[Freeswitch-users] T.38 gateway and peer/self

Brian West brian at freeswitch.org
Mon Feb 27 18:15:19 MSK 2017 

I need to point out that there was a slight behavior change in fax handling
in 1.6.14+, It was related to 488 handling, We do not now by default accept
a t.38 re-invite, You must set fax_enable_t38=true, or we will 488 the
re-invite, and some devices do not handle this well.  You can restore the
previous default behavior by setting fax_enable_t38=true in vars.xml

I had sent this out, the is the second time a behavior change notice has
gone out and very few have seen it.

/b


On Mon, Feb 27, 2017 at 6:40 AM, Peter Steinbach <lists at telefaks.de> wrote:

> Hello Michael,
>
> I just updated a test machine with current Freeswitch from GIT. He I did
> not find any T.38 reinvite issue.
>
> Best regards
> Peter
>
>
>
> On 02/24/17 22:06, Michael Jerris wrote:
>
> If you have to switch to older free switch, that is a problem, we need to
> figure out exactly what is going on with current freeswitch or the issue
> will just never get fixed.
>
> Please lets look at what happens when its running on latest 1.6 release
> not older release and figure out how to get that working properly.
>
>
> On Feb 24, 2017, at 3:46 PM, Peter Steinbach <lists at telefaks.de> wrote:
>
> I finally found a solution, for those who are interested.
>
>    - I switched back to old Freeswitch from Feb 2016, as new FS always
>    answered with 488 on T.38 reinvite from the B-Leg
>    - Then I implemented the following (coding outside of FS with XML-Curl)
>       - When call is done with T.38 on boths legs, do not anything
>       special, just use a minimum dialplan
>       - if B-leg does not answer with T.38, this normally fails in my
>       environment. I then store a Value NOT38 to the dialled number for 1/2 hour
>       in a cache
>       - when then the fax machine is retrying the same call, I lookup the
>          cache and return another dialplan with T38 gateway (self) enabled
>
> That way, pure T.38 calls work nicely, and calls with T.39 on the B-leg
> work on the second try.
> Hope this helps. At last here in Germany, we have to find some
> workarounds, as fax implementation on some carrier's side (to say the
> positive) does not improve.
>
> Best regards
> Peter
>
>
> On 02/24/17 14:29, Peter Steinbach wrote:
>
> Hello Brian,
>
> I just updated to latest GIT. Dialplan ist still
>
> Dialplan: sofia/internalvpn2/492927aaaaaa at 10.7.0.1 Action
> set(fax_enable_t38=true)
> Dialplan: sofia/internalvpn2/492927aaaaaa at 10.7.0.1 Action
> set(fax_enable_t38_request=true)
> Dialplan: sofia/internalvpn2/492927aaaaaa at 10.7.0.1 Action
> set(execute_on_answer=t38_gateway self)
> Dialplan: sofia/internalvpn2/492927aaaaaa at 10.7.0.1 Action ring_ready()
> Dialplan: sofia/internalvpn2/492927aaaaaa at 10.7.0.1 Action
> bridge(sofia/gateway/sip.provider.com/4940bbbbbbbbbbbbbbb at sip.provider.com)
>
>
> However the behavour changed now
> 2017-02-24 13:50:18.913016 [NOTICE] switch_ivr_originate.c:3633 Channel [
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1] has been answered
> 2017-02-24 13:50:18.913016 [DEBUG] sofia.c:7241 Channel
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1 entering state [completed][200]
> *EXECUTE sofia/internalvpn2/492927aaaaaa at 10.7.0.1
> <sofia/internalvpn2/492927aaaaaa at 10.7.0.1> t38_gateway(peer)*
> 2017-02-24 13:50:18.913016 [DEBUG] switch_core_media_bug.c:841 Attaching
> BUG to sofia/internalvpn2/492927aaaaaa at 10.7.0.1
> 2017-02-24 13:50:18.913016 [DEBUG] switch_channel.c:3780 (
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1) Callstate Change RINGING ->
> ACTIVE
