Comfort Noise local to phone

[Evan_Yealink]

Dear Customer,

This is Evan from Yealink Support Team, I'm glad to answer this question for you!

For example, A is talking with B.
A: Enables the CNG, CNG=1
If A mutes the call, A will send CN packets to B. When B receiving CN packets, it will
generate comfortable noise.

For more information about CNG:
Comfort Noise Generation (CNG) is used to generate background noise for voice communications during periods of silence in a conversation. It is a part of the silence suppression or VAD handling for VoIP technology. CNG, in conjunction with VAD algorithms, quickly responds when periods of silence occur and inserts artificial noise until voice activity resumes. The insertion of artificial noise gives the illusion of a constant transmission stream, so that background sound is consistent throughout the call and the listener does not think the line has released. The purpose of VAD and CNG is to maintain an acceptable perceived QoS while simultaneously keeping transmission costs and bandwidth usage as low as possible.

Best Regards,
Evan You