... two backup SIP servers IP Phone system: CPH-665 Features:Support three SIP servers running at the same time Provide two ... (voice active detect) CNG (comfort noise generation) Support Voice Gain Setting GSM, AMR, ILBC Support bridge and routing modeDTMF Sip Info, DTMF ... for ADSL, cable modem connecting) VLAN(802.1P 802.1Q)Support DMZ, DNS Relay, SNTP Client, FirewallSupport network tools: ping, trace ...