[Freeswitch-users] Successful faxing with spandsp / T38 and stats

[Sean Devoy]

Mitch,

That is very impressive.  Truly, far higher than I thought possible with
VOIP.
How about sharing your dialplan and hardware (ata brand and model) and
configuration that achieves this magic!  
Are your ATAs NAT'ed and remote from your fs server?

Details man Details!  :-)  I would love a reliable fax solution for my
customers.  I have about 99% inbound and 80% outbound for one customer and
another that we could find no way to limit its transmission speed so we have
0% for it.

Thanks,
Sean

-----Original Message-----
From: freeswitch-users-bounces at lists.freeswitch.org
[mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of Mitch
Capper
Sent: Tuesday, June 26, 2012 9:02 PM
To: FreeSWITCH Users Help
Subject: [Freeswitch-users] Successful faxing with spandsp / T38 and stats

Hello everyone,
I have been working on faxing for awhile now and figure I would post back
with some results and method.  Much of my method I have documented on the
wiki about faxing but some more details on my method are also below.  Faxing
overall is a horrific thing and when I first looked into VOIP faxing I did
not think I would be able to achieve nearly the success rate I have been
able to with FreeSWITCH.

These stats were collected over 1000 individual faxes and over 4000
pages sent to over 500 unique fax numbers.   I would guess a lot of
these numbers are geographically clustered around the northwest of the US
but I doubt that should matter a whole lot.
Up until last week I had but 1 fax that didn't complete (it was an 80+ page
fax that failed twice mid-fax before we just emailed it so it probably would
have completed with some extra time).

In the last week I have had two I have yet to get through (not sure why or
if I have finally found fax machines I just can't send to or
what have you).   I was blown away with the current success rate.  I
did not collect as detailed stats the entire time I was logging data
(probably only 3/4's+ of the total faxes have full detailed stats).
With all that said the below numbers should be decently reflective of real
world use.

First on the method:

I try a progressive retry system,  I try one method if it fails I wait
60 seconds then try the next.  I use two providers, flowroute and
t38faxing.com.   Flowroute I highly recommend they are a great
provider and have worked very well for faxing.  T38Faxing.com / EZCALL are
quite bad and I highly recommend avoiding (see bottom of email for why).

My 8 methods are: T38,ECM / ECM / T38_DISABLED,ECM / T38,SLOW /
T38_DISABLED,SLOW / BACKUP,ECM / BACKUP,SLOW / BACKUP,SLOW,T38_DISABLED

Slashes delimit the method and commas delimit the flags for that
method.   Slow=fax_disable_v17,  T38=fax_enable_t38_request,
T38_DISABLED=fax_enable_t38=false  BACKUP=T38Faxing.com (T38faxing.com fails
if t38_request is enabled so thats why T38 is not used with them).

If the line is busy I don't move to the next method nor if there is a
channel error.

The methods are tried in order they are not tried randomly.  Randomly would
make the below stats better but I care about fax through a fast as possible
so I try in order of what I thought had the best chance of success.

average secs per page: 28.055
average tries until success: 1.33 (not including busy).

Method Usage Rates:
        75% T38,ECM success rate: 82% avg secs/page: 27.4
        13% ECM success rate: 46% avg secs/page: 29.5
         7% ECM,T38_DISABLED success rate: 60% avg secs/page: 28.3
         2% T38,SLOW success rate: 56% avg secs/page: 45.7
         1% SLOW,T38_DISABLED success rate: 57% avg secs/page: 40.6
         1% ECM,BACKUP success rate: 57% avg secs/page: 35.8

Failure Reasons:
        40% The call dropped prematurely
        25% No response after sending a page
        11% Invalid response after sending a page
         6% Invalid ECM response received from receiver
         5% Received no response to DCS or TCF
         2% Unexpected message received
         2% Timed out waiting for initial communication
         2% The HDLC carrier did not stop in a timely manner
         1% Received bad response to DCS or training
         1% Disconnected after permitted retries
         0% Timed out waiting for the first message

Hope you enjoy the method and stats, honestly with this rate of success and
either a few better backup providers or even a single hard line for faxing
over you could run a very respectable faxing service using FS.

~Mitch


Providers:
As I mention on the wiki certainly one very important thing other than
trying various methods is quality providers.  Flowroute handled 99% of
the faxes above obviously and did a great job.     T38Faxing however I
cannot recommend avoiding more.  I used them as my backup provider after
surveying #freeswitch a bit and while I normally try to avoid a
brand bash it has just be a horrible experience.   They have a very
poor backend which would be livable if their support was not equally poor.
They frequently don't answer the phone and their support email system has
been down for awhile before (emails bounce) along with
their control panel for their website.   Their entire faxing service
wasn't working for over a week when contacted they said they were adjusting
their north american routing and it took over a day before
it was back up.   So overall I would suggest finding a different
provider from t38faxing.

_________________________________________________________________________
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http://www.freeswitchsolutions.com




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