On Fri, 2012-07-06 at 10:53 +0530, Naarumanchi Kaushik wrote: > 1. When a user calls himself(to the same endpoint), he will get User Busy > response as his device is already busy. So a User busy response is sent > based on his device status and not based on comparision between From and To > URIs. Is this correct?
Generally, this is not correct. In most SIP systems, an incoming call for an extension will be routed to the phone even if that extension or phone is busy. And the phone will generally alert the user and give the user an opportunity to put the current call on hold and answer the new call. I believe that this is because most SIP systems are made as business phone systems, and historically business phones have had multiple lines, and thus allow users to manipulate several calls at the same time. As Paul notes, it can be difficult for the calling phone to place the early dialog on hold, as the INVITE transaction has not completed. However, it's possible that the phone could use an UPDATE to modify the SDP of the early dialog, or simply stop rendering incoming media from the dialog (without any protocol action). In general, it is rarely useful for software to make any decision based on the From and To headers, as they do not necessarily indicate unique users or UAs, and because the actual UAS may be derived from the To URI by many stages of forwarding. > 2. If call forward always is enabled for this user, and if he calls > himself, then giving priority to call forward is correct or not? Should > this also be a User Busy response? This is also an implementation decision, but I would expect in this situation that the call would be forwarded. Given that the set-forwarding action declares that calls should not be given to the extension in question, a call from that extension would be forwarded to the specified destination. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
