HSS

The HSS (Home Subscriber Server) provides location management for mobile terminals by interworking with MSC/VLR, SMSC, and other entities over No.7 or SIGTRAN networks, supporting mobile call processing and a range of supplementary services in 2G and 3G networks.
Within IMS networks, it interworks with CSCF and AS to deliver location management, call processing, and additional services.
Moreover, the HSS handles location management, authentication, and VoLTE call processing within LTE networks.
Its architecture comprises a high-capacity in-memory real-time database, No.7/SIGTRAN, MAP/TCAP, and DIAMETER protocols, alongside operation and maintenance, and external device integration capabilities.