E911 System Overview
The central office routes 911 emergency calls into a dedicated emergency network. The calls are then distributed to the correct emergency operator by using either the automatic line identification information (ALI) received with the emergency call or the registered billing address of the line on which the call was made.
E911 is a system where emergency calls are routed through an E911 Adjunct with additional location information to the call. Support for this is only available on control units shipped with a U-Law default and set to United States locale.
The use of E911 may be mandatory in some locations and may include the provision of an adjunct owned and managed by a third party or the central office.
Dial Emergency Short Codes
On all IP Office systems, short codes using the Dial Emergency feature should be created which are accessible by all users from all extensions. If the system uses prefixes for external dialing, additional Dial Emergency short codes should be created to allow the dialing of emergency calls with and without the dialing prefix.
Emergency Dialing without an E911 Adjunct
If E911 is not enabled, all emergency calls are routed via normal short code operation.
In this case Dial Emergency short codes must be created as described above.
The lines used to route an extension's emergency calls must be correctly registered to the physical location of the extension. That information is held by the central office.
Emergency Dialing with an E911 Adjunct
An E911 adjunct is an additional piece of equipment. It holds a database of location information based on the base extension number passed to it by the IP Office. Connection from the IP Office is by loop-start analog trunks. The adjunct is then connected to the central office's 911 emergency network by CAMA (Centralized Automatic Message Accounting) trunks.
When E911 is enabled and operating, all 911 calls are routed to the adjunct. The base extension ID is used to add the appropriate location information to the calls ALI before passing it to the emergency network.
If emergency calls cannot be routed to the E911 adjunct due to congestion, the IP Office will automatically overflow to the first available external trunk. The E911 adjunct includes an alarm switch that can be connected to an IP Office analog extension port. Overflow of emergency calls can then be triggered if the E911 indicates an alarm such as disconnection of the adjunct trunks.
If you are using E911 with an E911 Adjunct, the following needs to be administered:
On the E911 System tab select Enable.
In the Adjunct Trunks list select those trunks that are connected to the E911 Adjunct.
In the Alarm Station field, indicate the extension number of the user to which the E911 adjunct's alarm connection has been connected.
- On an operator or security extension, a programmable button can be set to monitor the status of this user. That button will then indicate in use when the E911 adjunct is in it alarm state.