Turn your phone’s microphone off so the other party cannot hear you, or turn the microphone back on.
During a call, press 
. The LED on the phone lights up and a flashing microphone on the display indicates that the other party (parties) cannot hear you.
Microphone Mute applies to all modes: handset, headset, and hands-free. You can still hear all other parties while Mute is enabled.
To turn off Microphone Mute, press again.