asterisk users - Aug 2004 - We have thousands of U ISDN interface phones

Since the largest regional ILEC in Brazil completely stopped taking new BRI 
ISDN customers and started heavily incentiving their existing customers to 
migrate over to ADSL (regardless if what they need is voice or data), we have 
thousands of ISDN phones collecting dust.

Is there any network side U cards that will work with Asterisk, so we can turn 
those phones into useful things ? I'm sure there will be expensive stuff,
I'm
looking for an option that wouldn't cost more than US$ 100 per NT side U 
connection, no need for S conector stuff, could single port cards, or 
multiple. As this wouldn't be plugged into the PSTN directly, we don't
really
need to certify the hardware for Brazil.

On the other hand, those phones can be had for less than US$ 10 each (local 
cost), so we could grab a hundred and ship out for somebody else that can 
make use of them. I have no idea how cheap or how expensive this hardware is 
in Europe.

The phones are Teles.ISDN. There are also Teles.S0 cards (HiSax).

Regards,

Marcelo Pacheco