Specifications

MyPBX U5XX Administrator's Guide
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a-law: A PSTN standard codec, used outside of North America, that
provides very good voice quality and consumes 64kbit/s in each direction
(receiving and transmitting) of a VoIP call.
GSM: A wireless standard codec, used worldwide, that provides adequate
voice quality and consumes 13.3kbit/s in each direction (receiving and
transmitting) of a VoIP call. GSM is supported by many VoIP phones.
SPEEX: Speex is an Open Source/Free Software patent-free audio
compression format designed for speech. The Speex Project aims to lower
the barrier of entry for voice applications by providing a free alternative to
expensive proprietary speech codecs. Moreover, Speex is well-adapted to
Internet applications and provides useful features that are not present in
most other codecs.
G.722: G.722 is a wideband speech coding algorithms which supports the
bit rate of 64, 56 and 48kbps wideband. It‟s a broadband voice encoding of
G series.
G.726: A PSTN codec, used worldwide, that provides good voice quality and
consumes 32kbit/s in each direction (receiving and transmitting) of a VoIP
call. G.726 is supported by some VoIP phones.
ADPCM, G.729A, H261, H263, H263p, H264,MPEG4.
Note: If you would like to use G.729, please enter your license.
Figure 6-61
4）QOS
QoS (Quality of Service) is a major issue in VOIP implementations. The issue
is how to guarantee that packet traffic for a voice or other media connection
will not be delayed or dropped due interference from other lower priority
traffic.When the network capacity is insufficient, QoS could provide priority
to users by setting the value.