1. IP Telephony
Presented by:
Syed Iftekhar Hussain Rizvi
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2. 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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3. 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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4. 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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5. Different Types Of
IP Telephony
• PC to PC
• Phone-to-phone over IP
• PC-to-Phone
• Phone-to-PC
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6. PC to PC
Figure 1 (ref: www.iec.com)
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7. Phone-to-phone over IP
using Gateways
Figure 2 (ref: www.iec.com)
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8. Phone-to-phone over IP
using Adapter Boxes
Figure 3 (ref: www.iec.com)
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9. PC-to-Phone or Phone-to-
PC
Figure 4 (ref: www.iec.com)
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10. Different type of IP telephony
Standard
• H.323 standard
• Session initiation protocol (SIP)
• Media gateway to media controller protocol
(MGCP)
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11. 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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12. H.323 Components
• Terminals
• Gateways
• Gatekeepers
• Multipoint Control Units (MCUs)
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13. • 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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14. Gatekeepers
• Address Translation
• Admission Control
• Bandwidth Control
• Zone Management
• Call-Control Signaling
• Call Authorization
• Call Management
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15. 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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16. 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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17. H.225 RAS
• Gatekeeper discovery
• Endpoint registration
• Endpoint location
• Admission control
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18. 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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19. 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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20. H.323 Call Establishment
Figure 5 (ref: www.iec.com)
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21. H.323 Control signaling
Flows
Figure 6 (ref: www.iec.com)
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22. H.323 Media stream &
media control flow
Figure 7 (ref: www.iec.com)
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23. H.323 Call Release
Figure 8 (ref: www.iec.com)
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24. 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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25. 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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