Who called from 2152134899

Received a call from this number on July 12, 2012 at 11:12 AM.  Caller ID: Pennsylvania.  Caller waited for 6 rings but hang up after the beep of my answering machine and did not leave any message.  I am on national DO NOT CALL list.  When I called back, I received the following message: "Sorry, the number you have reached is not in service.  Please check the number and dial again."

I also got this call and no answer when I star 69 it says the number does not exist?

Didn't answer.  Caller Id = Pennsylvania

will not stop calling, when I then three weeks ago to please take my number off their call list.

Number called me, no answer. Dialed it back, number not in service