Muting
To Mute the Microphone:
During a call, press the (mute) button. The button will turn red and a red microphone will show up on the phone's screen.
To Un-Mute the Microphone:
Press the (mute) button again. The button will no longer be red, and the red microphone icon will disappear from the screen.
To mute the phone ringer, see Setting Ring Volume