[Freeswitch-users] refusing t38 in outgoing fax server transmission

Thu May 30 12:30:57 UTC 2019

Hello Brian,
thanks for your reply.
Can you point me out to the bug so i can check in which versions it has
been fixed?
Thanks a lot.
S

Il giorno gio 30 mag 2019 alle ore 01:58 Brian West <brian at freeswitch.com>
ha scritto:

> Update, this has been fixed for quite a while.
>
> On Wed, May 29, 2019 at 6:52 PM Giovanni Maruzzelli <gmaruzz at gmail.com>
> wrote:
>
>> On Thu, May 30, 2019 at 12:46 AM Sandro Bordacchini <
>> sandro.bordacchini at nems.it> wrote:
>>
>>> I am just wondering if it's possible to configure FS to accept the G711
>>> media and "turn off" the T38 media that have been received in the same sdp
>>> (refer to reinvite in the unsuccessful case).
>>> That would be really helpful for me but i wasnt able to get that kind of
>>> behaviour.
>>> Am I missing something?
>>>
>>
>> Maybe I do not understand what you want to achieve. If you do not act on
>> T38, then also if you are offered it, you will not take it in
>> consideration, and just process the call as a call without T38
>>
>> If you are "proxying" T38 (eg inbound T38 outbound plain g711), then
>> there are specific settings for it
>>
>> Check both of the links:
>>
>>
>> https://freeswitch.org/confluence/display/FREESWITCH/T.38#T.38-Sofiaprofileparameters
>>
>> https://freeswitch.org/confluence/display/FREESWITCH/mod_spandsp
>>
>> -giovanni
>>
>>
>>> Thanks a lot.
>>> S
>>>
>>> Il giorno mer 29 mag 2019 alle ore 10:20 Giovanni Maruzzelli <
>>> gmaruzz at gmail.com> ha scritto:
>>>
>>>> Hello Sandro,
>>>>
>>>> so, they want you to send out faxes with T30 in g711? That will be
>>>> *very* unreliable, you *want* to use T38.
>>>>
>>>> Anyway, you want to use PCMA with normal packet size (eg, not 10 ms).
>>>> You just specify PCMA as absolute_codec string.
>>>>
>>>> You do not have to refuse explicitly the call (no 488), you just do not
>>>> accept t38 fax transmission.
>>>>
>>>> So, disable t38 everywhere, and do the fax over g711 (eg, over pcma).
>>>>
>>>> That will be very unreliable. T38 has been created to solve that
>>>> unreliability.
>>>>
>>>> If you happen to find a FreeSWITCH book, there is a chapter about faxes.
>>>>
>>>>
>>>> Hope this help,
>>>> -giovanni
>>>>
>>>>
>>>> On Wed, May 29, 2019 at 6:51 AM Sandro Bordacchini <
>>>> sandro.bordacchini at nems.it> wrote:
>>>>
>>>>> Hello everyone.
>>>>>
>>>>> I am have a few FS installations interconnected with a voip provider;
>>>>> during outbound fax server transmissions, they told us that we need *to
>>>>> refuse T38 even if offered by the network*.
>>>>> The sdp offer/answer negotiation varies depending on the called
>>>>> number, probably due to a different routing in the voip provider's network.
>>>>> I experience some dropped calls (even before the fax transmission
>>>>> kicks in) using both FS versions 1.4.9 and 1.6.16.
>>>>>
>>>>> This is a successful sdp negotiation (after call is estabilished)
>>>>> First reinvite:
>>>>> REMOTE INVITE with SDP: v=0..o=LucentPCSF 413445855 413445856 IN IP4
>>>>> 10.198.1.230..s=-..c=IN IP4 10.198.1.230..t=0 0..m=audio 15756 RTP/AVP 8 96
>>>>> 4..a=rtpmap:96 telephone-event/8000..a=fmtp:96 0-15..a=ptime:20..a=X-sqn:
>>>>> 0..a=X-cap:  1 image udptl t38..
>>>>> LOCAL 200OK with SDP: v=0..o=FreeSWITCH 1558069426 1558069428 IN IP4
>>>>> 10.197.98.6..s=FreeSWITCH..c=IN IP4 10.197.98.6..t=0 0..m=audio 30394
>>>>> RTP/AVP 8 96..a=rtpmap:8 PCMA/8000..a=rtpmap:96
>>>>> telephone-event/8000..a=fmtp:96 0-16..a=silenceSupp:off - - -
>>>>> -..a=ptime:20..
>>>>> Then, a second reinvite happens:
>>>>> REMOTE INVITE with SDP: v=0..o=LucentPCSF 413445855 413445857 IN IP4
>>>>> 10.198.1.230..s=-..c=IN IP4 10.198.1.230..t=0 0..m=audio 0 RTP/AVP 0..c=IN
>>>>> IP4 10.198.1.230..m=image 12834 udptl t38..a=X-sqn: 0..a=X-cap:  1 image
>>>>> udptl t38..
>>>>> LOCAL 488
>>>>> Then, the last reinvite:
>>>>> REMOTE INVITE with SDP: v=0..o=LucentPCSF 413445855 413445858 IN IP4
>>>>> 10.198.1.230..s=-..c=IN IP4 10.198.1.230..t=0 0..m=audio 15756 RTP/AVP 8 96
>>>>> 4..a=rtpmap:96 telephone-event/8000..a=fmtp:96 0-15..a=ptime:20..a=X-sqn:
