ETSI TS 101 470 V1.1.1 (2013-11)

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

DTS/EMTEL-00023

General Information

• Status: Published
• Publication Date: 20-Nov-2013
• Technical Committee: EMTEL - Emergency Communications
• Current Stage: 12 - Completion
• Due Date: 18-Dec-2013
• Completion Date: 21-Nov-2013

Standards Content (Sample)

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

2 ETSI TS 101 470 V1.1.1 (2013-11)

Reference
DTS/EMTEL-00023
Keywords
accessibility, call centre, disability, emergency
services, IMS, IP, location, PSAP, real-time text,
total conversation
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3 ETSI TS 101 470 V1.1.1 (2013-11)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 9
4 Background . 10
5 Total Conversation Functionality for Emergency Services . 10
5.1 Basic functionality . 10
5.2 Total Conversation Environments . 11
5.2.1 Access using basic Session Initiation Protocol (SIP) . 12
5.2.2 IP Multimedia Subsystem (IMS) access . 12
5.2.3 Access through other IP based protocols . 13
5.2.4 Access through legacy (circuit switched) networks . 13
5.3 Total Conversation Media . 13
5.3.1 Video . 13
5.3.1.1 Basic SIP support . 14
5.3.1.2 IMS support. 14
5.3.2 Real-Time Text . 14
5.3.2.1 Basic SIP support . 14
5.3.2.2 IMS support. 14
5.3.3 Audio . 14
5.3.3.1 Basic SIP support . 15
5.3.3.2 IMS support. 15
5.4 Supplementary and assisting services. 15
5.4.1 General . 15
5.4.2 Assisting service . 15
5.4.2.1 Relay service . 15
5.4.2.1.1 Basic SIP support . 16
5.4.2.1.2 IMS support . 16
5.4.3 Multi-party multi-media call . 16
5.4.3.1 Basic SIP support . 16
5.4.4 Transfer and Forward supplementary services . 16
5.4.4.1 Basic SIP support . 16
5.5 Initiating the emergency call . 16
5.5.1 Basic SIP support . 17
5.5.2 IMS support . 17
5.6 Call scenarios . 17
5.6.1 Call without assisting service. 17
5.6.2 Assisting service need indicated by the user . 17
5.6.3 Assisting service invoked by the application service provider . 17
5.6.3.1 Basic SIP support . 18
5.6.3.2 IMS support. 18
5.6.4 Assisting service invoked by the PSAP call-taker . 18
5.7 Variation in services provided and media supported . 19
5.7.1 Basic SIP support . 20
5.7.2 IMS support . 20
5.8 Addressing emergency services from the user terminal . 20
5.8.1 Basic SIP support . 20
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4 ETSI TS 101 470 V1.1.1 (2013-11)
5.8.2 IMS support . 20
5.9 Routing of emergency calls . 20
5.9.1 Basic SIP support . 21
5.9.2 IMS support . 21
5.10 Location information provision in emergency calls. . 21
5.10.1 Basic SIP support . 21
5.10.2 IMS support . 21
5.11 PSAP call back . 21
5.11.1 Basic SIP support . 21
5.11.2 IMS support . 22
5.12 Connecting the call with an emergency control centre and other agencies . 22
5.13 Logging in the PSAP . 22
5.14 Recording in the PSAP . 22
5.15 Language considerations . 22
5.16 Co-operation between emergency handling organizations . 23
5.17 Security . 23
5.17.1 Basic SIP support . 23
5.17.2 IMS support . 23
5.18 Testing . 23
Annex A (informative): Bibliography . 24
History . 25

