Since the SDPs are the same, I assume that the responses are from the
same UAS, and carry the same to-tag. You didn't say if the responses
were reliable provisionals, so I will assume they were not. (The answer
is different if they are.)
In that case the answer is that this is entirely legal.
The recommended behavior for a UAC is to only generate local ringback if
a 180 has been received AND no inband media is being received. But its
really an implementation decision how to manage this to provide the best
user experience. The UAC isn't *wrong*, its just not a very good
implementation.
Paul
Brocha Strous wrote:
> Is it allowed for a UAS to send first a 183 with an SDP and then send a
> 180 also with an SDP (same as the 183)?
>
> It seems that some UAC's in this case end up hearing a double ring (one
> real one from the media stream and one locally generated. Is the UAS
> doing something wrong or UAC?
>
> Thanks,
>
> Brocha
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