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  1. 1. Voice Over IP Presented By Dhara Patel Jay Patel 21-Feb-2013 Page 1
  2. 2. Voice Over IP Overview VOIP uses the Internet Protocol (IP) to transmit voice as packets over an IP network. VOIP can be achieved on any data network that uses IP, like the Internet, Intranets and Local Area Networks (LAN). The voice signal is digitized, compressed and converted to IP packets and then transmitted over the IP network. VOIP services need only a regular phone connection, while others allow you to make telephone calls using an Internet connection instead.    Page 2
  3. 3. Voice Over IP Definition of VOIP VOIP is a technology that allows telephone calls to be made over computer networks like the Internet. Page 3
  4. 4. Voice Over IP Continue… VoIP converts analog voice signals into digital data packets and supports realtime, two-way transmission of conversations using Internet Protocol (IP). Page 4
  5. 5. Voice Over IP What is VOIP? VoIP is actually a very simple technology. But it is also powerful and as you will see it can save you substantial money over conventional phone calls via your usual telephone operator (Telkom) that basically does the same thing, but using their own network to route your calls. Page 5
  6. 6. Voice Over IP Why VoIP?        Can make and receive calls with / without a computer Can surf the net while making calls Can make local / long distance calls Supports both the Voice and Data Integrates other media like Video, Electronic White Board Flexibility Reliable Services Page 6
  7. 7. Voice Over IP How does VOIP work ?  You place your call by dialing a telephone number to any normal telephone number anywhere in the world.  A connection between you and the dialed number is then established.  As you talk into your telephone handset your voice is converted into digital data.  This data is then transmitted across the connection that you have already established by dialing the other parties telephone number. Page 7
  8. 8. Voice Over IP Continue…  The data is routed across the Internet using the same standard computer language that the Internet uses - which is called Internet Protocol (all computers connected to the Internet understand and use this language to communicate).  The data that was your voice is reconstituted on the other side into normal analogue sound that human beings understand. Page 8
  9. 9. Voice Over IP Continue…  VoIP calls can be made on the Internet using a VoIP service provider and standard computer audio systems. Alternatively, some service providers support VoIP through ordinary telephones that use special adapters to connect to a home computer network.  Many VoIP implementations are based on the H.323 Protocol. Page 9
  10. 10. Voice Over IP Protocols :  Voice over IP has been implemented in various ways using both proprietary and open protocols and standards. Examples of the network protocols used to implement VoIP include: H.323 Media Gateway Control Protocol (MGCP) Session Initiation Protocol (SIP) Real-time Transport Protocol (RTP) Session Description Protocol (SDP) Inter-Asterisk eXchange (IAX) Jingle XMPP VoIP extensions Page 10
  11. 11. Voice Over IP – RFC 3714 What is H.323 protocol? The H.323 protocol was one of the first VoIP protocols that found widespread implementation for long-distance traffic, as well as local area network services. However, since the development of newer, less complex protocols such as MGCP and SIP, H.323 deployments are increasingly limited to carrying existing long-haul network traffic. In particular, the Session Initiation Protocol (SIP) has gained widespread VoIP market penetration. Page 11
  12. 12. Voice Over IP H.323 Protocol  An International Telecommunications Union (ITU) standard that provides specification for computers, equipment, and services for multimedia communication over packet based networks that defines how real-time audio, video and data information is transmitted.  H.323 is commonly used in VoIP, Internet Telephony, and IP-based videoconferencing. Users can connect with other users over the Internet and use arying products that support H.323. This standard is based on the Internet Engineering Task Force (IETF) Real-Time Protocol (RTP) and Real-Time Control Protocol (RTCP), with additional protocols for call signaling , and data and audiovisual communications. Page 12
  13. 13. Voice Over IP Page 13
  14. 14. Voice Over IP Process of VOIP  The users voice (or fax) is converted into a digital signal, compressed, and broken down into a series of packets. The packets are then transported over private or public IP networks and reassembled and decoded on the receiving side. At the receiving end, the re-assembled packets arrive as a normal sounding voice call. Packet switching is very efficient. It lets the network route the packets along the least congested and cheapest lines. It also frees up the two computers communicating with each other so that they can accept information from other computers, as well. Page 14
  15. 15. Voice Over IP Continue…  Once the sound is recorded by the computer and compressed into very small samples, the samples are collected together into larger chunks and placed into data packets for transmission over the IP network.  This process is referred to packetization. Generally, a single IP packet will contain 10 or more milliseconds of audio, with 20 or 30 milliseconds being most common. Page 15
