I have had to intentionally block my health insurer, Matrix Medical, my HAP provider.
"Hi, this is Jackie, with an important message from your health provider. You are eligible for a free, in-home health check......" Blah blah.

The problem is, we had that checkup 2 weeks prior to the beginning of those calls.

I have at least 5 numbers blocked for those calls alone. Maybe 7. The numbers are all legit. One was a cell in the UP of Michigan. It has turned into a game for me.

I keep my contact list current. Many hundreds of people/companies that I have known. If an unknown number calls, I push it to voice mail. If a blocked number calls, it goes directly to voice mail.
I listen to all the messages, and either block the number, or call back.

I've been doing this for many years, and get way less spam calls than most people I know.