Patent ID: 6044149
Filing Date: 2000-03-28
Classification: H04M,H04Q

Abstract:
A device adapted to be coupled to a telephone line for detecting DTMF tones on the telephone line when the telephone line is in an off-hook condition, and generating a signal in response to at least one predetermined set of DTMF tones, the device comprising:an on/off-hook detection circuit for detecting, but not changing, the on/off-hook condition of the telephone line;a power supply circuit coupled to said on/off-hook detection circuit and activated by said on/off-hook detection circuit only when said on/off-hook detection circuit detects an off-hook condition of the telephone line;a DTMF receiver circuit coupled to and activated by said power supply circuit;a signal generator coupled to said power supply circuit; anda logic circuit coupled to said DTMF receiver circuit and said signal generator for activating said signal generator upon detection of said at least one predetermined set of DTMF tones.