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VOIP - Voice Over Internet Protocol

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VOIP - Voice Over Internet Protocol Powered By Docstoc
					Khalid Khursheed
  09-MBA-27
                     voip
• Real-time interactive
  audio/video application.
• Voice over ip,internet telephony.
• Idea- use internet as a telephone
   IDEA

  network with some additional
  capabilities.
• Instead of circuit switched
  packet switched is used.
• Two protocols-SIP,H.323
                     How it works.
• VoIP services convert your voice into
  a digital signal that travels over the
  Internet
• If you are calling a regular phone
  number, the signal is converted to a
  regular telephone signal.
• VoIP can allow you to make a call
  directly from a computer, a special
  VoIP phone, or a traditional phone
  connected to a special adapter.
            Devices required
• A broadband (high speed Internet)
  connection is required. This can be through a
  cable modem, or high speed services such as
  DSL or a local area network.
• A computer, adaptor, or specialized phone is
  required. Some VoIP services only work over
  your computer or a special VoIP phone, while
  other services allow you to use a traditional
  phone connected to a VoIP adapter
                      SIP
• Session initiation protocol
• An application layer that manages and
  terminates a multimedia session call.
• It can be used to create two party,multiparty or
  multicast sessions.
• SIP is designed to be independent of the
  underlying transport layer.
• SIP is a text based protocol as is HTTP.,uses
  messages.
                       SIP
                     messages




INVITE   ACK   BYE       OPTIONS   REGISTER   CANCEL
               SIP messages
• Each message has a header and a body.
• Header consist of several lines describe
  structure of message,callers capability.
• INVITE-caller initiates a session with invite
  message.
• ACK-After callee answers call,caller sends an
  ACK message for confirmation.
              SIP message
• BYE-it terminates a session.
• OPTIONS-message queries a machine about
  its capabilities.
• CANCEL-this message cancels an already
  started initialization process.
• REGISTER-this message makes a connection
  when the callee is not availabe.
                        SIP formats



 Sip:bob@201.23.45.78      Sip:bob@fhda.edu   Sip:bob@408-864-8900




Ip address               E-mail address       phone no.
               Simple sessions
 Simple session using SIP consists of three
 modules:
Establishing

Communicating

terminating
              Simple session
 Establishing a session-requires three way
  handshake.
Caller sends an INVITE message.
If callee is willing to start session,she sends a
  reply ,message.
To confirm that a reply code has been received
  the caller sends an ACK message.
               Continued..
• Communicating-after session has been
  established ,the caller and callee can
  communicate by using two temporary ports.

• Terminating the session-the session can be
  terminated with a BYE message sent by either
  party.

				
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Description: VOIP - Voice Over Internet Protocol