How it Works

This section provides a brief of how the SMF and UDM interact over the Unsubscribe-to-Notifications message:

  1. The NF such as SMF sends an Unsubscribe-to-Notifications request to the resource identified by the URI to the UDM. The SMF transacts the request to the UDM over the N10 interface. The Unsubscribe-to-Notifications request lets the SMF unsubscribe from notifications for a specific subscriber session. The SMF receives the URI details during the subscription creation process.

    The Unsubscribe-to-Notifications request contains the ‘SUPI’ and ‘subscriptionId’ in the URI.

  2. The UDM processes the request, and based on the response; it sends a response code to the SMF. For example, if the unsubscription is successful, then UDM sends 204 code. If the request is not processed, then the appropriate HTTP status code indicating the error is returned in the response body along with the additional error information.

  3. The SMF is equipped to handle the timeout and failure that occurs when sending the Unsubscribe-to-Notifications messages to the UDM. In the event, the Unsubscribe-to-Notifications request fails, the SMF continues to purge the corresponding sessions.

    The Unsubscribe-to-Notification message is required for sessions that are hosted on the EUTRA network. They may not be a requirement for sessions that are released on the NR and WLAN network. For these access types, the SMF sends the UDM registration and deregistration messages that include subscription to notifications through implicit-unsubscribe during the deregistration.