I called the number back, as I had missed their original call.
The response was: "Hi, this is Lisa, at your rewards redemption center. You recently visited one of our affiliate websites, so we have a $100 rewards certificate, redeemable at stores such as WalMart, Best Buy, etc."
At his point, I hung up and blocked this number on my iPhone. I'd like to know how they got my cell phone number from a drive-by on their website!