I was getting 5-10 spam calls a day, even though I've signed up to the no call list multiple times. I turned on that setting and it helped, but I started missing calls from the school, from doctors, etc... And you'd think they'd leave a message but they don't.
Recently I've started to be able to recognize spam calls by a small tone that I hear after I pick up. If I hear that I hang up immediately.
Spoofing a number should be illegal, and I believe there was a law put into effect in the past few years that did make it illegal. But there apparently isn't any teeth to the law.