The Evolved Packet Core (EPC) uses Diameter for access to the HSS, EIR and OCS. When the EPC is deployed in a PLMN there may be a need to use existing legacy elements like the HLR, EIR and Prepaid SCP with SS7. Conversely, when the HSS, EIR and OCS are deployed or upgraded to use Diameter there may be a need for them to be used by legacy elements using SS7. This use case describes Diameter Interworking between LTE and Legacy Elements Intra-PLMN (Home).
