Facebook users who deleted their Facebook data have discovered that the social network’s mobile applications have been recording much more information than most people were expecting. Logged information includes data on all phone calls made on the phone, the start time o each call, its duration, and the contact’s name. The Facebook app did not log phone calls to and from numbers not saved in the phone’s address book. The app also gathered information on all sent or received SMS messages to contact list entries. Not all accounts that Bleeping Computer checked had this information stored in the Facebook account backup.
Source: https://www.bleepingcomputer.com/news/technology/facebook-collected-call-and-sms-metadata-from-some-users-smartphones/