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Content for  TS 23.122  Word version:  19.0.0

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4.4 PLMN selection process  4.4.1 Introduction  4.4.2 Registration on a PLMN  4.4.3 PLMN selection  4.4.3.1 At switch-on or recovery from lack of coverage  4.4.3.1.1 Automatic Network Selection Mode Procedure  4.4.3.1.2 Manual Network Selection Mode Procedure  4.4.3.1.3 Manual CSG selection  4.4.3.1.3.1 General   4.4.3.1.3.2 Manual CSG selection within the RPLMN   4.4.3.1.3.3 Manual CSG selection in a PLMN different from the RPLMN   4.4.3.2 User reselection  4.4.3.2.1 Automatic Network Selection Mode  4.4.3.2.2 Manual Network Selection Mode  4.4.3.2.3 Manual CSG selection  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   4.4.3.3.1.2 Automatic and manual network selection modes when registered for disaster roaming services   4.4.3.3.2 Manual CSG selection  4.4.3.4 Investigation Scan for higher prioritized PLMN  4.4.3.5 Periodic attempts for signal level enhanced network selection  4.4.4 Abnormal cases  4.4.5 Roaming not allowed in this LA or TA  4.4.6 Steering of roaming 
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4.4  PLMN selection process  p. 42

4.4.1  Introduction  p. 42

There are two modes for PLMN selection, automatic and manual. These are described in clauses 4.4.3 below and illustrated in Figure 2a to Figure 2b in clause 5.
The MS not operating in SNPN access operation mode over 3GPP access shall perform PLMN selection process.
The MS operating in SNPN access operation mode over 3GPP access shall not perform PLMN selection process.
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4.4.2  Registration on a PLMN  p. 42

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:
  1. the MS has found a suitable cell of the PLMN to camp on; and
  2. 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  p. 42

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 TS 31.102. 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 TS 31.102. 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 TS 44.018, TS 44.060, TS 25.304, TS 36.304 and TS 38.304. 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.
The MS may support minimization of service interruption (MINT).
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4.4.3.1  At switch-on or recovery from lack of coverage  p. 43

