After seeing a friend’s re-post of the recent aggregation of Facebook contacts’ phone numbers into a “Phonebook” (available by navigating through Accounts > Edit Friends > Contacts), I double-checked the privacy setting of my phone number. (Account > Privacy Preferences > Customize Settings > Contact Info). Yup, my number is set to be displayed to “Only Me.” i.e. It’s private.

Or at least, it’s supposed to be. Two different friends were able to send me screenshots of their Phonebook, in which my mobile number is clearly visible. Interestingly, I wasn’t on a third friend’s list. 

What gives?? Can anyone replicate?

ADDENDUM: I’m told this is a “known issue” as of yesterday (thx @myrcurial ;) ). Apparently if you clicked through the TOS on your iPhone/Android Facebook app, you might have missed the part where it said it will slurp up ALL your friends’ data. “Please make sure your friends are comfortable with any use you make of their information.” hah. What a fucking joke.

Thus, the privacy setting that exists controls display of your mobile number on the info section of your profile, but is totally unrelated to your friends’ phonebooks. There is no way to opt out of Facebook matching your # to your identity, if any friend uses the mobile app. You can delete YOUR list of contacts, but that does nothing to blacklist your number from FB’s cloud if sourced from a friend. >:( Do not want.