5.30.3.3 UE configuration, subscription aspects and storage

To use CAG, the UE, that supports CAG as indicated as part of the UE 5GMM Core Network Capability, may be pre-configured or (re)configured with the following CAG information, included in the subscription as part of the Mobility Restrictions:

• an Allowed CAG list i.e. a list of CAG Identifiers the UE is allowed to access; and
• each entry of the Allowed CAG list may be associated with time validity information containing one or more time periods; and
• optionally, a CAG-only indication whether the UE is only allowed to access 5GS via CAG cells (see TS 38.304 [50] for how the UE identifies whether a cell is a CAG cell);

The HPLMN may configure or re-configure a UE with the above CAG information using the UE Configuration Update procedure for access and mobility management related parameters described in clause 4.2.4.2 of TS 23.502 [3].

The above CAG information is provided by the HPLMN on a per PLMN basis. In a PLMN the UE shall only consider the CAG information provided for this PLMN. The entries of the Allowed CAG list with time validity information are provided to the UE only if the UE indicates support of CAG with validity information.

NOTE 1: CAG information provisioning by an authorized administrator introduced in clause 5.50.3 and clause 4.15.6.3h of TS 23.502 [3] can be leveraged to provide/update CAG information.

NOTE 2: If the UE supports CAG but not CAG with validity information and there are entries of the Allowed CAG list that are associated with time validity information in the subscription data, the CAG Identifier of the corresponding entry in subscription data can be provided to the UE without time validity information when the validity condition is evaluated as true and removed when the evaluation changes to false. It is up to AMF local policy whether to provide such CAG Identifier to the UE. In case the AMF does not support CAG with validity information e.g. in the case of roaming, the UDM provides CAG information to the AMF without entries including time validity information.

When the subscribed CAG information changes, UDM sets a CAG information Subscription Change Indication and sends it to the AMF. The AMF shall provide the UE with the CAG information when the UDM indicates that the CAG information within the Access and Mobility Subscription data has been changed. When AMF receives the indication from the UDM that the CAG information within the Access and Mobility Subscription has changed, the AMF uses the CAG information received from the UDM to update the UE. Once the AMF updates the UE and obtains an acknowledgment from the UE, the AMF informs the UDM that the update was successful and the UDM clears the CAG information Subscription Change Indication flag.

The AMF may update the UE using either the UE Configuration Update procedure after registration procedure is completed, or by including the new CAG information in the Registration Accept or in the Registration Reject or in the Deregistration Request or in the Service Reject.

When the UE is roaming and the Serving PLMN provides CAG information, the UE shall update only the CAG information provided for the Serving PLMN while the stored CAG information for other PLMNs are not updated. When the UE is not roaming and the HPLMN provides CAG information, the UE shall update the CAG information stored in the UE with the received CAG information for all the PLMNs.

The UE shall store the latest available CAG information for every PLMN for which it is provided and keep it stored when the UE is de-registered or switched off, as described in TS 24.501 [47].

The CAG information is only applicable with 5GS.

NOTE 3: CAG information has no implication on whether and how the UE accesses 5GS over non-3GPP access.