GB2300992A

GB2300992A - Monitoring the integrity of alarm systems

Info

Publication number: GB2300992A
Application number: GB9510029A
Authority: GB
Inventors: Doug Nelson
Original assignee: Scantronic Ltd
Current assignee: Cooper Security Ltd
Priority date: 1995-05-18
Filing date: 1995-05-18
Publication date: 1996-11-20
Anticipated expiration: 2015-05-18
Also published as: GB9510029D0; GB2300992B

Abstract

Remote alarm stations 1-4 connected to a central monitoring station 11-14 via telephone lines 5 are caused to send a telephone call to the central station for system integrity checking, the central station having a calling line identifier 12 so that the calling line can be identified without answering the call, whereby no call charges are incurred during the system checking. In a first system, each remote station sends such a test call to the central station at predetermined times, eg. at regular intervals, known to the central station. In a second system, the remote stations generate the test calls in response to being polled by the central station. The central station distinguishes between test calls and genuine alarm calls by monitoring the duration or relative timing of the call. Thus, in the first system the remote station may only stay on line for one ring in the case of a test call, but may stay on line until the central station answers a genuine alarm call, and in the second system any call which is not in response to polling is deemed to be an alarm call.

Description

Monitoring of Telephone Svstems The present invention relates of telephone systems and more particularly to monitoring apparatus for monitoring the integrity of the system.

There are many telephone systems which either generate or receive calls automatically and it is important to monitor such systems in order to detect a fault. One such telephone system is an alarm communicator system which is arranged to generate a message which is sent to a central monitoring location via the normal telephone lines in the event of the alarm being activated. In such systems, it is important to know if the telephone line is operating correctly. This is currently achieved using a dial up facility by initiating a telephone call in, or from the remote equipment, with a subsequent exchange of data. As there is a connection made between the remote equipment to the central monitoring equipment thorough an exchange, a call charge is incurred.

In many countries, the normal telephone system is or includes a digital transmission at the commencement of a call which identifies the calling station and facilities are made for reading and displaying the identity of the calling station prior to or at the same time as causing the ringing of the station. In this country, this is called CDS which is a trade mark of British Telecommunications plc.

The present invention provides apparatus at a remote station for generating a telephone call on a telephone system supporting calling line identification and means at a central monitoring station for identifying the calling line without answering the call.

In one embodiment, the remote station generates the call at regular intervals. Alternatively, the central monitoring station calls the remote station which is provided with calling line identification equipment. The remote station then decodes the calling line identification without actually answering the call and identifies that the calling station is in fact its central monitoring station. Whereupon it then generates a call to the central station which then operates as before. Preferably, the central station expects to receive a call from the remote station within a predetermined time interval after the central station generated its call to the remote station.

In order that the present invention be more readily understood, embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows a diagram representing a first embodiment of the present invention; and Fig. 2 shows a diagram representing a second embodiment of the present invention.

The present invention will now be described in detail as used with an alarm system which communicates with a central monitoring station via conventional telephone lines. Referring to Fig. 1, an alarm system includes an alarm device 1, a control unit 2 and a communications unit 3. In the event of an alarm condition, the control unit 2 activates the communications unit 3 which in turn alerts a central monitoring station 10 by sending a message via a telephone line 5 which is provided with calling line identification facilities.

In order to ensure that the telephone line is intact and the control and communication units are functioning, the control unit 2 causes the communication unit 3 to contact the central station 10 at intervals which are known to the central station, e.g. regular intervals, even when no alarm condition exists.

The central station 10 includes a communication unit 11 for receiving an incoming telephone call and a decoding unit 12 for identifying the caller without actually answering the call. The decoded information is fed to a central monitoring unit 14 where the call is logged. In this way, no call charges are incurred and only the central station 10 needs to be modified as the alarm system is conventional. The decoding unit is a standard unit which generates the telephone number of the alarm device. The telephone number is unique to the alarm device and by a simple comparison of the telephone number with a list of known telephone number of devices it is monitoring, the central station 10 can determine whether or not all is well.

A modified version of the embodiment shown in Fig 1 is shown in Fig 2 where like parts are allocated like reference numerals. Here, rather than the control unit 2 of the alarm controlling communications between the alarm and the central station 10, the routine communications between the central station and alarm are controlled from the central station by virtue of the central station polling each of the alarms connected to it and each alarm returning a call within a predetermined period. This requires additional facilities at the alarm location as it is intended that the alarm will be provided with a decoder unit 4 for identifying the central station 10 as a caller without actually answering the call. Once this achieved, the control unit 2 then causes a call to be generated by the alarm as before.

In the event of an alarm, it is necessary for the central unit to answer the telephone caller. There are a number of ways in which the central station 10 can determine whether the call should be answered depending on whether the remote station is being polled or not.

It is most easily done by monitoring the duration or relative timing of the call.

In the case of an alarm being generated when using a system as described in relation to Fig. 1, it is possible for the control unit 2 of the remote station to stay on line waiting for the monitoring unit 14 to answer the call. Normally, the control unit 2 would wait for one ring and then terminate the call assuming that in the meantime it had been identified by the recorder unit 12. Once the call is answered by the central station 10 the usual alarm communication can take place.

In the case of an alarm being generated when using a system as described in relation to Fig. 2, any telephone call from a remote station not being a result of a polling telephone call from the central station 10 is deemed to be an alarm call and will be answered by the central station.

Various modifications may be made to the above described systems. For example, it is possible to incorporate the communication units at either or both these remote and central stations into the respective control units.

Claims

CLAIMS:

1. Apparatus for monitoring a remote station via a telephone system supporting calling line identification, the apparatus comprising means for receiving a telephone call from the remote station and for identifying the calling line without answering the call, and monitoring means for monitoring the duration or timing of the call and for causing the call to be answered in the event that the duration or timing does not comply with predetermined criteria.

2. Apparatus according to Claim 1, and comprising a control means for generating a signal for transmission to the remote station via the telephone system to cause the remote station to transmit a telephone call to the control means.

3. An alarm communicator system comprising a plurality of remote alarm devices in communication with a central monitoring station via a telephone system supporting calling line identification, wherein the central monitoring station includes means for receiving a telephone call from a remote alarm device and for identifying the calling line without answering the call.

4. An alarm system according to Claim 3, wherein each remote alarm device has a control unit arranged to cause a telephone call to be transmitted at intervals.

5. An alarm system according to Claim 4, wherein the central monitoring station includes control means for generating a signal for transmission to a remote station, wherein each remote station is provided with means of receiving a telephone call and for identifying the calling line without answering the call, and wherein the control unit in each remote alarm device is arranged to generate a telephone call to the central monitoring unit in response to identifying the calling line as that of the central monitoring unit.

6. An alarm communicator system according to Claim 3, 4 and 5 and comprising monitoring means at the central monitoring station for monitoring the duration or timing of the call from a remote station and for causing the call to be answered in the event that the duration or timing of the call does not comply with predetermined criteria.

7. An alarm communicator system substantially are hereinbefore described with reference to Fig. 1 and Fig 2 of the accompanying drawings.