Configuring MultiVoice
Configuration options
MultiVoice Gateway for the MAX— User’s Guide
Preliminary November 23, 1998
6-5
Silence detection and comfort noise generation
The MultiVoice Gateway can be configured to detect periods of silence during voice calls,
suppress transmission of voice packets during silent periods, and generate white (comfort)
noise to assure the user that a call is still connected during silent periods.
The Silence Detect/CNG parameter is used to enable/disable the silence detection and
suppression, and noise generation feature on the MultiVoice Gateway. Enabling this feature
prevents silence frames from being passed over the network, reducing the effective bandwidth
of the MultiVoice call. During those silent periods, the local Gateway will generate
background (comfort) noise to assure the caller that the call is still connected during these
silent periods. You may toggle between
Yes
and
No
, to enable/disable this feature. This value
defaults to No. Changes to this value become effective with the next MultiVoice call.
Note:
This parameter is ignored (
Silence
Detect/CNG=N/A
) when the MultiVoice
Gateway uses the G.723.1 audio codec (
Pkt
Audio
Mode=G.723
).
Dynamic jitter buffer control
MultiVoice calls are processed using packet-based jitter buffering. As the MultiVoice Gateway
processes each voice call, the jitter buffer size is automatically adjusted to a length of time
appropriate for processing a fixed number of RTP packets, regardless of which audio codec is
used to process those packets. A unique jitter buffer is opened for each call, which dynamically
adjusts its size to accommodate network conditions, such as:
•
low latency as a result of high network throughput
•
increased latency as a result of reduced network throughput
The Enable Adaptive Jtr Buf parameter changes the jitter buffer mode to either adaptive or
fixed for the MultiVoice calls. When the adaptive mode is selected, the jitter buffer size will
increase or decrease, depending on the number of late or out-of-sequence packets received,
between the values set for Max Jtr Buf Size and Initial Jtr Buf Size. You may toggle between
Yes
and
No
, to enable/disable this feature. This value defaults to Yes. Changes to this value
become effective with the next MultiVoice call.
The Max Jtr Buf Size parameter sets the maximum jitter buffer size for a call. When using
adaptive mode, the jitter buffer may increase to accommodate the entered number of audio
packets, based on the in-coming audio packet volume. You may enter a value between 1 and 19
(packets). This allows the MultiVoice Gateway to expand the length of a call’s jitter buffer to a
size proportionate to the selected number of audio packets. This value defaults to 19. Changes
to this value become effective with the next MultiVoice call.
The Initial Jtr Buf Size parameter sets the initial jitter buffer size for a call. When using
adaptive mode, the MultiVoice Gateway will open a jitter buffer to accommodate the entered
number of audio packets, based on the in-coming audio packet volume. In either adaptive or
fixed mode, the jitter buffer is built-up to Initial Jtr Buf Size at start-up. You may enter a value
between 1 and 19 (packets). This value defaults to 2. Changes to this value become effective
with the next MultiVoice call.
Note:
Under certain circumstances, the minimum jitter buffer size may be less then the initial
jitter buffer set through the MAX menu. The initial jitter buffer size and minimum jitter buffer
will be the same when the initial jitter buffer size configured is 1.
