Does your phone have a caller number?  OUrs has none and to have it installed there would an additional payment.  In the middle of the night our phone will just ring anytime and we picked it up there’s no one at the other end.  My cousin in Maryland also experience the same thing that i even joked with her that maybe she is the one calling us here.  But it’s not.  Anyway i told about the solution to unknown calls the Phone Number Investigator. she is so excited abut it and will try it the next time her phone rings and still no one at the other side.