5.5.4 eCall inactivity procedure

24.3013GPPNon-Access-Stratum (NAS) protocol for Evolved Packet System (EPS)Release 18Stage 3TS

The eCall inactivity procedure is applicable only to a UE configured for eCall only mode as specified in 3GPP TS 31.102 [17]. The procedure shall be started when:

– the UE is in any EMM-REGISTERED substate except substates EMM-REGISTERED.PLMN-SEARCH or EMM-REGISTERED.NO-CELL-AVAILABLE;

– the UE is in EMM-IDLE mode; and

– one of the following conditions applies:

1) timer T3444 expires or is found to have already expired and timer T3445 is not running;

2) timer T3445 expires or is found to have already expired and timer T3444 is not running; or

3) timers T3444 and T3445 expire or are found to have already expired.

The UE shall then perform the following actions:

– stop other running timers (e.g. T3411, T3412);

– if the UE is currently registered to EPS services only, perform a detach procedure for EPS services only;

– if the UE is currently registered for both EPS services and non-EPS services, perform a combined detach procedure for EPS services and non-EPS services;

– delete any GUTI, TAI list, last visited registered TAI, list of equivalent PLMNs, and eKSI; and

– enter EMM-DEREGISTERED.eCALL-INACTIVE state.