If you have a new iPhone 4S a security flaw has been found in Siri. Siri is the voice control function. By default the feature is on and can be used even when the phone is locked. This means that anyone can pick up someone else's phone, activate Siri and send messages and email. This can be fixed by changing the default setting to "Allow access to Siri when locked with a passcode to Off"
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Posted by Jon Lutz