Voice communication for elevator

Abstract

Upon detection of a trapped passenger in an elevator car, a resident monitoring device initiates communication between the car and a telephone in the building and between the car and a remote monitoring center. Upon detection of the first responsive telephonic communication from either the remote monitoring center or the telephone in the building, voice communication is established therebetween. Upon detection of a second responsive telephonic communication from the second location to respond, voice communication is established between the car and the second location as well so that simultaneous communication may be conducted between the car, the remote monitoring center, and the telephone in the building. A building telephone has a keypad which can be used to select another car for voice communication with a trapped passenger by pressing a selected key. A telephone ring voltage source is provided for alerting building personnel of a trapped passenger. A dual-tone, multi-frequency decoder is provided for determining which keypad button is depressed.

Dependencies are inferred from the claim text.