ETSI TS 133 127 V19.6.0 (2026-04)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; 5G; Lawful Interception (LI) architecture and functions (3GPP TS 33.127 version 19.6.0 Release 19)

RTS/TSGS-0333127vj60

General Information

• Status: Not Published
• Technical Committee: 3GPP SA 3 - Security
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Completion Date: 02-Apr-2026

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
5G;
Lawful Interception (LI) architecture and functions
(3GPP TS 33.127 version 19.6.0 Release 19)

3GPP TS 33.127 version 19.6.0 Release 19 1 ETSI TS 133 127 V19.6.0 (2026-04)

Reference
RTS/TSGS-0333127vj60
Keywords
5G,GSM,LTE,UMTS
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ETSI
3GPP TS 33.127 version 19.6.0 Release 19 2 ETSI TS 133 127 V19.6.0 (2026-04)
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Legal Notice
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ETSI
3GPP TS 33.127 version 19.6.0 Release 19 3 ETSI TS 133 127 V19.6.0 (2026-04)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 13
Introduction . 13
1 Scope . 14
2 References . 14
3 Definitions, symbols and abbreviations . 17
3.1 Definitions . 17
3.2 Symbols . 18
3.3 Abbreviations . 18
4 Requirements realisation . 21
5 Functional architecture . 21
5.1 General . 21
5.2 High-level generic LI architecture . 21
5.3 Functional entities . 22
5.3.1 Law Enforcement Agency (LEA) . 22
5.3.2 Point of Interception (POI) . 23
5.3.2.1 General . 23
5.3.2.2 Directly provisioned and triggered POIs . 23
5.3.2.3 IRI-POIs and CC-POIs . 23
5.3.2.4 Failure handling . 23
5.3.3 Triggering Function . 23
5.3.4 Mediation and Delivery Function (MDF) . 24
5.3.5 Administration Function (ADMF) . 24
5.3.5.1 General . 24
5.3.5.2 LICF . 25
5.3.5.3 LIPF . 26
5.3.5.4 IQF . 26
5.3.5.5 LI Function Selection . 26
5.3.5.6 LAF . 27
5.3.6 System Information Retrieval Function (SIRF) . 27
5.3.7 LEMF – Law Enforcement Monitoring Facility . 27
5.3.8 LARF . 27
5.4 LI interfaces . 27
5.4.1 General . 27
5.4.2 Interface LI_SI . 29
5.4.3 Interface LI_HI1 . 29
5.4.4 Interface LI_X1 . 30
5.4.4.1 General . 30
5.4.4.2 LIPF and POI . 30
5.4.4.3 LIPF and TF . 30
5.4.4.4 LIPF and MDF2/MDF3 . 31
5.4.5 Interface LI_X2 . 31
5.4.6 Interface LI_X3 . 31
5.4.7 Interface LI_T . 32
5.4.7.1 General . 32
5.4.7.2 Interface LI_T2 . 32
5.4.7.3 Interface LI_T3 . 32
5.4.8 Interface LI_HI2 . 32
5.4.9 Interface LI_HI3 . 32
5.4.10 Interface LI_HI4 . 33
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5.4.10.1 General . 33
5.4.10.2 LI operation notification . 33
5.4.10.3 Contents of the notification . 33
5.4.11 Interface LI_ADMF . 33
5.4.12 Interface LI_MDF . 33
5.4.13 Interface LI_IQF . 33
5.4.14 Interface LI_XQR . 33
5.4.15 Interface LI_HIQR . 34
5.4.16 Interface LI_XER . 34
5.4.17 Interface LI_XEM1. 35
5.4.18 Interface LI_HILA . 35
5.4.19 Interface LI_XLA . 35
5.4.20 Interface LI_X2_LA . 35
