4 Overall process structure

23.1223GPPNon-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle modeRelease 18TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.1 Process goal

The aim of the idle mode processes is to ensure that the registered PLMN is the selected PLMN and that the registered SNPN is the selected SNPN.

4.2 States description

Each of the processes of PLMN selection and SNPN selection, cell selection and location registration can be described by a set of states. The overall state of the mobile is thus a composite of the states of the three processes. In some cases, an event which causes a change of state in one process may trigger a change of state in another process, e.g., camping on a cell in a new registration area triggers an LR request. Except for SNPN selection, the relationship between the processes is illustrated in figure 1 in clause 5.

Except for SNPN selection, the states in which the MS may be, for each of the processes, are described below and illustrated in figures 2a, 2b and 3 in clause 5. For many of the states, a fuller description can be found in other Technical Specifications, and a reference to the Technical Specification is given after the state description.

In the event of any conflict between the diagrams and the text in the present document, the text takes precedence.

4.3 List of states

4.3.1 List of states for the PLMN selection process

4.3.1.1 List of states for automatic mode (figure 2a)

A1 Trying RPLMN ‑ The MS is trying to perform a Location Registration on the registered PLMN.

A2 On PLMN ‑ The MS has successfully registered on a PLMN.

A3 Trying PLMN ‑ The MS is trying to register on a PLMN in the ordered list of PLMNs.

A4 Wait for PLMNs to appear ‑ There are no allowable and available PLMNs at present and the MS is waiting for one to appear.

A5 HPLMN search in progress ‑ The MS is trying to find if the HPLMN is available.

A6 No SIM ‑ There is no SIM in the MS, or certain LR responses have been received.

4.3.1.2 List of states for manual mode (figure 2b)

M1 Trying registered PLMN ‑ The MS is trying to perform a Location Registration on the registered PLMN.

M2 On PLMN ‑ The MS has successfully registered on a PLMN.

M3 Not on PLMN ‑ The MS has failed to register on the selected PLMN.

M4 Trying PLMN ‑ The MS is trying to register on a user selected PLMN.

M5 No SIM ‑ There is no SIM in the MS, or certain LR responses have been received.

4.3.2 Void

4.3.3 List of states for location registration (figure 3)

The states are entered depending on responses to location registration (LR) requests. Independent update states exist for GPRS and for non-GPRS operation in MSs capable of GPRS and non-GPRS services.

L0 Null – The MS is considered in this state when switched off.

L1 Updated ‑ The MS enters this state if an LR request is accepted. The update status is set to "UPDATED". The GPRS and the non-GPRS update state of an MS may enter "Updated" as a result of combined signalling or as a result of individual signalling depending on the capabilities of the network.

L2 Idle, No IMSI ‑ The MS enters this state if an LR request is rejected with cause:

a) IMSI unknown in HLR;

b) illegal ME;

c) illegal MS;

d) GPRS services not allowed,

e) GPRS services and non-GPRS services not allowed,

or if there is no SIM. All update states of an MS enter this state regardless whether received by individual or combined signalling for events b) and c). Event a) has no influence on the GPRS update state. Events b) and c) result in "ROAMING NOT ALLOWED" for the GPRS and/or non-GPRS update status depending on the specific location registration procedure. Event d) results in "ROAMING NOT ALLOWED" for the GPRS update status. Event e) results in "ROAMING NOT ALLOWED" for the GPRS update status and non-GPRS update status.

If a SIM is present, the non-GPRS update status of the SIM is set to "ROAMING NOT ALLOWED".

L3 Roaming not allowed ‑ The MS enters this state if it receives an LR reject message with the cause:

a) PLMN not allowed;

b) Location area not allowed;

c) Tracking area not allowed;

d) Roaming not allowed in this location area;

e) Roaming not allowed in this tracking area;

f) GPRS services not allowed in this PLMN;

g) No suitable cells in location area;

h) No suitable cells in tracking area;

i) Not authorized for this CSG.

Except from event f) all update states of the MS are set to "Roaming not allowed" regardless whether received by individual or combined signalling. Event f) results in "Roaming not allowed" for the GPRS update state only. Event f) has no influence on the non-GPRS update state. The behaviour of the MS in the roaming not allowed state is dependent on the LR reject cause as shown in table 2 in clause 5. Additionally:

– in automatic mode, "PLMN not allowed", "Roaming not allowed in this location area" and "Roaming not allowed in this tracking area" cause the Automatic Network Selection procedure of clause 4.4.3.1.1 to be started; it is also caused by "GPRS services not allowed in this PLMN" when received by a GPRS MS operating in MS operation mode C;

– in manual mode, "PLMN not allowed" and "Roaming not allowed" cause the Manual Network Selection procedure of clause 4.4.3.1.2 to be started; it is also caused by "GPRS services not allowed in this PLMN" when received by a GPRS MS operating in MS operation mode C.

L4 Not updated ‑ The MS enters this state if any LR failure not specified for states L2 or L3 occurs, in which cases the MS is not certain whether or not the network has received and accepted the LR attempt. The non-GPRS update status on the SIM and/or the GPRS update status are set to "NOT UPDATED" depending on the specific location registration procedure and their outcome.

L5 LR request – The MS enters this state when determining that a LR request is to be made.

L6 LR pending – The MS enters this state after having started the LR, waiting for the outcome (response message from the network).

NOTE This clause does not describe all the cases. For more details refer to 3GPP TS 24.008 [23], 3GPP TS 24.301 [23A] and 3GPP TS 24.501 [64].

4.4 PLMN selection process

4.4.1 Introduction

There are two modes for PLMN selection, automatic and manual. These are described in clauses 4.4.3 below and illustrated in figures 2a to 2b in clause 5.

NOTE: Figures 2a to 2b in clause 5 do not cover CAG selection aspects.

The MS not operating in SNPN access mode shall perform PLMN selection process.

The MS operating in SNPN access mode shall not perform PLMN selection process.

4.4.2 Registration on a PLMN

The MS shall perform registration on the PLMN if the MS is capable of services which require registration. In both automatic and manual modes, the concept of registration on a PLMN is used. An MS successfully registers on a PLMN if:

a) the MS has found a suitable cell of the PLMN to camp on; and

b) an LR request from the MS has been accepted in the registration area of the cell on which the MS is camped (see table 1).

4.4.3 PLMN selection

The registration on the selected PLMN and the location registration are only necessary if the MS is capable of services which require registration. Otherwise, the PLMN selection procedures are performed without registration.

The ME shall utilise all the information stored in the SIM related to the PLMN selection; e.g. "HPLMN Selector with Access Technology", "User Controlled PLMN Selector with Access Technology", "Forbidden PLMNs", "Equivalent HPLMN", see 3GPP TS 31.102 [40]. The ME shall also utilise the extension of the "forbidden PLMNs" list that it has stored locally on the ME if available.

The ME shall either utilise the "Operator controlled PLMN Selector with Access Technology" that it has stored locally on the ME, or the Operator controlled PLMN Selector with Access Technology" stored in the SIM, for the purposes of PLMN selection.

The "HPLMN Selector with Access Technology", "User Controlled PLMN Selector with Access Technology" and "Operator Controlled PLMN Selector with Access Technology" data files in the SIM include associated access technologies for each PLMN entry, see 3GPP TS 31.102 [40]. The PLMN/access technology combinations are listed in priority order. If an entry indicates more than one access technology, then no priority is defined for the access technologies within this entry and the priority applied to each access technology within this entry is an implementation issue. If no particular access technology is indicated in an entry, it shall be assumed that all access technologies supported by the ME apply to the entry. If an entry only indicates access technologies not supported by the ME, the entry shall be ignored. If an entry indicates at least one access technology supported by the ME, the entry shall be used in the PLMN selection procedures if the other criteria defined for the specific PLMN selection procedures are fulfilled.

The Mobile Equipment stores a list of "equivalent PLMNs". This list is replaced or deleted at the end of each location update procedure, routing area update procedure, GPRS attach procedure, tracking area update procedure, EPS attach procedure, and registration procedure. The list is deleted by an MS attached for emergency bearer services or for access to RLOS after detach or registered for emergency services after de-registration. The stored list consists of a list of equivalent PLMNs as downloaded by the network plus the PLMN code of the registered PLMN that downloaded the list. All PLMNs in the stored list, in all access technologies supported by the PLMN, are regarded as equivalent to each other for PLMN selection, cell selection/re-selection and handover.

When the MS reselects to a cell in a shared network, and the cell is a suitable cell for multiple PLMN identities received on the BCCH or on the EC-BCCH the AS indicates these multiple PLMN identities to the NAS according to 3GPP TS 44.018 [34], 3GPP TS 44.060 [39], 3GPP TS 25.304 [32], 3GPP TS 36.304 [43] and 3GPP TS 38.304 [61]. The MS shall choose one of these PLMNs. If the registered PLMN is available among these PLMNs, the MS shall not choose a different PLMN.

The MS shall not use the PLMN codes contained in the "HPLMN Selector with Access Technology" data file.

It is possible for the home network operator to identify alternative Network IDs as the HPLMN. If the EHPLMN list is present, and not empty, the entries in the EHPLMN list are used in the network selection procedures. When attempting to select a network the highest priority EHPLMN that is available shall be selected. If the EHPLMN list is present and is empty or if the EHPLMN list is not present, the HPLMN derived from the IMSI is used for network selection procedures.

NOTE 1: The "HPLMN Selector with Access Technology" data file is only used by the MS to get the HPLMN access technologies related to the HPLMN code which corresponds to the PLMN code included in the IMSI if the EHPLMN list is not present or is empty. If the EHPLMN list is present then this data field is applicable to all the entries within the EHPLMN list.

NOTE 2: Different GSM frequency bands (e.g. 900, 1800, 1900, 400) are all considered GSM access technology. An MS supporting more than one band should scan all the bands it’s supports when scanning for GSM frequencies. However GSM COMPACT systems which use GSM frequency bands but with the CBPCCH broadcast channel are considered as a separate access technology from GSM.

NOTE 3: The inclusion of the HPLMN derived from the IMSI in the EHPLMN list is allowed. The priority of the HPLMN derived from the IMSI is given by its position in the EHPLMN list, see 3GPP TS 31.102 [40].

The MS may support minimization of service interruption (MINT).

4.4.3.1 At switch‑on or recovery from lack of coverage

At switch on, following recovery from lack of coverage, or when the MS stops operating in the SNPN access mode, the MS selects the registered PLMN or equivalent PLMN (if it is available) using all access technologies that the MS is capable of and if necessary (in the case of recovery from lack of coverage, see clause 4.5.2) attempts to perform a Location Registration.

NOTE 1: The MS in automatic network selection mode can end the PLMN search procedure once the registered PLMN or equivalent PLMN is found on an access technology.

NOTE 2: An MS in automatic network selection mode can use location information to determine which PLMNs can be available in its present location.

EXCEPTION: As an alternative option to this, if the MS is in automatic network selection mode and it finds coverage of an EHPLMN, the MS may register to that EHPLMN and not return to the registered PLMN or equivalent PLMN. If the EHPLMN list is not present or is empty, and the HPLMN is available, the MS may register on the HPLMN and not return to the registered PLMN or equivalent PLMN. The operator shall be able to control by SIM configuration whether an MS that supports this option is permitted to perform this alternative behaviour.

EXCEPTION: As an alternative option to this, if the MS is in automatic network selection mode, the MS has a list of "PLMNs where registration was aborted due to SOR" and the registered PLMN is part of the list of "PLMNs where registration was aborted due to SOR", the MS may choose not to return to the registered PLMN or equivalent PLMN and proceed as defined in clause 4.4.3.1.1 with the exception that in iii), the MS considers PLMNs which are in the list of "PLMNs where registration was aborted due to SOR" as lowest priority.

EXCEPTION: In A/Gb mode an MS with voice capability, shall not search for CPBCCH carriers. In A/Gb mode an MS not supporting packet services shall not search for CPBCCH carriers.

If successful registration is achieved, the MS indicates the selected PLMN.

If there is no registered PLMN, or if registration is not possible due to the PLMN being unavailable or registration failure, the MS follows one of the following two procedures depending on its PLMN selection operating mode. At switch on, if the MS provides the optional feature of user preferred PLMN selection operating mode at switch on then this operating mode shall be used. Otherwise, the MS shall use the PLMN selection mode that was used before switching off.

EXCEPTION: At switch on, if the MS is in manual mode and neither registered PLMN nor PLMN that is equivalent to it is available but EHPLMN is available, then instead of performing the manual network selection mode procedure of clause 4.4.3.1.2 the MS may select and attempt registration on the highest priority EHPLMN. If the EHPLMN list is not available or is empty and the HPLMN is available, then the MS may select and attempt registration on the HPLMN. If the MS supports CAG and needs to select or attempt registration on the highest priority EHPLMN or HPLMN, the MS follows network selection procedures of clause 4.4.3.1.1 bullet m). The MS shall remain in manual mode.

NOTE 3: If successful registration is achieved, then the current serving PLMN becomes the registered PLMN and the MS does not store the previous registered PLMN for later use.

EXCEPTION: If registration is not possible on recovery from lack of coverage due to the registered PLMN being unavailable, an MS attached to GPRS services, attached via E-UTRAN or registered via the NG-RAN may, optionally, continue looking for the registered PLMN for an implementation dependent time.

NOTE 4: An MS attached to GPRS services, attached via E-UTRAN or registered via the NG-RAN should use the above exception only if one or more PDP contexts, PDN connections or PDU sessions are currently active.

EXCEPTION: At switch on, if the RPLMN is a PLMN with which the MS was registered for disaster roaming services and the MS is registered via non-3GPP access connected to 5GCN or an NG-RAN cell of the RPLMN broadcasts neither the disaster related indication nor a "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN" including the MS determined PLMN with disaster condition or an allowable PLMN is available then the MS will ignore RPLMN and its equivalent PLMN.

