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.