AT&T 2256 - Manual (Page 29)

2 6
C o n f e rence Calling
1 If one handset is already on a call, you can
connect the second handset to the call by
pressing on the second handset
— OR —
Press
at the active handset. When
someone at the second handset answers,press
and hold
.
2 Disconnect either or both handsets by
pressing
.