AU594243B2

AU594243B2 - A computer-controlled switching system, in particular a so-called key telephone switching system

Info

Publication number: AU594243B2
Application number: AU17688/88A
Authority: AU
Inventors: Rolan Roth
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1987-06-16
Filing date: 1988-06-15
Publication date: 1990-03-01
Anticipated expiration: 2008-06-15
Also published as: NO882662D0; AU1768888A; EP0295470A3; ES2050679T3; NO304769B1; ATE103447T1; EP0295470A2; DE3888578D1; NO882662L; EP0295470B1

Abstract

To transfer a call, the ringing signal is first of all supplied successively by the central control device (ZSt) to the individual terminals within a group of specially selected subscriber terminals according to the sequence defined in a list (L) in the customer data store (KD) until the call is set up. Following unsuccessful call attempts within this group, the ringing signal is supplied in a defined sequence to all the other terminals, with the exception of one or more which are correspondingly stored. This may be carried out in ascending order, starting with the lowest telephone number. This type of call transfer is normally implemented for external incoming call requests only. Each exchange line (L3) may be allocated its own individual group of terminals. <IMAGE>

Description

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S F Ref: 60270 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION 594243

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: tilil i~i corret forr [prining Name and Address of Applicant: Address for Service: Siemens Aktiengesellschaft Wittelsbacher Platz 2 8000 Muenchen FEDERAL REPUBLIC OF GERMANY Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia I /i Complete Specification for the invention entitled: A Computer-Controlled Switching System, In Particular a So-Called Key Telephone Switching System The following statement is a full description of this invention, best method of performing it known to me/us including the h; 'i i 5845/4 .VA 0 i:A Al~ 2; -1

ABSTRACT

A COMPUTER-CONTROLLED SWITCHING SYSTEM, IN PARTICULAR A SO-CALLED KEY TELEPHONE SWITCHING

SYSTEM

.1 ::d Yi: 4: /r *a 0 0e *000 00 0' 4. 0 00 00 0*40 0 r Within the framework of a transfer of ringing facility, firstly the ringing signal is connected consecutively to individual terminal devices of a pre-selected group by means of a central control unit (ZSt) on the basis of a sequence specified in a list (L) in a customer daLa store (KD) until a conversation connection is established. If all connection attempts within this group are unsuccessful, the ringing signal is connected to each of the further t er minal devices in a specified sequence with the exception of any one or more pre-selected terminal devices whose identities are stored. This can take place commencing with the lowest subscriber number in an ascending sequence. Generally this mode of ringing transfer will be provided only for external incoming connection requests. For each exchange line (Le) a respective group of terminal devices can be assigned.

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:lc;i- A COMPUTER-CONTROLLED SWITCHING SYSTEM.

IN PARTICULAR A SO-CALLED KEY TELEPHONE SWITCHING

SYSTEM

The invention relates to a computer-controlled switching system such as a so-called KEY telephone switching system, comprising a programme store and a main storage zone arranged to hold 'system-specific information items and the respective operating states of the individual subscriber terminal devices and of the connection Jlines, and a coupling device via which under the control of a tee control computer unit the individual subscriber terminal devices can be connected to one another or to an ongoing line, and wherein the facility of transfer of ringing to at least one further subscriber terminal device is provided.

In a switching system of modern design the use of a control computer unit which cooperates with a corresponding storage system permits a series of user facilities. The individual user facilities provided for a subscriber station or the fundamental system-specific

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t user facilities are stored in a so-called customer data store. Such user facilities can be changed or cancelled via a subscriber terminal device provided for such functions or via a so-called operating terminal.

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1 So-called transfer of ringing can be provided as a system-specific user facility, thus not dependent upon a specific type of terminal device. The transfer of ringing facility ensures

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S- i M7 7/ 17 688/88 I I r r ij _i -2 that a call to be transmitted to a specific terminal device and the corresponding call signalling are forwarded to a predetermined different subscriber terminal device when the originally required subscriber does not answer within a specific time interval or after a specific number of ringing cycles. However, this type of transfer is generally inadequate if it is to be ensured that a connection request, in particular a connection request incoming via an external line, must at all costs lead to an appropriate conversation connection.

It is an aim of the invention to enhance such accessibility to a subscriber being particularly important in particular in smaller systems and in the case of smaller organisation units.

