by

P.Monika

10881A0479

Under the esteemed guidance by

Mr.Prof.Y.Pandu Rangaiah

Introduction

Why VoIP?

Architecture

Basic idea behind VoIP

Ways in which VoIP can be implemented

Devices in VoIP

Contents in VoIP

Quality of service

Advantages and disadvantages

Applications

Conclusion

References

(VoIP) stands for Voice over Internet protocol is

revolutionizing the world of communications. It allows you

to make and receive phone calls over the Internet and IP

networks for much cheaper than with the traditional

landline phone network.

It also makes your communication experience much richer

and nicer with a series of enhanced features and extended

possibilities.

With VoIP, we can make a call from anywhere if we have

broadband

Supports both voice and data.

Call routing.

Flexibility.

Reliability services

Continuously sample audio.

Convert each sample to digital form.

Send the resulting digitized stream accross an IP network in

packets.

Convert the stream back to analog for playback.

Before the procedure above, the system must handle call

setup. Phnumber to IP.

PC to PC

Phone to phone

Pc to phone

Access Lines (Local Loops):- Connects customer premises to the local voice switch.

Switches:- Connect access line to each other.

Trunks:- In telecommunications, trunking is a method for a system to provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually.

Pbx:- PBXs make connections among the internal

telephones of a private organization usually a business and

also connect them to the public switched telephone

network(PSTN) via trunk lines.

Router:- It is a device that forwards data

packets between computer networks, creating an

overlay internetwork

Router:-The device that forwards data packets between computer

networks, creating an overlay internetwork

ATA(analog telephone adapters):- A device which

converts analog signal from normal phone to digital signal

necessary for the transmission over internet.

PSTN:- PSTN is used only for analog phones

PSTN is connected to adapter which is further connected to PBX

DSL modem:- provide internet acess by transmitting data over the

wires of a local telephone network,

Cont.

VoIP servers

VoIP clients

VoIP Gateways

Codecs

VoIP protocols

Analog voice signal (sender)

Digital voice

Transmitted over the network

Analog voice signal(reciever)

VoIP server can be hardware or software.

Its duty is to conveying the voice and video data over

the data network like internet.

Responsible for call initiation and termination.

VoIP clients is also known as SIP clients.

It is a software application

It is normally installed on a users device to allow VoIP

calls

Cont.

VoIP gateways works as a bridge between PSTN and IP network.

Gateways are used for converting the analog data into digital IP

packets and vice versa for the transmission of the data through IP

network.

Gateway uses codec and IP protocols to work properly.

A voice codec is responsible for the compression of your voice

stream within a digital packet. It also determines sound quality

and bandwidth required to send the packet. A VoIP gateway

typically supports multiple voice codecs.

For eg: G.729 is an audio data compression algorithm for

voice that compresses digital voice in packets of 10 milliseconds

duration.

.

H.323 related protocol:- provides audio visual communication

network on any packet network.

Session Initiation Protocol(SIP):- signalling protocol used for

establishing sessions in an IP network.

Media Gateway Control Protocol(MGCP):- Coordinates

setup, handling and termination of media flows at the media gateway.

Media Gateway:- Terminates PSTN lines and packetizes media

streams for IP transport.

Real time transfer protocol:- VoIP phones use RTP to carry media

data over the internet.

RTP Control Protocol(RTPCP):- RTCP monitors the control

information for an RTP flow.

RTP is originated and received on even port numbers and the associated

RTCP communication uses the next higher odd port number.

SS7:- is a set of telephone signalling protocols which are being used to set

up most of the world's public switched telephone network(PSTN) telephone

calls. The main purpose is to set up and tear down calls.

Cont.

QoS (Quality of Service) is a major issue in VOIP implementations. The

issue is how to guarantee that packet traffic for a voice or other media

connection will not be delayed or dropped due interference from other

lower priority traffic.

Things to consider are:-

Latency: Delay for packet delivery

Jitter: Variations in delay of packet delivery

Packet loss: Too much traffic in the network causes the network to drop

packets

Burstiness of Loss and Jitter: Loss and Discards (due to jitter) tend to

occur in burst

Integration of voice and data

More bandwith

Cost reduction

Video conferencing

Fere IP to IP call

Phone line is down if braodband connection is down

Phone adapter and/or router should be occasionally

must be rebooted.

Voice quality degrades if internet connection has

latency, jitter or significant packet loss.

Skype

Nimbuzz

Yahoomessenger

Watsapp

Line

wechat

There are loads of benefits for using VoIP. One of the

main benefits is the cost efficiency.

Nowadays VoIP technology is generally used in all

offices for making long distance voice calls with

real time voice quality at low charges. So, VoIP

technology will be the best source for long distance

communication up to date.

VoIP technology will be the trend of future. Already,

more than 50 million people and businesses have begun

to subscribe to a VoIP phone provider.

[1]. Black, Uyless D ”Voice over IP”, 2nd ed. Upper Saddle River, NJ,

Prentice Hall, c2002. pp.314-316

[2]. ”VoIP in broadcast studio” by Michael Doch and Steve Church

[3]. Goralski, Walter, and Matthew C. Kolon.” IP telephony”. New York,

McGraw-Hill, c2000. 468 p.TK5105.8865.G67 1999

[4]. “ Internet telephony”, Lee W. McKnight, William Lehr, and David D.

Clark. Cambridge, C2001,pp.367-377.