[Freeswitch-users] Re-Invite t38 is incomplete when t38_passtrough=true

Antonio Silva asilva at wirelessmundi.com
Fri May 17 16:23:32 MSD 2013


Hi,

i have the following scenario when sending a fax:
ATA => FS  => Provider => destination


The ATA tries to send a fax to destination and in the middle of the call
there is the re-invite in t38 from the provider. 
In dialplan i have: <action application="export"
data="t38_passthru=true"/>


The invite from the provider is:

INVITE sip:gw+TRUNKIP at 10.10.1.254:5060;transport=udp;gw=TRUNKIP SIP/2.0
Via: SIP/2.0/UDP
10.10.1.1:5060;branch=z9hG4bKno6j3r305os1nm4ph2a1sb0000010.1
Call-ID: badda7ee-3980-1231-8db4-b4b52f5e67f8
From: <sip:4774 at 10.10.1.1:5060>;tag=dg2aai02-CC-52
To: "5313" <sip:nousername at 10.10.1.254:5060>;tag=t6DB42KFXarmN
CSeq: 2 INVITE
Contact: <sip:4774 at 10.10.1.1:5060;transport=udp>
Max-Forwards: 69
Content-Length: 437
Content-Type: application/sdp

v=0
o=HuaweiSoftX3000 38317113 38317116 IN IP4 10.10.1.2
s=Sip Call
c=IN IP4 10.10.1.2
t=0 0
m=image 29090 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxUdpEC:t38UDPRedundancy
m=audio 34264 RTP/AVP 8 0 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=ptime:20
a=silenceSupp:off - - - -
a=ecan:fb on -
a=X-fax
a=fmtp:101 0-15


And the invite sent to the ATA is:

INVITE sip:5313 at 192.168.1.97:5060;ref=5313 SIP/2.0
Via: SIP/2.0/UDP 10.10.1.254;rport;branch=z9hG4bK87p0gpcv4p31g
Max-Forwards: 70
From: <sip:4774 at sipdomain.net>;tag=mKN5ZFeQ19XDr
To: "5313" <sip:5313 at sipdomain.net>;tag=5de97158a7c051b0o0
Call-ID: 6aa68878-1a412510 at 192.168.1.97
CSeq: 44056889 INVITE
Contact: <sip:4774 at 10.10.1.254:5060;transport=udp>
User-Agent: suvoz
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE,
REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE
Supported: precondition, path, replaces
Content-Type: application/sdp
Content-Disposition: session
Content-Length: 291

v=0
o=FreeSWITCH 1368772703 1368772705 IN IP4 10.10.1.254
s=FreeSWITCH
c=IN IP4 10.10.1.254
t=0 0
m=image 13196 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:500
a=T38FaxMaxDatagram:500
a=T38FaxUdpEC:t38UDPRedundancy


As you can see the audio part is not send to the ata.

I understand that is another "call" between the ATA and FS, but should
FS send an invite to the ATA containing a audio part as well?

I'm not sure that is a bug or Is the normal behavior? should i open a
jira for it?


Searching for previous issues i found this, but there was no reply ...
http://freeswitch-users.2379917.n2.nabble.com/Doubts-about-T38-passthru-td7582305.html


Thanks for the help,
António

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