2. Click to edit Master title style Click to edit Master subtitle style IP Multimedia Subsystem (IMS) Emergency Services Christian Militeau Director, IEN Services Development ESIF 16 - January 2006

3. 2 Objectives Highlight Current Standards Activity Present an Overview of IMS Architecture Define IMS Core Network Elements Illustrate Registration and Call Flow Present an Overview of IMS in the context of Emergency Services

4. 3 Where does IMS come from? In Wireline there has been a long term move towards a Voice over Packet (VoIP) replacement for the PSTN Drivers have always been to reduce OPEX in fixed line networks by optimising bandwidth usage, and replacing outdated TDM switching fabric –Compressed speech into less than 64kbps channels (G Standards) –Further optimisation using VAD, Silence Suppression, ATM AAL2 or IP multiplexing yields significant reduction in core network bandwidth requirements. Drivers in 3GPP for Wireless are more service related –IMS is born out of a need for ‘feature rich’ services –Bandwidth requirements and their impact on capacity for the Radio interface (GSM, GPRS, 3G). IMS provides the final piece in the business case for the NGN

5. 4 IMS-Related Standards Initiatives

6. 5 IMS Releases

7. 6 What is IMS? An Industry Standard Service Architecture (SA) and Core Network (CN) architecture An IP Multimedia Services Architecture Defined with Open Standards from 3GPP and ETSI Based on IETF Protocols (SIP, RTP, RTSP, COPS, DIAMETER, etc.) Designed for both Wireless and Wireline Networks and for Fixed and Mobile Convergence (FMC) A Solution for Service Transparency Capable of Interworking with PSTN (i.e. legacy IN-based services) CSCF – Call Session Control Function HSS – Home Subscriber Server Access & Transport Plane Core Network Session Control Plane Service Architecture Applications/Services Plane HSS CSCF Access Network Other Networks Web Portal ApplicationServers Session Control CentralizedDatabases Media Control & Gateways MediaServer

8. 7 Access Network Other Networks Web Portal ApplicationServers Session Control CentralizedDatabases Media Control & Gateways MediaServer Access Layer Session Control Layer Application Layer Open Industry Standard Support for a Variety of Applications : Speed Applications to market Common Session Control Element to Provide Service Interworking Predictable interactions between multiple services Common Subscriber Database with Open Interfaces Service Consistency Across Wireless, Wireline and VoIP Endpoints: Retain ownership of the subscriber and their services Ability to provide differentiated services Distributed Session Control IMS flexibility and scalability reduce OPEX Support mobility/portability Common support for CoS, QoS, security, scalability, reliability, and performance Common OAM&P Environment Ease integration into OSS/BSS/NMS Common OAM&P,Billing, etc. Capable of Interworking with the PSTN (i.e. legacy IN- based services) IP Multimedia Subsystem (IMS) - Key Attributes

9. 8 RNC MSC(Server) SGSN GGSN CN MGW BSC UMTS/GPRS WLAN Corporate P-CSCF I-CSCF MRF MGW MGCF IMS S-CSCF SIP Application Servers SIP Application Servers HSS CDMA 2000 DSL/Cable Modem DSLAM/CMTS IMS Access Network Independence

10. 9 Clients Devices Access Transport SessionControl Applications Managed Core IP Network Media GW Signaling GW MRFCCSCF Service Broker HSS Pres. Data Loc. Data Subs Data Micro Billing Integrated Pre-paid & Postpaid AAA Group Lists Media Server POTS phone GGSN PDSN MSC Cellular Access Point WiFi/802.11x Local Loop VoIP handset Ckt-PBX IP-PBX IP-phones ISDN-phones IP-phones DSL/Cable IP LAN Wireless Router Base Station 5ESS (IP-Centrex) Office/Hotel Hotspot Home On the RoadHome/Office Dual-mode WiFi phone Soft-phones PSTN SS7 SIP Clients Ckt handset Multiple user interfaces with common look and feel Other Clients IMS Converged Communications Services Vision Network Operations, Applications Mgt, Subscriber registration/ authorization PresenceServersTelephonyServersUnifiedMessaging

11. 10 IMS Functional Elements Session Management (SIP) Routing Databases Network Interoperability Elements Services and Support Components Charging Components

12. 11 IMS Functional Elements Application Server (AS) Breakout Gateway Control Function (BGCF) Call Session Control Function (CSCF) Home Subscriber Server (HSS) Media Gateway Function (MGW) Media Gateway Control Function (MGCF) Multimedia Resource Function Controller (MRFC) Multimedia Resource Function Processor (MRFP) Security Gateway (SEG) Serving/Gateway GPRS Support Node (SGSN/GGSN) Signaling Gateway (SGW) Subscription Locator Function (SLF) Service Capability Interaction Manager (SCIM) Policy Decision Function (PDF) – “Bandwidth Manager” (CoS & QoS)

