Re: Selection of media (m=) at MG

Hello Arindam,


El 30/11/2011 21:20, Bhattacharjee, Arindam (Arindam) escribió:
> Hi Javi,
> + call establishment phase: H.248 Command.req for tone/announcement
> control plus media configuration with voice codec
>> You can do that by using reservevalue =ON in Local control and send SDP offer for both G711 and ClearMode.
>> Thus AGW should be able to encode/decode g711 and reserves resource for clearmode.

I understand you mean that I use:

m=audio <puerto> RTP/AVP <PT_dinámico> 0 [8]
a=rtpmap:<PT_dinámico> CLEARMODE/8000


But, how may we indicate to the MG that it uses G.711, and it only 
reserves resources for the CLEARMODE?

Regards,

Javi

> + information phase: H.248 Command.req for modification of the media
> configuration towards CLEARMODE
>> in this phase MGC may send reservevalue =OFF with SDP ClearMode only, releasing G711 resource.
> -Arindam
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Javi Muñoz
> Sent: Wednesday, November 30, 2011 1:31 PM
> To: [email protected]
> Subject: Re: [Megaco] Selection of media (m=) at MG
>
> An aditional comment,
>
> if, as we said, we admit the following behavior:
>
> + call establishment phase: H.248 Command.req for tone/announcement
> control plus media configuration with voice codec
> + information phase: H.248 Command.req for modification of the media
> configuration towards CLEARMODE
>
>
> The following could happen:
>
> 1º Call starts and command.req for tone/announcement is applied.
>
> 2º When MGC needs to change to the information phase, the MG responds it
> does not support the CLEARMODE due to insufficient resources (MGC may
> audit the MG before the call to check it supports CLEARMODE, but MGC can
> not know how its resources will change during the call).
>
> In that case, it would not be possible to continue a call that has
> already begun, which should not happen. The SDP description should
> ensure to the MGC that the MG reserves the resources needed by the call
> prior to the establishment of it.
>
> If this is true, it would not be valid to use the modify command between
> the establishment and information phases.
>
> Regards,
>
> Javi
>
>
> El 30/11/2011 18:44, Javi Muñoz escribió:
>>> 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
>>>>
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