Headset Adapter HP100 RJ9 Headset for Nortel M2008 M2616 M3903 M3904 M7310 T7208 T7208 T7316 & Polycom 300 301 335 500 600 601 Phones Monaural Over-The-Head Noise-Canceling Quality Headset with coiled cable with RJ9 modular plug for Polycom 670 CX600 VVX300 VVX310 VVX 400 VVX410 VVX500 VVX600 IP Phone Omni-directional microphone One earpiece provide great sound plus over-the-head-stability No Quick Disconnect feature but its RJ-9 modular plug allows you to walk away from the phone while still wearing your headset This CallTel Hp100 Monaural Over-The-Head Quality Headsets are also compatible with telephones with a built-in amplifier Some specific models