<s>
The	O
next-generation	B-Protocol
network	I-Protocol
(	O
NGN	O
)	O
is	O
a	O
body	O
of	O
key	O
architectural	O
changes	O
in	O
telecommunication	O
core	B-General_Concept
and	O
access	O
networks	O
.	O
</s>
<s>
The	O
general	O
idea	O
behind	O
the	O
NGN	O
is	O
that	O
one	O
network	B-Architecture
transports	O
all	O
information	O
and	O
services	O
(	O
voice	O
,	O
data	O
,	O
and	O
all	O
sorts	O
of	O
media	O
such	O
as	O
video	O
)	O
by	O
encapsulating	O
these	O
into	O
IP	B-Protocol
packets	B-Protocol
,	O
similar	O
to	O
those	O
used	O
on	O
the	O
Internet	O
.	O
</s>
<s>
NGNs	O
are	O
commonly	O
built	O
around	O
the	O
Internet	B-Protocol
Protocol	I-Protocol
,	O
and	O
therefore	O
the	O
term	O
all	B-Protocol
IP	I-Protocol
is	O
also	O
sometimes	O
used	O
to	O
describe	O
the	O
transformation	O
of	O
formerly	O
telephone-centric	O
networks	O
toward	O
NGN	O
.	O
</s>
<s>
NGN	O
is	O
a	O
different	O
concept	O
from	O
Future	B-Architecture
Internet	I-Architecture
,	O
which	O
is	O
more	O
focused	O
on	O
the	O
evolution	O
of	O
Internet	O
in	O
terms	O
of	O
the	O
variety	O
and	O
interactions	O
of	O
services	O
offered	O
.	O
</s>
<s>
A	O
next-generation	B-Protocol
network	I-Protocol
(	O
NGN	O
)	O
is	O
a	O
packet-based	O
network	B-Architecture
which	O
can	O
provide	O
services	O
including	O
Telecommunication	O
Services	O
and	O
is	O
able	O
to	O
make	O
use	O
of	O
multiple	O
broadband	B-General_Concept
,	O
quality	O
of	O
service-enabled	O
transport	O
technologies	O
and	O
in	O
which	O
service-related	O
functions	O
are	O
independent	O
from	O
underlying	O
transport-related	O
technologies	O
.	O
</s>
<s>
In	O
the	O
core	B-General_Concept
network	I-General_Concept
,	O
NGN	O
implies	O
a	O
consolidation	O
of	O
several	O
(	O
dedicated	O
or	O
overlay	O
)	O
transport	O
networks	O
each	O
historically	O
built	O
for	O
a	O
different	O
service	O
into	O
one	O
core	B-General_Concept
transport	O
network	B-Architecture
(	O
often	O
based	O
on	O
IP	B-Protocol
and	O
Ethernet	O
)	O
.	O
</s>
<s>
It	O
implies	O
amongst	O
others	O
the	O
migration	O
of	O
voice	O
from	O
a	O
circuit-switched	O
architecture	O
(	O
PSTN	O
)	O
to	O
VoIP	B-Application
,	O
and	O
also	O
migration	O
of	O
legacy	O
services	O
such	O
as	O
X.25	B-Protocol
,	O
Frame	B-Protocol
Relay	I-Protocol
(	O
either	O
commercial	O
migration	O
of	O
the	O
customer	O
to	O
a	O
new	O
service	O
like	O
IP	B-Application
VPN	I-Application
,	O
or	O
technical	O
emigration	O
by	O
emulation	O
of	O
the	O
"	O
legacy	O
service	O
"	O
on	O
the	O
NGN	O
)	O
.	O
</s>
<s>
In	O
the	O
wired	O
access	O
network	B-Architecture
,	O
NGN	O
implies	O
the	O
migration	O
from	O
the	O
dual	O
system	O
of	O
legacy	O
voice	O
next	O
to	O
xDSL	O
setup	O
in	O
local	O
exchanges	O
to	O
a	O
converged	O
setup	O
in	O
which	O
the	O
DSLAMs	B-Protocol
integrate	O
voice	O
ports	O
or	O
VoIP	B-Application
,	O
making	O
it	O
possible	O
to	O
remove	O
the	O
voice	O
switching	O
infrastructure	O
from	O
the	O
exchange	O
.	O
</s>
<s>
In	O
the	O
cable	O
access	O
network	B-Architecture
,	O
NGN	O
convergence	O
implies	O
migration	O
of	O
constant	O
