...
Functional
...
Requirements
...
Use
...
case
...
1:
...
| No Format |
|---|
(A) Calling T.38 endpoint <-->
(B) Channel Driver 1<-->
(C) Asterisk Core <-->
(D) T.38 Gateway Object <-->
(E) Channel Driver 2<-->
(F) Called T.30 endpoint
{noformat}
{ |
| Wiki Markup |
|---|
{graphviz} digraph G { "Calling T.38 Endpoint" -> "Channel Driver 1"; "Channel Driver 1" -> "Calling T.38 Endpoint"; subgraph cluster_1 { style=filled; label = "Asterisk"; "Channel Driver 1" -> "Asterisk Core"; "Asterisk Core" -> "Channel Driver 1"; "Asterisk Core" -> "T.38 Gateway Object"; "T.38 Gateway Object" -> "Asterisk Core"; "T.38 Gateway Object" -> "Channel Driver 2"; "Channel Driver 2" -> "T.38 Gateway Object"; } "Channel Driver 2" -> "Called T.30 Endpoint"; "Called T.30 Endpoint" -> "Channel Driver 2"; } {graphviz} |
In
...
this
...
use
...
case,
...
the
...
calling
...
endpoint
...
is
...
T.38
...
equipped
...
and
...
the
...
called
...
endpoint
...
is
...
not
...
(supports
...
T.30
...
only);
...
in
...
addition,
...
the
...
calling
...
endpoint
...
is
...
properly
...
configured
...
to
...
not
...
initiate
...
T.38
...
re-INVITEs
...
itself,
...
but
...
relies
...
on
...
the
...
receiving
...
gateway
...
(Asterisk+T.38
...
Gateway)
...
to
...
do
...
so.
...
during
...
call
...
setup,
...
called
...
endpoint
...
is
...
ringing,
...
gateway
...
does
...
nothing
...
when
...
called
...
endpoint
...
has
...
answered,
...
gateway
...
listens
...
for
...
FAX
...
preamble
...
(using
...
V.21
...
detector)
...
generated
...
by
...
called
...
endpoint
...
if
...
preamble
...
is
...
not
...
detected
...
after
...
15
...
seconds
...
from
...
call
...
answer,
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(this
...
may
...
need
...
to
...
be
...
optional)
...
if
...
preamble
...
is
...
detected,
...
gateway
...
mutes
...
audio
...
path
...
in
...
both
...
directions
...
(generating
...
silence
...
towards
...
both
...
endpoints).
...
gateway
...
waits
...
one
...
second,
...
then
...
constructs
...
T.38
...
negotiation
...
request
...
as
...
a
...
control
...
frame,
...
using
...
parameters
...
previously
...
set
...
via
...
FAXOPT()
...
dialplan
...
function,
...
and
...
sends
...
control
...
frame
...
to
...
core
...
if
...
T.38
...
negotiation
...
fails
...
(times
...
out,
...
or
...
is
...
rejected),
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(thus
...
clearing
...
the
...
'mute'
...
state
...
in
...
both
...
directions)
...
if
...
T.38
...
negotiation
...
succeeds
...
(request
...
is
...
accepted),
...
gateway
...
constructs
...
T.38
...
session
...
in
...
FAX
...
stack,
...
feeds
...
it
...
negotiated
...
parameters,
...
and
...
starts
...
session;
...
if
...
this
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
and
...
reports
...
appropriate
...
errors
...
while
...
T.38
...
session
...
is
...
active,
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
calling
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack;
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
calling
...
endpoint.
...
gateway
...
also
...
receives
...
audio
...
frames
...
from
...
called
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack,
...
and
...
receives
...
audio
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
called
...
endpoint
...
when
...
T.38
...
session
...
is
...
complete,
...
gateway
...
sends
...
