<s>
Mobile	B-Protocol
VoIP	I-Protocol
or	O
simply	O
mVoIP	O
is	O
an	O
extension	O
of	O
mobility	O
to	O
a	O
voice	B-Application
over	I-Application
IP	I-Application
network	O
.	O
</s>
<s>
Two	O
types	O
of	O
communication	O
are	O
generally	O
supported	O
:	O
cordless	O
telephones	O
using	O
DECT	B-Protocol
or	O
PCS	O
protocols	O
for	O
short	O
range	O
or	O
campus	O
communications	O
where	O
all	O
base	O
stations	O
are	O
linked	O
into	O
the	O
same	O
LAN	B-General_Concept
,	O
and	O
wider	O
area	O
communications	O
using	O
3G	B-Architecture
or	O
4G	B-Architecture
protocols	O
.	O
</s>
<s>
There	O
are	O
several	O
methodologies	O
that	O
allow	O
a	O
mobile	O
handset	O
to	O
be	O
integrated	O
into	O
a	O
VoIP	B-Application
network	O
.	O
</s>
<s>
One	O
implementation	O
turns	O
the	O
mobile	O
device	O
into	O
a	O
standard	O
SIP	B-Application
client	O
,	O
which	O
then	O
uses	O
a	O
data	O
network	O
to	O
send	O
and	O
receive	O
SIP	B-Application
messaging	O
,	O
and	O
to	O
send	O
and	O
receive	O
RTP	O
for	O
the	O
voice	O
path	O
.	O
</s>
<s>
This	O
methodology	O
of	O
turning	O
a	O
mobile	O
handset	O
into	O
a	O
standard	O
SIP	B-Application
client	O
requires	O
that	O
the	O
mobile	O
handset	O
support	O
,	O
at	O
minimum	O
,	O
high	O
speed	O
IP	O
communications	O
.	O
</s>
<s>
In	O
this	O
application	O
,	O
standard	O
VoIP	B-Application
protocols	O
(	O
typically	O
SIP	B-Application
)	O
are	O
used	O
over	O
any	O
broadband	O
IP-capable	O
wireless	O
network	O
connection	O
such	O
as	O
EVDO	O
rev	O
A	O
(	O
which	O
is	O
symmetrical	O
high	O
speed	O
—	O
both	O
high	O
speed	O
up	O
and	O
down	O
)	O
,	O
HSPA	O
,	O
Wi-Fi	O
or	O
WiMAX	O
.	O
</s>
<s>
Another	O
implementation	O
of	O
mobile	O
integration	O
uses	O
a	O
soft-switch	O
like	O
gateway	O
to	O
bridge	O
SIP	B-Application
and	O
RTP	O
into	O
the	O
mobile	O
network	O
's	O
SS7	O
infrastructure	O
.	O
</s>
<s>
In	O
this	O
implementation	O
,	O
the	O
mobile	O
handset	O
continues	O
to	O
operate	O
as	O
it	O
always	O
has	O
(	O
as	O
a	O
GSM	O
or	O
CDMA	O
based	O
device	O
)	O
,	O
but	O
now	O
it	O
can	O
be	O
controlled	O
by	O
a	O
SIP	B-Protocol
application	I-Protocol
server	I-Protocol
which	O
can	O
now	O
provide	O
advanced	O
SIP-based	O
services	O
to	O
it	O
.	O
</s>
<s>
Mobile	B-Protocol
VoIP	I-Protocol
will	O
require	O
a	O
compromise	O
between	O
economy	O
and	O
mobility	O
.	O
</s>
<s>
For	O
example	O
,	O
voice	B-Protocol
over	I-Protocol
Wi-Fi	I-Protocol
offers	O
potentially	O
free	O
service	O
but	O
is	O
only	O
available	O
within	O
the	O
coverage	O
area	O
of	O
a	O
single	O
Wi-Fi	O
access	O
point	O
.	O
</s>
<s>
Cordless	O
protocols	O
offer	O
excellent	O
voice	O
support	O
and	O
even	O
support	O
base	O
station	O
handoff	O
,	O
but	O
require	O
all	O
base	O
stations	O
to	O
communicate	O
on	O
one	O
LAN	B-General_Concept
as	O
the	O
handoff	O
protocol	O
is	O
generally	O
not	O
supported	O
by	O
carriers	O
or	O
most	O
devices	O
.	O
</s>
<s>
High	O
speed	O
services	O
from	O
mobile	O
