Help? What headset can be used with the Panasonic KX-TG9391 Base unit?

Q:  Panasonic KX-TG9391T base unit 2-line.  What headsets available that can plug into it?  It does NOT have a headset plug built-in, but something must exist that can plug into the handset plug.  Right? Maybe?

A:  Unfortunately due to circuitry issues (buzzing, etc), Plantronics does not typically recommend any of their products for use with the Panasonic KX-TG “base” model expandable phones.