I don't mean this maliciously but unless I've misread your comment this is a lot of text that boils down to "sometimes you'll be unreachable". Some of the reaso

I don't mean this maliciously but unless I've misread your comment this is a lot of text that boils down to "sometimes you'll be unreachable". Some of the reasons you list: - family members getting new phones - missed connections + job offers - teenage child being angry with you - emergencies Two responses: 1. The cellular phone has existed only for so long, and people found a way to exist before it. I'm not going to belabor the point since it's not very deep but this concept that you need to be reachable 99% of the time in 99% of the cases is wrong -- the cases where you actually absoutely need to be reached is often <1% of the time. 2. The problem is identity here -- it's not that you don't want certain numbers calling you, it's that you don't want certain numbers calling you. This could be solved by creating a system that links identities to numbers, though it's exceedingly optimistic notion that we'd get everyone to agree on the same system. In all the situations when you give someone your phone number or they give you theirs, you're agreeing to talk to each other. If you instead exchanged some sort of identity (let's say GPG key), the problem no longer is "how can I call a number they should be at", it's "how do I find how to contact this person with this identity". The latter question can be solved much more robustly. I've thought about something like this -- creating just a online store of just identities that you can freely create and discard, boiling down to GPG key. Having such a shared resource would mean that chat apps, telco providers, and various other usecases could just use GPG (in this example) to look up the right contact method... Attempting to create a widely used standard is basically suicide though so maybe this idea has no legs. In this imaginary scenario you have a whitelist that works the way you want -- people you want to contact you can, and you can have very limited overrides like a shared identity/utility key for hospitals/government/etc. [EDIT] - I also wanted to add -- again, I do think that this would have bad effects on "free and open communication", but I'm not sure it might actually be bad for society -- maybe free-and-open-communication by default for some mediums isn't good. I don't think closing down this loophole for phone numbers is going to squelch productive protests (one of the phenomenons I personally think we'd want to protect), but maybe I'm wrong.