24.3013GPPNon-Access-Stratum (NAS) protocol for Evolved Packet System (EPS)Release 18Stage 3TS
Cause #2 – IMSI unknown in HSS
This EMM cause is sent to the UE if the UE is not known (registered) in the HSS or if the UE has packet only subscription. This EMM cause does not affect operation of the EPS service, although it may be used by an EMM procedure.
Cause #3 – Illegal UE
This EMM cause is sent to the UE when the network refuses service to the UE either because an identity of the UE is not acceptable to the network or because the UE does not pass the authentication check, i.e. the RES received from the UE is different from that generated by the network.
Cause #6 – Illegal ME
This EMM cause is sent to the UE if the ME used is not acceptable to the network, e.g. on the prohibited list.
Cause #9 – UE identity cannot be derived by the network.
This EMM cause is sent to the UE when the network cannot derive the UE’s identity from the GUTI/S-TMSI/P-TMSI and RAI e.g. no matching identity/context in the network or failure to validate the UE’s identity due to integrity check failure of the received message.
Cause #10 – Implicitly detached
This EMM cause is sent to the UE either if the network has implicitly detached the UE, e.g. after the implicit detach timer has expired, or if the EMM context data related to the subscription does not exist in the MME e.g. because of a MME restart, or because of a periodic tracking area update request routed to a new MME.