GB2286092A

GB2286092A - Telephone communications switch system and apparatus

Info

Publication number: GB2286092A
Application number: GB9401753A
Authority: GB
Inventors: Michael Bryan Davison
Original assignee: SDX Business Systems PLC
Current assignee: Avaya ECS Ltd
Priority date: 1994-01-31
Filing date: 1994-01-31
Publication date: 1995-08-02
Also published as: GB9401753D0

Abstract

A telephone communication switch system for connecting an incoming telephone call to one of a number of devices (8 - 10). The system includes a sensor (11) for detecting characteristics of a ringing cadence control signal of a incoming call and for routing the incoming call to a device (8 - 10) determined in accordance with the detected ringing cadence. <IMAGE>

Description

TELEPHONE COMMUNICATIONS SWITCH SYSTEM AND APPARATUS The invention relates to a telephone communications switch system for connecting an incoming telephone call to one of a number of devices, and to telephone calling apparatus for generating a telephone communication to such a telephone communications switch system.

Conventional telephone communications switches such as private telephone exchanges typically route an incoming call to a particular extension in response to an operator actuated routing command. More sophisticated systems allow a caller to append extension routing information to the originally dialled number or request such additional information. For example, the caller may wish to access a voicemail system or a fax machine or alternatively a conventional voice extension. These routing systems, however, require special switches and exchanges to be provided which is uneconomic.

In accordance with one aspect of the present invention, a telephone communications switch system for connecting an incoming call to one of a number of devices includes sensing means for detecting characteristics of a ringing cadence control signal of an incoming call and for routing the incoming call to a device determined in accordance with the detected ringing cadence.

Currently, when a public switched telephone network (PSTN) exchange presents a call to a telephone, an electrical signal is applied to the two wires which represent the link to the PSTN exchange for a given line.

The electrical signal sent from the exchange causes the bell to ring on mechanical telephones. The cadencing of ringing is achieved by presenting and removing a control signal to achieve the required pattern. The period of the ring cadence is defined and enforced by various governmental bodies including the British Approvals Board for Telecommunications (BABT). We have realised, however, that despite this definition, it is possible to vary certain characteristics of the ring cadence control signal to provide additional information and yet remain within the tolerance requirements set down by BABT.

For example, the total duration of one cadence and/or the on-off timing within a cadence can be varied to take up a number of different values. These values can be equated to particular extension numbers, for example, thus allowing the call automatically to be routed to the appropriate extension.

Typically, the sensing means is located in a unit having an input port which receives the incoming call, a respective output port connected in use to each device, and switching means for routing the incoming call to the appropriate output port. Thus the telephone communications switch could be formed by a private exchange or by a standard telephone adapted to have this facility.

In other cases, the sensing means could be provided in the devices with the incoming call being routed in parallel to each device but only being passed for further processing by the device which corresponds to the particular ringing cadence.

In accordance with a second aspect of the present invention, a telephone calling apparatus comprises means for causing a ringing cadence control signal to be generated and sent to a telephone communications switch system connected to a number of devices, wherein the generating means causes a ringing cadence control signal to be generated with characteristics determined in accordance with the desired one of the devices connected to the telephone communications switch system, wherein the ringing cadence control signal is chosen from a group of such signals all falling within a tolerance band of a nominal ringing cadence control signal.

Preferably, all the ringing cadences in the group are acceptable by all possible devices to which the apparatus could be connected. This is particularly advantageous since the method can be used on existing networks. Where the receiving system is capable of sensing different ringing cadences then it will react accordingly. If a conventional device receives one of the special cadences (which usually differ inaudibly) however it will react in its normal manner.

Some examples of switch systems and calling apparatus according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a telephone communications system; Figure 2 illustrates different ring cadences; and, Figure 3 illustrates an alternative switch system.

The telephone system shown in Figure 1 comprises a calling device 1 (or a collection of devices) which includes a key pad 2 and an input device 3, for example a fax machine, telephone handset or the like. The key pad 2 and input device 3 are connected to a cadence control device 4.

