<s>
A	O
party	B-Architecture
line	I-Architecture
(	O
multiparty	O
line	O
,	O
shared	O
service	O
line	O
,	O
party	O
wire	O
)	O
is	O
a	O
local	B-Architecture
loop	I-Architecture
telephone	B-Architecture
circuit	I-Architecture
that	O
is	O
shared	O
by	O
multiple	O
telephone	O
service	O
subscribers	O
.	O
</s>
<s>
Party	B-Architecture
line	I-Architecture
systems	O
were	O
widely	O
used	O
to	O
provide	O
telephone	O
service	O
,	O
starting	O
with	O
the	O
first	O
commercial	O
switchboards	O
in	O
1878	O
.	O
</s>
<s>
A	O
majority	O
of	O
Bell	O
System	O
subscribers	O
in	O
the	O
mid-20th	O
century	O
in	O
the	O
United	O
States	O
and	O
Canada	O
were	O
served	O
by	O
party	B-Architecture
lines	I-Architecture
,	O
which	O
had	O
a	O
discount	O
over	O
individual	O
service	O
.	O
</s>
<s>
British	O
users	O
similarly	O
benefited	O
from	O
the	O
party	B-Architecture
line	I-Architecture
discount	O
.	O
</s>
<s>
Farmers	O
in	O
rural	O
Australia	O
and	O
South	O
Africa	O
used	O
party	B-Architecture
lines	I-Architecture
,	O
where	O
a	O
single	O
line	O
spanned	O
miles	O
from	O
the	O
nearest	O
town	O
to	O
one	O
property	O
and	O
on	O
to	O
the	O
next	O
.	O
</s>
<s>
Telephone	O
companies	O
offered	O
party	B-Architecture
lines	I-Architecture
beginning	O
in	O
the	O
late	O
1800s	O
,	O
although	O
subscribers	O
in	O
all	O
but	O
the	O
most	O
rural	O
areas	O
may	O
have	O
had	O
the	O
option	O
to	O
upgrade	O
to	O
individual	O
line	O
service	O
at	O
an	O
additional	O
monthly	O
charge	O
.	O
</s>
<s>
Party	B-Architecture
lines	I-Architecture
provided	O
no	O
privacy	O
in	O
communication	O
.	O
</s>
<s>
They	O
were	O
frequently	O
used	O
as	O
a	O
source	O
of	O
entertainment	O
and	O
gossip	B-Application
,	O
as	O
well	O
as	O
a	O
means	O
of	O
quickly	O
alerting	O
entire	O
neighbourhoods	O
of	O
emergencies	O
such	O
as	O
fires	O
,	O
becoming	O
a	O
cultural	O
fixture	O
of	O
rural	O
areas	O
for	O
many	O
decades	O
.	O
</s>
<s>
The	O
rapid	O
growth	O
of	O
telephone	O
service	O
demand	O
,	O
especially	O
after	O
WWII	O
,	O
resulted	O
in	O
many	O
party	B-Architecture
line	I-Architecture
installations	O
in	O
the	O
middle	O
of	O
the	O
20th	O
century	O
in	O
the	O
United	O
States	O
.	O
</s>
<s>
Nearly	O
three-quarters	O
of	O
Pennsylvania	O
residential	O
service	O
in	O
1943	O
was	O
party	B-Architecture
line	I-Architecture
,	O
with	O
users	O
encouraged	O
to	O
limit	O
calls	O
to	O
five	O
minutes	O
.	O
</s>
<s>
In	O
December	O
1942	O
,	O
University	O
of	O
Tennessee	O
's	O
strategy	O
in	O
an	O
American	B-Application
football	I-Application
game	O
versus	O
University	O
of	O
Mississippi	O
was	O
revealed	O
to	O
the	O
opposing	O
coach	O
as	O
a	O
telephone	O
on	O
the	O
Ole	O
Miss	O
team	O
's	O
bench	O
had	O
been	O
inadvertently	O
wired	O
to	O
the	O
same	O
party	B-Architecture
line	I-Architecture
.	O
</s>
<s>
While	O
primitive	O
lockout	O
devices	O
to	O
prevent	O
two	O
subscribers	O
from	O
picking	O
up	O
the	O
same	O
line	O
at	O
the	O
same	O
time	O
were	O
proposed	O
relatively	O
early	O
,	O
multiple	O
simultaneous	O
calls	O
did	O
not	O
become	O
viable	O
until	O
the	O
initial	O
tests	O
of	O
transistorised	O
pair	B-Protocol
gain	I-Protocol
devices	O
in	O
1955	O
.	O
</s>
<s>
Many	O
jurisdictions	O
require	O
a	O
person	O
engaged	O
in	O
a	O
call	O
on	O
a	O
party	B-Architecture
line	I-Architecture
to	O
end	O
the	O
call	O
