[asterisk-dev] fallback to audio faxing when T.38 INVITE fail with 488/606 Not acceptable

[Kevin P. Fleming]

Kristijan Vrban wrote:
>> However, the original message was a bit unclear if it was a re-invite or an invite.
> re-invite
> 
> And there is no difference if chan_sip get a 488 or 606 for the T.38
> re-INVITE (both are valid response) . As far as i can see, there is
> simply no logic that handle a fallback to audio fax when the caller
> can not handle T.38? I examined how a Cisco/Linksys SPA2120 handel
> this: It ACK the 488/606 for its rejected T.38 re-INVITE and send a
> re-re-INVITE with PCMU, and then the fax is transported via audio RTP.

If Asterisk sends a re-INVITE to T.38, and the other end rejects it,
there is nothing to be done to 'fallback' to audio mode; the call is
still in audio mode, because it never left audio mode.

Also, you are doing this testing with Asterisk 1.4, which has very
limited support for T.38; the T.38 support in Asterisk 1.6.x is vastly
improved, and I'd highly encourage you to use instead if you can.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kpfleming at digium.com
Check us out at www.digium.com & www.asterisk.org