  1. if
    • signal level enhanced network selection is not applicable (see clause 3.11); or
    • the MS has stopped applying signal level enhanced network selection according to requirement v) of clause 4.4.3.1.1;
    then the MS selects the registered PLMN or equivalent PLMN (if it is available) using all access technologies that the MS is capable of without considering the "Operator controlled signal threshold per access technology" stored in the USIM; or
  2. if:
    • signal level enhanced network selection is applicable (see clause 3.11); and
    • the received signal quality from a candidate PLMN/access technology combination comprising of a registered PLMN or an equivalent PLMN (if it is available) is equal to or greater than the "Operator controlled signal threshold per access technology" of the access technology configured in the USIM.
    the MS shall select the registered PLMN or equivalent PLMN (if it is available) and the access technology for which the received signal quality is equal to or greater than the "Operator controlled signal threshold per access technology" stored in the USIM. If for the registered PLMN or equivalent PLMN there are two or more access technologies for which the received signal quality is equal to or greater than the "Operator controlled signal threshold per access technology" stored in the USIM, it is up to implementation which access technology is selected by the MS.
and if necessary (in the case of recovery from lack of coverage, see clause 4.5.2) attempts to perform a Location Registration.
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. If signal level enhanced network selection is applicable (see clause 3.11), the MS may register to that EHPLMN or HPLMN only over an access technology for which the received signal quality is equal to or greater than the "Operator controlled signal threshold per access technology" stored in the USIM.
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;
  • registration is not possible due to the PLMN being unavailable or registration failure; or
  • signal level enhanced network selection is applicable (see clause 3.11) and the received signal quality of all access technologies (if the MS is capable of and if it is available) from the registered PLMN or equivalent PLMN (if available) is lower than the "Operator controlled signal threshold per access technology" stored in the USIM of the corresponding access technology.
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.
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.
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 UE determined PLMN with disaster condition or an allowable PLMN is available then the MS will ignore RPLMN and its equivalent PLMN.
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4.4.3.1.1  Automatic Network Selection Mode Procedure  p. 45
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:
  1. 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);
  2. each PLMN/access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);
  3. 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);
  4. other PLMN/access technology combinations with received high quality signal in random order;
  5. other PLMN/access technology combinations in order of decreasing signal quality.
  6. PLMN/NG-RAN combinations for any forbidden PLMNs broadcasting the PLMN ID of the UE determined PLMN with disaster condition or broadcasting the disaster related indication and matching the below conditions:
    1. 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 UE 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 UE 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.
    2. 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.
  7. PLMN /NG-RAN combinations for other forbidden PLMNs broadcasting the PLMN ID of the UE 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.
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.
i)
In i to v, 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 TS 24.301), 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 TS 24.301) and the MS camps on a E-UTRA cell which is not NB-IoT cell (see TS 36.304, TS 36.331), 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 PLMN/access technology combinations which do not advertise support for eCall over IMS, unless such PLMNs are available in GERAN or UTRAN.
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:
    1. 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 authorized based on the "Allowed CAG list" of the entry; or
    2. 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 TS 23.501) and the MS camps on an E-UTRA cell connected to 5GCN, which is not NB-IoT cell (see TS 36.304, TS 36.331), 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 TS 24.501).
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 UE determined PLMN with disaster condition as follows:
  1. 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 UE determined PLMN with disaster condition; or
  2. 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 UE 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 UE 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 UE 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 UE 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 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 over non-3GPP access and not in 5GMM-CONNECTED mode over non-3GPP access (see TS 24.501);
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:
  1. 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 UE determined PLMN with disaster condition as per bullet q2); or
  2. 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 UE determined PLMN with disaster condition as determined in bullet q1).
s)
In i to vii, if the RedCap UE camps on an NR cell connected to 5GCN, the MS shall not consider PLMNs which do not advertise support of RedCap UE.
s1)
In i to vii, if the eRedCap UE camps on an NR cell connected to 5GCN, the MS shall not consider PLMNs which do not advertise support of eRedCap UE.
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.
u1)
In i to vii, if a PLMN/access technology combination is included in the list of "PLMNs with associated RAT restrictions", the MS shall not consider it as PLMN selection candidate;
v)
In i), ii), iii), and v), if:
  • signal level enhanced network selection is applicable (see clause 3.11); and
  • the received signal quality of the candidate PLMN/access technology combination is lower than the threshold value indicated for the access technology in the "Operator controlled signal threshold per access technology" stored in the USIM.
