Section: 5.5.1.3.4.3 Combined attach successful for EPS services only
Content: Apart from the actions on the tracking area updating attempt counter, the description for attach for EPS services as specified in clause 5.5.1.2.4 shall be followed. In addition, the following description for attach for non-EPS services applies. If, due to emergency services fallback (see 3GPP TS 23.502[ Procedures for the 5G System (5GS) ]  [59], clause 4.13.4), there is a request for emergency services pending and the emergency bearer services indicator in the EPS network feature support IE indicates "emergency bearer services in S1 mode not supported", then the UE shall skip the requirements defined below in the present clause for the receipt of an ATTACH ACCEPT message including an EMM cause value, attempt to select GERAN or UTRAN radio access technology, select a setup message as defined in clause 5.3.7, proceed with appropriate MM specific procedures, and send the setup message. The UE receiving the ATTACH ACCEPT message takes one of the following actions depending on the EMM cause value: #2 (IMSI unknown in HSS) The UE shall stop T3410 if still running and shall reset the tracking area updating attempt counter. The UE shall set the update status to U3 ROAMING NOT ALLOWED and shall delete any TMSI, LAI and ciphering key sequence number. The UE shall enter state EMM-REGISTERED.NORMAL-SERVICE. The new MM state is MM IDLE. The USIM shall be considered as invalid for non-EPS services until the UE is switched off, the UICC containing the USIM is removed or the timer T3245 expires as described in clause 5.3.7a. If the UE maintains a counter for "SIM/USIM considered invalid for non-GPRS services", then the UE shall set this counter to UE implementation-specific maximum value. If, due to emergency services fallback (see 3GPP TS 23.502[ Procedures for the 5G System (5GS) ]  [59]), there is a request for CS fallback call pending (see clause 5.3.7), the UE shall attempt to select GERAN or UTRAN radio access technology and attempt emergency call setup. A UE operating in CS/PS mode 1 of operation with "IMS voice not available" shall disable the E-UTRA capability (see clause 4.5). #16 (MSC temporarily not reachable); or #17 (Network failure) The UE shall stop timer T3410 if still running, and shall enter state MM IDLE. The tracking area updating attempt counter shall be incremented, unless it was already set to 5. If the tracking area updating attempt counter is less than 5: - the UE shall start timer T3411, shall set the EPS update status to EU1 UPDATED and shall enter state EMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM. When timer T3411 expires the combined tracking area updating procedure indicating "combined TA/LA updating with IMSI attach" is triggered. If the tracking area updating attempt counter is equal to 5: - a UE operating in CS/PS mode 2 of operation and a UE operating in CS/PS mode 1 of operation with "IMS voice available" shall start timer T3402, shall set the EPS update status to EU1 UPDATED and shall enter state EMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM. When timer T3402 expires the combined tracking area updating procedure indicating "combined TA/LA updating with IMSI attach" is triggered; - a UE operating in CS/PS mode 1 of operation with "IMS voice not available" shall attempt to select GERAN or UTRAN radio access technology and proceed with appropriate MM or GMM specific procedures and disable the E-UTRA capability (see clause 4.5). #18 (CS domain not available) The UE shall stop timer T3410 if still running, shall reset the tracking area updating attempt counter, shall set the EPS update status to EU1 UPDATED and shall enter state EMM-REGISTERED.NORMAL-SERVICE. The UE shall enter state MM IDLE and shall set the update status to U2 NOT UPDATED. A UE in CS/PS mode 1 of operation 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). A UE in CS/PS mode 2 of operation and a UE operating in CS/PS mode 1 of operation with "IMS voice available" may provide a notification to the user or the upper layers that the CS domain is not available. The UE shall not attempt combined attach or combined tracking area updating procedures with current PLMN until switching off the UE or the UICC containing the USIM is removed. #22 (Congestion) The UE shall stop the timer T3410 if still running. The tracking area updating attempt counter shall be set to 5. The UE shall start the timer T3402, shall set the EPS update status to EU1 UPDATED, shall enter state EMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM, and shall enter state MM IDLE. Other EMM cause values and the case that no EMM cause IE was received are considered as abnormal cases. The combined attach procedure shall be considered as failed for non-EPS services. The behaviour of the UE in those cases is specified in clause 5.5.1.3.6.