Uniden EXS 9800 Owner's Manual page 11

6. Align the mounting slots on the
base with the mounting screws on
the wall. Push in and down until
the phone is firmly seated.
7. On the base, pull the handset retainer
out of the slot. Rotate clockwise 180°.
8. Flip the retainer from front to back.
Slide it back into the slot so that the lip
of the retainer is up and the oval is down.
The retainer holds the handset in place.
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