immediately	O
if	O
another	O
party	O
needs	O
the	O
line	O
for	O
an	O
emergency	O
.	O
</s>
<s>
In	O
May	O
1955	O
,	O
a	O
Rhinebeck	O
,	O
New	O
York	O
woman	O
was	O
indicted	O
by	O
a	O
grand	O
jury	O
after	O
her	O
refusal	O
to	O
relinquish	O
a	O
party	B-Architecture
line	I-Architecture
delayed	O
a	O
volunteer	O
firefighter	O
's	O
effort	O
to	O
report	O
a	O
grass	O
fire	O
.	O
</s>
<s>
In	O
June	O
1970	O
,	O
a	O
sixteen-year-old	O
girl	O
and	O
a	O
woman	O
were	O
charged	O
after	O
refusing	O
to	O
relinquish	O
a	O
party	B-Architecture
line	I-Architecture
to	O
allow	O
a	O
distress	O
call	O
as	O
three	O
boys	O
drowned	O
in	O
a	O
pond	O
in	O
Walsenburg	O
,	O
Colorado	O
.	O
</s>
<s>
By	O
the	O
1980s	O
,	O
party	B-Architecture
lines	I-Architecture
were	O
removed	O
in	O
most	O
locales	O
.	O
</s>
<s>
They	O
were	O
not	O
supported	O
by	O
new	O
technologies	O
and	O
subscriber-owned	O
equipment	O
such	O
as	O
answering	O
machines	O
and	O
computer	B-Application
modems	I-Application
.	O
</s>
<s>
Party	B-Architecture
lines	I-Architecture
in	O
the	O
United	O
States	O
were	O
ineligible	O
for	O
Universal	O
Service	O
Fund	O
subsidies	O
,	O
leading	O
telephone	O
companies	O
to	O
convert	O
them	O
to	O
individual	O
lines	O
to	O
benefit	O
from	O
these	O
subsidies	O
.	O
</s>
<s>
In	O
1971	O
,	O
Southern	O
Bell	O
announced	O
plans	O
to	O
gradually	O
phase	O
out	O
all	O
party	B-Architecture
lines	I-Architecture
in	O
North	O
Carolina	O
.	O
</s>
<s>
One	O
of	O
the	O
last	O
manual	O
telephone	O
exchanges	O
with	O
party	B-Architecture
lines	I-Architecture
in	O
Australia	O
was	O
closed	O
down	O
in	O
1986	O
in	O
the	O
township	O
of	O
Collarenebri	O
,	O
where	O
most	O
town	O
residents	O
had	O
a	O
telephone	O
number	O
of	O
only	O
three	O
digits	O
.	O
</s>
<s>
In	O
1989	O
,	O
the	O
Chesapeake	O
and	O
Potomac	O
Telephone	O
Company	O
replaced	O
party	B-Architecture
lines	I-Architecture
with	O
individual	O
lines	O
in	O
Talcott	O
,	O
West	O
Virginia	O
,	O
a	O
rural	O
area	O
which	O
once	O
had	O
as	O
many	O
as	O
sixteen	O
subscribers	O
on	O
one	O
line	O
.	O
</s>
<s>
Illinois	O
State	O
University	O
terminated	O
its	O
last	O
party	B-Architecture
line	I-Architecture
in	O
1990	O
.	O
</s>
<s>
Woodbury	O
,	O
Connecticut	O
's	O
independent	O
telephone	O
company	O
abandoned	O
its	O
last	O
party	B-Architecture
lines	I-Architecture
in	O
1991	O
,	O
the	O
last	O
in	O
that	O
state	O
to	O
do	O
so	O
.	O
</s>
<s>
The	O
same	O
year	O
,	O
Southwestern	O
Bell	O
announced	O
its	O
intentions	O
to	O
replace	O
all	O
of	O
its	O
party	B-Architecture
lines	I-Architecture
in	O
Texas	O
with	O
individual	O
line	O
service	O
by	O
November	O
1994	O
,	O
and	O
the	O
company	O
's	O
last	O
party	B-Architecture
line	I-Architecture
finally	O
shut	O
down	O
in	O
1996	O
.	O
</s>
<s>
Pacific	O
Bell	O
phased	O
out	O
most	O
of	O
its	O
party	B-Architecture
lines	I-Architecture
by	O
1997	O
,	O
and	O
the	O
last	O
ones	O
operating	O
in	O
Nevada	O
shut	O
down	O
in	O
2001	O
.	O
</s>
<s>
As	O
of	O
2002	O
,	O
SBC	O
Ameritech	O
's	O
only	O
operating	O
party	B-Architecture
lines	I-Architecture
were	O
located	O
in	O
Michigan	O
.	O
</s>
<s>
USA	O
Today	O
reported	O
in	O
2000	O
that	O
over	O
5,000	O
party	B-Architecture
lines	I-Architecture
still	O
existed	O
in	O
the	O
United	O
States	O
,	O
but	O
the	O
majority	O
of	O
them	O
were	O
