Unable to make or take calls

FP4 with stock Android, fully updated. The SIM card works in other phones.

  • When I try to call a number, nothing happens. The phone being called does not react.
  • When someone calls my FP4 it also does not react. Eventually the call goes to the answering service.
  • SMS/texts and data works.
  • Loudspeakers work.
  • Bluetooth works.

So, it’s troubleshooting time. I need some help on what I can do to find out why calls have stopped working.

Don’t be shy about being technical. I am a software engineer and I work in a company where we develop fancy electronic devices for customers, so I also have access to experienced HW engineers and a decent electronics lab.

How old is your SIM card? Old SIM cards can give problems in a Fairphone, whilst working in a phone from another brand.

it’s 2-3 years old or so. I should add that this problem only started a couple of months ago. I don’t make that many calls so I am a bit unsure of the exact time it started.