4.4.3.1.1 Automatic Network Selection Mode Procedure

The MS selects and attempts registration on other PLMN/access technology combinations, if available and, for bullets i, ii, iii, iv, v, allowable, in the following order:

i) either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present) ;

ii) each PLMN/access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

iii) each PLMN/access technology combination in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order);

iv) other PLMN/access technology combinations with received high quality signal in random order;

NOTE 1: High quality signal is defined in the appropriate AS specification.

v) other PLMN/access technology combinations in order of decreasing signal quality.

vi) PLMN/NG-RAN combinations for any forbidden PLMNs broadcasting the PLMN ID of the MS determined PLMN with disaster condition or broadcasting the disaster related indication and matching the below conditions:

a) if the indication of ‘applicability of "lists of PLMN(s) to be used in disaster condition" provided by a VPLMN’ is set to true:

– each PLMN in the "list of PLMN(s) to be used in disaster condition" stored in the ME which is associated with the PLMN ID of the MS determined PLMN with disaster condition, if any, ordered based on this list; otherwise

– if the ME does not have a stored "list of PLMN(s) to be used in disaster condition" associated with the PLMN ID of the MS determined PLMN with disaster condition, each PLMN in the "list of PLMN(s) to be used in disaster condition" stored in the ME which is associated with the PLMN ID of the HPLMN, if any, ordered based on this list.

b) if the indication of ‘applicability of "lists of PLMN(s) to be used in disaster condition" provided by a VPLMN’ is set to false:

– each PLMN in the "list of PLMN(s) to be used in disaster condition" stored in the ME which is associated with the HPLMN, if any, ordered based on this list.

vii) PLMN /NG-RAN combinations for other forbidden PLMNs broadcasting the PLMN ID of the MS determined PLMN with disaster condition or broadcasting the disaster related indication, in random order.

When following the above procedure the following requirements apply:

a) An MS with voice capability shall ignore PLMNs for which the MS has identified at least one GSM COMPACT.

b) In A/Gb mode or GSM COMPACT, an MS with voice capability, or an MS not supporting packet services shall not search for CPBCCH carriers.

c) In ii and iii, the MS should limit its search for the PLMN to the access technology or access technologies associated with the PLMN in the appropriate PLMN Selector with Access Technology list (User Controlled or Operator Controlled selector list).

An MS using a SIM without access technology information storage (i.e. the "User Controlled PLMN Selector with Access Technology" and the "Operator Controlled PLMN Selector with Access Technology" data files are not present) shall instead use the "PLMN Selector" data file, for each PLMN in the "PLMN Selector" data file, the MS shall search for all access technologies it is capable of. The priority ordering amongst the access technologies is implementation dependent.

d) In iv, v, vi and vii, the MS shall search for all access technologies it is capable of, before deciding which PLMN to select.

e) In ii, and iii, a packet only MS which supports GSM COMPACT, but using a SIM without access technology information storage (i.e. the "User Controlled PLMN Selector with Access Technology" and the "Operator Controlled PLMN Selector with Access Technology" data files are not present) shall instead use the "PLMN Selector" data file, for each PLMN in the "PLMN Selector" data file, the MS shall search for all access technologies it is capable of and shall assume GSM COMPACT access technology as the lowest priority radio access technology.

f) In i, the MS shall search for all access technologies it is capable of. No priority is defined for the preferred access technology and the priority is an implementation issue, but "HPLMN Selector with Access Technology" data file on the SIM may be used to optimise the procedure.

g) In i, an MS using a SIM without access technology information storage (i.e. the "HPLMN Selector with Access Technology" data file is not present) shall search for all access technologies it is capable of. The priority ordering amongst the access technologies is implementation dependent. A packet only MS which supports GSM COMPACT using a SIM without access technology information storage shall also assume GSM COMPACT access technology as the lowest priority radio access technology.

NOTE 2: For f) and g), the MS in automatic network selection mode can end the PLMN search procedure once the HPLMN or the highest priority EHPLMN is found on an access technology.

NOTE 3: For i, ii and iii, the MS can use location information to determine which PLMNs can be available in its present location.

h) In v, the MS shall order the PLMN/access technology combinations in order of decreasing signal quality within each access technology. The order between PLMN/access technology combinations with different access technologies is an MS implementation issue.

NOTE 4: Requirements a) and b) apply also to requirement d), so a GSM voice capable MS should not search for GSM COMPACT PLMNs, even if capable of GSM COMPACT.

NOTE 5: Requirements a) and b) apply also to requirement f), so a GSM voice capable MS should not search for GSM COMPACT PLMNs, even if this is the only access technology on the "HPLMN Selector with Access Technology" data file on the SIM.

i) In i to vii, the MS shall not consider PLMNs where voice service was not possible as PLMN selection candidate, unless such PLMN is available in GERAN or UTRAN or no other allowed PLMN is available.

j) In i to v, if the MS only supports EMM-REGISTERED without PDN connection (see 3GPP TS 24.301 [23A]), the MS shall not consider PLMNs which do not advertise support of EMM-REGISTERED without PDN connection.

k) In i to v, if the MS only supports control plane CIoT EPS optimization (see 3GPP TS 24.301 [23A]) and the MS camps on a E-UTRA cell which is not NB-IoT cell (see 3GPP TS 36.304 [43], 3GPP TS 36.331 [42]), the MS shall not consider PLMNs which do not advertise support of EPS services with control plane CIoT EPS optimization.

l) In i to vii, if the MS is in eCall only mode, the MS shall not consider PLMNs which do not advertise support for eCall over IMS, unless such PLMNs are available in GERAN or UTRAN.

NOTE 6: As an implementation option, an MS in eCall only mode that was not able to select any PLMN according to l) can perform a second iteration of i to v with no restriction.

m) In i to vii, if the MS supports CAG and:

1) is provisioned with a non-empty "CAG information list", the MS shall consider a PLMN indicated by an NG-RAN cell only if:

A) the cell is a CAG cell and broadcasts a CAG-ID for the PLMN such that there exists an entry with the PLMN ID of the PLMN in the "CAG information list" and the CAG-ID is included in the "Allowed CAG list" of the entry; or

B) the cell is not a CAG cell and:

– there is no entry with the PLMN ID of the PLMN in the "CAG information list"; or

– there exists an entry with the PLMN ID of the PLMN in the "CAG information list" but the "indication that the MS is only allowed to access 5GS via CAG cells" is not included in the entry; or

2) is provisioned with an empty "CAG information list" or is not provisioned with a "CAG information list", the MS shall consider a PLMN indicated by an NG-RAN cell only if the cell is not a CAG cell.

n) In i to vii, if the MS only supports control plane CIoT 5GS optimization (see 3GPP TS 23.501 [62]) and the MS camps on an E-UTRA cell connected to 5GCN, which is not NB-IoT cell (see 3GPP TS 36.304 [43], 3GPP TS 36.331 [42]), the MS shall not consider PLMNs which do not advertise support of 5GS services with control plane CIoT 5GS optimization.

o) In i to vii, if the MS supports CIoT 5GS optimizations, the MS shall not consider the PLMN/access technology combinations for which the MS preferred CIoT network behaviour is not advertised as supported by the PLMN/access technology combination (see 3GPP TS 24.501 [64]).

NOTE 7: As an implementation option, the MS supporting CIoT 5GS optimizations that was not able to select any PLMN according to o) can perform a second iteration of i to v with no restriction.

p) In iii, the MS shall use the PLMN/access technology combination in the "Operator Controlled PLMN Selector with Access Technology" stored in the ME, if the last update of the "Operator Controlled PLMN Selector with Access Technology" was due to receiving steering of roaming information containing the "list of preferred PLMN/access technology combinations" (see annex C) and storing it in the ME. Otherwise, the MS shall use the "Operator Controlled PLMN Selector with Access Technology" list retrieved from the SIM.

q1) for vi and vii, if a forbidden PLMN is broadcasting the "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN", the MS shall determine the MS determined PLMN with disaster condition as follows:

i) if the MS’s RPLMN is included in any "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN" broadcast by any NG-RAN cell and is allowable, the MS shall consider that the MS’s RPLMN is the MS determined PLMN with disaster condition; or

ii) if the MS’s RPLMN is not included in any "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN" broadcast by any NG-RAN cell or the MS’s RPLMN is not allowable or the MS does not have a RPLMN (see table 1), the MS shall determine the MS determined PLMN with disaster condition from PLMNs:

– in the "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN" broadcast by any NG-RAN cell; and

– which are allowable;

in the following order:

– either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present);

– each PLMN in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

– each PLMN in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order); and

– other PLMNs.

q2) for vi and vii, if a forbidden PLMN is broadcasting the "disaster related indication", the MS shall attempt to determine the MS determined PLMN with disaster condition as follows:

1) if the country of the MS’s RPLMN matches the country of a PLMN for which any NG-RAN cell broadcasts the "disaster related indication" and the MS’s RPLMN is allowable, the MS shall consider that the MS’s RPLMN is the MS determined PLMN with disaster condition; or

2) if the country of the MS’s RPLMN does not match the country of any PLMN for which any NG-RAN cell broadcasts the "disaster related indication" or the MS’s RPLMN is not allowable, the MS shall determine the MS determined PLMN with disaster condition from allowable PLMN(s) where the country of allowable PLMN(s) matches the country of a PLMN for which any NG-RAN cell broadcasts the "disaster related indication" in the following order:

– either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present);

– each PLMN in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

– each PLMN in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order).

r) The MS shall perform vi and vii to select a PLMN for disaster roaming services only if:

1) the MS supports MINT;

2) the indication of whether disaster roaming is enabled in the UE stored in the ME is set to "Disaster roaming is enabled in the UE";

3) there is no available PLMN which is allowable;

4) the MS is not in 5GMM-REGISTERED state and 5GMM-CONNECTED mode over non-3GPP access (see 3GPP TS 24.501 [64]);

4a) the MS does not have a PDN connection via an ePDG connected to EPC; and

5) an NG-RAN cell of the PLMN or of a shared network where the PLMN is available:

A) broadcasts the disaster related indication for the PLMN. The disaster related indication broadcasted by the NG-RAN cell for the PLMN indicates that the PLMN is accessible for disaster inbound roamers, that this PLMN accepts disaster inbound roamers from any PLMN(s) other than the PLMN(s) available on the NG-RAN cell, and that a disaster condition applies to all PLMN(s) other than the PLMN(s) available on the NG-RAN cell in the location of the broadcast. If the disaster related indication is broadcasted, the disaster inbound roamers attempt to determine the MS determined PLMN with disaster condition as per bullet q2); or

NOTE 8: In case of a shared network, the disaster related indication is broadcasted per PLMN.

B) broadcasts a "list of one or more PLMN(s) with disaster condition for which disaster roaming services is offered by the available PLMN" which includes the MS determined PLMN with disaster condition as determined in bullet q1).

s) In i to vii, if the MS only supports NR RedCap and the MS camps on an NR cell connected to 5GCN, the MS shall not consider PLMNs which do not advertise support of NR RedCap.

t) In i to vii, if the MS detects a PLMN in satellite NG-RAN access technology which fulfils the conditions related to the list of "PLMNs not allowed to operate at the present UE location" as defined in clause 3.1, it shall not consider the PLMN as PLMN selection candidate for satellite NG-RAN access technology.

u) In i to vii, if the MS detects a PLMN in a satellite E-UTRAN access technology which fulfils the conditions related to the list of "PLMNs not allowed to operate at the present UE location" as defined in clause 3.1, it shall not consider the PLMN as PLMN selection candidate for the satellite E-UTRAN access technology.

If successful registration is achieved, the MS indicates the selected PLMN.

If registration cannot be achieved because no PLMNs are available and allowable, and the MS does not support access to RLOS, the MS indicates "no service" to the user, waits until a new PLMN is available and allowable and then repeats the procedure.

If there were one or more PLMNs which were available and allowable, but an LR failure made registration on those PLMNs unsuccessful or an entry in any of the lists "forbidden location areas for roaming", "forbidden tracking areas for roaming", "5GS forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "5GS forbidden tracking areas for regional provision of service", "CAG information list", or "PLMNs not allowed to operate at the present UE location" prevented a registration attempt, the MS selects the first such PLMN again and enters a limited service state.

If:

– the MS supports access to RLOS;

– either the UICC containing the USIM is not present in the MS, or the UICC containing the USIM is present in the MS and the MCC part of the IMSI in the USIM is present in the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]);

– one or more PLMNs offering access to RLOS has been found;

– registration cannot be achieved on any PLMN; and

– the MS is in limited service state,

the MS shall select a PLMN offering access to RLOS as follows:

a) if at least one preferred PLMN exists based on the RLOS preferred PLMN list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]) and the MCC part of the preferred PLMN ID is present in the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]), the MS shall select the preferred PLMN offering access to RLOS and indicate the selected preferred PLMN for access to RLOS; and

b) if none of the preferred PLMNs for access to RLOS is available, the MS shall evaluate the remaining PLMNs offering access to RLOS that are not in the RLOS preferred PLMN list. If the MCC part of a PLMN ID is present in the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]), the MS shall select this PLMN and indicate the selected PLMN for access to RLOS.

If registration cannot be achieved because no PLMNs are available and allowable, and if no PLMN offering access to RLOS has been found, or none of the PLMNs offering access to RLOS is allowed to be accessed according to the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]), or the MS does not support access to RLOS, the MS indicates "no service" to the user, waits until a new PLMN is available and then repeats the procedure.

4.4.3.1.2 Manual Network Selection Mode Procedure

The MS indicates whether there are any PLMNs, which are available using all supported access technologies. This includes PLMNs in the "forbidden PLMNs" list, "forbidden PLMNs for GPRS service" list, PLMNs which only offer services not supported by the MS, and the list of "PLMNs not allowed to operate at the present UE location". An MS which supports GSM COMPACT shall also indicate GSM COMPACT PLMNs (which use PBCCH).

