The Panasonic KX-TGA510M cordless landline phone has an external volume control that lets you raise and lower the volume of your unit's ringer at will. The ringer is the audio clip that plays whenever you receive a call, letting you know that someone is trying to get in touch with you. This exterior volume control can also be used to turn the ringer completely off and then back on again based on your current needs.
Take the phone off of its charging cradle. The screen on the front of the phone will light up, indicating that it is ready for use.
Press the "Volume Down" button until the words "Ringer Off" appear on the screen of the phone. The ringer is now off.
Press the "Volume Up" button until the words "Ringer On" appear on the screen of the phone. The ringer is now on.