GB2014826A - Telephone intruder alarm system - Google Patents

Telephone intruder alarm system

Info

Publication number
GB2014826A
GB2014826A GB7905924A GB7905924A GB2014826A GB 2014826 A GB2014826 A GB 2014826A GB 7905924 A GB7905924 A GB 7905924A GB 7905924 A GB7905924 A GB 7905924A GB 2014826 A GB2014826 A GB 2014826A
Authority
GB
United Kingdom
Prior art keywords
telephone
handset
telephone line
detected
extension telephone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7905924A
Other versions
GB2014826B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
KORWIN P
Original Assignee
KORWIN P
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US05/879,476 external-priority patent/US4136266A/en
Priority claimed from US05/964,947 external-priority patent/US4230914A/en
Application filed by KORWIN P filed Critical KORWIN P
Publication of GB2014826A publication Critical patent/GB2014826A/en
Application granted granted Critical
Publication of GB2014826B publication Critical patent/GB2014826B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/68—Circuit arrangements for preventing eavesdropping

Abstract

A compact telephone intruder alarm system is operative for indicating to a current on-line user 20 of a primary extension telephone which is already interconnected with the telephone line of the subsequent interconnection and disconnection of another auxiliary extension telephone eg 16, 18 with the same telephone line. Electrical OFF- and ON-hook signals are respectively generated each time an extension telephone is interconnected or disconnected with the telephone line, and each such hook signal is successively detected and electrically amplified before being conducted to a light-emitting diode 40. The first detected OFF-hook signal indicates the start of the interconnection of the auxiliary extension telephone, and the second detected ON-hook signal indicates the duration and the end of the intruder presence on the telephone line. All electrical components are of miniature size and in one embodiment, Figs. 2, 3 (not shown) are mounted within the handset to simplify and to make installation less discernible. The light-emitting diode is readily viewable during conversation because it is mounted directly on the handset and instantly conveys the instrusion to the user. In another embodiment, Figs. 5-8 (not shown), the electrical components are mounted remotely from the handset. <IMAGE>
GB7905924A 1978-02-21 1979-02-20 Telephone intruder alarm system Expired GB2014826B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US05/879,476 US4136266A (en) 1978-02-21 1978-02-21 Telephone intruder alert system
US05/964,947 US4230914A (en) 1978-11-30 1978-11-30 System for and method of indicating intruder presence on telephone lines, and method of installation of telephone intruder alarm system

Publications (2)

Publication Number Publication Date
GB2014826A true GB2014826A (en) 1979-08-30
GB2014826B GB2014826B (en) 1982-03-31

Family

ID=27128539

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7905924A Expired GB2014826B (en) 1978-02-21 1979-02-20 Telephone intruder alarm system

Country Status (1)

Country Link
GB (1) GB2014826B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2154392A (en) * 1984-02-15 1985-09-04 Peter Henderson Telephone in use indicator (line busy lamp)
US4726048A (en) * 1984-04-03 1988-02-16 Waldman Herbert H Telephone privacy circuit
GB2206467A (en) * 1987-07-02 1989-01-05 Glynn John Hawkins Telephone warning device
EP0593120A1 (en) * 1992-10-14 1994-04-20 Koninklijke Philips Electronics N.V. Device for detecting the activation of a parallel connected telephone set

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2154392A (en) * 1984-02-15 1985-09-04 Peter Henderson Telephone in use indicator (line busy lamp)
US4726048A (en) * 1984-04-03 1988-02-16 Waldman Herbert H Telephone privacy circuit
GB2206467A (en) * 1987-07-02 1989-01-05 Glynn John Hawkins Telephone warning device
GB2206467B (en) * 1987-07-02 1991-05-01 Glynn John Hawkins On-line warning device
EP0593120A1 (en) * 1992-10-14 1994-04-20 Koninklijke Philips Electronics N.V. Device for detecting the activation of a parallel connected telephone set

Also Published As

Publication number Publication date
GB2014826B (en) 1982-03-31

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee