为免提电话加装声控装置贾彦疆本电路加装在免提电话机上，当有电话打进时．离着电话一定距离，手不与电话作任何接触，只需上一声就可以实现摘机通话，而当通话结束时对方挂机以后，自己一方的电话也会自动挂机。这就避免了有时手中正忙着其他事情而正好有电话打进来时的... Voice-activated device for hands-free phone installation Jia Yanjiang The circuit installed on the speakerphone, when a phone scored. Away from the phone a certain distance, the hands do not make any contact with the phone, just on the hook to achieve off-hook calls, and when the call ends when the other party hangs up, one’s own phone will automatically hang up. This avoids the sometimes busy hands on other things that happen to happen when a call comes in.