Download Telecommunications

Telecommunications and
Networks
Chapter 6
Chapter 6, Telecommunications and
Networks, describes basic concepts and
components of networks used for data
communications.
After studying chapter 6, you should be
able to address the learning objectives
described in the following 2 slides.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 2
Learning Objectives
Define “communications” and
“telecommunications”.
Describe the components of a
telecommunications system.
Identify & briefly discuss several
telecommunications applications.
Identify the benefits of a network.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 3
Networks have become the connective tissue
of organizations. The effective use of
telecommunications is critical for success in
today’s world. In an environment where
people must take action to seize opportunities
or avert problems before their competitors do,
having the right information at the right time
is critical.
Efficient and effective communication is a
key to successful business.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 4
Learning Objectives
Identify 3 basic types of communications
media and the characteristics of each.
Identify telecommunications hardware and
the role each plays.
Name 3 distributed processing alternatives &
their features.
Define “network topology” & identify five
alternatives.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 5
In telecommunications, the trend is for
greater volumes of more types of
information to be transmitted more
quickly. Understanding the technology
that enables this is important.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 6
Overview of
Telecommunications Systems
Communications is defined as the
transmission of a signal over a
medium from a sender to a receiver.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 8
Fig 6.1
Fig 6.2
In a conversation, a sender transmits a
signal through the medium of the air. In a
two-way conversation, the same person can
be both a sender and a receiver. The signal
is in words. For effective communication to
occur, the sender must encode the signal in a
way the receiver can understand. Therefore,
in a conversation, both sender and receiver
must speak the same language.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 11
Communication Flow
Synchronous communication
Asynchronous communication
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 12
Telephone conversations are examples of
synchronous communication. In synchronous
communication, the receiver gets the message
immediately. With asynchronous
communication, the receiver gets the message at
a late time – possibly even days after the
message is sent. Sending a letter is an example
of asynchronous communication, as is e-mail.
Both synchronous and asynchronous
communication are important in business.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 13
Fig 6.3
Telecommunications is the electronic
communication of signals, such as
telephone, radio and television. Data
communications is a subset of
telecommunications referring to the
electronic collection, processing, &
distribution of data.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 15
Figure 6.3 shows a model of
telecommunications, with a computer as the
sender. The computer sends the signal to a
telecommunications device which facilitates
electronic communication. This device then
transmits the signal across a medium to another
telecommunications device at the receiving end.
This device receives the signal and sends it to
the receiving computer. The process can then be
reversed. This chapter covers the parts of this
telecommunications model in greater detail.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 16
Data Transmission Speeds
Measured in bits per second (bps)
Kilobits per second (kbps)
Megabits per second (Mbps)
Gigabits per second (Gbps)
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 17
Data communications is characterized by
the speed at which the data is sent,
measured in bits per second. The most
common data transmission speeds range
from thousands to millions of bits per
second, or kilobits to megabits per second.
Some networks can support transmission of
billions of bits, or gigabits, per second.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 18
Computer Networks
Telecommunications media
Telecommunications devices
Software
Hardware devices
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 19
A computer network consists of at least two
computers or other devices connected by
media, telecommunications devices and
software that enable users to share data,
information, and resources locally and
worldwide. This chapter covers each of
these components in more detail.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 20
Telecommunications Media
Types of Media
Twisted Pair
Coaxial Cable
Fiber-Optic Cable
Microwave Transmission
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 22
The first 3 types of media – twisted pair, coaxial cable,
and fiber optic cable – are usually referred to as guided
or conducted media. That is, a signal is conducted over a
physical medium. Microwave and other forms of
wireless transmission are called broadcast media.
Generally speaking, there are fewer errors in guided than
in broadcast media.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 23
Different kinds of communications media have different
characteristics, including different speeds and capacities.
As with other components of an information system, the
choice of medium depends on the purpose of the
telecommunications system within the information system.