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5 ETSI TS 101 470 V1.1.1 (2013-11)
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 Specification (TS) has been produced by ETSI Special Committee Emergency Communications
(EMTEL).
Introduction
Total Conversation is 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 employing communication modalities suitable both for the Total Conversation Terminal user and
PSAP call-taker.
The present document is based on TR 103 170 [i.6].
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6 ETSI TS 101 470 V1.1.1 (2013-11)
1 Scope
Total Conversation, as defined in Recommendation ITU-T F.703 [2], is a combination of three media in a
conversational call: video, Real-Time Text and audio. The present document defines conditions for using Total
Conversation for emergency services with more media than in the regular voice call providing opportunities to more
rapid, reliable and confidence-creating resolution of the emergency service cases compared to plain voice emergency
calls, and especially for enabling access of emergency services or making them 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 addresses the organization of Public Safety Answering Points (PSAP) and the potential impact
on overall organizations of emergency services for handling Total Conversation calls. 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 call between call handling organizations, the call logging and call recording at the
PSAP, the PSAP call back aspects and specific call routing and location information provision aspects for these Total
Conversation calls. The present document refers to existing standards relevant for Total Conversation user terminals
and serving networks to facilitate a Total Conversation emergency call. The present document does not imply any
requirements on user terminals in general to be Total Conversation terminals.
The service specified here is one solution for accessible emergency services intended to fulfil requirements in the EU
Universal Service Directive [i.1] and [i.2]. The present document does not preclude that other solutions may be possible
and can be specified and implemented.
TM
Due consideration is taken of related standardization (e.g. 3GPP and IETF) and work in other bodies (e.g. the Expert
Group on Emergency Access (EGEA) and the European Emergency Number Association (EENA)).
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.
[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] Recommendation ITU-T G.711: "Pulse code modulation (PCM) of voice frequencies".
[5] Recommendation ITU-T G.722: "7 kHz audio-coding within 64 kbit/s".
[6] Recommendation ITU-T H.263: "Video coding for low bit rate communication".
[7] Recommendation ITU-T H.264: "Advanced video coding for generic audiovisual services".
[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".
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7 ETSI TS 101 470 V1.1.1 (2013-11)
[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+); Universal Mobile
Telecommunications System (UMTS); LTE; IP Multimedia Core Network Subsystem (IMS)
Multimedia Telephony Service and supplementary services; Stage 1 (3GPP TS 22.173)".
[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; IP Multimedia
Subsystem (IMS); Multimedia telephony; Media handling and interaction (3GPP TS 26.114)".
[14] ETSI TS 124 279: "Universal Mobile Telecommunications System (UMTS); LTE; Combining
Circuit Switched (CS) and IP Multimedia Subsystem (IMS) services; Stage 3 (3GPP TS 24.279)".
[15] ETSI ES 202 975: "Human Factors (HF); Harmonized relay services".
[16] IETF RFC 3261: "SIP: Session Initiation Protocol".
[17] IETF RFC 3264: "An Offer/Answer Model with Session Description Protocol (SDP)".
[18] IETF RFC 3551: "RTP Profile for Audio and Video Conferences with Minimal Control".
[19] IETF RFC 3711: "The Secure Real-time Transport Protocol (SRTP)".
[20] IETF RFC 6184: "RTP Payload Format for H.264 Video".
[21] IETF RFC 4103: "RTP Payload for Text Conversation".
[22] IETF RFC 4566: "SDP: Session Description Protocol".
[23] IETF RFC 4629: "RTP Payload Format for ITU-T Rec. H.263 Video".
[24] IETF RFC 5239: "A Framework for Centralized Conferencing".
[25] IETF RFC 5627: "Obtaining and Using Globally Routable User Agent URIs (GRUUs) in the
Session Initiation Protocol (SIP)".
[26] IETF RFC 5764: "Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the
Secure Real-time Transport Protocol (SRTP)".
[27] IETF RFC 6189: "ZRTP. Media Path Key Agreement for Unicast Secure RTP".
[28] IETF RFC 6263: "Application Mechanism for Keeping Alive the NAT Mappings Associated with
RTP / RTP Control Protocol (RTCP) Flows".
[29] IETF RFC 6442: "Location Conveyance for the Session Initiation Protocol".
[30] IETF RFC 6443: "Framework for Emergency Calling Using Internet Multimedia".
NOTE: This is an informational IETF document collecting references to many standard track normative IETF
documents of importance for Next Generation Emergency Services and therefore considered relevant as
normative reference.
[31] 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 Services.
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8 ETSI TS 101 470 V1.1.1 (2013-11)
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 2002/22/EC of the European Parliament and the Council of 7 March 2002 on universal
service and users' rights relating to electronic communications networks and services (Universal
Service Directive).
[i.2] Directive 2009/136/EC of the European Parliament and the Council of 25 November 2009
amending Directive 2002/22/EC on universal service and users’ rights relating to electronic
