ETSI TS 101 470 V1.2.1 (2024-12)

Emergency Communications (EMTEL); Total Conversation Access to Emergency Services

RTS/EMTEL-00055

General Information

• Status: Not Published
• Technical Committee: EMTEL - Emergency Communications
• Current Stage: 12 - Completion
• Due Date: 03-Jan-2025
• Completion Date: 20-Dec-2024

Standards Content (Sample)

TECHNICAL SPECIFICATION
Emergency Communications (EMTEL);
Total Conversation Access to Emergency Services

2 ETSI TS 101 470 V1.2.1 (2024-12)

Reference
RTS/EMTEL-00055
Keywords
accessibility, call centre, disability,
emergency communications, emergency services,
IMS, IP, location, PSAP, real-time text, total
conversation
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ETSI
3 ETSI TS 101 470 V1.2.1 (2024-12)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 9
3 Definition of terms, symbols and abbreviations . 9
3.1 Terms . 9
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Background . 11
5 Total Conversation Functionality for Emergency Communications . 11
5.1 Basic functionality . 11
5.2 Total Conversation Environments . 12
5.2.0 General . 12
5.2.1 Session Initiation Protocol (SIP) access. 12
5.2.2 IP Multimedia Subsystem (IMS) access . 13
5.2.3 Other IP based protocols access . 14
5.2.4 Void . 14
5.3 Total Conversation Media . 14
5.3.1 Video . 14
5.3.1.0 General . 14
5.3.1.1 SIP support . 14
5.3.1.2 IMS support. 14
5.3.2 Real-Time Text . 15
5.3.2.0 General . 15
5.3.2.1 SIP support . 15
5.3.2.2 IMS support. 15
5.3.3 Audio . 15
5.3.3.0 General . 15
5.3.3.1 SIP support . 16
5.3.3.2 IMS support. 16
5.4 Supplementary and assisting services. 16
5.4.1 General . 16
5.4.2 Assisting service . 16
5.4.2.0 General . 16
5.4.2.1 Relay service . 16
5.4.2.2 SIP support . 17
5.4.2.3 IMS support . 17
5.4.3 Multi-party multi-media communication . 17
5.4.3.0 General . 17
5.4.3.1 SIP support . 17
5.4.4 Transfer and Forwarding supplementary services . 17
5.4.4.0 General . 17
5.4.4.1 SIP support . 17
5.5 Initiating the emergency communication . 18
5.5.0 General . 18
5.5.1 SIP support. 18
5.5.2 IMS support . 18
5.6 Communication scenarios . 18
5.6.0 General . 18
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4 ETSI TS 101 470 V1.2.1 (2024-12)
5.6.1 Communication without assisting service . 18
5.6.2 Assisting service need indicated by the user . 18
5.6.3 Assisting service invoked by the application service provider . 19
5.6.3.0 General . 19
5.6.3.1 SIP support . 19
5.6.3.2 IMS support. 19
5.6.4 Assisting service invoked by the PSAP call-taker . 19
5.7 Variation in services provided and media supported . 20
5.7.0 General . 20
5.7.1 SIP support. 21
5.7.2 IMS support . 21
5.8 Addressing emergency communications from the user terminal . 22
5.8.0 General . 22
5.8.1 SIP support. 22
5.8.2 IMS support . 22
5.9 Routing of emergency communications . 22
5.9.0 General . 22
5.9.1 SIP support. 22
5.9.2 IMS support . 23
5.10 Location information provision in emergency communications . 23
5.10.0 General . 23
5.10.1 SIP support. 23
5.10.2 IMS support . 23
5.11 PSAP call-back . 23
5.11.0 General . 23
5.11.1 SIP support. 23
5.11.2 IMS support . 24
5.12 Connecting the communication with an emergency control centre and other agencies . 24
5.13 Logging in the PSAP . 24
5.14 Recording in the PSAP . 24
5.15 Language considerations . 24
5.16 Co-operation between emergency handling organizations . 25
5.17 Security . 25
5.17.0 General . 25
5.17.1 SIP support. 25
5.17.2 IMS support . 25
5.18 Test communication . 25
Annex A (informative): Bibliography . 26
History . 27

