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

[Kristijan Vrban]

I took a look into 1.6 source. 1.6 does a re-re-INVITE to audio after
its T.38 re-INVITE failed. A backport is simple. But i think in
allready know the answer. No, this is a new feature, no new features
into 1.4 So one more backport patch into my patch folder for my
asterisk 1.5 :)

kristijan

2010/1/13 Kevin P. Fleming <kpfleming at digium.com>:
> 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
>
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