You can use Voice Activity Detection (VAD) or silence suppression to save bandwidth. During a conversation, because only one party is speaking at a time, more than 40% of the transmission is silence. VAD in Avaya IP telephones monitor the locally produced voice signal for voice activity. When there is no voice activity for a configured period of time, the network does not transmit any packets, resulting in bandwidth savings.

When you enable silence suppression, the network at the remote end is made to generate comfort noise that fills the artificial silence in a transmission when no voice is present during a conversation. The trade-off with silence suppression lies with the silence detection algorithm. If the algorithm is too aggressive, the beginnings and ends of words can be clipped. If not aggressive enough, no bandwidth is saved.

Silence suppression is built into G.729B and can be enabled for other codecs from within Communication Manager. Because of voice quality concerns with respect to clipping, silence suppression is disabled by default with the exception of G.729B.

The following Avaya products use silence suppression to preserve bandwidth:

For procedures to administer QoS parameters, see Administering Network Connectivity on Avaya Aura® Communication Manager.