asterisk users - Feb 2006 - ISDN interface cards with pass-through

Hi!

Are there any multiport ISDN interface cards (PRI and BRI) which support 
pass-through in "power-off" mode. (I want to use Asterisk between the 
telco line and the existing PBX and I want "pass-through" when the
power
of the Asterisk server is switched off).

regards
klaus