ETSI TS 103 389 V1.2.1 (2013-09)

ETSI TS 103 389 V1.2.1 (2013-09)






Technical Specification
Railway Telecommunications (RT);
Global System for Mobile communications (GSM);
Usage of Session Initiation Protocol (SIP) on the
Network Switching Subsystem (NSS) to Fixed Terminal
Subsystem (FTS) interface for GSM Operation on Railways

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2 ETSI TS 103 389 V1.2.1 (2013-09)



Reference
RTS/RT-00021
Keywords
FTS, SIP, GSM-R, NSS, railways
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3 ETSI TS 103 389 V1.2.1 (2013-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 9
4 Reference System Architecture . 10
5 Interface Functionality . 11
5.1 Basic Call . 11
5.1.1 Progress Indication . 11
5.1.2 Early Media . 12
5.2 Connected Parties Identity Information . 12
5.3 Call Hold . 12
5.4 Multi Level Precedence and Pre-emption . 12
5.5 Voice Group Call and Broadcast Call Control . 12
5.6 User-User-Information-Element Transport . 12
5.7 Reason Transport . 13
6 Signalling Interface . 13
6.1 Network Layer Protocol . 13
6.2 Transport Layer Protocol . 13
6.3 Signalling Protocol . 13
6.3.1 SIP Entities . 13
6.3.1.1 SIP User Agent . 14
6.3.1.2 SIP Proxy . 14
6.3.2 SIP Request Methods . 14
6.3.3 SIP Responses . 15
6.3.4 SIP Header Fields . 15
6.3.5 SIP Bodies . 17
6.3.6 SIP URI Convention . 18
6.3.6.1 Display Name . 19
6.3.6.2 User Part . 19
6.3.6.3 Host Part . 19
6.3.6.4 URI Parameters . 19
6.3.6.5 Use . 19
6.3.6.6 Examples . 20
6.3.7 Option Tags . 21
6.4 Interface Functionality to Signalling Interface Mapping . 22
6.4.1 Basic Call . 22
6.4.2 Connected Parties Identity Information . 23
6.4.3 Media Session Renegotiation and Call Hold . 25
6.4.4 Early Media . 27
6.4.5 Multi Level Precedence and Pre-emption . 29
6.4.5.1 Resource Priority . 30
6.4.5.2 Reason Indication for Precedence and Pre-emption Events . 30
6.4.5.3 Signalling Procedure for Precedence Call Blocking . 30
6.4.5.4 Signalling Procedure for Pre-emption . 31
6.4.6 Group Call and Broadcast Call Control . 32
6.4.7 User-to-User-Information-Element Transport . 32
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4 ETSI TS 103 389 V1.2.1 (2013-09)
6.4.8 Release Cause Transport . 33
6.4.9 SIP Session Timer . 33
6.4.10 OPTIONS Processing . 35
6.4.10.1 OPTIONS Heartbeating . 36
6.4.11 Signalling for Group Call and Broadcast Call Control . 36
7 Media Interface . 38
7.1 Network Layer Protocol . 38
7.2 Transport Layer Protocol . 38
7.3 Real-Time Transport Protocol . 38
7.3.1 Media inactivity detection . 38
7.4 Media Codecs . 39
7.4.1 DTMF . 39
7.4.1.1 Limitations to RFC 4733 . 39
Annex A (normative): Locating SIP Entities . 40
Annex B (informative): Quality of Service Framework . 43
Annex C (informative): Security Framework . 44
Annex D (informative): Mapping of EIRENE to Interface Features . 45
Annex E (informative): Group Call Control Scenarios . 47
Annex F (informative): Bibliography . 49
History . 50

ETSI

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5 ETSI TS 103 389 V1.2.1 (2013-09)
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 Technical Committee Railway Telecommunications
(RT).
Introduction
While a number of interoperability specifications for various interfaces at various layers of GSM-R systems exist, the
interface between the Network Switching Subsystem (NSS) and the Fixed Terminal Subsystem (FTS) has not yet been
addressed by any interoperability specification activity.
In most of the GSM-R system deployments available at the time of the creation of the present document, the Network
Switching Subsystem and the Fixed Terminal Subsystem are interconnected using TDM based interfaces such as
DSS1 [i.2].
TS 102 610 [9] specifies the usage and format of UUIE for call-related end-to-end functionality in GSM-R systems but
no other interworking topics.
