Description
A Universal Resource Identifier (URI) in 3GPP is a compact sequence of characters that identifies an abstract or physical resource, adhering to IETF RFC 3986 and related standards. It is used extensively across 3GPP specifications for naming, addressing, and identifying entities such as users, services, applications, and network nodes. URIs serve as a common syntax for resource identifiers, enabling interoperability between 3GPP networks and the broader internet ecosystem. In architectures like the IP Multimedia Subsystem (IMS), URIs are crucial for user identities (e.g., SIP URIs like sip:user@domain.com), service identifiers, and routing information, forming the basis for session establishment and service invocation.
URIs work by providing a structured format that includes a scheme (e.g., sip, tel, http), authority, path, query, and fragment components. In 3GPP, specific URI schemes are standardized for various purposes. For example, SIP URIs are used for IMS user identities and routing, tel URIs for telephone numbers, and HTTP URIs for web-based services. When a UE or network element needs to reference a resource, it constructs or parses a URI according to these rules. During IMS registration, a UE provides a SIP URI as its public user identity, which the Home Subscriber Server (HSS) stores and uses for authentication and service provisioning. Routing engines in Call Session Control Functions (CSCFs) then use these URIs to direct signaling messages to the correct endpoints.
Key components in 3GPP involving URIs include the IMS core, where URIs are embedded in SIP headers like From, To, and Contact; service layer applications that use URIs for service discovery via Uniform Resource Names (URNs); and management systems where URIs identify managed objects. The URI syntax allows for extensibility, supporting parameters that convey additional information such as transport protocols or user preferences. In messaging services like SMS over IP (SMSoIP) or multimedia messaging, URIs can specify destination addresses or content locations. The parsing and validation of URIs are handled by protocol stacks in UEs and network functions, ensuring consistent interpretation across different implementations.
URI's role in 3GPP networks is multifaceted: it enables user identification and routing in IMS, facilitates service exposure through APIs (e.g., using URIs in RESTful interfaces), and supports resource location in management protocols like OMA DM or 3GPP management services. By adopting internet standards, 3GPP ensures that mobile networks can seamlessly integrate with web services and applications. URIs also underpin numbering and addressing evolution, supporting the transition from E.164 numbers to IP-based identifiers. This universality makes URIs a cornerstone for All-IP networks, supporting everything from voice over LTE (VoLTE) to IoT service layer communications.
Purpose & Motivation
The Universal Resource Identifier (URI) was incorporated into 3GPP to address the need for standardized, flexible resource identification in evolving mobile networks. Prior to its adoption, telecom systems relied heavily on E.164 numbers and proprietary addressing schemes, which were insufficient for IP-based multimedia services and internet interoperability. As 3GPP moved towards All-IP architectures with IMS in Release 5, there was a requirement for a universal naming system that could identify diverse resources—users, services, content—across heterogeneous networks. URIs, as established by IETF, provided a well-defined syntax that could unify addressing across telecom and internet domains.
URI solves problems of fragmentation and incompatibility in resource referencing. It enables seamless service discovery, session initiation, and messaging between mobile devices and internet servers. For example, in IMS, SIP URIs allow users to be identified independently of their devices or locations, supporting rich communication services. Without URIs, integrating web technologies like HTTP, email, or instant messaging into mobile networks would be cumbersome. URIs also future-proof addressing by accommodating new schemes and parameters as services evolve, such as for IoT device identifiers or API endpoints.
Historically, URI adoption in 3GPP was motivated by the convergence of telecom and IT, driven by the rise of multimedia and data services. Release 2 saw early use in messaging, but it was with IMS that URIs became central. They addressed limitations of traditional telecom identifiers by supporting alphanumeric formats, domain-based routing, and extensibility. This allowed 3GPP networks to offer innovative services like presence, video calling, and web integration, competing with OTT providers. URIs continue to be essential for 5G service-based architectures and network slicing, where resources need unique, scalable identifiers.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (68 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, clarifications and corrections were made to the handling and structure of URIs across several protocols and services. Specific updates included clarifying URI and address assignments, introducing the "user=phone" parameter for SIP URIs in the P-Asserted-Identity header, and correcting the Resource URI structure for the SoRProtection Service. Furthermore, corrections were applied to the expression of URI variables in the 5g-aka-confirmation resource and to the rules for mapping directory numbers (DN) to URIs.
