2909569 Voice Over Internet Protocol

8/12/2019 2909569 Voice Over Internet Protocol

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SEMINAR REPORT

ONVOICE OVER INTERNET PROTOCOL

CONTENTS

1) INTRODUCTION

2) WHAT IS VoIP ?

3) REQUIREMENT OF VoIP

4) HOW VoIP WORKS ?

a) Ho VoIP o!"# $a!% 1

&) Ho VoIP o!"# $a!% 2

') Ho VoIP o!"# $a!% 3() Ho VoIP o!"# $a!% 4

) PROS AND CONS OF VoIP

*) CONCLUSION


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INTRODUCTION

VoIP (voice over IP - that is, voice delivered using the Internet Protocol)

is a ter used in IP tele!hon" #or a set o# #acilities #or anaging the

deliver" o# voice in#oration using the Internet Protocol (IP)$ In general,

this eans sending voice in#oration in digital #or in discrete !ac%ets

rather than in the traditional circuit-coitted !rotocols o# the !u&lic

s'itched tele!hone net'or% (PSTN)$ A aor advantage o# VoIP and

Internet tele!hon" is that it avoids the tolls charged &" ordinar"

tele!hone service

VoIP is there#ore tele!hon" using a !ac%et &ased net'or% instead o# the

PSTN (circuit s'itched)$

uring the earl" *+s the Internet 'as &eginning its coercial s!read$

The Internet Protocol (IP), !art o# the TP.IP suite (develo!ed &" the

/$S$ e!artent o# e#ense to lin% dissiilar co!uters across an"

%inds o# data net'or%s) seeed to have the necessar" 0ualities to

&ecoe the successor o# the PSTN$

The #irst VoIP a!!lication 'as introduced in 1**2 - an 3Internet Phone3$

An Israeli co!an" &" the nae o# 3VocalTec3 'as the one develo!ing

this a!!lication$ The a!!lication 'as designed to run on a &asic P$ The


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idea 'as to co!ress the voice signal and translate it into IP !ac%ets #or

transission over the Internet$ This 3#irst generation3 VoIP a!!lication

su##ered #ro dela"s (due to congestion), disconnection, lo' 0ualit"

(&oth due to lost and out o# order !ac%ets) and inco!ati&ilit"$

VocalTecs Internet !hone 'as a signi#icant &rea%through, although the

a!!lications an" !ro&les !revented it #ro &ecoing a !o!ular

!roduct$ Since this ste! IP tele!hon" has develo!ed ra!idl"$ The ost

signi#icant develo!ent is gate'a"s that act as an inter#ace &et'een IP

and PSTN net'or%s$

W+a% ,# Vo,'- O.-! IP?

Voice over IP (VoIP) is a &lan%et descri!tion #or an" service that delivers

standard voice tele!hone services over Internet Protocol (IP)$ o!uters

to trans#er data and #iles &et'een co!uters norall" use Internet

!rotocol$

3Voice over IP is the technolog" o# digiti4ing sound, co!ressing it,

&rea%ing it u! into data !ac%ets, and sending it over an IP (internet

!rotocol) net'or% 'here it is reasse&led, deco!ressed, and converted

&ac% into an analog 'ave #or$$3 The transission o# sound over a

!ac%et s'itched net'or% in this anner is an order o# agnitude ore

e##icient than the transission o# sound over a circuit s'itched net'or%$

As entioned &e#ore, VoIP saves &and'idth also &" sending onl" the

conversation data and not sending the silence !eriods$ This is a


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considera&le saving &ecause generall" onl" one !erson tal%s at a tie

'hile the other is listening$ 5" reoving the VoIP !ac%ets containing

silence #ro the overall VoIP tra##ic 'e can reach u! to 2+6 saving$ In

a circuit s'itched net'or%, one call consues the entire circuit$ That

circuit can onl" carr" one call at a tie$

In a !ac%et s'itched net'or%, digital data is cho!!ed u! into !ac%ets,

sent across the net'or%, and reasse&led at the destination$ This t"!e o#

circuit can accoodate an" transissions at the sae tie &ecause

each !ac%et onl" ta%es u! 'hat &and'idth that is necessar"$$ Internet

Tele!hon" si!l" ta%es advantage o# the e##iciencies o# !ac%et s'itched

net'or%s$

7ate'a"s are the %e" co!onent re0uired to #acilitate IP Tele!hon"$

A gate'a" is used to &ridge the traditional circuit s'itched PSTN 'ith

the !ac%et s'itched Internet$


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The gate'a" allo's the calls to trans#er #ro one net'or% to the other

