Headset Compatibility Notes: Phone has designated headset port. LKA10 & AWH55 plugs into headset port, no lifter required. The AWH55 unit comes with an additional connection cable that goes from the AWH55 EU24 port to EU24 on the bottom of the phone itself. If the telephone firmware is above v 1.8 you can use the MIP adapter with the LKA10 through the headset port to get remote answering, ringing, and dialing.