Compatible Phones List: This professional Cisco phone headset ONLY compatible for some Plantronics Amplifiers and Cisco IP phones (please refer to compatible phone list below for details. If your phone model is not listed, please do not buy it and consult with us for compatibility advice and guide.) Notice: Not compatible with Cisco Spa phone series. Not for cell phones and computers. Plantronics: M10, M12, M22 & MX10 Amplifiers Cisco IP Phones: 7931G, 7940, 7940G, 7941, 7941G, 7942, 7942G, 7945, 7945G, 7960, 7960G, 7961, 7961G, 7962, 7962G, 7965, 7965G, 7970, 7970G, 7971, 7971G, 7975, 7975G, 6821, 6841, 6851, 6921, 6941, 6945, 6961, 7811 7821, 7841, 7861, 8811, 8841, 8845, 8851, 8861, 8941, 8945, 8961, 9951, 9971 Crystal Clear Communication phone headset for Cisco office phones with noise cancelling microphone and flexible boom mic delivers crystal-clear conversations even in noisy work environments. Acoustic Shock Protection protects our hearing carefully from sudden sound burst. Convenient In-line Controls Conveniently adjust this RJ9 telephone headset volume up/down, long press and hold to mute, release to unmute the microphone. Directly Plug and use with your Cisco IP phones without additional amplifiers or adapters. Super Comfortable This hands free phone headset with super soft ear cushion greatly improves the comfort of wearing all day and reduces pain on your neck and shoulder. Super lightweight and adjustable headband allow you to focus more on your calls and increase efficiency.