ETSI TR 103 140 V1.1.1 (2014-04)

Mobile Standards Group (MSG); eCall for VoIP

DTR/MSG-00eCall03

General Information

• Status: Published
• Publication Date: 10-Apr-2014
• Technical Committee: MSG - Mobile Standards Group
• Current Stage: 12 - Completion
• Due Date: 16-Apr-2014
• Completion Date: 11-Apr-2014

Standards Content (Sample)

Technical Report
Mobile Standards Group (MSG);
eCall for VoIP
2 ETSI TR 103 140 V1.1.1 (2014-04)

Reference
DTR/MSG-00eCall03
Keywords
ecall, IMS, LTE, UMTS
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ETSI
3 ETSI TR 103 140 V1.1.1 (2014-04)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 10
4 Introduction and General requirement . 11
4.1 Context . 11
4.2 General considerations for IMS eCall . 12
5 Non IMS solutions . 12
5.1 In-band modem over VoIP . 12
5.2 eCall over LTE with CS Fallback . 13
5.3 eCall over LTE using Over The Top services (OTT) . 13
5.4 ITS-Stations . 13
6 IMS solution for eCall . 14
6.1 Aspects of IMS eCall . 14
6.1.1 General . 14
6.1.2 eCall Architectural principles . 14
6.1.2.1 General . 14
6.1.2.2 eCall Flag . 14
6.1.2.3 Voice and any additional media sessions . 14
6.1.2.4 Transfer of MSD data. 15
6.1.2.5 Location information of the vehicle . 15
6.1.2.6 Caller identity . 15
6.1.2.7 Identifying network support for eCall over IMS . 15
6.1.2.8 Mobility management and session management for IMS eCall . 16
6.1.2.8.1 Mobility management . 16
6.1.2.8.2 Session management . 16
6.1.2.9 Call-back for eCall . 17
6.1.2.10 USIM configuration . 17
6.1.2.11 AT Command . 18
6.1.3 IMS eCall key implementation principles . 18
6.1.3.0 General . 18
6.1.3.1 Key Issue #1: indicating the eCall Flag. 18
6.1.3.1.1 Solution #1 . 18
6.1.3.1.2 Solution #2 . 19
6.1.3.1.3 Solution #3 . 19
6.1.3.2 Key Issue #2: Transfer of MSD data . 19
6.1.3.2.1 Solution #1 . 19
6.1.3.2.2 Solution #2 . 20
6.1.3.2.3 Solution #3 . 20
6.1.3.2.4 Solution #4 . 20
6.1.3.2.5 Solution #5 . 21
6.1.3.2.6 Solution #6 . 21
6.1.3.2.7 Solution #7 . 22
6.1.3.3 Key Issue #3: Security and Privacy of the MSD . 22
6.1.3.3.1 Solution #1 . 22
6.1.3.4 Key Issue #4: PSAP request for updated MSD . 22
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4 ETSI TR 103 140 V1.1.1 (2014-04)
6.1.3.4.1 Solution #1 . 22
6.1.3.4.2 Solution #2 . 23
6.1.3.4.3 Solution #3 . 23
6.1.3.5 Key Issue #5: Mobility Management - eCall inactive mode . 23
6.1.3.5.1 Solution #1 . 23
6.1.3.6 Key Issue #6: Session Management - Limiting the sessions . 24
6.1.3.6.1 Solution #1 . 24
6.1.3.6.2 Solution #2 . 24
6.1.3.7 Key Issue #7: Mobility Management and Session Management - attaching and requesting eCall
session . 24
6.1.3.7.1 Solution #1 . 24
6.1.3.7.2 Solution #2 . 25
6.1.3.7.3 Solution #3 . 25
6.1.3.7.4 Solution #4 . 26
6.1.3.7.5 Solution #5 . 26
6.1.3.8 Key Issue #8: Where to specify changes to SIP messages . 26
6.1.3.8.1 Solution #1 . 26
6.1.3.8.2 Solution #2 . 27
6.1.3.9 Key Issue #9: Identifying network support for IMS eCall . 27
6.1.3.9.1 Solution #1 . 27
6.1.3.10 Key Issue #10: PSAP acknowledgment to the IVS (receiving the MSD) . 27
6.1.3.10.1 Solution #1 . 27
6.1.3.10.2 Solution #2 . 28
6.1.3.11 Key Issue #11: defining identification for IMS eCall reconfiguration and test service . 28
6.1.3.11.1 Solution #1 . 28
6.1.4 Recommended solution . 29
6.1.5 Alternative Solution . 29
6.1.6 Open issues . 30
6.2 Work required in 3GPP . 30
6.2.1 SA1 . 30
6.2.2 SA2 . 30