only	O
connected	O
to	O
one	O
telephone	O
,	O
and	O
therefore	O
appeared	O
like	O
individual	O
telephone	O
service	O
at	O
cheaper	O
rates	O
.	O
</s>
<s>
To	O
signal	O
specific	O
subscribers	O
on	O
party	B-Architecture
lines	I-Architecture
selectively	O
,	O
telephone	O
operating	O
companies	O
implemented	O
various	O
signaling	O
systems	O
.	O
</s>
<s>
For	O
though	O
one	O
was	O
only	O
to	O
answer	O
one	O
's	O
own	O
ringing	O
code	O
,	O
every	O
party	O
on	O
the	O
same	O
subscriber	B-Architecture
line	I-Architecture
could	O
hear	O
all	O
the	O
ringing	O
codes	O
.	O
</s>
<s>
On	O
the	O
same	O
subscriber	B-Architecture
line	I-Architecture
,	O
one	O
party	O
used	O
the	O
tip	O
side	O
of	O
the	O
line	O
and	O
ground	O
for	O
ringing	O
,	O
whilst	O
the	O
other	O
party	O
on	O
the	O
same	O
line	O
used	O
the	O
ring	O
wire	O
and	O
ground	O
for	O
ringing	O
,	O
to	O
achieve	O
full	O
selectivity	O
for	O
two-party	O
lines	O
,	O
in	O
which	O
only	O
the	O
selected	O
station	O
would	O
ring	O
.	O
</s>
<s>
Another	O
selective	O
ringing	O
system	O
was	O
based	O
on	O
using	O
different	O
ringing	O
frequencies	O
for	O
each	O
station	O
on	O
the	O
party	B-Architecture
line	I-Architecture
.	O
</s>
<s>
All	O
fully	O
selective	O
ringing	O
systems	O
on	O
party	B-Architecture
lines	I-Architecture
still	O
brought	O
the	O
inconvenience	O
of	O
finding	O
the	O
line	O
in	O
use	O
occasionally	O
,	O
by	O
hearing	O
talking	O
when	O
one	O
picked	O
up	O
the	O
phone	O
to	O
make	O
a	O
call	O
.	O
</s>
<s>
All	O
party	B-Architecture
lines	I-Architecture
also	O
required	O
special	O
equipment	O
to	O
complete	O
calls	O
to	O
another	O
party	O
on	O
the	O
same	O
party	B-Architecture
line	I-Architecture
.	O
</s>
<s>
In	O
the	O
local-battery	O
system	O
of	O
the	O
early	O
cranked	O
magneto	B-Algorithm
phones	O
,	O
the	O
phone	O
's	O
own	O
battery	O
powered	O
its	O
transmitter	O
as	O
well	O
as	O
the	O
receiver	O
of	O
the	O
called	O
phone	O
.	O
</s>
<s>
Systems	O
which	O
identify	O
the	O
caller	O
's	O
name	O
and	O
address	O
to	O
emergency	O
telephone	O
numbers	O
(	O
such	O
as	O
Enhanced	O
9-1-1	O
in	O
North	O
America	O
)	O
may	O
be	O
unable	O
to	O
identify	O
which	O
of	O
multiple	O
parties	O
on	O
a	O
shared	O
line	O
placed	O
a	O
distress	O
call	O
;	O
this	O
is	O
aggravated	O
by	O
the	O
use	O
of	O
old	O
mechanical	O
switching	O
equipment	O
for	O
party	B-Architecture
lines	I-Architecture
as	O
this	O
obsolete	O
apparatus	O
consistently	O
provides	O
no	O
caller	O
ID	O
and	O
often	O
also	O
lacks	O
automatic	O
number	O
identification	O
capability	O
.	O
</s>
<s>
When	O
the	O
party	B-Architecture
line	I-Architecture
was	O
already	O
in	O
use	O
,	O
if	O
any	O
of	O
the	O
other	O
subscribers	O
to	O
that	O
line	O
picked	O
up	O
the	O
phone	O
,	O
they	O
could	O
hear	O
and	O
participate	O
in	O
the	O
conversation	O
.	O
</s>
<s>
Party	B-Architecture
lines	I-Architecture
were	O
typically	O
operated	O
using	O
mechanical	O
switching	O
systems	O
which	O
recognized	O
certain	O
codes	O
for	O
revertive	O
calls	O
;	O
these	O
no	O
longer	O
work	O
on	O
modern	O
electronic	O
or	O
digital	O
switchgear	O
.	O
</s>
<s>
Party	B-Architecture
lines	I-Architecture
are	O
not	O
suitable	O
for	O
Internet	O
access	O
.	O
</s>
<s>
If	O
one	O
customer	O
is	O
using	O
dial-up	O
,	O
it	O
will	O
jam	O
the	O
line	O
for	O
all	O
other	O
