> The app wants permission to see his contacts, and he > grants it. Maybe he's not paying attention, maybe there's > a useful feature that needs his contacts,

> The app wants permission to see his contacts, and he > grants it. Maybe he's not paying attention, maybe there's > a useful feature that needs his contacts, maybe the > software asks the phone for permission, and the phone > allows it without asking Bob. Whatever. Facebook now > knows Alice's phone number. IIRC the app simply doesn't install if you don't grant the permissions. Facebook doesn't find my real friends. Well, the phone I have attached is a prepaid card I haven't given to anyone and I have no real friends in my phony FB account, so I guess there's no way they can find me. If I had an account with real data I wouldn't link my phone to it. Not any phone that my real connections know.