ITS AN OFFSHORE SCAM - so while NOT impossible to track down - its very difficult to do so - they are using VoIP which makes it hard to trace the calls back to a certain location, as well as CHANGE the phone#'s they use almost daily.
JUST TELL THEM YOU KNOW THEY ARE SCAM AND HAVE REPORTED TO Secret Service, FBI, Attorney Generals and FTC and hang up then ignore any more calls.
When they call my business looking for people I actually give them the FBI main switchboard number as a good number to reach the person they are looking for. Either that or I tell them the person was fired for getting too many personal calls.
Funny, I haven't gotten one of these calls in a while...