[SIPForum-discussion] Need help about RFC 3262

jk j.koshiko at east.ntt.co.jp
Wed Jul 11 07:46:28 UTC 2007

"Reliable response" means a response which include Require header with 100rel. 
UAS can put "Require: 100rel" to provisional responses in order to ask UAC
to send PRACK for the provisional response.

Session description is independent of whether a response is reliable or not.
Reliable responses may or may not include SDP.

Hope this help.

> Hi,All
>   At the end of '3 UAS Behavior' RFC 3262, 
>    The UAS MAY send a final response to the initial request before
>    having received PRACKs for all unacknowledged reliable provisional
>    responses, unless the final response is 2xx and any of the
>    unacknowledged reliable provisional responses contained a session
>    description.  In that case, it MUST NOT send a final response until
>    those provisional responses are acknowledged.  If the UAS does send a
>    final response when reliable responses are still unacknowledged, it
>    SHOULD NOT continue to retransmit the unacknowledged reliable
>    provisional responses, but it MUST be prepared to process PRACK
>    requests for those outstanding responses.
> Can some one tell me, the red words 'reliable responses ' mean 'provisional responses contained a session description' or 'provisional responses without a session description'.
> thanks & regards,
> Minglu
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