1.PC-to-PC and PC-to-phone operation; 2.Driver built-in, plug and play; 3.USB1.1 compatible; 4.No need sound card; 5.No external power required; plies with H.323, MGCP, SIP protocol; 7.Echo cancellation, noise reduction; 8.Application support: Skype, Netmeeting /Messenger,Sjphone, Mediaring, Net2phone, Dialpad, Etalk, X-PRO, X-PRO Vonage, Firefly, Eyebeam and so on; 9.Full duplex com