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Standards First!™

Standards First!™. H.450 Supplementary Services for H.323 Systems. Karl Klaghofer Siemens AG. Standards First!™. Contents. Scope of H.450 Architecture Example call flows Gateway Interworking Standardization aspects Summary. Scope (1) – What is H.450 about ?.

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Standards First!™

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  1. Standards First!™

  2. H.450 Supplementary Services for H.323 Systems Karl Klaghofer Siemens AG Standards First!™

  3. Contents • Scope of H.450 • Architecture • Example call flows • Gateway Interworking • Standardization aspects • Summary

  4. Scope (1) – What is H.450 about ? ITU-T umbrella standard for Telephony / Multimedia supplementary services for H.323 systems, for features that need signalling over the IP network beyond what is defined within H.323 base signalling protocol Examples: • Three Party Services • Call Redirection Services • Team Function Services • Unsuccessful Call Services • Attendant related services • …

  5. Examples: Call Center, Automatic Call Distribution (ACD) Using Call Transfer service to redirect calls from the ACD server to an ACD agent Use Call Intrusion/silent monitoring service for ACD supervisor services Multimedia Messaging Use of Call Diversion service to forward to Messaging Center Use Message Waiting Indication service by Messaging Center to notify the served user Integration with other Applications Integrate with E-Mail Integrate with world of organizers (e.g. calendar based call diversion) Scope (2) - H.450 as “Building blocks”for Applications

  6. Endpoint Endpoint Gatekeeper / Proxy Gatekeeper / Proxy EP EP Architecture (1) - Principles • Functional, symmetrical Protocol derived from ISO “QSIG” protocol, optimized for IP/H.323 environment • Independent of type of network (Private or Carrier) • Media independent • Flexible in architecture: • Fully distributed model Intelligent endpoints supporting H.450; network transparent for H.450 -> the Internet/Intranet paradigm • Centralized model H.450 as the networking feature protocol -> the traditional telephony model IP / H.323 FE Functional Entity H.450 Signalling FE FE

  7. GWY/BS to Wireless GSM, W-LAN, Bluetooth,... Server Endpoints - Group Features • Proxies Gateway (to QSIG, ISDN,…) Gatekeeper / Proxy Soft client Stimulus EP Fax Soft client IP Phone Architecture (2) – Example H.450 Endpoints & Entities IP / H.323 Network H.450 Signalling

  8. … H.450.3 H.450.2 H.450.1 Architecture (3) – H.450 in H.323 Protocol Model Applications G.7xx H.26x H.245 RTCP H.225 RAS H.225.0 RTP Unreliable Transport (UDP) Reliable (TCP) Network Layer (IP)

  9. Architecture (4) – H.450 Signaling within H.323 messages TCP/IP packet H.225.0 message (e.g. SETUP) User-user IE (H323-UU-PDU) H450 Supplementary Service Component H.225.0 (Q.931) IE's h323-message -body NFE I Proprietary “H.450 like” feature 3 Ext H.450 Feature 1 H.450 Feature 2 Service APDUs How to to react if not understood ? • Ignore • Reject • Clear call e.g. Setup-UUIE: Fast Start, Endpoint type, Source Address, Dest Address, ... Allows for Manufacturer specific extensions using Object Identifier that indicate the manufacturer Destination of the Feature ? • endpoint • any entity • a specific one

  10. SETUP ctSetup (TransferNbA,..) FACILITY ctInitiate (addressC,..) CONNECT ctSetup.Res REL COM ctInitiate.Res Example Call Flows (1) – Single Step Transfer (H.450.2) EP A EP B EP C Active call Active Call Idle

  11. SETUP (ccbs) RELEASE COMPLETE (ccbs.Result) SETUP (ccExecPossible) RELEASE COMPLETE SETUP (ccRingout) ALERT / CONNECT Example Call Flows (2) – Automatic Callback on Busy (H.450.9) EP A EP B A called B – B met busy • Monitoring User B phase • B becomes available Active Call

  12. groupNotification (pickup address B, callingUserA, pickupId,…) SETUP (groupNotification) Alerting SETUP FACILITY pickup ALERTING SETUP (pickRequ, pickupID) SETUP pickExe.inv CONNECT pickExe.Res Example Call Flows (3) – Call Pickup Group w/Pickup Server (H.450.5) Pickup Group Server B A C D Active Call

  13. Gateway Interworking (1) - Opportunities Opportunity for Gateway Interworking of H.323/H.450 Features with corresponding Features of other networks/systems for end-to-end feature operation in inhomogeneous networks: • PBX interworking: • QSIG, • DPNSS, • Proprietary PBX protocols • Public Network interworking: • DSS1 • US ISDN Protocols (NIx) • SS7 • Interworking with Non-H.323/H.450 VoIP systems: • SIP