The media selected should be the most adaptive, cost
effective media that support these objectives. Media is
critical in determining the overall system’s efficiency and
effectiveness.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 24
Twisted Pair
Fig 6.4
Twisted pair cabling is made of pairs of copper wires
twisted together. Twisted pair is used for the phone
connection to your house. In networking it is common to
see cable consisting of 4 pairs of wires. Each pair is
twisted together to reduce electrical interference between
neighboring pairs, or crosstalk. The more twists there are
per foot, the less interference there will be. Twisted pair
is classified by the number of twists per foot. Data grade
cable has more twists per foot than does voice grade
cable.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 26
Shielded twisted pair cabling includes additional
shielding against external electro-magnetic
interference. Unshielded twisted pair, although it
doesn’t have the extra shielding, is used more often
because of its lower costs and greater practicality.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 27
Coaxial Cable
Fig 6.5
Like twisted pair, coaxial cable, or “co-ax”, is also
made from copper. However, because of extra
shielding and insulation, coax has less interference,
and therefore a higher capacity, or bandwidth, than
does twisted pair. Data can be sent over coax at about
500 Mbps, whereas data transmission speeds over
twisted pair for long distances are typically well below
that, although in a local area network fast speeds can
be attained using twisted pair.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 29
A type of coaxial cable is used for cable TV to your
home. Cable modems can be used for Internet access
several hundreds as times as fast as a modem and dialup phone line.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 30
Fiber Optic Cable
Fig 6.6
Unlike twisted pair and coax, fiber optic cable is made of
thin filaments of glass or plastic, not of copper wire.
Whereas a data signal travels over twisted pair or cable
as electricity, signals are transmitted as light pulses over
fiber. Lasers or LCDs produce the light. A thin coating,
called cladding, prevents the light from leaving the
strand. Also unlike copper media, fiber is not vulnerable
to electro-magnetic interference.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 32
Fiber has a much higher bandwidth than does copper
media – that is, it can carry more data faster. Fiber can
have a capacity of billions of bits per second. Fiber is
also the most secure medium around today. The biggest
drawback of fiber is that labor costs to install and repair
fiber are very high.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 33
Microwave Transmission
Fig 6.7
The expense of physical media can be great. Whereas
broadcast media, such as microwave, don’t require the
purchase of physical media, the hardware required is
more expensive. Microwave is a high frequency radio
signal.
In terrestrial microwave, a signal travels directly
between microwave transmission towers. This
requires an unobstructed straight path between towers.
Also, due to the curvature of the earth, towers must be
spaced about 30 miles apart.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 35
Satellite
Fig 6.8
Satellite transmission involves sending a signal from a
microwave tower to the satellite, which is basically a
microwave station, then back to another microwave
tower. Although this eliminates the need for a line-ofsight between towers, the delays to upload and
download the signal often make satellite transmission
impractical for sending signals short distance.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 37
Cellular
Fig 6.9
In cellular transmission, a service area is divided into
cells. Cellular signals are integrated into the regular
telephone network.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 39
Infrared Transmission
Line of sight
Short distances
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 40
Infrared transmission can be used to send data short
distances, for example, from a handheld computer to a
desktop or a printer. Infrared transmission can also be
used to connect peripherals, such as a mouse, to a
computer.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 41
Telecommunications Devices
Telecommunications devices are hardware that make
an electronic transmission occur or make it more
efficient.
Modems, multiplexers, and front-end processors are
examples of telecommunications devices.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 43
Modems
Analog signals: continuous
Digital signals: discrete
Modulation: translating digital data to
analog
Demodulation: translating analog data
to digital
Modems modulate & demodulate data
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 44
Often, data is sent over the regular telephone network,
which transmits analog signals. An analog signal is a
continuous signal; the transmission line varies smoothly
among an infinite number of states. Analog waves can
carry a continuous range of data. On the other hand,
computers produce digital signals. Digital signals send
discrete pulses and represent a limited number of states.
In the case of a computer, two states are represented.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 45
In order to send a digital signal over an analog line, the
signal must first be modulated, or changed to a form
that can be carried over an analog line. When the
signal is received, it must be demodulated so the
computer can understand it. This is what a modem
does.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 46
Fig 6.10
Modems are found between the sending computer and
the phone line and between the receiving computer and
the phone line. Modem transmission speeds are
measured in bits per second. Typical modems today can
download data at 56,600 bits per second. Before a
modem starts to send a message, it determines the
receiving modem’s characteristics and adjusts its own
speed to match. For example, if the other modem can
only receive at 14.4 kilobits per second, a faster modem
will send at the slower speed.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 48
Fig 6.11
Multiplexers are devices that combine
signals from several computers to allow
them to be sent over a single transmission
line.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 50
Fig 6.12
Front end processors are computers that manage
communications to and from a computer system. This
relieves the main computer of work so that it can be free
to process other tasks. Front end processors are usually
mainframes or midrange computers.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 52
Carriers and Services
Telecommunications carriers provide the
technological infrastructure, such as lines
and satellites, that enable data to be sent
from one place to another. Carriers may
also provide services to customers.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 54
Carriers
Common carriers

Long distance carriers
Value-added carriers
Special purpose carriers
 Additional services

Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 55
Common carriers are the long distance telephone
companies. Special purpose carriers offer services
beyond long distance. Typically these are value-added
carriers which are companies that sell services over their
telecommunications systems to subscribers. Many
common carriers are also value added carriers to some
clients. Some value added carriers are third parties.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 56
Services
Line types
Switched
 Dedicated

Private Branch Exchange (PBX)
Wide-area telecommunications service
(WATS)
Phone & dialing services
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 57
Switched lines are available from common carriers.
