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X.P0013-000-B v1.0 1 ALL-IP CORE NETWORK MULTIMEDIA DOMAIN - OVERVIEW 2 3 4 5 CONTENTS 6 7 1 Introduction .............................................................................................................................................. 1 2 Scope ........................................................................................................................................................ 2 3 Reference ................................................................................................................................................. 3 8 9 10 11 12 13 14 3.1 Normative References ................................................................................................................ 3 3.2 Informative References .............................................................................................................. 3 15 16 4 Terminology ............................................................................................................................................. 4 5 Assumptions ............................................................................................................................................. 5 6 Definitions ................................................................................................................................................ 6 17 18 19 20 21 22 6.1 Quality of Service (QoS) ........................................................................................................... 6 23 6.2 Home Subscriber Server (HSS) ................................................................................................. 6 24 25 7 Abbreviations ........................................................................................................................................... 7 8 MMD Core Network Architecture ........................................................................................................... 9 26 27 28 29 8.1 Network Entities ...................................................................................................................... 13 30 8.2 Reference Points ...................................................................................................................... 13 31 32 9 Documents for the core network packet data subsystem ........................................................................ 14 10 Documents for the core network IP Multimedia subsystem ................................................................... 15 11 Documents for the core network service capability subsystem .............................................................. 16 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 i X.P0013-000-B v1.0 1 LIST OF FIGURES 2 3 Figure 1 HSS Collective .......................................................................................................................... 6 4 5 Figure 2 MMD Core Network Architecture Model ................................................................................. 9 Figure 3 Packet Data Subsystem Core Network Architecture Model ....................................................10 6 7 8 9 10 Figure 4 IMS Core Network Architecture Model...................................................................................11 Figure 5 Session Control Reference Model ............................................................................................12 11 12 13 14 15 Figure 6 Multimedia Application Server Control Plane .........................................................................12 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 ii X.P0013-000-B v1.0 1 2 LIST OF TABLES 3 4 Table 1. Abbreviations .............................................................................................................................8 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 iii X.P0013-000-B v1.0 1 FOREWORD 2 3 4 5 (This foreword is not part of this document) 6 This document was prepared by 3GPP2 TSG-X. 7 This document contains major modifications from the previous revision. 9 8 10 This document is part of the series of documents X.S0013. 11 12 "Shall" and "shall not" identify requirements to be followed strictly to conform to this document and from which no deviation is permitted. "Should" and "should not" indicate that one of several possibilities is recommended as particularly suitable, without mentioning or excluding others, that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is discouraged but not prohibited. "May" and "need not" indicate a course of action permissible within the limits of the document. "Can" and "cannot" are used for statements of possibility and capability, whether material, physical or causal. 