01 Ims Overview 34 2t6j44

IMS Overview

Contents     

IMS Background IMS Network Architecture Addresses in IMS and their identification approaches IMS Service Mode Typical IMS Networking Solutions

Traditional Telecom Carriers Face Evolution  e-Business Perspective

Current Status

Near Future

Internet’s impact and pervasion on the Telecom

Independent networks results in expensive maintenance cost Long development cycle of traditional service

Transform

Fierce competition of telecom industry

Business mode integrates with Internet Operation&maintenance mode cored by customers Multiple networks melts in Standardize network service capability and open to the third party

Ideal Architecture to Integrate Telecom and Internet Abundant activists become the main purchasing power of new service Great cohesion and enlargement effect helps new service promotion Great service innovation power

Internet

Competition Play Integration

Integration of Internet and Telecom completes and develops the industrial chain

Telecom Industry

Clear IMS network architecture enriches service openness capacity IMS provides the third party with telecom service ability through service development environment , which could create more abundant applications, and finally Telecom is everywhere

Carries transforms from service-driven mode to channel provisioning mode

IMS Application in the International Market So far, IMS draws attention of more and more carriers and appears in the NGN architecture more oftenly.

French Telecom

AT&T

•IMS realizes the NExT strategy

•IMS plays the most important part in the AT&T NGN CARTS architecture

•FT plan uses IMS to realize FMC integration

BT •BT treats IMS as the core network technique in the 21CN plan and s Web2.0 service

Speed up IMS Business Application all Around the World BT 2008Q1Business use Vodafone 2008Business use FT 2007Q2 Business use

★★ ★ ★ ★ ★ DT 2007Q3 Business use ★

Comcast 2008Q4Business use

Etisalat 2008Q2Business use TM 2009Q1Business use SingTel MTN 2008Q4Business use 2008Q4Business use

★★ ★ Verizon

AT&T 2007 Business 2007Business use use

★

★

★

There are more than 200 IMS sites all round the world. In 2008, speed up the IMS business use，over 60% sites begin business operation.

Oversea Carriers’ IMS Business Use Case Main Services： • • • •

VoBB IP Centrex VT UC

Main Services： • VoBB • ICS application • FMC integration service

Development: • 2006 start • 2007 VoBBBusiness use • 2008-2010 deploy the FMC service

Development: • 2008Q1 start • 2009Q1 VoBBBusiness use • 2009Q2 IP CentrexBusiness use

Main Services： VoBB • RCS • IPTV service

IMS

Development: • 2007 VoBBBusiness use • 2008 Sep IPTV business use in 25 cities

Main Services： • VoBB • Integrate Centrex PBX • RCS(Rich Communication Service) • IMS-based IPTV

Development: 2007 VoBB business use • 2008 Centrex, PBX business use • 2008 10 million line PSTN reconstruction • 2008 IPTV business use

Enter into IMS business application stage， its maturity is yet to be verified by the market

Related IMS Standardization Institutions

Mature IMS Technique Standards CSI

VCC

Presence

Cellular Access to IMS

GLMS

PoC

Messaging

IP

Multimedia Telephony

Multimedia Telephony

Wireline Access to IMS

WLAN Access to IMS

Mobile 

Residential

IMS R6 is terminated in 2005，R7 is terminated in 2006，R8 is terminated in 2008

Contents     

IMS Background IMS Network Architecture Addresses in IMS and their identification approaches IMS Service Mode Typical IMS Networking Solutions

What is IMS? 

IMS：IP Multimedia Subsystem



IP =





IP-based transmission



IP-based session control



IP-based service implementation

Multimedia = 





Combination of voice, video, image and text, etc multiple access approaches, varied access approaches and terminals with varied capacities

Subsystem = 





Rely on existing network technique and devices, reuse the existing network system to the largest extent Wireless network regards PS/GPRS network as the bearer network Fixed network regards the IP system based on fixed access as the bearer network



IMS（IP Multimedia SubsystemIMS), introduced at R5 phase by 3GPP, relays on the PS domain. IMS provides mobile s with muli-media services based on fullIP network

3GPP R9 -Improved version of R8

3GPP R5

3GPP R99 -CN: TDM

3GPP R4 - CN: MSC Server & MGW

- CN: IMS subsystem and abundant related NEs

3GPP R6 - IMS QoS, Billing, FMC, etc.

