<s>
In	O
telephony	O
,	O
an	O
international	B-Device
gateway	I-Device
exchange	I-Device
is	O
a	O
telephone	O
switch	O
that	O
forms	O
the	O
gateway	O
between	O
a	O
national	O
telephone	O
network	O
and	O
one	O
or	O
more	O
other	O
international	B-Device
gateway	I-Device
exchanges	I-Device
,	O
thus	O
providing	O
cross-border	O
connectivity	O
.	O
</s>
<s>
Whereas	O
international	B-Device
gateway	I-Device
exchanges	I-Device
are	O
commonly	O
implemented	O
using	O
hardware	O
that	O
could	O
also	O
serve	O
to	O
build	O
a	O
Class	B-Device
4	I-Device
(	O
national	O
transit	O
)	O
switch	O
,	O
some	O
of	O
the	O
differences	O
between	O
an	O
international	B-Device
gateway	I-Device
exchange	I-Device
and	O
a	O
Class	B-Device
4	I-Device
switch	I-Device
include	O
:	O
</s>
<s>
International	O
variants	O
of	O
signalling	O
protocols	O
,	O
such	O
as	O
International	O
ISUP	B-Protocol
and	O
#5	O
,	O
in	O
addition	O
to	O
the	O
relevant	O
national	O
signalling	O
protocols	O
.	O
</s>
<s>
High	O
capacity	O
(	O
some	O
of	O
the	O
largest	O
telephone	O
exchanges	O
in	O
the	O
world	O
are	O
international	B-Device
gateway	I-Device
exchanges	I-Device
)	O
.	O
</s>
