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[asterisk-users] FXO Cards - T38

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steveu at coppice.org
Guest

Posted: Sun Feb 24, 2008 4:22 am Post subject: [asterisk-users] FXO Cards - T38

Rob Hillis wrote:

Quote:

T.38 is for all intents and purposes a codec. It's purpose is to
re-encode a fax transmission as a data stream to be re-assembled at
the other end as if it were a fax call. Seems to me to be pretty
close to the definition of a codec to me.

T.38 is not a simple re-encoder. It cannot work on a single stream,
independent of the related stream going in the opposite direction. This
is not what most people think of as a codec, and it doesn't fit into the
way codecs are handled in most platforms. This includes Asterisk, where
the two directions of codec processing are independent pipes.

Quote:

Your original comment was that you cannot use T.38 and G.729 in
Asterisk at the same time. On a technical level, this is /not/ true,
especially if the T.38 implementation does not rely on SpanDSP.
(whether or not such an implementation exists is another question)
Breaking license conditions is a separate issue altogether.

I was talking about the T.38 support which has been added to Asterisk
add-ons.

Quote:

You also appear to have answered another one of your questions on this
forum to someone else ("why on earth would you want to remove SpanDSP
as a dependency?") by telling us that you can't run G.729 at the same
time as T.38.

Again, this was with reference to the code which has been added to
Asterisk add-ons.

Quote:

I'm also curious as to why you assert that using G.729 in Asterisk
(/not/ ABE) at the same time as a T.38 implementation that relies on
SpanDSP since these are two completely separate plugins that are
installed and acquired separately. That's almost like asserting that
you can't run any commercial X application if you've installed my XYZ
web browser on the same machine. Just because they use a common
software base (X in this instance) /doesn't/ mean that you're
violating the GPL by running non commercial software on the same machine.

Try reading the GPL and the FSF's interpretation of it. If things are
running in the same address space as my code, they need to be GPL
compatible, or I am likely to take action. We have tackled this issue in
other ways, taking non-GPL code outside the address space of GPL code.
This can work well for things like G.729, as the compute in the codec is
so great it swamps the process to process communications overhead. It
creates a greater problem for things like ucLinux platforms (e.g.
Blackfin), as everything on the entire machine is in the same address
space.

Quote:

A more meaningful interpretation of the GPL would be that you either
can or can't run a T.38 implementation with Asterisk /full stop/.
Either the license is compatible, or it isn't. Trying to force any
other interpretation on people will end up with you being dismissed as
an extremist.

An extremist is someone who thinks they can do as they please, without
regard to the legitimate rights of others. In this case it appears to be
an accurate description of you.

I write code. I let people use it. I set reasonable, and widely
established rules for its use. I expect people to stick to them. I never
ask anyone to use my stuff. If you don't like my rules, Attractel
provides an alternative T.38 implementation, which is fully licence
compatible with Asterisk ABE and proprietary codecs.

Regards,
Steve

tzafrir.cohen at xorco...
Guest

Posted: Sun Feb 24, 2008 5:50 am Post subject: [asterisk-users] FXO Cards - T38

On Sun, Feb 24, 2008 at 08:25:15PM +1100, Rob Hillis wrote:

Quote:

Tzafrir Cohen wrote:

Quote:

They are not installed separately. They are modules loaded into the same
memory space.

Absolutely they are installed separately. G.729 is a product you
/purchase/ and the install onto your Asterisk server and load as a
completely separate module to app_fax. The fact that they are /written/
by the same company is irrelevant.

Quote:

That's almost like asserting that
you can't run any commercial X application if you've installed my XYZ
web browser on the same machine. Just because they use a common
software base (X in this instance) /doesn't/ mean that you're violating
the GPL by running non commercial software on the same machine.

Those are two separate processes. Completely separate from one another.
This is a common misunderstanding of the GPL (or of the application of
copyrights laws to computer software).

Perhaps not the best example. Perhaps a better example is the
/proprietary/ nvidia video driver used by a large number of people with
NVidia hardware - myself included. Granted, x.org is not released under
the GPL license, however assuming it was then by your logic you wouldn't
be able to use the nvidia driver.

As you mentioned, X.org is not GPL. There's no nVidia driver for, say,
Xvnc Smile

Quote:

To my mind, this is a ridiculous situation and needlessly limiting. It
goes from the ridiculous IP extremes of companies such as Microsoft to
the other end of the scale.

IP is the Internet Protocol. We're talking about copyrights here. Don't
try to bundle in completely different cencepts such as patents and
trademarks.

Quote:

I am yet to find /any/ situation where any
kind of extremism is a good thing. If the FSF starts trying to enforce
conditions such as these, they're going to look every bit as bad as the
companies such as Microsoft or Lexmark have in the past and do
themselves some significant damage.

