[Freeswitch-users] T.38 three re-invites then bye

Leon de Rooij leon at scarlet-internet.nl
Thu Aug 23 19:08:25 MSD 2012 

Hi all,

I've been having a problem with a new provider with sending them faxes over T.38. I don't think FreeSWITCH is to blame at all, but maybe FS can fix my issue, or someone here can help me find the cause of the problem ?

The call flow is as follows:

CPE
1.1.1.1
     |
    V
2.2.2.2
FreeSWITCH
3.3.3.3
     |
    V
4.4.4.4
Provider

In FreeSWITCH, I've set t38-passthru to true on the profile where the CPE INVITEs to. Further, I'm doing late negotiation (while offering the a-leg codecs to the b-leg and the other way around). RTP is flowing through FS.

In short, this is happening:

CPE -> FS -> Provider		INVITE (with audio PCMA, PCMU codecs)
Provider -> FS -> CPE		200 OK (with audio PCMA)

CPE -> FS -> Provider		reINVITE (with T.38 in SDP)
Provider -> FS -> CPE		200 OK (with T.38 in SDP - although with different error correction, is this a problem?)

Provider -> FS -> CPE		reINVITE (again with T.38 in SDP)
CPE -> FS -> Provider		200 OK (with T.38 in SDP)

CPE -> FS -> Provider		reINVITE (with T.38 in SDP)
Provider -> FS -> CPE		BYE (of course, or it'll loop forever)

Does a setting in FreeSWITCH exist so that it can change the error correction (because both endpoints seem to want a different one ?) Could that be the cause of the problem ?

Hope anyone can help.

Thanks,

Leon





Here's the trace - I left out the tryings, acks, removed some unnecessary sip headers to make things a bit less verbose:


U 2012/08/23 15:34:16.334938 3.3.3.3:5060 -> 4.4.4.4:5060
INVITE sip:+888 at 4.4.4.4 SIP/2.0.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528364 INVITE.
Contact: <sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel>.
Content-Type: application/sdp.
Content-Disposition: session.
Content-Length: 253.
X-Designated-Service: fax/t38.
.
v=0.
o=FreeSWITCH 1345708964 1345708965 IN IP4 3.3.3.3.
s=FreeSWITCH.
c=IN IP4 3.3.3.3.
t=0 0.
m=audio 19892 RTP/AVP 8 0 101 13.
a=rtpmap:8 PCMA/8000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-16.
a=ptime:30.


U 2012/08/23 15:34:18.192303 4.4.4.4:5060 -> 3.3.3.3:5060
SIP/2.0 180 Ringing.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528364 INVITE.
Server: DC-SIP/2.0.
Content-Length: 0.
Contact: <sip:+888 at 4.4.4.4:5060;transport=udp>.
.


U 2012/08/23 15:34:23.904745 4.4.4.4:5060 -> 3.3.3.3:5060
SIP/2.0 200 OK.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528364 INVITE.
Server: DC-SIP/2.0.
Contact: <sip:+888 at 4.4.4.4:5060;transport=udp>.
Content-Type: application/sdp.
Content-Length: 229.
.
v=0.
o=- 3554717663 3554717663 IN IP4 4.4.4.4.
s=-.
c=IN IP4 4.4.4.4.
t=0 0.
m=audio 22054 RTP/AVP 8 101.
a=ptime:30.
a=rtpmap:8 PCMA/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=silenceSupp:off - - - -.


U 2012/08/23 15:34:23.996849 3.3.3.3:5060 -> 4.4.4.4:5060
INVITE sip:+888 at 4.4.4.4:5060;transport=udp SIP/2.0.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528365 INVITE.
Contact: <sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel>.
Content-Type: application/sdp.
Content-Disposition: session.
Content-Length: 339.
X-Designated-Service: fax/t38.
.
v=0.
o=FreeSWITCH 1345708964 1345708966 IN IP4 3.3.3.3.
s=FreeSWITCH.
c=IN IP4 3.3.3.3.
t=0 0.
m=image 19892 udptl t38.
a=T38FaxVersion:0.
a=T38MaxBitRate:14400.
a=T38FaxTranscodingMMR.
a=T38FaxTranscodingJBIG.
a=T38FaxRateManagement:transferredTCF.
a=T38FaxMaxBuffer:500.
a=T38FaxMaxDatagram:512.
a=T38FaxUdpEC:t38UDPFEC.


