I have motto of zero tolerance for unsolicited calls from any organization at all. I choose who I want to do business with or give charity too or political party to support but NEVER due to a call into me.
When I id a scammer by picking up or looking up a missed call I make a contact on my mobile phone named "Scam Attempt1...2...3...4 whatever" and tie the number to it.
My phones caller ID lets me know at a glance to not pick up when they call again.