In accordance with the present invention there is disclosed a computer-controlled switching system such as a so-called KEY telephone switching system, comprising a programme store and a main storage zone S "15 arranged to hold system-specific information items and the respective operating states of individual subscriber terminal devices of said system S" and of connection lines interconnecting said terminal devices to said system, and a coupling device via which under the control of a control computer unit said terminal devices can be connected to one another or to r outgoing line of said system, and wherein a facility of transfer of ringing to at least one other said subscriber terminal device is provided, such that in the event that a conversation connection is not established to S an originally requested subscriber terminal device at the end of a 0, ipredetermined number of ringing cycles, as part of the transfer of ringing facility, firstly the ringing signal is connected consecutively to each subscriber terminal device of a group of pre-selected said terminal devices S until a conversation connection is established, or, after unsuccessful S connection attempts to said subscriber terminal devices assigned to said group,'in the same way, with the exception of any one or more pre-selected 0 subscriber terminal devices whose identities are held in a subscriber data 8: 'f memory, the ringing signal is then connected to each subscriber terminal is device of another group of said subscriber terminal devices in a jl T/ '2 predetermined sequence.

crr IAD/840o 1 .j 3 1 i i 11 1 1 1 1 1 1 1 -3- Thus, on the basis of the transfer of ringing principle, this takes place not only to one single further terminal device but, in order to obtain a conversation partner for the calling subscriber if at all possible, a plurality of terminal devices are called consecutively. This is carried out in two steps, whereby the subscribers of a first group can be dialled automatically before the change-over takes place to another group which includes the remaining subscribers or a specific number of further subscribers.

In the search for the first free subscriber terminal device during the following system search run, in which, commencing with the lowest subscriber number, the individual terminal devices can be called consecutively in ascending order, specific subscribers may be skipped.

This can, for example, be the terminal device programmed as "chief subscrJber" in the customer data store. Furthermore a terminal t8LC8 IAD840 '-r-3 F, 1 i to o.:6.

0S asR *00 4 a t 6 0 o 0* *o a device which has already activated the ringing transfer can likewise be skipped in this search for an accessible subscriber.

In accordance with a further development the provided form of this ringing transfer is executed only in the case of external incoming connection requests. For such calls, in particular in the case of calls incoming via an exchange line, it is particularly important that a conversation partner should be reached. In order to achieve a uniformly balanced loading of the individual subscribers, for each exchange line a respective group of subscriber terminal devices can be assigned within which the respective transfer of ringing takes place.

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 block circuit diagram of a telecommunications system embodying this invention.

Referring to the drawing, a switching device VE is connected to subscriber devices TO to Tn in a star formation. In this embodiment speech transmission is to take place in the analogue mode.

For the connection of the terminal devices a four-wire connection line is used which consists of a pair of speech wires a/b and a pair of signalling wires c/d. In an exclusively digital switching system, the control connection and the useful connection provided for the transmission of the items of speech information could take place on a two-wire connection line, in which case at least ope useful channel 1 '1 k.1

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44 4 9 4 4 and one control channel for each terminal device could be provided by means of respective time slots. For a fundamentally procedural adaptation the subscriber terminal devices TO to Tn are connected to an electronic coupling device KN via a connecting unit AT which also includes a ringing circuit. Lines Le lead to a public exchange OV or to a private network via the connecting unit AL. The control functions of the system are undertaken by a central control computer unit ZSt which is coupled via a system bus SB to a storage device SE, to the connecting units AT and AL, and to further system components, such as for example coupling device KN, a unit MZ which serves to form multi-frequency code signals, and a unit HZ which is responsible for generating audible tones. In this embodiment the functions of the central control unit ZSt are distributed between two processors.

Processor ZP is to provide, for example, switching-orientated control and the processor DP is to carry out signalling processing with the assistance of processing unit Ve which includes a transmitting section S and a receiving section E. A processing unit Ve of this type is assigned to each pair of signalling wires c/d.

Via these signal wires c/d a two-way information transmission takes place between the associated terminal device and the central control unit. As indicated for the terminal device T1 for which are shown individual function components, in the key set TS, in addition to digit keys Tw of the dialling keyboard, further function keys Tf can be provided. The information transmission from the control r

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t C C L tE C L computer ZSt of the switching device to the individual terminal devices TO to Tn can relate, for example, to items of setting-up information for optical display elements LF.

In so-called KEY switching systems one of the functions of such optical display elements, e.g. in the form of LEDs, is to indicate the state of the existing external lines Le and the seizure state of the individual subscriber terminal devices. This takes place with the cooperation of the control unit Pe which is provided in each terminal device, e.g. in the terminal device Ti.

In this embodiment the information items transmitted from the switching device VE to a terminal device via the signalling wires c/d are to be transmitted by binary voltage modulation, and the information items to be transmitted in the opposite direction are tzansmitted by binary current modulation. The latter serves to signal, for example, the actuation of individual keys on the respective terminal device. This is to take place, for example, in association with the control unit Pe by means of unit JR. The information bits which occur in the opposite direction as a result of the provided voltage modulation on the respective c/d signalling wires are recorded by means of the control unit Pe in unit UD. They then lead to the actuation of the display elements indicated by the unit LF. The display elements can consist of LEDs. In addition to or In place of these LEDs an appropriate display on a graphics display unit could take place.

