I have not signed up with AARP, and I've been getting numerous calls per week from different unknown phone numbers and from insurance companies for a couple of months, as well as a blizzard of envelopes in the mail. It's because I'll be 65 in a few months, and they know how to get addresses and phone numbers and match them with birth dates. Nothing to do with AARP except it's the same target audience.
Typical robo-dial/scammer call pattern - phone rings, caller ID shows "Ranger TX", do not recognize, do not answer, rolls over to voice mail, no message left = BLOCKED !!!!!