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..