Switches connect the sender’s and receiver’s phones.
The call is sent along a specific, unchanging path, and
only that call uses that path. When the parties hang up,
all or part of the path is used by other calls.
Dedicated, or leased, lines continuously connect two
devices at fixed points. No dialing is required; the
connection is always there. Although dedicated lines are
expensive, if there is a lot of use, they are cheaper than
dialup lines.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 58
A PBX system can manage voice and data within a
building. Not only does the PBX internally route calls,
but it can be used to connect a few external phone lines
to numerous internal lines.
WATS refers to the use of toll-free numbers. The
company pays a fee to the phone company, depending
on the volume of incoming or outgoing calls. WATS is
very cost-effective for organizations that frequently
make long distance calls.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 59
Common carriers provide increasingly more services
to residential and commercial customers. For example,
automatic number identification, more commonly
called caller ID, can be used to display the caller’s
phone number. In businesses, this can be integrated
with databases to retrieve and display the customer’s
record. Intelligent dialing is a service that will call
back someone when their line is free after you get a
busy signal.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 60
Services
Digital subscriber lines (DSL)
Integrated Services Digital Network
(ISDN)
T1 Carrier
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 61
DSL uses existing phone wires for fast connections for
home and business. This means that users can download
from the Internet at speeds over 500 kbps; upstream
transmission (from the home or business out) may be
slower. DSL is not universally available, although usage
is growing fast.
ISDN also uses existing common carrier lines to digitally
send data, video, image or voice at speeds over 64
kilobits per second.
A T1 line is a digital carrier for data and image. T1 lines
are dedicated and costly.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 62
Table 6.1
When choosing telecommunications services,
individuals and businesses must consider the cost, speed,
reliability and characteristics of each type. Table 6.1
summarizes this information.
T1 lines are expensive dedicated lines, but cost effective
for continual heavy users. They are also very fast, high
capacity lines. DSL is more affordable and it is fairly
fast; however, its availability is limited.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 64
Networks & Distributed
Processing
Telecommunications networks are becoming
increasingly important since they allow work to be done
wherever and whenever it is most advantageous. Data,
software, hardware, and other resources are becoming
ubiquitous – that is, easily accessible by anyone,
anytime, any place.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 66
Basic Processing Strategies
Centralized processing
Decentralized processing
Distributed processing
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 67
There are 3 basic processing strategies when more than
2 computer systems are used. In centralized
processing, all processing is done at one location. This
is the easiest strategy for the IS department to control
and is appropriate when an enterprise needs a high level
of security. In decentralized computing, different
locations have their own processing devices. Devices
at different locations aren’t connected together. This
strategy works well when there are independent
operating units and no data interchange between units.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 68
In distributed processing, computers at different
locations are connected by a communications network.
Data and processing are located where it is most
efficient and effective. For example, data and programs
used most by the Miami office would be located in
Miami, and those used most by the Boston office would
be in Boston. Users at both locations could access data
and programs at the other site when needed.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 69
Network Concepts &
Considerations
Network topology
Network types
Local Area Networks
 Wide Area Networks
 International networks
 Home & small business networks

Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 70
Network topology describes how a network is
logically organized – that is, how the data flows in the
network. Depending on the distance between nodes
and the services provided, networks may be classified
as local area networks or wide area networks.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 71
Fig 6.15
There are 5 main ways to arrange nodes in a network.
In a ring network, devices are connected in a ring and
message are routed around the ring from one device to
the next. A bus network contains devices connected
directly in a straight line. Each device can communicate
directly with every other device one the network. In bus
and ring topologies, there is no central coordinating
computer. A hierarchical network is structured as an
upside down tree like an organizational chart. Messages
are passed to computers along the “branches”.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 73
As in the bus and ring networks, there is no coordinating
computer. A star network has a central, coordinating
device; each computer on the network is directly
attached only to the central device. The central device is
the vulnerability of the network – it can become a
bottleneck under heavy traffic and the whole network
fails if it fails.
