"Early media" with fast connect

Paul E. Jones paulej at PACKETIZER.COM
Sat Apr 27 23:36:29 EDT 2002


"Early media" with fast connectErnst,

I think the key is "prepared to receive."  The endpoint may be prepared to receive, but it will not necessarily play the streams.

My assumption is that, if the endpoint is playing local ringback, it will do so until either:
  1) It is told not to do so any longer
  2) RTP streams arrive

However, playing RTP streams before receiving CONNECT may have some implications.  Perhaps some endpoints send RTP data that contains no real content... thus inadvertently killing the local ringback.

Whatever the resolution, I think we need to ensure that local ringback happens as long as is necessary, but that we terminate once "real" media arrives-- we do not want to clip audio.

Paul

  ----- Original Message ----- 
  From: Horvath Ernst 
  To: ITU-SG16 at echo.jf.INTEL.COM 
  Sent: Friday, April 26, 2002 7:40 AM
  Subject: "Early media" with fast connect


  Dear experts, 

  there seems to be a possible conflict with early media during call establishment using fast connect. 

  Clause 8.1.7.1 of H.323 clearly says that the calling endpoint must be prepared to receive media right away on the ports it indicated in fastStart, and that the called endpoint may start transmitting media as soon as it accepts a fastStart proposal (unless, of course, the calling endpoint indicated also "mediaWaitForConnect"). This is independent of any Progress indicator.

  Clause 8.1.7.4, on the other hand, requires that the calling endpoint provides tones like ringback locally if it did not receive a Progress indicator #1 or #8. So the calling endpoint is obliged to interrupt/ignore possible media streams from the called endpoint and replace them with its own tones. Isn't this a conflict situation?

  I would like to hear your opinion or any experience from implementations. 



  Kind Regards, 

  Ernst Horvath 
  Siemens AG 

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