Comdio H303AC Corded RJ Headset with Flexible Noise Canceling Mic for Aastra Shoretel Nortel Cisco E20 Polycom 335 VVX400 Digium D40 D70 Starleaf Office Telephone IP Phones ONLY WORKS FOR SOME SPECIFIC PHONES. SEE COMPATIBLE PHONE LIST IN DESCRIPTION, BUY THE ITEM TODAY IF YOU HAVE ONE OF THE PHONE MODELS LISTED BELOW. Superior quality sound with the flexible adjustable noise cancellation microphone. Direct connect over the head headset, No additional amplifiers or adapters required, Most easy setup headset solution. Super Lightweight, Super Durable Headset with Comfortable ear and mic cushions. NO Mic Mute / Volume Control built in.