Section: 4.4.11 CSG Subscriber Server
Content: CSG Subscriber Server (CSS) is an optional element that stores CSG subscription data for roaming subscribers. The CSS stores and provides VPLMN specific CSG subscription information to the MME. The CSS is accessible from the MME via the S7a interface. The CSS is always in the same PLMN as the current MME. If the same CSG ID exists in both CSS subscription data and HSS subscription data, the CSG subscription data from the HSS shall take precedence over the data from CSS. Figure 4.4.11-1 illustrates CSS connected to MME. Figure 4.4.11-1: CSS connected to MME