This number (unless it's a spoof) just called and a recorded female voice comes on saying "Please hold for a very important call," then goes right into "hold" music.  I muted long enough to write down the number.  I suspect this may be one of those "you owe us money so pay up right away or we'll put you in jail" calls or some BS like that, since legitimate companies that have an established relationship with our business usually self-identify immediately.  Could be legit, but betting it isn't.  If it's legit, this is a poor way to attempt communication.  Interested to read comments from whomever else gets unrequested calls from this as yet undocumented number.