OpenEPC provides a consolidated subscription repository which includes the functionality of the Home Subscriber Server (HSS) from 3GPP IMS and of the Subscription Profile Repository (SPR) from the 3GPP EPC. The OpenEPC HSS includes the following interfaces:

  • towards the 3GPP RAN, enabling authentication and authorization of default resources
    • S6a to MME
    • S6d to SGSN
    • S6”MSC” to MSC (proprietary, similar to S6a/d, instead of the MAP D interface)
    • (Upcoming MAP-based C/Gr interfaces for maximum interoperability with legacy)
  • towards EPC functions
    • SWx to AAA Server
    • Sp to PCRF and ANDSF (not standardized in 3GPP, hence Sh-like)
  • towards IMS functions
    • Cx to Interrogating/Serving – Call Session Control Functions (I/S-CSCF)
    • Sh to IMS Application Servers (AS)