On the plus side, patlive.com charges $1/minute as their cheapest plan. Robodialing them back, with a sufficiently clever script, would be costly for "Will".
If it was a reloadable card, you can still figure it out with more effort. You threaten to sue them into oblivion as facilitating criminal actions, and you get them to get you on a real phone number with the scammer, and then you track them down that way. You just have to try harder.
A reporter could pursue this by getting a job with that firm and tracking backwards.
We may get there. It'll probably take the form of deploying STIR/SHAKEN on the US side and making engagement with anyone who doesn't implement it purely opt-in.
I'm not a facebook fan, but I wouldn't be entirely against "Facebook Phone" (as in, a drop-in replacement for dialing numbers now that works as an appliance, not a shitty "add-on" for fb messenger) if they moved in to disrupt the industry. Of course privacy-be-damned at that point, but it's the lesser of two evils IMO.
You realize that the vast majority of "robo-calls" are originated from Class 2 Interconnectwd VoIP providers, aka SIP companies like Twilio, Flowroute, SIPSTATION, SIP.US, voip.ms, and the like.
VoIP is the problem, because you can put an extraordinary amount of of volume down a very narrow pipe, with almost zero verification or validation on the technical if you are an active customer with a SIP provider. Becoming an active customer is not very difficult, either.
I suggested FB only because it has fairly strong identity verification and (arguably) spam control. Plus they have the infrastructure to handle the bandwidth of a massive VoIP network.