Chapter 1

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Chapter 1

  1. 1. Chapter 1 Introduction to Telecommunications
  2. 2. Objectives <ul><li>Be able to explain what telecommunications is. </li></ul><ul><li>Have a basic understanding of the various networks used to transmit voice, video, and data signals from one location to another. </li></ul><ul><li>Know the types of media used to convey telecommunications signals between a sender and a receiver. </li></ul>
  3. 3. Objectives (continued) <ul><li>Understand the basics of the three major voice communication technologies (keysystem, private branch exchange, and automatic call distributor) available to a business enterprise and the type of business best served by each of these technologies. </li></ul><ul><li>Have a basic understanding of personal computer-based voice communication systems, referred to as computer telephony integrated (CTI) systems. </li></ul>
  4. 4. Objectives (continued) <ul><li>Have a basic understanding of what a local area network and a wide area network are and how a business uses them to meet data communication needs. </li></ul><ul><li>Have a basic understanding of Hypertext Markup Language (HTML) and web browsers. </li></ul>
  5. 5. Telecommunications <ul><li>Communication over a distance </li></ul><ul><ul><li>Voice </li></ul></ul><ul><ul><li>Video </li></ul></ul><ul><ul><li>Data </li></ul></ul><ul><li>Telecommunications – voice communications </li></ul><ul><li>Data Communication – data signals </li></ul>
  6. 6. Telephone Connected to Central Office
  7. 7. Public Switched Telephone Network (PSTN) <ul><li>Voice signals emerge from telephone as analog ( analogous ) signals </li></ul><ul><li>All telephones connected to a local central office </li></ul><ul><ul><li>Automated switching system connects callers to desired location </li></ul></ul><ul><ul><li>Contains a line circuit for each telephone connected to it </li></ul></ul><ul><ul><li>Codec (coder/decoder) converts analog signals into digital signals </li></ul></ul>
  8. 8. Packet (or Public) Data Network
  9. 9. Packet Data Network (PDN) <ul><li>Digital data can be transmitted over the PSTN </li></ul><ul><ul><li>Modems </li></ul></ul><ul><ul><li>Packet Data Network </li></ul></ul><ul><li>Wide area network </li></ul><ul><li>Uses PSTN facilities reserved for data transmission </li></ul>
  10. 10. Beginning of Telecommunications <ul><li>Samuel F.B. Morse (1791-1872) </li></ul><ul><li>Guglielmo Marconi (1874-1937) </li></ul>
  11. 11. Telegraph (Morse) <ul><li>Morse formed a telegraph company based on his invention in 1845. </li></ul><ul><li>Western Union Telegraph Company was established in 1856. </li></ul><ul><li>Morse developed </li></ul><ul><ul><li>The repeater, that could regenerate electrical signals. </li></ul></ul><ul><ul><li>Morse code, to transmit letters of the alphabet. </li></ul></ul>
  12. 12. Radio (Marconi) <ul><li>Marconi discovered how to make electric energy radiate from wire into air (electromagnetic radiation). </li></ul><ul><li>Radio waves first used for wireless telegraph. </li></ul><ul><li>Not long before voice signals were being carried. </li></ul><ul><li>In the 1940s radio signals were used to transmit video and television was born. </li></ul>
  13. 13. Fiber Optic Technology <ul><li>Two scientific developments in the 1980s </li></ul><ul><ul><li>A way transmit voice, data, and video using light. </li></ul></ul><ul><ul><li>A way to transmit light signals over narrow ribbons of glass (glass fiber). </li></ul></ul><ul><li>Sprint built an entire network using fiber </li></ul><ul><ul><li>Completely new network (not stuck with old technology). </li></ul></ul><ul><ul><li>First Interexchange Carrier (IEX) with an all-digital network for long distance calls. </li></ul></ul>
  14. 14. Invention of the Telephone <ul><li>In 1876, Elisha Gray and Alexander Graham Bell filed papers with the patent office for an invention called the telephone. </li></ul><ul><ul><li>Gray filed a disclosure notification. </li></ul></ul><ul><ul><li>Bell’s father-in-law filed a patent for Bell. </li></ul></ul><ul><li>The Supreme Court ruled in a split decision that Bell is to be recognized as the inventor of the telephone. </li></ul>
