[SIPForum-discussion] call-id and cseq relation -> rfc 3261 clarification help required

[Vijay Tiwari]

Hello Halit

Cseq is incremented by one in this case because we are sending re-invite to
the server and this is a new request. whenever we send new request to the
server, UAC will increment Cseq number by one.

and when we are re-transmit the request, then Cseq number will be same as
previous invite .

This is the only difference between re-invite and re-transmission of the
invite request.

Regards
vijay



On Thu, Mar 28, 2013 at 4:58 PM, SAKCA, HALIT (HALIT) <
halit.sakca at alcatel-lucent.com> wrote:

>  Dear All,
>
> Could you please help me to figure out following scenario and RFC 3261
> statement?
> A sip call with auth;
>
>    1. Agcf -> INVITE  -> scscf
>    2. Agcf <- 407  <- scscf
>    3. Agcf -> INVITE  -> scscf
>
> .
> .
> .
>
> The INVITE in 3rd has a different call-id than the INVITE in 1st,
> I see in RFC that;
>
> RFC 3261 clause 22.2 states (at the end of the clause):
>
>    When a UAC resubmits a request with its credentials after receiving a
>    401 (Unauthorized) or 407 (Proxy Authentication Required) response,
>    it MUST increment the CSeq header field value as it would normally
>    when sending an updated request.
>
> Does ‘*Incrementing Cseq*’ basically means that the *CallID remains the
> same*?
> I am wondering if it is only in case the UAC RESUBMITS a request.
> In request above we don't resubmit so we don't have to follow this rule.
> The UAC is not obliged to resubmit.
>
> Am I correct?
>
> Regards,
> Halit
>
>
>
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