ZoneFlex 7300 Series - VoIP Phones, VoIP Phone Systems & VoIP
VOIP
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Transcript of VOIP
VOICE OVER INTERNET PROTOCOL(VOIP)
Presented byJAASIR NAZIR WANI
M.Tech SE132262601006
PSTN (PUBLIC SWITCHED TELEPHONE NETWORK) Since the telephone was invented in the late 1800s,
telephone communication has not changed substantially. Known structure of conventional telephone network.
Chennai
PSTN
New Delhi
Call Direction
A CHANGE OF PERSPECTIVE
Traditional View
Telephony
Cable
Broadcast
Wireless
Data
A CHANGE OF PERSPECTIVE
Current View
Cable
Broadcast
Wireless
Telephony
Data
A CHANGE OF PERSPECTIVE
Reality
Data
EmailVoice
Web
VideoFile Transfer
Cable
Wire
les
s
Satellit
e
Fiber
Content
Devices
Apps
Users
WHAT IS VOIP VOIP allows you to make telephone calls using a
computer network, over a data network like the Internet.
VOIP is a technology whereby voice conversations are compressed digitized, encapsulate inside of IP packets and transported over a data network.
The main difference is that the traditional wired network we have been using for years allows only one caller per channel and VOIP compression allows many callers per channel.
Many names, different meaning to different people: Soft-switching Next Generation Voice Network IP Telephony Voice over Internet Voice over Internet Protocol Voice over Packet IP Communications
WHY NEED IP TELEPHONY Economic: (uses internet, IP routers...) Further savings: Because underlying
network infrastructure can be shared.a single set of equipment, wiring, network connection enough.Example: a company with reduced telephone
costs. Not only voice but also video: is transmitted
using similar concepts. Independent: Much larger selection of service
providers to provide voice and video communication services.
No geographical restriction!Located virtually anywhere in the world!
HOW DOES IT WORK Continuously sample audio Convert each sample to digital form Send digitized stream across Internet in
packets Convert the stream back to analog for
playback
VOIP technology (also called "Packet Switching") does not use direct connections.
As there is no direct connection, packets with different destinations may follow the same path, and those with the same destinations may follow divergent paths depending on network conditions.
ADVANTAGES USING VOIP RATHER PSTN? When you are using PSTN line, you typically pay for
time used to a PSTN line manager company: more time you stay at phone and more you'll pay. In addition you couldn't talk with other that one person at a time.
In opposite with VoIP mechanism you can talk all the time with every person you want (the needed is that other person is also connected to Internet at the same time), as far as you want (money independent) and, in addition, you can talk with many people at the same time.
At the same time, you can exchange data with people you are talking with, sending images, graphs and videos.
APPLICATION OF VOIP Enterprise Environment Application The Remote Worker / Branch Office
application The Residential Application
BASIC SYSTEM COMPONENTS OF VOIP
•CLIENTS•SERVERS•GATEWAYS
A general VOIP network
KEEP IN MIND! Challenge
Voice transmission delayCall setup: call establishment, call
termination, etc. Backward compatibility with existing PSTN
(Public Switched Telephone Network)
There are several communication schemes:
VOIP TO VOIP
Broadband Network
Call Direction
IP Protocol
VoIP VoIP
New York, USA New Delhi, India
VOIP TO POTS WITH INTERNET
Internet/Broadband
PSTN
Server/Gateway India
New York, USA New Delhi,India
Call Direction
IP Protocol
VoIP
VOIP TO POTS WITHOUT INTERNET
PSTN
Server/Gateway
India
New York, USA New Delhi, India
Call Direction
IP Protocol
VoIP
ENCODİNG, TRANSMİSSİON, AND PLAYBACK
Two groups have introduced standards for IP telephony International Telecommunications Union(ITU),
controls telephone standards. Internet Engineering Task Force(IETF), controls
TCP/IP standards.
CONT… Encoding: Pulse Code Modulation (PCM) Transmission: Real-Time Transport Protocol
(RTP)Note: RTP is not a tranport-layer protocol. It is a tranfer protocol that operates at Layer 5.
Each RTP message is encapsulated in UDP datagram, which is then encapsulated in an IP datagram for transmission.
WHY UDP İNSTEAD OF TCP? Higher overhead of TCP does not make sense for
telephone call. Because audio must stream! No wait for missing packets. Play missing part as silence.
UDP Offerrs best-effort delivery, to handle duplication, delay, out-of-order delivery.
Each RTP message contains: A sequence number A real-time clock value
WHAT DOES REAL-TİME CLOCK VALUE DO? Allows a receiver to construct the exact
temporal sequence of the data. İf a packet is missing , the receiver knows exactly
how long to wait before starting to play the next packet
CONCLUSION VOIP means Voice Over Internet Protocol, or
Voice over Internet, IP Telephony. Hot area both in research and market because
of low cost. Challenge in backward compatibility with PSTN. It uses UDP instead of TCP for voice
transmission. It follows the standards of ITU and IETF.
THANK YOU