Facebook may have your private phone number

In today's cutting edge world of technology, there have been ongoing battles about privacy online, and privacy features. Facebook is no exception to this, as they have had numerous privacy related concerns. Now users will be struck with paranoia once more by a "feature" in Facebook's iPhone and Android apps.

Facebook Sync is to blame for this apparent privacy blunder. The service attempts to sync your friends' profile pictures with the contacts in your phone. To do this, Facebook will upload all of the numbers in the address book and essentially do a quick comparison, according to The Guardian. The information gets uploaded to Facebook's Phonebook app, which is essentially a place where you can find all of the numbers of your contacts on Facebook. That's fine if you're happy with that but the warning was not clearly present on previous versions of the Facebook iPhone app. If you enabled this functionality previously then you may want to check this page to see if any phone numbers are listed.

You may be surprised at the plethora of numbers found. Some of the users added themselves, however if there were any blanks, Facebook Sync will fill these in. This isn't even just for your friends only, this applies to everyone in your address book. You are shown a warning (shown above), but still if you agree, which most people will, then privacy goes right out the window. What's not clear at the moment is how the algorithm works out and shares your numbers and if it's sharing your numbers to others.

Perhaps the more scary part to all of this is that via the Facebook API, all of this information can be easily accessed. Tom Scott's EVIL page demonstrates this incredibly well. While he anonymised the phone numbers, Scott still has shown just how easy it is to exploit this.

Image source: guardian.co.uk

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36 Comments

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OH SH*T!! someone knows my phone number, omfg, i'm totally screwed, my social life is ruined, there is a chance of HUMAN CONTACT!!!! damn.

Well you DID give fb your number, why cry? if they start sending you premium texts, sue them or whatever. not the worst thing to ever happen

Another time I'm glad I don't have a cell phone

I left the field for home phone blank, if anybody want my phone number they have to ask for it.

I am pretty sure this article is totally wrong. First, as others have mentioned, it can only match up phone numbers that user's have shared on Facebook. There's no way that it will add phone numbers for your friends on Facebook that don't already have them shared. Last, there's no way that your phone number is going to show up in Google search or sites like Evil if you share it in your profile and it's not marked PUBLIC. If you're dumb enough to post your phone number in a PUBLIC forum/group of any kind, of course it'll be searchable by anyone.

Total article failure.

If you are dumb enough to put your phone number in a group of random people who also lost their number (stupidy likes company i guess) then I don't think you care about random people calling you!

Most of my friends put their number on FB or if they change numbers update it there. Anyone one of us can then either have the number pushed down to the phone or manually update it. If you are on my friends list on facebook, odds are you already had my number! My info isn't public so it doesn't matter too much but yeah if someone goes and searches for my number in FB it should pull up my photo.

if you don't add your number to your profile then it has no contact to "match" it against.

I dont see how this is a concern. If you have added your number and allowed your friends to see it then why should you care if their phones upload it to facebook for matching. Not unless they are taking the name and number uploaded and matching it.

i use facebook and exchange to actually store my contacts phone numbers... all good in the hood

This is simply not true. I use the Facebook iPhone app and have contact sync enabled, but the only numbers that show up in Facebook are the ones that people have shared themselves. It uses the numbers to match a phone contact to a Facebook contact. If there is no number shared by a Facebook friend, how would it even know to match them up to add the number?

i just did this and my phone number isn't on facebook and neither are the few other random people i have on my contact list on my iphone...

Not really a problem tbh =/ I mean a lot of people's numbers are available in the white pages and if not pay a few dollars and I'm sure you can get all their personal information.

iAltair said,
I felt so naked after joining Facebook.

Sure it wasn't because of those "special" photos you posted on facebook?

If they look in the White Pages they have my number (mobile and fixed) aswell. As long as they don't call you, what does it matter?

nevann said,
Lots of people have your number. It's really not that private
It's just another way to track what you do in your daily life. SSN is for credit. ITIN is for Tax. Phone number can be used to locate you. Employee number to track you inside the corporate environment. And so on.

These companies survive because people don't think much about the consequences due to various reasons. It takes time to think and act, but humans are by design lazy, hence corporations will take advantage of you, given the opportunity. The fine-print is one of the best examples of how corporations get you to sign up for things you don't really want. Do you really want to give your phone number to Google? Let's say, a stranger knocks on your door and asks for your phone number. Would you give it? I would say no, but you don't care. Do you?

Edited by Jebadiah, Oct 9 2010, 5:29am :

nevann said,
Lots of people have your number. It's really not that private
You might also want to revise your definition of "privacy".

Mark Thomas said,
Sigh. Who cares. Really. What are they going to do, call you?

That's not the point.

To add, I have a jerk old friend who signs me up for text subscriptions and stuff i have to pay for and cancel. But i've gone to the police for that. Still, there is an example.

Mark Thomas said,
Sigh. Who cares. Really. What are they going to do, call you?

Exactly.. that is one of the points though who really cares.. wowee they got my number they can give me a call if they want.. If they get annoying I can easily block them voila all over.

ccoltmanm said,

That's not the point.

To add, I have a jerk old friend who signs me up for text subscriptions and stuff i have to pay for and cancel. But i've gone to the police for that. Still, there is an example.

Yup...because facebook is going to go sign your number up on marketing lists, spam lists, and every other list you could think of, just to screw you.

SirEvan said,

Yup...because facebook is going to go sign your number up on marketing lists, spam lists, and every other list you could think of, just to screw you.


Maybe not that bad, but you have to think: Why is Facebook obsessed with harvesting all this data? There's motivation for a reason.

Trueblue711 said,

Maybe not that bad, but you have to think: Why is Facebook obsessed with harvesting all this data? There's motivation for a reason.
Duh. So does Google and people still use their search engine, give them e-mails, chat, voice mail, etc. What do you think is the motivation behind what Google is doing? I bet Google would love to be as close to people as Facebook is.

I don't know why this is news though. The Facebook Android app already does this. Why didn't this make it to the front page when Facebook released the Android app? Did Guardian and Neowin just notice the "Notice"?

Sad thing is, even if you dont use facebook your number can still be compromised because you have clueless friends who do. Best thing nowadays is to keep all your info to yourself.

efjay said,
Sad thing is, even if you dont use facebook your number can still be compromised because you have clueless friends who do. Best thing nowadays is to keep all your info to yourself.
The point of a phone number is to contact you, bit difficult to keep it to yourself.

BGM said,
yes facebook does have my number.. i gave it to them.

Exactly! Don't know why people complain when they freely gave away their information anyway!