What is "Unknown Caller" on iPhone?

I am experiencing same problem on my new iPhone 13 pro I bought yesterday. All incoming calls are unknown,please help

That's because whoever that caller is has their caller ID information blocked.

That, or there is something wrong with caller ID information being sent by your cellular carrier.

Contact your carrier if this is happening for all incoming calls. Caller ID is a carrier feature.

I got several Unknown Caller calls and I bet my brand new iphone was randomly given the tel no. of someone who had recenly relinquished it and had not told all their contacts. If the message are inappropriate you can mark them as Junk and report to Apple.

Well, when I got my sim card I asked if I got to choose from several available numbers and I was told 'No', they're randomly generated and you get what you get. Although, especially if you receive inappropriate messages, I would hope your carrier would allow you to get a new number. Good luck!

I really have tried everything deemed useful to resolving this matter but it still persists . Could it be my service provider?