> About references, the only one is the ITU T.38 Annex D (see > latest T.38/2007 > specs)
Pls note that T.38 is under revision. There's a Draft Amendment to Recommendation ITU-T T.38 in work in ITU-T Q.14/16. Like to point out to new Annex H on "Signalled and provisioned T.38 protocol parameters" > parameters) is actually a common behavior, and even when the > parameters are present nobody care about (included the agent > that sends the parameter!!). I may not comment on such implementations, might be one issue for interop problems. Albrecht > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On > Behalf Of Andrea Rizzi > Sent: Dienstag, 10. Februar 2009 10:20 > To: [email protected] > Subject: Re: [Sip-implementors] T38 FAX flows problem? > > According to your call flow, it appears Broadsoft server acts > in a proprietary way that doesn't fit the usual switchover to > T.38. Here my > opinions: > > Problem 1 > The parameters you mention (and maybe you expect) are all > optional but T38FaxRateManagement, which is the only > mandatory parameter. Btw, from my (unfortunately very long) > experience in troubleshooting fax problems in VoIP networks, > I would strongly suggest you to relax your implementation for > interoperating to the real world. Broadsoft's behavior (just > m line with no > parameters) is actually a common behavior, and even when the > parameters are present nobody care about (included the agent > that sends the parameter!!). > > Problem 2 > Broadsoft server makes the media inactive, so you cannot do > anything else that stopping media. This is definitively a > "funny" behavior from Broadsoft. > I fear that a custom implementation take place, I'm arguing > from the "custom" attribute " a=bsoft: 1 image udptl t38 ", > that looks similar to a capability declaration (RFC3407). I > think that you should ask Broadsoft about, because you're doing right. > > About references, the only one is the ITU T.38 Annex D (see > latest T.38/2007 > specs) > > Andrea > > ------------------------------ > > Message: 2 > Date: Wed, 04 Feb 2009 08:54:22 +0900 > From: junpark <[email protected]> > Subject: [Sip-implementors] T38 FAX flows problem? > To: [email protected] > Message-ID: <02a701c9865a$bcddf050$8a8ff...@magma> > Content-Type: text/plain; charset=us-ascii > > Dear SIP implementors, > > Recently I met some problems in SIP T.38 FAX flows when my > device was working with a commercial network. > Please take a look at the whole SIP flows first, I will explain later. > > Device VOIP-Network > ------- INVITE (audio) --------> > <--------- 200 OK ---------------- > ----------- ACK ----------------> > > ========= audio session ======= > FAX tone detected > and > change to FAX session > > <------- INVITE (t38) ----------- (problem 1) > -------- 200 OK -----------------> > <---------- ACK ----------------- > > ========= t38 fax session ======= > > <---------fax signaling ---------> > ------- FCD Frm num: x --------> fax data transmission > ------- FCD Frm num: x --------> > ------- FCD Frm num: x --------> > ----------- RCP -------------------> > ----------- RCP -------------------> > ----------- RCP -------------------> > > at this moment, re-INVITE had come from VOIP-Network > > <------- INVITE (t38 a=inactive) --- (problem 2) > -------- 200 OK ----------------------> > <---------- ACK ---------------------- > > > I have 2 problems. > #1) when my device got the re-INVITE request to change T38 > fax session, the SDP body is as follows; > > v=0 > o=BroadWorks 147321730 2 IN IP4 10.7.0.74 > s=- > c=IN IP4 10.7.0.74 > t=0 0 > m=image 41432 udptl t38 > a=bsoft: 1 image udptl t38 > > There's no T38 related parameters but "m=image 41432 udptl > t38". There's no version information or baud rate. > I really don't understand if this kind of SDP body is O.K for > T.38 specification. > > > #2) When t38 fax