Yes ATI is getting all their aircraft from a company in Florida,their based in Orlando that buys and maintains their own fleet,but other companies can lease or borrow them it is Cargo Aircraft Management Inc.Look them up and the list they have available,they have lots of B757,B767.It is part of the Air Transport Services group.Several large Cargo carriers are using their aircraft.
Thru Mode S i cross check the tail numbers with FAA database,even though one company maybe borrowing aircraft it will tell what company owns it for sure.