Where in North America is area code 911?

There is no 911 area code in North America; 911 is used for emergency services.

When a caller makes a 911 call from a disconnected cell phone or a phone with no number attached to it, the FCC requires that a carrier still complete the call. The caller ID for that call would come up with a 911 area code with a phone number after it.

As far a prank calls with 911 area code, my guess is that it would be generated by a computer or a jail broken cell phone.