The 183 says "i'm working on it" but doesn't say alerting is happening.
You wouldn't want to generate ringback for a 183, but I suppose you
could generate comfort noise or relay clicking sounds to let the caller
know that something is happening.
Paul
Will Quan wrote:
> Thanks for the responses.
> Sorry, I failed to mention this is *unreliable*.
> Why send a 183 (no SDP) when you can just send the 180? Is there a
> difference?
> I was thinking the 183 maps to an ACM or similar, in which case there is
> only 1.
> -will
>
>
> ------------------------------------------------------------------------
> > Date: Thu, 15 Mar 2007 15:41:58 -0400
> > From: [EMAIL PROTECTED]
> > To: [EMAIL PROTECTED]
> > CC: [email protected]
> > Subject: Re: [Sip-implementors] 183 without SDP
> >
> >
> >
> > Will Quan wrote:
> > > Is it acceptable for a gateway to send a 183 without SDP and then
> one second later send another with SDP?--will
> >
> > If the first 183 is *unreliable*, then yes.
> >
> > If the first 183 is *reliable*, and the SDP in the 2nd 183 is an
> > *answer* then also yes.
> >
> > If the UAS is the one sending an offer (because the UAC didn't), and
> > the first 183 is *reliable*, then it must contain an offer.
> >
> > Paul
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