Section: 10.5.1.4 Mobile Identity
Content: The purpose of the Mobile Identity information element is to provide either the international mobile subscriber identity, IMSI, the temporary mobile subscriber identity, TMSI/P-TMSI/M-TMSI, the international mobile equipment identity, IMEI, the international mobile equipment identity together with the software version number, IMEISV, or the temporary mobile group identity (TMGI), associated with the optional MBMS Session Identity. The IMSI shall not exceed 15 digits, the TMSI/P-TMSI/M-TMSI is 4 octets long, and the IMEI is composed of 15 digits, the IMEISV is 16 digits (see 3GPP TS 23.003[ Numbering, addressing and identification ]  [10]). The TMGI is at maximum 6 octets long and is defined in subclause 10.5.6.13. The MBMS Session Identity, if included, is 1 octet long (see 3GPP TS 48.018[ None ]  [86]). For packet paging the network shall select the mobile identity type with the following priority: 1- P-TMSI: The P-TMSI shall be used if it is available. 2- IMSI: The IMSI shall be used in cases where no P-TMSI is available. For MBMS (pre-)notification (see 3GPP TS 44.018[ None ]  [84] and 3GPP TS 44.060[ None ]  [76]) the network shall select the mobile identity type "TMGI and optional MBMS Session Identity". NOTE 1: The type of identity "TMGI and optional MBMS Session Identity" is only used by the MBMS (pre-)notification procedure in of A/Gb mode. For all other transactions with the following exceptions: - emergency call establishment, emergency call re-establishment, mobile terminated call establishment, the identification procedure, the GMM identification procedure, the GMM authentication, GPRS attach, routing area updating, and ciphering procedure and the ciphering mode setting procedure; and - location updating when the MS is configured for "AttachWithIMSI" as specified in 3GPP TS 24.368[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [135] or 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [112] and the selected PLMN is neither the registered PLMN nor in the list of equivalent PLMNs; the mobile station and the network shall select the mobile identity type with the following priority: 1- TMSI: The TMSI shall be used if it is available. 2- IMSI: The IMSI shall be used in cases where no TMSI is available. For mobile terminated call establishment the mobile station shall select the same mobile identity type as received from the network in the PAGING REQUEST message. In case of enhanced DTM CS establishment (see 3GPP TS 44.018[ None ]  [84]) the mobile station shall select the mobile identity type with the following priority in the PAGING RESPONSE message: 1- TMSI: The TMSI shall be used if it is available. 2- IMSI: The IMSI shall be used in cases where no TMSI is available. For the PAGING RESPONSE message sent as a response to a paging for CS fallback, the MS shall: - select the TMSI as mobile identity type if the network has, in E-UTRAN, - paged the MS for CS fallback using the S-TMSI; or - indicated TMSI in the CS SERVICE NOTIFICATION message (see 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120]); - select the IMSI as mobile identity type if the network has, in E-UTRAN, - paged the MS for CS fallback using the IMSI; or - indicated IMSI in the CS SERVICE NOTIFICATION message (see 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120]). For emergency call establishment and re-establishment the mobile station shall select the mobile identity type with the following priority: 1- TMSI: The TMSI shall be used if it is available and if the location update status is UPDATED, and the stored LAI is equal to the one received on the BCCH from the current serving cell. 2- IMSI: The IMSI shall be used in cases where no TMSI is available or TMSI is available but either the update status is different from UPDATED, or the stored LAI is different from the one received on the BCCH from the current serving cell. 3- IMEI: The IMEI shall be used in cases where no SIM/USIM is available or the SIM/USIM is considered as not valid by the mobile station or no IMSI or TMSI is available. In the identification procedure and in the GMM identification procedure the mobile station shall select the mobile identity type which was requested by the network, if available. If the requested identity is not available, then the mobile station shall indicate the identity type "No Identity". In the ciphering mode setting procedure and in the GMM authentication and ciphering procedure the mobile shall select the IMEISV. The Mobile Identity information element is coded as shown in figure 10.5.4/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  and table 10.5.4/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] . The Mobile Identity is a type 4 information element with a minimum length of 3 octet and 11 octets length maximal. Further restriction on the length may be applied, e.g. number plans. Figure 10.5.4/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  Mobile Identity information element Figure 10.5.4a/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Mobile Identity information element for type of identity "TMGI and optional MBMS Session Identity" Table 10.5.4/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Mobile Identity information element