It was a very common hack when I was in school that, to call home, you'd make a person to person call and your parents would decline--saying the person you were calling for wasn't there--and then direct-dial you back.
[ADDED: And I'm sure there are people reading that comment with puzzled expressions who have no idea what I'm talking about. :-) ]
[ADDED: And I'm sure there are people reading that comment with puzzled expressions who have no idea what I'm talking about. :-) ]