I just got introduced to this "Falsehoods Programmers Believe About Phone Numbers" page.
https://github.com/google/libphonenumber/blob/master/FALSEHOODS.md
.. which reminds me of a previous good one it's probably referencing: "Falsehoods Programmers Believe About Names":
https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/
...both excellent documents.