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[asterisk-users] Asterisk 1.4 Fax

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rob at hillis.dyndns.org
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PostPosted: Tue Jan 01, 2008 5:12 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

I'd say "consider yourself very lucky". I know I did some testing here
some time ago with faxing over VoIP.

* One extension to another over G711a with both extensions on the
same LAN - worked 95% of the time
* One extension on my Asterisk server to an Extension on a friend's
Asterisk server using G711a via IAX - 95% failure rate. Both of
us awere on the same ISP and had ping times of ~40ms between us.

However, in a live environment, I convert a PSTN call to a t.38 encoded
call and can send the fax just about anywhere I damn well want (where
the remote end supports t.3Cool with a 95% success rate.

t.38 is the key to successful faxing over a VoIP network. Without it,
you're begging for trouble.
Doug Lytle wrote:
Quote:
Jonn R Taylor wrote:

Quote:
If I had ANY failed faxes I would here about it. Iaxmodem creates a log of its own, so when I get a connection that fails hylafax sends the failure to me. One of the things that I found is you need to add nojitterbuffer to the iaxmodem config file,


Really? I'll have to do some testing, I've never tried since I've read
you can't.

Doug



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jonnt at taylortelepho...
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PostPosted: Tue Jan 01, 2008 5:21 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

NOT true and I have proven that for the last year.



Jonn



_____

From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Rob Hillis
Sent: Tuesday, January 01, 2008 4:13 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] Asterisk 1.4 Fax



I'd say "consider yourself very lucky". I know I did some testing here some time ago with faxing over VoIP.

* One extension to another over G711a with both extensions on the same LAN - worked 95% of the time
* One extension on my Asterisk server to an Extension on a friend's Asterisk server using G711a via IAX - 95% failure rate. Both of us awere on the same ISP and had ping times of ~40ms between us.

However, in a live environment, I convert a PSTN call to a t.38 encoded call and can send the fax just about anywhere I damn well want (where the remote end supports t.3Cool with a 95% success rate.

t.38 is the key to successful faxing over a VoIP network. Without it, you're begging for trouble.
Doug Lytle wrote:

Jonn R Taylor wrote:


If I had ANY failed faxes I would here about it. Iaxmodem creates a log of its own, so when I get a connection that fails hylafax sends the failure to me. One of the things that I found is you need to add nojitterbuffer to the iaxmodem config file,



Really? I'll have to do some testing, I've never tried since I've read
you can't.

Doug





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support at drdos.info
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PostPosted: Tue Jan 01, 2008 5:42 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

Jonn R Taylor wrote:
Quote:
FYI... I love this.
Ben Franklin quote:

I truly believe it. But, it being a Franklin quote is in some dispute.
I like it all the same.

Doug

--
Ben Franklin quote:

"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."
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steveu at coppice.org
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PostPosted: Tue Jan 01, 2008 7:02 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

Jonn R Taylor wrote:
Quote:
I have always said that if some one said it can't be done, they did not try hard enough.

FYI... I love this.
Ben Franklin quote:

"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."

As the person behind the tools you are relying on, I can say you haven't
tried hard at all. You are just lucky, and almost certainly just being
very reliant on the majority of your FAXes using ECM mode, and retrying
a lot.

Trying hard for FAX over IP means implementing T.37, or at least T.38.
These are engineered solutions, not pot luck. Your present arrangement
assumes G.711 (not available a lot of the time), no signal manipulation
in the system beyond your controls (getting rarer and rarer), a very
crude network doing nothing to improve voice quality (should be getting
rarer too), limited packet loss (which is truly pot luck over the
internet, which you say you use), and a few other magic qualities.

A number of people claim solid FAXing results across VoIP paths, like
they've achieved some engineering breakthrough. The claims tend to
evaporate under closer inspection.

Steve
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asteriskal at gmail.com
Guest





PostPosted: Tue Jan 01, 2008 7:28 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

Guys!
what i was looking here was a simple hint/recommendation for installing
IaxModem and Hylafax.
Let me try it myself and see how feasible this solutions is.
On Jan 1, 2008 5:02 PM, Steve Underwood <steveu at coppice.org> wrote:

Quote:
Jonn R Taylor wrote:
Quote:
I have always said that if some one said it can't be done, they did not
try hard enough.
Quote:

FYI... I love this.
Ben Franklin quote:

"Those who would give up Essential Liberty to purchase a little
Temporary Safety, deserve neither Liberty nor Safety."
As the person behind the tools you are relying on, I can say you haven't
tried hard at all. You are just lucky, and almost certainly just being
very reliant on the majority of your FAXes using ECM mode, and retrying
a lot.

Trying hard for FAX over IP means implementing T.37, or at least T.38.
These are engineered solutions, not pot luck. Your present arrangement
assumes G.711 (not available a lot of the time), no signal manipulation
in the system beyond your controls (getting rarer and rarer), a very
crude network doing nothing to improve voice quality (should be getting
rarer too), limited packet loss (which is truly pot luck over the
internet, which you say you use), and a few other magic qualities.

A number of people claim solid FAXing results across VoIP paths, like
they've achieved some engineering breakthrough. The claims tend to
evaporate under closer inspection.

Steve


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jonnt at taylortelepho...
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PostPosted: Tue Jan 01, 2008 7:39 pm    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

Steve,

One of the main reasons that this works is controlling the data to and from the internet. I have spent the last 10 years building networks for ISP's. The key is getting the data from point a to point b in tact and in order.

I did not get "lucky" as you put it. I am a network engineer and I know how to make networks work the way they need to.