13 14 15 16 17 18 19 20 21 22 REVISION HISTORY 23 24 25 26 Revision Changes Date 27 28 29 30 0 v1.0 Initial Publication December 2003 0 v2.0 Version 2 July 2005 A. v1.0 Release A November 2005 34 B. v1.0 Release B December 2007 36 31 32 33 35 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 iv X.P0013-000-B v1.0 1 2 1 Introduction 3 4 5 6 7 8 The Multimedia Domain (MMD) is a collection of core network entities providing 3rd generation capabilities and based on IP protocols, elements and principles. This document provides an introduction to the core network elements and interfaces that make up a portion of the MMD. This document also introduces the series of documents that provide the complete specification of the core network interfaces and protocols that provide this part of the MMD capabilities. 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 1 X.P0013-000-B v1.0 2 1 Scope 2 3 This document contains the introduction of the Stage-1, Stage-2 and Stage-3 recommendations for the Multimedia Domain. It includes an overview of the system elements and interfaces and lists the series of documents that provide the complete specifications for the core network portions of the MMD. Not all MMD entities and interfaces may be covered by this version of this series of specifications. The specific entities and interfaces covered by a particular version are identified in each of the individual specifications. 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 2 X.P0013-000-B v1.0 1 2 3 Reference 3.1 Normative References 3 4 5 6 7 The following standards and documents contain provisions which, through reference in this text, constitute provisions of this document. At the time of publication, the editions indicated were valid. 8 9 10 11 12 13 14 15 16 [2] 3GPP2 X.S0011-D v1.0, “cdma2000 Wireless IP Network Standard” [3] 3GPP2 X.S0013-002-B v1.0, “IP Multimedia Subsystem (IMS); Stage-2” [4] 3GPP2 X.S0013-003-B v1.0, “IP Multimedia (IM) session handling; IM call model” [5] 3GPP2 X.S0013-004-B v1.0, “IP Multimedia Call Control Protocol based on SIP and SDP; Stage-3” [6] 3GPP2 X.S0013-005-B v1.0, “IP Multimedia (IM) Subsystem Cx Interface; Signaling flows and message contents” [7] 3GPP2 X.S0013-006-B v1.0, “Cx Interface based on the Diameter protocol; Protocol details” [8] 3GPP2 X.S0013-007-A v1.0, “IP Multimedia Subsystem; Charging Architecture” [9] 3GPP2 X.S0013-008-A v1.0, “IP Multimedia Subsystem; Offline Accounting, Information Flows and Protocol” [10] 3GPP2 X.S0013-009-0 v1.0, “MMD Call Flow Examples” [11] 3GPP2 X.S0013-010-B v1.0, “IP Multimedia Subsystem (IMS) Sh Interface signaling flows and message contents” [12] 3GPP2 X.S0013-011-B v1.0, “Sh interface based on the Diameter protocol” [13] 3GPP2 X.S0013-012-0 v1.0, “Service Based Bearer Control – Stage 2” [14] 3GPP2 X.S0013-013-0 v1.0, “Service Based Bearer Control – Tx Interface Stage-3” [15] 3GPP2 X.S0013-014-0 v1.0, “Service Based Bearer Control – Ty Interface Stage 3” [16] 3GPP2 X.S0013-016-0 v1.0, “Messaging service using the IP Multimedia (IM) Subsystem (IMS)” 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 3.2 Informative References 46 47 48 [1] 3GPP2 S.R0037-0, “IP Network Architecture Model for cdma2000 Spread Spectrum Systems”, Version 3.0, August, 2003. 49 50 51 52 53 54 55 56 58 59 60 3 X.P0013-000-B v1.0 4 1 Terminology 2 3 This document uses the following “verbal forms” and “verbal form definitions”: a. b. c. “shall” and “shall not” identify items of interest that are to be strictly followed and from which no deviation is recommended, 4 5 6 7 “should” and “should not” indicate items of interest that are highly desirable and particularly suitable, without identifying or excluding other items; or (in the negative form) indicate items of interest that are not desirable, are not particularly suitable, or are not recommended but not prohibited, and 8 “may” and “may not” indicate items of interest that are optional but permissible within the limits of this recommendation. 13 9 10 11 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 4 X.P0013-000-B v1.0 1 2 5 Assumptions 3 4 a. 5 6 7 8 9 The architecture described in this document assumes the following protocols: I. SIP (Session Initiation Protocol), II. DIAMETER, and III. MOBILE IP. 10 11 b. The use, support, and interoperation of IPv4 and IPv6 in the All-IP network are currently assumed in this document. c. There are known bearer paths not shown in Figure 2 (e.g., bearer paths between the Application Servers and the Border Router, the Application Servers and the Media Resource Function Processor). Some of these interfaces are shown in additional diagrams in this document, but not numerically labeled, see Section 2. d. There are known signaling paths not shown in Figure 2 (e.g., signaling paths between two Call Session Control Function (CSCF), two AAA, an external SIP entity beyond the Border Router and the CSCF). Some of these interfaces are shown in additional diagrams in this document, but not numerically labeled, see Section 2. 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 5 X.P0013-000-B v1.0 6 1 Definitions 2 3 This section provides definitions of some terms used within this document. 