If displayed, PLMNs meeting the criteria above are presented in the following order:

i)- either the HPLMN (if the EHPLMN list is not present or is empty) or, if one or more of the EHPLMNs are available then based on an optional data field on the SIM either only the highest priority available EHPLMN is to be presented to the user or all available EHPLMNs are presented to the user in priority order. If the data field is not present on the SIM, then only the highest priority available EHPLMN is presented;

ii)- PLMN/access technology combinations contained in the " User Controlled PLMN Selector with Access Technology " data file in the SIM (in priority order);

iii)- PLMN/access technology combinations contained in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order);

iv)- other PLMN/access technology combinations with received high quality signal in random order;

NOTE 1: High quality signal is defined in the appropriate AS specification.

v)- other PLMN/access technology combinations in order of decreasing signal quality.

In ii and iii, an MS using a SIM without access technology information storage (i.e. the "User Controlled PLMN Selector with Access Technology" and the "Operator Controlled PLMN Selector with Access Technology" data files are not present) shall instead present the PLMNs contained in the "PLMN Selector" data file in the SIM (in priority order).

In v, requirement h) in clause 4.4.3.1.1 applies.

In i to v, requirements j), k) and l) in clause 4.4.3.1.1 apply.

In iii, requirement p) in clause 4.4.3.1.1 applies.

In GSM COMPACT, the non-support of voice services shall be indicated to the user.

The HPLMN may provide on the SIM additional information on the available PLMNs. If this information is provided, then the MS shall indicate it to the user. This information, provided as free text may include:

– preferred partner,

– roaming agreement status,

– supported services

Furthermore, the MS may indicate whether the available PLMNs are present on the EHPLMN list, the Forbidden list, the User Controlled PLMN List or the Operator Controlled PLMN List. The MS may also indicate that the PLMN is not present on any of these lists.

If:

– the MS supports MINT;

– the MS is not registered via non-3GPP access connected to 5GCN;

– the MS has detected that the RPLMN is a MS determined PLMN with disaster condition as broadcasted by an NG-RAN cell of an available PLMN(s) (see clause 4.4.3.1.1);

– only forbidden PLMN(s) are available; and

– the MS receives indication that some of the forbidden PLMN(s) provide disaster roaming services to the MS(s) of the RPLMN (see clause 4.4.3.1.1),

then the MS may indicate to the user that those PLMN(s) support disaster roaming services.

In i to v, if the MS supports CAG, for each PLMN/access technology combination of NG-RAN access technology, the MS shall present to the user:

a) the PLMN/access technology combination and a list of CAG-IDs composed of one or more CAG-IDs such that for each CAG-ID:

1) there is an available CAG cell which broadcasts the CAG-ID for the PLMN; and

2) the following is true:

i) there exists an entry with the PLMN ID of the PLMN in the "CAG information list" and the CAG-ID is included in the "Allowed CAG list" of the entry; or

ii) the available CAG cell broadcasting the CAG-ID for the PLMN also broadcasts that the PLMN allows a user to manually select the CAG-ID.

For each of the presented CAG-ID, the MS may indicate to the user whether the CAG-ID is present in the "Allowed CAG list" stored in the UE; and

b) the PLMN/access technology combination without a list of CAG-IDs, if there is an available NG-RAN cell which is not a CAG cell for the PLMN. If there exists an entry for the presented PLMN in the "CAG information list" and the entry includes an "indication that the MS is only allowed to access 5GS via CAG cells", the MS may indicate to the user that the MS is only allowed to access the PLMN via CAG cells.

If the NAS receives a human-readable network name associated with a CAG-ID and a PLMN ID from the AS, the human-readable network name shall be sent along with the CAG-ID and PLMN ID to the upper layer for use in manual CAG selection.

NOTE 2: A human-readable network name can be broadcasted per CAG-ID and PLMN ID by a CAG cell.

Upon selection of a PLMN (and CAG-ID if the user selected a desired CAG-ID as well) by the user, the NAS shall provide the AS with the selected PLMN ID (and CAG-ID if the user selected a desired CAG-ID as well or an indication to select a non-CAG cell if the user did not select any CAG-ID) and the MS initiates registration on this PLMN (and on a cell which broadcasts the CAG-ID if the user selected a desired CAG-ID as well) using the access technology chosen by the user for that PLMN or using the highest priority available access technology for that PLMN, if the associated access technologies have a priority order (this may take place at any time during the presentation of PLMNs). For such a registration, the MS shall ignore the contents of the "forbidden location areas for roaming", "forbidden tracking areas for roaming", "5GS forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "5GS forbidden tracking areas for regional provision of service", "forbidden PLMNs for GPRS service", "PLMNs not allowed to operate at the present UE location" and "forbidden PLMNs" lists. Also for such a registration, if the NAS has provided the AS with an indication to select a non-CAG cell, the MS shall ignore the "indication that the MS is only allowed to access 5GS via CAG cells", if any, in the "CAG information list" for the selected PLMN:

– a non-CAG cell, the MS shall ignore the "indication that the MS is only allowed to access 5GS via CAG cells", if any, in the "CAG information list" for the selected PLMN; or

– a CAG cell and none of the CAG-ID(s) of the CAG cell are present in the "Allowed CAG list" associated with that PLMN in the "CAG information list", the MS shall consider the selected CAG-ID of the selected PLMN as part of the "Allowed CAG list" for the selected PLMN for this registration attempt.

NOTE 3: It is an MS implementation option whether to indicate access technologies to the user. If the MS does display access technologies, then the access technology selected by the user is only used for initial registration on the selected PLMN. If the MS does not display access technologies, then the access technology chosen for a particular PLMN should be the highest priority available access technology for that PLMN, if the associated access technologies have a priority order, and is only used for initial registration.

If the UE has a PDU session for emergency services, a PDN connection for emergency bearer services or a PDP context for emergency bearer services, manual network selection shall not be performed.

After selection of a PLMN and CAG-ID, if the AS does not provide an indication of finding a cell belonging to the selected PLMN and which broadcasts the selected CAG-ID for the registration procedure (see 3GPP TS 38.304 [40]), then:

i) the MS shall indicate to user that it can not find the selected PLMN and CAG-ID; and

ii) If there is an "indication that the MS is only allowed to access 5GS via CAG cells" in the "CAG information list" for the selected PLMN, the MS may attempt to camp on a suitable CAG cell broadcasting a CAG-ID present in the "Allowed CAG list" for the selected PLMN or an acceptable cell, otherwise the MS may attempt to camp on a suitable cell belonging to the selected PLMN (i.e. a non-CAG cell or a CAG cell broadcasting a CAG-ID present in the "Allowed CAG list" for the selected PLMN) or an acceptable cell.

Once the MS has registered on a PLMN selected by the user, the MS shall not automatically register on a different PLMN unless:

i) the new PLMN is declared as an equivalent PLMN by the registered PLMN. If the MS is registered for disaster roaming services, the UE shall also detect that the new PLMN offers disaster roaming services to the MS determined PLMN with disaster condition as broadcasted by the NG-RAN cell of the new PLMN (see clause 4.4.3.1.1) and that the MS determined PLMN with disaster condition in the old PLMN is also a MS determined PLMN with disaster condition in the new PLMN;

ii) the user selects automatic mode;

iii) the user initiates an emergency call while the MS is in limited service state and either the network does not broadcast the indication of support of emergency calls in limited service state, the registration request for emergency services is rejected by the network or the attach request for emergency bearer services is rejected by the network; or

iv) the user initiates access to RLOS, while the MS is in limited service state and either the network does not broadcast the indication of support of RLOS in limited service state, or the EPS attach request for access to RLOS is rejected by the network, or the EPS tracking area update request for access to RLOS is rejected by the network.

NOTE 4: If case iii) or iv) occurs, the MS can provide an indication to the upper layers that the MS has exited manual network selection mode.

Once the MS has registered on a PLMN selected by the user, the MS may automatically register on a different PLMN if:

1) the MS supports MINT;

2) the "list of PLMN(s) to be used in disaster condition" is non-empty;

3) there is no available PLMN which is declared as an equivalent PLMN by the RPLMN; and

4) the RPLMN of the MS is considered as the MS determined PLMN with disaster condition based on the determination of the MS determined PLMN with disaster condition as specified in clause 4.4.3.1.1.

NOTE 5: If the above case occurs, the MS can provide an indication to the upper layers that the MS has exited manual network selection mode.

If the user does not select a PLMN (or PLMN and CAG-ID), the selected PLMN shall be the one that was selected before the PLMN selection procedure started. If no such PLMN was selected or that PLMN is no longer available, then the MS shall attempt to camp on any acceptable cell and enter the limited service state.

If:

– the MS supports access to RLOS;

– one or more PLMNs offering access to RLOS has been found;

– registration cannot be achieved on any PLMN; and

– the MS is in limited service state,

the MS indicates the PLMNs offering access to RLOS, presented in the following order:

i) PLMNs contained in the RLOS preferred PLMN list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]) (in priority order) if the MCC part of the preferred PLMN ID is present in the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]); and

ii) any of the remaining PLMNs offering access to RLOS that are not in the RLOS preferred PLMN list if the MCC part of the PLMN ID is present in the RLOS allowed MCC list configured in the USIM (see 3GPP TS 31.102 [40]) or in the ME (see 3GPP TS 24.368 [50]).

Upon selection of a PLMN by the user, the MS initiates registration for access to RLOS on the PLMN chosen by the user (this may take place at any time during the presentation of PLMNs).

4.4.3.1.3 Manual CSG selection

4.4.3.1.3.1 General

The HPLMN may configure the MS whether to provide to the user CSGs for a certain PLMN without any restriction or to provide to the user only CSGs in the Operator CSG List for that PLMN.This configuration may be done either:

– in the USIM if the Operator CSG list is available in the USIM; or

– as described in 3GPP TS 24.285 [47].

In the absence of such configuration from the HPLMN for a certain PLMN, the MS shall by default provide to the user CSGs for that PLMN without any restriction.

For PLMNs where no restriction is configured, the MS provides to the user the CSGs that are available and the associated PLMNs using all access technologies which support CSGs (see 3GPP TS 23.003 [22A]) and which are supported by the MS. For each entry in the list, an indication is provided whether that CSG identity is in the Allowed CSG list or in the Operator CSG list stored in the MS for this PLMN.

For PLMNs where the MS is configured to provide to the user only CSGs in the Operator CSG List, the MS provides to the user the CSGs that are available and in the Operator CSG list, using all access technologies which support CSGs (see 3GPP TS 23.003 [22A]) and which are supported by the MS. For each entry in the list, the MS provides to the user the associated PLMN and an indication that the CSG identity is in the Operator CSG List stored in the MS for this PLMN.

Additional requirements for the display, including for the display of HNB name, can be found in 3GPP TS 22.220 [49].

The user may select a CSG from the indicated CSGs.

If the MS has a PDN connection for emergency bearer services, manual CSG selection shall not be performed.

4.4.3.1.3.2 Manual CSG selection within the RPLMN

If the user selects a CSG whose CSG identity is not included in the Allowed CSG list or Operator CSG list, then the MS shall attempt to register on a cell that corresponds to the CSG. For such a registration, the MS shall ignore the contents of the "forbidden location areas for roaming", "forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service" and "forbidden PLMNs for GPRS service" lists.

Upon successful or unsuccessful completion of the registration or if registration is not possible, because the MS is no longer in the coverage of the selected CSG, the MS shall return to automatic CSG selection mode.

Manual CSG selection within the RPLMN does not affect the current PLMN selection mode.

4.4.3.1.3.3 Manual CSG selection in a PLMN different from the RPLMN

If the user selects a CSG in a PLMN that is different from the RPLMN, then the following applies:

i) The MS shall store a duplicate of the RPLMN and a duplicate of the PLMN selection mode that were in use before the manual CSG selection was initiated, unless this manual CSG selection follows another manual CSG selection or a PLMN selection triggered by ProSe communications as specified in clause 3.1B or a PLMN selection triggered by V2X communication over PC5 as specified in clause 3.1C;

ii) The MS shall enter into Manual mode of PLMN selection in state M4 (Trying PLMN) as defined in clause 4.3.1.2;

iii) The MS shall select the PLMN corresponding to the CSG and attempt to register on the selected CSG cell in the PLMN. For such a registration, the MS shall ignore the contents of the "forbidden location areas for roaming", "forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "forbidden PLMNs for GPRS service" and "forbidden PLMNs" lists. If the registration is successful the MS remains in manual CSG selection mode, until the user selects automatic CSG selection mode, the MS is switched off or the condition of any of items iv) to viii) below is fulfilled;

iv) If the registration fails or the MS is no longer in the coverage of the selected CSG, then the MS shall return to the stored duplicate PLMN selection mode and automatic CSG selection mode and use the stored duplicate value of RPLMN for further action;

v) If the MS is switched off while on the selected CSG and switched on again, the MS should return to the stored duplicate PLMN selection mode, unless the MS provides the optional feature of user preferred PLMN selection operating mode at switch on. Additionally, the MS shall use the stored duplicate value of RPLMN and automatic CSG selection mode for further action;

vi) If the user initiates a PLMN selection while on the selected CSG, the MS shall delete the stored duplicate PLMN selection mode, use the stored duplicate value of RPLMN as RPLMN, return to automatic CSG selection mode and follow the procedures (as specified for switch-on or recovery from lack of coverage) in clause 4.4.3.1. The MS shall delete the stored duplicate value of RPLMN once the PLMN selection has been completed successfully;

vii) If the MS’s E-UTRA capability is disabled as a result of successful registration (as described in 3GPP TS 24.301 [23A] clauses 5.5.1.3.4.2, 5.5.1.3.4.3, 5.5.3.3.4.2 and 5.5.3.3.4.3) and the selected CSG is not available on UTRAN radio access technology, the MS shall re-enable the E-UTRA capability, return to the stored duplicate PLMN selection mode and automatic CSG selection mode and use the stored duplicate value of RPLMN for further action; and

viii) If the MS’s E-UTRA capability is disabled as a result of performing the service request procedure (as described in 3GPP TS 24.301 [23A] clause 5.6.1.5), the selected CSG is not available on UTRAN radio access technology and the MS performed a CS call, then after the end of the call, the MS shall re-enable the E-UTRA capability, return to the stored duplicate PLMN selection mode and automatic CSG selection mode and use the stored duplicate value of RPLMN for further action.

