Who called from 2013578007

Keep getting harrassing phone calls at work.  Pre-tending to be a debt collector.

I get calls on my cell phone. The person cites a case number and simply says to call them. Its hard to make out the company he is saying. It has the word "silver" in it?

Same thing...some guy calling say he's a lawyer or some shenanigans. Then gives case number. I have no idea who he is, but I know I don't owe any money, so I will see if they call back.

Caller spoke with my admin and claimed to be from "Core Logic" and said my business owed $4,000 or was going to be sent to collections.  It's a fraud.

Same with us. Called twice in past couple of weeks. Says it's about a case number, a debt due or such. Can't quite get the company name, but something like "Allen ... Silver." Caller gives his name as Christopher Spencer. Totally bogus.