Richard,

Notwithstanding what Paul sent, I am confused by your original question,
because INVITE F4 does NOT contain a To tag, so there is no dialog. The
first dialog-forming response leads to a different dialog, because the
To tag is different from that in the 302.

John

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On 
> Behalf Of Paul Kyzivat
> Sent: 14 March 2008 16:26
> To: Richard Good
> Cc: [email protected]
> Subject: Re: [Sip] 302 Support in RFC 3665
> 
> 
> 
> Richard Good wrote:
> > Hi,
> > 
> > I have a query regarding the 302 (Temporarily Moved) 
> message flow shown 
> > in RFC 3665.
> > 
> > Essentially if a SIP client receives a 302 message in 
> response to an 
> > INVITE  it should ACK this message and then using the 
> address in the 
> > contact field send a new INVITE request.
> > 
> > In the message flow shown in RFC 3665 (see section 3.6. Session via 
> > Redirect and Proxy Servers with SDP in ACK) the new INVITE 
> request has 
> > the same To field, From field, To Tag and Call ID - the 
> Request URI uses 
> > the address specified in the Contact field of the 302 response.  
> > Essentially this new INVITE is part of the same dialog but has a 
> > different Request URI.
> > 
> > My questions are: Is the 302 response not a final response? 
> Does it not 
> > end the dialog? Shouldn't the new INVITE have new Call ID, 
> tags etc. and 
> > shouldn't the address from the Contact field be in the 
> Request URI and 
> > To field of the new INVITE request?
> 
> See 3261 section 8.1.3.4. Using the same To, From, and Call-Id is 
> *recommended*, but not required.
> 
> Note that if the 3xx recursion is done by a proxy along the 
> path it must 
> be this way, so it seems harmless for the UAC to do as a proxy would.
> 
> OTOH, there are cases when it would be good for the To-URI to be 
> updated. For instance, if a UAC counts on a proxy at the originating 
> side to expand certain URIs, such as speed dial numbers, it would be 
> good to do so by redirection, and for the UAC to put the 
> expanded number 
> into the To-URI, so that the callee will have a clue of where 
> the call 
> was intended to go. But doing this seems to require some 
> indication that 
> this is intended - e.g. a special 3xx code for the purpose.
> 
>       Paul
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