... server,Peer to Peer/ IP callDTMF:Support SIP info, DTMF Relay, RFC2833Advanced Application FeaturesLarge dot matrix LCD display and softkeys make ... main DNS and secondary DNS server.Support VLANSupport DMZSupport DNS Relay, SNTP Client, FirewallSupport VPN (L2TP/UDP TUNNEL) , Open VPN/TLS ...