Summary:ASTERISK-16832: T.38 only negotiate 2400 Baud for Faxes
Reporter:Peter Katzmann (pk16208)Labels:
Date Opened:2010-10-19 06:14:29Date Closed:2013-01-15 11:09:45.000-0600
Versions:Frequency of
Description:Asterisk only negotiate a speed of 2400 Baud.
We encountered Problem with one Fax from nashuatec and the service technician told as the we only negotiate 2400 Baud.
We traced this on our patton smartnode 9660 and saw that asterisk ignores the remote request of the remote fax always.


It seems that the ast_control_t38_parameters.rate is not properly initialized with the max baudrate AST_T38_RATE_14400, because asterisk only negotiates to  AST_T38_RATE_2400  what equals to 0 in include/asterisk/frame.h in the enum.

When i reverse the enum (14440 is 0 , 12200 is 1 and so on) than the speed negotiation works as expected
Comments:By: Matt Jordan (mjordan) 2013-01-15 11:09:38.136-0600

T.38 has gotten some major work done to it in 1.8+. Based on my reading of the code, the rate parameter should be initialized to some value so long as the SDP chooses to negotiate T38MaxBitRate. Otherwise, the default will be 2400 baud - but if the far end chooses not to negotiate the rate, then any decision Asterisk would make would potentially be wrong.

The other way this could be a problem is if the other side negotiated "T38maxBitRate" as opposed to "T38MaxBitRate". The attribute was improperly registered with IANA, and Asterisk does not currently recognize the lower case spelling.

I'm going to close this issue out as 're-test with 1.8'. If you find you still have a problem, please contact a bug marshal in #asterisk-bugs and we'll be happy to reopen it for you.

By: Matt Jordan (mjordan) 2013-01-15 11:09:53.966-0600

Per the Asterisk maintenance timeline page at http://www.asterisk.org/asterisk-versions maintenance (bug) support for the 1.4 and 1.6.x branches has ended. For continued maintenance support please move to the 1.8 branch which is a long term support (LTS) branch. For more information about branch support, please see https://wiki.asterisk.org/wiki/display/AST/Asterisk+Versions.  After testing with Asterisk 1.8, if you find this problem has not been resolved, please open a new issue against Asterisk 1.8.