Voice Over Internet Protocol (VoIP) Copyright © 2006 Heathkit Company, Inc. All Rights Reserved Presentation 1 – Introduction to VoIP

2 Objectives At the end of this presentation, you will be able to:

3 Define PSTN, POTS, Voice over Internet Protocol, VoIP, IP Telephony and convergence. List advantages and disadvantages of VoIP. Briefly discuss the history of VoIP. Discuss the role of the International Telecommunications Union (ITU) and the Internet Engineering Task Force (IETF) in the evolution of VoIP.

4 Voice Over Internet Protocol (VoIP) A technology that allows us to transmit and receive real-time voice as data packets over a network that uses Internet Protocol (IP). Voice communication over the same network traditionally used for data communication.

5 VoIP does not necessarily use the Internet. VoIP implementations include private intranets. Better control can be maintained on intranets.

6 Our Century-Old Telephone System PSTN – Public Switched Telephone Network POTS – Plain Old Telephone System

7 IP Telephony Refers to voice, fax, and any other “normal” phone service if that service is provided via Internet Protocol (IP) instead of the PSTN. Technically, VoIP and IP Telephony are not the same even though they are often used as if they were.

8 Convergence The merging of telephone and data networking. The technology of transmitting and receiving voice, data, and video over a single network. Allows telephony, real-time presentations, and conferencing over internet protocol.

9 International Telecommunications Union (ITU) An international organization within the United Nations System where governments and the private sector coordinate global telecommunications networks and services. The leading publisher of telecommunication technology, regulatory and standards information. Released the first major protocol for VoIP called H.323.

10 Internet Engineering Task Force (IETF) International community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. Developed and popularized a second major VoIP protocol called Session Initiation Protocol (SIP).

11 Advantages of VoIP Lower cost long distance telephone service. Convergence of voice, data, and video over a single network. Enables new telecommunications services.

12 Disadvantages of VoIP Voice quality not always up to the standards of the PSTN. More susceptible to power failures. Non uniform 911 response. Not compatible with alarm systems that rely on telephone lines. Equipment Interoperability.

13 Two Globe-Spanning Networks The telephone system The Internet

14 History of Internetworking Data over voice networks Development of dedicated digital services Voice over the Internet or over intranets.

15 Data over Voice Networks Popular since the 1960’s. Modems convert the digital data provided by computers into the analog signals required by the telephone system.

16 Development of Dedicated Digital Services Integrated Services Digital Network (ISDN) Asynchronous Transfer mode (ATM) Frame Relay

17 The Internet Explosion Most networks changed to TCP/IP. During the 1990’s most businesses and many homes were connected to the Internet. Some Internet enthusiasts turned their attention to voice.

18 History of Voice Over the Internet Proprietary Schemes – 1980 through 1996 Standards Emerge – 1996 through 1999 Commercial VoIP – 1999 through today.

19 VoIP — 1980 through 1996 Universities and research organizations carried out research and development. Working groups within IETF developed Real- Time Protocol (RTP) and Session Initiations Protocol (SIP). ITU develops what would become the H.323 standard.

20 VoIP — 1996 through – ITU officially released Version 1 of H.323, a standard for real-time video conferencing – IETF officially released Version 1 of Session Initiation Protocol (SIP).

21 H.323 Versus SIP H.323 is more widely deployed, more mature, and more complicated. SIP is growing in popularity, simpler, and more like other, more familiar Internet technologies especially HTTP.

22 Special Concerns of VoIP Reliability Time Sensitivity Voice Quality Security

23 Reliability Our phone system is said to be % reliable; the Internet much less so. The phone system works during most power outages, VoIP requires power backup.

24 Time Sensitivity Real-time, two-way communications are extremely time sensitive. Late and undeliverable packets cause drop- outs and awkward periods of silence. Even differences in the spacing of transmitted and received packets can cause distortion.

25 Voice Quality VoIP is inevitably compared to PSTN. PSTN voice quality is generally better and has become the standard against which VoIP voice is compared. Most customers will tolerate some voice degradation because of the cost savings. VoIP voice quality is improving.

26 Carrier-Grade VoIP The reliability of PSTN. The voice quality of PSTN. The capacity of PSTN – millions of calls simultaneously. The speed of PSTN.

27 “Killer Applications” for the Internet. World Wide Web Instant Messaging Voice over IP

28 VoIP is becoming big business. Microsoft offers Microsoft Messenger and MSN Messenger Google offers Google Talk Yahoo! offers Yahoo! Messenger Ebay buys Skype for $2 Billion.

29 Will VoIP Signal the End of the PSTN?

Voice Over Internet Protocol (VoIP) Copyright © 2006 Heathkit Company, Inc. All Rights Reserved End