Fiber Optics Illustrated Dictionary - Part 93 ppsx

Fiber
Optics
Illustrated
Dictionary
and
suppliers ofcommunications products
for
mat-
ters
of
public
policy
and
international
commerce.
TIA
is
accredited
by
the
American National Standards In-
stitute
(ANSI)
to
develop standards
for
a variety
of
communication products.
See
TIAFiber Optic

Com-
munication
Standards
chart.
/>Telecommunications Information NetworkArchi-
tecture
TINA.
A common architecture
for
building
and
managing communications services developed
by
the
Telecommunications Information Network
Ar-
chitecture Consortium
in
the
early
1990s.
This
archi-
tecture logically separates
the
physical infrastructure
and
the
applications
from

the
need
to
communicate
directly with each
another.
Control and management
functions
are
integrated
and
can
be
placed
on
the
net-
work independent ofgeography
through
asingle Dis-
tributed Processing Environment (DPE).
See
Tele-
communications Information Network Architecture
Consortium.
Telecommunications Information Network Ar-
chitecture Consortium
TINA-C.
An
international

association ofover
40
telecommunications operators
and
manufacturers
who
first
came
together
at
a
TINA
Workshop
in
1990
and
formed the consortium
to
cooperatively define a
common
architecture
(TINA)
to
be
promoted
as
a global standard
for
building
and

managing telecommunications services.
This
work
draws
heavily
on
the
work
of
other organizations
and
standards bodies
in
order
to
take advantage
of
ongo-
ing studies and developments, to expedite the
progress of
the
TINA
project,
and
to
promote
the
har-
monious cooperation
of

various groups with similar
goals. .
telecommunications lines Physical lines, usually
metal wire
or
fiber optic cable, over which commu-
nications are transmitted, usually
by
electrical
im-
pulses
or
light. Contrast
to
wireless communications.
telecommunications main grounding
bus
bar
TMGB.
An important component
of
a telecommuni-
cations electronic grounding system that extends the
building grounding electrode system
for
a telecom-
munications network infrastructure.
Typically
one
per

building
is
housed
in
an
accessible communications
closet
as
a central attachment point
for
atelecommu-
nications bonding backbone (TBB) with
one
or
more
telecommunications grounding busbars (TGBs).
A
TMGB
is
designed
to
facilitate low-resistance
con-
tact between
lugs
and busbars.
It
should
be
directly

bonded
to
the
electrical service ground
and
to
a
TGB
which,
in
tum, connects
to
a permanent metallic
TIA
Fiber
Optic Communication Standards
Document
Designation Description
TWEIA-455-164A FOTP-I64
TIAlEIA-455-171A
FOTP-171A
TWEIA-455-191A
FOTP-191
TIA-526-2
OFSTP-2
FOTP-5
FOTP-78
100
Mbps
FOTP-87

FOTP-98
FOTP-157
Humidity
Test
Procedure
for
Fiber
Optic
Components
Spectral
Attenuation
Cutback
Measurement
for
Single-Mode
Optical
Fibers
Fiber
Optic
Cable
Knot
Test
Fiber
Optic
Cable
External
Freezing
Test
Measurement
of

Polarization
Dependent
Loss
(PDL)
of
Single-Mode
Fiber
Optic
Components
Single-Mode
Fiber,
Measurment
of
Mode
Field Diameter
by
Far-Field
Scanning
Attenuation
by
Substitution
Measurement
for
Short-Length
Multimode
Graded-Index
and
Single-Mode
Optical
Fiber

Cable
Assemblies
Measurement
of
Mode
Field
Diameter
of
Single-Mode
Optical
Fiber
Effective
Transmitter
Output
Power
Coupled
into
Single-Mode
Fiber
Optic
Cable
Single-Mode
Fiber
Optic
System
Transmission
Design
Fiber
Optic
Connector

Intermateability
Standards
Blank
Detail
Specification
for
Single-Mode
Fiber
Optic
Branching
Devices
for
Outside
Plant
Applications
Physical
Layer
Medium-Dependent
Sub
layer
and
10
Mbps
Auto-
Negotiation
on
850
om
Fiber
Optics

Relevant Technical Committees
TIAlEIA-455-87B
TWEIA-455-98A
TIAlEIA-455-157
TIAlEIA-455-5B
TIAlEIA-455-78A
TIA-559
TWEIA-604
TWEIA-620AAOO
TIAlEIA-785
FO-2.l
Single
Mode
Optical
Communication
Systems
FO-2.2
Digital
Multimode
Systems
FO-2.3
Optoelectronic
Sources,
Detectors,
and
Devices
FO-2.6
Reliability
ofFiber
Optic

Systems
&
Active
Optical
Components
FO-6.1
Fiber
Optic
Field
Tooling
&
Instrumentation
FO-6.2
FO-6.3
FO-6.6
FO-6.7
FO-6.9
Terminology,
Defmitions,
&
Symbology
Interconnecting
Devices
and
Passive
Products
Fibers
and
Materials
Optical

Cables
Polarization-Maintaining
Fibers,
Connectors,
and
Components
912
© 2003 by CRC Press LLC
structural
element
of
the
building.
The
TMGB
should
never
be
bonded
to
a
secondary
electrical
conduit
or
pipe,
as
this
may
result

in
different
ground
potentials
between
the
TMGB
and
the
communications
equip-
ment
grounding.
If
multiple
closets
exist
in
the
same
building;
the
TGBs
should
be
bonded
to
one
another
and

to
the
TMGB
through
approved
insulated
wires
to
form
a
TBB.
The
TMGB
resembles
a
metal
cribbage
board
in
that
it
has
pairs
of
holes
punched
(all
the
way)
through

a
thin
rectangular
board
and
is
supported
by
brackets
and
insulators
with
noncorrosive
fasteners.
The
holes
are
drilled
according
to
recognized
size
and
spacing
standards
(e.g.,
NEMA).
It
is
made

ofa
conductive
material
such
as
copper,
and
may
be
plated
with
an-
other
metal
such
as
nickel.
TMGBs
are
generally
designed
to
conform
to
ANSI!
TIA/EIA-607
specifications
and
BICSI
recommen-

dations
and
come
in
avariety of
widths
and
lengths.
Once
installed,
TMGBs
should
be
labeled
with
warn-
ings
not
to
remove
the
structure
or
disconnect
any
of
its
components.
Telecommunications
Management Network

TMN.
A
global
network
management
model
for
Network
Elements
(NE)
and
Operation
System
(OS)
and
the
interconnections
between
them.
Global
standardiza-
tion
provides
greater
incentives
for
common
interface
development.
Discussions

of
O&M
aspects
of
intel-
ligent
transmission
terminals
began,
and
TMN
was
first
formally
defined
in
1988,
with
the
recommen-
dation
for
M.30
10 (Principles
for
TMN)
published
in
1989,
in

addition
to
others
over
the
next
three
years.
OSI
Management,
originating
in
ISO,
was
adopted
as
a
framework
for
TMN
to
provide
transaction-ori-
ented capabilities
for
operations, administration,
maintenance,
and
provisioning
(OAM&P).

