1
2
VoIPVoIP(Voice Over IP)
3
Gateway functionality is required to adapt the PSTN transmission to IP (the Internet Protocol)
AnalogLocalLoop
AnalogLocalLoop
Intranet/Internet
VoIP Network Network
Packet Switched
Logical ConnectionsG/WG/W G/WG/W
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Voice Gateway A gateway provides:
Signaling - dial tone, call set-up etc. (H.323, MGCP, SS7) Conversion to IP, (often Ethernet, possibly ATM) Compression (G.711, G.723.1 etc.) Echo Cancellation Quality of Service (QOS)
PacketNetwork
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N
etw
ork
Interface
PacketNetwork
Gateway Product
DigitalT1/E1
T3OC1/OC3
PhysicalInterfaces
Analogulawalawlinear
pulse dialing2W/4W
loop startground startgain control
ToneInterfaces
Tone GenerationDTMF
Call Progress Tone
Tone DetectionDTMFV.21
Call ProgressMF (R1, R2)
Modem Tone
DTMF ToneRelay
SignalingInterfaces
CASFXSFXO
E & MTransparent
CCSQ.931QSIG
Transparent
Voice/FaxProcessing
EchoCancellation
VAD
VoiceCoding
Voice Playout
Fax ModemV.21
V.27terV.29V.17V.33
Interfaces
phone
PBX
CentralOffice
KeySystems
modem
fax
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Voice/Fax Standards
Voice over IP H.323 SS7 MGCP SIP TCP/IP Tone detection Echo cancellation (G.165, G.168) Voice codecs V.x modems
Voice over Frame Relay FRF.11
Voice over ATM AAL2
Voice over Cable DOCSIS 1.1 MGCP
Fax over Packet T.37, T.38
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Telephony
Interface
Protocol
Stacks
ATM Networks
Frame Relay Networks
IP Networks
H.323Gateway
PC w/H.323 Node
Frame RelayGateway
ATMGateway
Inter Operability Packet Network
Network ManagementInterface Functions
Gateway Product
H.323NetworkProtocolInterface
FRF.11NetworkProtocolInterface
ATMStandard In WorkProprietary Today
Address Translationand Parsing
Fax Relay/Advanced Local
Processing
Signaling TranslationCAS H.323/FRF.11/ATMCCS H.323/FRF.11/ATM
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ITU-T Speech Coding Standards
0
10
20
30
40
50
60
70
1
Voice CODEC
Ban
dwid
th G.711G.726G.728G.729ABG.723
64 kbps
32 kbps
16 kbps
8 kbps5.3 kbps
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Mean OpinionScore(MOS)
0
1
2
3
4
5
5.3 6.3 8 16 32 64
G.711 PCM
G.726 ADPCM
G.728 LD-CELP
G.729
G.729AB
GSM
G.723.1A
Subjective Voice Coder Quality
Kpbs
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VoDSL (VoIP &VoATM)
VoATMAAL2
ATM
IP
ADSL INTERLEAVED PATH
PLVT
VoIP
PLVT
LifelinePOTS
PPP
AAL5
ATM
AAL2AAL5
PPP
IPVoIP
LifelinePOTSDSL Client Access Network
ISP or Core
ADSL FAST PATH
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TI’s Golden Port
Integrated software with simultaneous support for: Voice - Fax - V.90 Modem - Signaling
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Network Requirements
Scalability - products typically range from 24/30 ports (T1/E1) to thousands of ports
Small Footprint - rack space in central offices and ISP POPs is expensive
Power Consumption - critical for both cost and heat Cost - cannot afford idle resources Simultaneous voice relay, fax relay, V.90 modem
termination Non-Blocking Manageable - accounting and operations
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Network Efficient Utilization
Network Type Bandwidth Utilization Grade of Service
Telogy Software Provides Choice of low bit rate codecs Configurable voice packet sizes (10 ms to 80 ms) Efficient Voice Activity Detector (VAD) Fax demodulation/remodulation Ability to restrict max fax transmission rate, e.g., 2400, 4800, 9600 bps Sub-Channel Multiplexing - FRF.11
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Universal Access
Recurring Cost Discrete Trunks
Capital Cost Idle Equipment
PacketNetwork
PSTN Replacement requires support for Voice, Fax and V.90 Modem
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Channel Density
