Asterisk support for T.38 passthrough

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Asterisk support for T.38 passthrough

Postby mininfo » Wed Nov 11, 2015 3:34 pm

Hi

I am trying to get my VTA-VR to actually use T.38 to fax out. I tested with 2 VTA-VRs connected to my asterisk server (1 to a 56k USR modem, 1 to an old HP 3200 Fax/Laser printer) I have enabled t.38 passthru and have enabled the T.38 in VTA-VR, but have noticed that the invite looks a little non-standard. The VTA-VR sends out m=audio a=rtpmap:110 t38-udp/8000 instead of just .... t38/8000

Most of the t38 invites I saw post related to asterisk has the m=image 4908 udptl t38 format, this appears to be defined in (RFC 3363, 2002)

Does anyone know if audio/t38 (RFC 4612, 2006) is/will be supported, and if yes, can it be modified to allow for t38-rtp , t38-udp media types?

For the below messages, 192.168.0.6 is VTA-VR on the HPLJ 3200. 192.168.0.7 is VTA-VR connected to USR modem/Windows XP. 192.168.0.14 is Asterisk in between.

Thanks

INVITE sip:102@192.168.0.14;transport=UDP SIP/2.0
From: "101"<sip:101@192.168.0.14>;tag=101a20f0-600a8c0-2710-563344c7-5f396ffa-563344c7
To: <sip:102@192.168.0.14>
Call-ID: 101a7f88-600a8c0-2710-563344c7-5800168d-563344c7@192.168.0.14
CSeq: 1 INVITE
Via: SIP/2.0/UDP 192.168.0.6:10000;branch=z9hG4bK-563344c7-b844a9c1-62b53ffb
Max-Forwards: 70
Supported: replaces,timer,100rel
User-Agent: VTA0015E9BCD2F111.4.1-r060815-1.00.09-20070402170142 CYT
Contact: <sip:101@192.168.0.6:10000;transport=UDP>
Min-SE: 0
Content-Type: application/sdp
Content-Length: 420

v=0
o=a0000 8645 6672 IN IP4 192.168.0.6
s=SIP Call
c=IN IP4 192.168.0.6
t=0 0
m=audio 10052 RTP/AVP 0 101 8 20 21 23 22 18 4 110
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:20 G726-32/8000
a=rtpmap:21 G726-40/8000
a=rtpmap:23 G726-16/8000
a=rtpmap:22 G726-24/8000
a=rtpmap:18 G729/8000
a=rtpmap:4 G723/8000
a=rtpmap:110 t38-udp/8000
a=fmtp:101 0-15
a=sendrecv



======


INVITE sip:102@192.168.0.7:10000;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 192.168.0.14:10000;branch=z9hG4bK50fa4ac4
Max-Forwards: 70
From: "Min Xu" <sip:101@192.168.0.14:10000>;tag=as48bce321
To: <sip:102@192.168.0.7:10000;transport=UDP>
Contact: <sip:101@192.168.0.14:10000>
Call-ID: 4350fce359016bd45c986eaf3be233b9@192.168.0.14:10000
CSeq: 102 INVITE
User-Agent: Asterisk PBX 11.1.2
Date: Fri, 30 Oct 2015 10:21:59 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Supported: replaces, timer
Content-Type: application/sdp
Content-Length: 256

v=0
o=root 340997884 340997884 IN IP4 192.168.0.14
s=Asterisk PBX 11.1.2
c=IN IP4 192.168.0.14
t=0 0
m=audio 5006 RTP/AVP 0 8 101
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv
mininfo
Newsterisk
 
Posts: 1
Joined: Fri Oct 30, 2015 3:46 pm

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