Hi All, I've been testing reliability with t.38 faxing pass through with * 1.4.21.1, Linksys ATA's 2102 x 2, Sharp UX-B800SE and Cannon ImageClass D880. cannon> <2102 #1> <SIP> <*> <SIP> <2102 #2> <sharp Started out with default settings on all devices, configured Asterisk to handle T.38 pass through, the configuration I believe is solid. I get relaiable results faxing from the sharp to the cannon. I get intermittent results, 50% success or failure, faxing from cannon to sharp. The first thing I did was to switch the faxes, so the ATA's and Asterisk remain the same, just switched the faxes to the oposite end of the path. Doing this comfirmed the original results, sharp to cannon is reliable, cannon to sharp is unreliable. What I observe faxing from sharp to cannon: path sets up as ulaw RTP, cannon answers, RTP switched to UDPTL, fax completes Faxing from cannon to sharp: path sets up as ulaw RTP, sharp answers, RTP switches to UDPTL only half the time when UDPTL is active, fax completes, when the path stays with RTP, fax always fails If I understand correctly, Asterisk switches the media stream to UDPTL when it hears valid fax tones on each side of the path, if it only detects fax tones on 1 path leg, then it keeps the media path through RTP. Or is the mechanism switching to UDPTL in the SIP headers? So, I adjusted db levels on the FXS ports, higher and lower, no effect. I increased jitter, reduced jitter, disabled jitter, no effect. Ensured echo can's were off, no effect. Manually set faxes to 14.4bps, ecm off, no effect. Even switched telephone cord, no effect. On these Linksys 2102's, you can predial #99 to force the ATA to enable fax t.38, this works and is reliable, no RTP is setup, just UDPTL. So my question is this: Can I setup Asterisk to only allow t.38 pass through from these ATA's, without the need to use the #99 in every dial string from the fax machine? Thanks. JR -- --------------------- JR Richardson Engineering for the Masses -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20080811/440d7dad/attachment.htm
Andrew Kohlsmith (lists)
2008-Aug-12 02:01 UTC
[asterisk-users] Intermittent T.38 pass through
On August 11, 2008 06:59:23 pm JR Richardson wrote:> So my question is this: Can I setup Asterisk to only allow t.38 pass > through from these ATA's, without the need to use the #99 in every dial > string from the fax machine?Can you use disallow/allow with UDPTL? I'm not sure, I've never played with this before. -A.