ETSI
5 ETSI TS 101 470 V1.2.1 (2024-12)
Intellectual Property Rights
Essential patents
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Foreword
This Technical Specification (TS) has been produced by ETSI Special Committee Emergency Communications
(EMTEL).
Modal verbs terminology
In the present document "shall", "shall not", "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
Total Conversation, as defined in Recommendation ITU-T F.703 [2], is a combination of three media in a conversation:
video, Real-Time Text and audio and considered as a general multimedia conversational service. Internet-based Total
Conversation services and terminals are deployed in a number of countries in Europe, and adopted for example by some
persons with disabilities who need video for sign language communication or Real-Time Text for a text based
conversation instead of or as complement to a voice conversation. The present document specifies how Total
Conversation can be used for access to emergency services by emergency communications employing communication
modalities suitable both for the Total Conversation Terminal user and PSAP call-taker. It provides opportunities to
more rapid, reliable and confidence-creating resolution of the emergency cases compared to plain voice emergency
communications.
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6 ETSI TS 101 470 V1.2.1 (2024-12)
The use of Total Conversation is of special interest for enabling access to emergency communications and make the
communication more usable for those persons who may have little or no use of voice telephony because of disabilities
related to hearing, speech or other human communication functions.
The present document is based on ETSI TR 103 170 [i.5].
ETSI
7 ETSI TS 101 470 V1.2.1 (2024-12)
1 Scope
The present document defines conditions for using Total Conversation for emergency communications with more media
than in the regular voice call. It addresses the answering of Public Safety Answering Points (PSAP) and the potential
impact on features provided by PSAPs for handling Total Conversation. The present document also addresses
functional requirements regarding the interface to the PSAP, the connection to external supporting services, the
transferring and sharing of the communication between emergency communication organizations, the logging and
recording at the PSAP, the PSAP call-back aspects and specific communication routing and location information
provision aspects for Total Conversation. The present document refers to existing standards relevant for Total
Conversation user terminals and serving networks to facilitate a Total Conversation emergency communication. The
present document does not imply any requirements on user terminals in general to be Total Conversation terminals.
The service specified here is a solution for accessible emergency communications intended to address requirements in
the European Electronic Communications Code [i.1] and the European Accessibility Act [i.2].
TM
Due consideration is taken of related standardization (e.g. 3GPP and IETF) and work in other bodies (e.g. the
European Emergency Number Association (EENA)).
2 References
2.1 Normative 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 in the
ETSI docbox.
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 necessary for the application of the present document.
[1] Recommendation ITU-T F.700: "Framework Recommendation for multimedia services".
[2] Recommendation ITU-T F.703: "Multimedia conversational services".
[3] Recommendation ITU-T G.114: "One-way transmission time".
[4] Void.
[5] Void.
[6] Void.
[7] Void.
[8] ITU-T H-series Supplement 1: "Application profile - Sign language and lip-reading real-time
conversation using low bit rate video communication".
[9] Recommendation ITU-T T.140: "Protocol for multimedia application text conversation".
[10] ETSI TS 122 101: "Universal Mobile Telecommunications System (UMTS); Service aspects;
Service principles (3GPP TS 22.101)".
[11] ETSI TS 122 173: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal
Mobile Telecommunications System (UMTS); LTE; IP Multimedia Core Network Subsystem
(IMS) Multimedia Telephony Service and supplementary services; Stage 1 (3GPP TS 22.173)".
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8 ETSI TS 101 470 V1.2.1 (2024-12)
[12] ETSI TS 123 167:"Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia
Subsystem (IMS) emergency sessions (3GPP TS 23.167)".
[13] ETSI TS 126 114:"Universal Mobile Telecommunications System (UMTS); LTE; 5G; IP
Multimedia Subsystem (IMS); Multimedia telephony; Media handling and interaction (3GPP
TS 26.114)".
[14] Void.
[15] ETSI ES 202 975: "Human Factors (HF); Requirements for relay services.
[16] IETF RFC 3261: "SIP: Session Initiation Protocol".
[17] IETF RFC 3264: "An Offer/Answer Model with Session Description Protocol (SDP)".
[18] Void.
[19] Void.
[20] IETF RFC 4103: "RTP Payload for Text Conversation".
[21] IETF RFC 8866: "SDP: Session Description Protocol".