Elements
of a
TMN
interface
consist of
various
definitions,
models,
and
profiles,
including
architectural
defini-
tion
of
TMN
entities,
OAM&P
functionality,
man-
agement
application
and
information models,
re-
source
information
models,
communication
proto-

cols,
conformance
requirements,
and
profiles.
Telecommunications
Policy,
Office
of
OTP
A
gov-
ernment
agency,
established
in
1970
as
an
Executive
Office
of
the
President
during
Richard
M.
Nixon's
administration.
The

OTP
evolved
from
the
1968
President's
Task
Force
on
Telecommunications
Policy.
Clay
T.
(Tom)
Whitehead
was
the
first
OTP
Director.
Some
of
the
staff
were
taken
from
the
ear-
lier Office of Telecommunications Management

(OTM).
The
OTP
was
rolled
into
the
U.S.
National
Telecommunications
and
Information
Administration
in
1978
resulting
from
reorganization.
Telecommunications Policy, President's Task
Force
on
A
significant
milestone
in
telecommunica-
tions
policy
development
which

came
about
partly
because
of
controversies
regarding
cable
and
long
distance
services.
The
Task
Force
was
established
in
1968
during
the
term
of
President
Lyndon
B.
Johnson.
Some
of
the

important
outcomes
of
Task
Force
research
included
the
establishment
ofa
government
agency
to
deal
with
telecommunications
policy
and
increased
emphasis
on
competition
and
deregulation.
Telecommunications
Policy
Research Conference
TPRC
An
annual

forum,
first
convened
in
1972
as
the
OTP
conference,
for
public
and
private
sector
scholars
and
decision-makers
to
discuss
recent
em-
pirical
and
theoretical
research
and
the
needs
of
the

telecommunications
industry.
See
Telecommunica-
tions
Policy,
Office
of.
/>Telecommunications
Reform
Act
An
act
by
the
U.S.
government
opening
up
local
and
long
distance
mar-
kets
to
competition.
The
act
included

a
highly
con-
troversial
provision
called
the
Communications
De-
cency
Act
(CDA)
which
was,
after
a
great
deal
of
dis-
cussion
and
input
from
the
Internet
community,
de-
clared
unconstitutional.

The
Reform
Act
significantly
altered
regulations
of
the
telecommunications
industry.
Telecommunications
Regulatory Email Grapevine
TREG.
An
informal
organization
that
carries
on
regu-
lar
online
discussions
about
real
world
issues
asso-
ciated
with

taking
products
and
services
through
the
various
regulatory
processes.
This
self-help,
group
an-
swers
queries
and
shares
experiences,
archiving
the
information
on
the
Web.
telecommunications relay service A
24-hour
tele-
phone
service
to

assist
hearing
impaired
individuals
to
intercommunicate
and
to
communicate
with
hear-
ing
subscribers.
This
service
may
have
a
variety
of
telebraille,
TTY,
and
voice
options.
In
general,
the
subscriber
calls

a
telephone
agent,
who
intercepts
the
call,
translates
it,
and
relays
it
to
the
callee
on
behalf
of
the
caller.
The
calls
and
call
content
are
confidential.
Telecommunications Research Establishment
TRE.
A

once-secret
facility
at
Malvern
where
com-
munications
research
such
as
radar
research
was
con-
ducted
during
World
War
ll.
The
TRE
was
established
in
1940,
evolving
from
the
Ministry
of

Aircraft
Pro-
duction
Research
Establishment
(MAPRE).
Some
of
the
early
research
in
digital
storage
devices
was
car-
'.
ried
out
here
towards
the
end
of
the
war.
Many
of
the

]~~.
researchers
at
this
facility
made
significant
scientific
achievements
in
a
number
of
fields
including
radio
astronomy.
See
Small
Scale
Experimental
Machine.
telecommunications service
This
is
defined
in
the
Telecommunications
Act

of
1996
and
published
by
the
Federal
Communications
Commission
(FCC),
as
"

the
offering
of
telecommunications
for
a
fee
directly
to
the
public,
or
to
such
classes
of
users

as
to
be
effectively
available
directly
to
the
pub-
lic,
regardless
of
the
facilities
used."
See
Federal
Communications
Commission,
Telecom-
munications
Act
of
1996.
Telecommunications Service Priority
TSP.
A
pro-
gram
of

the
Federal
Communications
Commission
(FCC)
for
identifying
and
prioritizing
telecommuni-
cations
services
that
support
national
security
and/or
emergency
preparedness
(NS/EP)
missions.
The
TSP
regulates,
administers,
and
operates
priority
restora-
tion

and
provisioning
of
qualified
NS/EP
telecommu-
nications
services
to
support
emergency
readiness
and
response
to
local,
national,
or
international
events
or
crises
that
might
harm
Americans
or
their
property.
/>913

© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Telecommunication
Standardization Bureau
TSB.
The
TSB
provides
support
for
the
standardization
sector
of
the
International
Telecommunication
Union
(ITU).
As
such,
it
helps
to
coordinate
the
work

of
the
lTU
-
T,
provides
secretarial
services,
assists
in
dis-
seminating
information,
and
ensures
the
publication
of
various
references
resulting
from
the
work
of
the
lTU-T.
See
International
Telecommunication

Union.
Telecommunications StandardsAdvisoryCouncil
of Canada
TSACC.
A
Canadian
industry-govern-
ment
alliance
formed
in
1991
to
develop
strategies
for
Canadian
and
international
standardization
in
in-
formation
technology
and
telecommunications.
Infor-
mation
on
telecommunications

technologies
is
pro-
vided
on
their
Web
site.
/>Telecommunications
Technology
Association
TTA.
Established
by
the
Korean
Ministry
of
Communica-
tion
in
1988, beginning operations
in
1992.
/>telecommuting
Virtual
commuting
to
the
work

site,
that
is,
communicating
through
various
telecommu-
nications
methods
instead
of
physically
traveling
to
the
work
site.
A
number
of
factors
have
contributed
to
the
increasing
desire
for,
and
availability

of,
tele-
commutingjobs:
increasing
congestion
in
cities
caus-
ing
higher
housing
costs
and
less
availability
ofhous-
ing;
increased
traffic
congestion;
more
families
with
two
working
parents
who
don't
want
to

leave
chil-
dren
unattended;
improved
telecommunications
ser-
vices,
with
faster
and
better transmission,
more
hookup
services
through
phone
lines,
and
videocon-
ferencing
options.
Telecommuting
is
not
for
everyone;
many
people
pre-

fer
to
work
under
direction
or
to
work
in
close
physi-
cal
proximity
to
co-workers,
but
many
work
better
undisturbed
and
will
use
the
time
saved
by
not
com-
muting

to
produce
a
higher-quality
product.
There
are
also
increasing
numbers
of
businesses
willing
to
pro-
vide
telework
options
so
that
they
can
recruit
highly
skilled
workers
from
diverse
regions.
See

telework,
virtual
office.
telecomputer, computerTVA
TV
broadcast
system-
computer
integrated
system
that
allows
a
user
to
con-
trol
program
selection
or
menu
options
for
viewing,
such
as
split
screen
for
more

than
one
show,
digital
effects,
sound
options,
integration
of
TV
and
phone
(e.g.,
on-screen
Caller
ill
on
the
TV
when
the
phone
rings),
email
and
Web
access,
shopping
from
home,

