How would I go about obtaining someone's last name if I only know their first name and place of employment?

Any super sleuths out there:)? This number has been calling me and harrassing me. I've been trying to find out who it is, but it's a prepaid cel phone. However I do think I have figured out who he is. I want to know if it's my ex before i get the police involved or anything. Any pointers would be great. Thanks

How would I go about obtaining someone's last name if I only know their first name and place of employment?
No, I don't think so. But even if it IS your ex....if the calls are that bad and threatening I wouldn't hesitate to get the police involved. The police can talk to the cell phone provider and find out who it is that's calling you.