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