13. 12 VisitedNetwork IMS Home Network - Functional Elements HSSDNSENUM I-CSCFS-CSCF Home Network AS AS AS Home Subscriber Server Centralized DB HLR successor User profile Filter criteria (sent to S-CSCF) Which applications Which conditions Home Subscriber Server Centralized DB HLR successor User profile Filter criteria (sent to S-CSCF) Which applications Which conditions Application Servers Push-to-talk Instant messaging Telephony AS 3 rd party or IMS Vendor Application Servers Push-to-talk Instant messaging Telephony AS 3 rd party or IMS Vendor Domain Name Server P-CSCF MGCF MGW PSTN H.248 ISUP BGCF SIP SS7 Diameter RTP TDM Call Session Control Function SIP registration SIP session setup Call Session Control Function SIP registration SIP session setup MSMS MRFC Media Gateway Control Function Interfaces to PSTN/PLMN by Converting SIP ISUP Interworking RTP to circuit H.248 control of MGW Media Gateway Control Function Interfaces to PSTN/PLMN by Converting SIP ISUP Interworking RTP to circuit H.248 control of MGW Breakout Gateway Control Function Selects network (MGCF or other BGCF) in which PSTN/ PLMN breakout is to occur Breakout Gateway Control Function Selects network (MGCF or other BGCF) in which PSTN/ PLMN breakout is to occur Media Resource Function Controller Pooling of Media servers (e.g. conference) Media Resource Function Controller Pooling of Media servers (e.g. conference) Proxy CSCF 1 st contact point for UA QoS Routes to S-CSCF Proxy CSCF 1 st contact point for UA QoS Routes to S-CSCF Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers Hides network topology Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers Hides network topology Serving CSCF Registrar Session control Application Interface Serving CSCF Registrar Session control Application Interface P-CSCF SIP UA/UE

14. 13 IMS Network-to-Network Connectivity HSSDNSENUM I-CSCFS-CSCF Visited Network Home Network SIP AS AS AS P/S-CSCF BackbonePacketNetwork Access MGCF MGW PSTN H.248 ISUP BGCF SIP SS7 Diameter RTP TDM RTP MSMS MRFC P-CSCF SIP Proxy/Serving CSCF Manages call origination Selects destination network Routes to I-CSCF Proxy/Serving CSCF Manages call origination Selects destination network Routes to I-CSCF Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers Hides network topology Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers Hides network topology UA/UE

15. 14 IMS UE Registration HSSS-CSCFP-CSCF UA/UE Register The UA/UE Registers with the S-CSCF MAR/MAA The S-CSCF consults HSS for Authentication Unauth The S-CSCF Challenges the UA/UE Register The UA/UE Registers with Credentials to the S-CSCF MAR/MAA S-CSCF Authenticates with HSS and Downloads User Profile

16. 15 IMS Subscription to UE State Changes HSSS-CSCFP-CSCF UA/UE Subscribe The P-CSCF Subscribes to the UA/UE Registration State Notify S-CSCF Notifies the P-CSCF of Registration State Subscribe The UA/UE Subscribes to its Registration State Notify S-CSCF Notifies the UA/UE of Registration State Now the Elements can Inform Each Other of Registration State Changes

17. 16 A Typical Example of an IMS Call User B DSL/Cable Modem DSLAM/CMTS RNC GGSN Network Z (UMTS/GPRS) Network X User A SGSN Network Y GRX P-CSCF I-CSCF S-CSCF HSS AS

18. 17 IMS (3G) Emergency Services Architecture

19. 18 3GPP IMS R7 Emergency Sessions HSSDNSENUM S-CSCF IMS Core Network AS AS AS P-CSCF MGCF MGW SelectiveRouter H.248 ISUP BGCF SIP SS7 Diameter TDM MSMS MRFC SIP CAMA E-MF IP PSAP Connectivity to Network Capable of Delivering Call to IP PSAP Connectivity to Network Capable of Delivering Call to IP PSAP Connectivity to Legacy Emergency Services Network Connectivity to Legacy Emergency Services Network 3GPP View of Emergency Sessions RTP IP Access Network Initiates Emergency Call IP Access Network Initiates Emergency Call PSAP Selection Left to Implementation PSAP Selection Left to Implementation IP Connectivity Access Network (ICAN) IP-PBX IP-phones (IP-Centrex, DSL, Cable) Legacy PSAP

