[SIPForum-techwg] Could to-tag in 200 OK response be differentwith the to-tag in 180 ringing?

[라스토기]

Hi,
 I don't thing there is any problem. 180 rining is just provisiong message and as of yet dialong is not made. 200 makes a dialog. so in case 180 & 200 OK has different to-tag, EP should ignore 180 to-tag & make dialog with 200 OK to-tag. 
Hope this will work for you,
bye
vipul rastogi

Engineer, Business Management Team


----- Original Message ----- 
From: "mike xu" <clumsguy at gmail.com>
To: "Dale Worley" <dworley at pingtel.com>
Cc: <techwg at sipforum.org>
Sent: Monday, July 30, 2007 11:37 AM
Subject: Re: [SIPForum-techwg] Could to-tag in 200 OK response be differentwith the to-tag in 180 ringing?


> Hi Dale,
> 
> Thank you for your reply.
> It seems that the transaction/dialog match part in the UAC which I
> used need to be enhanced to deal with such "forking" case.
> 
> Thanks again,
> Mike
> 
> On 7/27/07, Dale Worley <dworley at pingtel.com> wrote:
>> On Fri, 2007-07-27 at 12:49 +0800, mike xu wrote:
>> > Do you know that in RFC3261, could the to-tag in 200 OK be different
>> > with the one in 180 ringing?
>>
>> It is allowed, but it does not mean what you might expect.  Each to-tag
>> represents one dialog.  The 180 has a to-tag value, and it is part of a
>> dialog.  The 200 has a different to-tag value, and so it is part of a
>> *different* dialog.  The 180's dialog never succeeds (because the dialog
>> never returns a 200 response), and eventually the UAC deletes knowledge
>> of it.  So from the UAC's point of view, this is an example of forking.
>> (In general, a UAC must be able to track multiple early dialogs until it
>> receives a 200.  After that, it may also receive 200 responses for other
>> forks of the INVITE, which it must either handle or terminate by sending
>> BYE.
>>
>> > Below is the case which I met, in step F1 (180 ringing), callee
>> > generated one to-tag (46bf8) while in step F2 (200 OK) the sip server
>> > generates a new to-tag which is "as5123fc8f", and my sip endpoint
>> > didn't match this 200 OK response, the sip server will resend 200 OK
>> > and I obveriously couldn't hear the voice mail info.
>> >
>> >    Caller        SIP_SERVER       Callee
>> >      |                |              |
>> >      |       INVITE    |             |
>> >      |------------->|  INVITE      |
>> >      |    (100 Trying)  |----------->|
>> >      |<-------------|              |
>> >      |                |180 Ringing F1 |
>> >      |   180 Ringing   |<-----------|
>> >      |<-------------|              |
>> >      |                |   CANCEL     |
>> >      |                |----------->|
>> >      |                |   200 OK     |
>> >      |                |<-----------|
>> >      |                |487 Req Cancel |
>> >      |                |<------------|
>> >      |                |     ACK       |
>> >      |                |------------>|
>> >      |200 OK(SIP/SDP) F2|               |
>> >      |<-------------|               |
>> >      |    ACK         |               |
>> >      |------------->|               |
>> >      | voicemail RTP   |               |
>> >      |<===============||               |
>> >
>> > Does any body know that the new to-tag in F2's 200 OK response is
>> > valid or invalid? Does it comply to RFC3261?
>>
>> It looks like SIP_SERVER is doing what it should -- the 200 is
>> establishing a different dialog than the one that the 180 was reporting
>> on.
>>
>> Dale
>>
>>
>>
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