# Can cell phones transmit while inactive? **URL:** \ **Category:** Factual Questions\ **Created:** [May 16, 2006, 12:48am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907 "2006-05-16T00:48:49Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Neur0mancer\_1](https://avatars.discourse-cdn.com/v4/letter/n/46a35a/32.png) [@Neur0mancer\_1](https://boards.straightdope.com/u/Neur0mancer_1)\ **Post date:** [May 16, 2006, 12:48am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/1 "2006-05-16T00:48:49Z")
I have a friend who is worried about privacy issues and was telling me that he does not want to discuss some subjects anywhere in the vicinity of a cell phone because, he thinks, it’s possible that cell phones, even when they’re not activated, might be picking up sounds around them and transmitting them somewhere where people might be listening. To me this sounds like paranoid fantasy. However, I’d like to get some input on this from people who actually know something about the subject. Thus: Can a cell phone which is not activated, or even turned off, be transmitting sound elsewhere? Is there any way that computer filtering can be used to sort through very large numbers of conversations to pick out key words? (on this latter, I am really not inclined to believe it - it’s hard enough to get speech recognition software to recognize ambiguous words even when it’s been trained to one particular voice) ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [May 16, 2006, 1:41am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/2 "2006-05-16T01:41:25Z")
> [@Neur0mancer.](#): > > I have a friend who is worried about privacy issues and was telling me that he does not want to discuss some subjects anywhere in the vicinity of a cell phone because, he thinks, it’s possible that cell phones, even when they’re not activated, might be picking up sounds around them and transmitting them somewhere where people might be listening. > > To me this sounds like paranoid fantasy. However, I’d like to get some input on this from people who actually know something about the subject. > > Thus: > > Can a cell phone which is not activated, or even turned off, be transmitting sound elsewhere? > > Is there any way that computer filtering can be used to sort through very large numbers of conversations to pick out key words? > (on this latter, I am really not inclined to believe it - it’s hard enough to get speech recognition software to recognize ambiguous words even when it’s been trained to one particular voice) Highly doubtful. For one thing, its fairly easy to measure whether a cell phone is sending out any communications and if anybody ever discovered it doing such a thing, there would be massive consumer backlash. Also, sending requires power, it would be impossible for cell phones to maintain their current battery life if they were constantly sending out streams of data. ---
**Author:** ![tofergregg](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@tofergregg](https://boards.straightdope.com/u/tofergregg)\ **Post date:** [May 16, 2006, 1:47am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/3 "2006-05-16T01:47:13Z")
Well, I agree that it is a bit paranoid, but I have had the following happen to me: I was playing around with my phone, and I set up a voice activated phone number to a friend. I could place the call by clicking my bluetooth headset button and then speaking her name. It turns out that the button was getting pressed while the headset was in my pocket, and because her number was the only one I had set up to call by voice activation, my phone was automatically dialing it even though I hadn’t said a thing (unless my pants somehow said her name…). Anyway, she got a lot of random calls from me where she could just hear me in the background. I finally figure out how to turn the whole thing off, but it was annoying for a while, and she could have definitely been eavesdropping if she really wanted to. -Tofer ---
**Author:** ![Malienation](https://avatars.discourse-cdn.com/v4/letter/m/4af34b/32.png) [@Malienation](https://boards.straightdope.com/u/Malienation)\ **Post date:** [May 16, 2006, 2:40am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/4 "2006-05-16T02:40:57Z")
Nah, I don’t see it used to eavedrop on the owner. However, your friend has reason to be paranoid about something else. Your cell phone network knows where you are; it has to, to find you when someone wants to make a call to you, it has to know where to go to connect to you (it can’t go “searching”; that would be too cumbersome). This is true even if the phone is not being used (but it does have to be on). Periodically, the cell phone will send out a signal to the local network that identifies the phone to the nearest cell phone tower. Some will tell you that you really only have to be concerned about GPS equipped cell phones, but that’s not so. Multiple cell towers can “triangulate” on a cell phone “ping” (the periodic signal the cell phone sends out) to get a fairly accurate idea of where you are in the cell. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [May 16, 2006, 2:45am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/5 "2006-05-16T02:45:31Z")
> [@Neur0mancer.](#): > > Can a cell phone which is not activated, or even turned off, be transmitting sound elsewhere? In cell phones are software controlled radios. They can be programmed to do most anything. Battery life is one of the most watched specs of a cell phone. They get 300 hour standby time by turning every thing off but a low power timer that wakes the phone up every few seconds to listen to see if there is a call coming into it. If the phones are one listening for conversations and then transmitting the conversations that drains the battery really quick. It seems unlikely that a person’s phone would do such a thing without their knowledge. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [May 16, 2006, 3:11am UTC](https://boards.straightdope.com/t/can-cell-phones-transmit-while-inactive/356907/6 "2006-05-16T03:11:51Z")
[Italians Discuss Purported CIA Case](http://www.tau.ac.il/jcss/guardian280705.html) > [@](#): > > It wasn’t their lavish spending in luxury hotels, their use of credit cards or even frequent-flier miles that drew attention. Instead it was a trail of casual cell phone use that tripped up the 19 purported CIA operatives wanted by Italian authorities in the alleged kidnapping of a radical Muslim cleric. > > Italian prosecutors who have obtained arrest warrants for the 19 - none still believed to be in Italy - presented evidence that the suspects used at least 40 Italian cell phones, some in their own names. > … > One has been identified by prosecutors as the former CIA station chief in Milan, Robert Seldon Lady, > … > Unless the power or the wireless antenna is turned off, a mobile phone remains in constant contact with the nearest cell towers even when it’s not being used for a call. Information processed by the cells can be used to precisely locate or track the movements of a phone user. > > Nativi, the military expert, called the use of regular cell phone accounts ``a huge weakness in the operation.’’ It would have been more difficult to track anonymous prepaid cards, satellite phones or radios, he said. AP’s take on the incident: [Cell calls expose U.S. agents in Italy](http://www.post-gazette.com/pg/05212/545852.stm) Once they have your cell number, they can figure out where you’ve been. Changing numbers early and often helps, but it’s not a perfect solution: [Surge in Sale of Disposable Cell Phones May Have Terror Link](http://abcnews.go.com/WNT/Investigation/story?id=1499905) Another tactic: > [@](#): > > The trick is known to just about every two-bit crook in the cellular age: If you don’t want the cops to know where you are, take the battery out of your cell phone when it’s not in use. Had that trick been taught at the CIA’s rural Virginia training school for covert operatives, the Bush administration might have avoided much of the current crisis in Europe over the practice the CIA calls “rendition,” and CIA Director Porter Goss might not have ordered a sweeping review of the agency’s field operations. [The Trib story’s no longer online, so here’s a chunk of it](http://gnn.tv/headlines/6848/Most_Media_Ignore_How_the_CIA_Bungled_the_Abu_Omar_Rendition)