Post on 03-Jun-2018
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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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