[Freeswitch-users] T38 Fax Fallback

Mirko Brankovic mirkobrankovic at gmail.com
Fri Dec 8 12:23:43 UTC 2017


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


*Good one :D*

On Fri, Dec 8, 2017 at 10:00 AM, Callum Guy <callum.guy at x-on.co.uk> wrote:

> 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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>>> http://www.freeswitchsolutions.com
>>>
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>>
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>>
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://confluence.freeswitch.org
>> http://www.cluecon.com
>>
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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 <+44%20333%20332%200000> 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.
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://confluence.freeswitch.org
> http://www.cluecon.com
>
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>



-- 
Regards,
Mirko
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