<s>
Anti-tromboning	B-Protocol
(	O
also	O
referred	O
to	O
as	O
anti-hairpinning	O
or	O
media	O
release	O
)	O
is	O
a	O
feature	O
employed	O
in	O
telecommunication	O
networks	O
,	O
such	O
as	O
voice	B-Application
over	I-Application
IP	I-Application
networks	O
,	O
that	O
optimises	O
the	O
use	O
of	O
the	O
access	O
network	O
and	O
reduces	O
excess	O
processing	O
and	O
traffic	O
.	O
</s>
<s>
Tromboning	B-Protocol
is	O
a	O
type	O
of	O
situation	O
that	O
occurs	O
when	O
data	O
is	O
transferred	O
through	O
a	O
path	O
that	O
goes	O
to	O
a	O
large	O
exchange	O
node	O
and	O
back	O
,	O
much	O
in	O
the	O
way	O
that	O
the	O
path	O
of	O
the	O
sound	O
waves	O
inside	O
a	O
trombone	O
can	O
be	O
elongated	O
by	O
extending	O
the	O
trombone	O
's	O
slide	O
,	O
despite	O
the	O
air	O
entry	O
and	O
exit	O
points	O
remaining	O
the	O
same	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
a	O
poorly	O
optimised	O
network	O
a	O
local	O
telephone	O
call	O
may	O
be	O
routed	O
through	O
an	O
international	B-Device
exchange	I-Device
;	O
or	O
internet	O
traffic	O
between	O
an	O
internet	O
user	O
and	O
a	O
website	O
may	O
be	O
needlessly	O
diverted	O
through	O
a	O
data	O
center	O
,	O
adding	O
to	O
latency	B-Protocol
and	O
costs	O
.	O
</s>
<s>
A	O
network	O
border	O
node	O
,	O
such	O
as	O
a	O
session	B-Protocol
border	I-Protocol
controller	I-Protocol
,	O
handling	O
calls	O
as	O
they	O
pass	O
from	O
the	O
access	O
network	O
to	O
the	O
core	O
network	O
can	O
examine	O
the	O
IP	B-Protocol
address	I-Protocol
or	O
domains	O
of	O
both	O
the	O
caller	O
and	O
called	O
parties	O
and	O
if	O
they	O
reside	O
in	O
the	O
same	O
part	O
of	O
the	O
network	O
the	O
media	O
path	O
can	O
be	O
released	O
allowing	O
media	O
to	O
flow	O
directly	O
between	O
the	O
two	O
parties	O
without	O
entering	O
the	O
access	O
network	O
.	O
</s>
<s>
This	O
extends	O
into	O
situations	O
where	O
bulk	O
data	O
can	O
be	O
sent	O
over	O
a	O
less	O
reliable	O
but	O
higher-bandwidth	O
(	O
capacity	O
)	O
and	O
cheaper	O
or	O
faster	O
link	O
,	O
whilst	O
parity	B-Error_Name
data	I-Error_Name
for	O
reconstructing	O
bad	O
packets	O
or	O
supporting	O
determinancy	O
in	O
fuzzy-state	O
weakly	O
determined	O
data	O
can	O
be	O
sent	O
over	O
more	O
reliable	O
but	O
lower-bandwidth	O
and	O
more	O
expensive	O
or	O
more	O
latency-incurring	O
link	O
.	O
</s>
<s>
A	O
subscription	O
service	O
may	O
primarily	O
support	O
paying	O
members	O
,	O
but	O
allocate	O
a	O
certain	O
amount	O
of	O
under-utilised	O
bandwidth	O
to	O
provide	O
longhaul	O
access	O
to	O
non-paying	O
members	O
,	O
with	O
the	O
assumption	O
that	O
these	O
members	O
will	O
in	O
turn	O
provide	O
paying	O
members	O
with	O
traversal	O
of	O
bulk	O
media	O
data	O
within	O
a	O
geographical	O
area	O
,	O
or	O
even	O
high-latency	O
propagation	O
across	O
cells	O
.	O
</s>
