<s>
The	O
Nokia	B-Language
N81	I-Language
is	O
a	O
Symbian	B-Operating_System
OS	I-Operating_System
smartphone	B-Application
announced	O
by	O
Nokia	O
on	O
29	O
August	O
2007	O
and	O
released	O
the	O
next	O
month	O
.	O
</s>
<s>
It	O
runs	O
S60	B-Language
3rd	O
Edition	O
,	O
Feature	O
Pack	O
1	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
device	O
that	O
came	O
preloaded	O
with	O
the	O
N-Gage	B-Operating_System
2.0	I-Operating_System
gaming	O
service	O
in	O
2008	O
(	O
albeit	O
in	O
public	O
beta	O
)	O
,	O
and	O
it	O
features	O
two	O
dedicated	O
gaming	O
keys	O
that	O
can	O
be	O
used	O
for	O
N-Gage	B-Operating_System
games	O
(	O
this	O
would	O
later	O
also	O
appear	O
on	O
the	O
N96	B-Language
,	O
N85	O
and	O
5730	O
XpressMusic	O
)	O
.	O
</s>
<s>
During	O
the	O
launch	O
of	O
N-Gage	B-Operating_System
2.0	I-Operating_System
,	O
the	O
N81	O
was	O
specifically	O
chosen	O
by	O
Nokia	O
in	O
advertisements	O
.	O
</s>
<s>
It	O
was	O
also	O
much	O
marketed	O
as	O
a	O
music-centric	O
smartphone	B-Application
and	O
was	O
one	O
of	O
the	O
first	O
to	O
support	O
the	O
Nokia	B-Language
Music	I-Language
Store	I-Language
service	O
.	O
</s>
<s>
Several	O
reviewers	O
have	O
claimed	O
that	O
the	O
N81	O
has	O
,	O
much	O
like	O
the	O
older	O
Nokia	B-Operating_System
N91	I-Operating_System
,	O
a	O
very	O
high	O
sound	O
output	O
quality	O
and	O
therefore	O
highly	O
suitable	O
for	O
audiophiles	O
.	O
</s>
<s>
The	O
four-way	O
silver-coloured	O
D-pad	B-Device
below	O
the	O
display	O
also	O
contains	O
a	O
new	O
capacitive	O
sensor	O
called	O
the	O
Navi	O
wheel	O
,	O
which	O
allows	O
scrolling	O
in	O
the	O
S60	B-Language
gallery	O
and	O
music	O
player	O
applications	O
by	O
'	O
stroking	O
 '	O
the	O
key	O
,	O
in	O
a	O
similar	O
manner	O
to	O
the	O
iPod	B-Device
click	I-Device
wheel	I-Device
.	O
</s>
<s>
The	O
Navi	O
wheel	O
would	O
later	O
also	O
appear	O
on	O
other	O
Nokia	B-Language
Nseries	I-Language
handsets	O
:	O
N78	B-Language
,	O
N85	O
and	O
N96	B-Language
.	O
</s>
<s>
Other	O
than	O
these	O
the	O
N81	O
has	O
more	O
modest	O
specifications	O
compared	O
to	O
the	O
Nokia	B-Language
N95	I-Language
,	O
with	O
a	O
2-megapixel	O
camera	O
,	O
lacking	O
both	O
GPS	O
and	O
HSDPA	O
,	O
and	O
weighing	O
20	O
grams	O
heavier	O
.	O
</s>
<s>
The	O
Nokia	B-Language
N81	I-Language
notably	O
features	O
a	O
sliding	O
spring-loaded	O
physical	O
keylock	O
on	O
the	O
top	O
of	O
the	O
device	O
,	O
located	O
next	O
to	O
the	O
3.5mm	O
jack	O
.	O
</s>
<s>
It	O
is	O
the	O
first	O
Nseries	B-Language
device	O
that	O
swapped	O
the	O
miniUSB	O
port	O
in	O
favour	O
of	O
microUSB	O
.	O
</s>
<s>
The	O
Nokia	B-Language
N81	I-Language
had	O
a	O
lower	O
sound	O
output	O
compared	O
to	O
the	O
N91	O
due	O
to	O
the	O
release	O
of	O
the	O
new	O
firmware	O
version	O
.	O
</s>
