Tangential: please do not use a phone number as a PK. Aside from the nightmare of normalizing them, there is zero guarantee that someone will keep the same number.
Also fun fact, people mistype and mistranscribe data. Some people even... put down fake phone numbers because they don't want to be tracked!
I would think in a world where we constantly get spam calls and texts that people would understand that a phone number is not a good PKI. I mean we literally don't answer calls from unknown numbers because of this. How is it that we can only look at these things in one direction but not the other?