T.38
...
negotiation
...
request
...
to
...
revert
...
to
...
audio
...
mode
...
if
...
audio
...
mode
...
reversion
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
if
...
audio
...
mode
...
reversion
...
succeeds,
...
gateway
...
removes
...
itself
...
from
...
audio
...
path
Use case 2:
| No Format |
|---|
(A) Calling T.38 endpoint <-->
(B) Channel Driver 1 <-->
(C) Asterisk Core <-->
(D) T.38 Gateway Object <-->
(E) Channel Driver 2 <-->
(F) Called T.30 endpoint
{noformat}
{ |
| Wiki Markup |
|---|
{graphviz} digraph G { "Calling T.38 Endpoint" -> "Channel Driver 1"; "Channel Driver 1" -> "Calling T.38 Endpoint"; subgraph cluster_1 { style=filled; label = "Asterisk"; "Channel Driver 1" -> "Asterisk Core"; "Asterisk Core" -> "Channel Driver 1"; "Asterisk Core" -> "T.38 Gateway Object"; "T.38 Gateway Object" -> "Asterisk Core"; "T.38 Gateway Object" -> "Channel Driver 2"; "Channel Driver 2" -> "T.38 Gateway Object"; } "Channel Driver 2" -> "Called T.30 Endpoint"; "Called T.30 Endpoint" -> "Channel Driver 2"; } {graphviz} |
In
...
this
...
use
...
case,
...
the
...
calling
...
endpoint
...
is
...
T.38
...
equipped
...
and
...
the
...
called
...
endpoint
...
is
...
not
...
(supports
...
T.30
...
only);
...
in
...
addition,
...
the
...
calling
...
endpoint
...
is
...
improperly
...
configured
...
to
...
initiate
...
T.38
...
re-INVITEs
...
itself,
...
not
...
waiting
...
for
...
the
...
receiving
...
gateway
...
to
...
do
...
so.
...
during
...
call
...
setup,
...
called
...
endpoint
...
is
...
ringing,
...
gateway
...
does
...
nothing
...
when
...
called
...
endpoint
...
has
...
answered,
...
gateway
...
listens
...
for
...
FAX
...
preamble
...
(using
...
V.21
...
detector)
...
generated
...
by
...
called
...
endpoint
...
if
...
preamble
...
is
...
not
...
detected
...
after
...
15
...
seconds
...
from
...
call
...
answer,
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(this
...
may
...
need
...
to
...
be
...
optional)
...
if
...
preamble
...
is
...
detected,
...
gateway
...
mutes
...
audio
...
path
...
in
...
both
...
directions
...
(generating
...
silence
...
towards
...
both
...
endpoints).
...
gateway
...
waits
...
one
...
second,
...
and
...
during
...
this
...
time
...
a
...
T.38
...
negotiation
...
request
...
is
...
received
...
from
...
the
...
calling
...
endpoint;
...
gateway
...
processes
...
this
...
request
...
using
...
parameters
...
previously
...
set
...
using
...
FAXOPT()
...
dialplan
...
function
...
if
...
the
...
T.38
...
negotiation
...
request
...
cannot
...
be
...
accepted,
...
gateway
...
sends
...
a
...
T.38
...
negotiation
...
failure
...
response,
...
and
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(thus
...
clearing
...
the
...
'mute'
...
state
...
in
...
both
...
directions)
...
if
...
T.38
...
negotiation
...
succeeds
...
(request
...
can
...
be
...
accepted),
...
gateway
...
sends
...
a
...
T.38
...
negotiation
...
success
...
response,
...
constructs
...
T.38
...
session
...
in
...
FAX
...
stack,
...
feeds
...
it
...
negotiated
...
parameters,
...
and
...
starts
...
session;
...
if
...
this
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
and
...
reports
...
appropriate
...
errors
...
while
...
T.38
...
session
...
is
...
active,
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
calling
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack;
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
calling
...
endpoint.
...
gateway
...
also
...
receives
...
audio
...
frames
...
from
...
called
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack,
...
and
...
receives
...
audio
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
called
...
endpoint
...
when
...
T.38
...
session
...
is
...
complete,
...
gateway
...
sends
...
T.38
...
negotiation
...
request
...
to
...
revert
...
to
...
audio
...
mode
...
(this
...
may
...
be
...
received
...
from
...
calling
...
endpoint
...
first,
...
though)
...
if
...
audio
...
mode
...
reversion
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
if
...
audio
...
mode
...
reversion
...
succeeds,
...
gateway
...
removes
...
itself
...
from
...
audio
...
path
...
