Specifications

Chapter 7 - Port Configuration Administration Manual (SIP/MGCP Version)
AT-VP504E FXS 56
higher. If the network to which the AT-VP504E FXS is
connected suffers from a low level of congestion, the level of
jitter buffer protection should be lower.
3. Define the port1DspVoiceActivityDetection variable.
The Voice Activity Detection (VAD) enables the
AT-VP504E FXS to detect when the user talks, thus avoiding
to send silent RTP packets. This saves on network
resources. However, the VAD may affect packets that are not
really silent (for instance, cut sounds that are too low). The
VAD can thus lightly affect the voice quality.
The difference between transparent and conservative is how
"aggressive" the algorithm will consider something as an
inactive voice and how "fast" it will stop the voice stream. A
setting of conservative is a little bit more agressive compared
to a setting of transparent to react to silence.
The default value is 2 = Conservative.
Table 23: Jitter Buffer Variables
Variable Definition
port1DspMaxJitterBufferLen Maximum jitter buffer length in ms.
Default Value: 300
port1DspTargetJitterBufferLen Target jitter buffer length in ms.
Default Value: 150
port1DspAdaptativityJitterBuffer Adaptative Jitter Buffer.
• 0 =OFF
•1 =ON
Table 24: Voice Activity Detection Variables
Variable Description
0 = Off VAD is not used.
1 = Transparent Silences are least detected, affects the voice
quality the least.
2 = Conservative Silence detection is medium, voice quality
affected is medium.