Option 1. Continuing to use 9+ dialing
A. on ARS line that contains 11 / 911 / Dial emergency / 0... modify entry = 11 to be 11; (add semi-colon)
B. Add new entry on ARS = 11N / / Barred / 0
A. 9+911 will reach E911 immediately
B. 911 will reach E911 after dial delay timer expires
C. 911 + any other digit will be barred
Comment: in my experience this eliminates almost all false 911 calls. Most people dial 9+1, then pause, look at number, dial 1+10digitnumber, and bang you've got a false 911 call. This halts that. 9+ dialing is preserved. 911 dialed on its own does get through to E911, albeit slightly delayed.
Option 2. Change to 8+ dialing
A. Change system 9N short code to 8N (all other parameters remain the same)
B. REMOVE the ARS line that contains 11 / 911 / Dial emergency / 0... failure to do this will mean dialing 811 will call 911.
C. Create a new system Short code 911 / Dial Emergency / 911 / 0
A. 8+911 will reach E911 immediately
B. 911 will reach E911 immediately
Comments: Has the advantage over option 1 of having no delay for just dialing 911. Disadvantage = it's 8+ dialing, not 9+ dialing (how weird is that???). Has implications for extension numbering (8's and 9's).
Lab Testing: can be tested by setting the ARS to dial your cell or office line instead of E911.
Warning: should be tested for real, on site, every single time you deploy.