[22] IETF RFC 5239: "A Framework for Centralized Conferencing".
[23] IETF RFC 5627: "Obtaining and Using Globally Routable User Agent URIs (GRUUs) in the
Session Initiation Protocol (SIP)".
[24] IETF RFC 5764: "Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the
Secure Real-time Transport Protocol (SRTP)".
[25] Void.
[26] IETF RFC 6263: "Application Mechanism for Keeping Alive the NAT Mappings Associated with
RTP / RTP Control Protocol (RTCP) Flows".
[27] IETF RFC 6442: "Location Conveyance for the Session Initiation Protocol".
[28] Void.
NOTE: This is an informational IETF document collecting references to many standard track normative IETF
documents of importance for Next Generation Emergency Communications and therefore considered
relevant as normative reference.
[29] IETF RFC 6881: "Best Current Practice for Communications Services in Support of Emergency
Calling (BCP 181)".
NOTE: This is an IETF Best Current Practice document collecting references to many standard track normative
IETF documents of importance for Next Generation Emergency Communications.
[30] IETF RFC 9071: "RTP-Mixer Formatting of Multiparty Real-Time Text".
[31] ETSI TS 103 479: "Emergency Communications (EMTEL); Core elements for network
independent access to emergency services".
[32] IETF RFC 7852: "Additional Data related to an Emergency Call".
[33] IETF RFC 8373: "Negotiating Human Language in Real-time Communications".
[34] ETSI EN 301 549: "Accessibility requirements for ICT products and services".
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9 ETSI TS 101 470 V1.2.1 (2024-12)
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] Directive 2018/1972/EC of the European Parliament and the Council of 11 December 2018
establishing the European Electronic Communications Code (EECC).
[i.2] Directive (EU) 2019/882 of the European Parliament and of the Council of 17 April 2019 on the
accessibility requirements for products and services.
[i.3] ETSI EG 202 320: "Human Factors (HF); Duplex Universal Speech and Text (DUST)
communications".
[i.4] ETSI TR 102 180: "Emergency Communications (EMTEL); Basis of requirements for
communication of individuals with authorities/organizations in case of distress (emergency call
handling)".
[i.5] ETSI TR 103 170: "Emergency Communications (EMTEL); Total Conversation Access to
Emergency Services".
[i.6] IETF RFC 5012: "Requirements for Emergency Context Resolution with Internet Technologies".
[i.7] IETF RFC 5194: "Framework for Real-Time Text over IP Using the Session Initiation Protocol
(SIP)".
[i.8] ETSI TR 103 708: "Human Factors (HF); Real-Time Text (RTT) in Multiparty Conference
Calling".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
address: identifier of the destination of a communication containing only numbers, service URNs, or a wider range of
characters depending on the rules established by the application service provider
application service provider: organization or entity that, via a serving network, provides application-layer services,
which may include voice, video and text communication
assisting services: services invoked during a communication, assisting the user or the call-taker with specific tasks in
the communication
NOTE: Such tasks can for example be language translations, relay service or expert advice.
emergency service communications system: ESInet and PSAPs together, including technology for both emergency
communication handling and additional functions such as emergency communication distribution, emergency
communication recording, logging, and connection to emergency communications queue
Emergency Services IP network (ESInet): Internet Protocol (IP) based communications network dedicated for
emergency communications for public safety use
NOTE: An ESInet has an interface to the application service provider conveying emergency communications
from users. The ESInet is a managed IP network that is used for emergency services communications, and
can be shared by all public safety agencies in a region. It provides the IP transport infrastructure upon
which independent application platforms and core services can be deployed. ESInets may be
interconnected at local, regional, state, federal, national, and international levels to form an IP-based
internetwork. The term ESInet designates the network, not the services that ride on the network.
home environment: environment responsible for overall provision and control of the Personal Service Environment of
its subscribers
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10 ETSI TS 101 470 V1.2.1 (2024-12)
IP Multimedia Subsystem (IMS): standardized Next Generation Networking (NGN) architecture for telecom
operators that want to provide mobile and fixed multimedia services
modalities: methods for human expression and perception of communication
NOTE: Examples are written, signed and spoken languages, pictures, gestures, etc.
multi-party communication: real-time communication session with more than two participants where media sent from