The calling device 1 is shown connected to a private exchange 5 via a link 6. Typically, but not necessarily, the link 6 will be formed between two private exchanges.

The private exchange 5 is accessed by dialling a particular number from the key pad 2. The private exchange 5 includes a switch 7 which can route an incoming call to one of a number of extensions, three of which are shown. In this case, the three extensions 8-10 comprise a voice extension, a fax machine and voicemail respectively. The exchange 5 also includes a cadence sensor 11 whose function is to be described.

In use, a caller decides he wishes to access one of the extensions 8-10, for example the fax extension 9, attached to the private exchange 5. To achieve this, he dials the telephone number of the exchange 5 by entering the appropriate digits on the key pad 2. He appends to that number an additional number which constitutes an extension identifier or the number may be inferred by apparatus 1 from the type of device initiating the call.

The cadence control device 4 senses the appended number and generates a cadence control signal having a pulse modulation appropriate to that number. The call is then routed in a conventional manner through the link 6 until it reaches the exchange 5. The incoming call is monitored by the cadence sensor 11 which detects the pulse modulation of the ring cadence and the sensor 11 then controls the switch to route the incoming call to the appropriate one of the extensions, in this case the extension 9.

Figure 2 illustrates a number of different ring cadence sequences. Figure 2A illustrates a typical standard ring cadence with the permissible tolerances indicated by "#". It will be seen, therefore, that the off to on and the on to off time can be varied within the appropriate hashed areas 12,13.

Figures 2B-2E illustrate four different ring cadence sequences, all of which fall within the tolerance levels defined in Figure 2A but each of which differs from the others in a unique manner.

A typical example of the nominal periods for a ringing cadence and the tolerances permitted can be found in British Standard 6305. Thus, for a ringing tone with a frequency of 16 2/3 Hz or 25 Hz a nominal ringing cadence is defined as: 0.4s On 0.2s Off 0.4s On 2s Off Tolerances for these values of +10% to -20% are given as being acceptable. These tolerances are reflected diagrammatically in Figure 2A.

Figure 3 illustrates a modified form of receiving apparatus in which an incoming call on a line 14 is sent in parallel to a telephone or voice receiving device 15 and a fax machine 16. Each of the devices 15,16 has a cadence sensor 17,18 which monitors the incoming ringing cadence and compares this with the ringing cadence indicative of the associated device. If the two are the same, then the sensor 17 will allow the incoming call to pass to the associated device.

Claims

1. A telephone communications switch system for connecting an incoming telephone call to one of a number of devices, the switch system including sensing means for detecting characteristics of a ringing cadence control signal of an incoming call and for routing the incoming call to a device determined in accordance with the detected ringing cadence.

2. A system according to claim 1, wherein the sensing means is located in a unit having an input port which receives the incoming call, a respective output port connected in use to each device, and switching means for routing the incoming call to the appropriate output port.

3. A system according to claim 2, wherein the system is incorporated in a private exchange.

4. A switch according to any of the preceding claims, wherein the devices are selected from voice, fax and voicemail devices.

5. A telephone communications switch substantially as hereinbefore described with reference to either of the examples shown in the accompanying drawings.

6. A telephone calling apparatus comprising means for causing a ringing cadence control signal to be generated and sent to a telephone communications switch system connected to a number of devices, wherein the generating means causes a ringing cadence control signal to be generated with characteristics determined in accordance with the desired one of the devices connected to the telephone communications switch system, wherein the ringing cadence control signal is chosen from a group of such signals all falling within a tolerance band of a nominal ringing cadence control signal.

7. Apparatus according to claim 6, wherein all the ringing cadences in the group are acceptable by all possible devices to which the apparatus could be connected.

8. A telephone calling apparatus substantially as hereinbefore described with reference to the accompanying drawings.

9. A system or apparatus according to any of the preceding claims, wherein the characteristics of the ringing cadence control signal comprise one or more of a ringer-ON period, a ringer-OFF period, and the total duration of a ringing cadence.

10. A telephone communication system comprising at least one calling apparatus according to any of claims 6 to 9 and at least one telephone communications switch system according to any of claims 1 to 5 or 9.