The present document addresses the interoperability specification gap between the Network Switching Subsystem and
the Fixed Terminal Subsystem with an interface based on the Internet Protocol (IP) [2], the Session Initiation Protocol
(SIP) [3], the Session Description Protocol (SDP) [6] and the Real-Time Transport Protocol (RTP) [7].
In addition to the table of contents, the following explanation will help you navigate through and understand the
contents of the present document:
• Clauses 1 to 3 are predefined by ETSI.
• Clause 4 shows and explains the reference system architecture and identifies the interface(s) for the present
document.
• Clause 5 holds the functional requirements for the interface subject to the present document.
• Clause 6 specifies in detail the signalling interface for all supported functions and services.
• Clause 7 specifies in detail the media interface.
• Annex A explains the mechanism to locate SIP entities at the present interface.
• Annex B contains recommendations on the use and implementation of standardized Quality of Service
mechanisms at the present interface.
• Annex C contains recommendations about the security mechanisms.
• Annex D contains a mapping table of EIRENE [1] to interface features.
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6 ETSI TS 103 389 V1.2.1 (2013-09)
1 Scope
The present document defines the signalling and media interface between the Network Switching Subsystem and the
Fixed Terminal Subsystem in order to provide a clear set of services needed for GSM-R operations. This includes voice
call service and available call-related supplementary services. The present document addresses the Internet Layer and
upwards of the Internet Protocol Suite [i.18] on the signalling and media interface.
Any service other than voice call service and call-related supplementary services (such as data services, Short Message
Service, etc.) is out of scope of the present document; additional features may be addressed in future releases.
The present document does not specify any other interface between the Network Switching Subsystem and the Fixed
Terminal Subsystem nor does it cover any internal interfaces of either NSS or FTS. Voice recording and related
interfaces are out of scope of the present document. Such interfaces may be addressed in a future release of the present
document.
The present document does not address any specific 3GPP Release or Architecture.
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] UIC P001D010 (Version 15.1): "UIC Project EIRENE System Requirements Specification".
NOTE: Available at http://www.uic.org/IMG/pdf/eirene_srs_15.1.pdf.
[2] IETF RFC 791 (1981): "Internet Protocol".
[3] IETF RFC 3261 (2002): "SIP: Session Initiation Protocol".
[4] IETF RFC 3264 (2002): "An Offer/Answer Model Session Description Protocol (SDP)".
[5] IETF RFC 4733 (2006): "RTP Payload for DTMF Digits, Telephony Tones, and Telephony
Signals".
[6] IETF RFC 4566 (2006): "SDP: Session Description Protocol".
[7] IETF RFC 3550 (2003): "RTP: A Transport Protocol for Real-Time Applications".
[8] IETF RFC 3326 (2002): "The Reason Header Field for the Session Initiation Protocol (SIP)".
[9] ETSI TS 102 610 (V1.1.0): "Railways Telecommunications (RT); Global System for Mobile
communications (GSM); Usage of the User to User Information Element for GSM Operation on
Railways".
[10] IETF RFC 5234 (2008): "Augmented BNF for Syntax Specifications: ABNF".
[11] IETF RFC 3262 (2002): "Reliability of Provisional Responses in the Session Initiation Protocol
(SIP)".
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7 ETSI TS 103 389 V1.2.1 (2013-09)
[12] IETF RFC 4412 (2006): "Communications Resource Priority for the Session Initiation Protocol
(SIP)".
[13] IETF RFC 3325 (2002): "Private Extensions to the Session Initiation Protocol (SIP) for Asserted
Identity within Trusted Networks".
[14] IETF RFC 5876 (2010): "Updates to Asserted Identity in the Session Initiation Protocol (SIP)".
[15] IETF RFC 3323 (2002): "A Privacy Mechanism for the Session Initiation Protocol (SIP)".
[16] IETF RFC 4028 (2005): "Session Timers in the Session Initiation Protocol (SIP)".
[17] IETF RFC 3311 (2002): "The Session Initiation Protocol (SIP) UPDATE Method".
[18] IETF RFC 2474 (1998): "Definitions of the Differentiated Services Field (DS Field) in the IPv4
and IPv6 Headers".
[19] IETF RFC 2475 (1998): "An Architecture for Differentiated Services".
[20] IETF RFC 4594 (2006): "Configuration Guidelines for DiffServ Service Classes".
[21] IETF RFC 5865 (2010): "A Differentiated Services Code Point (DSCP) for Capacity-Admitted
Traffic".
[22] Recommendation ITU-T Q.850 (1998): "Usage of cause and location in the Digital Subscriber
Signalling System No. 1 and the Signalling System No. 7 ISDN user part".