  15. 15. Relay Centers and Speed of Delivery <ul><li>The telegraph system </li></ul><ul><li>The telephone system </li></ul><ul><li>Local Exchange Carriers (LECs) </li></ul><ul><li>Interactive-Voice-Response (IVR) systems </li></ul>
  16. 16. Connection of Telephone Offices
  17. 17. Connection of Telephone Offices <ul><li>Telegraph system </li></ul><ul><ul><li>Far superior to U.S. mail system </li></ul></ul><ul><ul><li>Sender still had to wait hours for response due to delay involved in messenger locating recipient </li></ul></ul><ul><li>Telephone company in 1870s originally used same approach </li></ul><ul><ul><li>Customer would give operator a message along with recipient </li></ul></ul><ul><ul><li>Message would be relayed to telephone center in next town </li></ul></ul>
  18. 18. Long Distance Network
  19. 19. Long Distance Network <ul><li>Toll network </li></ul><ul><ul><li>Established by Bell Company </li></ul></ul><ul><ul><li>Reduced number of relays made to complete long distance calls </li></ul></ul><ul><ul><li>Managed by AT&T Long Lines department </li></ul></ul><ul><li>Local Exchange Carrier (LEC) </li></ul><ul><ul><li>Bell and non-Bell </li></ul></ul><ul><ul><li>Connected to an AT&T toll center </li></ul></ul><ul><li>Could take up to an hour to get call through </li></ul>
  20. 20. Function Automation <ul><li>First functions to be automated were local operator functions </li></ul><ul><li>Next were long distance operator functions </li></ul><ul><li>Interactive-Voice-Response (IVR) systems </li></ul><ul><ul><li>Collect calls </li></ul></ul><ul><ul><li>Person-to-person </li></ul></ul><ul><ul><li>Allow caller to provide information via scripted questions </li></ul></ul><ul><ul><li>Operators used to handle calls rejected by automated system </li></ul></ul>
  21. 21. Another Type of Relay Center <ul><li>Hearing impaired </li></ul><ul><li>Operators at relay centers are called agents </li></ul><ul><ul><li>Operator talks to hearing party </li></ul></ul><ul><ul><li>Operator uses teletype to communicate with hearing impaired party </li></ul></ul>
  22. 22. Relay Center
  23. 23. Telecommunications for the Hearing Impaired <ul><li>Major telecommunications service </li></ul><ul><li>Each state government contracts to provide service via relay centers </li></ul><ul><li>Relay agent communicates with hearing party </li></ul><ul><li>Hearing impaired party uses a teletype </li></ul><ul><ul><li>Uses a special purpose modem </li></ul></ul><ul><ul><li>Different code than a PC for transmission </li></ul></ul>
  24. 24. Increasing Speed of Telecommunications <ul><li>Significant increases in speed in which telephone call can be made </li></ul><ul><ul><li>Automating the switching systems </li></ul></ul><ul><ul><li>Eliminating the need for operators to make connections </li></ul></ul><ul><li>Development of computer-controlled switching systems </li></ul><ul><li>Development of signaling systems to connect computer-controlled switching systems </li></ul>
  25. 25. SS7 Network
  26. 26. Signaling System 7 (SS7) <ul><li>Contains special purpose computers and databases connected in a data network </li></ul><ul><li>Connects all computer-controlled switching systems </li></ul><ul><li>Provides a path that allows information from one computer-controlled switching system to reach another </li></ul><ul><ul><li>Caller ID </li></ul></ul><ul><ul><li>Call forwarding </li></ul></ul><ul><ul><li>Conference calling </li></ul></ul><ul><li>Establishes calls in a few milliseconds </li></ul>
  27. 27. Increasing Ability to Handle Data <ul><li>PSTN has evolved into an all-digital network </li></ul><ul><li>Very Large Scale Integrated Circuit (VLSI) chips </li></ul><ul><ul><li>Large number of components </li></ul></ul><ul><ul><li>Small in size and cost </li></ul></ul><ul><li>Fiber optic cables for transmission media </li></ul><ul><li>Multiplexing – placing many signals over one transmission medium </li></ul>
  28. 28. Multiplexer
