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; 6. Complies 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 communication; 10. Support Skype speed-dialing function; 11. Key-in tone function.