<s>
Headsets	B-Device
connect	O
over	O
a	O
telephone	O
or	O
to	O
a	O
computer	O
,	O
allowing	O
the	O
user	O
to	O
speak	O
and	O
listen	O
while	O
keeping	O
both	O
hands	O
free	O
.	O
</s>
<s>
They	O
are	O
commonly	O
used	O
in	O
customer	O
service	O
and	O
technical	O
support	O
centers	O
,	O
where	O
employees	O
can	O
converse	O
with	O
customers	O
while	O
typing	B-Application
information	O
into	O
a	O
computer	O
.	O
</s>
<s>
Also	O
common	O
among	O
computer	O
gamers	O
are	O
headsets	B-Device
,	O
which	O
will	O
let	O
them	O
talk	O
with	O
each	O
other	O
and	O
hear	O
others	O
,	O
as	O
well	O
as	O
use	O
their	O
keyboards	B-Device
and	O
mice	B-Device
to	O
play	O
the	O
game	O
.	O
</s>
<s>
Telephone	O
headsets	B-Device
generally	O
use	O
loudspeakers	O
with	O
a	O
narrower	O
frequency	O
range	O
than	O
those	O
also	O
used	O
for	O
entertainment	O
.	O
</s>
<s>
Stereo	O
computer	O
headsets	B-Device
,	O
on	O
the	O
other	O
hand	O
,	O
use	O
32-ohm	O
speakers	O
with	O
a	O
broader	O
frequency	O
range	O
.	O
</s>
<s>
Headsets	B-Device
are	O
available	O
in	O
single-earpiece	O
and	O
double-earpiece	O
designs	O
.	O
</s>
<s>
Double-earpiece	O
headsets	B-Device
may	O
support	O
stereo	O
sound	O
or	O
use	O
the	O
same	O
monaural	O
audio	O
channel	O
for	O
both	O
ears	O
.	O
</s>
<s>
Single-earpiece	O
headsets	B-Device
free	O
up	O
one	O
ear	O
,	O
allowing	O
better	O
awareness	O
of	O
surroundings	O
.	O
</s>
<s>
Telephone	O
headsets	B-Device
are	O
monaural	O
,	O
even	O
for	O
double-earpiece	O
designs	O
,	O
because	O
telephone	O
offers	O
only	O
single-channel	O
input	O
and	O
output	O
.	O
</s>
<s>
The	O
microphone	O
arm	O
of	O
headsets	B-Device
may	O
carry	O
an	O
external	O
microphone	O
or	O
be	O
of	O
the	O
voice	O
tube	O
type	O
.	O
</s>
<s>
Most	O
external	O
microphone	O
designs	O
are	O
of	O
either	O
omnidirectional	O
or	O
noise-canceling	B-Algorithm
type	O
.	O
</s>
<s>
Noise-canceling	B-Algorithm
microphone	I-Algorithm
headsets	B-Device
use	O
a	O
bi-directional	O
microphone	O
as	O
elements	O
.	O
</s>
<s>
Standard	O
headsets	B-Device
with	O
a	O
headband	O
worn	O
over	O
the	O
head	O
are	O
known	O
as	O
over-the-head	O
headsets	B-Device
.	O
</s>
<s>
Headsets	B-Device
with	O
headbands	O
going	O
over	O
the	O
back	O
of	O
the	O
user	O
's	O
neck	O
are	O
known	O
as	O
backwear-headsets	O
or	O
behind-the-neck	O
headsets	B-Device
.	O
</s>
<s>
Headsets	B-Device
worn	O
over	O
the	O
ear	O
with	O
a	O
soft	O
ear-hook	O
are	O
known	O
as	O
over-the-ear	O
headsets	B-Device
or	O
earloop	O
headsets	B-Device
.	O
</s>
<s>
Convertible	O
headsets	B-Device
are	O
designed	O
so	O
that	O
users	O
