Phone connected via bluetooth to car audio system: media audio works, calls don't
I removed the phone/device again from the bluetooth car audio system and linked it again via bluetooth, after changing the phone bluetooth name.
It did not work.

I then turned off and on the phone.

Now it seems to be working, not sure how/why though!

UPDATE: it happened again, and only a complete power off and then power on of the phone solved the issue.