Who called from 4842543815

Got two calls from this number in one day. No messages left. Who are these people?

I just got a call today from this number.  You all said it's verafast?  http://www.verafast.com/   You have to check it out...they specialize in all sorts of crap!  It's a call center that could call you for lots of different things.   Like hell I'll be answering!

Called this evening, it said "Headquarters".  Didn't leave any messages.

Have been receiving calls at work number 2-3 times/day for the past 2 weeks.  I don't recognize the number so I haven't answered.  Glad I didn't.

They call everyday, sometimes more than once. They never leave a message. I was home and able to answer twice.  The line was dead and hung up.