ETSI TS 103 698 V1.1.1 (2020-12)

ETSI TS 103 698 V1.1.1 (2020-12)
TECHNICAL SPECIFICATION
Emergency Communications (EMTEL);
Lightweight Messaging Protocol for
Emergency Service Accessibility (LMPE)
---------------------- Page: 1 ----------------------
2 ETSI TS 103 698 V1.1.1 (2020-12)
Reference
DTS/EMTEL-00050
Keywords
chat, decentralized identifier, emergency
services, location, SSL/TLS certificates
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search

The present document may be made available in electronic versions and/or in print. The content of any electronic and/or

print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any

existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI

deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.

Users of the present document should be aware that the document may be subject to revision or change of status.

Information on the current status of this and other ETSI documents is available at

If you find errors in the present document, please send your comment to one of the following services:

No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying

The content of the PDF version shall not be modified without the written authorization of ETSI.

DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and

oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and

Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 5

Executive summary ............................................................................................................................................ 5

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 References ................................................................................................................................................ 7

2.1 Normative references ......................................................................................................................................... 7

2.2 Informative references ........................................................................................................................................ 8

3 Definition of terms, symbols and abbreviations ....................................................................................... 8

3.1 Terms .................................................................................................................................................................. 8

3.2 Symbols .............................................................................................................................................................. 8

3.3 Abbreviations ..................................................................................................................................................... 9

4 General ................................................................................................................................................... 10

4.1 Overview .......................................................................................................................................................... 10

4.2 Architecture ...................................................................................................................................................... 10

4.3 Mandatory Interfaces ........................................................................................................................................ 11

4.4 Optional Interfaces ........................................................................................................................................... 12

5 Entities .................................................................................................................................................... 12

5.1 Border Control Function (BCF) ....................................................................................................................... 12

5.1.1 Overview .................................................................................................................................................... 12

5.1.2 Mandatory Interfaces .................................................................................................................................. 12

5.1.3 Optional Interfaces ...................................................................................................................................... 13

5.2 Emergency Service Routing Proxy (ESRP) ..................................................................................................... 13

5.2.1 Overview .................................................................................................................................................... 13

5.2.2 Mandatory Interfaces .................................................................................................................................. 13

5.2.3 Optional Interfaces ...................................................................................................................................... 14

5.3 Emergency Call Routing Function (ECRF) ...................................................................................................... 14

5.3.1 Overview .................................................................................................................................................... 14

5.3.2 Mandatory Interfaces .................................................................................................................................. 14

5.3.3 Optional Interfaces ...................................................................................................................................... 14

5.4 Public Safety Answering Point (PSAP)............................................................................................................ 14

5.4.1 Overview .................................................................................................................................................... 14

5.4.2 Mandatory Interfaces .................................................................................................................................. 14

5.4.3 Optional Interfaces ...................................................................................................................................... 15

5.5 Location Information Server (LIS) ................................................................................................................... 15

5.5.1 Overview .................................................................................................................................................... 15

5.5.2 Mandatory Interfaces .................................................................................................................................. 15

5.5.3 Optional Interfaces ...................................................................................................................................... 15

5.5.4 Location Representation ............................................................................................................................. 16

5.6 Chat Application (APP) .................................................................................................................................... 16

5.6.1 Overview .................................................................................................................................................... 16

5.6.2 Mandatory Interfaces .................................................................................................................................. 16

5.6.3 Optional Interfaces ...................................................................................................................................... 16

5.6.4 Location Representation ............................................................................................................................. 16

6 Interfaces ................................................................................................................................................ 17

6.1 Signalling ......................................................................................................................................................... 17

6.1.1 SIP Transport (SIP-1) ................................................................................................................................. 17

6.1.2 SIP Session (SIP-2) ..................................................................................................................................... 17

6.1.2.1 Overview ............................................................................................................................................... 17

6.1.2.2 SIP Methods .......................................................................................................................................... 17

6.1.2.3 Required SIP Headers ........................................................................................................................... 17

6.1.2.4 Accepted SIP Headers ........................................................................................................................... 18

