[hylafax-users] T.38 and Open Source?

[eric machine]

Hi everyone,

I think when comes to T.38, it seems have to use either brooktrout sr140 or tr1034 to make this work. And it seems HylaFax Enterprise can do this.

Few questions:-

1. How about the open source version?

There's seems to have 2 breeds here.

1 is hylafax (original) open source and other hylafax+.

Can these also support T.38 with or without brooktrout sr140?

2. I read the dialogic brooktrout t.30 vs t.38. I could understand the benefits.

How about you guys? Do I really use T.38? Do you really care about this?

Can E1 or T1 do T.38? Or any analog telephone lines can do T.38?

The way I see T.38 as it happens between the fax gateway <--> fax server. So any lines can work right?

Any help? Thanks.

[shouldbe q931]

On Fri, Mar 1, 2013 at 3:27 AM, eric machine <eric.m...@hotmail.com> wrote:
> Hi everyone,
>
> I think when comes to T.38, it seems have to use either brooktrout sr140 or
> tr1034 to make this work. And it seems HylaFax Enterprise can do this.
>
> Few questions:-
>
> 1. How about the open source version?

There is no open source support for Brooktrout, I would suggest that
you had a look at the Brooktrout licensing for more information.

> There's seems to have 2 breeds here.
>
> 1 is hylafax (original) open source and other hylafax+.
>
> Can these also support T.38 with or without brooktrout sr140?

Not native within Hylafax , but there are methods to do T.38 without
Brooktrout such as T38modem

You might also investigate the Dialogic Diva Server "SoftIP"
http://www.dialogic.com/en/products/media/diva/diva-softip.aspx
however I have no experience with it.

In my experience, nothing beats an ISDN or analogue line for fax

With T.38 you are always dependent on a 3rd party for interaction with
the PSTN, this always makes fault finding more complex.

> 2. I read the dialogic brooktrout t.30 vs t.38. I could understand the
> benefits.
>
> How about you guys? Do I really use T.38? Do you really care about this?

I don't use or recommend T.38, unless its a pure T.38 environment
(where faxes are only sent to other T.38 endpoints), but in that
situation, why bother with fax at all...

> Can E1 or T1 do T.38? Or any analog telephone lines can do T.38?

No, T.38 is an IP protocol. You can use analogue modems to send IP
over analogue lines (remember dial up Internet ?), or ISDN terminal
adapters to send IP over ISDN lines, or routers to send IP over PPP
over T1/E1 lines, but there is no native support for IP on them

> The way I see T.38 as it happens between the fax gateway <--> fax server. So
> any lines can work right?

T.38 happens between T.38 endpoints, these could be fax gateways that
convert between analogue fax (T.30) and T.38, or a "pure" T.38
endpoint

Have you read the wikipedia article ? http://en.wikipedia.org/wiki/T.38


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[Lee Howard]

On 02/28/2013 07:27 PM, eric machine wrote:
> Can these also support T.38 with or without brooktrout sr140?

Yes.

https://sourceforge.net/projects/t38modem/

Thanks,

Lee.

[eric machine]

Thanks everyone for replying back. Few more questions to go.

a. How does one integrate the open source T.38 into HylaFax Open Source?

b. I thought T.38 is real time faxing, so it is more efficient to use T.38 over T.30? Hmm.. is my understanding wrong? Plus I read the Dialogic document talking about T.30 not being stable enough? something like that.

Any help? Thanks.

> Date: Fri, 1 Mar 2013 22:17:23 -0800
> From: fax...@howardsilvan.com
> To: eric.m...@hotmail.com
> CC: hylafa...@hylafax.org
> Subject: Re: [hylafax-users] T.38 and Open Source?

[Lee Howard]

On 03/02/2013 08:19 AM, eric machine wrote:
> Thanks everyone for replying back. Few more questions to go.
>
> a. How does one integrate the open source T.38 into HylaFax Open Source?

The T.38 is run by t38modem and isn't directly tied to HylaFAX. So
t38modem emulates a modem using T.38. HylaFAX doesn't need the
knowledge that the call was handled with T.38.

> b. I thought T.38 is real time faxing, so it is more efficient to use
> T.38 over T.30? Hmm.. is my understanding wrong? Plus I read the
> Dialogic document talking about T.30 not being stable enough?
> something like that.

I've not enough experience with T.38 to comment with respect to its
efficiency. But I would suggest that one should consider bias whenever
interpreting information provided by an organization that has something
to gain from your interpretation of the information. T.30 is stable, and
T.38 cannot possibly be "more stable" than T.30 since T.38 follows (or
emulates) T.30.

