If both 5GMM and EMM are enabled, a UE, operating in single-registration mode, shall maintain one common registration for 5GMM for 3GPP access and EMM.
Coordination between 5GMM for 3GPP access and EMM for a UE, which is capable of N1 mode and S1 mode and operates in dual-registration mode, is not needed, except as specified in
subclause 4.8.3.
The coordination between 5GMM for 3GPP access and EMM in
subclauses 5.1.4.2 and
5.1.4.3 only applies to the UEs operating in single-registration mode.
Regarding the coordination of
"SIM/USIM considered invalid" and
"USIM considered invalid for 5GS services" between the various mobility management entities see
subclause 5.1.5.
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
TS 24.301).
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
TS 24.301).
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
TS 24.301).
A UE operating in the single-registration mode that is not registered over 3GPP access shall be in state EMM-DEREGISTERED and in state 5GMM-DEREGISTERED for 3GPP access.
In N1 mode, upon successful completion of a registration procedure over 3GPP access, the UE operating in the 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.
At inter-system change from N1 mode to S1 mode in 5GMM-IDLE mode, the UE shall behave as specified in
subclause 4.8.2.3.
In S1 mode, upon successful completion of an attach or tracking area updating procedure, the UE operating in the single-registration mode shall enter substates 5GMM-REGISTERED.NO-CELL-AVAILABLE for 3GPP access and EMM-REGISTERED.NORMAL-SERVICE.
At inter-system change from S1 mode to N1 mode in 5GMM-IDLE mode, the UE operating in the single-registration mode:
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if the UE is registered for normal service in S1 mode, the UE shall enter substates EMM-REGISTERED.NO-CELL-AVAILABLE and 5GMM- REGISTERED.NORMAL-SERVICE for 3GPP access and then initiate the 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); or
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if the UE is registered for emergency bearer services in S1 mode, the UE shall initiate the initial registration for emergency services.