The design, comparison and current status of TWAREN voicemail

systems

2007/08/27

Chia-Hung Hsu Li-Chi Ku Che-Nan Yang

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Outline TWAREN VoIP Architecture Voicemail Systems

SEMS Unity Asterisk

Conclusions

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Architecture

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Architecture (cont.)

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Architecture (cont.)

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Voicemail SystemsSEMS (SIP Express Media Server)

Media Server for SIP Based VoIP Services.

Separation of Media and Control.

Application Modules

SessionHandling

DialogHandling

AudioLayer

AudioModules

SER IPCServer

SER IPCClient

RTPLayer

File I/O

Signaling Media

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Voicemail Systems (cont.)Modular Design

• Core and Plug-ins

SER and SIP Proxy Server

SIP

RTP

Socket / FIFO

SIP Proxy Server

SIP UASEMS

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Voicemail Systems (cont.)Signaling

IP Network

SIP Proxy Server

SIP UA1

SEMS

Mail ServerSIP UA2

(unregistered)

INVITE SIPUA2

INVITE SIPUA2

200 OK

200 OK

RTP Session

SMTP

Voice Mail

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Voicemail Systems (cont.)SEMS Services in TWAREN

SIP UA1

SEMS

RTP

Announcement

SIP UA1

SEMS

RTP

Conference

SIP UA2

RTP

SIP UA1

SEMS

RTP

Voicemail

Mail Server

SMTP

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Voicemail Systems (cont.)Example of Voicemail Format

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Voicemail Systems (cont.)CISCO Unity

One of the Cisco® Unified Communication Systems

powerful unified message (e-mail, voice, and fax messages)

intelligent voice messaging (full-featured voice mail providing advanced functions)

Commercial systems

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Voicemail Systems (cont.)Multiple network services integration

required:• Dynamic Domain Name Servers• Directory Servers• Message Stores

Supported message store• Microsoft Exchange• IBM Domino

Standards compliance• VPIM （ Voice Profile for Internet Mail ， RFC-

3804 ）• AMIS （ Audio Messaging Interchange

Specification ）

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Voicemail Systems (cont.)Signaling

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Voicemail Systems (cont.)Signaling (cont.)

IP Network

SIP Proxy Server

SIP UA1

Unity

SIP UA2(unregistered)

INVITE SIPUA2INVITE SIPUA2

200 OK200 OK

RTP SessionNotify

RTP Session

INVITE Unity

INVITE Unity

200 OK

200 OK

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Voicemail Systems (cont.) Asterisk

PBX Switching Core• accept calls from interfaces and handle according to

the dialplan.

Application Launcher• ring phones, connect to voicemail, etc.

Codec Translator• compressed with different codecs to seamlessly talk to

one another.

Scheduler and I/O Manager• which applications and drivers can take advantage of.

Dynamic Module Loader

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Voicemail Systems (cont.)Loadable Module APIs

• Channel API• Application API• Codec Translator API• File Format API

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Voicemail Systems (cont.)

Asterisk Application API

Asterisk Channel API

ApplicationLauncher

PBXSwitching

Core

Schedulerand I/O

Manager

DynamicModuleLoader

Asterisk File Format API

CodecTranslatorC

odec Translator API

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Voicemail Systems (cont.)Signaling

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Conclusions

badgoodbadUser Friendly

independentindependentshareDatabases

wav/gsmwavwavFile Format

SIP / H.323 / IAX / Skinny / PSTNSIP / SkinnySIPProtocol

lowhighlowSecurity

noyesnoReport

Sendmail / PostfixMicrosoft ExchangeSendmail / PostfixMail Server

SMTP / SIPSMTP / SIPSMTPMessages

easyhardeasyGetting Resource

hardmedianeasyDifficulties

lowhighlowCost

Linux/BSD/Mac OSWindows 2000Linux/BSDOperation System

X86 PCMCS ServerX86 PCHardware

freelicensefreeLicense

DigiumCISCOiptelVendor/Integrator

AsteriskUnitySEMS