etc.
This
is
an
example
of
the
convergence
of
the
com-
puter
and
broadcast
industries.
Standards
for
ATM
for
the
home
are
being
promoted
so
that
standardized
commercial
consumer systems
can

be
developed
which
allow
these
many
technologies
to
link
and
work
together.
See
Broadband
Residential,
fiber
to
the
home,
Home
Area
Network,
WebTV.
teleconference A
telephone
conference
where
three
or
more

participants
share
in
a
conversation.
Confer-
ence
call
buttons
or
codes
are
available
on
some
lo-
cal
multiline
systems,
and
operators
can
set
up
con-
ference
calls
across
public
lines

for
participants
who
are
distant
from
one
another.
See
videoconference.
telecopier
See
facsimile
machine.
914
teledensity A
measure
of
the
number
of
telephone
lines
per
100
POPs
(individual
people)
used
to

as-
sess
service distribution,
economic
compromises,
revenues,
etc.
Teledesic,
LLC A
privately
owned
constellation of
literally
hundreds
of satellites orbiting
at
700
km
(LEO)
designed
to
provide
switched
broadband
bi-
directional
network
services,
including
Internet

ac-
cess,
data,
voice,
videoconferencing,
and
interactive
multimedia.
It
is
designed
to
operate
at
up
to
64
Mbps
for
downlink
and
up
to
2
Mbps
for
uplink.
The
top
transmissions

speed
is
more
than
2000
times
faster
than
standard
modems
operating
over
wired
phone
lines.
Connection
is
through
small
parabolic
antennas.
The
Teledesic
group
approached
the
Federal
Com-
munications
Commission

(FCC)
in
1994
for
a
500-
MHz
frequency
allocation
within
the
Ka-band
for
this
service.
In
May
1998,
Motorola
Inc.
joined
the
venture
as
the
prime
contractor,
bringing
in
its

Celestri
technology,
along
with Boeing
Company
and
Matra
Marconi
Space,
a
European
satellite
manufacturer.
In
August
2001,
the
company
announced
that
either
Lockheed
Martin Commercial
Space
Systems
(LMCSS)
or
Alenia
Spazio
(an

Italian
vendor)
would
be
selected
as
the
prime
contractor
to
build
the
network
as
both
had
experience
in
building nongeostationary-orbit
satellite
systems.
In
November
2001,
a
talked
about
merger
with
another

McCaw
company,
ICO
Global
Communications
was
discontinued.
In
February
2002,
an
agreement
was
signed
with
Alenia
Spazio
to
contract
the
systems.
Teledesic
LLC
is
a
McCaw/Gates
company
sched-
uled
to

launch
its
satellites
in
the
early
2000s
and
to
be
in
service
by
2005.
TeleDirectory A
telephone
directory
service
from
British
Telecom
for
personal computer
users
who
have
a
frequent
need
for

directory
assistance
services
(e.g.,
five
or
more
numbers
per
day)
and
wish
to
ac-
cess
the
number
online.
Enquiries
are
billed
on
aper-
number
basis.
See
BT
Phonebase.
Telefunken A
German

radio
station
founded
in
1903
soon
after
Marconi's
wireless
demonstrations
in
Lon-
don,
England,
excited
the
imaginations
of
radio
ex-
perimenters
and
future
broadcasters.
telegaming
Gaming
over
a
distance
communications

medium
(telephone,
computer
network,
postal
ser-
vice).
Telegaming
has
been
around
for
a
long
time.
F
or
centuries,
people
have
played
long
distance
chess
and
backgammon
games
by
messenger
and,

more
re-
cently,
by
mail
or
phone.
Currently
it
implies
an
un-
broken
connection,
since
that
is
now
possible
through
computer
networks
and
games
like
chess
and
go
are
routinely

played
on
the
Internet.
Video
arcade
games
are
played
on
local
networks,
usually
on
an
Ethernet
link,
although
the
term
telegaming
doesn't
apply
as
well
to
an
activity
in
which

the
participants
can
see
or
hear
one
another
in
the
same
or
next
room.
telegenic
Having
characteristics
that
appeal
to
tele-
vision
audiences,
such
as
charisma,
talent,
humor,
relevance
(news),

or
other
qualities
favored
by
broad-
cast
networks
and
viewing
audiences.
© 2003 by CRC Press LLC
telegram
Originally
telegramme
(France,
1793).
A
printed
record
ofa
telegraphic
communication.
Early
telegraph
signals
were
transcribed
on
paper

tape
as
wiggly
lines;
later,
audible
signals
were
interpreted
by
human
operators
and
written
down
by
hand;
and,
finally,
devices
that
could
interpret
the
signals
into
text
and
impress
them

on
paper
as
telegrams
were
devised.
For
decades
the
telegram
was
delivered
into
the
hands
of
the
intended
receiver
or
at
least
brought
to
the
doorstep.
Courier
services
and
facsimile

ma-
chines
are
superseding
telegram
services.
See
tele-
graph
system,
teletypewriter.
telegraph fire alarm
That
telegraph
signals
could
be
used
to
report
fires
through
signal
boxes
was
realized
not
long
after
the

invention
of
the
telegraph,
and
many
of
the
larger
communities
installed
this
type
of
safety
system
by
the
early
1900s.
The
Boston
Fire
Alarm
system
was
one
of
the
first,

following
a
published
description
of
its
feasibility
by
William
F.
Channing
in
1845.
Later,
with
the
help
ofa
telegraph
engineer,
Moses
G.
Fanner,
Channing
supervised
the
1851
city
funding
and

1852
construction of
the
first
fire
alarm
telegraph
in
the
world.
Originally
based
on
manual
crank
boxes,
painted
black,
the
mechanisms
were
later
changed
to
pull
switches,
and
eventually
dials.
By

1881,
the
fire
boxes
were
changed
to
red.
telegraph history
The
telegraph
was
a
system
of
equipment
and
data
encoding
that
enabled
commu-
nication
over
distance,
originally
through
drum
beats,
signal

fires,
and
signal
towers,
and
later
by
wires
pow-
ered
by
high-intensity
batteries.
As
with
many
tech-
nologies,
the
telegraph
was
invented
in
a
number
of
places
at
about
the

same
time,
and
many
of
the
early
models
were
never practically
or
commercially
implemented.
In a
sense,
the
technology
has
come
full-circle.
Many
of
the
earliest
modern
telegraphs
were
optical
tele-
graphs

which
gradually
gave
way
to
electrical
sys-
tems
and
now,
200
years
later,
we
are
returning
to
the
use
of
optics,
channeled
automatically
through
fiber
rather
than
being
transmitted
by

humans
through
air.
Lesage
had
created
africtional
telegraph
as
early
as
1774,
and
A.
Ampere
and
P.
Barlow
proposed
early
designs
as
well.
1.
Munro
reports
that
someone
iden-
tified

only
as
C.M.
described
an
electric
telegraph
in
Scots
Magazine
in
February
1753
that
suggested
a
multi-wire
system
(similar
to
those
later
implemented
by
Campillo
in
Spain
and
Sommering
in

