| 摘要 |
<p>Deactivating a switch in a handset when a user wishes to answer an incoming call or terminate a call. A sound card within a personal computer transmits a hook tone that is above the human hearing range to a transmitter section of the handset. When the switch is in the activated state, the handset re-transmits the hook tone back to the sound card which converts the hook tone to digital information so that the hook tone can be detected by software running in the personal computer. When the manual switch is deactivated, the handset ceases to re-transmit the hook tone back to the sound card. The software detects the absence of the hook tone to determine if the handset is answering the incoming call. In traditional telephony terms, when the manual switch is deactivated, this is the offhook condition. When the manual switch is activated, this is the onhook condition. When the user is finished with the call and activates the manual switch, the handset again starts retransmitting hook tone that causes the hook tone to be detected by the software via the sound card. Then, the software signals the other party on the call that the call has been terminated. Low-pass filters are utilized in the handset to block the hook tone from the receiver and transmitter sections of the handset. A headset is similarly designed to provide the same switching features as the handset. <IMAGE></p> |
