Multiple PLMN Support

Feature Summary and Revision History

Summary Data

Table 1. Summary Data

Applicable Product(s) or Functional Area

SMF

Applicable Platform(s)

SMI

Feature Default Setting

Disabled – Configuration Required

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Table 2. Revision History
Revision Details Release

First introduced.

2021.01.0

Feature Description

The multi-PLMN feature supports multiple PLMNs for homer and roamer networks. A maximum number of 32 PLMNs can be configured.

The primary PLMN configured under profile DNN is used by SMF for peer discovery. The feature supports homer and roamer networks with different session type configuration. Homer with IPv6 session type configuration and roamer with IPv4 or IPv6 session type is a typical configuration.

The feature supports emergency calls from 4G and 5G RATs from roamer UEs with SIM (unauthenticated IMSI) and without SIM. For emergency calls without IMSI, if primary-PLMN is not configured (no PLMN ID and no primary PLMN under profile DNN), then one of the PLMNs in the PLMN list is used as primary PLMN for external messaging.

SMF validates UE PLMN on getting SmContextCreate or CreateSessionRequest message and populates the PLMN in external messaging.

How it Works

The operator PLMNs configured under PLMN list includes all UE PLMNs and serving PLMNs.

On receiving the Create Request from 4G or 5G RAT (SmContextCreate or Create Session Request), the SMF extracts UE PLMN from SUPI. SMF compares the UE PLMN and serving PLMN with the configured PLMN list and populates the PLMN in external messaging.

Configuring Multiple PLMN

This section describes how to configure the multi-PLMN feature.

Configuring Peer Network Function

This section describes how to configure the use of NRF discovery or local configuration for selecting peer network function.

The configuration under profile network-element allows the user to have different selection logic linked to subscriber policy. For example, the user can configure peer NF logic for homers, roamers or visitors. 

config 
   profile network-element amf amf_profile_name 
      skip-nf-discovery 
      exit 
   exit

NOTES:

  • skip-nf-discovery : Skips network function discovery.

Configuring PLMN ID

This section describes how to configure the PLMN ID. 

config 
   profile smf smf_profile_name 
      plmn-id mcc mcc_value mnc mnc_value 
      exit

NOTES:

  • plmn-id : Specifies the PLMN ID.

  • mcc mcc_value : Specifies the mobile country code.

  • mnc mnc_value : Specifies the mobile network code.

Configuring PLMN List

This section describes how to configure the PLMN list. 

config 
   profile smf smf_profile_name 
      plmn-list mcc mcc_value mnc mnc_value 
      exit

NOTES:

  • plmn-list : Specifies the PLMN list.

  • mcc mcc_value : Specifies the mobile country code.

  • mnc mnc_value : Specifies the mobile network code.

  • A maximum number of 32 PLMNs can be configured.

  • All operator PLMNs are configured under PLMN list including all UE-PLMNs and serving PLMNs.

Configuring Primary PLMN

This section describes how to configure the primary PLMN under DNN profile.

This configuration provides an option to configure the primary PLMN used by SMF, to discover if query parameters are configured appropriately. 

config 
   profile dnn intershat 
      primary-plmn mcc mcc_value mnc mnc_value 
      exit

NOTES:

  • primary-plmn : Configures the primary PLMN.

  • mcc mcc_value : Specifies the mobile country code.

  • mnc mnc_value : Specifies the mobile network code.

Configuring PLMN in NRF Discovery

This section describes how to configure the PLMN in NRF Discovery. 

config 
   profile network-element pcf pcf_profile_name 
      query-params target-plmn [ ue-plmn | serving-plmn | primary-plmn ] 
      exit

NOTES:

  • ue-plmn : The UE PLMN is sent in target PLMN if configured.

  • serving-plmn : The serving PLMN is sent in target PLMN if configured.

  • primary-plmn : The primary PLMN is sent in target PLMN if configured.

Configuring Serving PLMN MNC list

This section describes how to configure the MNC list for serving PLMN.

config 
   policy subscriber policy_name 
      precedence precedence_value 
      serving-plmn mcc mcc_value mnc-list mnc_list_values 
      exit

NOTES:

  • mnc-list : Configures the list of MNC values. For example: [580 660]

  • This configuration is backward compatible. If both mnc and mnc-list are configured, both are considered while selecting the operator policy.

Configuring Roamer in Operator Policy

This section describes how to configure the roamer network in Operator Policy. 

config 
   policy operator policy_name 
      roamer [ visitor-lbo | visitor-hrt | roamer ] 
      exit

NOTES:

  • roamer : Specifies the roamer network.

  • visitor-lbo : Specifies the visitor-lbo session.

  • visitor-hrt : Specifies the visitor-hrt session.

  • Visitors can be either visitor-lbo or visitor-hrt. The 5G visitor sessions are marked as visitor-lbo or visitor-hrt based on whether hsmfUri is received in SmContextCreate.

  • The roamer configuration under operator policy can be used to override the roamer status derived based on hsmfUri.