abusuve and threatening

Received a call February 15, 2014 at 3:39pm ... A make voice ... Seemed very far away & other than saying 'hello' to me said nothing.  Almost as though he was hoping it was someone else?

The number was found in a craigslist ad for an apartment in the Lincoln Park area of Chicago.  

No idea who called

I have received calls:
10:42 am
10:56 am
11:02 am
11:13 am
1:58   pm
3:04   pm
3:11   pm
I'm assuming that they will call through the rest of the day.  I caught them one time yesterday, waited for someone to talk and then at the top of my lungs, SCREAMED in their ear.  They are still calling.