ETSI TS 123 228 V15.4.0 (2019-04)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2 (3GPP TS 23.228 version 15.4.0 Release 15)

RTS/TSGS-0223228vf40

General Information

• Status: Published
• Publication Date: 25-Apr-2019
• Technical Committee: 3GPP SA 2 - Architecture
• Current Stage: 12 - Completion
• Completion Date: 26-Apr-2019

Standards Content (Sample)

ETSI TS 123 228 V15.4.0 (2019-04)






TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
IP Multimedia Subsystem (IMS);
Stage 2
(3GPP TS 23.228 version 15.4.0 Release 15)

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3GPP TS 23.228 version 15.4.0 Release 15 1 ETSI TS 123 228 V15.4.0 (2019-04)



Reference
RTS/TSGS-0223228vf40
Keywords
GSM,LTE,UMTS
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3GPP TS 23.228 version 15.4.0 Release 15 2 ETSI TS 123 228 V15.4.0 (2019-04)
Intellectual Property Rights
Essential patents
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
server (https://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.
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Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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3GPP TS 23.228 version 15.4.0 Release 15 3 ETSI TS 123 228 V15.4.0 (2019-04)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 15
1 Scope . 16
2 References . 16
3 Definitions, symbols and abbreviations . 20
3.1 Definitions . 20
3.2 Symbols . 22
3.3 Abbreviations . 23
4 IP multimedia subsystem concepts . 24
4.0 General . 24
4.1 Relationship to CS domain and the IP-Connectivity Access Network . 25
4.2 IMS services concepts . 26
4.2.1 Home-network based services . 26
4.2.1.1 Support of CAMEL or IN . 26
4.2.1.2 Support of OSA . 26
4.2.1.3 Dynamic services interactions handling . 26
4.2.1.3.1 Service information exchanged between Application Servers . 26
4.2.1.3.2 Handling by the Application Server . 26
4.2.1.3.3 Deletion of services interaction information . 26
4.2.2 Support of numbers in non-international format in the IMS . 26
4.2.3 Support of roaming users . 27
4.2.4 IP multimedia Subsystem Service Control Interface (ISC) . 29
4.2.4a HSS to service platform Interface . 31
4.2.4b S-CSCF Service Control Model . 33
4.2.4c I-CSCF to AS reference point (Ma) . 34
4.2.5 The QoS requirements for an IM CN subsystem session. 35
4.2.6 QoS Requirements for IM CN subsystem signalling . 36
4.2.7 Support of SIP forking . 37
4.2.7.1 SIP Forking . 37
4.2.7.2 Forking within and outside the IM CN Subsystem . 37
4.2.7.3 Support for forked requests . 38
4.3 Naming and addressing concepts . 38
4.3.1 Address management . 38
4.3.2 Void . 38
4.3.3 Identification of users . 38
4.3.3.0 General . 38
4.3.3.1 Private User Identities . 38
4.3.3.2 Public User Identities . 39
4.3.3.2a Globally Routable User Agent URI (GRUU) . 40
4.3.3.2a.1 Architecture Requirements . 40
4.3.3.2b Wildcarded Public User Identity . 41
4.3.3.3 Routing of SIP signalling within the IP multimedia subsystem . 41
4.3.3.3a Handling of dialled number formats . 42
4.3.3.3b Termination of session with the TEL URI format Public User Identity . 42
4.3.3.4 Relationship of Private and Public User Identities . 42
4.3.3.5 Relationship of Public User Identities, GRUUs, and UEs . 43
4.3.4 Identification of network nodes . 44
4.3.5 E.164 address to SIP URI resolution in an IM CN subsystem . 44
4.3.5.1 ENUM/DNS translation mechanism . 44
4.3.5.2 Handling of Tel URIs . 44
4.3.5.3 Handling of SIP URIs representing a telephone number . 44
4.3.6 Public Service Identities . 45
4.4 Signalling concepts. 45
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3GPP TS 23.228 version 15.4.0 Release 15 4 ETSI TS 123 228 V15.4.0 (2019-04)
4.5 Mobility related concepts . 46
4.6 Roles of Session Control Functions . 46
4.6.0 General . 46
4.6.1 Proxy-CSCF . 46
4.6.2 Interrogating-CSCF . 47
4.6.2.0 General . 47
4.6.2.1 Void. 48
4.6.3 Serving-CSCF . 48
4.6.4 Breakout Gateway Control Function . 50
4.6.5 Void . 51
4.7 Multimedia Resource Function . 51
4.7a Media Resource Broker . 52
4.8 Security Concepts . 52
4.9 Charging Concepts . 52
4.10 IMS group management concepts . 52
4.10.0 General . 52
4.10.1 IMS group administration . 52
4.10.2 Group identifiers . 53
4.11 Relationship to 3GPP Generic User Profile (GUP) . 53
4.12 Network Address Translation traversal in access network . 53
4.13 Identification of IMS communication Services . 53
4.13.1 General . 53
4.13.2 Identification of IMS communication Services . 53
4.13.3 Identification of IMS applications . 55
4.14 Border Control concepts . 56
4.15 IMS in transit network scenarios . 57
4.15.1 General concepts . 57
4.15.2 IMS transit network configurations . 57
4.15.3 Providing IMS application services in transit network scenarios . 57
4.15a Roaming Architecture for Voice over IMS with Local Breakout . 58
4.15b Roaming Architecture for Voice over IMS with home routed traffic . 59
4.16 Support of multimedia telephony . 59
4.16.1 Telephony Application Server . 59
4.16.2 Identification of multimedia telephony . 59
4.16.3 Session setup principles . 60
4.17 Support of short message service . 60
4.17.1 IP Short Message Gateway (IP-SM-GW) . 60
4.18 Support of Number portability . 60
4.18.1 Number portability . 60
4.19 Support of Preferred Circuit Carrier Access and Per Call Circuit Carrier Selection . 61
4.19.1 Preferred Circuit Carrier Access and Per Call Circuit Carrier Selection . 61
4.20 Support of IMS Service Centralization and Continuity . 61
4.21 Support of Overlap Signalling . 61
4.22 Support of Explicit Congestion Notification (ECN) . 62
4.22.1 General . 62
4.22.2 CS GERAN/UTRAN Interworking at MGCF/IM-MGW . 62
4.22.3 Interworking with non-ECN IP network and/or terminal at IBCF/TrGW . 63
4.22.4 Interworking with non-3GPP ECN IP terminal at IBCF/TrGW . 63
4.22.5 ECN support at IMS-ALG/IMS-AGW . 63
4.22.6 ECN support at MRFC/MRFP . 64
4.22.7 CS GERAN/UTRAN Interworking at the MSC Server enhanced for ICS/MSC Server enhanced for
SRVCC with SIP/CS-MGW . 64
4.23 Support of Load Balancing . 64
4.23.1 General . 64
4.23.2 Registration-based load balancing of S-CSCFs . 64
4.23.3 Registration independent load balancing of Transit Functions . 65
4.24 Support of Restoration Procedures . 65
4.25 Support of Overload Control . 65
4.25.1 General . 65
4.25.2 Next-hop monitoring of overload . 65
4.25.3 Filter based Overload Control . 66
4.26 Support for Business Trunking . 66
ETSI