>>>>> 0..a=X-cap:  1 image udptl t38..m=image 0 udptl t38..c=IN IP4 10.198.1.230..
>>>>> LOCAL 200OK with SDP: v=0..o=FreeSWITCH 1558069426 1558069429 IN IP4
>>>>> 10.197.98.6..s=FreeSWITCH..c=IN IP4 10.197.98.6..t=0 0..m=audio 30394
>>>>> RTP/AVP 8 96..a=rtpmap:8 PCMA/8000..a=rtpmap:96
>>>>> telephone-event/8000..a=fmtp:96 0-16..a=silenceSupp:off - - -
>>>>> -..a=ptime:20..m=image 0 udptl t38..
>>>>> And the fax is transmitted correctly
>>>>>
>>>>> This is an unsuccessful sdp negotiation:
>>>>> First reinvite
>>>>> REMOTE INVITE with SDP: v=0..o=LucentPCSF 579041281 579041282 IN IP4
>>>>> 10.198.1.230..s=-..c=IN IP4 10.198.1.230..t=0 0..m=audio 13302 RTP/AVP 8
>>>>> 96..a=rtpmap:96 telephone-event/8000..a=ptime:10..a=ecan:fb on
>>>>> -..a=Fax..m=image 17522 udptl
>>>>> t38..a=T38FaxVersion:0..a=T38MaxBitRate:14400..a=T38FaxRateManagement:transferredTCF..a=T38FaxMaxBuffer:1800..a=T38FaxMaxDatagram:260..a=T38FaxUdpEC:t38UDPRedundancy..a=ecan:fb
>>>>> on -..
>>>>> LOCAL 488
>>>>> and the remote hangs up.
>>>>>
>>>>> My point is that, in case of unsuccessful negotiation, FS receives a
>>>>> reinvite with two "m=" in the sdp, one G711A (port 13302) and one T38 (port
>>>>> 17522).
>>>>> Is it ok for FS to refuse "all the sdp" with 488 just because it has
>>>>> to refuse T38 or it should be configured to refuse only the T38 media?
>>>>> Should remote endpoint send another reinvite with only G711 or only
>>>>> T38 before hanging up?
>>>>>
>>>>> Thanks in advance to whoever read till here :-)
>>>>> Any hints?
>>>>>
>>>>> S.
>>>>>
>>>>> P.s.:
>>>>> This is what i get in the log in the unsuccessful case during the
>>>>> reinvite (1.4.9 code):
>>>>> [...]
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_media.c:3476 Audio
>>>>> Codec Compare [PCMA:8:8000:10:64000:1]/[PCMA:8:8000:10:64000:1]
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_media.c:3531 Audio
>>>>> Codec Compare [PCMA:8:8000:10:64000:1] ++++ is saved as a match
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_media.c:3397 Set
>>>>> telephone-event payload to 96
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_media.c:3713 Set 2833
>>>>> dtmf send payload to 96
>>>>> 2019-05-17 11:22:57.498389 [ERR] sofia.c:7065 Reinvite Codec Error!
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_session.c:1053 Send
>>>>> signal sofia/external/<calledfaxnumber> [BREAK]
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_session.c:1053 Send
>>>>> signal sofia/external/<calledfaxnumber> [BREAK]
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] switch_core_media.c:2280 Already
>>>>> using PCMA
>>>>> 2019-05-17 11:22:57.498389 [DEBUG] sofia.c:6444 Channel
>>>>> sofia/external/<calledfaxnumber> entering state [ready][488]
>>>>> 2019-05-17 11:22:57.638443 [DEBUG] switch_core_session.c:1053 Send
>>>>> signal sofia/external/<calledfaxnumber> [BREAK]
>>>>> 2019-05-17 11:22:57.638443 [NOTICE] sofia.c:952 Hangup
>>>>> sofia/external/<calledfaxnumber> [CS_EXECUTE] [NORMAL_CLEARING]
>>>>> 2019-05-17 11:22:57.638443 [DEBUG] switch_channel.c:3222 Send signal
>>>>> sofia/external/<calledfaxnumber> [KILL]
>>>>> 2019-05-17 11:22:57.638443 [DEBUG] switch_core_session.c:1388 Send
>>>>> signal sofia/external/<calledfaxnumber> [BREAK]
>>>>> 2019-05-17 11:22:57.638443 [DEBUG] mod_spandsp_fax.c:293 FLOW T.30
>>>>> Status changing to 'The call dropped prematurely'
>>>>>
>>>>> This are the most relevant settings on api originate:
>>>>> [DEBUG] switch_event.c:1688 Parsing variable [fax_use_ecm]=[off]
>>>>> [DEBUG] switch_event.c:1688 Parsing variable
>>>>> [absolute_codec_string]=[PCMA at 10i]
>>>>> [DEBUG] switch_event.c:1688 Parsing variable [fax_enable_t38]=[false]
>>>>> [DEBUG] switch_event.c:1688 Parsing variable
>>>>> [fax_enable_t38_request]=[false]
>>>>> [DEBUG] switch_event.c:1688 Parsing variable [refuse_t38]=[true]
>>>>> and on the external profile t38-passthru is set to false.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ing. Sandro Bordacchini / System Engineering and Product Management
>>>>> sandro.bordacchini at nems.it
>>>>>
>>>>>
>>>>> _________________________________________________________________________
