Telephone system used as burglar alarm - automatically calls number of supervising station when burglar breaks in

摘要

One of the number of telephone stations serve as a supervising station for the other stations. If a circuit at a supervised station is broken by an intruder, the supervised station automatically calls the number of the supervising station, adding a coded identification signal. If the number of the supervising station is engaged the supervised continues to call the number of the supervising station until the latter station accepts the call. The supervising station can effect the operation of appts. e.g. a light switch or a video recorder at any supervised station by calling the number of the supervised station and adding a coded signal corresponding to the appts. to be operated.