> 2017-02-24 13:50:18.913016 [DEBUG] switch_ivr_originate.c:3691 Originate
> Resulted in Success: [sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com]
> 2017-02-24 13:50:18.913016 [DEBUG] switch_ivr_bridge.c:1696 (
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com) State Change
> CS_CONSUME_MEDIA -> CS_EXCHANGE_MEDIA
> 2017-02-24 13:50:18.913016 [DEBUG] switch_core_state_machine.c:584 (
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com) Running State Change
> CS_EXCHANGE_MEDIA (Cur 2 Tot 10)
> 2017-02-24 13:50:18.913016 [DEBUG] switch_core_state_machine.c:653 (
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com) State EXCHANGE_MEDIA
> 2017-02-24 13:50:18.913016 [DEBUG] mod_sofia.c:645 SOFIA EXCHANGE_MEDIA
> 2017-02-24 13:50:18.953025 [DEBUG] sofia.c:7241 Channel
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1 entering state [ready][200]
> 2017-02-24 13:50:18.953025 [DEBUG] switch_rtp.c:7021 Correct audio ip/port
> confirmed.
> 2017-02-24 13:50:19.333126 [DEBUG] switch_rtp.c:7021 Correct audio ip/port
> confirmed.
> 2017-02-24 13:50:19.333126 [DEBUG] switch_core_io.c:448 Setting BUG Codec
> PCMA:8
> 2017-02-24 13:50:26.013047 [DEBUG] sofia.c:7241 Channel sofia/external/
> 4940bbbbbbbbbbbbbbb at sip.provider.com entering state [received][100]
> 2017-02-24 13:50:26.013047 [DEBUG] sofia.c:7251 Remote SDP:
> v=0
> o=HuaweiSoftX3000 1487923856 1487923858 IN IP4 185.39.xx.yy
> s=HuaweiSoftX3000
> c=IN IP4 185.39.xx.yy
> t=0 0
> m=image 16762 udptl t38
> a=T38FaxVersion:0
> a=T38MaxBitRate:14400
> a=T38FaxRateManagement:transferredTCF
> a=T38FaxMaxBuffer:500
> a=T38FaxMaxDatagram:500
> a=T38FaxUdpEC:t38UDPRedundancy
>
> *2017-02-24 13:50:26.013047 [DEBUG] switch_core_media.c:4634
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com
> <sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com> T38 REFUSE on request*
> 2017-02-24 13:50:26.013047 [DEBUG] sofia.c:8152 Reinvite resulted in codec
> negotiation failure.
> *2017-02-24 13:50:26.033201 [DEBUG] sofia.c:7234 Channel
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com
> <sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com> skipping state
> [ready][488]*
> *2017-02-24 13:50:31.993164 [DEBUG] mod_spandsp_fax.c:2212 Fax Tone
> Detected. [peer][]*
> *2017-02-24 13:50:31.993164 [DEBUG] mod_spandsp_fax.c:2080
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1
> <sofia/internalvpn2/492927aaaaaa at 10.7.0.1> starting gateway mode to
> sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com
> <sofia/external/4940bbbbbbbbbbbbbbb at sip.provider.com>*
> 2017-02-24 13:50:31.993164 [DEBUG] mod_spandsp_fax.c:2098 (
> sofia/internalvpn2/492927aaaaaa at 10.7.0.1) State Change CS_EXECUTE ->
> CS_RESET
> 2017-02-24 13:50:31.993164 [DEBUG] mod_spandsp_fax.c:2101 (sofia/external/
> 4940bbbbbbbbbbbbbbb at sip.provider.com) State Change CS_EXCHANGE_MEDIA ->
> CS_RESET
> 2017-02-24 13:50:31.993164 [DEBUG] switch_core_media_bug.c:1208 Removing
> BUG from sofia/internalvpn2/492927aaaaaa at 10.7.0.1
> 2017-02-24 13:50:31.993164 [DEBUG] switch_ivr_bridge.c:792 sofia/external/
> 4940bbbbbbbbbbbbbbb at sip.provider.com ending bridge by request from write
> function
>
> In this case the sip provider comes back with T.38 reinvite and Freeswitch
> refuses it.
>
> As you mentioned that there are further settings and variables (I see e.g.
> "fax_t38_tx_reinvite_packet_count" in the release notes), I am wondering
> how I will neeed to set this up in order to have in one single dialplan:
>
>    - send fax to SIP Provider(b leg) and have T.38 Re-invite from SIP
>    Provider and pass it to a-leg
>    - send fax to SIP Provider(b leg), do NOT receive T.38 Re-invite from
