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Content for  TS 24.501  Word version:  18.2.1

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5.3.19 Handling of congestion control for transport of user data via the control plane  5.3.19a Specific requirements for UE configured to use timer T3245  5.3.20 Specific requirements for UE when receiving non-integrity protected reject messages  5.3.21 CIoT 5GS optimizations  5.3.22 Interaction between MICO mode with active time and extended idle mode DRX cycle  5.3.23 Forbidden wireline access area  5.3.24 WUS assistance  5.3.25 Paging Early Indication with Paging Subgrouping Assistance  5.3.26 Support for unavailability period 
...

 

5.3.19  Handling of congestion control for transport of user data via the control plane |R16|  p. 187

The network may activate congestion control for transport of user data via the control plane, as specified in TS 23.501.
If the UE has indicated support for the control plane CIoT 5GS optimizations and the network decides to activate the congestion control for transport of user data via the control plane, the network may include a value for the control plane data back-off timer T3448 in REGISTRATION ACCEPT, SERVICE ACCEPT or SERVICE REJECT message, and shall store an control plane data back-off time on a per UE basis. The UE starts the timer T3448 with the value informed in the message. To avoid that large numbers of UEs simultaneously initiate deferred requests, the network should select the value for the timer T3448 for the informed UEs so that timeouts are not synchronised.
The network sends REGISTRATION ACCEPT message or SERVICE ACCEPT message without T3448 value IE to stop the timer T3448 running in the UE as specified in subclause 5.5.1.3.4 and subclause 5.6.1.4.
Based on the stored control plane data back-off time for the UE, the network may reject the transfer of user data via the control plane initiated by the UE.
While the timer T3448 is running, the UE in 5GMM-IDLE mode does not initiate the transport of user data via the control plane procedure, except if the UE is allowed to use exception data reporting (see the ExceptionDataReportingAllowed leaf of the NAS configuration MO in TS 24.368 or the USIM file EFNASCONFIG in TS 31.102) and the user data is related to an exceptional event.
The UE is allowed:
  1. to respond to paging with CONTROL PLANE SERVICE REQUEST message without uplink data; or
  2. to send a CONTROL PLANE SERVICE REQUEST message for emergency services or for emergency services fallback;
even if the timer T3448 is running.
Upon entering the state 5GMM-DEREGISTERED or a new PLMN which is not equivalent to the PLMN where the UE started the timer T3448, or upon being switched off while the timer T3448 is running, the UE stops the timer T3448.
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5.3.19a  Specific requirements for UE configured to use timer T3245 |R16|  p. 188

5.3.19a.1  UE not operating in SNPN access operation mode  p. 188

The following requirements apply for a UE that is configured to use timer T3245 (see TS 24.368 or TS 31.102).
When the UE adds a PLMN identity to the "forbidden PLMN list" or sets the USIM as invalid for 5GS services for 3GPP access or non-3GPP access, and timer T3245 (see TS 24.008) is not running, the UE shall start timer T3245 as specified in subclause 4.1.1.6 of TS 24.008.
Upon expiry of the timer T3245, the UE shall erase the "forbidden PLMN list" and "forbidden PLMNs for GPRS service" list and set the USIM to valid for 5GS services for 3GPP access and non-3GPP access. When the lists are erased, the UE performs cell selection according to TS 38.304 or TS 36.304.
If the UE is switched off when the timer T3245 is running, the UE shall behave as follows when the UE is switched on and the USIM in the UE remains the same:
  • let t1 be the time remaining for T3245 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the UE will follow the behaviour as defined in the paragraph above upon expiry of the timer T3245. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1.
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5.3.19a.2  UE operating in SNPN access operation mode  p. 188

The following requirements apply for a UE that is configured to use timer T3245 (see TS 24.368).
When the UE adds an SNPN to the "permanently forbidden SNPNs" list or "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, or sets the selected entry of the "list of subscriber data" or the selected PLMN subscription as invalid for 3GPP access or non-3GPP access, and timer T3245 (see TS 24.008) is not running, the UE shall start timer T3245 with a random value, uniformly drawn from the range between 12h and 24h.
Upon expiry of the timer T3245, the UE shall erase the "permanently forbidden SNPNs" list(s) and "temporarily forbidden SNPNs" list(s) and set the selected entry of the "list of subscriber data" or the selected PLMN subscription to valid for 3GPP access and non-3GPP access. When the lists are erased, the UE performs cell selection according to TS 38.304.
If the UE is switched off when the timer T3245 is running, the UE shall behave as follows when the UE is switched on and the selected entry of the "list of subscriber data" or the selected PLMN subscription remain the same:
  • let t1 be the time remaining for T3245 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the UE will follow the behaviour as defined in the paragraph above upon expiry of the timer T3245. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1.
    • Up

    5.3.20  Specific requirements for UE when receiving non-integrity protected reject messages |R16|  p. 188

    5.3.20.1  General  p. 188

    This subclause specifies the requirements for a UE that is not configured to use timer T3245 (see TS 24.368 or TS 31.102) and receives a REGISTRATION REJECT or SERVICE REJECT message without integrity protection with specific 5GMM causes.
    Up

