Plantronics WO300 Savi Office Over-the-head Monaural Noise-Canceling Wireless Office Headset for Unified Communications -- Supports leading softphone vendors; Avaya, Cisco, IBM and more, offering DECT 6.0 for an interference-free wireless range of up to 350 feet, Base unit accepts up to 4 headsets for on-the-fly conferencing, One-button call control manages PC or desk phone calls and lets you Connect and mix a softphone callon your PC with a call on your deskphone at the touch of a button