can	O
change	O
the	O
wearing	O
method	O
by	O
re-assembling	O
various	O
parts	O
.	O
</s>
<s>
There	O
are	O
also	O
under-the-chin	O
headsets	B-Device
similar	O
to	O
the	O
headphones	O
that	O
stenographers	O
wear	O
.	O
</s>
<s>
Headsets	B-Device
earpieces	O
may	O
be	O
for	O
either	O
one	O
or	O
both	O
ears	O
.	O
</s>
<s>
Telephone	O
headsets	B-Device
connect	O
to	O
a	O
fixed-line	B-Application
telephone	I-Application
system	O
.	O
</s>
<s>
A	O
telephone	O
headset	B-Device
functions	O
by	O
replacing	O
the	O
handset	O
of	O
a	O
telephone	O
.	O
</s>
<s>
Headsets	B-Device
for	O
standard	O
corded	O
telephones	O
are	O
fitted	O
with	O
a	O
standard	O
4P4C	O
commonly	O
called	O
an	O
RJ-9	O
connector	O
.	O
</s>
<s>
Headsets	B-Device
are	O
also	O
available	O
with	O
2.5mm	O
jack	O
sockets	O
for	O
many	O
DECT	B-Protocol
phones	O
and	O
other	O
applications	O
.	O
</s>
<s>
Cordless	O
bluetooth	B-Protocol
headsets	B-Device
are	O
available	O
and	O
often	O
used	O
with	O
mobile	O
telephones	O
.	O
</s>
<s>
Headsets	B-Device
are	O
widely	O
used	O
for	O
telephone-intensive	O
jobs	O
,	O
in	O
particular	O
by	O
call	O
centre	O
workers	O
.	O
</s>
<s>
Not	O
all	O
telephone	O
headsets	B-Device
are	O
compatible	O
with	O
all	O
telephone	O
models	O
.	O
</s>
<s>
Because	O
headsets	B-Device
connect	O
to	O
the	O
telephone	O
via	O
the	O
standard	O
handset	O
jack	O
,	O
the	O
pin-alignment	O
of	O
the	O
telephone	O
handset	O
may	O
be	O
different	O
from	O
the	O
default	O
pin-alignment	O
of	O
the	O
telephone	O
headset	B-Device
.	O
</s>
<s>
To	O
ensure	O
a	O
headset	B-Device
can	O
properly	O
pair	O
with	O
a	O
telephone	O
,	O
telephone	O
adapters	O
or	O
pin-alignment	O
adapters	O
are	O
available	O
.	O
</s>
<s>
Some	O
of	O
these	O
adapters	O
also	O
provide	O
mute	O
function	O
and	O
switching	O
between	O
handset	O
and	O
headset	B-Device
.	O
</s>
<s>
For	O
older	O
models	O
of	O
telephones	O
,	O
the	O
headset	B-Device
microphone	O
impedance	O
is	O
different	O
from	O
that	O
of	O
the	O
original	O
handset	O
,	O
requiring	O
a	O
telephone	O
amplifier	O
to	O
impedance-match	O
the	O
telephone	O
headset	B-Device
.	O
</s>
<s>
A	O
telephone	O
amplifier	O
provides	O
basic	O
pin-alignment	O
similar	O
to	O
a	O
telephone	O
headset	B-Device
adapter	O
,	O
but	O
it	O
also	O
offers	O
sound	O
amplification	O
for	O
the	O
microphone	O
as	O
well	O
as	O
the	O
loudspeakers	O
.	O
</s>
<s>
Most	O
models	O
of	O
telephone	O
amplifiers	O
offer	O
volume	O
control	O
for	O
the	O
loudspeaker	O
as	O
well	O
as	O
a	O
microphone	O
,	O
mute	O
function	O
and	O
switching	O
between	O
handset	O
and	O
headset	B-Device
.	O
</s>
