BT20 USB BT Dongle is a low-power, small form factor device that can be implemented within offices for connecting their IP phones to available Bluetooth headset. BT20, compatible with a variety of brands of Bluetooth headsets, users can answer / hang up the phone within the Bluetooth communication range. BT20 is Bluetooth specification V4.0, back compatible with Bluetooth 2.0, 2.1 and 3.0 for wide-ranging use.