protocol was doing its job, suddenly my > device received re-INVITE request with a=inactive. > Here's SDP body for this case. > > v=0 > o=BroadWorks 147321730 3 IN IP4 10.7.0.74 > s=- > c=IN IP4 0.0.0.0 > t=0 0 > m=image 41432 udptl t38 > a=bsoft: 1 image udptl t38 > a=inactive > > I've never heard of this kind of SIP flows. Do you have any > idea why the VoIP-Network device did send such an re-INVITE request? > At this moment, the FAX session was blocked - i.e. no more > fax data transmission was allowed since a=inactive was come. > And it turned out to be FAX transmission failure. > > These two problems bugs me. I couldn't find out any kind of > RFC or draft related to this problem. > If anyone has an idea for these, please let me know. > > > My best regards, > Jun > > > P.S: I attached whole SIP messages > > UDP SIP Packet(984bytes) Sent ---> 10.7.0.73/5060 INVITE > sip:[email protected] SIP/2.0 > Via: SIP/2.0/UDP > 10.251.242.195:5070;branch=z9hG4bKhsig0000000265AAXzcJzGDMYXEQAAAAAAAA > From: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > To: <sip:[email protected]> > Call-ID: [email protected] > CSeq: 1 INVITE > Contact: <sip:[email protected]:5070> > P-Preferred-Identity: <sip:[email protected]> > Max-Forwards: 70 > Allow: > INVITE,ACK,BYE,CANCEL,NOTIFY,REFER,OPTIONS,SUBSCRIBE,PRACK,UPD > ATE,INFO,MESSA > GE > Supported: 100rel, replaces > User-Agent: Samsung-iBG-SIPUA/2.4.0.3 > Content-Type: application/sdp > Content-Length: 337 > > v=0 > o=89137108 1 1 IN IP4 10.251.242.195 > s=- > c=IN IP4 10.251.242.195 > t=0 0 > m=audio 16438 RTP/AVP 8 18 4 4 2 0 > a=rtpmap:8 PCMA/8000 > a=rtpmap:18 G729/8000 > a=fmtp:18 annexb=no > a=rtpmap:4 G723/8000 > a=fmtp:4 bitrate=6.3;annexa=no > a=rtpmap:4 G723/8000 > a=fmtp:4 bitrate=5.3;annexa=no > a=rtpmap:2 G726-32/8000 > a=rtpmap:0 PCMU/8000 > > Trace Message received from <----- 10.7.0.73/5060 SIP/2.0 100 Trying > Via: SIP/2.0/UDP > 10.251.242.195:5070;branch=z9hG4bKhsig0000000265AAXzcJzGDMYXEQAAAAAAAA > From: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > To: <sip:[email protected]> > Call-ID: [email protected] > CSeq: 1 INVITE > > Trace Message received from <----- 10.7.0.73/5060 SIP/2.0 183 > Session Progress > Via: SIP/2.0/UDP > 10.251.242.195:5070;branch=z9hG4bKhsig0000000265AAXzcJzGDMYXEQAAAAAAAA > From: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > To: <sip:[email protected]>;tag=1281932696-1233246625680 > Call-ID: [email protected] > CSeq: 1 INVITE > Allow: ACK,BYE,CANCEL,INFO,INVITE,OPTIONS,PRACK,REFER,NOTIFY > Supported: > Contact: <sip:[email protected]:5060;transport=udp> > Session: Media > Remote-Party-ID: > <sip:[email protected];user=phone>;screen=yes;party=called;pr > ivacy=off;id-t > ype=subscriber > Content-Type: application/sdp > Content-Length: 145 > > v=0 > o=BroadWorks 143123727 1 IN IP4 10.7.0.74 > s=- > c=IN IP4 10.7.0.74 > t=0 0 > m=audio 42212 RTP/AVP 8 > a=ptime:10 > a=bsoft: 1 image udptl t38 > > Trace Message received from <----- 10.7.0.73/5060 SIP/2.0 200 OK > Via: SIP/2.0/UDP > 10.251.242.195:5070;branch=z9hG4bKhsig0000000265AAXzcJzGDMYXEQAAAAAAAA > From: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > To: <sip:[email protected]>;tag=1281932696-1233246625680 > Call-ID: [email protected] > CSeq: 1 INVITE > Allow: ACK,BYE,CANCEL,INFO,INVITE,OPTIONS,PRACK,REFER,UPDATE,NOTIFY > Supported: > Accept: multipart/mixed,application/media_control+xml,application/sdp > Contact: <sip:[email protected]:5060;transport=udp> > Remote-Party-ID: > <sip:[email protected];user=phone>;screen=yes;party=called;pr > ivacy=off;id-t > ype=subscriber > Content-Type: application/sdp > Content-Length: 145 > > v=0 > o=BroadWorks 143123727 1 IN IP4 10.7.0.74 > s=- > c=IN IP4 10.7.0.74 > t=0 0 > m=audio 42212 RTP/AVP 8 > a=ptime:10 > a=bsoft: 1 image udptl t38 > > Trace Message sent to -----> 10.7.0.73/5060 ACK > sip:[email