PSTN appliance security system with reduced PSTN traffic loading

Details PSTN appliance security system with reduced PSTN traffic loading PSTN appliance security system with reduced PSTN traffic loading

1998-03-16

2000-09-19

Chan, Wing F.

Telephonic communications

Telephone line or system combined with diverse electrical...

Remote control

379 9001, 37910601, 340531, 34082536, H04M 1100

Patent

active

061223506

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to security systems and more particularly but not exclusively to a security system for protecting consumer apparatus from theft.
2. Related Art
In our co-pending European Patent application No. 94302211.1 (Publication No EP 0675626A) there is described a security system which utilises an interface between a domestic power supply and the public switched telephone network (PSTN) to provide identity signals derived from the calling line identity (CLI) of the customers PSTN telephone line. The identity signals are requested by a security module in apparatus such as televisions, video recorders, hi fi equipment and the like.
The system is arranged such that each time mains electrical power is connected to protected apparatus the security module requests (by way of the electrical power circuit) an identity code. The interface to the telephone network recognises the request from the mains supply circuit and causes a telephone call to be established via the PSTN to the security control centre which returns an identity code. The identity code is compared with a previously stored identity code in the protected apparatus, non-identity being used to prevent power being supplied to operational circuits.
It has been realised that while the security system previously described provides a high level of protection (by making stolen goods unattractive to thieves since they will not work away from their proper location), since connection of any of several items of protected apparatus will result in a corresponding number of PSTN calls, high levels of PSTN traffic may be generated resulting in network congestion and higher consumer costs.


SUMMARY OF THE INVENTION

According to the present invention there is provided a security system comprising access means to cause seizure of a connection to a telephone exchange, means in the exchange to generate coded signals which identify the source of the seizure and service means responsive to the coded signals to transmit to the access means security signals which identify at least one protected apparatus and a release code for each such protected apparatus.
Preferably the service means transmits a data table identifying each protected apparatus with a corresponding release code and a house code for all protected apparatuses at a specified location, said house code being used to release all said protected apparatuses simultaneously.
The access means may include a data store which is cleared of all data if either the mains electrical power or the telephone line is disconnected from the access means , the data store holding a list of identities for each protected apparatus at the location and a release code for each such protected apparatus.
After disconnection of electrical power to the access means, and on subsequent reconnection thereof, the access means may be arranged to cause seizure of a connection to service means responsive to signals which identify the location of the access means to transmit thereto the list of apparatuses and release codes therefor. A house code may also be received by the access means, the access means immediately transmitting the house code to the mains power circuit.
A security module for inclusion in electrically powered apparatus and having means responsive to signals received from a power line to permit or deny connection of electrical power to operational circuits of the apparatus, the module being responsive to connection of mains power to monitor the electrical power line for signals identifying a house code valid for the protected apparatus to permit connection of power to operational circuits and if such signals are not received within a predetermined period to transmit to the power line signals requesting a release code for the apparatus.
The house code and release code for a protected apparatus may be the same or may be different, and, if different, the release code may be specific to the protected apparatus.
The module may transmit signals to line identifying

REFERENCES:
patent: 4942599 (1990-07-01), Gordon et al.
patent: 5021779 (1991-06-01), Bisak
patent: 5022067 (1991-06-01), Hughes
patent: 5351289 (1994-09-01), Logsdon et al.
patent: 5406269 (1995-04-01), Baran
patent: 5406619 (1995-04-01), Akhteruzzaman et al.
patent: 5410326 (1995-04-01), Goldstein
patent: 5729596 (1998-03-01), Reeder et al.

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