Description
A Declarative Object (DO) is a fundamental concept in 3GPP specifications related to Universal Subscriber Identity Module (USIM) applications and the UICC platform. Defined in specifications such as TS 31.102 (USIM characteristics) and TS 26.953 (IMS Multimedia Telephony service), a DO is a structured data object that uses a declarative language to describe the behavior, configuration, or presentation of a service. Unlike procedural objects that specify step-by-step instructions, a DO declares 'what' should be achieved, leaving the 'how' to the interpreting entity (e.g., the USIM or terminal). DOs are typically constructed using a tag-length-value (TLV) encoding scheme, where tags identify the type of object, length indicates the size of the value field, and value contains the actual declarative data. They are used to define elements like menu entries, call control rules, service parameters, or security policies within the USIM application. For instance, a DO can describe a menu structure for value-added services, allowing the mobile terminal to render a user interface directly from the USIM data. The USIM file system (EF, DF) often contains files comprised of one or more DOs. The terminal reads these DOs, interprets their meaning based on standardized tags, and executes the corresponding actions. This mechanism enables service personalization and network-driven updates, as operators can modify DOs via Over-The-Air (OTA) provisioning to change service behavior without replacing the physical SIM card. DOs are essential for enabling standardized, interoperable value-added services across different handset manufacturers and network operators.
Purpose & Motivation
Declarative Objects were introduced to overcome the limitations of hard-coded, procedural service logic on SIM/USIM cards, which made service deployment and updates cumbersome and inflexible. Prior to DOs, adding or modifying a service often required issuing new physical SIM cards or using proprietary, non-interoperable methods. The primary motivation was to create a standardized, flexible mechanism for describing and provisioning services on the UICC in a way that is independent of the terminal's implementation details. DOs enable a clear separation between service description (on the USIM) and service execution (on the terminal), promoting interoperability. This declarative approach allows network operators to dynamically configure services, such as multimedia telephony settings, address book structures, or service menus, via OTA updates. It simplifies the introduction of new services, reduces time-to-market, and enhances the user experience by allowing personalized service configurations. DOs are a cornerstone of the SIM Application Toolkit (SAT) and USIM Application Toolkit (USAT) ecosystems, enabling a wide range of value-added services from basic call control to advanced IMS-based applications.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (28 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-4, normative work from Rel-15.
In Release 15, updates to the USIM function introduced configuration support for 5GS, including enhanced PDU session call control and Mission Critical Services via the USIM Service Table. Specific enhancements allowed for the configuration of Access Identity 2 and extended USIM OPL configuration to support a 3-byte TAC for operation in NG-RAN. Furthermore, the release provided clarifications and updates to USIM management procedures for the 5G System.
- USIM Service Table update for PDU session call control support TS 31.102CR0786
- Allow configuration of MCS (Access Identity 2) via USIM. TS 31.102CR0794
- Mission Critical Services configuration data update to USIM TS 31.102CR0808
- Enhance USIM OPL configuration to support 3 bytes TAC when in NG-RAN. TS 31.102CR0818
- Updates to USIM management procedures for 5GS TS 31.102CR0806
- Clarification about presence of EFIMSConfigData in ISIM and USIM TS 31.102CR0833
In Release 16, the DO function was enhanced to allow the USIM to store configuration data for new network policies and access controls. Specifically, this included support for storing a PS Data Off list for home and roaming, a Trusted non-3GPP access networks list, and URSP rules. Additionally, new configurations for RLOS PLMN and MCC lists were introduced, along with a dedicated AID for USIM applications using non-IMSI based SUPI types.
- 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
- Dedicated AID for USIM Applications with non-IMSI based SUPI Types TS 31.102CR0897
+ 3 more changes
In Release 17, the DO function was enhanced by introducing several new USIM files for network configuration and policy storage. These additions specifically included files for pre-configured CAG information, SOR-CMCI parameters, disaster roaming settings, eDRX parameters for NG-RAN, and configuration for 5G NSWO and warning messages in SNPNs. This expanded the USIM's role in declaratively managing device behavior for features like network selection, mobility, and service reception.
- Introduce a USIM file to store pre-configured CAG information list TS 31.102CR0904
- SOR-CMCI storage in USIM TS 31.102CR0917
- Addition of USIM files for the indication of whether disaster roaming is enabled in the UE, disaster roaming wait range, disaster return wait range and applicability indicator for disaster roaming PLMNs list provided by VPLMN. TS 31.102CR0938
- Adding eDRX parameters in the USIM for NG-RAN TS 31.102CR0943
- 5G NSWO (Non-Seamless WLAN Offload) configuration support in the USIM compromised proposal. TS 31.102CR0946
- Support of 'No E-UTRA Disabling In 5GS' in USIM TS 31.102CR0947
+ 2 more changes
In Release 18, the Declarative Object (DO) function was expanded with new Elementary Files (EFs) on the USIM for enhanced service management. These additions specifically include an EF for Access Control to GBA_U_APIs and an EF for IMS Data Channel configuration. Furthermore, the release mandated the enabling of Service n°133 whenever Service n°123 is enabled to ensure consistent security parameter storage.
In Release 19, the DO function introduced new handling for backward compatibility with USIMs that lack extended security parameter storage in the EF_5GAuthKeys file. This ensures proper operation with legacy USIM applications on the UICC. Additionally, corrections were made to address an incorrect data object format for the SOR-CMCI.
Explore further
Broader topics and technologies where DO plays a role.
Defining Specifications
3GPP specifications that define or reference DO, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TR 26.953 vj00 | Study on Service Interactivity for Streaming & Download | Rel-19 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |