| 摘要 |
Activating a switch by a handset where the switch is manually activated when the user wishes to answer an incoming call. While the switch is in the deactivated state, the handset transmits to a sound card within a personal computer a multi-frequency tone which is detectable by the sound card. When the manual switch is activated, the handset ceases to transmit the multi-frequency tone to the sound card. The sound card detects the absence of the multi-frequency tone to determine if the handset is answering a call. In traditional telephony terms, when the manual switch is activated, this is the offhook condition. When the manual switch is deactivated, this is the onhook condition . When the user is done with the call and deactivates the manual switch, the handset again generates the multi-frequency tone that is subsequently detected by the software via the sound card. Then, the software knows to signal the other party on the call that the call has been terminated. A headset is similarly designed to provide the same multi-frequency tone generation features as the handset.
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