Nortel Networks 2007 - Manual (Page 45)

Terms you should know
Waiting, All Lines Forwarded to: 6453, Do Not Disturb On, Ring
Again Active, Ringer is OFF, and Line x Unavailable.
System or Switch
Your office communication system.
Switchhook
A button that the handset depresses, disconnecting your call
when you replace the handset. When lifted, the handset releases
the switchhook, and you either answer an incoming call or you
receive a dial tone to make a call.
User interface
Screen displays that interact with the end user as a result of an
action or event.
Volume control bar
A rocker bar you press to increase or decrease the volume of the
ringer, handset, headset, speaker, and the Handsfree feature.