ONLY order this cable if you have the Cisco IP phone models: 7920, 7921, 7921G, 7925G, 7926G, 7929. This cable has a special 2.5mm 4-conductor adapter with 3 black bands (rather than the normal 2 black bands found on cell phone headsets). The other end of the cord has QuickDisconnect to any Plantronics Call Center headset (H-series).Go here for other Cisco IP Headset models.