Tuesday, August 18, 2009

VOIP-Voice Over Internet Protocol(Download PPT,Abstract,Report)

1.INTRODUCTION
The public telephone network and the equipment that makes it possible are taken
for granted in most parts of the world. Availability of a telephone and access to a
low cost ,high quality worldwide network is considered to be essential in modern
society  .Anything  that  would  jeopardize  this  is  usually  since  more  and  more
communication  is  in digital  format and  transported via packet networks such as
IP,ATM cells etc. Since data  traffic  is growing much  faster  than  telephone  traffic,
there has been considerable interest in transporting voice over data networks.
Support  for  voice  communication  using  the  Internet  Protocol  (IP),  which  is
usually  just called  “voice over  IP” or VoIP, has been become especially attractive
given the cost, flat rate pricing of the public internet. In fact, toll quality telephone
over  IP has now become one of  the key  steps  leading  to  the  convergence of  the
voice,  video,  and  data  communication  industries.  The  feasibility  carrying  voice
and call signaling messages over the Internet has already been demonstrated but
delivering  high  quality  commercial  products,  establishing  public  services,  and
convincing users to buy in to the vision are just beginning.
VoIP can be defined as  the ability make telephone calls and  to send  facsimiles or
IP based data networks with suitable quality of service (QoS) and much superior
cost / benefit. Equipments producers   see VoIP   as a new opportunity to innovate
compete.  The  challenge  for  them  is  turning  this  vision  in  to  reality  by  quickly
developing  new  VoIP  enabled  equipments.  For  Internet  service  providers  the

possibility of introducing usage based pricing and increasing their traffic volumes
is  very  attractive.  Users  are  seeking  new  types  of  integrated  voice  /  data
application as well as cost benefits.
Success  fully  delivering  voice  over  packet  networks  precedence  a  tremendous
opportunity;  however,  implementing  the  products  is  not  as  straight  forward  a
task as it may first appear.
2. INTERGRATION OF IP & PSTN
Using VoIP we can communicate from PC to any other device – PC, phone, internet
phone, PDA, etc.
   1.PC-PC: we can community  from one PC to another PC using VoIP  i.e. voice mail
or  voice  chat.  For  this  PC  with  headphone,  a microphone  and  sound  card  are
required.
   2.PC-  Phone:  Allows  PC  user  to  establish  a  call  with  conventional  phone.  This
facility  enables  us  to  make  long  distance  a  call  with  rate  cheaper  than
conventional telephone call. 
  3.Phone  –  Internet Phone: Extension of PC  to phone  architecture. The  IP phone
connects  to  the  Internet  through a cable or DSL modem using an RJ-45 Ethernet
jack.
   3. PSTN vs. INTERNET.  
To understand Internet telephony or VoIP,  it  is necessary  to be  familiar with  the
fundamental  principles  behind  the  Internet  and  how  it  compares  to  PSTN.

Although  the  Internet  shares  some  characteristics  of  the  PSTN,  it  also  has
significant differences.
Computer  to  computer  data  communication  was  far  cheaper  than  voice
communication  through  Internet. One of  the main  reasons  for  these  is  the basic
difference  in  the  technologies  used  for  voice  and  data  communication.  Voice
networks use  circuit  switching while data  network use packet  switching.   What
this  means  is  that  for  a  voice  conversation  to  happen,  one  complete  and
continuous  circuit  has  to  be  held  open  between  the  two  parties  during  the  full
duration of conversation, while for a data transmission such a continuous connect
is unnecessary.    In data  transmission,  the data  is  split  into  independent packets
that  can  take  alternate  rules  to  the  intended  destination,  where  they  are
reassembled.   In voice communication, circuit switching is used because it is able
to  handle  data  in  real  time.    Packet  switching,  on  the  other  hand,  can  lead  to
delays,  which  can  lead  to  considerable  degradation  in  the  quality  of  the
conversation.  
So  the networks when  their  separate ways  till  the Real  time Transport Protocol
(RTP) was developed.   RTP provides support for streaming audio and video over
computer networks. Unlike what its name seems to suggest, RTP does not ensure
real time delivery of data. Instead it provides mechanisms for times stamping the
packets and methods  for synchronizing data streams with time properties.   Thus
it became technically possible to send voice over the net. 

                         

 

 

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