>    SIP Provider and then do T.38 Gateway in FS.
>
>
> Best regards Peter
>
>
> On 02/24/17 08:52, Peter Steinbach wrote:
>
> Hello Brian,
>
> this Version of Freeswitch is from 09-Feb-2016. So I think, we should
> update.
>
> We need to cover 2 scenarios
>
>    - send fax to SIP Provider(b leg) and have T.38 Re-invite from SIP
>    Provider and pass it to a-leg
>    - send fax to SIP Provider(b leg), do NOT receive T.38 Re-invite from
>    SIP Provider and then do T.38 Gateway in FS.
>
> And no: We cannot foresee, whether the SIp provider will do T.38 and not.
> Here in Germany, the main incumbant PSTN provider did not implement T.38,
> so it depends on the target number and actual route, if this will be T.38
> or not. A call to a certain number can be T.38 today and tomorrow it will
> be T.30 only, as some peering partner changed the routes in the meantime.
>
> Best regards
> Peter
>
>
> On 02/23/17 20:38, Brian West wrote:
>
> What revision of FreeSWITCH are you on?  These behaviors have been
> solidified in 1.6.15, Sadly MOST of the details of how it all works is
> locked up in my head, I've just not had the time to write it all down and
> update the documentation.  Can you outline all the scenarios you need to
> cover and if you have the ability know ahead of time which one needs to
> apply?
>
> /b
>
>
> On Thu, Feb 23, 2017 at 8:23 AM, Peter Steinbach <lists at telefaks.de>
> wrote:
>
>> Hello,
>>
>> we have the following screnario
>>
>>    - The caller, a local fax machine (Fax, ATA and Freeswitch) with
>>    T.38, is behind a slow line so therefore T.38 is needed here
>>    - a central Freeswitch fax server serves as a central gateway to the
>>    SIP provider
>>    - the SIP provider sometimes reinvites T.38 and sometimes not.
>>    - In case, the SIP provider does NOT answer with T.38, the central
>>    Freeswitch fax server shall act as a T.38 gateway and transcode between
>>    local fax (T.38) and SIP provider (T.30)
>>    - In case, the SIP provider does answer with T.38, the central
>>    Freeswitch fax server shall pass T.38 to the local fax ,machine (T.38)
>>
>> How we set this up
>>
>>    - according to the wiki we have a dialplan as follows: (this is what
>>    CLI shows)
>>
>> Dialplan: sofia/internalvpn2/49274xxxxx at 10.7.0.1 Action
>> set(fax_enable_t38=true)
>> Dialplan: sofia/internalvpn2/49274xxxxx at 10.7.0.1 Action
>> set(fax_enable_t38_request=true)
>> Dialplan: sofia/internalvpn2/49274xxxxx at 10.7.0.1 Action
>> set(execute_on_answer=t38_gateway self)
>> Dialplan: sofia/internalvpn2/49274xxxxx at 10.7.0.1 Action ring_ready()
>> Dialplan: sofia/internalvpn2/49274xxxxx at 10.7.0.1 Action bridge(
>> sofia/gateway/sip.provider.com/xxxxxxxxxxxxxxx at sip.provider.com)
>>
>> In all profiles, we have
>> <param name="t38-passthru" value="true"/>
>>
>> In case, the SIP provider does NOT answer with T.38, it works. The
>> caller's side is reinvited with T.38, the SIP provider side is T.30
>>
>> What the problem is: When the SIP provider' side IS answering with T.38,
>> then (sometimes, when I send it via cli from the local freeswitch near the
>> sending fax machine, it works)
>>
>>    - caller initiates a call
>>    - call is bridged to the SIP provider' side
>>    - we receive a T.38 Reinvite from the SIP provider' side
>>    - Freeswitch sends Trying back to the the SIP provider' side
>>    - Freeswitch logs: set(execute_on_answer=t38_gateway self)
>>    - Freeswitch sends a T.38 Reinvite to the caller, establishes T.38 on
>>    this side.
>>    - But the T.38 Reinvite from the SIP provider' side is not answerered
>>    - So the SIP provider' sidehangs up after 10 sec of timeout.
>>
