Some days I get several of these on my home (VOIP) phone.
Fortunately, "nomorobo" handles most of them. One ring, and... poof! They're cut off, sometimes so quickly that the caller ID info can't even make it through.
The others go to the answering machine, because I generally do not answer phone calls in any case.
This is a problem that likely can't be solved by going after the robo-callers themselves.
The telephone companies themselves might be able to cut a lot of these calls. I imagine they have the technology to block a lot of the calls, but persuading them to do so may be problematic if they're making money by "passing" them (I don't know whether they do or not).
The best way to handle robocalls is by pro-actively taking charge of them "at the receiving end" -- your own phone.
If you have a VOIP service (phone signal comes in over internet), you can probably sign up for Nomorobo for free. It works very well.
Nomorobo also has a service for cell phones, but it's not free.
I have no need for it because the only cell phone I have (old flip-phone) is ALWAYS turned off. It can't ring.
I believe Nomorobo also offers "business solutions", but these are also pay-for services.
If you have a traditional landline-based phone that comes in over the copper wires, Nomorobo can't work. In that case, you have to research and buy one of the traditional hardware "call cutters" and wire it into your phone line.
Addendum to GTHawk:
You -can't- eliminate that first ring with Nomorobo -- because the caller ID info by which the system works comes in between the first and second rings.
Nomorobo works because when your phone rings, it also "rings" Nomorobo, which quickly compares the number against a database of "known bad numbers" and then immediately cuts the call -- hence, the first ring and then.... silence.
The only way to keep the phone from ringing at all MIGHT be to use some kind of hardware-based call cutting device...