1.Following RFC-3261 SIP standard; 2.Support RFC-3261, TCP/UDP/IP, RTP/RTCP, HTTP, ICMP, ARP, DNS, DHCP, NTP/SNTP, FTP, PPPoE protocols; 3.DynamicIPsupport( DHCP and PPPoE); 4.Support G.723.1 (6.3k/5.3k),G.729A/B,G.711(A-law/U-law) voice codecs; 5.System status display on the LCD panel; 6. Remote software upgrade capability (via ftp); 7 Passing through NAT devices