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r r tt t C CI -t V rtcIt -7- Items of speech information are transmitted via the respective pair of a/b wires. Speech circuit Sp is connected to these speech wires. In association with handset HA the speechi circuit Sp provides a line termination and serves to process the items of speech information which, in this embodiment are transmitted in analogue form.

Via system bus SB the processors ZP and DP have access to data items stored in the storage device SE. These data items relate, for example, to the entire system programme stored in store P and to the assigned operating-technology data items contained in the main store A. Storage section KD stores items of customer data which include, for example, abbreviated dialling codes provided for the system and the authorisations assigned to the subscriber tetminal devices. These data items can be configured, for example, via the input keyboard of a terminal device specified as operating terminal.

For the customer data store KD a storage medium is selected in which the data stored therein are retained after the disconnection of the system or in the event of a power failure. These data items include a stored list L which contains the data arlsi-ag in connection with a programmed mode of ringing transfer. The user facility of ringing transfer provides the system with the possibility that when the desired conversation connection is not accepted in the event of an awaiting call, at least one further subscriber terminal device cam be called automatically. In particular In smaller systems, a ringing

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transfer facility of this kind is normally provided only for calls incoming on an external line Le. It can be restricted to calls which are fed via an exchange line Le from a public switching system OV to the switching device VE, If, in the event of such a connection attempt, the desired subscriber terminal device is busy or the respective subscriber does not answer, after a specified time interval or after a specified number of ringing cycles the ringing is transferred to another subscriber terminal device.

It is also possible to provide more than one further terminal device for such transfer, in which case a group of terminal devices accessible within the framework of the ringing transfer facility are formed. Several such groups can also be specified. The terminal devices assigned to a group are stored in the customer data store KD in the list L. The call which triggers a ringing transfer is forwarded consecutively to the individual subscriber terminal devices within the predetermined group of subscriber terminal devices until a conversation connection is established. If such a conversation connection is not possible, if so provided in the system, the ringing can be transferred to a further grolup of subscriber terminal devices.

It is possible to form one or more groups for this type of ringing transfer for each exchange line Le.

If this call signalling to the terminal devices firstly directly provided for this purpose within the framework of the transfer of ringing facility does not lead to a successful *1 i ii r j 1

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C. Ct tC C C~tt 4(1(11 connection, a general system search run can be adopted. In a system search run of this kind all the other subscriber terminal devices can then be included consecutively in this transferred call signalling method. Thus if a conversation connection to one of the subscriber terminal devices originally specified for the transfer of ringing is not possible, commencing with the lowest subscriber number the transfer of ringing takes place to the respective next station identified as free in the main store A. As indicated above, a group originally provided for the transfer of ringing can reduce in extreme cases to one single further subscriber terminal device.

In the subsequent system search run fundamentally it is als(t possible for a busy subscriber terminal device to be requested, by an appropriate gating-in of the ringing, to accept the awaiting conversation. If the call signalling carried out in this system search run does not lead to the answering of the call, the call is transferred to the next, preferably the next free, station.

The search for the first free station during the system search run can skip selected subscribers. These subscriber identities are contained in the main store so that first prior to the respective call signalling it is established whether the subscriber is to be skipped in the search run. For example a subscriber declared as "chief subscriber" can be excluded from the system search run. A station in which a user facility has been activated which indicates that the respective subscriber is unaccessible, is likewise skipped.

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This is the case, for example, when the call transfer has been activated at the respective subscribey terminal device. This can be established by calling up the main store A in which those subscribers which have requested such a user facility are stored.

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Claims

7- -12- A switching system as claimed In claim 3, wherein after unsuccessful connection attempts within a group of subscriber terminal devices, the ringing signal is connected to subscriber terminal devices combined in other groups and then to the remaining subscriber terminal devices. 6. A switching system as claimed in any one of the preceding claims, wherein the items of control information required for the consecutive transfer of ringing between all the subscriber terminal devices are read out by the central control computer unit from the information items stored in a subscriber data memory and, in the subscriber data memory those subscriber terminal devices which are to be excluded from the transfer of ringing which is to take place, are specified by an additional characteristic. 7. A computer-controlled switching system such as a so-called KEY telephone switching system, said switching system being substantially as o° described herein with reference to the accompanying d-aving. DATED this TWELFTH day of DECEMBER 1989 els Siemens Aktiengesellschaft 0 Patent Attorneys for the Applicant y SPRUSON FERGUSON k 1 C It 4 t C 6 4 f C C IAD/8400 o i V L T .r w}