Right. So why don't we all start using the g729/g723 code from
<imagine_URL_here>
? Is it OK for Cisco or Avaya to start merging parts of the Asterisk
source code into their products?

Maybe in a different world the coyright laws woulld be different and
hence copyleft would not be needed. Right now it is what we have.
Copyleft licenses (mostly the GNU GPL and the GNU LGPL) have played an
insturmental role in the generation of a large and solid pool of
software you can freely use and modify.

In addition, it is not the FSF folks that are "aggressivly forcing
licenses". The FSF has, for years, avoided such pulic actions and
preferred quiet settelments.

Sadly, this has not been good enough. As even reputable companies often
don't abide to the license under which they distribute their software.
And ignore requests to do so.

The developers of busybox tried before:
http://www.busybox.net/shame.html

But then again, those developers are a bunch of "Internet Protocol
extremists". They produce nothing useful.

--
Tzafrir Cohen
icq#16849755 jabber:tzafrir.cohen at xorcom.com
+972-50-7952406 mailto:tzafrir.cohen at xorcom.com
http://www.xorcom.com iax:guest at local.xorcom.com/tzafrir

digium at sanguinarius...
Guest

Posted: Sun Feb 24, 2008 5:56 am Post subject: [asterisk-users] FXO Cards - T38

Tzafrir Cohen wrote:

Quote:

On Sun, Feb 24, 2008 at 08:25:15PM +1100, Rob Hillis wrote:

Quote:

To my mind, this is a ridiculous situation and needlessly limiting. It
goes from the ridiculous IP extremes of companies such as Microsoft to
the other end of the scale.

IP is the Internet Protocol. We're talking about copyrights here. Don't
try to bundle in completely different cencepts such as patents and
trademarks.

Err, even I assumed he was referring to the Intellectual Property
extremes of companies such as Microsoft.

benny+usenet at amorse...
Guest

Posted: Sun Feb 24, 2008 7:13 am Post subject: [asterisk-users] FXO Cards - T38

Steve Underwood <steveu at coppice.org> writes:

Quote:

Try reading the GPL and the FSF's interpretation of it. If things are
running in the same address space as my code, they need to be GPL
compatible, or I am likely to take action.

The GPL is not an EULA. You don't have to agree to it to use the
software, only to distribute it.
/Benny

tzafrir.cohen at xorco...
Guest

Posted: Mon Feb 25, 2008 4:37 pm Post subject: [asterisk-users] FXO Cards - T38

On Mon, Feb 25, 2008 at 05:32:24PM -0300, Fernando Berretta wrote:

Quote:

Dear All,

Are you telling me Asterisk 1.6.0b2/4 has support for t38 and rxfax etc.
and will be able to receive faxes and negotiate with voip CPE's like
ATA's to transmit faxes which comes from FXO cards to VoIP Devices using
T38 ? it is possible to compile this version of app_fax to work with
Asterisk 1.4x ? Someone has tried it ?

You have rx_fax for 1.4 . You also have fax detection in chan_zap, and
thus can send faxes from the PSTN to rx_fax.

Not exactly the same, but maybe this is actually what you're looking
for.

--
Tzafrir Cohen
icq#16849755 jabber:tzafrir.cohen at xorcom.com
+972-50-7952406 mailto:tzafrir.cohen at xorcom.com
http://www.xorcom.com iax:guest at local.xorcom.com/tzafrir

zoachien at securax.org
Guest

Posted: Tue Feb 26, 2008 4:42 am Post subject: [asterisk-users] FXO Cards - T38

T.38 will not work with the fxo card.

Zoa

Fernando Berretta wrote:

Quote:

Dear All,

Are you telling me Asterisk 1.6.0b2/4 has support for t38 and rxfax
etc. and will be able to receive faxes and negotiate with voip CPE's
like ATA's to transmit faxes which comes from FXO cards to VoIP
Devices using T38 ? it is possible to compile this version of app_fax
to work with Asterisk 1.4x ? Someone has tried it ?

Best Regards,
Fernando

Thomas Kenyon wrote:

Quote:

Steve Underwood wrote:

Quote:

I thought * was still not capable for T.38 gateway operation. Doesn't
beta 4 just added T.38 termination? And, I believe it misses out some
key elements of doing that properly. Note that T.38 termination is an
addon, so it can't be used with, say, G.729.

Quote:

The only real option available at the moment is to keep one PSTN line on
an ATA with an FXO port and T.38 support available and direct calls from
the fax machines through to it. However, I should point out that while
I believe this should be possible, I haven't actually tried it myself.

The new asterisk T.38 functionality is from the Asterisk addons 1.6.0b2
version of app_fax (and a few small changes in 1.6.0b4), which I thought
someone would have mentioned to you, since it does use spandsp.

(Or at least the configure script checks for spandsp, I haven't actually
looked at the code).

