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List:       ooh323c-devel
Subject:    Re: [ooh323c-devel] ooh323 q931 signalling problem
From:       "Avin Patel" <apatel () obj-sys ! com>
Date:       2006-06-08 22:02:36
Message-ID: GDELLOOFNOHDINDMJPOOOELNFCAA.apatel () obj-sys ! com
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Hi Mortex,

Thanks for detail. That explains what you asking for.

> not exactly waht I mean. I will try to explain in more deatil.
>
> Some background
> ---------------------
> Based on this document
> http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186
> a0080094c33.shtml (and many others) we have 3 sceanrios:
>  A. We have end-to-end ISDN communnication with no VoIP
> internetworking. Not interesting in this, no Asterisk ;)
>  B. We have full H.323 - H.323 communication. In this case I
> think there will be no prboblem with let's call it "fake
> ring-back tone", because when the other side sends ALERTING
> message it itselfs rings (no additional establishment needed). In
> this case there is no need of IE Progress-Indicator.
>  C. We have H323-PSTN Internetworking scenario - OUR SCENARIO!!.
> What happens here? We have a termination GW which speeks H323
> with VoIP network and ISDN(CAS) with the PSTN network. Let's this
> GW be Asterisk+ooh323 with FXO card. We must sinchro all of this.
> How to do this when call establisment with PSTN side is "slower"
> then call establisment in VoIP side and "fake ring-back tones"
> will appear during this delay difference?
> Simple: Asterisk will tell the H323 device (the caller) to wait
> to receive the announcement cut-through in the voice band from
> the PSTN network.
> When Asterisk send to H323 Phone Alerting message with IE:
> Progress-Indicator with value 8 or 3 the H323 Phone will not
> generate local ring at all, nevertheless it has received the
> Alerting message. It will wait to receive the ring-tone in band!!
> The PI DOES NOT tell the H323 device to generate ring, busy or
> other tones! It is just a signal to H323 device to wait for in
> band announcemnts.
> So my patch currently tells the phone not to ring and have no
> sense if the ooh323 channel don't send in the RTP channel the
> ring tone and whatever announcment is generated from PSTN side.
>
> If ooh323 opens the RTP channel after sending the Alerting
> message with PI=8 or PI=3 then the PSTN will send in-band the
> ring-back tone and the caller will hear this tone.
> ---------------------------------------------------------------------
>
> What I propose:
> 1. We should make possible to enable/disable the use of
> Progress-Indicator and its value for each context. For ex. in
> ooh323.conf. In this way the user will have control over B and C scenario.

Sounds good.

> 2. Make ooh323 check whether PI is ebabled and if so include it
> in the  ALERTING message as Information Element and opens the
> channel for receiving/transmitting RTP after ALERTING is sent.

So problem exist here?
So the problem is you don't know,
How to propose RTP channel for inband annocument, i.e. How to get ip, port &
codec to use for inband-announcement RTP channel?
or
Where to change code for opening the RTP channel, And you alreay know the
ip, port & codec to use for inband-announcement channel ?

Regards,
Avin Patel
Objective Systems, Inc.




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