This time, the data that Facebook is mining is your call data and your text message data. But there is a difference. In this case, Facebook says that it asked permission when you installed Messenger or Facebook Lite. However, the default was to collect the data and it was not very clear to users that the data was being collected.
They have been doing this from both Android and iPhone users.
If you download your Facebook data (to download your data, go to http://www.facebook.com/settings and click on the tiny little link at the bottom that says download a copy of my facebook data), you can see what data Facebook has.
Roughly a year ago, Facebook made it more obvious that they were collecting the data when you install the app.
Facebook says that they never sell this data (probably true) and it’s purpose is to let friends find each other on Facebook and help them create a better experience for everyone (more doubtful).
OK; lets say you are a FB Messenger user, what can you do?
1. Check if your contacts are being synced with Facebook. The instructions are different between iPhone and Android users, but the instructions can be found at https://www.facebook.com/mobile/messenger/contacts/ .
2. You can turn off syncing contacts by following the instructions at https://www.facebook.com/help/838237596230667 . Again, the instructions are different between the iPhone and Android.
3. You can delete your call history from Messenger also. Instructions can be found at https://www.facebook.com/help/messenger-app/870177389760756?helpref=hc_fnav .
Suffice it to say, Facebook is going to try real hard to capture the data. After all, the name of the game for them is to harvest your data to increase your use and dependence on Facebook and to use that data to sell you stuff.
However, you can disable it. Just not easily.
Information for this post came from Ars Technica.