Who called from 8152092830

Got a call on my cell phone from this number.  Anyone know anything about who this is?

Got a call from this number 815-209-2830.  they didn't properly identify themselves or ask for any specific person.  In fact they just sat their until I started asking specific questions like who are you, what do you want.  Very spooky, very intrusive and no excuses for these guys.  Please send them back for retraining or are they just trying to collect everyones cell phone number and collect a huge cell phone database????

This is local number for the U.S. Census Bureau, local office located on Main Street in Rockford, IL.