I am trying to understand a little bit about security in case my phone goes stolen. I have read that even if a phone is stolen and the SIM card is removed, it can still be possible to find your phone because the hardware has a built-in International Mobile Station Equipment Identity (IMEI) number which gets transmitted at regular intervals over the mobile network. Apparently this number can be changed in the software in the same way that, for example, the MAC (Medium Access Control) number of a hardware device such as an ethernet card can be faked on Linux via software methods, but it appears that doing so is not legal in most countries as it could help people stealing your device. So, here come my questions:

  • Am I correct in assuming that if the device is turned off (either manually, or perhaps because the battery runs out), then presumably the IMEI cannot be tracked until the device is turned on, which means that the device can go lost this way? Or is there some Android app which can reveal the location of your phone even when the phone is powered off (perhaps a phone which is powered off still uses a minimal amount of battery to make this IMEI information available to the carrier, or maybe via GPS given that GPS does not require a SIM card to be present to operate)?


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    John, we've had this kind of question already a couple of times: Off is off (unless NSA implemented some backdoor here), and without battery, dead is dead. And of course it's illegal to fake an IMEI – but so is stealing an device. And GPS also needs to be powered, besides from being rather one-way. – Izzy Dec 14 '14 at 14:53
  • @Izzy, perhaps you are right, but PCs have a small CMOS battery which can be used to power certain features, including Wake-On-LAN which can be used to boot the PC's OS by means of sending a TCP/IP packet to the PC's ethernet card. I was wondering if, given the analogousness of smartphone hardware architecture to that of PC hardware architecture, if Android devices had a CMOS battery, I thought it might supply just enough power for supporting sending some network info while off. – John Sonderson Dec 14 '14 at 16:52
  • You really believe that CMOS battery is powering the boot? Try disconnecting all power then, and "WakeOnLan" it up. I'd be surprised if you'd even get a response. No, that CMOS battery is just to keep your BIOS config, basically. There wouldn't be enough power in that to feed a data transmission. – Izzy Dec 14 '14 at 18:03
  • @Izzy, I was not saying that the CMOS battery is powering the boot. But if the battery is not completely drained, then the CMOS battery should have enough power to react to the Wake-On-LAN, and as part of the reaction, cause the OS to start-up using the main battery for the boot-up process. I don't know if this is possible on Android, but since Android is based on Linux, if the mainboard supports this behavior then it should be possible (perhaps with root access). – John Sonderson Dec 14 '14 at 18:26
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    Though theoretically there might be ways to accomplish something like that (with a special mini-boot partition etc.), I've not heard from that in praxis. If it were there, I'm pretty sure someone would have discovered this. I have no definitive answer; all I can say is it's pretty unlikely. – Izzy Dec 14 '14 at 19:45

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