5.4.21 Interface LI_LAFP and LI_LAFC . 36
5.5 LI service discovery . 36
5.6 LI in a virtualised environment . 36
5.6.1 General . 36
5.6.2 Virtualised deployment architecture . 36
5.6.3 LI function instantiation and lifecycle management procedures . 38
5.6.3.1 Controller virtualisation layer and MANO procedures . 38
5.6.3.1.1 Responsibilities. 38
5.6.3.1.2 General procedures . 38
5.6.3.1.3 Instantiation . 38
5.6.3.1.4 Modification . 39
5.6.3.1.5 Termination . 39
5.6.3.1.6 Direct instantiation of LI Functions by ADMF . 39
5.6.3.2 LI_X0 procedures . 39
5.6.3.3 Exception Procedures . 41
5.7 Identifier association and reporting . 42
5.7.1 General . 42
5.7.2 Functional entities . 43
5.7.2.1 Identity Query Function (IQF) . 43
5.7.2.2 Identity Event Function (IEF) . 44
5.7.2.3 Identity Caching Function (ICF) . 44
6 Network layer based interception . 45
6.1 General . 45
6.2 5G . 45
6.2.1 General . 45
6.2.2 LI at AMF . 46
6.2.2.1 Architecture . 46
6.2.2.2 Target identities . 47
6.2.2.3 Identity privacy . 48
6.2.2.4 IRI events . 48
6.2.2.5 Common IRI parameters . 49
6.2.2.6 Specific IRI parameters . 49
6.2.2.7 Network topologies . 51
6.2.2A Identifier Reporting for AMF . 51
6.2.2A.1 General . 51
6.2.2A.2 IEF Events . 51
6.2.2A.3 IEF Event parameters . 51
6.2.2A.4 Network topologies . 52
6.2.3 LI for SMF/UPF . 52
6.2.3.1 Architecture . 52
6.2.3.2 Target identities . 54
6.2.3.3 IRI events . 54
6.2.3.4 Common IRI parameters . 55
6.2.3.5 Specific IRI parameters . 55
6.2.3.6 Network topologies . 55
6.2.3.7 Multi-Access PDU (MA PDU) Session Specific . 56
6.2.3.8 LI state transfers in SMF sets . 57
6.2.3.9 Interface LI_ST . 58
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6.2.4 LI at UDM for 5G . 58
6.2.5 LI at SMSF . 58
6.2.5.1 Architecture . 58
6.2.5.2 Target identities . 59
6.2.5.3 IRI events . 60
6.2.5.4 Common IRI parameters . 60
6.2.5.5 Specific IRI parameters . 60
6.2.5.6 Network topologies . 60
6.2.6 LI support at NRF . 60
6.2.6.1 Architecture . 60
6.2.6.2 LI_SI notifications . 61
6.2.6.3 LI_SI parameters . 61
6.2.7 External data storage . 62
6.2.7.1 UDSF or UDR . 62
6.2.7.2 LI State Storage Function (LI SSF) . 62
6.3 EPC . 62
6.3.1 General . 62
6.3.2 LI at the MME . 63
6.3.2.1 Architecture . 63
6.3.2.2 Target identities . 64
6.3.2.3 IRI events . 65
6.3.2.3.1 Option A . 65
6.3.2.3.2 Option B . 66
6.3.2.4 Common IRI parameters . 66
6.3.2.5 Specific IRI parameters . 67
6.3.2.5.1 Option A . 67
6.3.2.5.2 Option B . 68
6.3.2.6 Network topologies . 69
6.3.3 LI at SGW/PGW . 69
6.3.3.1 Architecture . 69
6.3.3.1.1 General . 69
6.3.3.1.2 Non-CUPS architecture . 70
6.3.3.1.3 EPS CUPS Architecture . 71
6.3.3.2 Target identities . 73
6.3.3.3 IRI events . 73
6.3.3.3.1 Option A . 73
6.3.3.3.2 Option B . 75
6.3.3.4 Common IRI parameters . 75
6.3.3.5 Specific IRI parameters . 75
6.3.3.6 Network topologies . 75
6.3.3.6.1 Network topologies without EPC/5GC interworking . 75
