Chapter 1

1. Chapter 1 Introduction to Telecommunications

2. Objectives • Be able to explain what telecommunications is. • Have a basic understanding of the various networks used to transmit voice, video, and data signals from one location to another. • Know the types of media used to convey telecommunications signals between a sender and a receiver.

3. Objectives (continued) • 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. • Have a basic understanding of personal computer-based voice communication systems, referred to as computer telephony integrated (CTI) systems.

4. Objectives (continued) • 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. • Have a basic understanding of Hypertext Markup Language (HTML) and web browsers.

5. Telecommunications • Communication over a distance • Voice • Video • Data • Telecommunications – voice communications • Data Communication – data signals

6. Telephone Connected to Central Office

7. Public Switched Telephone Network (PSTN) • Voice signals emerge from telephone as analog (analogous) signals • All telephones connected to a local central office • Automated switching system connects callers to desired location • Contains a line circuit for each telephone connected to it • Codec (coder/decoder) converts analog signals into digital signals

8. Packet (or Public) Data Network

9. Packet Data Network (PDN) • Digital data can be transmitted over the PSTN • Modems • Packet Data Network • Wide area network • Uses PSTN facilities reserved for data transmission

10. Beginning of Telecommunications • Samuel F.B. Morse (1791-1872) • Guglielmo Marconi (1874-1937)

11. Telegraph (Morse) • Morse formed a telegraph company based on his invention in 1845. • Western Union Telegraph Company was established in 1856. • Morse developed • The repeater, that could regenerate electrical signals. • Morse code, to transmit letters of the alphabet.

12. Radio (Marconi) • Marconi discovered how to make electric energy radiate from wire into air (electromagnetic radiation). • Radio waves first used for wireless telegraph. • Not long before voice signals were being carried. • In the 1940s radio signals were used to transmit video and television was born.

13. Fiber Optic Technology • Two scientific developments in the 1980s • A way transmit voice, data, and video using light. • A way to transmit light signals over narrow ribbons of glass (glass fiber). • Sprint built an entire network using fiber • Completely new network (not stuck with old technology). • First Interexchange Carrier (IEX) with an all-digital network for long distance calls.

14. Invention of the Telephone • In 1876, Elisha Gray and Alexander Graham Bell filed papers with the patent office for an invention called the telephone. • Gray filed a disclosure notification. • Bell’s father-in-law filed a patent for Bell. • The Supreme Court ruled in a split decision that Bell is to be recognized as the inventor of the telephone.

15. The telegraph system The telephone system Local Exchange Carriers (LECs) Interactive-Voice-Response (IVR) systems Relay Centers and Speed of Delivery

16. Connection of Telephone Offices

17. Connection of Telephone Offices • Telegraph system • Far superior to U.S. mail system • Sender still had to wait hours for response due to delay involved in messenger locating recipient • Telephone company in 1870s originally used same approach • Customer would give operator a message along with recipient • Message would be relayed to telephone center in next town

18. Long Distance Network

19. Long Distance Network • Toll network • Established by Bell Company • Reduced number of relays made to complete long distance calls • Managed by AT&T Long Lines department • Local Exchange Carrier (LEC) • Bell and non-Bell • Connected to an AT&T toll center • Could take up to an hour to get call through

20. Function Automation • First functions to be automated were local operator functions • Next were long distance operator functions • Interactive-Voice-Response (IVR) systems • Collect calls • Person-to-person • Allow caller to provide information via scripted questions • Operators used to handle calls rejected by automated system

21. Hearing impaired Operators at relay centers are called agents Operator talks to hearing party Operator uses teletype to communicate with hearing impaired party Another Type of Relay Center

22. Relay Center

23. Telecommunications for the Hearing Impaired • Major telecommunications service • Each state government contracts to provide service via relay centers • Relay agent communicates with hearing party • Hearing impaired party uses a teletype • Uses a special purpose modem • Different code than a PC for transmission

24. Increasing Speed of Telecommunications • Significant increases in speed in which telephone call can be made • Automating the switching systems • Eliminating the need for operators to make connections • Development of computer-controlled switching systems • Development of signaling systems to connect computer-controlled switching systems

