AT&T AT3111-2 - Manual (Page 40)

Appendix
36
You may need to de-register your handsets if:
You have the maximum number of registered handsets (five) and need to
replace a handset.
-OR-
You wish to change the designated handset number of your registered
handsets.
You must first de-register ALL the handsets, and then re-register ALL the
handsets you wish to use.
Please read carefully through all the instructions on this page before
beginning the de-registration process.
To de-register all handsets
1. Press and hold
FIND HANDSET on the telephone base for about 10
seconds (until the IN USE light turns on and starts to flash), then release
the FIND HANDSET button.
2. Immediately press and release FIND HANDSET again. You must press FIND
HANDSET while the IN USE light is still flashing. The IN USE light will flash
for approximately seven seconds.
3. Soon, the handsets will show handset(s) will show CONNECTING... and it
will take about 10 seconds to complete the de-registration process. All
handsets will show NOT REGISTERED if de-registration is successful.
4. To re-register the handset(s) to the telephone base, follow the
registration instructions on page 35.
NOTES:
1. If the de-registration process is not successful, you may need to reset the system and try
again. To reset: pick up the handset and press the /FLASH button, then press the
OFF/CLEAR button and place the handset back into the telephone base. You may also reset
by unplugging the power from the telephone base then plugging it back in.
2. You cannot de-register the handset(s) if any telephone connected to the telephone line is in use.
Replacing a handset
NOT REGISTERED