operators	O
using	O
EVDO	O
rev	O
A	O
or	O
HSPA	O
may	O
have	O
better	O
audio	O
quality	O
and	O
capabilities	O
for	O
metropolitan-wide	O
coverage	O
including	O
fast	O
handoffs	O
among	O
mobile	O
base	O
stations	O
,	O
yet	O
may	O
cost	O
more	O
than	O
Wi-Fi-based	O
VoIP	B-Application
services	O
.	O
</s>
<s>
As	O
device	O
manufacturers	O
exploited	O
more	O
powerful	O
processors	O
and	O
less	O
costly	O
memory	O
,	O
smartphones	B-Application
became	O
capable	O
of	O
sending	O
and	O
receiving	O
email	O
,	O
browsing	O
the	O
web	O
(	O
albeit	O
at	O
low	O
rates	O
)	O
and	O
allowing	O
a	O
user	O
to	O
watch	O
TV	O
.	O
</s>
<s>
Mobile	B-Protocol
VoIP	I-Protocol
users	O
were	O
predicted	O
to	O
exceed	O
100	O
million	O
by	O
2012	O
and	O
InStat	O
projects	O
288	O
million	O
subscribers	O
by	O
2013	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
most	O
innovations	O
in	O
mobile	B-Protocol
VoIP	I-Protocol
will	O
likely	O
come	O
from	O
campus	O
and	O
corporate	O
networks	O
,	O
open	B-License
source	I-License
projects	O
like	O
Asterisk	B-Language
,	O
and	O
applications	O
where	O
the	O
benefits	O
are	O
high	O
enough	O
to	O
justify	O
expensive	O
experiments	O
(	O
medical	O
,	O
military	O
,	O
etc	O
.	O
</s>
<s>
Mobile	B-Protocol
VoIP	I-Protocol
,	O
like	O
all	O
VoIP	B-Application
,	O
relies	O
on	O
SIP	B-Application
—	O
the	O
standard	O
used	O
by	O
most	O
VoIP	B-Application
services	O
,	O
and	O
now	O
being	O
implemented	O
on	O
mobile	O
handsets	O
and	O
smartphones	B-Application
and	O
an	O
increasing	O
number	O
of	O
cordless	O
phones	O
.	O
</s>
<s>
UMA	O
—	O
the	O
Unlicensed	O
Mobile	O
Access	O
Generic	O
Access	O
Network	O
allows	O
VoIP	B-Application
to	O
run	O
over	O
the	O
GSM	O
cellular	O
backbone	O
.	O
</s>
<s>
For	O
indoor	O
or	O
campus	O
(	O
cordless	O
phone	O
equivalent	O
)	O
use	O
,	O
the	O
IEEE	O
P1905	O
protocol	O
establishes	O
QoS	O
guarantees	O
for	O
home	O
area	O
networks	O
:	O
Wi-Fi	O
,	O
Bluetooth	B-Protocol
,	O
3G	B-Architecture
,	O
4G	B-Architecture
and	O
wired	O
backbones	O
using	O
AC	O
powerline	O
networking/HomePlug/IEEE	O
P1901	O
,	O
Ethernet	O
and	O
Power	O
over	O
Ethernet/IEEE	O
802.3af/IEEE	O
802.3at	O
,	O
MoCA	O
and	O
G.hn	B-General_Concept
.	O
</s>
<s>
In	O
combination	O
with	O
IEEE	O
802.21	O
,	O
P1905	O
permits	O
a	O
call	O
to	O
be	O
initiated	O
on	O
a	O
wired	O
phone	O
and	O
transferred	O
to	O
a	O
wireless	O
one	O
and	O
then	O
resumed	O
on	O
a	O
wired	O
one	O
,	O
perhaps	O
with	O
additional	O
capabilities	O
such	O
as	O
videoconferencing	B-Application
in	O
another	O
room	O
.	O
</s>
<s>
In	O
this	O
case	O
the	O
use	O
of	O
mobile	B-Protocol
VoIP	I-Protocol
enables	O
a	O
continuous	O
conversation	O
that	O
originates	O
,	O
and	O
ends	O
with	O
,	O
a	O
wired	O
terminal	O
device	O
.	O
</s>
<s>
An	O
older	O
technology	O
,	O
PCS	O
base	O
station	O
handoff	O
,	O
specifies	O
equivalent	O
capabilities	O
for	O
cordless	O
phones	O
based	O
on	O
800	O
,	O
900	O
,	O
2.4	O
