voip - study pd full

8/8/2019 VOIP - Study Pd Full

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TECH & FEATURES OF VOIP

(Voice Over Internet Protocol)


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VOIP allows us to make tollVOIP allows us to make toll--freefree

long distance voice and fax callslong distance voice and fax callsover existing IP data networksover existing IP data networks

instead of the public switchedinstead of the public switched

telephone networks (PSTN).VOIPtelephone networks (PSTN).VOIP

uses the Internet protocol (IP) touses the Internet protocol (IP) to

transmit Voice as packets over antransmit Voice as packets over an

IP network.IP network.

VOIP allows us to make tollVOIP allows us to make toll--freefree

long

distance voice and fax callslong distance voice and fax callsover existing IP data networksover existing IP data networks

instead of the public switchedinstead of the public switched

telephone networks (PSTN).VOIPtelephone networks (PSTN).VOIP

uses the Internet protocol (IP) touses the Internet protocol (IP) to

transmit Voice as packets over antransmit Voice as packets over an

IP network.IP network.


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To apprise you about the VOIP tech

and Its features


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INTERNET AND ITS TECH

OVERVIEW OF VOIP

VOIP TECHNOLOGY

REQR OF A VOIP SETUP


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In easy sayingIn easy sayingInternetInternet

is nothing but network ofis nothing but network of

networks. It certainly includes the multinational networks.networks. It certainly includes the multinational networks.

While browsing the internet, we type some addresses likeWhile browsing the internet, we type some addresses likewww.bangladesharmy.orgwww.bangladesharmy.org ororwww.hotmail.comwww.hotmail.com.. Let us seeLet us see

the process how we go to the corresponding web pages. Thisthe process how we go to the corresponding web pages. Thisis done in the following way :is done in the following way :

Client (User PC) -> ISP DNS SERVER -> Router/Gateway->

Other DNS Server/ Router/Gateway-> Web Server


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A protocol is a set of rules andA protocol is a set of rules andstandards that enable computers tostandards that enable computers to

Exchange information.Exchange information.


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Internet is virtually an endless horizon andInternet is virtually an endless horizon and

where a uniform address iswhere a uniform address is

needed to connect each other. The IPneeded to connect each other. The IP

addressing system provides us this facility.addressing system provides us this facility.It consists of 32 bits. So there can be 2It consists of 32 bits. So there can be 23232

(ie 4244967296) or 4 billion(ie 4244967296) or 4 billion

combinations. This 32 bits are arranged in thecombinations. This 32 bits are arranged in the

following fashion:following fashion:

xxxxxxxx . xxxxxxxx . xxxxxxxx . xxxxxxxxxxxxxxxx . xxxxxxxx . xxxxxxxx . xxxxxxxx


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0~ 255 . 0~255 . 0~255 . 0~255

ie

202.0.1.255 or 192.168.90.5

NETWORK

PART

HOST

PART

192. 168. 90. 5


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Routing, bridgingandswitchingare

methods of determining the best path a

transmission should take in order to reach its

destination, then directing the transmission to

that path.


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Client (User PC) -> ISP DNS SERVER -> Router/Gateway->Other DNS Server/ Router/Gateway-> Web Server

mail.yahoo.com 216.136.173.245

OTHER

NETWORKS

OTHER

NETWORKS

YAHOO MAIL

SERVER

DNS SERVER

216.136.173.245

ROUTER

ROUTER


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VOIP stands for 'VOIP stands for 'VV'oice 'oice oo'ver ''ver 'II'nternet ''nternet 'PP'rotocol.'rotocol.As the term says VOIP allows you to pass voiceAs the term says VOIP allows you to pass voice

through IP packets and through Internet.through IP packets and through Internet.

VOIP can use accelerating hardware to achieve this purposeVOIP can use accelerating hardware to achieve this purposeand can also be used in a PC environment. In otherand can also be used in a PC environment. In other

words "Voicewords "Voice--overover--IP" (VOIP) technology enablesIP" (VOIP) technology enables

the realthe real--time transmission of voice signals astime transmission of voice signals as

packetized data over "IP networks" that employ thepacketized data over "IP networks" that employ the

Transmission Control Protocol (TCP), RealTransmission Control Protocol (TCP), Real--TimeTimeTransport Protocol (RTP), User Data gram ProtocolTransport Protocol (RTP), User Data gram Protocol

(UDP), and Internet Protocol (IP) suite.(UDP), and Internet Protocol (IP) suite.


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VOICE(SOURCE) ADC

INTERNET

VOICE (DESTINATION)

DAC


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Almost free (Negligible expenditure).

Maximum utilization of available bandwidth.

Can exchange Voice/Video/Data/Graphs/Images simultaneously.

Facility of conference call.

Doesnt need a dedicated connection as it

is based on packet switching.

Point to multipoint communication.


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The delay during the conversationThe delay during the conversation

This delay mainlyThis delay mainlyoccurs due to netwok congestion.occurs due to netwok congestion. If theIf the

network is good then this problem cannetwork is good then this problem can

be eliminated.be eliminated.


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OVERVIEWOFVOIPCONNECTIONOVERVIEWOFVOIPCONNECTION

The ADC to convert analog voice to digital

signals (bits).

The bits have to be compressed in a good format

for transmission using different protocol.

Insert voice packets in data packets using a real-

time protocol (typically RTPover UDPover IP) .


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OVERVIEWOFVOIPCONNECTIONOVERVIEWOFVOIPCONNECTION

A signaling protocol to call users: ITU-T H323

does that.

At RX end, disassemble packets,extract datas,

then convert them to analog voice signals and sendthem to sound card (or any phone) .

All that must be done in a real time fashion cause

we cannot waiting for too long for a vocal answer!


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VOICE ADC COMPRESSIONALGORITHM

ASSEMBLING RTPINTCP/IP

DISASSEMBLING RTP FROMTCP/IP

DECOMPRESSIONALGORITHM DAC VOICE


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This is made by hardware, typically byThis is made by hardware, typically by

card integrated ADC.This also requires thecard integrated ADC.This also requires the

sound Card that we have in our PC or it can besound Card that we have in our PC or it can be

done by VOIP tel available in the market today.done by VOIP tel available in the market today.


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H323Network.H323Network.


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Gateway.Gateway.

Gatekeeper.Gatekeeper.

MCU. (MCU. (Multipoint Con UnitMultipoint Con Unit))

H323Network.H323Network.


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L 1- L6

10 BASE - TCOM

POWER SWITCH

100 240 V

AC


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PSTNPSTN

PSTNPSTN

GATEKEEPER

INTERNET


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RANGPUR

PABX

CTG

PABX

RANGAMATI

PABX

EXISTING TELECOM FACILITY

FMN TO AHQ/ FMN CONNECTION

DHAKA

PABX


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Drawbacks of Existing Telecom Facility

Engages via circuits/channel

Traffic congestion

Expensive


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INTERNET

RANGPUR CTG

64 kbps

RANGA-

MATI

8 X SUBSCRIBERS

64 kbps

DHAKA

8 X SUBSCRIBERS 8 X SUBSCRIBERS 8 X SUBSCRIBERS

TELECOMFACILITYWITHVOIPTECHNOLOGY


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Advantages of VOIP technology

Economic

No use of via mediam/ channel

Increased no of voice channel


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AHQ to Any Overseas Mission Area Connection


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Min expenditure per min

No use of via mediam/ channel

Increased no of voice channel

Advantages


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voip - study pd full

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