Someone in Oregon (or with Oregon numbers) has gotten a hold of people to contact. I just got a call from this number, and yesterday got a call from 503-201-2938 which blasted my ear with a boat horn, and then wanted me to book passage on a cruise line. Yeah, sorry, no, I'll use the money to see a doctor about this ringing in my ears.
I'm really amazed at the amount of people that say they call back. All you are doing by calling back is verifying that your phone number is valid. Once you do this, you definitely end up on a suckers list and you can now expect many more of these calls. These robo machines are just building a list of valid numbers to sell to other telemarketers. Must be some lonely people out there that call back numbers that they don't know or recognize, AND don't leave a message.
Best advice- don't answer numbers you don't know and don't call back if no message is left. If its legit AND important, they'll either call back AND/OR leave a message.