Got a call from this phone # yesterday. It is a scam. The caller pretends to be from the US Treasury. They threaten a lawsuit if not called back, say that the person they are calling will be forced to appear before a magistrate or grand jury on a federal offense charge. It is a scam.
I'm not sure blocking will do you any good. This is the second time I've received that same message from different phone numbers, apparently coming from completely different states (the first caller ID said originated from McKinney TX, and this one from Middletown DE).