User guide

Chapter 4 – Configuring Your MultiVOIP
40 MultiVOIP® Voice/Fax over IP Gateways
Voice/Fax Parameter Definitions (continued)
Coder Parameters
Coder
Manual or
Automatic
Determines whether selection of coder is manual or automatic. When
Automatic is selected, the local and remote voice channels negotiate
the voice coder to be used by selecting the highest bandwidth coder
supported by both sides without exceeding the Max Bandwidth
setting. G.723, G.729, or G.711 are negotiated.
Selected Coder
(SS models only)
G.711 a/u law 64 kbps;
G.726, @ 16/24/32/40 kbps;
G.727, @ nine bps rates;
G.723.1 @ 5.3 kbps, 6.3 kbps;
G.729, 8kbps;
Net Coder @
6.4, 7.2, 8, 8.8, 9.6 kbps
Select from a range of coders with specific bandwidths. The higher the
bps rate, the more bandwidth is used. The channel that you are calling
must have the same voice coder selected.
Default = G.723.1 @ 6.3 kbps, as required for H.323. Here 64K of digital
voice is compressed to 6.3K, allowing several simultaneous
conversations over the same bandwidth that would otherwise carry
only one.
To make selections from the Selected Coder drop-down list, the
Manual option must be enabled.
Selected Coder
G.711, G.729
-or-
G.729, G.711
Coder Priority has two options (G.711,G.729 or G.729, G711) on the
Selected Coder listing of the Coder group on the Voice/Fax window. If
G.711 is the higher priority, that is, G.711 is preferred to G729 on the
sending side, then G.711, G.729 option is selected. Similarly, if G.729
has the higher priority, then G.729, G.711 option is selected.
It is used whenever a user wants to advertise both G.711 and G.729
coders with higher preference to a particular coder.
It is useful when the calls are made from a particular channel on the
VOIP to two different destinations where one supports G.711 and the
other supports G.729.
Max bandwidth
(coder)
11 – 128 kbps
This drop-down list enables you to select the maximum bandwidth
allowed for this channel. The Max Bandwidth drop-down list is enabled
only if the Coder is set to Automatic.
If coder is to be selected automatically (“Auto” setting), then enter a
value for maximum bandwidth.
Advanced Features
Silence
Compression
Y/N
Determines whether silence compression is enabled (checked) for this
voice channel.
With Silence Compression enabled, the MultiVOIP does not transmit
voice packets when silence is detected, thereby reducing the amount
of network bandwidth that is being used by the voice channel (default
= on).
Echo Cancellation
Y/N
Determines whether echo cancellation is enabled (checked) for this
voice channel.
Echo Cancellation removes echo and improves sound quality (default =
on).
Forward Error
Correction
Y/N
Determines whether forward error correction is enabled (checked) for
this voice channel.
Forward Error Correction enables some of the voice packets that were
corrupted or lost to be recovered. FEC adds an additional 50%
overhead to the total network bandwidth consumed by the voice
channel (default = Off).
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