6.2.3 CT1 . 30
6.2.4 CT6 . 30
6.2.5 RAN2 . 31
6.2.6 RAN5 . 31
6.3 Work required in IETF . 31
7 Co-existence of CS and IMS eCall . 31
7.1 Considerations . 32
7.1.1 IVS assumptions . 32
7.1.2 Mobile Network Operator considerations . 32
7.1.3 PSAP assumptions . 32
7.2 Migration scenarios . 33
7.2.1 General . 33
7.2.2 Description of scenarios . 33
7.2.2.1 Initial scenarios with FG-eCall . 35
7.2.2.2 Scenarios where even FG-eCall is not possible . 35
7.2.2.3 Scenarios where NG-eCall is possible . 35
7.2.2.4 Scenarios 11 with NG-IVS, IMS eCall coverage, but with FG-PSAP . 35
7.3 TPS eCall. 35
8 Conclusions and recommendations . 36
8.1 Conclusions . 36
8.2 Potential advantages of IMS eCall vs. CS eCall . 36
8.3 Recommendations for next steps . 36
Annex A: Change requests . 38
Annex B: eCall and ITS . 39
B.1 Evolution of 'Intelligent Transport Systems' . 39
B.2 "Communications Access for Land Mobiles" (CALM) . 43
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5 ETSI TR 103 140 V1.1.1 (2014-04)
Annex C: Characterization of the eCall in-band modem Performance over 3GPP VoIP. 44
C.1 Introduction . 44
C.2 eCall simulation framework/test setup . 44
C.3 The Dynamic Adaptive de-jitter buffer . 45
C.4 Simulation Test Runs & Results . 46
C.5 Static dejitter buffer . 48
Annex D: Potential future enhancements of eCall . 49
D.1 General . 49
D.2 More comprehensive data set(s) . 49
D.3 Wider range of support services . 50
D.4 Wider range of users. 51
D.4.1 Commercial vehicles . 51
D.4.2 Powered two wheel vehicles . 51
D.4.3 Unpowered vehicles (bicycles, etc.) . 52
D.4.4 Vulnerable road users (visually, physically, mentally challenged) . 52
D.4.5 Personal eCall . 52
D.4.6 Evolution to LTE/4G (E-UTRAN) . 53
D.4.7 Inclusion in a general on-board telematics platform . 53
D.4.8 eCall features enhancement . 53
D.4.8.1 Removal of muting requirements . 53
D.4.8.2 Removal of 140 byte limit and provision of bidirectionality unidirectionality . 53
D.4.8.3 Option to provide video link between PSAP and occupants of the vehicle . 54
D.4.8.4 Option to enable PSAP to access onboard cameras to gain a first hand visual assessment of the crash
site situation . 54
Annex E: Potential conformance test cases for IMS eCall . 55
E.1 Introduction . 55
E.2 Test environment . 55
E.3 Test cases . 55
E.3.1 Test Case 1A: Manually initiated IMS eCall using eCall-only UE, call-back required and performed . 55
E.3.2 Test Case 1B: Manually initiated IMS eCall using eCall-only UE, call-back not required . 56
E.3.3 Test Case 2A: Automatically initiated eCall, call-back required and performed . 57
E.3.4 Test Case 2B: Automatically initiated eCall, call-back not required . 57
E.3.5 Test Case 3: Test eCall using eCall-only UE to a test point PSAP . 58
E.3.6 Test Case 4: Reconfiguration call of eCall-only UE . 58
E.3.7 Test Case 5: eCall state before and after inactivity timer T34XX expiry . 59
E.3.8 Test Case 6: eCall state before and after inactivity timer T34XY expiry . 59
E.3.9 Other test cases . 60
Annex F: Bibliography . 61
History . 64

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6 ETSI TR 103 140 V1.1.1 (2014-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document 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 (http://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.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Mobile Standards Group (MSG).
