Voice activity detection （VAD） suppresses the transmission of silence patterns. On average， and assuming that a link carries at least 24 calls， what percentage of total bandwidth could VAD save？（）

A.bursty
B.constant
C.bandwidth intensive
D.small packet sizes
E.time-sensitive
F.retransmittable

A.IP
B.TCP
C.RTP
D.UDP
E.H323
F.CRTP

A.the VoIP endpoints have the intelligence to set up and control calls
B.Call setup and control functionality is centralized in one call agent or cluster
C.Call setup and control resides in call agents that are distributed throughout the network
D.Each VoIP device has separate call control， voice packetization， and transport mechanisms