3Com NBX 100 Administrator's Manual page 260

260 C 5: S
HAPTER YSTEM
C
ONFIGURATION
Suppression, a careful listener might notice a difference in audio quality.
The background white noise generated by the receiving phone is subtly
different from the silence in an audio stream.
Silence suppression and echo suppression (described next) both result in
compromises to audio quality. Do not enable suppression settings unless
you are trying to solve network bandwidth congestion issues that you
cannot solve through other means such as increasing network capacity.
Echo Suppression Overview
Echo suppression is a method of reducing or eliminating audio feedback
(echo). The NBX system has internal mechanisms to deal with echo,
however, external conditions can induce echo that is beyond the scope of
the internal mechanisms. Echo on external calls is usually due to older
equipment at the phone company's central office. Echo can also be
caused by user behavior. If a caller has the phone volume turned up and
then that caller does not hold the phone flush to their ear, the handset's
mouthpiece can pick up audio from the ear piece, which can cause echo.
To enable audio settings, select System Configuration > System Settings >
Audio Settings.
Table 36 System Settings Audio Settings Dialog Box Fields
Field
Bandwidth Controls reduce the number or the size of packets transmitted during
a conversation. You can enable bandwidth controls to help reduce network
congestion, however, enabling bandwidth controls can compromise audio quality.
System-wide
Silence Suppression
System-wide
Silence Suppression
on VTL Calls
Purpose
Reduces the number of packets transmitted during a
conversation by not transmitting packets during times of
silence during a conversation. Enabling this check box enables
silence suppression on all conversations.
Implements silence suppression on calls carried over Virtual Tie
Lines.