,	O
5.8	O
and	O
DECT	B-Protocol
.	O
</s>
<s>
A	O
phone	O
can	O
in	O
theory	O
offer	O
both	O
PCS	O
cordless	O
and	O
mobile	B-Protocol
VoIP	I-Protocol
and	O
permit	O
calls	O
to	O
be	O
handed	O
off	O
from	O
traditional	O
cordless	O
to	O
cell	O
and	O
back	O
to	O
cordless	O
if	O
both	O
the	O
PCS	O
and	O
UMA/SIP/IEEE	O
standards	O
suites	O
are	O
implemented	O
.	O
</s>
<s>
A	O
more	O
popular	O
approach	O
has	O
been	O
full-spectrum	O
handsets	O
that	O
can	O
communicate	O
with	O
any	O
wireless	O
network	O
including	O
mobile	B-Protocol
VoIP	I-Protocol
,	O
DECT	B-Protocol
and	O
satellite	O
phone	O
networks	O
,	O
but	O
which	O
have	O
limited	O
handoff	O
capabilities	O
between	O
networks	O
.	O
</s>
<s>
The	O
intent	O
of	O
IEEE	O
802.21	O
and	O
IEEE	O
802.11u	O
is	O
that	O
they	O
be	O
added	O
to	O
such	O
phones	O
running	O
iPhone	B-Device
,	O
QNX	B-Operating_System
,	O
Android	B-Application
or	O
other	O
smartphone	B-Application
operating	O
systems	O
,	O
yielding	O
a	O
phone	O
that	O
is	O
capable	O
of	O
communicating	O
with	O
literally	O
any	O
digital	O
network	O
and	O
maintaining	O
a	O
continuous	O
call	O
at	O
high	O
reliability	O
at	O
a	O
low	O
access	O
cost	O
.	O
</s>
<s>
Most	O
VoIP	B-Application
vendors	O
implement	O
proprietary	O
technologies	O
that	O
permit	O
such	O
handoff	O
between	O
equipment	O
of	O
their	O
own	O
manufacture	O
,	O
e.g.	O
</s>
<s>
Typically	O
providing	O
mobility	O
costs	O
more	O
,	O
e.g.	O
,	O
the	O
Panasonic	O
VoIP	B-Application
cordless	O
phone	O
system	O
(	O
KX-TGP	O
)	O
costs	O
approximately	O
three	O
times	O
more	O
than	O
its	O
popular	O
DECT	B-Protocol
PSTN	O
equivalent	O
(	O
KX-TGA	O
)	O
.	O
</s>
<s>
Some	O
companies	O
,	O
including	O
Cisco	O
,	O
offer	O
adapters	O
for	O
analog/DECT	O
phones	O
as	O
alternatives	O
to	O
their	O
expensive	O
cordless	O
.	O
</s>
<s>
Early	O
experiments	O
proved	O
that	O
VoIP	B-Application
was	O
practical	O
and	O
could	O
be	O
routed	O
by	O
Asterisk	B-Language
even	O
on	O
low-end	O
routers	O
like	O
the	O
Linksys	B-Application
WRT54G	I-Application
series	I-Application
.	O
</s>
<s>
Suggesting	O
a	O
mesh	B-Architecture
network	I-Architecture
(	O
e.g.	O
</s>
<s>
WDS	B-General_Concept
)	O
composed	O
of	O
such	O
cheap	O
devices	O
could	O
similarly	O
support	O
roaming	O
mobile	B-Protocol
VoIP	I-Protocol
phones	O
.	O
</s>
<s>
These	O
experiments	O
,	O
and	O
others	O
for	O
IP	O
roaming	O
such	O
as	O
Sputnik	B-Language
,	O
were	O
the	O
beginning	O
of	O
the	O
5G	O
protocol	O
suite	O
including	O
IEEE	O
802.21	O
and	O
IEEE	O
802.11u	O
.	O
</s>
<s>
At	O
this	O
time	O
,	O
some	O
mobile	O
operators	O
attempted	O
to	O
restrict	O
IP	O
tethering	O
and	O
VoIP	B-Application
use	O
on	O
their	O
networks	O
,	O
often	O
by	O
deliberately	O
introducing	O
high	O
latency	O
into	O
data	O
communications	O
making	O
it	O
useless	O
for	O
voice	O
traffic	O
.	O
</s>
<s>
In	O
the	O
summer	O
of	O
2006	O
,	O
a	O
SIP	B-Application
(	O
Session	B-Application
