Sparklan WVTR-141, Руководство пользователя

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1.3.2 STUN, Simple Traversal of UDP through NAT
STUN can be used to help your, WIFI-ATA, to find the present types of NAT routers
and/or firewalls between it and the public Internet. STUN also allows the WIFI-ATA to
find the public IP address that NAT has assigned, so that the WIFI-ATA can embed it
in the SIP data stream. However, STUN does not work with symmetric NAT routers or
firewalls. For more information, please refer to RFC 3489 on STUN.
1.3.3 Voice Codec
A codec (coder/decoder) converts analog voice signals into digital signals and
decodes the digital signals back into voice signals. Each codec has its positive part,
good voice quality and bad part, bandwidth consumption. WIFI-ATA supports the
following codecs.
z
ITU-T G.711
：
G.711 is a Pulse Code Modulation (PCM) waveform codec. G.711
provides very good voice quality but requires 64 K bit/s of bandwidth.
z
ITU-T G.729
：
G.729 is an Analysis-by-Synthesis (ABS) hybrid waveform codec
that uses a filter based information about how the human vocal tract produces
sounds. G.729 provides good voice quality and reduces the required bandwidth to
8 K bit/s.
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