    5.3.20.2  Requirements for UE in a PLMN  p. 189

    The UE shall maintain:
    • a list of PLMN-specific attempt counters (see TS 24.301). The maximum number of possible entries in the list is implementation dependent. This list is applicable to access attempts via 3GPP access only;
    • a list of PLMN-specific attempt counters for non-3GPP access, if the UE supports non-3GPP access. The maximum number of possible entries in the list is implementation dependent. This list is applicable to access attempts via non-3GPP access only;
    • a list of PLMN-specific N1 mode attempt counters for 3GPP access. The maximum number of possible entries in the list is implementation dependent. This list is applicable to access attempts via 3GPP access only;
    • a list of PLMN-specific N1 mode attempt counters for non-3GPP access, if the UE supports non-3GPP access. The maximum number of possible entries in the list is implementation dependent. This list is applicable to access attempts via non-3GPP access only;
    • one counter for "SIM/USIM considered invalid for GPRS services" events (see TS 24.008);
    • one counter for "USIM considered invalid for 5GS services over non-3GPP access" events, if the UE supports non-3GPP access; and
    • a list of PLMN-specific attempt counters for the determined PLMN with disaster condition, if the UE supports MINT. The maximum number of possible entries in the list is implementation dependent. This list is applicable to access attempts via 3GPP access only.
    A UE supporting non-EPS services shall maintain one counter for "SIM/USIM considered invalid for non-GPRS services" events (see TS 24.008).
    The UE shall store the above lists of attempt counters and the event counters in its non-volatile memory. The UE shall erase the lists and reset the event counters to zero when the UICC containing the USIM is removed. The counter values shall not be affected by the activation or deactivation of MICO mode or power saving mode (see TS 24.301).
    The UE implementation-specific maximum value for any of the above counters shall not be greater than 10.
    If the UE receives a REGISTRATION REJECT or SERVICE REJECT message without integrity protection with 5GMM cause value #3, #6, #7, #11, #12, #13, #15, #27, #31, #62, #72, #73 or #80 before the network has established secure exchange of NAS messages for the N1 NAS signalling connection, the UE shall stop timer T3510 or T3517 if running, and start timer T3247 (see TS 24.008) with a random value uniformly drawn from the range between 30 minutes and 60 minutes, if the timer is not running, and take the following actions:
    1. if the 5GMM cause value received is #3, #6 or #7, and:
      1. if the 5GMM cause value is received over 3GPP access, the UE shall:
        1. if the UE is already registered over another access:
          • store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
          • search for a suitable cell in another tracking area according to TS 38.304 or TS 36.304; or
        2. otherwise, if the counter for "SIM/USIM considered invalid for GPRS services" events has a value less than a UE implementation-specific maximum value,
          • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete 5G-GUTI, last visited registered TAI, TAI list and ngKSI for 3GPP access;
          • if the 5GMM cause value received is #3 or #6, delete the list of equivalent PLMNs if any;
          • increment the counter for "SIM/USIM considered invalid for GPRS services" events;
          • if the 5GMM cause value received is #3 or #6, and if the counter for "SIM/USIM considered invalid for non-GPRS services" events has a value less than a UE implementation-specific maximum value, increment the counter;
          • if a registration procedure was performed, reset the registration attempt counter and if a service request procedure was performed, reset the service request attempt counter;
          • if the UE is operating in single-registration mode, handle the EMM parameters EMM state, EPS update status, EPS attach attempt counter, tracking area updating attempt counter or service request attempt counter, 4G-GUTI, TAI list, eKSI as specified in TS 24.301 for the case when the EPS attach, tracking area updating procedure or service request procedure is rejected with the EMM cause of the same value in a NAS message without integrity protection;
          • store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
          • search for a suitable cell in another tracking area according to TS 38.304 or TS 36.304; and as a UE implementation option, the UE may perform registration attempt over the non-3GPP access, if non-3GPP access is available, and the USIM is not considered invalid for 5GS services over non-3GPP access; and
        3. otherwise proceed as specified in subclauses 5.5.1 and 5.6.1;
      2. if the 5GMM cause value is received over non-3GPP access, the UE shall:
        1. if the UE is already registered over another access:
          • enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
          • may perform registration attempt over the non-3GPP access if another access point for non-3GPP access is available; or
        2. otherwise, if the counter for "USIM considered invalid for 5GS services over non-3GPP access" events has a value less than a UE implementation-specific maximum value,
          • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete the 5G-GUTI, last visited registered TAI, TAI list and ngKSI for non-3GPP access;
          • enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE;
          • increment the counter for "USIM considered invalid for 5GS services over non-3GPP access" events; and as a UE implementation option, the UE may either perform registration attempt over the non-3GPP access if another access point for non-3GPP access is available, or if 3GPP access is available, and the SIM/USIM is not considered invalid for 5GS services over 3GPP access, perform registration attempt over the 3GPP access; and
        3. otherwise proceed as specified in subclauses 5.5.1 and 5.6.1;
    2. if the 5GMM cause value received is #12, #13 or #15, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally, the UE may:
      1. if the 5GMM cause value is received over 3GPP access, non-3GPP access is available, the UE is not registered over non-3GPP access yet, and the USIM is not considered invalid for 5GS services over non-3GPP access, perform registration attempt over the non-3GPP access; or
      2. if the 5GMM cause value is received over non-3GPP access, 3GPP access is available, the UE is not registered over 3GPP access yet, and the USIM is not considered invalid for 5GS services over 3GPP access, perform registration attempt over the 3GPP access;
    3. if the 5GMM cause value received is #11 or #73 and the UE is in its HPLMN or EHPLMN:
      1. if the 5GMM cause value is received over 3GPP access, the UE shall:
        • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete, the 5G-GUTI, last visited registered TAI, TAI list, ngKSI for 3GPP access and the list of equivalent PLMNs. Additionally, if a registration procedure was performed, the UE shall reset the registration attempt counter and if a service request procedure was performed, reset the service request attempt counter;
        • if the 5GMM cause value received is #11 and the UE is operating in single-registration mode, handle the EMM parameters EMM state, EPS update status, EPS attach attempt counter, tracking area updating attempt counter or service request attempt counter, 4G-GUTI, TAI list, eKSI as specified in TS 24.301 for the case when the EPS attach, tracking area updating procedure or service request procedure is rejected with the EMM cause of the same value in a NAS message without integrity protection;
