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SPECIAL REPORT
Lawful Interception (LI);
IMS and LTE FAQ and Guidance
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2 ETSI SR 003 292 V1.2.1 (2018-09)
Reference
RSR/LI-00162
Keywords
IMS, lawful interception, LTE, RCS, VoLTE
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3 ETSI SR 003 292 V1.2.1 (2018-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Abbreviations . 8
4 Questions and guidance statements . 10
4.0 Introduction . 10
4.1 General solution architecture . 11
4.1.1 Introduction. 11
4.1.2 Question: What is the relationship between LTE and EPS? . 11
4.1.3 Question: What is new in the EPS/IMS architecture? . 11
4.1.4 Question: What is the service definition of VoLTE? . 11
4.1.5 Question: What other services are combined with VoLTE? . 11
4.1.6 Question: What types of IMS are there internationally? . 12
4.1.7 Question: What types of IMS service are of relevance to LEAs? . 12
4.2 Applicable international standards . 12
4.2.1 Introduction. 12
4.2.2 Question: What are the applicable international LI and DR standards? . 12
4.2.3 Question: What are the applicable VoLTE standards? . 13
4.2.4 Question: What are the pros and cons of the international LI and DR standards? . 13
4.3 Nodes and Intercept Access Points/Points of Intercept . 13
4.3.1 Introduction. 13
4.3.2 Question: For VoLTE intercept, what are the options for the IAPs and their pros and cons? . 13
4.3.3 Question: For IMS intercept, what are the options for the IAPs and their pros and cons? . 14
4.4 Identities used in IMS and how to target the right identity/identities . 14
4.4.1 Introduction. 14
4.4.2 Question: What are the available target identities? . 14
4.4.3 Question: Is IMSI and IMEI interception possible for IMS? . 15
4.4.4 Question: Is it always possible to determine who initiated an IMS session (or an IMS dialog), and
flagging which was targeted?. 16
4.4.5 Question: How can the start, end and duration of a session be defined? . 16
4.4.6 Question: How can the the direction and context of a session be defined? . 16
4.4.7 Question: Are device identifiers or P-GRUUs seen or both? Also, is the PANI header
available/useful? . 16
4.4.8 Question: Can location information be obtained from IMS? . 16
4.4.9 Question: How can location information be obtained? . 17
4.4.10 Question: How can present location information be obtained ? . 17
4.4.11 Question: How can location informationbe correlated (e.g. from access to service or vice versa)? . 17
4.4.12 Question: Are login and presence events seen? . 17
4.4.13 Question: Is it possible to determine the IP addresses of the participants (e.g. target and non-target)? . 17
4.5 Detailed call/sessions flows and guidance with regard to multi-location or multi-country sessions . 17
4.5.1 Question: Is it possible to enforce the use of clear media and clear signalling in the visiting network
possible? . 17
4.5.2 Question: Where is it decided what roaming scenarios are allowed or supported? . 17
4.5.3 Question: Do roamers always go back to their home network for their services? . 18
4.6 Supplementary Services . 18
4.6.1 Introduction. 18
4.6.2 Question: Will the Supplementary Services change? . 18
4.7 Terminals, LEMF capabilities and E2E issues . 19
4.7.1 Introduction. 19
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4 ETSI SR 003 292 V1.2.1 (2018-09)
4.7.2 Question: Should all of the signalling interpretation responsibility be placed on the LEMF?. 19
4.7.3 Question: Can the responsibility for the interpretation of the signalling be placed on the LEMF? . 19
4.8 Correlation . 19
4.8.1 Question: How can different identities for a single party be performed? . 19
4.8.2 Question: How can HI2 and HI3 be correlated? . 19
4.8.3 Question: How can you correlate different sessions between different accesses (e.g. CS call and
VoLTE call)? . 20
4.9 Codecs, codec changes and other issues affecting voice quality . 20
4.9.1 Introduction. 20
4.9.2 Question: What common codecs are seen? . 20
4.9.3 Question: Are there likely to be codecs beyond those specified in the core VoLTE specification
which are being used or expected to be used in VoLTE? . 20
4.9.4 Question: If proprietary codecs are used then appropriate technical details and licenses need to be
provided? . 21
4.9.5 Question: Can the IMS operators limit the codecs which are used? . 21
4.10 Impacts and dependencies on existing CS solutions . 21
4.10.1 Introduction. 21
4.10.2 Question: Is "double interception" possible? . 21
4.11 Related or complimentary technologies . 21
4.11.1 Introduction. 21
4.11.2 Question: What are the links or cross-overs with the Internet of Things? . 22
4.11.3 Question: What are the links to eCall?. 22
Annex A: Change Request history . 23
History . 24
ETSI
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5 ETSI SR 003 292 V1.2.1 (2018-09)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Special Report (SR) has been produced by ETSI Technical Committee Lawful Interception (LI).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document provides a summary of some of the issues that members of ETSI TC LI believe to be important
in relation to the Lawful Interception of IMS (IP Multimedia Subsystem) and LTE (Long Term Evolution).
