Losing listening capability

[swhite]

Hello,

Having a problem with my 3CX deployment and listen in capability. We're running 3CX Pro, Version 16.0.910 with 24 concurrent channels. It's on-premise, Debian based deployment. We have 7 Yealink T21P E2 SIP phones in the same office as extensions. 3 extensions are configured with manager permissions with full listening rights. We use the Windows app to monitor a Sales queue, with the CTI setting for listening. When we click Listen on the Windows App, most of the time it works. The desk phone for that manager's extension will ring and they can listen in to the call using their wireless headset or phone. However sometimes the functionality stops working. Clicking Listen in the Windows App will not ring the desk phone, and nothing will happen. Restarting the Windows App seems to work most of the time, and the functionality will return. There's no way to tell when it will work or not.

Looking for any advise in isolating the cause of this behavior.

Thanks!

 

[cobaltit]

I believe there is a bug|feature|defect where you can only perform one operation on a call. So if you listen-in you can't change it to whisper or full on barge or something to that effect. Not exactly the behavior you are describing but it may be related. I don't recall the exact thread where this was covered but if I come across it I'll let you know.

 

[swhite]

Thanks for the reply. I have been tracking it further and we're not running into that bug where it can be only listened to once, this appears different.

We're using the Windows Desktop App in CTI mode, clicking LISTEN on the app will make that manager's phone ring, and sometimes they can listen in with their headset. When it doesn't work, the phone will ring once briefly, the manager will be marked as unavailable, unable to listen and unable to take further calls until the call they tried to listen to drops off. In my pcap I see audio was established during the request, but none was present to the listener.

SIP ALG is disabled on the router, we tried setting PBX handles audio on the manager extension. Would it be recommended to let PBX try to handle audio on all extensions for this behavior? I can post a pcap if someone wants to look at that too, the attach files won't let me do pcap natively.

 

[swhite]

We've tried additional phones and experience the same issue on them. The listening in functionality appears severely broken, this is becoming a deal breaker for using this PBX and we are researching alternatives at this time.

 

[swhite]

I setup a on-net tablet to use the webclient as a listen-in device, we'll see how that goes. It failed entirely unless I used the local NAT address for the webclient.

On some calls I'm getting "Error: This operation cannot be performed at this time." when clicking Listen on the webclient (chrome browser on Android), but a lot I can listen to just fine. Anyone run into this error?