Since a few months, I am struggling to get X4Us to work with VitalPBX.
They ring and have audio when emitting calls but when receiving, they instantly place the call in missed calls and don’t ring, other features like transfers and call forwarding are causing issues.
I updated, downgraded firmwares, resetted the phones but it doesn’t seem to change anything.
Other Fanvil phones like the X210 or X6U are working as intended.
We use a lot of X4U both v1 and v2 without any issues. Are your phones properly registered to the server? Grab some logs as well via sngrep in the cli to see if the call process and whats going on, so we can help better.
Your issue does look like a codec issue.488 errors tells you their is no media compatibility between the calling and receiving endpoint, so you wont get a ring at all.
Check the codec setup on both server and the phones.