scope:

This Technical Report describes scenarios for co-existence of subscription data pertaining to legacy system (EPS) with data pertaining to the 5G system, when the HSS+UDM defined in Rel-15 is separated and both UDM and HSS are independent, and provides solutions to support this deployment where necessary.

NOTE 1: The subscription data referred to by this Technical Report comprises both static as well as dynamic data, including IMS, LCS, SMS data.

This technical report includes:

- diverse scenarios related to the storage of subscription data including, but not limited to, those of common repository for subscription data from EPS and 5GS, as well as separate repositories for EPS and 5GS subscription data; and

- the solutions supporting relevant procedures in TS 23.502 [2] (for e.g. authentication, mobility, handover and procedures for IMS and SMS handling in interworking between 5G system and EPS),

Provisioning aspects are out of the scope of this document.

Direct interactions between the EPS UDR and the 5GS UDR are out of the scope of this document.