I am working on this with the OP.
the users hard phone can call anyone with no issues. ( so I don't think it is related to the user settings/ user rights)
when using the Webclient they can log in and dial some numbers, others just act like the system does not know the extension exists.
I am lacking in understanding what all webclient uses for resources, does it use onex-portal for backend?
I can search the directory in onex portal and the extension is in there.
Is there any WEBRTC config anywhere?
I am puzzeled for sure.