        • if the 5GMM cause value received is #73 and the UE is operating in single-registration mode, the UE shall in addition set the EPS update status to EU3 ROAMING NOT ALLOWED and shall delete any 4G-GUTI, last visited registered TAI, TAI list and eKSI. Additionally, the UE shall reset the attach attempt counter or tracking area updating attempt counter, and enter the state EMM-DEREGISTERED;
        • store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
        • search for a suitable cell in another tracking area according to TS 38.304 or TS 36.304; and as a UE implementation option, the UE may perform registration attempt over the non-3GPP access, if non-3GPP access is available, the UE is not registered over non-3GPP access yet, and the USIM is not considered invalid for 5GS services over non-3GPP access;
      2. if the 5GMM cause value is received over non-3GPP access, the UE shall:
        • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete the 5G-GUTI, last visited registered TAI, TAI list and ngKSI for non-3GPP access. Additionally, if a registration procedure was performed, the UE shall reset the registration attempt counter and if a service request procedure was performed, reset the service request attempt counter; and
        • enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE. As a UE implementation option, the UE may perform registration attempt over the non-3GPP access if another access point for non-3GPP access is available, or if 3GPP access is available, the UE is not registered over 3GPP access yet, and the USIM is not considered invalid for 5GS services over 3GPP access, perform registration attempt over the 3GPP access;
    4. if the 5GMM cause value received is #11 or #73 and the UE is not in its HPLMN or EHPLMN, in addition to the UE requirements specified in subclause 5.5.1 and 5.6.1:
      • if the message was received via 3GPP access and if the PLMN-specific attempt counter for the PLMN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment the PLMN-specific attempt counter for the PLMN; or
      • if the message was received via non-3GPP access and if the PLMN-specific attempt counter for non-3GPP access for the PLMN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment the PLMN-specific attempt counter for non-3GPP access for the PLMN;
    5. if the 5GMM cause value received is #27, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally, if the PLMN-specific N1 mode attempt counter for the respective access type and for the PLMN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment this counter for the PLMN;
    6. if the 5GMM cause value received is #72, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally, if the PLMN-specific N1 mode attempt counter for non-3GPP access for the PLMN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment this counter for the PLMN;
    7. if the 5GMM cause value received is #31 for a UE that has indicated support for CIoT optimizations, the UE may discard the message or alternatively the UE should:
      • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2);
      • store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message; and
      • search for a suitable cell in another tracking area according to TS 38.304 or TS 36.304; and
    8. if the 5GMM cause value received is #62, the UE may discard the message or alternatively the UE should:
      • set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2);
      • store the current TAI in the list of "5GS forbidden tracking areas for roaming", memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for non-integrity protected NAS reject message; and
      • search for a suitable cell in another tracking area according to TS 38.304 or TS 36.304.
    9. if the 5GMM cause value received is #80, the UE shall proceed as specified in subclauses 5.5.1. If the PLMN-specific attempt counter of the PLMN which sent the reject message for the determined PLMN with disaster condition has a value less than a UE implementation-specific maximum value, the UE shall increment the PLMN-specific attempt counter of the PLMN which sent the reject message for the determined PLMN with disaster condition.
    Upon expiry of timer T3247, the UE shall:
    • remove all tracking areas from the list of "5GS forbidden tracking areas for regional provision of service" and the list of "5GS forbidden tracking areas for roaming", which were stored in these lists for non-integrity protected NAS reject message;
    • set the USIM to valid for 5GS services for 3GPP access, if:
      • the counter for "SIM/USIM considered invalid for GPRS services" events has a value less than a UE implementation-specific maximum value;
    • set the USIM to valid for 5GS services for non-3GPP access, if:
      • the counter for "USIM considered invalid for 5GS services over non-3GPP access" events has a value less than a UE implementation-specific maximum value;
    • set the USIM to valid for non-EPS services, if:
      • the counter for "SIM/USIM considered invalid for non-GPRS services" events has a value less than a UE implementation-specific maximum value;
    • for each PLMN-specific attempt counter that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the extension of the "forbidden PLMNs" list;
    • for each PLMN-specific attempt counter for non-3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of "forbidden PLMNs for non-3GPP access to 5GCN";
    • re-enable the N1 mode capability for 3GPP access and, for each PLMN-specific N1 mode attempt counter for 3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of PLMNs where N1 mode is not allowed for 3GPP access (see TS 23.122);
    • re-enable the N1 mode capability for non-3GPP access and, for each PLMN-specific N1 mode attempt counter for non-3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective PLMN from the list of PLMNs where N1 mode is not allowed for non-3GPP access;
    • if the UE is supporting A/Gb mode or Iu mode, perform the actions as specified in TS 24.008 for the case when timer T3247 expires;
    • if the UE is supporting S1 mode, perform the actions as specified in TS 24.301 for the case when timer T3247 expires;
    • initiate a registration procedure, if still needed, dependent on 5GMM state and 5GS update status, or perform PLMN selection according to TS 23.122; and
    • for each PLMN-specific attempt counter of the PLMN which sent the reject message for the determined PLMN with disaster condition that has a value greater than zero and less than a UE implementation-specific maximum value, consider the PLMN which sent the reject message is available for disaster roaming service for the respective determined PLMN with disaster condition.
    When the UE is switched off, the UE shall, for each PLMN-specific attempt counter that has a value greater than zero and less than the UE implementation-specific maximum value, remove the respective PLMN from the list of "forbidden PLMNs". When the USIM is removed, the UE should perform this action.
    When the UE is switched off, the UE shall, for each PLMN-specific attempt counter for non-3GPP access that has a value greater than zero and less than the UE implementation-specific maximum value, remove the respective PLMN from the list of "forbidden PLMNs for non-3GPP access to 5GCN". When the USIM is removed, the UE should perform this action.
    When the UE is switched off, the UE shall, for each PLMN-specific attempt counter of the PLMN which sent the reject message for the determined PLMN with disaster condition that has a value greater than zero and less than the UE implementation-specific maximum value, consider the PLMN is available for disaster roaming service for the respective determined PLMN with disaster condition. When the USIM is removed, the UE should perform this action.
    Up

