[SIPForum-discussion] Query regarding SIP 183 Session Progress

[Partha Ray]

Hi NIkas,
Yes , Callee can send it even if no sign from Calller side. But as Srinivas
mentioned , require embedes the supported itself,hence it is optional to
include both or just required or even just suported from callee side.

But here is the scenario.
If A calls B. A does support 100 rel but may or may not include it in
request, and then B includes require, then A would work accordingly
(PRACK------).  But is if A doesn't support it and B asked for it (require)
then A won't send any PRACK. But B would expect it. If B doesn't get it
with the time (timer set for it) then it would terminate the call. This
termination again would have multiple scenario (B may or may not have
responded 200 just after sending 18X with required).

BR,
Partha


On Fri, May 17, 2013 at 12:50 AM, Nikash N <nikash.n90 at gmail.com> wrote:

> Thank you Srinivas and Partha for your replies.
>
> @Partha
> In your 'Ans for second part', do you mean to say that, an entity (callee)
> can be configured such that it can send a supported and a required in
> subsequent messages even if the other entity (caller) does not send a
> supported header?
>
> Is there any relevant RFC or spec for 183? All I'm able to find is the
> Internet draft released by IETF in 2000. Has there been no updates to it
> since then?
>
> Thank you.
>
>
> On Thu, May 16, 2013 at 9:14 PM, Partha Ray <jubu.partha at gmail.com> wrote:
>
>> 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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>>
>
>
> --
> Regards
> Nikash
>
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