<s>
A	O
subscriber	B-Application
loop	I-Application
carrier	I-Application
or	O
subscriber	B-Application
line	I-Application
carrier	I-Application
(	O
SLC	O
)	O
provides	O
telephone	O
exchange-like	O
telephone	O
interface	O
functionality	O
.	O
</s>
<s>
Two	O
or	O
four	O
T1	B-Protocol
circuits	I-Protocol
(	O
depending	O
on	O
the	O
configuration	O
)	O
connect	O
the	O
SLC	O
remote	O
terminal	O
to	O
the	O
central	O
office	O
terminal	O
(	O
COT	O
)	O
,	O
in	O
the	O
case	O
of	O
a	O
universal	O
subscriber	B-Application
loop	I-Application
carrier	I-Application
(	O
USLC	O
)	O
.	O
</s>
<s>
An	O
integrated	O
subscriber	B-Application
loop	I-Application
carrier	I-Application
(	O
ISLC	O
)	O
has	O
its	O
T-spans	B-Protocol
terminating	O
directly	O
in	O
time	O
division	O
switching	O
equipment	O
in	O
the	O
telephone	O
exchange	O
.	O
</s>
<s>
These	O
systems	O
are	O
generally	O
installed	O
in	O
cabinets	O
that	O
have	O
some	O
form	O
of	O
uninterruptible	O
power	O
supply	O
or	O
other	O
backup	O
battery	O
arrangements	O
,	O
standby	O
generators	O
,	O
and	O
sometimes	O
with	O
additional	O
equipment	O
such	O
as	O
remote	O
DSLAMs	B-Protocol
.	O
</s>
<s>
SLCs	O
have	O
been	O
criticized	O
for	O
reducing	O
the	O
reliability	O
of	O
local	B-Architecture
loops	I-Architecture
due	O
to	O
their	O
increased	O
reliance	O
on	O
utility	O
power	O
.	O
</s>
