Comments inline... Thanks, Nataraju A B
> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sip-implementors- > [EMAIL PROTECTED] On Behalf Of Giancarlo Murino > Sent: Friday, November 03, 2006 2:31 PM > To: [email protected] > Subject: [Sip-implementors] Rules about Call ID, From tag and To tag > > Hi, > > I have a trouble about Call Id, From tag and To tag. On a Web site I read: > > > > Call-ID is so called call identifier. It must be a unique string that > identifies a call. A call consists of one or more dialogsi. Multiple user > agents may respond to a request when a proxy along the path forks the > request. Each user agent that sends a 2xx establishes a separate dialog > with > the caller. All such dialogs are part of the same call and have the same > Call-ID. > > From tag is generated by the caller and it uniquely identifies the dialog > in > the caller's user agent. To tag is generated by a callee and it uniquely > identifies, just like From tag, the dialog in the callee's user agent. > > This hierarchical dialog identifier is necessary because a single call > invitation can create several dialogs and caller must be able to > distinguish > them. > > > > So, if I have understood, if there are parallel dialogs (as in forking > case) > I have to use the same Call-Id , but different to tag and from tag, > because > such dialogs are part of the same call. But if I have two sequencial > dialogs > like in the following flow: > > ------------->INVITE (start first dialog) > > <------------- OK > > --------------> BYE (end first dialog) > > ------------->INVITE (start second dialog) > > <------------- OK > > --------------> BYE (end second dialog) > > Are they a part of the same call, or they belong to two different calls? > According to the definition of call (a call is a group of one or more > dialogs), I think they are a part of the same call. So, must they share > the same Call-ID? If they aren't a part of the same call, why? Giancarlo [ABN] No, it makes a different call. Once the call is terminated though BYE, even if we get a new INVITE with same call-id it would lead to a different call. Because it may not match any of the existing calls in any of the entities... I mean to say, subsequent calls having the same call-id would make a new call, because there exists nothing to make it part of it... _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