>>>>>
>>>>> The FreeSWITCH project is sponsored by SignalWire
>>>>> https://signalwire.com
>>>>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>>>> services.
>>>>> Build your next product on our scalable cloud platform.
>>>>>
>>>>> Join our online community to chat in real time
>>>>> https://signalwire.community
>>>>>
>>>>> Professional FreeSWITCH Services
>>>>> sales at freeswitch.com
>>>>> https://freeswitch.com
>>>>>
>>>>> Official FreeSWITCH Sites
>>>>> https://freeswitch.com/oss
>>>>> https://freeswitch.org/confluence
>>>>> https://cluecon.com
>>>>>
>>>>> FreeSWITCH-users mailing list
>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>> UNSUBSCRIBE:
>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>> https://freeswitch.com
>>>>
>>>>
>>>>
>>>> --
>>>> Sincerely,
>>>>
>>>> Giovanni Maruzzelli
>>>> OpenTelecom.IT
>>>> cell: +39 347 266 56 18
>>>>
>>>>
>>>> _________________________________________________________________________
>>>>
>>>> The FreeSWITCH project is sponsored by SignalWire
>>>> https://signalwire.com
>>>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>>> services.
>>>> Build your next product on our scalable cloud platform.
>>>>
>>>> Join our online community to chat in real time
>>>> https://signalwire.community
>>>>
>>>> Professional FreeSWITCH Services
>>>> sales at freeswitch.com
>>>> https://freeswitch.com
>>>>
>>>> Official FreeSWITCH Sites
>>>> https://freeswitch.com/oss
>>>> https://freeswitch.org/confluence
>>>> https://cluecon.com
>>>>
>>>> FreeSWITCH-users mailing list
>>>> FreeSWITCH-users at lists.freeswitch.org
>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>> UNSUBSCRIBE:
>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>> https://freeswitch.com
>>>
>>>
>>> _________________________________________________________________________
>>>
>>> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
>>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>> services.
>>> Build your next product on our scalable cloud platform.
>>>
>>> Join our online community to chat in real time
>>> https://signalwire.community
>>>
>>> Professional FreeSWITCH Services
>>> sales at freeswitch.com
>>> https://freeswitch.com
>>>
>>> Official FreeSWITCH Sites
>>> https://freeswitch.com/oss
>>> https://freeswitch.org/confluence
>>> https://cluecon.com
>>>
>>> FreeSWITCH-users mailing list
>>> FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>> https://freeswitch.com
>>
>>
>>
>> --
>> Sincerely,
>>
>> Giovanni Maruzzelli
>> OpenTelecom.IT
>> cell: +39 347 266 56 18
>>
>> _________________________________________________________________________
>>
>> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>> services.
>> Build your next product on our scalable cloud platform.
>>
>> Join our online community to chat in real time
>> https://signalwire.community
>>
>> Professional FreeSWITCH Services
>> sales at freeswitch.com
>> https://freeswitch.com
>>
>> Official FreeSWITCH Sites
>> https://freeswitch.com/oss
>> https://freeswitch.org/confluence
>> https://cluecon.com
>>
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> https://freeswitch.com
>
>
>
> --
>
> Brian West | Co-founder and Developer
>
> Need Commercial support? email sales at freeswitch.com
>
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>
> Email: brian at freeswitch.com
>
> Mobile: 918-424-9378
>
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>
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> _________________________________________________________________________
>
> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
> services.
> Build your next product on our scalable cloud platform.
>
> Join our online community to chat in real time
> https://signalwire.community
>
> Professional FreeSWITCH Services
> sales at freeswitch.com
> https://freeswitch.com
>
> Official FreeSWITCH Sites
> https://freeswitch.com/oss
> https://freeswitch.org/confluence
> https://cluecon.com
>
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> https://freeswitch.com

-- 

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