Section: 5.2.3.2.3 ATTEMPTING-REGISTRATION-UPDATE
Content: The UE in 3GPP access: a) shall not send any user data; b) shall initiate a registration procedure for mobility and periodic registration update on the expiry of timers T3502, T3511, T3346 or discontinuous coverage maximum time offset timer; c) shall initiate a registration procedure for mobility and periodic registration update when entering a new PLMN or SNPN, if timer T3346 is running and the new PLMN or SNPN is not equivalent to the PLMN or SNPN where the UE started timer T3346, the PLMN identity of the new cell is not in the forbidden PLMN lists, and the current TAI is not in one of the lists of 5GS forbidden tracking areas; d) shall initiate a registration procedure for mobility and periodic registration update when the current TAI has changed, if timer T3346 is not running: i) the PLMN identity of the new cell is not in one of the forbidden PLMN lists; ii) if the SNPN is not an SNPN selected for localized services in SNPN (see 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]), 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 UE 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 or iii) if the SNPN is an SNPN selected for localized services in SNPN (see 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]), the SNPN identity of the new 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; and the current TAI is not in one of the lists of 5GS forbidden tracking areas; e) may initiate a registration procedure for mobility and periodic registration update upon request of the upper layers to establish an emergency PDU session or perform emergency service fallback; e1) may initiate a registration procedure for mobility and periodic registration update upon request of the upper layers to establish a PDU session, even if timer T3502, T3346 or T3447 is running, if the UE is a UE configured for high priority access in the selected PLMN; e2) may initiate a registration procedure for mobility and periodic registration update upon request of the upper layers to establish a PDU session, even if timer T3502, T3346 is running, if the UE is a UE configured for high priority access in selected SNPN; f) may perform de-registration locally and initiate a registration procedure for initial registration for emergency services even if timer T3346 is running; g) shall initiate registration procedure for mobility and periodic registration update upon reception of paging, or upon reception of NOTIFICATION message with access type indicating 3GPP access; NOTE: As an implementation option, the MUSIM UE is allowed to not respond to paging based on the information available in the paging message, e.g. voice service indication. h) may initiate a registration procedure for mobility and periodic registration update upon request for an MMTEL voice call, MMTEL video call, or an MO IMS registration related signalling from the upper layers, and none of the following conditions is met: 1) timer T3346 is running; 2) the UE has stored a list of "non-allowed tracking areas" and the current TAI is in the list of "non-allowed tracking areas"; or 3) the UE has stored a list of "allowed tracking areas", the UE is camped on a cell which is in the registered PLMN, a PLMN from the list of equivalent PLMNs, or the registered SNPN, and the current TAI is not in the list of "allowed tracking areas"; i) shall initiate a registration procedure for mobility and periodic registration update if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running; j) if configured for eCall only mode as specified in 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [22], shall perform the eCall inactivity procedure at expiry of timer T3444 or timer T3445 (see subclause 5.5.3); k) may initiate a registration procedure for mobility and periodic registration update 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[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [17]) or the USIM file EFNASCONFIG in 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [22]) if timer T3346 is not already running for "MO exception data" and even if timer T3502 or timer T3511 is running; l) shall not initiate the de-registration signalling procedure unless the current TAI is part of the TAI list ; and m) shall initiate a registration procedure for mobility and periodic registration update if the UE supports the reconnection to the network due to RAN timing synchronization status change and receives an indication of a change in the RAN timing synchronization status, even if timer T3502 is running. The UE in non-3GPP access: a) shall not send any user data; b) shall initiate the registration procedure for mobility and periodic registration update on the expiry of timers T3502, T3511 or T3346; c) may initiate a registration procedure for mobility registration update upon request of the upper layers to establish an emergency PDU session; c1) may initiate a registration procedure for mobility and periodic registration update upon request of the upper layers to establish a PDU session, if the UE is a UE configured for high priority access in selected PLMN even if timer T3346 or T3502 is running; d) may perform de-registration locally and initiate a registration procedure for initial registration for emergency services even if timer T3346 is running; e) may initiate a registration procedure for mobility and periodic registration update upon request for an MMTEL voice call, MMTEL video call, or an MO IMS registration related signalling from the upper layers, if timer T3346 is not running; f) shall initiate a registration procedure for mobility and periodic registration update if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running; and g) shall not initiate the de-registration signalling procedure unless timer T3346 is running.