<s>
A	O
punch-down	B-Protocol
block	I-Protocol
(	O
also	O
punchdown	B-Protocol
block	I-Protocol
,	O
punch	B-Protocol
block	I-Protocol
,	O
punchblock	O
,	O
quick-connect	B-Protocol
block	I-Protocol
and	O
other	O
variations	O
)	O
is	O
a	O
type	O
of	O
electrical	O
connection	O
often	O
used	O
in	O
telephony	O
.	O
</s>
<s>
It	O
is	O
named	O
because	O
the	O
solid	O
copper	O
wires	O
are	O
"	O
punched	O
down	O
"	O
into	O
short	O
open-ended	O
slots	O
which	O
are	O
a	O
type	O
of	O
insulation-displacement	B-Protocol
connector	I-Protocol
.	O
</s>
<s>
A	O
tool	O
called	O
a	O
punch	B-Protocol
down	I-Protocol
tool	I-Protocol
is	O
used	O
to	O
push	O
the	O
wire	O
down	O
firmly	O
and	O
properly	O
into	O
the	O
slot	O
.	O
</s>
<s>
Punch-down	B-Protocol
blocks	I-Protocol
are	O
a	O
very	O
quick	O
and	O
easy	O
way	O
to	O
connect	O
wiring	B-Device
,	O
as	O
there	O
is	O
no	O
stripping	O
of	O
insulation	O
and	O
no	O
screws	O
to	O
loosen	O
and	O
tighten	O
.	O
</s>
<s>
Punch-down	B-Protocol
blocks	I-Protocol
are	O
often	O
used	O
as	O
patch	B-Protocol
panels	I-Protocol
,	O
or	O
as	O
breakout	B-Protocol
boxes	I-Protocol
for	O
PBX	B-Device
or	O
other	O
similar	O
multi-line	O
telephone	O
systems	O
with	O
50-pin	O
RJ21	O
(	O
Amphenol	O
)	O
connectors	O
.	O
</s>
<s>
They	O
are	O
sometimes	O
used	O
in	O
other	O
audio	O
applications	O
,	O
such	O
as	O
in	O
reconfigurable	O
patch	B-Protocol
panels	I-Protocol
.	O
</s>
<s>
Often	O
a	O
separate	O
tool	O
known	O
as	O
a	O
spudger	O
is	O
used	O
to	O
remove	O
small	O
stray	O
pieces	O
of	O
cut	O
off	O
wiring	B-Device
stuck	O
within	O
punch-down	B-Protocol
blocks	I-Protocol
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
insert	O
wiring	B-Device
without	O
the	O
proper	O
tool	O
,	O
but	O
this	O
requires	O
great	O
care	O
to	O
avoid	O
damaging	O
the	O
connectors	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
punch	B-Protocol
down	I-Protocol
multiple	O
wires	O
on	O
top	O
of	O
each	O
other	O
in	O
a	O
single	O
post	O
of	O
a	O
punch-down	B-Protocol
block	I-Protocol
,	O
but	O
this	O
practice	O
is	O
discouraged	O
because	O
of	O
reliability	O
concerns	O
.	O
</s>
<s>
Similarly	O
,	O
stranded	O
wire	O
can	O
be	O
used	O
on	O
punch-down	B-Protocol
blocks	I-Protocol
,	O
but	O
they	O
are	O
designed	O
for	O
solid	O
wire	O
connections	O
.	O
</s>
<s>
Once	O
the	O
contact	O
blades	O
in	O
a	O
punchdown	B-Protocol
block	I-Protocol
are	O
"	O
sprung	O
apart	O
"	O
by	O
poor	O
practices	O
,	O
the	O
entire	O
block	O
often	O
must	O
be	O
replaced	O
to	O
restore	O
reliable	O
connections	O
.	O
</s>
<s>
In	O
addition	O
,	O
punch-down	B-Protocol
blocks	I-Protocol
are	O
being	O
used	O
to	O
handle	O
larger	O
numbers	O
of	O
faster	O
data	O
signals	O
,	O
requiring	O
greater	O
care	O
and	O
proper	O
procedures	O
to	O
control	O
impedance	O
and	O
crosstalk	O
.	O
</s>
<s>
A	O
66	B-Architecture
block	I-Architecture
(	O
or	O
"	O
M	O
Block	O
"	O
)	O
is	O
used	O
in	O
older	O
analog	O
telephone	O
systems	O
.	O
</s>
<s>
A	O
110	B-Device
block	I-Device
is	O
often	O
used	O
in	O
residential	O
telephone	O
and	O
Cat	B-Protocol
5	I-Protocol
wire	O
systems	O
,	O
replacing	O
66	B-Architecture
blocks	I-Architecture
.	O
</s>
<s>
A	O
Krone	B-Protocol
block	I-Protocol
is	O
a	O
proprietary	O
European	O
alternative	O
.	O
</s>
<s>
A	O
BIX	B-Protocol
block	O
is	O
a	O
proprietary	O
block	O
developed	O
originally	O
by	O
Nortel	O
Networks	O
.	O
</s>
