Section: 5.1.4.2 Coordination between 5GMM for 3GPP access and EMM with N26 interface
Content: A UE that is not registered shall be in state EMM-DEREGISTERED and state 5GMM-DEREGISTERED for 3GPP access. In N1 mode, upon successful completion of a registration procedure over 3GPP access, the UE operating in single-registration mode shall enter substates 5GMM-REGISTERED.NORMAL-SERVICE or 5GMM-REGISTERED.NON-ALLOWED-SERVICE as described in subclause 5.3.5.2 for 3GPP access and EMM-REGISTERED.NO-CELL-AVAILABLE. The UE shall reset the registration attempt counter for 3GPP access and the attach attempt counter (see 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15]). At inter-system change from S1 mode to N1 mode, the UE shall enter substates 5GMM-REGISTERED.NORMAL-SERVICE or 5GMM-REGISTERED.NON-ALLOWED-SERVICE as described in subclause 5.3.5.2 for 3GPP accessand EMM-REGISTERED.NO-CELL-AVAILABLE and initiate a registration procedure for mobility and periodic registration update over 3GPP access indicating "mobility registration updating" in the 5GS registration type IE of the REGISTRATION REQUEST message (see subclause 5.5.1.3). In S1 mode, upon successful completion of an attach or tracking area updating procedure, the UE operating in single-registration mode shall enter substates 5GMM-REGISTERED.NO-CELL-AVAILABLE for 3GPP access and EMM-REGISTERED.NORMAL-SERVICE. The UE shall reset the registration attempt counter for 3GPP access and the attach attempt counter or tracking area updating attempt counter (see 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15]). At inter-system change from N1 mode to S1 mode when there is no active PDU session for which interworking with EPS is supported as specified in subclause 6.1.4.1, and EMM-REGISTERED without PDN connection is not supported by the UE or the MME, the UE shall enter state 5GMM-DEREGISTERED for 3GPP access and state EMM-DEREGISTERED and then initiate the EPS attach procedure. If EMM-REGISTERED without PDN connection is supported by the UE and the MME, the UE shall enter substates EMM-REGISTERED.NORMAL-SERVICE and 5GMM-REGISTERED.NO-CELL-AVAILABLE for 3GPP access and initiate a tracking area updating procedure. At inter-system change from N1 mode to S1 mode when there is at least one active PDU session for which interworking with EPS is supported as specified in subclause 6.1.4.1, the UE shall enter substates EMM-REGISTERED.NORMAL-SERVICE and 5GMM-REGISTERED.NO-CELL-AVAILABLE for 3GPP access and initiate a tracking area updating procedure (see 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15]).