Placing a Call and Other Basic Phone Tasks
If you are using...
Muting a Call
Press the Headset button or the EndCall softkey.
Press the Speaker button or the EndCall softkey.
You can mute the handset, headset, or speakerphone during a call. The mute
feature temporarily disables your phone's microphone. Mute prevents the party or
parties on the other end of the line from hearing you, but does not interfere with
your ability to hear them.
To mute a call, press the Mute button. To disengage mute, press Mute again.
Cisco IP Phone 7960 and 7940 Series User Guide
Making Telephone Calls