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

[Kristian Kielhofner]

That's pretty nasty of voxbeam to do...  Considering they return the
first 183 less than one second after the initial INVITE I'd say it's
very likely they're providing false ringback and/or FAS (false answer
supervision).  Meanwhile the actual ringback comes over two seconds
later with PCMA.  That's shady and if I were you I'd switch carriers
just on principle.

However, as I said before they're not doing anything that's not
allowed by the various specifications although FAS is considered by
many as fraud.

What are your codec settings like?  Perhaps FS is rejecting PCMA
because you're not allowing it?

On Tue, Jul 3, 2012 at 9:38 AM, Avi Marcus <avi at avimarcus.net> wrote:
> If so.. which I think is not.. is this a bug then in FS?
>
> http://pastebin.freeswitch.org/19423
> You see from the first SDP that PCMU and PCMA were both options.
> Then for the next SDP FreeSWITCH was only considering PCMU which was the one
> that got chosen by the first SDP.
>
> Voxbeam claims it's not their fault.. is it?
>
> -Avi
>
>
>
> On Tue, Jul 3, 2012 at 4:26 PM, Kristian Kielhofner <kris at kriskinc.com>
> wrote:
>>
>> 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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>>
>> 
>> 
>>
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>
>
>
> _________________________________________________________________________
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>
> 
> 
>
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>
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>
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-- 
Kristian Kielhofner