Germany).
If
so,
it
is
the
earliest
recorded
reference
to
a
modern
telegraph
system.
Samuel
T.
von
Sommering
created
a
35-wire
telegraph
based
upon
electrochemical
con-
cepts
which,
in
turn,

was
derived
from
the
work
of
Francesc
Salva
i
Campillo
in
Spain,
in
1795.
Optical
telegraphs
were
developed
by
Claude
and
Ignace
Chappe
in
the
early
1790s
and
were
probably

built
upon
the
ancient
tradition of
signal
fires.
The
Chappe
system
used
physically
coded
letters
and
symbols
relayed
through
a
system
of
towers
by
hu-
man
"transceivers."
The
concept
spread
to

other
parts
of
Europe,
including Denmark, where
an
optical
postal
telegraph
was
established
in
1801.
One
of
the
first
practical
commercial
implementations
ofa
nonoptical
telegraph
was
in
1837
by
C.
Wheat-
stone

and
W.
Cooke
in
England.
The
telegraph
in
America
owed
much
of
its
design
and
development
to
Samuel
Morse
and
Alfred
Vail.
Morse's
original
telegraph
caveat
(an
intention
to
file

a
patent)
de-
scribed
a
mechanism
with
a
horizontally
moved
key
which
made
corresponding
zigzag
marks
on
a
mov-
ing
paper
tape
to
represent
numbers,
which
were
then
looked
up

to
find
the
corresponding
words
in
a
refer-
ence
dictionary
prepared
by
Morse.
Vail
improved
on
the
mechanics
of
the
key,
making
it
move
up
and
down
instead
of
side-to-side,

thus
forming
dots
and
dashes
with
breaks
in
between
on
the
paper.
As
this
system
was
simpler
and
more
direct
than
doing
a
dic-
tionary
lookup,
it
evolved
into
the

system
now
known
as
Morse
(Vail)
code.
Their
telegraphic
invention
was
demonstrated
to
the
Presidency
in
1838.
Morse
sub-
sequently
won
funding
from
Congress
to
construct
a
telegraph
long
distance

line,
carried
out
the
project
with
assistance
from
Ezra Cornell,
and
began
to
spread
telegraphy
throughout
America
in
the
mid-
1800s.
Both
Wheatstone
and
Morse
received
advice
and
encouragement
on
the development of tele-

graphic
instruments
from
Joseph
Henry
in
the
1830s.
Morse,
unfortunately,
didn't
duly
credit
Henry's
as-
sistance.
Historic
Telegraph
Communications
Technology
One
of
the early Bell telegraph patent documents.
There were many inventors at the time independently
makingsimilardiscoveries,
and
substantial competi-
tion to
be
the first to patent

and
commercialize the
new communication technologies.
In
its
simplest
form,
the
telegraph
consists
ofa
sender
(a
keying device), a receiver (with a sounder or
printer),
and
a
simple
code
for
conveying
characters.
Early
telegraph
receiving
machines
used
paper
tapes
to

record
messages
(Morse's
telegraph
created
a
wig-
gly
line),
but
operators
began
to
recognize
the
slightly
audible
incoming
clicks
and
could
copy
messages
faster
than
a
paper
tape
could
print

them,
so
machines
were
soon
equipped
with
sounders
and
resonators
to
amplify
and
direct these clicks.
Not
surprisingly,
915
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
many
inventors
sought
ways
to translate
the
signals
into

letters
that
could
be
recorded
directly,
as
in
a
tele-
gram
or
teletype-style printout.
One
of
the
first
to
succeed
was
David
Hughes,
a
schoolteacher,
in
1856.
In
America,
messages
were

sent
by
shutting current
on
and
off,
while
in
Britain, Wheatstone introduced
polar
keying,
a
means
of
using
polarity
to
convey
sig-
nals.
The
concept of polarity
is
still
used
today
in
high-speed
data
transmissions.

In
1866,
M.
Loomis
demonstrated
that
signals
could
be
sent
from
one
airborne
kite
to
another,
when
each
was
strung
with
fine
copper
wire
of
the
same
length,
without
direct

physical
contact.
This
later
lead
to
his
1872
U.S.
patent
for
awireless
improved
telegraphic
system,
although
it
was
some
time
before
his
discoveries
were
put
into
practical
use.
By
the

1880s,
scientific investigations
and
demon-
strations
had
confirmed
the
viability of wired
and
wireless
telegraphy.
The
end
of
the
century
then
be-
came
a
time
ofcreative application of
the
concepts
and
evolutionary
improvements
in
speed

and
practi-
cality.
In
1895
and
1896,
in
Russia,
A.S.
Popow
was
con-
ducting experiments
with
wireless telegraphy
and
succeeded
in
sending
a
shipboard
message
to
his
labo-
ratory
in
St.
Petersburg.

Unfortunately,
due
to
the
se-
crecy
surrounding
Russian
naval
technology
and
in-
ventions
in
general, Popow's discoveries
were
not
communicated
to
the
rest
of
the
world,
and
he
did
not
receive
credit

for
his
early experiments.
In
the
late
1800s,
telautographs
that
could
transcribe
handwriting
were
created
by
several
inventors
such
as
E.
Gray
and
F.
Ritchie.
While
these
were
used
for
several

decades,
they
didn't
originally
work
over
long
transmission
lines
and
were
superseded
by
telewriters
and,
eventually,
facsimile
machines.
In
1886,
Amos
Dolbear,
a
Tufts
University scientist
and
writer,
was
awarded
a patent

for
a wireless
tele-
graph
based
on
induction.
In
1889,
EG.
Creed
invented
a
High
Speed
Automatic
Printing Telegraph System.
By
1898, his Creed
Printer
could
transmit
60
words
per
minute
and
his
technology
was

widely
sold
in
many
countries.
He
broadened.his enterprise
in
1923
by
demonstrating
marine
wireless
printed
telegraphy,
a
system
even-
tually
used
for
marine
safety.
Wireless
telegraphy
was
ofinterest
almost
from
the

beginning oftelegraphic
history.
In
the
early
1900s,
V.
Poulsen
and
P.
Pedersen
used
an
electric
arc
to
generate
high-frequency
waves,
setting
the
ground-
work
for
wireless
communications.
Poulsen
also
de-
veloped

the
telegrafon, a historic electromagnetic
tape
recorder.
Tape
recorders
were
later
used
to
de-
velop
dictation
and
telephone
answering
machines.
The
telegraph
had
a
revolutionary
impact
on
commu-
nications,
changing
forever
the
concept

of
distance.
It
networked
the
predominantly
rural
early settlers of
North
America
and
spurred
the
installation of
the
first
transatlantic
cable,
providing
instant
(by
l800s
stan-
dards)
communication
with
Europe.
Prior
to
the

oce-
anic cable, messages typically
took
2 months or
longer
to
travel
in
ships
from
one
continent
to
the
916
other.
News,
business, warfare,
and
family
contacts
were
dramatically affected
by
the
availability offast
long
distance communications.
See
Creed,

