[OpenSER-Users] Rewrite SDP for music of hold

[Iñaki Baz Castillo]

El Tuesday 10 July 2007 20:03:53 Christian Schlatter escribió:
> Iñaki Baz Castillo wrote:
> > Hi, I'm starting using OpenSer with Asterisk.
> >
> > In calls passing through Asterisk the caller or callee get music on hold
> > of Asterisk when is put on hold. But of course, direct calls between
> > OpenSer users don't get this music.
> >
> > I'm thinking in the posibility of detecting "on hold" reinvites (maybe
> > reading the "a=sendonly" of SDP body) and rewriting the SDP IP contact to
> > a music on hold server.
>
> You would also have to tell the music server where to send the rtp
> stream. And you'd have to keep dialog state on the proxy in order to
> capture the off-hold INVITE and tell the music server to stop sending
> media.
>
> This all leads to a sip proxy acting as a B2BUA/3PCC server which needs
> a lot of resources and is difficult to implement. I don't say it is
> impossible but adding this functionality to openser would be quite a task.
>
> Unfortunately even the IETF has no clear message on music on hold, no
> wonder sip phones normally do not support it in a standards compliant
> way. There is a draft called "SIP Service Examples" that already has 12
> revisions and that includes an example on how music on hold should be
> implemented.
>
> http://www1.tools.ietf.org/html/draft-ietf-sipping-service-examples-12#sect
>ion-2.3
>
> Previous revisions of this draft followed a 3PCC model for music on hold
> (http://tech-invite.com/Ti-sip-service-3.html), whereas revision 12 now
> implements music on hold with a call transfer.
>
> One can only hope that we will see products implementing these procedures.
>
> Pingtel seems to offer a music-on-hold server for the 3PCC model:
> http://interop.pingtel.com/#moh
>
> And SNOM phones seem to work fine together with the pingtel/sipX
> solution:
> http://sipx-wiki.calivia.com/index.php/HowTo_configure_SNOM_SIP_phone_with_
>sipX#Music_On_Hold_.28MoH.29


Thanks a lot. I see that it's not an easy task. I'll try it whena have some 
tiem and if I get something decent  I''ll tell it here.

Regards.

-- 
Iñaki Baz Castillo
ibc at in.ilimit.es