The Nokia Privacy Handset HSU-31 provides more privacy for your conversations. When you press the light guide on top of the handset release button and lift the Nokia Privacy Handset from its holder, the loudspeaker and microphone will be muted and you can speak in private. When you replace the Privacy Handset in its cradle, the call is terminated unless you have pressed the Menu selection key on your mobile phone in order to return to handsfree mode. Connects to the Handset socket on the Nokia CARK-91 control unit.