Media server; RE: Selection of media (m=) at MG

yes, (b) is the media server scenario.
E.g. an IMS media server, called MRFP, control via "H.248 Mp profile" (3GPP 29.333)
 

> -----Original Message-----
> From: Javi Muñoz [mailto:[email protected]] 
> Sent: Freitag, 2. Dezember 2011 13:09
> To: [email protected]
> Cc: Schwarz, Albrecht (Albrecht)
> Subject: Re: [Megaco] Selection of media (m=) at MG
> 
> Albrecht,
> 
> I complete my comment "(b)":
> 
> [ETSI TS 183 002 Clause 7.1.4]
> Access Gateways may be able to store recorded announcements 
> and shall support the generic announcement package. Generic 
> Announcement (ITU-T Rec. H.248.7 [18]): mandatory if local 
> announcements are available.
> When the announcement to be delivered is not available in the 
> gateway and cannot be autonomously retrieved by the gateway 
> from a remote repository, the MGC shall initiate a connection 
> to an external announcement machine, by temporarily adding a 
> termination into the context. Instructions to play 
> announcements are sent directly from the MGC to the server. 
> The announcement server may itself be implemented as an MG, 
> controlled using the H.248 protocol. However, this interface 
> is outside the scope of the present document. In an 
> originating MG, the context topology and the termination 
> modes shall be configured in such a way that in-band 
> information can be received from the remote side before the 
> called party's answer. This setting shall occur not later 
> than the receipt of the ACO message (or an equivalent message 
> from another signalling protocol that ISUP).
> 
> Regards,
> 
> Javi
> >
> >> well spotted, thus just a single media configuration ('Clearmode') 
> >> would be already sufficient to emulate that ISDN bearer service
> > However, two comments:
> >
> > (a) In the "call establishment phase": what must be created at the
> > MG?: would it be necessary to create a context, or would it 
> be enough 
> > to create only an ISDN termination in the null context (which would 
> > generate that tone/announcement, and then, MGC would apply a modify 
> > command to create the context for the information phase)?
> >
> > (b) I believe, the announcement do not necessarily have to 
> be recorded 
> > in AGW, but that may come from an announcement server (I guess this 
> > would also be possible for DTMF tones). Could this justify the 
> > creation of such IP termination with voice codec G.711 in the 
> > establishment phase, or that communication with the announcement 
> > server does not belong to the ISDN call and, therefore, it 
> should not 
> > be involved in its Megaco context?
> >
> > Regards,
> >
> >
> >
> >> PS
> >> Your previous email was related to ISDN-to-SIP 
> interworking at call 
> >> control level, a subject which is out of scope of MEGACO.
> >> Thus, something for SIPPING, SIP-IMPLEMENTERS, ... (or TISPAN WG3
> >> list) in my understanding.
> >>
> >>> -----Original Message-----
> >>> From: Javi Muñoz [mailto:[email protected]]
> >>> Sent: Mittwoch, 30. November 2011 18:13
> >>> To: [email protected]
> >>> Cc: Schwarz, Albrecht (Albrecht)
> >>> Subject: Re: [Megaco] Selection of media (m=) at MG
> >>>
> >>> A second comment,
> >>>
> >>> If:
> >>>>>      a) TGW: no impact, because tone/announcement 
> inserted by ISDN 
> >>>>> local exchange (terminating Q.931); TGW needs just
> >>> clearmode support
> >>>
> >>> (I agree)
> >>>
> >>> then, why?
> >>>>> E.g., MGC
> >>>>> ->   call establishment phase: IF tones/announcements THEN H.248
> >>>>> Command.req for tone/announcement control plus media 
> configuration 
> >>>>> with voice codec
> >>> That "media configuration with voice codec" (G.711) would 
> be done at 
> >>> the MeGaCo termination of the IP side of the MG, not at the 
> >>> termination of the ISDN side. If tone/announcement is 
> inserted (in 
> >>> the UNI ISDN) by this MG, the termination of the IP side 
> of the MG 
> >>> would not be used, so that "voice codec"
> >>> would not be relevant (no media would be transported over the IP 
> >>> network).
> >>>
> >>> am I wrong?
> >>>
> >>> Regards,
> >>>
> >>> Javi
> >>>
> >
> 
>