&" converting the incoing signal into the t"!e o# signal re0uired &" the

net'or% it is re0uired to send it on$ 8or e9a!le, A P user 'ishes to

call soeone using a conventional !hone$ The P sends the IP !ac%ets

containing digiti4ed voice to the gate'a"$

R-/0,!--%# o a VoIP

The re0uireents #or i!leenting an IP Tele!hon" solution to su!!ort

Voice Over IP varies #ro organi4ation to organi4ation, and de!ends on

the vendor and !roduct chosen$ The #ollo'ing section ais to identi#"

the #undaental re0uireents in the general case and is s!lit into :

sections;

So#t'are Re0uireents


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Vo,'- P!o'-##, Mo(05-6This as!ect o# the so#t'are is re0uired to

!re!are voice sa!les #or transission$ The #unctionalit" !rovided &"

the voice !rocessing odule should su!!ort;

A PCM I%-!a'- is re0uired to receive sa!les #ro the tele!hon"

inter#ace (e$g$ a voice card) and #or'ard the to the Voice Over IP

so#t'are #or #urther !rocessing$

E'+o Ca'-55a%,o is re0uired to reduce or eliinate the echo

introduced as a result o# the round tri! e9ceeding 2+ illiseconds$

I(5- No,#- D-%-'%,ois re0uired to su!!ress !ac%et transission on the

net'or% 'hen there are no voice signals to &e sent$ This hel!s to reduce

net'or% tra##ic as u! to =+6 o# voice calls are silence and there is no

!oint in sending silence$

A To- D-%-'%o! is re0uired to discriinate &et'een voice and #a9

signals &" detecting TM8 (ial Tone Multi #re0uenc") signals$

T+- Pa'"-% Vo,'- P!o%o'o5is re0uired to enca!sulate co!ressed voice

and #a9 data #or transission over the net'or%$


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A Vo,'- P5a7&a'" Mo(05- is re0uired at the destination to &u##er the

incoing !ac%ets &e#ore the" are sent to the odec #or deco!ression$

Ca55 S,a5, Mo(05-$ This is re0uired to serve as a signaling gate'a"

'hich allo's calls to &e esta&lished over a !ac%et s'itched net'or% as

o!!osed to a circuit s'itched net'or% (PSTN #or e9a!le)$

Pa'"-% P!o'-##, Mo(05-$ This odule is re0uired to !rocess the

voice and signaling !ac%ets read" #or transission on the IP &ased

net'or%$

N-%o!" Maa--% P!o%o'o5$ Allo's #or #ault, accounting and

con#iguration anageent to &e !er#ored$

Ha!(a!- R-/0,!--%#

The e9act hard'are, 'hich 'ould &e re0uired, again, de!ends on

organi4ational needs and &udget$ The list &elo' highlights the ost

general hard'are re0uired$

The ost o&vious re0uireent is the e9istence (or installation) o# an IP

&ased net'or% 'ithin the &ranch o##ice gate'a" is re0uired to &ridge the

di##erences &et'een the !rotocols used on an IP &ased net'or% and the

!rotocols used on the PSTN$


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The gate'a" ta%es a standard tele!hone signal and digiti4es it &e#ore

co!ressing it using a odec$ The co!ressed data is !ut into IP

!ac%ets and these !ac%ets are routed over the net'or% to the intended

destination$

The Ps attached to the IP &ased net'or% re0uire the voice.#a9 so#t'are

outlined a&ove$ The" also re0uire 8ull u!le9 Voice ards 'hich allo'

&oth counicating !arties to s!ea% at the sae tie - as o#ten ha!!ens

in realit"$

As an alternative to installing Voice ards, IP Tele!hones can &e

attached to the net'or% to #acilitate Voice Over IP$ A secondar" gate'a"

should &e considered as a &ac%u! in the event o# the #ailure o# the

!riar" gate'a"$

P!o%o'o5 R-/0,!--%#

There are an" !rotocols in e9istence &ut the ain ones are considered

to &e the #ollo'ing;

