I can't speak for all phone companies but AT&T has "Call Trace" Correct me if I'm wrong but after two traces, the offender is sent a letter....assuming, of course that they can actually trace it. On the third attempt, law enforcement is involved. The "Do Not Call" list doesn't seem to have much success but maybe the phone company will.
When we were called, my daughter said it was a wierd man's voice on the phone. When I got it, he was gone. I checked and saw that they called 4 times today while we were out. A call back resulted in a busy signal after a few minute wait. Jerks!