ETSI
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6 ETSI SR 003 292 V1.2.1 (2018-09)
1 Scope
The present document provides guidance to interested parties regarding implementation of Lawful Interception (LI) for
LTE, IMS and related services. It covers what is available and how it may be interpreted.
The present document is in the format of a set of Frequently Asked Questions and their accompanying answers,
contained within the present document. An Explanatory Note is produced to accompany the present document which
contains some observations based on the questions and answers.
The present document covers both Lawful Interception and Data Retention.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] GSMA IR.92 v7.0: "IMS Profile for Voice and SMS".
[i.2] GSMA RCC.61: "RCS Common Core 1.1 Service Description Document, Version 2.0".
[i.3] GSMA IR.64: "IMS Service Centralization and Continuity Guidelines".
[i.4] ETSI TS 133 107: "Universal Mobile Telecommunications System (UMTS); LTE; 3G security;
Lawful interception architecture and functions (3GPP TS 33.107)".
[i.5] ETSI TS 133 108: "Universal Mobile Telecommunications System (UMTS); LTE; 3G security;
Handover interface for Lawful Interception (LI) (3GPP TS 33.108)".
[i.6] ETSI TS 102 232-1: "Lawful Interception (LI); Handover Interface and Service-Specific Details
(SSD) for IP delivery; Part 1: Handover specification for IP delivery".
[i.7] ETSI TS 102 232-5: "Lawful Interception (LI); Handover Interface and Service-Specific Details
(SSD) for IP delivery; Part 5: Service-specific details for IP Multimedia Services".
[i.8] ETSI TS 102 232-7: "Lawful Interception (LI); Handover Interface and Service-Specific Details
(SSD) for IP delivery; Part 7: Service-specific details for Mobile Services".
[i.9] ETSI TS 102 657: "Lawful Interception (LI); Retained data handling; Handover interface for the
request and delivery of retained data".
[i.10] Recommendation ITU-T E.164: "The International Public Telecommunication Numbering Plan".
[i.11] IETF RFC 7977: "The Message Session Relay Protocol (MSRP)".
[i.12] IETF RFC 4825: "The Extensible Markup Language (XML) Configuration Access Protocol
(XCAP)".
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7 ETSI SR 003 292 V1.2.1 (2018-09)
[i.13] ATIS-1000678.v3.2015: "Lawfully Authorized Electronic Surveillance (LAES) for Voice over
Internet Protocol in Wireline Telecommunications Networks".
[i.14] ATIS-0700005.v002.2017: "Lawfully Authorized Electronic Surveillance (LAES) for 3GPP IMS-
based VoIP and other Multimedia Services".
[i.15] PKT-SP-ES-INF-I04-080425: "PacketCable™ 2.0 Electronic Surveillance Intra-Network
Specification".
[i.16] ETSI TS 123 228: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2
(3GPP TS 23.228)".
[i.17] ETSI TS 129 228: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; IP Multimedia (IM) Subsystem Cx and Dx
Interfaces; Signalling flows and message contents (3GPP TS 29.228)".
[i.18] ETSI TS 129 229: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Cx and Dx interfaces based on the Diameter
protocol; Protocol details (3GPP TS 29.229)".
[i.19] ETSI TS 129 230: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Diameter applications; 3GPP specific codes
and identifiers (3GPP TS 29.230)".
[i.20] ETSI TS 124 229: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; IP multimedia call control protocol based on
Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 (3GPP
TS 24.229)".
