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,UPDATE,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;privacy=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;privacy=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]
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