4 5 6 6.1 7 Quality of Service (QoS) 8 9 QoS refers to a set of capabilities that a network may provide to a communications session. These capabilities can be specified so that particular applications (e.g., conversational voice, video, streaming audio) fulfill human factors or other requirements with respect to fidelity and performance. 10 11 12 13 14 6.2 Home Subscriber Server (HSS) 15 16 17 For the documents related to the IP Multimedia Subsystem (IMS) elements and the Sh and Cx interfaces (see “11/Sh” and “16/Cx” in Figures 2, 3, 4 and 6), the term “HSS” is used to represent the Home AAA entity plus the Databases to which it interfaces. When used to define interfaces, the term HSS implies interfaces to the AAA component of the collective. The functionalities of the HSS collective and its interfaces are solely defined by the MMD documents and their normative references. The use of this term does not imply the support of any additional functionality. Other functionalities and interfaces supported by the AAA and Databases (e.g., Packet Data Subsystem Authentication, Authorization, Accounting) defined in other documents are not changed by the use of the HSS term in the MMD series of documents. 18 19 20 21 22 23 24 25 26 27 Figure 1 shows the HSS collective. For the purposes of the IMS elements and interfaces, the AAA plus the Databases are equivalent to the HSS: 28 29 30 31 32 33 34 35 36 37 Databases 38 39 40 41 42 4 43 44 45 46 47 AAA 48 49 50 51 52 53 54 Figure 1 HSS Collective 55 56 58 59 60 6 X.P0013-000-B v1.0 1 2 7 Abbreviations 3 4 This section provides a definition of the abbreviations used within this recommendation, as: 5 AAA Authentication, Authorization, and Accounting AGW Access Gateway API Application Programming Interface AS Application Server BR Border Router BSC Base Station Controller BTS Base Transceiver System CSCF Call Session Control Function DB Database DSI Dynamic Subscriber Information EIR Equipment Identity Register FA Foreign Agent HA Home Agent I-CSCF Interrogating CSCF 28 HSS Home Subscriber Server 29 IMS IP Multimedia Subsystem IP Internet Protocol IPv4 Internet Protocol Version 4 34 IPv6 Internet Protocol Version 6 35 MGW Media Gateway MGCF Media Gateway Control Function MM Mobility Manager 40 MRFC Media Resource Function Controller 41 MRFP Media Resource Function Processor OSA Open Service Access OSF Operations Systems Function OSS Open Support System PCF Packet Control Function P-CSCF Proxy-CSCF PDE Position Determining Entity PDF Policy Decision Function PDS Packet Data Subsystem PSTN Public Switched Telephone Network QoS Quality of Service MMD Multimedia Domain 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 30 31 32 33 36 37 38 39 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 7 X.P0013-000-B v1.0 RNC Radio Network Controller SCS Service Capability Server S-CSCF Serving CSCF SIP Session Initiation Protocol 1 2 3 4 5 6 7 Table 1. Abbreviations 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 8 X.P0013-000-B v1.0 1 2 8 MMD Core Network Architecture 3 4 5 6 7 8 9 Figure 2 presents the core network entities and associated reference points that comprise the MMD (Multimedia Domain) of the wireless All-IP Network Architecture Model. The network entities are represented by squares and rectangles; the interfaces between network entities are reference points identified by numbers. Figure 2 includes several reference points that have dual labels. Either of these labels may be used in the documents relating to these reference points. Note: in Figure 2 the “MMD Core Network” is identified by the network elements and reference points highlighted in “blue”. 10 11 12 13 14 15 16 21 22 23 24 ... Databases 18 20 Policy Rules Subscription Profile DSI 17 19 OSA Application Server Network EIR 1 m3 2 3 10 11/Sh m4 27 OSF Element Management Layer Position Server 15 AAA 16/Cx 12/ISC Call Session Control Function 28 29 9/Mi Tx 17/Mg m1 18 19 20 21 22 5/Mk Breakout Gateway Control Function OSA Service Capability Server 11/ Sh 25 26 12/ISC 8/OSA-API 4 OSFNetwork Management Layer / OSS m2 SIP Application Server 24/Mr 49/Mj Policy and Charging Rules Function Ty 29 30 31 32 33 Media Resource Function Controller Position Determining Entity Managed Network Entity Media Gateway Control Function 25/Mp 34 26/PSTN 30/Mn 35 36 37 31 Access Gateway 32/Mb cdma2000 Access Network 38 35 39 37/Mb 36/Mb 40 FA / Attendant 41 41 42 Other Access Networks 43/Mb 43 44 45 48 Mobile IP Home Agent 33/Mb Media Gateway 38/Mb 40/Mb 42/Mb Border Router 44/Mb 45/Mb hh 47/Um 46/Mb 34/Mb 46 47 Media Resource Function Processor Mobile Station PSTN IP Network 49 50 51 52 Figure 2 MMD Core Network Architecture Model 53 54 55 56 58 The MMD of the All-IP Network offers both general packet data support and multi-media session capabilities. The multi-media session capabilities are built on top of the general packet data support capabilities. The general packet data capabilities may be deployed without the multi-media session capabilities. Some network entities are common to providing both capabilities. 