Subject: RE: [SIP] Discussion

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 2 Nov 2000 00:51:44 -0500

> -----Original Message-----
> From: james jack [mailto:[email-masked]]
> Sent: Friday, October 20, 2000 2:50 AM
> To: [email-masked]
> Subject: [SIP] Discussion
> 
> 
> Hi,All:
>   I have one question to consult, the question is that
> about the 481 Call Leg/Transaction Does Not Exist, on
> RFC2543bis02, which says "This status is returned
> under three conditions: The server received a BYE
> request that does not match any existing call leg, the
> server received a CANCEL request that does not match
> any existing transaction or the server received an
> INVITE with a To tag that does not match the local tag
> value. (A server simply discards an ACK referring to
> an unknown transaction.)" . I can't understand the
> words "or the server received an INVITE with a To tag
> that does not match the local tag value", could
> someone give me some example? According to my known,To
> tag is inserted by UAS or redirect server. which means
> To tag is used in response, how can a INVITE request
> with a To tag?

Subsequent INVITE requests from the caller to called party for the same call
leg carry that tag in the To field. The 481 is sent if a UAS receives a
request with a tag in the To field that it did not previously insert.

-Jonathan R.

---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

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