Support two SIP servers running at the same time Redundancy SIP server support NAT,Firewall DHCP client and server Support PPPoE (used for ADSL,cable modem connceting Support major G7.xxx CODEC VAD,CNG G.165 compliant 16ms echo cancellation E.164 dial plan and customized dial rules Hotline Call Forwaard,Call Transfer,3-way conference calls Call ID display DND (Do Not Disturb),Black List,Limit List