Oct 11, 2014
811 is a service code, not a prefix. In the US, 811 - just three digits - is used for regional services that coordinate location services for underground public utilities.
At any rate X11 numbers, i.e. 411, 611, 811, 911 are service codes and not available for prefix assignment. ANY call you get that looks like AREA CODE + X11 + XXXX is fake, a spoofed number. Don't even bother calling back. If you get anyone at all, it will be phone repair, information, 911 emergency, social services, whatnot.
http://en.wikipedia.org/wiki/8-1-1
In any event, I logged a call from a spoofed 714-811-2456 when I wasn't home. On the block list it goes.