Hi Ram,
If the 1xx establishes an Early dialog, the Contact has to be there as it will be a part of the Dialog construction mechanism at the UAC, and will be used in mid-dialog request if any for constructing any Request before the INVITE transaction completes.
From RFC 3261 (Page 71, Sec 12.1.2 UAC Behaviour ):
The remote target MUST be set to the URI
from the Contact header field of the response.
from the Contact header field of the response.
If the 18x does not establish a dialog (i.e, to tag does not exist ), i dont think Contact is required, please correct me if i'am wrong !
The below discussion is supposedly for Dialog establishment with 18x, therefore a Contact is mandatory.
Sec 12.1.1 says that Contact is a must for responses that establishes a Dialog (also an Early Dialog, as in this case).
Thank you.
Cheers.
Simith
Ramachandran Iyer <[EMAIL PROTECTED]> wrote:
Yes,you are right that 3261 does mention a MUST, for a contact to be present in 18x.But i am still thinking, why would you want to mandate (MUST) the UAS for having a contact, may be it does not have any different contact to give at all. It may be pretty happy to be contacted at the same To: Uri present in the INV.. I do not believe or see a reason for mandating a contact here. It will be nice to hear from some1 if there is a reason to it.Rama
KrishnaKanthT 70508 <[EMAIL PROTECTED]> wrote:Hi,
It is mandatory for the 18x to have contact header when it has 100Rel.
According to rfc3262, a provisional response that is to be sent reliably MUST establish a dialog. According to section 12.1.1 of rfc3261, any response that establishes a dialog must contain a CONTACT header field.
Rgds
Krishna
>
> Message: 5
> Date: Tue, 22 Jun 2004 13:47:50 +0530
> From: <[EMAIL PROTECTED]>
> Subject: RE: [Sip-implementors] Question on 18x and PRACK
> To: <[EMAIL PROTECTED]>
> Cc: [EMAIL PROTECTED]
> Message-ID:
> <[EMAIL PROTECTED]>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Kasam,
>
> No it is not mandatory to have the contact header in 18X when it
> requires 100rel.
&a! mp;g! t;
> Yes it is MUST to retransmit a PRACK until you get a response for
> PRACK.
> Prack should be handled as any non-invite request.
>
>
> HTH,
>
> Regards,
> SReeram
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> KasammiyaPatil
> Sent: Tuesday, June 22, 2004 2:13 AM
> To: [EMAIL PROTECTED]
> Subject: [Sip-implementors] Question on 18x and PRACK
>
>
> Hi all,
>
> Is it a MUST for 18x message to have Contact header if it
> requires 100rel ?
>
> Is it a MUST to retransmit a PRACK ?
>
> Kasam Patil
> CS2K SIP Design and Development
> ESN: 351 8346 External: 919 991 8346
> Yahoo ID: kasampatil
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