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Service Control Using SIP in 3GPP’s IP Multimedia Subsystem (IMS) Xin Chen Fujitsu Laboratories of Europe LTD x.chen@fle.fujitsu.com. 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.
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Service Control Using SIP in 3GPP’s IP Multimedia Subsystem (IMS) Xin Chen Fujitsu Laboratories of Europe LTD x.chen@fle.fujitsu.com
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 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 IMS Overview
IMS Overview (1) – IMS Architectrure • IMS Architecture SIP Signaling Interface Service Control Interface Service Platform Diameter Interface ISC: IMS Service Control ISC I-CSCF S-CSCF P-CSCF Out/In Bound Proxy Service Proxy Entry Proxy Service Profile To/From terminating network IMS User Visited Network Home Network
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 IMS Overview (2)-Some important facts
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 Contents
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…)
IMS Service Architecture (2)— Overview Third Party Application ISC Interface based on SIP Intelligent Network Open Service Interface SIP Application Server SIP signaling interface Service control Interface (SIP) IM-SSF OSA Gateway ISC: IMS Service Control OSA: Open Service Access IM-SSF: IP Multimedia Service Switch Function Visited Network Home Network SIP Service Proxy
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) IMS Service Architecture (3)—ISC Interface
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 Contents
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 IMS Service Control (1)—Service Invocation and Interaction AS SIP Initial Req SIP Request Service Proxy SIP Initial Request SIP Request Triggered!
IMS 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);
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 Contents
3. PUBLISH 4.200 OK 1. PUBLISH 5. 200 OK Service Example (1) —Single Application Server case Example 1: Single application server triggering Presence Server 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 Sip: christelle@fujitsu.com 2. Filter Evaluation Service Proxy
3. MESSAGE 4. MESSAGE 6. MESSAGE 7. MESSAGE 1. MESSAGE 8. MESSAGE Service Examples (2) —Multiple Application Server case Example 2: Multiple application servers triggering Messaging Server Prepaid Server 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 Initial Filter Criteria of Messaging Server Application Server Address: message.operator.com Trigger point: Method = MESSAGE Handling: Proxy Priority: 2 2. Filter Evaluation 5. Filter Evaluation Service Proxy Sip: christelle@fujitsu.com
2. PUBLISH 6. Filter Evaluation 1. PUBLISH Service Example (3)—Service Interactions Example 3: Service interactions Presence Server Messaging Server 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 8. NOTIFY 7. SUBSCRIBE 10. MESSAGE 9. NOTIFY 4. MESSAGE 5. SUBSCRIBE 3. MESSAGE 11. MESSAGE Service Proxy
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 Contents
Dynamic trigger points assignment (Subsequent Filter Criteria) Future Work AS1 SIP Message with sFC (New header or in body?) SIP Initial Req Service Proxy sFC installed! SIP Initial Request SIP Message Triggered! • Further study service interactions in multiple application server environment. • Evaluate other alternatives for IMS service control (etc. SOAP)
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 Contents
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! Done! Open service interface! Done! Using SIP for service control! Done! Application server is supper box! Done! Static and dynamic service filtering! Done! SIP to BSCM mapping! Done!