4.4.3.2 User reselection

At any time the user may request the MS to initiate reselection and registration onto an available PLMN, according to the following procedures, dependent upon the operating mode.

4.4.3.2.1 Automatic Network Selection Mode

The MS selects and attempts registration on PLMN/access technology combinations, if available and allowable, in all of its bands of operation in accordance with the following order:

i) the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present);

ii) PLMN/access technology combinations contained in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) excluding the previously selected PLMN/access technology combination;

iii) PLMN/access technology combinations contained in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order) excluding the previously selected PLMN/access technology combination;

iv) other PLMN/access technology combinations with the received high quality signal in random order excluding the previously selected PLMN/access technology combination;

NOTE 1: High quality signal is defined in the appropriate AS specification.

v) other PLMN/access technology combinations, excluding the previously selected PLMN/access technology combination in order of decreasing signal quality or, alternatively, the previously selected PLMN/access technology combination may be chosen ignoring its signal quality;

vi) The previously selected PLMN/access technology combination.

The previously selected PLMN/access technology combination is the PLMN/access technology combination which the MS has selected prior to the start of the user reselection procedure.

NOTE 2: If the previously selected PLMN is chosen, and registration has not been attempted on any other PLMNs, then the MS is already registered on the PLMN, and so registration is not necessary.

The equivalent PLMNs list shall not be applied to the user reselection in Automatic Network Selection Mode.

When following the above procedure the requirements a), b), c), e), f), g), h), j), k), l), m), n), o) and p) in clause 4.4.3.1.1 apply: Requirement d) shall apply as shown below:

d) In iv, v, and vi, the MS shall search for all access technologies it is capable of before deciding which PLMN/access technology combination to select.

4.4.3.2.2 Manual Network Selection Mode

The Manual Network Selection Mode Procedure of clause 4.4.3.1.2 is followed.

4.4.3.2.3 Manual CSG selection

The procedure of clause 4.4.3.1.3 is followed.

4.4.3.3 In VPLMN

4.4.3.3.1 Automatic and manual network selection modes

4.4.3.3.1.1 Automatic and manual network selection modes when not registered for disaster roaming services

If the MS is in a VPLMN and not registered for disaster roaming services, the MS shall periodically attempt to obtain service on its HPLMN (if the EHPLMN list is not present or is empty) or one of its EHPLMNs (if the EHPLMN list is present) or a higher priority PLMN/access technology combinations listed in "user controlled PLMN selector" or "operator controlled PLMN selector" by scanning in accordance with the requirements that are applicable to i), ii) and iii) as defined in the Automatic Network Selection Mode in clause 4.4.3.1.1. For this purpose, a value of timer T may be stored in the SIM. The interpretation of the stored value depends on the radio capabilities supported by the MS:

– For an MS that does not support any of the following: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]);

a) if the MS is in a VPLMN through satellite NG-RAN access or satellite E-UTRAN access with a shared MCC, T is in the range 6 multiplied by integer M minutes to 8 multiplied by integer M hours in 6 multiplied by integer M minutes steps or T indicates that no periodic attempts shall be made. If no value for M is stored in the SIM, a default value of M equal to one is used; or

b) otherwise, T is either in the range 6 minutes to 8 hours in 6 minutes steps or it indicates that no periodic attempts shall be made. If no value for T is stored in the SIM, a default value of 60 minutes is used for T.

– For an MS that only supports any of the following or a combination of: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]), T is either in the range 2 hours to 240 hours, using 2 hour steps from 2 hours to 80 hours and 4 hour steps from 84 hours to 240 hours, or it indicates that no periodic attempts shall be made. If no value for T is stored in the SIM, a default value of 72 hours is used.

– For an MS that supports both:

a) any of the following or a combination of: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]); and

b) any access technology other than the following: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]),

T is interpreted depending on the access technology in use as specified below:

a) if the MS is using any of the following at the time of starting timer T: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]), T is either in the range 2 hours to 240 hours, using 2 hour steps from 2 hours to 80 hours and 4 hour steps from 84 hours to 240 hours, or it indicates that no periodic attempts shall be made. If no value for T is stored in the SIM, a default value of 72 hours is used; and

b) if the MS is not using any of the following at the time of starting timer T: EC-GSM-IoT, Category M1 or Category NB1 (as defined in 3GPP TS 36.306 [54]), T is either in the range 6 minutes to 8 hours in 6 minutes steps or it indicates that no periodic attempts shall be made. If the MS is using the satellite NG-RAN access technology or the satellite E-UTRAN access technology with a shared MCC at the time of starting timer T: T is in the range 6 multiplied by integer M minutes to 8 multiplied by integer M hours in 6 multiplied by integer M minutes steps. If no value for M is stored in the SIM, a default value of M equal to one is used. If no value for T is stored in the SIM, a default value of 60 minutes is used for T.

If the MS is configured with the MinimumPeriodicSearchTimer as specified in 3GPP TS 24.368 [50] or 3GPP TS 31.102 [40], the MS shall not use a value for T that is less than the MinimumPeriodicSearchTimer. If the value stored in the SIM, or the default value for T (when no value is stored in the SIM), is less than the MinimumPeriodicSearchTimer, then T shall be set to the MinimumPeriodicSearchTimer.

The MS does not stop timer T, as described in 3GPP TS 24.008 [23] and 3GPP TS 24.301 [23A], when it activates power saving mode (PSM) (see 3GPP TS 23.682 [27A]) or mobile initiated connection only mode (MICO) as described in 3GPP TS 24.501 [64].

The MS does not stop timer T, as described in 3GPP TS 24.008 [23] and 3GPP TS 24.301 [23A], when the access stratum is de-activated due to discontinuous coverage (see 3GPP TS 23.401 [58] and 3GPP TS 24.301 [23A]).

The MS can be configured for Fast First Higher Priority PLMN search as specified in 3GPP TS 31.102 [40] or 3GPP TS 24.368 [50]. Fast First Higher Priority PLMN search is enabled if the corresponding configuration parameter is present and set to enabled. Otherwise, Fast First Higher Priority PLMN search is disabled.

The attempts to access the HPLMN or an EHPLMN or higher priority PLMN shall be as specified below:

a) The periodic attempts shall only be performed in automatic mode when the MS is roaming, and not while the MS is attached for emergency bearer services, is registered for emergency services, has a PDU session for emergency services or has a PDN connection for emergency bearer services;

b) The MS shall make the first attempt after a period of at least 2 minutes and at most the time configured for T:

– only after switch on if Fast First Higher Priority PLMN search is disabled; or

– after switch on or upon selecting a VPLMN if Fast First Higher Priority PLMN search is enabled.

c) The MS shall make the following attempts if the MS is on the VPLMN at time T after the last attempt;

d) Periodic attempts shall only be performed by the MS while in idle mode or 5GMM-CONNECTED mode with RRC inactive indication (see 3GPP TS 24.501 [64]);

d1) Periodic attempts may be postponed while the MS is in power saving mode (PSM) (see 3GPP TS 23.682 [27A]) or when the access stratum is deactivated due to discontinuous coverage (see 3GPP TS 23.401 [58] and 3GPP TS 24.301 [23A]).

d2) Periodic attempts may be postponed while the MS is receiving eMBMS transport service in idle mode (see 3GPP TS 23.246 [68]).

d3) Periodic attempts may be postponed while the MS is receiving broadcast MBS service in idle mode (see 3GPP TS 23.247 [85]).

d4) Periodic attempts may be postponed till the next eDRX occasion while the MS is configured with eDRX.

d5) Periodic attempts may be postponed while the MS is in relaxed monitoring (see 3GPP TS 36.304 [43]).

d6) Periodic attempts may be postponed while the MS is in Mobile Initiated Connection Only mode (MICO).

e) If the HPLMN (if the EHPLMN list is not present or is empty) or a EHPLMN (if the list is present) or a higher priority PLMN is not found, the MS shall remain on the VPLMN.

f) In steps i), ii) and iii) of clause 4.4.3.1.1 the MS shall limit its attempts to access higher priority PLMN/access technology combinations to PLMN/access technology combinations of the same country as the current serving VPLMN, as defined in Annex B.

EXCEPTION: If the MS is in a VPLMN through satellite NG-RAN access or satellite E-UTRAN access with a shared MCC, the MS may attempt to access higher priority PLMN/access technology combinations irrespective of their MCC values.

EXCEPTION: If the MS is in a VPLMN, the MS may attempt to access higher priority PLMNs with a shared MCC with satellite NG-RAN access technology or satellite E-UTRAN access technology irrespective of their MCC values.

f1) In the case that the MS has a stored "Equivalent PLMNs" list the MS shall only select a PLMN if it is of a higher priority than those of the same country as the current serving PLMN which are stored in the "Equivalent PLMNs" list.

EXCEPTION: If the MS is in a VPLMN through satellite NG-RAN access or satellite E-UTRAN access with a shared MCC, the MS shall only select a PLMN if it is of a higher priority than those which are stored in the "Equivalent PLMNs" list.

EXCEPTION: If the MS is in a VPLMN, the MS shall only select a PLMN if it is of a higher priority than those of the same country as the current serving PLMN or those with a shared MCC with satellite NG-RAN access technology or satellite E-UTRAN access technology which are stored in the "Equivalent PLMNs" list.

g) Only the priority levels of Equivalent PLMNs of the same country as the current serving VPLMN, as defined in Annex B, and which are not in the list of "PLMNs where registration was aborted due to SOR" if the UE has a list of "PLMNs where registration was aborted due to SOR" shall be taken into account to compare with the priority level of a selected PLMN.

h) If the PLMN of the highest priority PLMN/access technology combination available is the current VPLMN, or one of the PLMNs in the "Equivalent PLMNs" list and is not in the list of "PLMNs where registration was aborted due to SOR" if the UE has a list of "PLMNs where registration was aborted due to SOR", the MS shall remain on the current PLMN/access technology combination.

i) In step iii) of clause 4.4.3.1.1 the MS shall consider PLMNs which are in the list of "PLMNs where registration was aborted due to SOR" as lowest priority, if the UE has a list of "PLMNs where registration was aborted due to SOR".

NOTE 1: As an MS implementation option, the MS can make an attempt when the timer TD, TE, TF, TG or TH expires and there is a PLMN/access technology combination which the MS could not select while the timer was running (e.g. the PLMN was in the list of PLMNs where voice service was not possible in E-UTRAN) that is higher priority than the current serving PLMN and belongs to the same country as the current serving PLMN, as defined in Annex B.

NOTE 2: As an MS implementation option, upon a transition in or out of international areas, a UE supporting satellite NG-RAN or satellite E-UTRAN can attempt to obtain service on a higher priority PLMN as defined in this clause. It is up to the UE implementation to determine when it is transitioning in and out of international areas. What constitutes an international area is out of scope of this specification and not the responsibility of 3GPP.

4.4.3.3.1.2 Automatic and manual network selection modes when registered for disaster roaming services

If the MS is registered for disaster roaming services, the MS shall periodically attempt to obtain service on an allowable PLMN of the same country as the current serving PLMN in accordance with the requirements as defined in the Automatic Network Selection Mode in clause 4.4.3.1.1.

If the MS is registered for disaster roaming services, timer T is either in the range 30 minutes to 40 hours in 30 minute steps, or it indicates that no periodic attempts shall be made. If no value for T is stored in the SIM, a default value of 60 minutes is used for T.

The attempts to obtain service on an allowable PLMN shall be as specified below:

a) The periodic attempts shall only be performed in automatic mode when the MS is registered for disaster roaming services and does not have a PDU session for emergency services;

a1) The MS shall make the first attempt after a period of at least 2 minutes and at most the time configured for T upon selecting a VPLMN for disaster roaming;

b) The MS shall make the following attempts if the MS is registered for disaster roaming services at time T after the last attempt;

c) The periodic attempts shall only be performed by the MS while in idle mode or 5GMM-CONNECTED mode with RRC inactive indication (see 3GPP TS 24.501 [64]);

d) The periodic attempts may be postponed:

– while the MS is in power saving mode (PSM) (see 3GPP TS 23.682 [27A]);

– while the MS is receiving eMBMS transport service in idle mode (see 3GPP TS 23.246 [68]);

– while the MS is receiving broadcast MBS service in idle mode (see 3GPP TS 23.247 [85]);

– till the next eDRX occasion while the MS is configured with eDRX;

– while the MS is in relaxed monitoring (see 3GPP TS 36.304 [43]);

– while the MS is in Mobile Initiated Connection Only mode (MICO).

e) The MS shall limit its attempts to access allowable PLMN/access technology combinations of the same country as the current serving VPLMN, as defined in Annex B.

EXCEPTION: If the MS is in a VPLMN through non-satellite access, the MS may attempt to access higher priority PLMNs with a shared MCC with satellite NG-RAN access technology or satellite E-UTRAN access technology.

4.4.3.3.2 Manual CSG selection

The procedure of clause 4.4.3.1.3 is followed.

4.4.3.4 Investigation Scan for higher prioritized PLMN

The support of this procedure is mandatory if the ME supports GSM COMPACT and otherwise optional.

