To activate the headset mode: 

1. Press HEADSET on the phone. 
The HEADSET key LED illuminates solid green when the headset mode is activated. 
Press the line key or the Answer soft key to answer a call, the call will connect to your headset automatically. 

To deactivate the headset mode: 

1. Press HEADSET again on the phone. 
The HEADSET key LED turns off when the headset mode is deactivated.