How it Works

This section describes how this feature works.

In the first occurrence, the UE registers with AMF through the initial registration or the mobility update registration procedure with a new AMF instance. In response to the registration request, the AMF sends the emergency service parameters to the UE.

When the emergency profile is modified, the UE is notified through the procedures defined in UE Context Update. To communicate the emergency services configuration, the UE reregisters with the AMF. The reregistration request has the Registration Required indicator in the Update Configuration message.

During the registration procedure, the AMF searches for an emergency profile in the call control policy configured for the UE. If the AMF detects the profile, it sets the following parameters in the Registration Accept message:

  • Emergency Services Support in the 5GC network feature

  • Emergency Number List in the Registration Accept message

  • Additional Emergency Number List in the Registration Accept message

When the UE does not have a valid subscription in a specific area, it can continue to register for the emergency services. This is driven based on the emergency services profile configuration on the AMF.