[Freeswitch-users] Multiple 183 SDP Change Codecs - allowed?

Kristian Kielhofner kris at kriskinc.com
Tue Jul 3 17:26:48 MSD 2012


Avi,

  Multiple 18x responses that change the SDP are allowed.  I can't
find the specific document text now but as a random guy on the
internet (for whatever that's worth) I'm certain it is allowed.

  A re-INVITE can't be sent from either side until the dialog has been
established (200+ACK).  In a case where the UAC (caller) would like to
update the session before it is established method UPDATE must be
used.

On Tue, Jul 3, 2012 at 1:04 AM, Avi Marcus <avi at avimarcus.net> wrote:
> Are multiple 183s from the endpoint that changes the SDP allowed? I'm under
> the impression this is broken, similar to
> http://wiki.freeswitch.org/wiki/NDLB#NDLB-allow-nondup-sdp
> ... which is why when the codec changes, FS freaks out and cancels the call
> because of codec negotiation error.
> Does that NDLB flag allow this, too?
>
> First has: audio 10116 RTP/AVP 0 101 13
> Second has:  audio 49020 RTP/AVP 8 13 101
> PCAP: http://ge.tt/7MpyBwJ
>
> Can someone point me to the specific RFC so I can tell the supplier to fix
> it?
> And just curious.. what would make this allowed? A re-INVITE..?
>
> -Avi
>
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-- 
Kristian Kielhofner



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