VoIP & Mobile VoIPVoIP & Mobile VoIP

97598039 97598039 梁紀翔梁紀翔NETLabNETLab

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TopicsTopics

►Voice over Internet ProtocolVoice over Internet Protocol H.323, SIP, SkypeH.323, SIP, Skype AdoptionAdoption BenefitsBenefits ChallengeChallenge

►Mobile VoIPMobile VoIP Generic Access NetworkGeneric Access Network

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Voice over Internet ProtocolVoice over Internet Protocol

►Family of transmission technologies for dFamily of transmission technologies for delivery of voice communications over IP nelivery of voice communications over IP networksetworks

►Talks to other IP phone or PTSNTalks to other IP phone or PTSN►Use codecs convert analog voice into digitUse codecs convert analog voice into digit

al audio stream al audio stream ►Video, text, file, conference, voice mail…eVideo, text, file, conference, voice mail…e

tctc

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Common protocolsCommon protocols

►H.323 (ITU-T)H.323 (ITU-T)►Session Initiation Protocol (RFC 3261)Session Initiation Protocol (RFC 3261)►Skype (Propritary)Skype (Propritary)

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H.323H.323

►FirstFirst VOIP standard (Feb. 1996) VOIP standard (Feb. 1996)►Part of H.32x familyPart of H.32x family►Audio-Video communication on packet Audio-Video communication on packet

networknetwork►Call singling & control, multimedia Call singling & control, multimedia

transport & control, bandwidth control transport & control, bandwidth control for P2P and multipoint conferencefor P2P and multipoint conference

►Based on Q.931 of ISDNBased on Q.931 of ISDN

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System

conrtrol

H.225Call

ControlSignaling

R T P / R T C P

( R e a l - t i m e T r a n s p o r t

p r o t o c o l / R e a l - t i m e

T r a n s p o r t C o n t r o l

P r o t o c o l )

I P

U D PA u d i o C o d i n g / D e c o d i n g

( G . 7 1 1 , e t c )

H.225RAS

(Registration, Admission, and Status)

H.245TerminalControl

&Management

T C P

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PSTN ISDN

Terminal

Gatekeeper Multipoint Control Units

Gateway

Zone

Terminal

Gatekeeper Multipoint Control Units

Gateway

Zone

WAN

LAN LAN

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Caller Callee

2.H.225 Call Setup (TCP)

3.H.245 Call Control (TCP)

4.RTP (UDP)

Gatekeeper

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SIPSIP

►Application Layer protocol for Application Layer protocol for controlling multimedia communication controlling multimedia communication session over IPsession over IP

►Client-Server HTTP like Text-based Client-Server HTTP like Text-based control message request/responsecontrol message request/response

►Depend on SDP (RFC 2327), RTPDepend on SDP (RFC 2327), RTP

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RequestMessages Type

Description

REGISTER Registers the user agent

INVITEInitiates a call by inviting

user to participate in session

ACK

Confirms that the client has received a final response to an INVITE request

CANCEL Cancels a pending request

BYEIndicates termination of the

call

OPTIONSUsed to query the

capabilities of a server

ResponseMessages Type

Description

1xxInformational Responsesex. 180 Ringing

2xxSuccessful Responsesex. 200 OK

3xxRedirection Responsesex. 302 Moved

Temporarily

4xxRequest Failure Responsesex. 404 Not Found

5xxServer Failure Responsesex. 503 Service

Unavailable

6xxGlobal Failures Responsesex. 600 Busy Everywhere

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SkypeSkype

►Proprietary P2P model, wriProprietary P2P model, written by KaZaA developerstten by KaZaA developers

►Decentralized user directoDecentralized user directoryry

►AES encryptedAES encrypted

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AdoptionsAdoptions

►Many implementations of Many implementations of H.323 & SIPH.323 & SIP Analog Telephone Adapter cAnalog Telephone Adapter c

onnects old phone and IP neonnects old phone and IP networktwork

Dedicated IP phoneDedicated IP phone Softphone on PCSoftphone on PC

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BenefitsBenefits

►Reducing communication and Reducing communication and infrastructure costsinfrastructure costs Charged per amount of data not per timeCharged per amount of data not per time Free/Open-source IP-PBX software Free/Open-source IP-PBX software

integrate legacy phone system ex. integrate legacy phone system ex. AsteriskAsterisk

►FlexibilityFlexibility Easy to encrypt, location independenceEasy to encrypt, location independence Integration with other servicesIntegration with other services

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ChallengeChallenge

►QoSQoS Latency and JitterLatency and Jitter

►Power failurePower failure►Emergency callEmergency call►Lack of redundancyLack of redundancy►Number portabilityNumber portability►SecuritySecurity►Fax and other telephony devicesFax and other telephony devices

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Mobile VoIPMobile VoIP

►Extension of mobility to VoIP networkExtension of mobility to VoIP network►Mobile device with SIP client ex. fringMobile device with SIP client ex. fring

High speed IP communication 3.5G, WiFi, WiMHigh speed IP communication 3.5G, WiFi, WiMaxax

Some company may block SIPSome company may block SIP►Use softswitch to bridge SIP and RTP to ceUse softswitch to bridge SIP and RTP to ce

ll phone networkll phone network Handset still use GSM or CDMAHandset still use GSM or CDMA

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Generic Access NetworkGeneric Access Network

►3GPP standard to let dual-mode 3GPP standard to let dual-mode handset to seamlessly roam or handset to seamlessly roam or handover between WLAN and handover between WLAN and WAN(GPRS)WAN(GPRS)

►GAN ControllerGAN Controller Inside cellular core network, as another Inside cellular core network, as another

base stationbase station

►When detects WLAN, establish secure When detects WLAN, establish secure IP connection to GAN Controller IP connection to GAN Controller

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Questions ?Questions ?

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ReferencesReferences► VoIP http://en.wikipedia.org/wiki/VoIPVoIP http://en.wikipedia.org/wiki/VoIP► H.323 http://hive.packetizer.com/users/packetizer/papers/h323/h323_protocol_overview.pdfH.323 http://hive.packetizer.com/users/packetizer/papers/h323/h323_protocol_overview.pdf► SIP http://www.cs.columbia.edu/sip/SIP http://www.cs.columbia.edu/sip/► Asterik http://www.asterisk.org/Asterik http://www.asterisk.org/► Skype http://www.skype.com/intl/en/Skype http://www.skype.com/intl/en/► GAN http://www.3gpp.org/ftp/Specs/html-info/43318.htmGAN http://www.3gpp.org/ftp/Specs/html-info/43318.htm► GAN http://www.3gpp.org/ftp/Specs/html-info/44318.htmGAN http://www.3gpp.org/ftp/Specs/html-info/44318.htm► ““ 行動網際網路電話之研製與實現”行動網際網路電話之研製與實現” , , 李昆達李昆達 , 2005, 2005► ““H.323 H.323 網路電話視訊監控與錄製系統之研製”網路電話視訊監控與錄製系統之研製” , , 曾致皓曾致皓 , 2008, 2008► ““H.323 H.323 網路電話音訊監控與錄製系統之研製”網路電話音訊監控與錄製系統之研製” , , 黃威穎黃威穎 , 2008, 2008► ““ 客製化客製化 H.323H.323 協定之智慧型網路電話監控與錄音系統”協定之智慧型網路電話監控與錄音系統” , , 蔡家瑞蔡家瑞 , 2009, 2009