[asterisk-users] Sending faxes with T.38 problem. Asterisk - 1.6.0.6

[Joshua Colp]

----- "Santiago Gimeno" <santiago.gimeno at gmail.com> wrote:

> Hello,
> 
> I'm having difficulties to make Asterisk (1.6.0.6) interoperate
> correctly with a CISCO mediaGW in order to send faxes to the PSTN
> using T.38.
> 
> When Asterisk sends the initial INVITE containing the T.38 media offer
> in the SDP, the CISCO answers with a 488 Not Acceptable Media.
> Apparently, it looks like a configuration problem in the CISCO, but I
> have tested the CISCO with the Zoiper client and it successfully sends
> faxes. The only difference I have noticed between the Asterisk and
> Zoiper is that whereas the Asterisk sends the T.38 SDP information in
> the initial INVITE, Zoiper establishes a voice call first and then
> re-negotiates(with a re-INVITE) the session in order to send the T.38
> media.
> Is it possible to make Asterisk work like this? or is this a problem
> in the configuration of the CISCO? Any ideas?

The issue here is receiving T38 in the initial INVITE of the incoming call. Right now
this causes the entire leg to be negotiated with T38, and the subsequent outgoing INVITE
to also get sent with only T38.

This was filed as an issue and is being tracked at http://bugs.digium.com/view.php?id=12437. Thus far
I have created a branch for Asterisk 1.4 that changes the behavior to accept the incoming INVITE with
either audio and T38, or only T38 (if we only got T38). The outgoing call initially goes out as audio until
T38 kicks in and it is reinvited to T38. This seems to work the best.

Since you are using 1.6.0 I will make some time to create a branch with the changes in it based off of 1.6.0 so
I can get further testing.

-- 
Joshua Colp
Digium, Inc. | Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at:  www.digium.com  & www.asterisk.org