the MS shall not consider the PLMN(s) in i) and PLMN/access technology combination(s) in ii), iii) and v) as selection candidate. If the received signal quality from none of the candidate PLMN(s) or PLMN/access technology combination(s) is equal to or greater than the "Operator controlled signal threshold per access technology" stored in the USIM, the MS shall stop applying signal level enhanced network selection and repeat the network selection procedure as specified in clause 4.4.3.1.
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 there were one or more PLMN/NG-RAN combinations which were available and which are forbidden PLMNs broadcasting the PLMN ID of the UE determined PLMN with disaster condition or broadcasting the disaster related indication, but an LR failure made registration on those PLMNs unsuccessful due to "Disaster roaming for the determined PLMN with disaster condition not allowed", 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 TS 31.102) or in the ME (see TS 24.368);
  • 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:
  1. if at least one preferred PLMN exists based on the RLOS preferred PLMN list configured in the USIM (see TS 31.102) or in the ME (see TS 24.368) and the MCC part of the preferred PLMN ID is present in the RLOS allowed MCC list configured in the USIM (see TS 31.102) or in the ME (see TS 24.368), the MS shall select the preferred PLMN offering access to RLOS and indicate the selected preferred PLMN for access to RLOS; and
  2. 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 TS 31.102) or in the ME (see TS 24.368), 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 TS 31.102) or in the ME (see TS 24.368), 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.
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4.4.3.1.2  Manual Network Selection Mode Procedure  p. 50
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:
  1. 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;
  2. PLMN/access technology combinations contained in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);
  3. 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);
  4. other PLMN/access technology combinations with received high quality signal in random order;
  5. 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 UE 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:
  1. 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:
      1. there exists an entry with the PLMN ID of the PLMN in the "CAG information list" and the CAG-ID is authorized based on the "Allowed CAG list" of the entry; or
      2. 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 authorized based on the "Allowed CAG list" stored in the UE; and
  2. 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.
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; or
  • a selected CAG-ID and the CAG-ID is not authorized based on 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 authorized based on the "Allowed CAG list" for the selected PLMN for this registration attempt.
If the MS has, or is establishing, a PDU session for emergency services, a PDN connection for emergency bearer services or a PDP context for emergency bearer services or CS emergency call, being registered for emergency services or having an ongoing emergency services fallback procedure, 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 TS 38.304), then:
  1. the MS shall indicate to user that it can not find the selected PLMN and CAG-ID; and
  2. 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 authorized based on 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 authorized based on 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:
  1. 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 UE 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 UE determined PLMN with disaster condition in the old PLMN is also a UE determined PLMN with disaster condition in the new PLMN;
  2. the user selects automatic mode;
  3. 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
  4. 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.
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 indication of whether disaster roaming is enabled in the UE is set to "Disaster roaming is enabled in the UE";
  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 UE determined PLMN with disaster condition based on the determination of the UE determined PLMN with disaster condition as specified in clause 4.4.3.1.1.
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;
  • 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 TS 31.102) or in the ME (see TS 24.368);
  • 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:
  1. PLMNs contained in the RLOS preferred PLMN list configured in the USIM (see TS 31.102) or in the ME (see TS 24.368) (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 TS 31.102) or in the ME (see TS 24.368); and
  2. 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 TS 31.102) or in the ME (see TS 24.368).
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).
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4.4.3.1.3  Manual CSG selection |R8|  p. 53
4.4.3.1.3.1  General   p. 53
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 TS 24.285.
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 TS 23.003) 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 TS 23.003) 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 TS 22.220.
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.
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4.4.3.1.3.2  Manual CSG selection within the RPLMN   p. 54
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.
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4.4.3.1.3.3  Manual CSG selection in a PLMN different from the RPLMN   p. 54
If the user selects a CSG in a PLMN that is different from the RPLMN, then the following applies:
  1. 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 or a PLMN selection triggered by A2X communication over PC5 as specified in clause 3.1D;
  2. The MS shall enter into Manual mode of PLMN selection in state M4 (Trying PLMN) as defined in clause 4.3.1.2;
  3. 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;
  4. 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;
  5. 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;
  6. 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;
  7. If the MS's E-UTRA capability is disabled as a result of successful registration (as described in 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 of TS 24.301) 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
  8. If the MS's E-UTRA capability is disabled as a result of performing the service request procedure (as described in clause 5.6.1.5 of TS 24.301), 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.
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4.4.3.2  User reselection  p. 54

