Section: 5.11.3 UE Core Network Capability
Content: The UE Core Network Capability is split into the UE Network Capability IE (mostly for E-UTRAN access related core network parameters) and the MS Network Capability IE (mostly for UTRAN/GERAN access related core network parameters) and contains capabilities, e.g. for CIoT, NAS/AS security algorithms (that also indicate support for EPS-UPIP), etc. Both the UE Network Capability and the MS Network Capability are transferred between CN nodes at MME to MME, MME to SGSN, SGSN to SGSN, and SGSN to MME changes. In order to ensure that the UE Core Network Capability information stored in the MME 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 Tracking Area Update), the UE shall send the UE Core Network Capability information to the MME during the Attach and non-periodic Tracking Area Update procedure within the NAS message. The MME shall store always the latest UE Core Network Capability received from the UE. Any UE Core Network Capability that an MME receives from an old MME/SGSN is replaced when the UE provides the UE Core Network Capability with Attach and the Tracking Area Update signalling. The MME shall remove the stored MS Network Capability, if MS Network Capability is not included in Attach or non-periodic Tracking Area Update signalling e.g. UE is only capable of E-UTRAN. If the UE's UE Core Network Capability information changes (in either ECM-CONNECTED or in ECM-IDLE state (including cases of being in GERAN/UTRAN coverage and having ISR activated)), the UE shall perform a Tracking Area Update ('type' different to 'periodic') when it next returns to E-UTRAN coverage - see clause 5.3.3.0. If the UE supports multiple user plane radio bearers on the NB-IoT RAT (see TS 36.306[ Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio access capabilities ]  [82], TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [37]), then the UE shall indicate this in the UE Network Capability IE. If the UE supports, the RACS feature defined in clause 5.11.3a, and in this specification for the impact on the EPS procedures, then the UE shall indicate this in the UE Network Capability IE. If the UE supports dual connectivity with NR (see clause 4.3.2a), then the UE shall indicate its support in a NAS indicator. If the UE supports Service Gap Control (see clause 4.3.17.9), then the UE shall indicate this in the UE Network Capability IE. If a UE operating two or more USIMs, supports and intends to use one or more Multi-USIM features (see clause 4.3.33) in a PLMN, it shall indicate in the UE Core Network Capability for this USIM in this PLMN that it supports these one or more Multi-USIM features, i.e. by means of one or more of the Connection Release Supported, Paging Cause Indication for Voice Service Supported, Reject Paging Request Supported, Paging Timing Collision Control Supported, and Paging Restriction Supported. Otherwise, the UE with the capabilities of Multi-USIM features shall indicate these one or more Multi-USIM features are not supported. A UE not operating two or more USIMs shall indicate the Multi-USIM features are not supported. NOTE: It is not necessary for a UE operating two or more USIMs to use Multi-USIM features with all USIMs. If the UE supports Enhanced support of discontinuous network coverage for satellite access (see clause 4.3.18.1), then the UE shall indicate this in the UE Network Capability IE. To allow for the addition of future features, the MME shall store the UE Network Capability and the MS Network Capability even if either or both is larger than specified in TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  [47]/TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [46], up to a maximum size of 32 octets for each IE.