The Essential Developers Toolkit for Designing Enterprise IP Telephony
Debbie GreenstreetDirector, Product ManagementTexas Instruments
Internet Telephony ExpoFebruary 2003
AgendaEnterprise IP TelephonyIP Telephony ArchitectureKey Functional AttributesSolution Components
Enterprise Network Telephony EvolutionPacketNetwork
Enterprise Gateway Block Diagram
Enterprise IP Phone Block Diagram LAN RJ45PC RJ45DEVICEHOSTUser InterfaceMemory InterfaceColor GraphicsEthernet InterfaceUSB InterfaceLCD I/FAudio I/FKeypad I/FUSB I/FORMemory IntfVoice InterfaceNetwork InterfaceProcessor and Associated Logic
VoiceVADGSMPacket InterfaceSignalingEchoCancellerFax RelayTx GainCaller IDToneDetectionSignaling SupportVoice CodecVoice PlayoutPacket Voice ProtocolRx GainFax Data PumpFax Protocol Relay InterfaceT.30 Fax Network DriverPCMInterfaceTone Gener- ationCODECSLICCONFVoIP Signal Processing Functional Components
VoIP RISC Software Functional Components Hardware Abstraction LayerDSP InterfaceApplication Services LayerTelephony Hardware Abstraction LayerH.323ProtocolCAS/CCS SignalingUser Interface UnitSIPProtocolCall ControlRTOSSupplementary Services
Real-Time Fax RelayFAX signal detectionDemodulation of the fax transmission and extracts the fax dataRemodulation of the fax data for transmission to the receiving fax machineFAX protocol processingeg, T.30 protocol Network Protocol Processing Packetizing/depacketizing T.38 UDP (TCP) Jitter control Error recovery
Echo CancellerFunctionsRemoval of echo from frame of PCM samplesDoubletalk detectionAcoustic Echo cancellationImportant AttributesConvergence time (initial/updates) - time to train on the echoConvergence on narrowband signals (e.g., MF/DTMF tones)Suppress echo on DTMF digitsDoubletalk detectionPerformance with high background noise - can cause instability and loss of echo cancellation
Interoperability - Telephony & Fax Challenges
Interoperability - Packet NetworkP r o tocol
StacksATM NetworksFrame Relay NetworksIP NetworksH.323 GatewayPC w/ H.323 NodeFrame Relay GatewayATM GatewayNetwork Management Interface FunctionsGateway Product
Jitter (Variable Delay) Voice/FaxKey Features for Robust Playout Buffer:Adaptable playout buffer including:Programmable buffer sizeDynamic buffer sizingJitter buffer real-time statisticsFax - large jitter buffer to reduce the chance of lost packets
Packet Loss Voice/FaxLost Packets Due to: Network congestion/performance Network architecture Improper jitter buffer size Software not designed for peak load654321Packet NetworkLostLostPotential Causes of Packet Reordering: Network congestion/performance Network architecture
VoIP Quality MonitoringWhat happens if it doesnt sound good.Telephony tools Support production lab testingLAN, packet network tools Dont capture voice QOS problemsNeed passive monitoring toolsAccurately estimate user perceived qualityMeasure live VoIP calls, not sample test callsIsolate and diagnose packet network quality problemsSeparate from signal processing quality problems.
