Asterisk ivr with billing, prepaid ivr calling system

Hello all,

I had setup asterisk IVR to call but now i want the users to verify pin for any outgoing calls (prepaid calling card)
and deduct the balance from their card.
I dont know how to do it.
need your help guys.
any reference or book for it.

It is similar to call originating using quentium+asterisk+radius for billing (prepaid calling system)

guys need your help.