An MS capable of both GSM voice and packet service shall, when indicated in the SIM, investigate if there is service from a higher prioritized PLMN not offering GSM voice service, either HPLMN (if the EHPLMN list is not present or is empty) or one of its EHPLMNs (if the EHPLMN list is present) or a PLMN in a "PLMN Selector with Access Technology " data file on the SIM.

The MS shall scan for PLMNs in accordance with the requirements described for automatic network selection mode in clause 4.4.3.1.1 that are applicable to i), ii) and iii) with the exception of requirement a) and b) in clause 4.4.3.1. Requirement a) and b) that are specified for automatic network selection mode in clause 4.4.3.1 shall be ignored during the investigation scan.

If indicated on the SIM, the investigation scan shall be performed:

i) After each successful PLMN selection and registration is completed, when the MS is in idle mode. This investigation scan may rely on the information from the already performed PLMN selection and may not necessarily require a rescan

ii) When the MS is unable to obtain normal service from a PLMN, (limited service state) see clause 3.5.

The investigation scan is restricted to automatic selection mode and shall only be performed by an MS that is capable of both voice and packet data. It shall only be performed if the selected PLMN is not already the highest prioritized PLMN in the current country. (HPLMN in home country, otherwise according to PLMN selector lists)

The MS shall return to RPLMN after the investigation scan is performed.

If a higher prioritized PLMN not offering GSM voice service is found, this shall be indicated to the user. The MS shall not select the PLMN unless requested by the user.

4.4.4 Abnormal cases

If there is no SIM in the MS, if there is an authentication failure, or if the MS receives an "IMSI unknown in HLR", "illegal ME" or "illegal MS" response to an LR request, then effectively there is no selected PLMN ("No SIM" state). In these cases, the states of the cell selection process are such that no PLMN selection information is used. Except when performing GPRS attach, EPS attach for emergency bearer services, an initial registration for emergency services, or EPS attach for access to RLOS, no further attempts at registration on any PLMN are made until the MS is switched off and on again, or a SIM is inserted. When performing GPRS attach, EPS attach for emergency bearer services, an initial registration for emergency services or EPS attach for access to RLOS, the PLMN of the current serving cell is temporarily considered as the selected PLMN.

When in Automatic Network Selection mode and the MS is in the "not updated" state with one or more suitable cells to camp on; then after the maximum allowed unsuccessful LR requests (controlled by the specific attempt counters) the MS may continue (or start if it is not running) the user reselection procedure of clause 4.4.3.2.1.

A multi mode MS that also supports 3GPP2 access technology may fall back to 3GPP2 mode if no SIM is inserted.

4.4.5 Roaming not allowed in this LA or TA

If in either PLMN selection mode the LR response "Roaming not allowed in this LA" or "Roaming not allowed in this TA" is received:

The PLMN Automatic or Manual Mode Selection Procedure of clause 4.4.3.1 are followed, depending on whether the MS is in automatic or manual mode.

4.4.6 Steering of roaming

If the MS receives a USAT REFRESH command qualifier (3GPP TS 31.111 [41]) of type "Steering of Roaming", the MS shall:

a) replace the highest priority entries in the "Operator Controlled PLMN Selector with Access Technology" list stored in the ME with the list provided in the REFRESH command;

b) delete the PLMNs identified by the list in the REFRESH command from the Forbidden PLMN list and from the Forbidden PLMNs for GPRS service list, if they are present in these lists. This includes any information stored in the SIM and the ME internal memory;

c) take the new information into account in subsequent attempts to access a higher priority PLMN; and

d) attempt to obtain service on a higher priority PLMN as specified in clause 4.4.3.3 by acting as if timer T that controls periodic attempts has expired.

In order to avoid unnecessary signalling, the network operator should avoid repeatedly using steering of roaming of a particular MS.

4.5 Location registration process

4.5.1 General

When the MS is switched on and capable of services requiring registration, the action taken by the location registration process is as follows:

a) SIM present and no LR needed (because of the status of the stored registration area identity and "attach" flag): The MS is in the update state "Updated";

b) SIM present and LR needed: A LR request is made;

c) No SIM present: The MS enters the update state "Idle, No IMSI".

In case b) above, and subsequently whenever a LR request is made, the MS enters a state depending on the outcome of the LR request, as listed in clause 4.3.3 above. In case c) the GPRS and the non-GPRS update state enters "Idle, No IMSI".

Whenever the MS goes to connected mode and then returns to idle mode again, the MS selects the appropriate state.

A multi mode MS that also supports 3GPP2 access technology may fall back to 3GPP2 mode if no SIM is inserted.

4.5.2 Initiation of Location Registration

An LR request indicating Normal Updating is made when, in idle mode,

– the MS changes cell while the update status is "NOT UPDATED"; (for MS capable of GPRS and non-GPRS services when at least one of both update statuses is "NOT UPDATED")

– the MS detects that it has entered a new registration area, i.e., when the received registration area identity differs from the one stored in the MS, and the LAI, TAI or PLMN identity is not contained in any of the lists of "forbidden location areas for roaming", "forbidden tracking areas for roaming", "5GS forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "5GS forbidden tracking areas for regional provision of service", "forbidden PLMNs for GPRS service" or "forbidden PLMNs" respectively, while being in one of the following update statuses:

– UPDATED;

– NOT UPDATED;

– ROAMING NOT ALLOWED.

– the MS detects that it has entered a new registration area, i.e., when the received registration area identity differs from the one stored in the MS, and the MS is attached for access to RLOS;

– the MS detects that it has entered a registration area that has the same identity as the one stored in the MS, while the update status is "ROAMING NOT ALLOWED", and

the LAI, TAI or PLMN identity is not contained in any of the lists of "forbidden location areas for roaming", "forbidden tracking areas for roaming", "5GS forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "5GS forbidden tracking areas for regional provision of service", "forbidden PLMNs for GPRS service" or "forbidden PLMNs" respectively; and

– if the selected cell is a satellite NG-RAN cell or a satellite E-UTRAN cell, it does not fulfil the conditions related to the list of "PLMNs not allowed to operate at the present UE location" as defined in clause 3.1, i.e. it is considered as candidate for PLMN selection.

– the periodic location updating timer expires while the non-GPRS update status is "NOT UPDATED" (triggers location updating);

– the periodic routing area update timer expires while the GPRS update status is "NOT UPDATED" (triggers routing area update);

– the periodic tracking area update timer expires while the EPS update status is "NOT UPDATED" (triggers tracking area update);

– the periodic registration update timer expires while the 5GS update status is "NOT UPDATED" (triggers mobility and periodic registration update procedure);

– a manual network reselection has been performed, an acceptable cell of the selected PLMN or the selected SNPN is present, and the MS is not in the update status "UPDATED" on the selected PLMN or the selected SNPN; or

– emergency bearer services over packet services are requested by upper layers.

An MS which is attached for PS services other than RLOS and enters a new PLMN shall perform a routing area update or a tracking area update or an MS which is registered via NG-RAN and enters a new PLMN or SNPN shall perform a registration update if the following conditions are fulfilled:

a) if the MS:

1) does not operate in SNPN access mode, is in S1 mode or N1 mode and the currently stored TAI list does not contain the TAI of the current serving cell; or

2) operates in SNPN access mode;

b) the LAI, TAI or PLMN identity of the current serving cell is not contained in any of the lists "forbidden location areas for roaming", "forbidden tracking areas for roaming", "5GS forbidden tracking areas for roaming", "forbidden location areas for regional provision of service", "forbidden tracking areas for regional provision of service", "5GS forbidden tracking areas for regional provision of service", "forbidden PLMNs for GPRS service" or "forbidden PLMNs", or the MS has a PDN connection for emergency bearer services, or the MS has a PDU session for emergency services;

b1) if the selected cell is a satellite NG-RAN cell or a satellite E-UTRAN cell, it does not fulfil the conditions related to the list of "PLMNs not allowed to operate at the present UE location" as defined in clause 3.1, i.e. it is considered as candidate for PLMN selection; and

c) the current update state is different from "Idle, No IMSI"; and

1) the MS is configured to perform the attach procedure with IMSI at PLMN change (see "AttachWithIMSI" leaf of the NAS configuration MO in 3GPP TS 24.368 [50] or USIM file NAS_CONFIG in 3GPP TS 31.102 [40]) and the new PLMN is the registered PLMN or an equivalent PLMN; or

2) the MS is not configured to perform the attach procedure with IMSI at PLMN change.

An MS which is attached for access to RLOS and enters a new PLMN shall perform tracking area update if the following condition is fulfilled:

– the currently stored TAI list does not contain the TAI of the current serving cell.

If the new PLMN the MS has entered is neither the registered PLMN nor an equivalent PLMN, an MS which is attached for PS services and configured to perform the attach procedure with IMSI at PLMN change (see "AttachWithIMSI" leaf of the NAS configuration MO in 3GPP TS 24.368 [50] or USIM file NASCONFIG in 3GPP TS 31.102 [40]) shall perform an attach procedure using IMSI as mobile identity.

An LR request indicating periodic location updating is made when, in idle mode, the periodic location updating timer expires while the non-GPRS update status is "UPDATED".

An LR request indicating periodic routing area update is made when the periodic routing area update timer expires while the GPRS update status is "UPDATED", except when the MS is attached for emergency bearer services.

An LR request indicating periodic tracking area update is made when the periodic tracking area update timer expires while the EPS update status is "UPDATED", except when the MS is attached for emergency bearer services.

An LR request indicating Periodic Registration Updating is made when the periodic registration timer expires while the 5GS update status is "UPDATED", except when the MS is registered for emergency services.

An LR request indicating IMSI attach is made when the MS is activated in the same location area in which it was deactivated while the non-GPRS update status is "UPDATED", and the system information indicates that IMSI attach/detach shall be used.

A GPRS attach is made by a GPRS MS when activated and capable of services which require registration. A GPRS attach may only be performed if the selected PLMN is not contained in the list of "forbidden PLMNs for GPRS service". Depending on system information about GPRS network operation mode MSs operating in MS operation mode A or B perform combined or non-combined location registration procedures. When the combined routing area update or GPRS attach is accepted with indication "MSC not reachable" or is not answered the MS performs also the corresponding location updating procedure or falls back to a GPRS only MS. When the combined routing area update or GPRS attach is rejected with cause "GPRS not allowed" the GPRS update status is "ROAMING NOT ALLOWED" and the MS performs the corresponding location updating procedure.

An LR request indicating Disaster Roaming registration updating is made when the MS supporting MINT needs to register to the PLMN offering disaster roaming services for the first time.

Furthermore, an LR request indicating normal location updating is also made when the response to an outgoing request shows that the MS is unknown in the VLR or SGSN, respectively.

Table 2 in clause 5 summarizes the events in each state that trigger a new LR request. The actions that may be taken while being in the various states are also outlined in table 2.

A GPRS MS which is both IMSI attached for GPRS and non-GPRS services and which is capable of simultaneous operation of GPRS and non-GPRS services shall perform routing area update in connected mode when it has entered a new routing area which is not part of a LA contained in the list of "forbidden location areas for roaming" or "forbidden location areas for regional provision of service".

4.5.3 Periodic Location Registration

A Periodic Location Updating timer (for non-GPRS operation), a Periodic Routing Area Update timer (for GPRS operation), a Periodic Tracking Area Update timer (for EPS operation) and a Periodic Registration Update timer (for 5GS operation) with the following characteristics shall be implemented in the MS (MS shall implement all timers corresponding to supported operations):

i) Upon switch on of the MS or when the system information indicates that periodic location registration shall be applied, and the timer is not running, the timer shall be loaded with a random value between 0 and the broadcast or signalled time‑out value and started.

ii) The time‑out value for the periodic location updating timer shall be within the range of 1 deci‑hour to 255 deci‑hours with a granularity of 1 deci‑hour.

iii) When the timer reaches its expiry value, it shall be initiated with respect to the relevant time‑out value, and the MS shall initiate the periodic location registration corresponding to the expired timer. If the MS is attached for emergency bearer services or the MS is registered for emergency services, the MS shall locally detach instead of performing periodic location registration.

iv) The periodic location updating timer shall be prevented from triggering periodic location updating during connected mode. When the MS returns to idle mode, the periodic location updating timer shall be initiated with respect to the broadcast time‑out value, then started. Thereafter, the procedure in iii) shall be followed.

v) The periodic routing area update timer shall be prevented from triggering the periodic routing area update during Ready state. At transition from Ready to Standby state the periodic routing area update timer shall be initiated with respect to its time‑out value, then started. Thereafter, the procedure in iii) shall be followed.

vi) If the MS performs a successful combined routing area update the periodic location updating timer shall be prevented from triggering the periodic location updating until the MS starts using location updating procedure, for example because of a changed network operation mode or the MS uses non-GPRS services only.

vii) When a change in the time‑out value occurs (at a change of serving cell or a change in the broadcast time‑out value or a change in the signalled time-out value), the related timer shall be reloaded so that the new time to expiry will be: "old time to expiry" modulo "new time‑out value".

viii) The periodic tracking area update timer shall be prevented from triggering periodic tracking Area updating during connected mode. When the MS returns to idle mode, the periodic tracking area update timer shall be initiated with respect to the signalled time‑out value, then started. Thereafter, the procedure in iii) shall be followed.

ix) The periodic registration update timer shall be prevented from triggering periodic registration updating during connected mode. If periodic timer is not running due to Strictly periodic registration feature, when the MS returns to idle mode, the periodic registration update timer shall be initiated with respect to the signalled time‑out value, then started. Thereafter, the procedure in iii) shall be followed.

4.5.4 IMSI attach/detach operation

The system information will contain an indicator indicating whether or not IMSI attach/detach operation is mandatory to use in the cell. The MS shall operate in accordance with the received value of the indicator.

