If she didn't have a cellphone, she would have to come home after school, and let me know where she is heading. When I was 14, I either came home when school let out, or used a payphone to call my mom, letting her know where I was going, and when I'd be home. Sometimes I need her to come straight home, because I forgot about an orthodontist appointment, or need her to watch her siblings.
I call her, because she's getting a little big for her britches (forgetting to call, or telling me she's eating at someone's house, instead of asking). She's on a pretty long rope, but as a parent, I have to remind her that I'm still holding the other end.