1.Support two sip servers running at the same time. 2.Redundancy sip server capable. Support PPPoE, (used for ADSL, cable modem connecting). Support major G7.xxx CODEC. VAD, CNG 3.G.165 compliant 16ms echo cancellation E.164 dial plan and customized dial rules 4Call Forward, Call Transfer, 3-way conference calls DND(Do Not Disturb),Black List, Limit List