[23] Recommendation ITU-T E.164 (2010): "The international public telecommunication numbering
plan".
[24] Recommendation ITU-T Q.955.3 (1993): "Stage 3 description for community of interest
supplementary services using DSS 1: Multi-level precedence and preemption (MLPP)".
[25] IETF RFC 3986 (2005): "Uniform Resource Identifier (URI): Generic Syntax".
[26] IETF RFC 768 (1980): "User Datagram Protocol".
[27] Recommendation ITU-T G.711 (1998): "Pulse code modulation (PCM) of voice frequencies".
[28] IETF RFC 2833 (2000): "RTP Payload for DTMF Digits, Telephony Tones and Telephony
Signals".
[29] IETF RFC 5009 (2007): "Private Header (P-Header) Extension to the Session Initiation Protocol
(SIP) for Authorization of Early Media".
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] IETF draft RFC draft-johnston-cuss-sip-uui-01: "A Mechanism for Transporting User to User Call
Control Information in SIP".
[i.2] ETSI ETS 300 403-1 (V1.3.2): "Integrated Services Digital Network (ISDN); Digital Subscriber
Signalling System No. one (DSS1) protocol; Signalling network layer for circuit-mode basic call
control; Part 1: Protocol specification [ITU-T Recommendation Q.931 (1993), modified]".
[i.3] IETF RFC 6086 (2011): "Session Initiation Protocol (SIP) INFO Method and Package
Framework".
[i.4] IETF RFC 3428 (2002): "Session Initiation Protocol (SIP) Extension for Instant Messaging".
[i.5] IETF RFC 3515 (2001): "The Session Initiation Protocol (SIP) Refer Method".
[i.6] IETF RFC 3265 (2002): "Session Initiation Protocol (SIP)-Specific Event Notification".
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8 ETSI TS 103 389 V1.2.1 (2013-09)
[i.7] IETF RFC 3903 (2004): "Session Initiation Protocol (SIP) Extension for Event State Publication".
[i.8] IETF RFC 1594 (1994): "FYI on Questions and Answers to Commonly asked "New Internet User"
Questions".
[i.9] IETF RFC 3665 (2003): "Session Initiation Protocol (SIP) Basic Call Flow Examples".
[i.10] IETF RFC 3960 (2004): "Early Media and Ringing Tone Generation in the Session Initiation
Protocol (SIP)".
[i.11] ETSI EN 300 925 (V7.0.2): "Digital cellular telecommunications system (Phase 2+) (GSM);
Voice Group Call Service (VGCS) - Stage 1 (GSM 02.68 version 7.0.2 Release 1998)".
[i.12] ETSI EN 300 926 (V8.0.1): "Digital cellular telecommunications system (Phase 2+) (GSM);
Voice Broadcast Service (VBS) - Stage 1 (GSM 02.69 version 8.0.1 Release 1999)".
[i.13] IETF RFC 3263 (2002): "Session Initiation Protocol (SIP): Locating SIP Servers".
[i.14] IETF RFC 1035 (1987): "Domain names - implementation and specification".
[i.15] IETF RFC 2181 (1997): "Clarifications to the DNS Specification".
[i.16] IETF RFC 2663 (1999): "IP Network Address Translator (NAT) Terminology and
Considerations".
[i.17] Recommendation ITU-T I.255.3 (1990): "Multi-Level Precedence and Pre-emption service".
[i.18] IETF RFC 1122 (1989): "Requirements for Internet Hosts -- Communication Layers".
[i.19] IETF RFC 3551: "RTP Profile for Audio and Video Conferences with Minimal Control".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
call: refers to a SIP Dialog (RFC 3261 [3]) between two Signalling Endpoints, established for the purpose of a voice
communication and related data exchange
Client: As defined in RFC 3261 [3].
Dialog: As defined in RFC 3261 [3].
Final response: As defined in RFC 3261 [3].
Fixed Terminal Subsystem (FTS): part of the EIRENE [1] system that provides access to this network (and services)
via controller equipment (in general referred to as Fixed Terminals)
Fully-Qualified Domain Name: As defined in RFC 1594 [i.8].
Header: As defined in RFC 3261 [3].
Header field: As defined in RFC 3261 [3].
Initiator, Calling Party, Caller: As defined in RFC 3261 [3].
Invitee, Invited User, Called Party, Callee: As defined in RFC 3261 [3].
Media Endpoint, RTP Endpoint: entity that terminates RTP stream(s) under the control of a single SIP Endpoint in
the same subsystem
NOTE: This entity may be physically separated from the SIP Endpoint.