Initiation	I-Application
Protocol	I-Application
)	O
stack	O
was	O
introduced	O
and	O
a	O
VoIP	B-Application
client	O
in	O
Nokia	O
E-series	O
dual-mode	O
Wi-Fi	O
handsets	O
(	O
Nokia	B-Language
E60	I-Language
,	O
Nokia	B-Language
E61	I-Language
,	O
Nokia	O
E70	O
)	O
.	O
</s>
<s>
The	O
SIP	B-Application
stack	O
and	O
client	O
have	O
since	O
been	O
introduced	O
in	O
many	O
more	O
E	O
and	O
N-series	O
dual-mode	O
Wi-Fi	O
handsets	O
,	O
most	O
notably	O
the	O
Nokia	B-Language
N95	I-Language
which	O
has	O
been	O
very	O
popular	O
in	O
Europe	O
.	O
</s>
<s>
In	O
spring	O
2008	O
Nokia	O
introduced	O
a	O
built	O
in	O
SIP	B-Application
VoIP	B-Application
client	O
for	O
the	O
very	O
first	O
time	O
to	O
the	O
mass	O
market	O
device	O
(	O
Nokia	O
6300i	O
)	O
running	O
Series	O
40	O
operating	O
system	O
.	O
</s>
<s>
Later	O
that	O
year	O
(	O
Nokia	O
6260	O
Slide	O
was	O
introduced	O
introducing	O
slightly	O
updated	O
SIP	B-Application
VoIP	B-Application
client	O
.	O
</s>
<s>
Nokia	O
maintains	O
a	O
list	O
of	O
all	O
phones	O
that	O
have	O
an	O
integrated	O
VoIP	B-Application
client	O
in	O
Forum	O
Nokia	O
.	O
</s>
<s>
Aircell	O
's	O
battle	O
with	O
some	O
companies	O
allowing	O
VoIP	B-Application
calls	I-Application
on	O
flights	O
is	O
another	O
example	O
of	O
the	O
growing	O
conflict	O
of	O
interest	O
between	O
incumbent	O
operators	O
and	O
new	O
VoIP	B-Application
operators	O
.	O
</s>
<s>
By	O
January	O
2009	O
OpenWRT	B-Application
was	O
capable	O
of	O
supporting	O
mobile	B-Protocol
VoIP	I-Protocol
applications	O
via	O
Asterisk	B-Language
running	O
on	O
a	O
USB	B-Protocol
stick	O
.	O
</s>
<s>
As	O
OpenWRT	B-Application
runs	O
on	O
most	O
Wi-Fi	O
routers	O
,	O
this	O
radically	O
expanded	O
the	O
potential	O
reach	O
of	O
mobile	B-Protocol
VoIP	I-Protocol
applications	O
.	O
</s>
<s>
Users	O
reported	O
acceptable	O
results	O
using	O
G.729	B-Algorithm
codecs	O
and	O
connections	O
to	O
a	O
"	O
main	O
NAT/Firewall	O
router	O
with	O
a	O
NAT	O
=	O
yes	O
and	O
canreinvite	O
=	O
no	O
..	O
As	O
such	O
,	O
my	O
asterisk	B-Language
will	O
stay	O
in	O
the	O
audio	O
path	O
and	O
ca	O
n't	O
redirect	O
the	O
RTP	O
media	O
stream	O
(	O
audio	O
)	O
to	O
go	O
directly	O
from	O
the	O
caller	O
to	O
the	O
callee.	O
"	O
</s>
<s>
The	O
combination	O
of	O
OpenWRT	B-Application
and	O
Asterisk	B-Language
is	O
intended	O
as	O
an	O
open	B-License
source	I-License
replacement	O
for	O
proprietary	O
PBXes	B-Device
.	O
</s>
<s>
The	O
company	O
xG	O
Technology	O
,	O
Inc	O
.	O
had	O
a	O
mobile	B-Protocol
VoIP	I-Protocol
and	O
data	O
system	O
operating	O
in	O
the	O
license-free	O
ISM	O
900MHz	O
band	O
(	O
902MHz	O
–	O
928MHz	O
)	O
.	O
</s>
<s>
In	O
January	O
2010	O
Apple	O
Inc	O
.	O
updated	O
the	O
iPhone	B-Device
developer	O
SDK	O
to	O
allow	O
VoIP	B-Application
over	O
cellular	O
networks	O
.	O
</s>
<s>
iCall	O
became	O
the	O
first	O
App	O
Store	O
app	O
to	O
enable	O
VoIP	B-Application
on	O
the	O
iPhone	B-Device
and	O