[i.21] ETSI TS 123 003: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); Numbering, addressing and identification (3GPP
TS 23.003)".
[i.22] IETF RFC 7254: "A Uniform Resource Name Namespace for the Global System for Mobile
Communications Association (GSMA) and the International Mobile Station Equipment Identity
(IMEI)".
[i.23] IETF RFC 7255: "A Uniform Resource Name Namespace for the Global System for Mobile
Communications Association (GSMA) and the International Mobile Station Equipment Identity
(IMEI)".
[i.24] 3GPP TR 33.827: "Study on Providing for LI in the S8 Home Routing Architecture for VoLTE
(Release 14)".
[i.25] ETSI TS 124 607: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Originating Identification Presentation (OIP)
and Originating Identification Restriction (OIR) using IP Multimedia (IM) Core Network (CN)
subsystem; Protocol specification (3GPP TS 24.607)".
[i.26] ETSI TS 124 608: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Terminating Identification Presentation (TIP)
and Terminating Identification Restriction (TIR) using IP Multimedia (IM) Core Network (CN)
subsystem; Protocol specification (3GPP TS 24.608)".
[i.27] ETSI TS 124 610: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Communication HOLD (HOLD) using IP
Multimedia (IM) Core Network (CN) subsystem; Protocol specification (3GPP TS 24.610)".
[i.28] ETSI TS 124 605: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Conference (CONF) using IP
Multimedia (IM) Core Network (CN) subsystem; Protocol specification (3GPP TS 24.605)".
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8 ETSI SR 003 292 V1.2.1 (2018-09)
[i.29] ETSI TS 124 604: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Communication Diversion (CDIV) using IP
Multimedia (IM) Core Network (CN) subsystem; Protocol specification (3GPP TS 24.604)".
[i.30] ETSI TS 124 611: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Anonymous Communication Rejection
(ACR) and Communication Barring (CB) using IP Multimedia (IM) Core Network (CN)
subsystem; Protocol specification (3GPP TS 24.611)".
[i.31] ETSI TS 124 615: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Communication Waiting (CW) using IP
Multimedia (IM) Core Network (CN) subsystem; Protocol Specification (3GPP TS 24.615)".
[i.32] ETSI TS 124 606: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Message Waiting Indication (MWI) using IP
Multimedia (IM) Core Network (CN) subsystem; Protocol specification (3GPP TS 24.606)".
[i.33] ETSI TS 124 647: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Advice Of Charge (AOC) using IP
Multimedia (IM) Core Network (CN) subsystem (3GPP TS 24.647)".
[i.34] ETSI TS 124 654: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Closed User Group (CUG) using IP
Multimedia (IM) Core Network (CN) subsystem, Protocol Specification (3GPP TS 24.654)".
[i.35] ETSI TS 124 239: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; Flexible Alerting (FA) using IP Multimedia
(IM) Core Network (CN) subsystem; Protocol specification (3GPP TS 24.239)".
[i.36] ETSI TS 124 182: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS) Customized
Alerting Tones (CAT); Protocol specification (3GPP TS 24.182)".
[i.37] ETSI TS 124 183: "Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia
Subsystem (IMS) Customized Ringing Signal (CRS); Protocol specification (3GPP TS 24.183)".
[i.38] ETSI TS 101 671: "Lawful Interception (LI); Handover interface for the lawful interception of
telecommunications traffic".
[i.39] IETF RFC 3550: "RTP: A Transport Protocol for Real-Time Applications".
[i.40] IETF RFC 4867: "TP Payload Format and File Storage Format for the Adaptive Multi-Rate
(AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs".
[i.41] IETF RFC 4733: "A Mechanism for Transporting User-to-User Call Control Information in SIP".
[i.42] IETF RFC 2833: "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals".
[i.43] GSMA IR.94: "IMS Profile for Conversational Video Service v10.0".
