Fusion PBX - one extension can't register any devices.

PGG

New Member
May 5, 2026
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Hi All,

I have a new FusionPBX installation running in a VM on Debian 13.

There are around 20 extensions configured, along with the same number of devices (Yealink SIP-T74U phones). Everything is working correctly except for one extension: 208.

This extension will not register any device. The same device can be assigned to a different extension and registers without any issues, but extension 208 will not register on any device. The phone simply shows “No Service”.

I have already tried the following:

  • Deleting and recreating the extension
  • Registering the device with a different extension number first, then changing it back to 208
  • Exporting/importing the extension configuration and modifying it manually
None of these steps helped.

No matter what I do, whenever I create extension 208, no device can register to it.

I had a similar issue with extension 202 a couple of weeks ago. At the time, I restored the VM from backup, which resolved it, but I did not have time to investigate the root cause. I would now like to understand what is causing this issue in case it happens again in the future.

Has anyone experienced something similar or knows what could be causing it?