What is HSS?
The HSS is the central subscriber database in a 4G LTE network (EPC). It stores subscriber authentication credentials, service profiles, and roaming permissions, and is the authoritative source of subscriber identity and access control for all LTE network functions. In 5G SA, the HSS is replaced by the UDM.
How Does HSS Work?
The HSS communicates with the MME via the S6a interface (Diameter protocol) for UE authentication and location management, and with IMS/P-CSCF via Cx/Dx interfaces for VoLTE service profiles. The HSS is based on the SS7-era HLR (Home Location Register) but redesigned for LTE’s all-IP architecture.
Use Cases
4G LTE subscriber authentication and authorisation, VoLTE subscriber profile management, international roaming authentication for LTE subscribers.
3GPP / Standards Reference
3GPP TS 29.272 (S6a/S6d Interfaces using Diameter), TS 23.401
Related Terms
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