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  p. 54
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:
  1. 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);
  2. 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;
  3. 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;
  4. other PLMN/access technology combinations with the received high quality signal in random order excluding the previously selected PLMN/access technology combination;
  5. 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;
  6. 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.
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), p) and v) 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.
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4.4.3.2.2  Manual Network Selection Mode  p. 55
The Manual Network Selection Mode Procedure clause 4.4.3.1.2 is followed.
4.4.3.2.3  Manual CSG selection |R8|  p. 55
The procedure of clause 4.4.3.1.3 is followed.

4.4.3.3  In VPLMN  p. 55

4.4.3.3.1  Automatic and manual network selection modes |R8|  p. 55
4.4.3.3.1.1  Automatic and manual network selection modes when not registered for disaster roaming services   p. 55
If the MS is in a VPLMN and not registered for disaster roaming services, and 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 TS 36.306);
    1. 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
    2. 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 TS 36.306), 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:
    1. any of the following or a combination of: EC-GSM-IoT, Category M1 or Category NB1 (as defined in TS 36.306); and
    2. any other than the following: EC-GSM-IoT, Category M1 or Category NB1 (as defined in TS 36.306),
      T is interpreted depending on what is in use as specified below:
      1. 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 TS 36.306), 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
      2. 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 TS 36.306), 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 TS 24.368 or TS 31.102, 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 TS 24.008 and TS 24.301, when it activates power saving mode (PSM) (see TS 23.682) or mobile initiated connection only mode (MICO) as described in TS 24.501.
The MS does not stop timer T, as described in TS 24.008 and TS 24.301, when the access stratum is de-activated due to discontinuous coverage (see TS 23.401 and TS 24.301).
The MS does not stop timer T when it activates unavailability period as described in TS 24.501.
The MS can be configured for Fast First Higher Priority PLMN search as specified in TS 31.102 or TS 24.368. 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 according to the present clause or according to clause 4.4.3.5;
d)
Periodic attempts shall only be performed by the MS while in idle mode or 5GMM-CONNECTED mode with RRC inactive indication (see TS 24.501);
d1)
Periodic attempts may be postponed while the MS is in power saving mode (PSM) (see TS 23.682) or when the access stratum is deactivated due to discontinuous coverage (see TS 23.401 and TS 24.301).
d2)
Periodic attempts may be postponed while the MS is receiving eMBMS transport service in idle mode (see TS 23.246).
d3)
Periodic attempts may be postponed while the MS is receiving broadcast MBS service in idle mode (see TS 23.247) or in 5GMM-CONNECTED mode with RRC inactive indication.
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 TS 36.304).
d6)
Periodic attempts may be postponed while the MS is in Mobile Initiated Connection Only mode (MICO).
d7)
Periodic attempts may be postponed while the MS unavailability period is activated as described in TS 24.501.
d8)
Periodic attempts may be postponed while the MS is receiving multicast MBS service in 5GMM-CONNECTED mode with RRC inactive indication (see TS 23.247).
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".
j)
In steps i), ii) and iii) of clause 4.4.3.1.1, if signal level enhanced network selection is applicable (see clause 3.11 and step d) of clause 4.4.3.5), the MS shall only select a PLMN, if the received signal quality of the candidate PLMN/access technology combination is equal to or greater than the "Operator controlled signal threshold per access technology".
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4.4.3.3.1.2  Automatic and manual network selection modes when registered for disaster roaming services   p. 57
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.
If the MS is configured with the MinimumPeriodicSearchTimer as specified in TS 24.368 or TS 31.102, 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 TS 24.008 and TS 24.301, when it activates power saving mode (PSM) (see TS 23.682) or mobile initiated connection only mode (MICO) as described in TS 24.501.
The MS does not stop timer T when it activates unavailability period as described in TS 24.501.
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, after completion of the initial registration for disaster roaming services or of the mobility registration for disaster roaming services;
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 TS 24.501);
d)
The periodic attempts may be postponed:
  • while the MS is in power saving mode (PSM) (see TS 23.682);
  • while the MS is receiving eMBMS transport service in idle mode (see TS 23.246);
  • while the MS is receiving broadcast MBS service in idle mode (see TS 23.247) or in 5GMM-CONNECTED mode with RRC inactive indication;
  • till the next eDRX occasion while the MS is configured with eDRX;
  • while the MS is in relaxed monitoring (see TS 36.304);
  • while the MS is in Mobile Initiated Connection Only mode (MICO);
  • while the unavailability period is activated in MS as described in TS 24.501; or
  • while the MS is receiving multicast MBS service in 5GMM-CONNECTED mode with RRC inactive indication (see TS 23.247).
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 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 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.
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4.4.3.3.2  Manual CSG selection |R8|  p. 59
The procedure of clause 4.4.3.1.3 is followed.

