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On the Android Lollipop phones and tablets you can easily tap your device to an NFC tag to unlock it, thanks to the smart lock feature. To unlock your Android device via NFC tags, do as follows:
1. First make sure your device running Lollipop is secured with a PIN, Password or a Pattern.
2. Go to Settings followed by Security (Find it under the Personal settings)
3. Tap the Smart Lock, and confirm your current security code or pattern
4. Go to the Trusted Devices settings and tap the Add button on the middle bottom
5. Select the NFC option and tap your device to an NFC tag
6. If you tap correctly, the NFC Found message appears and you are asked to enter a name for the new trusted device (your NFC tag).
7. Now everything is completely set up and as long as your device is tapped to that very NFC tag, you don't need to enter password or draw pattern
** Note that, to unlock your device with this programmed NFC tag, you should turn on the screen, tap the devices together and then swipe up the lock button.