Headset Compatibility: This wired headphones with microphone only works on Cisco IP phones with RJ9 headset jack, such as Cisco 6821, 6841, 6851, 6921, 6941, 6945, 6961, 7821, 7841, 7861, 7931G, 7940, 7940G, 7941, 7941G, 7942G, 7945, 7945G, 7960, 7960G, 7961, 7961G, 7962G, 7965G, 7970, 7970G, 7971G, 7975G, 7985G, 8811, 8841, 8845, 8851, 8861, 8865, 8941, 8945, 8961, 9951, 9971. Please do not buy this headset for Cisco SPA series phones. Headsets for Higher Productivity: Telephone headset makes your hands free when answering calls so you can still do multiple tasks at the same time. Phone headset with microphone noise canceling delivers more crystal clear sound comparing to handset, callers can hear your word clearly without missing any important information and have a better communication experience. Durable Headset for Call Center: MKJ Cisco headset with microphone is designed with sturdy construction to withstand the most demanding environments in call centers, busy offices, telemarketing centers etc. High-quality PU materials and the reinforced cord is used to against office chair wheels, sharp objects in the daily use. MKJ wired headphones are subjected to drop test, plug and play test, high and low temperature test to ensure the headset reliability for lasting use. Comfortable Headset for Call Center & Office: MKJ Cisco phone headset is with an ergonomic design to provide all-day wearing comfort in call centers and busy offices. The adjustable headband fits for any head sizes, 330° rotatable microphone boom can be easily adjusted for any talking position, soft ear cushions let users enjoy extended wear without any discomfort. Crystal Clear Sound: MKJ wired headphones with RJ9 Jack is ergonomic designed to help call center professionals to handle the heavy calls at ease. With its noise-canceling microphone to reduce most of background noise, this Cisco compatible phone headset delivers HD sound so your caller can hear your voice clearly. Also, the wideband speaker with frequency range 50HZ-10KHZ enable Cisco headset delivering more richer and natural sound.