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I've just read this piece of news that Android and Windows phones will get a 'killswitch', rendering them useless to potential thieves.

However, since all devices have a unique identification number (IMEI), why haven't mobile operators been blacklisting phones designated as stolen? I've worked in telecommunications and when a subscriber makes a call, a call data record is generated that contains loads of information including the unique ID of the device. Potentially, they could simply refuse connection to a blacklisted device, couldn't they?

I remember reading about mobile operators in Uganda blacklisting 'fake' phones (source) using the IMEI of the phone, so technically it seems feasible.

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Mobile operators already use this feature. By reporting the IMEI number of your stolen handset it will be recorded in the Equipment Identity Register (EIP) to prevent the use of the stolen handset in the network. After ensuring the device is stolen, the IMEI is transfered to Central Equipment Identity Register (CEIR) which is a database of handset on a blacklist and it will render the device unusable on all other network providers as well.

Many carriers, including AT&T and T-Mobile, are now using this shared database inside the U.S and Canada. As Rory mentioned, most European carriers are Europe-wide so this feature will work across Europe

I would also like to add that the killswitch is different than IMEI blocking. The main goal of the killswitch is to render the phone completely useless by remotely erasing all data from it and therefore turning a phone into "paperweight". As for the IMEI blocking, it only prevents the handset from connecting to the network (IF the specified network is using the shared database for blacklists)

The terms "paperweight" or "bricked phone" refer to a handset that has lost all operating system data, partition data, and bootloader data; preventing someone from re-flashing the OS on the phone. The handset is completely unusable, even for offline tasks such as taking pictures or running apps. In such a case the phone turns on, but constantly displays the manufacture logo screen. It literally has the value of a "paperweight"

Apart from rendering your phone completely useless the killswitch makes sure your sensitive data does not fall into the wrong hands.

  • But why would a killswitch be necessary then if there's already a way to blacklist a stolen phone and render it unusable? Particularly for the USA and Canada anyway, where, as you say, this is already done. – Nobilis Jun 20 '14 at 9:10
  • Killswitch can be at a different level, Nobilis. IMEI is useful for the carrier, but if I or one of my staff loses a device we may want to be able to kill it without having to go through the carrier's process. – Rory Alsop Jun 20 '14 at 9:48
  • Abbas - most European carriers are Europe-wide, so this feature does work across most of Europe. – Rory Alsop Jun 20 '14 at 9:49
  • @RoryAlsop Yes, that makes perfect sense, if you want to look at it from an information perspective. As the primary motivation in the article was described simply as 'theft', I wondered why this is big news since you can already prevent theft by simply blacklisting the IMEI of the device. – Nobilis Jun 20 '14 at 10:01
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    There is a big problem with stolen phones (iPhones in particular) being sent to europe for use. Blocking the IMEI in the US does nothing to stop this. There are also those using the phone with wifi only which isn't stoppable. I am not a big fan of the kill switch, but it does certainly offer protection that IMEI blocking cannot. – David Houde Jun 20 '14 at 11:02
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Additionally to the great explanations provided by others. IMEI cloning can be a problem that simply blocking won't prevent. It is possible for the IMEI to be changed. It needs to be a valid number, but there is nothing preventing someone from doubling up the IMEI or taking the IMEI from a cheaper phone and applying it to a much more expensive phone so that the more expensive phone can be sold at a profit.

Either option would likely cause issues down the line, but that would be after they already sold the phone and don't particularly care what happens to the buyer.

  • IMEI changing on iPhone is impossible as far as I know, other than unreliable jailbreak tweaks that will break every time the OS is updated. – user42178 Feb 15 '15 at 13:42
  • I'm not sure if it is possible to clone with a jtag or similar device against the hardware directly, but a thief doesn't care if it works long term. They care if they can pawn it off on someone before it breaks. – AJ Henderson Feb 15 '15 at 14:39
  • There aren't any JTAG solder points on the iPhone board, so that would require careful de-soldering of the telephony chip and reversing it (and doing that each time its firmware is updated)... I think it would cost more than just buying a new device... – user42178 Feb 15 '15 at 14:53
  • Fair enough, but a permanent fix still isn't a concern for a thief. They just want to get the cash. They are almost never the end user, because they know having stolen property is a bad idea. – AJ Henderson Feb 15 '15 at 14:57
  • In my opinion they don't even bother with changing the IMEI (at least not on such phones where it's more expensive than buying a new one) and just scamming naive buyers... easier for them and they're criminals already so it doesn't feel "wrong" for them. – user42178 Feb 15 '15 at 15:01

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