NEC NEAX 2400 IPX Reference Manual page 18

Feature + 3 Selects from 4 ring tones (repeat key "3"
Feature + 4 Adjusts transmission/receiving volume.
Feature + 5 Activates hands free operation.
Feature + 6 Deactivates hands free operation.
Feature + 7 Turns call indicator lamp ON/OFF. (If
Function Keys
Recall
Press this key to terminate current call and re-seize
dial tone.
Feature
Used to activate Dterm setup functions and to program
Speed Dial/Feature keys.
Conf (Conference)
Press this key to establish a 3-way conversation. LED
on key lights when key is active.
Redial
Press this key to activate Last Number Redial, Stack
Dial and Speed Calling.
Speaker
Controls the built-in speaker, which can be used for
hands free dialling/monitoring LED on key lights when
key is active.
18
to select tone).
turned OFF, this lamp will still light to
indicate message waiting.)