[Asterisk-Dev] T.38 pass-through / T.38 support

Matthew Boehm mboehm at cytelcom.com
Mon Jun 6 11:09:38 MST 2005 

Kevin P. Fleming wrote:

> I too am wondering just how Matthew Boehm's system is working; as of
> this point, a T.38 call of any form (RTP or UDPTL) can't be handled by
> chan_sip, and an existing call can't turn into T.38 either.

OK. Test call. This call came from PSTN -> PRI -> Cisco 5300
(22.22.22.22) -> Asterisk (33.33.33.33) -> ATA (44.44.44.44 NAT'd to
192.168.0.20)

cisco> show call active voice compact
G148A  ANS     T29    t38         TELE  P2819870065
G148A  ORG     T29    t38         VOIP  P2815692770    33.33.33.33:18056

A very very very very long SIP debug of the entire call:

    http://www.cytelcom.net/drmac/fax_trace.txt

Here is the short version:

    -- Executing Goto("SIP/22.22.22.22-4080d3e0","5000008|2815692770|1") in
new stack
    -- Goto (5000008,2815692770,1)
    -- Executing Goto("SIP/22.22.22.22-4080d3e0", "20|1") in new stack
    -- Goto (5000008,20,1)
    -- Executing Dial("SIP/22.22.22.22-4080d3e0", "SIP/TEI20|15") in new
stack
    -- Called TEI20
    -- SIP/TEI20-5556 is ringing
    -- SIP/TEI20-5556 answered SIP/22.22.22.22-4080d3e0
    -- Attempting native bridge of SIP/22.22.22.22-4080d3e0 and
SIP/TEI20-5556
Jun  6 10:09:40 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:40 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:41 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:41 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:42 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:42 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:43 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:43 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:44 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:44 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:45 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:45 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:46 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:47 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:47 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:48 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:48 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:49 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:49 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:50 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:50 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:51 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:51 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 16806 udptl t38
Jun  6 10:09:51 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:52 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:52 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:53 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:53 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:54 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:54 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:55 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:55 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:56 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:56 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:57 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:57 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:58 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:58 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
Jun  6 10:09:59 WARNING[14277]: chan_sip.c:3063 process_sdp: Unknown SDP
media type in offer: image 49170 udptl t38
<*** call complete ***>
cytrex*CLI> sip show channels
Peer             User/ANR    Call ID      Seq (Tx/Rx)   Format  Last Msg
192.168.0.20     (None)      1153024370@  00101/00138   unknow  Rx:
REGISTER 192.168.0.20     TEI20       6eb51a3f676  00102/00076   ulaw
(d)       Rx: ACK
22.22.22.22      9792979098  166F146B-D5  00101/00103   ulaw  (d)
Rx: ACK

I think Steve will be interested in this part:

INVITE sip:2819870065 at 33.33.33.33 SIP/2.0
Via: SIP/2.0/UDP 192.168.0.20:5060;branch=z9hG4bK441433602
From: <sip:TEI20 at 192.168.0.20:5060>;tag=2311634843
To: "2819870065" <sip:2819870065 at 33.33.33.33>;tag=as40e02db9
Call-ID: 74839a6a27d23cbf15e2441c677e51e4 at 33.33.33.33
CSeq: 9 INVITE
Contact: <sip:TEI20 at 192.168.0.20:5060>
max-forwards: 70
user-agent: Azacall200 V1.5.7-RC14
Allow: INVITE, ACK, OPTIONS, CANCEL, BYE
Content-Type: application/sdp
Content-Length:   258

v=0
o=- 108 3480 IN IP4 192.168.0.20
s=-
c=IN IP4 192.168.0.20
t=0 0
m=image 49170 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:0
a=T38FaxMaxDatagram:176
a=T38FaxUdpEC:t38UDPRedundancy

-Matthew
-- 
------------------------------------------------------------------------
Matthew Boehm, IT Director                    Cypress Telecommunications
mboehm at cytelcom.com                   3838 N. Sam Houston Parkway E #400
T: 832-200-8640 x3044                                  Houston, TX 77032

My girlfriend was recently diagnosed with multiple personality disorder;
 When she called yesterday, my CallerID box exploded.
------------------------------------------------------------------------

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