I don't have a link handy but the last time I interacted with the user you're replying to, it was also about cell phones, and they were doing dumb things like swapping SIMs with their wife, thinking it would make things more private....somehow.

Guess what a SIM card does when it's put into a new phone? Includes the last IMSI it was installed into when it joins the carrier's network.

They're not very well educated on digital privacy and engaging in a lot of cargo-cult privacy stuff that is almost certainly making them stand out like a giant red thumb. Very few people do things like switch SIM cards on a regular basis, at least ones who aren't engaged in criminal enterprises.

Their behavior reminds me of a former partner's ex, who was [paranoid-delusional | obsessed with] cell phone tracking.

I really have no idea why they're so concerned about their cell phone carrier "knowing" their home address.