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9 ETSI TS 103 389 V1.2.1 (2013-09)
Method: As defined in RFC 3261 [3].
Network Switching Subsystem (NSS): part of the PLMN infrastructure that performs all necessary functions in order
to handle the call services to and from the mobile stations as well as to and from fixed terminals
operational priority: as defined in EIRENE SRS [1] different call types have call priorities during railway
communications. This behaviour is mentioned as operational priority of a call
Option-tag: As defined in RFC 3261 [3].
Provisional response: As defined in RFC 3261 [3].
Proxy, proxy server: As defined in RFC 3261 [3].
Request: As defined in RFC 3261 [3].
Response: As defined in RFC 3261 [3].
Server: As defined in RFC 3261 [3].
Session: As defined in RFC 3261 [3].
Signalling Endpoint, SIP Endpoint: entity that acts as a SIP User Agent
NOTE: Within the scope of the present document this term refers to NSS and FTS.
Signalling Proxy, SIP Proxy: Proxy Server as defined by RFC 3261 [3]
(SIP) transaction: As defined in RFC 3261 [3].
Tag: As defined in RFC 3261 [3].
User Agent Client: As defined in RFC 3261 [3].
User Agent Server: As defined in RFC 3261 [3].
User Agent: As defined in RFC 3261 [3].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AF Assured Forwarding
AoCC Advice of Charge (Charging)
AoCI Advice of Charge (Information)
B2BUA Back to Back User Agent
BAIC Barring of All Incoming Calls
BAOC Barring of All Outgoing Calls
BIC-Roam Barring of Incoming Calls when Roaming Outside the Home PLMN Country
BOIC Barring of Outgoing International Calls
BOIC-exHC BOIC except those to Home PLMN Country
CCBS Completion of Calls to Busy Subscribers
CFB Call Forwarding on Mobile Subscriber Busy
CFNRc Call forwarding on Mobile Subscriber Not Reachable
CFNRy Call Forwarding on No Reply
CFU Call Forwarding Unconditional
CLIP Calling Line Identification Presentation
CLIR Calling Line Identification Restriction
CoLP Connected Line Identification Presentation
CoLR Connected Line Identification Restriction
CUG Closed User Group
CW Call waiting
DNS Domain Name Service
DSCP Differentiated Service Code Point
DTMF Dual Tone Multi Frequency
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10 ETSI TS 103 389 V1.2.1 (2013-09)
ECT Explicit Call Transfer
EF Expedited Forwarding
EIRENE European Integrated Railway Radio Enhanced Network
eMLPP enhanced Multi-Level Precedence and Pre-emption
FQDN Fully Qualified Domain Name
FTS Fixed Terminal Subsystem
GSM-R Global System Mobile-Railways
HOLD Call hold
IP Internet Protocol
MLPP Multi-Level Precedence and Pre-emption
MO/PP Mobile Originated/Point-to-Point
MPTY Multi Party Service
MT/PP Mobile Terminated/Point-to-Point
NAPT Network Address Port Translation
NAT Network Address Translation
NSS Network Switching Subsystem
PABX Private Access Branch eXchange
PHB Per Hop Behaviour
PLMN Public Land Mobile Network
PRACK Provisional Response Acknowledgement
PSTN Public Switched Telephone Network
QoS Quality of Service
RFC Request For Comments
RTP Real-Time Transport Protocol
SDP Session Description Protocol
SIP Session Initiation Protocol
SRTP Secured Real-time Protocol
TDM Time Division Multiplexing
ToS Type of Service
UA User Agent
UAC User Agent Client
UAS User Agent Server
UDP User Datagram Protocol
UIC Union Internationale des Chemins de Fer, International Union of Railways
URI Uniform Resource Identifier
USSD Unstructured Supplementary Service Data
UUIE User to User Information Element
UUS1 User-to-User Signalling 1
VBS Voice Broadcast Service
VGCS Voice Group Call Service
4 Reference System Architecture
The system architecture used to identify the interface that is the subject of the present document is a simplification of a
GSM-R system down to a minimum of logical entities relevant to the present document.
Within the context of the present document a GSM-R system is logically divided into a GSM-R Network and a Fixed
Terminal Subsystem. The interface between the Mobile Terminals and the NSS as well as the interface between the
Fixed Terminals and the FTS are explicitly not addressed in the present document. The focus of the present document is
solely:
• the Signalling Interface; and
• the Media Interface;
between the logical subsystem NSS and the logical subsystem FTS.
It is important to note that this architecture does not necessarily reflect any physical entities in a GSM-R system.
...