U 2012/08/23 15:34:24.093598 4.4.4.4:5060 -> 3.3.3.3:5060
SIP/2.0 200 OK.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528365 INVITE.
Server: DC-SIP/2.0.
Contact: <sip:+888 at 4.4.4.4:5060;transport=udp>.
Content-Type: application/sdp.
Content-Length: 272.
.
v=0.
o=- 3554717663 3554717664 IN IP4 4.4.4.4.
s=-.
c=IN IP4 4.4.4.4.
t=0 0.
m=image 22054 udptl t38.
a=T38FaxVersion:0.
a=T38MaxBitRate:14400.
a=T38FaxRateManagement:transferredTCF.
a=T38FaxMaxBuffer:72.
a=T38FaxMaxDatagram:316.
a=T38FaxUdpEC:t38UDPRedundancy.


U 2012/08/23 15:34:33.885255 4.4.4.4:5060 -> 3.3.3.3:5060
INVITE sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel SIP/2.0.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
From: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
To: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
CSeq: 693734809 INVITE.
Contact: <sip:+888 at 4.4.4.4:5060;transport=udp>.
Content-Type: application/sdp.
Content-Length: 272.
.
v=0.
o=- 3554717663 3554717665 IN IP4 4.4.4.4.
s=-.
c=IN IP4 4.4.4.4.
t=0 0.
m=image 22054 udptl t38.
a=T38FaxVersion:0.
a=T38MaxBitRate:14400.
a=T38FaxRateManagement:transferredTCF.
a=T38FaxMaxBuffer:72.
a=T38FaxMaxDatagram:316.
a=T38FaxUdpEC:t38UDPRedundancy.


U 2012/08/23 15:34:33.939092 3.3.3.3:5060 -> 4.4.4.4:5060
SIP/2.0 200 OK.
From: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
To: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 693734809 INVITE.
Contact: <sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel>.
Accept: application/sdp.
Content-Type: application/sdp.
Content-Disposition: session.
Content-Length: 345.
.
v=0.
o=FreeSWITCH 1345708964 1345708967 IN IP4 3.3.3.3.
s=FreeSWITCH.
c=IN IP4 3.3.3.3.
t=0 0.
m=image 19892 udptl t38.
a=T38FaxVersion:0.
a=T38MaxBitRate:14400.
a=T38FaxTranscodingMMR.
a=T38FaxTranscodingJBIG.
a=T38FaxRateManagement:transferredTCF.
a=T38FaxMaxBuffer:72.
a=T38FaxMaxDatagram:512.
a=T38FaxUdpEC:t38UDPRedundancy.


U 2012/08/23 15:34:33.950201 3.3.3.3:5060 -> 4.4.4.4:5060
INVITE sip:+888 at 4.4.4.4:5060;transport=udp SIP/2.0.
From: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
To: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
CSeq: 32528366 INVITE.
Contact: <sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel>.
User-Agent: c4-provider-ims-intx.
Content-Type: application/sdp.
Content-Disposition: session.
Content-Length: 338.
X-Designated-Service: fax/t38.
.
v=0.
o=FreeSWITCH 1345708964 1345708968 IN IP4 3.3.3.3.
s=FreeSWITCH.
c=IN IP4 3.3.3.3.
t=0 0.
m=image 19892 udptl t38.
a=T38FaxVersion:0.
a=T38MaxBitRate:14400.
a=T38FaxTranscodingMMR.
a=T38FaxTranscodingJBIG.
a=T38FaxRateManagement:transferredTCF.
a=T38FaxMaxBuffer:72.
a=T38FaxMaxDatagram:512.
a=T38FaxUdpEC:t38UDPFEC.


U 2012/08/23 15:34:34.043165 4.4.4.4:5060 -> 3.3.3.3:5060
BYE sip:gw+provider-voip-tel at 3.3.3.3:5060;transport=udp;gw=provider-voip-tel SIP/2.0.
Call-ID: 3bf65bb6-ed27-11e1-a810-1d8ba1d695aa.
From: <sip:+888 at 4.4.4.4>;tag=SDkvc5299-1.45.133.551104+1+a1b50004+4166b8ad.
To: "+777" <sip:+777 at provider.voip.tel>;tag=70aprjj2Z1QKK.
CSeq: 693734810 BYE.
Content-Length: 0.
Reason: Q.850; cause=41;text="Temporary failure".
.

Join us at ClueCon 2011 Aug 9-11, 2011
More information about the FreeSWITCH-users mailing list