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Why does my iPhone phone home when off?
December 25, 2009 2:34 AM   Subscribe

Why (and what) is my iPhone transmitting while switched off? My (Australian bought, legitimately carrier-unlocked, T-Mobile-SIM'd) iPhone 3GS is switched off (hold down top button, swipe red switch on screen) but connected to wall power and sitting on top of a poorly shielded computer speaker. Almost exactly at 5:00am it uttered the characteristic "dit dit de-dit dit de-dit dit de-dit" of a GSM phone chatting to a cell tower. I switched it off ffs, the GSM radio shouldn't be active! What is it sending to the tower and why?

I was at a pub the other day with some friends who were spouting conspiracy-theory baloney about how the CIA/FBI/NSA/USDA can track us and listen to our conversations via our iPhones. "Pshaw", I said, "while technically feasible to remotely install an app which starts an iPhone's mic recording and transmits back to a Three Letter Agency with the screen ostensibly off, Steve Jobs has got better things to do with his engineers' time and would tell the TLA to go jump unless it was law in which case I would have heard about it. You tinfoil-hat nutters!"

But then they told me to turn my iPhone off and see if it still transmits once every three hours or so. I've just done the experiment and lo and behold it does. What's going on? Do I need to be paranoid or is there a benign explanation?
posted by m1ndsurfer to Technology (12 answers total) 2 users marked this as a favorite
 
To charge the iPhone, I'm pretty sure it needs to be switched on — if I plug it in when it's switched off, regardless of how much charge it's holding, it turns on. I suppose you could plug it in then switch it off, but I don't know that it would charge.

I'm not exactly sure what you mean by 'our conversations'. If you mean phone calls, then if anyone wants to listen in to what you're saying, they don't need to compromise your phone, just hook straight into the network (see AT&T's notorious Room 641A for an example). If you're referring to actual physical conversations being monitored via your phone, then your friends have probably just watched The Dark Knight one too many times. It's technically possible, obviously, but without offering supporting evidence it's like saying that TVs secretly report what you watch to the FBI.

I can't speak directly as to why your iPhone's transmitting when it's switched off, but if it's still got power in it, the phone-related internal components still receive a charge so it's not outside of the realm of possibility that they're doing… something. I vote for benign explanation, since if the iPhone had some kind of magical 'phone home' feature, it would be on every phone, and if it was then given the length of time they've been on the market and the sheer number of them out there you'd think somebody would have noticed by now.
posted by jaffacakerhubarb at 3:37 AM on December 25, 2009


Oh, and as far as location goes your mobile phone (regardless of manufacturer) has to be connected to a nearby cell tower to function, and therefore by using triangulation, 'they' can triangulate your approximate position. This is obviously a bit easier with the 3G/3GS, since they have GPS. The emergency services can, I think, use this if you're in an unknown location or something like that.
posted by jaffacakerhubarb at 3:40 AM on December 25, 2009


Yes, by "our conversations" I mean those going on in the room containing the switched-off phone.

Yes, charging the phone requires some subsystems of the phone to be "on", but I would be incredibly surprised if charging required the GSM radio hardware to be active.

I know the phone network knows what cell the handset is connected to, it has to know in order to route calls. I'm talking about when the phone is off and not able to receive calls.
posted by m1ndsurfer at 4:35 AM on December 25, 2009


Steve Jobs has got better things to do with his engineers' time and would tell the TLA to go jump unless it was law in which case I would have heard about it. You tinfoil-hat nutters!"

Kind of a strange view. I mean, don't you think the TLA would pay him? With giving police subscriber's locations 8 million times and Yahoo trying to keep it's survelence price list secret the reason companies do these things is because the feds pay them.

Also, Cellphones need to be FCC approved, so of a phone maker dosn't cooperate with the government, they can't sell it. And this isn't just the U.S, but what kind of surveillance technology do you think China, Iran, etc requires be on phones?
posted by delmoi at 5:17 AM on December 25, 2009


"Yes, charging the phone requires some subsystems of the phone to be "on", but I would be incredibly surprised if charging required the GSM radio hardware to be active."

Unless you put the phone in "Airplane mode" with the radio disabled, when you plug it in to charge it boots itself fully including bringing up the radio interface. It's not that charging "requires" the radio to be active, it's that charging causes the phone to boot, which then causes the radio to be active unless you take some measure to prevent it.
posted by majick at 5:48 AM on December 25, 2009 [4 favorites]


Majick is correct. The phone booted when you plugged it in. No one is going to bother to have a special "charge only" mode.
posted by rr at 8:11 AM on December 25, 2009


While it is entirely possible to monitor your phone's microphone (even when it's off!), you really need to get yourself involved in something that high-level law enforcement would care enough about to tap your line before you start worrying about stuff like this.
posted by Aquaman at 8:19 AM on December 25, 2009


My first thought when I read this is that the phone is syncing with the clocks in the cell towers. Although, I don't know why it would need to sync every 3 hours.
posted by 47triple2 at 10:14 AM on December 25, 2009


If you're referring to actual physical conversations being monitored via your phone, […] It's technically possible, obviously, but without offering supporting evidence it's like saying that TVs secretly report what you watch to the FBI.
Well… TVs don't have any of the necessary hardware to transmit your conversations, so claiming your TV is eavesdropping is pretty tinfoilhatty. Cell phones do have that hardware, since that is in fact their primary function; making one act as a bug should be a straightforward change to their firmware. IIRC there have been a couple of poorly-documented but officially-acknowledged cases of this being done in organized-crime investigations.

OTOH, I think it's more than likely that the iPhone simply isn't as fully turned off as you expect, and is doing its normal cell-tower checkin. I can't think of a good way to test this theory without some fairly expensive radio equipment, however.
posted by hattifattener at 1:26 PM on December 25, 2009


Just fyi there is software available to secretly and remotely record data from your iPhone mic. I have such software installed on mine, in case of loss or theft. So it's not just "technically possible".
posted by skintension at 2:37 PM on December 25, 2009


skintension, what's the software called?
posted by mooreeasyvibe at 10:03 AM on December 26, 2009


http://www.google.com/search?q=remotely+record+from+your+iPhone+mic

Air Mic
posted by intermod at 2:53 PM on December 26, 2009


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