Frederick
George;
heliotrope;
Davy,
Ed-
ward;
Dolbear,
Amos;
Morse,
Samuel
F.B.;
Popow,
Aleksandr Stepanowitsch; Salva i Campillo,
Francesc; S6mmering, Samuel Thomas; Steinheil,
Karl
August;
telegram;
telegraph
system;
telephone;
Wheatstone,
Charles.
telegraph
key
A mechanical
switch
on
early tele-
graph
systems

that
enabled
acircuit
to
be
opened
and
closed
in
order
to
generate transmissions through a
signal
such
as
Morse
code.
telegraph signals For telegraph signals through
wires,
two
main
methods
were
used:
polar transmis-
sion,
in
which
the
polarity

was
changed
to
reverse
the
current;
and
neutral,
or
open/close transmission,
in
which
open
current
(space)
was
interspersed
with
no
current
(mark).
telegraph
system An apparatus
for
sending
and/or
receiving information
over
distance,
coded

in
some
fashion,
usually
in
Morse
code
dots
and
dashes.
A
basic
telegraph circuit consists of a
key
to
translate
finger
or
other mechanical pressure
into
signals, a
relay
sensitive
to
the
very
small
current
that
may

be
coming through
the
wire,
and
a receiving device
which
can
express
the
message
by
means
ofaudible
tones,
paper
tape
code,
or
printed letters.
Telegraph
systems
have
coexisted
with,
rather
than
been
superseded
by,

telephone
systems
for
a number
of
reasons,
including
the
expense
and
time
delays
of
setting
up
long
distance
toll
calls
to
some
areas,
and
the
importance,
in
some
situations, of
creating
awrit-

ten
record
in
the
form
ofa
telegram.
With
electronic
telephony advancing
and
facsimile machines prolif-
erating,
the
telegraph
is
becoming
more
historically
interesting
than
practical.
See
telegraph
history;
tele-
graph,
needle.
Telegraph Network System
A telegraph network map

of
the United States pub-
lished
ca.
1870 which shows the Pony Express Mail
& Telegraph Route
(in
spite
of
the
fact
that the Pony
Express was velY shortlived).
telegraph, needle A
type
of five-needle telegraph
devised
by
Charles Wheatstone
and
put
into
service
in
England
in
1837.
Faulty equipment
lead
to

the
© 2003 by CRC Press LLC
gradual
realization,
by
telegraph
operators,
that
two
needles
were
sufficient
and,
eventually,
only
one
needle
and
one
dial
were
used
to
efficiently
convey
messages.
The
needle
telegraph
also

represents
the
development
ofpolar
keying,
which
employed
posi-
tive
and
negative
voltages
for
indicating
mark
and
space
signals.
See
polar
keying.
telegraph, printing
Early
telegraph
papertape
and
manually
operated
sounding
systems

did
not
satisfy
the
needs
of
inventors
and
users
who
wanted
quick,
automated
written
messages.
Thus,
the
development
of
printing
telegraphs
was
of
interest
to
many.
One
of
the
first

successful systems
was
developed
by
A.
Vail
in
1837,
employing
a
type
wheel.
Later
D.
Hughes
developed
a practical
working
type
wheel
system
in
1855,
which
became
established
in
Europe,
but
didn't

catch
on
well
in
America,
where
Morse
systems
were
in
use.
Improvements
to
printing
tele-
graphs
continued
and,
in
1846,
R.E.
House
developed
a
printer
that
printed
telegraphically
transmitted
let-

ters
directly.
Further
improvements
to
House's
sys-
tem
resulted
in
a patent in
1852.
In
1905,
Donald
Murray
published
"Setting
Type
by
Telegraph"
in
the
Journal
of
the
Institute
of
Electrical
Engineers

and
went
on
to
improve
telegraphy
in
a
number
of
ways.
The
necessity
of
noise-free
transmissions
and
tech-
nical
expertise
to
maintain
the
equipment
prevented
printing
telegraphs
from
coming
into

widespread
use
until
decades
later.
See
teletypewriter.
Historic
Automatic
Telegraph
System
An
automatic telegraph
sender.
The
wheels shown
at
the
top
represented
characters
that
could
be
selected
and placed
in
order
to
spell out a

message.
This
ex-
ample
is
from
the
American Radio
Museum
collec-
tion.
telegraphese A
terse,
abbreviated
mode
of
messag-
ing
(or
speaking)
which
has
the
character
ofa
tele-
gram.
Since
telegrams
were

often
charged
by
the
let-
ter
or
by
the
word,
a
compact
style
of
communica-
tion
emerged
in
order
to
keep
the
cost
as
low
as
prac-
tical.
telegraphone, telegrafon
This

is
not
only
a
type
of
telegraph
instrument,
but
more
important,
was
an
early
electromagnetic
tape
recorder,
designed
in
1898
by
Danish
inventor
Valdemar
Poulsen.
Poulsen
suc-
ceeded
in
recording

electronic
waves
on
a
thin
wire
of
steel,
and
improved
on
the
technology
enough
to
receive
a u.S. patent
in
1890.
This
developed
into
dictating
machines
sold
through
the
American
Tele-
graphone

Company.
See
tape
recorder.
TeleLink Project
The
full
name
is
TeleLink
Train-
ing
For
Europe
Project.
This
is
a
European
Commu-
nity
(EC),
Euroform-funded
project
which
seeks
to
promote
and
develop

telework
training
opportunities
and
qualification
guidelines.
This
includes
qualifica-
tion
level
certification (currently
at
the
vocational
level)
for
teleworkers
and
a
system
of
TeleLink
cen-
ters
around
Europe.
See
ADVANCE
Project,

tele-
work.
telemarketing
The
promotion
of
products
and
ser-
vices
through
telephone
calls
to
individual
premises.
There
are
various
regulations
governing
when
tele-
marketers
may
call,
whom
they
may
call

(e.g.,
calls
to
a
person
at
his
or
her
place
of
business
must
be
stopped
if
the
callee
requests
it),
and
what
they
must
say
to
identify
themselves
and
their

affiliations.
There
are
also
restrictions
on
where
they
may
obtain
names,
and
how
they
must
dial
the
call.
Many
scams
have
been
perpetrated
through
telemarketing
schemes,
and
it
is
important

for
the
callee
to
get
sufficient
infor-
mation
to
ascertain
that
the
offering
is
legitimate.
If
you
don't
wish
further calls
from
the
source,
you
should
request
that
your
name
be

taken
off
their
list.
See
war
dialer
telemarketing broadcasts
The
promotion
of
prod-
ucts
and
services
through
mass
market
advertising
usually
providing
a
1-800
or
1-900
number
for
the
interested
buyer

to
call.
Automated
systems
for
tak-
ing
the
caller's
name
and
billing
information
through
touchtone
selections
are
becoming
prevalent.
telemedicine
Medical
information
and
services
and
medical
education provided
over
distance
through

telephone,
radio,
facsimile,
videoconferencing,
and
the
Internet.
Information
such
as
medical
imaging
results
can
readily
be
transferred
as
data,
since
much
ofit
is
digital
in
nature.
Teaching
and
other
commu-

nications
among
medical
professionals
and
their
pa-
tients
are
possible
through
newer
technologies.
telemetry, telemetering
The
art
and
science
of
gath-
ering
information
at
one
location,
usually
in
terms
of
some

