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IP Telephony

Guided by: Presented by: Dr.S.K.Ghosh

Nitesh Jain 05IT6008

M.Tech 1st year

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CONTENTS

• INTRODUCTION

• DIFFERENT TYPES

• WHAT IS H.323

• H.323 COMPONENTS

• PROTOCOL SPECIFED BY H.323

• H.323 CALL ESTABLISHMENT

• H.323 CONTROL SIGNALING FLOW

• H.323 MEDIA STREAM & MEDIA CONTROL FLOW

• H.323 CALL RELEASE

• CONCLUSION

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Introduction

• Internet telephony uses the Internet protocol to send audio, video an data between two or more users in the real time.

• IP telephony is the integration and convergence of voice and data networks, services, and applications.

• The main motivation of development of IP Telephony is the cost saving & integrating new services.

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Introduction (cont…)

• Vocaltec introduced the first Internet telephony software product in early 1995. Running a multimedia PC, the Vocaltec Internet Phone.

• In 1996, Vocaltec with an Intel Company announced to produce the first IP telephony gateway.

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Different Types Of IP Telephony

• PC to PC• Phone-to-phone over IP• PC-to-Phone• Phone-to-PC

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PC to PC

Figure 1 (ref: www.iec.com)

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Phone-to-phone over IP using Gateways

Figure 2 (ref: www.iec.com)

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Phone-to-phone over IP using Adapter Boxes

Figure 3 (ref: www.iec.com)

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PC-to-Phone or Phone-to-PC

Figure 4 (ref: www.iec.com)

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Different type of IP telephony Standard

• H.323 standard

• Session initiation protocol (SIP)

• Media gateway to media controller protocol (MGCP)

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What is H.323

• The H.323 standard for the transmission of real-time audio, video, and data communications over packet-based networks based on IP telephony.

• H.323 is a standard produced by the ITU-T Study Group 16.

• Currently the most widely-supported IP telephony signaling protocol.

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H.323 Components

• Terminals• Gateways• Gatekeepers• Multipoint Control Units (MCUs)

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• Terminals :H.323 terminal can either be a personal computer or a stand-alone device, running an H.323 and the multimedia applications.

• Gateways :An H.323 gateway provides connectivity between an H.323 network and a non-H.323 network.

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Gatekeepers

• Address Translation• Admission Control• Bandwidth Control• Zone Management• Call-Control Signaling• Call Authorization• Call Management

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Multipoint Control Units:

• MCUs provide support for conferences of three or more H.323 terminals. All terminals participating in the conference establish a connection with the MCU.

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Protocols Specified by H.323

• audio CODECs• video CODECs• H.225 registration, admission, and status

(RAS)• H .225 call signaling• H.245 control signaling• real-time transfer protocol (RTP)• real-time control protocol (RTCP)

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H.225 RAS

• Gatekeeper discovery• Endpoint registration• Endpoint location• Admission control

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H .225 call signaling• H.225 call signaling is used to set up connections

between H.323 endpoints over which the real-time data can be transported.

• Two types :

– Direct call signaling– Gateway routed call signaling

H.245 Control Signaling• Capabilities Exchange

• Logical Channel Signaling

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Real-Time Transport Protocol

• Real-time transport protocol (RTP) provides end-to-end delivery services of real time audio and video.

• RTP is used to transport data via the user datagram protocol

Real-Time Control Protocol (RTCP)

• RTCP provides control services for RTP.

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H.323 Call Establishment

Figure 5 (ref: www.iec.com)

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H.323 Control signaling Flows

Figure 6 (ref: www.iec.com)

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H.323 Media stream & media control flow

Figure 7 (ref: www.iec.com)

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H.323 Call Release

Figure 8 (ref: www.iec.com)

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Conclusion• Internet telephony is cost savings and

integrating new services. • Internet Telephony is a powerful and

economical communication options by combination of the telephone networks and data networks.

• Many public telecommunication operators are establishing their own IP telephony services, and using IP-based networks as alternative transmission platforms.

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References :• Book on “IP Telephony“Olivier Hersent,

David Gurle & Jean-Pierre Petit.

• www.iec.org/online/tutorials/• www.cis.ohio-state.edu/~jain/• www.cs.columbia.edu/~coms6181/• www.cisco.com/• www.tmcnet.com/• www.javvin.com/

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THANK YOU

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