Why?
Why play music over the phone instead of just talking? Why not call the cops for christs sake? Great movie, but some parts dont make sense. Was it explained in the book?
shareI've not read the book, but I guess they were avoiding getting overheard on the phone - if all their parents could hear was music, they wouldn't assume they were having contact with the outside world.
As to why they didn't call the police, they probably assumed the powers-that-be would just side with their "respectable" parents - and they were probably right, given that nobody bothered checking if any home schooling was actually taking place when they were taken out of school, for example.