Plantronics CS50 900 MHz Wireless Office Headset System (Discontinued by Manufacturer) Call controls at your finger tips; call answer/end, volume +/-, and mute Noise-cancelling microphone filters out background noise Remote ring detection Roam up to 300 feet from your office phone. Up to eight hours talk time per battery charge In case the unit does not charge kindly try replacing the battery. The unit is compatible with the following brands - cisco, avaya, polycom, at&t and panasonic Call controls at your finger tips; call answer/end, volume +/-, and mute Noise-cancelling microphone filters out background noise Remote ring detection Roam up to 300 feet from your office phone Up to eight hours talk time per battery charge