Random One-Way audio

[Tim Mrazek]

• 3CX Version, Enterprise Annual 16.0.3.676
• Server OS, Debian 9
• Is the 3CX Server Hosted and where? Local hosted
• IP Phone Make/Model/Firmware 3CX App
• Provisioning Method: Local / VPN / STUN / SBC Local
• Trunk Provider or Gateway Make/Model Twilio
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

This is a branching issue from another post
https://www.3cx.com/community/threa...adset-after-answering-call.69638/#post-309141

In that post we are having issues with calls continuing to ring in the call center agents headsets. When we are able to temporarily fix this issue, we start receiving one-way audio calls. It's not all calls, but about 10% of our queue calls have this issue. Now, I will be working with our providors tech support here in the next few days, but I'm wondering if there is anything I could look into until then. Currently, here is what we have noticed

• neither the caller nor the agent can hear each other. It's silence on the call.
• the recording picks up the callers voice. Not the agents.
• Affects random calls, not consistent. Callers will try us back and get through fine.
• Only seems to be affecting queue calls. Outbound and Direct to extension calls are fine.
• Some calls register as 'no audio recieved from callee' on our providor for some of these calls after their timeout is reached.

 

[Tim Mrazek]

So I'm getting more confused on this one. I have a trace from our provider for one of these calls. From the providor end we are not hearing anything from the agent, when the agent picks up the call from the queue. You can hear the caller still on the line, "Hello...", but no audio from our end. Even using audacity you an see that there is a definite cut in audio. no background noises.
On 3CX we see the same thing in the recordings, audio from the caller, but not the agent. On the agents side, there is only silence.

 

[Tim Mrazek]

Could this be a problem with the system connecting the call center agents? They seem to only happen on inbound call center calls, and when they are being answered. Not while holding. Is there a way to check that on server logs? I have a constant TCPDUMP running rotating pcap files and pull the logs out. I'm not seeing anything out of the ordinary.