Unable to register FXS port when FXO configured on Grandstream HT813


#1

I’ve configured a HT813 with FreePBX using this guide on the this website (sorry it won’t let me add a link as a new user) but is is the plucero site /configure-grandstream-ht813-with-freepbx
Having set up an incoming and outgoing route, it works fine.
However when I try and register the FXO as an extensions, it simply will not register.
I had thought it might be an issue with the HT813, so I tried registering the FXO to a cloud provider and that happily-exists with the FXO.
I then thought perhaps FreePBX, cannot distinguish what port (FXO / FXS) was communicating, but having checked the port numbers (FXO: 5060 and FXO:5062) that did not appear to be the issue.

Finally I changed the FXO trunk from pjsip to sip and now the FXO and FXS now work happily together
If I change the trunk back to pjsip, they still work, until I reboot the HT813.

Any ideas why?