Detach가 이루어지기 이전에는 RRC-Connected / ECM-Connected / EMM-Registered Mode에 존재하다가,UE 또는 MME에 의해서 Detach가 이루어 지게 되면,RRC-Idle / ECM-Idle / EMM-Deregistered 상태로 변경되게 됩니다.

UE-Initiated Detach- UE Power Off (Switch Off)- Lost or Removed the ICC/UICC Card- UE is used to non-EPS service For example, CS Fallback, SMS, etc… - Flight Mode On NW-Initiated Detach (By MME or HSS)- Explicit Detach (The MME sent to Detach Message to the UE)O&M (Operation & Maintenance) by operatorFail Re-authenticationOperator can’t support the bearer no more.HSS is needed to change the Subs..

Spec. 23.301 / 23.401 / 23.272 – Attach Procedure