Showing results for 
Search instead for 
Did you mean: 

Silence Suppression (comfort noise) on non-PSTN call


Third-party call centre application is connected to CUCM7.1.5 via a SIP trunk.  Call centre agents have nailed-up calls to CUCM - incoming calls are connected by the call centre application to the agents (all 7942 phones).  When the agent is not in a customer call, because there is a silent call active to the call centre application, they receive comfort noise which they find irritating.  How can I disable comfort noise, either on a per-phone basis or globally?  All I can find on this is references to PSTN calls and configuring comfort noise on voice ports; that doesn't apply in this case as no PSTN calls are active when the comfort noise is received.

4 Replies 4

James Hawkins

Hi Pete,

Hope you are well.

VAD can be enabled/disabled for SIP trunks within the SIP Profile applied to the trunk

Device > Device Settings > SIP Profile

Select the profile applied to your trunk, scroll to the bottom and see if the "Enable VAD" button is ticked.

VAD can be enabled/disabled for phones using the CallManager Clusterwide Parameter (Service) Service Parameter Silence Suppression

Both these are set to off by default though so unlikely to solve your issue.

Daniel Gagne

Hello James,


I know that this is very hold stuff but anyway.


We are facing the same issue here with a new implepemtation of a third party Contact center.


When there is no customer at the other end, the Concact center platform sends a re-invite with and sdp containing

 c= IN IP4  which instruct CUBE to break the RTP stream to the phone. Then the phone sees no RTP packet comming in from CUBE, it then starts to conceal them with white noise.


Did you manage to  fix this somehow?



Did you try to disable VAD on Cube ??



VAD is not enabled on CUBE.





Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers