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. Support Skype speed-dialing function; 9. Full duplex communication; 10.Key-in tone function.