Can H.323 And Sip Interoperate With One Another; What Is Voice Quality; How Are Voice Quality Normally Rated; What Is Codec - ZyXEL Communications P-2608HWL-D1 Support Notes

Can H.323 and SIP interoperate with one another?

In interoperability between the two, the industry is making slow but sure progress. Interoperability must first
happen between vendor implementations of the same protocol (SIP-to-SIP and H.323-to-H.323) and then
between protocols. Currently in order for SIP client to talk to H.323 client the ITSP must have a trunking
gateway act as a translator between the two protocols without the trunking gateway the two protocols are not
able to communicate to one another.

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 using a metric called the Mean Opinion Score (MOS) which is a
recommendation by ITU-T. The MOS is a 5-point scale where 5 represents excellent voice quality and 1
represents bad voice quality.

What is codec?

Codec is an algorithm that converts analog signal into digital signal and vice versa. There are three code types:
waveform codec, source codec, and hybrid codec. Each consumes different amount of bandwidth and provides
different voice quality.

What is the relation 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 the Prestige support?

The Prestige supports the following commonly used codecs.
• G.729 voice codec
• G.711u-law voice codec
• G.711a-law voice codec
All contents copyright (c) 2005 ZyXEL Communications Corporation.
P-2608HWL Series Support Notes
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