participants are distributed for presentation among the participants in the communication
personal service environment: environment containing personalized information defining how subscribed services are
provided and presented towards the user
NOTE: Each subscriber of the Home Environment has her/his own Personal Service Environment. The Personal
Service Environment is defined in terms of one or more User Profiles.
Public Safety Answering Point (PSAP): physical location where emergency communications are received under the
responsibility of a public authority
Real-Time Text (RTT): form of text conversation in point to point situations or in multipoint conferencing where the
text being entered is displayed in such a way that the communication is perceived by the user as being continuous
NOTE: This feature is often called RTT.
relay service: telecommunications service that enables users of different modes of communication e.g. text, sign,
speech, to interact by providing conversion between the modes of communication, normally by a human operator
NOTE: A type of assisting service (definition from ETSI ES 202 975 [15]).
serving network: entity that provides the user with access to the services of the Home Environment
SIP: session control environment for communications, using the IETF RFC 3261 [16] and related protocols in the IP
networks
NOTE: The above refers to an environment outside the scope of IMS.
total conversation: bidirectional symmetric real-time transfer of motion video, Real-Time Text and voice between
users in two or more locations
total conversation service: multimedia real time conversation service that provides bidirectional symmetric real time
transfer of motion video, real time text and voice between users in two or more locations
total conversation terminal: user terminal capable of being used for Total Conversation
user: individual taking advantage of the Total Conversation service
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3GPP Third Generation Partnership Project
BOM Byte Order Mark
CRLF Carriage Return, Line Feed
CS Circuit Switched
EC European Commission
EENA European Emergency Number Association
EMTEL Emergency Communications
ESInet Emergency Services IP network
GRUU Globally Routable User Agent URI
GTT Global Text Telephony
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11 ETSI TS 101 470 V1.2.1 (2024-12)
IMS MES IMS Multimedia Emergency Session
IMS IP Multimedia Subsystem
IP Internet Protocol
LoST Location to Service Translation protocol
LTD Long Term Definition
MES Multimedia Emergency Session
PSAP Public Safety Answering Point
PSTN Public Switched Telephone Network
RCS Rich Communications Suite
RTP Real Time Protocol
RTT Real-Time Text
SIP Session Initiation Protocol
SOS Start Of String
SRTP Secure Real Time Protocol
ST String Terminator
TLS Transport Layer Security
UCS Universal Character Set
URI Uniform Resource Indicator
URN Uniform Resource Name
UTF UCS Transformation Format
4 Background
The Total Conversation service is defined in Recommendation ITU-T F.703 [2]. It is used for user-to-user
communication in a variation of media and modes of communication. The present document applies to Total
Conversation when used for emergency communications.
Background information can be found in ETSI TR 103 170 [i.5].
5 Total Conversation Functionality for Emergency
Communications
5.1 Basic functionality
The emergency communications system capable of handling Total Conversation emergency communications shall
provide its users with a way to make and receive emergency communications with Total Conversation and
communicate simultaneously in a conversational way using available combinations of video, Real-Time Text and audio.
The communication is made in a similar way as for a voice emergency communication.
Emergency numbers and associated URN information are used by the Total Conversation user when initiating
emergency communications.
When the emergency Total Conversation communication is answered, the common media supported by the terminal
and the PSAP for Total Conversation shall be used to initiate Total Conversation.
If an emergency communications system has both Total Conversation call-taker workstations and workstations
supporting fewer media than the Total Conversation workstations, then Total Conversation emergency communication
shall be handled by the Total Conversation workstations whenever possible.
If an emergency communication with Total Conversation media requested cannot be handled by a Total Conversation
workstation in the PSAP, then the PSAP shall be allowed to handle the communication in a workstation with support of
fewer medias. In the case that not all three media are used by the PSAP, or the user requires to use a modality not
supported by the PSAP, relay services may be invoked to handle the missing media or modalities if needed.
The present document assumes the conceptual service architecture shown in figure 1.
ETSI
12 ETSI TS 101 470 V1.2.1 (2024-12)

