Uniden XCA4500 - Manual (Page 11)

Installing the Backup Battery
In the event of a power outage, your phone has a 9-volt battery backup
which can prevent the loss of your messages for up to four hours.
1. Press down and away from
the Base to remove the cover.
2. Place the battery in the
compartment.
Note: Make sure that the
positive battery terminal
touches the left contact.
3. Replace the battery cover.
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