Green Number <-> ISDN <-> Asterisk


my company uses a green number that is routed on an ISDN line (our telephony company offer us this service). Is there a way on Asterisk to intercept Caller ID and immediately hangup the calling without answering and without paying connection fee, if the Caller ID is blacklisted ?

We would like to filter an ISDN Connection where there are calls directed to a green number.

I hope that I explained the problem using my poor english !!!

Best regards.