Section: 5.3.8 Detach procedure 5.3.8.1 General
Content: The Detach procedure allows: - the UE to inform the network that it does not want to access the EPS any longer, and - the network to inform the UE that it does not have access to the EPS any longer. The UE is detached either explicitly or implicitly: - Explicit detach: The network or the UE explicitly requests detach and signal with each other. - Implicit detach: The network detaches the UE, without notifying the UE. This is typically the case when the network presumes that it is not able to communicate with the UE, e.g. due to radio conditions. Four detach procedures are provided when the UE accesses the EPS through E-UTRAN. The first detach procedure is UE-initiated detach procedure and other detach procedures are network-initiated detach procedure: - UE-Initiated Detach Procedure. In the ISR activated case the UE initiated detach is split into two sub procedures, one for UE camping on E-UTRAN and one for UE camping on GERAN/UTRAN; - MME-Initiated Detach Procedure; - SGSN-Initiated Detach procedure with ISR activated; - HSS-Initiated Detach Procedure. NOTE 1: The MME and the UE may enter EMM-DEREGISTERED state without the above procedures.