2. 1 WAN,1 LAN,4 FXS Ports for 4 Phones 3. CodecG.711A/u,G.7231 high/low,G.729 4. Echo cancellationSupport G.168 5. Support Voice Gain Setting, Jitter Buffer,VAD,CNG 6. NAT transversesupport STUN client, Citron, AVS 7. SIP support SIP domain,SIP authentication (none,basic, MD5),DNS name of server, Peer to Peer 8. SIP support dual public server 9. DTMFSupport SIP info,DTMF Relay,RFC2833 10. SIP application: support Call forward/transfer/holding/waiting 11. Call control features: 12. Flexible dial map support Hotline 13. Empty calling No. reject service 14. Black list for reject authenticated call 15. No disturb 16. Caller ID 17. Support T.38 Fax