Moreover, if you can come up with an attack that’s a workplace safety violation against the call center, they’ll have to come up with some kind of countermeasur

Moreover, if you can come up with an attack that’s a workplace safety violation against the call center, they’ll have to come up with some kind of countermeasures to protect their workers’ ears if they don’t want to get sued and shut down. Do this enough times and the costs to them may exceed the benefits. (Mind you, this only applies to call centers operated at the behest — employment or contractual — of companies that are headquartered in places that actually have workplace safety regulations. Won’t protect you from scammers operating out of developing nations. But it might cause a technological differentiation between scammer tech and other call-center tech; at which point it would become possible to detect scam calls just by the “sound” of them, and have middleboxes drop them.)