AT&T 7406BIS - Manual (Page 15)

Self-Test Allows you to test the operation of the lights and ringer of your voice
terminal.
Send All Calls Temporarily sends all your calls to the extension of a person
designated to answer them when you cannot (perhaps a secretary or receptionist). Use
when you will be away from your desk for awhile, or when you do not want to be
interrupted by telephone calls.
Shift Allows you to access the top-labeled features on split-labeled, shiftable buttons,
including Select Ring. Use whenever you need to access one of these features.
Speaker Allows you to place calls or access other voice features without lifting the
handset. However, in order to speak to the other party, you must lift the handset.
Use with features that require listening only, such as on-hook dialing, monitoring calls,
on hold, and group listening situations. Note: Your voice terminal has either the
Speaker (listen-only) or the Speakerphone function. Check with the System Manager.
Speakerphone Allows you to place calls or access other voice features without lifting
the handset. Use any time you prefer hands-free communication, both speaking and
listening or for group listening. Note: Your voice terminal may be set for the Speaker
(listen-only) feature. Check with the System Manager.
Terminal Busy Indication Provides a visual indication of the busy (off-hook) or idle
(on-hook) status of a specified voice terminal. Use this information when servicing
calls for another person. For example, if you are a secretary servicing your
supervisor’s calls, use this feature to see whether your supervisor’s extension is busy
or idle.