There was a story on different news sites that stated the chairman of the FCC has said telephone companies must use call authentication before the end of 2019
now it was originally brought up due to cellular spoofed spammer and scammers calling with a false number. Or numbers not owned by the spammer.
you see the phone company makes money on selling phone services to scammers, and it makes money selling its customers blocking services. So there is no real incentive to stop the calls from being sent to you. The phone company will say there is nothing they can do. Remember they are the phone company. There is nothing they want to do.
unless the government inacts policy to say fine Verizon and other phone companies hundreds, thousands, millions of dollars until they actually do something, you will have to combat this problem with what is available.