iPhone does not ring from Unknown callers

My phone does not ring when the call is from an unknown number. I’ve searched the community and read the responses to similar queries posted earlier, but none of the answers work for me. The most common response has been that I need to turn off the silence calls from unknown callers function on the phone in settings. However, I have checked that many times and this facility in my phone is not turned on. I’ve even turned it on and then off again and restarted my phone, it still is turned off but I still cannot receive calls from unknown calls. Any better solutions, please?