There is a number you can dial to report the crank call to the police. Don't remember it now, but it's a *--, number. Also if you have caller id, I believe that you can block private calls, so they have to call you with a viewable number present.
Also, you can answer the phone stating that the call is being recorded and record if you can.
But, definately involve the police! In this age of extreme violence these calls should not be taken lightly. Even if they are nothing, better to be embarassed than to be hurt. And the police are there to help you. I went through something like it with my ex, and after the police were involved and I was taping the calls, they finally stopped.
Also, you can answer the phone stating that the call is being recorded and record if you can.
But, definately involve the police! In this age of extreme violence these calls should not be taken lightly. Even if they are nothing, better to be embarassed than to be hurt. And the police are there to help you. I went through something like it with my ex, and after the police were involved and I was taping the calls, they finally stopped.