bit	O
rate	O
voice	O
to	O
CableLabs	O
PacketCable	B-Device
standards	O
that	O
provide	O
VoIP	B-Application
and	O
SIP	B-Application
services	O
.	O
</s>
<s>
In	O
an	O
NGN	O
,	O
there	O
is	O
a	O
more	O
defined	O
separation	O
between	O
the	O
transport	O
(	O
connectivity	O
)	O
portion	O
of	O
the	O
network	B-Architecture
and	O
the	O
services	O
that	O
run	O
on	O
top	O
of	O
that	O
transport	O
.	O
</s>
<s>
Increasingly	O
applications	O
,	O
including	O
voice	O
,	O
tend	O
to	O
be	O
independent	O
of	O
the	O
access	O
network	B-Architecture
(	O
de-layering	O
of	O
network	B-Architecture
and	O
applications	O
)	O
and	O
will	O
reside	O
more	O
on	O
end-user	O
devices	O
(	O
phone	O
,	O
PC	O
,	O
set-top	O
box	O
)	O
.	O
</s>
<s>
Next-generation	B-Protocol
networks	I-Protocol
are	O
based	O
on	O
Internet	B-Architecture
technologies	I-Architecture
including	O
Internet	B-Protocol
Protocol	I-Protocol
(	O
IP	B-Protocol
)	O
and	O
multiprotocol	B-Protocol
label	I-Protocol
switching	I-Protocol
(	O
MPLS	B-Protocol
)	O
.	O
</s>
<s>
At	O
the	O
application	O
level	O
,	O
Session	B-Application
Initiation	I-Application
Protocol	I-Application
(	O
SIP	B-Application
)	O
seems	O
to	O
be	O
taking	O
over	O
from	O
ITU-T	O
H.323	B-Protocol
.	O
</s>
<s>
Initially	O
H.323	B-Protocol
was	O
the	O
most	O
popular	O
protocol	O
,	O
though	O
its	O
popularity	O
decreased	O
in	O
the	O
"	O
local	O
loop	O
"	O
due	O
to	O
its	O
original	O
poor	O
traversal	O
of	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
(	O
NAT	O
)	O
and	O
firewalls	O
.	O
</s>
<s>
For	O
this	O
reason	O
as	O
domestic	O
VoIP	B-Application
services	O
have	O
been	O
developed	O
,	O
SIP	B-Application
has	O
been	O
more	O
widely	O
adopted	O
.	O
</s>
<s>
However	O
,	O
in	O
voice	O
networks	O
where	O
everything	O
is	O
under	O
the	O
control	O
of	O
the	O
network	B-Architecture
operator	O
or	O
telco	O
,	O
many	O
of	O
the	O
largest	O
carriers	O
use	O
H.323	B-Protocol
as	O
the	O
protocol	O
of	O
choice	O
in	O
their	O
core	B-General_Concept
backbones	O
.	O
</s>
<s>
With	O
the	O
most	O
recent	O
changes	O
introduced	O
for	O
H.323	B-Protocol
,	O
it	O
is	O
now	O
possible	O
for	O
H.323	B-Protocol
devices	O
to	O
easily	O
and	O
consistently	O
traverse	O
NAT	O
and	O
firewall	O
devices	O
,	O
opening	O
up	O
the	O
possibility	O
that	O
H.323	B-Protocol
may	O
again	O
be	O
looked	O
upon	O
more	O
favorably	O
in	O
cases	O
where	O
such	O
devices	O
encumbered	O
its	O
use	O
previously	O
.	O
</s>
<s>
Nonetheless	O
,	O
most	O
of	O
the	O
telcos	O
are	O
extensively	O
researching	O
and	O
supporting	O
IP	B-Protocol
Multimedia	I-Protocol
Subsystem	I-Protocol
(	O
IMS	O
)	O
,	O
which	O
gives	O
SIP	B-Application
a	O
major	O
chance	O
of	O
being	O
the	O
most	O
widely	O
adopted	O
protocol	O
.	O
</s>
<s>
For	O
voice	O
applications	O
one	O
of	O
the	O
most	O
important	O
devices	O
in	O
NGN	O
is	O
a	O
Softswitch	B-Device
–	O
a	O
programmable	O
device	O
that	O
controls	O
Voice	B-Application
over	I-Application
IP	I-Application
(	O
VoIP	B-Application
)	O
calls	O
.	O
</s>
<s>
The	O
most	O
important	O
function	O
of	O
the	O
