Even if Unity connection allowed 911 or 9911 to be dialed from an AA, the CSS of the VM ports on CUCM would have to allow the call in order for it to reach the PSTN.
I would suggest looking through the CSS assigned to the Unity Connection voice mail ports on CUCM, and ensure 911 or 9911 is not able to be dialed.
If you are unsure about whether the CSS assigned to the ports will allow emergency calling, you can use DNA on CUCM to find out.
1. Go to CUCM IP address /dna in your web browser. Example: "https://10.1.1.1/dna"
2. Navigate to Analysis > Analyzer
3. Enter 911 or 9911 into the "Dialed Digits" section
4. Set the "Calling Search Space" to the same CSS that is configured on your voice mail ports.
5. Click "Do Analysis" and see if the pattern is blocked or not.
If DNA does not load, ensure the service is activated:
1. Go to "Cisco Unified Communications Manager Serviceability".
2. Navigate to "Tools > Feature Services"
3. Select the IP address of the CUCM publisher and then click "Go"
4. Start the "Cisco Dialed Number Analyzer Server" and "Dialed Number Analyzer" services.