quantity,
and
transmitting
that
information
to
another
location
for
storage,
analysis,
or
evaluation.
Weather
balloon
data
gathering
and
transmission
through
a
radiosonde
to
a weather
station
for
inter-
pretation
is
one

example
of
telemetry.
The
transmit-
ting
of
information
from
space
probes
is
another.
Te-
lemetry
equipment
is
typically
included
on
artificial
satellites
to
aid
in
the
control
and
orientation
of

the
satellites.
TeletextA
commercial
computer
service
offered
by
NBC,
which
was
discontinued
in
1985.
Many
of
these
early
computer
services
came
and
went,
but
they
are
coming
back
in
updated

forms
now
that
there
is
a
large
user
base
drawn
to
the
Web.
telephone A communications apparatus
designed
primarily
to
convey
human
voice
communications.
In
its
simplest
form,
a
telephone
consists
of a
tran-

sistor
that
converts
sound
into
electrical
impulses,
and
917
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
a receiver, which converts
them
back again into
sound.
Additional
technology
is
used
to
amplify
and
direct
the
communication
between
these

two
basic
de-
vices.
The
design
of
the
telephone set
has
gone
through
five
overlapping
phases
in
its
development.
See
the
Telephone
Development
Phases
chart.
See
telephone
history.
Historic
Telephone
The earliest telephone was a simple device that

looked more like a pinhole camera than current
fa-
miliar desktop phones
and
mobile handsetphones.
telephone amplifier A
device
to
amplify
sounds
at
the
receiving
end
ofa
call.
This
can
be
incorporated
into
the
handset,
headset,
or
speakerphone,
or
may
be
an

add-on
to
provide
even
more
amplification
for
the
hard
of
hearing.
Most
handset
telephone
amplifi-
ers draw current
from
the
phone line, but
many
speakerphones
and
add-on
amplifiers
require
a
sepa-
rate
power
source.

The
amplifier
is
often
adjustable
through
a
dial
or
slider
on
the
side
of
the
phone.
telephone answering machine
An
electronic
or
me-
chanical
device
for
answering
calls
and
often
for
re-

cording
them
digitally
or
on
tape.
Telephone
answer-
ing
machines
based
on
reel-to-reel
mechanisms
have
been
available
since
the
early
1960s,
but
small
cas-
sette
and
digital
answering
machines
did

not
become
common
until
the
late
1970s
and
early
1980s.
Most
households
now
have
answering
machines
to
respond
to
calls,
take
messages,
or
screen
calls.
Many
of
these
will
include

information
on
the
time
and
date
of
the
call,
and
some
will
record
the
identity of
the
caller,
if
Caller
ill
is
activated
on
the
subscriber
line.
Computer
voicemail
applications
can

also
be
hooked
to
a
phone
line
through
a data/fax/voice
modem
to
allow
the
software
to
function
as
a
full-featured
an-
swering
machine
with
multiple
mailboxes.
telephone answering service
1.
A
service
offered

by
commercial
vendors
in
which
a
human
operator
or
voice-automated
system
will
answer
the
subscriber's
phone
line
when
it
is
call
fOIWarded,
or
when
the
an-
swering
service
number
is

called
directly
and
for-
wards
the
message
to
the
subscriber.
This
service
is
widely
used
by
small
businesses,
freelancers,
and
real
estate
agents.
Sometimes
these
services
are
combined
with
paging.

2.
A
service
offered
by
local
phone
com-
panies
in
which
a
human
operator
or
voice-automated
918
system
will
take
calls
and
fOIWard
messages
to
the
subscriber,
or
through
which

the
subscriber
can
use
a
touchtone
phone
to
retrieve
messages.
telephone central
office
See
central
office.
telephone circuit
An
electrical
connection
consist-
ing
minimally
ofa
transmitter,
receiver,
amplifier,
and
connecting
wires,
and

more
commonly
comprising
a
system
of
two-way
audio
and
signaling
connections
between
local
exchanges
and
subscriber lines
and
telephones.
Telephone
Company of Prince Edward Island A
historic
telephone
exchange,
incorporated
in
1885,
the
year
after
the

phone
exchange
was
first
established
on
the
island.
telephone exchange
Switching
center
for
telephone
circuits.
See
central
office,
private
branch
exchange.
Innovative Optical
Telephone
An innovative optic telephone, based on the stimu-
lation through a diaphragm
of
aflamefrom an acety-
lene burner. The impulses were thenfurther transmit-
ted optically through a light-sensitive selenium
cell
and

reflector. The optic telephone was developed by
Ernst Ruhmer,
and
was used
for
long distance com-
munications.
[Scientific American,
November
1,
1902.}
telephone history
The
telephone
was
a significant
evolutionary
development,
occurring
a
few
decades
after
the
invention of
the
telegraph.
While
the
tele-

graph
revolutionized
telecommunications
by
making
communications
over
great distances possible,
the
telephone
personalized
it,
and
many
inventors
were
excited
by
the
potential of sending
tones,
or
even
voice,
over
phone
lines.
The
use
of

tubes
and
strings
to
magnify
sound
and
channel
acoustic
vibrations
existed
at
least
as
early
as
the
time
of
Robert
Hooke,
long
before
the
devel-
opment
of
modem
telephones,
but

such
devices,
like
the
acoustic tubes demonstrated
in
1682
by
Dom
Gauthey,
were
physically
limited
as
to
loudness
and
distance.
It
was
not
until
electricity
and
magnetism
were
harnessed
that
amplified,
long-distance

modem
telephony
was
possible.
In
the
early
1800s,
German
inventor
Philip
Reis
ob-
served
that
a
magnetized
iron
bar
could
be
made
to
© 2003 by CRC Press LLC
emit
sound.
In
America,
Charles
Page

made
a
similar
discovery,
terming
the
sound
"galvanic
music."
Sub-
sequently, a number of inventors advanced tele-
graphic
and
microphonic
technologies
leading
up
to
the
invention of
the
telephone. Belgian inventor
Charles
Bourseul
described
his
idea
for
transmitting
tones

in
1854,
but
wasn't
able
to
implement
a
fully
working
version
before
Philip
Reis
and
Alexander
Graham
Bell
developed
their
own
telephonic
devices.
Reis
first
demonstrated
the
transmission
of
tones

through
wire
in
Frankfurt
in
1861.
He
reported
in
a
letter
that
he
could
transmit
words,
but
there
is
no
direct
way
to
verify
the
claim.
Around
the
time
ofReis's

death,
an
American
physi-
cist,
Elisha
Gray,
was
making
numerous
experiments
in
telegraphy
and
developed
early
concepts
for
har-
monic
telegraphy,
the
transmission
of
tones,
and
te-
lephony.
In
the

mid-1800s,
Italian-born
Antonia
Meucci
was
successfully
experimenting
with
wires
attached
to
animal
membranes
to
transfer
sound
through
current,
but
news
of
his
significant
discoveries
did
not
become
widely
known
outside

