Legal questions: Who had title to the phone? If it belonged to the father, could he have charged his son with theft for failing to give it back on request? Important because the cops tend to listen more to the first person to call them.
Yes, file charges against the little punk. Bet that phone was the best money could buy which will bring higher charges of theft. His college fund should disappear along with the kid's car and any other thing in dad's name. Whatever dad does, do not let the kid think he can lord it over the rest of the family with threats to call CPS.