That makes a lot of sense because my number is definitely not listed anywhere and I did NOT put my number on the 'Do Not Call' list.

Just because your number isn't listed doesn't mean that you can't receive calls.  It also doesn't mean that your number was sold.  The use robodialers to call all numbers in a given area.  Also, since your number is not on the DNC, then they not only can legally call you, but you are also unable to file a complaint about it.

I didn't answer, they didn't leave message.

Home mortgage interest rate solicitation call.  They left a recorded message on my VM.  I blocked the number.

Lower interest rates. SCAM! added to block list