[asterisk-bugs] [Asterisk 0012437]: Asterisk negotiates only T.38 when answering even if the other end offers audio

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
====================================================================== 
http://bugs.digium.com/view.php?id=12437 
====================================================================== 
Reported By:                marsosa
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   12437
Category:                   Channels/chan_sip/T.38
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     confirmed
Asterisk Version:           1.4.18 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Disclaimer on File?:        N/A 
Request Review:              
====================================================================== 
Date Submitted:             04-14-2008 08:31 CDT
Last Modified:              07-22-2008 18:20 CDT
====================================================================== 
Summary:                    Asterisk negotiates only T.38 when answering even if
the other end offers audio
Description: 
One of our gateways (audiocodes mp-118) offers ulaw,g729 and t.38 when an
incoming call is sent to asterisk, and asterisk answer() with t.38 only,
instead of using ulaw. T.38 is enabled on the gateway because this is
needed for reinvites, if i disable it, the call works ok but fails later
when the ata wants to do reinvite for receiving faxes with t.38 '488 not
acceptable'.
The main problem here is that, after answering with t.38, asterisk sends
invites with t.38 only to the ip phones, and they rejected with not
acceptable.
====================================================================== 

---------------------------------------------------------------------- 
 mazhar996 - 07-22-08 18:20  
---------------------------------------------------------------------- 
Hi there,
    I have exactly the same problem with TELES.iSWITCH , TELES offers T.38
in the initial invite and Asterisk negotiates T.38, this causes a voice
call to fail. Even IVRs could not be played.
     Its hard for me to convence my provider to enable T.38 but negotiate
it in the reinvite instead of initial invite. They say thats their
standard, either they can enable it on the whole or not at all.
      Please let me know if there is some fix. 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
07-22-08 18:20  mazhar996      Note Added: 0090585                          
======================================================================