PSAP call-
Application PSAP taker work-
User
station
service network
terminal
provider
Emergency
Control Centre
and other
agency
Serving network                            Emergency service IP network

Assisting service
Assisting service
invoked by
invoked by
application
PSAP
service provider
Figure 1: Conceptual service architecture for Total Conversation access to emergency services
5.2 Total Conversation Environments
5.2.0 General
There are currently two main standardized IP network session control environments. They are: SIP and IP Multimedia
Subsystem IMS.
Selection of environment for terminal implementation is influenced by conditions out of the scope of the present
document. A terminal needs to support only the same environment for Total Conversation emergency communications
as it supports for Total Conversation non-emergency communications.
An overview of Total Conversation access to emergency communications for the two session control environments are
provided in clauses 5.2.1 and 5.2.2.
Support for Total Conversation access to emergency communications may be added for any other emerging session
control environment. The terms for such additions are described in clause 5.2.3.
5.2.1 Session Initiation Protocol (SIP) access
Total Conversation can be based on Internet communication using the session control protocol SIP as specified in IETF
RFC 3261 [16] but not necessarily in accordance with the IMS framework specified in 3GPP. In this case Total
Conversation can be viewed as an extension of a system for voice over IP (VoIP) based on SIP.
NOTE: A particular characteristic of this environment is that the Internet is an unmanaged network that is
untrusted, inherently insecure and does not guarantee any quality of service (i.e. is "best effort").
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13 ETSI TS 101 470 V1.2.1 (2024-12)
The specifics for Total Conversation in this environment are specified in IETF RFC 5194 [i.7], and also in ETSI
EG 202 320 [i.3]. These two specifications concentrate on describing the conditions for the Real-Time Text medium,
while they specify that video and audio may also be enabled in the communication to compose the Total Conversation
service.
The requirements for emergency communications in this environment are described in IETF RFC 5012 [i.6].
The specific mechanisms for emergency communications handling in this environment are specified in ETSI
TS 103 479 [31].
The main document specifying emergency communications by PSAPs implementing Total Conversation is ETSI
TS 103 479 [31], where communication protocols and other details in the interface are specified.
The protocols and procedures used in the interface between the serving network and the Emergency Service IP Network
shall be as specified in ETSI TS 103 479 [31], clause 6 except clauses 6.2 and 6.8.
5.2.2 IP Multimedia Subsystem (IMS) access
Total Conversation can be based on the IP Multimedia Subsystem (IMS) as specified by 3GPP and used in mobile
communication.
NOTE 1: A particular characteristic of this deployment scenario is that the IMS architecture is an operator managed
network that can be trusted, and provides security and quality of service.
Total Conversation in IMS shall be provided by the IMS Multimedia Telephony service described in ETSI
TS 122 173 [11], by including all three media of video, real time text and voice, described in ETSI TS 126 114 [13].
The IMS Multimedia Emergency Sessions (MES) as specified in ETSI TS 122 101 [10], clause 10.4.2 shall be used for
Total Conversation emergency communications.
NOTE 2: Some functionalities for IMS based access to emergency communications for Total Conversation related
to user preference based invocation of assisting services are not supported until Release 12 of the 3GPP
specifications.
These specifications are essentially based upon the same session control protocol and media considerations as those
used for the SIP case described in clause 5.2.1 of the present document but with IMS specific protocol extensions as
described in ETSI TS 122 173 [11] and in ETSI TS 126 114 [13], and IMS specific mechanisms for emergency
handling as described in ETSI TS 122 101 [10] and ETSI TS 123 167 [12].
The emergency communications initiated from Total Conversation users in the IMS system, are expected to be routed to
PSAPs using SIP according to the principles in clause 5.2.1 of the present document.
The functionality and procedures in the PSAP, Emergency Service IP Network and external services are not influenced
by this serving network. They are, in the present document, assumed to be based on SIP.
The opportunity to have emergency communications with the media included in Total Conversation was first specified
in 3GPP Release 11 of IMS in the multimedia emergency session concept. Thus the IMS access is valid only for IMS
networks implementing 3GPP IMS Release 11 or higher.
The functionality available in emergency communications is specified in ETSI TS 122 101 [10]. The functionality
entitled "Global Text Telephony (GTT)" in that description contains the IP based Real-Time Text component in Total
Conversation communications. GTT shall be combined with audio and video and be implemented together as the three
media in IMS Multimedia Telephony to provide the intended IMS based Total Conversation based emergency
communications.
Some of the functionalities needed for Total Conversation access in ETSI TS 122 101 [10] are made conditional on the
availability of regulation or national policy.
NOTE 3: The requirements expressed in article 109 in the European Electronic Communication Code [i.1] and its
recital 285 are indicating a requirement for availability of such functionalities for Europe. Also the
European Accessibility Act [i.2] Article 4.8 relates to accessible emergency communications by e.g. Total
Conversation.
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14 ETSI TS 101 470 V1.2.1 (2024-12)
The protocols procedures and codecs used in the interface between the serving network and the Emergency Service IP
Network shall be as specified ETSI TS 103 479 [31], clause 6 except clauses 6.1 and 6.8. The serving network shall
bridge any differences between what is used in IMS and this interface to the emergency service IP network capable of
handling Total Conversation emergency communication.
5.2.3 Other IP based protocols access
Total Conversation can be implemented with other protocols between user equipment and communications service than
those specified in clauses 5.2.1 and 5.2.2 of the present document. If it is decided that a service using such protocols
shall provide emergency communications with the capability to handle Total Conversation, then the default method
shall be to use the same interface as for the SIP based protocols described in the present document and ETSI
TS 103 479 [31], clause 6 except clauses 6.2 and 6.8. The application service provider using such protocols shall
establish the procedures and technology for the conversion.
Only if the protocol used between the Total Conversation user terminal and the application service provider is
introduced as a supported standard protocol for emergency service communication systems in the region where it is
provided, then that protocol may be used as the emergency communications access protocol. For emergency
communications with other regions, not supporting this protocol, conversion to the protocols specified in ETSI
TS 103 479 [31], clause 6 except clauses 6.2 and 6.8 shall take place by the application service provider.
The introduction of a new protocol for emergency communication may be done through a revised version of the present
document.
5.2.4 Void
5.3 Total Conversation Media
5.3.1 Video
5.3.1.0 General
A capability to use two way video communications in emergency communic
...