protected]:5060 SIP/2.0 > Via: SIP/2.0/UDP > 10.251.242.195:5070;branch=z9hG4bK0000000265AAiLgJzPDM8XEgAAAAAAAA > From: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > To: <sip:[email protected]>;tag=1281932696-1233246625680 > Call-ID: [email protected] > CSeq: 1 ACK > Max-Forwards: 70 > User-Agent: Samsung-iBG-SIPUA/2.4.0.3 > Content-Length: 0 > > > > UDP SIP Packet(755bytes) Received <--- 10.7.0.73/5060 INVITE > sip:[email protected]:5070 SIP/2.0 > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sbh87t0d3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505626 INVITE > Contact: <sip:[email protected]:5060;transport=udp> > Allow: ACK,BYE,CANCEL,INFO,INVITE,OPTIONS,PRACK,REFER,UPDATE,NOTIFY > Supported: > Accept: multipart/mixed,application/media_control+xml,application/sdp > Max-Forwards: 9 > Content-Type: application/sdp > Content-Length: 133 > > v=0 > o=BroadWorks 143123727 2 IN IP4 10.7.0.74 > s=- > c=IN IP4 10.7.0.74 > t=0 0 > m=image 42212 udptl t38 > a=bsoft: 1 image udptl t38 > > Trace Message sent to -----> 10.7.0.73/5060 SIP/2.0 200 OK > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sbh87t0d3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505626 INVITE > Contact: <sip:[email protected]:5070> > Content-Type: application/sdp > Content-Length: 218 > > v=0 > o=89137108 1 2 IN IP4 10.251.242.195 > s=- > c=IN IP4 10.251.242.195 > t=0 0 > m=image 16438 udptl t38 > a=T38FaxVersion:0 > a=T38MaxBitRate:14400 > a=T38FaxRateManagement:transferredTCF > a=T38FaxUdpEC:t38UDPRedundancy > > Trace Message received from <----- 10.7.0.73/5060 ACK > sip:[email protected]:5070 SIP/2.0 > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sch87t0d3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505626 ACK > Contact: <sip:[email protected]:5060;transport=udp> > Max-Forwards: 9 > Content-Length: 0 > > > UDP SIP Packet(765bytes) Received <--- 10.7.0.73/5060 INVITE > sip:[email protected]:5070 SIP/2.0 > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sbh87tgd3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505627 INVITE > Contact: <sip:[email protected]:5060;transport=udp> > Allow: ACK,BYE,CANCEL,INFO,INVITE,OPTIONS,PRACK,REFER,UPDATE,NOTIFY > Supported: > Accept: multipart/mixed,application/media_control+xml,application/sdp > Max-Forwards: 9 > Content-Type: application/sdp > Content-Length: 143 > > v=0 > o=BroadWorks 143123727 3 IN IP4 10.7.0.74 > s=- > c=IN IP4 0.0.0.0 > t=0 0 > m=image 42212 udptl t38 > a=bsoft: 1 image udptl t38 > a=inactive > > Trace Message sent to -----> 10.7.0.73/5060 SIP/2.0 200 OK > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sbh87tgd3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505627 INVITE > Contact: <sip:[email protected]:5070> > Content-Type: application/sdp > Content-Length: 230 > > v=0 > o=89137108 1 3 IN IP4 10.251.242.195 > s=- > c=IN IP4 10.251.242.195 > t=0 0 > m=image 16438 udptl t38 > a=T38FaxVersion:0 > a=T38MaxBitRate:14400 > a=T38FaxRateManagement:transferredTCF > a=T38FaxUdpEC:t38UDPRedundancy > a=recvonly > > ACK sip:[email protected]:5070 SIP/2.0 > Via: SIP/2.0/UDP > 10.7.0.73:5060;branch=z9hG4bKg8ejpd10do70mgs145g0sch87tgd3.1 > From: <sip:[email protected]>;tag=1281932696-1233246625680 > To: <sip:[email protected]>;tag=9718bb9b-Nde0-7239063 > Call-ID: [email protected] > CSeq: 295505627 ACK > Contact: <sip:[email protected]:5060;transport=udp> > Max-Forwards: 9 > Content-Length: 0 > > > ___________________________________________ > Hyoungjoon Park (Jun Park) > PMP#504269 > > Senior Engineer > Ubigate Lab > Telecommunication Network Business > Samsung Electronics Co., LTD. > (O) +82-31-279-2343 (F) +82-31-279-5255 (M) +82-10-9530-2343 > email : <mailto:[email protected]> [email protected] > > > > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] 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