The information that you're seeing *probably* is referring to fax over
VoIP (and calling that T.30) as compared to FoIP (T.38). And, sure, in
that scenario I guess one could reasonably argue that T.38 is better.
But that's a silly comparison, anyway, since nobody should fax over VoIP
in the first place. The real comparison should be between T.38 and T.30
over PSTN... and I assure you that T.30 over PSTN will always be
more-reliable than T.38.

[Darren Nickerson]

On Mar 2, 2013, at 11:19 AM, eric machine <eric.m...@hotmail.com> wrote:

> Thanks everyone for replying back. Few more questions to go.
>
> a. How does one integrate the open source T.38 into HylaFax Open Source?

I don't think anyone here is likely to product a detailed how-to guide for you, and I'm not aware that one exists. People have done it in a variety of ways, with varying levels of success, and many people feel that T.38 is not the right solution to the problem of faxing over converged data/voice networks. In the end, you must decide.

I actually believe your question has been asked and answered, the answer was to look into:

http://sourceforge.net/projects/t38modem/

Open Source is free, but that doesn't mean you can rely on free continuous assistance from your fellow Open Source users. You are loosely expected to give as much as you receive, which means you should become an active participant of any community before you begin to draw on it for intensive technical assistance on any one topic.

> b. I thought T.38 is real time faxing, so it is more efficient to use T.38 over T.30? Hmm.. is my understanding wrong? Plus I read the Dialogic document talking about T.30 not being stable enough? something like that.

You're probably referencing:

http://www.dialogic.com/~/media/products/docs/whitepapers/12687-t38-g711-foip-wp.pdf

I believe this is a relatively fair, thorough and for the most part academic and vendor neutral treatment of the discussion, but as Lee has pointed out, you should read this critically bearing in mind there may be vendor bias in the information presented.

I recommend you also review:

http://www.soft-switch.org/foip.html

-Darren

[shouldbe q931]

Just to add to Darren and Lee

Comparing T.38 to T.30 on G711 is _not_ the same as comparing T.38 to
T.30 on PSTN. With T.30 on PSTN, you have a direct "path" to the other
device, with T.38, you still need a PSTN gateway somewhere in the
path, a gateway that you probably don't manage, and you probably don't
have any control over call routing.

If you are somewhere with very high latency, such as if all of your
traffic transits a geostationary satellite, then you would want T.37,
but this is effectively fax over email, at which point, you might as
well just use email....

If you want to go down the T.38 route, you might take a look a
FreeSWITCH, the fax implementation is not as mature or feature rich as
HylaFAX, but people do seem to be able to get it working, with the
usual platform independent issues that T.38 has.

Cheers

Arne

[Lee Howard]

On 03/04/2013 04:36 PM, eric machine wrote:
> 1)
> *T.38 and T.30
> over PSTN...*
> When you say T.30 or T.38 over PSTN... are these considered as
> directly over PSTN?

I don't say "T.38 over PSTN" as there is no such thing. T.38 is over
IP. IP != PSTN

> HylaFax server <---> LAN <----> Fax Gateway (AudioCodes) <---> ISDN
> PRI/E1 <----> PSTN <----> traditional fax machine
>
> and this
>
> HylaFax server <---> LAN <----> Avaya CM (or Avaya Gateway) <---> ISDN
> PRI/E1 <----> PSTN <----> traditional fax machine

Any time you do: HylaFAX <---> LAN then you're either talking about
VoIP or T.38 not PSTN... despite the fact that downstream the call is
gatewayed to the PSTN.

> Or the above are referring to "T.38 to T.30 on G711" or "T.38 to T.30
> over VOIP"?
>
> I just want to confirm this fact.

I don't understand the question. However, I suspect that you're
referring to "T.30" as synonymous with "audio-driven fax". So the call
paths that you describe above are either T.38 or are "audio driven fax"
over VoIP. Neither are fully PSTN.

> 2)
>
> If point 1 is correct as in "T.30 over PSTN", example
>
> HylaFax server <---> LAN <----> Fax Gateway (AudioCodes) <---> ISDN
> PRI/E1 <----> PSTN <----> traditional fax machine

This is not "over PSTN". The LAN connection there between HylaFAX and
the gateway implies that there is either VoIP or T.38... neither of
which are PSTN.

> So for HylaFax server, it doesn't need any T.38 modem built-in (eg.
> open source T.38 or Dialogic Brooktrout SR14) to have T.30 working.

Well, I wouldn't recommend that call path at all. But if you had to do
it, then I guess T.38 would be the only hope to have anything resembling
reliable and reproducible.

> And do I still need a Fax gateway (like AudioCodes)? I want to have
> something like FOIP to work. Or Fax Gateway will not work for T.30?
> Have to use traditional Fax Boards attached to the server manually?

I have no idea about your proposed fax gateway as I don't use them.

