Audicom 2.5mm Call Center Headset with Mic + Quick Disconnect Headphone for Polycom IP320 IP321 IP330 IP331 SoundPoint Pro SE-220 Zultys Technologies: ZIP 4x4 ZIP 4x5 Telephone IP Phones (700RQD25B) Direct connect over-the-head 2.5mm headset, No additional amplifiers or adapters required, Most easy setup headset solution. Noise canceling microphone to reduce background noise and Acoustic Shock Protection circuit to protect your hearing. Superior Call Center quality headset, excellent sound quality, lightweight, durable and comfortable for all day use. ONLY PURCHASE IF YOU HAVE ONE OF THE PHONE MODELS LISTED BELOW, CHECK OUR STORE FOR HEADSETS FOR OTHER PHONE MODELS OR CONTACT US FOR COMPATIBILITY GUIDE! NO Mic Mute / Volume Control built in. 2.5MM HEADSET, ONLY COMPATIBLE WITH PHONES WITH 2.5MM HEADSET JACK.