    5.3.20.3  Requirements for UE in an SNPN  p. 193

    If the UE is operating in SNPN access operation mode, the UE shall maintain, for each of the entries in the "list of subscriber data":
    • one SNPN-specific attempt counter for 3GPP access. The counter is applicable to access attempts via 3GPP access only;
    • one SNPN-specific attempt counter for non-3GPP access, if the UE supports access to SNPN over non-3GPP access. The counter is applicable in case of access to SNPN over non-3GPP access only;
    • one counter for "the entry for the current SNPN considered invalid for 3GPP access" events; and
    • one counter for "the entry for the current SNPN considered invalid for non-3GPP access" events, if the UE supports access to SNPN over non-3GPP access. The counter is applicable in case of access to SNPN over non-3GPP access only.
    The UE shall store the above counters in its non-volatile memory. The UE shall erase the attempt counters and reset the event counters to zero when the selected entry of the "list of subscriber data" is updated or USIM is removed for the selected PLMN subscription. The counter values shall not be affected by the activation or deactivation of MICO mode or power saving mode (see TS 24.301).
    The UE implementation-specific maximum value for any of the above counters shall not be greater than 10.
    If the UE receives a REGISTRATION REJECT or SERVICE REJECT message without integrity protection with 5GMM cause value #3, #6, #7, #12, #13, #15, #27, #72, #74, or #75 before the network has established secure exchange of NAS messages for the N1 NAS signalling connection, the UE shall stop timer T3510 or T3517, if running, and start timer T3247 (see TS 24.008) with a random value uniformly drawn from the range between:
    1. 15 minutes and 30 minutes for 5GMM cause value #74; or
    2. 30 minutes and 60 minutes for other 5GMM cause values;
    if the timer is not running, and take the following actions:
    a.
    if the 5GMM cause value received is #3, #6, or #7 and the UE is neither registered for onboarding services in SNPN nor performing initial registration for onboarding services in SNPN:
    1.
    if the 5GMM cause value is received over 3GPP access:
    i.
    if the UE is already registered over another access, the UE shall:
    1. store the current TAI in the list of "5GS forbidden tracking areas for roaming" for the current SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both the selected entry of the "list of subscriber data" or the selected PLMN subscription, memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for the current SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, the selected entry of the "list of subscriber data" or the selected PLMN subscription, for non-integrity protected NAS reject message and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
    2. search for a suitable cell in another tracking area according to TS 38.304; or
    ii.
    otherwise if the counter for "the entry for the current SNPN considered invalid for 3GPP access" events has a value less than a UE implementation-specific maximum value, the UE shall:
    A.
    set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete 5G-GUTI, last visited registered TAI, TAI list, and ngKSI for 3GPP access;
    A1.
    if the 5GMM cause value received is #3 or #6, delete the list of equivalent SNPNs, if any;
    B.
    increment the counter for "the entry for the current SNPN considered invalid for 3GPP access" events;
    C.
    reset the registration attempt counter in case of a REGISTRATION REJECT message or reset the service request attempt counter in case of a SERVICE REJECT message;
    D.
    store the current TAI in the list of "5GS forbidden tracking areas for roaming" for the current SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, the selected entry of the "list of subscriber data" or the selected PLMN subscription, memorize the current TAI was stored in the list of "5GS forbidden tracking areas for roaming" for the current SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, the selected entry of the "list of subscriber data" or the selected PLMN subscription, for non-integrity protected NAS reject message, and enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
    E.
    search for a suitable cell in another tracking area according to TS 38.304. As a UE implementation option, if access to SNPN over non-3GPP access is available and the selected entry of the "list of subscriber data" or the selected PLMN subscription is not considered invalid for non-3GPP access, then the UE may perform registration attempt over non-3GPP access; or
    iii.
    otherwise, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1;
    2.
    if the 5GMM cause value is received over non-3GPP access:
    1. if the UE is already registered over another access, the UE shall enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; or
    2. otherwise if the counter for "the entry for the current SNPN considered invalid for non-3GPP access" events has a value less than a UE implementation-specific maximum value, the UE shall:
      1. set the 5GS update status to 5U3 ROAMING NOT ALLOWED (and shall store it according to subclause 5.1.3.2.2) and shall delete the 5G-GUTI, last visited registered TAI, TAI list, and ngKSI for non-3GPP access;
      2. enter the state 5GMM-DEREGISTERED.LIMITED-SERVICE; and
      3. increment the counter for "the entry for the current SNPN considered invalid for non-3GPP access" events. As a UE implementation option, if 3GPP access is available and the selected entry of the "list of subscriber data" or the selected PLMN subscription is not considered invalid for 3GPP access, then the UE may make a registration attempt over 3GPP access; or
    3. otherwise, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1;
    b.
    if the 5GMM cause value received is #12, #13, or #15, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally:
    1. if the 5GMM cause value is received over 3GPP access, access to SNPN over non-3GPP access is available, the UE is not registered over non-3GPP access yet, and the selected entry of the "list of subscriber data" or the selected PLMN subscription is not considered invalid for non-3GPP access, the UE may perform registration attemptover non-3GPP access; or
    2. if the 5GMM cause value is received over non-3GPP access, 3GPP access is available, the UE is not registered to the current SNPN over 3GPP access yet, and the selected entry of the "list of subscriber data" or the selected PLMN subscription is not considered invalid for 3GPP access, the UE may make a registration attempt over 3GPP access;
    c.
    if the 5GMM cause value received is #27, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally, if the SNPN-specific attempt counter for the respective access type and for the current SNPN has a value less than a UE implementation-specific maximum value, the UE shall increment this counter for the SNPN;
    c1.
