Aastra 57i IP Phone User Manual page 124

You can set the emergency dial plan using the Aastra Web UI.
Use the following procedure to specify the numbers to use on your phone
for dialing emergency services in your area.
Aastra Web UI
1. Click on Operation->Phone Lock.
2. In the "Emergency Dial Plan" field, enter the 3-digit number used in
your local area to contact emergency services. For multiple numbers,
enter a "|" between each emergency number. For example:
911|110
Default for this field is 911|999|112|110.
3. Click
116 Model 57i IP Phone User Guide
to save the emergency dial plan to your phone.