Section: 4.7.5.1.1 Normal and periodic routing area updating procedure initiation
Content: To initiate the normal routing area updating procedure, the MS sends the message ROUTING AREA UPDATE REQUEST to the network, starts timer T3330 and changes to state GMM-ROUTING-AREA-UPDATING-INITIATED. If timer T3302 is currently running, the MS shall stop timer T3302. If timer T3311 is currently running, the MS shall stop timer T3311. If the MS supports S1 mode, the MS shall handle the P-TMSI IE as follows: - If the TIN indicates "GUTI" and the MS holds a valid GUTI allocated by an MME, the MS shall map the GUTI into a P-TMSI, P-TMSI signature and RAI as specified in 3GPP TS 23.003[ Numbering, addressing and identification ]  [10]. The MS shall include the mapped RAI in the Old routing area identification IE and the mapped P-TMSI signature in the P-TMSI signature IE. In addition, the MS shall include the P-TMSI type IE with P-TMSI type set to "mapped P-TMSI". When the routing area updating procedure is initiated in Iu mode, the MS shall also include the mapped P-TMSI in the P-TMSI IE. Additionally, in Iu mode and A/Gb mode, if the MS holds a valid P-TMSI and RAI, the MS shall indicate the P-TMSI in the Additional mobile identity IE and the RAI in the Additional old routing area identification IE. - If the TIN indicates "P-TMSI" or "RAT-related TMSI" and the MS holds a valid P-TMSI and RAI, the MS shall indicate the RAI in the Old routing area identification IE. In addition, the MS shall include the P-TMSI type IE with P-TMSI type set to "native P-TMSI". When the routing area updating procedure is initiated in Iu mode, the MS shall also include the P-TMSI in the P-TMSI IE. If the MS does not support S1 mode, the MS shall include the P-TMSI type IE with P-TMSI type set to "native P-TMSI". If the MS supports PSM and requests the use of PSM, the MS shall include the T3324 value IE with a requested timer value in the ROUTING AREA UPDATE REQUEST message. When the MS includes the T3324 value IE and the MS indicates support for extended periodic timer value in the MS network feature support IE, it may also include the T3312 extended value IE to request a particular T3312 value to be allocated. If the routing area updating procedure is not initiated by the MS due to an S1 mode to Iu mode or S1 mode to A/Gb mode intersystem change, or if it is initiated due to such an intersystem change and the TIN indicates "RAT-related TMSI", the MS shall use the existing UMTS security context for the PS domain. The ROUTING AREA UPDATE REQUEST message shall contain the P-TMSI signature when received in a previous ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT message. If the MS has a valid UMTS security context, the MS shall indicate it in the GPRS ciphering key sequence number IE. If the routing area updating procedure is initiated by the MS due to an S1 mode to Iu mode or S1 mode to A/Gb mode inter-system change in idle mode, or if it is initiated by the MS due to PS to CS domain change from S1 mode due to SRVCC or vSRVCC handover, and the TIN indicates "GUTI", the MS shall derive a UMTS security context for the PS domain from the current EPS security context as described in the subclause 4.7.7.10. The ROUTING AREA UPDATE REQUEST message shall include a P-TMSI signature filled with a NAS token as specified in 3GPP TS 33.401[ 3GPP System Architecture Evolution (SAE); Security architecture ]  [123]. Furthermore, the MS shall indicate the eKSI value, which is associated with the derived UMTS security keys, in the CKSN field of the GPRS GSM ciphering key sequence number IE in the ROUTING AREA UPDATE REQUEST message. NOTE: When the MS includes a P-TMSI signature filled with a NAS token, 8 bits of the NAS token will be filled with bits from the M-TMSI (see 3GPP TS 23.003[ Numbering, addressing and identification ]  [10]). If the routing area updating procedure is initiated by the MS due to the S1 mode to Iu mode or S1 mode to A/Gb mode inter-system change in connected mode, the MS shall derive a UMTS security context for the PS domain from the current EPS security context as described in the subclause 4.7.7.10. Furthermore, the MS shall indicate the eKSI value, which is associated with the derived UMTS security keys, in the CKSN field of the GPRS GSM ciphering key sequence number IE in the ROUTING AREA UPDATE REQUEST message. In Iu mode, if the MS wishes to prolong the established PS signalling connection after the normal routing area updating procedure (for example, the MS has any CM application request pending), it may set a follow-on request pending indicator on (see subclause 4.7.13). In order to indicate the new DRX parameter while in GERAN or UTRAN coverage, the MS shall send the ROUTING AREA UPDATE REQUEST message containing the DRX parameter in the DRX parameter IE to the network, with the exception of the case if the MS had indicated its MS specific DRX parameter (3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120]) to the network while in E-UTRAN coverage. In this case, when the MS enters GERAN or UTRAN coverage and initiates a routing area updating procedure, the MS shall not include the DRX parameter in the DRX parameter IE in the ROUTING AREA UPDATE REQUEST message. If the MS supports eDRX and requests the use of eDRX, the MS shall include the extended DRX parameters IE in the ROUTING AREA UPDATE REQUEST message. In A/Gb mode, if the MS supports the restriction on use of enhanced coverage, then the MS shall set the Restriction on use of enhanced coverage capability bit to "Mobile station supports restriction on use of enhanced coverage" in the MS network capability IE of the ROUTING AREA UPDATE REQUEST message If the MS supports dual connectivity of E-UTRA with NR, then the MS shall set the Dual connectivity of E-UTRA with NR capability bit to "Mobile station supports dual connectivity of E-UTRA with NR" in the MS network capability IE of the ROUTING AREA UPDATE REQUEST message. In A/Gb mode, if a UMTS security context is available and if the MS indicates support of integrity protection in the MS network capability IE included in the ROUTING AREA UPDATE REQUEST message, then the MS shall use the current GPRS GSM Kint key and the current GPRS GSM integrity algorithm to integrity protect the ROUTING AREA UPDATE REQUEST message in the LLC layer. If LLC layer has not yet been configured, then the GMM layer in the MS shall assign the GPRS GSM Kint key, the GPRS GSM Kc128 key, the GPRS GSM integrity algorithm and the GPRS GSM ciphering algorithm to the LLC layer, and indicates to the LLC layer that it shall start integrity protection. This shall be done so that the LLC layer can integrity protect, but not cipher, the ROUTING AREA UPDATE REQUEST message. The MS shall include the CKSN in the CKSN IE in the ROUTING AREA UPDATE REQUEST message. If the MS has no UMTS security context available, then the MS shall not integrity protect the ROUTING AREA UPDATE REQUEST message in the LLC layer. The MS shall in this case set the CKSN IE to the value "no key is available" and send the ROUTING AREA UPDATE REQUEST message unprotected.