[asterisk-users] Asterisk 1.6 T.38 generation towards a Cisco voice router

[Jon Schøpzinsky]

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 Schøpzinsky

Systems Architect

 

Firstcom A/S

Bådehavnsgade 2C, 2.

2450 København SV

 

Web:  http://www.firstcom.dk <http://www.firstcom.dk> 

 

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