Question about configuration of asterisk

I am trying to use asteriskt as a gateway, which sit between PSTN and the old PBX. The asterisk connect with PSTN and PBX through BRI ISDN card.
I have read the book “the future of Telephony”,but there is nothing about the configuration for ISDN telephon.
anyone can help? which file and how should I configure ?

Have a look at here: