calls from this number to my cell.

no message left on voicemail....I am emailing state attorney general's office in nebraska and filing a complaint

Calls at least once a week...usually when I'm at work.  No messages left

I got it too.  I keep getting more from the different numbers in the same area code - also 213.  

Report calls like this at:

https://complaints.donotcall.gov/complaint/complaintcheck.aspx
and
http://esupport.fcc.gov/complaints.htm?sid=&id=d1e37

Also, complain to your phone provider.  Enough people complain, these jerks get in trouble.  What they are doing is illegal and they know it.

Call or go to the website of the "national do not call" and report them
they can not call your cell phone. and they want you to call them pack
that's why they only call and hang up, this way your on the hook for
calling them.