59 60 9 X.P0013-000-B v1.0 Figure 3 shows the entities that comprise the general packet data support portion of the MMD core network. These are known collectively as the Packet Data Subsystem (PDS). Figure 3 includes several reference points that have dual labels. Either of these labels may be used in the documents relating to these reference points. Note: in Figure 3 the “Packet Data Subsystem” is identified by the network elements and reference points highlighted in “blue”. 1 2 3 4 5 6 7 8 9 10 OSA Application Server Network EIR Policy Rules Subscription Profile DSI ... Databases 1 m3 2 3 OSF Element Management Layer 12/ISC 8/OSA-API 4 12 13 14 5/Mk 10 11/Sh m4 OSA Service Capability Server 11/ Sh Position Server 15 AAA 16/Cx 12/ISC Call Session Control Function 18 19 20 21 22 16 Breakout Gateway Control Function 9/Mi Tx 17/Mg m1 11 15 OSFNetwork Management Layer / OSS m2 SIP Application Server 24/Mr 17 18 19 49/Mj 20 21 Policy and Charging Rules Function 22 23 24 Ty 29 25 26 Managed Network Entity Media Resource Function Controller Position Determining Entity Media Gateway Control Function 25/Mp 27 28 29 30 26/PSTN 30/Mn 31 Access Gateway 32/Mb cdma2000 Access Network 35 Media Resource Function Processor 37/Mb 36/Mb FA / Attendant 41 Other Access Networks 43/Mb 33/Mb 32 Media Gateway 33 34 38/Mb 35 40/Mb 36 Mobile IP Home Agent 42/Mb 37 Border Router 44/Mb 45/Mb 47/Um 31 38 39 46/Mb 34/Mb Mobile Station PSTN IP Network 40 41 42 43 44 45 46 47 Figure 3 Packet Data Subsystem Core Network Architecture Model 48 49 50 Figure 4 shows the entities that comprise the multimedia session capabilities of an All-IP network. These entities are known collectively as the IP Multimedia Subsystem (IMS). Figure 4 includes several reference points that have dual labels. Either of these labels may be used in the documents relating to these reference points. Note: in Figure 4 the “IP Multimedia Subsystem” is identified by the network elements and reference points highlighted in “blue”. 51 52 53 54 55 56 58 59 60 10 X.P0013-000-B v1.0 1 2 3 OSA Application Server Network EIR Policy Rules Subscription Profile DSI 4 ... Databases SIP Application Server 5 6 7 8 9 10 11 1 m3 2 3 OSFNetwork Management Layer / OSS m2 10 11/Sh m4 14 15 16 OSF Element Management Layer Position Server 15 AAA 16/Cx 12/ISC Call Session Control Function 9/Mi Tx 17/Mg m1 18 19 20 21 22 5/Mk Breakout Gateway Control Function OSA Service Capability Server 11/ Sh 12 13 12/ISC 8/OSA-API 4 24/Mr 49/Mj Policy and Charging Rules Function Ty 29 17 18 19 20 Managed Network Entity Media Resource Function Controller Position Determining Entity 21 Media Gateway Control Function 25/Mp 26/PSTN 22 30/Mn 23 24 31 25 Access Gateway 32/Mb cdma2000 Access Network 35 26 37/Mb 36/Mb 27 28 FA / Attendant 41 29 Other Access Networks 30 43/Mb 31 34 35 Mobile IP Home Agent 33/Mb Media Gateway 38/Mb 40/Mb 42/Mb Border Router 44/Mb 45/Mb hh 32 33 Media Resource Function Processor 47/Um 46/Mb 34/Mb Mobile Station PSTN IP Network 36 37 38 39 Figure 4 IMS Core Network Architecture Model 40 41 42 43 44 45 46 The session control functions within the IMS are logically interconnected in various ways in the session scenarios. Figure 5 identifies the reference points within the IMS between these session control entities. In many cases there are dual labels for these reference points either of which may be used in the applicable documents. The Breakout Gateway Control Function (BGCF) and the Media Gateway Control Function (MGCF) may be in any network (i.e., home, visited, 3rd party). 47 48 49 50 51 52 53 54 55 56 58 59 60 11 X.P0013-000-B v1.0 1 Home or Visited Network 2 Home Network Only 3 4 IP Multimedia Client (Proxy) Session Control Manager hh/Gm (Interrogating) Session ff/ Control Mw Manager dd/Mw (Serving) Session Control Manager 5 6 7 8 9 10 17/Mg 9/Mi 11 12 13 Media Gateway Control Function 49/Mj Breakout Gateway Control Function 5/Mk Breakout Gateway Control Function 14 15 16 17 18 19 20 21 Figure 5 Session Control Reference Model 22 23 In addition to the PDS and IMS there is also a collection of entities that provide specific service capabilities for the MMD (e.g., geo-location capabilities, presence capabilities). These entities comprise the service capability. Figure 6 shows the entities that comprise the service capability subsystem portion of the MMD. Figure 6 identifies the reference points within the MMD service capability subsystem between these session control entities. In many cases there are dual labels for these reference points either of which may be used in the applicable documents. 