ETSI TS 129 164 V16.0.0 (2020-08)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Interworking between the 3GPP CS domain with BICC or ISUP as signalling protocol and external SIP-I networks (3GPP TS 29.164 version 16.0.0 Release 16)

RTS/TSGC-0329164vg00

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 3 - Interworking with external networks (formely CN3)
• Current Stage: 12 - Completion
• Completion Date: 12-Aug-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
Interworking between the 3GPP CS domain with BICC or ISUP
as signalling protocol and external SIP-I networks
(3GPP TS 29.164 version 16.0.0 Release 16)

R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
3GPP TS 29.164 version 16.0.0 Release 16 1 ETSI TS 129 164 V16.0.0 (2020-08)

Reference
RTS/TSGC-0329164vg00
Keywords
GSM,UMTS
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3GPP TS 29.164 version 16.0.0 Release 16 2 ETSI TS 129 164 V16.0.0 (2020-08)
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Legal Notice
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ETSI
3GPP TS 29.164 version 16.0.0 Release 16 3 ETSI TS 129 164 V16.0.0 (2020-08)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 Network characteristics . 8
4.1 Key characteristics of ISUP/BICC based CS Domain . 8
4.2 Key characteristics of external SIP-I network . 8
5 Interworking reference model . 9
6 Control plane interworking . 9
6.1 General . 9
6.2 Interworking between CS Domain using ISUP signalling and external network using SIP-I signalling . 10
6.2.1 Control Plane Interworking . 10
6.2.2 Services performed by network entities in the control plane . 11
6.2.2.1 Services of the IWU . 11
6.2.2.2 Services of the external SIP-I signalling function . 11
6.2.3 Signalling interactions between network entities in the control plane . 11
6.2.3.1 Signalling between the IWU and SIP-I signalling function . 11
6.2.4 SIP-ISUP protocol interworking . 11
6.2.4.1 Incoming call interworking from SIP-I to ISUP at I-IWU . 11
6.2.4.1.0 General . 11
6.2.4.1.1 Interworking of received ISUP messages to SIP messages . 11
6.2.4.1.2 Receipt of encapsulated ISUP information within SIP . 12
6.2.4.1.3 Special Procedures for the Reception of SIP INVITE request . 12
6.2.4.1.3.1 Propagation of overlap signalling toward the 3GPP CS domain . 12
6.2.4.1.3.2 Derivation of TMR, USI and HLC parameters within send IAM message . 12
6.2.4.1.3.3 Receipt of SIP INVITE without SDP offer . 12
6.2.4.2 Outgoing Call Interworking from ISUP to SIP-I at O-IWU . 13
6.2.4.2.1 General . 13
6.2.4.2.2 Sending of ISUP information to adjacent SIP nodes . 13
6.2.4.2.3 Receipt of encapsulated ISUP information within SIP-I . 13
6.2.4.2.4 Special procedures related to outgoing INVITE . 14
6.2.4.2.4.1 Overlap Signalling . 14
6.2.4.2.4.2 Coding of encapsulated ISUP IAM parameters in outgoing INVITE . 14
6.2.4.2.4.3 Media offered in SDP of outgoing INVITE . 14
6.3 Interworking between CS Domain using BICC signalling and external network using SIP-I signalling . 14
6.3.1 Control Plane Interworking . 14
6.3.2 SIP-BICC protocol interworking . 15
6.3.2.1 General . 15
6.3.2.2 Incoming call interworking from SIP to BICC at I-IWU . 15
6.3.2.3 Outgoing Call Interworking from BICC to SIP at O-IWU . 15
6.4 Supplementary services . 15
6.4.1 Special procedures for supplementary service interworking . 15
6.4.2 Interworking of CLIP/CLIR supplementary service . 16
6.4.3 Interworking of Call Hold (HOLD) supplementary service . 16
6.4.4 Interworking of Completion of Calls to Busy Subscriber (CCBS) supplementary service to SIP
net works . 16
7 User plane Interworking . 16
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7.1 ISUP based CS Domain . 16
7.2 BICC based CS Domain . 16
8 Interactions between control node and MGW . 17
8.1 Overview . 17
8.2 Signalling interactions . 17
8.2.1 Backward through-connection for outgoing call interworking from BICC to SIP at O-IWU. . 17
8.2.2 Handling of RTP telephone events . 17
8.3 Signalling procedures . 18
Annex A (normative): Codec Negotiation between a BICC based CS Domain and an
external SIP-I network . 19
Annex B (informative): Change history . 20
History . 21

