I've tried going into my contacts app/profile/edit/typing in my mobile phone number. This still does not update it. I still get My phone number 'unknown'. (I have an Galaxy A5 phone).
I've seen this before.
It's usually connected to the sim card and when a person has ported from one mobile network to another or had a sim swap performed.
Also on some networks it seems to be a missing option. My friend uses a s7 on the UK Mobile Network Virgin Mobile and his days unknown too.
Perhaps check in your Samsung Account that the number is listed there.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help.
This happened in Note 5 and now my Note 8. It seems to be related to old numbers. I have had my mobile number for over 20 years and when the network operator created a new SIM with my number, my mobile number do not get written on the SIM. The solution is to take the new SIM and plug it into Apple Phone which is capable of writing your number into the SIM. Then you can use the SIM on your android phone and will now show your mobile number.
Hope this works for you because it worked for me. If you don't have a friend who has Apple Phone then go to the network operator which sells both Android and Apple Phone to have them help you.
Thanks for both your responses. I had just bought a new phone and had my data imported from one to the other, so now I know that's the problem. I'll find a friend with an iPhone. Thanks for the explanation and advice.