20-key display keysets have an inbuilt headset socket
enabling a non-amplified headset to be easily connected. A feature key programmed as
(Function 9 #) can be used to turn headset mode on or off.
In headset mode, the speaker key is used to answer an incoming call
and subsequently used to toggle the call between the headset and handsfree operation. The
clear key is used to terminate a headset call. If the handset is picked-up during a
headset call, the call transfers to the handset.