Section: 5.2.2.3.2 Namf_EventExposure_Subscribe service operation
Content: Service operation name: Namf_EventExposure_Subscribe. Description: The consumer NF uses this service operation to subscribe to or modify event reporting for one UE, a group of UE(s) or any UE. Input, Required: NF ID, Target of Event Reporting: UE(s) ID (SUPI or Internal Group Identifier or indication that any UE is targeted), ((set of) Event ID(s) defined in clause 5.2.2.3.1, Notification Target Address (+ Notification Correlation ID))s, Event Reporting Information defined in Table 4.15.1-1. Input, Optional: (Event Filter (s) associated with each Event ID; Event Filter (s) are defined in clause 5.2.2.3.1, Subscription Correlation ID (in the case of modification of the event subscription), Expiry time, list of group member UE(s) whose subscription to event notification(s) are removed or added for a group-based event notification subscription, operation indication (cancellation or addition), Idle Status Indication request (if UE reachability or Availability after DDN failure reporting is requested). Output, Required: When the subscription is accepted: Subscription Correlation ID (required for management of this subscription), Expiry time (required if the subscription can be expired based on the operator's policy). Output, Optional: First corresponding event report is included, if available (see clause 4.15.1). The NF consumer subscribes to the event notification by invoking Namf_EventExposure to the AMF. The AMF allocates an Subscription Correlation ID for the subscription and responds to the consumer NF with the Subscription Correlation ID. UE ID identifies the UE, SUPI and/or GPSI. Event ID (see clause 4.15.1) identifies the events that the NF consumer is interested in. The Subscription Correlation ID is unique within the AMF Set. The ((set of) Event ID(s), Notification Target Address (+ Notification Correlation ID)) helps the Event Receiving NF to co-relate a notification against a corresponding event subscription for the indicated Event ID. In the case that the NF consumer subscribes to the AMF on behalf of other NF, the NF consumer include the Notification Target Address(+Notification Correlation ID) of other NF for the Event ID which is to be notified to other NF directly and the Notification Target Address(+Notification Correlation ID) of itself for the Subscription Correlation ID change event. Each Notification Target Address(+ Notification Correlation ID) is associated with the related (set of) Event ID(s).When the Subscription Correlation ID change due to the AMF reallocation, the notification is sent to NF consumer which triggers this subscription. Event filter may include "AN type(s)" as part of the list of parameter values to match and it indicates to subscribe the event per Access Type. Event receiving NF ID identifies the NF that shall receive the event reporting. When the consumer NF needs to modify an existing subscription previously created by itself in the AMF, it invokes Namf_EventExposure_Subscribe service operation which contains the Subscription Correlation ID and the new Event Filters with Event ID to the AMF.