24
Setup DSP (CODEC)
CODEC is an algorithm which converts analog signal into digital signal and vice versa.
There are three main types of waveform codec, source codec, and hybrid codec.
Each consume different amount of bandwidth and provide different voice quality
level.
As VoIP is a general term sends voice information in digital form in discrete packets
over digital network and this digital network is public network, thus there may be
other packet such as data packet uses network at the same time. The codec choice
is related to how much bandwidth voice packet will consume. In bandwidth wise
aspect the smaller amount of bandwidth used the better. But in voice aspect the
higher quality the better.
VoIP line card supports the following commonly used CODEC.
G711a,
G711mu,
G723,
G726-16,
G726-24,
G726-32
G726-40,
G729ab
Note: G.711 mu-law or G.711 a-law is country specific, thus ZyXEL device is shipped
preconfigured to use u-law or a-law according to specific country. If for special
reason this setting needed to be changed, it can be modify through device CI
command through telnet. For the command please refer to the CI command list in
the firmware release note.
CODEC choice is depending on what codec is supported on both ends of the VoIP
hosts. Generally a codec with low bandwidth consumption and high voice quality is
a good CODEC.
The usage is as following:
MSC1024GB> profile voip dsp set