6.3.3.6.2 Network topologies with EPC/5GC interworking . 76
6.3.3.7 EPC-5GC Interworking via SMF+PGW-C and UPF+PGW-U . 76
6.3.4 LI at ePDG . 76
6.3.4.1 Architecture . 76
6.3.4.2 Target identities . 78
6.3.4.3 IRI events . 78
6.3.4.4 Common IRI parameters . 78
6.3.4.5 Specific IRI parameters . 78
6.3.4.6 Network topologies . 78
6.4 3G . 78
6.5 VoNR . 78
6.6 4G/5G Interworking . 79
7 Service layer based interception . 79
7.1 General . 79
7.2 Central subscriber management . 79
7.2.1 General . 79
7.2.2 LI at UDM . 80
7.2.2.1 Architecture . 80
7.2.2.2 Target identities . 81
7.2.2.3 Identity privacy . 81
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7.2.2.4 IRI events . 81
7.2.2.5 Common IRI parameters . 82
7.2.2.6 Specific IRI parameters . 82
7.2.2.7 Network topologies . 82
7.2.3 LI at HSS . 82
7.2.3.1 Architecture . 82
7.2.3.2 Target identities . 83
7.2.3.3 IRI events . 84
7.2.3.4 Common IRI parameters . 84
7.2.3.5 Specific IRI parameters . 84
7.2.3.6 Network topologies . 84
7.2.4 LI at the IMS supporting HSS . 84
7.2.4.1 Architecture . 84
7.2.4.2 Target identities . 85
7.2.4.3 IRI events . 85
7.2.4.4 Common IRI parameters . 85
7.2.4.5 Specific IRI parameters . 85
7.2.4.6 Network topologies . 85
7.3 Location . 86
7.3.1 General . 86
7.3.2 Service usage location reporting . 86
7.3.2.1 General . 86
7.3.2.2 Embedded location reporting . 86
7.3.2.3 Separated location reporting. 86
7.3.3 Lawful Access Location Services (LALS) . 87
7.3.3.1 General . 87
7.3.3.2 Target positioning . 87
7.3.3.2.1 General . 87
7.3.3.2.2 Immediate location provision . 88
7.3.3.2.3 Periodic location provision . 88
7.3.3.2.4 Intermediate and multiple location provision . 88
7.3.3.3 Triggered location . 89
7.3.3.4 LI_X2 interface for target positioning and triggered location . 90
7.3.4 Cell database information reporting . 90
7.3.5 Location Acquisition. 92
7.3.5.1 General . 92
7.3.5.2 Location acquisition architecture . 92
7.3.5.2.1 Location information delivery via the LI_HILA . 92
7.3.5.2.2 Location information delivery via the LI_HI2 . 93
7.4 IMS . 93
7.4.1 General . 93
7.4.2 Architecture . 94
7.4.2.1 Overview . 94
7.4.2.2 Target identities . 95
7.4.2.3 Target identification . 96
7.4.3 IRI-POI . 96
7.4.3.1 General . 96
7.4.3.2 IRI events . 96
7.4.3.3 Common IRI parameters . 97
7.4.3.4 Specific IRI parameters . 97
7.4.4 CC-TF and CC-POI . 98
7.4.4.1 General . 98
7.4.4.2 CC intercept trigger . 98
7.4.4.3 Common CC parameters . 98
7.4.5 Correlation of xCC and xIRI. 99
7.4.6 Network topologies . 99
7.4.6.1 General . 99
7.4.6.2 IMS Network Functions providing the IRI-POI . 99
7.4.6.3 IMS Network Functions providing the CC-TF and CC-POI functions . 102
7.4.7 Roaming cases . 103
7.4.7.1 Media unavailable in a roaming case . 103
7.4.7.2 S8HR . 103
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3GPP TS 33.127 version 19.6.0 Release 19 7 ETSI TS 133 127 V19.6.0 (2026-04)
7.4.7.2.1 Background .
...