VTech 15750 User Manual page 18

Power-fail backup mode operation
During power-fail backup mode, the telephone base,
answering system and all Bluetooth related features
will be disabled. The operating time is subject to the
battery level of the handset placed in the telephone
base and the actual usage. For optimal performance,
you are not recommended to use the handset placed in
the telephone base when this mode is on.
Using other system handsets (Recommended):
Operate the handsets the same way as usual, except
the answering system and all Bluetooth related
features which will be disabled.
Using the handset placed in the telephone base:
To maximize the operating time, you are not advised
to use this handset. If you do have to use it, make sure
you do not lift it from the telephone base. All operations
should be done with the handset placed in the
telephone base. In this case, calls can only be made and
received using the speakerphone.
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