H6323 is an IT/ (International Telecounications /nion) a!!roved

standard 'hich de#ines ho' audio .visual con#erencing data is

transitted across a net'or%$ : relies on the RTP (Real-Tie

Trans!ort Protocol) and RTP (Real Tie ontrol Protocol) on to! o#


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/P (/ser atagra Protocol) to deliver audio streas across !ac%et

&ased net'or%s$

8692361 de#ines ho' an audio signal 'ith a &and'idth o# :$?@:$1 re0uires a ver" lo' transission rate and delivers near

carrier class 0ualit"$ The VoIP 8oru as the &aseline odec #or lo' &it

rate IP Tele!hon" has chosen this encoding techni0ue$

869116The IT/ standardised PM (Pulse ode Modulation) as 7$11$

This allo's carrier class 0ualit" audio signals to &e encoded #or

transission at data rates o# 2=@&!s or =?@&!s$ 7$11 uses A-Ba' or

Mu-Ba' #or a!litude co!ression and is the &aseline re0uireent #or

ost IT/ ultiedia counications standards$

R-a5:T,- T!a#$o!% P!o%o'o5 (RTP) is the standard !rotocol #or

streaing a!!lications develo!ed 'ithin the IET8 (Internet Engineering

Tas% 8orce)$

R-#o0!'- R-#-!.a%,o P!o%o'o5(RSVP) is the !rotocol 'hich su!!orts

the reservation o# resources across an IP net'or%$ RSVP can &e used toindicate the nature o# the !ac%et streas that a node is !re!ared to

receive$


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Ho VoIP o!"#


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Ho VoIP o!"# ; Pa!% 1

Bet us loo% at ver" si!le VoIP call$ onsider t'o VoIP tele!hones

connected via an IP net'or% $In this e9a!le &oth VoIP tele!hones are

connected to a local BAN$ Sall"Cs !hone has an IP address o#

1*>$1=D$1$1 ,5illCs !hone is 1*>$1=D$1$>, the IP addresses uni0uel"

identi#" the tele!hones$ 5oth our !hones are con#igured to use a 'idel"

used VoIP standard called :$

5ill 'ants to tal% to Sall" and his !hone %no's the IP address o# Sall"Cs

!hone$ 5ill li#ts the handset and dials Sall", the !hone sends a call

setu! re0uest !ac%et to Sall"s !hone, Sall"Cs !hone starts to ring, and

res!onds to 5ills !hone 'ith a call !roceeding essage$ hen Sall"

li#ts the handset the !hone sends a connect essage to 5ills !hone$ The

t'o !hones 'ill no' e9change the data !ac%ets containing the s!eech$

At the end o# the call 5ill re!laces his handset and !hone sto!s sending

voice data sends a disconnect essage and Sall"s !hone res!onds 'ith a

release essage$ The call is no' co!lete$ all the essages contain the

F*:1 ISN !rotocol$


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Ma,


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and re0uires iniu training$ The onl" ne' e0ui!ent re0uired is a

gate'a" at each o##ice$ Voice 0ualit" is good, &ecause the co!an" has

control over the &and'idth$

D,#a(.a%a-6E9tra &and'idth a" &e re0uired &et'een o##ices, 'hich

o##set the savings$

Other #actors$$$ The carrier !roviding the intero##ice &and'idth 'ill

alost certainl" o##er an alternative solution including anageent o#

the internal tele!hone tra##ic$

IP P> A traditional Private 5ranch E9change (P5G) connects all the

!hones 'ithin an organi4ation to the !u&lic tele!hone net'or%$

Essentiall" IP P5G re!laces all the internal !hones 'ith VoIP

tele!hones$ The IP P5G has standard tele!hone trun% connections to the

!u&lic tele!hone net'or%$ The IP P5G is a P5G 'ith VoIP, &ut it also


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has the a&ilit" to su!!ort VoIP over the Internet and O##ice to O##ice

VoIP$

A(.a%a-#6Single ca&le in#rastructure$ The technolog" is trans!arent

to the user, and re0uires iniu training$ 8uture !roo# technolog"$

D,#a(.a%a-#$ Priaril" use#ul #or 7reen#ield sites, &ut can &e ada!ted

to 'or% 'ith e9isting technolog"$

$

Ho VoIP o!"# $a!% 2 ; T+- P!o%o'o5#$

I have ade an assu!tion that &oth ends o# a VoIP tele!hone

conversation are co!ati&le$ This co!ati&ilit" onl" ha!!ens i# &oth

ends agree to use the sae !rotocol$ All anu#acturers 'ho clai to &e

!roducing industr" standard voice over IP either su!!ort SIP or :

!rotocol$

So +a% ,# H6323 ?

