I've had the same phone number for over 20 years now, since LNP became a thing I've moved it a couple of times to different providers. Most recently I've parked it with a non-local voip provider which gives me a great deal of flexibility. It sounds like under your proposal no one would receive my calls?
No matter what solution is proposed, there's always a subset of people who depend on that very behavior (see https://xkcd.com/1172/ ).
I think no-one receiving calls from parked non-local voip numbers would be an acceptable price to pay for the elimination of voip spam. You are free to disagree, tech is all about making compromises.
Incidentally, this quickly follows the path we took with SMTP. I can no longer telnet into a random SMTP server and dump incoming mail, which no doubt ruined the carefully honed scripts of many sysadmins.