iPod	O
Touch	O
over	O
cellular	O
3G	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
In	O
second	O
half	O
of	O
2010	O
Nokia	O
introduced	O
three	O
new	O
dualmode	O
Wi-Fi	O
capable	O
Series40	O
handsets	O
(	O
Nokia	O
X3-02	O
,	O
Nokia	O
C3-01	O
and	O
,	O
Nokia	O
C3-01	O
Gold	O
Edition	O
)	O
with	O
integrated	O
SIP	B-Application
VoIP	B-Application
that	O
supports	O
HD	B-Algorithm
voice	I-Algorithm
(	O
AMR-WB	O
)	O
.	O
</s>
<s>
The	O
mainstreaming	O
of	O
VoIP	B-Application
in	O
the	O
small	O
business	O
market	O
led	O
to	O
the	O
introduction	O
of	O
more	O
devices	O
extending	O
VoIP	B-Application
to	O
business	O
cordless	O
users	O
.	O
</s>
<s>
Panasonic	O
introduced	O
the	O
KX-TGP	O
base	O
station	O
supporting	O
up	O
to	O
6	O
cordless	O
handsets	O
,	O
essentially	O
a	O
VoIP	B-Application
complement	O
to	O
its	O
popular	O
KX-TGA	O
analogue	O
phones	O
which	O
likewise	O
support	O
up	O
to	O
4	O
cordless	O
handsets	O
.	O
</s>
<s>
However	O
,	O
unlike	O
the	O
analogue	O
system	O
which	O
supports	O
only	O
four	O
handsets	O
in	O
one	O
"	O
conference	O
"	O
on	O
one	O
line	O
,	O
the	O
TGP	O
supports	O
3	O
simultaneous	O
network	O
conversations	O
and	O
up	O
to	O
8	O
SIP	B-Application
registrations	O
(	O
e.g.	O
</s>
<s>
In	O
its	O
publicity	O
Panasonic	O
specifically	O
mentions	O
Digium	B-Protocol
(	O
founded	O
by	O
the	O
creator	O
of	O
Asterisk	B-Language
)	O
,	O
its	O
product	O
Switchvox	O
and	O
Asterisk	B-Language
itself	O
.	O
</s>
<s>
Several	O
router	O
manufacturers	O
including	O
TRENDnet	B-Protocol
and	O
Netgear	O
released	O
sub-	O
$300	O
Power	B-Device
over	I-Device
Ethernet	I-Device
switches	O
aimed	O
at	O
the	O
VoIP	B-Application
market	O
.	O
</s>
<s>
Unlike	O
industry	O
standard	O
switches	O
that	O
provided	O
the	O
full	O
30	O
watts	O
of	O
power	O
per	O
port	O
,	O
these	O
allowed	O
under	O
50	O
watts	O
of	O
power	O
to	O
all	O
four	O
PoE	B-Device
ports	O
combined	O
.	O
</s>
<s>
This	O
made	O
them	O
entirely	O
suitable	O
for	O
VoIP	B-Application
and	O
other	O
low-power	O
use	O
(	O
Motorola	O
Canopy	O
or	O
security	O
camera	O
or	O
Wi-Fi	O
APs	O
)	O
typical	O
of	O
a	O
SOHO	O
application	O
,	O
or	O
supporting	O
an	O
8-line	O
PBX	B-Device
,	O
especially	O
in	O
combination	O
with	O
a	O
multi-line	O
handset	O
such	O
as	O
the	O
Panasonic	O
KX-TGP	O
(	O
which	O
does	O
not	O
require	O
a	O
powered	O
port	O
)	O
.	O
</s>
<s>
Accordingly	O
,	O
by	O
the	O
end	O
of	O
2011	O
,	O
for	O
under	O
US$3000	O
it	O
was	O
possible	O
to	O
build	O
an	O
office	O
VoIP	B-Application
system	O
based	O
entirely	O
on	O
cordless	O
technology	O
capable	O
of	O
several	O
hundred	O
metres	O
reach	O
and	O
on	O
Power	B-Device
over	I-Device
Ethernet	I-Device
dedicated	O
wired	O
phones	O
,	O
with	O
up	O
to	O
8	O
DID	O
lines	O
and	O
3	O
simultaneous	O
conversations	O
per	O
base	O
station	O
,	O
with	O
24	O
handsets	O
each	O
capable	O
of	O
communicating	O
on	O
any	O
subset	O
of	O
the	O
8	O
lines	O
,	O
plus	O