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3GPP TS 29.164 version 16.0.0 Release 16 5 ETSI TS 129 164 V16.0.0 (2020-08)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI
3GPP TS 29.164 version 16.0.0 Release 16 6 ETSI TS 129 164 V16.0.0 (2020-08)
1 Scope
The present document defines interworking procedures between a 3GPP CS domain (see 3GPP TS 23.205 [2]) which
applies either BICC or ISUP as signalling protocol, and external networks that use SIP-I (see ITU-T Q.1912.5 [20],
Profile C) as signalling protocol. The document also describes the related interworking architecture. The control plane
interworking is performed by an interworking unit at the interconnection between the 3GPP CS domain and an external
SIP-I network. The user plane interworking is performed by an MGW. The present document defines stage 2
procedures for the control of the MGW.
The present specification reuses existing interworking procedures of 3GPP TS 29.163 [4] and ITU-T Q.1912.5 [20],
Profile C, as far as possible.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 23.205: "Bearer-independent circuit-switched core network; Stage 2".
[3] 3GPP TS 26.102: "Adaptive Multi-Rate (AMR) speech codec; Interface to Iu and Uu".
[4] 3GPP TS 29.163: “Interworking between the IP Multimedia (IM) Core Network (CN) subsystem
and Circuit Switched (CS) networks”.
[5] 3GPP TS 29.205: "Application of Q.1900 series to Bearer Independent CS Network architecture;
Stage 3".
[6] 3GPP TS 29.332: "Media Gateway Control Function (MGCF) – IM-Media Gateway (IM-MGW)
interface, Stage 3".
[7] 3GPP TS 29.414: "Core network Nb data transport and transport signalling".
[8] 3GPP TS 29.415: "Core network Nb interface user plane protocols".
[9] ITU-T Recommendation E.164 (05/1997): "The international public telecommunication
numbering plan".
[10] ITU-T Recommendation G.711 (11/98): "Pulse Code Modulation (PCM) of voice frequencies".
[11] ITU-T Recommendation H.248.1 (05/02): "Gateway control protocol: Version 2".
[12] ITU-T Recommendation I.363.5 (1996): "B-ISDN ATM Adaptation Layer specification: Type 5
AAL".
[13] ITU-T Recommendation Q.701 (03/93), Q.702 (11/88), Q.703 (07/96), Q.704 (07/96), Q.705
(03/93), Q.706 (03/93), Q.707 (11/88), Q.708 (03/99), Q.709 (03/93): "Functional description of
the message transfer part (MTP) of Signalling System No. 7".
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[14] ITU-T Recommendation Q.730 (12/99), Q.731.1 (07/96), Q.731.3 (03/93), Q.731.4 (03/93),
Q.731.5 (03/93), Q.731.6 (03/93), Q.731.7 (06/97), Q.731.8 (02/92), Q.732.5-2 (12/99), Q.732.7
(07/96), Q.733.1 (02/92), Q.733.2 (03/93), Q.733.3 (06/97), Q.733.4 (03/93), Q.733.5 (12/99),
Q.734.1 (03/93), Q.734.2 (07/96), Q.735.1 (03/93), Q.735.3 (03/93), Q.735.6 (07/93), Q.736.1
(10/95), Q.736.3 (10/95), Q.737.1 (06/97): "ISDN user part supplementary services".
[15] ITU-T Recommendations Q.761to Q.764 (12/99): "Signalling System No.7 ISDN User Part".
[16] ITU-T Recommendation Q.765 (2000): "Signalling System No. 7 – Application transport
mechanism".
[17] ITU-T Recommendation Q.765.5 (2000): "Signalling system No. 7 – Application transport
mechanism: Bearer Independent Call Control (BICC)".
[18] ITU-T Recommendation 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".
[19] ITU-T Recommendations Q.1902.1 to Q.1902.6 (07/2001): "Bearer Independent Call Control".
[20] ITU-T Recommendation Q.1912.5 (03/04): "Interworking between Session Initiation Protocol
(SIP) and Bearer Independent Call Control Protocol or ISDN User Part".
[21] ITU-T Recommendation Q.2110 (1994): "B-ISDN ATM adaptation layer - Service Specific
Connection Oriented Protocol (SSCOP)".
[22] ITU-T Recommendation Q.2140 (1995): "B-ISDN ATM adaptation layer - Service specific
coordination function for signalling at the network node interface (SSCF AT NNI)".
[23] ITU-T Recommendation Q.2210 (1996): "Message transfer part level 3 functions and messages
using the services of ITU-T Recommendation Q.2140".
[24] IETF RFC 791: "Internet Protocol".
[25] IETF RFC 768: "User Datagram Protocol".
[26] IETF RFC 793: "Transmission Control Protocol".
[27] IETF RFC 2460: "Internet Protocol, Version 6 (IPv6) Specification"
[28] IETF RFC 4733: "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals".
[29] IETF RFC 2960: "Stream Control Transmission Protocol".
[30] IETF RFC 2976: "The SIP INFO Method".
[31] IETF RFC 3204: "MIME media types for ISUP and QSIG Objects".
[32] IETF RFC 3261: "SIP: Session Initiation Protocol".
[33] IETF RFC 3262: "Reliability of provisional responses".
[34] IETF RFC 3264: "An Offer/Answer Model with the Session Description Protocol (SDP)".
[40] IETF RFC 3311: "SIP UPDATE method".
[35] IETF RFC 3312: "Integration of Resource Management and Session Initiation Protocol (SIP)".
[36] IETF RFC 3550: "RTP: A Transport Protocol for Real-Time Applications".
[37] 3GPP TS 29.202: "Core Signalling System No. 7 (SS7) signalling transport in core network; Stage
3".
[38] 3GPP TS 29.231: "Application of SIP-I Protocols to Circuit Switched (CS) core network
architecture; Stage 3".
[39] 3GPP TS 29.235: "Interworking between the 3GPP CS domain with SIP-I as signalling protocol
and other networks".
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3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1], in
3GPP TS 29.163 [4], in ITU-T E.164 [9], in ITU-T Q.1912.5 [20] and the following apply. A term defined in the
present document takes precedence over the definition of the same term, if any, in any other of the specifications listed
above.
Interworking Unit (IWU): Logical entity that interworks SIP-I signalling with BICC or ISUP signalling in the 3GPP
CS Domain.
Incoming Interworking Unit (I-IWU): Logical entity that terminates incoming calls from the external SIP-I network
side and originates outgoing calls towards the CS Domain side using the BICC or ISUP protocols.
Outgoing Interworking Unit (O-IWU): Logical entity that terminates incoming BICC or ISUP calls from the CS
Domain side and originates outgoing calls towards external SIP-I network.
External SIP-I signalling function: function in the external network, which has the capabilities to process SIP with
encapsulated ISUP messages.
For references to 3GPP TS 29.163 [4] procedures within the present specification, the MGCF in 3GPP TS 29.163 [4] is
to be understood as IWU. The IM-MGW is to be understood as MGW. The Mn interface is to be understood as
interface between IWU and MGW. The IM CN subsystem is to be understood as external SIP-I network. The CS
network is to be understood as 3GPP CS domain.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1], in 3GPP TS 29.163 [4], in
ITU-T E.164 [9], in ITU-T Q.1912.5 [20], and the following apply. An abbreviation defined in the present document
takes precedence over the definition of the same abbreviation, if any, in any other of the specification listed above.
IW-MGW Interworking Media Gateway Function