6.1.2.5 Resource Priority ................................................................................................................................... 19

6.1.2.6 History-Info and Reason ....................................................................................................................... 19

6.1.2.7 Call-Info ................................................................................................................................................ 19

6.1.2.8 SIP Message Bodies .............................................................................................................................. 20

6.1.2.9 SIP Element Overload ........................................................................................................................... 20

6.1.2.10 Test Call ................................................................................................................................................ 21

6.1.2.11 Decentralised Identifier (DID) .............................................................................................................. 21

6.2 Instant Messaging (IM-2) ................................................................................................................................. 22

6.2.1 Overview .................................................................................................................................................... 22

6.2.2 Session Mode Initiation .............................................................................................................................. 22

6.2.3 Session Mode Chat ..................................................................................................................................... 23

6.2.4 Session Mode Termination ......................................................................................................................... 24

6.2.5 Keep-Alive Messages ................................................................................................................................. 24

6.2.6 Transfer ....................................................................................................................................................... 25

6.2.7 Redirect ....................................................................................................................................................... 26

6.3 Chat Transfer (HTTP-3) ................................................................................................................................... 28

6.3.1 Overview .................................................................................................................................................... 28

6.3.2 Transfer Negotiation ................................................................................................................................... 28

6.3.3 Transfer Execution ...................................................................................................................................... 29

6.3.4 Message Sequence Chart ............................................................................................................................ 29

Annex A (normative): JSON Schema ................................................................................................. 33

A.1 ChatTransferNegotiationRequest ........................................................................................................... 33

A.2 ChatTransferNegotiationResponse ......................................................................................................... 33

A.3 ChatTransferExecutionRequest .............................................................................................................. 34

A.4 ChatTransferExecutionResponse ........................................................................................................... 34

A.5 Message Type Definition ....................................................................................................................... 35

Annex B (informative): Organizational Descriptions ......................................................................... 36

B.0 General ................................................................................................................................................... 36

B.1 Certificate Authority............................................................................................................................... 36

B.2 National, and Regional Authorities ........................................................................................................ 36

B.3 Public Safety Computer Emergency Response Team (CERT) .............................................................. 36

B.4 ETSI Protocol Naming and Numbering Service (PNNS) ...................................................................... 36

B.5 Emergency Call Service Authorities ...................................................................................................... 36

Annex C (informative): Parameter Registries ..................................................................................... 38

C.0 General ................................................................................................................................................... 38

Annex D (informative): Use Case Examples ........................................................................................ 39

D.0 General ................................................................................................................................................... 39

D.1 National/Regional ................................................................................................................................... 39

D.2 International/Roaming ............................................................................................................................ 40

D.3 Smart IoT Devices And Chatbots ........................................................................................................... 41

History .............................................................................................................................................................. 42

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

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

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.

This Technical Specification (TS) has been produced by ETSI Special Committee Emergency Communications

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

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

Lightweight Messaging Protocol for Emergency Service accessibility (LMPE) extends a SIP SIMPLE based messaging

service with session mode and facilities to redirect or transfer a chat. The mechanisms introduced in the present

document differ from existing solutions like MSRP in a sense that no media plane is required. This reduces the

functionality to chat, but requires less deployment effort and complexity (e.g. no intermediate services or relays in case

of NAT), especially in a roaming use case. In addition, to further reduce complexity, the identification of a user is

carried out via a device identifier only, such as a mobile phone number as with comparable chat services. In summary, it

simplifies the implementation and thus can be used in simple mobile applications or even smart IoT devices and

The referred baseline specification (ETSI TS 103 479 [1]) already defines page mode messaging suitable for a single

message exchange or a series of short messages similar to paging or SMS on a mobile device. Routing and mapping

mechanisms (defined in ETSI TS 103 479 [1]) to determine the proper control room, are based on location information.

