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.
- MME-Initiated Detach Procedure;
- SGSN-Initiated Detach procedure;
- HSS-Initiated Detach Procedure.