I wonder if an adnauseam approach could help. Instead of the customer relying on the carrier or manually blocking spam numbers, if everyone picked up every spam call, goes through the automated system to reach a person, says “hello?”, then mutes the mic and lets the human stick around until they hang up.

Sure, they have robocallers that can hit 50,000 numbers a minute, but what happens when every single number answers and gets routed to the humans?