@kensanata Whitelisting, with a possible distribution of (preferably locally/limited) vetted general numbers, would be preferred. Blacklisting does not scale, present systems prove this.
Vetted numbers would include local or regional service and government contacts, though those would then become attack / spoof targets for spammers. A well-known vetted number can reach many others. 1:1 whitelist personal contacts, not so much.
Generalistic and moderated instance.