Telephone Training Adapter Y Splitter+Mute Button for Headset for Nortel Meridican, Norstar, Avaya, Ashtra, Mitel, Polycom, Ge and Other Ip Phone Can plug either into handset port or headset port Mute button control with red indicator when on to avoid accidental talk into conversation Handset or Headset Splitter Great use for call center / telephone marketing trainings Easy setup, plug and play