If someone calls me, I can take the call normally. If I dial the number from the infotainment of my car, the call will take place normally.

If I start the call from my phone, the following happens:
It will create the connection, you hear one tone, then the display of the infotainment system says "being terminated" and the call goes to my phone. Here I need to deactivate bluetooth to take the call, otherwise I cannot talk or listen on either phone or infotainment.

I think this happened after Android 13 update, but maybe I fiddled in some settings as well.

I am desperate. Btw, I can use the infotainment calls from an Android phone. So it is more unlikely that the infotainment is at fault.

What never worked is joining Teams calls, I never figured that one out as well.