Try this on your iOS7 iPhone.

1) Lock the screen (password protected for security).
2) Press emergency call while the phone is locked.
3) Enter any telephone number you wish to call.
4) Tap the call button continuously, quick succession, and without stop. Sooner or later your phone will reboot.
5) Listen to the earpiece and noticed that it dialed the non emergency number.

Neat feature eh? Now anybody can use your phone for IDD calls even if it's locked and password protected.

Sent from my mind using Telepathy 2