[asterisk-users] FAX Issues

Tue Aug 9 23:15:38 CDT 2011

Off topic but cool tech.  One of the defunct Asterisk Appliance's was
based on the Altix 350.

http://www.sgi.com/products/servers/altix/numalink.html

On Wed, Aug 10, 2011 at 12:12 AM, Steve Totaro
<stotaro at totarotechnologies.com> wrote:
> I do love this stuff.  Being self taught, Asterisk actually made me
> learn LAMP from the command line.  I was a pure Windows and Cisco guy,
> all self taught since the VIC20 and Commodore 64, I taught myself
> BASIC.
>
> Anyways, just like anything you need to define the job before you
> attempt to choose the proper tool(s).
>
> Just a quick correction to number 5, Hylafax is a very powerful fax
> app, IAXmodem is just a bit of glue.  It has error correction and
> other features that help in TX/RX faxes successfully.  Asterisk is not
> the endpoint.
>
> It has been in dev since the early 90s, starting with SGI and their
> IRIX servers.  (I love SGI and the Cray Numalink)
>
> http://en.wikipedia.org/wiki/HylaFAX
>
> On Tue, Aug 9, 2011 at 10:31 PM, C F <shmaltz at gmail.com> wrote:
>> Guys in my opinion this thread has been very productive. Which proves
>> one thing, as many people you are going to ask about faxing with
>> asterisk that many opinions you are going to get (maybe even add +1
>> opinions :P).
>> In the end it depends on your experience, hence I asked the OP to try
>> for himself.
>> Faxing is one of those things that for everyone something else works.
>> What works for you might and might not work for someone else.
>> To sum it up:
>> 1. Faxing doesn't like lost packets.
>> 2. That said, T.38 "could" work
>> 3. Pure TDM (and by that I don't mean the literal definition of TDM
>> but POTS as well) is still the best.
>> 4. Running that TDM thru asterisk is again open to different
>> experiences among users.
>> 5. Using Asterisk as a fax endpoint (hylafax, app_fax take your pick)
>> should work in most cases if the handoff to asterisk is TDM and could
>> work if it's T.38
>>
>>
>>
>> On Tue, Aug 9, 2011 at 9:28 PM, Steve Totaro
>> <stotaro at asteriskhelpdesk.com> wrote:
>>> On Tue, Aug 9, 2011 at 8:31 PM, Lee Howard <faxguy at howardsilvan.com> wrote:
>>>> Steve Totaro wrote:
>>>>>
>>>>> On Tue, Aug 9, 2011 at 7:22 PM, Lee Howard <faxguy at howardsilvan.com>
>>>>> wrote:
>>>>>
>>>>>>
>>>>>> Ryan McGuire wrote:
>>>>>>
>>>>>>>
>>>>>>> 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.
>>>>>>>
>>>>>>
>>>>>> As SIP is usually running over UDP/IP it doesn't take much to produce
>>>>>> dropped packets.  Dropped packets mean lost audio which means lost data
>>>>>> and
>>>>>> possible demodulation difficulties for the modems.  If you're in an
>>>>>> environment where dropped UDP packets don't occur you're in a very rare
>>>>>> scenario.
>>>>>>
>>>>>
>>>>> I suppose you are talking about from the provider and not on the LAN?
>>>>>
>>>>
>>>> You certainly can (and usually will) have UDP packet loss on an uncontrolled
>>>> LAN.
>>>
>>> Then you should be fired for not controlling your LAN.
>>>
>>>>
>>>>> At Equinix in Ashburn VA, I have never had a dropped packet via the
>>>>> crossconnect from our cage to Level3's cage.  Sub ms pings.  Putting
>>>>> the primary PBX in Equinix and a 100meg speed for all VoIP calls in
>>>>> our out.  100meg DIA and 100meg layer 2 fiber to corporate.
>>>>
>>>> I have no reason to doubt your claims, but if this is true, then your
>>>> arrangement there clearly mitigates the likelihood of UDP packet loss.
>>>>  Nevertheless, this arrangement is not something that the typical user who
>>>> asks "how do I fax over SIP/VoIP" is going to have.  Without being very
>>>> clear about the environment and explaining the pitfalls of not following
>>>> your example exactly, you're not doing them any favors by encouraging them
>>>> to attempt it in their environment.
>>>
>>> I don't care what you doubt or not.  I engineered it, Got the
>>> contracts signed, provisioned, setup BGP, got all that cleared with
>>> the steering committee.
>>>
>>> I do not assume anything about anyone and cannot define a typical
>>> user.  That is making as ass out of you and me.
>>>
>>> I encourage everyone to attempt and test everything!  Not put it in
>>> production without some reasonable testing.
>>>
>>>>
>>>> For every one user who I've ever heard from saying that they have reliable
>>>> G.711 faxing over their SIP channels I've heard from a dozen who don't.
>>>
>>> Roger That.  That is why I advise clients it is not the best way to go.
>>>
>>>>
>>>> Thanks,
>>>>
>>>> Lee.
>>>
>>> He came in giving no details about his setup.  Now I see it is 1000 phones.
>>>
>>> I guess you don't care to read threads, and like to jump in the middle
>>> not knowing what you are talking about.
>>>
>>> I said that there is really no good way to handle faxes with Asterisk
>>> except with a T1, IAXmodem, and Hylafax.
>>>
>>> I bought fax for Asterisk when migrating to an all SIP world and it
>>> was a dismal failure and Digium didn't even have anyone that could
>>> explain any of the stats or problems I had.  I paid for it so I didn't
>>> have to screw around and finally I just took a refund and a big dent
>>> as far as the companies opinion of me.
>>>
>>> I wanted to try the 1.2 asterisk fork and that other project that came
>>> from the fact that Asterisk has deadlock issues and a whole cross
>>> platform rewrite has been done.
>>>
>>> Thanks,
>>> Steve Totaro
>>>
>>> --
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>>
>> --
>> _____________________________________________________________________
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>>
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>