Re: [Sip] INVITE without SDP body.

[Christer Holmberg <christer.holmberg@lmf.ericsson.se>]

Hi,

> Thanks for your response.
> I agree but I 'm a bit confused because in the
> draft-elwell-sippping-qsig2sip-03.txt (Interworking between SIP and
> QSIG),
> it is mentioned :
>
>     If the SIP INVITE request does not contain SDP information and
> does not contain
>     either a Required header or a Supported header with option tag
> 100rel, the gateway
>     SHALL NOT issue a QSIG SETUP message and SHALL send a SIP 488 (NOT
> ACCEPTABLE HERE) response.
>
> What did I understand wrong?

I don't think you understood anything wrong :)

Specific SIP APPLICATIONS (in your case the QSIG-to-SIP interworking)
may require certain things (eg some SIP extensions, SDP in the INVITE
etc etc etc), but it is not a general SIP PROTOCOL requirement that you
must use PRACK if you don't have SDP in the INVITE.

Regards,

Christer Holmberg
Ericsson Finland




>
>
> Thanks again.
>
>
> Christer Holmberg wrote:
>
>> Hi,
>>
>> 100rel is needed only if you want to use PRACK. It has nothing to do
>> with the
>> fact if you have a SDP in the INVITE or not.
>>
>> Note, however, that if you use PRACK you may have to send the SDP
>> before you
>> send the ACK (in a PRACK), but that's another issue...
>>
>> Regards,
>>
>> Christer Holmberg
>> Ericsson Finland
>>
>>
>> Paraskevopoulos Pavlos wrote:
>>
>>
>> > Hello,
>> >
>> > I 'm trying to build a SIP gateway, and I would appreciate a little
>> > help.
>> >
>> > Think of that scenario
>> >
>> > ISDN                     GW                         SIP-EP
>> > ----------------------------------------------------------------
>> > -->SETUP                 --->INVITE(no SDP)
>> >
>> >              ALERTING<---                      180<-----
>> >              CONNECT<---                       200<-----
>> >                         ---->ACK(SDP)
>> >
>> >
>> > I want to send the INVITE request without SDP info. The SDP info
>> > will
>> > come later with the ACK.
>> > Does the INVITE request have to contain a Required or Supported
>> > header
>> > with option tag 100rel?
>> >
>> > Thanks in advance.
>> >
>> > _______________________________________________
>> > Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
>> > This list is for NEW development of the core SIP Protocol
>> > Use sip-implementors@cs.columbia.edu for questions on current sip
>> > Use sipping@ietf.org for new developments on the application of sip
>> >
>>
>>
>>

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