<s>
In	O
telecommunications	O
,	O
a	O
network	B-Protocol
interface	I-Protocol
device	I-Protocol
(	O
NID	O
;	O
also	O
known	O
by	O
several	O
other	O
names	O
)	O
is	O
a	O
device	O
that	O
serves	O
as	O
the	O
demarcation	B-Architecture
point	I-Architecture
between	O
the	O
carrier	O
's	O
local	B-Architecture
loop	I-Architecture
and	O
the	O
customer	O
's	O
premises	B-Protocol
wiring	I-Protocol
.	O
</s>
<s>
Outdoor	O
telephone	O
NIDs	O
also	O
provide	O
the	O
subscriber	O
with	O
access	O
to	O
the	O
station	O
wiring	O
and	O
serve	O
as	O
a	O
convenient	O
test	O
point	O
for	O
verification	O
of	O
loop	O
integrity	O
and	O
of	O
the	O
subscriber	O
's	O
inside	B-Protocol
wiring	I-Protocol
.	O
</s>
<s>
Generically	O
,	O
an	O
NID	O
may	O
also	O
be	O
called	O
a	O
network	B-Protocol
interface	I-Protocol
unit	I-Protocol
(	O
NIU	O
)	O
,	O
telephone	B-Protocol
network	I-Protocol
interface	I-Protocol
(	O
TNI	O
)	O
,	O
system	B-Protocol
network	I-Protocol
interface	I-Protocol
(	O
SNI	O
)	O
,	O
or	O
telephone	B-Protocol
network	I-Protocol
box	I-Protocol
.	O
</s>
<s>
Australia	O
's	O
National	O
Broadband	O
Network	O
uses	O
the	O
term	O
network	B-Device
termination	I-Device
device	I-Device
or	O
NTD	B-Device
.	O
</s>
<s>
An	O
optical	O
network	O
terminal	O
(	O
ONT	O
)	O
is	O
a	O
type	O
of	O
NID	O
used	O
with	O
fiber-to-the-premises	B-Architecture
applications	O
.	O
</s>
<s>
In	O
its	O
role	O
as	O
the	O
demarcation	B-Architecture
point	I-Architecture
(	O
dividing	O
line	O
)	O
,	O
the	O
NID	O
separates	O
the	O
telephone	O
company	O
's	O
equipment	O
from	O
the	O
customer	O
's	O
wiring	O
and	O
equipment	O
.	O
</s>
<s>
Accessing	O
the	O
test	O
jack	O
disconnects	O
the	O
customer	B-Protocol
premises	I-Protocol
wiring	I-Protocol
from	O
the	O
public	O
switched	O
telephone	O
network	O
and	O
allows	O
the	O
customer	O
to	O
plug	O
a	O
"	O
known	O
good	O
"	O
telephone	O
into	O
the	O
jack	O
to	O
isolate	O
trouble	O
.	O
</s>
<s>
They	O
protect	O
customer	O
wiring	O
,	O
equipment	O
,	O
and	O
personnel	O
from	O
any	O
transient	O
energy	O
on	O
the	O
line	O
,	O
such	O
as	O
from	O
a	O
lightning	B-Architecture
strike	O
to	O
a	O
telephone	O
pole	O
.	O
</s>
<s>
Such	O
NIDs	O
are	O
colloquially	O
called	O
smartjacks	O
or	O
Intelligent	O
Network	B-Protocol
Interface	I-Protocol
Devices	I-Protocol
(	O
INIDs	O
)	O
as	O
an	O
indication	O
of	O
their	O
built-in	O
"	O
intelligence	O
"	O
,	O
as	O
opposed	O
to	O
a	O
simple	O
NID	O
,	O
which	O
is	O
just	O
a	O
wiring	O
device	O
.	O
</s>
<s>
Smartjacks	O
are	O
typically	O
used	O
for	O
more	O
complicated	O
types	O
of	O
telecommunications	O
service	O
,	O
such	O
as	O
T1	B-Protocol
lines	I-Protocol
.	O
</s>
<s>
Despite	O
the	O
name	O
,	O
most	O
smartjacks	O
are	O
much	O
more	O
than	O
a	O
simple	O
telephone	B-Protocol
jack	I-Protocol
.	O
</s>
<s>
A	O
very	O
common	O
capability	O
provided	O
by	O
a	O
smartjack	O
is	O
loopback	B-Protocol
,	O
such	O
that	O
the	O
signal	O
from	O
the	O
telephone	O
company	O
is	O
transmitted	O
back	O
to	O
the	O
telephone	O
company	O
.	O
</s>
<s>
The	O
telephone	O
company	O
usually	O
has	O
the	O
ability	O
to	O
remotely	O
activate	O
loopback	B-Protocol
,	O
without	O
even	O
needing	O
personnel	O
at	O
the	O
customer	O
site	O
.	O
</s>
<s>
Additional	O
smartjack	O
diagnostic	O
capabilities	O
include	O
alarm	B-Protocol
indication	I-Protocol
signal	I-Protocol
,	O
which	O
reports	O
trouble	O
at	O
one	O
end	O
of	O
the	O
line	O
to	O
the	O
far	O
end	O
.	O
</s>
<s>
In	O
fiber-to-the-premises	B-Architecture
systems	O
,	O
the	O
signal	O
is	O
transmitted	O
to	O
the	O
customer	O
premises	O
using	O
fiber	B-Architecture
optic	I-Architecture
technologies	I-Architecture
.	O
</s>
<s>
An	O
optical	O
network	O
terminal	O
(	O
ONT	O
)	O
is	O
used	O
to	O
terminate	O
the	O
fiber	B-Architecture
optic	I-Architecture
line	O
,	O
demultiplex	B-Architecture
the	O
signal	O
into	O
its	O
component	O
parts	O
(	O
voice	O
telephone	O
,	O
television	O
,	O
and	O
Internet	O
access	O
)	O
,	O
and	O
provide	O
power	O
to	O
customer	O
telephones	O
.	O
</s>
<s>
These	O
terminals	O
are	O
used	O
in	O
both	O
active	O
optical	O
networks	O
and	O
passive	B-Architecture
optical	I-Architecture
networks	I-Architecture
.	O
</s>
<s>
Severe	O
climatic	O
conditions	O
:	O
These	O
cover	O
environments	O
more	O
severe	O
than	O
those	O
of	O
a	O
normal	O
environment	O
(	O
i.e.	O
,	O
higher	O
humidity	O
,	O
high	O
lightning	B-Architecture
activity	O
,	O
exposure	O
to	O
salt-laden	O
atmosphere	O
,	O
and	O
exposure	O
to	O
contaminants	O
)	O
.	O
</s>