Introduction
Current eCall is based on CS emergency call in GSM and UMTS networks.
LTE spectrum auctions are taking place in the EU and there will be extensive LTE coverage before the implementation
of eCall becomes mandatory in 2015. The longevity of GSM networks in the EU over the lifetime of vehicles is
uncertain and GSM spectrum is likely to be re-allocated for UMTS and/or LTE. There is no CS emergency call in LTE.
The applicability of the existing technical solution for eCall (in-band modem) should be assessed for VoIP/VoLTE, as
well as new technical solutions to be developed that are suitable for packet switched (UMTS and LTE) and offer better
performance for eCall for VoIP.
Longer term strategies need to be considered and guidance (probably for further work) provided in respect of the long
term migration of eCall to support over packet switched networks, and the co-existence and possible integration of
eCall and other ITS communication equipment installed in vehicles.
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7 ETSI TR 103 140 V1.1.1 (2014-04)
1 Scope
The present document contains the findings of STF456. The following areas are addressed:
• Assessment of in-band modem solution in case of no use of CS bearers.
• Study the adaptation of IMS emergency call and IMS Multimedia Emergency Service for supporting current
and future service required by eCall.
• Hybrid CS/IMS solution.
• Migration options and recommendations.
2 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
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
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] Next-Generation Pan-European eCall, draft-gellens-ecrit-ecall-01.
NOTE: Available at http://tools.ietf.org/html/draft-gellens-ecrit-ecall-01.
[i.2] ETSI TS 122 101: "Universal Mobile Telecommunications System (UMTS); Service aspects;
Service principles (3GPP TS 22.101 Release 8)", eCall requirements for data transmission.
[i.3] ETSI TS 124 008: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; Mobile radio interface Layer 3 specification; Core
network protocols; Stage 3 (3GPP TS 24.008)", eCall Discriminator Table 10.5.135d.
[i.4] ETSI TS 126 268: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); eCall data transfer; In-band modem solution; ANSI-C
reference code (3GPP TS 26.268)", eCall Data Transfer - ANSI-C Reference Code.
[i.5] ETSI TR 126 969: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); eCall data transfer; In-band modem solution;
Characterization report (3GPP TR 26.969)", eCall Data Transfer - Technical Report -
Characterisation Report.
[i.6] eCall minimum set of data CEN EN 15722 Road transport and traffic telematics - eSafety - eCall
minimum set of data.
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8 ETSI TR 103 140 V1.1.1 (2014-04)
[i.7] CEN EN 16062: "High Level Application Protocols".
[i.8] ETSI TS 124 229: "Digital cellular telecommunications system (Phase 2+); 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)",
clause 5.1.6 Emergency Service".
[i.9] ETSI TS 136 331: "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource
Control (RRC); Protocol specification (3GPP TS 36.331)", clause 6.2.2 Message definitions, SIB
for IMS Emergency Support.
[i.10] IETF RFC 3051: "A Uniform Resource Name (URN) for Emergency and Other Well-Known
Services".
[i.11] IETF RFC 4975: "Message Session Relay Protocol".
[i.12] Internet Protocol-based In-Vehicle Emergency Calls; draft-gellens-ecrit-car-crash-01.
[i.13] ETSI TS 123 167: "Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia
Subsystem (IMS) emergency sessions (3GPP TS 23.167)".
