Subject: [Sip] Refer subscription clarification

From: "Hearty, John" <[email-masked]>
Date: Fri, 6 Dec 2002 20:58:25 -0700

The refer-07 draft states:

"The lifetime of the state being subscribed to is determined by the progress of the referenced request."

If the original dialog that was refered is dropped after the transferee already sent a 202 to the transferor for the Refer, is the subscription still considered alive by the Transferor?  Example flow to illustrate what I'm getting at:

              Transferor           Transferee             Transfer
                   |                    |                  Target
                   |            INVITE  |                    |
         Call-ID:1 |<-------------------|                    |
                   |            200 OK  |                    |
         Call-ID:1 |------------------->|                    |
                   |            ACK     |                    |
         Call-ID:1 |<-------------------|                    |
                   |  INVITE (hold)     |                    |
         Call-ID:1 |------------------->|                    |
                   |  200 OK            |                    |
         Call-ID:1 |<-------------------|                    |
                   |  ACK               |                    |
         Call-ID:1 |------------------->|                    |
                   |  REFER             |                    |
         Call-ID:1 |------------------->|                    |
                   |  202 Accepted      |                    |
         Call-ID:1 |<-------------------|                    |
                   | NOTIFY (100 Trying)|                    |
         Call-ID:1 |<-------------------|                    |
                   |            200 OK  |                    |
         Call-ID:1 |------------------->|                    |
                   |                    |  INVITE            |
         Call-ID:2 |                    |------------------->|
                   |                    |  180               |
         Call-ID:2 |                    |<-------------------|
                   |  BYE               |                    |
         Call-ID:1 |<-------------------|                    |
                   |  200 OK            |                    |
         Call-ID:1 |------------------->|                    |
                   |                    |  CANCEL            |
         Call-ID:2 |                    |------------------->|
                   |                    |  200 OK            |
         Call-ID:2 |                    |<-------------------|
                   |                    |             487    |
         Call-ID:2 |                    |<-------------------|
                   |                    |             ACK    |
         Call-ID:2 |                    |------------------->|

 Is the Transferee expected to still send a Notify at this point?  I presume he is based on the text above, and that the subscription is not over when the Transferor gets the BYE for Call-ID 1.  Please confirm.  I realize the CANCEL of Call-ID:2 should probabally happen before the BYE on Call-ID:1, I have reasons I'd rather not go into why it is happening in the order shown.  Posted to the sip list because I could not find any clear reference to this, and clarification may be needed in the draft.

John Hearty
Level 3
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From: Robert Sparks <[email-masked]>
Date: 07 Dec 2002 09:47:49 -0600

inline

> If the original dialog that was refered is dropped after the transferee already sent a 202 to the transferor for the Refer, is the subscription still considered alive by the Transferor?  Example fl…
I dont know what "the original dialog that was refered" means.
I am assuming from the flow that you are asking this question.
  
   If I send a REFER inside a dialog created by an INVITE, does
   a BYE terminate the subscription?

which is exactly the same question as
  
   If I send a SUBSCRIBE inside a dialog created by an INVITE, does
   a BYE terminate the subscription?

If that's not your question ask again.

The answer to the above question is no - and the answer to your below
question is yes, a NOTIFY is still expected.

If that was your question, then I don't think _this_ draft needs
further clarification. That's a basic use of sip-events question, as
we've discussed on the list many times, and should be clarified there.

RjS