<s>
Most	O
telephone	O
headsets	B-Device
have	O
a	O
Quick	O
Disconnect	O
(	O
QD	O
)	O
cable	O
,	O
allowing	O
fast	O
and	O
easy	O
disconnection	O
of	O
the	O
headset	B-Device
from	O
the	O
telephone	O
without	O
having	O
to	O
remove	O
the	O
headset	B-Device
.	O
</s>
<s>
It	O
is	O
usually	O
connected	O
to	O
a	O
wireless	O
headset	B-Device
and	O
allows	O
cordless	O
headset	B-Device
use	O
on	O
technically	O
primitive	O
desk	O
phones	O
.	O
</s>
<s>
The	O
lifter	O
allows	O
cordless	O
headsets	B-Device
to	O
be	O
used	O
remotely	O
with	O
such	O
phones	O
.	O
</s>
<s>
The	O
phone	O
user	O
presses	O
the	O
appropriate	O
headset	B-Device
button	O
to	O
either	O
answer	O
a	O
call	O
or	O
terminate	O
a	O
call	O
.	O
</s>
<s>
The	O
headset	B-Device
's	O
base	O
station	O
's	O
interface	O
with	O
the	O
handset	O
lifter	O
will	O
take	O
the	O
appropriate	O
action	O
-	O
lift	O
or	O
replace	O
the	O
handset	O
.	O
</s>
<s>
Computer	O
headsets	B-Device
generally	O
come	O
in	O
two	O
connection	O
types	O
:	O
standard	O
3.5mm	O
and	O
USB	B-Protocol
connection	O
.	O
</s>
<s>
General	O
3.5mm	O
computer	O
headsets	B-Device
come	O
with	O
two	O
3.5mm	O
connectors	O
:	O
one	O
connecting	O
to	O
the	O
microphone	B-Device
jack	I-Device
and	O
one	O
connecting	O
to	O
the	O
headphone/speaker	O
jack	O
of	O
the	O
computer	O
.	O
</s>
<s>
3.5mm	O
computer	O
headsets	B-Device
connect	O
to	O
the	O
computer	O
via	O
a	O
soundcard	B-Device
,	O
which	O
converts	O
the	O
digital	O
signal	O
of	O
the	O
computer	O
to	O
an	O
analog	O
signal	O
for	O
the	O
headset	B-Device
.	O
</s>
<s>
USB	B-Protocol
computer	O
headsets	B-Device
connect	O
to	O
the	O
computer	O
via	O
a	O
USB	B-Protocol
port	O
,	O
and	O
the	O
audio	O
conversion	O
occurs	O
in	O
the	O
headset	B-Device
or	O
in	O
the	O
control	O
unit	O
of	O
the	O
headset	B-Device
.	O
</s>
<s>
Gaming	O
headsets	B-Device
for	O
computers	O
are	O
specifically	O
designed	O
for	O
gaming	O
and	O
provide	O
some	O
additional	O
features	O
that	O
can	O
be	O
beneficial	O
for	O
gamers	O
.	O
</s>
<s>
Mobile	O
(	O
cellular	O
)	O
phone	O
headsets	B-Device
are	O
often	O
referred	O
to	O
as	O
handsfree	O
.	O
</s>
<s>
Mobile	O
headsets	B-Device
come	O
in	O
a	O
range	O
of	O
wearing-styles	O
,	O
including	O
behind-the-neck	O
,	O
over-the-head	O
,	O
over-the-ear	O
,	O
and	O
lightweight	O
earbuds	O
.	O
</s>
<s>
Some	O
aftermarket	O
mobile	O
headsets	B-Device
come	O
with	O
a	O
standard	O
2.5mm	O
plug	O
different	O
from	O
the	O
phone	O
's	O
audio	O
connector	O
,	O
so	O
users	O
have	O
to	O
purchase	O
an	O
adapter	O
.	O
</s>
<s>
A	O
USB	B-Protocol
headset	B-Device
for	O
a	O