Other Features to ConsiderSecurityOften mentioned, but no common standard yetCableLabs including security for Voice over CableIPSEC for signalingAES for voice packetsWireless LANNatural progression from data network popularityBusiness office applicationsConsumer opportunities in Asia/Japan
Issues in Standards-Based TechnologiesNew emerging markets and technologyNeed for interoperability among vendors, providersStandards bodies produce comprehensive specificationsNo way to avoid infringementCompliance requires use of third party IPWork-arounds/design-arounds not possibleInfringement is easily identifiableIf you are in a particular area you are infringingWebsite searches flag product offeringsPotential liability is uncertainValidity/Invalidity of claimants IPClaimants may have IP but no pricing structure
Company Profiles Affect Risk and ResponseThree categories of companies at riskTechnology providersOriginal equipment manufacturersEnd usersLocation in the food chain affects both risk and responseTechnology Providers Service Providers End Users OEM ManufacturersIP Claim #nIP Claim #1Example: Sum = $9/portNo Licensing, Indemnification $9/portNon-Payment can Result in Enjoinment
VoIP Product Development ChecklistTime to Market GoalProduct scheduleOpportunity costsInternal ResourcesHow manyExpertiseProduct DifferentiationCorporate expertiseMarket needsRisk AssessmentTechnologyIntellectual propertyScalabilityFeature growth
VoIP Toolkit Silicon
VoIP Toolkit - SoftwareIP Network HardwareDSP SoftwareTelephony Hardware Hardware Abstraction LayerDSP InterfaceApplication Services LayerTelephony Hardware Abstraction LayerH.323ProtocolCAS/CCS SignalingUser Interface UnitSIPProtocolCall ControlRTOSSupplementary ServicesApplications
VoIP Toolkit Board LevelOptionsBoard level VoIP functionality with common interface, eg PCI, for insertion in larger systemBasic level of core VoIP software often includedIP phone reference designBenefitsBoard level design (hardware and software) completeReduces hardware and software resources requirements
Toolkit Questions to AskSiliconWhat hardware interfaces are requiredWhat level of functional integration makes senseSoftwareWhat RTOS model makes senseProtocol sourceVoIP technology providerThird party expertProprietary solutionCall Control, Supp Services, etcHow much is needed, uniqueness, expertiseApplications modelFeature differentiationDevelopment/test tools
Your VoIP Product - Pulling It All TogetherEnterprise IP Telephony RequirementsVariety of features, protocols what is right for your productMarket, cost goalsFeature differentiationEvaluate Development OptionsInternal resources, expertiseOff the shelf productsTools AvailableHardwareChip sets, boards, reference designsSoftwareRTOSProtocol stacksCall control, supplementary serviceDont forget test, quality of service, serviceability
As mentioned earlier, corporate networks were one of the primary applications to benefit from VoIP technology. These solutions migrated from the access devices, or Small Medium Enterprise gateways to IP based solutions. IP based PBXsIP phones
Allied Business market report predicts that the SME IP PBX hosted business will exceed $12.7 B by the end of 2007 and that over 50% of seats shipped will by IP by 2003.
IP Centrex good market opportunities as well. Spec available
The reference design will be implemented as the TI IP Phone development and demonstration board.
Customers can use this to develop their IP Phone application code to the APIs which we will provide. Customer application code will include things like the user interface (display, speed dials, keypad control), and all the PBX type functions (call hold, forwarding, etc)
The breadth of interoperability issues are often overlooked when implementing a voice and fax over packet solution. A lot of telephony signaling standards as well as physical interfaces are involved in interface to the full range of telephony products. For a quality solution, and true interoperability, tone detection must be differentiated from the voice, and handled separately. Then, processing the subsequent signals (whether voice energy, modem tones, echo etc) has significant interoperability issues based on standards, network conditions and end station capabilities.
Animations:5 clicks to bring up groupings.6th click - next slide ECO symbol back to main interoperability slideOf course, the network interface has a tremendous set of interoperability issues surrounding standards, network type, network conditions, configuration, addressing schemes, etc. Not only is the packet network type itself important with respect to support of interoperability and standards, but interoperability with respect to configurations and conditions within that network. Address translation between packet addressing and E.164 addresses, voice and fax encapsulation schemes, translation between telephony signaling and network signaling all have significant ramifications with respect to packet network interoperability.
Animations:3 clicks to bring up groupings.4th click - next slide ECO symbol back to main interoperability slidePacket networks introduce another effect, not present in traditional TDM networks; variations in the rate which packets arrive. This jitter affects quality in both voice and fax solutions. The Golden Gateway solution provides a robust jitter buffer that provides dynamic sizing to accommodate varying network conditions. This buffer allows accumulation of enough packets to provide a constant cadence of packet playout to the users ear, or to the fax machine, avoiding voice and fax sample loss. Statistics on this buffer are provided to the gateway equipment for efficient use and flexible configuration. Not all solution on the market provide this important feature. Telogy can handle up to 300ms of jitter on fax calls, superior to most solutions.
Animations:Groupings appear automatically.Click - next slideHyperlink:Action button links to QOS Issues slide
Another area that affects the quality of both voice and fax calls is network packet loss. Lost packets at the network level are due to network congestion, (significant activity and usage), and in some cases, insufficient or poor network architecture. Packet loss can occur at the voice/fax over packet gateway if a playout buffer to accommodate jitter is not employed, or is improperly sized. Packets may also be lost in a VoIP solution if the solution is not designed based on Peak MIPs performance of each of the
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