It is a great idea though. I have been known to lock myself out by accident so this would be very useful for me. Many of those type systems have emergency code

It is a great idea though. I have been known to lock myself out by accident so this would be very useful for me. Many of those type systems have emergency codes (i.e. dial #0911 or #9110) that will also automatically unlock the doors for the fire/police. On the other hand, I could think of emergency or family uses where combined with a PIN code something like this could allow emergency access to a family member's apartment and also notify authorities at the same time. Or for a hack to have the system notify authorities while entering the building without alerting someone else.