Support 2.0 (RFC3261) and correlative RFCs Support IAX2 Support 2 SIP lines Codec:G.711A/u G.723.1 high/lowG.729 a/b G.722.1G.726 Support HD voice Soft keys programmable Hard function key reprogrammable SIP application:support call forward/transfer(blind/attended)/holding/waiting/3 way talking/conference/pickup/join call/redial and unredial/ Click to dial/secondary dialing automatically Support SRTP Support BLF Two 10/100 BaseT Ethernet Interface 128*48 FSTN graphic LCD Support Multi-line Support IAX2 line key Support Open VPN and L2TP 4 DSS keys PoE(optional) TR-069(optional)