Caller ID says "MASSACHUSETTS". They leave no message.

I call back after hours (using *67 to block my number).  I hear the following, "Sorry, the number you have reached is not in service.  Please, check the number, and dial again".  I then hear a short busy signal followed b about a minute of silence.  After about a minute an extended busy signal begins.  I believe that everything preceeding the last busy signal was the outgoing message.

So they don't identify themselves on their caller ID or voicemail and they leave no message.  This smells like a SCAM.