Comfort Noise - Nortel BCM50 Configuration Manual

When several calls are made over a full-duplex link, all calls share the same transmit path and they
share the same receive path. Since the calls are independent, the peak bandwidth must account for
the possibility that all speakers at one end of the link may talk at the same time. Therefore, the
peak bandwidth for n calls is n * the full transmission rate. The following figure shows the peak
bandwidth requirements for two calls on a full-duplex link with silence suppression. Note that the
peak bandwidth is twice the full transmission rate, even though the average bandwidth is
considerably less.
The spare bandwidth made available by silence suppression is available for lower priority data
applications that can tolerate increased delay and jitter.
Figure 151 Two calls on a full-duplex link with silence suppression
Conversation
Tx
Rx
Hola Isabella
Tx
Rx
Fred here.
Conversation
Bandwidth used
Peak channel bandwidth is n * average
bandwidth per call

Comfort noise

To provide a more natural sound during periods of silence, comfort noise is added at the
destination gateway when silence suppression is active. The source gateway sends information
packets to the destination gateway informing it that silence suppression is active and describing
what background comfort noise to insert. The source gateway only sends the information packets
when it detects a significant change in background noise.
Buenos noches Juan
Hello Fred. This is Susan.
Appendix B Silence suppression
Muy bien, y tu?
Com o esta?
Do you have a minute?
Hi!
Independent Tx and Rx bandwidth
not shared by half-duplex calls.
Networking Configuration Guide
Sure!
Channel/Link max
Time
Channel/Link max
Time
533