Use
...
case
...
3:
...
| No Format |
|---|
(A) Calling T.30 endpoint <-->
(B) Channel Driver 1 <-->
(C) Asterisk Core <-->
(D) T.38 Gateway Object <-->
(E) Channel Driver 2 <-->
(F) Called T.38 endpoint
{noformat}
{ |
| Wiki Markup |
|---|
{graphviz} digraph G { "Calling T.30 Endpoint" -> "Channel Driver 1"; "Channel Driver 1" -> "Calling T.30 Endpoint"; subgraph cluster_1 { style=filled; label = "Asterisk"; "Channel Driver 1" -> "Asterisk Core"; "Asterisk Core" -> "Channel Driver 1"; "Asterisk Core" -> "T.38 Gateway Object"; "T.38 Gateway Object" -> "Asterisk Core"; "T.38 Gateway Object" -> "Channel Driver 2"; "Channel Driver 2" -> "T.38 Gateway Object"; } "Channel Driver 2" -> "Called T.38 Endpoint"; "Called T.38 Endpoint" -> "Channel Driver 2"; } {graphviz} |
In
...
this
...
use
...
case,
...
the
...
calling
...
endpoint
...
is
...
not
...
T.38
...
equipped
...
but
...
the
...
called
...
endpoint
...
is.
...
In
...
addition,
...
the
...
called
...
endpoint
...
is
...
improperly
...
configured
...
to
...
rely
...
on
...
the
...
calling
...
endpoint
...
to
...
initiate
...
T.38
...
re-INVITEs.
...
during
...
call
...
setup,
...
called
...
endpoint
...
is
...
ringing,
...
gateway
...
does
...
nothing
...
when
...
called
...
endpoint
...
has
...
answered,
...
gateway
...
listens
...
for
...
FAX
...
preamble
...
(using
...
V.21
...
detector)
...
generated
...
by
...
called
...
endpoint
...
if
...
preamble
...
is
...
not
...
detected
...
after
...
15
...
seconds
...
from
...
call
...
answer,
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(this
...
may
...
need
...
to
...
be
...
optional)
...
if
...
preamble
...
is
...
detected,
...
gateway
...
mutes
...
audio
...
path
...
in
...
both
...
directions
...
(generating
...
silence
...
towards
...
both
...
endpoints).
...
gateway
...
waits
...
one
...
second,
...
then
...
constructs
...
T.38
...
negotiation
...
request
...
as
...
a
...
control
...
frame,
...
using
...
parameters
...
previously
...
set
...
via
...
FAXOPT()
...
dialplan
...
function,
...
and
...
sends
...
control
...
frame
...
to
...
called
...
endpoint
...
if
...
T.38
...
negotiation
...
fails
...
(times
...
out,
...
or
...
is
...
rejected),
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(thus
...
clearing
...
the
...
'mute'
...
state
...
in
...
both
...
directions)
...
if
...
T.38
...
negotiation
...
succeeds
...
(request
...
is
...
accepted),
...
gateway
...
constructs
...
T.38
...
session
...
in
...
FAX
...
stack,
...
feeds
...
it
...
negotiated
...
parameters,
...
and
...
starts
...
session;
...
if
...
this
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
and
...
reports
...
appropriate
...
errors
...
while
...
T.38
...
session
...
is
...
active,
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
called
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack;
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
called
...
endpoint.
...
gateway
...
also
...
receives
...
audio
...
frames
...
from
...
calling
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack,
...
and
...
receives
...
audio
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
calling
...
endpoint
...
when
...
T.38
...
session
...
is
...
complete,
...
gateway
...
sends
...