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3GPP TS 23.228 version 15.4.0 Release 15 5 ETSI TS 123 228 V15.4.0 (2019-04)
5 IP multimedia subsystem procedures . 66
5.0 General . 66
5.0a Session-unrelated procedures . 67
5.1 CSCF related procedures . 67
5.1.0 Establishing IP-Connectivity Access Network bearer for IM CN Subsystem Related Signalling . 67
5.1.1 Procedures related to Proxy-CSCF discovery . 67
5.1.1.0 General . 67
5.1.1.1 DHCP/DNS procedure for P-CSCF discovery . 67
5.1.1.2 Void. 68
5.1.2 Procedures related to Serving-CSCF assignment . 68
5.1.2.1 Assigning a Serving-CSCF for a user . 68
5.1.2.2 Cancelling the Serving-CSCF assignment . 69
5.1.2.3 Void. 69
5.1.3 Procedures related to Interrogating-CSCF . 69
5.1.4 Procedures related to Proxy-CSCF . 70
5.1.5 Subscription Updating Procedures . 70
5.1.5.0 General . 70
5.1.5.1 Subscription updating information flow . 70
5.2 Application level registration procedures . 70
5.2.0 General . 70
5.2.1 Requirements considered for registration . 70
5.2.1a Implicit Registration . 71
5.2.1a.0 General . 71
5.2.1a.1 Implicit Registration for UE without ISIM or IMC . 73
5.2.2 Registration flows . 73
5.2.2.1 Requirements to consider for registration . 73
5.2.2.2 Assumptions . 73
5.2.2.3 Registration information flow – User not registered . 74
5.2.2.4 Re-Registration information flow – User currently registered . 75
5.2.2.5 Stored information. . 77
5.3 Application level de-registration procedures . 78
5.3.1 Mobile initiated de-registration. 78
5.3.2 Network initiated de-registration . 79
5.3.2.0 General . 79
5.3.2.1 Network Initiated Application (SIP) De-registration, Registration Timeout . 80
5.3.2.2 Network Initiated Application (SIP) De-registration, Administrative. 80
5.3.2.2.0 General . 80
5.3.2.2.1 Network Initiated De-registration by HSS, administrative . 81
5.3.2.2.2 Network Initiated De-registration by Service Platform . 81
5.4 Procedures for IP multi-media sessions . 83
5.4.0 General . 83
5.4.1 Bearer interworking concepts . 83
5.4.2 Interworking with Internet . 83
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