Panasonic KX-TGM420 Operating Instructions Manual page 55

Turning on auto boost
If the auto boost feature is turned on, volume booster
turns on automatically when you make or answer a
call. This feature is useful if the unit is used mainly by
a user who is hard of hearing.
1 [MENU] [#] [7] [8] [2]
2 [ ]: Select the desired setting.  [SAVE] 
[OFF]
If the volume booster is turned on, the BOOST
•
indicator lights in red during a call.
Note:
• While on a call, you can temporarily turn the volume
booster off by pressing [BOOST], and adjust the
volume by pressing [+] or [–] on the side
repeatedly.
Adjusting the volume
While on a call, you can adjust the volume by pressing
[+] or [–] on the side repeatedly.
• The selected volume setting is shown on the
handset display.
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