2 SIP Lines + 1 IAX2 Line Asterisk, 3CX Compatible VoIP Phone 2 RJ 45 Ports Support VLAN,VPN (L2TP/UDP) ... low, G.729 A/B Support G.168 echo cancellation standard, compliant 96ms echo cancellation Support voice volume adjustment, including IN/OUT ... (Voice Activity Detection) Support CNG (Comfort Noise Generation) Support Echo Suppression and AGC (Automatic Gain Control) Support DIGEST validate and MD5/ ...