Silence Suppression And Comfort Noise Generation - Cisco SPA2102-AN - Single Port Router Administration Manual

Configuring Voice Services

Silence Suppression and Comfort Noise Generation

Silence Suppression and Comfort Noise Generation
Cisco Small Business ATA Administration Guide
Voice Activity Detection (VAD) with Silence Suppression is a means of increasing
the number of calls supported by the network by reducing the required bandwidth
for a single call. VAD uses a sophisticated algorithm to distinguish between
speech and non-speech signals. Based on the current and past statistics, the VAD
algorithm decides whether or not speech is present. If the VAD algorithm decides
speech is not present, the silence suppression and comfort noise generation is
activated. This is accomplished by removing and not transmitting the natural
silence that occurs in normal two-way connection. The IP bandwidth is used only
when someone is speaking. During the silent periods of a telephone call, additional
bandwidth is available for other voice calls or data traffic because the silence
packets are not being transmitted across the network.
Comfort Noise Generation provides artificially-generated background white noise
(sounds), designed to reassure callers that their calls are still connected during
silent periods. If Comfort Noise Generation is not used, the caller may think the call
has been disconnected because of the "dead silence" periods created by the VAD
and Silence Suppression feature.
Silence suppression is configured in the Line and PSTN Line tabs. See
Routing Field Reference," on page 105.
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