Over the ne9t #e' "ears, the industr" 'ill address the &and'idth

liitations &" u!grading the Internet &ac%&one to as"nchronous trans#er

ode (ATM), the s'itching #a&ric designed to handle voice, data, and


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video tra##ic$ Such net'or% o!tii4ation 'ill go a long 'a" to'ard

eliinating net'or% congestion and the associated !ac%et loss$ The

Internet industr" also is tac%ling the !ro&les o# net'or% relia&ilit" and

sound 0ualit" on the Internet through the gradual ado!tion o# standards$

Standards-setting e##orts are #ocusing on the three central eleents o#

Internet tele!hon"; the audio codec #oratH trans!ort !rotocolsH and

director" services$

H6323 Ca55 S-/0-'- ;


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As such, : addresses the core Internet-tele!hon" a!!lications &"

de#ining ho' dela"-sensitive tra##ic, (i$e$, voice and video), gets !riorit"

trans!ort to ensure real-tie counications service over the Internet$

(The ? s!eci#ication de#ines the trans!ort o# voice, data, and video

over regular tele!hon" net'or%s, 'hile + de#ines the !rotocols #or

trans!orting voice, data, and video over integrated services digital

net'or% (ISN)$

Ho VoIP o!"# $a!% 3; E'o(,

The call control !art o# : sets u! the !araeters #or the #ull du!le9

voice !ath &et'een source tele!hone and destination tele!hone$ I 'ill

continue 'ith " analogies to e9!lain ho' "our voice gets trans!orted

across the Internet$

In ters o# : there is a trade o## &et'een call 0ualit" and

&and'idth, in general the higher the 0ualit" the greater the &and'idth

re0uired

uring the call setu! !ortion o# : the !hones have to decide 'hich

s!eech encoder.decoder to use 'hen the" send the s!eech to the other

!hone, 5ill and Sall" &oth have !hones that su!!ort 7$>:$1, 7$11 and7>*$

The ain di##erence &et'een each o# these encoders is the aount o#

&and'idth the" use, 7$11 uses =?%&it.s and 7$>:$1 can use as little as


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2$:%&it.s$ Although it 'ould see o&vious to use the encoder 'ith the

lo'est &and'idth, there is a loss o# 0ualit" 'ith a lo'er &and'idth$$ At

the sae tie a strea o# 7>:$1 encoded voice data starts &eing sent

#ro each !hone to the other !hone$

Ho VoIP o!"# $a!% 4 ;H-a! %+- Q0a5,%76

The !er#orance o# the s!eech encoders at each end, the nu&er o#

!ac%ets lost on route, Batenc" and itter$

I have alread" tal%ed a&out the encoders in the !revious

section$ I also &undle into the encoding !rocess echo su!!ression$ In the

earl" da"s o# voice calls via satellite there 'ould &e an anno"ing echo$

As the technolog" i!roved the echo disa!!eared$ Echo su!!ression is

ver" %e" to good 0ualit" VoIP calls $ I do not d'ell on the su&ect since

the atheatics is &e"ond " co!rehension$ 7ood echo su!!ression

a%es #or 0ualit" calls$

5e 'arned that &ecause a anu#acturer has a 7$>:$1 encoder it

a" not sound the sae as another anu#acturer 'ho clais to have

7$>:$1, 0ualit" does var"$ As a general rule the occasional lost !ac%et

'ill not a##ect too drasticall" the 0ualit" o# a call, &ut lose 2 in a ro' and

an entire 'ord is lost and this 'ill &e a !ro&le$ So i# "ou are going to

have lost !ac%ets a%e sure the" are onl" lost in a regular distri&utedanner$ 26 lost !ac%ets distri&uted evenl" 'ill not result in the loss o#

'ords lose 26 o# the 'ords &" clustering the !ac%ets and the e##ect is

&ad$


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PROS AND CONS ;

