The telephone has a headset socket which you can control using the key headset HEADSET button.

To use the headset: (9504/9508)

To make and answer calls on the headset, use the key headset HEADSET button in the same way as lifting or replacing the handset. The button is lit while the phone is in headset mode.

Remaining in Headset Mode
If you use the DROP key to end a headset call, the phone will remain in headset mode. New calls will alert on the headset. You can use the Intercom, Call Appearance, Line Appearance and Drop buttons to make and answer calls while remaining in headset mode.

If not already in headset mode, when you make or answer calls by first pressing an Intercom, Call Appearance or Line Appearance button, the call is automatically connected either on the speaker or headset. Which is used is set by the phone's Default Hands Audio Path setting.

If already using the handset, you can switch to headset by pressing key headset HEADSET. You can then replace the handset.