Everybody had to go to a store and have their ID read by the system, and if they didn't, the phone number would be shut down.
Unsure how that worked for MVNOs though.
Now I live in the USA and am well-familiar with the spam calls. I wonder if this new rule will reduce/prevent them. I think in general the ability to spoof numbers should be banned / controlled. Someone from India should not be allowed to call me with a caller ID from Mayo Clinic.