As a rule I never answer strange area codes at odd hours, 99% of the time they don't leave a message confirming that they were not someone important. I hate spam on my cell and this was apparently just that, thanks for the warnings and info here. I always google the number during or afterwards to confirm any lingering doubts that I missed an important call.
If your cell phone is running iOS 8, just select "block this caller" from the choices at Phone>Recents>(i), where "(i)" is the right-margin icon opposite the number.