computer	O
also	O
cannot	O
be	O
directly	O
plugged	O
into	O
a	O
phone	O
's	O
or	O
portable	O
media	O
player	O
's	O
micro-USB	O
slot	O
.	O
</s>
<s>
Smartphones	B-Application
often	O
use	O
a	O
standard	O
3.5mm	O
jack	O
,	O
so	O
users	O
may	O
be	O
able	O
to	O
directly	O
connect	O
the	O
headset	B-Device
to	O
it	O
.	O
</s>
<s>
There	O
are	O
however	O
different	O
pin-alignment	O
to	O
the	O
3.5mm	O
plug	O
,	O
mainly	O
OMTP	O
and	O
CTIA	O
,	O
so	O
a	O
user	O
should	O
find	O
out	O
which	O
settings	O
their	O
device	O
uses	O
before	O
buying	O
a	O
headphone/headset	O
.	O
</s>
<s>
Many	O
wireless	O
mobile	O
headsets	B-Device
use	O
Bluetooth	B-Protocol
technology	I-Protocol
,	O
supported	O
by	O
many	O
phones	O
and	O
computers	O
,	O
sometimes	O
by	O
connecting	O
a	O
Bluetooth	B-Protocol
adapter	O
to	O
a	O
USB	B-Protocol
port	O
.	O
</s>
<s>
Since	O
version	O
1.1	O
Bluetooth	B-Protocol
devices	O
can	O
transmit	O
voice	O
calls	O
and	O
play	O
several	O
music	O
and	O
video	O
formats	O
,	O
but	O
audio	O
will	O
not	O
be	O
played	O
in	O
stereo	O
unless	O
the	O
cell	O
phone	O
or	O
media	O
device	O
,	O
and	O
the	O
headset	B-Device
,	O
both	O
have	O
the	O
A2DP	O
profile	O
.	O
</s>
<s>
In	O
2019	O
,	O
wireless	O
headsets	B-Device
were	O
a	O
new	O
trend	O
for	O
business	O
and	O
consumer	O
communications	O
.	O
</s>
<s>
The	O
first	O
wireless	O
headsets	B-Device
were	O
jointly	O
invented	O
by	O
NASA	O
and	O
Plantronics	O
during	O
Apollo	O
program	O
to	O
improve	O
astronaut	O
's	O
communications	O
during	O
mission	O
.	O
</s>
<s>
Digital	B-Protocol
Enhanced	I-Protocol
Cordless	I-Protocol
Telecommunications	I-Protocol
(	O
DECT	B-Protocol
)	O
is	O
one	O
of	O
the	O
most	O
common	O
standards	O
for	O
cordless	O
telephones	O
.	O
</s>
<s>
Different	O
countries	O
have	O
regulations	O
for	O
the	O
bandwidth	O
used	O
in	O
DECT	B-Protocol
,	O
but	O
most	O
have	O
pre-set	O
this	O
band	O
for	O
wireless	O
audio	O
transmission	O
.	O
</s>
<s>
The	O
most	O
common	O
profile	O
of	O
DECT	B-Protocol
is	O
Generic	O
access	O
profile	O
(	O
GAP	O
)	O
,	O
which	O
is	O
used	O
to	O
ensure	O
common	O
communication	O
between	O
base	O
station	O
and	O
its	O
cordless	O
handset	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
Panasonic	O
DECT	B-Protocol
base-station	O
theoretically	O
can	O
connect	O
to	O
a	O
Siemens	O
DECT	B-Protocol
Handset	O
.	O
</s>
<s>
Based	O
on	O
this	O
profile	O
,	O
developers	O
such	O
as	O
Plantronics	O
,	O
Jabra	O
or	O
Accutone	O
have	O
launched	O
wireless	O
headsets	B-Device
which	O
can	O
directly	O
pair	O
with	O
any	O
GAP-enabled	O
DECT	B-Protocol
telephones	I-Protocol