- Clarification to URI and address assignments TS 24.379CR0387
- "user=phone" URI parameter for SIP URIs in the SIP P-Asserted-Identity header field TS 29.163CR1016
- Correcting Resource URI structure of the SoRProtection Service TS 29.509CR0027
- Correct the expression of URI variables in 5g-aka-confirmation resource TS 29.509CR0051
- Correct the DN to URI mapping rules TS 32.158CR0003
In Release 16, new URI functionality included adding support for accessing the absolute URI associated with the media storage function of the MCData content server and for file display. The release also introduced updates for server URIs in location management and initial MC service UE configuration, while performing corrections and structural refinements such as removing duplicated server URI definitions and standardizing the removal of trailing forward slashes in resource URIs.
- Accessing the absolute URI associated with the media storage function TS 24.282CR0115
- Included absolute URI associated with the media storage function of MCData content server TS 24.483CR0066
- Included absolute URI associated with the media storage function of MCData content server TS 24.484CR0135
- Add location management sever URI to initial MC service UE configuration TS 23.280CR0186
- Remove the duplicated Key Management Server URI definiton TS 23.280CR0194
- Remove the duplicated MCPTT server URI in UE configuration table TS 23.379CR0208
+ 13 more changes
In Release 17, the primary enhancements for the URI function involved a series of corrections and clarifications to ensure proper operation across various mission-critical services. These included specific fixes to the Request-URI and elements like `<mcptt-request-uri>`, `<mcvideo-request-uri>`, and `<mcdata-request-uri>` for group geographic and emergency alert area notifications, alongside corrections to API and resource URIs for services like Naf_EventExposure. The release also formalized the use of the `<functional-alias-URI>` element and worked on aligning API URIs with service-based interface templates.
- Corrections to Request-URI and <mcvideo-request-uri> for group geo and emergency alert area notification TS 24.281CR0134
- MCData - Corrections to Request-URI and <mcdata-request-uri> for group geo and emergency alert area notification TS 24.282CR0243
- Several corrections related to use of functional alias URI and its resolution response TS 24.282CR0325
- Correcting Request-URI for emergency alert TS 24.379CR0732
- Several corrections related to use of functional alias URI and its resolution response TS 24.379CR0816
- Corrections to the API URI TS 29.509CR0136
+ 16 more changes
In Release 18, enhancements to the URI function included the introduction of a functional alias URI requirement and its application in procedures like emergency alert cancellation and SNM. Corrections were made to URI definitions and usage within specific interfaces and data types, such as for `mcvideo-regroup-uri-Type`, `mcdata-regroup-uri-Type`, and the `Nnwdaf_DataManagement` API. Additionally, clarifications and fixes were applied to elements like `called-functional-alias-URI` and the callback URI for the `mbsSession` service.
- Functional Alias URI requirement TS 23.280CR0335
- Resolving the target KMS URI for a migrated MC service user TS 23.280CR0361
- Fix use of call-to-functional-alias-ind, called-functional-alias-URI and functional-alias-URI within anyExt TS 24.281CR0183
- Fix the missing use of functional-alias-URI in emergency alert cancel request TS 24.281CR0184
- Correction for mcvideoregroup XSD for "mcvideo-regroup-uri-Type" TS 24.281CR0197
- Fix use of call-to-functional-alias-ind, called-functional-alias-URI and functional-alias-URI within anyExt TS 24.282CR0338
+ 7 more changes
In Release 19, the enhancements for the URI function included the addition of an LMS URI within the MCS UE initial configuration Managed Object and document, the introduction of a default location configuration URI, and refinements to the format of structured URI query parameters. The release also addressed corrections to the resource URI structure and notification URI, alongside implementing an affiliation check for SIP MESSAGE requests used for absolute URI discovery.
- Addition of LMS URI in MCS UE initial configuration MO TS 24.483CR0186
- Addition of LMS URI in MCS UE initial configuration document TS 24.484CR0280
- Default location configuration URI TS 24.484CR0290
- The format of the structured URI query parameters TS 24.558CR0115
- Incorrect resource URI structure TS 29.520CR1072
- Incorrect Notification URI TS 29.520CR1146
+ 3 more changes
Explore further
Broader topics and technologies where URI plays a role.
