<s>
In	O
telecommunication	O
,	O
a	O
customer	B-Architecture
service	I-Architecture
unit	I-Architecture
(	O
CSU	O
)	O
is	O
a	O
device	O
that	O
provides	O
an	O
accessing	O
arrangement	O
at	O
a	O
user	O
location	O
to	O
either	O
switched	O
or	O
point-to-point	B-Architecture
,	O
data-conditioned	B-General_Concept
circuits	O
at	O
a	O
specifically	O
established	O
data	O
signaling	O
rate	O
.	O
</s>
<s>
A	O
CSU	O
provides	O
local	O
loop	O
equalization	B-Algorithm
,	O
transient	O
protection	O
,	O
isolation	O
,	O
and	O
central	O
office	O
loop-back	B-Protocol
testing	O
capability	O
.	O
</s>