[i.14] ETSI TS 124 301: "Universal Mobile Telecommunications System (UMTS); LTE; Non-Access-
Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 (3GPP TS 24.301)".
[i.15] ETSI TS 131 102: "Universal Mobile Telecommunications System (UMTS); LTE; Characteristics
of the Universal Subscriber Identity Module (USIM) application (3GPP TS 31.102)".
[i.16] IETF RFC 6086: "Session Initiation Protocol (SIP) INFO Method and Package Framework".
[i.17] IETF RFC 2326: "Real Time Streaming Protocol (RTSP)".
[i.18] IETF RFC 6881: "Best Current Practice for Communications Services in Support of Emergency
Calling".
[i.19] IETF RFC 5547: "A Session Description Protocol (SDP) Offer/Answer Mechanism to Enable File
Transfer".
[i.20] IETF RFC 4103: "RTP Payload for Text Conversation".
[i.21] IETF RFC 3265: "Session Initiation Protocol (SIP)-Specific Event Notification".
[i.22] ETSI TS 122 173: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; IP Multimedia Core Network Subsystem (IMS)
Multimedia Telephony Service and supplementary services; Stage 1 (3GPP TS 22.173)".
[i.23] Additional Data related to an Emergency Call draft-ietf-ecrit-additional-data-20.
NOTE: Available at http://datatracker.ietf.org/doc/draft-ietf-ecrit-additional-data/.
[i.24] ETSI TS 127 007: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; AT command set for User Equipment (UE) (3GPP
TS 27.007)".
[i.25] ETSI TS 125 331: "Universal Mobile Telecommunications System (UMTS); Radio Resource
Control (RRC); Protocol specification (3GPP TS 25.331)".
[i.26] ETSI TS 123 272: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; Circuit Switched (CS) fallback in Evolved Packet
System (EPS); Stage 2 (3GPP TS 23.272)".
[i.27] ETSI TS 126 114: "Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia
Subsystem (IMS); Multimedia telephony; Media handling and interaction (3GPP TS 26.114)".
[i.28] ETSI TS 123 401: "Universal Mobile Telecommunications System (UMTS); General Packet
Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) access (3GPP TS 23.401)".
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9 ETSI TR 103 140 V1.1.1 (2014-04)
[i.29] ETSI TS 123 060: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); General Packet Radio Service (GPRS); Service
description; Stage 2 (3GPP TS 23.060)".
[i.30] ETSI TS 123 228: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2
(3GPP TS 23.228)".
[i.31] ETSI TS 102 936-1: "eCall Network Access Device (NAD) conformance specification;
Part 1: Protocol test specification".
[i.32] ISO 21217:2014: "Intelligent transport systems -- Communications access for land mobiles
(CALM) -- Architecture".
[i.33] ETSI TS 126 073: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; ANSI C code for the Adaptive Multi Rate (AMR)
speech codec (3GPP TS 26.073)".
[i.34] EN 16102: "Intelligent transport systems - eCall - Operating requirements for third party support".
[i.35] CEN TS 16405: "Intelligent transport systems - eCall - Additional data concept specification for
heavy goods vehicles".
[i.36] Draft-jesske-ecrit-ecall-urn-extension-00: "Uniform Resource Name (URN) extension for
automatic and manual Emergency Services".
NOTE: Available at http://tools.ietf.org/html/draft-jesske-ecrit-ecall-urn-extension-00.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
circuit switched emergency call: CS voice call type TS12 teleservice, that is applicable in CS (2G and 3G) networks
NOTE: This type is not applicable for PS based networks.
eCall: Pan European in-vehicle Emergency Call defined under the eSafety initiative of the European Commission
IMS eCall: eCall over IMS
NOTE: That there can be other packet based solutions.
IMS emergency call: IP based emergency call that is applicable for PS based 3G and 4G networks
In-band eCall: CS voice call where the MSD is sent in the same voice channel, using in-band modem
ITS-station: entity in a communication network capable of communicating with other similar entities
NOTE: This definition is based on ISO standards 21217.
