LevelOne VOI-7100 - Manual (Page 46)

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Codec Priority Adjust Codec priority to meet your
requirement, lower number shows higher
priority.
RTP Packet
Length Adjust Codec g711, g729 and g723 packet
length
G.723 5.3K Enables 5.3K bit/s rate when use g723
Voice VAD VAD (Voice Activity Detection) is used to
reduce the transmission rate during
inactive speech periods. VAD classifies
the input signal into active speech,
inactive speech or background noise.
Based on the VAD decisions.
One of the most important factors is how much bandwidth is used for each
VoIP call. The higher the CODEC bandwidth is, the higher the cost of each call
across the network will be.
Following is a list of CODECs and their associated bandwidth:
G.711 The G.711 pulse code modulation (PCM) coding scheme uses the most
bandwidth. G.711 takes samples 8000 times per second, each of which is 8 bits
in length, for a total bandwidth of 64,000 bps.
G.726 The G.726 adaptive differential pulse code modulation (ADPCM) coding
schemes use somewhat less bandwidth. While each coding scheme takes
samples 8000 times per second like PCM, G.726 ADPCM uses 4, 3, or 2 bits
for each sample, thereby resulting in total required bandwidths of 32,000,
24,000, or 16,000 bps.