To me the issue does not seem to be if there is a single or multiple instances of UA. Pls. consider following argument.
Requirement: Today a user has many un-unified IDs: email address, mobile number, home number, work number, fax number, pager number etc. Although, we all would like to have a single AOR to distribute to our friends e.g. sip:[EMAIL PROTECTED] A UAC sends all kinds of SIP communications to this one AOR. Somehow they should be routed to appropriate application on UAS side. Question: Is there any SIP header/field that specifies "type of service" contained in a SIP request? Note that there may not be any message body in the SIP request. The 'types of services' can be standardized by IANA. Thanks, Kedar -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dale Worley Sent: Monday, July 18, 2005 12:06 PM To: [email protected] Subject: RE: [Sip-implementors] Multiple applications using a single SIP UA > From: Sip Shakers > > My doubt if there is only one instance of SIP UA on the device and all > applications are using the same SIP UA then how does UA handles > routing of incoming SIP requests to different applications. > E.g. co-existence of VoIP/PTT application, IM session, interactive > games with in a single device like PDA and all will use INVITE > requests to create or receive session. So if there is any incoming > INVITE then how does UA find out what is the purpose of this invite or > which application should get this INVITE for processing. I think this is one of those problems that looks worse than it is. Let us assume that you have multiple applications, and they are all using the same SIP UA. (In practice, they would usually have different UAs listening on different port numbers, which would solve the problem.) But since the applications have different purposes, they have different incoming addresses, and they distribute those addresses to their correspondents. Each correspondent contacts the right address. For instance, the VoIP application receives calls on address A, whereas the IM system receives calls on address B. Exactly how addresses A and B differ is a detailed technical problem, but not interesting in principle -- they could have different user parts, or different parameters or be distinguished in some other way. In many usage situations, the externally visible Address Of Record doesn't directly go to the UA, but rather to a proxy, and the application tells the proxy "Please send all calls to AOR A1 to my local contact address C1" But then a different application tells the proxy "Please send all calls to AOR A2 to my local contact address C2." As above, the different applications must have different local contact addresses, and so the correspondents don't get confused, there must be a different AOR for each application. Dale _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
