Panasonic KX-TG2226B Service Manual page 40

b) BASE UNIT
A short beep followed by a long beep is heard. This indicates the unit is in TEST POWER LOW
mode. Once in TEST POWER LOW mode, to return the unit to the original NORMAL POWER
mode, press 2, 5, 8, 0 simultaneously while the handset unit is in stand-by (not in use, not
charging). A long beep is heard. Then disconnect the battery from the handset. Reconnect the
battery and place the handset on the cradle to exchange security codes. A single beep is heard.
Note:
You can check the other channels as follows, if need.
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