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ADSL Asymmetric Digital Subscriber Line
AMR Adaptive Multi-Rate Wideband
AMR-NB Adaptive Multi Rate - NarrowBand
AMR-WB Adaptive Multi Rate - WideBand
ANDSF Access Network Discovery and Selection Function
AS Application Server
A-SBC Access Session Border Controller
ASN.1 Abstract Syntax Notation One
ATCF Access Transfer Control Function
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9 ETSI SR 003 292 V1.2.1 (2018-09)
ATGW Access Transfer Gateway
ATIS Alliance for Telecommunications Industry Solutions
CBP Constrained Baseline Profile
CC Content of Communications
CGI Cell Global Identifier
CHP Constrained High Profile
CMTS Cable Modem Termination System
CS Circuit Switched
CS+IMS Circuit Switched and IMS
CSCF Call Session Control Function
CSP Communication Service Provider
CX IMS I/S-CSCF to HSS interface
DF Delivery Function
DR Data Retention
DSR Dynamic Source Routing
ECGI E-UTRAN Cell Global Identifier
ENUM E.164 Number to URI Mapping
EPC Evolved Packet Core
ePDG evolved Packet Data Gateway
EPS Evolved Packet System
eRCS enhanced RCS
eSRVCC enhanced SRVCC
E-UTRAN Evolved-UMTS-Terrestrial Radio Access Network
EVS Enhanced Voice Services
FFS For Further Study
GPRS General Packet Radio Services
GRUU Globally Routable User agent URI
GSMA Global System Mobile Association
GW GateWay
HEVC High Efficiency Video Coding
HI2 Handover Interface port 2 (for Intercept Related Information)
HI3 Handover Interface port 3 (for Content of Communication)
HPLMN Home Public Land Mobile Network
HSS Home Subscriber Server
IAP Intercept Access Point
ICS IMS Centralized Service
IMEI International Mobile Equipment Identity
IMS IP Multimedia Subsystem
IMSI International Mobile Subscriber Identity
IoT Internet of Things
IP Internet Protocol
IR GSMA Permanent Reference Document
IRI Intercept Related Information
LBO Local Break Out
LEA Law Enforcement Agency
LEMF Law Enforcement Monitoring Facility
LI Lawful Interception
LIID Lawful Interception Identifier
LTE Long Term Evolution
MCC Mobile Country Code
MF Mediation Function
MGCF Media Gateway Control Function
MGW Media GateWay
MMS Multimedia Messaging Service
MNC Mobile Network Code
MRF Media Resource Function
MSC Mobile Switching Centre
MSISDN Mobile Station International Subscriber Directory Number
MSRP Message Session Relay Protocol
MTAS Mobile Terminating Access Service
MVNO Mobile Virtual Network Operator
NAI Network Access Identifier
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10 ETSI SR 003 292 V1.2.1 (2018-09)
NB Narrow Band
PANI Private-Access-Network-Info
PCC Policy Control and Charging
P-CSCF Proxy-CSCF
PE Provider Edge
P-GRUU Public GRUU
PGW Packet data network GateWay
PLMN Public Land Mobile Network
PMN Public Mobile Network
PS Packet Switched
PSTN Public Switched Telephone Network
RCS Rich Communications Service
RS Reference Signal
RTP Real-Time Transport Protocol
S8HR S8 (interface point) Home Routing
SDP Session Description Protocol
SEW Support of Emergency services over WLAN
NOTE: More information available at http://www.3gpp.org/DynaReport/WiCr--690033.htm.
S-GW Serving GateWay
SIM Subscriber Identity Module
SIP Session Initiation Protocol
SM SIP MESSAGE
SMS Short Message Service
S-PGW Serving PGW
SR-VCC Single Radio-Voice Control Continuity
SS Supplementary Services
TEL Telephone
TIP Terminating Identification Presentation
TIR Terminating Identification Restriction
TLS Transport Layer Security
UE User Equipment
UMTS Universal Mobile Telecommunications System
URI Uniform Resource Identifier
URL Uniform Resource Locator
URN Uniform Resource Name
US United States
ViLTE Video over LTE
VoLTE Voice over LTE
VoWiFi Voice over Wireless Fidelity
VPLMN Visited Public Land Mobile Network
WebRTC Web Real Time Communications
WLAN Wireless Local Area Network
XCAP XML Configuration Access Protocol
XML eXtensible Markup Language
4 Questions and guidance statements
4.0 Introduction
This clause contains a series of subclauses regarding various themes relating to IMS, LTE and VoLTE; each of the
clauses contains a list of Frequently Asked Questions and Answers.
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