Who called from 8474533300

Several calls with nobody on the other end.

Continual calls with no one on the other end

3 calls in the past 24 hours, with no message left.

Local call, never leaves messages, and if I answer no one says anything on the other end but no hang ups either, I had to end the call.  Very bizarre.
Caller ID showed:  Hampshire, IL

This has to be a robo call., as I will get a call on my home phone and work phone both at the same time.
My home and work numbers on both on the Do Not Call Registry.