Who called from 5702601707

This number calls and leaves no message, probably some kind of scammer....caller ID says St. Clair Pennslyvania.

I receive a call from this # every day.  When I pick up the phone to answer no one is on the line.  I just get a busy signal.  When I try to call them back again I just get a busy signal.  The caller ID says it is from St. Clair, PA  After awhile it gets very annoying!  Does anyone have any idea who this call is from and why they are cvalling?