communications networks and services, Directive 2002/58/EC concerning the processing of
personal data and the protection of privacy in the electronic communications sector and Regulation
(EC) No 2006/2004 on cooperation between national authorities responsible for the enforcement
of consumer protection laws.
[i.3] "EENA NG1-1-2 Long Term Definition", EENA 2012.
NOTE http://www.eena.org/ressource/static/files/2013-03-15-eena_ltd_v1-1_final.pdf.
[i.4] ETSI EG 202 320: "Human Factors (HF); Duplex Universal Speech and Text (DUST)
communications".
[i.5] 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.6] ETSI TR 103 170: "Emergency Communications (EMTEL); Total Conversation Access to
Emergency Services".
[i.7] IETF RFC 5012: "Requirements for Emergency Context Resolution with Internet Technologies".
[i.8] IETF RFC 5194: "Framework for Real-Time Text over IP Using the Session Initiation Protocol
(SIP)".
[i.9] draft-ietf-ecrit-additional-data: "Additional Data related to an Emergency Call".
NOTE: http://tools.ietf.org/html/draft-ietf-ecrit-additional-data (work in progress).
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
address: identifier of the destination of a call containing only numbers, 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 call, assisting the user or the call-taker with specific tasks in the call
NOTE: Such tasks can for example be language translations, relay service or expert advice.
basic SIP: session control environment for calls, using the RFC 3261 [16] and related protocols in the IP networks
NOTE: The above refers to an environment outside the scope of IMS.
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9 ETSI TS 101 470 V1.1.1 (2013-11)
Emergency Services IP network (ESInet): Internet Protocol (IP) based communications network dedicated for public
safety use
NOTE: An ESInet delivers emergency requests and corresponding data to emergency services providers and
facilitates communication between emergency service providers and other supporting entities. An ESInet
is typically deployed to support a set of PSAPs and other public safety agencies on a geographic basis. A
given PSAP, or other appropriate entity, may connect to one or more ESInets. ESInets may be
interconnected to facilitate emergency event handling and other related interactions (from EENA NG112
LTD [i.3]).
emergency service system: ESiNet and PSAPs together, including technology for both emergency call handling and
additional functions such as emergency call distribution, emergency call recording, logging, and connection to
emergency service queue
home environment: environment responsible for overall provision and control of the Personal Service Environment of
its subscribers
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 call: real-time communication session with more than two participants where media sent from participants
are distributed for presentation among the participants in the call
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 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 calls 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 ES 202 975 [15]).
serving network: entity that provides the user with access to the services of the Home Environment
total conversation: audiovisual conversation service providing bidirectional symmetric real-time transfer of motion
video, Real-Time Text and voice between users in two or more locations
NOTE: Definition from Recommendation ITU-T F.703 [2].
total conversation terminal: user terminal capable of being used for Total Conversation
user: individual taking advantage of the Total Conversation service
3.2 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
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10 ETSI TS 101 470 V1.1.1 (2013-11)
EC European Commission
EENA European Emergency Number Association
EGEA Expert Group on Emergency Access
EMTEL Emergency Communications
ESInet Emergency Services IP network
GRUU Globally Routable User Agent URI
GTT Global Text Telephony
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
ZRTP Media Path Key Agreement for Secure RTP
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 service access.
Background information can be found in TR 103 170 [i.6].
5 Total Conversation Functionality for Emergency
Services
5.1 Basic functionality
The emergency service capable of handling Total Conversation emergency calls shall provide its users with a way to
make and receive emergency calls with Total Conversation and communicate simultaneously in a conversational way
using available combinations of video, Real-Time Text and audio. The call is made in a similar way as for a voice
emergency call.
An emergency number or address is used by the Total Conversation user when calling emergency services and a calling
action shall be initiated.
When the emergency Total Conversation call is answered, the common media supported by the terminal and the PSAP
for Total Conversation shall be used to initiate a Total Conversation Call.
If an emergency service system has both Total Conversation call-taker workstations and workstations supporting fewer
media than the Total Conversation workstations, then Total Conversation emergency calls shall be handled by the Total
Conversation workstations whenever possible.
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11 ETSI TS 101 470 V1.1.1 (2013-11)
If an emergency call 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 call in a workstation with support of fewer media. In the case
that not all 3 media is 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.

