<s>
A	O
telephone	B-Device
switchboard	I-Device
was	O
a	O
device	O
used	O
to	O
connect	O
circuits	O
of	O
telephones	O
to	O
establish	O
telephone	O
calls	O
between	O
users	O
or	O
other	O
switchboards	O
,	O
throughout	O
the	O
20th	O
century	O
.	O
</s>
<s>
A	O
private	B-Device
branch	I-Device
exchange	I-Device
(	O
PBX	O
)	O
in	O
a	O
business	O
usually	O
has	O
an	O
attendant	O
console	O
,	O
or	O
an	O
auto-attendant	O
function	O
,	O
which	O
bypasses	O
the	O
operator	O
.	O
</s>
<s>
Cord	O
switchboards	O
were	O
often	O
referred	O
to	O
as	O
"	O
cordboards	B-Device
"	O
by	O
telephone	O
company	O
personnel	O
.	O
</s>
<s>
With	O
this	O
the	O
BOCs	O
took	O
intraLATA	O
call	O
traffic	O
from	O
AT&T	O
as	O
well	O
as	O
services	O
which	O
were	O
once	O
provided	O
on	O
a	O
cordboard	B-Device
(	O
Toll	O
Stations	O
,	O
Mobile	O
and	O
Marine	O
 [ Ship-to-Shore ] 	O
)	O
.	O
</s>
<s>
A	O
key	O
in	O
the	O
forward	O
position	O
(	O
front	O
key	O
)	O
connects	O
the	O
operator	O
to	O
the	O
cord	O
pair	O
,	O
and	O
a	O
key	O
in	O
the	O
back	O
position	O
sends	O
a	O
ring	O
signal	O
out	O
on	O
the	O
cord	O
(	O
on	O
older	O
manual	B-Device
exchanges	I-Device
)	O
.	O
</s>
<s>
Each	O
cord	O
has	O
a	O
three-wire	O
TRS	B-Device
phone	I-Device
connector	I-Device
:	O
tip	O
and	O
ring	O
for	O
testing	O
,	O
ringing	O
and	O
voice	O
;	O
and	O
a	O
sleeve	O
wire	O
for	O
busy	O
signals	O
.	O
</s>
