The authorities already don’t have much leverage over “domestic” spam call centers that are actually located overseas but somehow always manage to acquire domestic numbers to call from.

A couple of years ago Australia had a big reform of the laws where sms providers / voip companies had to actually verify their users owned the numbers they send from. Anecdotally before then I was getting a scam text message every day, now I haven’t had one in years.

Phone numbers in Australia are also all tied to ID. If there is a will to fix the system, it can be done.

Good now we only need to get 100% of sovereign nations and rogue states to adopt uniform global treaties