[Freeswitch-users] Issues with T.38 on outgoing fax (sofia T38 invite failed)

[Raúl Alexis Betancor Santana]

Some carriers gateways doesn't like a T.38 invite on advance, usually the
order that gives better results for faxing are first invite on PCMU/PCMA
(or any other supported codec) and then re-invite to T.38.

Take a look at how gonicus gofaxip do-it (https://github.com/gonicus/gofaxip
)

On Fri, Dec 1, 2017 at 10:21 PM, Kevin Olbrich <ko at sv01.de> wrote:

> Hi!
>
> Our carrier supports T.38 for outgoing faxes. I am trying to send faxes
> like this:
>
> originate {origination_caller_id_name='kevin',origination_caller_id_
>> number='+49123456789',ignore_early_media=true,absolute_
>> codec_string='PCMA,PCMU',fax_use_ecm=true,fax_enable_t38=
>> true,fax_enable_t38_request=true}sofia/gateway/carrier_1/+4912121212
>> &txfax(/opt/faxout.tif)
>
>
>
> Log:
>
> 668fd128-f2f5-4af5-9536-6780762c2efa 2017-12-01 21:38:57.513164 [DEBUG]
>> sofia_glue.c:1295 sofia/external/+4912121212 sending invite version: 1.6.19
>> -36-7a77e0b 64bit
>> 668fd128-f2f5-4af5-9536-6780762c2efa Local SDP:
>> 668fd128-f2f5-4af5-9536-6780762c2efa v=0
>> 668fd128-f2f5-4af5-9536-6780762c2efa o=FreeSWITCH 1512130268 1512130270
>> IN IP4 123.123.123.123
>> 668fd128-f2f5-4af5-9536-6780762c2efa s=FreeSWITCH
>> 668fd128-f2f5-4af5-9536-6780762c2efa c=IN IP4 123.123.123.123
>> 668fd128-f2f5-4af5-9536-6780762c2efa t=0 0
>> 668fd128-f2f5-4af5-9536-6780762c2efa m=image 30466 udptl t38
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxVersion:0
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38MaxBitRate:14400
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxFillBitRemoval
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxRateManagement:
>> transferredTCF
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxMaxBuffer:2000
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxMaxDatagram:400
>> 668fd128-f2f5-4af5-9536-6780762c2efa a=T38FaxUdpEC:t38UDPRedundancy
>> 668fd128-f2f5-4af5-9536-6780762c2efa
>> 668fd128-f2f5-4af5-9536-6780762c2efa 2017-12-01 21:38:57.533158 [DEBUG]
>> sofia.c:7084 Channel sofia/external/+4912121212 entering state [calling][0]
>> 668fd128-f2f5-4af5-9536-6780762c2efa 2017-12-01 21:38:57.673120 [DEBUG]
>> sofia.c:6294 sofia/external/+4912121212 T38 invite failed
>> 668fd128-f2f5-4af5-9536-6780762c2efa 2017-12-01 21:38:57.673120 [DEBUG]
>> sofia.c:7077 Channel sofia/external/+4912121212 skipping state [ready][488]
>
>
>
> Carrier confirmed that T.38 is possible... What could be the cause for
> this? How can I enforce T.38 instead of falling back to g711a (hangup on
> failed invite)?
>
> Thanks.
>
> Kind regards,
> Kevin
>
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