Facebook argues that users gave it permission but many users say that is false, and the permission was for “Contacts” to “help friends find each other” and was not for “Let Facebook Log your phone calls and text messages in our secret database so we can share that with others and learn when you are talking to your doctor or therapist”.
Facebook has not provided any explanation for why it needed phone and text records nor what it used them for.
Source: Facebook scraped call, text message data for years from Android phones [Updated] | Ars Technica