Therefore a single message exchange is not practicable as caller location may change and lead to messages being routed

to a different control room. The present document defines specific message types to group messages into sessions with

routing and mapping only required at setup time. In addition the same principles are used to support supplementary

services like chat redirect and transfer. Each mechanism is transparent to ETSI TS 103 479 [1] core services and

Emergency communications services are primarily voice only, along with a marginal share of data and multimedia used

by Public Safety Answering Points (PSAPs). Improving access to emergency services for citizens, especially for the

deaf and hard of hearing, requires PSAPs and people in need to handle new modes of communications such as text.

Messenger services are widespread and well known to the public and currently, the present document defines extension

to support a comparable messenger service to access emergency control rooms by leveraging the new architecture

introduced in ETSI TS 103 479 [1]. The main purpose of the extensions is to enable a simplified chat session mode

combined with means to redirect or transfer a chat session. Furthermore the specification allows a lightweight

implementation of a messenger application for emergency chat or bot services. The fact that besides a signalling plane,

no further media sessions are required, supports a straight integration with firewalls or, in general, network security

The purpose of the present document is to describe a lightweight session based emergency chat protocol that extends

the base messaging functionality as defined in ETSI TS 103 479 [1]. The messaging service is based only on methods of

the SIP signalling plane and interworks with Border Control Function, Emergency Service Routing Proxy, Emergency

Call Routing Function, Public Safety Answering Point, the Location Information Server. It is important to emphasize

that the introduced feature is an alternative to MSRP, real-time text or, in general, total conversation and not a

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

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

Referenced documents which are not found to be publicly available in the expected location might be found at

The following referenced documents are necessary for the application of the present document.

[1] ETSI TS 103 479: "Emergency Communications (EMTEL); Core elements for network

[2] IETF RFC 2046: "Multipurpose Internet Mail Extensions (MIME) Part Two: MediaTypes ", Freed

[3] IETF RFC 3261: "SIP: Session Initiation Protocol", Rosenberg, J., Schulzrinne, H., Camarillo, G.,

[4] IETF RFC 3325: "Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity

Within Trusted Networks", Jennings, C., Peterson, J. and Watson, M., November 2002.

[5] IETF RFC 3326: "The Reason Header Field for the Session Initiation Protocol (SIP)", Oran, D.

[6] IETF RFC 3428: "Session Initiation Protocol (SIP) Extension for Instant Messaging", Campbell,

[7] IETF RFC 3841: " Caller Preferences for the Session Initiation Protocol (SIP)"," Rosenberg, J.,

[8] IETF RFC 4119: "A Presence-Based GEOPRIV Location Object Format", Peterson, J., December

[9] IETF RFC 4244: "An Extension to the Session Initiation Protocol (SIP) for Request History

[10] IETF RFC 4412: "Communications Resource Priority for the Session Initiation Protocol (SIP)",

[11] IETF RFC 4566: "SDP: Session Description Protocol", Handley, M., Jacobson, V. and Perkins, C.,

[12] IETF RFC 5031: "A Uniform Resource Name (URN) for Emergency and Other Well-Known

[13] IETF RFC 5621: "Message Body Handling in the Session Initiation Protocol (SIP)", Camarillo, G.,

[14] IETF RFC 6442: "Location Conveyance for the Session Initiation Protocol", Polk, J., Rosen, B.

[15] IETF RFC 6881: "Best Current Practice for Communications Services in Support of Emergency

[16] IETF RFC 7135: "Registering a SIP Resource Priority Header Field Namespace for Local

[17] IETF RFC 8446: "The Transport Layer Security (TLS) Protocol Version 1.3", V Rescorla, E.,

[18] W3C: "Decentralized Identifiers (DIDs) v1.0 Core Data Model and representations", Working

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

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

The following referenced documents are not necessary for the application of the present document, but they assist the

NOTE: Available at https://eena.org/knowledge-hub/documents/ng112-long-term-definition-standard-for-

[i.2] EENA Version 1.05, March 2016: "Public Safety Digital Transformation The Internet of Things

NOTE: Available at https://eena.org/document/the-internet-of-things-and-emergency-services/.

[i.3] W3C Recommendation, November 2019: "Verifiable Credentials Data Model 1.0".