1. Service Control Using SIP in 3GPP’s IP Multimedia Subsystem (IMS) Xin Chen Fujitsu Laboratories of Europe LTD x.chen@fle.fujitsu.com

2. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 2 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Examples Part 5. Future work Part 6. Conclusion

3. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 3 IMS Overview Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

4. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 4 IMS Overview (1) – IMS Architectrure  IMS Architecture Out/In Bound Proxy Visited Network Entry Proxy Service Proxy Service Platform Home Network IMS User To/From terminating network SIP Signaling Interface Service Control Interface Diameter Interface Service Profile ISC ISC: IMS Service Control P-CSCF I-CSCFS-CSCF

5. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 5 IMS 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

6. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 6 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

7. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 7 IMS 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…)

8. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 8 IMS Service Architecture (2) — Overview Service Proxy SIP Application Server OSA Gateway IM-SSF Visited Network Intelligent Network SIP signaling interface Service control Interface (SIP) Third Party Application Open Service Interface SIP ISC Interface based on SIP ISC: IMS Service Control OSA: Open Service Access IM-SSF: IP Multimedia Service Switch Function Home Network

9. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 9 IMS 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)

10. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 10 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

11. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 11 IMS 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 Initial Req SIP Request

12. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 12 IMS Service Control (2) — Service Triggers l 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). l 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);

13. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 13 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

14. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 14 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:christelle@fujitsu.com ” Handling: Proxy Priority: x Example 1: Single application server triggering 1. PUBLISH 3. PUBLISH Service Proxy Presence Server Sip: christelle@fujitsu.com 2. Filter Evaluation 4.200 OK 5. 200 OK

15. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 15 Service 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:christelle@fujitsu.com ” Handling: Proxy Priority: 1 1. MESSAGE 3. MESSAGE Service Proxy Prepaid Server Sip: christelle@fujitsu.com 2. Filter Evaluation Messaging Server Initial Filter Criteria of Messaging Server Application Server Address: message.operator.com Trigger point: Method = MESSAGE Handling: Proxy Priority: 2 4. MESSAGE 5. Filter Evaluation 6. MESSAGE7. MESSAGE 8. MESSAGE

16. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 16 Service Example (3) — Service Interactions Service Proxy Messaging Server Presence Server 1. PUBLISH 2. PUBLISH 11. MESSAGE 4. MESSAGE5. SUBSCRIBE 7. SUBSCRIBE 8. NOTIFY 9. NOTIFY 10. MESSAGE 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:christelle@fujitsu.com” Handling: Proxy Priority: x 6. Filter Evaluation

17. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 17 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

18. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 18 Future Work  Dynamic trigger points assignment (Subsequent Filter Criteria) Service Proxy SIP Initial Request Triggered! AS1 SIP Initial Req 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)

19. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 19 Contents Part 1. IMS Overview Part 2. IMS Service Architecture Part 3. IMS Service Control Part 4. Service Example Part 5. Future work Part 6. Conclusion

20. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 20 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!

21. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 21 Thank you!

22. © Copyright Fujitsu Laboratories of Europe Limited. All rights reserved 22