[SIPForum-discussion] Does anybody know the reason why the calling get connected while no ringing in a

[erol turac]

The mandatory messages to establish a session are invite, 200 OK and ACK.
So, you will not hear any ringback tone unless local EP takes any
provisional response, like 100 Trying-180 Ringing (can be generated by any
hop) and 183 Session Progress(end to end).

Rgrds,


On 9/2/07, 大 泥人 <qinglan_zeng at hotmail.com> wrote:
>
>  All,
>
> Does anybody know the reason why the calling get connected while no
> ringing in advance?
>
>
>
> Thanks
>
> With Best Regards
>
> Daniel Zeng
>
>  ------------------------------
> From:  *<harini.dhanasekaran at wipro.com>*
> To:  *<vijaycec at yahoo.co.in>, <discussion at sipforum.org>*
> Subject:  *Re: [SIPForum-discussion] Response messages & Protocol*
> Date:  *Sun, 2 Sep 2007 10:13:49 +0530*
>
>     Hi Vijay,
>
>  Here is the ans for ur first question: diff between 486 and 600
> response...
>
>  Suppose if user A is trying to call user B, then 486 response message is
> sent by user B in the following situation:
>    If user B's end system was contacted successfully, but the user B is
> currently not willing or busy or unable   to take additional calls at this
> end system.
>
>  600 response message is sent by user B during the following situation:
>     The user B could be available elsewhere, such as through a voice mail
> service (if user B has registered for it). 600 (Busy Everywhere) response
> message is sent if the client knows that no other end system(such as voice
> mail service or call forward to another end system service) will be able to
> accept this call.
>
>  otherwise 486 response message is sent...
>
>  in both the cases, user A would hear busy tone on his/her end system...
>
>  for the call flows refer:
> http://www.tech-invite.com/Ti-sip-service-8.html
>
>  Thank you,
>  Regards,
>  Harini Dhanasekaran.
>
>  ------------------------------
> *From:* discussion-bounces at sipforum.org on behalf of Vijay T
> *Sent:* Sat 9/1/2007 11:37 PM
> *To:* discussion at sipforum.org
> *Subject:* [SIPForum-discussion] Response messages & Protocol
>
>   Dear ALL
>      1.What is the difference between 486-Busy Here and 600-Busy
> Everywhere Response messages....Please tell me some examples..
>
>      2.In SIP call flow when TCP come into picture and when it'll be
> changed from UDP to TCP??explain me with some examples...
>
> Thanks & Regards
> Vijay
>
>
>  ------------------------------
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-- 
Erol Turaç
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