On my Samsung Galaxy SIII, one can go to Settings -> More -> Security -> SIM card lock -> Set up SIM card lock -> Lock SIM card` which displays a check box which can be used to configure the phone to either (a) require the user to enter the SIM PIN when the device finishes booting up to access all of the device's features, or (b) to access the device without ever having to enter the SIM PIN, not even after the device has been booted.

  • I would like to ask, where is the information about requiring or not requiring the PIN stored? Is it stored on the SIM card or on Android internal storage? In the first case, inserting the SIM in a new phone would preserve the setting, and in the second case it would not. Can anyone please confirm?

When the user is not required to enter the PIN, the PIN on the SIM card is not deleted and the user is in fact require to enter such PIN both when enabling or disabling this feature. Hence I would also like to ask:

  • If the user changes the PIN. Is (1) the old PIN on the SIM card overwritten with the new PIN, or, (2) does the SIM card preserve the old PIN and store the new pin in some other location on the SIM card, or, (3) is the new PIN stored on internal storage leaving the SIM card unaffected? I'm not sure how I would go about checking this, but I would be interested in knowing the answer.


  • 1
    Just to #1: My guess is it's stored on the SIM – since when I've disabled it, and then put the SIM into another (factory-reset) device, I was not asked for a PIN again. Just experience, not knowledge – hence a comment, not an answer :) – Izzy Dec 15 '14 at 19:09
  • Interesting. That means the information is stored on the SIM card. I don't have another phone with me at the moment. I wonder, if you don't mind, if the PIN is changed and the SIM card is placed in another phone, I bet you need to enter the new PIN on the new phone as well, so the new PIN is also stored on the SIM. What I don't know is whether the new PIN overwrites the old PIN, or whether after changing the PIN the factory-default and previous PINs are still known to the SIM card or not. Thanks. – John Sonderson Dec 15 '14 at 19:27
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    It's a SIM pin, Android has nothing to do with it. A factory-reset won't restore your "old" pin, and switching the SIM to another device will require you to enter the new pin there. So strictly speaking, this is not even an Android question ;) – Izzy Dec 15 '14 at 19:38
  • I've tried this. When the PIN is disabled, the old PIN remains on the SIM card, and needs to be re-entered to re-enable SIM PIN lock. There are also screen lock features provided by Android, but these are separate and have nothing to do with the SIM card: information configured with screen PIN lock and other screen lock features are stored on the device's internal storage. – John Sonderson Dec 17 '14 at 14:11

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