4.4.3.4  Investigation Scan for higher prioritized PLMN  p. 59

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:
  1. 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
  2. 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.
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4.4.3.5  Periodic attempts for signal level enhanced network selection |R18|  p. 60

If signal level enhanced network selection is applicable (see clause 3.11) and the received signal quality of registered PLMN observed over an averaging window is lower than the "Operator controlled signal threshold per access technology" the MS shall periodically attempt to obtain service on an allowable PLMN/access technology combination for which the received signal quality of the candidate PLMN/access technology combination is equal to or greater than the "Operator controlled signal threshold per access technology" in accordance with the requirements that are applicable to i), ii), iii), iv) and v) as defined in the Automatic Network Selection Mode in clause 4.4.3.1.1. For this purpose, the value of the timer TSENSE is configured with an MS implementation specific value with a minimum value of 2 min and a maximum value set to the value applicable for timer T as defined in clause 4.4.3.3.1.1.
The averaging window shall be shorter than the value of the timer TSENSE.
The MS does not stop timer TSENSE, as described in TS 24.008 and TS 24.301, when it activates power saving mode (PSM) (see TS 23.682) or mobile initiated connection only mode (MICO) as described in TS 24.501.
The MS does not stop timer TSENSE, as described in TS 24.008 and TS 24.301, when the access stratum is de-activated due to discontinuous coverage (see TS 23.401 and TS 24.301) or when the MS activates unavailability period as described in TS 24.501.
The attempts to obtain service on an allowable PLMN shall be as specified below:
  1. The periodic attempts shall only be performed in automatic mode, and not while the MS is attached for emergency bearer services, is registered for emergency services, has a PDN connection for emergency bearer services or has a PDU session for emergency services.
  2. When the MS detects that the received signal quality of the current cell of the registered PLMN is below the "Operator controlled signal threshold per access technology" either upon registration or any time later, the MS shall start timer TSENSE, if not already running.
  3. If upon expiry of timer TSENSE the received signal quality of the registered PLMN observed over an averaging window is equal to or greater than the "Operator controlled signal threshold per access technology" the MS shall stay on the current selected PLMN. If timer T defined in clause 4.4.3.3.1.1 expires while timer TSENSE is running and the received signal quality of registered PLMN observed over an averaging window is lower than the "Operator controlled signal threshold per access technology", the MS shall stop timer TSENSE and shall perform the actions defined in this clause instead of the action defined for timer T expiry defined in clause 4.4.3.3.1.1.
  4. If the received signal quality of the registered PLMN and all other available and allowable PLMN/access technology combinations are lower than the "Operator controlled signal threshold per access technology", the MS shall stop applying signal level enhanced network selection and repeat the network selection procedure as specified in clause 4.4.3.3.1.1.
  5. The attempts shall only be performed by the MS while in idle mode or 5GMM-CONNECTED mode with RRC inactive indication (see TS 24.501).
  6. The attempts may be postponed:
    • while the MS is in power saving mode (PSM) (see TS 23.682) or when the access stratum is deactivated due to discontinuous coverage or when the UE activated unavailability period (see TS 23.401 and TS 24.301);
    • while the MS is receiving eMBMS transport service in idle mode (see TS 23.246);
    • till the next eDRX occasion while the MS is configured with eDRX;
    • while the MS is in relaxed monitoring (see TS 36.304);
    • while the MS is in Mobile Initiated Connection Only mode (MICO).
  7. 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 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 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.
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4.4.4  Abnormal cases  p. 61

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.
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4.4.5  Roaming not allowed in this LA or TA  p. 61

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 |R7|  p. 61

If the MS receives a USAT REFRESH command qualifier (TS 31.111) of type "Steering of Roaming", the MS shall:
  1. 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, if any, or replace the SOR-CMCI in the ME with the SOR-CMCI provided in REFRESH command, if any, or both;
  2. 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;
  3. take the new information into account in subsequent attempts to access a higher priority PLMN; and
  4. 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.
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