International Mobile Subscriber Identity

In Release 15, key enhancements for the IMSI function and subscriber identity management included the introduction of new USIM configuration mechanisms for 5G-specific access control. Specifically, this release enabled the storage of 5G UAC Access Identity Information, including the MCS (Access Identity 2) indicator, directly on the USIM via a new Elementary File (EF). Furthermore, it allowed for the configuration of NAS signalling low priority and other access identities via OMA-DM or the USIM, aligning subscriber identity capabilities with the new 5G system requirements.

• Support for identity attestation and verification TS 23.228CR1184
• Description of MC system identity TS 23.280CR0138
• UE configuration for AC 11-15 and MCS (access identity 2) TS 24.501CR0083
• UE configuration for NAS signalling low priority via OMA-DM or USIM not applicable in 5GS TS 24.501CR0084
• Preferred list terminating at ME or USIM TS 24.501CR0212
• MCS Indicator and Access Identity 2 TS 24.501CR0614

+ 35 more changes

In Release 16, the IMSI's role was extended by enhancing the USIM's configuration capabilities for new network types, specifically for SNPNs (Standalone Non-Public Networks) and trusted non-3GPP access. The release introduced new USIM-stored configuration lists, such as for RLOS (Radio Link Outage Survival) PLMN lists and trusted non-3GPP access networks, and clarified the validity of the USIM for specific access types within an SNPN. Additionally, it defined procedures for identity handling in SNPNs, specifying that a 5G-GUTI is not globally unique in an SNPN and detailing the use of a 5GMM cause value for SNPNs with a globally-unique identity.

• Usage of PDU session identity for the PDU sessions requested by the TWIF TS 24.501CR1686
• Support for USIM configuration of RLOS PLMN list TS 31.102CR0847
• URSP storage in USIM TS 31.102CR0861
• Specify storage for a potentially separate KSEAF for non-3gpp access on the USIM TS 31.102CR0864
• USIM configuration of RLOS allowed MCC list TS 31.102CR0881
• Support for Trusted non-3GPP access networks list by USIM TS 31.102CR0891

+ 25 more changes

In Release 17, the IMSI function was extended to support Multi-USIM devices in 5GS, including new UE support indications and the use of the Service Request procedure for managing paging restrictions. It also introduced new USIM storage for parameters like SOR-CMCI, eDRX for NG-RAN, and disaster roaming configurations, including a specific access identity for disaster roamers. Furthermore, enhancements were made for storing pre-configured CAG information lists and Non-Seamless WLAN Offload (NSWO) configurations directly on the USIM.

• "List of subscriber data" handling for SNPN supporting AAA-Server for primary authentication and authorization TS 24.501CR3133
• Definitions and abbreviations for Multi-USIM in 5GS TS 24.501CR3119
• Using Service Request procedure for removing paging restrictions in 5GS for a Multi-USIM UE TS 24.501CR3226
• Multi-USIM UE support indications in 5GS TS 24.501CR3121
• Introducing access identity 3 for disaster roamer TS 24.501CR3679
• Transferring Alternative IMSI between MMEs TS 29.274CR2048

+ 36 more changes

In Release 18, the IMSI function was enhanced through new USIM capabilities for Equivalent Standalone Non-Public Networks (SNPNs), including mechanisms for mobile identity selection and the invalidation of subscriber data lists. The release also introduced extended storage for 5G security parameters on the USIM by mandating that Service n°133 be enabled when Service n°123 is enabled. Furthermore, it clarified procedures for USIM validity in 5GS services and added new Elementary Files (EFs) to the USIM for Access Control to GBA_U_APIs and IMS Data Channel configuration.

• Equivalent SNPN usage for mobile identity selection TS 24.501CR4840
• Equivalent SNPNs: entry of list of subscriber data becoming invalid TS 24.501CR5028
• 5G Security Parameters extended storage on USIM (Mandating Service n°133 to be enabled when Service n°123 is enabled) Rel18. TS 31.102CR1014
• Add EF of Access Control to GBA_U_APIs to the USIM TS 31.102CR1007
• Add EF of IMS Data Channel configuration to the USIM TS 31.102CR1006
• Introduction of mobile IAB for NR TS 38.304CR0370

+ 15 more changes

In Release 19, the key new development for the IMSI function was the introduction of support for third-party user identity information within the IMS, including the associated procedure and an updated IETF reference for signing and verifying this identity. The release also focused on identity management clarifications and corrections, specifically addressing the 5GS mobile identity and UE actions upon 5G-GUTI deletion. Additionally, it included backward compatibility handling for USIMs without extended security parameter storage in the EF_5GAuthKeys file.

• Support of third party user identity information in IMS TS 23.228CR1478
• Procedure for supporting of third party user identity information in IMS TS 23.228CR1524
• Update the IETF reference to the process of signing and verifying third party user identity information TS 23.228CR1652
• KI#1: Cancel procedure for subscriber specific IMS Events TS 23.228CR1655
• Use of native 4G-GUTI TS 24.501CR6417
• Clarification of the mobile reachable tmer to avoid an expired timer in the unavailability period TS 24.501CR6542

+ 4 more changes