If the headset is a wireless one there is a button on the headset itself you need to press to pick up or hang up a call. alternativly look for a headset or pick up button on the phone needs to be pressed. this i diffulcult to answer further without knowing the model of your headset.
download user manual for the phone at the following http://www.tc.mtu.edu/voice/equipment/Mitel5220/5220userguideR4.0.pdf check page 23 regarding using heaset.
when the phone rings press the headset feature on your phone and then select the ringing line button. then press cancel to hang up.
Answers & Comments
If the headset is a wireless one there is a button on the headset itself you need to press to pick up or hang up a call. alternativly look for a headset or pick up button on the phone needs to be pressed. this i diffulcult to answer further without knowing the model of your headset.
download user manual for the phone at the following
http://www.tc.mtu.edu/voice/equipment/Mitel5220/5220userguideR4.0.pdf
check page 23 regarding using heaset.
when the phone rings press the headset feature on your phone and then select the ringing line button.
then press cancel to hang up.
I hope this was useful.