5 Procedure

22.0163GPPInternational Mobile station Equipment Identities (IMEI)Release 17TS

It shall be possible to perform the IMEI check at any access attempt, except IMSI detach, and during an established call at any time when a dedicated radio resource is available, in accordance with the security policy of the PLMN operator. It shall also be possible to perform the IMEI check when a UE is IMS registered.

The network shall terminate any access attempt or ongoing call when receiving indication from the EIR that the UE is on the prohibited list or the UE is not on the allowed list). An indication of "illegal ME" shall in these cases be given to the user. Furthermore this is equivalent to an authentication failure hence any call or IMS session establishment or any location updating is forbidden for the MS, it cannot answer to paging, it is just allowed to perform Emergency Calls. Emergency calls must never be terminated as a result of the IMEI check procedure.