The FTC is very well aware of the problem: Just yesterday there was a long news item from a major news agency about the fact that the FTC can't do anything right now about spoofed calls, because of the limitation of their own technology. There is a growing movement by some Senators and Congressmen/women to have pressure put on telephone companies to protect their subscribers from this abuse. It's not easy to solve. But the authorities are aware of it, and while I too have been suffering from this same thing for months now, I am sure that in time they'll find a solution.
Constant calls from "Texas call" on caller ID 1-936-495-8708
10sec voice mail says "1000 dollars on grocery savings coupons...."
Haven't been able to catch a human yet to put us on do not call back list. ANNOYING!