Cuba.
When
he
later
emigrated
to
the
U.S.,
he
filed
a
caveat
for
a
patent,
in
Decem-
ber
1871,
for
a
teletrofono.
Bell's
Telephone
Demonstration
Here
Alexander
Graham
Belldemonstrates his
tele-

phone invention.
The
inset shows one
of
his early
sketches
of
the
invention,
from
the famous Bell note-
books.
Bellachievedgreatfinancial success
from
com-
mercializing his discoveries.
The
better-known precursors
to
the
telephone
in
America
and
later variations
appear
to
have
been
in-

vented
more-or-Iess
independently
by
Elisha
Gray
and
Alexander
Graham
Bell,
but
Bell
filed
his
tele-
phone
patent
(it
was
actually
a precursor
to
the
tele-
phone,
a
hannonic
telegraph)
a
few

hours
before
Gray
filed
a
caveat
(intention
to
file
within
3
months)
in
February
1876.
The
murky
history
of
the
invention
of
the
telephone
at
this
point
stems
in
part

from
the
fact
that
many
innovations
were
being
developed
si-
multaneously
and
also
because
the
inventors
under-
stood
the
great
commercial
potential
of
their
devices.
Hundreds
of
lawsuits
were
threatened

and
filed
over
the
next
few
decades,
although
some
claims
were
more
amicably
settled.
For
example,
in
January
1877,
Bell
wrote
to
Gray
rescinding
any
previous
accusa-
tions
he
may

have
made
that
Gray
copied
from
Bell's
work.
(In
fact,
both
men
may
have
copied
from
a
third
source,
Antonia
Meucci.
It
has
been
suggested,
but
not
confirmed,
that
both

Bell
and
Gray
had
access
to
Meucci's
teletrofono
documents
when
they
were
in
the
hands
of
Western
Union.)
Emil
Berliner
was
an
inventor
with
a
strong
interest
in
music and the improvement
of

the
quality of
transmission of
sound
(which
applied
equally
well
to
telephony).
In
April
1877,
he
filed
a
caveat
for
a
patent
for
a
telephone
transmitter,
three
and
a half
months
before
Thomas

Edison
applied
for
a
patent
for
a
similar
device.
In
a
1911
lecture
on
the
origins
of
the
membrane
tele-
phone,
Bell
described
how
he
worked
out
the
idea
in

discussions
with
his
father
while
on
a
family
visit
in
Canada
in
the
summer
of1874,2
years
before
it
was
successfully
implemented.
Bell
and
Watson
reported
that
Bell
first
spoke
intelligibly

over
wires
in
March
1876.
The
transmission
succeeded
by
use
ofa
liquid
medium,
something
not
mentioned
in
Bell's
patent.
This
voice
capability
was
not
publicly
demonstrated
until
some
time
later,

which
seems
odd
given
the
magnitude
of
the
reported
achievement.
Ironically,
Bell
had
been
discouraged
by
investors
from
trying
to
make
a
talking
telegraph
and
was
prodded
to
con-
centrate

on
a
harmonic
telegraph
instead.
Gray
had
publicly
demonstrated
rudimentary
tele-
phone-related
technology
before
the
Bell
patent
was
filed,
and
later
successfully
earned
a
number
of
tele-
phone-related
patents.
He

designed
a
telephone
in
the
1870s
not
unlike
the
second-generation
switch-hook
phones
that
employed
separate
ear
and
mouth
pieces
which
came
into
use
in
later
years.
The
first
commercial
telephone

exchange
was
estab-
lished
in
Connecticut,
U.S.,
and
became
operational
in
1878.
It
was
followed
the
same
year
by
the
second
commercial
exchange
in
Ontario,
Canada.
The
Bell
patents
formed

the
basis
of
the
early
Bell
System
in
the
United
States,
a
company
that
has
in-
fluenced
the
development
of
communications,
and
thus
the
course
of
history,
in
countless important
ways.

The
Bell
Telephone
Company
of
Canada
was
incorporated
in
1880.
By
this
time,
telephone
technology
began
to
spread
to
other
nations
outside
Europe
and
North
America.
The
first
telephone
exchange

was
established
in
Ja-
pan
in
1890
in
the
TokyoNokohama
region.
In
1926,
automatic
step-by-step
switches
were
introduced
in
Japan.
The
most
interesting
evolutionary
step
in
telephone
technology,
besides
the

growth
of
wireless
commu-
nications,
is
probably
the
videophone, descended
from
early
picture
telephones
such
as
the
Picture-
phone.
The
Bell
Labs
were
transmitting
pictures
in
the
late
1920s
and
demonstrated

the
early
technol-
ogy
to
the
Institute of
Radio
Engineers
in
1956,
but
it
was
not
until
1964
that
a practical
experimental
system
was
completed and
the
Picturephone
was
919
© 2003 by CRC Press LLC
Fiber
Optics

Illustrated
Dictionary
exhibited cooperatively
by
Bell
and
the
American
Telephone
and
Telegraph
Company
(AT&T)
at
the
New
York
World's
Fair.
Currently
many
companies
are
scrambling
to
be
the
first
to
get

a
cheap,
publicly
accepted
version
ofa
pic-
ture
telephone
or
as
they
are
known
now,
audiograph-
ics
systems,
videophones,
or
videoconferencing
sys-
tems.
With
the
growth
of
the
Internet
and

the
drop
in
price of
small
video
cameras,
they
began
to
be
com-
mon
computer peripherals
in
2002.
Another significant
change
in
telephony
has
been
the
sending of
voice
over
computer
networks
by
means

ofa specialized handset attached
to
a
computer.
This
permits
the
connection of
long
distance calls
world
round
without
any
long
distance
toll
fees.
The
tech-
nology
threatens
to
dramatically change
the
estab-
lished
economic
structure of
the

telephone
system,
and
it
is
difficult
to
predict
whether
the
same
revenue-
generating
model
that
has
worked
for
about
100
years
will
be
viable
in
the
future,
given
the
current

rate
of
change.
In
fact,
some
of
the
long
distance carriers,
worried
by
this
threat
to
their survival,
have
lobbied
for
this
type
oftransmission
to
be
blocked.
See
Bell,
Alexander Graham; Berliner, Emil; Bourseul,
Charles; Callender switch;
Gray,

Elisha; Meucci,
Antonio;
Photophone;
Reis,
Philip.
See
telegraph
his-
tory
which
has
a
common
ancestry
and
additional
details.
telephone landline density A
measure
of
the
num-
ber
of
installed
phone
lines
per
100
people.

