FW: [MMUSIC] Seeking input from G.726 ADPCM implementers

Tom-PT Taylor taylor at NORTELNETWORKS.COM
Tue Oct 15 08:33:09 EDT 2002

POSE Laurent FTRD/DAC/ISS wrote:
> Hello,
> could anybody can explain me why the progress indicator has been
> set to "forbidden" in the setup message? (H.225v4 §7.3.10)

When H.225v1 was standardized, the people active in that effort did not
believe it would be required.  For reasons of backward compatibility it can
not be retro-fitted in the obvious place (although it could be added at the
end of the ASN.1 for the particular message).

> when H.323 is used in VoIP trunking between 2 ISUP networks, the lack of
> this information has an impact on the selection of the called ISDN
 > terminal (for exemple : if a fax and a telephone are behind a PABX and if
> BC=3.1kHz, without the progress indicator, fax terminal can pick up the
> call instead of the telephone)

Really?  It is not at all clear to me how this would work in the called ISDN
terminal.  There is nothing I can see in the progress indicator to say
whether a call is voice or fax.  How is the progress indicator used to
achieve this?

Dr Chris Purvis -- Development Manager
ISDN Communications Ltd, The Stable Block, Ronans, Chavey Down Road
Winkfield Row, Berkshire.  RG42 6LY  ENGLAND
Phone: +44 1344 899 007
Fax:   +44 1344 899 001

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