Many organizations use a combination of these various
topologies, or a hybrid network.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 74
Network Types
Logical Area Network (LAN)
 Limited geographical area
 Any topology possible
 Network Interface Card (NIC)
 Designs
Peer-to-peer
 Client-server

Wide Area Network (WAN)
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 75
Local Area Networks connect processing devices within
a limited geographic area and do not usually use
common carrier facilities. Devices are attached to the
media using network interface cards, also called network
adapters. LANs can be designed in any of the topologies
previously discussed and communications can be
designed so that the network is peer-to-peer or clientserver. In a peer-to-peer network there are no computers
dedicated as servers. All computers can be both servers
of resources and clients requesting resources.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 76
This design is appropriate for small networks that don’t
change much. In a client-server network, some
computers are dedicated servers and provide
applications, files, databases, telecommunications or
other services to computers requesting those services,
called clients. Client server networks are more
appropriate for large, busy or dynamic networks, but do
require professional network administration.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 77
Wide Area Networks connect devices over large
geographic distances using common carrier facilities.
Companies may use wide area networks provided by
others, such as AT&T long distance service or may
deploy their own WAN using enterprise facilities
along with common carrier facilities.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 78
Network Types
International networks
Global
 Transborder data flows
 Infrastructure differences

Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 79
Some enterprises’ wide area networks are
international networks – that is, they connect
facilities in different countries. Global networks
present some challenges. They must comply with
laws regulating the electronic transmission of data
across borders. Some countries restrict the nature of
information that can be sent electronically. Some
countries have no laws about electronic data
transmission and serve as data havens – that is,
business may perform certain types of processing in
those countries to avoid the laws of the countries in
which they regularly do business.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 80
Another challenge is the inadequate
telecommunications infrastructure in some countries
that can cause problems or limit a network’s
usefulness.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 81
Fig 6.18
More and more individuals are deploying small
networks for small businesses or home use. There are
some products that try to make that easier by allowing a
network to run over existing phone wiring or over
existing electrical wiring. In the near future, we should
see an increase in wireless LANs for home and small
business use.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 83
Connecting Computers in a
Distributed System
Terminal-to-Host
File Server
Client/Server
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 84
Terminal to host, file server, & client server systems are
the most common ways to configure distributed
computing.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 85
Fig 6.19
In a terminal-to-host configuration, users have dumb
terminals connected to a host computer. All file access
and processing is done on the host.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 87
Fig 6.20
In a file server environment, the file or database resides
on a host computer, the file server, and applications,
including the database management system, run on the
user’s computer. All processing is done on the user’s
computer. When an application needs a record, the file
server sends the whole file.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 89
Fig 6.21
In a client/server environment, some computers are
designated as servers for specific tasks, such as
printing, database management, printing, program
execution, or communications. Network computers
request services from the servers. Processing occurs on
both the clients and the servers, so clients receive
exactly the data or services needed. Potentially, a
client/server environment can result in lower costs and
improved performance, although a client/server
environment is complex and costly and hard to manage.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 91
Communications Software
and Protocols
Communications software is necessary for a network to
function. Protocols are the rules and standards that allow
devices to communicate with one another. Examples of a
non-technology protocols are bowing before royalty or
shaking hands when introduced at a business meeting.
Some protocols are implemented in communications
software.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 93
Communications Software
Error checking
Message formatting
Security
Network Operating System (NOS)
Network Management Software
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 94
Communications software, a necessary part of a
network, performs such functions as error checking,
message formatting, and communications log
maintenance. Network Operating Systems performs
the same functions for a network that an operating
system does for a computer. When equipment on the
network, such as databases or printers, is required, the
network operating system intercepts the request and
sends it to the network device. When a message is
received from the network, the network operating
system receives it for the computer.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 95
Network management software includes programs that
allow a network manager to monitor activity and status
of network devices from a single computer. Network
management software can check for viruses, manage
software licenses, or monitor device usage and traffic.
Network management software also allows the manager
to install new software and upgrades remotely over the
network. Network management software improves
efficiency of the network management function.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 96
Communications Protocols
Fig 6.22
Protocols are rules or standards that all devices on a
network must follow in order to communicate
successfully. Protocols are analogous to hardware
standards discussed in Chapter 3: they allow
interoperability of technology from different
manufacturers. There are several different protocol
frameworks or models. The Open Systems
Interconnection (OSI) model is a standard framework
for designing network architectures. The OSI model
divides the data communications process into 7 layers.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 98
Different protocols handle functions at different
layers. Layers allow protocols from different levels to
be mixed and matched. The top layer of the OSI
model, the Application Layer, defines standards for
how the application running on a computer interacts
with other applications on the network. The third OSI
layer, the Network layer, defines how messages are
routed through interconnected networks, such as the
Internet. The bottom layer, the physical layer, defines
electrical and interface standards that transmit bits
over the media. Communicating devices must use the
same standards at corresponding levels.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 99
The Internet protocol stack, also known as TCP/IP, is
another protocol framework. It is commonly used and
often replaces the top 5 layers of the OSI model in
practice. You may be familiar with HTTP, an
application layer protocol belonging to the Internet
protocol stack. HTTP is a standard way for web
browser software to communicate with web server
software.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 100
Network Interconnectivity
Technology
Most networks have interconnectivity devices – that is,
hardware and software that connects them to other
networks that use different standards or protocols.