    if the 5GMM cause value received is #72, the UE shall proceed as specified in subclauses 5.5.1 and 5.6.1. Additionally, if the SNPN-specific attempt counter for non-3GPP access for the current SNPN has a value less than a UE implementation-specific maximum value, the UE shall increment this counter for the SNPN; and
    d.
    if:
    1. the 5GMM cause value received is #74 or #75; or
    2. the 5GMM cause value received is #3, #6, or #7 and the UE is registered for onboarding services in SNPN or performing initial registration for onboarding services in SNPN;
    in addition to the UE requirements specified in subclauses 5.5.1 and 5.6.1:
    1. if the message was received via 3GPP access and if the SNPN-specific attempt counter for 3GPP access for the SNPN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment the SNPN-specific attempt counter for 3GPP access for the SNPN; or
    2. if the message was received via non-3GPP access and if the SNPN-specific attempt counter for non-3GPP access for the SNPN sending the reject message has a value less than a UE implementation-specific maximum value, the UE shall increment the SNPN-specific attempt counter for non-3GPP access for the SNPN.
    Upon expiry of timer T3247, the UE shall:
    • remove, for each SNPN, all tracking areas from the list of "5GS forbidden tracking areas for regional provision of service" and the list of "5GS forbidden tracking areas for roaming" for the SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, the selected entry of the "list of subscriber data" or the selected PLMN subscription, which were stored in these lists for non-integrity protected NAS reject message;
    • set each entry of the "list of subscriber data" or the PLMN subscription to valid for 3GPP access, if the corresponding counter for "the entry for the current SNPN considered invalid for 3GPP access" events has a value less than a UE implementation-specific maximum value;
    • set each entry of the "list of subscriber data" or the PLMN subscription to valid for non-3GPP access, if the corresponding counter for "the entry for the current SNPN considered invalid for non-3GPP access" events has a value less than a UE implementation-specific maximum value;
    • remove each SNPN identity from the "permanently forbidden SNPNs" list for 3GPP access or "temporarily forbidden SNPNs" list for 3GPP access 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, if the corresponding SNPN-specific attempt counter for 3GPP access has a value greater than zero and less than a UE implementation-specific maximum value and the SNPN identity is included in any of the "permanently forbidden SNPNs" list for 3GPP access or "temporarily forbidden SNPNs" list for 3GPP access;
    • remove each SNPN identity from the "permanently forbidden SNPNs" list for non-3GPP access or "temporarily forbidden SNPNs" list for non-3GPP access 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, if the corresponding SNPN-specific attempt counter for non-3GPP access has a value greater than zero and less than a UE implementation-specific maximum value and the SNPN identity is included in any of the "permanently forbidden SNPNs" list for non-3GPP access or "temporarily forbidden SNPNs" list for non-3GPP access;
    • re-enable the N1 mode capability for 3GPP access and, for each SNPN-specific attempt counter for 3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective SNPN from the list of SNPNs for which the N1 mode capability was disabled due to receipt of a reject from the network with 5GMM cause #27 "N1 mode not allowed" (see TS 23.122);
    • re-enable the N1 mode capability for non-3GPP access and, for each SNPN-specific attempt counter for non-3GPP access that has a value greater than zero and less than a UE implementation-specific maximum value, remove the respective SNPN from the list of SNPNs for which N1 mode capability was disabled for non-3GPP access due to receipt of a reject from the network with 5GMM cause #27 "N1 mode not allowed" or 5GMM cause #72 "non-3GPP access to 5GCN not allowed"; and
    • initiate a registration procedure, if still needed, dependent on 5GMM state and 5GS update status, or perform SNPN selection according to TS 23.122.
    When the UE is switched off or a UICC containing the USIM is removed:
    • for each SNPN-specific attempt counter for 3GPP access having a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the respective SNPN identity from the "permanently forbidden SNPNs" list(s) for 3GPP access or "temporarily forbidden SNPNs" list(s) for 3GPP access, if available; and
    • for each SNPN-specific attempt counter for non-3GPP access having a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the respective SNPN identity from the "permanently forbidden SNPNs" list(s) for non-3GPP access or "temporarily forbidden SNPNs" list(s) for non-3GPP access, if available.
    When an entry of the "list of subscriber data" is updated:
    • if the UE does not support access to an SNPN using credentials from a credentials holder and equivalent SNPNs, and the SNPN-specific attempt counter for 3GPP access for the SNPN corresponding to the entry has a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the SNPN identity corresponding to the entry from the "permanently forbidden SNPNs" list for 3GPP access or "temporarily forbidden SNPNs" list for 3GPP access, if available;
    • if the UE does not support access to an SNPN using credentials from a credentials holder and equivalent SNPNs, and the SNPN-specific attempt counter for non-3GPP access for the SNPN corresponding to the entry has a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the SNPN identity corresponding to the entry from the "permanently forbidden SNPNs" list for non-3GPP access or "temporarily forbidden SNPNs" list for non-3GPP access, if available;
    • if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, and the SNPN-specific attempt counter for 3GPP access for an SNPN in the "permanently forbidden SNPNs" list for 3GPP access or "temporarily forbidden SNPNs" list for 3GPP access, associated with the entry, has a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the SNPN identity corresponding to the SNPN from the "permanently forbidden SNPNs" list for 3GPP access or "temporarily forbidden SNPNs" list for 3GPP access, associated with the entry; and
    • if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, and the SNPN-specific attempt counter for non-3GPP access for an SNPN in the "permanently forbidden SNPNs" list for non-3GPP access or "temporarily forbidden SNPNs" list for non-3GPP access associated with the entry, has a value greater than zero and less than the UE implementation-specific maximum value, the UE shall remove the SNPN identity corresponding to the SNPN from the "permanently forbidden SNPNs" list for non-3GPP access or "temporarily forbidden SNPNs" list for non-3GPP access, associated with the entry.
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    5.3.21  CIoT 5GS optimizations |R16|  p. 197

