Voip Ppt Final 1

7/28/2019 Voip Ppt Final 1

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VoIP

PRESENTED BY

Ankit Aggarwal

M.Tech 3rd Sem

(Digital Comm.)


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An Introduction to Telephone

The first telephone was invented in 1876 by Alexander

Graham Bell.

The first phone company was started in 1879

( International Bell Telephone Company (IBTC) and nowknown as American Telephone & Telegraph Company

AT&T).Slogan A phone in every household.

The device which allows conversation to two or moreusers when they are not in the same vicinity of each

other to be heard directly.

Earlier telephones were based on analog communication.


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VoIP

A recent application of Internet technology

Voice over IP (VoIP) which meansTransmission of voice over Internet

Introduction of VoIP in 1995 by Vocaltec Inc.

The use of the Internet that was originallydesigned to carry computer data to carry

voice

Voice over Internet Protocol Also known as :

Next Generation Voice Network

IP Telephony

Voice over Internet

Voice over Internet Protocol

Voice over Packet


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Why we need VoIP? Low cost.

Not only voice but also video is transmitted usingsimilar concepts.

Spreads at a fast pace

Independent

No geographical restriction


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A Basic IP Telephone System

The simplest IP telephone system uses two basic components:

-IP telephone: end device allowing humans to place and receive calls.-Media Gateway Controller: providing overall control and coordinationbetween IP phones; allowing a caller to locate a callee


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Interconnection IP telephone system needs to interoperate with PSTN or

another IP telephone system.

Two additional components needed for suchinterconnection: Media Gateway

Signaling Gateway

Media Gateway - translates audio between IP network and PSTN.

Signaling Gateway - translates signaling operations.


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How VoIP works?

Converting the voice signalADC (analog to digital)

DAC (digital to analog)

Voice (source) - - ADC - - - Internet - - - DAC - - Voice (dest)

Transmission of voice traffic in packets


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VoIP Components

Encoder

Packetizer

Playback Buffer

Decoder

Encoder Packetizer

Sender Receiver

NetworkPlayback

Buffer

Depacketizer Decoder


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Programmable buttons

Foot stand adjuster

Display button

Message button

Directories button

Help button

Settings button

Services button

Volume button

VoIP Phone

Speaker button

Mute button

Headset button

Navigation button

Keypad

Softkey buttons

Handset light strip

Touchscreen

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Advantages

Use computer and phone at same time

Do not need multiple phone lines

Unlimited talking time world wide

Local, long distance, international calls all the sameprice

Talk with several people at same time with noadditonal cost


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Disadvantages

Some VoIP services do not work during power outages

If a remote site fails connections may be unreachable

If there is congestion in the network it may cause delays, and increasedpacket loss


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Various Issues in designing

network The most important factors in the designing of the

network is

Service It is essential for maintaining customersatisfaction.

Cost A factor which is always involve in maintaining

profitability.


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What is Traffic

Traffic is defined as either the amount of data or

the number of messages over a circuit during a

given period of time.

It is also defined as the relationship between the

call attempts and the speed with which the calls

are completed.


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The most important factors that should be taken into the

account when analyzing the traffic -

Traffic Load measurement

Grade of Service

Traffic Types

Sampling Methods


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Factors in analysing the voip

traffic

There are following factors

Voice Codecs

Samples

Voice Activity Detection

RTP Header Compression

Call Arrival Patterns


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Various Issues in Analyzing VoiP

Traffic Delay Jitter - The delay experienced in receiving a

packet when a packet is expected to arrive at the endpoint at a certain time

Latency - The time taken for a packet to arrive at itsdestination

Bandwidth It is to be shared between voice andcomputer data

Packet loss - It is not acceptable

Reliability

Scalability Ability to add more telephone instruments

Security As it uses internet therefore it is vulnerableto the security risks.


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Analyzing VoiP by Vbuzzer

A type of soft phone system by which we can analyze the

VoiP system.

It is an internet telephony software which is not designed

to simply duplicate the traditional telephone system.

Users can send and receive voice calls to or from otherVbuzzer users on the internet.


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PC PCNetwork

Vbuzzer Vbuzzer

Vbuzzer test bed setup


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Call Setup Process in Vbuzzer

Vbuzzer

Caller

Proxy

Server

Vbuzz

erCallee

Invite Invite

100 Trying

180 Ringing

200 OK

ACK

200 OK

180 Ringing

100 Trying

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