Jonn

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Steve Underwood
Sent: Tuesday, January 01, 2008 6:02 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] Asterisk 1.4 Fax

Jonn R Taylor wrote:
Quote:
I have always said that if some one said it can't be done, they did not try hard enough.

FYI... I love this.
Ben Franklin quote:

"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."

As the person behind the tools you are relying on, I can say you haven't
tried hard at all. You are just lucky, and almost certainly just being
very reliant on the majority of your FAXes using ECM mode, and retrying
a lot.

Trying hard for FAX over IP means implementing T.37, or at least T.38.
These are engineered solutions, not pot luck. Your present arrangement
assumes G.711 (not available a lot of the time), no signal manipulation
in the system beyond your controls (getting rarer and rarer), a very
crude network doing nothing to improve voice quality (should be getting
rarer too), limited packet loss (which is truly pot luck over the
internet, which you say you use), and a few other magic qualities.

A number of people claim solid FAXing results across VoIP paths, like
they've achieved some engineering breakthrough. The claims tend to
evaporate under closer inspection.

Steve
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To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
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rob at hillis.dyndns.org
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PostPosted: Wed Jan 02, 2008 12:53 am    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

I think perhaps you are the exception rather than the rule.

Maybe you were able to engineer your network so that fax works without
any of the FoIP protocols - good luck to you if you have. For /most/
people, it's unlikely they would have sufficient control over their WAN
segment to ensure that it is sufficiently fast and reliable enough for
fax to work reliably.

In any case, why on earth would you attempt to re-invent the wheel?
T.38 is not only considerably more reliable and robust, it's nowhere
/near/ as bandwidth intensive as G711.

The original question was regarding using IAXmodem and Hylafax to
receive faxes over a SIP connection. Given that T.38 can not work in
this situation, the simple answer is that it /isn't/ the best solution.
Jonn R Taylor wrote:
Quote:

NOT true and I have proven that for the last year.



Jonn



------------------------------------------------------------------------

*From:* asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] *On Behalf Of *Rob Hillis
*Sent:* Tuesday, January 01, 2008 4:13 PM
*To:* Asterisk Users Mailing List - Non-Commercial Discussion
*Subject:* Re: [asterisk-users] Asterisk 1.4 Fax



I'd say "consider yourself very lucky". I know I did some testing
here some time ago with faxing over VoIP.

* One extension to another over G711a with both extensions on the
same LAN - worked 95% of the time
* One extension on my Asterisk server to an Extension on a
friend's Asterisk server using G711a via IAX - 95% failure
rate. Both of us awere on the same ISP and had ping times of
~40ms between us.

However, in a live environment, I convert a PSTN call to a t.38
encoded call and can send the fax just about anywhere I damn well want
(where the remote end supports t.3Cool with a 95% success rate.

t.38 is the key to successful faxing over a VoIP network. Without it,
you're begging for trouble.


Doug Lytle wrote:

Jonn R Taylor wrote:

Quote:
If I had ANY failed faxes I would here about it. Iaxmodem creates a log of its own, so when I get a connection that fails hylafax sends the failure to me. One of the things that I found is you need to add nojitterbuffer to the iaxmodem config file,


Really? I'll have to do some testing, I've never tried since I've read
you can't.

Doug



------------------------------------------------------------------------

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norman at myasd.com
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PostPosted: Wed Jan 02, 2008 11:05 am    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

On Jan 1, 2008, at 1:00 PM, asterisk-users-request at lists.digium.com
wrote:

Quote:
The most recent versions of t38modem can apparently provide both a SIP
and H.323 T.38 to class 1 FAX modem interface for HylaFAX. What it
cannot provide is an audio FAX interface. The sipmodem code I am
working
on will integrate audio and T.38 FAX processing in a single SIP
entity.
Apparently, indeed. I've been unable to get it to send faxes via a
Cisco gateway. (Receive is OK.) The other side always reports errors,
so it may or may not work for you.

Norman Franke
ASD, Inc.



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oza-4h07 at myamail.com
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PostPosted: Thu Jan 03, 2008 7:44 am    Post subject: [asterisk-users] Asterisk 1.4 Fax Reply with quote

Hello,

2008/1/1, Steve Underwood <steveu at coppice.org>:
Quote:

Hi Rob,

Rob Hillis wrote:
Quote:
Well that answers that question. I see that t38modem provides an H232
modem - is this unsuitable for HylaFAX's purpose? (ignoring the fact
that it requires a kernel recompile on most newer distros.)

Steve Underwood wrote:
Quote:
Rob Hillis wrote:

Quote:
Last time I heard IAXModem didn't support T.38 because the IAX2
protocol didn't support T.38 - whether that's still the case or not, I
don't know.

There are actually two reasons. One is that T.38 over IAX is not
defined. The other is the current T.38 termination support in spandsp
is
Quote:
Quote:
only for the full FAX machine it contains. T.38 termination to the
class
Quote:
Quote:
1 FAX modem (T.31) interface for HylaFAX is a work in progress. When
that is done, I hope we will have a sipmodem to replace iaxmodem,
offering bother audio and T.38 to HylaFAX functionality.

Steve


The most recent versions of t38modem can apparently provide both a SIP
and H.323 T.38 to class 1 FAX modem interface for HylaFAX. What it
cannot provide is an audio FAX interface.
What is an "audio FAX interface" ?
I'm not sure to understand what it is.

Cheers

Quote:
The sipmodem code I am working
on will integrate audio and T.38 FAX processing in a single SIP entity.

Steve


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