Section: 4.7.9.1.2 Paging for GPRS services using IMSI
Content: Paging for GPRS services using IMSI is an abnormal procedure used for error recovery in the network. The network may initiate paging using IMSI if the P-TMSI is not available due to a network failure. In Iu mode, to initiate the procedure the GMM entity in the network requests the lower layer to start paging (see 3GPP TS 25.331[ None ]  [23c] and 3GPP TS 25.413[ UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling ]  [19c]). In A/Gb mode, to initiate the procedure the GMM entity in the network requests the RR sublayer to start paging (see 3GPP TS 44.018[ None ]  [84], 3GPP TS 44.060[ None ]  [76]). Upon reception of a paging indication for GPRS services using IMSI, the MS shall stop the timer T3346, if it is running, locally deactivate any active PDP context(s), MBMS context(s) and locally detach from GPRS. The local detach includes deleting any RAI, P-TMSI, P-TMSI signature and GPRS ciphering key sequence number stored, setting the GPRS update status to GU2 NOT UPDATED and changing state to GMM-DEREGISTERED. The MS shall stop all timers T3396 that are running. If S1 mode is supported by the MS, the MS shall in addition handle the EMM parameters EMM state, EPS update status, last visited registered TAI, TAI list, GUTI and KSIASME as specified in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120] for the case when a paging for EPS services using IMSI is received. In Iu mode, when an MS receives a paging request for GPRS services using the IMSI from the network before an MS initiated GMM specific procedure has been completed, then the MS shall abort the GMM specific procedure, and the MS shall proceed according to the description in this clause. After performing the local detach, the MS shall then perform a GPRS attach or combined GPRS attach procedure. After performing the attach, the MS should activate PDP context(s) to replace any previously active PDP context(s). The MS should also perform the procedures needed in order to activate any previously active multicast service(s). NOTE 1: In some cases, user interaction may be required and then the MS cannot activate the PDP and MBMS context(s) automatically. NOTE 2: The MS does not respond to the paging except with the Attach Request. Hence timers T3313 and T3315 in the network are not used when paging with IMSI. NOTE 3: Paging without DRX parameters may require a considerable extension of the paging duration. NOTE 4: Paging without using eDRX parameters may result in the paging with IMSI not to be received by the MS for which eDRX has been negotiated or may require a considerable extension of the paging duration.