Re: [Sipping] 3pcc - controller receiving invite

[Niall Murray <nmurray@xxxxxxxxxxxxxxx>]

Hello All,

My question is probably quite simple as I am new to SIP but I have a questions in relation to 3PCC best practices with SIP :http://tools.ietf.org/html/rfc3725.

In all of the examples in this document, the controller initiates the session. My query relates to the scenario whereby if a device acting as a controller receives an invite. If this called controlling device was aware of a number of local devices it wanted to use in the session I imagine that it could either parse the initial invite SDP, and send the updated or new SDP (with relevant SDP parts) to each of the respective devices e.g. m =audio is sent to speaker, whereas m=video is sent to display device. Or an alternative approach would be just to forward the initial invite SDP to all the devices and parse and edit the SDP "answer" back to the calling device. Are both of these approaches valid? Please see the flow below :


Audio / Video Device           Controller         Speaker       Display Device

           |                          |                   |                   |

           |(1) INV SDP (m=video,     |                   |                   |             

           |      m=audio )           |                   |                   |

                     |   ------------>          |                   |                   |

           |                          |2)INV SDP m=audio  |                   |

                     |                          |  ------------>    |                   |

           |                          |3)INV SDP m=video  |                   |

                     |                          |  -----------------------------------> |

           |                          |                   |                   |

                     |                          | (4) 200 OK answer1|                   |





           |                          |  (audio)          |                   |

           |                          |<------------------|                   |
                     |                          |                   |(5)200 OK answer2  |
           |                          |                   | (video)           |

           |                          |<--------------------------------------|
           |                          |                   |                   |
           |                          |                   |                   |

                     |              (6)Parsing and combining of     |                   |




                         audio/video SDP at controller   |                   |




           | 200 OK(Combined a/v SDP) |                   |                   |





           |   <------------------    |                   |                   |




           |      (7) ACK             |                   |                   |  




           |      -------------->     |                   |                   |




           |                          |         (8) ACK   |                   |  





           |                          |  -------------->  |                   |    




           |                          |                   |                   |




           |                          |       (9) ACK   ------------------->  |                   




          ====================================================================
          ==================================Media Flow========================           




          ====================================================================

Are there any known issues with this?
Thanks in advance,
Niall

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