Some observations on Facebook’s “Phonebook”

Facebook has a personal “Phonebook” for your account. A couple of people have seen this and thought “Oh my God, Facebook has information I never gave it”. I’m not so sure this is correct. As far as I can tell, the information there is a combination of information other people have added to their account plus information I have shared. Based on my observations, it appears the information they’re showing me is either

• Phone numbers I already had
• Phone numbers that my Facebook friends share with their friends
• Phone numbers that people who aren’t Facebook friends share with the public
• And in some cases, phone numbers I already had combined correlated with the FB profiles of people who have put their phone number in the protected part of their profile

I cannot find a single instance of it divulging a phone number to me from a stranger. But I can see why people might be a little surprised about that last part. I’m not.

I use a phone operating system, WebOS, that integrates all my contacts from Google, from information I imported from my old Palm Treo, from LinkedIn, and also information it downloads from Facebook. This is kind of cool, because when I get a phone call from a Facebook friend I get their Facebook profile picture showing up on the screen. It also means I don’t have to grovel through multiple sources to get all the information I know about somebody. I suppose I shouldn’t be too surprised that some of that information made it up to Facebook. I can’t recall for sure, but I might have also used one of Facebook’s “Find your friends, upload your contacts” things. I’ve also set up various links between Google contacts and Apple Address Book and the like, so it’s damn near impossible to find where the data came from.

So here are some observations on what data they have, and what data they don’t have.

Case 1: My FB friend Dennis Mike was worried because when he looks at his phonebook, it shows his cell phone number which he doesn’t think he’s every shared with FB. I don’t have his phone number in my phone, and he doesn’t show in the FB Phonebook for me. So it’s not sharing his phone number with people who didn’t already have it, even FB friends.

Case 2: It shows my daughter’s phone number (which is information I already had) linked to my daughter’s FB profile with a “Add as friend” link. (She unfriended me a while ago, long story.) I assume that this is combining information I already had (her phone number) with information that Facebook got from her profile and decided “aha, this Facebook profile is a person you already know”. She may not be disclosing her phone number to non-friends, but FB decided that’s information I already have.

Case 3: It shows my brother’s phone number, but it’s not linked to his profile, in spite of the fact that we’re FB friends. I think that means that he never linked his phone to FB, and because his name on my phone is different than his name on FB (Dave versus David) it doesn’t manage to find the link.

Case 4: It shows a guy who I had some business dealings with, full name, linked to his Facebook profile with an “Add as a friend” link. In my phone, I have his number and his name as “Dave @ [company name]”. So I guess this is another example of FB correlating a phone number in my phone with a phone number that somebody put in the protected part of his profile.

I guess my point of this investigation is that Facebook has some information, and they’re able to do some correlations on this. What’s visible seems pretty innocuous, and it really does help you find the FB profiles of people you know. I see this feature as a good thing, both because of the way it helps you and because it gives you some insight into the sorts of correlations that it’s possible they’re doing behind your back and not exposing to the general public. As they say on Angry Mac Bastards, if a business isn’t charging you money, it’s because you’re not the customer, you’re the product.