Service Control Using SIP in 3GPP’s IP Multimedia Subsystem (IMS) Xin Chen

Service Control Using SIP in 3GPP’s IP Multimedia

Subsystem (IMS)

Xin ChenFujitsu Laboratories of Europe LTD

[email protected]

© Copyright Fujitsu Laboratories of Europe Limited. All rights reserved2

ContentsContents

Part 1. IMS OverviewPart 2. IMS Service ArchitecturePart 3. IMS Service ControlPart 4. Service ExamplesPart 5. Future workPart 6. Conclusion


IMS OverviewIMS Overview

Part 1. IMS OverviewPart 2. IMS Service ArchitecturePart 3. IMS Service ControlPart 4. Service ExamplePart 5. Future workPart 6. Conclusion


IMS Overview (1) – IMS ArchitectrureIMS Overview (1) – IMS Architectrure

IMS Architecture

Out/In Bound Proxy

Visited Network

Entry Proxy Service Proxy

Service Platform

HomeNetwork

IMS User

To/From terminating network

SIP Signaling InterfaceService Control InterfaceDiameter Interface

Service

Profile

ISC

ISC: IMS Service Control

P-CSCF I-CSCF S-CSCF


IMS Overview (2)-Some important factsIMS Overview (2)-Some important facts

IMS is a combination of network and services

IMS provider also owns the service platform

One time registration by Service Proxy

Service Proxy is in the home IMS network

Service control is done in the home IMS network


ContentsContents



IMS Service Architecture (1)-- RequirementsIMS Service Architecture (1)-- Requirements

Distributed Services Architecture Support third party applications Deliver combined, advance services (VoIP, IM, Presence…) Maximise the network performance Support service customisation Support Legacy services (number translation, pre-paid…)


IMS Service Architecture (2)— OverviewIMS Service Architecture (2)— Overview

Service Proxy

SIP Application

ServerOSA

Gateway

IM-SSF

Visited Network

Intelligent Network

SIP signaling interfaceService control Interface (SIP)

Third Party Application

Open Service Interface

SIP

ISC Interface based on SIP

ISC: IMS Service ControlOSA: Open Service AccessIM-SSF: IP Multimedia Service Switch Function

HomeNetwork


IMS Service Architecture (3)—ISC InterfaceIMS Service Architecture (3)—ISC Interface

The roles of ISC interface: Service invocation Present SIP parameters to applications Interact with Service Proxy for service provisioning

Why SIP Service invocation is free of basic call model Service is transparent for the Service Proxy No additional development needed, purely a SIP proxy All SIP parameters are presented to applications Easy to integrate new services (standardised ISC interface) Maximise the application capabilities (user agent, proxy server, B2BUA)


ContentsContents



IMS Service Control (1)—Service Invocation and InteractionIMS Service Control (1)—Service Invocation and Interaction

Service triggers on initial SIP requests at Service Proxy Service Proxy proxies request to corresponding AS based on triggers AS acts as user agents, proxy server, 3PCC or B2BUA AS may Record-Route SIP request to stay in signalling path Service Proxy maintains the states between dialogs sent to/from

applications

Service Proxy

SIP Initial Request Triggered!

AS

SIP

Initia

l Re

q

SIP

Re

qu

es

t

SIP Request


IMS Service Control (2)—Service TriggersIMS Service Control (2)—Service Triggers

Service Point Triggers (SPTs) are those points in the SIP signalling on which Filter Criteria can be set.

SIP methods (e.g. REGISTER, INVITE, SUBSCRIBE, MESSAGE); presence or absence of any header; content of any header; direction of the request session description information (SDP). Initial Filter criteria (iFC) (described using XML) address of the Application Server to be contacted; Trigger Point: combination of SPTs by means of logical expressions (AND,

OR,NOT, etc.); priority of the iFC (in case SPTs trigger multiple iFCs); Default handling (either reject or proxy the request);


ContentsContents



Service Example (1) —Single Application Server case Service Example (1) —Single Application Server case

Initial Filter Criteria of Presence Server

Application Server Address: presence.operator.com

Trigger point:

Event=“presence” AND Method = PUBLISH AND Request-URI= “sip:[email protected]”

Handling: Proxy

Priority: x

Example 1: Single application server triggering

1. PUBLISH

3.

PU

BL

ISH

Service Proxy

Presence Server

Sip: [email protected]

2. Filter Evaluation

4.2

00

OK

5. 200 OK


Service Examples (2) —Multiple Application Server caseService Examples (2) —Multiple Application Server case

Example 2: Multiple application servers triggering

Initial Filter Criteria of Prepaid Server

Application Server Address: prepaid.operator.com

Trigger point:

Method = MESSAGE OR INVITE AND From= “sip:[email protected]”

Handling: Proxy

Priority: 1

1. MESSAGE3

. M

ES

SA

GE

Service Proxy

Prepaid Server

Sip: [email protected]


Messaging Server

Initial Filter Criteria of Messaging Server

Application Server Address: message.operator.com

Trigger point:

Method = MESSAGE

Handling: Proxy

Priority: 2

4.

ME

SS

AG

E


6. M

ESSAGE

7. M

ESSAGE

8. MESSAGE


Service Example (3)—Service InteractionsService Example (3)—Service Interactions

Service Proxy

Messaging Server

Presence Server

1. PUBLISH

2. P

UBLISH

11. MESSAGE4

. M

ES

SA

GE

5.

SU

BS

CR

IBE

7. S

UBSCRIBE

8. N

OTI

FY

9.

NO

TIF

Y

10

. M

ES

SA

GE

3. MESSAGE

Example 3: Service interactions

Initial Filter Criteria of Presence Server

Application Server Address: presence.operator.com

Trigger point:

Event=“presence” AND Method = SUBSCRIBE AND Request-URI=“sip:[email protected]”

Handling: Proxy

Priority: x6. Filter Evaluation


ContentsContents



Future WorkFuture Work

Dynamic trigger points assignment (Subsequent Filter Criteria)

Service Proxy

SIP Initial Request Triggered!

AS1

SIP

Initia

l Re

q

sFC installed!

SIP Message with sFC (New header or in

body?)

SIP Message

Further study service interactions in multiple application server environment. Evaluate other alternatives for IMS service control (etc. SOAP)


ContentsContents



Conclusion– Do we meet the requirements?Conclusion– Do we meet the requirements?

Distributed Services Architecture

Support third party applications

Deliver combined, advance services

Maximise the network performance

Support service customisation

Support Legacy services

Standardised ISC interface!

Open service interface!

Using SIP for service control!

Application server is supper box!

Static and dynamic service filtering!

SIP to BSCM mapping!

Done!

Done!

Done!

Done!

Done!

Done!


Thank you!


Date post:	23-Jan-2016
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Service Control Using SIP in 3GPP’s IP Multimedia Subsystem (IMS) Xin Chen

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