First Source Advantage LLC Calling my work I don't even know who these people are! Internet

My boss came to me the other day advising that this number, which I provided, has been calling me everyday at work saying it's a very important call for me. I don't even know who these people are. I have received no correspondence or anything from them. It really doesn't seem legitimate given the fact that they are only calling my work. No one calls my work unless it's my kids' daycare w/ an emergency. My own parents don't even have my work #. All other businesses call my home.

None even have my cell, except maybe 1. When you call the # I provided they don't even leave their name until you wait for a representative then you can just leave a message. I thought someone told me once legitimate businesses always say their name when you first call? I see other people were reporting this company as well. If this is valid and I owe them a debt or something wouldn't I have received something in the mail? Or wouldn't they have called my home phone? I know all debt I owe. I have never heard of these people. Thanks.