Section: 5.5.3.3.4.2 Combined tracking area updating successful
Content: The description for normal tracking area update as specified in clause 5.5.3.2.4 shall be followed. In addition, the following description for location area updating applies. The TMSI reallocation may be part of the combined tracking area updating procedure. The TMSI allocated is then included in the TRACKING AREA UPDATE ACCEPT message together with the location area identification (LAI). In this case the MME shall change to state EMM-COMMON-PROCEDURE-INITIATED and shall start the timer T3450 as described in clause 5.4.1. The LAI may be included in the TRACKING AREA UPDATE ACCEPT message without TMSI. If the MME does not indicate "SMS only" in the TRACKING AREA UPDATE ACCEPT message, subject to operator policies the MME should allocate a TAI list that does not span more than one location area. For a shared network in CS domain, the MME indicates the selected PLMN for CS domain in the LAI to the UE as specified in 3GPP TS 23.272[ Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2 ]  [9]. The UE, receiving a TRACKING AREA UPDATE ACCEPT message, stores the received location area identification, resets the location update attempt counter, sets the update status to U1 UPDATED and enters MM state MM IDLE. If the UE maintains a counter for "SIM/USIM considered invalid for non-GPRS services" events (see clause 5.3.7b), then the UE shall reset this counter. If the LAI contained in the TRACKING AREA UPDATE ACCEPT message is a member of the list of "forbidden location areas for regional provision of service" or the list of "forbidden location areas for roaming" then such entry shall be deleted. If the PLMN identity for the CS domain which is provided as part of the LAI contained in the TRACKING AREA UPDATE ACCEPT message differs from the PLMN identity provided as part of the GUTI, the MME shall include the PLMN identity for the CS domain in the list of equivalent PLMNs in the TRACKING AREA UPDATE ACCEPT message. If the UE requested "SMS only" in the Additional update type IE, or if the UE requested a combined tracking area updating for EPS and non-EPS services, but the network decides to accept the tracking area update request for EPS services and "SMS only", the network shall indicate "SMS only" in the Additional update result IE. In addition, if the SMS services are provided via SMS in MME, the network shall, in the TRACKING AREA UPDATE ACCEPT message, provide a non-broadcast LAI and may indicate in the EPS update result IE that ISR is activated. If a TMSI has to be allocated, then the network shall also provide a TMSI which cannot cause any ambiguity with assigned TMSI values. If the TRACKING AREA UPDATE ACCEPT message includes the Additional update result IE with value "SMS only", a UE operating in CS/PS mode 2 and a UE operating in CS/PS mode 1 with "IMS voice available" shall not attempt to use CS fallback for mobile originating services. As an implementation option, if the TRACKING AREA UPDATE ACCEPT message does not include the Additional update result IE with value "SMS only" and the UE is not configured for NAS signalling low priority then the UE may stop timer T3246 if running. If the TRACKING AREA UPDATE ACCEPT message includes the Additional update result IE with value "CS Fallback not preferred", this indicates to a UE operating in CS/PS mode 2 and a UE operating in CS/PS mode 1 with "IMS voice available" that it is attached for EPS and non-EPS services and that it can use CS fallback. How to handle the old TMSI stored in the UE depends on the mobile identity included in the TRACKING AREA UPDATE ACCEPT message. - If the TRACKING AREA UPDATE ACCEPT message contains an IMSI, the UE is not allocated any TMSI, and shall delete any old TMSI accordingly. - If the TRACKING AREA UPDATE ACCEPT message contains a TMSI, the UE shall use this TMSI as new temporary identity. The UE shall delete its old TMSI and shall store the new TMSI. In this case, a TRACKING AREA UPDATE COMPLETE message is returned to the network to confirm the received TMSI. - If neither a TMSI nor an IMSI has been included by the network in the TRACKING AREA UPDATE ACCEPT message, the old TMSI, if any is available, shall be kept. NOTE 1: It is possible for UEs compliant with earlier versions of this specification to send a TRACKING AREA UPDATE COMPLETE message even if TMSI reallocation is not part of the combined tracking area updating procedure. If the TRACKING AREA UPDATE ACCEPT message includes the Additional update result IE with value "SMS only" or "CS Fallback not preferred", a UE operating in CS/PS mode 1 with "IMS voice not available" shall attempt to select GERAN or UTRAN radio access technology and disable the E-UTRA capability (see clause 4.5). The network receiving a TRACKING AREA UPDATE COMPLETE message stops timer T3450, changes to state EMM-REGISTERED. NOTE 2: Upon receiving a TRACKING AREA UPDATE COMPLETE message, if a new TMSI was included in the TRACKING AREA UPDATE ACCEPT message, the MME sends an SGsAP-TMSI-REALLOCATION-COMPLETE message as specified in 3GPP TS 29.118[ Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification ]  [16A]. Unless the MME supporting N26 is in a deployment where it, after intersystem change from N1 mode to S1 mode, has an IMEI or an IMEISV for the UE, then after the UE performs intersystem change from N1 mode to S1 mode, if: - the network supports SRVCC for IMS emergency sessions (see 3GPP TS 23.216[ Single Radio Voice Call Continuity (SRVCC); Stage 2 ]  [8]); - the UE has an emergency PDN connection; - the UE has set the SRVCC to GERAN/UTRAN capability bit in the MS network capability IE to "SRVCC from UTRAN HSPA or E-UTRAN to GERAN/UTRAN supported; and - the MME has neither an IMEI nor an IMEISV for the UE; NOTE 3: The AMF can receive an IMEI from the UE and pass it to the MME during the intersystem change if the UE is emergency registered and the UE doesn't have a valid USIM or the UE's IMSI remains unauthenticated. then the MME shall initiate the identification procedure (see clause 5.4.4) or the security mode control procedure (see clause 5.4.3) with the UE.