Hello! Could you please share with your experience of work. My girlfriend is the stewardess

and she calling every day to dispatcher to get the information about next flight. Taking into account that all 2000 employees are doing the same , the telephone numbers (only 3) they are calling to is permanently busy.

By the way, it's actual not only for stewardesses but for pilots also.
That's why I'm interesting how it works in your countries – how do you know about the next flight you'll work in?
thank you!