ONLY WORKS with Plantronics M10, M12, M22 & MX10 Amplifiers and CISCO IP phone models :
Cisco IP 6921, 6941, 6945, 6961, 7821, 7841, 7861 Cisco IP 7931G, 7940, 7940G, 7941, 7941G, 7942, 7942G, 7945, 7945G Cisco IP 7960, 7960G, 7961, 7961G, 7962, 7962G, 7965, 7965G Cisco IP 7970, 7970G, 7971, 7971G, 7975, 7975G Cisco IP 8811, 8841, 8845, 8851, 8861, 8941, 8945, 8961, 9951, 9971

ONLY COMPATIBLE FOR SOME SPECIFIC PHONE MODELS LISTED ABOVE. Not compatible with Cisco Spa phone series.
FOR OTHER PHONE MODELS, PLS CONTACT US FOR COMPATIBILITY GUIDE OR ADVICE.
No Volume Adjuster and Mute Switch function on the headset.