The following definitions are copied from TS 124 008 [i.3]:
eCall-only: eCall-only mode, as described in TS 122 101
removal of eCall-only restriction: limitations as described in TS 122 101 for the eCall-only mode do not apply any
more
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10 ETSI TR 103 140 V1.1.1 (2014-04)
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACEM Motorcycle Industry European Association
ACN Automatic Crash Notification
ADR Agreement on Dangerous goods by Road
AMR Adaptive Multi Rate
ANSI American National Standards Institute
ANSI-C American National Standard Programming Language C
APN Access Point Name
ASN Abstract Syntax Notation
AT Attention (command)
BSMD Bounded Secured Managed Domain
CALM Communications Access for Land Mobiles
CAN Controller Area Network (vehicle bus)
CB Call Barring
CDU Command Definition Utility
CLI Calling Line Identification
CM Connection Management
CR Change Request
CS Circuit Switched
CSCF Call Session Control Function
CSFB Circuit Switched Fall Back
DJB De-Jitter Buffer
ECRIT Emergency Context Resolution with Internet Technologies
EPS Evolved Packet Switch
ESM EPS Session Management
ETSI TC MSG ETSI Technical Committee MSG
FFS For Further Study
FG First Generation
GPRS General Packet Radio Service
GPS Global Positional System
HLAP High Level Application Protocol
IANA Internet Assigned Numbers Authority
ICB Incoming Call Barring
IETF Internet Engineering Task Force
IMS IP Multimedia Subsystem
IP Internet Protocol
ISIM IP Multimedia Services Identity Module
ITS Intelligent Transport System(s)
ITS-S ITS Station
IVS In-Vehicle System
LTE Long Term Evolution
MGW Media Gateway
MNO Mobile Network Operator
MSD Minimum Set of Data
MSRP Message Session Relay Protocol
MT Mobile Terminated
NAS Non-Access Stratum
NG Next Generation
OCB Outgoing Call Barring
OMA Open Mobile Alliance
OTT Over The Top
PCM Pulse Code Modulation
PDN Packet Data Network
PE Pan European
PLMN Public Land Mobile Network
PS Packet Switching
PSAP Public Safety Answering Point
QoS Quality of Service
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11 ETSI TR 103 140 V1.1.1 (2014-04)
RFC Request for Comment
RTP Real Time Protocol
RTSP Real Time Streaming Protocol
SAP Service Access Point
SDP Session Description Protocol
SIB System Broadcast Information
SIP Session Initiation Protocol
SMS Short Message Service
SS System Simulator
STF Special Task Force
TCP Transmission Control Protocol
TPS eCall Third Party Supported eCall (CEN)
TPS Third Party Supported
UDP User Datagram Protocol
UE User Equipment
UMTS Universal Mobile Telecommunications System
URI Uniform Resource Identifier
URN Uniform Resource Name
USIM Universal Subscriber Identity Module
UTRAN Universal Terrestrial Radio Access Network
VoIP Voice over IP
VoLTE Voice over LTE
WAVE Wireless Access in the Vehicular Environment
XML Extended Markup Language
4 Introduction and General requirement
4.1 Context
Pan European eCall is an emergency call generated either automatically via activation of in-vehicle sensors or manually
by the vehicle occupants; when activated, it provides notification and relevant location information to the most
appropriate Public Safety Answering Points (PSAP), by means of mobile wireless communications networks and carries
a defined standardized minimum set of data, notifying that there has been an incident that requires response from the
emergency services and establishes an audio channel between the occupants of the vehicle and the most appropriate
PSAP.
This European Commission initiative of eCall was conceived in the late 1990s, and has evolved to a European
Parliament decision requiring the implementation of In-vehicle system in new vehicles and the deployment of eCall in
the European Member States in 2015.
