Usage: USB conference phone provides free VoIP conference all through Skype, QQ, ICQ, MSN Messenger and Yahoo messengers. The advanced DSP based acoustic echo cancellation functions makes the conference call crystal clear. For business, SOHO, Telecommuter and residential users who use Skype, QQ for voice communications. Relative model: VoiceCrystal P. Functions & Features: Full-duplex conversation, crystal clear voice Best for the conference room within 30 m2 and Microphones gather covers 3m Easy installation Support within 10 attendees Deep Echo cancellation Bi-directional noise suppression purifies voice signal from both parties. Hypercardioid directional microphone plus AGC automatic gain control satisfy group conference Hi-Fi audio amplifier and rare-earth Neodymium magnet speaker LCD with Caller ID Convenience redial,on hold,mute and rapid-dial SonicClear patented voice processing technology Compatible with USB VoIP