>> What are we doing wrong here? Is it possible to act as a t.38 passthrough
>> router and a T.38 gateway in the same dialplan?
>>
>>
>>
>> --
>> With kind regards
>> Peter Steinbach
>>
>> Telefaks Services GmbHmailto:lists <lists> (att) telefaks.de
>> Internet: www.telefaks.de
>>
>>
>> _________________________________________________________________________
>> 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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>>
>
>
>
> --
>
> *Brian West*
> brian at freeswitch.org
>
> *Twitter: @FreeSWITCH , @briankwest*
>
> http://www.freeswitchbook.com
> http://www.freeswitchcookbook.com
>
> Allison prompts for FreeSWITCH:
>
> *https://www.gofundme.com/allison-prompts-for-freeswitch*
> <https://www.gofundme.com/allison-prompts-for-freeswitch>
>
> Wish to schedule a meeting?
>
> http://app.timebridge.com/#/meet/freeswitch
>
> Got Bugs? Report them here <https://freeswitch.org/jira>! | Reddit:
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>
> *T:*+19184209001 <(918)%20420-9001> | *F:*+19184209002 <(918)%20420-9002>
> | *M:*+1918424WEST (9378)
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>
>
> _________________________________________________________________________
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>
> Official FreeSWITCH Siteshttp://www.freeswitch.orghttp://confluence.freeswitch.orghttp://www.cluecon.com
>
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>
>
>
> --
> With kind regards
> Peter Steinbach
>
> Telefaks Services GmbHmailto:lists <lists> (att) telefaks.de
> Internet: www.telefaks.de
>
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services: consulting at freeswitch.orghttp://www.freeswitchsolutions.com
>
> Official FreeSWITCH Siteshttp://www.freeswitch.orghttp://confluence.freeswitch.orghttp://www.cluecon.com
>
> FreeSWITCH-users mailing listFreeSWITCH-users at lists.freeswitch.orghttp://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-usershttp://www.freeswitch.org
>
>
>
> --
> With kind regards
> Peter Steinbach
>
> Telefaks Services GmbHmailto:lists <lists> (att) telefaks.de
> Internet: www.telefaks.de
>
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services: consulting at freeswitch.orghttp://www.freeswitchsolutions.com
>
> Official FreeSWITCH Siteshttp://www.freeswitch.orghttp://confluence.freeswitch.orghttp://www.cluecon.com
>
> FreeSWITCH-users mailing listFreeSWITCH-users at lists.freeswitch.orghttp://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-usershttp://www.freeswitch.org
>
>
>
> --
> With kind regards
> Peter Steinbach
>
> Telefaks Services GmbHmailto:lists <lists> (att) telefaks.de
> Internet: www.telefaks.de
>
> _________________________________________________________________________
> 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
>
> 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
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>
>
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services: consulting at freeswitch.orghttp://www.freeswitchsolutions.com
>
> Official FreeSWITCH Siteshttp://www.freeswitch.orghttp://confluence.freeswitch.orghttp://www.cluecon.com
>
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>
>
>
> --
> With kind regards
> Peter Steinbach
>
> Telefaks Services GmbHmailto:lists <lists> (att) telefaks.de
> Internet: www.telefaks.de
>
>
> _________________________________________________________________________
> 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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>



-- 

*Brian West*
brian at freeswitch.org

*Twitter: @FreeSWITCH , @briankwest*

http://www.freeswitchbook.com
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