Multi-Instance - ability of software to support multiple modems in same DSP Old software base hard-coded for single channel operation;
difficult to migrate to multi-channel Software designed for multi-channel operation from its inception
results in a more robust product
Critical decisions on MIPS and memory vs. modem performance tradeoffs Skimping here will result in a poor performing solution
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Hardware Architecture
Multi-processor
Real time call discrimination
Maximizes scalability
Eliminates the requirement for discrete trunks
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Multi ProcessorT1/E1 Building Block
Ethernet(Internet)
CISC or RISC Processor Telephony Protocols Network Protocols Management Routing Billing
Digital Signal Processor(s) (DSP)
Voice Compression Tone Detection/Generation Echo Cancellation Silence Suppression Fax Modem V.90 Data Modem
DSP
DSP
DSP
DSP
RISC Processor Modem Control Processing
PSTN Trunks
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Determines on a call by call basis if the calling “device” is a Human, Fax Machine, or a Modem Tone Detection Flag Detection Called number parsing
Dynamic Call Discrimination
CISC Ethernet(Internet)
DSP
DSP
DSP
DSP
RISC
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480Miles
8 ms1 ms
60 Miles
16 ms
960Miles
1,920Miles
32 ms
Echo Cancellation
GatewayPBX
CO Switch with
echo canceller
Every 60 miles between the Gateway’s echo canceller and the reflecting hybrid requires 1 ms of echo tail
Telogy Software provides selectable tail length from 8 ms to 128 ms, G.165, G.168 compliant
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Packet Loss Voice/Fax
Lost Packets Due to:•Network Congestion/Performance•Network Architecture•Improper Jitter Buffer Size•Software Not Designed for Peak Load
65 4
32 1 Playout
Buffer
GatewayProductPacket Network
Lost Lost
Telogy Voice Software Provides:•Lost packet compensation for all codecs•Lost packet statistics•Peak MIPS design philosophy
Telogy Fax Software Provides:•Control packet redundancy to correct for lost packets•Advanced local processing to negate the effects of network problems•Very high call completion rates (100% at 5%; 97% at 10)
Potential Causes of Packet Reordering:•Network Congestion/Performance•Network Architecture
GatewayProduct
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Real-Time Fax Gateway Real-Time Fax Gateway
Emulates the Central Office and the remote fax machine (fax modem) Demodulates the fax transmission and extracts the fax data Encapsulates the fax data Transmits the fax data in packets Remodulates the fax data for transmission to the remote fax machine
PacketNetwork
64K bps
14.4 Kbps
64K bps
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Success Factors for Fax over Packet Networks Success Factors for Fax over Packet Networks
PacketCompensation
Fax Interface Unit to Fax Interface
Unit CompatabilityDelay
Compensation
Network Call Stability
Fax to Fax Interface Unit Compatability
Analog Signal Quality
JitterCompensations
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Fax LatencyFax Latency
OriginatingFTE FIU
DestinationFTE
Duration ofT.4 timer(per T.30)
Timeout occurswithout receiving a
reply and FTE startsretransmission oforiginal message.
FIU
FTE endstransmission and
starts T4 timer
Network
Delay
Delay
Retransmission from Originating FTE “collides”
with reply from Destination FTE
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Technique To Technique To Keep Call AliveKeep Call Alive
Duration of T.4 timer(per T.30)
OriginatingFTE FIU FIU
DestinationFTE
NetworkFTE endstransmission and
starts T4 timerDelay
Delay
Message arrives overnetwork. FIU remodulatesmessage as it is received.
Before timeout at Originating FTE, FIU starts sending “preamble” fill signal in anticipation of receiving message over network.
