5.4.4a UE MM Core Network Capability handling

The UE MM Core Network Capability is split into the S1 UE network capability (mostly for E-UTRAN access related core network parameters) and the UE 5GMM Core Network Capability (mostly to include other UE capabilities related to 5GCN or interworking with EPS) as defined in TS 24.501 [47] and contains non radio-related capabilities, e.g. the NAS security algorithms, etc. The S1 UE network capability is transferred between all CN nodes at AMF to AMF, AMF to MME, MME to MME and MME to AMF changes. The UE 5GMM Core Network Capability is transferred only at AMF to AMF changes.

In order to ensure that the UE MM Core Network Capability information stored in the AMF is up to date (e.g. to handle the situation when the USIM is moved into a different device while out of coverage and the old device did not send the Detach message; and the cases of inter-RAT Registration Area Update), the UE shall send the UE MM Core Network Capability information to the AMF during the Initial Registration and Mobility Registration Update procedure within the NAS message.

The AMF shall store always the latest UE MM Core Network Capability received from the UE. Any UE MM Core Network Capability that an AMF receives from an old AMF/MME is replaced when the UE provides the UE MM Core Network Capability with Registration signalling.

If the UE's UE MM Core Network Capability information changes (in either CM-CONNECTED or in CM-IDLE state), the UE shall perform a Mobility Registration Update procedure when it next returns to NG-RAN coverage. See clause 4.2.2 of TS 23.502 [3].

The UE shall indicate in the UE 5GMM Core Network Capability if the UE supports:

• Attach in EPC with Request type "Handover" in PDN CONNECTIVITY Request message (clause 5.3.2.1 of TS 23.401 [26]).
• EPC NAS.
• SMS over NAS.
• LCS.
• 5G SRVCC from NG-RAN to UTRAN, as specified in TS 23.216 [88].
• Radio Capabilities Signalling optimisation (RACS).
• Network Slice-Specific Authentication and Authorization (NSSAA) as specified in clause 5.15.10.
• NSSAA over EPC as specified in Annex L of TS 23.502 [3].
• Network Slice Replacement as described in clause 5.15.19.
• Parameters in Supported Network Behaviour for 5G CIoT as described in clause 5.31.2.
• Receiving WUS Assistance Information (E-UTRA) see clause 5.4.9.
• Paging Subgrouping Support Indication (NR) see clause 5.4.12.
• Support of LP-WUS Disabling (see clause 5.4.12a).
• LP-WUS Paging Subgrouping Support Indication, see clause 5.4.12a.
• CAG, see clause 5.30.3.3.
• CAG with validity information (if UE supports CAG), see clause 5.30.3.3.
• Subscription-based restrictions to simultaneous registration of network slices (see clause 5.15.12).
• Support of NSAG (see clause 5.15.14).
• Partial Network Slice support in a RA (see clause 5.15.17).
• Minimization of Service Interruption (MINT), as described in clause 5.40.
• MINT-EPS, as described in clause 4.14 of TS 23.401 [26].

NOTE 1: The MINT capability indicates whether the UE supports Disaster Roaming service in 5GS as described in clause 5.40. The MINT-EPS capability indicates whether the UE supports Disaster Roaming service in EPS as described in clause 4.14 of TS 23.401 [26].

• Equivalent SNPNs (see clause 5.30.2.11).
• Unavailability Period Support, as described in clause 5.4.1.4.
• Support for network reconnection due to RAN timing synchronization status change, see clauses 5.27.1.12 and 5.3.4.4.
• UE Configuration of network-controlled Slice Usage Policy (see clause 5.15.15.2).
• Temporarily available network slices (see clause 5.15.16).
• Support of S-NSSAI location availability information, as described in clause 5.15.18.2.
• Support of network verified UE location over NR NTN (see clause 5.4.11.4).

If a UE operating two or more USIMs, supports and intends to use one or more Multi-USIM features (see clause 5.38) in a PLMN for a USIM, it shall indicate in the UE 5GMM Core Network Capability for this USIM in this PLMN that it supports these one or more Multi-USIM features with the following indications:

• Connection Release Supported.
• Paging Cause Indication for Voice Service Supported.
• Reject Paging Request Supported.
• Paging Restriction Supported.

Otherwise, the UE with the capabilities of Multi-USIM features but does not intend to use them shall not indicate support of these one or more Multi-USIM features.

A UE not operating two or more USIMs shall indicate the Multi-USIM features are not supported.

NOTE 2: It is not necessary for a UE operating two or more USIMs to use Multi-USIM features with all USIMs.