Plantronics P420 - Manual (Page 6)

Plantronics P420 USB Speakerphone 6
3 Using your P420 USB speakerphone
Volume up, volume down and mute
1 Press the down arrow (left button) to decrease the
speaker volume.
2 Press the up arrow (right button) to increase the speaker
volume.
NOTE A prolonged press of the volume buttons will increase or
decrease the volume several levels until you stop pressing the
button. The P420 will beep when a volume up button or volume
down button is pressed and a series of beeps when a prolonged
press is performed. Each beep signals one level of volume
increase or decrease.
3 Press the microphone icon (middle button) to mute
the microphone. A blue light will flash indicating that the
microphone is muted.
4 Press this button again to unmute. The blue light will
become solid indicating the microphone is unmuted.