Modbus
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
114
with
one
special
application
rule
to
be
defined.
Use
default
value
for
those
parameters
that
are
not
mentioned
in
the
table.
Configuration
Path
[Special
AP
&
ALG]
‐
[Special
AP
List]
ID
1
Trigger
Port
554
(Quick
Time
4)
Incoming
Ports
6970
‐
6999
Rule
■
Enable
Scenario
Operation
Procedure
In
above
diagram,
the
Gateway
is
the
gateway
of
Network
‐
A
and
the
subnet
of
its
Intranet
is
10.0.75.0/24.
The
gateway
has
the
IP
address
of
10.0.75.2
for
LAN
interface
and
118.18.81.33
for
WAN
interface.
It
serves
as
a
NAT
router.
Define
a
special
application
rule
with
the
trigger
port
554
(Quick
Time
4)
and
incoming
ports
6970
‐
6999,
and
activate
the
rule.
So,
the
local
user
at
host
with
IP
address
10.0.75.100
can
enjoy
the
music
by
using
Quick
Time
4
application.
The
media
server
is
in
the
Internet.
ALG
Configuration
This
gateway
supports
the
SIP
ALG
feature
to
allow
one
SIP
phone
behind
the
NAT
gateway
can
call
another
SIP
phone
in
the
Internet,
even
the
gateway
executes
its
NAT
mechanism
between
the
Intranet
and
the
Internet.
The
NAT
gateway
monitors
the
control
traffic
and
open
up
port
mappings
(firewall
pinhole)
dynamically
as
required
to
know
about
an
address/port
number
combination
that
allows
incoming
packets,
so
it
will
support
address
and
port
translation
for
SIP
application
layer
"control/data"
protocols
as
shown
in
following
diagram.
The
NAT
Gateway
enables
the
SIP
ALG
feature,
so
it
will
monitor
the
SIP
Phone
#1
actions,
open
up
the
required
ports
and
make
the
address
and
port
translation
in
a
SIP
voice
communication.
