Sharon Standifird is a mom in Texas that invented a brilliant app called Ignore No More. When a parent calls their kid and the kid doesn't answer, the app will lock their phone and give them two options. They can call their parent back or call 911.
They cannot play games, text, etc until they call their parents back and get the unlock code.
Ignore No More costs $1.99 but it's only available for Android phones. Apple doesn't allow apps to lock up the phone the way this does.