Telemarketers have ruined the phone network for me. I haven't answered an unknown call for the past 10 years, which sometimes means I miss important ones. 99.9% of all calls are an attempt to get money, and the 0.1% that's a dentist appointment, a friend that changed numbers or whatever become collateral damage.
A ban is the right idea but I wonder how they can handle it, logistically. I think there needs to be a technical solution.
A national "whitelist", where hospitals, doctors, utility companies and such can register to get their numbers whitelisted perhaps, combined with a setting on phones that block any non-whitelist number.
Each country could maintain their own whitelists, and corrupt nations selling whitelist status to scammers would get blocked in any other country at least.
I'm in North America and most of the calls I get are using local numbers, often spoofed from (I suspect) South and South East Asia. Good luck enforcing Canadian or American law in literal slave camps on the China-Myanmar border.
That new law is not going to change the number of spam calls most people will get, as they're not from properly registered businesses.
I haven't seen one in decades, and even then it was usually some pamphlets or books to support a cause or the other.
On the phone (Italy), OTOH, I used to get daily scam call to buy "Amazon stocks" or change utility providers or install water filters. That seems to have massively faded out due to new regulations tho.
Scams have been heavily hit in January when the French regulator mandated the telcos to implement a complete block of spoofed phone numbers (it's not an actual hard block, but unauthenticated calls will be market as "private number" which are ignored by most people already).
There will always be scammers who register an actual phone number to run their scams, but this rule will at least stop the constant phone harassment that made everyone unplug their landline phone.