Patent ID: 7266398

Claim:
A circuit being set in a communication apparatus and co-operating with a button of an audio receiving/transmitting device for triggering an on-hook or off-hook function by pressing the button while the communication apparatus receives an incoming call, the communication apparatus comprising an audio-signal receiving port, a bias source, and a detecting-signal input port, the circuit comprising: a connecting device comprising an audio-signal input end for electrically and detachably connecting to the audio receiving/transmitting device; a first signal line for connecting the audio-signal receiving port and the audio-signal input end; a second signal line for connecting the bias source and the first signal line; and a detecting device for electrically connecting to the first signal line and the detecting-signal input port, wherein a first connecting point is defined as the place where the detecting device electrically connects to the first signal line, the detecting device being used for detecting a detecting signal of a voltage value of the first connecting point and outputting a detecting-signal value of the detecting signal to the detecting-signal input port; wherein, when the audio receiving/transmitting device is electrically connected to the connecting device, the communication apparatus receives the incoming call, and the button is pressed, a temporarily broken circuit is caused between the audio-signal input end of the connecting device and the audio receiving/transmitting device the temporarily broken circuit further causing the detecting-signal value to be higher than a threshold value, to trigger the on-hook function of the communication apparatus; and wherein, when the on-hook function is activated, the audio receiving/transmitting device is connected to the connecting device, and the button is pressed, the temporarily broken circuit between the audio-signal input end of the connecting device and the audio receiving/transmitting device is caused again and further causes the detecting-signal value to be higher than the threshold value, to trigger the off-hook function of the communication apparatus.