    CIoT 5GS optimizations provide improved support of small data and SMS transfer. A UE supporting CIoT 5GS optimizations can indicate the 5GS CIoT network behaviour the UE can support and prefers to use during the registration procedure (see TS 23.502). The UE may indicate the support for control plane CIoT 5GS optimization, user plane CIoT 5GS optimization, N3 data transfer and header compression (see subclause 9.11.3.1). Furthermore, the UE may, separately from the indication of support, indicate preference for control plane CIoT 5GS optimization or user plane CIoT 5GS optimization (see subclause 9.11.3.9A). The indication of preference is also considered as the request to use. A UE supporting CIoT EPS optimizations can also indicate the EPS CIoT network behaviour the UE can support during the registration procedure. Furthermore, the UE may, separately from the indication of support, indicate preference for control plane CIoT EPS optimization or user plane CIoT EPS optimization.
    The UE can be in NB-N1 mode or WB-N1 mode when requesting the use of CIoT 5GS optimizations during the registration procedure. A UE in NB-N1 mode always indicates support for control plane CIoT 5GS optimization.
    In NB-N1 mode, the UE, when requesting the use of CIoT 5GS optimizations, does not:
    • request an initial registration for emergency services;
    • request a PDU session establishment for emergency PDU session; or
    • indicate UE's usage setting during the registration procedure.
    The network does not indicate to the UE support of emergency services when the UE is in NB-N1 mode (see subclause 5.5.1.2.4 and 5.5.1.3.4).
    The control plane CIoT 5GS optimization enables support of efficient transport of user data (IP, Ethernet and Unstructured) or SMS messages over control plane via the AMF without triggering user-plane resources establishment. The support of control plane CIoT 5GS optimization is mandatory for the network in NB-N1 mode and optional in WB-N1 mode. Optional header compression of IP data and Ethernet data can be applied to PDU sessions with IP PDU session type and Ethernet PDU session type that are configured to support header compression. For IP header compression, Robust Header Compression (ROHC) protocol specified in RFC 5795 is used. For Ethernet header compression, Ethernet Header Compression (EHC) protocol specified in TS 38.323 is used.
    For a UE that supports Location Services (LCS) notification mechanisms in N1 mode, the control plane CIoT 5GS optimization also enables the transport of location services messages from 5GMM-IDLE mode using the CONTROL PLANE SERVICE REQUEST message when location services are requested (see subclause 6.7.1 in TS 23.273).
    The user plane CIoT 5GS optimization enables support for change from 5GMM-IDLE mode over 3GPP access to 5GMM-CONNECTED mode over 3GPP access without the need for using the service request procedure (see subclause 5.3.1.5).
    If the UE supports user plane CIoT 5GS optimization, it shall also support N3 data transfer.
    If the UE indicates support of one or more CIoT 5GS optimizations and the network supports one or more CIoT 5GS optimizations and decides to accept the registration request, the network indicates the supported CIoT 5GS optimizations to the UE per registration area when accepting the UE request. Network indication of support is interpreted by the UE as the acceptance to use the respective feature. After completion of the registration procedure, the UE and the network can then use the accepted CIoT 5GS optimizations for the transfer of user data (IP, Ethernet, Unstructured and SMS).
    A UE in NB-N1 mode or WB-N1 mode can request the use of SMS over NAS by setting the SMS requested bit of the 5GS update type IE in the REGISTRATION REQUEST message as specified in subclauses 5.5.1.2.2 and 5.5.1.3.2.
    The AMF indicates whether it allows the use of SMS over NAS for a UE in NB-N1 mode or WB-N1 mode by setting the SMS allowed bit of the 5GS registration result IE in the REGISTRATION ACCEPT message as specified in subclauses 5.5.1.2.4 and 5.5.1.3.4.
    If the UE and the network support both the control plane CIoT 5GS optimization and N3 data transfer, then when receiving the UE's request for a PDU session establishment, the AMF decides whether the PDU session should be NEF PDU session or N6 PDU session as specified in TS 23.501 and then:
    1. if NEF PDU session is to be established for unstructured data type, the AMF includes control plane only indication for the requested PDU session to the SMF;
    2. if N6 PDU session is to be established and the DNN or S-NSSAI of the newly requested N6 PDU session supports interworking with EPS as specified in TS 23.502:
      1. if there are existing N6 PDU sessions supporting interworking with EPS for this UE that were established with the control plane only indication, the AMF includes the control plane only indication for the newly requested N6 PDU session to the SMF; or
      2. if there are existing N6 PDU sessions supporting interworking with EPS for this UE that were established without the control plane only indication, the AMF does not include the control plane only indication for the newly requested N6 PDU session to the SMF;
      3. if there is no existing N6 PDU session supporting interworking with EPS for this UE, the AMF determines whether to include the control plane only indication for the newly requested N6 PDU session to the SMF based on local policies, the UE's preferred CIoT network behaviour and the supported CIoT network behaviour; and
    3. if N6 PDU session is to be established and the DNN or S-NSSAI of the N6 PDU session does not support interworking with EPS as specified in TS 23.502, the AMF determines whether to include the control plane only indication for the newly requested N6 PDU session to the SMF based on local policies, the UE's preferred CIoT network behaviour and the supported CIoT network behaviour.
    In NB-N1 mode, if the UE or the network does not support N3 data transfer, then when receiving the UE's request for a PDU session establishment, the AMF decides whether the PDU session should be NEF PDU session or N6 PDU session as specified in TS 23.501 and then includes the control plane only indication for the requested PDU session to the SMF.
    If the network supports user plane CIoT 5GS optimization, it shall also support N3 data transfer.
    Broadcast system information may provide information about support of CIoT 5GS optimizations (see TS 36.331). At reception of new broadcast system information, the lower layers deliver it to the 5GMM layer in the UE. The information provided by lower layers is per PLMN and used by the UE to determine whether certain CIoT 5GS optimizations are supported in the cell.
    The UE shall not attempt to use CIoT 5GS optimizations which are indicated as not supported.
    In NB-N1 mode, at any given time, there cannot be user-plane resources established for a number of PDU sessions that exceeds the UE' s maximum number of supported user-plane resources. The UE in NB-N1 mode shall not:
    1. request the establishment of user-plane resources for a number of PDU sessions that exceeds the UE' s maximum number of supported user-plane resources; or
    2. initiate the establishment of a new PDU session, or request the transfer of a PDU session from the non-3GPP access to the 3GPP access, if:
      1. the UE has indicated preference for user plane CIoT 5GS optimization;
      2. the network accepted the use of user plane CIoT 5GS optimization; and
      3. the UE currently has user-plane resources established fora number of PDU sessions that is equal to the UE' s maximum number of supported user-plane resources.
    The AMF enforces a limit on the number of PDU sessions with active user-plane resources for a UE in NB-N1 mode based on the UE's maximum number of supported user-plane resources as follows:
    1. there can be a maximum of one PDU session with active user-plane resources when the Multiple user-plane resources support bit is set to "Multiple user-plane resources not supported", or
    2. there can be a maximum of two PDU sessions with active user-plane resources when the Multiple user-plane resources support bit is set to "Multiple user-plane resources supported".
    A PDU session for a UE in NB-N1 mode shall only have one QoS rule and that is the default QoS rule. Reflective QoS is not supported in NB-N1 mode. Reflective QoS is not applicable for a PDU session with control plane only indication.
    In NB-N1 mode, when the UE requests the lower layer to establish a RRC connection and the UE requests the use of user plane CIoT 5GS optimization, the UE shall pass an indication of the requested CIoT 5GS optimizations to the lower layers. If the UE requests the use of N3 data transfer without user plane CIoT 5GS optimization, then the UE shall also pass an indication of user plane CIoT 5GS optimization to lower layers.
    In WB-N1 mode, when the UE requests the lower layer to establish a RRC connection and the UE requests the use of control plane CIoT 5GS optimization or user plane CIoT 5GS optimization, the UE shall pass an indication of the requested CIoT 5GS optimizations to the lower layers.
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    5.3.22  Interaction between MICO mode with active time and extended idle mode DRX cycle |R16|  p. 199