  14. PBX Gateway Interworking (2) – Example QSIG GWY H.323/H.450 Gateway IP/LAN QSIG H.323 / H.450 Gateway interworking • H.450 based on QSIG concepts • Corresponding functions in both worlds allows easy interworking • Smooth migration from SCN to IP • Features available End-to-end between LAN and PBX QSIG Suppl Service H450.X H450.X QSIG Suppl Service H450.1 QSIG GF H450.1 QSIG GF H245 H245 QSIG Basic Call QSIG Basic call H.225.0 H.225.0 UDP TCP TCP UDP D-channel D-channel IP IP MAC MAC ISDN Control Plane Gateway interworking Voice Voice G.711 G.711 G.7xx G.7xx RTP RTP B-Channel B-Channel UDP UDP IP IP MAC MAC ISDN User Plane

  15. Gateway Interworking (3) – What about SIP ? H.323-SIP Gateway Supplemen-tary Service IW Basic Call IW H.450 SIP SS SIP VoIP System H.323/H.450 VoIP System SIP BC H.323 • Internet drafts available for H.323 – SIP Interworking • for Basic Call; with first products available on the market • Desire for Interworking between H.323 and SIP also on • Supplementary Services level – first candidates: • IETF Work item: SIP Call Transfer • Further SIP drafts available: MWI, Call Diversion, etc.

  16. Standardization – Methods All Standards of the H.450 series of ITU-T Recommendations follows the same, consistent method of specification: • Stage 1 Service Description – Users Perspective • Stage 3 Service Description – Procedures, Interactions • Call Flow Diagrams • Generic API definition • Syntax definition (ASN.1) • SDLs • High degree of interoperability between different implementations • can be expected

  17. Standardization – Status (1) Published ITU-T SG16 H.450.x standards – 12 Recommendations that cover more than 25 key features: • H.450.1 Generic Functions (Framework, base methods) • Call Related & Call independent H.450 signalling • Remote Operation Service - ROS (Invoke, Return Result, • Return Error, Reject) • Action Indicator (i-apdu) • Adressed entity (NFE) • Manufacturer Specific Information Extension Mechanism (MSI) • H.450.2 Call Transfer for H.323 • Single Step Transfer (w/o Consultation) • Transfer w/ Consultation • Transfer into Ringing/Active • H.450.3 Call Diversion for H.323 • Call Forwarding Unconditional (CFU) • Call Forwarding on Busy (CFB) • Call Forwarding on No Reply (CFNR) • Call Deflection (CD)

  18. Standardization – Status (2) • H.450.4 Call Hold for H.323 • Near End Hold • Remote End Hold • H.450.5 Call Park and Call Pickup in H.323 • Directed Park / Directed Pickup • Group Park / Group Pickup • Call Pickup Groups • H.450.6 Call Waiting in H.323 • H.450.7 Message Waiting Indication for H.323 • MWI Activation, Deactivation • MWI Interrogation • Message Waiting Callback (MWCB) • H.450.8 Names Identification in H.323 • Calling, Connected, Alerting, Busy Name Indication • H.450.9 Call Completion for H.323 • Call Completion on Busy (CCBS) • Call Completion on No Reply (CCNR)

  19. Standardization – Status (3) • H.450.10 Call Offering for H.323 • H.450.11 Call Intrusion for H.323 • Intrusion / Break in at Busy User • Silent Monitoring • Recording • H.450.12 Common Information • Feature Capabilities • Feature Control (do not hold, do not transfer, call type...) • Party Category (user, attendant, ...) • H.450 is on the ITU-T SG16 work program also in its new study period (- 2004); i.e. further H.450.x Rec. will be added Other standardization bodies H.450 activities: • ECMA TC32 • Published Interworking Standards for H.450.x – QSIG Interworking • ETSI Tiphon • Published H.450 Protocol Implementation Profiles (PICS)

  20. Summary • Open, standard feature protocol for H.323 based IP systems • Multi-vendor interoperability • Flexible in Architecture • Enables smooth migration from SCN to IP • Customer can determine its own speed of migration • End-to-end feature availability between SCN and IP systems during migration phase via Gateway Interworking • Allows to distinguish from competitors • Standard Manufacturer Specific Escape mechanism for proprietary add-ons to standardized H.450 signalling • H.450 as application enabler

  21. Thank You ! • Karl Klaghofer • Siemens AG • (karl.klaghofer@icn.siemens.de)

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