... this modular plug into the headset jack on your phone (phone must be headset-ready, see list below) ... Lucent: 4004, 4020, 4022, 4035, 4037 Telephones AltiGen phone Models: 500, 510, 600, 705, 710, 720 ... IP601 IP Phones Safecom: SDSIP-500IP SIP Phones ShoreTel Phone: IP100, IP212K, IP230, IP265, IP530, IP560, ... 2-line) Uniden: 420 and 450Binaural headset photo: Binaural Call center handsfree headset