AT&T 2812B - Manual (Page 17)

14
Telephone operation
Options while on calls
Multiple handset use
While on a call, a person on the other handset can
press
PHONE
/FLASH
or SPEAKER to join the
same conversation.
A person on either handset can press
OFF
/CLEAR
,
or place the handset in the telephone base or
charger to drop out of the call, but the call will not
be terminated until both handsets hang up.
NOTE: When two handsets are used on the same outside
call, the call transfer feature cannot be used (page 16).