Features: 1) PC-to-PC and PC-to-phone operation 2) Driver built-in, plug and play 3) USB1.1 compatible, no need sound card 4) No external power required 5) Complies with H.323, MGCP, SIP protocol 6) Echo cancellation, noise reduction 7) Full duplex communication 8) Application support: Netmeeting / Messenger, Mediaring, Net2phone, Dialpad 9) Key-in tone function