Defining Specifications
3GPP specifications that define or reference URI, 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 |
| TS 22.495 v1700 | NGN Requirements for IMS Services | Rel-7 |
| TR 22.977 vj00 | Speech Enabled Services and Multimodal Framework | Rel-19 |
| TS 23.057 vj00 | Mobile Execution Environment (MExE) Specification | Rel-19 |
| TS 23.140 v1600 | MMS Non-Realtime Service Definition | Rel-6 |
| TS 23.179 vd50 | MCPTT Functional Architecture | Rel-13 |
| TS 23.222 vj80 | Common API Framework for 3GPP Northbound APIs | Rel-19 |
| TS 23.280 vk10 | Common Architecture for Mission Critical Services | Rel-20 |
| TS 23.283 vk00 | Mission Critical Communication Interworking | Rel-20 |
| TS 23.379 vk00 | MCPTT Functional Architecture | Rel-20 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TS 23.722 vf10 | Common API Framework (CAPIF) for 3GPP Northbound APIs | Rel-15 |
| TR 23.758 vh00 | Study on Edge Application Architecture | Rel-17 |
| TS 23.782 vf00 | Interworking between LTE MC and non-LTE MC systems | Rel-15 |
| TR 23.783 vi00 | Technical Report on Mission Critical Services over 5GS | Rel-18 |
| TR 23.976 vj00 | Push Service Requirements Analysis | Rel-19 |
| TS 24.109 vj00 | HTTP Digest AKA & GAA Stage 3 | Rel-19 |
| TS 24.141 vj00 | Presence Service Protocol Details | Rel-19 |
| TS 24.173 vj00 | Multimedia Telephony Service and Supplementary Services in IMS | Rel-19 |
| TS 24.196 vj00 | Enhanced Calling Name (eCNAM) Stage 3 Protocol | Rel-19 |
| TS 24.206 v1700 | Voice Call Continuity Between CS and IMS | Rel-7 |
| TS 24.228 v1500 | IP Multimedia Call Control Signaling Flows | Rel-5 |
| TS 24.229 vj50 | IMS call control protocol based on SIP and SDP | Rel-19 |
| TS 24.259 vj00 | Personal Network Management (PNM) Protocol Details | Rel-19 |
| TS 24.281 vj40 | MCVideo Signalling Control Specification | Rel-19 |
| TS 24.282 vj50 | MCData Signalling Control Protocols | Rel-19 |
| TS 24.292 vj00 | IMS Centralized Services (ICS) Protocol | Rel-19 |
| TS 24.322 vj00 | IMS Tunneling over Restrictive Networks | Rel-19 |
| TS 24.379 vj50 | Mission Critical Push To Talk (MCPTT) call control | Rel-19 |
| TS 24.404 v1700 | Communication Diversion Services (CDIV) | Rel-7 |
| TS 24.406 v810 | Message Waiting Indication (MWI) Protocol | Rel-8 |
| TS 24.407 v830 | OIP and OIR Simulation Services Protocol | Rel-8 |
| TS 24.416 v1700 | Malicious Call Identification Service | Rel-7 |
| TS 24.423 v850 | PSTN/ISDN Simulation Services XCAP Protocol | Rel-8 |
| TS 24.454 v840 | Closed User Group (CUG) Protocol Specification | Rel-8 |
| TS 24.481 vj20 | Mission Critical Services (MCS) group management | Rel-19 |
| TS 24.483 vj20 | Mission Critical Services Management Object | Rel-19 |
| TS 24.484 vj30 | MCS Configuration Management | Rel-19 |
| TS 24.504 v8m0 | Communication Diversion Services Stage 3 | Rel-8 |
| TS 24.516 v830 | MCID Protocol Specification for NGN | Rel-8 |
| TS 24.523 vj00 | NGCN-NGN Interconnection Scenarios | Rel-19 |
| TS 24.524 vj00 | Hosted Enterprise Services Architecture | Rel-19 |
| TS 24.525 vj00 | Business Trunking Architecture & Requirements | Rel-19 |
| TS 24.542 vj00 | SEAL Notification Management Protocol | Rel-19 |
| TS 24.543 vj50 | SEAL Data Delivery Management Protocol | Rel-19 |
| TS 24.558 vj50 | Edge Enabler APIs Stage 3 | Rel-19 |
| TS 24.583 vj00 | Application Layer Support for Personal IoT Network | Rel-19 |
