... .You plug this modular plug into the headset jack on your phone (phone must be headset-ready, see list below) Superior sound ... NT8B50, NTZK23AA, NTZKAB: (M2216): ACDI Orchid: DBT 2000, DBT 3000 Plantronics: A100, S10, S11, S50, T10, T20, T50, T100, T110 ... option modules Optiset E Advance Optiset Advance Plus+ Headset Adapter Comfort 300E+ Headset Adapter Comfort F300E Optipoint 410 Standard & Advance ...