TISPAN R1 -- NGN/FMC etc.

2000/03

2001/03

2002/03

2005/12

3GPP R7 - Improved version of R6

3GPP R8 -RCS,SC,S R,VCC

TISPAN R2 -NASS/RACS, etc.

2006/X

2008/06

2009/06

Primary IMS Features Home network implements call control and service control, which ensures consistence of service provisioning, helps expansion of private service, in this way, the home carriers will try to offers more attractive services multimobile/fixed access approaches, which brings convenience for all service operation

Access Independent

Home Location Control

Primary IMS Features

Service Provision Service and control are independent for the convenience of flexible and prompt service provisioning and service integration, and finally implement open service provisioning mode

Security Mechanism Unified •Several security access mechanism coPolicy existence transforms to Fully IMS mechanism Control •Deploy signaling protection mechanism Unified QoS and between security domains charging policy •Deploy network topology concealment control mechanism mechanism

IMS System Architecture Service Network AS provides various value-added services. So far, there are 3 service provisioning approaches: SIP-AS provisioning, Parlay gateway provisioning and S provisioning

Service Layer

Application

IM-SSF

SIP AS

(SIP/OSA AS,CAMEL SE)

OSASCS AS

ISC

Control Layer

BGCF

HSS

IMS core network IMS Data Made up by P/I/SHLR/AuC(CS/PS) CSCFNE, SLF/HSS, BGCF and MRFC/MRFP, mainly implement IMS management, interworking between networks andPOTS service AG triggering.

S-CSCF

I-CSCF MGCF

SLF

P-CSCF

CSCF SGW

AGCF

CS Networks (PSTN/SS, PLMN)

MRFC MRFP PDF

Interworking domain Covers SGW, MGCF/MGW applied in the traditional PSTN, PLMN networks interworking in the service domain

IMMGW

NASS

Bearer Layer UE

UE

RAN

RAN

PDSN

SGSN

WAG/ AGW GGSN

SBC

BAS Fixed access

Wimax/WiFi

UE UE

IP-CAN network IP interworking network provides IP access bearer. The IP network can be any network, including CDMA PS domain, WCDMA PS domain, WIMAX, WIFI and fixed broadband access

Logical IMS Entity Classification Session Control and Route

  

P-CSCF S-CSCF I-CSCF

Data Management Authentication

 

HSS SLF

Media Resource （MRF）

 

MRFC MRFP

Service Control



AS

Interworking Function

  

Logical architecture of IMS NE functions can be configured together based on actual deployment needs

MGCF BGCF MGW

IMS Logical Function NE 





Proxy (P)-CSCF： 

First connection point from UE to the network



Establish security alliance between P-SCSCF and terminal



PDF function: implement authorized bearer resource and QoS management based on service SDP



SIP header compression



Bearer, control binding and enable/disable of QoS resource

HSS

S-CSCF S-CSCF

Interrogating (I)-CSCF： 

External point of the IMS system



THIG function is to hide interior topological information of the IMS network



S-CSCF distribution function



Positioning function of called S-CSCF

S-CSCF

I-CSCF

Serving (S)-CSCF： 

’s Registrar: responsible for ’s registration



Responsible for ’s authentication and authorization



Responsible for service control and triggering, and interact with the service layer

P-CSCF

IMS Logical Function NE 

HSS: (Home Subscriber Server) 





Save subscription data of IMS s, Service Profile, location information and authentication information Provide traditional HLR function, including CS/PS contract data

AS

HSS HSS Centralized Databases AAA, Profiles, …

S-CSCF

Interface：Diameter(IMS)、MAP(CS/PS) S-CSCF



SLF：(Subscription Locator Function) 

Position HSS based on SIP URI



Invoke it when visiting HSS



No need of SLF in single HSS environment

I-CSCF

IMS Logical Function NE 



MRFC: (Multimedia Resource Function Control) 

