I can make or receive call using the sim card on slot #1 because the microphone either don’t work at all (people can’t hear me) or very poorly with a lot of noise.
Calls on sim in slot #2n work fine.
I switched sim cards and the problem is the same (unrelated to sim cards but to sim slots).
I did the tests as described here:
The primary microphone has A LOT of noise on the test.
The secondary sounds fine (I’m not sure really because it’s echoing but I’m assuming that how this secondary microphone works - I did hold the phone upside down as instructed for this test).
Thanks for your help