an	O
unlimited	O
number	O
of	O
softphones	O
running	O
on	O
computers	O
and	O
laptops	O
and	O
smartphones	B-Application
.	O
</s>
<s>
This	O
compared	O
favourably	O
to	O
proprietary	O
PBX	B-Device
technology	O
especially	O
as	O
VoIP	B-Application
cordless	O
was	O
far	O
cheaper	O
than	O
PBX	B-Device
cordless	O
.	O
</s>
<s>
This	O
was	O
a	O
competitive	O
response	O
to	O
major	O
cordless	O
vendors	O
such	O
as	O
Panasonic	O
moving	O
into	O
the	O
business	O
VoIP	B-Application
cordless	O
market	O
Cisco	O
had	O
long	O
dominated	O
,	O
as	O
it	O
suppressed	O
the	O
market	O
for	O
the	O
cordless	O
makers	O
 '	O
native	O
VoIP	B-Application
phones	O
and	O
permitted	O
Cisco	O
to	O
argue	O
the	O
business	O
case	O
to	O
spend	O
more	O
on	O
switches	O
and	O
less	O
on	O
terminal	O
devices	O
.	O
</s>
<s>
However	O
,	O
this	O
solution	O
would	O
not	O
permit	O
the	O
analogue	O
phones	O
to	O
access	O
every	O
line	O
of	O
a	O
multi-line	O
PBX	B-Device
,	O
only	O
one	O
hardwired	O
line	O
per	O
phone	O
.	O
</s>
<s>
As	O
of	O
late	O
2011	O
,	O
most	O
cellular	O
data	O
networks	O
were	O
still	O
extremely	O
high	O
latency	O
and	O
effectively	O
useless	O
for	O
VoIP	B-Application
.	O
</s>
<s>
IP-only	O
providers	O
such	O
as	O
Voipstream	O
had	O
begun	O
to	O
serve	O
urban	O
areas	O
,	O
and	O
alternative	O
approaches	O
such	O
as	O
OpenBTS	B-Language
(	O
open	B-License
source	I-License
GSM	O
)	O
were	O
competing	O
with	O
mobile	B-Protocol
VoIP	I-Protocol
.	O
</s>
<s>
In	O
November	O
2011	O
,	O
Nokia	O
introduced	O
Nokia	B-Operating_System
Asha	I-Operating_System
303	I-Operating_System
with	O
integrated	O
SIP	B-Application
VoIP	B-Application
client	O
that	O
can	O
operate	O
both	O
over	O
Wi-Fi	O
and	O
3G	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
In	O
February	O
2012	O
,	O
Nokia	O
introduced	O
Nokia	O
Asha	O
302	O
and	O
in	O
June	O
Nokia	B-Operating_System
Asha	I-Operating_System
311	I-Operating_System
both	O
with	O
integrated	O
SIP	B-Application
VoIP	B-Application
client	O
that	O
can	O
operate	O
both	O
over	O
Wi-Fi	O
and	O
3G	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
By	O
September	O
2014	O
,	O
mobile-enabled	O
VoIP	B-Application
(	O
VoLTE	O
)	O
had	O
been	O
launched	O
by	O
T-Mobile	O
US	O
across	O
its	O
national	O
network	O
and	O
by	O
AT&T	O
Mobility	O
in	O
a	O
few	O
markets	O
.	O
</s>
<s>
Verizon	B-Application
plans	O
to	O
launch	O
its	O
VoLTE	O
service	O
"	O
in	O
the	O
coming	O
weeks	O
,	O
"	O
according	O
to	O
media	O
reports	O
in	O
August	O
,	O
2014	O
.	O
</s>
<s>
It	O
provides	O
HD	B-Algorithm
Voice	I-Algorithm
,	O
which	O
increases	O
mobile	O
voice	O
quality	O
,	O
and	O
permits	O
optional	O
use	O
of	O
video	B-Application
calling	I-Application
and	O
front	O
and	O
rear-facing	O
cameras	O
.	O
</s>
<s>
In	O
the	O
future	O
,	O
Verizon	B-Application
's	O
VoLTE	O
is	O
expected	O
to	O
also	O
permit	O
video	O
sharing	O
,	O
chat	O
functionality	O
,	O
and	O
file	O
transfers	O
.	O
</s>
