Caller ID says "MASSACHUSETTS".  They call twice within seconds.  They leave no message.

I call back after hours (using *67 to block my number).  I hear, "The number you have dialed is not in service.  Please, check the number and try your call again.  Thank you."

I looked elsewhere for information on this number, but I discovered nothing.

So they spoof their caller ID, leave no message, and can't be called back.  Smells like a SCAM.