<br><br><div class="gmail_quote">2009/3/20 Klaus Darilion <span dir="ltr"><<a href="mailto:klaus.mailinglists@pernau.at">klaus.mailinglists@pernau.at</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<br>
Steve Underwood schrieb:<br>
<div class="im">> Hi Olivier,<br>
><br>
> Olivier wrote:<br>
>> T.38 says that if the call starts in audio mode it is the called end<br>
>> which should initiate a re-invite to change from audio to T.38. This<br>
>> makes sense, as that is the end which has the best chance of figuring<br>
>> out if a FAX machine answers the call. In practice many T.38<br>
>> implementations will send out a re-invite when they are the calling<br>
>> side, so any practical implementation has to allow for this.<br>
>> Clashes are<br>
>> possible, if both ends send re-invite, and this is not always handled<br>
>> properly<br>
>><br>
>><br>
>> Yesterday, with 2 consecutive sendings on the same setup (same fax<br>
>> file, same ATAs, same servers), on the first try, I've seen the<br>
>> reINVITE coming from callee on from the caller on the second try.<br>
>> I don't remember I changed anything between both tries (though I may<br>
>> have done without noticing this).<br>
> That is what typically what happens when the calling end doesn't obey<br>
> the spec. It comes down to a race for who initiates the re-invite first.<br>
> If you are lucky the two ends sort themselves out. If you are unlucky<br>
> you end up with both ends re-inviting, and you may get a call failure.<br>
<br>
</div>This is what I see very often - both sides send reINVITE (overlapping),<br>
both sides reject with 491 (request pending) with the result that the<br>
switch to T.38 failed. I have only once seen handling overlapping<br>
reINVITEs smart (ComISDN client)<br>
<br>
Theoretically it would be perfect if the reINVITE is always triggered by<br>
the callee (as the spec says) - but there are ATAs which need up to 15<br>
seconds to detect a fax and send reINVITE - and in this cases you<br>
sometimes have to work around by allowing the caller to send reINVITE too.</blockquote><div><br>Linksys 3102 have an option specifying if reINVITE should be inbound, outbound or both.<br>Unfortunately, I couldn't find this option in Patton SmartNodes.<br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
<br>
regards<br>
<font color="#888888">Klaus<br>
</font><div><div></div><div class="h5"><br>
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