Interior media control resource function in the IMS domain



Maintain and control media resources in MRFP：H.248



Interwork with S-CSCF and receive AS control indirectly

MRFP: (Multimedia Resource Function Processor ) media resource function 

Interior media resource function in the IMS domain



Receive MRFC control：H.248



Provide vocoder, notice tone and conference bridge

IMS App IMS App IMS App

S-CSCF

MRFC

MRFP MRFP MRFP Access Network

Equipment (UE)

IMS Logical Function NE 





BGCF: (Breakout Gateway Control Function) 

Select proper outlet for the outgoing call from the IMS network



Select a MGCF in local network if the callee and IMS are in an identical network



Handle to BGCF of another network interface if called does not belong to local network



Maintain or visit topology information of network interface and exit policy database

S-CSCF

BGCF

SIP

MGCF

MGCF: (Media Gateway Control Function) 

Interworking point of IMS control and traditional PSTN/CS network



Control IMS-MGW to finish interworking of the media ：H.248



IMS end：interwork with I/S-CSCF

H.248



PSTN/CS end：protocol switching from SIP to BICC/ISUP protocol

Media Gateway SG

IM-MGW: (IMS Media Gateway) 

Interworking point of IMS media and traditional PSTN/CS network



Receive control from MGCF：H.248



Provide vocoder, echo elimination, notice tone, DTMF and conference bridge

I-CSCF

MGC

SS7

PLMN|PSTN TDM PBX

IMS Logic Function NE 

S-CSCF implements the triggered IMS services  Service triggering implements dynamic service trigger through iFC mechanism  After completing service logic, AS returns the request to S-CSCF for future triggering

Initial Filter Criteria (iFC) at Registration Application Server

Application Server

Application Server

HSS XML iFC

Incoming Messages

SIP

S P T

SIP

F

SIP

XML sFC

F Originating or Terminating Filters

S-CSCF

Filter Criteria

SIP

F

R o u t i n g

SIP

Outgoing Messages

Other Logic Function NEs in IMS 

SBC: Session Border Control 



It locates at the boundary of IMS core network. As a signaling proxy and a media proxy of the IMS network, it is responsible for separating the access network and the IMS core network. Through SBC, interoperating between public network and private network, NAT traversal, firewall traversal, QoS control and network security could be realized.

DNS、ENUM Server： 

DNS (Domain Name System)：The server is responsible for the analysis of URL address and IP address by seeking help from the internet DNS server or creating a DNS server within the network.



ENUM (E.164 Number URI Mapping) server is responsible for transforming telephone numbers to URL.

Other Logic Function NEs in IMS 

AGCF: Access GateWay Control Function 

It controls the premises gateway and the access media gateway by using the H.248 protocol to conduct transformations between SIP/SIP-I and H.248 protocol.



AGCF does not implement any services. The basic call service is implemented in S-CSCF; the supplementary services and the value-added services are implemented in service application layer. Thus AGCF, similar to P-CSCF, is only a network accessing point.

Contents     

IMS Background IMS Network Architecture Addresses in IMS and Their Identification Approaches IMS Service Mode Typical IMS Networking Solution

Address and Identity    

Private Identity (PVI) Public Identity (PUI) Relation Between PUI and PVI Network Node No.

Private Identity (PVI) 

PVI：Every in IMS has one or more than one private identity (IMPI), or PVI. It is assigned by the operator of the network to which the belongs. PVI is used to , authenticate, manage and charge. 





PVI is only used to identify a subscription in home network instead of an Format：NAI, for example, name@domain_name

For example，Xiaoming’s PVI： 1. 2.

[email protected]

Public Identity (PUI) 

PUI： Every in IMS has one or more than one public identity (IMPU), or PUI. uses it as a request to communicate with other s, so PUI could be made public.  



PUI is used by an to communicate with other s Format：SIP URI，TEL URI

For example, Xiaoming’s PUI： 1. 2. 3.

sip:[email protected] tel:+8613912345678

Relation Between PUI and PVI 

Relation Between PUI and PVI Public Identity 1 (SIP URI format) Private Identity 1 (For Mobile terminals)

Public Identity 2 (Tel E.164 format)

Service Profile 1 (Enhanced Services) Implicitly ed ID set 1

Public Identity 3 (SIP URI format) Public Identity 4 (Tel E.164 format) Private Identity 2 (For Fixed terminals)

Public Identity 5 (SIP URI format) Public Identity 6 (Tel E.164 format)

One PVI could match several PUI： One phone, more than one number

Implicitly ed ID set 2

Several PVI share one PUI： One number, several 27 phones; number sharing.

