> Let's imagine the case for Automatic Callback. User A calls user B but
> he is busy. When user B hangs up, user A is alerted.
> What I don't understand here is how A can send a SUBSCRIBE which
> contains the call-id, to-tag and from-tag of B's dialog with another
> user in order to be alerted to the end of that conversation.
> How can A be aware of this information?

User A need not to know dialog information of User B. USer A sends SUBSCRIBE 
and when user B becomes available, sends NOTIFY to user A. On this user A could 
send INVITE to B. Dialog ID of SUBSCRIBE has no relation with that of INVITE.

Vipul Rastogi
Engineer, Business Management Team
Telecommunication Network Business
Samsung Electronics CO, LTD
Suwon P.O.BOX 105, 416
Korea 442-600
MO 010-9530-0354
----- Original Message ----- 
From: "Rosa Maria Martinez Perallon" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, January 23, 2008 1:00 AM
Subject: [Sip-implementors] Call-id for Dialog event package


> Hello,
> I have checked the RFC 4235 about the Dialog Event package and there is
> something that I don't understand.
> 
> The paper claims that a subscription MUST contain the next parameters:
> call-id, to-tag, from-tag.
> 
> Let's imagine the case for Automatic Callback. User A calls user B but
> he is busy. When user B hangs up, user A is alerted.
> What I don't understand here is how A can send a SUBSCRIBE which
> contains the call-id, to-tag and from-tag of B's dialog with another
> user in order to be alerted to the end of that conversation.
> How can A be aware of this information?
> 
> Thanks
> _______________________________________________
> Sip-implementors mailing list
> [email protected]
> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors

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