Section: 5.3.9.3 Purge function
Content: The Purge function allows an MME to inform the HSS that it has deleted the subscription data and MM context of a detached UE. The MME may, as an implementation option, delete the subscription data and MM context of an UE immediately after the implicit or explicit detach of the UE. Alternatively the MME may keep for some time the subscription data and the MM context of the detached UE, so that the data can be reused at a later attach without accessing the HSS. Figure 5.3.9.3-1: Purge Procedure 1. After deleting the Subscription data and MM contexts of a detached UE, the MME sends Purge UE (IMSI) message to the HSS. 2. The HSS sets the UE Purged for E-UTRAN flag and acknowledges with a Purge UE Ack message.