ZTE supports three migration solutions which can be chosen by the network operator flexibly:
1. Cutover solution: it migrates all subscribers from the existing HSS to ZTE HSS/UDM step by step, then 5G SA service can be enabled for the subscribers. It is applicable to the migration of HSS user data from the same vendor or different vendors.
2. UDIWF (User Data Interworking Function) solution: for a subscriber in the existing HSS, when he/she change his/her UE to 5G SA capable UE and is allowed to use 5G SA service, the UE can register in 5GC network without 5G SA service provisioning. It is applicable to the migration of HSS user data from the same vendor or different vendors.
3. FE Relay solution: when a subscriber in the existing HSS is provisioned with 5G SA service, his/her profile is migrated to a new HSS/UDM automatically. The existing signaling network keeps the same. When the subscriber can't be found in the existing HSS, the signaling would be relayed to the new HSS/UDM. It is applicable to the migration of SDM user data from the same vendor.