RTEMS and ISDN

[muellaue at via.at (Wolfgang Müllauer)]

Hello all,

I am currently planning to write an ISDN Stack for RTEMS, as 
we try to use PCs with RTEMS 4.0 als a platform for IVR 
(interactive voice response) systems.

I have the following idea: 

We are currently using Dialogic Voice boards that cost more than 
800USD per analog interface. These boards have one or more DSPs
and a general Purpose CPU for managing the interface, doing 
DTMF decoding, playing soundes etc.

IMHO it should be possible to use a dumb $90 PCI-ISDN adapter for 
speech processing if it is possible to configure a cyclic task
that is scheduled every 125 us (8000 Hz) for managing the basic voice
processing like conferencing, playing sounds  etc. 
As current Motherboards have up to 5 PCI slots, we could configure 
an IVR with 10 ISDN Voice channels and maybe VoIP Support at a fraction
of the costs of general purpose IVR systems.

So my questions:

Has anybody experience with tasks that are scheduled every 125 us - does
that work under everyday conditions?

Can I realize such a system with a Pentium-II-450 PC?

Has anybody written an ISDN Protocol Stack for RTEMS?

Does anybody do any signal processing in RTEMS?


all hints are welcome!


Wolfgang Muellauer
ASC Datenservice
Vienna / Austria (Europe)
(muellaue at via.at)