25. SS7 Network

26. Signaling System 7 (SS7) • Contains special purpose computers and databases connected in a data network • Connects all computer-controlled switching systems • Provides a path that allows information from one computer-controlled switching system to reach another • Caller ID • Call forwarding • Conference calling • Establishes calls in a few milliseconds

27. Increasing Ability to Handle Data • PSTN has evolved into an all-digital network • Very Large Scale Integrated Circuit (VLSI) chips • Large number of components • Small in size and cost • Fiber optic cables for transmission media • Multiplexing – placing many signals over one transmission medium

28. Multiplexer

29. Multiplexer • Very Large-Scale Integrated Circuit (VLSI) chips • Hardware devices that handle digital signals • Small (in size and cost), special purpose integrated circuit chips • Use of fiber optic cables for transmission media has helped make enormously fast signal changes possible • Multiplexing is a technique used to place many signals over one transmission medium

30. Multiplexing Using DWDM and OC-48

31. Dense Wave Division Multiplexer (DWDM) • Uses 32 different light waves to carry signals over one fiber • Each multiplexer sends signals at 10 billion signal changes per second • One fiber can carry 320 billion signal changes per second • One fiber cable can contain 140 fibers for 22 trillion signal changes per second

32. Fiber Cable Networks • Handle all types of telecommunications services • Telephone calls • Data and video • Internet • Business users • Link personal computers, file servers, and mainframes • Cellular technology • Connnect to switching centers

33. Fiber Carrying All Types of Circuits

34. Telecommunications for Voice Applications in Business • Large businesses have a telecommunications department to handle use of technology • Voice and data services have merged – Voice-Over Internet Protocol (VoIP) • Private switching systems • Private Branch Exchange (PBX) • Keysystem • Automatic Call Distributor (ACD)

35. Voice-Over Internet Protocol (VoIP)

36. Voice-Over Internet Protocol • Delivers voice and data over the data network • Standards developed • Quality improved • Can replace analog telephones

37. PBX Switching System

38. PBX Switching System • Has all telephones of the business connected to it • Also connected to the local exchange carrier (Central Office, CO lines) • Employees can dial each other directly or dial 9 for a CO (outside) line

39. PC-Based PBX or UnPBX

40. UnPBX • Furnished via personal computers • Special cards containing RJ-11 jacks • Jacks allow for connecting to telephones or C.O. lines • Can also provide information about the call on its screen • Computer Telephony Integrated (CTI) systems do this automatically using caller ID

41. Keysystems

42. Keysystems • Many small businesses do not need a PBX • Used when business has • Less than 24 telephones • Less than12 connections to the LEC • Hybrid systems • Combines some features and functions of a PBX with a keysystem • Used to handle requirements between those of a PBX and keysystem

43. Automatic Call Distributor

44. Automatic Call Distributor • Used by large call centers to distribute incoming calls to their operators • Used by telemarketing companies to place outbound calls automatically • Predictive dialing software • System connects the next call with the next available agent

45. ACD and LAN

46. ACD and LAN • Many inbound ACD installations also include the installation of a local area network (LAN) for data • Calls received by the ACD can also include information for the call center from the PSTN via SS7 • This information is used to provide the operator or agent with information about the caller • Computer Telephony Integration (CTI) combine these functions with the ACD in PC-based systems

47. Telecommunications for Data Applications in Business • Need for special data communication networks that tie all computers together • Local Area Networks (LANs) • Metropolitan Area Networks (MANs) • Wide Area Networks (WANs)

48. LAN to WAN

49. Local Area Networks (LANs) • 80% of LANs use Ethernet to allow PCs to access the network • PCs connected to Ethernet via two twisted-pair copper wires • RJ-45 connectors terminate the four wires • Network Interface Card (NIC) in PC • Wiring hub serves as the Ethernet

50. The Internet • Grown tremendously over the last two decades • As much impact on society as telephone, television, and PC • National Information Infrastructure (NII) – U.S. Government program to establish an information super highway