I finally found a solution, for those who are interested.

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@10.7.0.1 Action set(fax_enable_t38=true)
Dialplan: sofia/internalvpn2/492927aaaaaa@10.7.0.1 Action set(fax_enable_t38_request=true)
Dialplan: sofia/internalvpn2/492927aaaaaa@10.7.0.1 Action set(execute_on_answer=t38_gateway self)
Dialplan: sofia/internalvpn2/492927aaaaaa@10.7.0.1 Action ring_ready()
Dialplan: sofia/internalvpn2/492927aaaaaa@10.7.0.1 Action bridge(sofia/gateway/sip.provider.com/4940bbbbbbbbbbbbbbb@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@10.7.0.1] has been answered
2017-02-24 13:50:18.913016 [DEBUG] sofia.c:7241 Channel sofia/internalvpn2/492927aaaaaa@10.7.0.1 entering state [completed][200]
EXECUTE sofia/internalvpn2/492927aaaaaa@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@10.7.0.1
2017-02-24 13:50:18.913016 [DEBUG] switch_channel.c:3780 (sofia/internalvpn2/492927aaaaaa@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@sip.provider.com]
2017-02-24 13:50:18.913016 [DEBUG] switch_ivr_bridge.c:1696 (sofia/external/4940bbbbbbbbbbbbbbb@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@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@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@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@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@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@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@10.7.0.1 starting gateway mode to sofia/external/4940bbbbbbbbbbbbbbb@sip.provider.com
2017-02-24 13:50:31.993164 [DEBUG] mod_spandsp_fax.c:2098 (sofia/internalvpn2/492927aaaaaa@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@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@10.7.0.1
2017-02-24 13:50:31.993164 [DEBUG] switch_ivr_bridge.c:792 sofia/external/4940bbbbbbbbbbbbbbb@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:

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@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@10.7.0.1 Action set(fax_enable_t38=true)
Dialplan: sofia/internalvpn2/49274xxxxx@10.7.0.1 Action set(fax_enable_t38_request=true)
Dialplan: sofia/internalvpn2/49274xxxxx@10.7.0.1 Action set(execute_on_answer=t38_gateway self)
Dialplan: sofia/internalvpn2/49274xxxxx@10.7.0.1 Action ring_ready()
Dialplan: sofia/internalvpn2/49274xxxxx@10.7.0.1 Action bridge(sofia/gateway/sip.provider.com/xxxxxxxxxxxxxxx@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 GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de

_________________________________________________________________________
Professional FreeSWITCH Consulting Services:
consulting@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@lists.freeswitch.org
http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
http://www.freeswitch.org



--

Brian West
brian@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

Wish to schedule a meeting?

http://app.timebridge.com/#/meet/freeswitch

Got Bugs? Report them here! | Reddit: /r/freeswitch

T:+19184209001 | F:+19184209002 | M:+1918424WEST (9378)
Skype:briankwest



_________________________________________________________________________
Professional FreeSWITCH Consulting Services: 
consulting@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@lists.freeswitch.org
http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
http://www.freeswitch.org


-- 
With kind regards
Peter Steinbach 

Telefaks Services GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de




_________________________________________________________________________
Professional FreeSWITCH Consulting Services: 
consulting@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@lists.freeswitch.org
http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
http://www.freeswitch.org


-- 
With kind regards
Peter Steinbach 

Telefaks Services GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de




_________________________________________________________________________
Professional FreeSWITCH Consulting Services: 
consulting@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@lists.freeswitch.org
http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
http://www.freeswitch.org


-- 
With kind regards
Peter Steinbach 

Telefaks Services GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de