1.Support three SIP servers running at the same time 2.Provide two backup SIP servers IP Phone system: CPH-665 Features:Support three SIP servers running at the same time Provide two backup SIP serversVoice code: G.711A/u, G.723.1 high/low, G.729a/b, G.722, G.726G.168 compliant echo cancellation(64ms/96ms/128ms)VAD (voice active detect) CNG (comfort noise generation) Support Voice Gain Setting ...