Who called from 2243572987

Got a call from (224) 357-2987 today at 12:50 PM (PDT).  Caller ID said "Illinois Call."  Since I don't know anyone from out that way, I let the answering machine take it.  They left no message.

Same people just called.  This time, a scratchy, completely incomprehensible message was left.

Who are these people!?

These people just won't let up!  So I called back, to find out who they were (probably a mistake, but at this point, I was pretty ired).  No one answered, just got a machine explaining that the "party that I was trying to reach would be notified of my call."  

They called back, and I thought, 'Okay, we'll find out who you are!' but lo and behold! they hung up...

...and called me back two more times while I was busy elsewhere!  But left no messages.

So just who the blazes are these people!?