<s>
Central	B-Device
office	I-Device
multiplexing	I-Device
(	O
or	O
CO	O
muxing	B-Architecture
)	O
is	O
telephone	O
exchange	O
(	O
central	O
office	O
)	O
equipment	O
that	O
derives	O
a	O
number	O
of	O
lower-speed	O
channels	O
from	O
one	O
high-bandwidth	O
channel	O
.	O
</s>
<s>
This	O
type	O
of	O
multiplexing	B-Architecture
is	O
needed	O
when	O
the	O
customer	O
wants	O
to	O
terminate	O
the	O
DS1	B-Protocol
or	O
DS3	O
in	O
the	O
central	O
office	O
and	O
wants	O
to	O
‘	O
pick	O
up’	O
lower	O
level	O
services	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
customer	O
may	O
order	O
a	O
DS3	O
,	O
using	O
it	O
to	O
carry	O
a	O
number	O
of	O
DS1	B-Protocol
level	O
services	O
from	O
different	O
IXC	O
carriers	O
.	O
</s>
