Allowed PLMN List Support

In networks, where non-roaming SMF and hSMF are in different nodes, AMF can select SMF based on the NRF discovery using query parameters such as NSSAI, PLMN-ID of SUPI, DNN, and so on. This selection might not provide correct results.

In such scenarios, SMF uses the NRF discovery service to register with NRF with the Allowed PLMN list. Either non-roaming SMF can register with list of home serving PLMNs or hSMF can register with partner serving PLMNs.

The SMF includes the configured allowed-plmn-list in allowedPlmns in a Network profile at the time of registering a network function to the NRF.

AMF discovers SMF using a requester-plmn-list in addition to the existing query parameters.

If allowed plmns is configured and SMF receives any SmContextCreate or SmContextUpdate with serving-plmn, which doesn’t match with the configured allowed-plmn, then calls get rejected.

For more information about NF Discovery, refer to the NF Discovery chapter in the UCC 5G SMF Configuration and Administration Guide

Configuring the Allowed PLMN List

To configure the Allowed PLMN list for SMF use the following sample configuration.

config 
   profile smf smf_profile_name 
      allowed-plmn-list  [ mcc-mnc ] 
      end 

NOTES:

  • allowed-plmn-list [ mcc-mnc ] : Configures the allowed plmn list.