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
There are currently two main standardized IP network session control environments. They are: basic 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 calls as it
supports for Total Conversation non-emergency calls.
An overview of Total Conversation access to emergency services for the two session control environments are provided
in clauses 5.2.1 and 5.2.2.
Support for Total Conversation access to emergency services may be added for any other emerging session control
environment for Total Conversation. The terms for such additions are described in clause 5.2.3.
A brief description of legacy PSTN access with relation to a subset of Total Conversation is included in clause 5.2.4.
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12 ETSI TS 101 470 V1.1.1 (2013-11)
5.2.1 Access using basic Session Initiation Protocol (SIP)
Total Conversation can be based on Internet communication using the session control protocol SIP as specified in
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. This is called "basic
SIP" in the present document.
NOTE 1: 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").
The specifics for Total Conversation in this environment are specified in RFC 5194 [i.8], and also in EG 202 320 [i.4].
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 call to compose the Total Conversation service.
The requirements for emergency services in this environment are described in RFC 5012 [i.7].
The specific mechanisms for emergency call handling in this environment are specified in RFC 6443 [30] and
RFC 6881 [31].
PSAPs implementing Total Conversation access shall be able to handle emergency calls using the interface protocols
specified in RFC 6881 [31].
The protocols and procedures used in the interface between the serving network and the Emergency Service Network
shall be as specified in RFC 6881 [31].
NOTE 2: More information on suitable procedures and protocols for this environment is found in EENA
NG112 LTD [i.3].
5.2.2 IP Multimedia Subsystem (IMS) access
Total Conversation can be based on the IP Multimedia Subsystem IMS as specified by 3GPP.
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 TS 122 173 [11],
by including all three media described in TS 126 114 [13].
The IMS MES as specified in TS 122 101 [10] shall be used for Total Conversation emergency calls.
NOTE 2: Some functionalities for IMS based access to Emergency Services 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 call control protocol and media considerations as those used
for the basic SIP case described in clause 5.2.1 but with some IMS specific protocol extensions and some IMS specific
mechanisms for emergency handling.
The emergency calls initiated from Total Conversation users in the IMS system, are expected to be routed to emergency
services using basic SIP according to the principles in clause 5.2.1.
The functionality and procedures in the PSAP, Emergency Service Network and external services are not influenced by
this serving network. They are, in the present document, assumed to be based on basic SIP.
The opportunity to make emergency calls 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 Release 11 or higher.
The functionality available in emergency services is specified in 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
calls. 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 access to emergency services.
Some of the functionality needed for Total Conversation access in TS 122 101 [10] is made conditional on the
availability of regulation or national policy. The requirements expressed in article 26.4 in the European Universal
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13 ETSI TS 101 470 V1.1.1 (2013-11)
Service Directive [i.1] and in recitals 12 and 13 of the amending directive [i.2] should be regarded as indicating a
requirement for availability of such functionality for Europe.
The protocols procedures and codecs used in the interface between the serving network and the Emergency Service
Network should be as specified in RFC 6881 [31]. The serving network shall bridge any differences between what is
used in IMS and this interface to the emergency service capable of handling Total Conversation emergency calls.
The way that the emergency calls are processed within the IMS network shall follow TS 123 167 [12].
The use of IMS for the case of voice call in CS mode combined in a data/video session using Rich Communications
Suite (RCS), is specified in TS 124 279 [14].
5.2.3 Access through other IP based protocols
Total Conversation can be implemented with other protocols than those specified in clauses 5.2.1 and 5.2.2. If an
authority decided that a service using such protocol shall provide access to emergency service with capability to handle
Total Conversation, then the default method shall be to use the same interface as for the basic SIP based protocols
described in the present document. 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 among ESiNets and PSAPs in the region where it is provided, then that
protocol may be used as the emergency access protocol. The introduction of the new protocol for emergency access
may be done through a revised version of the present document.
5.2.4 Access through legacy (circuit switched) networks
A legacy form of Real-Time Text exists in some countries, called text telephony, enabling limited communication with
Real-Time Text in the PSTN, sometimes alternating with voice.
