UAC                   UAS
       | session established |
       |<===================>|
       |                     |
       | F1  re-INVITE (SDP) |
       |-------------------->|
       | F2 1xx-rel (SDP)    |
       |<--------------------|
       | F3   UPDATE         |
       |<--------------------| Target refreshing
       | F4 2xx UPT          |
       |-------------------->|
       |                     |
       | F5/6 Cancel/200OK   |
       |-------------------->|
       | F7    487 INV       |
       |<--------------------|
       | F7     ACK          |
       |-------------------->|
       | F8  re-INVITE (SDP) |
       |-------------------->| Using which dialog state

F3/F4 is about target refreshing.

And if UAC sends Cancel, UAS sends 487. The first Re-INVITE is discarded.

But if UAC sends another Re-INVITE, which dialog state should it use?

I think is the one refreshed by F3. That's the merit of regarding 
UPDATE/200OK's atomicity.



--------------------------------------------------------
ZTE Information Security Notice: The information contained in this mail is 
solely property of the sender's organization. This mail communication is 
confidential. Recipients named above are obligated to maintain secrecy and are 
not permitted to disclose the contents of this communication to others.
This email and any files transmitted with it are confidential and intended 
solely for the use of the individual or entity to whom they are addressed. If 
you have received this email in error please notify the originator of the 
message. Any views expressed in this message are those of the individual sender.
This message has been scanned for viruses and Spam by ZTE Anti-Spam system.
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email protected] for questions on current sip
Use [email protected] for new developments on the application of sip

Reply via email to