<s>
The	O
term	O
presentity	B-Protocol
is	O
a	O
combination	O
of	O
two	O
words	O
-	O
"	O
presence	O
"	O
and	O
"	O
entity	O
"	O
.	O
</s>
<s>
It	O
basically	O
refers	O
to	O
an	O
entity	O
that	O
has	O
presence	B-Protocol
information	I-Protocol
associated	O
with	O
it	O
;	O
information	O
such	O
as	O
status	O
,	O
reachability	O
,	O
and	O
willingness	O
to	O
communicate	O
.	O
</s>
<s>
The	O
term	O
presentity	B-Protocol
is	O
often	O
used	O
to	O
refer	O
to	O
users	O
who	O
post	O
and	O
update	O
their	O
presence	B-Protocol
information	I-Protocol
through	O
some	O
kind	O
of	O
presence	O
applications	O
on	O
their	O
devices	O
.	O
</s>
<s>
In	O
this	O
case	O
presence	B-Protocol
information	I-Protocol
describes	O
availability	O
and	O
willingness	O
of	O
this	O
user	O
to	O
communicate	O
via	O
set	O
of	O
communication	O
services	O
.	O
</s>
<s>
For	O
example	O
,	O
users	O
of	O
an	O
instant	O
messaging	O
service	O
(	O
such	O
as	O
ICQ	O
or	O
MSN	O
Messenger	O
)	O
are	O
presentities	B-Protocol
and	O
their	O
presence	B-Protocol
information	I-Protocol
is	O
their	O
user	O
status	O
(	O
online	O
,	O
offline	O
,	O
away	O
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
Presentity	B-Protocol
can	O
also	O
refer	O
to	O
a	O
resource	O
or	O
role	O
such	O
as	O
a	O
conference	O
room	O
or	O
help	O
desk	O
.	O
</s>
<s>
A	O
presentity	B-Protocol
can	O
also	O
refer	O
to	O
a	O
group	O
of	O
users	O
,	O
for	O
example	O
a	O
collection	O
of	O
customer	O
service	O
agents	O
in	O
a	O
call	O
center	O
.	O
</s>
<s>
This	O
presentity	B-Protocol
may	O
be	O
considered	O
available	O
if	O
there	O
is	O
at	O
least	O
one	O
agent	O
ready	O
to	O
accept	O
a	O
call	O
.	O
</s>
