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List:       asterisk-dev
Subject:    Re: [asterisk-dev] mISDN clear channel
From:       Klaus Darilion <klaus.mailinglists () pernau ! at>
Date:       2008-04-24 7:49:50
Message-ID: 48103B9E.7090004 () pernau ! at
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Kévin Bouchard schrieb:
> 
> Hi,
> 
> 
> I need to setup an H.324M call that is bridged through Asterisk over 
> mISDN (DB410P). In order to do that, some bits need to be setup in Q.931 
> setup message. I have hardcoded the Low Layer compatibility (UL1) to be 
> set to H.223 & H.245 signaling properly. I use the "Unrestricted 
> digital" option of mISDN as well. However, the H.223 stream on the other 
> end is neither understand by the ISDN terminal on the NT side. I suspect 
> Asterisk not to set the ISDN b-channel to "clear" or without compression 
> to pass a byte stream other than ULAW or ALAW voice data on it.

Asterisk can not handle clear channels - the digital data is "tunneled" 
through Asterisk using either A or U law. Often there is a problem if 
the local channel used by h324m_call is U law, and ISDN is A law. 
(verify with "show channel ..." - there you should see the used codec)

If mISDN uses ALAW, try to remove AST_FORMAT_ULAW from app_h324m.c.

regards
klaus

> 
> If this mailing list is not the proper place to discuss mISDN issues, 
> can someone point me to the right place to discuss them?
> 
> Is this supported in chan_misdn?
> 
> Thanks,
> 
> 
> Kevin.
> 
> 
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