[asterisk-users] FAX Issues

[Ryan McGuire]

Unless your network is under load and you are seeing dropped packets
and high jitter, I would absolutely not do T.38. The cheapest and
easiest approach that I have found is to buy yourself an FXS gateway
and just make sure you are using ulaw.

Is this for personal use, or for business use? One feature that you
may want to utilize is fax tone detection if you only have a single
incoming line. If you use fax tone detection you can send the call
directly to your FXS gateway.

I've successfully faxed through my SIP provider as well as through an
FXO gateway going to a DOCSIS modem (consumer grade "digital voice").
TDM and POTS are really synonymous by the way, TDM is just a more
specific acronym (time-division multiplexing). You need not worry
about the details though, if you are simply doing inband passthrough
and you are using 711u on your VOIP legs you should be fine... YMMV of
course.

-Ryan

On Tue, Aug 9, 2011 at 6:00 PM, Steve Totaro
<stotaro at totarotechnologies.com> wrote:
> On Tue, Aug 9, 2011 at 5:21 PM, C F <shmaltz at gmail.com> wrote:
>> On Tue, Aug 9, 2011 at 3:38 PM, Sassy Natan <sassyn at gmail.com> wrote:
>>> Hi,
>>> I would like to make sure I got it right:
>>> 1. Asterisk 1.4 doesn't support FAX support. It do however works if u sent
>>> fax from the PSTN and have anther FAX machine answer to it even if it is
>>> behind asterisk. This works like any regular phone, and as far as I know
>>> this mode known as T.38 pass through.
>>
>> No its not T.38 pass through. T.38 pass through is only if the 2 end
>> points negotiated T.38, i.e. a provider that supports T.38 and an ATA
>> that supports T.38. What you are describing will most likely fail if
>> there is any VoIP in between, and should succeed over pure TDM using
>> digium or similar cards.
>
> Fax was never officially supported by Asterisk/Digium using TDM cards.
>
> I works for the most part, but there is no comparison to a pure POTS
> line.  Much depends on the line quality, the sending and receiving fax
> devices.  Some places with good fax machines, PRIs coming in and some
> FXS ports would work just fine.
>
> Others, are a nightmare and make you look bad.
>
> Depending on your customer's fax needs, sometimes it is better to tell
> them to keep or have some POTS lines provisioned for reliable faxing
> and to back that up, bring up being able to reach 911 if the phone
> system is down and the company's liability, even though everyone has
> cell phones.  This is the best for TDM faxing with nothing fancy.
>
> I have sent people to www.trustfax.com
>
> TDM faxing is something that burned me more than once, so I don't suggest it.
>
>>
>>> 2. If u want asterisk 1.4 to able to sent and receive emails you will have
>>> to patch the source code using the spandsp patches. There are some other
>>> ways to make this work like using  IAX, hylafax  but I need to know if this
>>> is true. This mode is what know to be as NVFAX detected
>>
>> asterisk doesn't have the ability to send or receive emails. It does
>> have the ability to use something like sendmail to send/receive
>> emails.
>> I'm assuming its a typo and you meant faxes.
>> What exactly are you trying to accomplish? If you need to know
>> something go ahead and try/test it and report back. After all that is
>> what we all did to be able to answer it. Apparently the fact that
>> others tried it and told you that it works still warrants a
>> question:"I need to know if this is true"
>>
>
> I have been advised that everyone must post their solutions to the
> list so that you don't have to test.  I think it was a self appointed
> list moderator.  People are required to come back, aknowledge that
> something worked and give credit.  Flaw: Just because something worked
> for someone doesn't mean that your solution wouldn't work better.
>
> Anyways, I am with you.  I learned this stuff with very little
> documentation except .conf examples and code.  Integration is where
> things get really fun and creative.  Logically testing and failing and
> testing until you find your solution is extremely rewarding (at least
> to me).  Making a Definity G3 and Asterisk fully integrate can cause
> severe rage followed by euphoria, so be warned.  Being creative is
> dangerous to some on the list.
>
> Try iaxmodem and hylafax.  Alex B did a very nice writeup on how to
> set that up so that it works very well.
>
>>
>>> 3. Now version 1.6 support Fax in a better way then 1.4. There is app_fax.c
>>> in the source code. Can someone please tell me what does this apps do?
>>
>> I assume you meant than not then, but I'm not sure if its a typo, you
>> might just not know.
>> app_fax.c does faxing. The question is what are YOU trying to do?
>>
>>
>>> 4. Version 1.8 as two modes: SpanDSP mode and some other method, what is
>>> the different between then.... can someone please help?
>>
>> Whats the other mode?
>>
>
> The best mode for T38 is probably Freeswitch or Callweaver.
>
>>
>>>
>>> Thanks
>>> Sassy
>>> --
>
> --
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