3CX Upgrade to 15.5.15502.6 bricks Yealink T42G's

[stuffuk1]

Automatic upgrade to 15.5.15502.6

All of our Yealink T42G ceased to register.
They appeared in Phones but would not assign to an extension, even though you go through the motions.
Reset Phones, no longer getting ip through DHCP
Upgraded firmware to 28.81.0.110 - higher firmware doesn't work - Yealink now on 29.83.0.50
(manually set ip and upgrade through web interface)
Reset and IP obtained through DHCP
Phones did not autoprovision
Had to set provision url in phone web interface and disable trusted certificates
Phone then registered, but it is still showing

Yealink

SIP-T42G

Not Supported 29.81.0.110

Seems to work, however
We lost our phone system for over 24 hours, whilst troubleshooting.

now all calls drop after approximately 30 seconds.

 

[JohnS_3CX]

Hi @stuffuk1

The correct T42G firmware for your current PBX is 29.83.0.55 and will be downloaded by your management console if you go to the updates section. If the phones are registered now, you should be able to push this firmware to them via the management console (Phones Section).

• Please ensure you are using updated 3CX templates (not custom templates)
• Please factory-reset the phone after the firmware upgrade to V 29.83.0.55
• Delete a phone from its extension, now reboot the phone and allow it to appear, try to assign it now

You can try on one phone and if all is good, proceed with the rest too. Ensure your network is healthy and that DHCP leases are available. Ensure no DHCP Options are active (like Option 66 that may interfere with provisioning)