A phone company I was a customer of used my phone number as the customer Id. Which doesn't work great for people, or companies, with more than one phone number.

A phone company I was a customer of used my phone number as the customer Id. Which doesn't work great for people, or companies, with more than one phone number. They could also only provision one SIM per phone number, and not use a phone number tied to a SIM as a virtual number, and also the primary (customer Id) phone number had to be tied to a SIM. I ported my phone number away from them, but what if I ever go back? Will my old data be there? Including my old address? What if my phone number gets recycled, and some-one else gets that phone number and ports it to them? So many questions.