Convert 3.5mm Smartphone plug to single 4P4C RJ9/RJ10 handset plug. NOT COMPATIBLE WITH iphone Headset.Still get great quality stereo sound from headset via this adapter.ONLY COMPATIBLE WITH Cisco Unified 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 6921 6941 6945 6961 7821 7841 7861 8811 8841 8851 8861 8941 8945 8961 9951 9971 and Plantronics Amplifier: M10 M12 M22 and MX10 Vista Modular AdaptersNot Compatible With iphone and bose Headset.This adapter will allow user simply convert the headset solution for your IP phones with your exist headset that work with the standard 3.5mm smartphone.Simply plug the RJ plug into the headset port on your IP Phones, and insert your exist the standard 3.5mm smartphone headset into the other end adapter, now you are ready to make / receive phone calls on your IP phones with your standard 3.5mm smartphone headset headphones.cable length: 25cm(10inch)4P4C RJ9 Telephone CableColor: (rj9 female adapter Gray, )Wire Cable Leads color: Green, Red, Yellow, Black;Dimension: Adapter Head: 17 x 11 x 10mm/ 0.57 x 0.43 x 0.4inch(L*W*T)4P4C RJ9 Telephone Cable,616E 4P4C RJ9 Female Telephone Connector Adapter w 5 Wires Cable,A great replacement for the old one.colour: blackMaterial: plasticPackage Contents: 3 * 4P4C RJ9 Telephone Cable1 * 3.5mm female to rj9 male cableOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.