Automotive manufacturers, and to a lesser extent aftermarket system providers have, in conjunction with PSAPs and
MNOs, been working towards the Standardization and introduction of eCall for a decade. Although legally
implementation will not be required until 2015, it takes several years of work in advance to build changes into
automotive type acceptance tests and to introduce in-vehicle system into new models. Further, several automotive
manufacturers already have private third party 'emergency call' support which they have had to amend to be consistent
with and compliant with eCall. There is therefore already significant commitment and investment already made into the
introduction of the system.
The Standardization aspects, both at the telecommunications level and at the application level were defined and
standardized in the period 2002 - 2012 and the communications aspects are based on CS emergency call in GSM and
UMTS networks.
The telecommunications sector, which always evolves rapidly, has made particular advances in the past decade. While
the period 2000 - 2012 saw the widespread deployment of UMTS networks, which continue to expand to cover most of
the continent, the next generation of cellular mobile communications, LTE/4G has been standardized and is beginning
to roll out across Europe. This has a particularly significant impact on eCall because, while GSM and UMTS are partly
'circuit switched' networks, LTE are 'packet switched' only networks, therefore there is no circuit switched emergency
call in LTE.
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12 ETSI TR 103 140 V1.1.1 (2014-04)
The existing standardized solution for eCall identification procedures and protocols are determined using the circuit
switching technologies considering the circuit switched 'Teleservice 12' for voice. Further, eCall, as currently defined,
establishes a voice channel and sends data within the voice channel, whereas the normal modus operandi for a packet
switched network is the obverse - transmitting packets of data.
The existing standards relevant to IMS eCall are the "IMS Emergency Service" and the "IMS Emergency Multimedia
Service". Only comparatively small additions are necessary to specify IMS eCall based on existing (and already
implemented and deployed) standards [i.8],[i.9]. The existing IMS Emergency Call standards provide a very good basis
for routing eCalls to the most appropriate PSAP if new URN classes can be defined in IETF [i.10], [i.1] for sos.eCall-
Automatic, sos.eCall-Manual and eCall-Test. The IETF ECRIT is currently working on drafts for eCall [i.1] and ACN
[i.12], the latter which contains information about activities outside Europe.
4.2 General considerations for IMS eCall
IMS is a platform for emergency voice calls in LTE. General requirements for eCall over IMS are based on
requirements for eCall over CS defined in TS 122 101 [i.2] and additional considerations for the support of IMS that are
mainly:
NOTE: Some of these additional considerations are dependent on future CEN requirement changes.
• The voice component is based on VoIP and not TS12.
• The data to be carried over IP need not have limitations of max size of 140 bytes.
• Even though not required for eCall, it would be possible to have other media besides voice within eCall,
between the IVS and the PSAP, as long as the required capabilities are supported by all involved parties (IVS,
PSAP, MNO).
• eCall voice component and the Minimum Set of Data (MSD) are transported transparently and are subject to
privacy considerations.
• The MSD and voice are sent to (or accessible by) the same PSAP-entity.
• An end-to-end receipt acknowledgement from the PSAP to the IVS is needed.
• In IMS eCall, there should be a network support indication for "IMS eCall" without first registering on a
PLMN.
• In the future, IVSs need to support eCall for both CS and IMS to guarantee its connectivity across different
networks and PSAP-implementations.
• There is no specific requirement to encrypt the MSD.
5 Non IMS solutions
5.1 In-band modem over VoIP
The eCall in-band modem is based on a pulse-position modulation scheme which requires proper time synchronization
between the IVS and PSAP. Functions or systems that distort the timeline of the eCall signal by inserting or removing
samples (e.g. sample slips, adaptive de-jitter buffering, and time-warping) can cause the sender and receiver to lose
synchronization.
The eCall in-band modem employs a synchronization-tracker feature designed to compensate for occasional and small
sample slips that occur in circuit-switched networks. This synchronization-tracker has also been shown to compensate
for the occasional loss or insertion of voice frames caused by adaptive de-jitter buffering. The simulation results in
Annex C illustrate how the performance of the in-band modem degrades when operating over a VoIP network with
jitter. The results also demonstrate that, despite the degradation, the performance is still generally acceptable in
condition
...