[asterisk-users] FAX Issues

[C F]

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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