.	O
</s>
<s>
So	O
users	O
with	O
a	O
DECT	B-Protocol
Wireless	O
Headset	B-Device
can	O
pair	O
it	O
with	O
their	O
home	O
DECT	B-Protocol
phones	O
and	O
enjoy	O
wireless	O
communication	O
.	O
</s>
<s>
Because	O
DECT	B-Protocol
specifications	O
are	O
different	O
between	O
countries	O
,	O
developers	O
who	O
use	O
the	O
same	O
product	O
across	O
different	O
countries	O
have	O
launched	O
wireless	O
headsets	B-Device
which	O
use	O
2.4GHz	B-Algorithm
RF	O
as	O
opposed	O
to	O
the	O
1.89	O
or	O
1.9GHz	O
in	O
DECT	B-Protocol
.	O
</s>
<s>
Almost	O
all	O
countries	O
in	O
the	O
world	O
have	O
the	O
2.4GHz	B-Algorithm
band	I-Algorithm
open	O
for	O
wireless	O
communications	O
,	O
so	O
headsets	B-Device
using	O
this	O
RF	O
band	O
is	O
sellable	O
in	O
most	O
markets	O
.	O
</s>
<s>
However	O
,	O
the	O
2.4GHz	B-Algorithm
frequency	O
is	O
also	O
the	O
base	O
frequency	O
for	O
many	O
wireless	O
data	O
transmission	O
,	O
i.e.	O
</s>
<s>
Wireless	B-Architecture
LAN	I-Architecture
,	O
Wi-Fi	O
,	O
Bluetooth	B-Protocol
...	O
,	O
the	O
bandwidth	O
may	O
be	O
quite	O
crowded	O
,	O
so	O
using	O
this	O
technology	O
may	O
be	O
more	O
prone	O
to	O
interference	O
.	O
</s>
<s>
Because	O
2.4GHz	B-Algorithm
Wireless	O
Headsets	B-Device
cannot	O
directly	O
"	O
talk	O
"	O
to	O
any	O
standard	O
cordless	O
telephones	O
,	O
an	O
extra	O
base-unit	O
is	O
required	O
for	O
this	O
product	O
to	O
function	O
.	O
</s>
<s>
Most	O
2.4GHz	B-Algorithm
Wireless	O
Headsets	B-Device
come	O
in	O
two	O
units	O
,	O
a	O
wireless	O
headset	B-Device
and	O
a	O
wireless	O
base-station	O
,	O
which	O
connects	O
to	O
your	O
original	O
telephone	O
unit	O
via	O
the	O
handset	O
jack	O
.	O
</s>
<s>
The	O
wireless	O
headset	B-Device
communicates	O
with	O
the	O
base-station	O
via	O
2.4GHz	B-Algorithm
RF	O
,	O
and	O
the	O
voice	O
signals	O
are	O
sent	O
or	O
received	O
via	O
the	O
base	O
unit	O
to	O
the	O
telephone	O
unit	O
.	O
</s>
<s>
Some	O
products	O
will	O
also	O
offer	O
an	O
automatic	O
handset	O
lifter	O
,	O
so	O
the	O
user	O
can	O
wirelessly	O
lift	O
the	O
handset	O
off	O
the	O
telephone	O
by	O
pressing	O
the	O
button	O
on	O
the	O
wireless	O
headset	B-Device
.	O
</s>
<s>
Bluetooth	B-Protocol
technology	I-Protocol
is	O
widely	O
used	O
for	O
short-range	O
voice	O
transmission	O
.	O
</s>
<s>
A	O
very	O
common	O
application	O
is	O
a	O
hands-free	O
Bluetooth	B-Protocol
earpiece	O
for	O
a	O
phone	O
which	O
may	O
be	O
in	O
a	O
user	O
's	O
pocket	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
Bluetooth	B-Protocol
headsets	B-Device
.	O
</s>
<s>
Headsets	B-Device
using	O
Bluetooth	B-Protocol