20. 19 Potential Long Term IMS Emergency Services Network HSSDNSENUM I-CSCFS-CSCF Customer Home Network IMS Emergency Services Network SIP AS AS PSAP Selection AS P/S- CSCF BackbonePacketNetwork Access MGCF MGW BGCF SIP Diameter RTP MSMS MRFC P-CSCF SIP IP PSAP Call Delivered to IP PSAP with Location Call Delivered to IP PSAP with Location Call Enters IMS ESNet With Location Call Enters IMS ESNet With Location Location is Used to Determine PSAP Location is Used to Determine PSAP H.248 Selective Router ISUP SS7 TDM CAMA E-MF Legacy PSAP CAMA E-MF OR Call Delivered to Legacy Network Without Location (Query for Location Needed) OR Call Delivered to Legacy Network Without Location (Query for Location Needed)

21. 20 Emergency Call Delivery VoIP to IP PSAP P-CSCF I-CSCF MRF MGW MGCF IMS ES Network S-CSCF SIP Application Servers SIP Application Servers HSS IP PSAP Legacy ESNet/PSAP PSTN Legacy EO STP VSP VoIP Network PIDF-LO ANI Call Originates with Location Location used for PSAP Selection Call Delivered with Location

22. 21 Emergency Call Delivery VoIP to Legacy PSAP P-CSCF I-CSCF MRF MGW MGCF IMS ES Network S-CSCF SIP Application Servers SIP Application Servers HSS IP PSAP PSTN Legacy EO STP VSP VoIP Network PIDF-LO ANI Call Originates with Location Location Could be used for PSAP Selection Call Delivered only w/Callback (ANI) Query Mechanism Needed for Location Legacy ESNet/PSAP

23. 22 Emergency Call Delivery Legacy PSTN to IP PSAP P-CSCF I-CSCF MRF MGW MGCF IMS ES Network S-CSCF SIP Application Servers SIP Application Servers HSS IP PSAP PSTN Legacy EO STP VSP VoIP Network PIDF-LO ANI Call Originates with only Callback (ANI) Mechanism to Provide Location and PSAP Selection Required Call Delivered with Location Legacy ESNet/PSAP

24. 23 Emergency Call Delivery Legacy PSTN to Legacy PSAP P-CSCF I-CSCF MRF MGW MGCF IMS ES Network S-CSCF SIP Application Servers SIP Application Servers HSS IP PSAP PSTN Legacy EO STP VSP VoIP Network PIDF-LO ANI Call Originates with only Callback (ANI) Mechanism to Provide Location and PSAP Selection Required Call Delivered only w/Callback (ANI) Query Mechanism Needed for Location Legacy ESNet/PSAP

25. 24 Emergency Services - Additional Topics Bridge/Transfer –Including Location, if Feasible Alternate Routing Default Routing Wireless Phase 2 Updates TTY/TDD 3 rd Party Call Centers

26. 25 BACKUP SLIDES

27. 26 FUNCTIONAL ELEMENTS DESCRIPTIONS Home Subscriber Server (HSS) Application Server (AS) Call Session Control Function (CSCF) Breakout Gateway Control Function (BGCF) Media Gateway Function (MGW) Media Gateway Control Function (MGCF) Multimedia Resource Function Controller (MRFC) Multimedia Resource Function Processor (MRFP)

28. 27 Home Subscriber Server (HSS) Presence, Location and Profile End-User Identity Private and Public End-User Information Registration Information Service Initiation Information Subscriber Service Profile (SSP) –Downloaded to CSCF at Registration HSS Diameter

29. 28 Application Server (AS) Contains Call Related Application Logic Facilitates a Service Creation Environment Queried by S-CSCF in Real Time to Execute Logic Generally Specialized for Each Service May Provide Gateway to Legacy Applications (e.g. AIN) AS AS AS SIP Diameter

30. 29 Call/Session Control Function (CSCF) CSCF – Processes SIP Signaling P-CSCF –First Point of User Contact –Authenticates user –May Include Policy Functions C-CSCF –Central Node of Control Plane –Acts as Registar for User (Downloads SSP from HSS) –Invokes Application Servers –Performs Primary Routing Function I-CSCF –Located at Edge of Administrative Domain –Is the Ingress Network Point Defined in DNS –Shields Network Topology from External Networks I-CSCFS-CSCFP-CSCF SIP Diameter

31. 30 PSTN (Circuit Switched) Gateway BGCF – Routes to Gateway Based Upon Telephone Number MGCF – Controlling Function for SGW and MGW SGW – Provides Signaling Conversion Between SIP and ISUP MGW – Provides Conversion between RTP and TDM MGCF MGW H.248 ISUP BGCF SIP TDM SGW SIP

32. 31 Multimedia Resource Function (MRF) Offers Services Such as Conferencing MRFC – SIP User Interface toward S-CSCF MRFP – Controls the Media Server (MS) SIP MSMS MRFC