Hi All, Excited to see mention of T.38 passthru with 1.4.0.... BUT it seems like "Emperor's New Clothes" from my perspective. As I understand it, T.38 passthru only works via a re-invite mechanism - so two T.38 devices try talking fax and request a T.38 media stream. Asterisk is now savvy enough to realise it can't do it, so opts out - "Hey Guys, I don't know diddly squat about T.38, so why don't you two just talk to eachother and leave me out of it." That's great if you don't need to know about when the call ended, but for those that do, I assume that it's not a viable solution. Is my understanding correct? Alex Lake
Notwithstanding that lot above, I would like to try T.38 but it didn't quite work the way I was hoping. I've got calls coming in on a context "gamma" and am sending them out on a context "gamma-OUT". I've put the following into each SIP peer definition: canreinvite = yes t38pt_udptl = yes However, when I place a call to a fax machine, I get the following message: WARNING[13698]: chan_sip.c:4691 process_sdp: Unsupported SDP media type in offer: image 28326 udptl t38 The full exchange is shown below. Thanks for any light anyone can shed on this! Rgds, Alex PS - Let me know if there's a better way to put all this stuff in a posting. ------------------- INVITE sip:442070173460@89.202.128.200 SIP/2.0 Max-Forwards: 69 Session-Expires: 3600;Refresher=uac Supported: timer To: "442070173460" <sip:442070173460@89.202.128.200>;tag=as0cfcd0f2 From: <sip:442070600003@83.245.6.83>;tag=3373030299-438089 Call-ID: 2b91c1ee563365b54ae5d9ad53df4855@89.202.128.200 CSeq: 2 INVITE Via: SIP/2.0/UDP 83.245.6.83:5060;branch=z9hG4bK58ebba15bca29d9c48091635d0a0f023 Contact: sip:442070600003@83.245.6.83:5060 Allow-Events: telephone-event Content-Type: application/sdp Content-Length: 344 v=0 o=msw 4535 11 IN IP4 83.245.6.83 s=sip call c=IN IP4 83.245.6.84 t=0 0 m=image 28326 udptl t38 a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxMaxDatagram:72 a=T38FaxMaxBuffer:200 a=T38FaxRateManagement:transferredTCF a=T38FaxTranscodingJBIG:0 a=T38FaxTranscodingMMR:0 a=T38FaxFillBitRemoval:0 a=T38MaxBitRate:14400 a=T38FaxVersion:0 <-------------> --- (13 headers 15 lines) --- Sending to 83.245.6.83 : 5060 (no NAT) [Nov 20 16:51:40] WARNING[13698]: chan_sip.c:4691 process_sdp: Unsupported SDP media type in offer: image 28326 udptl t38 <--- Transmitting (no NAT) to 83.245.6.83:5060 ---> SIP/2.0 488 Not acceptable here....