... , 1LAN, 2SIP accounts, 3way conference call, full duplex hand-free speaker phone, support SMS Features: Support SIP 2.0 (RFC3261 ... G.726 Echo cancellation: Support G.168, and Hands-free can support 96ms, Hand free Speaker Phone Support Voice Gain Setting, VAD, CNG ... Full duplex hands-free speakerphone NAT transverse: support STUN client SIP support SIP domain ...