[SIPForum-discussion] Require: timer in the INVITE

[Abhisek Acharya]

hey mate..

First of all lets talk about Supported and Require headers,..These headers
are there to denote the support  for fee SIP extensions like
 PRACK,Session-Refresher Mechanism (RFC 4028) ,SIP Preconditions etc.


For PRACK Supported :100 rel is used and for Refrehser Supported :timer is
used.Lets assume A calls B and A adds a Supported header with timer that
means it supports this mechanism but Session-Refresher will only kick off
if B party sends a Require header with  timer .

But the trick is calling party is always discouraged to send Require:100
rel in initial INVITE as this means Session-Refresher is a MUST for calling
party and this might lead to call fail as the called party may or may not
support this mechanism.

And If called party SIP stack does not support the RFC defined error
response is 420 which is your SBC is sending....


NOTE:--The carrer should only send RE-INVITE with Require if you have sent
200OK response with Require timer ..which means you have agreed to
partcipate in a Refresher mechanism.

If not the carrier should not add  Require rather it should add
Supported:timer which will not create the problem



















On Tue, Jul 2, 2013 at 10:06 AM, Zuñiga, Guillermo <
Guillermo.Zuniga at cwpanama.com> wrote:

>  Hi Fellows.****
>
> ** **
>
> I am having a issue with some calls are negotiating to a fax call with t38
> when I am getting the Re-Invite(t38)****
>
> I am seeing that invite have the following Header Requiere: timer. And my
> SBC is rejecting with 420 bad extension( I found the way to solve this in
> my SBC).****
>
> But really I would like to know if is correct that Carriers send me the
> Re-invite with this Header when we are negotiating the fax call?****
>
> What is used this header?****
>
> There is any relationship between Requiere Timer and the others
> Headers(Supported: timer, Session-Expires?) that are coming in the
> Re-Invite?****
>
> ** **
>
> Thanks for help me understand better this headers.****
>
> ** **
>
> Regards****
>
> Guillermo****
>
> ** **
>
>
>
> Guillermo ZunigaEspecialista de Soporte TécnicoGerencia de Soporte Técnico
>
> Tel:+507 263-6671Cel:+507 6670-0481 Fax:+507 265-3295Email:
> Guillermo.Zuniga at cwpanama.com
>
>  <http://www.cwpanama.com>
>
> <http://www.cwpanama.com>
>
>
>
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>
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