As seen on the Hacker news, there is currently a way to bypass the iPhone lock screen (iPad with SIM too?) running iOS 6.1.x
I had to change the steps listed in “The Hacker news” slightly for it to work:
-Go to emergency call, push down the power button and tap cancel.
-Dial 112 and tap green and inmediately red.
-Go to lock screen, by pressing the power button
-Go to passcode screen, by pressing the home button
-Keep pushing down the power button …1…2…3…seconds and before showing the slider “turn off”…tap the emergency call button and …voilá!
-Then without releasing the power button press the home button and let go…
From there you gain full access to the phone application and can change/add/delete contact, as well as use the phone to make phone calls but you cannot stop a call you started with that technic.