  29. 29. Multiplexer <ul><li>Very Large-Scale Integrated Circuit (VLSI) chips </li></ul><ul><ul><li>Hardware devices that handle digital signals </li></ul></ul><ul><ul><li>Small (in size and cost), special purpose integrated circuit chips </li></ul></ul><ul><li>Use of fiber optic cables for transmission media has helped make enormously fast signal changes possible </li></ul><ul><li>Multiplexing is a technique used to place many signals over one transmission medium </li></ul>
  30. 30. Multiplexing Using DWDM and OC-48
  31. 31. Dense Wave Division Multiplexer (DWDM) <ul><li>Uses 32 different light waves to carry signals over one fiber </li></ul><ul><li>Each multiplexer sends signals at 10 billion signal changes per second </li></ul><ul><li>One fiber can carry 320 billion signal changes per second </li></ul><ul><li>One fiber cable can contain 140 fibers for 22 trillion signal changes per second </li></ul>
  32. 32. Fiber Cable Networks <ul><li>Handle all types of telecommunications services </li></ul><ul><ul><li>Telephone calls </li></ul></ul><ul><ul><li>Data and video </li></ul></ul><ul><ul><li>Internet </li></ul></ul><ul><li>Business users </li></ul><ul><ul><li>Link personal computers, file servers, and mainframes </li></ul></ul><ul><li>Cellular technology </li></ul><ul><ul><li>Connnect to switching centers </li></ul></ul>
  33. 33. Fiber Carrying All Types of Circuits
  34. 34. Telecommunications for Voice Applications in Business <ul><li>Large businesses have a telecommunications department to handle use of technology </li></ul><ul><li>Voice and data services have merged – Voice-Over Internet Protocol (VoIP) </li></ul><ul><li>Private switching systems </li></ul><ul><ul><li>Private Branch Exchange (PBX) </li></ul></ul><ul><ul><li>Keysystem </li></ul></ul><ul><li>Automatic Call Distributor (ACD) </li></ul>
  35. 35. Voice-Over Internet Protocol (VoIP)
  36. 36. Voice-Over Internet Protocol <ul><li>Delivers voice and data over the data network </li></ul><ul><li>Standards developed </li></ul><ul><li>Quality improved </li></ul><ul><li>Can replace analog telephones </li></ul>
  37. 37. PBX Switching System
  38. 38. PBX Switching System <ul><li>Has all telephones of the business connected to it </li></ul><ul><li>Also connected to the local exchange carrier (Central Office, CO lines) </li></ul><ul><li>Employees can dial each other directly or dial 9 for a CO (outside) line </li></ul>
  39. 39. PC-Based PBX or UnPBX
  40. 40. UnPBX <ul><li>Furnished via personal computers </li></ul><ul><ul><li>Special cards containing RJ-11 jacks </li></ul></ul><ul><ul><li>Jacks allow for connecting to telephones or C.O. lines </li></ul></ul><ul><li>Can also provide information about the call on its screen </li></ul><ul><li>Computer Telephony Integrated (CTI) systems do this automatically using caller ID </li></ul>
  41. 41. Keysystems
  42. 42. Keysystems <ul><li>Many small businesses do not need a PBX </li></ul><ul><li>Used when business has </li></ul><ul><ul><li>Less than 24 telephones </li></ul></ul><ul><ul><li>Less than12 connections to the LEC </li></ul></ul><ul><li>Hybrid systems </li></ul><ul><ul><li>Combines some features and functions of a PBX with a keysystem </li></ul></ul><ul><ul><li>Used to handle requirements between those of a PBX and keysystem </li></ul></ul>
  43. 43. Automatic Call Distributor
  44. 44. Automatic Call Distributor <ul><li>Used by large call centers to distribute incoming calls to their operators </li></ul><ul><li>Used by telemarketing companies to place outbound calls automatically </li></ul><ul><ul><li>Predictive dialing software </li></ul></ul><ul><li>System connects the next call with the next available agent </li></ul>
  45. 45. ACD and LAN
  46. 46. ACD and LAN <ul><li>Many inbound ACD installations also include the installation of a local area network (LAN) for data </li></ul><ul><li>Calls received by the ACD can also include information for the call center from the PSTN via SS7 </li></ul><ul><li>This information is used to provide the operator or agent with information about the caller </li></ul><ul><li>Computer Telephony Integration (CTI) combine these functions with the ACD in PC-based systems </li></ul>
