How do you teach the ATC to say airline Names?

I've come up with some fictional airlines that I fly in the sim and would like to know if it is possible to teach the ATC to say the airline name when making radio contact. In some cases, I got lucky and the sim had the name in its vocabulary, but for some of the others, all I get is the flight number. Is it possible to teach the A.I. or whatever to say the new names? Is there a folder or file I need to add the name to?