A GPRS MS shall perform GPRS attach/detach procedures independent of the value of the IMSI attach/detach indicator. When a GPRS MS has to perform IMSI attach/detach independent of GPRS procedures (for example GPRS network operation mode 2) the handling described in the clause above applies.

When IMSI attach/detach operation applies, an MS shall send the IMSI detach message to the network when the MS is powered down or the SIM is removed while the update status is "UPDATED". The IMSI detach message will not be acknowledged by the network.

When the MS returns to the active state, the MS shall perform an LR request indicating IMSI attach, provided that the MS still is in the same registration area. If the registration area has changed, an LR request indicating normal location updating according to clause 4.5.2 shall be performed.

4.5.5 No Suitable Cells In Location Area

If during location registration the LR response "No Suitable Cells In Location Area" or "No Suitable Cells In Tracking Area" is received:

– The MS shall attempt to find another LA or TA of the same PLMN, the same SNPN, an equivalent PLMN or an equivalent SNPN, on which it received the LR response. If the MS is able to find another LA or TA it shall attempt registration. If the MS is unable to find an LA or TA, the PLMN Automatic or Manual Mode Selection Procedure of clause 4.4.3.1 or the SNPN Automatic or Manual Mode Selection Procedure of clause 4.9.3.1 shall be followed, depending on whether the MS is in automatic or manual mode and whether the MS operates in SNPN access mode.

4.6 Service indication (A/Gb mode only)

This is an indication to the user that service or CTS service is available.

The service indication should be set if the following conditions are all satisfied:

a) Cell Selection: Camped on a suitable cell and in updated state, or in connected mode having been camped on a suitable cell.

b) Location registration: In updated state, for MSs capable of services requiring registration.

A specific CTS service indication should be set when the CTS MS is attached to a CTS FP.

However due to the fact that there may be some transitory changes of state, the service indication is permitted to continue to be set for up to 10 seconds after the above conditions cease to be met. Also the service indication is permitted to take up to 1 second to be set after the above conditions are met.

4.7 Pageability of the mobile subscriber

An MS is required to listen to all paging messages that could address it (see 3GPP TS 45.002 [24]), when the following conditions are all satisfied:

– A SIM is inserted;

– The MS is camped on a cell;

– The MS is not in state "Idle, No IMSI"; and

– The MS is not performing the task to search for available PLMNs or available SNPNs. (Whenever possible during this task, the MS should listen for paging.). However, when the MS is camped on a cell, is registered in a PLMN and is performing its regular search for a higher priority PLMN, as specified in 3GPP TS 22.011 [9], then it shall listen to all paging messages that could address it.

NOTE: In A/Gb mode, during cell reselection there is a certain period when the MS is no longer camped on the old cell but must decode the full BCCH, CPBCCH or EC-BCCH before camping on the new cell. This leads to a period of slightly more than 8 51 frame multiframes when the MS will not necessarily be pageable (full BCCH or CPBCCH is decoded) or up to 32 51 frame multiframes when the MS will not necessarily be pageable (full EC-BCCH is decoded).

4.8 MM Restart Procedure

In some cases, e.g. on change of SIM data, there is a need for the MM to be restarted without the need for user intervention.

To perform the procedure the MS shall behave as if the SIM is removed and afterwards a new SIM is inserted.

4.9 SNPN selection process

4.9.1 General

The MS operating in SNPN access mode shall perform the SNPN selection process.

The MS not operating in SNPN access mode shall not perform the SNPN selection process.

There are two SNPN selection modes – automatic SNPN selection mode and manual SNPN selection mode.

In the SNPN selection process, the MS shall consider only the access networks of the NG-RAN access technology.

4.9.2 Registration on an SNPN

The MS shall perform registration on the SNPN if the MS is capable of services which require registration. In both automatic SNPN selection mode and manual SNPN selection mode, the concept of registration on an SNPN is used. An MS successfully registers on an SNPN if:

a) the MS has found a suitable cell of the SNPN to camp on; and

b) an LR request from the MS has been accepted in the registration area of the cell on which the MS is camped.

4.9.3 SNPN selection

4.9.3.0 General

The ME is configured with a "list of subscriber data" containing zero or more entries. Each entry of the "list of subscriber data" consists of:

a) a subscriber identifier in the form of a SUPI with the SUPI format "network specific identifier" containing a network-specific identifier or with the SUPI format "IMSI" containing an IMSI, except when the subscribed SNPN uses:

1) the EAP based primary authentication and key agreement procedure using the EAP-AKA’; or

2) the 5G AKA based primary authentication and key agreement procedure;

NOTE 1: A subscriber identifier in the form of a SUPI with the SUPI format "network specific identifier" containing a network-specific identifier or with the SUPI format "IMSI" containing an IMSI, is available in USIM if the subscribed SNPN uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure.

NOTE 2: If the MS supports access to an SNPN using credentials from a credentials holder and is configured with the SNPN selection parameters as described in h), the subscriber identifier in the form of a SUPI configured in the ME or the USIM needs to be:

– with the SUPI format "network specific identifier"; or

– with the SUPI format "IMSI", if the subscribed SNPN has an assigned PLMN ID.

b) credentials except when the subscribed SNPN uses:

1) the EAP based primary authentication and key agreement procedure using the EAP-AKA’; or

2) the 5G AKA based primary authentication and key agreement procedure.

If the MS supports access to an SNPN using credentials from a credentials holder, the credentials can include an indication to use MSK for derivation of K_AUSF after success of primary authentication and key agreement procedure;

NOTE 3: Credentials are available in USIM if the subscribed SNPN uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure. If the MS supports access to an SNPN using credentials from a credentials holder, credentials available in USIM can include an indication to use MSK for derivation of K_AUSF after success of primary authentication and key agreement procedure.

ba) optionally, a routing indicator, except when the subscribed SNPN uses:

1) the EAP based primary authentication and key agreement procedure using the EAP-AKA’; or

2) the 5G AKA based primary authentication and key agreement procedure;

NOTE 3A: Routing indicator is available in USIM if the subscribed SNPN uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure.

bb) optionally, the protection scheme identifier as specified in 3GPP TS 33.501 [66], except when the subscribed SNPN uses:

1) the EAP based primary authentication and key agreement procedure using the EAP-AKA’; or

2) the 5G AKA based primary authentication and key agreement procedure;

If the protection scheme identifier is configured in the entry of the "list of subscriber data" and not set to "null-scheme", the entry of the "list of subscriber data" also contains the home network public key and the home network public key identifier as specified in in 3GPP TS 33.501 [66];

NOTE 3B: The protection scheme identifier, the home network public key and the home network public key identifier are available in USIM if the subscribed SNPN uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure.

c) an SNPN identity of the subscribed SNPN;

d) optionally, the unified access control configuration indicating for which access identities (see 3GPP TS 24.501 [64]) the ME is configured, when the MS accesses an SNPN using the entry.

Access identity 11 or 15, if configured, is applicable for the MS only in the subscribed SNPN.

Access identity 12, 13 or 14, if configured, is applicable for the MS only:

1) in the subscribed SNPN; and

2) if the MCC of the SNPN identity of the subscribed SNPN is not the MCC of value 999, in the non-subscribed SNPNs of the same country as the subscribed SNPN;

Access identity 1 or 2, if configured, is applicable for the MS only:

1) in the subscribed SNPN;

2) if the MCC of the SNPN identity of the subscribed SNPN is not the MCC of value 999, in the non-subscribed SNPNs of the same country as the subscribed SNPN; and

3) in an SNPN equivalent to the subscribed SNPN;

e) zero or more sets of pre-configured URSP rules (see 3GPP TS 24.526 [77]), each set for the subscribed SNPN or a non-subscribed SNPN;

f) optionally, the default configured NSSAI (see 3GPP TS 24.501 [64]);

g) optionally, if the MS supports access to an SNPN using credentials from a credentials holder, the SNPN selection parameters, consisting of:

1) a user controlled prioritized list of preferred SNPNs, where each entry contains an SNPN identity;

2) a credentials holder controlled prioritized list of preferred SNPNs, where each entry contains an SNPN identity; and

3) a credentials holder controlled prioritized list of Group IDs for Network Selection (GINs); and

NOTE 4: How the ME is configured with the "list of subscriber data" is out of scope of 3GPP in this release of the specification.

NOTE 5: Multiple entries can include the same subscriber identifier and credentials.

NOTE 6: Handling of more than one entry with the same SNPN identity is left up to MS implementation.

NOTE 7: Handling of the case when the subscribed SNPN uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure and the MS has multiple valid USIMs (3GPP TS 31.102 [40]) is left up to MS implementation.

NOTE 8: To enable UE mobility between SNPNs in 5GMM-IDLE mode, SNPN identities in the credentials holder controlled prioritized list of preferred SNPNs are assumed to be globally-unique SNPN identities.

h) optionally:

1) an indication of whether the MS shall ignore all warning messages received in the subscribed SNPN; and

2) an indication of whether the MS shall ignore all warning messages received in an SNPN other than the subscribed SNPN.

NOTE 9: The ME can be configured with an indication to use anonymous SUCI associated with an entry of "list of subscriber data" when the EAP method associated with the credentials of the entry supports SUPI privacy at the EAP layer.

NOTE 10: Anonymous SUCI is not used if the subscribed SNPN of the entry uses the EAP based primary authentication and key agreement procedure using the EAP-AKA’ or the 5G AKA based primary authentication and key agreement procedure.

The MS which supports onboarding services in SNPN shall be pre-configured with default UE credentials for primary authentication and may be pre-configured with onboarding SNPN selection information. Contents of the onboarding SNPN selection information are MS implementation specific. Contents of default UE credentials for primary authentication are out of scope of 3GPP.

Additionally, if the MS has a USIM with a PLMN subscription, the ME may be configured with the SNPN selection parameters associated with the PLMN subscription, consisting of:

a) a user controlled prioritized list of preferred SNPNs, where each entry contains an SNPN identity;

b) a credentials holder controlled prioritized list of preferred SNPNs, where each entry contains an SNPN identity; and

c) a credentials holder controlled prioritized list of GINs;

and with the following configuration parameters associated with the PLMN subscription:

a) zero or more sets of pre-configured URSP rules (see 3GPP TS 24.526 [77]), each set for the HPLMN or a non-subscribed SNPN.

NOTE 11: To enable MS mobility between SNPNs in 5GMM-IDLE mode, SNPN identities in the credentials holder controlled prioritized list of preferred SNPNs are assumed to be globally-unique SNPN identities.

NOTE 12: If an MS accesses an SNPN using the PLMN subscription, access identity 1, 2, 12, 13, or 14 is configured in the USIM of the MS, and the SNPN is of the same country as the HPLMN, then the configured access identity 1, 2, 12, 13, or 14 is applicable for the MS.

NOTE 13: If an MS accesses an SNPN using the PLMN subscription, an indication of whether the MS shall ignore all warning messages in an SNPN is configured in the USIM of the MS.

NOTE 14: Handling of URSP rules is specified in 3GPP TS 24.526 [77].

The MS shall maintain a list of "temporarily forbidden SNPNs" and a list of "permanently forbidden SNPNs" in the ME. Each entry of those lists consists of an SNPN identity. If the MS supports access to an SNPN using credentials from a credentials holder, the MS shall maintain one list of "temporarily forbidden SNPNs" and one list of "permanently forbidden SNPNs" per entry of the "list of subscriber data" or the PLMN subscription, and shall use the lists associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription. In addition, if the MS supports onboarding services in SNPN, a "permanently forbidden SNPNs" list for onboarding services and a "temporarily forbidden SNPNs" list for onboarding services shall be maintained.

The MS shall add an SNPN to the list of "temporarily forbidden SNPNs" (for onboarding services, if the MS is registered for onboarding services in SNPN or performing initial registration for onboarding services in SNPN) which is, if the MS supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if a message with cause value #74 "Temporarily not authorized for this SNPN" (see 3GPP TS 24.501 [64]) is received by the MS in response to an LR request from the SNPN. In addition, if:

– the message is integrity-protected; or

– the message is not integrity-protected, and the value of the SNPN-specific attempt counter for that SNPN is equal to the MS implementation specific maximum value as defined in 3GPP TS 24.501 [64];

then the MS shall start an MS implementation specific timer not shorter than 60 minutes.

The MS shall remove an SNPN from the list of "temporarily forbidden SNPNs" (for onboarding services, if the MS is registered for onboarding services in SNPN or performing initial registration for onboarding services in SNPN) which is, if the MS supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if:

a) there is a successful LR after a subsequent manual selection of the SNPN;

b) the MS implementation specific timer not shorter than 60 minutes expires;

c) the MS is configured to use timer T3245 and timer T3245 expires;

d) the MS is not configured to use timer T3245, the timer T3247 expires and the value of the SNPN-specific attempt counter for that SNPN is less than the MS implementation specific maximum value as defined in 3GPP TS 24.501 [64];

e) the MS is switched off;

f) an entry of the "list of subscriber data" with the subscribed SNPN identity identifying the SNPN is updated or the USIM is removed if:

– EAP based primary authentication and key agreement procedure using EAP-AKA’; or

– 5G AKA based primary authentication and key agreement procedure;

was performed in the selected SNPN; or

g) the selected entry of the "list of subscriber data" is updated or USIM is removed for the selected PLMN subscription.

If an SNPN is removed from the list of "temporarily forbidden SNPNs" list, the MS shall stop the MS implementation specific timer not shorter than 60 minutes, if running.

The MS shall add an SNPN to the list of "permanently forbidden SNPNs" (for onboarding services, if the MS is registered for onboarding services in SNPN or performing initial registration for onboarding services in SNPN) which is, if the MS supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if a message with cause value #75 "Permanently not authorized for this SNPN", #3 "Illegal UE" (applicable in an onboarding SNPN only), #6 "Illegal ME" (applicable in an onboarding SNPN only), or #7 "5GS services not allowed" (applicable in an onboarding SNPN only) (see 3GPP TS 24.501 [64]) is received by the MS in response to an LR request from the SNPN.

