Telecommunications and Networks - Principles of Information Systems - page 249

Some cell phones, such as the BlackBerry Curve 8320, can send and receive data and
make VoIP phone calls over wireless Wi-Fi 802.11 b/g networks. When you exit the hot
spot, the phone switches the call seamlessly to the cellular network. Being able to make phone
calls over Wi-Fi is a great option in areas where the cellular service is spotty. 51
Some of the advantages associated with the use of VoIP include:
• For corporate customers, some telecommunications-related cost savings are possible by
using a single data network to carry both voice and data.
• VoIP enables online retailers to provide “click to talk” customer service—online
customers needing additional help can click a hyperlink to create a VoIP phone
connection to a live customer service representative.
• Some VoIP providers permit users to call anywhere in the world at a low cost per minute.
Some of the disadvantages of VoIP include:
• VoIP users may not be able to place calls if power is lost either locally or at the broadband
carrier itself because broadband modems and other VoIP equipment depend on electricity
from the power company. Conventional phones can continue to operate during a local
power failure because they receive their power from the telephone company's local office,
which operates on a separate power supply.
• Some VoIP calls might have lower quality than conventional phone calls if data packets
are lost or delayed at any point in the network between VoIP users.
• Support for the sending of faxes over VoIP is still limited.
• Not all VoIP services connect directly to emergency services through 911.
• Not all VoIP providers offer directory assistance or white page listings.
Merrill Lynch, the global financial management and advisory company, implemented an
advanced VoIP voice trading system. Over 4,000 IQ/MAX next-generation trading desktops
were installed on its two largest trading floors in New York and London plus other trading
floors around the globe. Tony Kerrison, CTO, Global Technology Infrastructure at Merrill
Lynch, said, “… what matters most to our traders is efficiency, dependability, and user
friendliness. The outstanding VoIP technology IQ/MAX delivers will provide our traders
with highly advanced, reliable, and collaborative trading floor communications.” 52

Linking Personal Computers to Mainframes and Networks
One of the most basic ways that telecommunications connect users to information systems
is by connecting personal computers to mainframe computers so that data can be downloaded
or uploaded. For example, a user can download a data file or document file from a database
to a personal computer. Some telecommunications software programs instruct the computer
to connect to another computer on the network, download or send information, and then
disconnect from the telecommunications line. These programs are called unattended sys-
tems because they perform the functions automatically, without user intervention.

Voice Mail
With voice mail , users can send, receive, and store verbal messages for and from other people
around the world. Some voice mail systems assign a code to a group of people. Suppose the
code 100 stands for the 238 sales representatives in a company. If anyone calls the voice mail
system, enters the number 100, and leaves a message, all 238 sales representatives receive the
same message. Call management systems can be linked to corporate e-mail and instant mes-
saging systems. Calls to employees can be generated from instant messages or converted into
e-mail messages to ensure quicker access and response.

voice mail
Technology that enables users to
send, receive, and store verbal mes-
sages for and from other people
around the world.

Reverse 911 Service
Reverse 911 service is a communications solution that delivers emergency notifications to
users in a selected geographical area. The technology employs databases of phone numbers
and contact information to send over 250,000 voice or text messages via phone, pager, cell
phone, or e-mail per hour. A series of messages was sent to some 500,000 residents of San
Diego using reverse 911 services when disastrous wildfires swept the area in October
2007. 53

reverse 911 service
A communications solution that
delivers emergency notifications to
users in a selected geographical
area.