A(.a%a-# o VoIP

There are an" advantages to &e gained #ro i!leenting an IP

Tele!hon" solution 'ithin the organi4ation$ The #ollo'ing list ais to

highlight soe o# the advantages o# such a strateg";

S,5- -%o!" ,!a#%!0'%0!-$ hen installing VoIP in the o##ice onl"

a single ca&le is re0uired to the des%, #or &oth tele!hone and data$

Eliinating se!arate tele!hone 'iring$

VoIP 0#-# @#o%@ #,%'+,'hich eliinates ost o# the legac" P5G

e0ui!ent$ Reducing the cost o# installing a counications in#ra-

structure and the aintenance cost once installed$

S,$5- 0$!a(- $a%+6The VoIP P5G technolog" is so#t'are &ased$

It is easier to e9!and, u!grade and aintain than its traditional tele!hon"

counter!arts$

>a(,(%+ -,',-'76 VoIP can co!ress ore voice calls into

availa&le &and'idth than legac" tele!hon"$$ IP Tele!hon" hel!s to

eliinate 'asted &and'idth &" not trans!orting the =+6 o# noral

s!eech 'hich is silence

IP - the underl"ing !rotocol : ,# #0$$o!%-( &7 o#% $5a%o!#and is

inde!endent o# the trans!ort !rotocol used$


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O57 o- $+7#,'a5 -%o!" ,# !-/0,!-( %o (-a5 ,%+ &o%+ .o,'-aB

and data tra##ic instead o# t'o !h"sical net'or%s$


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W+,5- #o- #%a(a!(# +a.- &-- #-% &7 %+- ITU %+- %-'+o5o7 ,#

o% #ull" standardi4ed and there is no guarantee that !roducts #ro

di##erent vendors 'ill &e intero!era&le$ Soe vendors are tr"ing to

resolve this !ro&le &" #oring grou!s and a%ing guarantees a&out

the !roducts in the grou! &ut this is onl" a !artial solution - vendors

out'ith the grou! cannot guarantee intero!era&ilit"$

H-a.7 'o-#%,o o %+- -%o!" 'a !-#05% , 'o#,(-!a&5-

(-!a(a%,oo# service as IP is not good at !roviding FoS (Fualit" o#

Service) guarantees$ 8eed&ac% to Bucent Technologies custoers re#lect

this 'orr"$ Maor co!anies are !lanning to install IP Tele!hon"

ca!a&ilities at soe !oint and have carried out initial investigations,

ho'ever;

Since onl" one !h"sical net'or% #or &oth data and voice.#a9

transissions is re0uired, #ailure o# the net'or% could &e catastro!hic, as

all counications ca!a&ilities are lost$

O$$o!%0,%,-#

Man" vendors o##er the a&ilit" to incor!orate Virtual Private Net'or%ing(VPN) 'ith relative ease into the IP Tele!hon" solutions the" !rovide$

This allo's an" transission to &e encr"!ted using a nu&er o#

cr"!togra!hic techni0ues and !roviding securit" &" transitting the


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counications through a tunnel 'hich is set u! using PPTP (Point-to-

Point Tunneling Protocol) &e#ore coencing counications$

IP Tele!hon" allo's co!anies to e9!loit o!uter Tele!hon"

Integration to its #ull e9tent$

The convergence o# counications technologies allo's greater control

over counications, ost vendors !rovide logging and accounting

#acilities 'here&" all usage can &e onitored$

Co'50#,o ;

ithout a dou&t, the data revolution 'ill onl" gain oentu in the

coing "ears, 'ith ore and ore voice tra##ic oving onto data

net'or%s$ Vendors o# voice e0ui!ent 'ill continue to develo!

integrated voice and data devices &ased on !ac%eti4ed technolog"$ /sers

'ith u&i0uitous voice and data service integrated over one universal

in#rastructure 'ill &ene#it #ro true, sealess, trans!arent inter'or%ing

&et'een voice and all t"!es o# data$

REFRENCES;


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16 Co$0%-! N-%o!"# &7 A(!- S6Ta-&a0

26 I%-!-%o!", ,%+ TCPIP &7 Do05a# E6'o-!

36 6,-'6o!6'o

46 6%-5o76'o

6 6!a(6'o

*6 6a,5%o;&5a-!#5,#60%-Ba#6-(0


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2909569 Voice Over Internet Protocol

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