In countries where legacy text telephones prevail, the authorities may arrange for emergency service access for text
telephony into the IP based emergency service access interfaces for Total Conversation by means of gateways between
PSTN and IP networks with suitable capabilities.
The gateways shall cater for adaptation to possible limitations in media simultaneity of the PSTN Text Telephones.
Legacy call handling as specified in EG 202 320 [i.4] and RFC 5194 [i.8] should be applied.
5.3 Total Conversation Media
5.3.1 Video
A capability to use two way video communications in emergency calls shall be provided by PSAP call-taker
workstations and emergency service systems supporting Total Conversation emergency calls. Calls without video shall
also be supported.
A view of the other communicating person(s) is provided to each participant in the call.
NOTE: In sign language communication all users need to see the head and hands of all participants in the call.
The PSAP call-taker workstations used for Total Conversation shall be capable of transmitting a view of the call-taker
including the face and the hands. This view is suitable both in general and for cases when the call-taker is using sign
language.
Video communication for conversational use with Total Conversation should be provided with characteristics and
quality suitable for use of sign language and lip reading when used for emergency calls. This is specified in ITU-T
Series H, Supplement 1 [8].
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14 ETSI TS 101 470 V1.1.1 (2013-11)
5.3.1.1 Basic SIP support
Both the following codecs shall be supported by PSAPs and ESInet in the interface between serving networks and the
ESInet. At least one of them shall be supported and used in this interface by the combination of serving networks and
Total Conversation user terminals when used for emergency calls.
Recommendation ITU-T H.264 [7] coding, using the transport specification in RFC 6184 [20].
Recommendation ITU-T H.263 [6] coding, using the transport specification in RFC 4629 [23].
5.3.1.2 IMS support
Video included in Total Conversation emergency sessions in IMS shall follow the specification in the video-related
clauses of TS 126 114 [13] regarding the Total Conversation user terminal and the serving network.
5.3.2 Real-Time Text
A capability to use Real-Time Text in emergency calls shall be provided by PSAP call-taker workstations and
emergency service systems supporting Total Conversation. Calls without Real-Time Text shall also be supported.
A capability to use Real-Time Text in the emergency call interoperable with the emergency service system shall be
provided by the serving network in interaction with the Total Conversation user terminals.
Real-Time Text communication should be provided in the Total Conversation emergency call according to the quality
criteria for good text conversation communication. Such criteria are described in Recommendations ITU-T F.700 [1]
and F.703 [2].
5.3.2.1 Basic SIP support
Recommendation ITU-T T.140 [9] and RFC 4103 [21] for coding, presentation and transport of Real-Time Text shall
be supported by Total Conversation PSAPs and ESInet as specified in RFC 6881 [31]. These specifications for Real-
Time Text shall also be supported by the serving network in the interface between serving networks and the ESInet for
Total Conversation emergency calls with Total Conversation user terminals.
NOTE: Two errata are available in IETF for RFC 4103 [21].
The need for keep-alive communication should be considered as described in RFC 6263 [28]. Regular transmission of
the UTF-8 BOM character is an alternative keep-alive method. BOM characters shall not be interpreted as user-
generated text.
On reception, any character codes that cannot be presented shall be ignored. This may be because of graphical rendering
limitations or for special signalling character codes such as SOS-ST strings specified in Recommendation
ITU-T T.140 [9].
When deleting, each backspace character shall delete exactly one Unicode character, regardless of the byte-length of
that character in UTF-8. The only exception to this is that CRLF combinations sent by non-compliant systems, instead
of the proper Unicode line-separator character, shall be treated as a single character when deleting.
5.3.2.2 IMS support
Real-Time Text included in Total Conversation emergency sessions in IMS shall support the specification in the text-
related clauses of TS 126 114 [13] regarding the Total Conversation user terminal and the serving network.
5.3.3 Audio
A capability to use two ways audio in Total Conversation emergency calls shall be provided by PSAP call-taker
workstations and emergency service systems. Calls without audio shall also be supported
A capability to use two ways audio in the Total Conversation emergency call interoperable with the emergency service
system shall be provided by the serving network in interaction with the Total Conversation user terminals.
ETSI
15 ETSI TS 101 470 V1.1.1 (2013-11)
The emergency service system handling Total Conversation calls shall support both wide band and narrow band audio
codecs. This is valid for all components of the emergency service system, including the EsiNet, the PSAP workstation,
call distribution and call recording equipment.
The Total Conversation user terminals shall support at least one of wide band or narrow band codec.
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