ZyXEL Communications P-2302HWUDL-P1 Series, Поддержка заметок

Страница: 154 / 185

P2302HWUDL-P1 Support Notes
All contents Copyright

2007 ZyXEL Communications Corporation.
154
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 the ZyXEL Device support?
The ZyXEL Device 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 .
What do I need in order to use SIP?
The minimum required to use VoIP is as follow.
1. A high-speed Internet connection. This can be a cable modem, or a high-speed network services such as
ISDN, DSL or a T-1 link. The need of the bandwidth required will depend on the amount of telephone traffic
will be in your network.
2. A PC with VoIP software installed or a hardware VoIP box such as ATA or device like P-2302 VoIP station
gateway.
3. An account with a VoIP provider such as an ITSP. The account can be configured to recognize your calls
automatically, or you can require the users to enter their unique account numbers issued.