ZyXEL Communications 2304R-P1 User Manual

Page 92

Prestige 2304 Support Notes

gateway act as a translator between the two protocols without the truncking gateway the two protocols are not

able to communicate to one another.

What is voice quality?

Voice quality is how well an 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 a algorithm which converts analog signal into digital signal and vice versa. There are three main type

of waveform codec, source codec, and hybrid codec. Each consume different amount of bandwidth and provide

different voice quality level.

What is the relation of codec and VoIP?

As VoIP is a general term send voice information in digital form in discrete packets over digital network and

this digital network is public network, thus there maybe other packet such data packet uses network at the same

time. The codec choose is related to how much bandwidth voice packet will consume. In bandwidthwise

aspect the smaller amount of bandwidth used the better. But in voice aspect the higher quality the better.

What codec does Prestige support?

Prestige supports the following commonly used codec.

• G.729 voice codec
• G.711u-law voice codec
• G.711a-law voice codec

Which codec should I choose?

As which codec choose is depending on what codec is supported on both end of the VoIP host. Generally a

codec with low bandwidth consumption and high voice quality is a good codec .