________________________________________ From: [email protected] [[email protected]] On Behalf Of Premalatha Kuppan [[email protected]] Thanks for the valuable comments.
Then during outgoing call, how can both devices participate such that audio should be from/to one device and video from/to other device ? ________________________________________ As you know, there is no completely standardized way to do this. It is an area of active research in the SIPCORE working group. Generally speaking, GRUU is not centrally significant to solving the problem. Of course, an incoming call can be forked to several UAs at the same time, and several UAs may send 200 responses. But the calling UA will (in all ordinary circumstances) select one of the 200 responses to continue the call and will immediately terminate the dialogs created by the other 200s. One technique is to use a B2BUA, such as a conference server, to maintain dialogs to all of the UAs that you want to participate in the call, and to route the media appropriately. Another technique is to have one UA answer the call and pretend to the calling UA that it has all the media facilities needed. The answering UA can then place a call to the "secondary" UA (e.g., the laptop that displays the video), configuring that dialog to only have video media. After that, the answering UA can either relay the media arriving from the remote UA to the secondary UA, or it can use 3rd party call control techniques to get the remote UA to send the correct media (e.g., video) directly to the secondary UA. Some complication arises when the answering UA attempts to contact the secondary UA. One technique is for the answering UA to know the secondary UA's contact URI. A better solution is for it to know its GRUU, which generally stays the same over time, even if the secondary UA's network location changes. Another possibility is for the answering UA to place a call to its own AOR, specifying caller preferences and SDP for the media that it needs displayed on its behalf (e.g., video). The call will only ring on UAs capable of handling the specified media, and you can cause the one you desire to use to answer. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
