User guide

Chapter 4: Configuring Your MultiVOIP GSM
Multi-Tech Systems, Inc. MVPGSM 38
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 will 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 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
This is applicable to outgoing IP calls only. 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. 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
additional
choices
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 screen. If G.711 is the higher priority, i.e., 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
checkbox Determines whether silence compression is enabled (checked)
for this voice channel.
With Silence Compression enabled, the MultiVOIP GSM will 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
checkbox Determines whether echo cancellation is enabled (checked) for
this voice channel.
Echo Cancellation removes echo and improves sound quality
(default = on).
Forward Error
Correction
checkbox 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 doubles the
overhead to the total network bandwidth consumed by the
voice channel (default = Off).
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