Finally picked up phone after seeing this # with "IMS" in caller ID window last 2 days. I said hello then several seconds later a man with a very thick accent said something about Facebook then hung up. Tired of my phone being tied up with this crap. I am on the DNC list and it means nothing.
If you are getting called on a mobile phone, you can easily add the number to your "blocked callers" list. Google how to do that if you're not sure, for your particular phone.