i think we should teach a computer to subtract a out going call with its prevous number. although i only looked at the first data set but look a the screen shot i have uploaded. these phone numbers have a set simmular numbers. some made from the same caller have the same phone number but diffrent area code. others are a set addtion from the previous numbers. this way we can identify them it should be too costly since the untied state is currently montoring all phone calls i think since the younger Bush.