Some calls (Queue) are lost when phone is answered (3cx v15 + Yealink T48G)

[Florian Berger]

Hello everybody!

I do experience a very odd problem with 3cx v15.

Setup:

We have the pbx set up for queues, and clients (Yealink T48G Phones) register and unregister from queues in order to receive or not receive calls from that particular queue.

Sometimes when a call is answered, the caller is lost immediately, and one can hear a "busy tone".

It does not happen everytime, just on a few. I could not find any error messages on the 3cx admin console.

Another thing that happens from time to time, is that phones eventually stop to render the call tone (the sound you hear when you call someone, and it is ringing). There is just silence, and suddenly the the other end answers. That problem is fixed temporarily by rebooting the phone.

3cx is set up following best practices, phones run in a dedicated VLAN, and the WAN site of PBX is set up in accordance with 3cx guidelines for our firewall (Sonicwall). Firewall-Test passed fine.

Phones and PBX are both on latest Firmware/Software.

Any hint or idea on that problem is very appreciated!

/Florian

 

[GiannosC_3CX]

Dear Florian,

Another thing that happens from time to time, is that phones eventually stop to render the call tone (the sound you hear when you call someone, and it is ringing). There is just silence, and suddenly the the other end answers. That problem is fixed temporarily by rebooting the phone.

Ensure that the firmware of your IP Phones is supported by 3CX System and has the default template.

Sometimes when a call is answered, the caller is lost immediately, and one can hear a "busy tone".

Please check under extension configuration on options tab the Support Re-Invites and Support 'Replaces' header if those settings are enabled.
Also you can enable on the Activity Logs, Settings the verbose option to find more information about call termination.
Please find this link to help you how to manage the above situation http://www.3cx.com/blog/docs/3cx-server-activity-log/

 

[Florian Berger]

Ensure that the firmware of your IP Phones is supported by 3CX System and has the default template.

/

I'm using the latest firmware, and I'm using the default template for one exception: It is an altered version of the default template which sets VLAN to on, and sets approbate VLAN ID as well.

Please check under extension configuration on options tab the Support Re-Invites and Support 'Replaces' header if those settings are enabled.
Also you can enable on the Activity Logs, Settings the verbose option to find more information about call termination.
Please find this link to help you how to manage the above situation http://www.3cx.com/blog/docs/3cx-server-activity-log/

I'll try to find out more by enabling verbose-mode.

In extension configuration, shall I set "PBX delivers audio" to true for T48g?