Panasonic KX-TG2000B Operating Instructions Manual page 88

Using an Optional Headset
With the Cordless Handset
Connecting the headset to the cordless handset
Open the headset jack cover, and connect the headset to the headset jack
as shown.
When the headset is connected, make sure to use the headset to talk with the
caller. If you want to have a normal cordless phone conversation, disconnect the
headset.
88
Headset Jack