Yealink DECT Conference Phone , Built-in Battery , Built-in Bluetooth 4.0 , Built-in 3-Microphone Array , Optima HD Voice, Full Duplex Technology, 20-Foot (6-Meter) and 360-Degree Microphone Pickup Range , Yealink Noise Proof Technology , 5-Way Conference Call , Connect to PC via Micro USB Port , Hybrid UC Meeting , 3.1” 248×120-Pixel Graphical LCD with Backlight,Support Call Recording via Micro SD Card, Sensitive Touch Keypad, Upgrade Over the Air , Charging Cradle