AT&T E5654B - Manual (Page 49)

Appendix
If you are replacing a handset on a system that has the maximum number of registered
handsets (four) or wish to change the assigned handset number of your registered
handsets, you must first de-register the handsets, then re-register all handsets.
To de-register all handsets
• Press the
*883244#
on the base dial pad.
• Press
SELECT/MENU
on the base.
All handsets will lose registration with the base and the handsets will
display (can take up to 30 seconds):
The handsets have been de-registered from the base, and can now be re-registered
(see page 48).
Replacing a handset
ENTER BASE ID