[SIPForum-discussion] 183 Session Progress without SDP

Manish Aggarwal maaggarwal at gmail.com
Thu Apr 9 19:22:59 UTC 2009

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.


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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