Mwi (Message Waiting Indication); Quality Of Service (Qos) - ZyXEL Communications V300-T1 User Manual

Chapter 10 SIP Account Setup
However, DPCM produces a high quality signal (high signal-to-noise ratio or SNR) for
high difference signals (where the actual signal is very different from what was predicted)
but a poor quality signal (low SNR) for low difference signals (where the actual signal is
very similar to what was predicted). This is because the level of quantization noise is the
same at all signal levels. Adaptive DPCM solves this problem by adapting the difference
signal's level of quantization according to the audio signal's difference level. A low
difference signal is given a higher quantization level, increasing its signal-to-noise ratio.
This provides a similar sound quality at all signal levels.
G.722 samples audio at 16 kHz; twice the traditional rate of 8 kHz. G.722 provides
excellent quality audio and requires 48 to 64 kbps.
• G.722.2 is similar to G.722, but with a lower compression rate that can vary according to
the amount of available bandwidth. When there is plenty of bandwidth, the compression
ratio decreases, and when there is network congestion the compression ratio increases.
G.722.2 is also known as Adaptive Multi Rate - WideBand (AMR-WB).
• G.723.1 is a Code Excited Linear Prediction (CELP) codec that compresses voice audio in
30 ms frames. G.723.1 operates at two bitrates: 6.3 kbps when sampling at 24 bytes or 5.3
kbps when sampling at 20 bytes per 30 ms frame.
• G.726 is an ADPCM waveform codec that uses a lower bitrate than standard PCM
conversion. G.726 operates at 16, 24, 32 or 40 kbps.
• G.729 is an Analysis-by-Synthesis (AbS) hybrid waveform codec. It uses a filter based on
information about how the human vocal tract produces sounds. The codec analyzes the
incoming voice signal and attempts to synthesize it using its list of voice elements. It tests
the synthesized signal against the original and, if it is acceptable, transmits details of the
voice elements it used to make the synthesis. Because the codec at the receiving end has
the same list, it can exactly recreate the synthesized audio signal.
G.729 provides good sound quality and reduces the required bandwidth to 8kbps.

10.1.9 MWI (Message Waiting Indication)

Enable Message Waiting Indication (MWI) enables your phone to give you a message–waiting
(beeping) dial tone when you have one or more voice messages. Your VoIP service provider
must have a messaging system that sends message-waiting-status SIP packets as defined in
RFC 3842.

10.1.10 Quality of Service (QoS)

Quality of Service (QoS) refers to both a network's ability to deliver data with minimum delay
and the networking methods used to provide bandwidth for real-time multimedia applications.
10.1.10.1 Type Of Service (ToS)
Network traffic can be classified by setting the ToS (Type Of Service) values at the data source
(for example, at the V300) so a server can decide the best method of delivery, that is the least
cost, fastest route and so on.
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V300 User's Guide