One of the sad things that broke when number porting became a thing was there was no definitive answer of which phones were cell phones and which were land lines. This was unfortunate because if you were called on your cell phone for a long time it would cost you money, and if someone called in an unsolicited way, you had 'damages' that you could sue for on the theory that they knew it was a cell phone and they called it anyway. Now however they have reasonable doubt and so they call whenever.

I wrote the FCC once and suggested that a good use of some of those fees I pay would be to create a service that would instantly back trace and log a complaint on a number using telemetry from inside the phone system. That combined with a federal criminal statute which allowed for jail time for masking the origin of a phone call and I think you could make to fairly costly for the owners and enablers of this stuff.