[Freeswitch-users] T38 Fax Fallback

Fri Dec 8 09:00:57 UTC 2017

Mirko, Loi,

Thanks for your responses. I really wanted to check if there was anything
obvious which our platform was not handling properly however your responses
help to confirm that Fax/FOIP is rarely plain sailing. I had actually found
Mirko's email thread before writing this - Brian's response was helpfully
discouraging!

I'm not clear on whether it will be possible to remove the media proxy from
the call path on this occasion but it is something I'll look into.

I will also look into finding resource to test on the latest stable release
and see if the recent modifications are resolving this situation.

Once those avenues are exhausted I'll get on with the day job! If anyone
does have other suggestions then please do get in touch.

Thanks again,

Callum

*NB. When was the last time you got a fax?!?*

On Fri, Dec 8, 2017 at 4:36 AM Lợi Đặng <loi.dangthanh at gmail.com> wrote:

> Hi, media proxy mode is not willing to work fine with fax t38, since
> `t38_passthru=true` dont have any effect in that mode.
> Could consider getting away from media proxy mode since it's not
> recommended anymore by FS's developers.
> Btw, you may want to upgrade your FS to 1.6.15 or later.
>
> http://lists.freeswitch.org/pipermail/freeswitch-users/2017-January/124459.html
>
> rgds,
> Loi Dang
>
> On Fri, Dec 8, 2017 at 1:55 AM Mirko Brankovic <mirkobrankovic at gmail.com>
> wrote:
>
>> I had a same question:
>> http://thread.gmane.org/gmane.comp.telephony.freeswitch.user/86263
>> Sorry google lead me only to this link...
>>
>> On Dec 7, 2017 18:06, "Callum Guy" <callum.guy at x-on.co.uk> wrote:
>>
>>> Hi All,
>>>
>>> I'll try and keep this simple.
>>>
>>> We are experiencing difficulty transmitting fax with a certain UK
>>> provider (BT) who have suggested the fix for the fault is that we "*should
>>> fall back to using G711 pass through in order to negotiate/ send fax*"
>>>
>>> The call initially connects with G711 (and the media is proxied).
>>> Fax is detected by the originator which issues a RE-INVITE request to
>>> use T38.
>>> This is rejected by the gateway with a 488 at which point we would
>>> expect the call to fall back to G711 however FreeSWITCH is reporting that
>>> this is not possible due to a media bug:
>>>
>>> "*Session is connected to a media bug. Re-Negotiation implicitly
>>> disabled.*"
>>>
>>> My understanding was that a media bug would be required for the initial
>>> fax tone detection which subsequently triggers the T38 session start?
>>> Could anyone confirm whether we need to be looking into closing off the
>>> media bug manually or if there is an alternative route to resolving this
>>> issue?
>>>
>>> We are running FreeSWITCH (Version 1.4.26  64bit).
>>> Calls are dispatched with setting "t38_passthru=true".
>>>
>>> Any help would be very much welcomed.
>>>
>>> Best Regards,
>>>
>>> Callum
>>> --
>>> Callum Guy
>>> Head of Information Security
>>> X-on
>>>
>>>
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>>
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>
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>
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-- 
Callum Guy
Head of Information Security
X-on

-- 

*0333 332 0000  |  www.x-on.co.uk <http://www.x-on.co.uk>  |   ** 
<https://www.linkedin.com/company/x-on>   <https://www.facebook.com/XonTel> 
  <https://twitter.com/xonuk> * 
X-on is a trading name of Storacall Technology Ltd a limited company 
registered in England and Wales.
Registered Office : Avaland House, 110 London Road, Apsley, Hemel 
Hempstead, Herts, HP3 9SD. Company Registration No. 2578478.
The information in this e-mail is confidential and for use by the 
addressee(s) only. If you are not the intended recipient, please notify 
X-on immediately on +44(0)333 332 0000 and delete the
message from your computer. If you are not a named addressee you must not 
use, disclose, disseminate, distribute, copy, print or reply to this email. Views 
or opinions expressed by an individual
within this email may not necessarily reflect the views of X-on or its 
associated companies. Although X-on routinely screens for viruses, 
addressees should scan this email and any attachments
for viruses. X-on makes no representation or warranty as to the absence of 
viruses in this email or any attachments.

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