Softswitch	B-Device
is	O
creating	O
the	O
interface	O
to	O
the	O
existing	O
telephone	O
network	B-Architecture
,	O
PSTN	O
,	O
through	O
Signalling	B-Protocol
Gateways	I-Protocol
and	O
Media	O
Gateways	O
.	O
</s>
<s>
However	O
,	O
the	O
Softswitch	B-Device
as	O
a	O
term	O
may	O
be	O
defined	O
differently	O
by	O
the	O
different	O
equipment	O
manufacturers	O
and	O
have	O
somewhat	O
different	O
functions	O
.	O
</s>
<s>
One	O
may	O
quite	O
often	O
find	O
the	O
term	O
Gatekeeper	B-Application
in	O
NGN	O
literature	O
.	O
</s>
<s>
This	O
was	O
originally	O
a	O
VoIP	B-Application
device	O
,	O
which	O
converted	O
(	O
using	O
gateways	O
)	O
voice	O
and	O
data	O
from	O
their	O
analog	O
or	O
digital	O
switched-circuit	O
form	O
(	O
PSTN	O
,	O
SS7	O
)	O
to	O
the	O
packet-based	O
one	O
(	O
IP	B-Protocol
)	O
.	O
</s>
<s>
As	O
soon	O
as	O
this	O
kind	O
of	O
device	O
started	O
using	O
the	O
Media	B-Protocol
Gateway	I-Protocol
Control	I-Protocol
Protocol	I-Protocol
,	O
the	O
name	O
was	O
changed	O
to	O
Media	B-Protocol
Gateway	I-Protocol
Controller	I-Protocol
(	O
MGC	O
)	O
.	O
</s>
<s>
The	O
IP	B-Protocol
Multimedia	I-Protocol
Subsystem	I-Protocol
(	O
IMS	O
)	O
is	O
a	O
standardised	O
NGN	O
architecture	O
for	O
an	O
Internet	O
media-services	O
capability	O
defined	O
by	O
the	O
European	O
Telecommunications	O
Standards	O
Institute	O
(	O
ETSI	O
)	O
and	O
the	O
3rd	O
Generation	O
Partnership	O
Project	O
(	O
3GPP	O
)	O
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
another	O
popular	O
acronym	O
was	O
introduced	O
by	O
BT	O
(	O
British	O
Telecom	O
)	O
as	O
21CN	O
(	O
21st	O
Century	O
Networks	O
,	O
sometimes	O
mistakenly	O
quoted	O
as	O
C21N	O
)	O
—	O
this	O
is	O
another	O
loose	O
term	O
for	O
NGN	O
and	O
denotes	O
BT	O
's	O
initiative	O
to	O
deploy	O
and	O
operate	O
NGN	O
switches	O
and	O
networks	O
in	O
the	O
period	O
2006	O
–	O
2008	O
(	O
the	O
aim	O
being	O
by	O
2008	O
BT	O
to	O
have	O
only	O
all-IP	B-Protocol
switches	O
in	O
their	O
network	B-Architecture
)	O
.	O
</s>
<s>
THUS	O
 '	O
NGN	O
contains	O
10,600	O
km	O
of	O
fibre	B-Architecture
optic	I-Architecture
cable	O
with	O
more	O
than	O
190	O
points	O
of	O
presence	O
throughout	O
the	O
UK	O
.	O
</s>
<s>
The	O
core	B-General_Concept
optical	O
network	B-Architecture
uses	O
dense	O
wavelength-division	O
multiplexing	O
(	O
DWDM	O
)	O
technology	O
to	O
provide	O
scalability	O
to	O
many	O
hundreds	O
of	O
gigabits	O
per	O
second	O
of	O
bandwidth	O
,	O
in	O
line	O
with	O
growth	O
demand	O
.	O
</s>
<s>
On	O
top	O
of	O
this	O
,	O
the	O
THUS	O
backbone	B-General_Concept
network	I-General_Concept
uses	O
MPLS	B-Protocol
technology	O
to	O
deliver	O
the	O
highest	O
possible	O
performance	O
.	O
</s>
<s>
IP/MPLS	B-Protocol
-based	O
services	O
carry	O
voice	O
,	O
video	O
and	O
data	O
traffic	O
across	O
a	O
converged	O
infrastructure	O
,	O
potentially	O
allowing	O
organisations	O
to	O
enjoy	O
lower	O
infrastructure	O
costs	O
,	O
as	O
well	O
as	O
added	O
flexibility	O
and	O
functionality	O
.	O
</s>
<s>
The	O
THUS	O
NGN	O
accommodates	O
seven	O
Classes	O
of	O
