I added the number to my "rejected calls" list, and when it called again, I tried calling back and got a recorded message from Verizon Wireless saying this number has been changed, disconnected or is no longer in service. WTF? I don't know what I signed up for that sold my number to these spammers, but I get calls on a daily basis from random numbers that don't leave messages. Most of the time when I Google the number, I read that they're telling people they've won some sort of sweepstakes but want a credit card number. Freaks.
I read some of the comments, and I guarantee this is NOT State Farm!
I never answer unfamiliar numbers. Instead I look them up on MyCallBot.com which shows the reports on several different sites like this. I then save under a name like "Scammers" and then block the number.