[SIPForum-discussion] 180 ringing there is no SDP . so how we are able to listen the ring tone.(ringing).

[Knight Tiger]

Hi,
            When the proxy server sends a 180 Ringing message, it notifies
the caller that the callee phone is ringing. The proxy server does NOT tell
caller the media supported by the callee (This information is contained in
the SDP) . The proxy is not aware of the media capabilities of the callee.
180 Ringing is a provisional response meaning that it is optional and one
cannot send SDP on such a message.

When the caller receives the 180 Ringing message, the SIP client on the
caller's phone will play a ringing tone to intimate the user that the
callee's phone is ringing. This is generated by the caller's phone and the
callee has nothing to do with it.

It is similar to mobile phones were you call someone and you hear the same
ring back while the caller's phone has different ring tones. The telephone
exchange generates this fixed ring back to you irrespective of the ring tone
used by the callee.


Knight


On 4/25/07, Shiying Li <jackstraw.lee at gmail.com> wrote:
>
> Ringing is the default action as soon as it receive a 180 message for the
> INVITE which is sent by itself.
>
>
> On 21 Apr 2007 04:22:04 -0000, mwilliam prusty <
> callwilliam90653 at rediffmail.com> wrote:
> >
> >
> > in the 180 ringing there is no SDP i.e no media information. . so how we
> > are able to listen the ring tone.(ringing).
> >
> >
> >
> > plz answer
> >
> >
> >   [image: 2007-1-R-N-0083]<http://adworks.rediff.com/cgi-bin/AdWorks/click.cgi/www.rediff.com/signature-home.htm/1050715198@Middle5/1166323_1160412/1165498/1?PARTNER=3&OAS_QUERY=null+target=new+>
> > _______________________________________________
> > This is the SIP Forum discussion mailing list
> > TO UNSUBSCRIBE, or edit your delivery options, please visit
> > http://sipforum.org/mailman/listinfo/discussion
> > Post to the list at discussion at sipforum.org
> >
> >
>
> _______________________________________________
> This is the SIP Forum discussion mailing list
> TO UNSUBSCRIBE, or edit your delivery options, please visit
> http://sipforum.org/mailman/listinfo/discussion
> Post to the list at discussion at sipforum.org
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sipforum.org/pipermail/discussion/attachments/20070425/139633df/attachment-0002.html>