    The UE can request the use of both MICO mode with active time and eDRX during a registration procedure but it is up to the network to decide to enable none, one of them or both (see TS 23.501).
    If the network accepts the use of both MICO mode with active time (see subclause 5.3.6) and eDRX (see subclause 5.3.16), the extended DRX parameters provided to the UE should allow for multiple paging occasions before the active timer expires.
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    5.3.23  Forbidden wireline access area |R16|  p. 199

    The AMF shall send a REGISTRATION REJECT, SERVICE REJECT or DEREGISTRATION REQUEST message over a wireline access network with the 5GMM cause #77 "wireline access area not allowed", if conditions specified in TS 23.316 for AMF's enforcement of forbidden area are fulfilled.
    If a REGISTRATION REJECT, SERVICE REJECT or DEREGISTRATION REQUEST message is received over a wireline access network with the 5GMM cause #77 "wireline access area not allowed":
    1. the 5G-RG shall not access 5GCN over the wireline access network until the 5G-RG is switched off, the UICC containing the USIM is removed, or the 5G-RG starts using another wireline access network;
    2. the W-AGF acting on behalf of the FN-CRG shall not access 5GCN until the W-AGF acting on behalf of the FN-CRG determines that the FN-CRG is switched off; and
    3. the W-AGF acting on behalf of the N5GC device shall not access 5GCN until the W-AGF acting on behalf of the FN-CRG determines that the FN-CRG serving the N5GC device is switched off.
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    5.3.24  WUS assistance |R16|  p. 200