Service	O
,	O
four	O
of	O
which	O
are	O
currently	O
offered	O
on	O
MPLS	B-Protocol
IP	B-Application
VPN	I-Application
.	O
</s>
<s>
In	O
the	O
Netherlands	O
,	O
KPN	O
is	O
developing	O
an	O
NGN	O
in	O
a	O
network	B-Architecture
transformation	O
program	O
called	O
all-IP	B-Protocol
.	O
</s>
<s>
Next	B-Protocol
Generation	I-Protocol
Networks	I-Protocol
also	O
extends	O
into	O
the	O
messaging	O
domain	O
and	O
in	O
Ireland	O
,	O
Openmind	O
Networks	O
has	O
designed	O
,	O
built	O
and	O
deployed	O
Traffic	O
Control	O
to	O
handle	O
the	O
demands	O
and	O
requirements	O
of	O
all	B-Protocol
IP	I-Protocol
networks	O
.	O
</s>
<s>
In	O
Bulgaria	O
,	O
BTC	O
(	O
Bulgarian	O
Telecommunications	O
Company	O
)	O
has	O
implemented	O
the	O
NGN	O
as	O
underlying	O
network	B-Architecture
of	O
its	O
telco	O
services	O
on	O
a	O
large-scale	O
project	O
in	O
2004	O
.	O
</s>
<s>
The	O
inherent	O
flexibility	O
and	O
scalability	O
of	O
the	O
new	O
core	B-General_Concept
network	I-General_Concept
approach	O
resulted	O
in	O
an	O
unprecedented	O
rise	O
of	O
classical	O
services	O
deployment	O
as	O
POTS/ISDN	O
,	O
Centrex	O
,	O
ADSL	O
,	O
VPN	B-Application
,	O
as	O
well	O
as	O
implementation	O
of	O
higher	O
bandwidths	O
for	O
the	O
Metro	O
and	O
Long-distance	O
Ethernet	O
/	O
VPN	B-Application
services	O
,	O
cross-national	O
transits	O
and	O
WebTV/IPTV	O
application	O
.	O
</s>
<s>
In	O
February	O
2014	O
,	O
Deutsche	O
Telekom	O
revealed	O
that	O
its	O
subsidiary	O
Makedonski	O
Telekom	O
had	O
become	O
the	O
first	O
European	O
incumbent	O
to	O
convert	O
its	O
PSTN	O
infrastructure	O
to	O
an	O
all	B-Protocol
IP	I-Protocol
network	B-Architecture
.	O
</s>
<s>
The	O
capital	O
investment	O
worth	O
14	O
million	O
euros	O
makes	O
Macedonia	O
the	O
first	O
country	O
in	O
the	O
South-East	O
Europe	O
whose	O
network	B-Architecture
will	O
be	O
fully	O
based	O
on	O
Internet	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
In	O
Canada	O
,	O
startup	O
Wind	O
Mobile	O
owned	O
by	O
Globalive	O
is	O
deploying	O
an	O
all-ip	B-Protocol
wireless	O
backbone	O
for	O
its	O
mobile	O
phone	O
service	O
.	O
</s>
<s>
In	O
mid	O
2005	O
,	O
China	O
Telecom	O
announced	O
its	O
commercial	O
roll-out	O
of	O
China	O
Telecom	O
's	O
Next	O
Generation	O
Carrying	O
Network	B-Architecture
,	O
or	O
CN2	O
,	O
using	O
Internet	B-Protocol
Protocol	I-Protocol
Next-Generation	B-Protocol
Network	I-Protocol
(	O
IP	B-Protocol
NGN	O
)	O
architecture	O
.	O
</s>
<s>
Its	O
IPv6-capable	O
backbone	B-General_Concept
network	I-General_Concept
leverages	O
softswitches	B-Device
(	O
the	O
control	O
layer	O
)	O
and	O
protocols	O
like	O
DiffServ	O
and	O
MPLS	B-Protocol
,	O
which	O
boosts	O
performance	O
of	O
its	O
bearer	O
layer	O
.	O
</s>
<s>
The	O
MPLS-optimized	O
architecture	O
also	O
enables	O
Frame	B-Protocol
Relay	I-Protocol
and	O
ATM	O
traffic	O
to	O
be	O
transported	O
over	O
a	O
Layer	O
2	O
VPN	B-Application
,	O
which	O
supports	O
both	O
legacy	O
traffic	O
and	O
new	O
IP	B-Protocol
services	O
over	O
a	O
single	O
IP/MPLS	B-Protocol
network	B-Architecture
.	O
</s>
