Received a call to our land line today (18 Apr 2017) from this number at 9:56 am (Central Time). Caller ID: Unavailable. Didn't answer. No message left.
If you have an iPhone, you can click on the lower case i in a circle next to the call in your Recents page. Then, scroll down the page and there is a Block this Caller for you to click on. I have been using this for 2 years. Those calls go right into another folder (which can be found under voicemail) if you ever want to see them again.