What Is Voice Quality - ZyXEL Communications Prestige 2302RL Support Notes

What is voice quality?

Voice quality is how well a person can hear the voice on the opposite end.
How are voice quality normally rated?
Voice quality is most commonly rated through a voice quality metric called the Mean Opinion Score (MOS)
which is recommendation by ITU-T. The MOS is a 5-point scale where 5 represent excellent voice quality and
1 represent bad voice quality.
What is codec?
Codec is an algorithm that converts analog signal into digital signal and vice versa. There are three codeec
types: waveform, source, and hybrid codec. Each consume different amount of bandwidth and provide different
voice quality.
What is the relationship between codec and VoIP?
VoIP is the general term to refer to the sending of digitized voice information in discrete packets over public
digital network (the Internet) where other data packets can be sent at the same time. A codec determines how
much bandwidth voice packets will use. To save bandwidth usage, you would use as little bandwidth as possible
at the cost of reduced voice quality.
What codec types does Prestige support?
The Prestige supports the following commonly used codecs.
 G.729 voice codec
 G.711u-law voice codec
 G.711a-law voice codec
Which codec should I choose?
Choose a codec that is also supported on the remote VoIP host since both ends of the VoIP connection must use
the same codec. In general, a codec with low bandwidth consumption and high voice quality is a good codec.
What do I need in order to use SIP?
The following lists the minimum requirement for running VoIP applications.
All contents copyright (c) 2007 ZyXEL Communications Corporation.
Prestige 2302RL Support Notes
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