Solved Yealink T20P - STUN autoprovisioning not working

[carmen.leroux]

3CXon Debian (cloud hosted)
3CX Version number: 16.0.9
Provisioning Method: STUN

All Firewall ports are open (including STUN ports)

We have a T29G, a T21P_E2 and some W60B/W52P hardware that works perfectly, however the T20P devices does not register over STUN.

I have tried all versions of firmware available on the Yealink site as well as the suggested firmware version on 3CX website.

Also tried disabling the trusted certificates under Security on the Yealink.

 

[carmen.leroux]

To add, when I enter the details on the phone manually, the phone registers, but we have too many devices to make it work this way.

 

[Saqqara]

You need to disable



Under Security - Anti-Hacking

Check limitations - https://www.3cx.com/sip-phones/yealink-t20p-t22p-t26p-t28p/

 

[carmen.leroux]

Hi @Saqqara

Thank you for the quick response. I disabled the setting and now I am sorted.

Enable PCI compliance SSL/SecureSIP Transport and Ciphers (This will leave only TLSv1.2 enabled and may prevent old legacy phones and old 3CX Apps to connect remotely to your system)

 

[JohnS_3CX]

You can re-enable the above setting now that the device loaded its config, so you can regain higher security.

It won't be able to reprovision, but it will work so long as you don't make any changes to the extension credentials.

You can do it temporarily again later if you need to reprovision them.

Consider replacing the T20P with a more modern device when possible.