Asterisk and A2billing Customization

Server is prepping to act a filter to restrict abnormal activities , I need 2 customization 1) if a number is currently been dial thought the system, don't allow it to process another call to the same number until the current call is drop. 2) restrict a number that is dial more then 2 times for the day - reset restriction 12 mid night ( 1st dial ok -> 2nd dial ok -> 3rd dial Block for the day) all restriction must send a 503 code