GS290 - I can't hear the call


I’m quite new here in the community and own a GS290 from the /e/ foundation shop since Thursday.
I have some issue with the normal phone call. Maybe somebody could help me with that…

My situation:
When I’m calling with the headset or with the speaker on, everything is alright. But when I want to call somebody with the phone nearby my ear without headset, I don’t hear anything.
The same with music. With headset I can hear music. Without headset I don’t hear anything.

Is there any configuration I messed up or didn’t see or anything like this? Is there anybody with the same problem?

Thanks for your support.