Panasonic KX-TGF675 Operating Instructions Manual page 27

You should leave one handset on the base
unit for supplying the power, and use another
handset for making calls.
Answering calls during a power
failure
n When only 1 handset is registered:
1
When the unit rings, keep the handset
on the base unit and press M
MZN.
R Speakerphone is turned on.
2
When you finish talking, press MOFFN.
n When 2 or more handsets are registered:
When the unit rings, use a handset which is
not supplying power to the base unit.
R Do not use or lift the handset which is
placed on the base unit during power
backup mode.
Note:
R The range of the base unit is limited during
a power failure. Please use the handset
close to the base unit.
For assistance, please visit http://shop.panasonic.com/support
Making/Answering Calls Using the Handset
N or
27