... support 1. PC-to-PC and PC-to-phone operation; 2. USB1.0 & 2.0 Compatible ... Vonage, UBIFONE, Imtel, Voip Buster, Voip discount , Voipcheap, VOIP Stunt, SparVOIP, INTERNETCALLS, NetAppel, YpoivyY, FreeCall, WebCall, VOIP RAIDER, VoipWise Onet2phone; ... 8. Full duplex communication; 9. Support Skype speed-dialing function; 10. Key-in tone function. WIDETELL USB VOIP PHONE ...