[SIPForum-discussion] Query regarding SIP 183 Session Progress

[Partha Ray]

Hi Nikash,

Ans for first part:  Basically 'supported' is used by either side
to declare their capability. It is not mandatory but always a good practice
if the B party (in your case includes it). *And if it supports precondition
too, but does not want to use it for this session, does it need to specify
that in the supported header?  Ans: If a user doesn't want to use this
capability for a session , you need to configure the entity for that not to
include** supported header. You can't make it per session basis. This is a
global setting for all entities.(Either for all session or not
 supported at all). You can't have combination of both at the same time.*
*
*
Ans for second part: Yes callee can do it if configured accordingly. Infact
it is the best practice to include it if supported(declaring your
capability).  Callee can send 'required': in any subsequent provisional
response. (18X).

BR,
Partha


On Thu, May 16, 2013 at 7:05 AM, Nikash N <nikash.n90 at gmail.com> wrote:

> Hi
>
> I've a scenario here which I'd like to discuss.
>
> Caller sends an INVITE with "100rel, timer, precondition" in supported
> header. The Callee responds with a 100 Trying and then a 183 Session
> Progress, in which the require header contains "100rel". Is there a
> necessity for the 183 to have "100rel" in supported header too? And if it
> supports precondition too, but does not want to use it for this session,
> does it need to specify that in the supported header?
>
> Alternatively in a different scenario, if an INVITE does not contain a
> supported or a require header, can the callee respond back with a
> "supported" header containing "100rel". And then, if the caller supports
> 100rel too, and wants to use it, in what SIP message can he send a
> "require" header after these exchanges?
>
> Thank you.
>
> --
> Regards
> Nikash
>
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