  16. 16. Voice Over IP Ways Of Using VoIP PC to PC PC to Phone Phone to PC Phone to Phone Page 16
  17. 17. Voice Over IP Diagrams Page 17
  18. 18. Voice Over IP Conceptual Model Page 18
  19. 19. Voice Over IP The phone works – why bother with VoIP user perspective carrier perspective variable compression: tin can to broadcast quality  no need for dedicated lines better codecs + silence suppression – packet header overhead = maybe reduced bandwidth security through encryption shared facilities simplify management, redundancy caller & talker identification advanced services better user interface (more than 12 keys, visual feedback, semantic rather than stimulus) cheaper bit switching no local access fees (but dropping to 1c/min for PSTN) fax as data rather than voiceband data (14.4 kb/s) adding video, application sharing is easy Page 19
  20. 20. Voice Over IP Advantages of VOIP Main advantage of VOIP is that the customer can make calls from anywhere in the world where broadband internet connection is available. Greater Efficiency. Another main advantage is the amount of money you end up saving on your phone bills as compared to a traditional phone line. Inexpensive and easy to use. Since it is simple, upgrading is relatively simpler too. You can integrate it with an existing phone connection. With VOIP PC-to-PC, calls are free no matter the distance and PCto-Phone charges are nominal. For a monthly fee you may make unlimited free calls within a geographic area. Page 20
  21. 21. Voice Over IP Continue…  You may purchase a number in a geography area of your choice, which works out very cheap. If your relatives and friends live in Virginia and you moved to California, you may purchase a Virginia number and make local calls to your loved ones.  You may access your VOIP account just like your email Id from any where in the world as long as you have an internet phone. This makes it easy for those who travel frequently to make calls frequently to those back at home at local call rates, no matter where they are.  You may call or message or do both at the same time with VOIP services.  VOIP cost about half the cost of traditional phone services and it seems that the taxes and surcharges are much lower. Also your bill is easier to understand and it can be viewed via the Internet. Page 21
  22. 22. Voice Over IP Disadvantages You must have high-speed internet access in order to obtain VoIP phone service. Loss of service during outages. Without power VOIP phones are useless, so in case of emergencies during power cuts it can be a major disadvantage. With VOIP emergency calls, it is hard to locate you and send help in time.(Show video) Page 22
  23. 23. Voice Over IP Continue.. Some times during calls, there may be periods of silence when data is lost while it is being unscrambled. Latency and traffic. No standard protocol is applicable. Page 24
  24. 24. Voice Over IP Continue… VoIP packet loss occurs when a large amount of traffic on the network causes dropped packets. This results in dropped conversations, a delay in receiving the voice communication, or extraneous noise on the call. Page 25
  25. 25. Voice Over IP Threats / Risks Many of the threats associated with VoIP are similar to the threats inherent to any internet application. Internet users are already familiar with the nuisance of email abuse in the form of spam and phishing attempts. VoIP opens yet another pathway for these annoyances, which can lead to spam over internet telephony (SPIT), spoofing, and identity theft. Additionally, the confidentiality of VoIP conversations themselves has come into question, depending on service type or VoIP configuration.  Spam over internet telephony (SPIT)  Spoofing  Confidentiality concerns Page 26
  26. 26. Voice Over IP How to Protect Against Risks  Use and maintain anti-virus and anti-spyware programs.  Be cautious about opening files attached to email messages or instant messages.  Verify the authenticity and security of downloaded files and new software.  Configure your web browser(s) securely.  Use a firewall.  Identify, back-up, and secure your personal or financial data.  Create and use strong passwords.  Patch and update your application software.  If you are using a software VoIP application, consider using encryption software for both your installation and for those you wish to talk to. Page 27
  27. 27. Voice Over IP Continue…  The disadvantages of VOIP could be annoying, but their effects are relatively limited. The complaints of VOIP are usually tolerable if the callers are using a free service. As the technology is advancing, we will expect the VOIP quality will match the traditional telephone technology. These are some of advantages and disadvantages of VOIP. All said and done, we could say that the advantages of VOIP outweigh the disadvantages of it. Page 28
  28. 28. Voice Over IP Name confusion  Commonly used interchangeably:    Internet telephony Voice-over-IP (VoIP) IP telephony (IPtel)  Also: VoP (any of ATM, IP, MPLS)  Some reserve Internet telephony for transmission across the (public) Internet  Transmission of telephone services over IP-based packet switched networks  Also includes video and other media, not just voice. Page 29
  29. 29. Voice Over IP Page 30