Has been calling for the past 2 years now.  I've found that the number belongs to a Nextel/Sprint user.  Abusively calling multiple times and not saying anything.  At one point called and pushed buttons to annoy.  I've provided number to the police and forwarded the number and complaint to Sprint to handle.  Hopefully this person will get what they are dishing out.  I'm sure I'm not the only one being harassed here.