5.2.2.3.3 ATTEMPTING-REGISTRATION

The UE in 3GPP access:

• shall initiate an initial registration procedure on the expiry of timers T3502, T3511 or T3346;
• may initiate an initial registration procedure for emergency services even if timers T3502, T3511 or T3346 are running;

b1) may initiate an initial registration procedure even if timer T3502, T3346 or T3447 is running, if the UE is a UE configured for high priority access in selected PLMN;

b2) may initiate an initial registration procedure even if timer T3502, T3346 is running, if the UE is a UE configured for high priority access in selected SNPN;

• shall initiate an initial registration procedure when entering a new PLMN or SNPN, except if:
• timer T3346 is running and the new PLMN or SNPN is equivalent to the PLMN or SNPN where the UE started timer T3346;
• the PLMN identity of the new cell is in the forbidden PLMN lists;

iii) the SNPN is not an SNPN selected for localized services in SNPN (see 3GPP TS 23.122 [5]), the UE is not to perform initial registration for onboarding services in SNPN, the SNPN identity of the new cell is in the "permanently forbidden SNPNs" list or the "temporarily forbidden SNPNs" list which are, if the MS supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription;

• the SNPN is an SNPN selected for localized services in SNPN (see 3GPP TS 23.122 [5]), the SNPN identity of the new cell is in the "permanently forbidden SNPNs for access for localized services in SNPN" list or the "temporarily forbidden SNPNs for access for localized services in SNPN" list, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription;
• the UE is to perform initial registration for onboarding services in SNPN, the SNPN identity of the new cell is in the "permanently forbidden SNPNs for onboarding services in SNPN" list or the "temporarily forbidden SNPNs for onboarding services in SNPN" list; or
• the current TAI is in one of the lists of 5GS forbidden tracking areas;
• shall initiate an initial registration procedure when the current TAI has changed, if timer T3346 is not running,
• the PLMN identity of the new cell is not in one of the forbidden PLMN lists;
• the SNPN is not an SNPN selected for localized services in SNPN (see 3GPP TS 23.122 [5]), the UE is not to perform initial registration for onboarding services in SNPN, and the SNPN identity of the new cell is in neither the "permanently forbidden SNPNs" list nor the "temporarily forbidden SNPNs" list which are, if the MS supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription;
• the SNPN is an SNPN selected for localized services in SNPN (see 3GPP TS 23.122 [5]) and the SNPN identity of the cell is in neither the "permanently forbidden SNPNs for access for localized services in SNPN" list nor the "temporarily forbidden SNPNs for access for localized services in SNPN" list, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription; or
• the UE is to perform initial registration for onboarding services in SNPN, and the SNPN identity of the cell is in neither the "permanently forbidden SNPNs for onboarding services in SNPN" list nor the "temporarily forbidden SNPNs for onboarding services in SNPN" list;

and the current TAI is not in one of the lists of 5GS forbidden tracking areas;

• shall initiate an initial registration procedure if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running;
• may initiate an initial registration procedure for UE in NB-N1 mode upon receiving a request from upper layers to transmit user data related to an exceptional event and the UE is allowed to use exception data reporting (see the ExceptionDataReportingAllowed leaf of the NAS configuration MO in 3GPP TS 24.368 [17]) or the USIM file EFNASCONFIG in 3GPP TS 31.102 [22]) if timer T3346 is not already running for "MO exception data" and even if timer T3502 or timer T3511 is running;
• may initiate an initial registration procedure with 5GS registration type IE set to "initial registration" for initiating of an emergency PDU session, upon request of the upper layers to establish the emergency PDU session; and
• if the UE supports faster service recovery, is configured for faster service recovery in N1 mode as defined in the FasterRecovery leaf of the NAS configuration MO in 3GPP TS 24.368 [17] and the entry into this state was caused by the abnormal case d1 or e defined in clause 5.5.1.2.7,
• if the timer T3511 is running, the UE detects the ShortTimerEvent; and the counter of attempts to stop T3511 is less than the MaxNumShortTimerStop:
• the UE may initiate the initial registration procedure and increment the counter of attempts to stop T3511; and
• if the timer T3502 is running, the UE detects the LongTimerEvent, the counter of registration while T3502 is running is less than the MaxNumLongTimerReg:
• the UE may re-enable the N1 mode capability, initiate the initial registration procedure and increment the counter of attempts to register while T3502 is running.

NOTE 1: When the counter of attempts to stop T3511 and the counter of attempts to register while T3502 is running reach their maximum value, the UE follows the behaviour as if the UE is not configured with fast service recovery.

The UE in non-3GPP access:

• shall initiate an initial registration procedure on the expiry of timers T3502, T3511 or T3346;
• may initiate an initial registration procedure for emergency services even if timers T3502, T3511 or T3346 are running;

b1) may initiate an initial registration procedure even if timer T3502 or T3346 is running if the UE is a UE configured for high priority access in selected PLMN;

• shall initiate an initial registration procedure when entering a new PLMN or SNPN, except if timer T3346 is running and the new PLMN or SNPN is equivalent to the PLMN or SNPN where the UE started timer T3346;
• shall initiate an initial registration procedure if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running; and
• may initiate an initial registration procedure with 5GS registration type IE set to "initial registration" for initiating of an emergency PDU session, upon request of the upper layers to establish the emergency PDU session.