DTMF seems broken on T54W with newest firmware

[ProudCanadian]

I have just discovered that after upgrading my users T54W's to 96.86.0.5 DTMF seems to be broken.
PBX Version: 16.0.8.9
Attempted factory reset with no result
Tested from multiple handsets.
Can no longer sign into voicemail, hotdesks, or use Digital Receptionist menu's locally.

Had a user on the older firmware version test, and it seemed fine for her. (96.85.0.5).

The templates are the same between working and non-working handsets, the firmware version is the only difference I have found so far.

Rolling an impacted headset back to the previous firmware version resolved the issue, and upgrading it immediately returns.
3CX app and webclient are behaving normally.

 

[ProudCanadian]

Just confirmed on the handset that RFC2833 is selected

 

[Evolute IT]

How is the phone provisioned?

 

[ChrisC_3CX]

@ProudCanadian

Could you perhaps perform the following test so that we can look into this:

1. In the Management Console, go to "Dashboard >> Activity Log >> Settings" and enable Verbose Logging.

2. Start a packet capture on an affected IP Phone running firmware version 96.86.0.5 by accessing it's UI.

3. While the packet capture is running on the IP Phone, start a packet capture on the 3CX PBX from within "Dashboard >> Activity Log >> Select All Interfaces" from the drop-down and click on capture.

4. While both packet captures are running, dial the voicemail extension from the IP Phone and attempt to login to the extension's voicemail.

5. Wait a few seconds and then, stop and save the IP Phone packet capture. Also stop the 3CX PBX packet capture and click on "Generate Support Information package". An email will be will be sent to the administrator email of the 3CX PBX containing a link to the log/capture file. Please download it.

6. Downgrade the device to firmware version 96.85.0.5 and repeat the above procedure.

7. You will end up with 4 files, 2 IP Phone packet captures, one for each firmware version, and two Support Info file packs. Please send me all four files via a PM.

 

[ProudCanadian]

PM has been sent.

 

[ChrisC_3CX]

@ProudCanadian
Thanks for providing the files! I have gone over the packet captures and have found that the issue is occurring due to the fact that the SDP sent by the Yealink T54W also contains the OPUS codec. This of course applies for both firmware version but there are some SDP parameter differences which cause the issue when using the newer firmware version. This issue has been addressed in 3CX v18 but for the time being, on v16, you will have to remove the OPUS codec from the device.

Since we do not include OPUS in 3CX's default template it must've been added manually via the IP Phone or via a custom template so please either revert to using our default template or manually remove it from the IP Phone.

Let me know if you can indeed resolve the issue this way!

 

[ProudCanadian]

Very interesting!
I wondered if it was codec related, but after setting the phone to G.711 I still had the issue so I discounted that as the cause.
Is it just the mere presence of that codec being enabled that causes this issue, or something to do with the priority order (Or another setting elsewhere).

I only ask as I have Opus enabled as a low priority option on these phones so that they can natively use the codec when communicating with another model we support.

 

[ChrisC_3CX]

@ProudCanadian
For now you will actually have to remove the specific codec completely.

Depending on the changes to be made in 3CX's new release it may get added to the default template so that you can then configure it via 3CX without needing to worry if it will cause issues or not.