Section: 5.2.16.3.4 Nnssf_NSSAIAvailability_Subscribe service operation
Content: Service operation name: Nnssf_NSSAIAvailability_Subscribe Description: This service operation enables a NF Service Consumer (e.g. AMF) to subscribe to a notification of any changes in status of the NSSAI availability information (e.g. S-NSSAI validity time, S-NSSAIs and optionally NSI IDs available per TA and the restricted S-NSSAI(s) and optionally NSI IDs per PLMN in that TA in the serving PLMN of the UE) upon this is updated by another AMF. This service also enables the NF Service Consumer (e.g. AMF or NSSF in the VPLMN) to subscribe to a notification of Network Slice Replacement and Network Slice Instance Replacement. Inputs, Required: Callback URI of the NF Service Consumer: Inputs, Conditional Required: If this service operation is invoked to subscribe for changes in status of the NSSAI availability information, then the following inputs are required: - list of TAIs supported by the NF service consumer, event to be subscribed. If this service operation is invoked to subscribe for changes in status of the NSSAI validity time information, then the following inputs are required: - The S-NSSAIs, event to be subscribed. If this service operation is invoked to subscribe to a notification for Network Slice Replacement, then the following inputs are required: - for the S-NSSAI of the serving PLMN: set of S-NSSAIs served by the NF Service Consumer that may be replaced, NF type of the NF Service Consumer (e.g. AMF), Requester ID, event to be subscribed. - for HPLMN S-NSSAI: S-NSSAIs for the HPLMN, NF type of the NF Service Consumer (e.g. AMF or NSSF), Requester ID and PLMN ID, event to be subscribed. If this service operation is invoked to subscribe to a notification when the Network Slice instance is congested or no longer available, then the following inputs are required: - The S-NSSAIs, NSI IDs, event to be subscribed. Inputs, Optional: Expiry time. Outputs, Required: Subscription Correlation ID. Outputs, Conditional Required: If this service operation is invoked to subscribe for changes in status of the NSSAI availability information, then the following outputs are required: - Expiry time (if present in the request, may be included in the response based on operator's policy and taking into account the expiry time present in the request (i.e. should be less than or equal to that value); if not present in the request, may be included in the response based on operator's policy. Whatever the case, if not included in the response, this means that the subscription is valid without an expiry time). Outputs, Optional: If this service operation is invoked to subscribe for changes in status of the NSSAI availability information, then the following outputs are optional: - A list of TAIs and for each TAI, the S-NSSAIs and optionally NSI IDs supported by the AMF and 5G-AN and authorized by the NSSF for the TAI and a list of S-NSSAIs and optionally NSI IDs restricted per PLMN for the TAI. The NSSS indicates to the AMF that the S-NSSAI(s) are not available in the corresponding TAIs.