Headset Compatibility: This Corded RJ9 Telephone headset with microphone only works with Cisco phones with RJ9 headset jack, such as CP-7821, 7841, 7861, 7931G, 7940, 7941G, 7942G, 7945G, 7960, 7961, 7962G, 7965G, 7975G 8811, 8841, 8845, 8851, 8861, 8865, 9951 etc. Crystal Clear Chat: With wideband technology the telephone headset for Cisco IP phones provides high-definition and crystal-clear communication, and noise cancelling microphone blocks out unwanted background noise and pick up loud and clear sound which makes you feel that you are having a face to face conversation. Also this wired binaural headset cover the both ears and helps you to concertrate on the call and hear less ambient noise, makes you more productivity during the conference call. Productivity & Extended Comfort: This corded telephone headset with microphone allows you to work efficiently and comfortably - you can concentrate on the conversation while working on the computer during conference calls. Adjustable headband will fit all sizes head and the soft ear cushion ensures added comfort even for long-time wearing. Great Durability: High-end materials and durable construture ensure this corded headset compatible with Cisco phone to withstand the constant demands of all-day use in busy environments. The built-in reinforced cord will protect headset against office chair wheels, sharp objects on daily use. Stainless steel headband, superior quality speaker and noise cancelling microphone, reliable plastic parts make this headset durable enough even for 24/7 busy environment. Hearing Protection: This RJ9 phone headset work for Cisco 7841 headset with built-in hearing protection circuit will provide users with safe and comfortable audio experience. It protects you from long term daily sudden sound burst, any sound above 118db is filtered out. It is a guarantee for those who takes a large volume of call every day, including call center agent, customer service, telemarketing workers etc. This wired headphone with microphone only compatibe with Cisco phone with RJ9 headset jack, please do not buy this headset for Cisco Spa series phone! This RJ9 phone headset uses wideband audio technology to assure a clear and natural sound experience, and its noise-canceling microphone filters out most background noise for clear 2-way communication. It is equipped with big soft ear cushion to ensure all-day comfortable wearing and adjustable headband let you find the perfect fit. This headset with microphone design well compatible with most phones already with RJ9 headset jack. Phone Compatibility (Included but not limited): IP Phones:  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 and 8900, 8941, 8945, 8961, 9951, 9971 Note: This RJ9 Cord ONLY Compatible with Phones with RJ9 Headset Jack!