  47. 47. Telecommunications for Data Applications in Business <ul><li>Need for special data communication networks that tie all computers together </li></ul><ul><ul><li>Local Area Networks (LANs) </li></ul></ul><ul><ul><li>Metropolitan Area Networks (MANs) </li></ul></ul><ul><ul><li>Wide Area Networks (WANs) </li></ul></ul>
  48. 48. LAN to WAN
  49. 49. Local Area Networks (LANs) <ul><li>80% of LANs use Ethernet to allow PCs to access the network </li></ul><ul><li>PCs connected to Ethernet via two twisted-pair copper wires </li></ul><ul><ul><li>RJ-45 connectors terminate the four wires </li></ul></ul><ul><ul><li>Network Interface Card (NIC) in PC </li></ul></ul><ul><ul><li>Wiring hub serves as the Ethernet </li></ul></ul>
  50. 50. The Internet <ul><li>Grown tremendously over the last two decades </li></ul><ul><li>As much impact on society as telephone, television, and PC </li></ul><ul><li>National Information Infrastructure (NII) – U.S. Government program to establish an information super highway </li></ul>
  51. 51. Internet Timeline
  52. 52. Key Internet Events <ul><li>1961 - Leonard Kleinrock publishes paper on packet switching </li></ul><ul><li>1969 - ARPANET test </li></ul><ul><li>1970 - Network Control Protocol (NCP) implemented on ARPANET </li></ul><ul><li>1971 - E-mail </li></ul><ul><li>1974 - Kahn and Cerf publish paper on TCP/IP </li></ul><ul><li>1974 - 62 hosts on ARPANET </li></ul><ul><li>1979 - USENET newsgroup network </li></ul>
  53. 53. Key Internet Events <ul><li>1983 - Internet Activity Board (IAB) created to oversee protocol development </li></ul><ul><li>1983 - TCP/IP version 4 adopted for ARPANET </li></ul><ul><li>1983 - 500 hosts </li></ul><ul><li>1984 - Domain Name System (DNS) </li></ul><ul><li>1986 - National Science Foundation Network (NSFNET) </li></ul><ul><li>1988 - Worm virus </li></ul><ul><li>1988 - Computer Emergency Response Team (CERT) </li></ul><ul><li>1990 - ARPANET retired </li></ul>
  54. 54. Key Internet Events <ul><li>1991 - Gopher menu-driven Intenet interface </li></ul><ul><li>1991 - Tim Berners-Lee develops World Wide Web </li></ul><ul><li>1992 - 1,000,000 hosts </li></ul><ul><li>1993 - Mosaic graphical WWW interface </li></ul><ul><li>1993 - Internet Network Information Center (InterNIC) </li></ul><ul><li>1993 - 2,000,000 hosts </li></ul><ul><li>1995 - NSF stops supporting NSFNET </li></ul><ul><ul><li>Internet goes commercial </li></ul></ul><ul><ul><li>Internet Service Providers (ISPs) </li></ul></ul>
  55. 55. Key Internet Events <ul><li>1995 - NSF starts supporting Very-High-Speed Backbone Network Service (vBNS) </li></ul><ul><li>1996 - Telecommunications Act of 1996 </li></ul><ul><li>1996 - 10,000,000 hosts </li></ul><ul><li>1997 to present - E-commerce, distance learning, Voice-Over IP, Virtual Private Networks, Television-Over IP, etc. </li></ul>
  56. 56. The World Wide Web (WWW) <ul><li>Organizes the resources of the Internet </li></ul><ul><li>Tim Berners-Lee </li></ul><ul><ul><li>Hypertext Markup Language (HTML) </li></ul></ul><ul><ul><li>Hypertext Transport Protocol (HTTP) </li></ul></ul><ul><li>Internet Engineering Task Force (IETF) established standards for HTML and HTTP </li></ul><ul><li>Browsers based on HTML </li></ul><ul><ul><li>Mosaic </li></ul></ul><ul><ul><li>Netscape </li></ul></ul>
  57. 57. Summary <ul><li>Telecommunications means to communicate over a distance using electrical signals, radio waves, or light waves </li></ul><ul><li>Advances in technology have enabled the PSTN to serve as a medium for the transfer of voice, data, and video </li></ul>
  58. 58. Telecommunications Jobs <ul><li>Enormous growth in the job market for telecommunications technicians, engineers, and managers </li></ul><ul><ul><li>Continual evolution of telecommunications technology </li></ul></ul><ul><ul><li>Deregulation of the telecommunications industry </li></ul></ul><ul><ul><li>Explosive growth of personal computing </li></ul></ul><ul><ul><li>Need for LANs and WANs to connect PCs together </li></ul></ul><ul><ul><li>Increasing needs of information technology </li></ul></ul><ul><ul><li>Growth of the Internet </li></ul></ul>

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