When I’m called, people do not hear me while I do hear them. When calling internally I have a similar problem, so I guess this can’t be firewall related? Just to be sure I have checked my firewall settings and the netwerk settings in FreePBX, all seems correct.
I have no idea what just happened. I reverted an old snapshot I had to check and see if I might have messed up the system somewhere… this only made my problems worse, so I re-reverted to the snapshot from before reverting (still with me?) and tested again. All problems seem to be solved now.