Confbridge audio mixing with other bridges

Using Asterisk 16.6.2

I’m receiving reports that users joined into 1 conference bridge are being mixed with audio from other conference bridges on the same server. The marked user from Conference A is being heard by Conferences A and B, but is not hearing anything from Conference B. I haven’t found this to be a known issue - can anyone provide insight into why this might happen?

The only times I’ve seen this come up have been a result of a non-ConfBridge issue. Being heard due to being in the same physical area, or someone doing a transfer in some way, or a three way call on a phone.

TY for the quick response!

That’s interesting. Since the default menu for an admin user has the option for *2, is it possible that a transfer is being initiated instead of the menu being invoked?

That… depends. If there is a Local channel in the middle that had at one side a Dial() with the DTMF feature turned on, then yes, it’s possible. DTMF features like blind transfer, attended, etc only work when Dial() is in use.

Dial() is not being invoked here at all, an IVR from an inbound channel is dumping the call straight into ConfBridge().

Since it’s a fluky thing, I want to wait till I have another case of this to pursue further, but I’m not sure what logging might be useful here. How does ConfBridge mix audio… Is it with MixMonitor?

It does not. It has a process that runs every 20ms that takes audio from each participant channel in the bridge, mixes it, then sends it to each channel while removing that channels audio.

A channel also can’t be in multiple conference bridges at once, stuff would implode if it did.