The MS shall remove an SNPN from the list of "permanently forbidden SNPNs" (for onboarding services, if the MS is registered for onboarding services in SNPN or performing initial registration for onboarding services in SNPN) which is, if the MS supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if:

a) there is a successful LR after a subsequent manual selection of the SNPN;

b) the MS is configured to use timer T3245 and timer T3245 expires;

c) the MS is not configured to use timer T3245, the timer T3247 expires and the value of the SNPN-specific attempt counter for that SNPN is less than the MS implementation specific maximum value as defined in 3GPP TS 24.501 [64];

d) an entry of the "list of subscriber data" with the subscribed SNPN identity identifying the SNPN is updated or the USIM is removed if:

– EAP based primary authentication and key agreement procedure using EAP-AKA’; or

– 5G AKA based primary authentication and key agreement procedure;

was performed in the selected SNPN; or

e) the selected entry of the "list of subscriber data" is updated or USIM is removed for the selected PLMN subscription.

When the MS reselects to a cell in a shared network, and the cell is a suitable cell for multiple SNPN identities received in the broadcast information as specified in 3GPP TS 38.331 [65], the AS indicates these multiple SNPN identities to the NAS according to 3GPP TS 38.304 [61]. The MS shall select one of these SNPNs. If the registered SNPN is available among these SNPNs, the MS shall not select a different SNPN.

The MS operating in SNPN access mode shall maintain one or more lists of "5GS forbidden tracking areas for roaming", each associated with an SNPN and, if the MS supports access to an SNPN using credentials from a credentials holder, entry of the "list of subscriber data" or the PLMN subscription. The MS shall use the list of "5GS forbidden tracking areas for roaming" associated with the selected SNPN and, if the MS supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription. If the MS selects a new SNPN, the MS shall keep the list of "5GS forbidden tracking areas for roaming" associated with the previously selected SNPN and, if the MS supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription. If the number of the lists to be kept is higher than supported, the MS shall delete the oldest stored list of "5GS forbidden tracking areas for roaming". The MS shall delete all lists of "5GS forbidden tracking areas for roaming", when the MS is switched off and periodically (with period in the range 12 to 24 hours). The MS shall delete the list of "5GS forbidden tracking areas for roaming" associated with an SNPN:

a) when the entry with the subscribed SNPN identifying the SNPN in the "list of subscriber data" is updated;

b) when the USIM is removed if:

– the EAP based primary authentication and key agreement procedure using the EAP-AKA’; or

– the 5G AKA based primary authentication and key agreement procedure;

was performed in the selected SNPN; or

c) if the MS supports access to an SNPN using credentials from a credentials holder, when the list of "5GS forbidden tracking areas for roaming" is associated with:

– the entry of the "list of subscriber data" and the entry of the "list of subscriber data" is updated; or

– the PLMN subscription and USIM is removed.

NOTE 15: The number of the lists of "5GS forbidden tracking areas for roaming" supported by the MS is MS implementation specific.

If a message with cause value #15 (see 3GPP TS 24.501 [64]) is received by an MS operating in SNPN access mode, the TA is added to the list of "5GS forbidden tracking areas for roaming" of the selected SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription,. The MS shall then search for a suitable cell in the same SNPN but belonging to a TA which is not in the "5GS forbidden tracking areas for roaming" list of the selected SNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, the selected entry of the "list of subscriber data" or the selected PLMN subscription.

The MS should maintain a 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". When the MS disables its N1 mode capability due to receipt of a reject from an SNPN with 5GMM cause #27 "N1 mode not allowed":

– the MS should add the SNPN identity of the SNPN which sent a reject with 5GMM cause #27 "N1 mode not allowed" to the list of SNPNs for which the N1 mode capability was disabled and should start timer TJ if timer TJ is not already running. The number of SNPNs for which the N1 mode capability was disabled that the MS can store is implementation specific, but it shall be at least one. The value of timer TJ is MS implementation specific;

– in automatic SNPN selection, the MS shall not select an SNPN for which the N1 mode capability was disabled as SNPN selection candidates, unless no other SNPN is available;

– if the MS is not configured to use timer T3245, the MS maintains a list of SNPN-specific attempt counters for 3GPP access as specified in 3GPP TS 24.501 [64], and T3247 expires, then the MS removes for each SNPN-specific attempt counter for 3GPP access that has a value greater than zero and less than the MS implementation-specific maximum value the respective SNPN from the list of SNPNs for which the N1 mode capability was disabled, as specified in clause 5.3.20.3 in 3GPP TS 24.501 [64]; and

– the MS shall delete stored information on SNPNs for which the N1 mode capability was disabled when the MS is switched off, the USIM is removed, the entries of the "list of subscriber data" for the SNPNs are updated, or timer TJ expires.

NOTE 16: The expiry of timer TJ does not cause a reset of the SNPN-specific attempt counters for 3GPP access (see 3GPP TS 24.501 [64]).

If the MS does not support access to an SNPN using credentials from a credentials holder, the MS should maintain a list of SNPNs where the N1 mode capability was disabled because IMS voice was not available and the MS’s usage setting was "voice centric". If the MS supports access to an SNPN using credentials from a credentials holder, the MS should maintain one or more lists of SNPNs where the N1 mode capability was disabled because IMS voice was not available and the MS’s usage setting was "voice centric", each associated with selected entry of the "list of subscriber data" or the PLMN subscription. When the MS disables its N1 mode capability due to IMS voice not available and the MS’s usage setting was "voice centric":

– the MS should add the SNPN identity of the SNPN to the list of SNPNs where voice service was not possible in N1 mode and should start timer TK if timer TK is not already running. The number of SNPNs that the MS can store where voice services is not possible is implementation specific, but it shall be at least one. The value of timer TK is MS implementation specific;

– in automatic SNPN selection the MS shall not consider SNPNs where voice service was not possible in N1 mode as SNPN selection candidates, unless no other SNPN is available; and

– the MS shall delete stored information on SNPNs where voice service was not possible in N1 mode when the MS is switched off, the USIM is removed, the entries of the "list of subscriber data" for the SNPNs are updated, or timer TK expires.

The MS may support equivalent SNPNs. If the MS supports equivalent SNPNs, the ME shall store up to one list of equivalent SNPNs:

– per entry of "list of subscriber data"; or

– per the PLMN subscription, if the MS supports access to an SNPN using credentials from a credentials holder.

SNPNs in the list of equivalent SNPNs associated with the selected entry of "list of subscriber data" or the selected PLMN subscription shall be regarded by the MS as equivalent to each other for SNPN selection, cell selection, and cell re-selection. The list of equivalent SNPNs associated with the selected entry of "list of subscriber data" or the selected PLMN subscription is created, replaced or deleted at the end of each registration procedure. The stored list consists of a list of equivalent SNPNs as provided by the network plus the SNPN identity of the registered SNPN that provided the list. When the MS is switched off, the MS shall keep the stored list(s) so that they can be used for SNPN selection after switch on. The MS shall delete the stored list associated with an entry of "list of subscriber data" or the PLMN subscription, when the USIM is removed, the associated entry of "list of subscriber data" is updated, or the MS registered for emergency services deregisters.

Editor’s note: (WI: eNPN_Ph2, CR: 1003) when the MS is registering or is registered for onboarding services in SNPN, it is FFS whether list of equivalent SNPNs is needed.

4.9.3.1 At switch‑on or recovery from lack of coverage

4.9.3.1.0 General

At switch on, following recovery from lack of coverage, or when the MS starts operating in the SNPN access mode, the MS selects the registered SNPN or an equivalent SNPN (if it is available) using NG-RAN access technology and if necessary (in the case of recovery from lack of coverage, see clause 4.5.2) attempts to perform an LR.

NOTE 1: The MS in automatic SNPN selection mode can end the SNPN search procedure once the registered SNPN or an equivalent SNPN is found on NG-RAN access technology.

NOTE 2: An MS in automatic SNPN selection mode can use location information to determine which SNPNs can be available in its present location.

If successful registration is achieved, the MS indicates the selected SNPN.

If there is no registered SNPN, or registration is not possible due to the SNPN and all equivalent SNPNs, if any, being unavailable or registration failure, unless the MS needs to select an SNPN for onboarding services in SNPN, the MS follows the procedure in clause 4.9.3.1.1 or clause 4.9.3.1.2 depending on its SNPN selection mode. If the MS needs to select an SNPN for onboarding services in SNPN, the MS follows the procedure in clause 4.9.3.1.3 or clause 4.9.3.1.4 depending on its SNPN selection mode for onboarding services in SNPN. At switch on, the MS shall use the SNPN selection mode and the SNPN selection mode for onboarding services in SNPN that were used before switching off.

NOTE 3: If successful registration is achieved, then the current serving SNPN becomes the registered SNPN and the MS does not store the previous registered SNPN for later use.

If registration is not possible on recovery from lack of coverage due to the registered SNPN and all equivalent SNPNs, if any, being unavailable, an MS may, optionally, continue looking for the registered SNPN or an equivalent SNPN for an implementation dependent time.

NOTE 4: An MS registered to an SNPN should behave as described above only if one or more PDU sessions are currently active.

4.9.3.1.1 Automatic SNPN selection mode procedure

If:

– there is at least one entry in the "list of subscriber data"; or

– there is zero or more entries in the "list of subscriber data", the MS has a USIM with a PLMN subscription and the ME is provisioned with the SNPN selection parameters associated with the PLMN subscription,

the MS shall select one entry in the "list of subscriber data", if any, or the PLMN subscription, if any, to be used for automatic SNPN selection. How the MS selects the entry in the "list of subscriber data" or the PLMN subscription is MS implementation specific.

The MS selects an SNPN, if available and allowable, in the following order:

a) the SNPN with which the UE was last registered or an equivalent SNPN;

b) the SNPN identified by an SNPN identity of the subscribed SNPN in the selected entry of the "list of subscriber data" in the ME, if any;

c) if the MS supports access to an SNPN using credentials from a credentials holder, using the SNPN selection parameters in the selected entry of the "list of subscriber data" or associated with the selected PLMN subscription:

1) each SNPN which broadcasts the indication that access using credentials from a credentials holder is supported and which is identified by an SNPN identity contained in the user controlled prioritized list of preferred SNPNs (in priority order);

2) each SNPN which broadcasts the indication that access using credentials from a credentials holder is supported and which is identified by an SNPN identity contained in the credentials holder controlled prioritized list of preferred SNPNs (in priority order);

3) each SNPN which broadcasts the indication that access using credentials from a credentials holder is supported and which broadcast a GIN contained in the credentials holder controlled prioritized list of GINs (in priority order). If more than one such SNPN broadcast the same GIN, the order in which the MS attempts registration on those SNPNs is MS implementation specific; and

4) each SNPN identified by an SNPN identity which is included neither in the SNPN selection parameters of the entries of the "list of subscriber data" nor in the SNPN selection parameters associated with the PLMN subscription, which does not broadcast a GIN which is included in the credentials holder controlled prioritized list of GINs, and which broadcasts an indication that the SNPN allows registration attempts from MSs that are not explicitly configured to select the SNPN. If more than one such SNPN is available, the order in which the MS attempts registration on those SNPNs is MS implementation specific.

The MS shall limit its search for the SNPN to the NG-RAN access technology.

Once the MS selects the SNPN, the MS attempts registrations on the selected SNPN using the NG-RAN access technology, the subscriber identifier and the credentials from the selected entry of the "list of subscriber data" or from the USIM, if the PLMN subscription is selected.

If successful registration is achieved, the MS indicates the selected SNPN.

If registration cannot be achieved because no SNPNs are available, allowable, and identified by an SNPN identity in an entry of the "list of subscriber data" in the ME, the MS indicates "no service" to the user, waits until a new SNPN is available, allowable, and identified by an SNPN identity in an entry of the "list of subscriber data" in the ME and then repeats the procedure.

If there were one or more SNPNs which were available, allowable, and identified by an SNPN identity in an entry of the "list of subscriber data" in the ME but an LR failure made registration on those SNPNs unsuccessful, the MS selects one of those SNPNs again and enters a limited service state.

If an SNPN is being removed from the "temporarily forbidden PLMNs" or the "permanently forbidden PLMNs" list (e.g due to MS implementation specific timer not shorter than 60 minutes expires or timer T3245 expires), and the MS is in limited service state, and the MS does not have a PDU session for emergency services, the MS shall perform SNPN selection as described in subclause 4.9.3.1. If the MS has an established emergency PDU session, then the UE shall attempt to perform the SNPN selection subsequently after the emergency PDU session is released.

