They spoof numbers. It almost always is a number from my state or the area code, very rarely do I get calls from out of state and they are all already labeled “spam risk/telemarketer” when they come in.

Also thank you for writing this comment, I was going to say ios had no way to block unknown numbers, but I searched to double check myself and they finally do have that option! It may have been around for quite awhile, I hadn’t checked for a long while.