[SIPForum-discussion] 183 Session Progress without SDP

[nitin kapoor]

hello Sunny,

UAS is not the b2bua but the proxy server is the b2bua.

And still i am not sure, with the given description. I mean as manish said
first 183 is sent for the initial invite to tell the UAC that INVITE are in
still processing. And in the attached traces, i couldn't see the reason of
disconnection to this call.

Thanks
Nitin Kapoor

2009/4/11 Sunny <guangu.he at gmail.com>

> Maybe the UAS is a B2BUA?  Hum...
>
>
> 2009/4/10 Tomasz Zieleniewski <tzieleniewski at gmail.com>
>
>> Hi All,
>>
>> I totally agree with Manish,
>> One more thing that came to my mind was that
>> gateway by sending this first 183 ASAP could assure that if for any
>> reason originating UAC on the whole sip downstream
>> path didn't receive the 100 trying response this will cause that this
>> INVITE transaction will move to Proceeding state and there would
>> no retransmissions.
>>
>> Cheers
>> - Tomasz Zieleniewski
>>
>> 2009/4/9 Manish Aggarwal <maaggarwal at gmail.com>:
>>
>> > Multiple provisional responses is allowed as per the protocol spec.
>> > This can be used to create an early dialogue.
>> >
>> > A UAS will send this, when its taking long time to process INVITE (and
>> > before sending 200 OK).
>> >
>> > Have heard of this behavior before though.
>> >
>> >
>> > -Manish
>> >
>> > On Thu, Apr 9, 2009 at 12:26 PM, nitin kapoor <nitinkapoorr at gmail.com>
>> > wrote:
>> >>
>> >> Dear All,
>> >>
>> >> We are facing one problem where we are getting two 183 session for 1
>> >> INVITE. UAC sending the INVITE to Switch and switch has forwarded the
>> same
>> >> invite to UAS. Then UAS first send the 183 Session progress without SDP
>> and
>> >> after 2 Sec its sends the another 183 Session Progress with SDP which
>> is
>> >> something i am not able to understand.
>> >>
>> >> 1) Can you please tell me on which cases UAS sends the two 183 Session
>> >> progress like this.( with SDP & without SDP)?
>> >> 2) Is this the correct behaviour?
>> >>
>> >> I checked this on RFC3261 and another sip pdf but unable to search it.
>> >>
>> >> Please find the attached Traces.
>> >>
>> >> Thanks
>> >> Nitin Kapoor
>> >>
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>> >
>> >
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>
>
>
> --
> Thanks
>
> Sunny
> --------------------------------------------------------------
> Skype:Guangwu.He
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