropriate commands are provided for these function flow sequences. However, the parameter addresses and continuation addresses can be regarded similarly inasmuch as the store positions operated by means of these addresses are used, in the course of the linking of various function flow sections in different switching operations, for various switching steps which are common to the different switching operations.

Thus switching operations which differ from one another (different signal transmission) only in terms of initial switching states (seizure, dialling characteristic reception, conversation etc.) by virtue of an appropriate characterisation in stores assigned to the devices in use (for example house sets, exchange sets etc.) for connection establishment and dis-establishment, are each assigned a respective store block in a store assigned to the central control unit or sub-control unit. Each switching operation consists of a linking of various function flow sections and, depending upon the succession of switching states, also various switching steps. The store block in each case stores the parameter addresses (and also continuation addresses) for the consecutive function flow sections (disconnection of tones, operation of code receivers etc.) and switching steps (callback, switchover, connection of dialling tone etc.).

In this way, by having multiple exploitation of common function flow sequences and switching steps for various switching operations it is possible not only to save storage space but also to simplify considerably the handling of these switching operations and the insertion of new facilities into an existing system. The store positions required for the linking of the switching steps and function flow sequences only represent less the store positions than are required in existing systems.

Claims (6)

Claims

1. A centrally controlled telecommunications exchange having a store assigned to the central control unit or to a subcontrol unit and for use in controlling switching operations which include identical switching steps and/or function flow sequences, said store having blocks of storage positions respectively associated with said switching operations, each said block containing control data which, on operation of the store block, effects the relevant switching operation at least partly by operating further storage positions containing control data for effecting said switching steps and/or function flow sequences and to which said blocks have common access.

2. An exchange according to claim 1 wherein each said block contains a command, a resultant state, a continuation address and/or a parameter address.

3. An exchange according to claim 1 or claim 2 wherein the exchange has a speech path switching network, and exchange of switching data, address commands and control commands, transmitted across the speech path switching network for the establishment of connections, between control devices provided for different functions, and data stores which can be modified in respect of each individual connection state and data stores which cannot be modified in respect of each individual connection, with groups of data transmission lines which facilitate the exchange of information and wherein switching operations, such as connecting, disconnecting, switchingover, dial reception, storage and analysis which are required for the establishment and disestablishment of connections and which are instigated by a central control unit and stores assigned to this central control unit, can each be controlled by means of function flow sections which are at least partially common to similar switching operations.

4. A centrally controlled telecommunications exchange, said exchange being substantially as described herein with reference to the accompanying drawing.

5. A method of controlling a centrally controlled telecommunications exchange including the steps of assigning blocks of storage positions in a store, associated with the central control unit or sub-control unit, to respective switching operations which include identical switching steps and/or function flow sequences to which further storage positions are assigned, and effecting one of said switching operations by operating one of said blocks which operates the further storage positions containing control data for effecting said switching steps and/or function flow sequences included in said one switching operation.

6. A method of controlling a centrally controlled telecommunications exchange, said method being substantially as described herein with reference to the accompanying drawing.