customers	O
of	O
the	O
same	O
party	B-Architecture
line	I-Architecture
.	O
</s>
<s>
Bridge	B-Architecture
taps	I-Architecture
made	O
party	B-Architecture
lines	I-Architecture
unsuitable	O
for	O
DSL	O
,	O
even	O
in	O
the	O
few	O
areas	O
where	O
distance	O
from	O
the	O
central	O
office	O
did	O
not	O
already	O
preclude	O
its	O
use	O
.	O
</s>
<s>
Telephone	O
companies	O
typically	O
do	O
not	O
allow	O
client-owned	O
equipment	O
to	O
be	O
directly	O
connected	O
to	O
party	B-Architecture
lines	I-Architecture
,	O
posing	O
an	O
additional	O
obstacle	O
to	O
their	O
use	O
for	O
data	O
.	O
</s>
<s>
Telephone	O
service	O
for	O
dispatchers	O
and	O
service	O
personnel	O
between	O
way	O
stations	O
along	O
railways	O
used	O
a	O
form	O
of	O
party	B-Architecture
line	I-Architecture
service	I-Architecture
for	O
many	O
decades	O
starting	O
in	O
the	O
early	O
1900s	O
.	O
</s>
<s>
Various	O
pair	B-Protocol
gain	I-Protocol
methods	O
using	O
time-division	B-Protocol
multiplexing	I-Protocol
and	O
frequency-division	B-Protocol
multiplexing	I-Protocol
prevented	O
interference	O
between	O
simultaneous	O
calls	O
.	O
</s>
<s>
A	O
distant	O
suburb	O
may	O
have	O
a	O
subscriber	B-Application
loop	I-Application
carrier	I-Application
or	O
digital	B-Application
loop	I-Application
carrier	I-Application
system	O
in	O
which	O
a	O
remote	B-Architecture
concentrator	I-Architecture
is	O
located	O
near	O
the	O
subscribers	O
to	O
connect	O
multiple	O
local	O
subscriber	B-Architecture
loops	I-Architecture
to	O
one	O
common	O
line	O
to	O
a	O
central	O
office	O
exchange	O
.	O
</s>
<s>
A	O
single	O
optical	O
fibre	O
can	O
also	O
be	O
shared	O
between	O
multiple	O
subscribers	O
in	O
fibre	B-Architecture
to	I-Architecture
the	I-Architecture
cabinet	I-Architecture
systems	O
.	O
</s>
<s>
CATV	O
cable	B-Device
modems	I-Device
are	O
connected	O
to	O
an	O
inherently	O
shared	O
medium	O
.	O
</s>
<s>
Digital	O
wireless	O
connections	O
,	O
such	O
as	O
mobile	O
phones	O
or	O
voice	B-Application
over	I-Application
IP	I-Application
running	O
over	O
rural	O
wireless	O
Internet	O
infrastructure	O
are	O
also	O
inherently	O
a	O
shared	O
medium	O
.	O
</s>
<s>
Party	B-Architecture
lines	I-Architecture
are	O
still	O
in	O
use	O
primarily	O
in	O
rural	O
areas	O
where	O
local	B-Architecture
loops	I-Architecture
are	O
long	O
and	O
individual	O
circuits	O
are	O
uneconomical	O
when	O
spread	O
sparsely	O
over	O
a	O
large	O
area	O
.	O
</s>
<s>
In	O
isolated	O
communities	O
,	O
party	B-Architecture
lines	I-Architecture
have	O
been	O
used	O
for	O
local	O
service	O
only	O
,	O
without	O
the	O
facilities	O
to	O
switch	O
calls	O
through	O
a	O
central	O
office	O
for	O
connection	O
to	O
the	O
public	O
switched	O
telephone	O
network	O
.	O
</s>
<s>
An	O
example	O
of	O
a	O
community	O
linked	O
by	O
a	O
party	B-Architecture
line	I-Architecture
is	O
in	O
Big	O
Santa	O
Anita	O
Canyon	O
high	O
in	O
the	O
mountains	O
above	O
Los	O
Angeles	O
,	O
near	O
Sierra	O
Madre	O
,	O
California	O
.	O
</s>
<s>
A	O
group	O
camp	O
,	O
a	O
pack	O
station	O
and	O
81	O
cabins	O
all	O
communicate	O
by	O
magneto-type	O
crank	O
phones	O
.	O
</s>
<s>
In	O
modern	O
use	O
,	O
the	O
term	O
party	B-Architecture
line	I-Architecture
has	O
occasionally	O
been	O
used	O
to	O
market	O
conference	O
calling	O
and	O
voice	O
bulletin	O
board	O
services	O
.	O
</s>