T.38
...
negotiation
...
request
...
to
...
revert
...
to
...
audio
...
mode
...
if
...
audio
...
mode
...
reversion
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
if
...
audio
...
mode
...
reversion
...
succeeds,
...
gateway
...
removes
...
itself
...
from
...
audio
...
path
Use case 4:
| No Format |
|---|
(A) Calling T.30 endpoint <-->
(B) Channel Driver 1 <-->
(C) Asterisk Core <-->
(D) T.38 Gateway Object <-->
(E) Channel Driver 2 <-->
(F) Called T.38 endpoint
{noformat}
{ |
| Wiki Markup |
|---|
{graphviz} digraph G { "Calling T.30 Endpoint" -> "Channel Driver 1"; "Channel Driver 1" -> "Calling T.30 Endpoint"; subgraph cluster_1 { style=filled; label = "Asterisk"; "Channel Driver 1" -> "Asterisk Core"; "Asterisk Core" -> "Channel Driver 1"; "Asterisk Core" -> "T.38 Gateway Object"; "T.38 Gateway Object" -> "Asterisk Core"; "T.38 Gateway Object" -> "Channel Driver 2"; "Channel Driver 2" -> "T.38 Gateway Object"; } "Channel Driver 2" -> "Called T.38 Endpoint"; "Called T.38 Endpoint" -> "Channel Driver 2"; } {graphviz} |
In
...
this
...
use
...
case,
...
the
...
calling
...
endpoint
...
is
...
not
...
T.38
...
equipped
...
but
...
the
...
called
...
endpoint
...
is.
...
In
...
addition,
...
the
...
called
...
endpoint
...
is
...
properly
...
configured
...
to
...
initiate
...
T.38
...
re-INVITEs
...
itself.
...
during
...
call
...
setup,
...
called
...
endpoint
...
is
...
ringing,
...
gateway
...
does
...
nothing
...
when
...
called
...
endpoint
...
has
...
answered,
...
gateway
...
listens
...
for
...
FAX
...
preamble
...
(using
...
V.21
...
detector)
...
generated
...
by
...
called
...
endpoint
...
if
...
preamble
...
is
...
not
...
detected
...
after
...
15
...
seconds
...
from
...
call
...
answer,
...
gateway
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(this
...
may
...
need
...
to
...
be
...
optional)
...
if
...
preamble
...
is
...
detected,
...
gateway
...
mutes
...
audio
...
path
...
in
...
both
...
directions
...
(generating
...
silence
...
towards
...
both
...
endpoints).
...
gateway
...
waits
...
one
...
second,
...
and
...
during
...
this
...
time
...
a
...
T.38
...
negotiation
...
request
...
is
...
received
...
from
...
the
...
called
...
endpoint;
...
gateway
...
processes
...
this
...
request
...
using
...
parameters
...
previously
...
set
...
using
...
FAXOPT()
...
dialplan
...
function
...
if
...
the
...
T.38
...
negotiation
...
request
...
cannot
...
be
...
accepted,
...
gateway
...
sends
...
a
...
T.38
...
negotiation
...
failure
...
response,
...
and
...
removes
...
itself
...
from
...
the
...
audio
...
path
...
(thus
...
clearing
...
the
...
'mute'
...
state
...
in
...
both
...
directions)
...
if
...
T.38
...
negotiation
...
succeeds
...
(request
...
can
...
be
...
accepted),
...
gateway
...
sends
...
a
...
T.38
...
negotiation
...
success
...
response,
...
constructs
...
T.38
...
session
...
in
...
FAX
...
stack,
...
feeds
...
it
...
negotiated
...
parameters,
...
and
...
starts
...
session;
...
if
...
this
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
and
...
reports
...
appropriate
...
errors
...
while
...
T.38
...
session
...
is
...
active,
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
called
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack;
...
gateway
...
receives
...
T.38
...
media
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
called
...
endpoint.
...
gateway
...
also
...
receives
...
audio
...
frames
...
from
...
calling
...
endpoint
...
and
...
passes
...
them
...
to
...
FAX
...
stack,
...
and
...
receives
...
audio
...
frames
...
from
...
FAX
...
stack
...
and
...
sends
...
them
...
to
...
calling
...
endpoint
...
when
...
T.38
...
session
...
is
...
complete,
...
gateway
...
sends
...
T.38
...
negotiation
...
request
...
to
...
revert
...
to
...
audio
...
mode
...
if
...
audio
...
mode
...
reversion
...
fails,
...
gateway
...
causes
...
channel(s)
...
to
...
be
...
hung
...
up
...
if
...
audio
...
mode
...
reversion
...
succeeds,
...
gateway
...
removes
...
itself
...
from
...
audio
...
path