When I call this number back from an unlisted blocked number, it sounds like a real person actually picks up... but as you listen to the voice, you realize it's someone using a computer with pre-recorded phrases, as they repeated "Hello" a few times and then had the voice thank me for calling today and that they appreciated my time (despite the fact that I said nothing on the phone). Clearly a spam, and now they're permanently blocked.
Phone rang around 6:00 PM this evening. Didn't recognize the number, so I let it ring. No message left on the answering machine. Caller ID just said "Massachusetts", which is quite obvious in that 617 is the Boston area code.