Using the E911 service, you can identify the physical location of a registered user in the event of an emergency call. The system determines the location using the IP address and port level discovery of the E911 administration.

Session Manager interacts with E911 service user registrations to obtain an Emergency Location Identification Number (ELIN). Each Session Manager synchronizes with the E911 services server, stores ELIN records for registered users, and sends the ELIN to the Communication Manager when a user makes an emergency call. Session Manager synchronizes with the E911 services server when:

• You add the ELIN server to the Session Manager.

• The connection between Session Manager and the server is lost and later restored.

• User registration and unregistration causes the Session Manager to synchronize with the E911 service.

E911 services operate in a primary and secondary server mode. The primary server is active, and the secondary server is in standby mode.