24 25 26 27 28 29 30 31 32 SIP Application Server Application Server 33 [Control and Content] [Content only] 34 Type A Type B Type C Service Application Service Application Service Application OSA Application Server [Control and Content] 8/OSA-API 11/Sh 35 36 37 38 39 12/ISC 40 41 42 OSA Service Capability Server 10 Databases 4 12/ISC 43 44 45 46 11/Sh 47 48 Position Server 15 AAA 16/Cx Call Session Control Function 49 50 51 52 53 Figure 6 Multimedia Application Server Control Plane 54 55 56 The Application Server (AS) interfaces offer applications access to a range of network capabilities and information in two categories, Open Service Access (OSA) based AS and SIP based Application 58 59 60 12 X.P0013-000-B v1.0 Servers. The Application Programming Interface (API) to be used on Reference Point 8 is a standard interface between the Application Server and the OSA Service Capability Server (OSA SCS). 1 2 3 4 5 8.1 6 Each network entity may be a physical device, it may form part of a physical device, or it may be distributed over a number of physical devices. The Network Entities are identified in [1] and detailed description of the functions and procedures provided by these Network Entities is provided in the documents listed in Section 3. 7 8 9 10 11 12 13 14 15 16 17 18 Network Entities 8.2 Reference Points An interface exists when two Network Entities are interconnected through exactly one signaling or bearer stream Reference Point. Reference Points identify that a logical relationship exists between two Network Entities. An interface is defined across a specific Reference Point by defining the protocol and data exchanged between the entities. Zero, one or more interfaces may be defined for each reference point in the MMD. The Reference Points are identified in [1]. 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 13 X.P0013-000-B v1.0 9 Documents for the core network packet data subsystem 1 2 3 4 5 The MMD is specified by a series of documents of which this document provides an overview. The Packet Data Subsystem is specified in [2]. 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 14 X.P0013-000-B v1.0 1 2 3 4 10 Documents for the core network IP Multimedia subsystem 5 6 7 8 9 The MMD is specified by a series of documents of which this document, Part 0, provides an overview. The following documents comprise the Core Network IP Multimedia Subsystem (IMS) and, in this release, address reference point’s 5/Mk, 9/Mi, 11/Sh, 12/ISC, 16/Cx, 17/Mg, 24/Mr, 49/Mj, dd/Mw, ff/Mw, hh/Gm, Mb, ii, Tx and Ty, which are shown in the reference model. 10 11 a. IP Multimedia Subsystem (IMS); Stage-2 [3]: This document includes functional entity actions and information flows for the entities and interfaces that comprise the IMS. b. IP Multimedia (IM) session handling; IM call model [4]: This document covers the call model to be supported by SIP session control functional entities, c. IP Multimedia Call Control Protocol based on SIP and SDP; Stage-3 [5]: This document specifies the Stage-3 for the SIP based interfaces of IMS. d. IP Multimedia (IM) Subsystem Cx Interface; Signaling flows and message contents [6]: This document specifies detailed Stage-2 for interface 16/Cx, e. Cx Interface based on the Diameter protocol; Protocol details [7]: This document specifies Stage-3 for interface 16/Cx, f. IP Multimedia Subsystem; Charging Architecture [8]: This document specifies the architecture for off-line and on-line accounting functions, and g. IP Multimedia Subsystem: Offline Accounting, Information Flows and Protocol [9]: This document specifies detailed Stage-2 and Stage-3 for the IMS Accounting interfaces. h. MMD Call Flow Examples [10]: This document specifies detailed Stage-2 and Stage-3 for the IMS Accounting interfaces. i. Service Based Bearer Control – Stage 2 [13]: This document specifies Stage-2 for interfaces Tx and Ty. j. Service Based Bearer Control – Tx Interface Stage-3 [14]: This document specifies Stage-3 for interface Tx. k. Service Based Bearer Control – Ty Interface Stage-3 [15]: This document specifies Stage-3 for interface Ty. l. Messaging service using the IP Multimedia (IM) Subsystem (IMS) [16]: This document provides the protocol details for the messaging service within the IP Multimedia Subsystem (IMS) based on the Session Initiation Protocol (SIP), the Session Description Protocol (SDP) and, the Message Session Relay Protocol (MSRP). 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 15 X.P0013-000-B v1.0 11 Documents for the core network service capability subsystem 1 2 3 4 5 The MMD is specified by a series of documents of which this document provides an overview. The following documents comprise the Core Network Service Capabilities Subsystem (SCS) and, in this release, address reference point 11/Sh. a. IP Multimedia Subsystem (IMS) Sh Interface signaling flows and message contents [11]: This document specifies detailed Stage-2 for interface 11/Sh. b. Sh interface based on the Diameter protocol [12]: 6 7 8 9 10 11 12 13 14 15 This document specifies Stage-3 for interface 11/Sh. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 58 59 60 16