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steveu at coppice.org
Guest

Posted: Tue Feb 26, 2008 7:28 am Post subject: [asterisk-users] FXO Cards - T38

zoa wrote:

Quote:

T.38 will not work with the fxo card.

Zoa

That statement is a bit vague. What has been put in add-ons so far is
only support for T.38 termination. Not T.38 gateway operation.

Steve

Quote:

Fernando Berretta wrote:

Quote:

Dear All,

Are you telling me Asterisk 1.6.0b2/4 has support for t38 and rxfax
etc. and will be able to receive faxes and negotiate with voip CPE's
like ATA's to transmit faxes which comes from FXO cards to VoIP
Devices using T38 ? it is possible to compile this version of app_fax
to work with Asterisk 1.4x ? Someone has tried it ?

Best Regards,
Fernando

Thomas Kenyon wrote:

Quote:

Steve Underwood wrote:

Quote:

steveu at coppice.org
Guest

Posted: Tue Feb 26, 2008 7:35 am Post subject: [asterisk-users] FXO Cards - T38

Benny Amorsen wrote:

Quote:

Steve Underwood <steveu at coppice.org> writes:

Quote:

Try reading the GPL and the FSF's interpretation of it. If things are
running in the same address space as my code, they need to be GPL
compatible, or I am likely to take action.

The GPL is not an EULA. You don't have to agree to it to use the
software, only to distribute it.

This is the key drawback of GPL 2 for my purposes. You can indeed do
whatever you want with my GPL code internally. Supply it to anyone as
something mingled with non-GPL compatible code, though, and you are in
violation of the licence. So, only in house use is OK.

Regards,
Steve

zoachien at securax.org
Guest

Posted: Tue Feb 26, 2008 8:13 am Post subject: [asterisk-users] FXO Cards - T38

Fernando Berretta wrote:

Quote:

Tzafir,

I'm sorry, my question wasn't clear.

Apparently Asterisk 1.6.0b2 and b4 has support for t38 because of some
modifications on app_fax so the questions are:

1 - If I use Asterisk 1.6.0b2 o b4 and a fax is received from a FXO
Card and this FXO port is forwarded to other ATA/Gateway is asterisk
going to transmit this fax using t38 ?
PSTN FAX MACHINE--------------------ASTERISK(1.6.0b2) FXO
CARD-------------------t38?------------------------ATA/Gateway---------FAX
MACHINE

No this is not going to work with the code you find in add-ons (Steve
Underwood was right, my last email was a bit vague).
The FAX -> ASTERISK -> t.38 part will not work.

2 - If the first answer is yes, if we compile app_fax with asterisk 1.4x
same behavior could be achieved ?

Quote:

Regards,
Fernando

Tzafrir Cohen wrote:

Quote:

On Mon, Feb 25, 2008 at 05:32:24PM -0300, Fernando Berretta wrote:

Quote:

You have rx_fax for 1.4 . You also have fax detection in chan_zap, and
thus can send faxes from the PSTN to rx_fax.

Not exactly the same, but maybe this is actually what you're looking
for.

fernando.berretta at g...
Guest

Posted: Tue Feb 26, 2008 9:07 am Post subject: [asterisk-users] FXO Cards - T38

Thanks for clarify.. so Asterisk will be able to receive faxes which
comes from a Gateway using t38 but will not be able to relay faxes which
comes from PSTN through a FXO card to other Gateway using t38

can this version of app_fax be used with Asterisk 1.4x ?
Steve Underwood wrote:

Quote:

zoa wrote:

Quote:

T.38 will not work with the fxo card.

Zoa

That statement is a bit vague. What has been put in add-ons so far is
only support for T.38 termination. Not T.38 gateway operation.

Steve

Quote:

Fernando Berretta wrote:

Quote:

Dear All,

Are you telling me Asterisk 1.6.0b2/4 has support for t38 and rxfax
etc. and will be able to receive faxes and negotiate with voip CPE's
like ATA's to transmit faxes which comes from FXO cards to VoIP
Devices using T38 ? it is possible to compile this version of app_fax
to work with Asterisk 1.4x ? Someone has tried it ?

Best Regards,
Fernando

Thomas Kenyon wrote:

Quote:

Steve Underwood wrote:

Quote:

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digium at sanguinarius...
Guest

Posted: Wed Feb 27, 2008 3:47 am Post subject: [asterisk-users] FXO Cards - T38

Fernando Berretta wrote:

Quote:

Tzafir,

I'm sorry, my question wasn't clear.

Apparently Asterisk 1.6.0b2 and b4 has support for t38 because of some
modifications on app_fax so the questions are:

1 - If I use Asterisk 1.6.0b2 o b4 and a fax is received from a FXO Card
and this FXO port is forwarded to other ATA/Gateway is asterisk going to
transmit this fax using t38 ?

Excuse my ignorance, but don't ATAs generally only support T.38 Origination?

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