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Difference Between a Good Modem and aDifference Between a Good Modem and aGreat ModemGreat Modem
Key Algorithms - where some vendors cut corners Echo Canceller and Equalizer
Structure, speed and level of convergence, length Full vs. Reduced Complexity Viterbi decoder Handshaking sequence
Works reliably in channel impairment situations Full channel analysis
Smart optimization techniques
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Network ManagementNetwork Management
Telogy Software Provides Quality statistics Supervisory statistics Online configuration Complete SNMP MIB for VOP
ChallengesQuality Measurement
Packet Loss Latency Jitter
Supervisory Measurement Call Accounting Call Type
Configuration Address Translation Signaling Mode Network Environment Parameters
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Network Management Diagnostics Network Management Diagnostics
VOICE MON - Voice Packet Software MonitorPCM trace capabilityLoop back capabilitySignal level measurementsPlayout statisticsMemory dump facility
FAX MON - Fax Software MonitorReal-time fax traceAll significant eventsMillisecond accuracy on timestampingCompress format interpreted by PC software
SIG MON - Micro Signaling Trace MonitorReal-time trace capabilityControllable levels of tracingAll significant events including state changes, etc.Customer can route output to Monitoring System
V. MON - Modem MonitorReal-time trace capabilityConfiguration optionsStatisticsStatus
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Software Scalability Software Scalability
What to Look For: Pre-integrated hardware and software scaling from One to Thousands of ports Optimized solutions and cost for all market areas Synchronized feature migration
Client ProductsTelogy Software
Client Suite
Low DensityMulti-Function
Access ProductsTelogy Software
Access Suite
Multi-ChannelMulti-Function
Infrastructure ProductsTelogy Software
Infrastructure Suite
High DensityBroad range of
capabilities
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Intellectual PropertyIntellectual Property
It’s a Standards-Based World G.728, G.729, G.723.1, etc. V.90, V.34, etc.
Intellectual Property Critical Success Factor for Marketplace Success Now at forefront of Customer focus
Key Competitive Issue Affects product costs Liability
Patents 101
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Telephones and Fax Machines connect directly with each other over time division multiplexed circuits
Traditional TelephonyTraditional Telephony
Lahore Karachi
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Central OfficeCentral Office
Connections are managed by Central Office Switches and Enterprise PBXs Route calls onto digital trunks Provide billing information (Call Detail Records - CDRs) Provide management information (Alarms, Usage etc.)
CircuitSwitched
DigitalTrunks
AnalogLocalLoop
AnalogLocalLoop
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ModemsModems
Analog Modem calls are made in the same way as PSTN voice and fax calls
CircuitSwitched
DigitalTrunks
AnalogLocalLoop
AnalogLocalLoop
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Modems and the Internet/Intranet Modems and the Internet/Intranet
PC Client to WEB Server rather than Peer to Peer Many clients connecting through each POP
Digital access trunks required to be operationally economical
Remote Access Servers (RAS) An integration of Digital Modems and IP Router
PacketNetwork
RemoteAccess Server
WEBServer
POP
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Basics-Analog Voice to PCMBasics-Analog Voice to PCM
An analog voice signal is received
The Signal is converted to a Pulse Code Modulation(PCM) digital stream
10110101 11010011 11001001 00100100 00111100 10010011 11100001 00100100
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Basics-PCM to FramesBasics-PCM to Frames
11010011 11001001 00100100 00111100 10010011 11100001 00100100 00111100
And Voice frames are created
10110101 11010011 11001001 00100100 00111100 10010011 11100001 00100100 00111100
The PCM stream is fed into the CODEC
10110101
Each Frame is 10 ms long (G.729a) and contains 10 bytes of “speech”
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SummarySummary
Carrying Voice, Fax and Data over Packet networks provides the most bandwidth efficient method of integrating divergent technologies
While the challenges to this integration are substantial, the expanded market addressed by Telogy’s Golden Port make universal port implementations your best choice