[Asterisk-Users] asterisk acts as media gateway for existing pabx ?

[Jean-Louis curty]

Hi, 

I'd like to realize the following setup  traditional phones --> pbx
(non ip )  --> asterisk --- ISDN network


is it possible to set up an asterisk server in such way that it acts
as gateway between a traditionnal pbx and an isdn network ( I'm in
France ). this to let people continue with their existing pbx + phones
and enjoy voip features ?

outgoing calls:
if yes,do I need isdn card dedicated to incoming calls from pbx to
asterisk and dedicated card from pbx to outside

and what about the setup for incoming calls... the call comes in
asterisk server.. how to dispatch the call back to the pbx if it's an
extension still connected to the pbx ?

I hope it's clear enough ....

thanks 
jean-louis