4.9.3.1.2 Manual SNPN selection mode procedure

The MS indicates to the user any available SNPNs which meet the criteria specified in bullets a) and b). If the MS does not support access to an SNPN using credentials from a credentials holder, this includes SNPNs in the list of "permanently forbidden SNPNs", and the list of "temporarily forbidden SNPNs". The MS may indicate to the user whether the available SNPNs are present in the list of "temporarily forbidden SNPNs" or the list of "permanently forbidden SNPNs". If the MS supports access to an SNPN using credentials from a credentials holder, this includes SNPNs in the lists of "permanently forbidden SNPNs", and the lists of "temporarily forbidden SNPNs" associated with each entry of the "list of subscriber data" or the PLMN subscription. The MS may indicate to the user whether the available SNPNs are present in a list of "temporarily forbidden SNPNs" or a list of "permanently forbidden SNPNs" for an entry of the "list of subscriber data" or the PLMN subscription.

a) SNPNs identified by an SNPN identity in an entry of the "list of subscriber data" in the ME, if any. The order in which those SNPNs are indicated is MS implementation specific;

b) if the MS supports access to an SNPN using credentials from a credentials holder, for the SNPNs which broadcast the indication that access using credentials from a credentials holder is supported:

1) each SNPN which is identified by an SNPN identity contained in one of the user controlled prioritized lists of preferred SNPNs configured in the ME. SNPNs included in the same list are indicated in the order in which they are included in the list. Prioritization between the different lists is MS implementation specific;

2) each SNPN which is identified by an SNPN identity contained in one of the credentials holder controlled prioritized lists of preferred SNPNs configured in the ME. SNPNs included in the same list are indicated in the order in which they are included in the list. Prioritization between the different lists is MS implementation specific;

3) each SNPN which broadcasts a GIN contained in one of the credentials holder controlled prioritized lists of GINs configured in the ME. SNPNs broadcasting a GIN included in the same list are indicated in the order in which the GIN is included in the list. Prioritization between the different lists is MS implementation specific. If more than one SNPN broadcast the same GIN, the order in which those SNPNs are indicated is MS implementation specific; and

4) each SNPN identified by an SNPN identity which is included neither in the SNPN selection parameters of the entries of the "list of subscriber data" nor in the SNPN selection parameters associated with the PLMN subscription and which does not broadcast a GIN which is included in one of the credentials holder controlled prioritized lists of GINs configured in the ME. The order in which those SNPNs are indicated is MS implementation specific.

For each of the SNPNs indicated to the user, the MS shall forward a human-readable network name along with the SNPN identity to the upper layers if the system information broadcasted for the SNPN includes the human-readable network name for the SNPN.

The MS shall limit its search for the SNPN to the NG-RAN access technology.

The user may select an SNPN and the MS then initiates registration on this SNPN using the NG-RAN access technology, the subscriber identifier and the credentials from the selected entry of the "list of subscriber data" or from USIM, if the PLMN subscription is selected, determined as follows:

– for bullet a) above, the entry of the "list of subscriber data", with the SNPN identity matching the selected SNPN (this may take place at any time during the presentation of SNPNs), shall be considered as selected;

– for bullet b-1) above:

i) the entry of the "list of subscriber data" which contains the user controlled prioritized lists of preferred SNPNs that includes the SNPN identity of the selected SNPN shall be considered as selected, if the user controlled prioritized list of preferred SNPNs that includes the SNPN identity of the selected SNPN is included in the entry of the "list of subscriber data"; or

– the PLMN subscription shall be considered as selected, if the user controlled prioritized list of preferred SNPNs associated with the PLMN subscription includes the SNPN identity of the selected SNPN;

– for bullet b-2) above:

i) the entry of the "list of subscriber data" which contains the credentials holder controlled prioritized list of preferred SNPNs that includes the SNPN identity of the selected SNPN shall be considered as selected, if the credentials holder controlled prioritized list of preferred SNPNs that includes the SNPN identity of the selected SNPN is included in the entry of the "list of subscriber data"; or

ii) the PLMN subscription shall be considered as selected, if the credentials holder controlled prioritized list of preferred SNPNs associated with the PLMN subscription includes the SNPN identity of the selected SNPN;

– for bullet b-3) above:

i) the entry of the "list of subscriber data" which contains the credentials holder controlled prioritized list of GINs that includes the GIN broadcast by the selected SNPN shall be considered as selected, if the credentials holder controlled prioritized list of GINs that includes the GIN broadcast by the selected SNPN is included in the entry of the "list of subscriber data"; or

ii) the PLMN subscription shall be considered as selected, if the credentials holder controlled prioritized list of GINs associated with the PLMN subscription includes the GIN broadcast by the selected SNPN; and

– for bullet b-4) above, the entry of the "list of subscriber data" or the PLMN subscription shall be selected by MS implementation specific means.

NOTE1: If the SNPN identity of the selected SNPN is included in more than one of the following: one or more user controlled prioritized list(s) of preferred SNPNs configured in the ME, one or more credentials holder controlled prioritized list(s) of preferred SNPNs configured in the ME or the list of SNPNs which are broadcasting a GIN included in one or more credentials holder controlled prioritized list(s) of GINs configured in the ME, which subscription is selected is MS implementation specific.

Once the MS has registered on an SNPN selected by the user, the MS shall not automatically register on a different SNPN unless:

a) the user selects automatic SNPN selection mode;

b) the user initiates an emergency call while the MS is in limited service state and either the SNPN does not broadcast the indication of support of emergency calls in limited service state or the registration request for emergency services is rejected by the network; or

c) the new SNPN is declared as an equivalent SNPN by the registered SNPN.

NOTE 2: If case b) occurs, the MS can provide an indication to the upper layers that the MS has exited manual network SNPN selection mode.

If the user does not select an SNPN, the selected SNPN shall be the one that was selected either automatically or manually before the SNPN selection procedure started. If no such SNPN was selected or that SNPN is no longer available, then the MS shall attempt to camp on any acceptable cell and enter the limited service state.

4.9.3.1.3 Automatic SNPN selection mode procedure for onboarding services in SNPN

When the MS needs to access an SNPN for onboarding services in SNPN, the MS shall select an SNPN indicating that onboarding is allowed and, if the onboarding SNPN selection information is pre-configured, also matching the onboarding SNPN selection information. If more than one such SNPNs are available, how the MS selects one of those SNPNs is MS implementation specific. The MS shall not select an SNPN not indicating that onboarding is allowed or not matching the onboarding SNPN selection information, if pre-configured, for onboarding services in SNPN.

The MS shall limit its search for the SNPN to the NG-RAN access technology.

Once the MS selects the SNPN, the MS shall attempt initial registration for onboarding services in SNPN on the selected SNPN using the NG-RAN access technology and the default UE credentials for primary authentication.

If successful registration is achieved, the MS may indicate to upper layers the selected SNPN. How this indication is displayed by upper layers is implementation specific.

If successful registration is not achieved and one or more other SNPNs indicating that onboarding is allowed and matching the onboarding SNPN selection information, if pre-configured, are available, the MS can select such other SNPN and attempt initial registration for onboarding services in SNPN on the selected SNPN using the NG-RAN access technology and the default UE credentials for primary authentication, or the MS can perform SNPN selection not for onboarding services in SNPN as specified in clause 4.9.3.1.1 or clause 4.9.3.1.2 depending on its SNPN selection mode.

If:

– registration cannot be achieved because no SNPNs indicating that onboarding is allowed and matching the onboarding SNPN selection information, if pre-configured, are available; or

– there were one or more SNPNs indicating that onboarding is allowed and matching the onboarding SNPN selection information, if pre-configured, but an LR failure made registration on all those SNPNs unsuccessful;

the MS can indicate no onboarding services to upper layers, enter limited service state and wait until a new SNPN indicating that onboarding is allowed and matching the onboarding SNPN selection information, if pre-configured, is available and then repeat the procedure, or the MS can perform SNPN selection not for onboarding services in SNPN as specified in clause 4.9.3.1.1 or clause 4.9.3.1.2 depending on its SNPN selection mode.

4.9.3.1.4 Manual SNPN selection mode procedure for onboarding services in SNPN

The MS shall indicate to upper layers one or more SNPNs, which are available and indicate that onboarding is allowed.

These include SNPNs in the list of "permanently forbidden SNPNs" for onboarding services and the list of "temporarily forbidden SNPNs" for onboarding services. The MS may indicate to the user whether the available SNPNs are present in the list of "temporarily forbidden SNPNs" or the list of "permanently forbidden SNPNs".

The MS shall limit its search for the SNPN to the NG-RAN access technology.

For each SNPN indicated to upper layers, the MS shall indicate to the upper layers along with the SNPN identity:

a) whether the SNPN matches the onboarding SNPN selection information, if pre-configured; and

b) the human-readable network name, if the system information broadcast includes the human-readable network name for the SNPN.

4.9.3.2 User reselection

4.9.3.2.0 General

At any time the user may request the MS to initiate reselection and registration onto an available SNPN, according to the following procedures, dependent upon the SNPN selection mode of the UE.

4.9.3.2.1 Automatic SNPN selection mode

If:

– there is at least one entry in the "list of subscriber data"; or

the MS shall select one entry in the "list of subscriber data", or the PLMN subscription, if any, to be used for automatic SNPN selection. How the MS selects the entry in the "list of subscriber data" or the PLMN subscription is MS implementation specific.

The MS selects an SNPNs, if available and allowable, in accordance with the following order:

a) the SNPN identified by an SNPN identity of the subscribed SNPN in the selected entry of the "list of subscriber data" in the ME, if any, excluding the previously selected SNPN;

b) if the MS supports access to an SNPN using credentials from a credentials holder, using the SNPN selection parameters in the selected entry of the "list of subscriber data" or associated with the selected PLMN subscription:

3) each SNPN which broadcasts the indication that access using credentials from a credentials holder is supported and which broadcast a GIN contained in the credentials holder controlled prioritized list of GINs (in priority order), excluding the previously selected SNPN. If more than one such SNPN broadcast the same GIN, the order in which the MS attempts registration on those SNPNs is MS implementation specific; and

4) each SNPN identified by an SNPN identity which is included neither in the SNPN selection parameters of the entries of the "list of subscriber data" nor in the SNPN selection parameters associated with the PLMN subscription and which broadcasts an indication that the SNPN allows registration attempts from MSs that are not explicitly configured to select the SNPN, excluding the previously selected SNPN. If more than one such SNPN is available, the order in which the MS attempts registration on those SNPNs is MS implementation specific.

c) the previously selected SNPN.

The MS shall limit its search for the SNPN to the NG-RAN access technology.

The previously selected SNPN is the SNPN which the MS has selected prior to the start of the user reselection procedure.

The equivalent SNPNs list shall not be applied to the user reselection in automatic SNPN selection mode.

Once the MS selects an SNPN, if the selected SNPN is other than the previously selected SNPN, the MS attempts registrations on the selected SNPN using the NG-RAN access technology, the subscriber identifier and the credentials from the selected entry of the "list of subscriber data" or from the USIM, if the PLMN subscription is selected.

NOTE: If the previously selected SNPN is selected, and registration has not been attempted on any other SNPNs, then the MS is already registered on the SNPN, and so registration is not necessary.

4.9.3.2.2 Manual SNPN selection mode procedure

The manual SNPN selection mode procedure of clause 4.9.3.1.2 is followed.

4.9.4 Abnormal cases

If:

a) the MS does not support access to an SNPN using credentials from a credentials holder and:

1) the "list of subscriber data" is empty; or

2) for each entry of the "list of subscriber data", such that an SNPN with the SNPN identity of the entry is available:

i) there has been an authentication failure for the subscriber identifier of the entry on the SNPN; or

ii) the MS has received an "illegal ME" or "illegal UE" response to an LR request for the subscriber identifier of entry on the SNPN; or

b) the MS supports access to an SNPN using credentials from a credentials holder and:

1) the "list of subscriber data" is empty and:

i) the MS is not provisioned with SNPN selection parameters associated with the PLMN subscription;

ii) the MS does not have a USIM; or

iii) both of the above;

2) for each entry of the "list of subscriber data", such that an SNPN with the SNPN identity of the subscribed SNPN of the entry is available:

i) there has been an authentication failure for the subscriber identifier of the entry on the SNPN; or

ii) the MS has received an "illegal ME" or "illegal UE" response to an LR request for the subscriber identifier of entry on the SNPN;

and:

i) the MS is not provisioned with SNPN selection parameters associated with the PLMN subscription;

ii) the MS does not have a USIM; or

iii) both of the above; or

3) for each available SNPN which broadcasts an indication that access using credentials from a credentials holder is supported and:

i) is identified by an SNPN identity contained in one of the user controlled prioritized lists of preferred SNPNs configured in the ME;

ii) is identified by an SNPN identity contained in one of the credentials holder controlled prioritized lists of preferred SNPNs configured in the ME;

iii) broadcasts a GIN contained in one of the credentials holder controlled prioritized lists of GINs configured in the ME; or

iv) is identified by an SNPN identity which is included neither in the SNPN selection parameters of the entries of the "list of subscriber data" nor in the SNPN selection parameters associated with the PLMN subscription, which does not broadcast a GIN which is included in one of the credentials holder controlled prioritized lists of GINs configured in the ME and which broadcasts an indication that the SNPN allows registration attempts from MSs that are not explicitly configured to select the SNPN;

the following applies:

i) there has been an authentication failure in the SNPN; or

ii) the MS has received an "illegal ME" or "illegal UE" response to an LR request from the SNPN;

then effectively there is no selected SNPN ("No SIM" state).

In these cases, the states of the cell selection process are such that the "list of subscriber data" (if any) or the PLMN subscription (if any) is not used. An MS in "No SIM" state configured with default UE credentials for primary authentication may perform SNPN selection procedure for onboarding services in SNPN. Except when an MS in "No SIM" state performs an initial registration for emergency services to an SNPN or an MS in "No SIM" state configured with default UE credentials for primary authentication performs registration for onboarding services in SNPN, no further attempts at registration on any SNPN are made until the MS is switched off and on again, or an entry of the "list of subscriber data" with the SNPN identity of the SNPN is updated or the USIM is inserted. When performing an initial registration for emergency services, an SNPN supporting emergency services, of the current serving cell is temporarily considered as the selected SNPN. If the MS needs to make an emergency call, the MS supports accessing a PLMN and there is no available SNPN supporting emergency services, the MS shall stop operating in SNPN access mode and attempt to camp on a cell of a PLMN so that emergency calls can be made. After an emergency call is released, the MS may re-start operating in SNPN access mode and perform SNPN selection.

When in automatic SNPN selection mode and the MS is in the "not updated" state with one or more suitable cells to camp on; then after the maximum allowed unsuccessful LR requests (controlled by the specific attempt counters) the MS may continue (or start if it is not running) the user reselection procedure in clause 4.9.3.2.1.