Unwanted phone calls and threats

I have been recieving these calls for months now.  I have no idea where they are coming from, but my caller ID always shows a different number, even a different area code.  I have repeatedly asked to be removed from their list (obviously without any success!) and they usually just hang up on me.  However back in December the "operator" was a man and began to threaten my life and calling me terrible names.   I filed a complaint with the Attorney General of Missouri, but nothing has been done.  I don't know what else to do about this!