Remote condition monitoring device

Claim 1

A remote-condition monitoring apparatus for use in conjunction with a preexisting telephone system comprising lead means including first and second leads adaptable for connection to preexisting telephone station lines, monitoring means operative to determine when a preselected measurable physical parameter exceeds a present limit, ring detector means for detecting the electrical ringing signal on said lead means representing the presence of an incoming telephone call on said preexisting telephone station lines to produce a ring detector signal in response to said ringing signal, first switching means operative in response to said monitoring means to selectively interconnect said lead means and said incoming call detecting means when said preset limit is exceeded, electrical simulating means operative to provide an electrical simulation signal equivalent to that produced at the central switching office of said preexisting telephone system by the lifting of a telephone receiver to thereby cause the completion of the calling circuit for said incoming telephone call by said central switching office, second switching means connected to the output of said ring detector means and operative in response to said ring detector signal to connect said electrical simulating means to the output of said lead means whereby said ringing signal is applied to said electrical simulating means to initiate said electrical simulation signal, and tone generator means connected to said electrical simulating means and operative in response thereto to produce an audible tone over said completed callIng circuit.