4 Network characteristics
4.1 Key characteristics of ISUP/BICC based CS Domain
The 3GPP CS domain uses either BICC Capability Set 2 (see ITU-T Q.1902.1 to Q.1902.6 [19] and Q.765.5 [17]) with
3GPP specific extensions, as specified for the 3GPP Nc interface in 3GPP TS 29.205 [5], or ISUP (see ITU-T Q.761 to
Q.764 [15]), as signalling protocol.
If BICC is used as signalling protocol, the 3GPP Nb interface, as specified in 3GPP TS 29.414 [7] and 3GPP TS 29.415
[8], is used for the user plane transport. If ISUP is applied as signalling protocol, TDM transport of the user plane is
applied.
4.2 Key characteristics of external SIP-I network
The external SIP-I network applies SIP, IETF RFC 3261 [32], with ISUP encapsulated according to IETF RFC 3204
[31], as specified in ITU-T Q.1912.5 [20] Profile C. The SIP Signalling Profile defined for Profile C in Annex C of
Q.1912.5 is applied.
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The network uses either IPv4 (IETF RFC 791 [24]) or IPv6 (IETF RFC 2460 [27]).
For the transport of most media, RTP (IETF RFC 3550 [36]) over UDP (IETF RFC 768 [25]) is applied.
For the transport of control signalling, UDP (IETF RFC 768 [25]), TCP (IETF RFC 793 [26]) or SCTP (IETF RFC
2960 [29]) can be used.
5 Interworking reference model
Figure 5.1 details the interworking reference model for the present specification

BICC/ISUP over Nc/ISUP
SGW
M3UA/SCTP/IP over TDM
(G)MSC
IWU
Server
BICC/ISUP over
SCTP/IP
SIP-I
External H.248
Mc
SIP-I
E.g.
media/
Network
RTP/
UDP/IP/
Nb/TDM
IW-
MGW
MGW
3GPP CS Domain
Scope Of
User Plane
thisTS
Control Plane
NOTE 1: If needed a SGW is applied for conversion (both ways) of the transport level between the IWU and the
(G)MSC. The SGW may be implemented as a stand-alone entity or it may be located in another entity of
the CS Domain. A SGW function is not required for certain signalling transports, where M3UA+SCTP+IP is
used in CS network and IWU. The implementation options are not further discussed in the present
document.
NOTE 2: The IWU is a logical function that may reside with other 3GPP logical functions in the same physical
nodes, e.g. in an (G)MSC Server. The figure shows only the logical separation.

Figure 5.1: interworking reference model
6 Control
...