> 3)
>
> Lastly, when you say this
> *and I assure you that T.30 over PSTN will always be
> more-reliable than T.38.*
> I assume T.30 over PSTN is better as T.38 over PSTN, basically because
> T.38 software emulates, it means it create additional overhead? Is
> that what it actually meant? Just to double confirm.

There have been plenty of pointers throughout the e-mails over the last
few days that will help you understand what fax is and what T.38 is and
why T.38 cannot exceed the reliability of fax (T.30) over the PSTN. It
can emulate it; it can come close to it; but it can never be better than it.

The biggest issue with T.38 appears to be compatibility between
endpoints and gateways. There are some technical hurdles - for example
the inevitable switch from G.711 (or whatever audio codec is used) to
T.38 in a call can be troublesome. But almost always T.38 is still
going to run on UDP/IP, which means that if you have a lot of packet
loss on the connection that data can still get lost even though T.38 may
be retransmitting packets in quadruple.

But... I'm not a T.38 expert. I evaluated T.38 several years ago to see
if it was something that I could utilize. But the reliability that I
needed was just not reproducible with any degree of certainty without
spending a lot of money on equipment that locked-away the protocol from
my ability to analyze or improve. I enjoy the control over the protocol
that using a T.38 gateway cannot afford me. So I stayed with fax over
PSTN, and I think that it's been good for my customers.

Thanks,

Lee.

[Lee Howard]

On 03/05/2013 03:59 PM, eric machine wrote:
> Hi Lee,
>
> Just to double confirm on this

>
> I don't say "T.38 over PSTN" as there is no such thing. T.38 is over
> IP. IP != PSTN

> So basically for T.30 over PSTN, do you mean by this?
>
> HylaFax Server has built-in fax card <-> ISDN PRI/E1 connected
> directly <--> PSTN
>
> and
>
> HylaFax Server has built-in fax card <--> Analog Phone Lines connected
> directly <--> PSTN
>
> Is that what you meant?

Yes.

> Any help to confirm?
>
> If the above is possible and reliable, then there's no point buying a
> voice/fax gateway.

Correct.

> But I am wondering how much is a fax card (plugged into the server)?

Look up the prices...

Analog... Mainpine, Multitech.

T1/E1... use Asterisk+IAXmodem with some DAHDI-compatible hardware. If
you really wanted to get crazy you could try CallWeaver or FreeSWITCH
instead of Asterisk.

> Are there any affordable ones which can work in Linux (as HylaFax has
> to be installed in linux)? Any recommendation on brands?

OpenVOX boards (DAHDI-compatible) are fairly inexpensive. But given the
nature of our conversations thus far I worry that dumping Asterisk onto
your learning-curve will prove to be very difficult.

[shouldbe q931]

On Wed, Mar 6, 2013 at 12:11 AM, Lee Howard <fax...@howardsilvan.com> wrote:
> On 03/05/2013 03:59 PM, eric machine wrote:
>>
>
>> But I am wondering how much is a fax card (plugged into the server)?
>
>
> Look up the prices...
>
> Analog... Mainpine, Multitech.
>
> T1/E1... use Asterisk+IAXmodem with some DAHDI-compatible hardware. If you
> really wanted to get crazy you could try CallWeaver or FreeSWITCH instead of
> Asterisk.
>

For BRI/PRI I like the Dialogic Diva Server cards, IMHO its a
"simpler" solution that adding asterisk to the mix.

Cheers

Arne

[eric machine]

Hi Lee,

Just to double confirm on this

I don't say "T.38 over PSTN" as there is no such thing. T.38 is over

IP. IP != PSTNSo basically for T.30 over PSTN, do you mean by this?

HylaFax Server has built-in fax card <-> ISDN PRI/E1 connected directly <--> PSTN

and

HylaFax Server has built-in fax card <--> Analog Phone Lines connected directly <--> PSTN

Is that what you meant?

Any help to confirm?

If the above is possible and reliable, then there's no point buying a voice/fax gateway. But I am wondering how much is a fax card (plugged into the server)? Are there any affordable ones which can work in Linux (as HylaFax has to be installed in linux)? Any recommendation on brands?

Thanks.

> Date: Tue, 5 Mar 2013 11:14:19 -0800

> From: fax...@howardsilvan.com
> To: eric.m...@hotmail.com
> CC: hylafa...@hylafax.org
> Subject: Re: [hylafax-users] T.38 and Open Source?
>

> On 03/04/2013 04:36 PM, eric machine wrote:
> > 1)
> > *T.38 and T.30
> > over PSTN...*
> > When you say T.30 or T.38 over PSTN... are these considered as
> > directly over PSTN?
>

> I don't say "T.38 over PSTN" as there is no such thing. T.38 is over
> IP. IP != PSTN
>