| TS 24.604 vj00 | Communications Diversion (CDIV) Protocol Spec | Rel-19 |
| TS 24.606 vj00 | MWI Service Protocol Description | Rel-19 |
| TS 24.607 vj10 | OIP and OIR Supplementary Services Stage 3 | Rel-19 |
| TS 24.616 vj00 | Malicious Call Identification (MCID) Protocol | Rel-19 |
| TS 24.623 vj00 | XCAP Protocol for Supplementary Services | Rel-19 |
| TS 24.654 vj00 | Closed User Group (CUG) supplementary service | Rel-19 |
| TS 24.841 v1600 | Presence Service IP Multimedia Subsystem | Rel-6 |
| TS 24.883 vg00 | MCPTT Interworking with LMR Systems | Rel-16 |
| TS 26.150 vj00 | Syndicated Feed Reception (SFR) Specification | Rel-19 |
| TS 26.233 vf00 | 3GPP Packet-Switched Streaming Service (PSS) | Rel-15 |
| TS 26.234 vj00 | 3GPP PSS Protocols and Codecs Specification | Rel-19 |
| TS 26.237 vj00 | IMS for PSS and MBMS Control | Rel-19 |
| TS 26.247 vj00 | 3GPP Progressive Download & DASH over HTTP | Rel-19 |
| TS 26.346 vj20 | MBMS User Services Media Codecs & Protocols | Rel-19 |
| TS 26.510 vj10 | Media Delivery APIs for 5GMS and RTC Systems | Rel-19 |
| TS 26.512 vj10 | 5G Media Streaming Protocols & APIs | Rel-19 |
| TS 26.804 vj10 | 5G Media Streaming Extensions Study | Rel-19 |
| TS 26.851 vb20 | Enhancements to Multimedia (EMM) for PSS, MMS, MBMS | Rel-11 |
| TR 26.938 vj00 | DASH Deployment Guidelines for 3GPP Networks | Rel-19 |
| TR 26.946 vj00 | MBMS User Services Overview | Rel-19 |
| TR 26.955 vj00 | Video Codec Analysis for 5G Services | Rel-19 |
| TS 29.116 vj00 | REST-based protocol for xMB reference point | Rel-19 |
| TS 29.163 vj00 | Interworking between 3GPP IM CN and CS networks | Rel-19 |
| TS 29.199 v1900 | Multimedia Messaging Web Services | Rel-9 |
| TS 29.201 vj00 | RESTful Rx Interface for AF-PC Communication | Rel-19 |
| TS 29.379 vj00 | MCPTT call control interworking with LMR systems | Rel-19 |
| TS 29.509 vj50 | AUSF Service Based Interface Protocol | Rel-19 |
| TS 29.517 vj40 | 5G AF Event Exposure Service Stage 3 | Rel-19 |
| TS 29.520 vj40 | 5G Network Data Analytics Services Stage 3 | Rel-19 |
| TS 29.532 vj30 | MB-SMF Service Based Interface Protocol | Rel-19 |
| TS 29.573 vj50 | PLMN/SNPN Interconnection Interface Stage 3 | Rel-19 |
| TS 29.580 vj30 | 5G MBSF Service Interface Stage 3 Specification | Rel-19 |
| TS 29.581 vj20 | MBSTF Service Based Interface Protocol Specification | Rel-19 |
| TS 29.591 vj40 | 5G NEF Southbound Services Stage 3 | Rel-19 |
| TS 31.829 vd00 | ISIM Conformance Requirements Technical Report | Rel-13 |
| TS 32.153 vj00 | IRP Technology-Specific Templates Specification | Rel-19 |
| TS 32.158 vk00 | Management and Orchestration REST Solution Sets | Rel-20 |
| TS 32.182 vj00 | UDC Common Baseline Information Model (CBIM) | Rel-19 |
| TS 32.808 v1800 | Common User Profile Storage Framework | Rel-8 |
| TS 33.107 vj00 | Lawful Interception Architecture & Functions | Rel-19 |
| TS 33.108 vj00 | LI Handover Interface Specification | Rel-19 |
| TS 33.117 vk00 | Catalogue of General Security Assurance Requirements | Rel-20 |
| TS 33.320 vj00 | H(e)NB Subsystem Security Architecture | Rel-19 |
| TR 33.739 vi10 | Study on security enhancement of support for | Rel-18 |
| TS 33.822 v1800 | Security Architecture for Inter-Access Mobility | Rel-8 |
| TR 33.978 v1800 | Interim Security for Early IMS | Rel-8 |
| TS 36.579 | 3GPP TR 36.579 | Rel-2 |
| TS 37.579 vi40 | Mission Critical services conformance testing | Rel-18 |
