Jon Schøpzinsky
2009-May-13 07:30 UTC
[asterisk-users] Asterisk 1.6 T.38 generation towards a Cisco voice router
Hello List. We are having some problems using t.38 together with a Cisco voice router at one of our providers end. We are using the new digium asterisk fax module to generate the fax, and when we use together with our internal Audiocodes Mediant 2000 gateways, we have no issues what so ever, and the faxes go right through. When we send faxes to our other provider, who has cisco hardware at their end, we get this error: -- Channel 'SIP/xxx.xxxxxx.se-08aaf470' fax session '0', [ 006.607923 ], STAT_EVT_HW_CLOSE st: WT_HW_CLS rt: WCLSNCLS -- Channel 'SIP/xxx.xxxxxx.se-08aaf470' fax session '0', [ 006.608118 ], STAT_SES_COMPLETE -- Channel 'SIP/xxx.xxxxxx.se-08aaf470' fax session '0' is complete, result: 'SUCCESS' (FAX_NO_FAX), error: 'CANCELED', pages: 0, resolution: 'unknown', transfer rate: '2400', remoteSID: '' [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:32] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:33] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:33] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short [Apr 23 15:30:33] WARNING[31839]: rtp.c:1434 ast_rtp_read: RTP Read too short I can see that asterisk discards all RTP T.38 packets sent from the provider, which the error message also indicates. Is there a known problem, connecting to cisco hardware using t.38 in Asterisk 1.6? or does anybody know of a patch that fixes this problem? I can see that in the end of the T.38 packet, cisco adds 4 zero fields, which are not in the packets that Asterisk sends. Is this some weird "we-are-cisco-and-therefore-decide-how-the-packets-should-look"? Kind Regards Jon Leren Sch?pzinsky Systems Architect Firstcom A/S B?dehavnsgade 2C, 2. 2450 K?benhavn SV Web: http://www.firstcom.dk <http://www.firstcom.dk> -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20090513/343b7853/attachment-0001.htm
David Backeberg
2009-May-13 12:12 UTC
[asterisk-users] Asterisk 1.6 T.38 generation towards a Cisco voice router
On Wed, May 13, 2009 at 3:30 AM, Jon Sch?pzinsky <jos at firstcom.dk> wrote:> We are having some problems using t.38 together with a Cisco voice router at > one of our providers end. > > We are using the new digium asterisk fax module to generate the fax, and > when we use together with our internal Audiocodes Mediant 2000 gateways, we > have no issues what so ever, and the faxes go right through. > I can see that asterisk discards all RTP T.38 packets sent from the > provider, which the error message also indicates. > > Is there a known problem, connecting to cisco hardware using t.38 in > Asterisk 1.6? or does anybody know of a patch that fixes this problem?I doubt that there is a known problem, as I'm using Cisco with asterisk and T.38 and having success. Do you have full control over the Cisco gear? Please post the dialpeer info from the Cisco gear and I'll take a look at it. You can also go back through the archives for similar posts because we've discussed this a few times in the last few months. Among other things, I saw that your fax tried to transmit at 2400bps. The gear should be able to support 9600. So that's already fishy. What happens if you try to send a 'normal' audio fax over voip through that gear? Some things you should know: * do not compress voip faxes. Faxes are already compressed. If you try to use a compression codec you'll wreck the fax. * on the cisco dialpeer be darn sure that you've turned off vad * for sip on asterisk, you need to enable reinvite, and you also need to configure a t38pt_udptl = yes entry in your sip.conf, but you probably already to that right if you were T.38-ing to the other gear. Are you sure you weren't just sending a normal audio fax to the other gear?