Update for iOS 12
With iOS 12 and iPhones that have Touch ID, you can still bypass the iPhone lock screen and trick Siri into getting into a person's phone. The bypass is the same as it was in earlier versions of the operating system:
- Press the home button using a finger not associated with your fingerprint authentication, prompting Siri to wake up.
- Say to Siri: Cellular data.
Siri then opens the cellular data settings where you can turn off cellular data.
[ Further reading: How to use a strong passcode to better secure your iPhone ]
As was the case before, anyone can do this. It doesn't have to be the person who "trained" Siri.
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