Patent ID: 7190771

Claim:
An Internet telephony device, comprising: a first output device and a second output device, distinct from said first output device; an input device constructed and adapted to receive an audio input signal, and circuitry constructed and adapted to analyze said audio input signal, wherein said circuitry is constructed and adapted to detect in said audio input signal a multi-frequency signal indicative of an incoming call, and automatically to send an output signal to a said first output device when said multi-frequency signal corresponding to an incoming call is detected, and otherwise to send said audio input signal to said second output device, wherein said circuitry comprises: a plurality of frequency filters, each corresponding to a different frequency indicative of said multi-frequency signal, and each filter constructed and adapted to detect a different frequency indicative of said multi-frequency signal, a plurality of capacitors, one corresponding to each of said plurality of frequency filters, each connected to a different one of said plurality of frequency filters, for filtering out signals having certain durations; a plurality of switches connected in series, one corresponding to each of said plurality of frequency filters, each connected to a different one of said plurality of capacitors, for selectively causing said audio signal to be routed to the first output device when said frequency indicative of said multi-frequency signal are detected for a sufficient period of time by said plurality of frequency filters in conjunction with said plurality of capacitors, and otherwise causing said audio signal to be routed to said second output device.