DESC: USB VoIP Display Phone offers LCD display. Compatible with most VoIP software. Features a slim and sleek design. Screen display to view call history and contact list. Chat message. Supports multi languages. Voice conference call up to four people. No power adapter required. Complies with USB 1.1 and greater. Built-in microphone and speaker with six different volume levels four different ring tones. USB 5' cable included. Resolution 128 x 64 pixels. Operation voltage 4.75 to 5.25 Volt.