telephone pickup
Any
of several devices
for
con-
necting
into
an
ongoing
telephone
conversation,
usu-
ally
for
monitoring
purposes.
Telephone Pioneers of America
TPA.
A nonprofit
organization
founded
in
1911,
with
chapters
through-
out
the
United
States

and
Canada.
Originally consist-
ing
of
telephone
pioneers
with
25
years ofservice
or
more,
with
Theodore
N.
Vail
as
its
first president,
membership later
opened
up
to
a wider
group,
now
numbering almost 100,000,
as
fewer pioneers re-
mained

from
the
original
group.
TPA
engages
in
a number of community-oriented
activities, with a particular
focus
on
education. A
somewhat analogous organization serving non-Bell
employees
is
the
Independent Pioneers.
/>telephone receiver
The
portion ofa handset, head-
set, or speakerphone which converts electrical
impulses
into
sound.
On
a
handset,
the
receiver
is

the
part
that
you
hold
up
to
your
ear.
Inside a
basic
tradi-
tional
receiver
is
a
magnet,
with
coils
wound
around
the
poles
connected
in
series
and
a light,
thin,
vibrat-

ing
diaphragm mounted very close
to
the
magnet
poles.
When
current
passes
through
the
coils,
the
dia-
phragm vibrates, producing
sound
by
moving
the
air
next
to
it.
Early receivers
used
a
bar
magnet,
which
later

was
replaced
by
a
horseshoe
magnet.
See
tele-
phone transmitter.
Telephone Relay Service A telephone service
en-
abling
handicapped
individuals
to
communicate
over
telephones through
third
party interpreters.
It
is
usu-
ally
provided
free
of
charge.
telephone repeater
An

amplification device em-
ployed
on
telephone circuits
to
rebuild
and
maintain
signals across distances,
which
otherwise would
be
subject
to
loss.
telephone signaling
Any
device
that
indicates
an
in-
coming
call, usually a
bell,
but
may
also
be
a

light
or
moving
indicator.
telephone switchboard A centralized distribution
point
for
managing telephone calls. Early switch-
boards
consisted
ofa
human
operator
answering
calls,
and
plugging a
large
physical
jack
into
the
receptacle
of
the
person
to
whom
the
call

was
being
patched.
The
first
commercial switchboard
in
North
America
Overview
of
Telephone Development Phases
Type
Time period Notes
original
invention
late
l800s
Proof of
concept,
tbe
first
discernible,
intelligible
buman
voices
can
be
heard
over

distances.
hand
crank
pbones
late
1800s,
early
1900s
Pbones
were
large,
to
accommodate
a
battery,
and
had
to
be
cranked
to
send
a ringing
current.
Hand-crank
phones
were
still
in
use

in
rural
areas,
including
some
of
the
San
Juan
Islands
in
the
1960s.
dial
phones
early
1900s
to
1980s
Common
batteries
and
automatic
switching
systems
made
it
possible
to
create

smaller,
line-powered
phones
and
rotary
dials
so
the
subscriber
could
direct
dial
a
local
call,
and
later,
long-distance
calls.
touch
tone
phones
late
1970s
to
present
Phones
that
sent
tones

rather
than
pulses
through
the
line,
which
were
interpreted
according
to
pitch.
This
made
automated
menu-controlled
systems
possible.
digital
phones
early
1990s
to
present
Interface
speakers
or
beadset
peripherals
that

attach
directly
to
a
computing
device
or
desktop
system
to
enable
the
user
to
talk
into
a digitizing
program
that
samples
the
sound
and
transmits
it
over
public
data
networks.
920

© 2003 by CRC Press LLC
Semiautomatic Telephone Switching System
went
into
operation
in
Connecticut
in
1878.
Switches
were
mechanized
in
the
mid-1900s,
although
it
was
not
uncommon
for
human
switchboard
operators
to
staff
manual
switchboards
in
rural

areas
and
private
branches until the 1950s. Although mechanical
switchin~
stations
still
exist,
updated
switchboards
function
electronically.
telephone tag
Colloquial
phrase
for
two
parties
at-
tempting
to
contact
one
another
by
phone,
not
reaching
the
other person,

and
leaving messages with
an
answering
machine,
operator,
or
voice
mail
system.
Doing
this
back
and
forth
a
few
times
is
telephone
tag.
telephone transmitter
The
portion of a handset,
headset,
or
speakerphone
which
converts
sound

into
electrical
impulses.
On
a
traditional
handset,
the
re-
ceiver
circuit
connects
to
the
part
that
you
hold
next
to
your
mouth.
Inside
the
mouthpiece
is
a
movable
diaphragm
with

an
attached
carbon
electrode,
behind
which
another
carbon
electrode
is
fastened
securely
inside
the
housing.
Between
the
electrodes
are
car-
bon
granules
(it's
possible
to
build
a
simple
phone
transmitter

using
the
core
of
a
carbon
pencil laid
across
two
conducting
surfaces
connected
to
wires
and
a
diaphragm).
When
a
current
is
applied,
resis-
tance
decreases,
as
a result of
the
carbon
granules

compressing
more
closely
together.
Thus
the
current
increases
and
attracts
the
diaphragm
more
strongly.
The
diaphragm
vibrates
to
produce
an
electrical
im-
pulse
that
corresponds
to
the
movement
of
air

caused
by
the
speaker's
voice.
An
induction
coil
may
also
be
used
to
increase
the
voltage
to
compensate
for
sig-
nalloss
through
the
transmissions
medium.
See
Blake
transmitter,
coherer,
telephone,

telephone
receiver.
telephone user interface
TUI.
The
use
of
telephone
equipment,
usually
a
handset
or
headset
or
telephone
line
attached
to
a peripheral
card,
to
interact
with
computer
software.
Instead
of
using
a

keyboard
and
mouse
as
the
input
devices,
voice
or
touchtones
over
the
handset
or
phone
line
are
used
to
control
the
ac-
tions
of
the
computer.
For
example,
you
may

have
a
computer
set
up
like
an
answering
machine
to
answer
calls,
respond
to
callers,
and
log
time,
date,
and
caller
messages.
Then,
from
a
remote
location,
you
may
call

the
line
attached
to
the
computer,
and
by
speaking
or
pressing
touchtone
buttons,
have
the
computer
send
back
information
about
the
calls
or
replay
the
calls.
telephony
The
science
and

practice
of
transmitting
audio
communications
over
distance,
that
is,
over
a
greater
distance
than
these
communications
could
be
transmitted
without
technological
aid.
The
term
has
broadened
from
audio
communications
to

encompass
a
wide
variety of
media,
typically
now
including
vi-
sual
communications
that
accompany
sound
commu-
nications
(as
in
audiographics
and
videoconferenc-
ing),
although
it
is
preferred
that
the
more
general

term
telecommunication
be
used
for
audio/visual
transmissions.
Most
telephony
occurs
over
wires,
but
wireless
services
transmitted
by
radio
waves
and
sat-
ellite
links
are
increasing.
I
Telephony,
in
its
simplest

sense,
is
not
a
high
band-
width
application;
each
conversation
requires
only
a
narrow
channel,
but
because
of
its
continuous
bidi-
rectional nature, bandwidth
needs
increase
as
the
number
of
simultaneous
calls

increases.
Traditional
telephony
media,
such
as
copper
wires,
are
no
longer
strictly
used
for
oral
communications;
they
now
ser-
vice
a
large
number
of
data
transmission
services
such
as
Internet

connectivity,
facsimile
transmission,
and
more.
Due
to
increased
demands
for
lines
with
greater
speed
and
accuracy
than
are
needed
for
simple
voice
transmissions,
fiber
and
coaxial
technologies
are
be-
ing

used
to
upgrade
data
lines
and,
consequently,
the
phone
lines.
See
HFC,
telephone,
telegraph.
Telephony
Application Interface
TAP!.
A
standard-
ized
telephone
interface
developed
by
Microsoft
and
Intel Corporation
for
the
creation of a variety of

A schematic
for
a historic semiautomatic telephone switching system (it still required a human operator
to
turn a
spring-loaded knob to
send
the dialpulses through the wire). [Scientific American, October
11,
1902.]
921
© 2003 by CRC Press LLC