Panasonic KX-TGM420 Operating Instructions Manual page 35

• If your phone service provider requires additional
devices in order to make and receive calls, such as a
modem, you may still not be able to make and
receive calls even if the base unit's backup power
feature is functioning.
Base unit battery installation (for replacement)
Important:
• The following AAA (R03) size batteries can be used
with the base unit:
– Rechargeable Ni-MH batteries*1
– Standard (non-rechargeable) alkaline batteries*2
• Do NOT use manganese batteries.
• Confirm correct polarities (+, -).
*1 The base unit can fully charge Ni-MH batteries in
about 15 hours.
*2 If the rechargeable batteries become depleted
during a power failure, you can insert alkaline
batteries into the base unit. Remove the alkaline
batteries when power is restored.
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