Service Profile 2 (Legacy Services)

Service Profile 3 (Converged Services)

Service Profile 4 (Enhanced Services) Implicitly ed ID set 3

Implicit registration： several PUI

Service Profile 5 (Legacy Services)

PUI corresponds to service configuration

Network Node No. 

Locating at the boundary of SIP domain and CS domain, MGCF/IM-MGW has two equipment identities:  



Host name or domain name SS7 signaling point code

For example： Domain name: Mgcf. jiangsu.ctcims.com xxx-yyy-001 IMMGW. jiangsu.ctcims.com xxx-yyy-002

Contents     

IMS Background IMS Network Architecture Addresses in IMS and Their Identification Approaches IMS Service Mode Typical IMS Networking Solution

IMS Service Provision Mode ISC – IMS Service Control SCIM – Service Capability Interaction Manager OSA – Open Service Architecture SCS – Service Capability Server IM-SSF – IP Multimedia Service Switching Function

SIP AS AS

AS OSA Service Capability Server (SCS)

SCIM Sh (Diameter)

OSA API

OSA-AS

ISC (SIP) ISC (SIP)

HSS

S-CSCF Cx (Diameter)



IMS defines the standard SIPbased ISC interface and separates the service layer completely from the control layer.



IMS s three service offering modes, namely:

Mr (SIP) Mp (H.248)

ISC (SIP) Si

MRFC

MRFP

MAP

IM-SSF



SIP AS



OSA SCS



IM-SSF

CAP

CSE

The Domestic Network is Responsible for the Service Control －Offering Consistent Communication Experience

IMS Service Trigger Mechanism Sh

HSS

Cx

AS 1

SIP Interface

ISC

Incoming Call leg

1

S P I

2

Sh

3

SIP message possibly with modification by AS1

S-CSCF triggers services through iFC；



The processing mode of SCSCF is independent of services, through which, the components of S-CSCF could be shared and reused by many services；



S-CSCF analyzes the request from the terminal according to the service triggering point and triggers the corresponding application server which then will complete the service logic process；



S-CSCF only triggers services; it no longer processes service logic.

AS 2 SIP Interface

Service Logic



4.a

INVITE Match Initial Filter Criteria

ISC

Service Logic

5a

SIP me ssage possibly with modification by AS2

Outgoing Call leg

S - CSCF

Filter Criteria X AS1 Filter Criteria Y AS2 6a 4.b SIP message forwarded by S - CSCF

SIP message forwarded by S - CSCF

iFC Triggering Mechanism －Separate Call Control From Service Logic

Contents     

IMS Background IMS Network Architecture Addresses in IMS and Their Identification Approaches IMS Service Mode Typical IMS Networking Solution

Object Architecture of the ZIMS Zhimei Solution Unified OSS/BSS

Rich Services

VOIP

Multimedia Telephone

IM/PS/GM

MRBT/MRAT

Convergent Centrex

Enhanced Phone Book …

Office Collaborate

Multimedia Conference

File Transfer

Web Call

X-sharing

Service Continuity

PROVISIONING

IP Network HSS/HLR

PORTAL SELF-CARE

Converged

I-CSCF

MRF IBGF

MGCF

MGW/SGW

PSTN

S-CSCF

Core

BGCF

AGCF/mAGCF

IBCF

P/E-CSCF

PLMN

PCRF/PDF/SPDF/A-RACF/DPIC

EMS/NMS

AG

Various Accesses CCF/CDF/CGF/OCS

Multimedia Terminals

TDM Access

SBC xPON

xDSL

AGW LAN/Wi-Fi

WiMAX

GGSN WCDMA/GPRS/ TD-SCDMA

PDSN

SAE-GW/ePDG

EV-DO

LTE