v1.0	O
or	O
v1.1	O
generally	O
consist	O
of	O
a	O
single	O
monaural	O
earpiece	O
,	O
which	O
can	O
only	O
access	O
Bluetooth	B-Protocol
's	O
headset/handsfree	O
profile	O
.	O
</s>
<s>
Depending	O
on	O
the	O
phone	O
's	O
operating	O
system	O
,	O
this	O
type	O
of	O
headset	B-Device
will	O
either	O
play	O
music	O
at	O
a	O
very	O
low	O
quality	O
(	O
suitable	O
for	O
voice	O
)	O
,	O
or	O
will	O
be	O
unable	O
to	O
play	O
music	O
at	O
all	O
.	O
</s>
<s>
Headsets	B-Device
with	O
the	O
A2DP	O
profile	O
can	O
play	O
stereo	O
music	O
with	O
acceptable	O
quality	O
.	O
</s>
<s>
Some	O
A2DP-equipped	O
headsets	B-Device
automatically	O
de-activate	O
the	O
microphone	O
function	O
while	O
playing	O
music	O
;	O
if	O
these	O
headsets	B-Device
are	O
paired	O
to	O
a	O
computer	O
via	O
Bluetooth	B-Protocol
connection	O
,	O
the	O
headset	B-Device
may	O
disable	O
either	O
the	O
stereo	O
or	O
the	O
microphone	O
function	O
.	O
</s>
<s>
Desktop	O
devices	O
using	O
Bluetooth	B-Protocol
technology	I-Protocol
are	O
available	O
.	O
</s>
<s>
With	O
a	O
base	O
station	O
that	O
connects	O
via	O
cables	O
to	O
the	O
fixed-line	B-Application
telephone	I-Application
and	O
also	O
the	O
computer	O
via	O
soundcard	B-Device
,	O
users	O
with	O
any	O
Bluetooth	B-Protocol
headset	B-Device
can	O
pair	O
their	O
headset	B-Device
to	O
the	O
base	O
station	O
,	O
enabling	O
them	O
to	O
use	O
the	O
same	O
headset	B-Device
for	O
both	O
fixed-line	B-Application
telephone	I-Application
and	O
computer	O
VoIP	O
communication	O
.	O
</s>
<s>
This	O
type	O
of	O
device	O
,	O
when	O
used	O
together	O
with	O
a	O
multiple-point	O
Bluetooth	B-Protocol
headset	B-Device
,	O
enables	O
a	O
single	O
Bluetooth	B-Protocol
headset	B-Device
to	O
communicate	O
with	O
a	O
computer	O
and	O
both	O
mobile	O
and	O
landline	B-Application
telephones	I-Application
.	O
</s>
<s>
Some	O
Bluetooth	B-Protocol
office	O
headsets	B-Device
incorporate	O
Class	O
1	O
Bluetooth	B-Protocol
into	O
the	O
base	O
station	O
so	O
that	O
,	O
when	O
used	O
with	O
a	O
Class	O
1	O
Bluetooth	B-Protocol
headset	B-Device
,	O
the	O
user	O
can	O
communicate	O
from	O
a	O
greater	O
distance	O
,	O
typically	O
around	O
100	O
feet	O
compared	O
to	O
the	O
33	O
feet	O
of	O
the	O
more	O
usual	O
Class	O
2	O
Bluetooth	B-Protocol
headset	B-Device
.	O
</s>
<s>
Many	O
headsets	B-Device
supplied	O
with	O
these	O
base	O
stations	O
connect	O
to	O
cellphones	O
via	O
Class	O
2	O
Bluetooth	B-Protocol
,	O
however	O
,	O
restricting	O
the	O
range	O
to	O
about	O
33	O
feet	O
.	O
</s>
<s>
These	O
headsets/phones	O
can	O
be	O
wired	O
or	O
wireless	O
.	O
</s>