    A UE supporting reception of WUS assistance information indicates its capability for reception of WUS assistance information during registration procedure (see TS 23.501). The UE supporting WUS assistance information may include its UE paging probability information in the Requested WUS assistance information IE in the REGISTRATION REQUEST message (see TS 23.501). The UE shall not include its UE paging probability information during:
    1. a registration procedure for initial registration for emergency services (see subclause 5.5.1.2);
    2. a registration procedure for initial registration for initiating an emergency PDU session (see subclause 5.5.1.2);
    3. a registration procedure for mobility and periodic registration update (see subclause 5.5.1.3) for initiating an emergency PDU session if the UE is in the state 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE; or
    4. a registration procedure for mobility and periodic registration update (see subclause 5.5.1.3) when the UE has an emergency PDU session established.
    The UE and the network may negotiate the UE paging probability information during a registration procedure when the UE does not have an emergency PDU session. The UE paging probability information is an assistance information used to determine the WUS group for paging UE (see TS 23.501, TS 36.300).
    If a UE supporting WUS assistance information did not receive the Negotiated WUS assistance information IE during the last registration procedure due to an active emergency PDU session over 3GPP access, the UE shall initiate a registration procedure for mobility and periodic registration update to request WUS assistance information after the emergency PDU session is released over 3GPP access.
    If the UE does not have an emergency PDU session and the network accepts the use of the WUS assistance information for the UE, the network determines the negotiated UE paging probability information for the UE based on the requested UE paging probability information, if any, local configuration or previous statistical information for the UE, and then indicates the negotiated UE paging probability information in the Negotiated WUS assistance information IE to the UE in the REGISTRATION ACCEPT message. The network shall store the negotiated UE paging probability information in the 5GMM context of the UE for paging.
    The UE shall use WUS assistance information only if the UE received the Negotiated WUS assistance information IE during the last registration procedure. If the UE did not receive the Negotiated WUS assistance information IE during the last registration procedure, the UE shall delete any existing WUS assistance information received from the network.
    If the network did not accept the request to use WUS assistance information, the network shall delete the stored negotiated UE paging probability information for the UE, if available.
    When an emergency PDU session is successfully established after the UE received the Negotiated WUS assistance information IE during the last registration procedure, the UE and the AMF shall not use WUS assistance information until:
    • the successful completion of the PDU session release procedure of the emergency PDU session;
    • the UE receives WUS assistance information during a registration procedure with PDU session status IE or upon successful completion of a service request procedure, if the UE or the network locally releases the emergency PDU session; or
    • the successful completion of the handover of the emergency PDU session to non-3GPP access.
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    5.3.25  Paging Early Indication with Paging Subgrouping Assistance |R17|  p. 200

    A UE may indicate its capability to support NR paging subgrouping during registration procedure when the UE:
    • initiates a registration procedure with 5GS registration type IE not set to "emergency registration"; and
    • does not have an active emergency PDU session.
    If a UE supporting NR paging subgrouping did not indicate its capability to support NR paging subgrouping during the last registration procedure due to an active emergency PDU session over 3GPP access, the UE shall initiate a registration procedure for mobility and periodic registration update procedure to indicate its capability to support NR paging subgrouping after the emergency PDU session is released over 3GPP access.
    If the UE indicates support of NR paging subgrouping the UE may include its paging probability information in the Requested PEIPS assistance information IE in the REGISTRATION REQUEST message. If the UE indicates support of NR paging subgrouping and the network supports and accepts the use of the PEIPS assistance information for the UE, the network provides to the UE the Negotiated PEIPS assistance information, including the Paging subgroup ID, in the REGISTRATION ACCEPT message or the CONFIGURATION UPDATE COMMAND message. The Paging subgroup ID is used to determine the NR paging subgroup for paging the UE. The network shall store the Paging subgroup ID in the 5GMM context of the UE.
    The UE shall use PEIPS assistance information only if the UE received the Negotiated PEIPS assistance information IE during the last registration procedure. If the UE did not receive the Negotiated PEIPS assistance information IE during the last registration procedure, the UE shall delete any existing PEIPS assistance information received from the network.
    If the network did not accept the request to use PEIPS assistance information during the registration procedure, the network shall delete the stored PEIPS assistance information for the UE, if available.
    If the UE supports the use of the PEIPS assistance information and the network supports and accepts the use of the PEIPS assistance information, the network may provide the PEIPS assistance information to the UE by including the Updated PEIPS assistance information IE in the CONFIGURATION UPDATE COMMAND message.
    When an emergency PDU session is successfully established over 3GPP access after the UE received the Negotiated PEIPS assistance information IE during the last registration procedure, the UE and the AMF shall not use PEIPS assistance information until:
    • the successful completion of the PDU session release procedure of the emergency PDU;
    • the UE receives PEIPS assistance information during a registration procedure with PDU session status IE or upon successful completion of a service request procedure, if the UE or the network locally releases the emergency PDU session;
    • the successful completion of handover of emergency PDU session to non-3GPP access; or
    • the successful transfer of the emergency PDU session in 5GS to the EPS or ePDG connected to EPC.
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    5.3.26  Support for unavailability period |R18|  p. 201

    If the UE and network support unavailability period and an event is triggered in the UE making the UE unavailable for a certain period of time, the UE may store its 5GMM and 5GSM context in USIM or non-volatile memory to be able to reuse it after the unavailability period.
    To activate the unavailability period, the UE provides an unavailability period duration during the registration procedure or during the de-registration procedure (see TS 23.501 and TS 23.502). The support for the unavailability period is negotiated in the registration procedure. If the UE provided an unavailability period duration in the last registration procedure or de-registration procedure, the AMF considers the UE unreachable until the UE re-register for a normal service without providing an unavailability period duration. During the registration procedure, the AMFmay determine the value of the periodic registration update timer (T3512) provided to the UE based on the unavailability period duration. The AMF releases the N1 signalling connection after the completion of the registration procedure in which the UE provided an unavailability period duration.
    When the unavailability period is activated, all NAS timers are stopped and associated procedures aborted except for timers T3512, T3346, T3447, T3396, T3584, T3585, any back-off timers, T3247, and the timer T controlling the periodic search for HPLMN or EHPLMN or higher prioritized PLMNs (see TS 23.122).
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