Kuando Busylight Combi is a -headset in use- indicator. It lights up RED, when you are on a call.It also has a manual -Do Not Disturb- switch, so you can signal if you wish to concentrate without getting interrupted.Simply connect it to the Headset, handset or desk phone and download and install the software.> Features & specifications:Kuando Busylight Combi is connected to the Phone via a small box. The small light is discrete and still visible from a long distance.- Built-in speaker- Memory chip with 8 ringtones & IM tone- USB connected (HID device)- 1,5 meter cord. - Adhesive tape for easy and flexible mounting. On monitors, cubes and laptops.