<s>
Live	B-Protocol
Communications	I-Protocol
Server	I-Protocol
2005	I-Protocol
(	O
LCS	O
2005	O
)	O
,	O
codenamed	O
Vienna	O
,	O
is	O
the	O
second	O
version	O
of	O
a	O
SIP	B-Application
based	O
instant	B-Application
messaging	I-Application
and	O
presence	B-Protocol
server	O
after	O
Live	B-Protocol
Communications	I-Protocol
Server	I-Protocol
2003	I-Protocol
.	O
</s>
<s>
LCS	O
2005	O
has	O
been	O
superseded	O
by	O
Microsoft	B-Protocol
Office	I-Protocol
Communications	I-Protocol
Server	I-Protocol
2007	I-Protocol
.	O
</s>
<s>
This	O
product	O
allows	O
SIP	B-Application
clients	O
to	O
exchange	O
IMs	B-Application
and	O
presence	B-Protocol
using	O
the	O
SIMPLE	O
protocol	O
.	O
</s>
<s>
The	O
Standard	O
Edition	O
uses	O
a	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
Desktop	O
Engine	O
(	O
MSDE	B-Application
)	O
(	O
included	O
with	O
the	O
product	O
)	O
to	O
store	O
configuration	O
and	O
user	O
data	O
.	O
</s>
<s>
Enterprise	O
Edition	O
uses	O
a	O
full	O
version	O
of	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
(	O
purchased	O
separately	O
)	O
.	O
</s>
<s>
New	O
features	O
to	O
this	O
version	O
compared	O
to	O
the	O
2003	O
release	O
is	O
the	O
ability	O
to	O
leverage	O
SQL	B-Language
and	O
remote	O
user	O
access	O
.	O
</s>
<s>
Presence	B-Protocol
is	O
conveyed	O
as	O
levels	O
of	O
availability	O
to	O
communicate	O
.	O
</s>
<s>
Levels	O
of	O
presence	B-Protocol
support	O
by	O
LCS	O
:	O
</s>
<s>
These	O
presence	B-Protocol
levels	O
are	O
controlled	O
manually	O
and	O
automatically	O
.	O
</s>
<s>
Automatic	O
presence	B-Protocol
changes	O
can	O
be	O
triggered	O
by	O
the	O
following	O
events	O
:	O
</s>
<s>
The	O
user	O
's	O
data	O
is	O
stored	O
in	O
an	O
SQL	B-Language
database	I-Language
on	O
the	O
backend	O
server	O
(	O
on	O
Enterprise	O
Edition	O
)	O
or	O
on	O
the	O
Home	O
Server	O
(	O
on	O
Standard	O
Edition	O
)	O
.	O
</s>
<s>
The	O
contact	O
list	O
is	O
the	O
list	O
of	O
users	O
the	O
end	O
user	O
has	O
added	O
to	O
client	O
software	O
in	O
order	O
to	O
facilitate	O
the	O
sending	O
of	O
IM	B-Application
's	O
and	O
for	O
the	O
monitoring	O
the	O
presence	B-Protocol
.	O
</s>
<s>
This	O
server	O
role	O
is	O
required	O
to	O
allow	O
remote	O
SIP	B-Application
clients	O
to	O
connect	O
from	O
the	O
internet	O
.	O
</s>
<s>
This	O
server	O
role	O
would	O
be	O
traditionally	O
deployed	O
in	O
a	O
DMZ	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
server	O
's	O
job	O
would	O
be	O
to	O
scan	O
the	O
SIP	B-Application
traffic	O
and	O
only	O
allow	O
communication	O
that	O
the	O
server	O
had	O
been	O
configured	O
to	O
allow	O
to	O
traverse	O
to	O
the	O
internal	O
network	O
.	O
</s>
<s>
This	O
role	O
is	O
used	O
to	O
aggregate	O
connections	O
,	O
from	O
a	O
branch	O
office	O
clients	O
,	O
across	O
a	O
single	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
(	O
TLS	B-Protocol
)	O
encrypted	O
link	O
,	O
allowing	O
many	O
remote	O
clients	O
to	O
share	O
a	O
single	O
communication	O
channel	O
.	O
</s>
<s>
This	O
server	O
role	O
is	O
designed	O
to	O
allow	O
3rd	O
party	O
developers	O
to	O
leverage	O
the	O
Live	B-Protocol
Communications	I-Protocol
Server	I-Protocol
SIP	B-Application
stack	O
with	O
a	O
custom	O
code	O
running	O
on	O
top	O
of	O
it	O
.	O
</s>
<s>
This	O
allows	O
3rd	O
parties	O
to	O
make	O
a	O
gateway	O
server	O
that	O
could	O
be	O
used	O
to	O
communicate	O
with	O
a	O
PBX	B-Device
or	O
other	O
internal	O
telephony	O
infrastructure	O
without	O
having	O
to	O
create	O
a	O
fully	O
functioning	O
SIP	B-Application
stack	O
.	O
</s>
<s>
This	O
is	O
a	O
feature	O
that	O
allows	O
organizations	O
to	O
IM	B-Application
and	O
share	O
presence	B-Protocol
information	I-Protocol
between	O
their	O
existing	O
base	O
of	O
Live	O
Communications	O
Server-enabled	O
users	O
and	O
contacts	O
using	O
public	O
IM	B-Application
services	O
provided	O
by	O
MSN	O
,	O
AOL	O
and	O
Yahoo	O
!	O
.	O
</s>
