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.