I don't know if it'd work if her phone's off. Best we could hope for would be last known location... We do have the "find my iPhone" app, but I'm still hoping that she just forgot to toss it on a charger. This is where cell phones fail us... We don't own a home phone anymore because we all have cells and do our best to keep them charged, normally. I know I carry a charger wherever I go, so my phone is rarely off.