Key Tones; Message Indicator - Panasonic KX-TGM420 Operating Instructions Manual

Key tones

Use this procedure to change the volume of the tones
that sound when you press keys on the handset and
base unit, or to turn them off. The default setting is
"Low". Includes confirmation tones and error tones,
etc. This feature can be set for each unit.
1 For handset: [MENU] [#] [1] [6] [5]
For base unit (using a handset):
[MENU] [#] [*] [1] [6] [5]
2 [ ]: Select the desired setting.  [SAVE] 
[OFF]

Message indicator

The message indicator on the handset and base unit
can indicate unit status, as explained below.
Indicator Status
Flashing
rapidly
60 | P a g e
– Outside call or intercom call is being
received or on hold. (page 69, 70, 82)
– The handset alarm is sounding. (page
121)