Digium, Inc.
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Chapter 3: Telephone System Configuration
MWI Mode - This option allows the user to specify the type of Mes-
sage Waiting Indicator detection to be done on trunk (FXO) interfaces.
The options are none, which performs no detection, FSK which per-
forms Frequency Shift Key detection, or NEON which perform Neon
MWI dection. The default value is none.
Echo Cancellation NLP Type - This option allows you to specify the
type of Non Linear Processor you want applied to the post echo-can-
celled audio reflections received from analog connections. There are
several options:
–
None - This setting disables NLP processing and is not a recom-
mended setting. Under most circumstances, choosing None will
cause some residual echo.
–
Mute - This setting causes the NLP to mute inbound audio streams
while a user connected to the appliance is speaking. For users in
quiet environments, Mute may be acceptable.
–
Random Noise - This setting causes the NLP to inject random noise
to mask the echo reflection. For users in normal environments, Ran-
dom Noise may be acceptable.
–
Hoth Noise - This setting causes the NLP to inject a low-end Gauss-
ian noise with a frequency spectrum similar to voice. For users in
normal environments, Hoth Noise may be acceptable.
–
Suppression NLP - This setting causes the NLP to suppress echo
reflections by reducing the amplitude of their volume. Suppression
may be used in combination with the Echo cancellation NLP Max