Bridges, routers, gateways, and switches are examples of
these interconnectivity devices.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 102
Fig 6.23
In its simplest form, a bridge connects two local area
networks that use the same protocol at the second layer
of the OSI model, the Data Link layer. A bridge
forwards all messages that don’t have an address it
recognizes as being from its “own” network, to the
other network it is attached to.
Routers are more complex than bridges, and connect
networks that use different data link layer protocols. A
router looks at the address on the message and
determines which network to send it over. Many
different networks can be connected to a router.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 104
Routers are the main device connecting the many
networks making up the Internet.
Gateways operate at OSI layers above the network
layer and connect networks that are very dissimilar.
Gateways connect networks that use different protocols
in the top layers of the OSI stack. Gateways reformat
messages so that they can be understood by dissimilar
networks.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 105
Switches are now replacing bridges and gateways in
many places. Switches can examine the address of a
message and route it, but are more efficient and
adaptable than older devices.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 106
Telecommunications
Applications
Telecommunications networks are technological
infrastructures that enterprises use to achieve business
goals. Networks allow data to be accessed at remote
locations, employees to communicate electronically with
one another, as well as with clients and suppliers. In
most companies, networks are necessary for doing
business.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 108
Telecommunications
Applications
Voice & electronic mail
Electronic software & document
distribution
Telecommuting
Videoconferencing
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 109
Many of you use voice and electronic mail daily –
sometimes it hard to imagine life before e-mail.
In electronic software distribution, software is
installed on a file server for users to download to their
desktop machines. This is much more efficient than
having someone go to each computer to load the
software. Some companies allow you to download
software over the Internet.
Telecommuting allows employees to work away from
the office using personal computers and networks to
stay in contact.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 110
Videoconferencing allows individuals to communicate
verbally, as well as see one another and view the same
documents.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 111
Fig 6.24
Videoconferencing allows face to face meetings to be
conducted among individuals in different locations
without the time and expense of travel. Although much
corporate videoconferencing involves large, specialized
rooms and facilities, the technology exists to
videoconference from desktop PCs. There are also some
trials today using videoconferencing between a patient at
home and physician or nurse.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 113
Fig 6.25
Electronic Data Interchange, EDI, is the computer-tocomputer exchange of data between companies or
trading partners. Consider for example, part of the
lifecycle of a purchase order for paint used in the
manufacture of widgets at the ABC company. In a
manual system, a buyer must create a purchase order
(PO) and have it approved by a superior. If the PO
wasn’t entered in on the computer, someone must enter
it. When the PO arrives at the paint supplier, the order
must be entered into the supplier’s computer system.
When the order is shipped, an invoice is created, often
with additional data entry.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 115
When ABC’s accounts payable clerk gets the invoice, he
enters the information into the computer system, etc.
Using EDI, the PO would be created on the computer
and sent directly to the supplier’s computer, which
would receive it and initiate the processing. All of the
supplier’s computer systems would use the same
database of information. The invoicing system, for
example, would be notified (by the computer
application) when the paint is shipped, and an invoice
would automatically be electronically transmitted to
ABC’s computer.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 116
ABC’s computer would schedule the invoice for
payment (which would also be done electronically
using electronic funds transfer between banks). The
bottom line is that EDI reduces error and time involved
in transactions by reducing, if not eliminating, human
intervention.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 117
The ABC widget example used a direct EDI
connection between the supplier and ABC. However,
a third-party clearinghouse is sometimes used. In a
direct connection, the supplier and customer must
have compatible information systems and formatting.
This can be costly or inconvenient. By using a thirdparty clearinghouse, data conversion and related
services are done by the clearinghouse.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 118
Telecommunications
Applications
Distance learning
Public Network Services
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 119
You are familiar with distance learning as a
telecommunications application. Distance learning is
now being used for corporate training, as well as by
traditional colleges & universities & commercial
educational enterprises. It is expected that the use of
distance learning will increase.
Many of you might also be familiar with public
network services. These are online content providers,
such as AOL, and offer news, investment information,
e-mail, virtual shopping malls, and many other
services.
Chapter 6
Principles of Information Systems,
Fifth Edition
Slide 120