3GPP 23.501 v20.2.0 — the document's own text
6.2.7 UDM
Taught in 4. What each network function does (The 5G system architecture, in depth), 18. Being served by somebody else's network (The 5G system architecture, in depth), 2. Who does what in the core (The 5G system architecture, overview).
The Unified Data Management (UDM) includes support for the following functionality:
- Generation of 3GPP AKA Authentication Credentials.
- User Identification Handling (e.g. storage and management of SUPI for each subscriber in the 5G system).
- Support of de-concealment of privacy-protected subscription identifier (SUCI).
- Access authorization based on subscription data (e.g. roaming restrictions).
- UE's Serving NF Registration Management (e.g. storing serving AMF for UE, storing serving SMF for UE's PDU Session).
- Support to service/session continuity e.g. by keeping SMF/DNN assignment of ongoing sessions.
- MT-SMS delivery support.
- Lawful Intercept Functionality (especially in outbound roaming case where UDM is the only point of contact for LI).
- Subscription management.
- SMS management.
- 5G-VN group management handling.
- Support of external parameter provisioning as described in clause 4.15.6 of TS 23.502 [3].
- Support for the Disaster Roaming as described in clause 5.40.
- Support for the control of time synchronization service based on subscription data as described in clause 5.27.1.11.
To provide this functionality, the UDM uses subscription data (including authentication data) that may be stored in UDR, in which case a UDM implements the application logic and does not require an internal user data storage and then several different UDMs may serve the same user in different transactions.
NOTE 1: The interaction between UDM and HSS, when they are deployed as separate network functions, is defined in TS 23.632 [102] and TS 29.563 [103] or it is implementation specific.
NOTE 2: The UDM is located in the HPLMN of the subscribers it serves and access the information of the UDR located in the same PLMN.